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.

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.

Effect of Residence Time on Hydrothermal Carbonization of Corn Cob Residual

Directory of Open Access Journals (Sweden)

Lei Zhang

2015-05-01

Full Text Available Hydrothermal carbonization is a promising technique for conversion of industrial waste into valuable products. Producing hydrochar from corn cob residual (CCR in a cost-effective way is key, from an economic standpoint. For this purpose, the effect of residence time in the range of 0.5 to 6 h was studied under the optimal temperature of 250 °C. Results showed that the higher heating value (HHV of hydrochar increased approximately 40% in comparison to that of the raw material; however, prolonging the residence time beyond 0.5 h had a negligible effect on the HHV increase. Chemical compositions and H/C and O/C ratios of hydrochars revealed a minimal effect of longer residence time. Furthermore, thermogravimetric and derivative thermogravimetric analysis (TG/DTG, Fourier transform infrared spectroscopy (FTIR, and X-ray diffraction (XRD analysis of hydrochars also verified that the pyrolysis behavior and chemical structure of hydrochars with various residence times were similar.

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

A new time-space accounting scheme to predict stream water residence time and hydrograph source components at the watershed scale

Science.gov (United States)

Takahiro Sayama; Jeffrey J. McDonnell

2009-01-01

Hydrograph source components and stream water residence time are fundamental behavioral descriptors of watersheds but, as yet, are poorly represented in most rainfall-runoff models. We present a new time-space accounting scheme (T-SAS) to simulate the pre-event and event water fractions, mean residence time, and spatial source of streamflow at the watershed scale. We...

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.)

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.

Seasonal change of residence time in spring water and groundwater at a mountainous headwater catchment

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Nagano, Kosuke; Tsujimura, Maki; Onda, Yuichi; Iwagami, Sho; Sakakibara, Koichi; Sato, Yutaro

2017-04-01

Determination of water age in headwater is important to consider water pathway, source and storage in the catchment. Previous studies showed that groundwater residence time changes seasonally. These studies reported that mean residence time of water in dry season tends to be longer than that in rainy season, and it becomes shorter as precipitation and discharge amount increases. However, there are few studies to clarify factors causing seasonal change in mean residence time in spring water and groundwater based on observed data. Therefore, this study aims to reveal the relationship between mean residence time and groundwater flow system using SFconcentration in spring and 10 minutes interval hydrological data such as discharge volume, groundwater level and precipitation amount in a headwater catchment in Fukushima, Japan. The SF6 concentration data in spring water observed from April 2015 to November 2016 shows the mean residence time of springs ranged from zero to 14 years. We also observed a clear negative correlation between discharge rate and residence time in the spring. The residence time in shallow groundwater in rainy season was younger as compared with that in low rainfall period. Therefore, the shallow groundwater with young residence time seems to contribute to the spring in rainy season, causing shorter residence time. Additionally, the residence time of groundwater ranged from 3 to 5 years even in low rainfall period. The residence time in high groundwater table level in ridge was older as compared with that in low groundwater table level. These suggest that the contribution of groundwater with older age in the ridge becomes dominant in the low discharge.

Working time of neurosurgical residents in Europe--results of a multinational survey.

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Stienen, Martin N; Netuka, David; Demetriades, Andreas K; Ringel, Florian; Gautschi, Oliver P; Gempt, Jens; Kuhlen, Dominique; Schaller, Karl

2016-01-01

The introduction of the European Working Time directive 2003/88/EC has led to a reduction of the working hours with distinct impact on the clinical and surgical activity of neurosurgical residents in training. A survey was performed among European neurosurgical residents between 06/2014 and 03/2015. Multiple logistic regression was used to assess the relationship between responder-specific variables (e.g., age, gender, country, postgraduate year (PGY)) and outcome (e.g., working time). A total of 652 responses were collected, of which n = 532 responses were taken into consideration. In total, 17.5, 22.1, 29.5, 19.5, 5.9, and 5.5 % of European residents indicated to work 80 h/week, respectively. Residents from France and Turkey (OR 4.72, 95 % CI 1.29-17.17, p = 0.019) and Germany (OR 2.06, 95 % CI 1.15-3.67, p = 0.014) were more likely to work >60 h/week than residents from other European countries. In total, 29 % of European residents were satisfied with their current working time, 11.3 % indicated to prefer reduced working time. More than half (55 %) would prefer to work more hours/week if this would improve their clinical education. Residents that rated their operative exposure as insufficient were 2.3 times as likely as others to be willing to work more hours (OR 2.32, 95 % CI 1.47-3.70, p 50 % of his/her working time in the operating room. By contrast, 77.4 % indicate to devote >25 % of their daily working time to administrative work. For every advanced PGY, the likelihood to spend >50 % of the working time in the OR increases by 19 % (OR 1.19, 95 % CI 1.02-1.40, p = 0.024) and the likelihood to spend >50 % of the working time with administrative work decreases by 18 % (OR 0.84, 95 % CI 0.76-0.94, p = 0.002). The results of this survey on >500 European neurosurgical residents clearly prove that less than 40 % conform with the 48-h week as claimed by the WTD2003/88/EC. Still, more than half of them would chose to work

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 → ∞

Effect of viscosity on tear drainage and ocular residence time.

Science.gov (United States)

Zhu, Heng; Chauhan, Anuj

2008-08-01

An increase in residence time of dry eye medications including artificial tears will likely enhance therapeutic benefits. The drainage rates and the residence time of eye drops depend on the viscosity of the instilled fluids. However, a quantitative understanding of the dependence of drainage rates and the residence time on viscosity is lacking. The current study aims to develop a mathematical model for the drainage of Newtonian fluids and also for power-law non-Newtonian fluids of different viscosities. This study is an extension of our previous study on the mathematical model of tear drainage. The tear drainage model is modified to describe the drainage of Newtonian fluids with viscosities higher than the tear viscosity and power-law non-Newtonian fluids with rheological parameters obtained from fitting experimental data in literature. The drainage rate through canaliculi was derived from the modified drainage model and was incorporated into a tear mass balance to calculate the transients of total solute quantity in ocular fluids and the bioavailability of instilled drugs. For Newtonian fluids, increasing the viscosity does not affect the drainage rate unless the viscosity exceeds a critical value of about 4.4 cp. The viscosity has a maximum impact on drainage rate around a value of about 100 cp. The trends are similar for shear thinning power law fluids. The transients of total solute quantity, and the residence time agrees at least qualitatively with experimental studies. A mathematical model has been developed for the drainage of Newtonian fluids and power-law fluids through canaliculi. The model can quantitatively explain different experimental observations on the effect of viscosity on the residence of instilled fluids on the ocular surface. The current study is helpful for understanding the mechanism of fluid drainage from the ocular surface and for improving the design of dry eye treatments.

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

Effect of Resident Involvement on Operative Time and Operating Room Staffing Costs.

Science.gov (United States)

Allen, Robert William; Pruitt, Mark; Taaffe, Kevin M

The operating room (OR) is a major driver of hospital costs; therefore, operative time is an expensive resource. The training of surgical residents must include time spent in the OR, but that experience comes with a cost to the surgeon and hospital. The objective of this article is to determine the effect of surgical resident involvement in the OR on operative time and subsequent hospital labor costs. The Kruskal-Wallis statistical test is used to determine whether or not there is a difference in operative times between 2 groups of cases (with residents and without residents). This difference leads to an increased cost in associated hospital labor costs for the group with the longer operative time. Cases were performed at Greenville Memorial Hospital. Greenville Memorial Hospital is part of the larger healthcare system, Greenville Health System, located in Greenville, SC and is a level 1 trauma center with up to 33 staffed ORs. A total of 84,997 cases were performed at the partnering hospital between January 1st, 2011 and July 31st, 2015. Cases were only chosen for analysis if there was only one CPT code associated with the case and there were more than 5 observations for each group being studied. This article presents a comprehensive retrospective analysis of 29,134 cases covering 246 procedures. The analysis shows that 45 procedures took significantly longer with a resident present in the room. The average increase in operative time was 4.8 minutes and the cost per minute of extra operative time was determined to be $9.57 per minute. OR labor costs at the partnering hospital was found to be $2,257,433, or $492,889 per year. Knowing the affect on operative time and OR costs allows managers to make smart decisions when considering alternative educational and training techniques. In addition, knowing the connection between residents in the room and surgical duration could help provide better estimates of surgical time in the future and increase the predictability of

Effect of protected research time on ABSITE scores during general surgery residency.

Science.gov (United States)

Orkin, Bruce A; Poirier, Jennifer; Kowal-Vern, Areta; Chan, Edie; Ohara, Karen; Mendoza, Brian

2018-02-01

Objective - To determine whether residents with one or more years of dedicated research time (Research Residents, RR) improved their ABSITE scores compared to those without (Non-Research Residents, N-RR). A retrospective review of general surgery residents' ABSITE scores from 1995 to 2016 was performed. RR were compared to N-RR. Additional analysis of At Risk (AR) v Not At Risk residents (NAR) (35th percentile as PGY1-2) was also performed. Cohort - 147 residents (34 RR and 113 N-RR). There were no differences in initial ABSITE scores (p = 0.47). By definition, the AR group had lower scores than NAR. Overall, post-research RR v PGY-4 N-RR scores did not differ (p = 0.84). Only the AR residents improved their scores (p = 0.0009 v NAR p = 0.42), regardless of research group (p = 0.70). Protected research time did not improve residents' ABSITE scores, regardless of initial scores. At Risk residents improved regardless of research group status. Copyright © 2017 Elsevier Inc. All rights reserved.

Single molecule diffusion and the solution of the spherically symmetric residence time equation.

Science.gov (United States)

Agmon, Noam

2011-06-16

The residence time of a single dye molecule diffusing within a laser spot is propotional to the total number of photons emitted by it. With this application in mind, we solve the spherically symmetric "residence time equation" (RTE) to obtain the solution for the Laplace transform of the mean residence time (MRT) within a d-dimensional ball, as a function of the initial location of the particle and the observation time. The solutions for initial conditions of potential experimental interest, starting in the center, on the surface or uniformly within the ball, are explicitly presented. Special cases for dimensions 1, 2, and 3 are obtained, which can be Laplace inverted analytically for d = 1 and 3. In addition, the analytic short- and long-time asymptotic behaviors of the MRT are derived and compared with the exact solutions for d = 1, 2, and 3. As a demonstration of the simplification afforded by the RTE, the Appendix obtains the residence time distribution by solving the Feynman-Kac equation, from which the MRT is obtained by differentiation. Single-molecule diffusion experiments could be devised to test the results for the MRT presented in this work. © 2011 American Chemical Society

Residence times in a hypersaline lagoon: Using salinity as a tracer

Science.gov (United States)

Mudge, Stephen M.; Icely, John D.; Newton, Alice

2008-04-01

Generally the waters of the Ria Formosa Lagoon, Portugal have a short residence time, in the order of 0.5 days (Tett, P., Gilpin, L., Svendsen, H., Erlandsson, C.P., Larsson, U., Kratzer, S., Fouilland, E., Janzen, C., Lee, J., Grenz, C., Newton, A., Ferreira, J.G., Fernandes, T., Scory, S., 2003. Eutrophication and some European waters of restricted exchange. Continental Shelf Research 23, 1635-1671). This estimation is based on the measurements of currents and the modelling of water exchange at the outlets to the ocean. However, observations of the temperature and salinity in the inner channels imply that residence time is greater in these regions of the lagoon. To resolve this apparent contradiction, spatial measurements of the temperature and salinity were made with a meter for conductivity, temperature and depth along the principal channels of the western portion of the lagoon, with a sampling frequency of two per second. Evaporation rates of 5.4 mm day -1 were measured in a salt extraction pond adjacent to the lagoon and used to determine the residence time through salinity differences with the incoming seawater. In June 2004, the water flooding in from the ocean had an average salinity of 36.07 which contrasted with a maximum of 37.82 at mid ebb on a spring tide, corresponding to a residence time of >7 days; the mean residence time was 2.4 days. As the tide flooded into the channels, the existing water was advected back into the lagoon. Although there was a small amount of mixing with water from another inlet, the water body from the inner lagoon essentially remained distinct with respect to temperature and salinity characteristics. The residence time of the water was further prolonged at the junction between the main channels, where distinct boundaries were observed between the different water masses. As the water ebbed out, the shallow Western Channel was essentially isolated from the rest of the outer lagoon, and the water from this channel was forced

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

Influence of temperature on patch residence time in parasitoids: physiological and behavioural mechanisms

Science.gov (United States)

Moiroux, Joffrey; Abram, Paul K.; Louâpre, Philippe; Barrette, Maryse; Brodeur, Jacques; Boivin, Guy

2016-04-01

Patch time allocation has received much attention in the context of optimal foraging theory, including the effect of environmental variables. We investigated the direct role of temperature on patch time allocation by parasitoids through physiological and behavioural mechanisms and its indirect role via changes in sex allocation and behavioural defences of the hosts. We compared the influence of foraging temperature on patch residence time between an egg parasitoid, Trichogramma euproctidis, and an aphid parasitoid, Aphidius ervi. The latter attacks hosts that are able to actively defend themselves, and may thus indirectly influence patch time allocation of the parasitoid. Patch residence time decreased with an increase in temperature in both species. The increased activity levels with warming, as evidenced by the increase in walking speed, partially explained these variations, but other mechanisms were involved. In T. euproctidis, the ability to externally discriminate parasitised hosts decreased at low temperature, resulting in a longer patch residence time. Changes in sex allocation with temperature did not explain changes in patch time allocation in this species. For A. ervi, we observed that aphids frequently escaped at intermediate temperature and defended themselves aggressively at high temperature, but displayed few defence mechanisms at low temperature. These defensive behaviours resulted in a decreased patch residence time for the parasitoid and partly explained the fact that A. ervi remained for a shorter time at the intermediate and high temperatures than at the lowest temperature. Our results suggest that global warming may affect host-parasitoid interactions through complex mechanisms including both direct and indirect effects on parasitoid patch time allocation.

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.

Steady And Unsteady Lumped-Parameter Models For Determination of Groundwater Residence Time Distribution

International Nuclear Information System (INIS)

Oezyurt, N.N.

2002-01-01

Groundwater's residence time distribution is an important information to identify the transport mechanism in aquifer systems. In the absence or scarcity of geometric, hydraulic and geohydrologic data needed to describe a flow system, lumped parameter models, that handle the flow system as a whole, exist as an alternative to determine the residence time distribution. Lumped parametre models comprise of idealized models of piston and well-mixed flow and their combinations. Aquifer properties such as, dead volume and by-pass flow can also be included in these models. With the aid of these models, conceptual aquifer models can be tested and residence time distribution of groundwater can be determined

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

Residence-time framework for modeling multicomponent reactive transport in stream hyporheic zones

Science.gov (United States)

Painter, S. L.; Coon, E. T.; Brooks, S. C.

2017-12-01

Process-based models for transport and transformation of nutrients and contaminants in streams require tractable representations of solute exchange between the stream channel and biogeochemically active hyporheic zones. Residence-time based formulations provide an alternative to detailed three-dimensional simulations and have had good success in representing hyporheic exchange of non-reacting solutes. We extend the residence-time formulation for hyporheic transport to accommodate general multicomponent reactive transport. To that end, the integro-differential form of previous residence time models is replaced by an equivalent formulation based on a one-dimensional advection dispersion equation along the channel coupled at each channel location to a one-dimensional transport model in Lagrangian travel-time form. With the channel discretized for numerical solution, the associated Lagrangian model becomes a subgrid model representing an ensemble of streamlines that are diverted into the hyporheic zone before returning to the channel. In contrast to the previous integro-differential forms of the residence-time based models, the hyporheic flowpaths have semi-explicit spatial representation (parameterized by travel time), thus allowing coupling to general biogeochemical models. The approach has been implemented as a stream-corridor subgrid model in the open-source integrated surface/subsurface modeling software ATS. We use bedform-driven flow coupled to a biogeochemical model with explicit microbial biomass dynamics as an example to show that the subgrid representation is able to represent redox zonation in sediments and resulting effects on metal biogeochemical dynamics in a tractable manner that can be scaled to reach scales.

Soil Carbon Residence Time in the Arctic - Potential Drivers of Past and Future Change

Science.gov (United States)

Huntzinger, D. N.; Fisher, J.; Schwalm, C. R.; Hayes, D. J.; Stofferahn, E.; Hantson, W.; Schaefer, K. M.; Fang, Y.; Michalak, A. M.; Wei, Y.

2017-12-01

Carbon residence time is one of the most important factors controlling carbon cycling in ecosystems. Residence time depends on carbon allocation and conversion among various carbon pools and the rate of organic matter decomposition; all of which rely on environmental conditions, primarily temperature and soil moisture. As a result, residence time is an emergent property of models and a strong determinant of terrestrial carbon storage capacity. However, residence time is poorly constrained in process-based models due, in part, to the lack of data with which to benchmark global-scale models in order to guide model improvements and, ultimately, reduce uncertainty in model projections. Here we focus on improving the understanding of the drivers to observed and simulated carbon residence time in the Arctic-Boreal region (ABR). Carbon-cycling in the ABR represents one of the largest sources of uncertainty in historical and future projections of land-atmosphere carbon dynamics. This uncertainty is depicted in the large spread of terrestrial biospheric model (TBM) estimates of carbon flux and ecosystem carbon pool size in this region. Recent efforts, such as the Arctic-Boreal Vulnerability Experiment (ABoVE), have increased the availability of spatially explicit in-situ and remotely sensed carbon and ecosystem focused data products in the ABR. Together with simulations from Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP), we use these observations to evaluate the ability of models to capture soil carbon stocks and changes in the ABR. Specifically, we compare simulated versus observed soil carbon residence times in order to evaluate the functional response and sensitivity of modeled soil carbon stocks to changes in key environmental drivers. Understanding how simulated carbon residence time compares with observations and what drives these differences is critical for improving projections of changing carbon dynamics in the ABR and globally.

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

Explaining Direct Care Resource Use of Nursing Home Residents: Findings from Time Studies in Four States

Science.gov (United States)

Arling, Greg; Kane, Robert L; Mueller, Christine; Lewis, Teresa

2007-01-01

Objective To explain variation in direct care resource use (RU) of nursing home residents based on the Resource Utilization Groups III (RUG-III) classification system and other resident- and unit-level explanatory variables. Data Sources/Study Setting Primary data were collected on 5,314 nursing home residents in 156 nursing units in 105 facilities from four states (CO, IN, MN, MS) from 1998 to 2004. Study Design Nurses and other direct care staff recorded resident-specific and other time caring for all residents on sampled nursing units. Care time was linked to resident data from the Minimum Data Set assessment instrument. Major variables were: RUG-III group (34-group), other health and functional conditions, licensed and other professional minutes per day, unlicensed minutes per day, and direct care RU (wage-weighted minutes). Resident- and unit-level relationships were examined through hierarchical linear modeling. Data Collection/Extraction Methods Time study data were recorded with hand-held computers, verified for accuracy by project staff at the data collection sites and then merged into resident and unit-level data sets. Principal Findings Resident care time and RU varied between and within nursing units. RUG-III group was related to RU; variables such as length of stay and unit percentage of high acuity residents also were significantly related. Case-mix indices (CMIs) constructed from study data displayed much less variation across RUG-III groups than CMIs from earlier time studies. Conclusions Results from earlier time studies may not be representative of care patterns of Medicaid and private pay residents. New RUG-III CMIs should be developed to better reflect the relative costs of caring for these residents. PMID:17362220

Molecular Dynamics Simulations and Kinetic Measurements to Estimate and Predict Protein-Ligand Residence Times.

Science.gov (United States)

Mollica, Luca; Theret, Isabelle; Antoine, Mathias; Perron-Sierra, Françoise; Charton, Yves; Fourquez, Jean-Marie; Wierzbicki, Michel; Boutin, Jean A; Ferry, Gilles; Decherchi, Sergio; Bottegoni, Giovanni; Ducrot, Pierre; Cavalli, Andrea

2016-08-11

Ligand-target residence time is emerging as a key drug discovery parameter because it can reliably predict drug efficacy in vivo. Experimental approaches to binding and unbinding kinetics are nowadays available, but we still lack reliable computational tools for predicting kinetics and residence time. Most attempts have been based on brute-force molecular dynamics (MD) simulations, which are CPU-demanding and not yet particularly accurate. We recently reported a new scaled-MD-based protocol, which showed potential for residence time prediction in drug discovery. Here, we further challenged our procedure's predictive ability by applying our methodology to a series of glucokinase activators that could be useful for treating type 2 diabetes mellitus. We combined scaled MD with experimental kinetics measurements and X-ray crystallography, promptly checking the protocol's reliability by directly comparing computational predictions and experimental measures. The good agreement highlights the potential of our scaled-MD-based approach as an innovative method for computationally estimating and predicting drug residence times.

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

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...

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

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

Tracer concentration curves and residence time analysis in technological flow systems. 2

International Nuclear Information System (INIS)

Pippel, W.

1976-01-01

Tracer concentration curves measured in flow systems by means of radioactive isotopes are treated as a two dimensional random process. Comparing them with the family distribution functions described in part I, it follows that only in case of ergodic behaviour of the system tracer curves can be considered as age distribution functions. The conception of ergodicity in residence time systems has been explained with the aid of a time function measurable by a special method of radioactive tracer technique and by the mean value of the residence time obtainable from this function. Furthermore, technological consequences in evaluating tracer concentration curves of real flow systems are discussed with respect to supposed ergodic or nonergodic behaviour. These considerations are of special importance for flow systems with temporary fluctuations in structure. (author)

Mineralogical Controls over Carbon Storage and Residence Times in Grassland Soils

Science.gov (United States)

Dwivedi, D.; Riley, W. J.; Torn, M. S.; Spycher, N.

2014-12-01

Globally, soil organic matter (SOM) contains approximately three times more carbon than the atmosphere and terrestrial vegetation contain combined. However, it is not well understood why some SOM persists for a long time while other SOM decomposes quickly. For future climate predictions, representing soil organic matter (SOM) dynamics accurately in Earth system models is essential. Soil minerals stabilize organic carbon in soil; however, there are gaps in our understanding of how soil mineralogy controls the quantity and turnover of long-residence-time organic carbon. To investigate the impact of soil mineralogy on SOM dynamics, we used a new model (Biotic and Abiotic Model of SOM—BAMS1 [Riley et al., 2014]) integrated with a three-dimensional, multiphase reactive transport solver (TOUGHREACT). The model represents bacterial and fungal activity, archetypal polymer and monomer carbon substrate groups, aqueous chemistry, gaseous diffusion, aqueous advection and diffusion, and adsorption and desorption processes. BAMS1 can predict bulk SOM and radiocarbon signatures without resorting to an arbitrary depth-dependent decline in SOM turnover rates. Results show a reasonable match between observed and simulated depth-resolved SOM and Δ14C in grassland ecosystems (soils formed on terraces south of Eureka, California, and the Central Chernozem Region of Russia) and were consistent with expectations of depth-resolved profiles of lignin content and fungi:aerobic bacteria ratios. Results also suggest that clay-mineral surface area and soil sorption coefficients constitute dominant controls over organic carbon stocks and residence times, respectively. Bibliography: Riley, W.J., F.M. Maggi, M. Kleber, M.S. Torn, J.Y. Tang, D. Dwivedi, and N. Guerry (2014), Long residence times of rapidly decomposable soil organic matter: application of a multi-phase, multi-component, and vertically resolved model (BAMS1) to soil carbon dynamics, Geoscientific Model Development, vol. 7, 1335

Lean principles optimize on-time vascular surgery operating room starts and decrease resident work hours.

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Warner, Courtney J; Walsh, Daniel B; Horvath, Alexander J; Walsh, Teri R; Herrick, Daniel P; Prentiss, Steven J; Powell, Richard J

2013-11-01

Lean process improvement techniques are used in industry to improve efficiency and quality while controlling costs. These techniques are less commonly applied in health care. This study assessed the effectiveness of Lean principles on first case on-time operating room starts and quantified effects on resident work hours. Standard process improvement techniques (DMAIC methodology: define, measure, analyze, improve, control) were used to identify causes of delayed vascular surgery first case starts. Value stream maps and process flow diagrams were created. Process data were analyzed with Pareto and control charts. High-yield changes were identified and simulated in computer and live settings prior to implementation. The primary outcome measure was the proportion of on-time first case starts; secondary outcomes included hospital costs, resident rounding time, and work hours. Data were compared with existing benchmarks. Prior to implementation, 39% of first cases started on time. Process mapping identified late resident arrival in preoperative holding as a cause of delayed first case starts. Resident rounding process inefficiencies were identified and changed through the use of checklists, standardization, and elimination of nonvalue-added activity. Following implementation of process improvements, first case on-time starts improved to 71% at 6 weeks (P = .002). Improvement was sustained with an 86% on-time rate at 1 year (P < .001). Resident rounding time was reduced by 33% (from 70 to 47 minutes). At 9 weeks following implementation, these changes generated an opportunity cost potential of $12,582. Use of Lean principles allowed rapid identification and implementation of perioperative process changes that improved efficiency and resulted in significant cost savings. This improvement was sustained at 1 year. Downstream effects included improved resident efficiency with decreased work hours. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All

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

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...

Geometrical effects on the electron residence time in semiconductor nano-particles.

Science.gov (United States)

Koochi, Hakimeh; Ebrahimi, Fatemeh

2014-09-07

We have used random walk (RW) numerical simulations to investigate the influence of the geometry on the statistics of the electron residence time τ(r) in a trap-limited diffusion process through semiconductor nano-particles. This is an important parameter in coarse-grained modeling of charge carrier transport in nano-structured semiconductor films. The traps have been distributed randomly on the surface (r(2) model) or through the whole particle (r(3) model) with a specified density. The trap energies have been taken from an exponential distribution and the traps release time is assumed to be a stochastic variable. We have carried out (RW) simulations to study the effect of coordination number, the spatial arrangement of the neighbors and the size of nano-particles on the statistics of τ(r). It has been observed that by increasing the coordination number n, the average value of electron residence time, τ̅(r) rapidly decreases to an asymptotic value. For a fixed coordination number n, the electron's mean residence time does not depend on the neighbors' spatial arrangement. In other words, τ̅(r) is a porosity-dependence, local parameter which generally varies remarkably from site to site, unless we are dealing with highly ordered structures. We have also examined the effect of nano-particle size d on the statistical behavior of τ̅(r). Our simulations indicate that for volume distribution of traps, τ̅(r) scales as d(2). For a surface distribution of traps τ(r) increases almost linearly with d. This leads to the prediction of a linear dependence of the diffusion coefficient D on the particle size d in ordered structures or random structures above the critical concentration which is in accordance with experimental observations.

Children's Perspectives on Everyday Experiences of Shared Residence: Time, Emotions and Agency Dilemmas

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Haugen, Gry Mette D.

2010-01-01

Shared residence is often presented as an arrangement that is in the best interests of the child following the divorce of its parents. Based on in-depth interviews with Norwegian children who have experienced shared residence, this article seeks to explore some dilemmas concerning time, agency and the children's emotions. Three characteristics of…

Residence-Time Distributions in Laminar Flows and During the Passage of Granular Solids Through Rotary Kilns

Energy Technology Data Exchange (ETDEWEB)

Beek, W. J.; De Ridder, H. J. [Technische Hogeschool, Delft (Netherlands); Houtman, J. P.W.; Kuiper, D. [Reactor Instituut, Delft (Netherlands)

1967-06-15

Data on residence-time distributions are important in the design of apparatus for the chemical industry. Radioactive tracers can be useful in many cases, e.g. where a pulse technique is desired. Two examples are given in which a pulse of radioactive tracer is used. The first example deals with the residence-time distribution of a laminar, Newtonian flow in an annulus. This problem arises especially in the extrusion and injection moulding of polymers and in the coating of wires with plastics. In these cases the fractions of polymer with long residence times may have other properties than the polymer that flows fastest, because the polymerization reaction or the degradation reactions go on during the process. Two difficulties are to be considered: (a) the tracer pulse (a radioactive Au-sol suspended in the liquid used) cannot be distributed over the cross-section in proportion to the local flow velocity, and (b) the outflowing liquid must be sampled discontinuously. Both effects have been studied and corrections are indicated. When these corrections are applied to the measured distribution curve, the result is in fair agreement with the calculated residence-time distribution. The second example considers the residence-time distribution in a granular solid (sand) passing through a rotary kiln. The response was measured at the outlet to a pulse at the inlet of radioactive material (sand impregnated with a solution of radioactive AuCl{sub 3}). When calculating the residence-time distribution from the experimental data, difficulties were encountered because the duration of the pulse was of the same order of magnitude as the average residence time. Considering this, it was found that the axial dispersion of the flow of sand could be described by an effective dispersion coefficient. This dispersion coefficient proved to be very low (order of magnitude 10{sup -5} m{sup 2}/s); hence, in practical situations, the flow of granular material through a rotary kiln may often be

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

Impact of the European Working Time Directive (EWTD) on the operative experience of surgery residents.

Science.gov (United States)

Hopmans, Cornelis J; den Hoed, Pieter T; van der Laan, Lijckle; van der Harst, Erwin; van der Elst, Maarten; Mannaerts, Guido H H; Dawson, Imro; Timman, Reinier; Wijnhoven, Bas P L; IJzermans, Jan N M

2015-04-01

In Europe and the United States, work hour restrictions are considered to be particularly burdensome for residents in surgery specialties. The aim of this study was to examine whether reduction of the work week to 48 hours resulting from the implementation of the European Working Time Directive has affected the operative experience of surgery residents. This study was conducted in a general surgery training region in the Netherlands, consisting of 1 university hospital and 6 district training hospitals. Operating records summarizing the surgical procedures performed as "primary surgeon" in the operating theater for different grades of surgeons were retrospectively analyzed for the period 2005-2012 by the use of linear regression models. Operative procedures performed by residents were considered the main outcome measure. In total, 235,357 operative procedures were performed, including 47,458 (20.2%) in the university hospital and 187,899 (79.8%) in the district training hospitals (n = 5). For residents in the university hospital, the mean number of operative procedures performed per 1.0 full-time equivalent increased from 128 operations in 2005 to 204 operations in 2012 (P = .001), whereas for residents in district training hospitals, no substantial differences were found over time. The mean (±SD) operative caseload of 64 residents who completed the 6-year training program between 2005 and 2012 was 1,391 ± 226 (range, 768-1856). A comparison of the operative caseload according to year of board-certification showed no difference. Implementation of the European Working Time Directive has not affected adversely the number of surgical procedures performed by residents within a general surgical training region in the Netherlands. Copyright © 2015 Elsevier Inc. All rights reserved.

Spatial distribution of residence time, microbe and storage volume of groundwater in headwater catchments

Science.gov (United States)

Tsujimura, Maki; Ogawa, Mahiro; Yamamoto, Chisato; Sakakibara, Koichi; Sugiyama, Ayumi; Kato, Kenji; Nagaosa, Kazuyo; Yano, Shinjiro

2017-04-01

Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, and time and stock information of the water is principal to understand hydrological processes in the catchments. Also, a variety of microbes are included in the groundwater and spring water, and those varies in time and space, suggesting that information of microbe could be used as tracer for groundwater flow system. However, there have been few researches to evaluate the relationship among the residence time, microbe and storage volume of the groundwater in headwater catchments. We performed an investigation on age dating using SF6 and CFCs, microbe counting in the spring water, and evaluation of groundwater storage volume based on water budget analysis in 8 regions underlain by different lithology, those are granite, dacite, sedimentary rocks, serpentinite, basalt and volcanic lava all over Japan. We conducted hydrometric measurements and sampling of spring water in base flow conditions during the rainless periods 2015 and 2016 in those regions, and SF6, CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute concentrations and total number of prokaryotes were determined on all water samples. Residence time of spring water ranged from 0 to 16 years in all regions, and storage volume of the groundwater within topographical watershed was estimated to be 0.1 m to 222 m in water height. The spring with the longer residence time tends to have larger storage volume in the watershed, and the spring underlain by dacite tends to have larger storage volume as compared with that underlain by sand stone and chert. Also, total number of prokaryotes in the spring water ranged from 103 to 105 cells/mL, and the spring tends to show clear increasing of total number of prokaryotes with decreasing of residence time. Thus, we observed a certain relationship among residence time, storage volume and total number of prokaryotes in the spring water, and

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.

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...

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.

Meteorologic, oceanographic, and geomorphic controls on circulation and residence time in a coral reef-lined embayment: Faga'alu Bay, American Samoa

Science.gov (United States)

Storlazzi, C. D.; Cheriton, O. M.; Messina, A. M.; Biggs, T. W.

2018-06-01

Water circulation over coral reefs can determine the degree to which reef organisms are exposed to the overlying waters, so understanding circulation is necessary to interpret spatial patterns in coral health. Because coral reefs often have high geomorphic complexity, circulation patterns and the duration of exposure, or "local residence time" of a water parcel, can vary substantially over small distances. Different meteorologic and oceanographic forcings can further alter residence time patterns over reefs. Here, spatially dense Lagrangian surface current drifters and Eulerian current meters were used to characterize circulation patterns and resulting residence times over different regions of the reefs in Faga'alu Bay, American Samoa, during three distinct forcing periods: calm, strong winds, and large waves. Residence times varied among different geomorphic zones of the reef and were reflected in the spatially varying health of the corals across the embayment. The relatively healthy, seaward fringing reef consistently had the shortest residence times, as it was continually flushed by wave breaking at the reef crest, whereas the degraded, sheltered, leeward fringing reef consistently had the longest residence times, suggesting this area is more exposed to land-based sources of pollution. Strong wind forcing resulted in the longest residence times by pinning the water in the bay, whereas large wave forcing flushed the bay and resulted in the shortest residence times. The effect of these different forcings on residence times was fairly consistent across all reef geomorphic zones, with the shift from wind to wave forcing shortening mean residence times by approximately 50%. Although ecologically significant to the coral organisms in the nearshore reef zones, these shortened residence times were still 2-3 times longer than those associated with the seaward fringing reef across all forcing conditions, demonstrating how the geomorphology of a reef environment sets a

Dedicated Shift Wrap-up Time Does Not Improve Resident Sign-out Volume or Efficiency.

Science.gov (United States)

Jeanmonod, Rebecca K; Brook, Christopher; Winther, Mark; Pathak, Soma; Boyd, Molly

2010-02-01

Sign-out (SO) is a challenge to the emergency physician. Some training programs have instituted overlapping 9-hour shifts. The residents see patients for eight hours, and have one hour of wrap-up time. This hour helps them complete patient care, leaving fewer patients to sign-out. We examined whether this strategy impacts SO burden. This is a retrospective review of patients evaluated by emergency medicine (EM) residents working 9-hour (eight hours of patient care, one hour wrap-up time) and 12-hour shifts (12 hours patient care, no reserved time for wrap-up). Data were collected by reviewing the clinical tracker. A patient was assigned to the resident who initiated care and dictated the chart. SO was defined as any patient in the ED without disposition at change of shift. Patient turn-around-time (TAT) was also recorded. One-hundred sixty-one postgraduate-year-one resident (PGY1), 264 postgraduate-year-two resident (PGY2), and 193 postgraduate-year-three resident (PGY3) shifts were included. PGY1s signed out 1.9 patients per 12-hour shift. PGY2s signed out 2.3 patients on 12-hour shifts and 1.8 patients on 9-hour shifts. PGY3s signed out 2.1 patients on 12-hour shifts and 2.0 patients on 9-hour shifts. When we controlled for patients seen per hour, SO burden was constant by class regardless of shift length, with PGY2s signing out 18% of patients seen compared to 15% for PGY3s. PGY1s signed out 18% of patients seen. TAT for patients seen by PGY1s and PGY2s was similar, at 189 and 187 minutes, respectively. TAT for patients seen by PGY3s was significantly less at 175 minutes. The additional hour devoted to wrapping up patients in the ED had no affect on SO burden. The SO burden represented a fixed percentage of the total number of patients seen by the residents. PGY3s sign-out a smaller percentage of patients seen compared to other classes, and have faster TATs.

Dedicated Shift Wrap-up Time Does Not Improve Resident Sign-out Volume or Efficiency

Directory of Open Access Journals (Sweden)

Jeanmonod, Rebecca K

2010-02-01

Full Text Available Objectives: Sign-out (SO is a challenge to the emergency physician. Some training programs have instituted overlapping 9-hour shifts. The residents see patients for eight hours, and have one hour of wrap-up time. This hour helps them complete patient care, leaving fewer patients to sign-out. We examined whether this strategy impacts SO burden.Methods: This is a retrospective review of patients evaluated by emergency medicine (EM residents working 9-hour (eight hours of patient care, one hour wrap-up time and 12-hour shifts (12 hours patient care, no reserved time for wrap-up. Data were collected by reviewing the clinical tracker. A patient was assigned to the resident who initiated care and dictated the chart. SO was defined as any patient in the ED without disposition at change of shift. Patient turn-around-time (TAT was also recorded.Results: One-hundred sixty-one postgraduate-year-one resident (PGY1, 264 postgraduate-year-two resident (PGY2, and 193 postgraduate-year-three resident (PGY3 shifts were included. PGY1s signed out 1.9 patients per 12-hour shift. PGY2s signed out 2.3 patients on 12-hour shifts and 1.8 patients on 9-hour shifts. PGY3s signed out 2.1 patients on 12-hour shifts and 2.0 patients on 9-hour shifts. When we controlled for patients seen per hour, SO burden was constant by class regardless of shift length, with PGY2s signing out 18% of patients seen compared to 15% for PGY3s. PGY1s signed out 18% of patients seen. TAT for patients seen by PGY1s and PGY2s was similar, at 189 and 187 minutes, respectively. TAT for patients seen by PGY3s was significantly less at 175 minutes.Conclusion: The additional hour devoted to wrapping up patients in the ED had no affect on SO burden. The SO burden represented a fixed percentage of the total number of patients seen by the residents. PGY3s sign-out a smaller percentage of patients seen compared to other classes, and have faster TATs. [West J Emerg Med. 2010; 11(1:35-39].

Academic time at a level 1 trauma center: no resident, no problem?

Science.gov (United States)

Matsushima, Kazuhide; Dickinson, Rebecca M; Schaefer, Eric W; Armen, Scott B; Frankel, Heidi L

2012-01-01

Globally, the compliance of resident work-hour restrictions has no impact on trauma outcome. However, the effect of protected education time (PET), during which residents are unavailable to respond to trauma patients, has not been studied. We hypothesized that PET has no impact on the outcome of trauma patients. We conducted a retrospective review of relevant patients at an academic level I trauma center. During PET, a trauma attending and advanced practice providers (APPs) responded to trauma activations. PGY1, 3, and 4 residents were also available at all other times. The outcome of new trauma patient activations during Thursday morning 3-hours resident PET was compared with same time period on other weekdays (non-PET) using a univariate and multivariate analysis. From January 2005 to April 2010, a total of 5968 trauma patients were entered in the registry. Of these, 178 patients (2.98%) were included for study (37 PET and 141 non-PET). The mean injury severity score (ISS) was 16.2. Although no significant difference were identified in mortality, complications, or length of stay (LOS), we do see that length of emergency department stay (ED-LOS) tends to be longer during PET, although not significantly (314 vs 381 minutes, p = 0.74). On the multiple logistic regression model, PET was not a significant factor of complications, LOS, or ED-LOS. Few trauma activations occur during PET. New trauma activations can be staffed safely by trauma activations and APPs. However, there could be some delays in transferring patients to appropriate disposition. Additional study is required to determine the effect of PET on existing trauma inpatients. Copyright © 2012 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Origin and residence time of water in the Lima aquifer

International Nuclear Information System (INIS)

Montoya, Modesto; Mamani, Enoc

2013-01-01

The 8 million inhabitants of the coastal city Lima are supplied with water from the Rimac and Chillon rivers and water wells in the Lima aquifer. The history of the Rimac River flow and static level of water in its wells have been correlated to calculate the residence time of water in the aquifer it is recharged by the Rimac River until it reaches a well located 12 km away in the Miraflores District near the sea. The relative abundance of 2 H and 18 O are used to identify the origins of the waters from those wells, and the 3 H and 14 C contents are used to estimate the time after they fall as rain. (authors).

