WorldWideScience

Sample records for waiting time distribution

  1. Waiting time distribution in M/D/1 queueing systems

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk; Staalhagen, Lars

    1999-01-01

    The well-known formula for the waiting time distribution of M/D/1 queueing systems is numerically unsuitable when the load is close to 1.0 and/or the results for a large waiting time are required. An algorithm for any load and waiting time is presented, based on the state probabilities of M/D/1...

  2. Waiting time distribution revealing the internal spin dynamics in a double quantum dot

    Science.gov (United States)

    Ptaszyński, Krzysztof

    2017-07-01

    Waiting time distribution and the zero-frequency full counting statistics of unidirectional electron transport through a double quantum dot molecule attached to spin-polarized leads are analyzed using the quantum master equation. The waiting time distribution exhibits a nontrivial dependence on the value of the exchange coupling between the dots and the gradient of the applied magnetic field, which reveals the oscillations between the spin states of the molecule. The zero-frequency full counting statistics, on the other hand, is independent of the aforementioned quantities, thus giving no insight into the internal dynamics. The fact that the waiting time distribution and the zero-frequency full counting statistics give a nonequivalent information is associated with two factors. Firstly, it can be explained by the sensitivity to different timescales of the dynamics of the system. Secondly, it is associated with the presence of the correlation between subsequent waiting times, which makes the renewal theory, relating the full counting statistics and the waiting time distribution, no longer applicable. The study highlights the particular usefulness of the waiting time distribution for the analysis of the internal dynamics of mesoscopic systems.

  3. The waiting time distribution as a graphical approach to epidemiologic measures of drug utilization

    DEFF Research Database (Denmark)

    Hallas, J; Gaist, D; Bjerrum, L

    1997-01-01

    The emergence of large, computerized pharmacoepidemiologic databases has enabled us to study drug utilization with the individual user as the statistical unit. A recurrent problem in such analyses, however, is the overwhelming volume and complexity of data. We here describe a graphical approach...... that effectively conveys some essential utilization parameters for a drug. The waiting time distribution for a group of drug users is a charting of their first prescription presentations within a specified time window. For a drug used for chronic treatment, most current users will be captured at the beginning...... of the window. After a few months, the graph will be dominated by new, incident users. As examples, we present waiting time distributions for insulin, ulcer drugs, systemic corticosteroids, antidepressants, and disulfiram. Appropriately analyzed and interpreted, the waiting time distributions can provide...

  4. Determining prescription durations based on the parametric waiting time distribution

    DEFF Research Database (Denmark)

    Støvring, Henrik; Pottegård, Anton; Hallas, Jesper

    2016-01-01

    in continued treatment. We exploited this to estimate percentiles of the IAD by inversion of the estimated FRD and defined the duration of a prescription as the time within which 80% of current users will have presented themselves again. Statistical properties were examined in simulation studies...

  5. Waiting-time distributions of magnetic discontinuities: clustering or Poisson process?

    Science.gov (United States)

    Greco, A; Matthaeus, W H; Servidio, S; Dmitruk, P

    2009-10-01

    Using solar wind data from the Advanced Composition Explorer spacecraft, with the support of Hall magnetohydrodynamic simulations, the waiting-time distributions of magnetic discontinuities have been analyzed. A possible phenomenon of clusterization of these discontinuities is studied in detail. We perform a local Poisson's analysis in order to establish if these intermittent events are randomly distributed or not. Possible implications about the nature of solar wind discontinuities are discussed.

  6. Identification of waiting time distribution of M/G/1, Mx/G/1, GIr/M/1 queueing systems

    Directory of Open Access Journals (Sweden)

    A. Ghosal

    1988-01-01

    Full Text Available This paper brings out relations among the moments of various orders of the waiting time of the 1st customer and a randomly selected customer of an arrival group for bulk arrivals queueing models, and as well as moments of the waiting time (in queue for M/G/1 queueing system. A numerical study of these relations has been developed in order to find the (β1,β2 measures of waiting time distribution in a comutable form. On the basis of these measures one can look into the nature of waiting time distribution of bulk arrival queues and the single server M/G/1 queue.

  7. Queues with waiting time dependent service

    DEFF Research Database (Denmark)

    Bekker, R.; Koole, G. M.; Nielsen, Bo Friis

    2011-01-01

    Motivated by service levels in terms of the waiting-time distribution seen, for instance, in call centers, we consider two models for systems with a service discipline that depends on the waiting time. The first model deals with a single server that continuously adapts its service rate based...... on the waiting time of the first customer in line. In the second model, one queue is served by a primary server which is supplemented by a secondary server when the waiting of the first customer in line exceeds a threshold. Using level crossings for the waiting-time process of the first customer in line, we...... derive steady-state waiting-time distributions for both models. The results are illustrated with numerical examples....