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

Groundwater residence time : tell me who you are and I will tell which information you may provide

Science.gov (United States)

Aquilina, Luc; Labasque, Thierry; Kolbe, Tamara; Marçais, Jean; Leray, Sarah; Abbott, Ben; de Dreuzy, Jean-Raynald

2016-04-01

Groundwater residence-time or ages have been widely used in hydrogeology during the last decades. Following tritium measurements, anthropogenic gases (CFC, SF6, 35Kr) have been developed. They provide information at the aquifer scale on long residence times. They complement the more localized data obtained from sparse boreholes with hydraulic and geophysical methods. Anthropogenic tracer concentrations are most generally considered as "Groundwater ages" using a piston flow model providing an order of magnitude for the residence time. More advanced information can however be derived from the combined analysis of the tracer concentrations. For example, the residence time distribution over the last 50 years can be well approached by the concentration of two sufficient different anthropogenic tracers in the group (CFC, SF6, 35Kr), i.e. tracers whose anthropogenic chronicles are sufficiently different. And, with additional constrains on geological and hydraulic properties, groundwater ages contribute to characterize the aquifer structures and the groundwater resources. Complex geological environments also include old groundwater bodies in extremely confined aquifer sections. In such cases, various tracers are related to highly different processes. CFCs can be taken as a marker of modern contamination to track exchanges between shallower and deeper aquifers, leakage processes, and modification of circulations linked to recent anthropogenic changes. 14C or 36Cl can be used to evidence much older processes but have to be related to the history of the chemical element itself. Numerous field studies in fact demonstrate the broad-range extent of the residence time distribution spanning in some cases several orders of magnitude. Flow and transport models in heterogeneous structures confirm such wide residence times and help to characterize their distribution. Residence times also serve as a privileged interface to the fate of some contaminants in aquifers or to trace

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

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.

Origin and residence time of water in the Lima aquifer

Energy Technology Data Exchange (ETDEWEB)

Montoya, Modesto [Instituto Peruano de Energia Nuclear, Av. Canada 1470, San Borja, Lima (Peru); Universidad Nacional de Ingenieria, Av. Tupac Amaru 210, Rimac, Lima (Peru); Mamani, Enoc [Direccion de Servicios, Instituto Peruano de Energia Nuclear, Av. Jose Saco km 12.5, Carabayllo, Lima (Peru)

2013-07-01

The 8 million inhabitants of the coastal city Lima are supplied with water from the Rimac and Chillon rivers and water wells in the Lima aquifer. The history of the Rimac River flow and static level of water in its wells have been correlated to calculate the residence time of water in the aquifer it is recharged by the Rimac River until it reaches a well located 12 km away in the Miraflores District near the sea. The relative abundance of {sup 2}H and {sup 18}O are used to identify the origins of the waters from those wells, and the {sup 3}H and {sup 14}C contents are used to estimate the time after they fall as rain. (authors).

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)

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)

Mean residence times of atmospheric aerosols in the boundary layer as determined from 210Bi/210Pb activity ratios

International Nuclear Information System (INIS)

Papastefanou, C.; Bondietti, E.A.

1991-01-01

Concentrations of radioactive 210 Pb and 210 Bi were measured in surface air after chemical separation and radiochemical analysis in an annual cycle and were used to determine aerosol residence times in the lower atmosphere. It was concluded that residence times of 8 days would apply to aerosols of 0.3 μm activity median aerodynamic diameter (AMAD). Cascade impactor data are also presented in relating the residence times and the AMAD of atmospheric aerosols. (author)

Conformational Network and Residence Time Estimation of Trypsin-Benzamidine Unbinding Pathways

OpenAIRE

Dickson, Alex; Lotz, Samuel D.

2016-01-01

In this poster we present results from molecular dynamics sampling of benzamidine unbinding from trypsin. We give background on the weighted ensemble technique used (WExplore) and the Markovian state model construction. Our network shows three unique unbinding pathways including a never before observed unbinding pathway. We also estimate residence time to within one order of magnitude to the experimental value.

Seasonal variation of residence time in spring and groundwater evaluated by CFCs and numerical simulation in mountainous headwater catchment

Science.gov (United States)

Tsujimura, Maki; Watanabe, Yasuto; Ikeda, Koichi; Yano, Shinjiro; Abe, Yutaka

2016-04-01

Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time of subsurface water in time and space at the mountainous headwaters especially with steep slope. We investigated the temporal variation of the residence time of the spring and groundwater with tracing of hydrological flow processes in mountainous catchments underlain by granite, Yamanashi Prefecture, central Japan. We conducted intensive hydrological monitoring and water sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2013 in River Jingu Watershed underlain by granite, with an area of approximately 15 km2 and elevation ranging from 950 m to 2000 m. The CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Also, a numerical simulation was conducted to reproduce of the average residence times of the spring and groundwater. The residence time of the spring water estimated by the CFCs concentration ranged from 10 years to 60 years in space within the watershed, and it was higher (older) during the low flow season and lower (younger) during the high flow season. We tried to reproduce the seasonal change of the residence time in the spring water by numerical simulation, and the calculated residence time of the spring water and discharge of the stream agreed well with the observed values. The groundwater level was higher during the high flow season and the groundwater dominantly flowed through the weathered granite with higher permeability, whereas that was lower during the low flow season and that flowed dominantly through the fresh granite with lower permeability. This caused the seasonal variation of the residence time of the spring

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.

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.

Measuring gas-residence times in large municipal incinerators, by means of a pseudo-random binary signal tracer technique

International Nuclear Information System (INIS)

Nasserzadeh, V.; Swithenbank, J.; Jones, B.

1995-01-01

The problem of measuring gas-residence time in large incinerators was studied by the pseudo-random binary sequence (PRBS) stimulus tracer response technique at the Sheffield municipal solid-waste incinerator (35 MW plant). The steady-state system was disturbed by the superimposition of small fluctuations in the form of a pseudo-random binary sequence of methane pulses, and the response of the incinerator was determined from the CO 2 concentration in flue gases at the boiler exit, measured with a specially developed optical gas analyser with a high-frequency response. For data acquisition, an on-line PC computer was used together with the LAB Windows software system; the output response was then cross-correlated with the perturbation signal to give the impulse response of the incinerator. There was very good agreement between the gas-residence time for the Sheffield MSW incinerator as calculated by computational fluid dynamics (FLUENT Model) and gas-residence time at the plant as measured by the PRBS tracer technique. The results obtained from this research programme clearly demonstrate that the PRBS stimulus tracer response technique can be successfully and economically used to measure gas-residence times in large incinerator plants. It also suggests that the common commercial practice of characterising the incinerator operation by a single-residence-time parameter may lead to a misrepresentation of the complexities involved in describing the operation of the incineration system. (author)

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

Development of Electronic Medical Record-Based "Rounds Report" Results in Improved Resident Efficiency, More Time for Direct Patient Care and Education, and Less Resident Duty Hour Violations.

Science.gov (United States)

Ham, Phillip B; Anderton, Toby; Gallaher, Ryan; Hyrman, Mike; Simmerman, Erika; Ramanathan, Annamalai; Fallaw, David; Holsten, Steven; Howell, Charles Gordon

2016-09-01

Surgeons frequently report frustration and loss of efficiency with electronic medical record (EMR) systems. Together, surgery residents and a programmer at Augusta University created a rounds report (RR) summarizing 24 hours of vitals, intake/output, labs, and other values for each inpatient that were previously transcribed by hand. The objective of this study was to evaluate the RR's effect on surgery residents. Surgery residents were queried to assess the RR's impact. Outcome measures were time spent preparing for rounds, direct patient care time, educational activity time, rates of incorrect/incomplete data on rounds, and rate of duty hour violations. Hospital wide, 17,200 RRs were generated in the 1-month study. Twenty-three surgery residents participated. Time spent preparing for rounds decreased per floor patient (15.6 ± 3.0 vs 6.0 ± 1.2, P care unit patient (19.9 ± 2.9 vs 7.5 ± 1.2 P care increased from 45.1 ± 5.6 to 54.0 ± 5.7 per cent (P = 0.0044). Educational activity time increased from 35.2 ± 5.4 to 54.7 ± 7.1 minutes per resident per day (P = 0.0004). Reported duty hour violations decreased 58 per cent (P care at academic medical centers.

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

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

International Nuclear Information System (INIS)

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

2015-01-01

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. (authors)

Investigation of Residence and Travel Times in a Large Floodplain Lake with Complex Lake-River Interactions: Poyang Lake (China

Directory of Open Access Journals (Sweden)

Yunliang Li

2015-04-01

Full Text Available Most biochemical processes and associated water quality in lakes depends on their flushing abilities. The main objective of this study was to investigate the transport time scale in a large floodplain lake, Poyang Lake (China. A 2D hydrodynamic model (MIKE 21 was combined with dye tracer simulations to determine residence and travel times of the lake for various water level variation periods. The results indicate that Poyang Lake exhibits strong but spatially heterogeneous residence times that vary with its highly seasonal water level dynamics. Generally, the average residence times are less than 10 days along the lake’s main flow channels due to the prevailing northward flow pattern; whereas approximately 30 days were estimated during high water level conditions in the summer. The local topographically controlled flow patterns substantially increase the residence time in some bays with high spatial values of six months to one year during all water level variation periods. Depending on changes in the water level regime, the travel times from the pollution sources to the lake outlet during the high and falling water level periods (up to 32 days are four times greater than those under the rising and low water level periods (approximately seven days.

Origin and residence time of water in the Lima Aquifer

OpenAIRE

Montoya, Modesto; Mamani, Enoc

2014-01-01

The 8 million inhabitants of the coastal city Lima are supplied with water from the Rimac and Chillon rivers and water wells in the Lima aquifer. The history of the Rimac River flow and static level of water in its wells have been correlated to calculate the residence time of water in the aquifer it is recharged by the Rimac River until it reaches a well located 12 km away in the Miraflores District near the sea. The relative abundance of H-2 and O-18 are used to identify the origins of the w...

RTDB: A memory resident real-time object database

International Nuclear Information System (INIS)

Nogiec, Jerzy M.; Desavouret, Eugene

2003-01-01

RTDB is a fast, memory-resident object database with built-in support for distribution. It constitutes an attractive alternative for architecting real-time solutions with multiple, possibly distributed, processes or agents sharing data. RTDB offers both direct and navigational access to stored objects, with local and remote random access by object identifiers, and immediate direct access via object indices. The database supports transparent access to objects stored in multiple collaborating dispersed databases and includes a built-in cache mechanism that allows for keeping local copies of remote objects, with specifiable invalidation deadlines. Additional features of RTDB include a trigger mechanism on objects that allows for issuing events or activating handlers when objects are accessed or modified and a very fast, attribute based search/query mechanism. The overall architecture and application of RTDB in a control and monitoring system is presented

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.

A 2D Hydrodynamic-Particle Analysis model was applied to the Gulf of Kachchh (GoK) to estimate the residence time of pollutants. The tidal currents in the Gulf have a strong E-W component, which prevents the material in the north being transported...

Using 50 years of soil radiocarbon data to identify optimal approaches for estimating soil carbon residence times

Science.gov (United States)

Baisden, W. T.; Canessa, S.

2013-01-01

In 1959, Athol Rafter began a substantial programme of systematically monitoring the flow of 14C produced by atmospheric thermonuclear tests through organic matter in New Zealand soils under stable land use. A database of ∼500 soil radiocarbon measurements spanning 50 years has now been compiled, and is used here to identify optimal approaches for soil C-cycle studies. Our results confirm the potential of 14C to determine residence times, by estimating the amount of ‘bomb 14C’ incorporated. High-resolution time series confirm this approach is appropriate, and emphasise that residence times can be calculated routinely with two or more time points as little as 10 years apart. This approach is generally robust to the key assumptions that can create large errors when single time-point 14C measurements are modelled. The three most critical assumptions relate to: (1) the distribution of turnover times, and particularly the proportion of old C (‘passive fraction’), (2) the lag time between photosynthesis and C entering the modelled pool, (3) changes in the rates of C input. When carrying out approaches using robust assumptions on time-series samples, multiple soil layers can be aggregated using a mixing equation. Where good archived samples are available, AMS measurements can develop useful understanding for calibrating models of the soil C cycle at regional to continental scales with sample numbers on the order of hundreds rather than thousands. Sample preparation laboratories and AMS facilities can play an important role in coordinating the efficient delivery of robust calculated residence times for soil carbon.

Using 50 years of soil radiocarbon data to identify optimal approaches for estimating soil carbon residence times

International Nuclear Information System (INIS)

Baisden, W.T.; Canessa, S.

2013-01-01

In 1959, Athol Rafter began a substantial programme of systematically monitoring the flow of 14 C produced by atmospheric thermonuclear tests through organic matter in New Zealand soils under stable land use. A database of ∼500 soil radiocarbon measurements spanning 50 years has now been compiled, and is used here to identify optimal approaches for soil C-cycle studies. Our results confirm the potential of 14 C to determine residence times, by estimating the amount of ‘bomb 14 C’ incorporated. High-resolution time series confirm this approach is appropriate, and emphasise that residence times can be calculated routinely with two or more time points as little as 10 years apart. This approach is generally robust to the key assumptions that can create large errors when single time-point 14 C measurements are modelled. The three most critical assumptions relate to: (1) the distribution of turnover times, and particularly the proportion of old C (‘passive fraction’), (2) the lag time between photosynthesis and C entering the modelled pool, (3) changes in the rates of C input. When carrying out approaches using robust assumptions on time-series samples, multiple soil layers can be aggregated using a mixing equation. Where good archived samples are available, AMS measurements can develop useful understanding for calibrating models of the soil C cycle at regional to continental scales with sample numbers on the order of hundreds rather than thousands. Sample preparation laboratories and AMS facilities can play an important role in coordinating the efficient delivery of robust calculated residence times for soil carbon.

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.

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

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.

Using 50 years of soil radiocarbon data to identify optimal approaches for estimating soil carbon residence times

Energy Technology Data Exchange (ETDEWEB)

Baisden, W.T., E-mail: t.baisden@gns.cri.nz [National Isotope Centre, GNS Science, P.O. Box 31312, Lower Hutt (New Zealand); Canessa, S. [National Isotope Centre, GNS Science, P.O. Box 31312, Lower Hutt (New Zealand)

2013-01-15

In 1959, Athol Rafter began a substantial programme of systematically monitoring the flow of {sup 14}C produced by atmospheric thermonuclear tests through organic matter in New Zealand soils under stable land use. A database of {approx}500 soil radiocarbon measurements spanning 50 years has now been compiled, and is used here to identify optimal approaches for soil C-cycle studies. Our results confirm the potential of {sup 14}C to determine residence times, by estimating the amount of 'bomb {sup 14}C' incorporated. High-resolution time series confirm this approach is appropriate, and emphasise that residence times can be calculated routinely with two or more time points as little as 10 years apart. This approach is generally robust to the key assumptions that can create large errors when single time-point {sup 14}C measurements are modelled. The three most critical assumptions relate to: (1) the distribution of turnover times, and particularly the proportion of old C ('passive fraction'), (2) the lag time between photosynthesis and C entering the modelled pool, (3) changes in the rates of C input. When carrying out approaches using robust assumptions on time-series samples, multiple soil layers can be aggregated using a mixing equation. Where good archived samples are available, AMS measurements can develop useful understanding for calibrating models of the soil C cycle at regional to continental scales with sample numbers on the order of hundreds rather than thousands. Sample preparation laboratories and AMS facilities can play an important role in coordinating the efficient delivery of robust calculated residence times for soil carbon.

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 recharged by a losing reach of the Lower American River, despite the presence of levees with slurry cut-off walls.1 Flow in the Lower American River is controlled through the operation of the Folsom and Nimbus Dams, with a minimum flow of 500 cfs. Water table elevation in wells in close proximity to the river are compared to river stage to determine the effect of river stage on groundwater recharge rates. Additionally, Tritium-3Helium dates and stable isotopes (∂18O and ∂2H) have been measured in monitoring wells 200- 2400 ft lateral distance from the river, and depths of 25 -225 feet 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.

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)

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)

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.

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.

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.

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.

Redfield Ratios in Inland Waters: Higher Biological Control of C:N:P Ratios in Tropical Semi-arid High Water Residence Time Lakes

Directory of Open Access Journals (Sweden)

Ng H. They

2017-08-01

Full Text Available The canonical Redfield C:N:P ratio for algal biomass is often not achieved in inland waters due to higher C and N content and more variability when compared to the oceans. This has been attributed to much lower residence times and higher contributions of the watershed to the total organic matter pool of continental ecosystems. In this study we examined the effect of water residence times in low latitude lakes (in a gradient from humid to a semi-arid region on seston elemental ratios in different size fractions. We used lake water specific conductivity as a proxy for residence time in a region of Eastern Brazil where there is a strong precipitation gradient. The C:P ratios decreased in the seston and bacterial size-fractions and increased in the dissolved fraction with increasing water retention time, suggesting uptake of N and P from the dissolved pool. Bacterial abundance, production and respiration increased in response to increased residence time and intracellular nutrient availability in agreement with the growth rate hypothesis. Our results reinforce the role of microorganisms in shaping the chemical environment in aquatic systems particularly at long water residence times and highlights the importance of this factor in influencing ecological stoichiometry in all aquatic ecosystems.

Pediatricians Working Part-Time Has Plateaued.

Science.gov (United States)

Cull, William L; Frintner, Mary Pat; O'Connor, Karen G; Olson, Lynn M

2016-04-01

To examine trends in pediatricians working part-time and residents seeking part-time work and to examine associated characteristics. The American Academy of Pediatrics (AAP) Periodic Survey of Fellows and the AAP Annual Survey of Graduating Residents were used to examine part-time employment. Fourteen periodic surveys were combined with an overall response rate of 57%. Part-time percentages were compared for surveys conducted from 2006-2009 and 2010-2013. The AAP Annual Surveys of Graduating Residents (combined response rate = 60%) from 2006-2009 were compared with 2010-2013 surveys for residents seeking and obtaining part-time positions following training. Multivariable logistic regression models identified characteristics associated with part-time work. Comparable percentages of pediatricians worked part-time in 2006-2009 (23%) and 2010-2013 (23%). There was similarly no statistically significant difference in residents seeking part-time work (30%-28%), and there was a slight decline in residents accepting part-time work (16%-13%, aOR .75, 95% CI .56-.96). Increases in working part-time were not found for any subgroups examined. Women consistently were more likely than men to work part-time (35% vs 9%), but they showed different patterns of part-time work across age. Women in their 40s (40%) were more likely than other women (33%) and men in their 60s (20%) were more likely than other men (5%) to work part-time. There has been a levelling off in the number of pediatricians working part-time and residents seeking part-time work. Overall, women remain more likely to work part-time, although 1 in 5 men over 60 work part-time. Copyright © 2016 Elsevier Inc. All rights reserved.

Anesthesia preparation time is not affected by the experience level of the resident involved during his/her first month of adult cardiac surgery.

Science.gov (United States)

Broussard, David M; Couch, Michael C

2011-10-01

This study was designed to answer the question of whether the experience level of the resident on his/her first month of adult cardiothoracic anesthesiology has an impact on operating room efficiency in a large academic medical center. Traditionally, the resident's 1st month of cardiac anesthesia had been reserved for the clinical anesthesia (CA)-2 year of training. This study analyzed the impact on operating room efficiency of moving the 1st month of cardiac anesthesia into the CA-1 year. The authors hypothesized that there would be no difference in anesthesia preparation times (defined as the interval between "in-room" and "anesthesia-ready" times) between CA-1 and CA-2 residents on their 1st month of cardiac anesthesia. This study was retrospective and used an electronic anesthesia information management system database. This study was conducted on care provided at a single 450-bed academic medical center. This study included 12 residents in their 1st month of cardiac anesthesia. The anesthesia preparation time (defined as the interval between "in-room" and "anesthesia-ready" times) was measured for cases involving residents on their first month of cardiac anesthesia. Anesthesia preparation times for 6 CA-1 resident months and 6 CA-2 resident months (100 adult cardiac procedures in total) were analyzed (49 for the CA-1 residents and 51 for the CA-2s). There were no differences in preparation time between CA-1 and CA-2 residents as a group (p = 0.8169). The CA-1 residents had an unadjusted mean (±standard error) of 51.1 ± 3.18 minutes, whereas the CA-2 residents' unadjusted mean was 50.2 ± 2.41 minutes. Adjusting for case mix (valves v coronary artery bypass graft surgery), the CA-1 mean was 49.1 ± 5.22 minutes, whereas the CA-2 mean was 49.1 ± 4.54 minutes. These findings suggest that operating room efficiency as measured by the anesthesia preparation time may not be affected by the level of the resident on his/her 1st month of adult cardiac anesthesia

Survey of some natural decay-series isotopes in the Wairakei geothermal area and possible residence-time applications

International Nuclear Information System (INIS)

Stewart, M.K.; Burnett, W.C.; Whitehead, N.E.

1993-01-01

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

A time-efficient web-based teaching tool to improve medical knowledge and decrease ABIM failure rate in select residents.

Science.gov (United States)

Drake, Sean M; Qureshi, Waqas; Morse, William; Baker-Genaw, Kimberly

2015-01-01

The American Board of Internal Medicine (ABIM) exam's pass rate is considered a quality measure of a residency program, yet few interventions have shown benefit in reducing the failure rate. We developed a web-based Directed Reading (DR) program with an aim to increase medical knowledge and reduce ABIM exam failure rate. Internal medicine residents at our academic medical center with In-Training Examination (ITE) scores ≤ 35 th percentile from 2007 to 2013 were enrolled in DR. The program matches residents to reading assignments based on their own ITE-failed educational objectives and provides direct electronic feedback from their teaching physicians. ABIM exam pass rates were analyzed across various groups between 2002 and 2013 to examine the effect of the DR program on residents with ITE scores ≤ 35 percentile pre- (2002-2006) and post-intervention (2007-2013). A time commitment survey was also given to physicians and DR residents at the end of the study. Residents who never scored ≤ 35 percentile on ITE were the most likely to pass the ABIM exam on first attempt regardless of time period. For those who ever scored ≤ 35 percentile on ITE, 91.9% of residents who participated in DR passed the ABIM exam on first attempt vs 85.2% of their counterparts pre-intervention (p ITE were more likely to fail ABIM exam on first attempt, those who participated in the DR program were less likely to fail than the historical control counterparts. The web-based teaching method required little time commitment by faculty.

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.

Using stable isotope tracers to assess hydrological flow paths, residence times and landscape influences in a nested mesoscale catchment

Directory of Open Access Journals (Sweden)

P. Rodgers

2005-01-01

Full Text Available δ18O measurements in precipitation and stream waters were used to investigate hydrological flow paths and residence times at nested spatial scales in the mesoscale (233 km2 River Feugh catchment in the northeast of Scotland over the 2001-2002 hydrological year. Precipitation δ18O exhibited strong seasonal variation, which although significantly damped within the catchment, was reflected in stream water at six sampling sites. This allowed δ18O variations to be used to infer the relative influence of soil-derived storm flows with a seasonally variable isotopic signature, and groundwater of apparently more constant isotopic composition. Periodic regression analysis was then used to examine the sub-catchment difference using an exponential flow model to provide indicative estimates of mean stream water residence times, which varied between approximately 3 and 14 months. This showed that the effects of increasing scale on estimated mean stream water residence time was minimal beyond that of the smallest (ca. 1 km2 headwater catchment scale. Instead, the interaction of catchment soil cover and topography appeared to be the dominant controlling influence. Where sub-catchments had extensive peat coverage, responsive hydrological pathways produced seasonally variable δ18O signatures in runoff with short mean residence times (ca. 3 months. In contrast, areas dominated by steeper slopes, more freely draining soils and larger groundwater storage in shallow valley-bottom aquifers, deeper flow paths allow for more effective mixing and damping of δ18O indicating longer residence times (>12 months. These insights from δ18O measurements extend the hydrological understanding of the Feugh catchment gained from previous geochemical tracer studies, and demonstrate the utility of isotope tracers in investigating the interaction of hydrological processes and catchment characteristics at larger spatial scales.

Optimizing residence time, temperature and speed to improve TMP pulp properties and reduce energy

Energy Technology Data Exchange (ETDEWEB)

Sabourin, M.; Xu, E.; Cort, B.; Boileau, I.; Waller, A.

1997-04-01

The concept of reducing energy consumption in pulp mills by increasing the disc speed of refining has been established using single disc and double disc refiners in both pilot plant and mill applications. The RTS study evaluated in this paper reviews the effect of high-speed single disc refining coupled with shortdwell-high pressure retention conditions. Coupling these variables permitted evaluation of an optimum residence time, temperature and speed (RTS) operational window. The objective of the RTS conditions to sufficiently soften the wood chips through high temperature such that the fibre is more receptive to initial defiberization at high intensity. The improved pulp from the primary refiner at high intensity could potentially demonstrate improvements in physical pulp properties at a reduced specific energy requirement. The spruce/fir RTS-TMP described here required significantly less specific energy and produced TMP with slightly improved strength properties and equivalent optical properties compared to conventional TMP pulp. Studies on the radiate pine furnish indicated that the physical pulp property/specific energy relationships could be adjusted by manipulating the residence time. 4 refs., 10 tabs., 10 figs.

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.

Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.

Science.gov (United States)

Lv, Jinze; Zhu, Lizhong

2013-01-01

A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

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)

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)

Water Residence Time estimation by 1D deconvolution in the form of a l2 -regularized inverse problem with smoothness, positivity and causality constraints

Science.gov (United States)

Meresescu, Alina G.; Kowalski, Matthieu; Schmidt, Frédéric; Landais, François

2018-06-01

The Water Residence Time distribution is the equivalent of the impulse response of a linear system allowing the propagation of water through a medium, e.g. the propagation of rain water from the top of the mountain towards the aquifers. We consider the output aquifer levels as the convolution between the input rain levels and the Water Residence Time, starting with an initial aquifer base level. The estimation of Water Residence Time is important for a better understanding of hydro-bio-geochemical processes and mixing properties of wetlands used as filters in ecological applications, as well as protecting fresh water sources for wells from pollutants. Common methods of estimating the Water Residence Time focus on cross-correlation, parameter fitting and non-parametric deconvolution methods. Here we propose a 1D full-deconvolution, regularized, non-parametric inverse problem algorithm that enforces smoothness and uses constraints of causality and positivity to estimate the Water Residence Time curve. Compared to Bayesian non-parametric deconvolution approaches, it has a fast runtime per test case; compared to the popular and fast cross-correlation method, it produces a more precise Water Residence Time curve even in the case of noisy measurements. The algorithm needs only one regularization parameter to balance between smoothness of the Water Residence Time and accuracy of the reconstruction. We propose an approach on how to automatically find a suitable value of the regularization parameter from the input data only. Tests on real data illustrate the potential of this method to analyze hydrological datasets.

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

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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...

First passage time problems in time-dependent fields

International Nuclear Information System (INIS)

Fletcher, J.E.; Havlin, S.; Weiss, G.H.

1988-01-01

This paper discusses the simplest first passage time problems for random walks and diffusion processes on a line segment. When a diffusing particle moves in a time-varying field, use of the adjoint equation does not lead to any simplification in the calculation of moments of the first passage time as is the case for diffusion in a time-invariant field. We show that for a discrete random walk in the presence of a sinusoidally varying field there is a resonant frequency omega* for which the mean residence time on the line segment in a minimum. It is shown that for a random walk on a line segment of length L the mean residence time goes like L 2 for large L when omega omega*, but when omega = omega* the dependence is proportional to L. The results of our simulation are numerical, but can be regarded as exact. Qualitatively similar results are shown to hold for diffusion processes by a perturbation expansion in powers of a dimensionless velocity. These results are extended to higher values of this parameter by a numerical solution of the forward equation

Leveraging time and learning style, iPod vs. realtime attendance at a series of medicine residents conferences: a randomised controlled trial

Directory of Open Access Journals (Sweden)

Michael Tempelhof

2009-06-01

Conclusions Residency training programmes can optimise time management strategies with the integration of innovative learning resources into educational curricula. This study suggests that iPod capture of conferences is a reasonable resource to help meet the educational goals of residents and residency programs.

[Work satisfaction, quality of life and leisure time of residents at the Soroka University Medical Center, Beer Sheba, Israel].

Science.gov (United States)

Acker, Asaf; Perry, Zvi; Reuveni, Haim; Toker, Asaf

2009-02-01

Work dissatisfaction among physicians worldwide continues to rise over the last few decades, mainly due to declining professional prestige, tack of self fulfillment, time pressure and tack of leisure time. Physicians' burnout is a major result of dissatisfaction, causing doctors to leave the medical profession, and to provide lower quality of care. To examine the work satisfaction, quality of life and leisure time of residents in the Soroka University Medical Center. A validated questionnaire was delivered during the second half of 2004 to 252 residents in the Soroka University Medical Center The data was analyzed using the SPSS 12 for windows program. Descriptive analysis, parametric Students' T Test [where pleisure time. Further attention must be given to these matters--a step which will eventually improve patient care, and delay, to some extent, the burnout of physicians.

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.

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.)

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.

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.

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.

A residence-time-based transport approach for the groundwater pathway in performance assessment models

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Robinson, Bruce A.; Chu, Shaoping

2013-03-01

This paper presents the theoretical development and numerical implementation of a new modeling approach for representing the groundwater pathway in risk assessment or performance assessment model of a contaminant transport system. The model developed in the present study, called the Residence Time Distribution (RTD) Mixing Model (RTDMM), allows for an arbitrary distribution of fluid travel times to be represented, to capture the effects on the breakthrough curve of flow processes such as channelized flow and fast pathways and complex three-dimensional dispersion. Mathematical methods for constructing the model for a given RTD are derived directly from the theory of residence time distributions in flowing systems. A simple mixing model is presented, along with the basic equations required to enable an arbitrary RTD to be reproduced using the model. The practical advantages of the RTDMM include easy incorporation into a multi-realization probabilistic simulation; computational burden no more onerous than a one-dimensional model with the same number of grid cells; and straightforward implementation into available flow and transport modeling codes, enabling one to then utilize advanced transport features of that code. For example, in this study we incorporated diffusion into the stagnant fluid in the rock matrix away from the flowing fractures, using a generalized dual porosity model formulation. A suite of example calculations presented herein showed the utility of the RTDMM for the case of a radioactive decay chain, dual porosity transport and sorption.

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

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.

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

Burnout syndrome during residency in internal medicine and pediatrics in a country without working time directive.

Science.gov (United States)

Aksoy, Duygu Yazgan; Durusu Tanriover, Mine; Unal, Sule; Dizdar, Omer; Kalyoncu, Umut; Karakaya, Jale; Unal, Serhat; Kale, Gulsev

2014-01-01

The purpose of this paper is to demonstrate burnout syndrome among internal medicine and pediatrics residents in a country that does not have the working time directive (WTD) and also to determine the risk factors and consequent impact on efficient functioning in clinical areas. A 57-item questionnaire was given to internal medicine and pediatrics residents. Responses from 22 pediatrics and 33 internal medicine residents were evaluated. Demographic findings, burnout scores, having hobbies, social activities and reading books unrelated to medicine were similar between the two groups. Six pediatrics residents (27.3 per cent) and 11 (33.3 per cent) internal medicine residents met the criteria for clinically significant burnout. Personal accomplishment scores and reading books unrelated to medicine were found to be related to burnout. Burnout is a syndrome characterized by depersonalization, emotional exhaustion and a low sense of personal accomplishment. It is important to document burnout in countries where WTDs are not implemented. Further studies might demonstrate burnout's effect on patient safety, service quality and physician's performance.

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)

Measurement of residence time distribution of liquid phase in an industrial-scale continuous pulp digester using radiotracer technique

International Nuclear Information System (INIS)

Sheoran, Meenakshi; Goswami, Sunil; Pant, Harish J.; Biswal, Jayashree; Sharma, Vijay K.; Chandra, Avinash; Bhunia, Haripada; Bajpai, Pramod K.; Rao, S. Madhukar; Dash, A.

2016-01-01

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. - Highlights: • Radiotracer experiments were conducted to measure RTD of liquid phase in a pulp digester • Mean residence times of white liquor were measured • Axial dispersion and tanks-in-series models were used to investigate flow patterns • Parallel flow paths were observed in first section of the digester • Optimized flow rates of biomass and liquor were obtained

Life events during surgical residency have different effects on women and men over time.

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Chen, Michelle M; Yeo, Heather L; Roman, Sanziana A; Bell, Richard H; Sosa, Julie A

2013-08-01

Women represent half of medical school graduates in the United States. Our aim was to characterize the effects of marriage and childbirth on the experiences of surgery residents. This was a prospective, longitudinal study of categorical general surgery residents between 2008 and 2010. Outcomes included changes in faculty and peer relationships, work-life balance, financial security, and career goals over time. We included 4,028 residents. Compared with men, women in postgraduate years (PGYs) 1 through 5 were less likely to be married (28.2% to 47.3% vs 49.6% to 67.6%) or have children (4.6% to 18.0% vs 19.0% to 45.8%) (P < .001). Women who married during PGY1 to PGY3 became worried about performing in front of senior residents (P = .005); men who married were more likely to be happy at work (P = .005). Women who had a first child during PGY1 to PGY3 were more likely to feel overwhelmed (P = .008) and worry about financial security (P = .03) than other women. Men who had a child were more likely to feel supported by faculty (P = .004), but they experienced more family strain (P = .008) compared to childless men. Marriage and childbirth are associated with divergent changes in career experiences for women and men. Women lag behind their male peers in these life events from start to finish of residency. Copyright © 2013 Mosby, Inc. All rights reserved.

Groundwater flowpaths and residence times inferred by 14C, 36Cl and 4He isotopes in the Continental Intercalaire aquifer (North-Western Africa)

Science.gov (United States)

Petersen, J. O.; Deschamps, P.; Hamelin, B.; Fourré, E.; Gonçalvès, J.; Zouari, K.; Guendouz, A.; Michelot, J.-L.; Massault, M.; Dapoigny, A.; ASTER Team

2018-05-01

In a semi-arid to arid climate context, dependency on groundwater resources may lead to overexploitation and deterioration of water quality. The Continental Intercalaire (CI) aquifer is one such continental-scale aquifer (more than a million of km2), which is mainly confined, poorly recharged but intensely abstracted. To date, the management of this resource relies on hydrogeological modelling and key parameters such as recharge/discharge rate and groundwater dynamics. We use a combination of residence time indicators (14C, 36Cl, 4He) and stable isotopes of water (2H and 18O) to give greater constraint on the groundwater residence time in the CI. In previous studies, 14C measurements and steady state modelling indicate a residence time of less than 100 ka whereas in others, 36Cl measurements and transient scenarios modelling suggest a longer residence time (>500 ka). In this study, most of the 14C measurements are below the limit of detection, establishing residence times greater than 40 ka and confirming the necessity of strict sampling protocols to exclude all air and AMS measurements when low 14C concentrations are expected. In the Tunisian recharge area, detectable 14C indicate sporadic recharge episodes (3-7 ka and 29-43 ka), whereas 4He and 36Cl concentrations in central areas suggest very old (water quality in the whole system.

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

One of the major water-quality problems in the Chesapeake Bay is an overabundance of nutrients from the streams and rivers that discharge to the Bay. Some of these nutrients are from nonpoint sources such as atmospheric deposition, agricultural manure and fertilizer, and septic systems. The effects of efforts to control nonpoint sources, however, can be difficult to quantify because of the lag time between changes at the land surface and the response in the base-flow (ground water) component of streams. To help resource managers understand the lag time between implementation of management practices and subsequent response in the nutrient concentrations in the base-flow component of streamflow, a study of ground-water discharge, residence time, and nitrate transport in springs throughout the Chesapeake Bay Watershed and in four smaller watersheds in selected hydrogeomorphic regions (HGMRs) was conducted. The four watersheds were in the Coastal Plain Uplands, Piedmont crystalline, Valley and Ridge carbonate, and Valley and Ridge siliciclastic HGMRs.A study of springs to estimate an apparent age of the ground water was based on analyses for concentrations of chlorofluorocarbons in water samples collected from 48 springs in the Chesapeake Bay Watershed. Results of the analysis indicate that median age for all the samples was 10 years, with the 25th percentile having an age of 7 years and the 75th percentile having an age of 13 years. Although the number of samples collected in each HGMR was limited, there did not appear to be distinct differences in the ages between the HGMRs. The ranges were similar between the major HGMRs above the Fall Line (modern to about 50 years), with only two HGMRs of small geographic extent (Piedmont carbonate and Mesozoic Lowland) having ranges of modern to about 10 years. The median values of all the HGMRs ranged from 7 to 11 years. Not enough samples were collected in the Coastal Plain for comparison. Spring samples showed slightly younger

Reflections in a time of transition: orthopaedic faculty and resident understanding of accreditation schemes and opinions on surgical skills feedback

Directory of Open Access Journals (Sweden)

Kenneth R. Gundle

2016-04-01

Full Text Available Introduction: Orthopaedic surgery is one of the first seven specialties that began collecting Milestone data as part of the Accreditation Council for Graduate Medical Education's Next Accreditation System (NAS rollout. This transition from process-based advancement to outcome-based education is an opportunity to assess resident and faculty understanding of changing paradigms, and opinions about technical skill evaluation. Methods: In a large academic orthopaedic surgery residency program, residents and faculty were anonymously surveyed. A total of 31/32 (97% residents and 29/53 (55% faculty responded to Likert scale assessments and provided open-ended responses. An internal end-of-rotation audit was conducted to assess timeliness of evaluations. A mixed-method analysis was utilized, with nonparametric statistical testing and a constant-comparative qualitative method. Results: There was greater familiarity with the six core competencies than with Milestones or the NAS (p<0.05. A majority of faculty and residents felt that end-of-rotation evaluations were not adequate for surgical skills feedback. Fifty-eight per cent of residents reported that end-of-rotation evaluations were rarely or never filled out in a timely fashion. An internal audit demonstrated that more than 30% of evaluations were completed over a month after rotation end. Qualitative analysis included themes of resident desire for more face-to-face feedback on technical skills after operative cases, and several barriers to more frequent feedback. Discussion: The NAS and outcome-based education have arrived. Residents and faculty need to be educated on this changing paradigm. This transition period is also a window of opportunity to address methods of evaluation and feedback. In our orthopaedic residency, trainees were significantly less satisfied than faculty with the amount of technical and surgical skills feedback being provided to trainees. The quantitative and qualitative analyses

Hydrochemistry, origin and residence time of deep groundwater in the Yuseong area

International Nuclear Information System (INIS)

Koh, Yong Kwon; Kim, Geon Young; Bae, Dae Seok; Park, Kyung Woo

2005-01-01

As a part of the radioactive waste disposal research program in Korea, the geological, hydrogeological and hydrogeochemical investigations have been carried out in the Yuseong area (KAERI). The temperature or groundwater is measured up to 24 .deg. C and thermal gradient is obtained, to 0.26 .deg. C/100m. pH of groundwater at upper section shows about 7 and the pH of groundwater of 200m below surface reaches almost constant value as 9.9∼10.3. The redox potential of groundwater varied with depth and more negative values were recognized in deep groundwater. The redox potential of deep groundwater, main factor of U solubility, was measured up to -150 mV. These high pH and reduced conditions indicates that the maximum U concentration in groundwater would be limited by the equilibrium solubility of U minerals. The chemistry of shallow groundwater shows Ca-HCO 3 or Ca-Na-HCO 3 type, whereas the deep groundwater belongs to typical Na-HCO 3 type. The chemistry of groundwater below 250m from the surface is constant with depth, indicating that the extent of water-rock reaction is almost unique, which is controlled by the residence time of groundwater. The carbon isotope data (δ 13 C) of groundwater show the contribution of carbon from either that microbial oxidation of organic matter or carbon dioxide from plant respiration. The measurement and interpretation of C-14 indicate that the residence time of borehole deep groundwater ranges from about 2,000 to 6,000 yr BP. The high δ 34 S so4 value of groundwater indicate that the sulfate reduction might be occurred in the deep environment

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

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...

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.

U Isotope Systematics on Groundwaters from Southwestern France : Mixing Processes and Residence Times

Science.gov (United States)

Innocent, C.; Malcuit, E.; Négrel, P.

2011-12-01

The Eocene Sands Aquifer of the Aquitanian Basin (Southwestern France) has been extensively studied for its hydrology, hydrogeochemistry and also for stable isotopes (André, 2002; André et al., 2005). 14C dates were also obtained in the southern part of the aquifer (André, 2002). Recently, in the framework of the CARISMEAU research project (Négrel et al., 2007), groundwaters have been analyzed for their U activity ratio in order to put some constraints on their residence time in the aquifer. A excellent correlation has been found between 234U/238U ratios (which can be as high as 13.5) and 14C dates, which allowed to propose residence times for the analyzed groundwaters at the scale of the whole aquifer (including the city of Bordeaux and its suburb) (Innocent and Négrel, 2008; submitted). The second step of the CARISMEAU research project (CARISMEAU 2) now focusses on the restricted "Entre-Deux-Mers" area. New groundwaters have been recovered and analyzed for their U isotopic composition. As for previous data, U activity ratios are typically very high, ranging from 2.9 to 8.6. Owing to additional 14C ages from the northern part of the aquifer, it is shown that most of the measured uranium activity ratios correlate with these 14C dates and fall on or close to the straight line defined previously (see above). As a consequence, residence times derived from U isotopic compositions fairly agree with 14C data, with only one exception from a groundwater which plots apart from the correlation line. Pumping tests have been done at a selected site (EMZM 7), involving pumping times of 1 hour, 8 hours and 16 hours. For each pumping time, waters have been recovered at different, increasing pumping rates of 80 m3 per hour, 120 m3 per hour, 160 m3 per hour, and 120 m3 per hour. The chemical composition of these twelve waters has not been found to vary significantly. Uranium activities are constant for ten of the twelve groundwaters (around 6.5, with a U concentration around

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

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...

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

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

Design report for the residence time extension of KNK II/2 from 455 to 720 equivalent full-power days

International Nuclear Information System (INIS)

Schade, H.-J.; Steinmetz, B.; Wehmann, U.

1985-05-01

The report describes the performance of the whole reactor and of its assemblies and their components during the residence time extension of the second core of KNK II from the foreseen value of 455 equivalent full-power days (efpd) to 720 efpd. By this extension existing reactivity and design reserves can be utilized, and the burnup of the test zone assemblies can be increased towards the level aimed at for future sodium breeder reactors. The investigations about the static and the dynamic behavior of the core with its components and of the heat transfer systems under nominal and accidental conditions show, that the plant can be safely operated during the residence time extension [de

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.

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)

A Comparison Study of Communication Skills between General Surgery and General Practice Residents on First-time Patient Visits

Directory of Open Access Journals (Sweden)

Ahmed Al Ansari

2012-04-01

Full Text Available Background: There is little published research about differences in doctor-patient communication of different specialties. Accordingly, we compared doctor-patient communication skills in two different specialties, general surgery (GS and general practice (GP. Methods: Twenty residents training at the Bahrain Defence Force Hospital (10 men and 10 women; mean age 28 years; 10 GS and 10 GP participated in 200 patient first visit consultations. The consultations were video-recorded and analysed by four trained observers using the MAAS Global scale. Results: 1 Internal consistency reliability of the MAAS Global (> 0.91 and Ep2 = 0.84 for raters was high, 2 GP residents spent more time (12 minutes than GS residents (7 minutes, in the visits, 3 There were several differences on the MAAS Global items between GP and GS residents (GS > GP, p GS, p < 0.05 on information giving, and 4 The present participants performed well compared to normative samples as well as to criterion-referenced cut-off scores. The general level of communication skills in both specialties, however, was ‘unsatisfactory’ and ‘doubtful’, as it is for normative samples. Conclusion: Excellent doctor-patient communication is essential but does not appear to receive the amount of attention that it deserves in practice settings. There are some differences between specialties as well as unsatisfactory communication skills for both specialties, since residents from both programs spent less time than recommended on each consultation. Our findings emphasize the need to improve the communication skills of physicians in general and for surgeons in particular.

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.

Latitude of residence and position in time zone are predictors of cancer incidence, cancer mortality, and life expectancy at birth.

Science.gov (United States)

Borisenkov, Mikhail F

2011-03-01

According to the hypothesis of circadian disruption, external factors that disturb the function of the circadian system can raise the risk of malignant neoplasm and reduce life span. Recent work has shown that the functionality of the circadian system is dependent not only on latitude of residence but also on the region's position in the time zone. The purpose of the present research was to examine the influence of latitude and time zone on cancer incidence, cancer mortality, and life expectancy at birth. A stepwise multiple regression analysis was carried out on residents of 59 regions of the European part of the Russian Federation (EPRF) using age-standardized parameters (per 100,000) of cancer incidence (CI), cancer mortality (CM), and life expectancy at birth (LE, yrs) as dependent variables. The geographical coordinates (latitude and position in the time zone) of the regions were used as independent variables, controlling for the level of economic development in the regions. The same analysis was carried out for LE in 31 regions in China. Latitude was the strongest predictor of LE in the EPRF population; it explained 48% and 45% of the variability in LE of women and men, respectively. Position within the time zone accounted for an additional 4% and 3% variability of LE in women and men, respectively. The highest values for LE were observed in the southeast of the EPRF. In China, latitude was not a predictor of LE, whereas position in the time zone explained 15% and 18% of the LE variability in women and men, respectively. The highest values of LE were observed in the eastern regions of China. Both latitude and position within the time zone were predictors for CI and CM of the EPRF population. Latitude was the best predictor of stomach CI and CM; this predictor explained 46% and 50% of the variability, respectively. Position within the time zone was the best predictor of female breast CM; it explained 15% of the variability. In most cases, CI and CM increased

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

Chemical and isotopic properties of water discharging from springs and wells in Shenandoah National Park (SNP), near the crest of the Blue Ridge Mountains, VA, USA were monitored to obtain information on groundwater residence times. Investigated time scales included seasonal (wet season, April, 1996; dry season, August–September, 1997), monthly (March through September, 1999) and hourly (30-min interval recording of specific conductance and temperature, March, 1999 through February, 2000). Multiple environmental tracers, including tritium/helium-3 (3H/3He), chlorofluorocarbons (CFCs), sulfur hexafluoride (SF6), sulfur-35 (35S), and stable isotopes (δ18O and δ2H) of water, were used to estimate the residence times of shallow groundwater discharging from 34 springs and 15 wells. The most reliable ages of water from springs appear to be based on SF6 and 3H/3He, with most ages in the range of 0–3 years. This range is consistent with apparent ages estimated from concentrations of CFCs; however, CFC-based ages have large uncertainties owing to the post-1995 leveling-off of the CFC atmospheric growth curves. Somewhat higher apparent ages are indicated by 35S (>1.5 years) and seasonal variation of δ18O (mean residence time of 5 years) for spring discharge. The higher ages indicated by the 35S and δ18O data reflect travel times through the unsaturated zone and, in the case of 35S, possible sorption and exchange of S with soils or biomass. In springs sampled in April, 1996, apparent ages derived from the 3H/3He data (median age of 0.2 years) are lower than those obtained from SF6 (median age of 4.3 years), and in contrast to median ages from 3H/3He (0.3 years) and SF6 (0.7 years) obtained during the late summer dry season of 1997. Monthly samples from 1999 at four springs in SNP had SF6apparent ages of only 1.2 to 2.5±0.8 years, and were consistent with the 1997 SF6 data. Water from springs has low excess air (0–1 cm3 kg−1) and N2–Ar temperatures that vary

Measurements of liquid phase residence time distributions in a pilot-scale continuous leaching reactor using radiotracer technique

International Nuclear Information System (INIS)

Pant, H.J.; Sharma, V.K.; Shenoy, K.T.; Sreenivas, T.

2015-01-01

An alkaline based continuous leaching process is commonly used for extraction of uranium from uranium ore. The reactor in which the leaching process is carried out is called a continuous leaching reactor (CLR) and is expected to behave as a continuously stirred tank reactor (CSTR) for the liquid phase. A pilot-scale CLR used in a Technology Demonstration Pilot Plant (TDPP) was designed, installed and operated; and thus needed to be tested for its hydrodynamic behavior. A radiotracer investigation was carried out in the CLR for measurement of residence time distribution (RTD) of liquid phase with specific objectives to characterize the flow behavior of the reactor and validate its design. Bromine-82 as ammonium bromide was used as a radiotracer and about 40–60 MBq activity was used in each run. The measured RTD curves were treated and mean residence times were determined and simulated using a tanks-in-series model. The result of simulation indicated no flow abnormality and the reactor behaved as an ideal CSTR for the range of the operating conditions used in the investigation. - Highlights: • Radiotracer technique was applied for evaluation of design of a pilot-scale continuous leaching reactor. • Mean residence time and dead volume were estimated. Dead volume was found to be ranging from 4% to 15% at different operating conditions. • Tank-in-series model was used to simulate the measured RTD data and was found suitable to describe the flow in the reactor. • No flow abnormality was found and the reactor behaved as a well-mixed system. The design of the reactor was validated

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

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

The Effect of Beaver Activity on the Ammonium Uptake and Water Residence Time Characteristics of a Third-Order Stream Reach

Science.gov (United States)

Briggs, M.; Gooseff, M. N.; Wollheim, W. M.; Peterson, B. J.; Morkeski, K.

2009-12-01

Increasing beaver populations within low gradient basins in the northeastern United States are fundamentally changing the way water and dissolved nutrients are exported through these stream networks to the coast. Beaver dams can increase water residence time and contact with organic material, promote anoxic conditions and enhance both surface and hyporheic transient storage; all of these may have an impact on biogeochemical reactivity and nutrient retention. To quantitatively assess some of these effects we co-injected NaCl and NH4+ into the same 3rd-order stream reach in Massachusetts, USA under pre- and post-dam conditions. These experiments were done at similar discharge rates to isolate the impacts of a large natural beaver dam (7 m X 1.3 m) on the low-gradient (0.002) system where variable discharge also imparts a strong control on residence time. During the post-dam experiment there was an estimated 2300 m3 of water impounded behind the structure, which influenced more than 300 m of the 650 m stream reach. Our results showed that median transport time through the reach increased by 160% after dam construction. Additionally the tracer tailing time normalized to the corresponding median transport time increased from 1.08 to 1.51, indicating a pronounced tailing of the tracer signal in the post-dam condition. Data collected within the beaver pond just upstream of the dam indicated poor mixing and the presence of preferential flow paths through the generally stagnant zone. The uptake length (Sw) for NH4+ was 1250 m under the pre-dam condition, and may have changed for the post-dam reach in part because of the observed changes in residence time. As beaver population growth continues within these basins the consequences may be a smoothing of the outlet hydrograph and increased nutrient and organic matter removal and storage along the stream network.

Pediatricians working part-time: past, present, and future.

Science.gov (United States)

Cull, William L; Mulvey, Holly J; O'Connor, Karen G; Sowell, Debra R; Berkowitz, Carol D; Britton, Carmelita V

2002-06-01

Pediatrics has consistently attracted a large number of women. Although the majority of practicing pediatricians are male, female pediatricians will soon constitute the majority. The challenge to balance personal and professional life is of particular concern to women, and part-time positions may provide a potential solution. To examine how many pediatricians currently work part-time, to examine trends in part-time employment from 1993 to present, to determine pediatric residents' interest in part-time employment, and to identify perceived barriers to part-time work. Two data sources were used for these analyses. The first was an American Academy of Pediatrics Periodic Survey from 1993 and 2000 asking a combined national sample of 3218 American Academy of Pediatrics members about their employment status. Multiple mailings were conducted for each survey producing an overall response rate of 62%. The second data source was a survey asking a national random sample of 500 pediatric residents completing training in 2000 about their job search experiences and attitudes toward part-time employment. Four mailings of this survey were completed, and responses were obtained from 71% of residents. The percentage of pediatricians working part-time increased from 11% in 1993 to 15% in 2000. This increase did not exceed what would be expected based on the rise in the percentage of pediatricians who are female from 36% in 1993 to 45% in 2000. On average, pediatricians working part-time provided 36% fewer direct patient care hours than full-time pediatricians (42 hours vs 27 hours). No statistically significant difference in direct patient care hours was apparent between male and female pediatricians working full-time. Female residents were more likely than male residents to consider part-time or reduced-hours positions (42% vs 14%) and to accept part-time or reduced-hours positions (14% vs 3%). Also, considerably more female residents (58%) than male residents (15%) indicated that

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)

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)

Groundwater residence time in basement aquifers of the Ochi-Narkwa Basin in the Central Region of Ghana

Science.gov (United States)

Ganyaglo, Samuel Y.; Osae, Shiloh; Akiti, Tetteh; Armah, Thomas; Gourcy, Laurence; Vitvar, Tomas; Ito, Mari; Otoo, Isaac

2017-10-01

Groundwaters from basement aquifers in the Ochi-Narkwa basin of the Central Region together with rain and surface waters have been analysed for stable isotopes (δ18O, δ2H and δ13C) and radioisotopes (3H and 14C) to determine sources of recharge, groundwater residence time and flow path. The mechanism of recharge to the groundwaters is by direct infiltration of past local rainfall of mean isotopic composition δ18O = -3.8‰ V-SMOW and δ2H = -18‰ V-SMOW. Tritium in the groundwaters ranged from 0.05 ± 0.07 to 4.75 ± 0.16 TU. Tritium data revealed that 85% of the groundwater samples were of modern recharge or young waters. The 14C content of the groundwaters ranged between 9.50 pMC in borehole CR2-50 at Ekumfi Asokwa to 113.56 pMC in borehole CR3-26 at Onyaadze. Evaluation of 3H and 14C data distinguished three groups of water namely (1) waters characterised by high 3H and high 14C depicting modern recharge, (2) waters showing a mixture of young and old water due to fractures and (3) waters showing low 3H and low 14C contents referred to as very old waters and include borehole CR2-50 at Ekumfi Asokwa. The estimated age or residence time of this older water is 19,459 years BP based on uncorrected age. The major flow direction is northwest-southeast. The dominant months contributing to recharge in the study area were February, March, April, May, June, August, September and October. Groundwater residence times in the basement aquifers of the Ochi-Narkwa basin showed that groundwater abstraction is sustainable and requires that the recharge areas are protected from contamination.

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...

Residence times and mixing of water in river banks: implications for recharge and groundwater - surface water exchange

Science.gov (United States)

Unland, N. P.; Cartwright, I.; Cendón, D. I.; Chisari, R.

2014-02-01

The residence time of groundwater within 50 m of the Tambo River, South East Australia, has been estimated through the combined use of 3H and 14C. Groundwater residence times increase towards the Tambo River which implies a gaining river system and not increasing bank storage with proximity to the Tambo River. Major ion concentrations and δ2H and δ18O values of bank water also indicate that bank infiltration does not significantly impact groundwater chemistry under baseflow and post-flood conditions, suggesting that the gaining nature of the river may be driving the return of bank storage water back into the Tambo River within days of peak flood conditions. The covariance between 3H and 14C indicates the leakage and mixing between old (~17 200 yr) groundwater from a semi-confined aquifer and younger groundwater (bank storage, as rapid pressure propagation into the semi-confined aquifer during flooding will minimise bank infiltration. This study illustrates the complex nature of river groundwater interactions and the potential downfall in assuming simple or idealised conditions when conducting hydrogeological studies.

A study of residence time distribution using radiotracer technique in the large scale plant facility

Science.gov (United States)

Wetchagarun, S.; Tippayakul, C.; Petchrak, A.; Sukrod, K.; Khoonkamjorn, P.

2017-06-01

As the demand for troubleshooting of large industrial plants increases, radiotracer techniques, which have capability to provide fast, online and effective detections to plant problems, have been continually developed. One of the good potential applications of the radiotracer for troubleshooting in a process plant is the analysis of Residence Time Distribution (RTD). In this paper, the study of RTD in a large scale plant facility using radiotracer technique was presented. The objective of this work is to gain experience on the RTD analysis using radiotracer technique in a “larger than laboratory” scale plant setup which can be comparable to the real industrial application. The experiment was carried out at the sedimentation tank in the water treatment facility of Thailand Institute of Nuclear Technology (Public Organization). Br-82 was selected to use in this work due to its chemical property, its suitable half-life and its on-site availability. NH4Br in the form of aqueous solution was injected into the system as the radiotracer. Six NaI detectors were placed along the pipelines and at the tank in order to determine the RTD of the system. The RTD and the Mean Residence Time (MRT) of the tank was analysed and calculated from the measured data. The experience and knowledge attained from this study is important for extending this technique to be applied to industrial facilities in the future.

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.

Assessment of resident operative performance using a real-time mobile Web system: preparing for the milestone age.

Science.gov (United States)

Wagner, Justin P; Chen, David C; Donahue, Timothy R; Quach, Chi; Hines, O Joe; Hiatt, Jonathan R; Tillou, Areti

2014-01-01

To satisfy trainees' operative competency requirements while improving feedback validity and timeliness using a mobile Web-based platform. The Southern Illinois University Operative Performance Rating Scale (OPRS) was embedded into a website formatted for mobile devices. From March 2013 to February 2014, faculty members were instructed to complete the OPRS form while providing verbal feedback to the operating resident at the conclusion of each procedure. Submitted data were compiled automatically within a secure Web-based spreadsheet. Conventional end-of-rotation performance (CERP) evaluations filed 2006 to 2013 and OPRS performance scores were compared by year of training using serial and independent-samples t tests. The mean CERP scores and OPRS overall resident operative performance scores were directly compared using a linear regression model. OPRS mobile site analytics were reviewed using a Web-based reporting program. Large university-based general surgery residency program. General Surgery faculty used the mobile Web OPRS system to rate resident performance. Residents and the program director reviewed evaluations semiannually. Over the study period, 18 faculty members and 37 residents logged 176 operations using the mobile OPRS system. There were 334 total OPRS website visits. Median time to complete an evaluation was 45 minutes from the end of the operation, and faculty spent an average of 134 seconds on the site to enter 1 assessment. In the 38,506 CERP evaluations reviewed, mean performance scores showed a positive linear trend of 2% change per year of training (p = 0.001). OPRS overall resident operative performance scores showed a significant linear (p = 0.001), quadratic (p = 0.001), and cubic (p = 0.003) trend of change per year of clinical training, reflecting the resident operative experience in our training program. Differences between postgraduate year-1 and postgraduate year-5 overall performance scores were greater with the OPRS (mean = 0.96, CI

Residence time of contaminants released in surface coal mines -- a wind-tunnel study

Energy Technology Data Exchange (ETDEWEB)

Thompson, R.S. [Environmental Protection Agency, Research Triangle Park, NC (United States)

1994-12-31

Surface coal mining operations (blasting, shoveling, loading, trucking, etc.) are sources of airborne particles. The 1990 Clean Air Act Amendments direct the EPA to analyze the accuracy of the Industrial Source Complex model and the AP-42 emission factors, and to make revisions as may be necessary to eliminate any significant over-prediction of air concentration of fugitive particles from surface coal mines. A wind-tunnel study was performed at the US EPA`s Fluid Modeling Facility to investigate dispersion from surface coal mines in support of the dispersion modeling activities. Described here is the portion of the study directed at determining the residence time that material released near the floor of a mine will stay within the mine.

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

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

Taste, choice and timing: Investigating resident and carer preferences for meals in aged care homes.

Science.gov (United States)

Milte, Rachel; Ratcliffe, Julie; Chen, Gang; Miller, Michelle; Crotty, Maria

2018-03-01

There has been little empirical investigation of the preferences of people living in aged care homes for food services. The aim of the present study was to elicit consumer preferences and their willingness to pay for food service in aged care homes. Current residents or their family members were invited to take part in the discrete choice experiment questionnaire administered via interview. Of the 109 eligible residents and 175 eligible family members approached for consent 121 (43%) participated, including 43 residents. Participant preferences were influenced by food taste, choice in relation to serving size, timing of meal selection, visual appeal, and additional cost. Participants indicated they would be willing to pay an additional $24 (US$18.42) per week for food which tasted excellent and $8 (US$6.14) per week to have choice in serving sizes. The study found that respondents were willing to pay a premium to receive food that met their expectations of taste, and for a high level of control over serving sizes, which has implications for the funding and provision of food and dining in long-term care in the future. © 2018 The Authors Nursing & Health Sciences Published by John Wiley & Sons Australia, Ltd.

Measurements of liquid phase residence time distributions in a pilot-scale continuous leaching reactor using radiotracer technique.

Science.gov (United States)

Pant, H J; Sharma, V K; Shenoy, K T; Sreenivas, T

2015-03-01

An alkaline based continuous leaching process is commonly used for extraction of uranium from uranium ore. The reactor in which the leaching process is carried out is called a continuous leaching reactor (CLR) and is expected to behave as a continuously stirred tank reactor (CSTR) for the liquid phase. A pilot-scale CLR used in a Technology Demonstration Pilot Plant (TDPP) was designed, installed and operated; and thus needed to be tested for its hydrodynamic behavior. A radiotracer investigation was carried out in the CLR for measurement of residence time distribution (RTD) of liquid phase with specific objectives to characterize the flow behavior of the reactor and validate its design. Bromine-82 as ammonium bromide was used as a radiotracer and about 40-60MBq activity was used in each run. The measured RTD curves were treated and mean residence times were determined and simulated using a tanks-in-series model. The result of simulation indicated no flow abnormality and the reactor behaved as an ideal CSTR for the range of the operating conditions used in the investigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Variability in Benthic Exchange Rate, Depth, and Residence Time Beneath a Shallow Coastal Estuary

Science.gov (United States)

Russoniello, Christopher J.; Heiss, James W.; Michael, Holly A.

2018-03-01

Hydrodynamically driven benthic exchange of water between the water column and shallow seabed aquifer is a significant and dynamic component of coastal and estuarine fluid budgets. Associated exchange of solutes promotes ecologically important chemical reactions, so quantifying benthic exchange rates, depths, and residence times constrains coastal chemical cycling estimates. We present the first combined field, numerical, and analytical modeling investigation of wave-induced exchange. Temporal variability of exchange was calculated with data collected by instruments deployed in a shallow estuary for 11 days. Differential pressure sensors recorded pressure gradients across the seabed, and up- and down-looking ADCPs recorded currents and pressures to determine wave parameters, surface-water currents, and water depth. Wave-induced exchange was calculated (1) directly from differential pressure measurements, and indirectly with an analytical model based on wave parameters from (2) ADCP and (3) wind data. Wave-induced exchange from pressure measurements and ADCP-measured wave parameters matched well, but both exceeded wind-based values. Exchange induced by tidal pumping and current-bed form interaction—the other primary drivers in shallow coastal waters were calculated from tidal stage variation and ADCP-measured currents. Exchange from waves (mean = 20.0 cm/d; range = 1.75-92.3 cm/d) greatly exceeded exchange due to tides (mean = 3.7 cm/d) and current-bed form interaction (mean = 6.5 × 10-2 cm/d). Groundwater flow models showed aquifer properties affect wave-driven benthic exchange: residence time and depth increased and exchange rates decreased with increasing hydraulic diffusivity (ratio of aquifer permeability to compressibility). This new understanding of benthic exchange will help managers assess its control over chemical fluxes to marine systems.

Assessment of the vaginal residence time of biomarkers of semen exposure.

Science.gov (United States)

Thurman, Andrea; Jacot, Terry; Melendez, Johan; Kimble, Thomas; Snead, Margaret; Jamshidi, Roxanne; Wheeless, Angie; Archer, David F; Doncel, Gustavo F; Mauck, Christine

2016-11-01

The primary objective of this pilot study is to determine and compare the residence time in the vagina of biomarkers of semen exposure for up to 15 days post exposure. The biomarkers are prostate-specific antigen (PSA), Y chromosome DNA, the sex determining region of the Y chromosome (SRY) and testis-specific protein Y-encoded 4 (TSPY4). The secondary objectives are to determine if biomarker concentrations differed between intercourse and inoculation groups, to establish whether the sampling frequency post exposure affected biomarker concentrations and decay profile and to determine if biomarker concentrations in vaginal swabs obtained by the participant at home were similar to swabs obtained by the nurse in the clinic. We randomized healthy women to unprotected intercourse (n=17) versus vaginal inoculation with the male partner's semen in the clinic (n=16). Women were then further randomized to have vaginal swabs obtained at either 7 or 4 time points after semen exposure, up to 15 days post exposure, either obtained at home by the participant or in the clinic by the research nurse. PSA and SRY were markers of recent semen exposure. TSPY4 was detectable in approximately 50% of participants at 15 days post exposure. Unprotected intercourse resulted in significantly higher concentrations of select biomarkers. Sampling frequency and home versus clinic sampling had no significant effect on biomarker concentrations. Objective biomarkers of recent or distant semen exposure may have great utility for verifying protocol compliance in a variety of clinical trials. Copyright © 2016 Elsevier Inc. All rights reserved.

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...

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)

"It's Not Just Time Off": A Framework for Understanding Factors Promoting Recovery From Burnout Among Internal Medicine Residents.

Science.gov (United States)

Abedini, Nauzley C; Stack, Shobha W; Goodman, Jessie L; Steinberg, Kenneth P

2018-02-01

Burnout rates for internal medicine residents are among the highest of all specialties, yet little is known about how residents recover from burnout. We identified factors promoting recovery from burnout and factors that assist with the subsequent avoidance of burnout among internal medicine residents. A purposive sample of postgraduate year 2 (PGY-2), PGY-3, and recent graduates who experienced and recovered from burnout during residency participated in semistructured, 60-minute interviews from June to August 2016. Using qualitative methods derived from grounded theory, saturation of themes occurred after 25 interviews. Coding was performed in an iterative fashion and consensus was reached on major themes. Coding revealed 2 different categories of resident burnout- circumstantial and existential -with differing recovery and avoidance methods. Circumstantial burnout stemmed from self-limited circumstances and environmental triggers. Recovery from, and subsequent avoidance of, circumstantial burnout arose from (1) resolving workplace challenges; (2) nurturing personal lives; and (3) taking time off. In contrast, existential burnout stemmed from a loss of meaning in medicine and an uncertain professional role. These themes were identified around recovery: (1) recognizing burnout and feeling validated; (2) connecting with patients and colleagues; (3) finding meaning in medicine; and (4) redefining a professional identity and role. Our study suggests that residents experience different types of burnout and have variable methods by which they recover from and avoid further burnout. Categorizing residents' burnout into circumstantial versus existential experiences may serve as a helpful framework for formulating interventions.

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

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

Investigation of liquid phase axial dispersion in Taylor bubble flow by radiotracer residence time distribution analysis

Directory of Open Access Journals (Sweden)

Jin J.H.

2013-05-01

Full Text Available A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separated by slugs of pure liquid. This type of flow regime is well suited for solid catalyzed gas-liquid reactors in which the reaction efficiency is a strong function of axial dispersion in the regions of pure liquid. This paper presents an experimental study of liquid phase axial dispersion in a Taylor bubble flow developed in a horizontal tube using high speed photography and radiotracer residence time distribution (RTD analysis. A parametric dependence of axial dispersion on average volume fraction of gas phase was also investigated by varying the relative volumetric flow rates of the two phases. 137mBa produced from a 137Cs/137mBa radionuclide generator was used as radiotracer and measurements were made using the NaI(Tl scintillation detectors. Validation of 137mBa in the form of barium chloride as aqueous phase radiotracer was also carried out. Axial Dispersion Model (ADM was used to simulate the hydrodynamics of the system and the results of the experiment are presented. It was observed that the system is characterized by very high values of Peclet Number (Pe∼102 which reveals an approaching plug type flow. The experimental and model estimated values of mean residence times were observed in agreement with each other.

Time dependence of vacuum arc parameters

International Nuclear Information System (INIS)

Anders, A.; Anders, S.; Brown, I.G.

1993-01-01

Time-resolved investigations of the expanded plasma of vacuum arc cathode spots are described, including the study of the ion charge state distribution, the random cathode spot motion, and the crater formation. It was found that the ion charge state distribution changes over a time scale on the order of hundreds of microseconds. For the random spot motion two time scales were observed: a very short spot residence time of tens of nanoseconds which gives, combined with the step width, the diffusion parameter of the random motion, and a longer time scale on the order of 100 μs during which the diffusion parameter changes. Crater formation studies by scanning electron microscopy indicate the occurrence of larger craters at the end of crater chains. The existence of a time scale, much longer than the elementary times for crater formation and spot residence, can be explained by local heat accumulation

Watershed Influences on Residence Time and Oxygen Reduction Rates in an Agricultural Landscape

Science.gov (United States)

Shope, C. L.; Tesoriero, A. J.

2015-12-01

Agricultural use of synthetic fertilizers and animal manure has led to increased crop production, but also elevated nitrogen concentrations in groundwater, resulting in impaired water quality. Groundwater oxygen concentrations are a key indicator of potential biogeochemical processes, which control water/aquifer interactions and contaminant transport. The U.S. Geological Survey's National Water-Quality Assessment Program has a long-history of studying nutrient transport and processing across the United States and the Glacial Aquifer system in particular. A series of groundwater well networks in Eastern Wisconsin is being used to evaluate the distribution of redox reaction rates over a range of scales with a focus on dissolved O2 reduction rates. An analysis of these multi-scale networks elucidates the influence of explanatory variables (i.e.: soil type, land use classification) on reduction rates and redox reactions throughout the Fox-Wolf-Peshtigo watersheds. Multiple tracers including dissolved gasses, tritium, helium, chlorofluorocarbons, sulfur hexafluoride, and carbon-14 were used to estimate groundwater ages (0.8 to 61.2 yr) at over 300 locations. Our results indicate O2 reduction rates along a flowpath study area (1.2 km2) of 0.15 mg O2 L-1 yr-1 (0.12 to 0.18 mg O2 L-1 yr-1) up to 0.41 mg O2 L-1 yr-1 (0.23 to 0.89 mg O2 L-1 yr-1) for a larger scale land use study area (3,300 km2). Preliminary explanatory variables that can be used to describe the variability in reduction rates include soil type (hydrologic group, bulk density) and chemical concentrations (nitrite plus nitrate, silica). The median residence time expected to reach suboxic conditions (≤ 0.4 mg O2 L-1) for the flowpath and the land use study areas was 66 and 25 yr, respectively. These results can be used to elucidate and differentiate the impact of residence time on groundwater quality vulnerability and sustainability in agricultural regions without complex flow models.

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 ...

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.

Effects of Temperature and Residence Time on the Emissions of PIC and Fine Particles during Fixed Bed Combustion of Conifer Stemwood Pellets

Energy Technology Data Exchange (ETDEWEB)

Boman, Christoffer; Lindmark, Fredrik; Oehman, Marcus; Nordin, Anders [Umeaa Univ. (Sweden). Energy Technology and Thermal Process Chemistry; Pettersson, Esbjoern [Energy Technology Centre, Piteaa (Sweden); Westerholm, Roger [Stockholm Univ., Arrhenius Laboratory (Sweden). Dept. of Analytical Chemistry

2006-07-15

The use of wood fuel Pellets has proved to be well suited for the small-scale market enabling controlled and efficient combustion with low emission of products of incomplete combustion (PIC). Still a potential for further emission reduction exists and a thorough understanding of the influence of combustion conditions on the emission characteristics of air pollutants like PAH and particulate matter (PM) is important. The objective was to determine the effects of temperature and residence time on the emission performance and characteristics with focus on hydrocarbons and PM during combustion of conifer stemwood Pellets in a laboratory fixed bed reactor (<5 kW). Temperature and residence time after the bed section were varied according to statistical experimental designs (650-970 deg C and 0.5-3.5 s) with the emission responses; CO, organic gaseous carbon, NO, 20 VOC compounds, 43 PAH compounds, PM{sub tot}, fine particle mass/count median diameter (MMD and CMD) and number concentration. Temperature was negatively correlated with the emissions of all studied PIC with limited effects of residence time. The PM{sub tot} emissions of 15-20 mg/MJ was in all cases dominated by fine (<1 {mu}m) particles of K, Na, S, Cl, C, O and Zn. Increased residence time resulted in increased fine particle sizes (i.e. MMD and CMD) and decreased number concentrations. The importance of high temperature (>850 deg C) in the bed zone with intensive, air rich and well mixed isothermal conditions for 0.5-1.0 s in the post combustion zone was illustrated for wood Pellets combustion with almost a total depletion of all studied PIC. The results emphasize the need for further verification studies and technology development work.

Spinning Disc Technology – Residence Time Distribution and Efficiency in Textile Wastewater Treatment Application

Science.gov (United States)

Iacob Tudose, E. T.; Zaharia, C.

2018-06-01

The spinning disc (SD) technology has received increased attention in the last years due to its enhanced fluid flow features resulting in improved property transfers. The actual study focuses on characterization of the flow within a spinning disc system based on experimental data used to establish the residence time distribution (RTD) and its dependence on the feeding liquid flowrate and the disc rotational speed. To obtain these data, an inert tracer (sodium chloride) was injected as a pulse input in the liquid stream entering the disc and the salt concentration of the liquid leaving the disc was continuously recorded. The obtained data indicate that an increase in the liquid flowrate from 10 L/h to 30 L/h determines a narrower RTD function. Also, at rotational speed of 200 rpm, the residence time distribution is broader than that for 500 rpm and 800 rpm. The RTD data suggest that depending on the needed flow characteristics, one can choose a certain flowrate and rotational speed domain for its application. Also, the SD technology was used to process textile wastewater treated with bentonite (as both coagulation and discoloration agent) in order to investigate whether the quality indicators such as the total suspended solid content, turbidity and discoloration, can be improved. The experimental results are promising since the discoloration and the removals of suspended solids attained values of over 40%, and respectively, 50 %, depending on the effluent flowrate (10 l/h and 30 L/h), and the disc rotational speed (200 rpm, 550 rpm and 850 rpm) without any other addition of chemicals, or initiation of other simultaneous treatment processes (e.g., advanced oxidative, or reductive, or biochemical processes). This recommends spinning disc technology as a suitable and promising tool to improve different wastewater characteristics.

Spectrum analysis of radiotracer residence time distribution for industrial and environmental applications

International Nuclear Information System (INIS)

Kasban, H.; Ashraf Hamid

2014-01-01

Radiotracer signal analysis and recognition still represents challenges in industrial and environmental applications specially in residence time distribution (RTD) measurement. This paper presents a development for the RTD signal recognition method that is based on power density spectrum (PDS). In this development, the features are extracted from the signals and/or from their higher-orders statistics (HOS) (Bispectrum and Trispectrum) instead of PDS. The HOS are estimated using direct, indirect and parametric estimations. The recognition results are analyzed and compared for different HOS estimation in order to select the best HOS estimation method for the purpose of RTD signal recognition. The artificial neural networks are used for training and testing of the proposed method. The proposed method is tested using RTD signals obtained from the measurements carried out using radiotracer technique. The simulation results show that the parametric estimation of the Trispectrum gives the higher recognition rate and is the most reliable for the RTD signal recognition. (author)

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.

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

A model of environmental behaviour of contaminated dust and its application to determining dust fluxes and residence times

International Nuclear Information System (INIS)

Allott, R.W.; Kelly, M.; Hewitt, C.N.

1994-01-01

A model has been developed to describe the temporal behaviour of the concentrations of a pollutant tracer within the urban environment of Barrow-in-Furness, NW England. The tracer used was 137 Cs derived primarily from wet deposition of the radioactive cloud from the Chernobyl reactor accident. The 137 Cs activity deposited during this primary event was supplemented by a small secondary atmospheric deposition input of resuspended activity. The model was validated against the measured temporal behaviour of 137 Cs in urban dust for two outdoor reservoirs in which the only observed input of dust and activity was by atmospheric deposition. Further modelling studies on other reservoirs (both outdoors and indoors) confirmed the existence of additional input influxes of dust and activity. The model enabled estimates of the magnitudes of these additional fluxes to be made and mean dust mass residence times to be calculated. These residence times correspond to environment half-lives of 170 ± 70 d outdoors and 20 ± 1 d indoors, for reservoirs which only receive a single primary input of a contaminant. Where secondary inputs of pollutants occur, the mean environmental half-lives of the pollutants increase by 50% for outdoor dust reservoirs and over 18-times for indoor reservoirs. This re-contamination of indoor dusts has implications in that attention should be paid to reducing outdoor contamination levels to ensure that attempts to reduce the levels of a pollutant indoors by cleaning are effective. (Author)

Hydraulic paths and estimation of the real residence time of the water in Lago Maggiore (N. Italy: application of massless markers transported in 3D motion fields

Directory of Open Access Journals (Sweden)

Nicoletta Sala

2012-01-01

Full Text Available This study, conducted using the TRIM_LM model, is a continuation of work on the movement of the water mass at different depths in Lago Maggiore, and thus on the estimation of the real residence time of the water in the lake. Three-dimensional CFD numerical simulations were extended to a 4-year period, focusing on the movements of 202 (two hundred and two massless markers inserted at different points in Lago Maggiore and at the mouths of 11 of its tributaries, enabling us to establish more realistic water renewal times for Lago Maggiore. By crossing the data of the horizontal trajectories of the environmental markers with those of their vertical variations, we reconstructed their movements over the four years of the simulation programme. An analysis of the results shows that the water mass in the layers of the upper 100 m has residence times between a minimum of 1 y and a maximum of 4-5 y. The water from the tributaries has residence times between 250 and 1000 days, depending on the distance of the tributaries from the closing section of the lake. The water in the layers below 100 m has residence times that still cannot be quantified with precision, but that can certainly be estimated at a number of years in two figures. These times are strongly conditioned by the depth of the late winter mixing, which in the last 40 y has not exceeded 200 m.

Maximizing time from the constraining European Working Time Directive (EWTD): The Heidelberg New Working Time Model.

Science.gov (United States)

Schimmack, Simon; Hinz, Ulf; Wagner, Andreas; Schmidt, Thomas; Strothmann, Hendrik; Büchler, Markus W; Schmitz-Winnenthal, Hubertus

2014-01-01

The introduction of the European Working Time Directive (EWTD) has greatly reduced training hours of surgical residents, which translates into 30% less surgical and clinical experience. Such a dramatic drop in attendance has serious implications such compromised quality of medical care. As the surgical department of the University of Heidelberg, our goal was to establish a model that was compliant with the EWTD while avoiding reduction in quality of patient care and surgical training. We first performed workload analyses and performance statistics for all working areas of our department (operation theater, emergency room, specialized consultations, surgical wards and on-call duties) using personal interviews, time cards, medical documentation software as well as data of the financial- and personnel-controlling sector of our administration. Using that information, we specifically designed an EWTD-compatible work model and implemented it. Surgical wards and operating rooms (ORs) were not compliant with the EWTD. Between 5 pm and 8 pm, three ORs were still operating two-thirds of the time. By creating an extended work shift (7:30 am-7:30 pm), we effectively reduced the workload to less than 49% from 4 pm and 8 am, allowing the combination of an eight-hour working day with a 16-hour on call duty; thus, maximizing surgical resident training and ensuring patient continuity of care while maintaining EDTW guidelines. A precise workload analysis is the key to success. The Heidelberg New Working Time Model provides a legal model, which, by avoiding rotating work shifts, assures quality of patient care and surgical training.