  8. Arrival time pattern and waiting time distribution of patients in the emergency outpatient department of a tertiary level health care institution of North India

    Directory of Open Access Journals (Sweden)

    Yogesh Tiwari

    2014-01-01

    Full Text Available Background: Emergency Department (ED of tertiary health care institute in India is mostly overcrowded, over utilized and inappropriately staffed. The challenges of overcrowded EDs and ill-managed patient flow and admission processes result in excessively long waits for patients. Aim: The objective of the present study was to analyze the patient flow system by assessing the arrival and waiting time distribution of patients in an Emergency out Patient Department (EOPD. Materials and Methods: This short cross-sectional descriptive study was conducted in the EOPD of a Tertiary level health care Institution in North India in the month of May, 2011. The data was obtained from 591 patients, who were present in the EOPD during the month of May, 2011. The waiting time, inter arrival time between two consecutive patients were calculated in addition to the daily census data (discharge rate, admission rate and transfer out rates etc. of the emergency. Results: Arrival time pattern of patients in the EOPD was highly stochastic with the peak arrival hours to be "9.00-12.00 h" in which around 26.3% patients arrived in the EOPD. The primary waiting areas of patients included patients "under observation" (29.6%; "waiting for routine diagnostic tests" (16.4% and "waiting for discharge" (14.6%. Around 71% patients were waiting due to reasons within emergency complex. Conclusion: The patient flow of the ED could only be addressed by multifaceted, multidisciplinary and hospital wide approach.

  9. Organ Type and Waiting Time

    Science.gov (United States)

    ... Your Child Adjust Camps Resources LIVING DONATION Facts Types Being a Living Donor About the Operation Financing Living Donation Home / Before The Transplant / About Organ Allocation / Organ Type & Waiting Time Organ Facts Heart ...

  10. 46 CFR 9.10 - Waiting time.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Waiting time. 9.10 Section 9.10 Shipping COAST GUARD... § 9.10 Waiting time. The same construction should be given the act when charging for waiting time as... for duty the waiting time amounts to at least one hour. ...

  11. Third degree waiting time discrimination: optimal allocation of a public sector healthcare treatment under rationing by waiting.

    Science.gov (United States)

    Gravelle, Hugh; Siciliani, Luigi

    2009-08-01

    In many public healthcare systems treatments are rationed by waiting time. We examine the optimal allocation of a fixed supply of a given treatment between different groups of patients. Even in the absence of any distributional aims, welfare is increased by third degree waiting time discrimination: setting different waiting times for different groups waiting for the same treatment. Because waiting time imposes dead weight losses on patients, lower waiting times should be offered to groups with higher marginal waiting time costs and with less elastic demand for the treatment.

  12. The Behavior of the Renewal Sequence in Case the Tail of the Waiting-Time Distribution Is Regularly Varying with Index -1

    NARCIS (Netherlands)

    J.B.G. Frenk (Hans)

    1982-01-01

    textabstractA second-order asymptotic result for the probability of occurrence of a persistent and aperiodic recurrent event is given if the tail of the distribution of the waiting time for this event is regularly varying with index -1.

  13. Mrs. Manumbu's wait: a case for reducing client waiting time.

    Science.gov (United States)

    1992-01-01

    Management Sciences for Health has published a case study on reducing client waiting time, case discussion questions, and a case analysis for training and group discussion for family planning (FP) managers. A married mother of 3 children carries her 5-week-old son as she walks for 1 hour on a hot day to a FP clinic. She wants to learn how to prevent another birth too soon. After registering, she joins at least 35 other women and children under a tree. She sits next to a good friend who has been waiting for 2 hours. They listen to another woman who tells about waiting for 3 hours only to be told she needed to return the following day because too many people wanted to visit the physician. The woman adds that she just wanted a new supply of oral contraceptives. The long walk to the clinic was not the problem, leaving her children alone by themselves was the problem. The new client begins to be concerned about waiting for 3 hours while her children are also home alone; plus, she had chores to do. The case discussion questions ask participants how the waiting time can discourage the new client from using FP, what the clinic can do to ameliorate the situation, and what programs and policies can reduce long client waits. Some solutions to improving the waiting situation include providing transportation, appointments, and fast routes for resupplying contraceptives as well as analyzing client flow and implementing the findings. Mid- and senior-level managers could begin a community-based service delivery program in villages, support a triage policy, and implement higher level training for nurses to perform more medical functions.

  14. Consumer Perception and Evaluation of Waiting Time

    NARCIS (Netherlands)

    G. Antonides (Gerrit); P.C. Verhoef (Peter)

    2000-01-01

    textabstractTelephone waiting times for a commercial service were varied in two different experiments. In the first experiment, the telephone rate was either zero or fixed at Dfl.1.- (approx. $0.40) per minute. Consumer perceptions of waiting times could be described best by a psychophysical power

  15. Improving Patient Satisfaction with Waiting Time

    Science.gov (United States)

    Eilers, Gayleen M.

    2004-01-01

    Waiting times are a significant component of patient satisfaction. A patient satisfaction survey performed in the author's health center showed that students rated waiting time lowest of the listed categories--A ratings of 58% overall, 63% for scheduled appointments, and 41% for the walk-in clinic. The center used a quality improvement process and…

  16. Revisiting Waiting Times in DNA evolution

    CERN Document Server

    Nicodeme, Pierre

    2012-01-01

    Transcription factors are short stretches of DNA (or $k$-mers) mainly located in promoters sequences that enhance or repress gene expression. With respect to an initial distribution of letters on the DNA alphabet, Behrens and Vingron consider a random sequence of length $n$ that does not contain a given $k$-mer or word of size $k$. Under an evolution model of the DNA, they compute the probability $\\mathfrak{p}_n$ that this $k$-mer appears after a unit time of 20 years. They prove that the waiting time for the first apparition of the $k$-mer is well approximated by $T_n=1/\\mathfrak{p}_n$. Their work relies on the simplifying assumption that the $k$-mer is not self-overlapping. They observe in particular that the waiting time is mostly driven by the initial distribution of letters. Behrens et al. use an approach by automata that relaxes the assumption related to words overlaps. Their numerical evaluations confirms the validity of Behrens and Vingron approach for non self-overlapping words, but provides up to 44...

  17. Waiting time care guarantees: necessity or nemesis?

    Science.gov (United States)

    Joshi, N P; Noseworthy, F T; Noseworthy, T W

    2006-01-01

    One of the priorities of governments in Canada is to reduce long waiting times for health services. This has raised the prospect of introducing waiting time care guarantees. Such guarantees affirm the healthcare system's social contract with the public and provide an entitlement to Canadians to receive timely care. There are clinical, legal and political implications, which must be considered and well managed before introduction. Other countries have ventured down this path. They teach us that waiting time care guarantees are good policy and make good sense. Correspondingly, they remind us not to make a promise we are not ready to keep.

  18. Enhancing outpatient clinics management software by reducing patients' waiting time.

    Science.gov (United States)

    Almomani, Iman; AlSarheed, Ahlam

    The Kingdom of Saudi Arabia (KSA) gives great attention to improving the quality of services provided by health care sectors including outpatient clinics. One of the main drawbacks in outpatient clinics is long waiting time for patients-which affects the level of patient satisfaction and the quality of services. This article addresses this problem by studying the Outpatient Management Software (OMS) and proposing solutions to reduce waiting times. Many hospitals around the world apply solutions to overcome the problem of long waiting times in outpatient clinics such as hospitals in the USA, China, Sri Lanka, and Taiwan. These clinics have succeeded in reducing wait times by 15%, 78%, 60% and 50%, respectively. Such solutions depend mainly on adding more human resources or changing some business or management policies. The solutions presented in this article reduce waiting times by enhancing the software used to manage outpatient clinics services. Both quantitative and qualitative methods have been used to understand current OMS and examine level of patient's satisfaction. Five main problems that may cause high or unmeasured waiting time have been identified: appointment type, ticket numbering, doctor late arrival, early arriving patient and patients' distribution list. These problems have been mapped to the corresponding OMS components. Solutions to the above problems have been introduced and evaluated analytically or by simulation experiments. Evaluation of the results shows a reduction in patient waiting time. When late doctor arrival issues are solved, this can reduce the clinic service time by up to 20%. However, solutions for early arriving patients reduces 53.3% of vital time, 20% of the clinic time and overall 30.3% of the total waiting time. Finally, well patient-distribution lists make improvements by 54.2%. Improvements introduced to the patients' waiting time will consequently affect patients' satisfaction and improve the quality of health care services

  19. Waiting times for radiation therapy in Ontario.

    Science.gov (United States)

    Benk, Veronique; Przybysz, Raymond; McGowan, Tom; Paszat, Lawrence

    2006-02-01

    The mass media and clinical journals have reported lengthy waiting times after surgery before initiation of radiation therapy (RT) for cancer across Canada. We aimed to describe the length of time between the last date of surgery or biopsy or chemotherapy and first date of RT. This is a population-based study measuring waiting times for RT in Ontario among all patients with potentially curable cancer of the cervix, tonsil and larynx and a random sample of women who had had breast cancer resection, whose first date of RT fell between Sept. 1, 2001, and Aug. 31, 2002. Abstraction of original health care records provided each patient's demographics, cancer stage and cancer treatment (last surgery, consultation, simulation, first RT). Last dates of chemotherapy before RT were obtained from abstraction or from Ontario Health Insurance Plan (OHIP) files, and last dates of surgery before RT were compared with dates in the Canadian Institute for Health Information (CIHI) Discharge Abstract Database. Waiting times between the last date of surgery or chemotherapy and the first date of RT varied significantly among the health regions of Ontario. Increasing age, but not the presence of comorbidity, was associated with longer waiting times. Women who did not receive postoperative chemotherapy before RT for breast cancer waited significantly longer than all others. Measurement of waiting times for cancer RT must discount time during which adjuvant intravenous chemotherapy is administered after surgery and before RT. There appears to be a formal or informal process by which those at highest risk begin RT most rapidly.