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

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...

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

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

International Nuclear Information System (INIS)

Engqvist, Anders

2010-09-01

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

Evaluation of quantitative imaging methods for organ activity and residence time estimation using a population of phantoms having realistic variations in anatomy and uptake

International Nuclear Information System (INIS)

He Bin; Du Yong; Segars, W. Paul; Wahl, Richard L.; Sgouros, George; Jacene, Heather; Frey, Eric C.

2009-01-01

Estimating organ residence times is an essential part of patient-specific dosimetry for radioimmunotherapy (RIT). Quantitative imaging methods for RIT are often evaluated using a single physical or simulated phantom but are intended to be applied clinically where there is variability in patient anatomy, biodistribution, and biokinetics. To provide a more relevant evaluation, the authors have thus developed a population of phantoms with realistic variations in these factors and applied it to the evaluation of quantitative imaging methods both to find the best method and to demonstrate the effects of these variations. Using whole body scans and SPECT/CT images, organ shapes and time-activity curves of 111In ibritumomab tiuxetan were measured in dosimetrically important organs in seven patients undergoing a high dose therapy regimen. Based on these measurements, we created a 3D NURBS-based cardiac-torso (NCAT)-based phantom population. SPECT and planar data at realistic count levels were then simulated using previously validated Monte Carlo simulation tools. The projections from the population were used to evaluate the accuracy and variation in accuracy of residence time estimation methods that used a time series of SPECT and planar scans. Quantitative SPECT (QSPECT) reconstruction methods were used that compensated for attenuation, scatter, and the collimator-detector response. Planar images were processed with a conventional (CPlanar) method that used geometric mean attenuation and triple-energy window scatter compensation and a quantitative planar (QPlanar) processing method that used model-based compensation for image degrading effects. Residence times were estimated from activity estimates made at each of five time points. The authors also evaluated hybrid methods that used CPlanar or QPlanar time-activity curves rescaled to the activity estimated from a single QSPECT image. The methods were evaluated in terms of mean relative error and standard deviation of the

Using reactor network for global identification based on residence time distribution theory

Energy Technology Data Exchange (ETDEWEB)

Hocine, S.; Pibouleau, L.; Azzaro-Pantel, C.; Domenech, S. [Laboratoire de Genie Chimique - UMR 5503 CNRS/ INPT ENSIACET, 31 - Toulouse (France)

2006-07-01

In the ventilation systems, the control of transfer contaminants is one of the principal problems during the design and control phases. The installation of a suitable ventilation system for the control of contaminant transfer is essential in industry, because it makes it possible to detect and to prevent chemical and radiological risks. Research on air distribution in ventilated rooms traditionally involves full-scale experiments, scale -model experiments and application of the computational fluid dynamics (C.F.D.) tools. Most of the time, particularly in our case of large and cluttered enclosures, the predictive approach based on C.F.D. codes can not be used. The solution retained here is the establishment of a model based on the well known residence time distribution. This model is widely used in chemical engineering to treat non-ideal flows. The proposed method is based on the experimental determination of the residence time distribution curve, generally obtained through the response of the system to tracer release. A superstructure involving the set of all the possible solutions corresponding to the physical reactor is then defined, and the model will be selected from this superstructure according to its simulated response. The superstructure is identified as a combination of elementary systems, representing ideal flow patterns, as perfect mixed flows, plug flows, continuous stirred tank reactors, etc. The selected model is derived from the comparison between the simulated response to a stimulus, and the experimental response. The structure and parameters of the model are simultaneously optimized in order to fit the experimental curve with a minimal number of elementary units, constituting a key point for future control purposes of the process. This problem is a dynamic M.I.N.L.P. (Mixed Integer Non Linear Programming) problem with bilinear equality constraints. Generally, these constraints lead to numerical difficulties for reaching an optimum solution (even a

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

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.

Residence time as a key for comprehensive assessment of the relationship between changing land use and nitrates in regional groundwater systems.

Science.gov (United States)

Cao, Yingjie; Tang, Changyuan; Song, Xianfang; Liu, Changming; Zhang, Yinghua

2013-04-01

In this study, an approach is put forward to study the relationship between changing land use and groundwater nitrate contamination in the Sanjiang Plain. This approach emphasizes the importance of groundwater residence time when relating the nitrates to the changing land use. The principles underlying the approach involve the assessment of groundwater residence time by CFCs and the Vogel age model and the reconstruction of the land use at the groundwater recharge time by interpolation. Nitrate trend analysis shows that nitrates have begun to leach into the aquifers since agricultural activities boomed after the 1950s. Hydrochemical analysis implies that the possible process relating to the nitrate reduction in the groundwater is the oxidation of Fe(ii)-silicates. However, the chemical kinetics of the oxidation of Fe(ii)-silicates is slow, so this denitrification process contributes little to the nitrate variations. Stepwise regression shows that the nitrate concentrations of samples had no direct relationship with the land use at the groundwater sampling time, but had a relatively strong relationship with the land use at the groundwater recharge time. Dry land is recognized as the dominant factor contributing to the elevated concentration of nitrates. The nitrogen isotope for nitrate (δ(15)N-NO3) gives a more direct result of the identification of nitrate sources: the use of manure in agricultural activities. Principle component (PC) regression shows that the process of the dry land exploitation is the major process that controls the nitrate contamination in the Sanjiang Plain.

Impact of meander geometry and stream flow events on residence times and solute transport in the intra-meander flow

Science.gov (United States)

Nasir Mahmood, Muhammad; Schmidt, Christian; Trauth, Nico

2017-04-01

Stream morphological features, in combination with hydrological variability play a key role in water and solute exchange across surface and subsurface waters. Meanders are prominent morphological features within stream systems which exhibit unique hydrodynamics. The water surface elevation difference across the inner bank of a meander induces lateral hyporheic exchange within the intra-meander region. This hyporheic flow is characterized by considerably prolonged flow paths and residence times (RT) compared to smaller scales of hyporheic exchange. In this study we examine the impact of different meander geometries on the intra-meander hyporheic flow field and solute mobilization under both steady state and transient flow conditions. We developed a number of artificial meander shape scenarios, representing various meander evolution stages, ranging from a typical initial to advanced stage (near cut off ) meander. Three dimensional steady state numerical groundwater flow simulations including the unsaturated zone were performed for the intra-meander region. The meandering stream was implemented in the model by adjusting the top layers of the modelling domain to the streambed elevation and assigning linearly decreasing head boundary conditions to the streambed cells. Residence times for the intra-meander region were computed by advective particle tracking across the inner bank of meander. Selected steady state cases were extended to transient flow simulations to evaluate the impact of stream discharge events on the temporal behavior of the water exchange and solute transport in the intra-meander region. The transient stream discharge was simulated for a number of discharge events of variable duration and peak height using the surface water model HEC-RAS. Transient hydraulic heads obtained from the surface water model were applied as transient head boundary conditions to the streambed cells of the groundwater model. A solute concentration source was added in the

Phase-Type Models of Channel-Holding Times in Cellular Communication Systems

DEFF Research Database (Denmark)

Christensen, Thomas Kaare; Nielsen, Bo Friis; Iversen, Villy Bæk

2004-01-01

In this paper, we derive the distribution of the channel-holding time when both cell-residence and call-holding times are phase-type distributed. Furthermore, the distribution of the number of handovers, the conditional channel-holding time distributions, and the channel-holding time when cell re...... residence times are correlated are derived. All distributions are of phase type, making them very general and flexible. The channel-holding times are of importance in performance evaluation and simulation of cellular mobile communication systems.......In this paper, we derive the distribution of the channel-holding time when both cell-residence and call-holding times are phase-type distributed. Furthermore, the distribution of the number of handovers, the conditional channel-holding time distributions, and the channel-holding time when cell...

Test determination with tritium as a radioactive tracer of the residence time distribution in the stability pool for Cabrero sewage

International Nuclear Information System (INIS)

Diaz, Francisco; Duran, Oscar; Henriquez, Pedro; Vega, Pedro; Padilla, Liliana; Gonzalez, David; Garcia Agudo, Edmundo

2000-01-01

This work was prepared by the Chilean and International Atomic Energy Agencies and covers the hydrodynamic functioning of sewage stability pools using tracers. The plant selected in the city of Cabrero, 500 km. south of Santiago, and is a rectangular facultative pool with a surface area of 7100 m 2 and a maximum volume of 12,327 m2 that receives an average flow of 20 l/s, serving a population of 7000 individuals. The work aims to characterize the runoff from the flow that enters the pool, using a radioactive tracer test, where the incoming water is marked, and its out-coming passage is determined, to establish the residence time distribution. Tritium was selected in the form of tritiated water as a tracer that is precisely emptied into the water flow from the distribution ravine at the lake entrance. Samples are taken at the outflow to determine the concentration of tritium after distillation, simultaneously measuring the flow, to be analyzed in a liquid flicker counter. An average test time of 5.3 days was obtained and an analysis of the residence time distribution for the tracer shows that it leaves quickly and indicates bad flow distribution in the lake with a major short circuit and probable dead zones

Estimation of groundwater residence time and evaluation of geomorphological processes using cosmogenic and terrigenic radionuclides and isotopes of noble gases

International Nuclear Information System (INIS)

Mahara, Yasunori; Ohta, Tomoko; Igarashi, Toshifumi

2013-01-01

In this paper, the estimation of groundwater residence time and geomorphological changing processes are discussed by focusing on isotopes of noble gases and radionuclides with a long half-life as an environmental tracer. Noble gases and radionuclides are produced in the atmospheric air and terrestrial rocks by spallation and various muon reactions during cosmic rays irradiation. Groundwater dating and geomorphological changing are estimated from changes in the number of atoms of cosmogenic and terrigenic nuclides in groundwater and terrestrial rock. The main tools of groundwater dating are combination of the dissolved helium and tritium (half-life T 1/2 =12.3 y) for younger groundwater less than 60 years of residence time, and of the dissolved helium and 36 Cl (T 1/2 =3.01 x 10 5 y) for older groundwater over million years. On the other hand, the main tools on the geomorphological changes are the estimation of exposure time using cosmogenic radionuclides ( 10 Be(half-life T 1/2 =1.6 x 10 6 y), 14 C (T 1/2 =5730 y), 26 Al (T 1/2 =7.16 x 10 5 y) and 36 Cl) and cosmogenic stable noble gases ( 3 He and 21 Ne) produced in rock. (author)

Health care aides use of time in a residential long-term care unit: a time and motion study.

Science.gov (United States)

Mallidou, Anastasia A; Cummings, Greta G; Schalm, Corinne; Estabrooks, Carole A

2013-09-01

Organizational resources such as caregiver time use with older adults in residential long-term care facilities (nursing homes) have not been extensively studied, while levels of nurse staffing and staffing-mix are the focus of many publications on all types of healthcare organizations. Evidence shows that front-line caregivers' sufficient working time with residents is associated with performance, excellence, comprehensive care, quality of outcomes (e.g., reductions in pressure ulcers, urinary tract infections, and falls), quality of life, cost savings, and may be affiliated with transformation of organizational culture. To explore organizational resources in a long-term care unit within a multilevel residential facility, to measure healthcare aides' use of time with residents, and to describe working environment and unit culture. An observational pilot study was conducted in a Canadian urban 52-bed long-term care unit within a faith-based residential multilevel care facility. A convenience sample of seven healthcare aides consented to participate. To collect the data, we used an observational sheet (to monitor caregiver time use on certain activities such as personal care, assisting with eating, socializing, helping residents to be involved in therapeutic activities, paperwork, networking, personal time, and others), semi-structured interview (to assess caregiver perceptions of their working environment), and field notes (to illustrate the unit culture). Three hundred and eighty seven hours of observation were completed. The findings indicate that healthcare aides spent most of their working time (on an eight-hour day-shift) in "personal care" (52%) and in "other" activities (23%). One-to-three minute activities consumed about 35% of the time spent in personal care and 20% of time spent in assisting with eating. Overall, caregivers' time spent socializing was less than 1%, about 6% in networking, and less than 4% in paperwork. Re-organizing healthcare aides

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

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.

Residence time distribution in twin-screw extruders

NARCIS (Netherlands)

Jager, T.

1992-01-01

For the twin-screw extruders used in the food industry at short time high temperature processes the knowledge of their reactor properties is incomplete for mass- and heat flow. Therefore each process change such as: scale-up or product development requires a great number of measurements

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.

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.

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  Communication of "significant" results was more likely to occur via telephone, compared with communication of nonsignificant results. Participation in a shared audit and feedback quality improvement project can improve rates of resident follow-up and communication of results, although communication gaps remained.

A passive heat tracer experiment to determine the seasonal variation in residence times in a managed aquifer recharge system with DTS

NARCIS (Netherlands)

des Tombe, B.F.; Bakker, M.; Schaars, F; van der Made, KJ; Calje, R; Borst, L.

2016-01-01

Targeted provisional session N°8.01 The seasonal variation in residence times is determined in a managed aquifer recharge system using a passive heat tracer test. The managed aquifer recharge system consists of a sequence of alternating elongated recharge basins and rows of recovery wells. The

The cultural differences in time and time management: A socio-demographic approach

Directory of Open Access Journals (Sweden)

F. Venter

2006-12-01

Full Text Available Purpose/Objectives: The aim of this article is to investigate perceived cultural differences in the perceptions of time and time management, and the implications regarding productivity amongst socio-demographic groups in Gauteng. This study indicates that socio-demographic variables such as home language, gender, education, age and income are related to various factors of time perception. Design/Methodology/Approach: The questionnaire consisted of 35 questions to be rated on a five-point Likert scale. Six dimensions of time were measured, namely, the sense of purpose, effective organisation, structured routine, present orientation, persistence and a global time perception. A multi-cultural non-probability convenience sample (n=804 was drawn from residents in the Gauteng region. Respondents were selected from upper- middle- and lowerincome groups residing in various suburban areas and townships in the region. Students of the North-West University carried out the fieldwork. Findings/Implications: The research study found that the dimensions sense of purpose and persistence of time obtained the highest mean factor scores: 4.05 and 3.95 respectively on the 1 (negative to 5 (positive scale, with 87, 4% and 83.8% of the respondents obtaining high scores (above 3.40 respectively. This implies that most respondents felt that they spent their time usefully and meaningfully, while at the same time, would not give up until the task was completed. The dimension present orientation of time produced the lowest mean factor score of 3.09, with 29.4% of respondents obtaining scores below 2.60, indicating a lack of focusing on completing a task at a designated point in time. The study also found that organisations have to increase productivity and reduce costs. The consequences of this for many employees included increased workloads, longer working hours and greater time pressure. Originality/Value: The findings of this study are original and innovative. The

Mean residence times for tritium in some terrestrial plants

International Nuclear Information System (INIS)

Gogate, S.S.; Krishnamoorthy, T.M.; Soman, S.D.

1975-01-01

Uptake of tritiated water from a single or multiple exposure, its fixation and elimination from 3 terrestrial plants, Raphanus sativus L., Amaranthus viridis L. and Phyllanthus fraternus Webster under experimental field conditions are described. Tissue free water tritium (TFWT) attains peak concentration within 4 hr after a single exposure in R. sativus and then decreases with a single component from both leaves and root, with a biological half-time of 36.4 +- 4.2 and 48.5 +- 7.2 hr respectively. TFWT in leaves of A. viridis reaches its peak value within 0.5 hr of exposure and its decay exhibits 2 component fall, one having a very short half-life of 2.4 +- 0.7 hr and the other a long half-time of 86.1 +- 2.0 hr. The two component decay of tritium in TFWT is well represented in P. fraternus. The long-lived components are nearly 8 times of the short-lived ones, both in leaves and stems respectively. Generally, the long -lived component accounts for 15% of the peak TFWT. Tissue bound tritium (TBT) reaches to 4% of TFWT in Phyllanthus sp. TBT elimination time is many times longer than the experimental periods employed in the present study. (author)

Spatial and temporal variation of residence time and storage volume of subsurface water evaluated by multi-tracers approach in mountainous headwater catchments

Science.gov (United States)

Tsujimura, Maki; Yano, Shinjiro; Abe, Yutaka; Matsumoto, Takehiro; Yoshizawa, Ayumi; Watanabe, Ysuhito; Ikeda, Koichi

2015-04-01

Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time and stock information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time and storage volume of subsurface water in time and space at the mountainous headwaters especially with steep slope. We performed an investigation on age dating and estimation of storage volume using simple water budget model in subsurface water with tracing of hydrological flow processes in mountainous catchments underlain by granite, Paleozoic and Tertiary, Yamanashi and Tsukuba, central Japan. We conducted hydrometric measurements and sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2012 in the catchments, and CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Residence time of subsurface water ranged from 11 to 60 years in the granite catchments, from 17 to 32 years in the Paleozoic catchments, from 13 to 26 years in the Tertiary catchments, and showed a younger age during the high-flow season, whereas it showed an older age in the low-flow season. Storage volume of subsurface water was estimated to be ranging from 10 ^ 4 to 10 ^ 6 m3 in the granite catchments, from 10 ^ 5 to 10 ^ 7 m3 in the Paleozoic catchments, from 10 ^ 4 to 10 ^ 6 m3 in the Tertiary catchments. In addition, seasonal change of storage volume in the granite catchments was the highest as compared with those of the Paleozoic and the Tertiary catchments. The results suggest that dynamic change of hydrological process seems to cause a larger variation of the residence time and storage volume of subsurface water in time and space in the granite catchments, whereas higher groundwater recharge rate due to frequent fissures or cracks seems to cause larger

[Fire behavior of Mongolian oak leaves fuel bed under no-wind and zero-slope conditions. II. Analysis of the factors affecting flame length and residence time and related prediction models].

Science.gov (United States)

Zhang, Ji-Li; Liu, Bo-Fei; Di, Xue-Ying; Chu, Teng-Fei; Jin, Sen

2012-11-01

Taking fuel moisture content, fuel loading, and fuel bed depth as controlling factors, the fuel beds of Mongolian oak leaves in Maoershan region of Northeast China in field were simulated, and a total of one hundred experimental burnings under no-wind and zero-slope conditions were conducted in laboratory, with the effects of the fuel moisture content, fuel loading, and fuel bed depth on the flame length and its residence time analyzed and the multivariate linear prediction models constructed. The results indicated that fuel moisture content had a significant negative liner correlation with flame length, but less correlation with flame residence time. Both the fuel loading and the fuel bed depth were significantly positively correlated with flame length and its residence time. The interactions of fuel bed depth with fuel moisture content and fuel loading had significant effects on the flame length, while the interactions of fuel moisture content with fuel loading and fuel bed depth affected the flame residence time significantly. The prediction model of flame length had better prediction effect, which could explain 83.3% of variance, with a mean absolute error of 7.8 cm and a mean relative error of 16.2%, while the prediction model of flame residence time was not good enough, which could only explain 54% of variance, with a mean absolute error of 9.2 s and a mean relative error of 18.6%.

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.

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

Science.gov (United States)

Moody, John A.

2017-01-01

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

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

Associations of psychosocial working conditions and working time characteristics with somatic complaints in German resident physicians.

Science.gov (United States)

Fischer, Nina; Degen, Christiane; Li, Jian; Loerbroks, Adrian; Müller, Andreas; Angerer, Peter

2016-05-01

Somatic complaints (SC) are highly prevalent in working populations and cause suffering and extensive health-care utilization. Adverse psychosocial working conditions as conceptualized in the Job Demand-Control-Support Model (JDC-S) and adverse working time characteristics (WTC) are potential risk factors. This combination is particularly common in hospital physicians. This study examines associations of JDC-S and WTC with SC in resident physicians from Germany. A cross-sectional study was conducted among 405 physicians at the end of residency training. SC were measured using the Giessen Subjective Complaints List (GBB-24) containing the sub-categories exhaustion, gastrointestinal, musculoskeletal, and cardiovascular complaints. Data on working conditions were collected by a self-report method for work analysis in hospitals (TAA-KH-S) and by questions on WTC (i.e., working hours). Multivariable stepwise regression analyses were applied. Workload showed the most pronounced relationship with all sub-categories of SC except gastrointestinal complaints. Job autonomy was not significantly related to any SC sub-category. Social support at work was inversely associated with all SC sub-categories except for cardiovascular complaints. Free weekends were associated with reduced SC except for exhaustion. Shift work was related to an increased SC total score and musculoskeletal complaints. Working hours showed no association with SC. In resident physicians, high workload and shift work are associated with increased SC, while social support at work and free weekends are associated with decreased SC. These insights may inform the development of preventive measures to improve the health of this professional group. Prospective studies are needed though to corroborate our findings.

Creating a Residency Application Personal Statement Writers Workshop: Fostering Narrative, Teamwork, and Insight at a Time of Stress.

Science.gov (United States)

Campbell, Bruce H; Havas, Nancy; Derse, Arthur R; Holloway, Richard L

2016-03-01

Every graduating medical student must write a personal statement for the Electronic Residency Application Service (ERAS), yet there are no widely available resources designed to aid the writing process, causing stress among applicants. The authors offered every Medical College of Wisconsin senior student in the Classes of 2014 and 2015 a voluntary self-contained two-hour Residency Application Personal Statement Writers Workshop. The session included the selection of writing prompts, speedwriting, and a peer-edit critique. Data were gathered before and after each workshop and at the time of ERAS submission. One hundred nine students elected to participate. Of the 96 participants completing a preworkshop questionnaire, only 28 (29%) were comfortable with creative and reflective writing. Fifty-four students completed a follow-up survey after submitting their ERAS application. Fifty-one (94%) found the session effective in getting their personal statement started, and 65 (70%) were surprised by the quality of their writing. Almost all could trace some of their final statement to the workshop. Forty-six (85%) found working with other students helpful, and 49 (91%) would recommend the session to future students; 47 (87%) agreed that the workshop was "fun." The full workshop will be repeated yearly. Workshops will also be offered to residents preparing fellowship applications. A shorter version (without the peer-edit critique) was used successfully with the entire Class of 2016 to help them reflect on their initial clinical encounters. The authors will seek further opportunities to enhance reflection for students, residents, and faculty with these techniques.

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.

INFLUENCE OF RESIDENCE-TIME DISTRIBUTION ON A SURFACE-RENEWAL MODEL OF CONSTANT-PRESSURE CROSS-FLOW MICROFILTRATION

Directory of Open Access Journals (Sweden)

W. Zhang

2015-03-01

Full Text Available Abstract This work examines the influence of the residence-time distribution (RTD of surface elements on a model of cross-flow microfiltration that has been proposed recently (Hasan et al., 2013. Along with the RTD from the previous work (Case 1, two other RTD functions (Cases 2 and 3 are used to develop theoretical expressions for the permeate-flux decline and cake buildup in the filter as a function of process time. The three different RTDs correspond to three different startup conditions of the filtration process. The analytical expressions for the permeate flux, each of which contains three basic parameters (membrane resistance, specific cake resistance and rate of surface renewal, are fitted to experimental permeate flow rate data in the microfiltration of fermentation broths in laboratory- and pilot-scale units. All three expressions for the permeate flux fit the experimental data fairly well with average root-mean-square errors of 4.6% for Cases 1 and 2, and 4.2% for Case 3, respectively, which points towards the constructive nature of the model - a common feature of theoretical models used in science and engineering.

The Effect of Sports and Physical Activity on Elderly Reaction Time and Response Time

Directory of Open Access Journals (Sweden)

Abdolrahman Khezri

2014-07-01

Full Text Available Objectives: Physical activities ameliorate elderly motor and cognitive performance. The aim of this research is to study the effect of sport and physical activity on elderly reaction time and response time. Methods & Materials: The research method is causal-comparative and its statistical population consists of 60 active and non-active old males over 60 years residing at Mahabad city. Reaction time was measured by reaction timer apparatus, made in Takei Company (YB1000 model. Response time was measured via Nelson’s Choice- Response Movement Test. At first, reaction time and then response time was measured. For data analysis, descriptive statistic, K-S Test and One Sample T Test were used Results K-S Test show that research data was parametric. According to the results of this research, physical activity affected reaction time and response time. Results: of T test show that reaction time (P=0.000 and response time (P=0.000 of active group was statistically shorter than non- active group. Conclusion: The result of current study demonstrate that sport and physical activity, decrease reaction and response time via psychomotor and physiological positive changes.

Crystallite size variation of TiO_2 samples depending time heat treatment

International Nuclear Information System (INIS)

Galante, A.G.M.; Paula, F.R. de; Montanhera, M.A.; Pereira, E.A.; Spada, E.R.

2016-01-01

Titanium dioxide (TiO_2) is an oxide semiconductor that may be found in mixed phase or in distinct phases: brookite, anatase and rutile. In this work was carried out the study of the residence time influence at a given temperature in the TiO_2 powder physical properties. After the powder synthesis, the samples were divided and heat treated at 650 °C with a ramp up to 3 °C/min and a residence time ranging from 0 to 20 hours and subsequently characterized by x-ray diffraction. Analyzing the obtained diffraction patterns, it was observed that, from 5-hour residence time, began the two-distinct phase coexistence: anatase and rutile. It also calculated the average crystallite size of each sample. The results showed an increase in average crystallite size with increasing residence time of the heat treatment. (author)

Flow Characterization of Vapor Phase of Geothermal Fluid in Pipe Using Isotope 85Kr and Residence Time Distribution Modeling

Directory of Open Access Journals (Sweden)

S. Sugiharto

2014-08-01

Full Text Available Measurement of vapor flow in geothermal pipe faces great challenges due to fast fluids flow in high-temperature and high-pressure environment. In present study the flow rate measurement has been performed to characterization the geothermal vapor flow in a pipe. The experiment was carried out in a pipe which is connected to a geothermal production well, KMJ-14. The pipe has a 10” outside diameter and contains dry vapor at a pressure of 8 kg/cm2 and a temperature of 170 oC. Krypton-85 gas isotope (85Kr has been injected into the pipe. Three collimated radiation detectors positioned respectively at 127, 177 and 227m from injection point were used to obtain experimental data which represent radiotracer residence time distribution (RTD in the pipe. The last detector at the position of 227 m did not respond, which might be due to problems in cable connections. Flow properties calculated using mean residence time (MRT shows that the flow rate of the vapor in pipe is 10.98 m/s, much faster than fluid flow commonly found in various industrial process plants. Best fitting evaluated using dedicated software developed by IAEA expert obtained the Péclet number Pe as 223. This means that the flow of vapor of geothermal fluids in pipe is plug flow in character. The molecular diffusion coefficient is 0.45 m2/s, calculated from the axial dispersion model.

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.

Prolonged naproxen joint residence time after intra-articular injection of lipophilic solutions comprising a naproxen glycolamide ester prodrug in the rat

DEFF Research Database (Denmark)

Thing, Mette; Lu, Yi; Agårdh, Li

2013-01-01

time. Two oils, medium-chain triglycerides and castor oil, differing with respect to viscosity were tested. After intra-articular administration of oil prodrug solutions, a significant increase in the time to maximum naproxen serum concentration from around 40 to 245min, an increase in the MRTj from......Intra-articular injection of oil solutions of lipophilic prodrugs that rapidly degrade to their parent compound in synovial fluid may constitute a feasible approach to increase the joint residence time of non-steroidal anti-inflammatory drugs. In this in vivo study, oil solutions of the N......,N-diethyl glycolamide ester prodrug of naproxen (16mg/ml) were injected into the rat knee joint by dosing 6μl formulation per 100g body weight. The sustained release properties were compared to those of intra-articularly injected aqueous and oil solutions of naproxen by monitoring the naproxen serum concentrations over...

Teaching leadership in trauma resuscitation: Immediate feedback from a real-time, competency-based evaluation tool shows long-term improvement in resident performance.

Science.gov (United States)

Gregg, Shea C; Heffernan, Daithi S; Connolly, Michael D; Stephen, Andrew H; Leuckel, Stephanie N; Harrington, David T; Machan, Jason T; Adams, Charles A; Cioffi, William G

2016-10-01

Limited data exist on how to develop resident leadership and communication skills during actual trauma resuscitations. An evaluation tool was developed to grade senior resident performance as the team leader during full-trauma-team activations. Thirty actions that demonstrated the Accreditation Council for Graduate Medical Education core competencies were graded on a Likert scale of 1 (poor) to 5 (exceptional). These actions were grouped by their respective core competencies on 5 × 7-inch index cards. In Phase 1, baseline performance scores were obtained. In Phase 2, trauma-focused communication in-services were conducted early in the academic year, and immediate, personalized feedback sessions were performed after resuscitations based on the evaluation tool. In Phase 3, residents received only evaluation-based feedback following resuscitations. In Phase 1 (October 2009 to April 2010), 27 evaluations were performed on 10 residents. In Phase 2 (April 2010 to October 2010), 28 evaluations were performed on nine residents. In Phase 3 (October 2010 to January 2012), 44 evaluations were performed on 13 residents. Total scores improved significantly between Phases 1 and 2 (p = 0.003) and remained elevated throughout Phase 3. When analyzing performance by competency, significant improvement between Phases 1 and 2 (p competencies (patient care, knowledge, system-based practice, practice-based learning) with the exception of "communication and professionalism" (p = 0.56). Statistically similar scores were observed between Phases 2 and 3 in all competencies with the exception of "medical knowledge," which showed ongoing significant improvement (p = 0.003). Directed resident feedback sessions utilizing data from a real-time, competency-based evaluation tool have allowed us to improve our residents' abilities to lead trauma resuscitations over a 30-month period. Given pressures to maximize clinical educational opportunities among work-hour constraints, such a model may help

Chalk Catchment Transit Time: Unresolved Issues

Energy Technology Data Exchange (ETDEWEB)

Darling, W. G.; Gooddy, D. C. [British Geological Survey, Crowmarsh Gifford, Wallingford, Oxfordshire (United Kingdom); Barker, J. A. [School of Civil Engineering and the Environment, University of Southampton, Southampton (United Kingdom); Robinson, M. [Centre for Ecology and Hydrology, Crowmarsh Gifford, Wallingford, Oxfordshire (United Kingdom)

2013-07-15

The mean transit time (MTT) of a catchment is the average residence time of water from rainfall to river outflow at the foot of the catchment. As such, MTT has important water quality as well as resource implications. Many catchments worldwide have been measured for MTT using environmental isotopes, yet the Chalk, an important aquifer in NW Europe, has received little attention in this regard. The catchment of the River Lambourn in southern England has been intermittently studied since the 1960s using isotopic methods. A tritium peak measured in the river during the 1970s indicates an apparent MTT of {approx}15 years, but the thick unsaturated zone (average {approx}50 m) of the catchment suggests that the MTT should be much greater because of the average downward movement through the Chalk of {approx}1 m/a consistently indicated by tritium and other tracers. Recent work in the catchment using SF{sub 6} as a residence time indicator has given groundwater ages in the narrow range 11-18 yrs, apparently supporting the river tritium data but in conflict with the unsaturated zone data even allowing for a moderate proportion of rapid bypass flow. The MTT of the catchment remains unresolved for the time being. (author)

RESIDENCE TIMES OF PARTICLES IN DIFFUSIVE PROTOPLANETARY DISK ENVIRONMENTS. I. VERTICAL MOTIONS

International Nuclear Information System (INIS)

Ciesla, F. J.

2010-01-01

The chemical and physical evolution of primitive materials in protoplanetary disks are determined by the types of environments they are exposed to and their residence times within each environment. Here, a method for calculating representative paths of materials in diffusive protoplanetary disks is developed and applied to understanding how the vertical trajectories that particles take impact their overall evolution. The methods are general enough to be applied to disks with uniform diffusivity, the so-called constant-α cases, and disks with a spatially varying diffusivity, such as expected in 'layered-disks'. The average long-term dynamical evolution of small particles and gaseous molecules is independent of the specific form of the diffusivity in that they spend comparable fractions of their lifetimes at different heights in the disk. However, the paths that individual particles and molecules take depend strongly on the form of the diffusivity leading to a different range of behavior of particles in terms of deviations from the mean. As temperatures, gas densities, chemical abundances, and photon fluxes will vary with height in protoplanetary disks, the different paths taken by primitive materials will lead to differences in their chemical and physical evolution. Examples of differences in gas phase chemistry and photochemistry are explored here. The methods outlined here provide a powerful tool that can be integrated with chemical models to understand the formation and evolution of primitive materials in protoplanetary disks on timescales of 10 5 -10 6 years.

RESIDENCE TIMES OF PARTICLES IN DIFFUSIVE PROTOPLANETARY DISK ENVIRONMENTS. II. RADIAL MOTIONS AND APPLICATIONS TO DUST ANNEALING

International Nuclear Information System (INIS)

Ciesla, F. J.

2011-01-01

The origin of crystalline grains in comets and the outer regions of protoplanetary disks remains a mystery. It has been suggested that such grains form via annealing of amorphous precursors in the hot, inner region of a protoplanetary disk, where the temperatures needed for such transformations were found, and were then transported outward by some dynamical means. Here we develop a means of tracking the paths that dust grains would have taken through a diffusive protoplanetary disk and examine the types and ranges of environments that particles would have seen over a 10 6 yr time period in the dynamic disk. We then combine this model with three annealing laws to examine how the dynamic evolution of amorphous grains would have led to their physical restructuring and their delivery to various regions of the disk. It is found that 'sibling particles' - those particles that reside at the same location at a given period of time-take a wide range of unique and independent paths through the disk to arrive there. While high temperatures can persist in the disk for very long time periods, we find that those grains that are delivered to the cold outer regions of the disk are largely annealed in the first few x10 5 yr of disk history. This suggests that the crystallinity of grains in the outer disk would be determined early and remain unchanged for much of disk history, in agreement with recent astronomical observations.

Time use and rurality – Canada 2005

OpenAIRE

Hugh Millward; Jamie Spinney

2009-01-01

This paper provides a preliminary assessment of rurality as a factor affecting where and how people use their time, in a North American context. Rurality is a complex concept, but two key aspects are the degree of urban influence, and economic dependence on resource industries (farming and fishing particularly). Using dichotomous variables from the 2005 Canadian time use survey, we find that rural residence and resource employment both strongly influence time use and travel behaviour. Respond...

Flow pattern and residence time of groundwater within the south-eastern Taoudeni sedimentary basin (Burkina Faso, Mali)

Science.gov (United States)

Huneau, F.; Dakoure, D.; Celle-Jeanton, H.; Vitvar, T.; Ito, M.; Traore, S.; Compaore, N. F.; Jirakova, H.; Le Coustumer, P.

2011-10-01

SummaryThe knowledge about groundwater flow conditions within the Southeastern Taoudeni Basin Aquifer shared by Burkina Faso and Mali is relatively limited with very little information on potentiometric heads, recharge processes, residence time and water quality. A better evaluation of groundwater resources in this area is a strategic point for water resources management in the entire Soudano-Sahelian region which endures since the beginning of the twentieth century a continuous decrease in precipitation amount. This paper provides a transboundary synthesis using water ( 18O, 2H and 3H) and carbon isotopes ( 13C and 14C) in conjunction with hydrogeological and hydrochemical data. The objectives are to improve the conceptual model of groundwater recharge and flow within this sandstone reservoir, and to assess the changes in the aquifer due to water abstraction and recent climate changes including an insight into Sahelian aquifers palaeorecharge processes. The local meteoric water line for the Bobo-Dioulasso station is proposed: δ 2H = 8.0 (±0.5)δ 18O + 10.2 (±2.1). Two main tendencies can be derived from groundwater chemistry. First, a slight evolution from the Ca-Mg-HCO 3 type towards a Na-K-HCO 3 type that indicates developed interactions between groundwater and clay minerals related to the residence time of groundwater. A second tendency towards Cl-NO 3-SO 4-HCO 3 water types indicates the anthropogenic influence on groundwater related to the poor sanitary conditions observed around wells. The carbon-14 activity measured on the TDIC varies between 0.3 and 122 pmC, so our record contains samples covering a wide period from Actual to Pleistocene suggesting a continuous recharge of the system through time even if the Sahel region has endured many different climate phases which have influenced the infiltration and recharge processes. All groundwater samples have stable isotope compositions in the range of the present day regional and global meteoric water line

Use of multiple age tracers to estimate groundwater residence times and long-term recharge rates in arid southern Oman

International Nuclear Information System (INIS)

Müller, Th.; Osenbrück, K.; Strauch, G.; Pavetich, S.; Al-Mashaikhi, K.-S.; Herb, C.; Merchel, S.; Rugel, G.; Aeschbach, W.; Sanford, W.

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, "1"4C and "3"6Cl 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  100 ka in the central section north of the mountains, and up to and > one Ma in the Empty Quarter. The "1"4C data were used to help calibrate the "4He and "3"6Cl data. Mixing models suggest that long open boreholes north of the mountains compromise "1"4C-only interpretations there, in contrast to "4He and "3"6Cl 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, δ"2H and δ"1"8O 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. - Highlights: • Multiple age tracers are required for the interpretation of the groundwater system. • Different tracers are applicable along different sections of the flowpath. • Groundwater residence times >1 Ma have been determined for the northern Najd area.

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

International Nuclear Information System (INIS)

Han, Dongmei; Cao, Guoliang; McCallum, James; Song, Xianfang

2015-01-01

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_3"− 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"1"8O, δ"2H) analysis, "3H 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_3"− 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_3"− 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 transported for tens of years, through the

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

Impact of solids residence time on biological nutrient removal performance of membrane bioreactor.

Science.gov (United States)

Ersu, Cagatayhan Bekir; Ong, Say Kee; Arslankaya, Ertan; Lee, Yong-Woo

2010-05-01

Impact of long solids residence times (SRTs) on nutrient removal was investigated using a submerged plate-frame membrane bioreactor with anaerobic and anoxic tanks. The system was operated at 10, 25, 50 and 75 days SRTs with hydraulic retention times (HRTs) of 2 h each for the anaerobic and anoxic tanks and 8 h for the oxic tank. Recirculation of oxic tank mixed liquor into the anaerobic tank and permeate into the anoxic tank were fixed at 100% each of the influent flow. For all SRTs, percent removals of soluble chemical oxygen demand were more than 93% and nitrification was more than 98.5% but total nitrogen percent removal seemed to peak at 81% at 50 days SRT while total phosphorus (TP) percent removal showed a deterioration from approximately 80% at 50 days SRT to 60% at 75 days SRT. Before calibrating the Biowin((R)) model to the experimental data, a sensitivity analysis of the model was conducted which indicated that heterotrophic anoxic yield, anaerobic hydrolysis factors of heterotrophs, heterotrophic hydrolysis, oxic endogenous decay rate for heterotrophs and oxic endogenous decay rate of PAOs had the most impact on predicted effluent TP concentration. The final values of kinetic parameters obtained in the calibration seemed to imply that nitrogen and phosphorus removal increased with SRT due to an increase in anoxic and anaerobic hydrolysis factors up to 50 days SRT but beyond that removal of phosphorus deteriorated due to high oxic endogenous decay rates. This indirectly imply that the decrease in phosphorus removal at 75 days SRT may be due to an increase in lysis of microbial cells at high SRTs along with the low food/microorganisms ratio as a result of high suspended solids in the oxic tank. Several polynomial correlations relating the various calibrated kinetic parameters with SRTs were derived. The Biowin((R)) model and the kinetic parameters predicted by the polynomial correlations were verified and found to predict well the effluent water quality

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

Physical Activity, Study Sitting Time, Leisure Sitting Time, and Sleep Time Are Differently Associated With Obesity in Korean Adolescents: A Population-Based Study.

Science.gov (United States)

Kong, Il Gyu; Lee, Hyo-Jeong; Kim, So Young; Sim, Songyong; Choi, Hyo Geun

2015-11-01

Low physical activity, long leisure sitting time, and short sleep time are risk factors for obesity, but the association with study sitting time is unknown. The objective of this study was to evaluate the association between these factors and obesity.We analyzed the association between physical activity, study sitting time, leisure sitting time, and sleep time and subject weight (underweight, healthy weight, overweight, and obese), using data from a large population-based survey, the 2013 Korea Youth Risk Behavior Web-based Survey. Data from 53,769 participants were analyzed using multinomial logistic regression analyses with complex sampling. Age, sex, region of residence, economic level, smoking, stress level, physical activity, sitting time for study, sitting time for leisure, and sleep time were adjusted as the confounders.Low physical activity (adjusted odds ratios [AORs] = 1.03, 1.12) and long leisure sitting time (AORs = 1.15, 1.32) were positively associated with overweight and obese. Low physical activity (AOR = 1.33) and long leisure sitting time (AOR = 1.12) were also associated with underweight. Study sitting time was negatively associated with underweight (AOR = 0.86) but was unrelated to overweight (AOR = 0.97, 95% confidence interval [CI] = 0.91-1.03) and obese (AOR = 0.94, 95% CI = 0.84-1.04). Sleep time (physical activity, decreasing leisure sitting time, and obtaining sufficient sleep would be beneficial in maintaining a healthy weight. However, study sitting time was not associated with overweight or obese.

[Part-time medical specialist training; experiences with job-sharing for trainee internists].

Science.gov (United States)

Bevers, K; Nauta, S; Stuyt, P M

2004-02-14

Due to various factors such as social changes, an increasing number of couples with two incomes, and a growing proportion of female doctors, there has been a growing demand for part-time work in recent years. This is also true for resident physicians. Objections such as a discontinuity in care and the decline in the quality of education frequently prevent resident physicians from working part-time. Over the past two years, the University Medical Centre Nijmegen, the Netherlands, has experimented with job-sharing on clinical wards for resident physicians in internal medicine. This approach works well in practice, as long as a number of conditions, including the proper transfer of medical information and good communication, are satisfied. Job-sharing is one means of satisfying the growing demand for part-time work among resident physicians and specialists.

Cost analysis of nursing home registered nurse staffing times.

Science.gov (United States)

Dorr, David A; Horn, Susan D; Smout, Randall J

2005-05-01

To examine potential cost savings from decreased adverse resident outcomes versus additional wages of nurses when nursing homes have adequate staffing. A retrospective cost study using differences in adverse outcome rates of pressure ulcers (PUs), urinary tract infections (UTIs), and hospitalizations per resident per day from low staffing and adequate staffing nursing homes. Cost savings from reductions in these events are calculated in dollars and compared with costs of increasing nurse staffing. Eighty-two nursing homes throughout the United States. One thousand three hundred seventy-six frail elderly long-term care residents at risk of PU development. Event rates are from the National Pressure Ulcer Long-Term Care Study. Hospital costs are estimated from Medicare statistics and from charges in the Healthcare Cost and Utilization Project. UTI costs and PU costs are from cost-identification studies. Time horizon is 1 year; perspectives are societal and institutional. Analyses showed an annual net societal benefit of 3,191 dollars per resident per year in a high-risk, long-stay nursing home unit that employs sufficient nurses to achieve 30 to 40 minutes of registered nurse direct care time per resident per day versus nursing homes that have nursing time of less than 10 minutes. Sensitivity analyses revealed a robust set of estimates, with no single or paired elements reaching the cost/benefit equality threshold. Increasing nurse staffing in nursing homes may create significant societal cost savings from reduction in adverse outcomes. Challenges in increasing nurse staffing are discussed.

Characterization of the Gacka River basin karst aquifer (Croatia): Hydrochemistry, stable isotopes and tritium-based mean residence times

Energy Technology Data Exchange (ETDEWEB)

Ozyurt, Nur N. [Department of Geological Engineering, Hacettepe University, 06800 Ankara (Turkey); Lutz, Hans O. [Stable Isotope Laboratory, Medical Faculty, Rijeka University, 51000 Rijeka (Croatia); Faculty of Physics, Bielefeld University, 33615 Bielefeld (Germany); Hunjak, Tamara; Mance, Diana [Stable Isotope Laboratory, Medical Faculty, Rijeka University, 51000 Rijeka (Croatia); Roller-Lutz, Zvjezdana, E-mail: roller@medri.uniri.hr [Stable Isotope Laboratory, Medical Faculty, Rijeka University, 51000 Rijeka (Croatia)

2014-07-01

The Gacka River basin aquifer is a highly-developed karst system, located in the Croatian Dinarides. It is mostly composed of permeable Jurassic and Cretaceous carbonate rocks, and clastic sedimentary rocks of Paleogene age. Gacka River provides high quality water for the town of Otočac and several villages; together with the neighboring Lika River, the water is used for the Hydroelectric Power Plant at Senj on the coast. About 10 perennial and over 20 seasonal springs are located at 450 to 460 m a.s.l. (above sea level). Three major springs (Pećina, Majerovo and Tonkovića) provide 57% of the mean annual river flow. Similarities between the average groundwater temperatures as well as between the average specific electrical conductivity values (9.0 °C-328 μS/cm, 9.6 °C-350 μS/cm and 8.9 °C-312 μS/cm) of the springs imply that they are fed from aquifers with similar mean residence times (MRTs). The mean δ{sup 18}O contents of Majerovo, Tonkovića, and Pećina are around − 10.1‰, − 9.2‰ and − 8.9‰, respectively, revealing differences in the mean recharge area elevations. Compared to the temporal amplitude of the{sup 18}O signal of precipitation, the {sup 18}O signal variations of the springs are substantially attenuated because the recharges occurring at different times are well mixed within the aquifers. This indicates MRTs of more than just a few years. The average tritium contents of Pećina, Majerovo and Tonkovića are 5.48 TU, 6.13 TU and 6.17 TU, respectively. Serially connected exponential-plug type unsteady lumped-parameter models run on an annual time scale resulted in rather satisfactory matches between the observed and calculated tritium contents for all studied springs. The models revealed similar MRTs (and corresponding reservoir volumes) for Pećina, Tonkovića and Majerovo of 12 years (470 Mm{sup 3}), 12 years (1190 Mm{sup 3}), and 12.2 years (1210 Mm{sup 3}), respectively. Plug flow conditions dominate in about 90% of the total

Determination of residence times of ions in a resistive glass selected ion flow-drift tube using the Hadamard transformation.

Science.gov (United States)

Spesyvyi, Anatolii; Španěl, Patrik

2015-09-15

Selected ion flow tube mass spectrometry, SIFT-MS, used for trace gas analyses has certain fundamental limitations that could be alleviated by adding a facility that allows reaction times and ion interaction energies to be varied. Thus, a selected ion flow-drift tube, SIFDT, has been created to explore the influence of an embedded electric field on these parameters and on reaction processes. The new SIFTD instrument was constructed using a miniature resistive glass drift tube. Arrival times of ions, t, analysed by a downstream quadrupole mass spectrometer over the m/z range 10-100 were studied by modulating the injected ion current using a gate lens. Single pulse modulation was compared with pseudorandom time multiplexing exploiting the Hadamard transformation. A simple model involving analysis of ethanol and water vapour mixture in air was used to explore the advantages of the SIFDT concept to SIFT-MS analysis. It is shown that the resistive glass drift tube is suitable for SIFDT experiments. The Hadamard transformation can be used to routinely determine reagent ion residence time in the flow-drift tube and also to observe differences in arrival times for different product ions. Two-dimensional data combining arrival time and mass spectra can be obtained rapidly. The calculated ion drift velocities vary with the reduced field strength, E/N, and the calculated ion mobilities agree with theoretical and previous literature values. This study has provided evidence that the SIFDT-MS technique can be implemented in a miniature and low-cost instrument and two- or three-dimensional data can be obtained (product ion count rates as functions of m/z, t and E/N) using the Hadamard transformation thus providing exciting possibilities for further analytical additions and extensions of the SIFT-MS technique. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Dead time effects in laser Doppler anemometry measurements

DEFF Research Database (Denmark)

Velte, Clara Marika; Buchhave, Preben; George, William K.

2014-01-01

frequency range, starting around the cutoff frequency due to the finite size of the MV. Using computer-generated data mimicking the LDA data, these effects have previously been shown to appear due to the effect of dead time, i.e., the finite time during which the system is not able to acquire new...... measurements. These dead times can be traced back to the fact that the burst-mode LDA cannot measure more than one signal burst at a time. Since the dead time is approximately equal to the residence time for a particle traversing a measurement volume, we are dealing with widely varying dead times, which...

Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

International Nuclear Information System (INIS)

Ahmed, A.A.; Mohamed, A.; Ali, A.E.; Barakat, A.; Abd El-Hady, M.; El-Hussein, A.

2004-01-01

During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived ( 222 Rn) decay products 214 Pb and 210 Pb. The samples were taken by using a single-filter technique and γ-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214 Pb and 210 Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214 Pb and 210 Pb within the whole year was found to be 1.4±0.27 Bq m -3 and 1.2±0.15 mBq m -3 , respectively. Different 210 Pb: 214 Pb activity ratios during the year varied between 1.78x10 -4 and 1.6x10 -3 with a mean value of 8.9x10 -4 ±7.6x10 -5 . From the ratio between the activity concentrations of the radon decay products 214 Pb and 210 Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5±0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air

Impacts of Streambed Heterogeneity and Anisotropy on Residence Time of Hyporheic Zone.

Science.gov (United States)

Liu, Suning; Chui, Ting Fong May

2018-05-01

The hyporheic zone (HZ), which is the region beneath or alongside a streambed, plays an important role in the stream's ecology. The duration that a water molecule or a solute remains within the HZ, or residence time (RT), is one of the most common metrics used to evaluate the function of the HZ. The RT is greatly influenced by the streambed's hydraulic conductivity (K), which is intrinsically difficult to characterize due to its heterogeneity and anisotropy. Many laboratory and numerical studies of the HZ have simplified the streambed K to a constant, thus producing RT values that may differ from those gathered from the field. Some studies have considered the heterogeneity of the HZ, but very few have accounted for anisotropy or the natural K distributions typically found in real streambeds. This study developed numerical models in MODFLOW to examine the influence of heterogeneity and anisotropy, and that of the natural K distribution in a streambed, on the RT of the HZ. Heterogeneity and anisotropy were both found to shorten the mean and median RTs while increasing the range of the RTs. Moreover, heterogeneous K fields arranged in a more orderly pattern had longer RTs than those with random K distributions. These results could facilitate the design of streambed K values and distributions to achieve the desired RT during river restoration. They could also assist the translation of results from the more commonly considered homogeneous and/or isotropic conditions into heterogeneous and anisotropic field situations. © 2017, National Ground Water Association.

Investigating the Role of Hydrologic Residence Time in Nitrogen Transformations at the Sediment-Water Interface using Controlled Variable Head Experiments

Science.gov (United States)

Hampton, T. B.; Zarnetske, J. P.; Briggs, M. A.; Singha, K.; Day-Lewis, F. D.

2017-12-01

Many important biogeochemical processes governing both carbon and nitrogen dynamics in streams take place at the sediment-water interface (SWI). This interface is highly variable in biogeochemical function, with stream stage often influencing the magnitude and direction of water and solute exchange through the SWI. It is well known that the SWI can be an important location for carbon and nitrogen transformations, including denitrification and greenhouse gas production. The degree of mixing of carbon and nitrate, along with oxygen from surface waters, is strongly influenced by hydrologic exchange at the SWI. We hypothesize that hydrologic residence time, which is also determined by the magnitude of exchange, is a key control on the fate of nitrate at the SWI and on the end products of denitrification. Previous studies in the headwaters of the Ipswich River in MA as part of the Lotic Intersite Nitrogen Experiments (LINX II) and other long-term monitoring suggest that the Ipswich River SWI represents an important source of nitrous oxide, a potent greenhouse gas. Using a novel constant-head infiltrometer ring embedded in the stream sediments, we created four unique controlled down-welling (i.e., recharge) conditions, and tested how varying this hydrologic flux and thus the residence time distribution influenced biogeochemical function of the Ipswich River SWI. Specifically, we added isotopically-labelled 15N-nitrate to stream water during each controlled hydrologic flux experiment to quantify nitrate transformation rates, including denitrification end products, under the different hydrologic conditions. We also measured a suite of carbon and nitrogen solutes, along with dissolved oxygen conditions throughout each experiment to characterize the broader residence timescale and biogeochemical responses to the hydrologic manipulations. Initial results show that the oxic conditions of the SWI were strongly responsive to changes in hydrologic flux rates, thereby changing the

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.

Comment on "Scrutinizing the carbon cycle and CO2residence time in the atmosphere" by H. Harde

Science.gov (United States)

Köhler, Peter; Hauck, Judith; Völker, Christoph; Wolf-Gladrow, Dieter A.; Butzin, Martin; Halpern, Joshua B.; Rice, Ken; Zeebe, Richard E.

2018-05-01

Harde (2017) proposes an alternative accounting scheme for the modern carbon cycle and concludes that only 4.3% of today's atmospheric CO2 is a result of anthropogenic emissions. As we will show, this alternative scheme is too simple, is based on invalid assumptions, and does not address many of the key processes involved in the global carbon cycle that are important on the timescale of interest. Harde (2017) therefore reaches an incorrect conclusion about the role of anthropogenic CO2 emissions. Harde (2017) tries to explain changes in atmospheric CO2 concentration with a single equation, while the most simple model of the carbon cycle must at minimum contain equations of at least two reservoirs (the atmosphere and the surface ocean), which are solved simultaneously. A single equation is fundamentally at odds with basic theory and observations. In the following we will (i) clarify the difference between CO2 atmospheric residence time and adjustment time, (ii) present recently published information about anthropogenic carbon, (iii) present details about the processes that are missing in Harde (2017), (iv) briefly discuss shortcoming in Harde's generalization to paleo timescales, (v) and comment on deficiencies in some of the literature cited in Harde (2017).

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)

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.

Reduced variability and execution time to reach a target with a needle GPS system: Comparison between physicians, residents and nurse anaesthetists.

Science.gov (United States)

Fevre, Marie-Cécile; Vincent, Caroline; Picard, Julien; Vighetti, Arnaud; Chapuis, Claire; Detavernier, Maxime; Allenet, Benoît; Payen, Jean-François; Bosson, Jean-Luc; Albaladejo, Pierre

2018-02-01

Ultrasound (US) guided needle positioning is safer than anatomical landmark techniques for central venous access. Hand-eye coordination and execution time depend on the professional's ability, previous training and personal skills. Needle guidance positioning systems (GPS) may theoretically reduce execution time and facilitate needle positioning in specific targets, thus improving patient comfort and safety. Three groups of healthcare professionals (41 anaesthesiologists and intensivists, 41 residents in anaesthesiology and intensive care, 39 nurse anaesthetists) were included and required to perform 3 tasks (positioning the tip of a needle in three different targets in a silicon phantom) by using successively a conventional US-guided needle positioning and a needle GPS. We measured execution times to perform the tasks, hand-eye coordination and the number of repositioning occurrences or errors in handling the needle or the probe. Without the GPS system, we observed a significant inter-individual difference for execution time (Pgaming were found to be independent factors associated with a shorter execution time. Use of GPS attenuated the inter-individual and group variability. We observed a reduced execution time and improved hand-eye coordination in all groups as compared to US without GPS. Neither US training, video gaming nor demographic personal or professional factors were found to be significantly associated with reduced execution time when GPS was used. US associated with GPS systems may improve safety and decrease execution time by reducing inter-individual variability between professionals for needle-handling procedures. Copyright © 2016 Société française d'anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

On the late-time behavior of tracer test breakthrough curves

Energy Technology Data Exchange (ETDEWEB)

HAGGERTY, ROY; MCKENNA, SEAN A; MEIGS, LUCY C

2000-06-12

The authors investigated the late-time (asymptotic) behavior of tracer test breakthrough curves (BTCs) with rate-limited mass transfer (e.g., in dual or multi-porosity systems) and found that the late-time concentration, c, is given by the simple expression: c = t{sub ad} (c{sub 0}g {minus} m{sub 0}{partial_derivative}g/{partial_derivative}t), for t >> t{sub ad} and t{sub a} >> t{sub ad} where t{sub ad} is the advection time, c{sub 0} is the initial concentration in the medium, m{sub 0} is the 0th moment of the injection pulse; and t{sub a} is the mean residence time in the immobile domain (i.e., the characteristic mass transfer time). The function g is proportional to the residence time distribution in the immobile domain, the authors tabulate g for many geometries, including several distributed (multirate) models of mass transfer. Using this expression they examine the behavior of late-time concentration for a number of mass transfer models. One key results is that if rate-limited mass transfer causes the BTC to behave as a power-law at late-time (i.e., c {approximately} t{sup {minus}k}), then the underlying density function of rate coefficients must also be a power-law with the form a{sup k{minus}}, as a {r_arrow}0. This is true for both density functions of first-order and diffusion rate coefficients. BTCs with k < 3 persisting to the end of the experiment indicate a mean residence time longer than the experiment and possibly infinite, and also suggest an effective rate coefficient that is either undefined or changes as a function of observation time. They apply their analysis to breakthrough curves from Single-Well Injection-Withdrawal tests at the Waste Isolation Pilot Plant, New Mexico.

LEISURE TIME FOR SECONDARY SCHOOL STUDENTS

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Besa Havziu

2015-06-01

Full Text Available Today, in education prevails the paradigm that is geared towards the complete and varied development of a person. This implies the development of the students ability for self-determination towards various other perspective offered by contemporary social residence. Meanwhile in the time of adolescence, the youth experience serious crises regarding their identity, in which the free time and the activities during the free time can be positively used with a cause to be interrupted unconstructive and chaotic use of the free time by the youth. In this thesis are being analyzed the contents and the ways with what the secondary school students in the Republic of Macedonia fulfill their free time outside the school, specifically there will be an examination about the gender differences i.e. the amount and manner of spending their free time. In the approach to the study of the problem of research, we decided to apply: inductive method, deductive method and the method of comparison. 

Disinfection of drinking water by ultraviolet light. Minimum dose and shortest time of residence are central criteria when choosing plant

Energy Technology Data Exchange (ETDEWEB)

1977-06-23

It is no longer mandatory that a given residue of chlorine is present in drinking water and this has led to interest in the use of ultraviolet radiation for disinfection of water in large public waterworks. After a brief discussion of the effect of ultraviolet radiation related to wavelength, the most usual type of irradiation equipment is briefly described. Practioal considerations regarding the installation, such as attenuation of the radiation due to water quality and deposits are presented. The requirements as to dose and residence time are also discussed and finally it is pointed out that hydraulic imperfections can reduce the effectiveness drastically.

Radiologists' preferences for just-in-time learning.

Science.gov (United States)

Kahn, Charles E; Ehlers, Kevin C; Wood, Beverly P

2006-09-01

Effective learning can occur at the point of care, when opportunities arise to acquire information and apply it to a clinical problem. To assess interest in point-of-care learning, we conducted a survey to explore radiologists' attitudes and preferences regarding the use of just-in-time learning (JITL) in radiology. Following Institutional Review Board approval, we invited 104 current radiology residents and 86 radiologists in practice to participate in a 12-item Internet-based survey to assess their attitudes toward just-in-time learning. Voluntary participation in the survey was solicited by e-mail; respondents completed the survey on a web-based form. Seventy-nine physicians completed the questionnaire, including 47 radiology residents and 32 radiologists in practice; the overall response rate was 42%. Respondents generally expressed a strong interest for JITL: 96% indicated a willingness to try such a system, and 38% indicated that they definitely would use a JITL system. They expressed a preference for learning interventions of 5-10 min in length. Current and recent radiology trainees have expressed a strong interest in just-in-time learning. The information from this survey should be useful in pursuing the design of learning interventions and systems for delivering just-in-time learning to radiologists.

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

Orthopedic resident work-shift analysis: are we making the best use of resident work hours?

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Hamid, Kamran S; Nwachukwu, Benedict U; Hsu, Eugene; Edgerton, Colston A; Hobson, David R; Lang, Jason E

2014-01-01

Surgery programs have been tasked to meet rising demands in patient surgical care while simultaneously providing adequate resident training in the midst of increasing resident work-hour restrictions. The purpose of this study was to quantify orthopedic surgery resident workflow and identify areas needing improved resident efficiency. We hypothesize that residents spend a disproportionate amount of time involved in activities that do not relate directly to patient care or maximize resident education. We observed 4 orthopedic surgery residents on the orthopedic consult service at a major tertiary care center for 72 consecutive hours (6 consecutive shifts). We collected minute-by-minute data using predefined work-task criteria: direct new patient contact, direct existing patient contact, communications with other providers, documentation/administrative time, transit time, and basic human needs. A seventh category comprised remaining less-productive work was termed as standby. In a 720-minute shift, residents spent on an average: 191 minutes (26.5%) performing documentation/administrative duties, 167.0 minutes (23.2%) in direct contact with new patient consults, 129.6 minutes (17.1%) in communication with other providers regarding patients, 116.2 (16.1%) minutes in standby, 63.7 minutes (8.8%) in transit, 32.6 minutes (4.5%) with existing patients, and 20 minutes (2.7%) attending to basic human needs. Residents performed an additional 130 minutes of administrative work off duty. Secondary analysis revealed residents were more likely to perform administrative work rather than directly interact with existing patients (p = 0.006) or attend to basic human needs (p = 0.003). Orthopedic surgery residents spend a large proportion of their time performing documentation/administrative-type work and their workday can be operationally optimized to minimize nonvalue-adding tasks. Formal workflow analysis may aid program directors in systematic process improvements to better align

Relaxation of the vibrational distribution function in N2 time varying discharges

International Nuclear Information System (INIS)

Capitelli, M.; Gorse, C.; Ricard, A.

1981-01-01

Relaxation of the electron and vibrational distribution functions have been calculated in function of residence time in nitrogen electrical discharges and post-discharges. In the discharge the vibrational temperature get bigger with the residence time for t -2 s. In the post-discharge the vibrational distribution is evolving in such a manner that the high levels are overpopulated as the low vibrational level population is dropping

First passage times for multiple particles with reversible target-binding kinetics

Science.gov (United States)

Grebenkov, Denis S.

2017-10-01

We investigate the first passage problem for multiple particles that diffuse towards a target, partially adsorb there, and then desorb after a finite exponentially distributed residence time. We search for the first time when m particles undergoing such reversible target-binding kinetics are found simultaneously on the target that may trigger an irreversible chemical reaction or a biophysical event. Even if the particles are independent, the finite residence time on the target yields an intricate temporal coupling between particles. We compute analytically the mean first passage time (MFPT) for two independent particles by mapping the original problem to higher-dimensional surface-mediated diffusion and solving the coupled partial differential equations. The respective effects of the adsorption and desorption rates on the MFPT are revealed and discussed.

Tile Drainage Density Reduces Groundwater Travel Times and Compromises Riparian Buffer Effectiveness.

Science.gov (United States)

Schilling, Keith E; Wolter, Calvin F; Isenhart, Thomas M; Schultz, Richard C

2015-11-01

Strategies to reduce nitrate-nitrogen (nitrate) pollution delivered to streams often seek to increase groundwater residence time to achieve measureable results, yet the effects of tile drainage on residence time have not been well documented. In this study, we used a geographic information system groundwater travel time model to quantify the effects of artificial subsurface drainage on groundwater travel times in the 7443-ha Bear Creek watershed in north-central Iowa. Our objectives were to evaluate how mean groundwater travel times changed with increasing drainage intensity and to assess how tile drainage density reduces groundwater contributions to riparian buffers. Results indicate that mean groundwater travel times are reduced with increasing degrees of tile drainage. Mean groundwater travel times decreased from 5.6 to 1.1 yr, with drainage densities ranging from 0.005 m (7.6 mi) to 0.04 m (62 mi), respectively. Model simulations indicate that mean travel times with tile drainage are more than 150 times faster than those that existed before settlement. With intensive drainage, less than 2% of the groundwater in the basin appears to flow through a perennial stream buffer, thereby reducing the effectiveness of this practice to reduce stream nitrate loads. Hence, strategies, such as reconnecting tile drainage to buffers, are promising because they increase groundwater residence times in tile-drained watersheds. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Radiotracer method for residence time distribution study in multiphase flow system

International Nuclear Information System (INIS)

Sugiharto, S.; Su'ud, Z.; Kurniadi, R.; Wibisono, W.; Abidin, Z.

2009-01-01

[ 131 I] isotope in different chemical compounds have been injected into 24 in hydrocarbon transmission pipeline containing approximately 95% water, 3% crude oil, 2% gas and negligible solid material, respectively. The system is operated at the temperature around 70 deg. C enabling fluids flow is easier in the pipeline. The segment of measurement was chosen far from the junction point of the pipeline, therefore, it was reasonably to assume that the fluids in such multiphase system were separated distinctively. Expandable tubing of injector was used to ensure that the isotopes were injected at the proper place in the sense that [ 131 I]Na isotope was injected into water layer and iodo-benzene, [131] IC 6 H 5, was injected into crude oil regime. The radiotracer selection was based on the compatibility of radiotracer with each of fluids under investigation. [ 131 I]Na was used for measuring flow of water while iodo-benzene, [131] IC 6 H 5, was used for measuring flow of crude oil. Two scintillation detectors were used and they are put at the distances 80 and 100 m, respectively, from injection point. The residence time distribution data were utilized for calculation water and crude oil flows. Several injections were conducted in the experiments. Although the crude oil density is lighter than the density of water, the result of measurement shows that the water flow is faster than the crude oil flow. As the system is water-dominated, water may act as carrier and the movement of crude oil is slowed due to friction between crude oil with water and crude oil with gas at top layer. Above of all, this result was able to give answer on the question why crude oil always arrives behind water as it is checked at gathering station. In addition, the flow patterns of the water in the pipeline calculated by Reynolds number and predicted by simple tank-in-series model is turbulence in character.

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…

Urban-Rural Differences in Aerobic Physical Activity, Muscle Strengthening Exercise, and Screen-Time Sedentary Behavior.

Science.gov (United States)

Robertson, Michael C; Song, Jaejoon; Taylor, Wendell C; Durand, Casey P; Basen-Engquist, Karen M

2018-02-16

Compared to their urban counterparts, US residents in rural settings face an increased risk of premature mortality and health problems that have been linked to insufficient physical activity (PA) levels. There is limited literature regarding urban-rural differences in adherence to national guidelines for all 3 PA-related behaviors. We investigated urban-rural differences in aerobic PA, leisure-time muscle strengthening PA, and leisure screen-time sedentary behavior in a combined data set of the 2011-2014 waves (N = 14,188) of the nationally representative National Cancer Institute's Health Information National Trends Survey. We found no evidence of a difference between large urban and rural residents' aerobic PA levels. The typical number of weekly bouts of leisure-time muscle strengthening PA was 25% lower for rural residents (incidence rate ratio [IRR] = 0.751, P rural residents to engage in 6.6% less daily leisure screen-time sedentary behavior than their large urban counterparts (IRR = 0.934, P = .031). Taken together with previous literature, these results suggest that rural residents may engage in comparable levels of total PA, but less leisure-time PA, than their urban counterparts. © 2018 National Rural Health Association.

Time to and predictors of dual incontinence in older nursing home admissions.

Science.gov (United States)

Bliss, Donna Z; Gurvich, Olga V; Eberly, Lynn E; Harms, Susan

2018-01-01

There are few studies of nursing home residents that have investigated the development of dual incontinence, perhaps the most severe type of incontinence as both urinary and fecal incontinence occur. To determine the time to and predictors of dual incontinence in older nursing home residents. Using a cohort design, records of older nursing home admissions who were continent or had only urinary or only fecal incontinence (n = 39,181) were followed forward for report of dual incontinence. Four national US datasets containing potential predictors at multiple levels describing characteristics of nursing home residents, nursing homes (n = 445), and socioeconomic and sociodemographic status of the community surrounding nursing homes were analyzed. A Cox proportional hazard regression with nursing home-specific random effect was used. At 6 months after admission, 28% of nursing home residents developed dual incontinence, at 1 year 42% did so, and at 2 years, 61% had dual incontinence. Significant predictors for time to developing dual incontinence were having urinary incontinence, greater functional or cognitive deficits, more comorbidities, older age, and lesser quality of nursing home care. The development of dual incontinence is a major problem among nursing home residents. Predictors in this study offer guidance in developing interventions to prevent and reduce the time to developing this problem which may improve the quality of life of nursing residents. © 2017 Wiley Periodicals, Inc.

Residents as teachers: psychiatry and family medicine residents' self-assessment of teaching knowledge, skills, and attitudes.

Science.gov (United States)

Brand, Michael W; Ekambaram, Vijayabharathi; Tucker, Phebe; Aggarwal, Ruchi

2013-09-01

Residents are one of the prime sources of information and education for medical students. As an initial step in supporting residents as teachers, a baseline self-assessment of residents' knowledge, skills, attitudes, and values related to teaching was conducted among psychiatry and family medicine residents to compare and improve their confidence and skills as teachers. Psychiatry residents (N=12) and family medicine residents (N=23) completed self-assessments of their knowledge, skills, attitudes, and values related to teaching. Residents also were asked to list steps used in the One-Minute Preceptor process and estimate the time each spent in teaching. Descriptive summary statistics were used for four main areas related to teaching; t-test and chi-square analyses were conducted to ascertain whether there was a significant difference in resident groups. In the current study, the perceived amount of time spent for teaching patients was significantly higher among family practice residents, whereas no group differences were found for time teaching medical students, peers, community members, non-physicians, or others. However, family medicine residents rated themselves higher than psychiatry residents in their understanding of their roles in teaching medical students and teaching patients. Also, family medicine residents' self-reported teaching skills were more advanced (82.4%) than psychiatry residents' (54.2%). They most likely applied at least two different teaching methods in inpatient and outpatient settings, as compared with psychiatry residents. No significant group differences were found in the other 15 items assessing teaching knowledge, skills, attitudes, and values. Results indicate that residents' knowledge, skills, attitudes, and values regarding teaching varies across institutions and training programs. The psychiatry residents in this study do not clearly understand their role as educators with patients and medical students; they have a less clear

The impact of travel time on geographic distribution of dialysis patients.

Science.gov (United States)

Kashima, Saori; Matsumoto, Masatoshi; Ogawa, Takahiko; Eboshida, Akira; Takeuchi, Keisuke

2012-01-01

The geographic disparity of prevalence rates among dialysis patients is unclear. We evaluate the association between travel time to dialysis facilities and prevalence rates of dialysis patients living in 1,867 census areas of Hiroshima, Japan. Furthermore, we study the effects of geographic features (mainland or island) on the prevalence rates and assess if these effects modify the association between travel time and prevalence. The study subjects were all 7,374 people that were certified as the "renal disabled" by local governments in 2011. The travel time from each patient to the nearest available dialysis facility was calculated by incorporating both travel time and the capacity of all 98 facilities. The effect of travel time on the age- and sex-adjusted standard prevalence rate (SPR) and 95% confidence intervals (CIs) at each census area was evaluated in two-level Poisson regression models with 1,867 census areas (level 1) nested within 35 towns or cities (level 2). The results were adjusted for area-based parameters of socioeconomic status, urbanity, and land type. Furthermore, the SPR of dialysis patients was calculated in each specific subgroup of population for travel time, land type, and combination of land type and travel time. In the regression analysis, SPR decreased by 5.2% (95% CI: -7.9--2.3) per 10-min increase in travel time even after adjusting for potential confounders. The effect of travel time on prevalence was different in the mainland and island groups. There was no travel time-dependent SPR disparity on the islands. The SPR among remote residents (>30 min from facilities) in the mainland was lower (0.77, 95% CI: 0.71-0.85) than that of closer residents (≤ 30 min; 0.95, 95% CI: 0.92-0.97). The prevalence of dialysis patients was lower among remote residents. Geographic difficulties for commuting seem to decrease the prevalence rate.

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.

Results of the 2005-2008 Association of Residents in Radiation Oncology Survey of Chief Residents in the United States: Clinical Training and Resident Working Conditions

International Nuclear Information System (INIS)

Gondi, Vinai; Bernard, Johnny Ray; Jabbari, Siavash; Keam, Jennifer; Amorim Bernstein, Karen L. de; Dad, Luqman K.; Li, Linna; Poppe, Matthew M.; Strauss, Jonathan B.; Chollet, Casey T.

2011-01-01

Purpose: To document clinical training and resident working conditions reported by chief residents during their residency. Methods and Materials: During the academic years 2005 to 2006, 2006 to 2007, and 2007 to 2008, the Association of Residents in Radiation Oncology conducted a nationwide survey of all radiation oncology chief residents in the United States. Chi-square statistics were used to assess changes in clinical training and resident working conditions over time. Results: Surveys were completed by representatives from 55 programs (response rate, 71.4%) in 2005 to 2006, 60 programs (75.9%) in 2006 to 2007, and 74 programs (93.7%) in 2007 to 2008. Nearly all chief residents reported receiving adequate clinical experience in commonly treated disease sites, such as breast and genitourinary malignancies; and commonly performed procedures, such as three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. Clinical experience in extracranial stereotactic radiotherapy increased over time (p < 0.001), whereas clinical experience in endovascular brachytherapy (p <0.001) decreased over time. The distribution of gynecologic and prostate brachytherapy cases remained stable, while clinical case load in breast brachytherapy increased (p = 0.006). A small but significant percentage of residents reported receiving inadequate clinical experience in pediatrics, seeing 10 or fewer pediatric cases during the course of residency. Procedures involving higher capital costs, such as particle beam therapy and intraoperative radiotherapy, and infrequent clinical use, such as head and neck brachytherapy, were limited to a minority of institutions. Most residency programs associated with at least one satellite facility have incorporated resident rotations into their clinical training, and the majority of residents at these programs find them valuable experiences. The majority of residents reported working 60 or fewer hours per week on required clinical duties

Impact of Residency Training Redesign on Residents' Clinical Knowledge.

Science.gov (United States)

Waller, Elaine; Eiff, M Patrice; Dexter, Eve; Rinaldo, Jason C B; Marino, Miguel; Garvin, Roger; Douglass, Alan B; Phillips, Robert; Green, Larry A; Carney, Patricia A

2017-10-01

The In-training Examination (ITE) is a frequently used method to evaluate family medicine residents' clinical knowledge. We compared family medicine ITE scores among residents who trained in the 14 programs that participated in the Preparing the Personal Physician for Practice (P4) Project to national averages over time, and according to educational innovations. The ITE scores of 802 consenting P4 residents who trained in 2007 through 2011 were obtained from the American Board of Family Medicine. The primary analysis involved comparing scores within each academic year (2007 through 2011), according to program year (PGY) for P4 residents to all residents nationally. A secondary analysis compared ITE scores among residents in programs that experimented with length of training and compared scores among residents in programs that offered individualized education options with those that did not. Release of ITE scores was consented to by 95.5% of residents for this study. Scores of P4 residents were higher compared to national scores in each year. For example, in 2011, the mean P4 score for PGY1 was 401.2, compared to the national average of 386. For PGY2, the mean P4 score was 443.1, compared to the national average of 427, and for PGY3, the mean P4 score was 477.0, compared to the national PGY3 score of 456. Scores of residents in programs that experimented with length of training were similar to those in programs that did not. Scores were also similar between residents in programs with and without individualized education options. Family medicine residency programs undergoing substantial educational changes, including experiments in length of training and individualized education, did not appear to experience a negative effect on resident's clinical knowledge, as measured by ITE scores. Further research is needed to study the effect of a wide range of residency training innovations on ITE scores over time.

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

Separating Direct and Indirect Turbofan Engine Combustion Noise While Estimating Post-Combustion (Post-Flame) Residence Time Using the Correlation Function

Science.gov (United States)

Miles, Jeffrey Hilton

2011-01-01

A previous investigation on the presence of direct and indirect combustion noise for a full-scale turbofan engine using a far-field microphone at 130 is extended by also examining signals obtained at two additional downstream directions using far-field microphones at 110 deg and 160 deg. A generalized cross-correlation function technique is used to study the change in propagation time to the far field of the combined direct and indirect combustion noise signal as a sequence of low-pass filters are applied. The filtering procedure used produces no phase distortion. As the low-pass filter frequency is decreased, the travel time increases because the relative amount of direct combustion noise is reduced. The indirect combustion noise signal travels more slowly because in the combustor entropy fluctuations move with the flow velocity, which is slow compared to the local speed of sound. The indirect combustion noise signal travels at acoustic velocities after reaching the turbine and being converted into an acoustic signal. The direct combustion noise is always propagating at acoustic velocities. The results show that the estimated indirect combustion noise time delay values (post-combustion residence times) measured at each angle are fairly consistent with one another for a relevant range of operating conditions and demonstrate source separation of a mixture of direct and indirect combustion noise. The results may lead to a better idea about the acoustics in the combustor and may help develop and validate improved reduced-order physics-based methods for predicting turbofan engine core noise.

Rehabilitation time before disability pension.

Science.gov (United States)

Støver, Morten; Pape, Kristine; Johnsen, Roar; Fleten, Nils; Sund, Erik R; Claussen, Bjørgulf; Ose, Solveig Osborg; Bjørngaard, Johan Håkon

2012-10-30

The decision to grant a disability pension is usually the end of a long process of medical examinations, treatment and rehabilitation attempts. This study investigates to what extent the time spent on rehabilitation time prior to disability pension is associated with characteristics of the individual or the local employment and welfare office, measured as municipality variance. A study of 2,533 40 to 42 year olds who received disability pension over a period of 18 years. The logarithm of the rehabilitation time before granting a disability pension was analysed with multilevel regression. The rehabilitation time before a disability pension was granted ranged from 30 to 5,508 days. Baseline health characteristics were only moderately associated with rehabilitation time. Younger people and people with unemployment periods had longer rehabilitation time before a disability pension was granted. There were only minor differences in rehabilitation time between men and women and between different levels of education. Approximately 2% of the total variance in rehabilitation time could be attributed to the municipality of residence. There is a higher threshold for granting a disability pension to younger persons and those who are expecting periods of unemployment, which is reflected in the extended rehabilitation requirements for these groups. The longer rehabilitation period for persons with psychiatric disorders might reflect a lack of common knowledge on the working capacity of and the fitted rehabilitation programs for people with psychiatric disorders.

Rehabilitation time before disability pension

Directory of Open Access Journals (Sweden)

Støver Morten

2012-10-01

Full Text Available Abstract Background The decision to grant a disability pension is usually the end of a long process of medical examinations, treatment and rehabilitation attempts. This study investigates to what extent the time spent on rehabilitation time prior to disability pension is associated with characteristics of the individual or the local employment and welfare office, measured as municipality variance. Methods A study of 2,533 40 to 42 year olds who received disability pension over a period of 18 years. The logarithm of the rehabilitation time before granting a disability pension was analysed with multilevel regression. Results The rehabilitation time before a disability pension was granted ranged from 30 to 5,508 days. Baseline health characteristics were only moderately associated with rehabilitation time. Younger people and people with unemployment periods had longer rehabilitation time before a disability pension was granted. There were only minor differences in rehabilitation time between men and women and between different levels of education. Approximately 2% of the total variance in rehabilitation time could be attributed to the municipality of residence. Conclusions There is a higher threshold for granting a disability pension to younger persons and those who are expecting periods of unemployment, which is reflected in the extended rehabilitation requirements for these groups. The longer rehabilitation period for persons with psychiatric disorders might reflect a lack of common knowledge on the working capacity of and the fitted rehabilitation programs for people with psychiatric disorders.

Perceived and Real Histopathology Turnaround Time: A Teaching ...