  20. WAITING TIME IN THE WAITING ROOM IN FAMILY PRACTICE AND PATIENT SATISFACTION

    Directory of Open Access Journals (Sweden)

    Janko Kersnik

    2001-05-01

    Full Text Available Background: Appointment system shortens the waiting time in the waiting room for the patient and allows better use of time for the doctor. We wanted to examine how long patients are willing to wait in the waiting room, how long they waited at the last visit, patient satisfaction with the last visit, the satisfaction with the length of waiting in the past 12 months and the overall patient satisfaction score for the last 12 months. Appointment system proved to be effective means of organising practice time. Waiting time in the waiting room with appointment system was considerably shorter (mean 18.5 minutes as compared to the waiting time in the practices without appointment system (mean 55.4 minutes, the fact which is reflected also in higher satisfaction with waiting in the waiting room in the past 12 months. Three quarters of patients in practices with appointment system waited standard 20 minutes or less, as opposed to the other practices where only one quarter of patients waited 20 minutes or less.Conclusions: The overall satisfaction with the doctor with the appointment system does not differ in both types of practices. The patients from practices with appointment system evaluated better possibility to get an appointment to suit the patients, but worse help of the doctors’ staff, possibility to get through to the office by phone, the length of time during the consultation and the doctors’ thoroughness.

  1. Time to wait: a systematic review of strategies that affect out-patient waiting times.

    Science.gov (United States)

    Naiker, Ugenthiri; FitzGerald, Gerry; Dulhunty, Joel M; Rosemann, Michael

    2017-03-30

    Objective Out-patient waiting times pose a significant challenge for public patients in need of specialist evaluation and intervention. The aim of the present study was to identify and categorise effective strategies to reduce waiting times for specialist out-patient services with a focus on the Australian healthcare system.Methods A systematic review of major health databases was conducted using the key terms 'outpatient*' AND 'waiting time', 'process*' AND 'improvement in outpatient clinics'. Identified articles were assessed for their relevance by sequential review of the title, abstract and full text. References of the selected manuscripts were scanned for additional relevant articles. Selected articles were evaluated for consistent and emerging themes.Results In all, 152 articles were screened, of which 38 were included in the present review. Numerous strategies identified in the articles were consolidated into 26 consistent approaches. Three overarching themes were identified as significantly affecting waiting times: resource realignment, operational efficiency and process improvement.Conclusions Strategies to align resources, increase operational efficiency and improve processes provide a comprehensive approach that may reduce out-patient waiting times.What is known about the topic? Out-patient waiting times are a challenge in most countries that seek to provide universal access to health care for all citizens. Although there has been extensive research in this area, many patients still experience extensive delays accessing specialist care, particularly in the public health sector. The multiple factors that contribute to bottlenecks and inefficiencies in the referral process and affect patient waiting times are often poorly understood.What does this paper add? This paper reviews the published healthcare literature to identify strategies that affect specialist out-patient waiting times for patients. The findings suggest that there are numerous operational

  2. Time while waiting: patients' experiences of scheduled surgery.

    Science.gov (United States)

    Carr, Tracey; Teucher, Ulrich C; Casson, Alan G

    2014-12-01

    Research on patients' experiences of wait time for scheduled surgery has centered predominantly on the relative tolerability of perceived wait time and impacts on quality of life. We explored patients' experiences of time while waiting for three types of surgery with varied wait times--hip or knee replacement, shoulder surgery, and cardiac surgery. Thirty-two patients were recruited by their surgeons. We asked participants about their perceptions of time while waiting in two separate interviews. Using interpretative phenomenological analysis (IPA), we discovered connections between participant suffering, meaningfulness of time, and agency over the waiting period and the lived duration of time experience. Our findings reveal that chronological duration is not necessarily the most relevant consideration in determining the quality of waiting experience. Those findings helped us create a conceptual framework for lived wait time. We suggest that clinicians and policy makers consider the complexity of wait time experience to enhance preoperative patient care. © The Author(s) 2014.

  3. Determinants of Patient Waiting Time in the General Outpatient ...

    African Journals Online (AJOL)

    satisfied with the care received is strongly related to the quality ... clinic wait.[1] Failure to incorporate consumer‑driven features into the design of wait experience could lead to patient and provider dissatisfaction. Waiting time ... respondents waited for 90‑180 min in the clinic, whereas 36.1% (35/96) of the patients spent.

  4. An accelerated failure time model for investigating pedestrian crossing behavior and waiting times at signalized intersections.