African Journals Online (AJOL)

2018-03-05

Mar 5, 2018 ... Background: This study aims to audit analytic turnaround time (TAT) in a histopathology ... facility where not only pathology services are rendered, but residency ..... pathology as a tool for quality assurance. Niger J Med. 2008 ...

TIME CALIBRATED OSCILLOSCOPE SWEEP CIRCUIT

Science.gov (United States)

Smith, V.L.; Carstensen, H.K.

1959-11-24

An improved time calibrated sweep circuit is presented, which extends the range of usefulness of conventional oscilloscopes as utilized for time calibrated display applications in accordance with U. S. Patent No. 2,832,002. Principal novelty resides in the provision of a pair of separate signal paths, each of which is phase and amplitude adjustable, to connect a high-frequency calibration oscillator to the output of a sawtooth generator also connected to the respective horizontal deflection plates of an oscilloscope cathode ray tube. The amplitude and phase of the calibration oscillator signals in the two signal paths are adjusted to balance out feedthrough currents capacitively coupled at high frequencies of the calibration oscillator from each horizontal deflection plate to the vertical plates of the cathode ray tube.

Prediction of evacuation time for emergency planning zone of Uljin nuclear site

International Nuclear Information System (INIS)

Jeon, In Young; Lee, Jai Ki

2002-01-01

The time for evacuation of residents in Emergency Planning Zone (EPZ) of Uljin nuclear site in case of a radiological emergency was estimated with traffic analysis. Evacuees were classified into 4 groups by considering population density, local jurisdictions, and whether they are residents or transients. The survey to investigate the behavioral characteristics of the residents was made for 200 households and included a hypothetical scenario explaining the accident situation and questions such as dwelling place, time demand for evacuation preparation, transportation means for evacuation, sheltering place, and evacuation direction. The microscopic traffic simulation model, CORSIM, was used to simulate the behavior of evacuating vehicles on networks. The results showed that the evacuation time required for total vehicles to move out from EPZ took longer in the daytime than at night in spite that the delay times at intersections were longer at night than in the daytime. This was analyzed due to the differences of the trip generation time distribution. To validate whether the CORSIM model can appropriately simulate the congested traffic phenomena assumable in case of emergency, a benchmark study was conducted at an intersection without an actuated traffic signal near Uljin site during the traffic peak-time in the morning. This study indicated that the predicted output by the CORSIM model was in good agreement with the observed data, satisfying the purpose of this study

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.

An estimate of hydrothermal fluid residence times and vent chimney growth rates based on 210Pb/Pb ratios and mineralogic studies of sulfides dredged from the Juan de Fuca Ridge

International Nuclear Information System (INIS)

Kadko, D.; Tatsumoto, Mitsunobu

1985-01-01

The 210 Pb/Pb ratios across two sulfide samples dredged from the Juan de Fuca Ridge are used to estimate the growth rate of the sulfide material and the residence time of the hydrothermal fluid within the oceanic crust from the onset of basalt alteration. 210 Pb is added to the hydrothermal fluid by two processes: 1) high-temperature alteration of basalt and 2) if the residence time of the fluid is on the order of the 22.3-year half-life of 210 Pb, by in-situ growth from 222 Rn (Krishnaswami and Turekian, 1982). Stable lead is derived only from the alteration of basalt. The 210 Pb/Pb ratio across one sample was proportional 0.5 dpm/10 -6 g Pb, and across the other is was proportional 0.4 dpm/10 -6 g Pb. These values are quite close to the 238 U/Pb ratios of basalts from the area, suggesting that the residence time of the hydrothermal fluid from the onset of basalt alteration is appreciably less than the mean life of 210 Pb, i.e., the time required for ingrowth from the radon. An apparent growth rate of 1.2 cm/yr is derived from the slope of the 210 Pb/Pb curve for one of the samples. This is consistent with its mineralogy and texture which suggest an accretionary pattern of development. There is no obvious sequential growth pattern, and virtually no gradient in 210 Pb/Pb across the second sample. This is consistent with alteration of the original 210 Pb/Pb distribution by extensive remobilization reactions which are inferred from the mineralogic and textural relationships of the sample. (orig.)

First passage time to allopatric speciation.

Science.gov (United States)

Yamaguchi, Ryo; Iwasa, Yoh

2013-12-06

Allopatric speciation is a mechanism to evolve reproductive isolation; it is caused by the accumulation of genetic differences between populations while they are geographically isolated. Here, we studied a simple stochastic model for the time until speciation caused by geographical isolation in fragmented populations that experience recurrent but infrequent migration between subpopulations. We assumed that mating incompatibility is controlled by a number of loci that behave as neutral characters in the accumulation of novel mutations within each population. Genetic distance between populations was defined as the number of incompatibility-controlling loci that differ between them. Genetic distance increases through the separate accumulation of mutations in different populations, but decreases after a successful migration event followed by genetic mixing between migrants and residents. We calculated the time to allopatric speciation, which occurs when the genetic distance exceeds a specified threshold. If the number of invasive individuals relative to the resident population is not very large, diffusion approximation provides an accurate prediction. There is an intermediate optimal rate of migration that maximizes the rate of species creation by recurrent invasion and diversification. We also examined cases that involved more than two populations.

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

Mobile technology in radiology resident education.

Science.gov (United States)

Korbage, Aiham C; Bedi, Harprit S

2012-06-01

The authors hypothesized that ownership of a mobile electronic device would result in more time spent learning radiology. Current trends in radiology residents' studying habits, their use of electronic and printed radiology learning resources, and how much of the funds allotted to them are being used toward printed vs electronic education tools were assessed in this study. A survey study was conducted among radiology residents across the United States from June 13 to July 5, 2011. Program directors listed in the Association of Program Directors in Radiology e-mail list server received an e-mail asking for residents to participate in an online survey. The questionnaire consisted of 12 questions and assessed the type of institution, the levels of training of the respondents, and book funds allocated to residents. It also assessed the residents' study habits, access to portable devices, and use of printed and electronic radiology resources. Radiology residents are adopters of new technologies, with 74% owning smart phones and 37% owning tablet devices. Respondents spend nearly an equal amount of time learning radiology from printed textbooks as they do from electronic resources. Eighty-one percent of respondents believe that they would spend more time learning radiology if provided with tablet devices. There is considerable use of online and electronic resources and mobile devices among the current generation of radiology residents. Benefits, such as more study time, may be obtained by radiology programs that incorporate tablet devices into the education of their residents. Copyright © 2012 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Evaluation of AHRQ's on-time pressure ulcer prevention program: a facilitator-assisted clinical decision support intervention for nursing homes.

Science.gov (United States)

Olsho, Lauren E W; Spector, William D; Williams, Christianna S; Rhodes, William; Fink, Rebecca V; Limcangco, Rhona; Hurd, Donna

2014-03-01

Pressure ulcers present serious health and economic consequences for nursing home residents. The Agency for Healthcare Research & Quality, in partnership with the New York State Department of Health, implemented the pressure ulcer module of On-Time Quality Improvement for Long Term Care (On-Time), a clinical decision support intervention to reduce pressure ulcer incidence rates. To evaluate the effectiveness of the On-Time program in reducing the rate of in-house-acquired pressure ulcers among nursing home residents. We employed an interrupted time-series design to identify impacts of 4 core On-Time program components on resident pressure ulcer incidence in 12 New York State nursing homes implementing the intervention (n=3463 residents). The sample was purposively selected to include nursing homes with high baseline prevalence and incidence of pressure ulcers and high motivation to reduce pressure ulcers. Differential timing and sequencing of 4 core On-Time components across intervention nursing homes and units enabled estimation of separate impacts for each component. Inclusion of a nonequivalent comparison group of 13 nursing homes not implementing On-Time (n=2698 residents) accounts for potential mean-reversion bias. Impacts were estimated via a random-effects Poisson model including resident-level and facility-level covariates. We find a large and statistically significant reduction in pressure ulcer incidence associated with the joint implementation of 4 core On-Time components (incidence rate ratio=0.409; P=0.035). Impacts vary with implementation of specific component combinations. On-Time implementation is associated with sizable reductions in pressure ulcer incidence.

Satisfaction of women urologists with maternity leave and childbirth timing.

Science.gov (United States)

Lerner, Lori B; Baltrushes, Robin J; Stolzmann, Kelly L; Garshick, Eric

2010-01-01

Women physicians must consider many conflicting issues when timing childbirth. We characterized maternity leave, breast-feeding practices and satisfaction associated with pregnancy timing in women urologists. A 114-item anonymous survey including questions on maternity leave duration for firstborn children, workplace policies, attitudes and satisfaction was mailed to all 365 American board certified women urologists in May and July 2007. Logistic regression was used to identify factors associated with greater satisfaction. A total of 243 women urologists (69%) responded, of whom 158 had at least 1 biological child. Average maternal age at first birth was 32.6 years. Of the children 10%, 32% and 52% were born before, during and after residency, respectively. Only 42% of women reported the existence of a formal maternity leave policy. Of the women 70% took 8 weeks or less of leave. Those with 9 weeks or greater were 3.8 times more likely to report satisfaction (p = 0.001). Although women in practice were 2.0 times more likely to take 9 weeks or greater compared to those in training or earlier (p = 0.046), only 30% in practice took this much time. Dissatisfaction with leave was not related to birth timing (residency vs practice) or maternal age at delivery but to work/residency related issues in 69% of respondents, financial concerns in 13% and personal/other in 18%. For breast-feeding 67% of respondents were satisfied with the duration and 22% were not. Dissatisfaction was secondary to work factors. Satisfaction with leave was related to the amount of maternity leave with women with 9 weeks or greater more likely to report satisfaction. Women in practice were more likely to take 9 weeks or greater but most did not due to strong stressors related to work, partners/peers or finances. Work factors were cited for dissatisfaction with breast-feeding.

Reservoir theory, groundwater transit time distributions, and lumped parameter models

International Nuclear Information System (INIS)

Etcheverry, D.; Perrochet, P.

1999-01-01

The relation between groundwater residence times and transit times is given by the reservoir theory. It allows to calculate theoretical transit time distributions in a deterministic way, analytically, or on numerical models. Two analytical solutions validates the piston flow and the exponential model for simple conceptual flow systems. A numerical solution of a hypothetical regional groundwater flow shows that lumped parameter models could be applied in some cases to large-scale, heterogeneous aquifers. (author)

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.

Process algebra with timing : real time and discrete time

NARCIS (Netherlands)

Baeten, J.C.M.; Middelburg, C.A.; Bergstra, J.A.; Ponse, A.J.; Smolka, S.A.

2001-01-01

We present real time and discrete time versions of ACP with absolute timing and relative timing. The starting-point is a new real time version with absolute timing, called ACPsat, featuring urgent actions and a delay operator. The discrete time versions are conservative extensions of the discrete

Process algebra with timing: Real time and discrete time

NARCIS (Netherlands)

Baeten, J.C.M.; Middelburg, C.A.

1999-01-01

We present real time and discrete time versions of ACP with absolute timing and relative timing. The startingpoint is a new real time version with absolute timing, called ACPsat , featuring urgent actions and a delay operator. The discrete time versions are conservative extensions of the discrete

Discharge residence of TLD tagged fish

International Nuclear Information System (INIS)

Romberg, G.P.; Prepejchal, W.

1974-01-01

Although visual observations suggested that fish remained in the discharge for considerable periods, temperature-sensitive tags indicated the majority of fish spend less than 50 hr or 10 percent of the time at discharge temperatures. During 1974 a second fish tagging study was conducted, using temperature-sensitive tags to yield discharge residence times of Lake Michigan salmonids at Point Beach thermal discharge. Preliminary results revealed that many fish tag values were close to Unit I line indicating that calculated maximum discharge residence times for these fish will be nearly 100 percent of the elapsed time

The TIME Questionnaire: A tool for eliciting personhood and enhancing dignity in nursing homes.

Science.gov (United States)

Pan, Jingyan Linda; Chochinov, Harvey; Thompson, Genevieve; McClement, Susan

2016-01-01

This study aimed at evaluating the effectiveness of the TIME (This Is ME) Questionnaire in eliciting personhood and enhancing dignity; specifically investigating the residents' and health care providers' perspectives in the nursing home setting. Residents (n = 41) from six nursing homes in a Canadian urban center completed both the TIME Questionnaire and a feedback response questionnaire; health care providers (n = 22) offered feedback both through a questionnaire or participation in a focus group. 100% of the residents indicated the summary was accurate. 94% stated that they wanted to receive a copy of the summary, 92% indicated they would recommend the questionnaire to others, 72% wanted a copy of the summary to be placed into their medical chart. Overall HCPs' agreed that they have learned something new from TIME, and that TIME influenced their attitude, care, respect, empathy/compassion, sense of connectedness, as well as personal satisfaction in providing care. Copyright © 2016 Elsevier Inc. All rights reserved.

Psychotherapy Training: Residents' Perceptions and Experiences.

Science.gov (United States)

Kovach, Jessica G; Dubin, William R; Combs, Christopher J

2015-10-01

This survey examined actual training hours in psychotherapy modalities as reported by residents, residents' perceptions of training needs, and residents' perceptions of the importance of different aspects of psychotherapy training. A brief, voluntary, anonymous, Internet-based survey was developed. All 14 program directors for Accreditation Council for Graduate Medical Education accredited programs in Pennsylvania, New Jersey, and Delaware provided email addresses for current categorical residents. The survey inquired about hours of time spent in various aspects of training, value assigned to aspects of training, residents' involvement in their own psychotherapy, and overall resident wellness. The survey was e-mailed to 328 residents. Of the 328 residents contacted, 133 (40.5%) responded. Median reported number of PGY 3 and 4 performed versus perceived ideal hours of supportive therapy, cognitive behavioral therapy (CBT), and psychodynamic therapy did not differ. Answers for clinical time utilizing these modalities ranged from "none or less than 1 h" per month to 20+ h per month. PGY 3 and 4 residents reported a median of "none or less than 1 h" per month performed of interpersonal, dialectical behavior therapy, couples/family/group, and child therapies but preferred more time using these therapies. Residents in all years of training preferred more hours of didactic instruction for all psychotherapies and for medication management. Residents ranked teaching modalities in the following order of importance: supervision, hours of psychotherapy performed, personal psychotherapy, readings, and didactic instruction. Residents engaged in their own psychotherapy were significantly more likely to rank the experiential aspects of psychotherapy training (personal psychotherapy, supervision, and hours performed) higher than residents not in psychotherapy. Current psychotherapy training for psychiatry residents is highly variable, but overall, residents want more

Time-Location Patterns of a Population Living in an Air Pollution Hotspot

International Nuclear Information System (INIS)

Wu, X.M.; Fan, Z.T.; Strickland, P.O.; Wu, X.M.; Fan, Z.T.; Strickland, P.O.

2010-01-01

This study characterized the time-location pattern of 107 residents living in air pollution hotspots, the Waterfront South and Cope wood/Davis Streets communities in Camden, NJ. Most residents in the two communities are minority and impoverished individuals. Results showed that employment status played the fundamental role in determining time-location patterns of this study population, and the variations of time-location pattern by season and by day-type were partially attributed to employment status. Compared to the National Human Activity Pattern Survey, the Camden cohort spent significantly more time outdoors (3.8 hours versus 1.8 hours) and less time indoors (19.4 hours versus 20.9 hours) than the general US population, indicating a higher risk of exposure to ambient air pollution for the Camden cohort. The findings of the study are important for understanding exposure routes and sources for the socio economically disadvantaged subgroup and ultimately help develop effective strategies to reduce community exposure to ambient air pollution in hotspots

Post-irradiation examinations on the KNK II/1 fuel element NY-203 with 400 equivalent full-power days residence time and 10 % burnup

International Nuclear Information System (INIS)

Patzer, G.; Geier, F.

1984-09-01

The fuel assembly NY-203 has been irradiated in the first core of KNK II up to a burnup of about 10 % and a residence time of 400 equivalent full-power days. The assembly contained 211 fuel pins with 6.0 mm outer diameter and fuel pellets with the composition (U 0 .7Pu 0 .3)O 2 .00. The cladding material was the austenitic steel 1.4988 lg. Some selected pins were examined in the hot cells of the KfK Karlsruhe. The post-irradiation examinations did not reveal any critical design aspects [de

Parental leave for residents and pediatric training programs.

Science.gov (United States)

2013-02-01

The American Academy of Pediatrics (AAP) is committed to the development of rational, equitable, and effective parental leave policies that are sensitive to the needs of pediatric residents, families, and developing infants and that enable parents to spend adequate and good-quality time with their young children. It is important for each residency program to have a policy for parental leave that is written, that is accessible to residents, and that clearly delineates program practices regarding parental leave. At a minimum, a parental leave policy for residents and fellows should conform legally with the Family Medical Leave Act as well as with respective state laws and should meet institutional requirements of the Accreditation Council for Graduate Medical Education for accredited programs. Policies should be well formulated and communicated in a culturally sensitive manner. The AAP advocates for extension of benefits consistent with the Family Medical Leave Act to all residents and interns beginning at the time that pediatric residency training begins. The AAP recommends that regardless of gender, residents who become parents should be guaranteed 6 to 8 weeks, at a minimum, of parental leave with pay after the infant's birth. In addition, in conformance with federal law, the resident should be allowed to extend the leave time when necessary by using paid vacation time or leave without pay. Coparenting, adopting, or fostering of a child should entitle the resident, regardless of gender, to the same amount of paid leave (6-8 weeks) as a person who takes maternity/paternity leave. Flexibility, creativity, and advanced planning are necessary to arrange schedules that optimize resident education and experience, cultivate equity in sharing workloads, and protect pregnant residents from overly strenuous work experiences at critical times of their pregnancies.

Quantifying faculty teaching time in a department of obstetrics and gynecology.

Science.gov (United States)

Emmons, S

1998-10-01

The goal of this project was to develop a reproducible system that measures quantity and quality of teaching in unduplicated hours, such that comparisons of teaching activities could be drawn within and across departments. Such a system could be used for allocating teaching monies and for assessing teaching as part of the promotion and tenure process. Various teaching activities, including time spent in clinic, rounds, and doing procedures, were enumerated. The faculty were surveyed about their opinions on the proportion of clinical time spent in teaching. The literature also was reviewed. Based on analysis of the faculty survey and the literature, a series of calculations were developed to divide clinical time among resident teaching, medical student teaching, and patient care. The only input needed was total time spent in the various clinical activities, time spent in didactic activities, and the resident procedure database. This article describes a simple and fair database system to calculate time spent teaching from activities such as clinic, ward rounds, labor and delivery, and surgery. The teaching portfolio database calculates teaching as a proportion of the faculty member's total activities. The end product is a report that provides a reproducible yearly summary of faculty teaching time per activity and per type of learner.

Time-out/Time-in

DEFF Research Database (Denmark)

Bødker, Mads; Gimpel, Gregory; Hedman, Jonas

2014-01-01

time-in and time-out use. Time-in technology use coincides and co-exists within the flow of ordinary life, while time-out use entails ‘taking time out’ of everyday life to accomplish a circumscribed task or engage reflectively in a particular experience. We apply a theoretically informed grounded...

Matrix diffusion: heavy-tailed residence time distributions and their influence on radionuclide retention

International Nuclear Information System (INIS)

Haggerty, R.

2002-01-01

Matrix diffusion in rocks is frequently assumed to be both Fickian and effectively homogeneous over space- and time-scales relevant to radionuclide retention. This paper discusses some cases of rocks where one or both of these assumptions may be invalid and what the consequences may be for modeling and performance assessment: a single pore diffusivity and matrix block size which is not representative of the diffusion process at all time- or space-scales, a scale-dependent diffusion rate coefficient which decreases with time- and space-scales, a retention capacity of host rocks that may be smaller than apparent in laboratory and field tests because all of the pore space is not accessible via diffusion over the performance assessment-scale transport time. (J.S.)

Recharge sources and residence times of groundwater as determined by geochemical tracers in the Mayfield Area, southwestern Idaho, 2011–12

Science.gov (United States)

Hopkins, Candice B.

2013-01-01

Parties proposing residential development in the area of Mayfield, Idaho are seeking a sustainable groundwater supply. During 2011–12, the U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, used geochemical tracers in the Mayfield area to evaluate sources of aquifer recharge and differences in groundwater residence time. Fourteen groundwater wells and one surface-water site were sampled for major ion chemistry, metals, stable isotopes, and age tracers; data collected from this study were used to evaluate the sources of groundwater recharge and groundwater residence times in the area. Major ion chemistry varied along a flow path between deeper wells, suggesting an upgradient source of dilute water, and a downgradient source of more concentrated water with the geochemical signature of the Idaho Batholith. Samples from shallow wells had elevated nutrient concentrations, a more positive oxygen-18 signature, and younger carbon-14 dates than deep wells, suggesting that recharge comes from young precipitation and surface-water infiltration. Samples from deep wells generally had higher concentrations of metals typical of geothermal waters, a more negative oxygen-18 signature, and older carbon-14 values than samples from shallow wells, suggesting that recharge comes from both infiltration of meteoric water and another source. The chemistry of groundwater sampled from deep wells is somewhat similar to the chemistry in geothermal waters, suggesting that geothermal water may be a source of recharge to this aquifer. Results of NETPATH mixing models suggest that geothermal water composes 1–23 percent of water in deep wells. Chlorofluorocarbons were detected in every sample, which indicates that all groundwater samples contain at least a component of young recharge, and that groundwater is derived from multiple recharge sources. Conclusions from this study can be used to further refine conceptual hydrological models of the area.

Fluid flow profile in a packed bead column using residence time curves and radiotracer techniques

Energy Technology Data Exchange (ETDEWEB)

Almeida, Ana Paula F. de; Gonçalves, Eduardo Ramos; Brandão, Luis Eduardo B.; Salgado, Cesar M., E-mail: anacamiqui@gmail.com, E-mail: egoncalves@con.ufrj.br, E-mail: brandao@ien.gov.br, E-mail: otero@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

Filling columns are extremely important in the chemical industry and are used for purification, separation and treatment processes of gas or liquid mixtures. The objective of this work is to study the hydrodynamics of the fluid for a characterization of aqueous phase flow patterns in the filling column, associating with the methodology of the Curves of Residence Time Distribution (RTD) to analyze and associate theoretical models that put as conditions column operating. RTD can be obtained by using the pulse-stimulus response technique which is characterized by the instantaneous injection of a radiotracer into the system input. In this work, 68Ga was used as radiotracer. Five shielded and collimated NaI (Tl) 1 x 1″ scintillator detectors were suitably positioned to record the movement of the radiotracer's path in the conveying line and filling column. Making possible the analysis of the RTD curve in the regions of interest. With the data generated by the NaI (Tl) detectors with the passage of the radiotracer in the transport line and inside the column, it was possible to evaluate the flow profile of the aqueous phase and to identify operational failures, such as internal conduit and the existence of a retention zone in the inside the column. Theoretical models were used for different flow flows: the piston flow and perfect mixing. (author)

Fluid flow profile in a packed bead column using residence time curves and radiotracer techniques

International Nuclear Information System (INIS)

Almeida, Ana Paula F. de; Gonçalves, Eduardo Ramos; Brandão, Luis Eduardo B.; Salgado, Cesar M.

2017-01-01

Filling columns are extremely important in the chemical industry and are used for purification, separation and treatment processes of gas or liquid mixtures. The objective of this work is to study the hydrodynamics of the fluid for a characterization of aqueous phase flow patterns in the filling column, associating with the methodology of the Curves of Residence Time Distribution (RTD) to analyze and associate theoretical models that put as conditions column operating. RTD can be obtained by using the pulse-stimulus response technique which is characterized by the instantaneous injection of a radiotracer into the system input. In this work, 68Ga was used as radiotracer. Five shielded and collimated NaI (Tl) 1 x 1″ scintillator detectors were suitably positioned to record the movement of the radiotracer's path in the conveying line and filling column. Making possible the analysis of the RTD curve in the regions of interest. With the data generated by the NaI (Tl) detectors with the passage of the radiotracer in the transport line and inside the column, it was possible to evaluate the flow profile of the aqueous phase and to identify operational failures, such as internal conduit and the existence of a retention zone in the inside the column. Theoretical models were used for different flow flows: the piston flow and perfect mixing. (author)

More Learning in Less Time: Optimizing the Resident Educational Experience with Limited Clinical and Educational Work Hours.

Science.gov (United States)

Sedney, Cara L; Spirou, Eleni; Voelker, Joseph L; Rosen, Charles L

2017-11-01

Resident education in the United States and elsewhere has undergone significant changes in recent years owing to work hour restrictions, requiring didactics to fit within a limited schedule, while being increasingly effective at accomplishing educational goals. A single small program experience in improving the didactic experience of residents is described. Focused mentorship, curricula for intangibles, asynchronous education, and independent curricula all are useful tools in resident education. Residents can be exposed to both clinical material and specialty-specific mores using focused and intentional educational techniques. Copyright © 2017 Elsevier Inc. All rights reserved.

Perceptions, training experiences, and preferences of surgical residents toward laparoscopic simulation training: a resident survey.

Science.gov (United States)

Shetty, Shohan; Zevin, Boris; Grantcharov, Teodor P; Roberts, Kurt E; Duffy, Andrew J

2014-01-01

Simulation training for surgical residents can shorten learning curves, improve technical skills, and expedite competency. Several studies have shown that skills learned in the simulated environment are transferable to the operating room. Residency programs are trying to incorporate simulation into the resident training curriculum to supplement the hands-on experience gained in the operating room. Despite the availability and proven utility of surgical simulators and simulation laboratories, they are still widely underutilized by surgical trainees. Studies have shown that voluntary use leads to minimal participation in a training curriculum. Although there are several simulation tools, there is no clear evidence of the superiority of one tool over the other in skill acquisition. The purpose of this study was to explore resident perceptions, training experiences, and preferences regarding laparoscopic simulation training. Our goal was to profile resident participation in surgical skills simulation, recognize potential barriers to voluntary simulator use, and identify simulation tools and tasks preferred by residents. Furthermore, this study may help to inform whether mandatory/protected training time, as part of the residents' curriculum is essential to enhance participation in the simulation laboratory. A cross-sectional study on general surgery residents (postgraduate years 1-5) at Yale University School of Medicine and the University of Toronto via an online questionnaire was conducted. Overall, 67 residents completed the survey. The institutional review board approved the methods of the study. Overall, 95.5% of the participants believed that simulation training improved their laparoscopic skills. Most respondents (92.5%) perceived that skills learned during simulation training were transferrable to the operating room. Overall, 56.7% of participants agreed that proficiency in a simulation curriculum should be mandatory before operating room experience. The

Text messaging among residents and faculty in a university general surgery residency program: prevalence, purpose, and patient care.

Science.gov (United States)

Shah, Dhruvil R; Galante, Joseph M; Bold, Richard J; Canter, Robert J; Martinez, Steve R

2013-01-01

There is little information about the use of text messaging (texting) devices among resident and faculty physicians for patient-related care (PRC). To determine the prevalence, frequency, purpose, and concerns regarding texting among resident and attending surgeons and to identify factors associated with PRC texting. E-mail survey. University medical center and its affiliated hospitals. Surgery resident and attending staff. Prevalence, frequency, purpose, and concerns regarding patient-related care text messaging. Overall, 73 (65%) surveyed physicians responded, including 45 resident (66%) and 28 attending surgeons (62%). All respondents owned a texting device. Majority of surgery residents (88%) and attendings (71%) texted residents, whereas only 59% of residents and 65% of attendings texted other faculty. Most resident to resident text occurred at a frequency of 3-5 times/d (43%) compared with most attending to resident texts, which occurred 1-2 times/d (33%). Most resident to attending (25%) and attending to attending (30%) texts occurred 1-2 times/d. Among those that texted, PRC was the most frequently reported purpose for resident to resident (46%), resident to attending (64%), attending to resident (82%), and attending to other attending staff (60%) texting. Texting was the most preferred method to communicate about routine PRC (47% of residents vs 44% of attendings). Age (OR: 0.86, 95% CI: 0.79-0.95; p = 0.003), but not sex, specialty/clinical rotation, academic rank, or postgraduate year (PGY) level predicted PRC texting. Most resident and attending staff surveyed utilize texting, mostly for PRC. Texting was preferred for communicating routine PRC information. Our data may facilitate the development of guidelines for the appropriate use of PRC texting. Copyright © 2013 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Working on the Weekend: Fathers' Time with Family in the United Kingdom

Science.gov (United States)

Hook, Jennifer L.

2012-01-01

Whereas most resident fathers are able to spend more time with their children on weekends than on weekdays, many fathers work on the weekends, spending less time with their children on these days. There are conflicting findings about whether fathers are able to make up for lost weekend time on weekdays. Using unique features of the United…

Stable isotope and noble gas constraints on the source and residence time of spring water from the Table Mountain Group Aquifer, Paarl, South Africa and implications for large scale abstraction

Science.gov (United States)

Miller, J. A.; Dunford, A. J.; Swana, K. A.; Palcsu, L.; Butler, M.; Clarke, C. E.

2017-08-01

Large scale groundwater abstraction is increasingly being used to support large urban centres especially in areas of low rainfall but presents particular challenges in the management and sustainability of the groundwater system. The Table Mountain Group (TMG) Aquifer is one of the largest and most important aquifer systems in South Africa and is currently being considered as an alternative source of potable water for the City of Cape Town, a metropolis of over four million people. The TMG aquifer is a fractured rock aquifer hosted primarily in super mature sandstones, quartzites and quartz arenites. The groundwater naturally emanates from numerous springs throughout the cape region. One set of springs were examined to assess the source and residence time of the spring water. Oxygen and hydrogen isotopes indicate that the spring water has not been subject to evaporation and in combination with Na/Cl ratios implies that recharge to the spring systems is via coastal precipitation. Although rainfall in the Cape is usually modelled on orographic rainfall, δ18O and δ2H values of some rainfall samples are strongly positive indicating a stratiform component as well. Comparing the spring water δ18O and δ2H values with that of local rainfall, indicates that the springs are likely derived from continuous bulk recharge over the immediate hinterland to the springs and not through large and/or heavy downpours. Noble gas concentrations, combined with tritium and radiocarbon activities indicate that the residence time of the TMG groundwater in this area is decadal in age with a probable maximum upper limit of ∼40 years. This residence time is probably a reflection of the slow flow rate through the fractured rock aquifer and hence indicates that the interconnectedness of the fractures is the most important factor controlling groundwater flow. The short residence time of the groundwater suggest that recharge to the springs and the Table Mountain Group Aquifer as a whole is

Coordinated scheduling for dynamic real-time systems

Science.gov (United States)

Natarajan, Swaminathan; Zhao, Wei

1994-01-01

In this project, we addressed issues in coordinated scheduling for dynamic real-time systems. In particular, we concentrated on design and implementation of a new distributed real-time system called R-Shell. The design objective of R-Shell is to provide computing support for space programs that have large, complex, fault-tolerant distributed real-time applications. In R-shell, the approach is based on the concept of scheduling agents, which reside in the application run-time environment, and are customized to provide just those resource management functions which are needed by the specific application. With this approach, we avoid the need for a sophisticated OS which provides a variety of generalized functionality, while still not burdening application programmers with heavy responsibility for resource management. In this report, we discuss the R-Shell approach, summarize the achievement of the project, and describe a preliminary prototype of R-Shell system.

Number needed to eat: pizza and resident conference attendance.

Science.gov (United States)

Cosimini, Michael J; Mackintosh, Liza; Chang, Todd P

2016-12-01

The didactic conference is a common part of the resident education curriculum. Given the demands of clinical responsibilities and restrictions on duty hours, maximising education is a challenge faced by all residency programmes. To date, little research exists with respect to how the provision of complimentary food affects physician and resident conference attendance. The objective of this study was to determine whether complimentary food improves resident arrival times and attendance at educational conferences and, furthermore, to test whether this provision is a potentially cost-effective tool for improving education. A retrospective review of 36 resident educational Friday noon conferences, including 1043 resident arrivals, was performed. Data were analysed for total attendance, arrival times, number needed to eat (NNE) and the percentage of residents arriving on time, and compared between days on which food was and was not provided. Median attendance was 3.7% higher (p = 0.04) on days on which food was provided, at a cost of US$46 for each additional resident in attendance. Arrival times were also statistically significantly improved when food was provided, with a median improvement of 0.7 minutes (p = 0.02) and an 11.0% increase in on-time arrivals (p < 0.001). The NNE was 10.6. Complimentary food improves both attendance and arrival times by a small, but statistically significant, degree. The provision of complimentary food can be considered as an incentive for attendance and on-time arrival at didactic educational sessions, although more cost-effective modalities may exist. © 2016 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

A computer-based time study system for timber harvesting operations

Science.gov (United States)

Jingxin Wang; Joe McNeel; John Baumgras

2003-01-01

A computer-based time study system was developed for timber harvesting operations. Object-oriented techniques were used to model and design the system. The front-end of the time study system resides on the MS Windows CE and the back-end is supported by MS Access. The system consists of three major components: a handheld system, data transfer interface, and data storage...

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.

Timing is everything: priority effects alter community invasibility after disturbance.

Science.gov (United States)

Symons, Celia C; Arnott, Shelley E

2014-02-01

Theory suggests that communities should be more open to the establishment of regional species following disturbance because disturbance may make more resources available to dispersers. However, after an initial period of high invasibility, growth of the resident community may lead to the monopolization of local resources and decreased probability of successful colonist establishment. During press disturbances (i.e., directional environmental change), it remains unclear what effect regional dispersal will have on local community structure if the establishment of later arriving species is affected by early arriving species (i.e., if priority effects are important). To determine the relationship between time-since-disturbance and invasibility, we conducted a fully factorial field mesocosm experiment that exposed tundra zooplankton communities to two emerging stressors - nutrient and salt addition, and manipulated the arrival timing of regional dispersers. Our results demonstrate that invasibility decreases with increasing time-since-disturbance as abundance (nutrient treatments) or species richness (salt treatments) increases in the resident community. Results suggest that the relative timing of dispersal and environmental change will modify the importance of priority effects in determining species composition after a press disturbance.

Time Operators and Time Crystals

OpenAIRE

Nakatsugawa, K.; Fujii, T.; Saxena, A.; Tanda, S.

2017-01-01

We investigate time operators in the context of quantum time crystals in ring systems. We demonstrate that a self-adjoint time operator with a periodic time evolution can be derived for a free particle on a ring system: The conventional Aharonov-Bohm time operator is obtained by taking the infinite-radius limit. We also reveal the relationship between our time operator and a $\\mathcal PT$-symmetric time operator. We find that both time operators indeed describe the periodic time evolution of ...

Decay times in one-dimensional chains

International Nuclear Information System (INIS)

Van den Broeck, C.; Bouten, M.

1986-01-01

The authors calculate the average residence time tau for a particle performing a random walk over a chain of N neighboring sites i = 1,..., N, with decay rates λ/sub i/ depending on the location of the particle in the chain. Exact results are given for some particular cases, while bounds on tau are given for specific initial conditions. In the continuum limit, various results from the literature are recovered or improved upon

Some Examples of Residence-Time Distribution Studies in Large-Scale Chemical Processes by Using Radiotracer Techniques

Energy Technology Data Exchange (ETDEWEB)

Bullock, R. M.; Johnson, P.; Whiston, J. [Imperial Chemical Industries Ltd., Billingham, Co., Durham (United Kingdom)

1967-06-15

The application of radiotracers to determine flow patterns in chemical processes is discussed with particular reference to the derivation of design data from model reactors for translation to large-scale units, the study of operating efficiency and design attainment in established plant and the rapid identification of various types of process malfunction. The requirements governing the selection of tracers for various types of media are considered and an example is given of the testing of the behaviour of a typical tracer before use in a particular large-scale process operating at 250 atm and 200 Degree-Sign C. Information which may be derived from flow patterns is discussed including the determination of mixing parameters, gas hold-up in gas/liquid reactions and the detection of channelling and stagnant regions. Practical results and their interpretation are given in relation to an define hydroformylation reaction system, a process for the conversion of propylene to isopropanol, a moving bed catalyst system for the isomerization of xylenes and a three-stage gas-liquid reaction system. The use of mean residence-time data for the detection of leakage between reaction vessels and a heat interchanger system is given as an example of the identification of process malfunction. (author)

Medication Refusal: Resident Rights, Administration Dilemma.

Science.gov (United States)

Haskins, Danielle R; Wick, Jeannette Y

2017-12-01

Occasionally, residents actively or passively refuse to take medications. Residents may refuse medication for a number of reasons, including religious beliefs, dietary restrictions, misunderstandings, cognitive impairment, desire to self-harm, or simple inconvenience. This action creates a unique situation for pharmacists and long-term facility staff, especially if patients have dementia. Residents have the legal right to refuse medications, and long-term care facilities need to employ a process to resolve disagreement between the health care team that recommends the medication and the resident who refuses it. In some cases, simple interventions like selecting a different medication or scheduling medications in a different time can address and resolve the resident's objection. If the medical team and the resident cannot resolve their disagreement, often an ethics consultation is helpful. Documenting the resident's refusal to take any or all medications, the health care team's actions and any other outcomes are important. Residents' beliefs may change over time, and the health care team needs to be prepared to revisit the issue as necessary.

Pediatric resident perceptions of family-friendly benefits.

Science.gov (United States)

Berkowitz, Carol D; Frintner, Mary Pat; Cull, William L

2010-01-01

The aim of this study was to examine the importance of family-friendly features in residency program selection, benefits offered to and used by residents, and importance of benefits in future job selection. A survey of a random, national sample of 1000 graduating pediatric residents in 2008 was mailed and e-mailed. Survey response rate for graduating resident respondents was 59%. Among the respondents, 76% were women. Thirty-seven percent of men and 32% of women were parents. Residents with children were more likely than residents without children to rate family-friendly characteristics as very important in their residency selection (P maternity leave (88%), paternity leave (59%), individual flexibility with schedule (63%), and lactation rooms (55%), but fewer reported on-site child care (24%), care for ill children (19%), and part-time residency positions (12%). Among residents reporting availability, 77% of women with children used maternity leave and lactation rooms. Few held part-time residency positions (2%), but many expressed interest (23% of women with children). The majority of residents with and without children reported that flexibility with schedule was important in their future job selection. Most women with children (71%) and many women without children (52%) considered part-time work to be very important in their job selection. Family-friendly benefits are important to residents, particularly those with children. The data provides a benchmark for the availability and use of family-friendly features at pediatric training programs. The data also shows that many residents are unaware if benefits are offered, which suggests a need to make available benefits more transparent to residents. Copyright 2010 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Common Factors Among Family Medicine Residents Who Encounter Difficulty.

Science.gov (United States)

Binczyk, Natalia M; Babenko, Oksana; Schipper, Shirley; Ross, Shelley

2018-04-01

Residents in difficulty are costly to programs in both time and resources, and encountering difficulty can be emotionally harmful to residents. Approximately 10% of residents will encounter difficulty at some point in training. While there have been several studies looking at common factors among residents who encounter difficulty, some of the findings are inconsistent. The objective of this study was to determine whether there are common factors among the residents who encounter difficulty during training in a large Canadian family medicine residency program. Secondary data analysis was performed on archived resident files from a Canadian family medicine residency program. Residents who commenced an urban family medicine residency program between the years of 2006 and 2014 were included in the study. Five hundred nine family medicine residents were included in data analysis. Residents older than 30 years were 2.33 times (95% CI: 1.27-4.26) more likely to encounter difficulty than residents aged 30 years or younger. Nontransfer residents were 8.85 times (95% CI: 1.17-66.67) more likely to encounter difficulty than transfer residents. The effects of sex, training site, international medical graduate status, and rotation order on the likelihood of encountering difficulty were nonsignificant. Older and nontransfer residents may be facing unique circumstances and may benefit from additional support from the program.

[The European Working Time Directive and surgical residents' expertise: no effect on the number of operations].

Science.gov (United States)

Guicherit, Onno R

2015-01-01

Residents' working hours in the Netherlands were first capped in the early 1990 s. In 2003, European legislation consolidated restrictions to a 48-hour week. No adverse effects were seen on the number of surgical operations performed either in the first or the second decade following these measures. Either the effect on surgical training is minimal, or the number of operations carried out during a residency is not a meaningful indicator of its quality. Personalized modular rotations in both university and teaching hospitals are needed for residents with sub-specializations. Training activities, in combination with more supervision, have to focus on a broader set of competencies beyond simply mastering surgical procedures.

Implementation of a "Flipped Classroom" for Neurosurgery Resident Education.

Science.gov (United States)

Girgis, Fady; Miller, Jonathan P

2018-01-01

Engaging residents across a multiyear training spectrum is challenging given the heterogeneity of experience and limited time available for educational activities. A "flipped classroom" model, in which residents prepare ahead of time for mentored topic discussions, has potential advantages. We implemented a curriculum consisting of topics distributed across the specialty. Weekly, each resident was randomly assigned to research a specific aspect of an assigned topic appropriate to his or her level of experience: junior residents about what characterizes each clinical entity, midlevel residents about when to intervene, and chief residents about how to administer treatment. Residents completed an anonymous survey 6 months after implementation. Board examination performance was assessed before and after implementation. A total of 12 residents participated in the program. Weekly, 1.75±0.40 hours were spent in preparation, with senior residents reporting less time than junior residents. All residents indicated that the accumulation of experience across 7 years of residency was a major advantage of this program, and all preferred it to lectures. Performance on the board examination significantly increased after implementation (from 316±36 to 468±45, pflipped classroom is a viable approach to resident education and is associated with increased engagement and improved performance using validated knowledge-assessment tools.

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.

Geochemical modelling of groundwater evolution and residence time at the Kivetty site

International Nuclear Information System (INIS)

Pitkaenen, P.; Luukkonen, A.; Ruotsalainen, P.; Leino-Forsman, H.; Vuorinen, U.

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.)

DSM-IV: a nosology sold before its time?

Science.gov (United States)

Zimmerman, M; Jampala, V C; Sierles, F S; Taylor, M A

1991-04-01

The purpose of this study was to determine whether American psychiatrists believe that DSM-IV is being published too soon after DSM-III-R. The authors conducted a mail survey of the attitudes of practicing psychiatrists (N = 454), residency program directors (N = 128), residents (N = 1,331), and researchers (N = 196) toward the scheduled publication of DSM-IV in the early 1990s. They found that the majority of all four groups believed that DSM-IV is being published prematurely. In contrast to respondents who believed that the timing of DSM-IV is appropriate, those who indicated that it is being published too soon had more recently completed their residency training and also believed that DSM-III-R was published prematurely. There was no association between the psychiatrists' responses and their theoretical orientation, Board certification status, ownership of the DSM manuals, the length of time they had used DSM-III, and the diagnostic manual (DSM-III or DSM-III-R) they were currently using. The belief that DSM-IV is being published too soon could contribute to underuse of DSM-IV by substantial numbers of psychiatrists. Thus, to foster compliance with it, APA must preserve in its efforts to demonstrate that the advantages of publishing it in 1993 outweigh the disadvantages of adopting yet another manual.

Pathology resident and fellow education in a time of disruptive technologies.

Science.gov (United States)

Ziai, James M; Smith, Brian R

2012-12-01

The development of disruptive technologies is changing the practice of pathology. Their implementation challenges traditional educational paradigms. Training programs must adapt to these heuristic needs. The dual explosion of new medical knowledge and innovative methodologies adds new practice aspects to the pathologist's areas of expertise. This transformation potentially challenges the traditional core model of training. It raises questions as to how pathology should incorporate future expanding subspecialty needs into educational and practice models. This article examines the impact of these disruptive technologies on resident and fellow education and explores alternative educational and practice models that may better accommodate pathology's future. Copyright © 2012 Elsevier Inc. All rights reserved.

Part-time employment of gynecologists and obstetricians: a sub-group analysis of a Germany-wide survey of residents.

Science.gov (United States)

Schott, Sarah; Lermann, Johannes; Eismann, Sabine; Neimann, Johannes; Knabl, Julia

2017-01-01

Combining family and career is increasingly taken for granted in many fields. However, the medical profession in Germany has inadequately developed structures. Little is known regarding the satisfaction of physicians working part-time (PT). This Germany-wide on-line survey collected information on the working situation of PT employees (PTE) in gynecology. An anonymous questionnaire with 95 items, nine of which concerned PT work, was sent to 2770 residents and physicians undergoing further specialist training. Of the 481 participants, 104 (96 % female, 4 % male) stated they worked PT, which is greater than the national average. 94 % of all women and 60 % of all men would work PT for better compatibility between work and family life. The PTE regularly work night shifts (NS) (96 %) and weekends (98 %). The number of monthly NS (median 5-9) was not different between the full-time (FT) employees and the PTE who work >75 %. Only when the working hours are reduced by 25 % or more, there are fewer NS (median 1-4) PTE that have a desire for fewer NS. The classic PT model is seldom realized; over 70 % of PTE work whole days, while other working models do not play a major role in Germany. On-call models were subjectively declared to have the best family friendly work-life balance. The results obtained indicated that structures must be developed that to address the problem of childcare and the long working hours to ensure comprehensive medical care from specialists.

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

ERICA: leisure-time physical inactivity in Brazilian adolescents.

Science.gov (United States)

Cureau, Felipe Vogt; da Silva, Thiago Luiz Nogueira; Bloch, Katia Vergetti; Fujimori, Elizabeth; Belfort, Dilson Rodrigues; de Carvalho, Kênia Mara Baiocchi; de Leon, Elisa Brosina; de Vasconcellos, Mauricio Teixeira Leite; Ekelund, Ulf; Schaan, Beatriz D

2016-02-01

OBJECTIVE To evaluate the prevalence of leisure-time physical inactivity in Brazilian adolescents and their association with geographical and sociodemographic variables. METHODS The sample was composed by 74,589 adolescents participating in the Study of Cardiovascular Risks in Adolescents (ERICA). This cross-sectional study of school basis with national scope involved adolescents aged from 12 to 17 years in Brazilian cities with more than 100 thousand inhabitants. The prevalence of leisure-time physical inactivity was categorized according to the volume of weekly practice (physical inactivity was 54.3% (95%CI 53.4-55.2), and higher for the female sex (70.7%, 95%CI 69.5-71.9) compared to the male (38.0%, 95%CI 36.7-39.4). More than a quarter of adolescents (26.5%, 95%CI 25.8-27.3) reported not practicing physical activity in the leisure time, a condition more prevalent for girls (39.8%, 95%CI 38.8-40.9) than boys (13.4%, 95%CI 12.4-14.4). For girls, the variables that were associated with physical inactivity were: reside in the Northeast (RP = 1.13, 95%CI 1.08-1.19), Southeast (RP = 1.16, 95%CI 1.11-1.22) and South (RP = 1.12, 95%CI 1.06-1.18); have 16-17 years (RP = 1.06, 95%CI 1.12-1.15); and belong to the lower economic class (RP = 1.33, 95%CI 1.20-1.48). The same factors, except reside in the Southeast and South, were also associated with not practicing physical activity in the leisure time for the same group. In males, as well as the region, being older (p physical activities in the leisure time. CONCLUSIONS The prevalence of leisure-time physical inactivity in Brazilian adolescents is high. It presents regional variations and is associated with age and low socioeconomic status. Special attention should be given to girls and to those who do not engage in any physical activity during the leisure time, so that they can adopt a more active lifestyle.

Pediatric dermatology training survey of United States dermatology residency programs.

Science.gov (United States)

Nijhawan, Rajiv I; Mazza, Joni M; Silverberg, Nanette B

2014-01-01

Variability exists in pediatric dermatology education for dermatology residents. We sought to formally assess the pediatric dermatology curriculum and experience in a dermatology residency program. Three unique surveys were developed for dermatology residents, residency program directors, and pediatric dermatology fellowship program directors. The surveys consisted of questions pertaining to residency program characteristics. Sixty-three graduating third-year residents, 51 residency program directors, and 18 pediatric dermatology fellowship program directors responded. Residents in programs with one or more full-time pediatric dermatologist were more likely to feel very competent treating children and were more likely to be somewhat or extremely satisfied with their pediatric curriculums than residents in programs with no full-time pediatric dermatologist (50.0% vs 5.9%, p = 0.002, and 85.3% vs 52.9%, p dermatology fellowships were much more likely to report being extremely satisfied than residents in programs without a pediatric dermatology fellowship (83.3% vs 21.2%; p dermatology residency programs to continue to strengthen their pediatric dermatology curriculums, especially through the recruitment of full-time pediatric dermatologists. © 2013 Wiley Periodicals, Inc.

Reproductive Psychiatry Residency Training: A Survey of Psychiatric Residency Program Directors.

Science.gov (United States)

Osborne, Lauren M; MacLean, Joanna V; Barzilay, Erin Murphy; Meltzer-Brody, Samantha; Miller, Laura; Yang, Sarah Nagle

2018-04-01

The reproductive life cycle has unique influences on the phenotypic expression of mental illness in women. Didactic and clinical training focused on these sex-specific influences should be a vital component of the education of future psychiatrists. The authors sought to determine the current state of and attitudes toward reproductive psychiatry in resident education. The authors administered a web-based survey to psychiatry residency training directors. They assessed the availability of both mandated and optional didactic and clinical training experiences in reproductive psychiatry. Fifty residency program directors answered the survey, for a response rate of 28%. More than half of residency program directors (59%) reported requiring some training in reproductive psychiatry. Both the breadth and depth of topics covered varied greatly among programs. Lack of time (48%) and lack of qualified faculty (26%) were the most frequently cited barriers to more training. Only 40% of residency directors surveyed agreed that all residents should be competent in reproductive psychiatry. These findings suggest that specific training in reproductive psychiatry is inconsistent in US residency programs, and that training that does exist varies considerably in clinical time and content. Given that women comprise more than 50% of all psychiatric patients and most women will menstruate, give birth, and undergo menopause, future psychiatrists would benefit from more systematic instruction in this area. The authors propose the development of a national, standardized reproductive psychiatry curriculum to address this gap and aid in producing psychiatrists competent to treat women at all stages of life.

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

Western aeronautical test range real-time graphics software package MAGIC

Science.gov (United States)

Malone, Jacqueline C.; Moore, Archie L.

1988-01-01

The master graphics interactive console (MAGIC) software package used on the Western Aeronautical Test Range (WATR) of the NASA Ames Research Center is described. MAGIC is a resident real-time research tool available to flight researchers-scientists in the NASA mission control centers of the WATR at the Dryden Flight Research Facility at Edwards, California. The hardware configuration and capabilities of the real-time software package are also discussed.

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

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.

Personal Therapy in Psychiatry Residency Training: A National Survey of Canadian Psychiatry Residents.

Science.gov (United States)

Hadjipavlou, George; Halli, Priyanka; Hernandez, Carlos A Sierra; Ogrodniczuk, John S

2016-02-01

The authors collected nationally representative data on Canadian residents' experiences with and perspectives on personal psychotherapy in their psychiatric training. A 43-item questionnaire was distributed electronically to all current psychiatry residents in Canada (N = 839). Four hundred residents from every program across Canada returned the survey (response rate 47.7%). The prevalence of personal therapy at any time was 55.3%, with 42.8% receiving personal therapy during residency. Of residents who undertook personal psychotherapy, 59.3% engaged in weekly therapy, 74.1% received psychodynamic psychotherapy, and 81.5% participated in long-term therapy (>1 year). Personal growth, self-understanding, and professional development were the most common reasons for engaging in personal therapy; however, one-third of residents did so to alleviate symptoms of depression, anxiety, or other mental health concerns. Time was the most important factor impeding residents from personal therapy; only 8.8% found stigma to act as a barrier. The vast majority of residents rated their experience with personal therapy as having a positive or very positive impact on their personal life (84.8%) and overall development as psychiatrists (81.8%). For 64% of respondents, personal therapy had an important or very important role in psychiatry residency training. Residents who received personal therapy rated themselves as better able to understand what happens moment by moment during therapy sessions, detect and deal with patients' emotional reactions, and constructively use their personal reactions to patients. Interest in personal therapy remains strong among psychiatry trainees in Canada. Residents who engaged in psychotherapy endorsed greater confidence in psychotherapy and rated their psychotherapy skills more favorably than those who had never been in the patient role, supporting the view of personal therapy as an important adjunct to psychotherapy training during residency.

Patient-Centered Handovers: Ethnographic Observations of Attending and Resident Physicians: Ethnographic Observations of Attending and Resident Physicians.

Science.gov (United States)

Mount-Campbell, Austin F; Rayo, Michael F; OʼBrien, James J; Allen, Theodore T; Patterson, Emily S

Handover communication improvement initiatives typically employ a "one size fits all" approach. A human factors perspective has the potential to guide how to tailor interventions to roles, levels of experience, settings, and types of patients. We conducted ethnographic observations of sign-outs by attending and resident physicians in 2 medical intensive care units at one institution. Digitally audiotaped data were manually analyzed for content using codes and time spent using box plots for emergent categories. A total of 34 attending and 58 resident physician handovers were observed. Resident physicians spent more time for "soon to be discharged" and "higher concern" patients than attending physicians. Resident physicians spent less time discussing patients which they had provided care for within the last 3 days ("handbacks"). The study suggested differences for how handovers were conducted for attending and resident physicians for 3 categories of patients; handovers differ on the basis of role or level of expertise, patient type, and amount of prior knowledge of the patient. The findings have implications for new directions for subsequent research and for how to tailor quality improvement interventions based upon the role, level of experience, level of prior knowledge, and patient categories.

Time over time

Directory of Open Access Journals (Sweden)

Vicente Navarro, Eduardo

2006-05-01

Full Text Available The present essay is designed to be a general introduction to the philosophical problem of time from its very different forms and ways of approaching. In this sense, the article covers the problem from different perspectives and gives a brief account of the plurality and diversity of the time found in the different philosophical definitions, in the different layers of knowledge, in different periods and cultures and also in the different instruments used to measure time itself

Frozen section evaluation via dynamic real-time non-robotic Telepathology system in a university Cancer center by resident / faculty cooperation team.

Science.gov (United States)

Vosoughi, Aram; Smith, Paul Taylor; Zeitouni, Joseph A; Sodeman, Gregori M; Jorda, Merce; Gomez-Fernandez, Carmen; Garcia-Buitrago, Monica; Petito, Carol K; Chapman, Jennifer R; Campuzano-Zuluaga, German; Rosenberg, Andrew E; Kryvenko, Oleksandr N

2018-04-30

Frozen section telepathology interpretation experience has been largely limited to practices with locations significantly distant from one another with sporadic need for frozen section diagnosis. In 2010 we established a real-time non-robotic telepathology system in a very active cancer center for daily frozen section service. Herein, we evaluate its accuracy compared to direct microscopic interpretation performed in the main hospital by the same faculty and its cost-efficiency over a 1-year period. From 643 (1416 parts) cases requiring intraoperative consultation, 333 cases (690 parts) were examined by telepathology and 310 cases (726 parts) by direct microscopy. Corresponding discrepancy rates were 2.6% (18 cases: 6 (0.9%) sampling and 12 (1.7%) diagnostic errors) and 3.2% (23 cases: 8 (1.1%) sampling and 15 (2.1%) diagnostic errors), P=.63. The sensitivity and specificity of intraoperative frozen diagnosis were 0.92 and 0.99, respectively, in telepathology, and 0.90 and 0.99, respectively, in direct microscopy. There was no correlation of error incidence with post graduate year level of residents involved in the telepathology service. Cost analysis indicated that the time saved by telepathology was $19691 over one year of the study period while the capital cost for establishing the system was $8924. Thus, real-time non-robotic telepathology is a reliable and easy to use tool for frozen section evaluation in busy clinical settings, especially when frozen section service involves more than one hospital, and it is cost efficient when travel is a component of the service. Copyright © 2018. Published by Elsevier Inc.

Does Daylight Savings Time encourage physical activity?

Science.gov (United States)

Zick, Cathleen D

2014-07-01

Extending Daylight Savings Time (DST) has been identified as a policy intervention that may encourage physical activity. However, there has been little research on the question of if DST encourages adults to be more physically active. Data from residents of Arizona, Colorado, New Mexico, and Utah ages 18-64 who participated in the 2003-2009 American Time Use Survey are used to assess whether DST is associated with increased time spent in moderate-to-vigorous physical activity (MVPA). The analysis capitalizes on the natural experiment created because Arizona does not observe DST. Both bivariate and multivariate analyses indicate that shifting 1 hour of daylight from morning to evening does not impact MVPA of Americans living in the southwest. While DST may affect the choices people make about the timing and location of their sports/recreational activities, the potential for DST to serve as a broad-based intervention that encourages greater sports/recreation participation is not supported by this analysis. Whether this null effect would persist in other climate situations is an open question.

Evaluating Residence Time for Cesium Removal from Simulated Hanford Tank Wastes Using SuperLig(R) 644 Resin

International Nuclear Information System (INIS)

Hassan, N.M.

2003-01-01

Batch contact and column experiments were performed to evaluate the effect of residence time on cesium (Cs) removal from two simulated Hanford tank wastes using SuperLig(R) 644 resin. The two waste simulants mimic the compositions of tanks 241-AZ-102 and 241-AN-107 at the U.S. Department of Energy (DOE) Hanford site. A single column made of glass tube (2.7-cm i.d.), which contained approximately 100 mL of H-form SuperLig(R) 644 resin was used in the column experiments. The experiments each consisted of loading, elution, and regeneration steps were performed at flow rates ranging from 0.64 to 8.2 BV/h for AZ-102 and from 1.5 to 18 BV/h for AN-107 simulant. The lowest flow rates of 0.64 and 1.5 BV/h were selected to evaluate less than optimal flow conditions in the plant. The range of the flow rates is consistent with the River Protection Project design for the waste treatment plant (WTP) columns, which will operate at a flow rate between 1.5 to 3 BV/h. Batch contact experiments were also performed for two batches of SuperLig(R) 644 to determine the equilibrium distribution coefficients (Kds) as a function of Cs concentration

Residence times and mixing of water in river banks: implications for recharge and groundwater-surface water exchange

Science.gov (United States)

Unland, N. P.; Cartwright, I.; Cendón, D. I.; Chisari, R.

2014-12-01

Bank exchange processes within 50 m of the Tambo River, southeast Australia, have been investigated through the combined use of 3H and 14C. Groundwater residence times increase towards the Tambo River, which suggests the absence of significant bank storage. Major ion concentrations and δ2H and δ18O values of bank water also indicate that bank infiltration does not significantly impact groundwater chemistry under baseflow and post-flood conditions, suggesting that the gaining nature of the river may be driving the return of bank storage water back into the Tambo River within days of peak flood conditions. The covariance between 3H and 14C indicates the leakage and mixing between old (~17 200 years) groundwater from a semi-confined aquifer and younger groundwater (bank infiltration. Furthermore, the more saline deeper groundwater likely controls the geochemistry of water in the river bank, minimising the chemical impact that bank infiltration has in this setting. These processes, coupled with the strongly gaining nature of the Tambo River are likely to be the factors reducing the chemical impact of bank storage in this setting. This study illustrates the complex nature of river groundwater interactions and the potential downfall in assuming simple or idealised conditions when conducting hydrogeological studies.

2003 survey of Canadian radiation oncology residents

International Nuclear Information System (INIS)

Yee, Don; Fairchild, Alysa; Keyes, Mira; Butler, Jim; Dundas, George

2005-01-01

Purpose: Radiation oncology's popularity as a career in Canada has surged in the past 5 years. Consequently, resident numbers in Canadian radiation oncology residencies are at all-time highs. This study aimed to survey Canadian radiation oncology residents about their opinions of their specialty and training experiences. Methods and Materials: Residents of Canadian radiation oncology residencies that enroll trainees through the Canadian Resident Matching Service were identified from a national database. Residents were mailed an anonymous survey. Results: Eight of 101 (7.9%) potential respondents were foreign funded. Fifty-two of 101 (51.5%) residents responded. A strong record of graduating its residents was the most important factor residents considered when choosing programs. Satisfaction with their program was expressed by 92.3% of respondents, and 94.3% expressed satisfaction with their specialty. Respondents planning to practice in Canada totaled 80.8%, and 76.9% plan to have academic careers. Respondents identified job availability and receiving adequate teaching from preceptors during residency as their most important concerns. Conclusions: Though most respondents are satisfied with their programs and specialty, job availability and adequate teaching are concerns. In the future, limited time and resources and the continued popularity of radiation oncology as a career will magnify the challenge of training competent radiation oncologists in Canada

Medical Student Interest in Flexible Residency Training Options.

Science.gov (United States)

Piotrowski, Madison; Stulberg, Debra; Egan, Mari

2018-05-01

Medical residents continue to experience high rates of burnout during residency training even after implementation of the 2003 Accreditation Council for Graduate Medical Education duty-hour restrictions. The purpose of this study is to determine medical student interest in flexible residency training options. Researchers developed an 11-question survey for second through fourth-year medical students. The populations surveyed included medical students who were: (1) attending the 2015 American Academy of Family Physicians National Conference, the 2015 Family Medicine Midwest Conference, and (2) enrolled at University of Chicago Pritzker School of Medicine, University of Illinois College of Medicine at Chicago, Drexel University College of Medicine, and Case Western Reserve University School of Medicine. The survey was completed by 789 medical students. Over half of medical students surveyed indicated that they would be interested in working part-time during some portion of their residency training (51%), and that access to part-time training options would increase their likelihood of applying to a particular residency program (52%). When given the option of three residency training schedules of varying lengths, 41% of male students and 60% of female students chose a 60-hour workweek, even when that meant extending the residency length by 33% and reducing their yearly salary to $39,000. There is considerable interest among medical students in access to part-time residency training options and reduced-hour residency programs. This level of interest indicates that offering flexible training options could be an effective recruitment tool for residency programs and could improve students' perception of their work-life balance during residency.

The importance of timing for breaking commuters’ car driving habits

DEFF Research Database (Denmark)

Thøgersen, John

2012-01-01

consistent with the traveller’s conscious intentions. However, the behavioural effects of the free travel card appeared only among individuals who had recently relocated residence or workplace, prior to the intervention. This suggests that timing is essential when designing interventions to promote...

The "resident's dilemma"? Values and strategies of medical residents for education interactions: a cellular automata simulation.

Science.gov (United States)

Heckerling, P S; Gerber, B S; Weiner, S J

2006-01-01

Medical residents engage in formal and informal education interactions with fellow residents during the working day, and can choose whether to spend time and effort on such interactions. Time and effort spent on such interactions can bring learning and personal satisfaction to residents, but may also delay completion of clinical work. Using hypothetical cases, we assessed the values and strategies of internal medicine residents at one hospital for both cooperative and non-cooperative education interactions with fellow residents. We then used these data and cellular automata models of two-person games to simulate repeated interactions between residents, and to determine which strategies resulted in greatest accrued value. We conducted sensitivity analyses on several model parameters, to test the robustness of dominant strategies to model assumptions. Twenty-nine of the 57 residents (50.9%) valued cooperation more than non-cooperation no matter what the other resident did during the current interaction. Similarly, thirty-six residents (63.2%) endorsed an unconditional always-cooperate strategy no matter what the other resident had done during their previous interaction. In simulations, an always-cooperate strategy accrued more value (776.42 value units) than an aggregate of strategies containing non-cooperation components (675.0 value units, p = 0.052). Only when the probability of strategy errors reached 50%, or when values were re-ordered to match those of a Prisoner's Dilemma, did non-cooperation-based strategies accrue the most value. Cooperation-based values and strategies were most frequent among our residents, and dominated in simulations of repeated education interactions between them.

The effect of centralization of health care services on travel time and its equality.

Science.gov (United States)

Kobayashi, Daisuke; Otsubo, Tetsuya; Imanaka, Yuichi

2015-03-01

To analyze the regional variations in travel time between patient residences and medical facilities for the treatment of ischemic heart disease and breast cancer, and to simulate the effects of health care services centralization on travel time and equality of access. We used medical insurance claims data for inpatients and outpatients for the two target diseases that had been filed between September 2008 and May 2009 in Kyoto Prefecture, Japan. Using a geographical information system, patient travel times were calculated based on the driving distance between patient residences and hospitals via highways and toll roads. Locations of residences and hospital locations were identified using postal codes. We then conducted a simulation analysis of centralization of health care services to designated regional core hospitals. The simulated changes in potential spatial access to care were examined. Inequalities in access to care were examined using Gini coefficients, which ranged from 0.4109 to 0.4574. Simulations of health care services centralization showed reduced travel time for most patients and overall improvements in equality of access, except in breast cancer outpatients. Our findings may contribute to the decision-making process in policies aimed at improving the potential spatial access to health care services. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Where Do Ethno-Linguistic Groups Meet? How Copresence during Free-Time Is Related to Copresence at Home and at Work.

Directory of Open Access Journals (Sweden)

Ott Toomet

Full Text Available This paper analyzes ethnic segregation across the whole activity space-at place of residence, place of work, and during free-time. We focus on interethnic meeting potential during free-time, measured as copresence, and its relationship to copresence at place of residence and work. The study is based on cellphone data for a medium-sized linguistically divided European city (Tallinn, Estonia, where the Estonian majority and mainly Russian-speaking minority populations are of roughly equal size. The results show that both places of residence and work are segregated, while other activities occur in a far more integrated environment. Copresence during free-time is positively associated with copresence at place of residence and work, however, the relationship is very weak.

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.

Investigation of residence time and groundwater flux in Venice Lagoon: comparing radium isotope and hydrodynamical models

International Nuclear Information System (INIS)

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

2010-01-01

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 224 Ra to 228 Ra determined from 30 monitoring stations and a mean pore water endmember. 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.

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

Ophthalmology resident surgical competency: a national survey.

Science.gov (United States)

Binenbaum, Gil; Volpe, Nicholas J

2006-07-01

To describe the prevalence, management, and career outcomes of ophthalmology residents who struggle with surgical competency and to explore related educational issues. Fourteen-question written survey. Fifty-eight program directors at Accreditation Council on Graduate Medical Education-accredited, United States ophthalmology residency programs, representing a total of 2179 resident graduates, between 1991 and 2000. Study participants completed a mailed, anonymous survey whose format combined multiple choice and free comment questions. Number of surgically challenged residents, types of problems identified, types of remediation, final departmental decision at the end of residency, known career outcomes, and residency program use of microsurgical skills laboratories and applicant screening tests. One hundred ninety-nine residents (9% overall; 10% mean per program) were labeled as having trouble mastering surgical skills. All of the programs except 2 had encountered such residents. The most frequently cited problems were poor hand-eye coordination (24%) and poor intraoperative judgment (22%). Most programs were supportive and used educational rather than punitive measures, the most common being extra practice-laboratory time (32%), scheduling cases with the best teaching surgeon (23%), and counseling (21%). Nearly one third (31%) of residents were believed to have overcome their difficulties before graduation. Other residents were encouraged to pursue medical ophthalmology (22%) or to obtain further surgical training through a fellowship (21%) or a supervised practice setting (12%); these residents were granted a departmental statement of satisfactory completion of residency for Board eligibility. Twelve percent were asked to leave residency. Of reported career outcomes, 92% of residents were practicing ophthalmology, 65% as surgical and 27% as medical ophthalmologists. Ninety-eight percent of residency programs had microsurgical practice facilities, 64% had a formal

Trends in U.S. adult chronic disability rates over time.

Science.gov (United States)

Iezzoni, Lisa I; Kurtz, Stephen G; Rao, Sowmya R

2014-10-01

Trends in the patterns and prevalence of chronic disability among U.S. residents carry important implications for public health and public policies across multiple societal sectors. To examine trends in U.S. adult population rates of chronic disability from 1998 to 2011 using 7 different disability measures and examining the implications of trends in population age, race and ethnicity, and body mass index (BMI). We used National Health Interview Survey data on civilian, non-institutionalized U.S. residents ages ≥ 18 from selected years between 1998 and 2011. We used self-reported information on functional impairments, activity/participation limitations, and expected duration to create 7 chronic disability measures. We used direct standardization to account for changes in age, race/ethnicity, and BMI distributions over time. Multivariable logistic regression models identified associations of disability with sociodemographic characteristics. Without adjustment, population rates of all 7 disabilities increased significantly (p disability types continued to show increased rates over time (p disability. If these trends continue, the numbers and proportions of U.S. residents with various disabilities will continue rising in coming years. In particular, the prevalence of movement difficulties and work limitations will increase. Furthermore, disability will remain strongly associated with low levels of education, employment, and income. Copyright © 2014 Elsevier Inc. All rights reserved.

Surgical Pathology Resident Rotation Restructuring at a Tertiary Care Academic Center.

Science.gov (United States)

Mehr, Chelsea R; Obstfeld, Amrom E; Barrett, Amanda C; Montone, Kathleen T; Schwartz, Lauren E

2017-01-01

Changes in the field of pathology and resident education necessitate ongoing evaluation of residency training. Evolutionary change is particularly important for surgical pathology rotations, which form the core of anatomic pathology training programs. In the past, we organized this rotation based on subjective insight. When faced with the recent need to restructure the rotation, we strove for a more evidence-based process. Our approach involved 2 primary sources of data. We quantified the number of cases and blocks submitted per case type to estimate workload and surveyed residents about the time required to gross specimens in all organ systems. A multidisciplinary committee including faculty, residents, and staff evaluated the results and used the data to model how various changes to the rotation would affect resident workload, turnaround time, and other variables. Finally, we identified rotation structures that equally distributed work and created a point-based system that capped grossing time for residents of different experience. Following implementation, we retrospectively compared turnaround time and duty hour violations before and after these changes and surveyed residents about their experiences with both systems. We evaluated the accuracy of the point-based system by examining grossing times and comparing them to the assigned point values. We found overall improvement in the rotation following the implementation. As there is essentially no literature on the subject of surgical pathology rotation organization, we hope that our experience will provide a road map to improve pathology resident education at other institutions.

Surgical Pathology Resident Rotation Restructuring at a Tertiary Care Academic Center

Directory of Open Access Journals (Sweden)

Chelsea R. Mehr MD

2017-11-01

Full Text Available Changes in the field of pathology and resident education necessitate ongoing evaluation of residency training. Evolutionary change is particularly important for surgical pathology rotations, which form the core of anatomic pathology training programs. In the past, we organized this rotation based on subjective insight. When faced with the recent need to restructure the rotation, we strove for a more evidence-based process. Our approach involved 2 primary sources of data. We quantified the number of cases and blocks submitted per case type to estimate workload and surveyed residents about the time required to gross specimens in all organ systems. A multidisciplinary committee including faculty, residents, and staff evaluated the results and used the data to model how various changes to the rotation would affect resident workload, turnaround time, and other variables. Finally, we identified rotation structures that equally distributed work and created a point-based system that capped grossing time for residents of different experience. Following implementation, we retrospectively compared turnaround time and duty hour violations before and after these changes and surveyed residents about their experiences with both systems. We evaluated the accuracy of the point-based system by examining grossing times and comparing them to the assigned point values. We found overall improvement in the rotation following the implementation. As there is essentially no literature on the subject of surgical pathology rotation organization, we hope that our experience will provide a road map to improve pathology resident education at other institutions.

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.

SU-E-T-45: Antibody Mean Residence Time in Blood and Its Correlation with Protein Molecular Weight

International Nuclear Information System (INIS)

Kwok, C; Williams, L

2014-01-01

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

Wairarapa Valley groundwater : residence time, flow pattern, and hydrochemistry trends

International Nuclear Information System (INIS)

Morgenstern, U.

2005-01-01

The Wairarapa groundwater system has a complicated hydrogeological setting as it evolved from sea level changes, tectonic activity, and geomorphic process. Due to increasing groundwater demand a better understanding of the groundwater resources is required to help achieve effective management and sustainable use. In addition to previous 'classical' hydrogeology studies, this report represents the first stage of a comprehensive approach using age dating and chemistry time trends for understanding the Wairarapa groundwater system. The methodology of groundwater age dating and mixing models is described in Appendix 1. Historic tritium data were evaluated, and combined with new tritium and CFC/SF 6 data to allow for robust age dating. (author). 14 refs., 30 figs

Are All Competencies Equal in the Eyes of Residents? A Multicenter Study of Emergency Medicine Residents' Interest in Feedback.

Science.gov (United States)

Bentley, Suzanne; Hu, Kevin; Messman, Anne; Moadel, Tiffany; Khandelwal, Sorabh; Streich, Heather; Noelker, Joan

2017-01-01

Feedback, particularly real-time feedback, is critical to resident education. The emergency medicine (EM) milestones were developed in 2012 to enhance resident assessment, and many programs use them to provide focused resident feedback. The purpose of this study was to evaluate EM residents' level of interest in receiving real-time feedback on each of the 23 competencies/sub-competencies. This was a multicenter cross-sectional study of EM residents. We surveyed participants on their level of interest in receiving real-time on-shift feedback on each of the 23 competencies/sub-competencies. Anonymous paper or computerized surveys were distributed to residents at three four-year training programs and three three-year training programs with a total of 223 resident respondents. Residents rated their level of interest in each milestone on a six-point Likert-type response scale. We calculated average level of interest for each of the 23 sub-competencies, for all 223 respondents and separately by postgraduate year (PGY) levels of training. One-way analyses of variance were performed to determine if there were differences in ratings by level of training. The overall survey response rate across all institutions was 82%. Emergency stabilization had the highest mean rating (5.47/6), while technology had the lowest rating (3.24/6). However, we observed no differences between levels of training on any of the 23 competencies/sub-competencies. Residents seem to ascribe much more value in receiving feedback on domains involving high-risk, challenging procedural skills as compared to low-risk technical and communication skills. Further studies are necessary to determine whether residents' perceived importance of competencies/sub-competencies needs to be considered when developing an assessment or feedback program based on these 23 EM competencies/sub-competencies.

Reducing employee travelling time through smart commuting

International Nuclear Information System (INIS)

Rahman, A N N A; Yusoff, Z M; Aziz, I S; Omar, D

2014-01-01

Extremely congested roads will definitely delay the arrival time of each trip.This certainly impacted the journey of employees. Tardiness at the workplace has become a perturbing issue for companies where traffic jams are the most common worker excuses. A depressing consequence on daily life and productivity of the employee occurs. The issues of commuting distance between workplace and resident area become the core point of this research. This research will emphasize the use of Geographical Information System (GIS) technique to explore the distance parameter to the employment area and will focus on the accessibility pattern of low-cost housing. The research methodology consists of interview sessions and a questionnaire to residents of low-cost housing areas in Melaka Tengah District in Malaysia. The combination of these processes will show the criteria from the selected parameter for each respondent from their resident area to the employment area. This will further help in the recommendation of several options for a better commute or improvement to the existing routes and public transportations system. Thus enhancing quality of life for employees and helping to reduce stress, decrease lateness, absenteeism and improving productivity in workplace

Reducing employee travelling time through smart commuting

Science.gov (United States)

Rahman, A. N. N. A.; Yusoff, Z. M.; Aziz, I. S.; Omar, D.

2014-02-01

Extremely congested roads will definitely delay the arrival time of each trip.This certainly impacted the journey of employees. Tardiness at the workplace has become a perturbing issue for companies where traffic jams are the most common worker excuses. A depressing consequence on daily life and productivity of the employee occurs. The issues of commuting distance between workplace and resident area become the core point of this research. This research will emphasize the use of Geographical Information System (GIS) technique to explore the distance parameter to the employment area and will focus on the accessibility pattern of low-cost housing. The research methodology consists of interview sessions and a questionnaire to residents of low-cost housing areas in Melaka Tengah District in Malaysia. The combination of these processes will show the criteria from the selected parameter for each respondent from their resident area to the employment area. This will further help in the recommendation of several options for a better commute or improvement to the existing routes and public transportations system. Thus enhancing quality of life for employees and helping to reduce stress, decrease lateness, absenteeism and improving productivity in workplace.

Axial dispersion, holdup and slip velocity of dispersed phase in a pulsed sieve plate extraction column by radiotracer residence time distribution analysis.

Science.gov (United States)

Din, Ghiyas Ud; Chughtai, Imran Rafiq; Inayat, Mansoor Hameed; Khan, Iqbal Hussain

2008-12-01

Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range of dispersed and continuous phase superficial velocities in a pulsed sieve plate extraction column using radiotracer residence time distribution (RTD) analysis. Axial dispersion model (ADM) was used to simulate the hydrodynamics of the system. It has been observed that increase in dispersed phase superficial velocity results in a decrease in its axial dispersion and increase in its slip velocity while its holdup increases till a maximum asymptotic value is achieved. An increase in superficial velocity of continuous phase increases the axial dispersion and holdup of dispersed phase until a maximum value is obtained, while slip velocity of dispersed phase is found to decrease in the beginning and then it increases with increase in superficial velocity of continuous phase.

The Raptor Real-Time Processing Architecture

Science.gov (United States)

Galassi, M.; Starr, D.; Wozniak, P.; Brozdin, K.

The primary goal of Raptor is ambitious: to identify interesting optical transients from very wide field of view telescopes in real time, and then to quickly point the higher resolution Raptor ``fovea'' cameras and spectrometer to the location of the optical transient. The most interesting of Raptor's many applications is the real-time search for orphan optical counterparts of Gamma Ray Bursts. The sequence of steps (data acquisition, basic calibration, source extraction, astrometry, relative photometry, the smarts of transient identification and elimination of false positives, telescope pointing feedback, etc.) is implemented with a ``component'' approach. All basic elements of the pipeline functionality have been written from scratch or adapted (as in the case of SExtractor for source extraction) to form a consistent modern API operating on memory resident images and source lists. The result is a pipeline which meets our real-time requirements and which can easily operate as a monolithic or distributed processing system. Finally, the Raptor architecture is entirely based on free software (sometimes referred to as ``open source'' software). In this paper we also discuss the interplay between various free software technologies in this type of astronomical problem.

Where do ethno-linguistic groups meet? How copresence during free-time is related to copresence at home and at work

NARCIS (Netherlands)

Toomet, O.; Silm, S.; Saluveer, E.; Ahas, R.; Tammaru, T.

2015-01-01

This paper analyzes ethnic segregation across the whole activity space—at place of residence, place of work, and during free-time. We focus on interethnic meeting potential during free-time, measured as copresence, and its relationship to copresence at place of residence and work. The study is based

Multiplexing real-time timed events

NARCIS (Netherlands)

Holenderski, M.J.; Cools, W.A.; Bril, R.J.; Lukkien, J.J.

2009-01-01

This paper presents the design and implementation of RELTEQ, a timed event management algorithm based on relative event times, supporting long event interarrival time, long lifetime of the event queue, no drift and low overhead. It is targeted at embedded operating systems. RELTEQ has been conceived

"Internet of Things" Real-Time Free Flap Monitoring.

Science.gov (United States)

Kim, Sang Hun; Shin, Ho Seong; Lee, Sang Hwan

2018-01-01

Free flaps are a common treatment option for head and neck reconstruction in plastic reconstructive surgery, and monitoring of the free flap is the most important factor for flap survival. In this study, the authors performed real-time free flap monitoring based on an implanted Doppler system and "internet of things" (IoT)/wireless Wi-Fi, which is a convenient, accurate, and efficient approach for surgeons to monitor a free flap. Implanted Doppler signals were checked continuously until the patient was discharged by the surgeon and residents using their own cellular phone or personal computer. If the surgeon decided that a revision procedure or exploration was required, the authors checked the consumed time (positive signal-to-operating room time) from the first notification when the flap's status was questioned to the determination for revision surgery according to a chart review. To compare the efficacy of real-time monitoring, the authors paired the same number of free flaps performed by the same surgeon and monitored the flaps using conventional methods such as a physical examination. The total survival rate was greater in the real-time monitoring group (94.7% versus 89.5%). The average time for the real-time monitoring group was shorter than that for the conventional group (65 minutes versus 86 minutes). Based on this study, real-time free flap monitoring using IoT technology is a method that surgeon and reconstruction team can monitor simultaneously at any time in any situation.