    Science.gov (United States)

    Yang, Xiaobao; Abdel-Aty, Mohamed; Huan, Mei; Peng, Yichuan; Gao, Ziyou

    2015-09-01

    The waiting process is crucial to pedestrians in the street-crossing behavior. Once pedestrians terminate their waiting behavior during the red light period, they would cross against the red light and put themselves in danger. A joint hazard-based duration model is developed to investigate the effect of various covariates on pedestrian crossing behavior and to estimate pedestrian waiting times at signalized intersections. A total of 1181 pedestrians approaching the intersections during red light periods were observed in Beijing, China. Pedestrian crossing behaviors are classified into immediate crossing behavior and waiting behavior. The probability and effect of various covariates for pedestrians' immediate crossing behavior are identified by a logit model. Four accelerated failure time duration models based on the exponential, Weibull, lognormal and log-logistic distributions are proposed to examine the significant risk factors affecting duration times for pedestrians' waiting behavior. A joint duration model is developed to estimate pedestrian waiting times. Moreover, unobserved heterogeneity is considered in the proposed model. The results indicate that the Weibull AFT model with shared frailty is appropriate for modelling pedestrian waiting durations. Failure to account for heterogeneity would significantly underestimate the effects of covariates on waiting duration times. The proposed model provides a better understanding of pedestrian crossing behavior and more accurate estimation of pedestrian waiting times. It may be applicable in traffic system analysis in developing countries with high flow of mixed traffic. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Outpatient waiting time in Jos University Teaching Hospital ...

    African Journals Online (AJOL)

    Problem Long waiting time for services has been identified as a reason people avoid presenting to for care in African countries. Design Examination of causes for long outpatient waiting time and the effect of measures to reduce waiting time. Setting Outpatient department of the Jos University Teaching Hospital.

  6. Outpatient waiting time in Jos University Teaching Hospital ...

    African Journals Online (AJOL)

    Lessons learned In-house training of records staff had little long-term impact on reducing the time patients waited to collect their cards. Increased staffing and coordinating staff strength to correspond to times of peak patient load had the greatest effect in reducing outpatient waiting time. Constructive use of patient waiting ...

  7. The Nondeterministic Waiting Time Algorithm: A Review

    Directory of Open Access Journals (Sweden)

    John Jack

    2009-07-01

    Full Text Available We present briefly the Nondeterministic Waiting Time algorithm. Our technique for the simulation of biochemical reaction networks has the ability to mimic the Gillespie Algorithm for some networks and solutions to ordinary differential equations for other networks, depending on the rules of the system, the kinetic rates and numbers of molecules. We provide a full description of the algorithm as well as specifics on its implementation. Some results for two well-known models are reported. We have used the algorithm to explore Fas-mediated apoptosis models in cancerous and HIV-1 infected T cells.

  8. Willing to wait?: The influence of patient wait time on satisfaction with primary care

    Directory of Open Access Journals (Sweden)

    Balkrishnan Rajesh

    2007-02-01

    Full Text Available Abstract Background This study examined the relationship between patient waiting time and willingness to return for care and patient satisfaction ratings with primary care physicians. Methods Cross-sectional survey data on a convenience sample of 5,030 patients who rated their physicians on a web-based survey developed to collect detailed information on patient experiences with health care. The survey included self-reported information on wait times, time spent with doctor, and patient satisfaction. Results Longer waiting times were associated with lower patient satisfaction (p Conclusion The time spent with the physician is a stronger predictor of patient satisfaction than is the time spent in the waiting room. These results suggest that shortening patient waiting times at the expense of time spent with the patient to improve patient satisfaction scores would be counter-productive.

  9. Waiting time dynamics of priority-queue networks.

    Science.gov (United States)

    Min, Byungjoon; Goh, K-I; Kim, I-M

    2009-05-01

    We study the dynamics of priority-queue networks, generalizations of the binary interacting priority-queue model introduced by Oliveira and Vazquez [Physica A 388, 187 (2009)]. We found that the original AND-type protocol for interacting tasks is not scalable for the queue networks with loops because the dynamics becomes frozen due to the priority conflicts. We then consider a scalable interaction protocol, an OR-type one, and examine the effects of the network topology and the number of queues on the waiting time distributions of the priority-queue networks, finding that they exhibit power-law tails in all cases considered, yet with model-dependent power-law exponents. We also show that the synchronicity in task executions, giving rise to priority conflicts in the priority-queue networks, is a relevant factor in the queue dynamics that can change the power-law exponent of the waiting time distribution.

  10. Waiting times in discrete-time cyclic-service systems

    Science.gov (United States)

    Boxma, O. J.; Groenendijk, W. P.

    1987-03-01

    Single-server, multiqueue systems with cyclic service in discrete time are considered. Nonzero switchover times between consecutive queues are assumed; the service strategies at the various queues may differ. A decomposition for the amount of work in such systems is obtained, leading to an exact expression for a weighted sum of the mean waiting times at the various queues.

  11. Mean Waiting Time and Patients' Satisfaction in GOPD, Federal ...

    African Journals Online (AJOL)

    Background: Waiting time is a major determinant of the patients' level of satisfaction. It is the average time spent by the patient from the time of presentation in the hospital to the time of contact with a health service provider. Objective: To determine the mean waiting time in the Records department/card room and the General ...