Effects of time perspective and self-control on procrastination and Internet addiction

OpenAIRE

Kim, Jinha; Hong, Hyeongi; Lee, Jungeun; Hyun, Myoung-Ho

2017-01-01

Background and aims College students experiencing stress show tendencies to procrastinate and can develop Internet addiction problems. This study investigated the structural relationship between time perspective and self-control on procrastination and Internet addiction. Methods College students (N?=?377) residing in South Korea completed the following questionnaires: the Pathological Internet Use Behavior Symptom Scale for Adults, the Zimbardo Time Perspective Inventory, the Self-Control Rat...

Factors associated with television viewing time in toddlers and preschoolers in Greece: the GENESIS study.

Science.gov (United States)

Kourlaba, Georgia; Kondaki, Katerina; Liarigkovinos, Thodoris; Manios, Yannis

2009-06-01

The aim of this work was to describe the television (TV) viewing time of preschoolers and to examine factors that may be associated with it. A representative sample of 2374 Greek children aged 1-5 years was examined (GENESIS study). Several anthropometric, socio-demographic and lifestyle characteristics were recorded. The mean value of children's TV viewing time was 1.32 h/day. Twenty six percent of participants spent > or =2 h/day in TV viewing. The percentage of children whose TV viewing time was longer than 2 h/day was higher in children aged 3-5 years (32.2%) than in those aged 1-2 years (11.1%). Multiple logistic regression revealed that the time parents spent viewing TV and the region of residence were significantly associated with child's TV viewing time among children aged 3-5 years. Among children aged 1-2 years, the maternal educational status, the region of residence and the maternal TV viewing time were found to be related to child's TV viewing time. The current findings suggest that almost one third of Greek preschoolers exceed the limit of 2 h/day TV viewing and that parental TV viewing time may be the most important determinant of children's TV viewing time.

Real time control of the SSC string magnets

International Nuclear Information System (INIS)

Calvo, O.; Flora, R.; MacPherson, M.

1987-01-01

The system described in this paper, called SECAR, was designed to control the excitation of a test string of magnets for the proposed Superconducting Super Collider (SSC) and will be used to upgrade the present Tevatron Excitation, Control and Regulation (TECAR) hardware and software. It resides in a VME orate and is controlled by a 68020/68881 based CPU running the application software under a real time operating system named VRTX

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  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.

Secondary organic aerosol formation by limonene ozonolysis: Parameterizing multi-generational chemistry in ozone- and residence time-limited indoor environments

Science.gov (United States)

Waring, Michael S.

2016-11-01

Terpene ozonolysis reactions can be a strong source of secondary organic aerosol (SOA) indoors. SOA formation can be parameterized and predicted using the aerosol mass fraction (AMF), also known as the SOA yield, which quantifies the mass ratio of generated SOA to oxidized terpene. Limonene is a monoterpene that is at sufficient concentrations such that it reacts meaningfully with ozone indoors. It has two unsaturated bonds, and the magnitude of the limonene ozonolysis AMF varies by a factor of ∼4 depending on whether one or both of its unsaturated bonds are ozonated, which depends on whether ozone is in excess compared to limonene as well as the available time for reactions indoors. Hence, this study developed a framework to predict the limonene AMF as a function of the ozone [O3] and limonene [lim] concentrations and the air exchange rate (AER, h-1), which is the inverse of the residence time. Empirical AMF data were used to calculate a mixing coefficient, β, that would yield a 'resultant AMF' as the combination of the AMFs due to ozonolysis of one or both of limonene's unsaturated bonds, within the volatility basis set (VBS) organic aerosol framework. Then, β was regressed against predictors of log10([O3]/[lim]) and AER (R2 = 0.74). The β increased as the log10([O3]/[lim]) increased and as AER decreased, having the physical meaning of driving the resultant AMF to the upper AMF condition when both unsaturated bonds of limonene are ozonated. Modeling demonstrates that using the correct resultant AMF to simulate SOA formation owing to limonene ozonolysis is crucial for accurate indoor prediction.

Effects of Fatigue on Driving Safety: A Comparison of Brake Reaction Times in Night Float and Postcall Physicians in Training.

Science.gov (United States)

Talusan, Paul G; Long, Theodore; Halim, Andrea; Guliani, Laura; Carroll, Nicole; Reach, John

2014-12-01

Concerns about duty hour and resident safety have fostered discussion about postshift fatigue and driving impairment. We assessed how converting to a night float schedule for overnight coverage affected driving safety for trainees. Brake reaction times were measured for internal medicine and orthopaedic surgery resident volunteers after a traditional 28-hour call shift and after a night float shift. We conducted matched paired t tests of preshift and postshift reaction time means. Participants also completed the Epworth Sleepiness Scale pre- and postshift. From June to July 2013, we enrolled 58 interns and residents (28 orthopaedic surgery, 30 internal medicine). We included 24 (41%) trainees on night float rotations and 34 (59%) trainees on traditional 28-hour call shifts. For all residents on night float rotations, there was no significant difference pre- and postshift. An increase in reaction times was noted among trainees on 28-hour call rotations. This included no effect on reaction times for internal medicine trainees pre- and postshift, and an increase in reaction times for orthopaedic trainees. For both night float and traditional call groups, there were significant increases in the Epworth Sleepiness Scale. Trainees on traditional 28-hour call rotations had significantly worse postshift brake reaction times, whereas trainees on night float rotations had no difference. Orthopaedic trainees had significant differences in brake reaction times after a traditional call shift.

Current neurosurgical trainees' perception of the European Working Time Directive and shift work.

Science.gov (United States)

Tait, M J; Fellows, G A; Pushpananthan, S; Sergides, Y; Papadopoulos, M C; Bell, B A

2008-02-01

The introduction of the shift system in response to the European Working Time Directive has had an enormous impact on the running of neurosurgical units in the UK. This study seeks to establish what provisions are currently in place for out of hours cover and what has been the effect of the introduction of shifts in three main areas: patient safety, training and 'work/life balance'. The on-call registrar at each UK neurosurgical unit was contacted by telephone. Data regarding current emergency provision were sought. Registrars who had worked both on-calls and the shift system during their career as a neurosurgical registrar were asked to make a comparison. Data were collected from all 33 UK units. Twenty-two still use a traditional 24-h on-call system. Twenty-one on-call rotas were classed as non-resident although 12/21 of those officially on non-resident rotas were in fact resident whilst on call. Twenty-two registrars had worked both systems as a neurosurgical registrar. Twenty-one (95.45%) felt that traditional on-calls gave better clinical exposure. Twenty-one (95.45%) felt that on-calls allowed the provision of better patient care. Nineteen (86.36%) felt that on-calls were safer. Thirteen (59.09%) reported that they were more tired when doing shift work than on-calls. Fourteen (63.63%) found that the on-call system gives more useful spare time and more time to deal with family commitments. Current neurosurgery registrars feel the shift system is less safe, harmful to training and worse in terms of work/life balance. More than one-third of units are claiming to have non-resident on-call systems in order to appear compliant with EWTD when registrars are in fact resident.

[Fifty years of residency in Psychiatry at the University of Montreal: relevance and necessity of the Residents' Association].

Science.gov (United States)

Thibault, Alexis

2015-01-01

In the context of the fiftieth anniversary celebrations of the Département de psychiatrie de l'Université de Montréal, the present article offers to retrace the history of the Psychiatry Resident's Association (ARPUM). Since the Association's activities and demands reflected the concerns of the time, a depiction of the Residency Program and exploration of the historical and administrative context, in each key period, is also undertaken. Multiple psychiatrists from every decade, who were once active members of the Association, were interviewed and asked to describe the Residency Program at their time, with its positive and negative aspects, based on their own personal experience as a resident, but also as a member of the organization. The interviewees were also invited to share their recollections of the various Association's demands, representations, activities and functioning, depending on the issues and periods. Various private and public archives were also used, in order to contextualize the residents' experiences and the Association's work. A brief exploration of the historical and political context that led to the creation of the organization is explained. Training and working conditions of residents at that time are reported, enabling the understanding of the first demands when the group was born. Historical jumps are then proposed, from decades to decades, in order to depict key issues, whether they were academic, clinical or organizational, through which the Association worked, over the evolution of the Residency Program. The internal functioning and its occasional problems throughout the years are also described, as is the role in organizing social and educational events. The Residency Program is in constant mutation, and the Association has played its part in shaping the psychiatric training at the Université de Montréal. Multiple positive and tangible impacts were and are still made possible from the collaborative work between the Département de

Maternity leave: existing policies in obstetrics and gynecology residency programs.

Science.gov (United States)

Davis, J L; Baillie, S; Hodgson, C S; Vontver, L; Platt, L D

2001-12-01

To survey program directors in obstetrics and gynecology regarding maternity leave and to determine how programs are dealing with maternity leave coverage. Questionnaires regarding impact and policy on maternity leave were mailed to accredited obstetrics and gynecology residency programs. A total of 188 of 274 (69%) questionnaires were returned completed. Respectively, 80% and 69% of respondents indicated that they have a formal maternity (maximum mean 8.7 weeks) and paternity (mean 5.27 days) leave policy. Approximately 75% of programs require residents to make up time if their leave exceeds 8 weeks during the first 3 years. Eighty-five percent of programs require residents to make up time if their leave exceeds 6 weeks during the fourth year. Ninety-three percent of programs require residents to make up time if their leave exceeds 20 weeks over the 4 years. Seventy-seven percent of respondents have other residents in their program cover for the absent resident. Thirty-seven percent of programs have schedules flexible enough to allow rearrangement so that some rotations go uncovered. Eighty-three percent of programs surveyed stated that maternity leave has a somewhat to very significant impact on the residents' schedules. Most residency programs have written maternity/paternity leave policies. A more flexible curriculum may help to accommodate the residents on leave without overburdening the residents who are left to cover.

Confidence, knowledge, and skills at the beginning of residency. A survey of pathology residents.

Science.gov (United States)

Hsieh, Cindy M; Nolan, Norris J

2015-01-01

To document the pathology learning experiences of pathology residents prior to residency and to determine how confident they were in their knowledge and technical skills. An online survey was distributed to all pathology residency program directors in the United States, who were requested to forward the survey link to their residents. Data were obtained on pathology electives, grossing experience, and frozen section experience. Likert scale questions assessed confidence level in knowledge and skills. In total, 201 pathology residents responded (8% of residents in the United States). Prior to starting residency, most respondents had exposure to anatomic pathology through elective rotations. Few respondents had work-related experience. Most did not feel confident in their pathology-related knowledge or skills, and many did not understand what pathology resident duties entail. Respondents gained exposure to pathology primarily through elective rotations, and most felt the elective experience prepared them for pathology residency. However, elective time may be enhanced by providing opportunities for students to increase hands-on experience and understanding of resident duties. Copyright© by the American Society for Clinical Pathology.

E-Learning and Medical Residents, a Qualitative Perspective

Science.gov (United States)

Segerman, Jill; Crable, Elaine; Brodzinski, James

2016-01-01

Medical education helps ensure doctors acquire skills and knowledge needed to care for patients. However, resident duty hour restrictions have impacted the time residents have available for medical education, leaving resident educators searching for alternate options for effective medical education. Classroom situated e-learning, a blended…

Incorporating resident research into the dermatology residency program

Science.gov (United States)

Wagner, Richard F; Raimer, Sharon S; Kelly, Brent C

2013-01-01

Programmatic changes for the dermatology residency program at The University of Texas Medical Branch were first introduced in 2005, with the faculty goal incorporating formal dermatology research projects into the 3-year postgraduate training period. This curriculum initially developed as a recommendation for voluntary scholarly project activity by residents, but it evolved into a program requirement for all residents in 2009. Departmental support for this activity includes assignment of a faculty mentor with similar interest about the research topic, financial support from the department for needed supplies, materials, and statistical consultation with the Office of Biostatistics for study design and data analysis, a 2-week elective that provides protected time from clinical activities for the purpose of preparing research for publication and submission to a peer-reviewed medical journal, and a departmental award in recognition for the best resident scholarly project each year. Since the inception of this program, five classes have graduated a total of 16 residents. Ten residents submitted their research studies for peer review and published their scholarly projects in seven dermatology journals through the current academic year. These articles included three prospective investigations, three surveys, one article related to dermatology education, one retrospective chart review, one case series, and one article about dermatopathology. An additional article from a 2012 graduate about dermatology education has also been submitted to a journal. This new program for residents was adapted from our historically successful Dermatology Honors Research Program for medical students at The University of Texas Medical Branch. Our experience with this academic initiative to promote dermatology research by residents is outlined. It is recommended that additional residency programs should consider adopting similar research programs to enrich resident education. PMID:23901305

Incorporating resident research into the dermatology residency program.

Science.gov (United States)

Wagner, Richard F; Raimer, Sharon S; Kelly, Brent C

2013-01-01

Programmatic changes for the dermatology residency program at The University of Texas Medical Branch were first introduced in 2005, with the faculty goal incorporating formal dermatology research projects into the 3-year postgraduate training period. This curriculum initially developed as a recommendation for voluntary scholarly project activity by residents, but it evolved into a program requirement for all residents in 2009. Departmental support for this activity includes assignment of a faculty mentor with similar interest about the research topic, financial support from the department for needed supplies, materials, and statistical consultation with the Office of Biostatistics for study design and data analysis, a 2-week elective that provides protected time from clinical activities for the purpose of preparing research for publication and submission to a peer-reviewed medical journal, and a departmental award in recognition for the best resident scholarly project each year. Since the inception of this program, five classes have graduated a total of 16 residents. Ten residents submitted their research studies for peer review and published their scholarly projects in seven dermatology journals through the current academic year. These articles included three prospective investigations, three surveys, one article related to dermatology education, one retrospective chart review, one case series, and one article about dermatopathology. An additional article from a 2012 graduate about dermatology education has also been submitted to a journal. This new program for residents was adapted from our historically successful Dermatology Honors Research Program for medical students at The University of Texas Medical Branch. Our experience with this academic initiative to promote dermatology research by residents is outlined. It is recommended that additional residency programs should consider adopting similar research programs to enrich resident education.

Time Trends in Antipsychotic Drug Use in Patients with Dementia

DEFF Research Database (Denmark)

Nørgaard, Ane; Jensen-Dahm, Christina; Gasse, Christiane

2015-01-01

: To investigate time trends in use of antipsychotics and other psychotropic drugs in dementia care. METHODS: The study included longitudinal data on all Danish residents ≥65 years. The study population was defined on January 1 of each year from 2000-2012. Data included prescriptions, discharge diagnoses......, and somatic and psychiatric comorbidities. Multivariate time trend analyses of psychotropic drug use in patients with dementia within 4-year age bands were performed. RESULTS: Overall, among patients with dementia the prevalence of antipsychotic drug use decreased from 31.3% in 2000 to 20.4% in 2012...

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)

Working at the Weekend: Fathers' Time with Family in the United Kingdom.

Science.gov (United States)

Hook, Jennifer L

2012-08-01

Whereas most resident fathers are able to spend more time with their children on weekends than on weekdays, many fathers work on the weekends spending less time with their children on these days. There are conflicting findings about whether fathers are able to make up for lost weekend time on weekdays. Using unique features of the United Kingdom's National Survey of Time Use 2000 (UKTUS) I examine the impact of fathers' weekend work on the time fathers spend with their children, family, and partners (N = 595 fathers). I find that weekend work is common among fathers and is associated with less time with children, families, and partners. Fathers do not recover lost time with children on weekdays, largely because weekend work is a symptom of overwork. Findings also reveal that even if fathers had compensatory time, they are unlikely to recover lost time spent as a family or couple.

Cooperative learning as applied to resident instruction in radiology reporting.

Science.gov (United States)

Mueller, Donald; Georges, Alexandra; Vaslow, Dale

2007-12-01

The study is designed to evaluate the effectiveness of an active form of resident instruction, cooperative learning, and the residents' response to that form of instruction. The residents dictated three sets of reports both before and after instruction in radiology reporting using the cooperative learning method. The reports were evaluated for word count, Flesch-Kincaid grade level, advancement on clinical spectrum, clarity, and comparison to prior reports. The reports were evaluated for changes in performance characteristics between the pre- and postinstruction dictations. The residents' response to this form of instruction was evaluated by means of a questionnaire. The instruction was effective in changing the resident dictations. The results became shorter (Pcooperative learning activities. The least positive responses related to the amount of time devoted to the project. Sixty-three percent of respondents stated that the time devoted to the project was appropriate. Cooperative learning can be an effective tool in the setting of the radiology residency. Instructional time requirements must be strongly considered in designing a cooperative learning program.

Implementing Run-Time Evaluation of Distributed Timing Constraints in a Real-Time Environment

DEFF Research Database (Denmark)

Kristensen, C. H.; Drejer, N.

1994-01-01

In this paper we describe a solution to the problem of implementing run-time evaluation of timing constraints in distributed real-time environments......In this paper we describe a solution to the problem of implementing run-time evaluation of timing constraints in distributed real-time environments...

Space-Time Crystal and Space-Time Group.

Science.gov (United States)

Xu, Shenglong; Wu, Congjun

2018-03-02

Crystal structures and the Bloch theorem play a fundamental role in condensed matter physics. We extend the static crystal to the dynamic "space-time" crystal characterized by the general intertwined space-time periodicities in D+1 dimensions, which include both the static crystal and the Floquet crystal as special cases. A new group structure dubbed a "space-time" group is constructed to describe the discrete symmetries of a space-time crystal. Compared to space and magnetic groups, the space-time group is augmented by "time-screw" rotations and "time-glide" reflections involving fractional translations along the time direction. A complete classification of the 13 space-time groups in one-plus-one dimensions (1+1D) is performed. The Kramers-type degeneracy can arise from the glide time-reversal symmetry without the half-integer spinor structure, which constrains the winding number patterns of spectral dispersions. In 2+1D, nonsymmorphic space-time symmetries enforce spectral degeneracies, leading to protected Floquet semimetal states. We provide a general framework for further studying topological properties of the (D+1)-dimensional space-time crystal.

Night-time activity forecast by season and weather in a longitudinal design - natural light effects on three years' rest-activity cycles in nursing home residents with dementia.

Science.gov (United States)

Wahnschaffe, Amely; Nowozin, Claudia; Rath, Andreas; Floessner, Theresa; Appelhoff, Stefan; Münch, Mirjam; Kunz, Dieter

2017-12-01

Backround: Night-time agitation is a frequent symptom of dementia. It often causes nursing home admission and has been linked to circadian rhythm disturbances. A positive influence of light interventions on night-time agitation was shown in several studies. The aim of our study was to investigate whether there is a long-term association between regional weather data (as indicator for daylight availability) and 24-hour variations of motor activity. Motor activity of 20 elderly nursing home residents living with dementia was analyzed using recordings of continuously worn wrist activity monitors over a three-year period. The average recording duration was 479 ± 206 days per participant (mean ± SD). Regional cloud amount and day length data from the local weather station (latitude: 52°56'N) were included in the analysis to investigate their effects on several activity variables. Nocturnal rest, here defined as the five consecutive hours with the least motor activity during 24 hours (L5), was the most predictable activity variable per participant. There was a significant interaction of night-time activity with day length and cloud amount (F 1,1174 = 4.39; p = 0.036). Night-time activity was higher on cloudy short days than on clear short days (p = 0.007), and it was also higher on cloudy short days than on cloudy long days (p = 0.032). The need for sufficient zeitgeber (time cue) strength during winter time, especially when days are short and skies are cloudy, is crucial for elderly people living with dementia. Activity forecast by season and weather might be a valuable approach to anticipate adequately complementary use of electrical light and thereby foster lower night-time activity.

Trends in violence education in family medicine residency curricula.

Science.gov (United States)

Cronholm, Peter F; Singh, Vijay; Fogarty, Colleen T; Ambuel, Bruce

2014-09-01

Violence is a significant public health issue with far-reaching implications for the health of individuals and their communities. Our objective was to describe trends in violence-related training in family medicine residency programs since the last national survey was conducted in 1997. Surveys were sent to 337 US family medicine residency programs with the program director having active Society of Teachers of Family Medicine (STFM) membership. Measures included residency setting and characteristics, violence-related curricular content, teaching techniques and personnel, timing of content, and impact of changes in Residency Review Committee (RRC) and Accreditation Council for Graduate Medical Education (ACGME) requirements. Descriptive statistics and bivariate analyses comparing measures across time were used. A total of 201 (60%) surveys were completed. The most common violence curricula was child (83%) and elder abuse (76%), and the most common teachers of violence-related content were family physicians, psychologists, and social workers. The most common teaching methods were clinical precepting (94%), lectures (90%), case vignettes (71%), and intimate partner violence (IPV) shelter experiences (67%). ACGME and RRC changes were not reflected in self-reported measures of curricular emphasis or time. Violence curricular content and number of hours has been constant in family medicine residencies over time. An increase in the reported use of active learning strategies was identified as a trend across surveys. Next steps for violence curricula involve assessment of residents' competency to identify and intervene in violence.

Results of the 2003 Association of Residents in Radiation Oncology (ARRO) surveys of residents and chief residents in the United States

International Nuclear Information System (INIS)

Jagsi, Reshma; Buck, David A.; Singh, Anurag K.; Engleman, Mark; Thakkar, Vipul; Frank, Steven J.; Flynn, Daniel

2005-01-01

Purpose: To document demographic characteristics of current residents, career motivations and aspirations, and training program policies and resources. Methods: In 2003, the Association of Residents in Radiation Oncology (ARRO) conducted two nationwide surveys: one of all U.S. radiation oncology residents and one of chief residents. Results: The Chief Residents' Survey was completed by representatives from all 77 programs (response rate, 100%). The Residents' Survey was returned by 229 respondents (response rate, 44%). In each, 32% of respondents were female. The most popular career after residency was private practice (46%), followed by permanent academic practice (28%). Changes that would entice those choosing private practice to consider an academic career included more research experience as a resident (76%), higher likelihood of tenure (69%), lesser time commitment (66%), and higher salary (54%). Although the majority of respondents were satisfied with educational experience overall, a number of programs were reported to provide fewer resources than required. Conclusions: Median program resources and numbers of outliers are documented to allow residents and program directors to assess the relative adequacy of experience in their own programs. Policy-making bodies and individual programs should consider these results when developing interventions to improve educational experiences of residents and to increase retention of radiation oncologists in academic practice

Time poverty in Brazil: measurement and analysis of its determinants

Directory of Open Access Journals (Sweden)

Lilian Lopes Ribeiro

2012-06-01

Full Text Available This article analyzes well-being on an individual level, through the allocation of work hours done by adults and children and thus it measures time poverty in Brazil. In order to achieve such measurement, poverty indicators such as Foster, Greer and Thorbecke (FGT were adapted into a time poverty mode. Additionally, an analysis of its determinants was also conducted. Among other findings, the fact that women (either children and adult ones are the time-poorest individuals in urban or rural areas. Another unfortunate finding is that the high rate of time poverty among children, numerically 16,1% is not far from the adult rate which is of 19,7%. The overall composite time poor individual profile is of an African-Brazilian adult woman of little education, not necessarily income poor and residing in an urban area of the northeast region, living in a household of few people, she is the mother of children who are younger than 14 years old.

A Quantile Regression Approach to Estimating the Distribution of Anesthetic Procedure Time during Induction.

Directory of Open Access Journals (Sweden)

Hsin-Lun Wu

Full Text Available Although procedure time analyses are important for operating room management, it is not easy to extract useful information from clinical procedure time data. A novel approach was proposed to analyze procedure time during anesthetic induction. A two-step regression analysis was performed to explore influential factors of anesthetic induction time (AIT. Linear regression with stepwise model selection was used to select significant correlates of AIT and then quantile regression was employed to illustrate the dynamic relationships between AIT and selected variables at distinct quantiles. A total of 1,060 patients were analyzed. The first and second-year residents (R1-R2 required longer AIT than the third and fourth-year residents and attending anesthesiologists (p = 0.006. Factors prolonging AIT included American Society of Anesthesiologist physical status ≧ III, arterial, central venous and epidural catheterization, and use of bronchoscopy. Presence of surgeon before induction would decrease AIT (p < 0.001. Types of surgery also had significant influence on AIT. Quantile regression satisfactorily estimated extra time needed to complete induction for each influential factor at distinct quantiles. Our analysis on AIT demonstrated the benefit of quantile regression analysis to provide more comprehensive view of the relationships between procedure time and related factors. This novel two-step regression approach has potential applications to procedure time analysis in operating room management.

Visas for Switzerland and France - Time needed to process applications

CERN Multimedia

2012-01-01

Please note that any person required to be in possession of a visa in order to take up functions at CERN must start the application process sufficiently early to allow the visa to be issued in time.   The submission of an incomplete application, local circumstances and an increase in applications before the summer holiday period can all result in considerable variation in the time needed to process your application and issue the visa. You are therefore recommended to submit your visa application at least three months, and not later than 21 days, prior to your departure date. We would also like to remind you that the Swiss Consulate in Paris and the French Consulate in Geneva can issue visas exclusively to people resident within their respective spheres of competence (i.e. those who are holders of a French or Swiss residence permit respectively). You must therefore obtain all visas required for stays longer than three months in France or Switzerland from the visa-issuing authority competent for ...

Praise for borders: philosophy and literature for our times

Directory of Open Access Journals (Sweden)

Francisco José Chaguaceda Alonso

2017-09-01

Full Text Available Philosophic thought has always been knowledge in doubt, questioned about its usefulness. This permanent weakness has accentuated itself in our time. Now, is it true that philosophy lack sense or usefulness in our modern world? Nothing is further from reality, as this article attempts to argue. Philosophy is knowledge for our times as a time of reckoning and closed identities. It is knowledge of frontier and migrant for meeting and understanding the other, for dialogue and listening. That is its value, but along its journey of knowledge and comprehension it needs literature. In the very frontier between philosophy and literature resides its meaning. Maybe thought conducted in Spanish is an example of this. In short, is there more usefulness for knowledge than to be an instrument for meeting and understanding of others? How can philosophy be knowledge of these characteristics?

Time Here, Time There, Time Everywhere: Teaching Young Children Time through Daily Routine

Science.gov (United States)

Lee, Joohi; Lee, Joo Ok; Fox, Jill

2009-01-01

According to Piaget, 5- or 6-year-old children gradually acquire the concept of time based on events (Piaget, 1969). In his experiment of investigating children's time concepts, Piaget found that children of these ages were able to place pictures based on sequential events with some errors; the younger children made more errors. The National…

Thermal discharge residence by Lake Michigan Salmonids

International Nuclear Information System (INIS)

Romberg, G.P.; Prepejchal, W.

1975-01-01

Lake Michigan salmon and trout were tagged with a thermoluminescent dosimeter (TLD) temperature tag to estimate their thermal exposure and residence time at a warm water discharge. Fish were collected, tagged, and released at the Point Beach Nuclear Plant, Two Rivers, Wisconsin, in the fall of 1973 and 1974. Tags were recovered during the same season, primarily from fish recaptured at Point Beach. Average uniform temperature exposure and maximum possible discharge residence time were determined. Appropriate hourly intake and discharge temperatures were averaged to calculate mean temperature exposure for the case of maximum discharge residence. Lowest discharge temperature not included within the period of maximum residence was identified to serve as a possible indicator of avoidance temperature. Mean values for the above parameters were calculated for fish species for each tagging year and are reported with the accompanying range of intake and discharge temperatures

Psychiatric Emergency Services - Can Duty-Hour Changes Help Residents and Patients?

Science.gov (United States)

Brainch, Navjot; Schule, Patrick; Laurel, Faith; Bodic, Maria; Jacob, Theresa

2018-04-14

Limitations on resident duty hours have been widely introduced with the intention of decreasing resident fatigue and improving patient outcomes. While there is evidence of improvement in resident well-being and education following such initiatives, they have inadvertently resulted in increased number of hand-offs between clinicians leading to potential errors in patient care. Current literature emphasizes need for more specialty/setting-specific scheduling, while considering residents' opinions when implementing duty-hour reforms. There are no reports examining the impact of duty-hour changes on residents or patients in psychiatric emergency service (PES) settings. Our purpose was to assess the impact of a recent scheduling change and decrease in overall duty hours, on resident well-being and sense of burnout, while also evaluating changes to patient wait-time and length of stay (LOS) in PES. Residents completed Maslach Burnout Inventory and anonymous surveys focusing on: fatigue, sleep, life outside work for shifts - regular (8 am-8 pm) and swing shifts (12 pm-10 pm). Data from the electronic medical records were collected for 6 months pre- and post-schedule change (January 2016-February 2017), for LOS and patient wait-time. Residents' preference for shifts was split. However, 86% reported getting enough sleep during swing shifts, while 83% reported lack of sleep during regular shifts. The average patient wait-time and LOS significantly decreased from 169 to 147 and 690 to 515 min, respectively. The change to swing shifts significantly impacts LOS and patient wait-time. The short shifts demonstrated an improvement in well-being for residents, but were not the singular factor for overall resident satisfaction.

The State of Communication Education in Family Medicine Residencies.

Science.gov (United States)

Jansen, Kate L; Rosenbaum, Marcy E

2016-06-01

Communication skills are essential to medical training and have lasting effects on patient satisfaction and adherence rates. However, relatively little is reported in the literature identifying how communication is taught in the context of residency education. Our goal was to determine current practices in communication curricula across family medicine residency programs. Behavioral scientists and program directors in US family medicine residencies were surveyed via email and professional organization listservs. Questions included whether programs use a standardized communication model, methods used for teaching communication, hours devoted to teaching communication, as well as strengths and areas for improvement in their program. Analysis identified response frequencies and ranges complemented by analysis of narrative comments. A total of 204 programs out of 458 family medicine residency training sites responded (45%), with 48 out of 50 US states represented. The majority of respondents were behavioral scientists. Seventy-five percent of programs identified using a standard communication model; Mauksch's patient-centered observation model (34%) was most often used. Training programs generally dedicated more time to experiential teaching methods (video review, work with simulated patients, role plays, small groups, and direct observation of patient encounters) than to lectures (62% of time and 24% of time, respectively). The amount of time dedicated to communication education varied across programs (average of 25 hours per year). Respondent comments suggest that time dedicated to communication education and having a formal curriculum in place are most valued by educators. This study provides a picture of how communication skills teaching is conducted in US family medicine residency programs. These findings can provide a comparative reference and rationale for residency programs seeking to evaluate their current approaches to communication skills teaching and

Career goals and expectations of men and women pharmacy residents.

Science.gov (United States)

King, C M; Oliver, E J; Jeffrey, L P

1982-11-01

Personal and professional characteristics of men and women hospital pharmacy residents were studied to identify differences that could affect future hospital pharmacy practice. Residents in 111 ASHP-accredited pharmacy residency programs received a survey containing questions on demographic information, reasons for selecting a residency, areas of professional interest, postresidency career goals, responsibilities to home and family, and advantages and disadvantages associated with gender. Of 286 residents receiving questionnaires, 226 responded; the percentages of men and women responding corresponded to the ratio of men and women in hospital pharmacy residencies. While men and women expressed educational goals that were not significantly different, more men than women had earned or were in the process of earning advanced degrees. No significant differences were evident between men's and women's plans for marriage and children, but 73% of the women indicated that they would take time out from their practice to raise children, compared with only 9% of the men. The majority of residents did not think their gender affected them in their residency programs, but in professional interactions more men saw gender as an advantage and more women as a disadvantage. Significantly more than women aspired to be hospital pharmacy directors. The results suggest that men are obtaining advanced training closer to the time they graduate from pharmacy school and that in the future women competing for promotions may be older than men competing for comparable positions. Those planning pharmacy staffing should consider the needs of women, and men, who expect to take time out from their careers for family responsibilities and possibly seek part-time positions when they return to the work force.

Career Interests of Canadian Psychiatry Residents: What Makes Residents Choose a Research Career?

Science.gov (United States)

Laliberté, Vincent; Rapoport, Mark J.; Andrew, Melissa; Davidson, Marla

2016-01-01

Objectives: Training future clinician-researchers remains a challenge faced by Canadian psychiatry departments. Our objectives were to determine the prevalence of residents interested in pursuing research and other career options as part of their practice, and to identify the factors associated with interest in research. Method: Data from a national online survey of 207 Canadian psychiatry residents from a total of 853 (24.3% response rate) were examined. The main outcome was interest in research as part of residents’ future psychiatrist practice. Bivariate and multivariate analyses were performed to identify demographic and vocational variables associated with research interest. Results: Interest in research decreases by 76% between the first and fifth year of psychiatry residency (OR 0.76 per year, 95% CI 0.60 to 0.97). Training in a department with a residency research track did not correlate with increased research interest (χ2 = 0.007, df = 1, P = 0.93). Conclusions: Exposing and engaging psychiatry residents in research as early as possible in residency training appears key to promoting future research interest. Psychiatry residency programs and research tracks could consider emphasizing research training initiatives and protected research time early in residency. PMID:27253699

Short-time home coming project in evacuation zone

International Nuclear Information System (INIS)

Tatsuzaki, Hideo

2011-01-01

Accident at Fukushima Daiichi Nuclear Power Plants (NPPs) forced neighboring residents to evacuate, and evacuation zone (20 km radius from NPPs) was defined as highly contaminated and designated as no-entry zones. Residents had been obliged to live a refugee life for a longer period than expected. Short-time home coming project was initiated according to their requests. They came to the meeting place called transfer place (20 - 30 km radius from NPPs), wore protective clothing and personal dosimeter with having drinking water and came home in evacuation zone with staffs by bus. Their healthcare management professionals were fully prepared for emergency. After collecting necessary articles at home within two hours, they returned to the meeting place by bus for screening and dressing, and went back to refuge house. If screening data were greater than 13 kcpm using GM counters, partial body decontamination had been conducted by wiping and if greater than 100 kcpm, whole body decontamination was requested but not conducted. Dose rate of residents and staffs was controlled less than 1 mSv, which was alarm level of personal dosimeter. Stable iodine was prepared but actually not used. (T. Tanaka)

Time flies faster under time pressure.

Science.gov (United States)

Rattat, Anne-Claire; Matha, Pauline; Cegarra, Julien

2018-04-01

We examined the effects of time pressure on duration estimation in a verbal estimation task and a production task. In both temporal tasks, participants had to solve mazes in two conditions of time pressure (with or without), and with three different target durations (30 s, 60 s, and 90 s). In each trial of the verbal estimation task, participants had to estimate in conventional time units (minutes and seconds) the amount of time that had elapsed since they started to solve the maze. In the production task, they had to press a key while solving the maze when they thought that the trial's duration had reached a target value. Results showed that in both tasks, durations were judged longer with time pressure than without it. However, this temporal overestimation under time pressure did not increase with the length of the target duration. These results are discussed within the framework of scalar expectancy theory. Copyright © 2018 Elsevier B.V. All rights reserved.

Using skype as an alternative for residency selection interviews.

Science.gov (United States)

Edje, Louito; Miller, Christine; Kiefer, Jacklyn; Oram, David

2013-09-01

Residency interviews can place significant time and financial burdens on applicants. To determine whether the use of Skype as a screening tool during interview season in a family medicine residency is cost-effective and time-efficient for the applicant and the residency program. We surveyed 2 groups of medical students during interviews for our family medicine program. Thirty-two students were interviewed via our face-to-face, traditional interview (TI) process, and 10 students, the second group, who did not meet the program's standard interview selection criteria for TI, underwent our Skype interview (SI) process. Using an unpaired t test, we found that the applicants' costs of an SI were significantly less than a TI, $566 (95% confidence interval [CI] $784-$349, P Skype may be a cost-effective and time-efficient screening tool for both the applicant and the program. Alternate uses of SI may include the time-sensitive, postmatch Supplemental Offer and Acceptance Program.

The costs and quality of operative training for residents in tympanoplasty type I.

Science.gov (United States)

Wang, Mao-Che; Yu, Eric Chen-Hua; Shiao, An-Suey; Liao, Wen-Huei; Liu, Chia-Yu

2009-05-01

A teaching hospital would incur more operation room costs on training surgical residents. To evaluate the increased operation time and the increased operation room costs of operations performed by surgical residents. As a model we used a very common surgical otology procedure -- tympanoplasty type I. From January 1, 2004 to December 31, 2004, we included in this study 100 patients who received tympanoplasty type I in Taipei Veterans General Hospital. Fifty-six procedures were performed by a single board-certified surgeon and 44 procedures were performed by residents. We analyzed the operation time and surgical outcomes in these two groups of patients. The operation room cost per minute was obtained by dividing the total operation room expenses by total operation time in the year 2004. The average operation time of residents was 116.47 min, which was significantly longer (pcost USD $40.36 more for each operation performed by residents in terms of operation room costs. The surgical success rate of residents was 81.82%, which was significantly lower (p=0.016) than that of the board-certified surgeon (96.43%).

Pediatric dermatology training during residency: a survey of the 2014 graduating residents.

Science.gov (United States)

Akhavan, Alaleh; Murphy-Chutorian, Blair; Friedman, Adam

2015-01-01

Knowledge of pediatric dermatology is considered a core competency of dermatology training and should be expected of all practicing dermatologists. While the numbers of both pediatric dermatology fellowships and board certified pediatric dermatologists in the workforce have increased over the years, recent reports suggest that there is a gap in pediatric dermatology education during dermatology residency. The goal of this study is to assess the current state of pediatric education during residency, as well as the clinical experience, satisfaction and expectations of graduating dermatology residents. A 31-question self-report survey was distributed electronically to 294 third-year dermatology residents with questions pertaining to demographics, didactic education, resident experience in pediatric dermatology training, satisfaction with pediatric training and future plans. One hundred and twenty-three residents responded (41.8% response rate) representing approximately 29.1% of the total number of graduating residents. 69 (56.1%) residents reported academic time specifically devoted to pediatric dermatology, the majority (79.7%) of which was led by pediatric dermatologists. 82% of residents reported dedicated pediatric dermatology clinics at their program. 86.8% of respondents felt that their training in pediatric dermatology will allow them to confidently see pediatric dermatology patients in practice. This survey highlights a promising state of pediatric dermatology training among current graduating dermatology residents. The majority of current graduating dermatology residents are satisfied with their pediatric dermatology education, feel confident treating pediatric patients, and plan to see pediatric patients in clinical practice. © 2015 Wiley Periodicals, Inc.

Gap timing and the spectral timing model.

Science.gov (United States)

Hopson, J W

1999-04-01

A hypothesized mechanism underlying gap timing was implemented in the Spectral Timing Model [Grossberg, S., Schmajuk, N., 1989. Neural dynamics of adaptive timing and temporal discrimination during associative learning. Neural Netw. 2, 79-102] , a neural network timing model. The activation of the network nodes was made to decay in the absence of the timed signal, causing the model to shift its peak response time in a fashion similar to that shown in animal subjects. The model was then able to accurately simulate a parametric study of gap timing [Cabeza de Vaca, S., Brown, B., Hemmes, N., 1994. Internal clock and memory processes in aminal timing. J. Exp. Psychol.: Anim. Behav. Process. 20 (2), 184-198]. The addition of a memory decay process appears to produce the correct pattern of results in both Scalar Expectancy Theory models and in the Spectral Timing Model, and the fact that the same process should be effective in two such disparate models argues strongly that process reflects a true aspect of animal cognition.

Dedicated clock/timing-circuit theories of time perception and timed performance.