  12. Hospital waiting time: the forgotten premise of healthcare service delivery?

    Science.gov (United States)

    Pillay, Datuk Ir M S; Ghazali, Roslan Johari Dato Mohd; Manaf, Noor Hazilah Abd; Abdullah, Abu Hassan Asaari; Bakar, Azman Abu; Salikin, Faisal; Umapathy, Mathyvani; Ali, Roslinah; Bidin, Noriah; Ismail, Wan Ismefariana Wan

    2011-01-01

    This is a national study which aims to determine the average waiting time in Malaysian public hospitals and to gauge the level of patient satisfaction with the waiting time. It also aims to identify factors perceived by healthcare providers which contribute to the waiting time problem. Self-administered questionnaires were the main method of data collection. Two sets of questionnaires were used. The first set solicited information from patients on their waiting time expereince. The second set elucidated information from hospital employees on the possible causes of lengthy waiting time. The questionnaires were administered in 21 public hospitals throughout all 13 states in Malaysia. A total of 13,000 responses were analysed for the patient survey and almost 3,000 were analysed for the employee survey. The findings indicate that on average, patients wait for more than two hours from registration to getting the prescription slip, while the contact time with medical personnel is only on average 15 minutes. Employee surveys on factors contributing to the lengthy waiting time indicate employee attitude and work process, heavy workload, management and supervision problems, and inadequate facilities to be among the contributory factors to the waiting time problem. Public healthcare in Malaysia is in a state of "excess demand", where demand for subsidised healthcare far outstrips supply, due to the large fee differential between public and private healthcare services. There is a need for hospital managers to reduce the boredom faced by patients while waiting, and to address the waiting time problem in a more scientific manner, as has been carried out in other countries through simulation and modelling techniques. Healthcare organisations are keen to address their waiting time problem. However, not much research has been carried out in this area. The study thus fills the lacuna in waiting time studies in healthcare organisations.

  13. TSA Security Checkpoint Wait Times – API (PMIS)

    Data.gov (United States)

    Department of Homeland Security — TSA operational data including: Airport wait time (hourly) data Airport throughput (hourly) data Prohibited item (hourly) data Monthly Objectives Report (MOR) data...

  14. Wait times, patient satisfaction scores, and the perception of care.

    Science.gov (United States)

    Bleustein, Clifford; Rothschild, David B; Valen, Andrew; Valatis, Eduardas; Schweitzer, Laura; Jones, Raleigh

    2014-05-01

    To analyze the impact of waiting time on patient satisfaction scores; not only of satisfaction with the provider in general, but also with the specific perception of the quality of care and physician abilities. Using surveys regarding patient satisfaction with provider care, data was collected from a sample of 11,352 survey responses returned by patients over the course of 1 year across all 44 ambulatory clinics within a large academic medical center. While a small minority of patients volunteered identification, the surveys were made anonymously. A questionnaire with Health Consumer Assessment of Healthcare Providers and Systems patient satisfaction and waiting time queries was administered via mail to all clinic patients-roughly 49,000-with a response rate of 23%. Employing a standard statistical approach, results were tabulated and stratified according to provider scores and wait time experience, and then analyzed using statistical modeling techniques. While it is well established that longer wait times are negatively associated with clinical provider scores of patient satisfaction, results indicated that every aspect of patient experience-specifically confidence in the care provider and perceived quality of care-correlated negatively with longer wait times. The clinical ambulatory patient experience is heavily influenced by time spent waiting for provider care. Not only are metrics regarding the likelihood to recommend and the overall satisfaction with the experience negatively impacted by longer wait times, but increased wait times also affect perceptions of information, instructions, and the overall treatment provided by physicians and other caregivers.

  15. Wait-Time and Multiple Representation Levels in Chemistry Lessons

    Science.gov (United States)

    Li, Winnie Sim Siew; Arshad, Mohammad Yusof

    2014-01-01

    Wait-time is an important aspect in a teaching and learning process, especially after the teacher has posed questions to students, as it is one of the factors in determining quality of students' responses. This article describes the practices of wait-time one after teacher's questions at multiple representation levels among twenty three chemistry…

  16. Asymptotic inference for waiting times and patiences in queues with abandonment

    DEFF Research Database (Denmark)

    Gorst-Rasmussen, Anders; Hansen, Martin Bøgsted

    Motivated by applications in call center management, we propose a framework based on empirical process techniques for inference about the waiting time and patience distribution in multiserver queues with abandonment. The framework rigorises heuristics based on survival analysis of independent...

  17. Reducing outpatient waiting time: a simulation modeling approach.

    Science.gov (United States)

    Aeenparast, Afsoon; Tabibi, Seyed Jamaleddin; Shahanaghi, Kamran; Aryanejhad, Mir Bahador

    2013-09-01

    The objective of this study was to provide a model for reducing outpatient waiting time by using simulation. A simulation model was constructed by using the data of arrival time, service time and flow of 357 patients referred to orthopedic clinic of a general teaching hospital in Tehran. The simulation model was validated before constructing different scenarios. In this study 10 scenarios were presented for reducing outpatient waiting time. Patients waiting time was divided into three levels regarding their physicians. These waiting times for all scenarios were computed by simulation model. According to the final scores the 9th scenario was selected as the best way for reducing outpatient's waiting time. Using the simulation as a decision making tool helps us to decide how we can reduce outpatient's waiting time. Comparison of outputs of this scenario and the based- case scenario in simulation model shows that combining physician's work time changing with patient's admission time changing (scenario 9) would reduce patient waiting time about 73.09%. Due to dynamic and complex nature of healthcare systems, the application of simulation for the planning, modeling and analysis of these systems has lagged behind traditional manufacturing practices. Rapid growth in health care system expenditures, technology and competition has increased the complexity of health care systems. Simulation is a useful tool for decision making in complex and probable systems.

  18. Determinants of Patient Waiting Time in the General Outpatient ...

    African Journals Online (AJOL)

    Patients spend substantial amount of time in the clinics waiting for services to be delivered by physicians and other allied health professionals. The degree to which health consumers are satisfied with the care received is strongly related to the quality of the waiting experience. Healthcare organizations that strive to deliver ...

  19. [Influence of waiting time on patient and companion satisfaction].

    Science.gov (United States)

    Fontova-Almató, A; Juvinyà-Canal, D; Suñer-Soler, R

    2015-01-01

    To evaluate patient and companion satisfaction of a hospital Emergency Department and its relationship with waiting time. Prospective, observational study. Hospital de Figueres Emergency Department (Girona, Spain). sociodemographic characteristics, satisfaction level, real and perceived waiting time for triage and being seen by a physician. A total of 285 responses were received from patients and companions. The mean age of the patients and companions (n=257) was 54.6years (SD=18.3). The mean overall satisfaction (n=273) was 7.6 (SD=2.2). Lower perceived waiting time until nurse triage was related to higher overall satisfaction (Spearman rho (ρ)=-0.242, P<.001), and lower perceived waiting time until being seen by physician, with a higher overall satisfaction (ρ=-0.304; P<.001). Users who were informed about estimated waiting time showed higher satisfaction than those who were not informed (P=.001). Perceived waiting time and the information about estimated waiting time determined overall satisfaction. Copyright © 2014 SECA. Published by Elsevier Espana. All rights reserved.

  20. Parental satisfaction with paediatric care, triage and waiting times.

    Science.gov (United States)

    Fitzpatrick, Nicholas; Breen, Daniel T; Taylor, James; Paul, Eldho; Grosvenor, Robert; Heggie, Katrina; Mahar, Patrick D

    2014-04-01

    The present study aims to determine parental and guardian's perceptions of paediatric emergency care and satisfaction with care, waiting times and triage category in a community ED. A structured questionnaire was provided to parents or guardians of paediatric patients presenting to emergency. The survey evaluated parent perceptions of waiting time, environment/facilities, professionalism and communication skills of staff and overall satisfaction of care. One hundred and thirty-three completed questionnaires were received from parents of paediatric patients. Responses were overall positive with respect to the multiple domains assessed. Parents generally considered waiting times to be appropriate and consistent with triage categories. Overall satisfaction was not significantly different for varying treatment or waiting times. Patients triaged as semi-urgent were of the opinion that waiting times were less appropriate than urgent, less-urgent or non-urgent patients. On the basis of the present study, patient perceptions and overall satisfaction of care does not appear to be primarily influenced by time spent waiting or receiving treatment. Attempts made at the triage process to ensure that semi-urgent patients have reasonable expectations of waiting times might provide an opportunity to improve these patients' expectations and perceptions. © 2014 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

  1. Wait times for gastroenterology consultation in Canada: The patients’ perspective

    Science.gov (United States)

    Paterson, WG; Barkun, AN; Hopman, WM; Leddin, DJ; Paré, P; Petrunia, DM; Sewitch, MJ; Switzer, C; van Zanten, S Veldhuyzen

    2010-01-01

    Long wait times for health care have become a significant issue in Canada. As part of the Canadian Association of Gastroenterology’s Human Resource initiative, a questionnaire was developed to survey patients regarding wait times for initial gastroenterology consultation and its impact. A total of 916 patients in six cities from across Canada completed the questionnaire at the time of initial consultation. Self-reported wait times varied widely, with 26.8% of respondents reporting waiting less than two weeks, 52.4% less than one month, 77.1% less than three months, 12.5% reported waiting longer than six months and 3.6% longer than one year. One-third of patients believed their wait time was too long, with 9% rating their wait time as ‘far too long’; 96.4% believed that maximal wait time should be less than three months, 78.9% believed it should be less than one month and 40.3% believed it should be less than two weeks. Of those working or attending school, 22.6% reported missing at least one day of work or school because of their symptoms in the month before their appointment, and 9.0% reported missing five or more days in the preceding month. A total of 20.2% of respondents reported being very worried about having a serious disease (ie, scored 6 or higher on 7-point Likert scale), and 17.6% and 14.8%, respectively, reported that their symptoms caused major impairment of social functioning and with the activities of daily living. These data suggest that a significant proportion of Canadians with digestive problems are not satisfied with their wait time for gastroenterology consultation. Furthermore, while awaiting consultation, many patients experience an impaired quality of life because of their gastrointestinal symptoms. PMID:20186353

  2. Waiting Time Increases Risk of Attrition in Gambling Disorder Treatment

    DEFF Research Database (Denmark)

    Linnet, Jakob; Pedersen, Anders Sune

    2014-01-01

    completion in gambling disorder. We compared 48 gambling disorder sufferers with a 56% completion rate (21 non-completers and 27 completers). Binomial logistic regression analysis showed that waiting time from initial contact to the first session with a therapist was a significant predictor of risk...... of attrition: longer waiting times were associated with increased risk of attrition. Age, gender, or comorbidity was not associated with an increased risk of attrition. These data suggest that gambling disorder sufferers benefit from fast access to treatment, and that longer waiting time increases the risk...

  3. Average waiting time profiles of uniform DQDB model

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-09-07

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

  4. [Improving the CMP appointment waiting time for children and adolescents].

    Science.gov (United States)

    Cani, Pascale

    2014-01-01

    The increasing activity of mental health centres for children and adolescents and longer waiting times in obtaining a first appointment have led an area of child psychiatry to question the organisation of new consultation applications. Two CMP in the sector had a waiting period of over 40 days for half of the patients. Two improvement actions were implemented:the implementation of organisation and reception nurses and the development of a new applications management process. The evaluation after one year showed a decrease of half of the appointment waiting time without changing the non showed up rate.

  5. Determinants of Patient Waiting Time in the General Outpatient ...

    African Journals Online (AJOL)

    Annals of Medical and Health Sciences Research | Oct-Dec 2013 | Vol 3 | Issue 4 | ... clinic waiting time is an important indicator of quality of ... healthcare services. ... Subjects and Methods: This descriptive cross‑sectional study was carried.

  6. Moderate alcohol consumption and waiting time to pregnancy

    DEFF Research Database (Denmark)

    Juhl, Mette; Andersen, Anne-Marie Nybo; Grønbæk, Morten

    2001-01-01

    BACKGROUND: Recent research indicates that even a moderate consumption of alcohol in women trying to become pregnant is associated with longer waiting time to pregnancy. The findings, though, are based upon few observations. METHODS: Self-reported data on alcohol intake and waiting time...... to pregnancy (0-2, 3-5, 6-12 and >12 months) was used for 39 612 pregnant women, recruited to the Danish National Birth Cohort within the first 24 weeks of pregnancy from 1997 to 2000. Main outcome measures were odds ratios (OR) for a prolonged waiting time to pregnancy according to alcohol intake. RESULTS......: In nulliparous women neither moderate nor high alcohol intake was related with longer waiting time to pregnancy compared with a low intake. In parous women, a modest association was seen only among those with an intake of >14 drinks per week (subfecundity OR 1.3; 95% confidence interval 1.0-1.7). Women who...

  7. Moderate alcohol consumption and waiting time to pregnancy

    DEFF Research Database (Denmark)

    Juhl, Mette; Andersen, Anne-Marie Nybo; Grønbaek, Morten

    2001-01-01

    BACKGROUND: Recent research indicates that even a moderate consumption of alcohol in women trying to become pregnant is associated with longer waiting time to pregnancy. The findings, though, are based upon few observations. METHODS: Self-reported data on alcohol intake and waiting time......: In nulliparous women neither moderate nor high alcohol intake was related with longer waiting time to pregnancy compared with a low intake. In parous women, a modest association was seen only among those with an intake of >14 drinks per week (subfecundity OR 1.3; 95% confidence interval 1.0-1.7). Women who...... to pregnancy (0-2, 3-5, 6-12 and >12 months) was used for 39 612 pregnant women, recruited to the Danish National Birth Cohort within the first 24 weeks of pregnancy from 1997 to 2000. Main outcome measures were odds ratios (OR) for a prolonged waiting time to pregnancy according to alcohol intake. RESULTS...

  8. Effect of emergency physician burnout on patient waiting times

    OpenAIRE

    De Stefano, Carla; Philippon, Anne-Laure; Krastinova, Evguenia; Hausfater, Pierre; Riou, Bruno; Adnet, Frederic; Freund, Yonathan

    2017-01-01

    International audience; Burnout is common in emergency physicians. This syndrome may negatively affect patient care and alter work productivity. We seek to assess whether burnout of emergency physicians impacts waiting times in the emergency department. Prospective study in an academic ED. All patients who visited the main ED for a 4-month period in 2016 were included. Target waiting times are assigned by triage nurse to patients on arrival depending on their severity. The primary endpoint wa...

  9. Adjusting patients streaming initiated by a wait time threshold in emergency department for minimizing opportunity cost.

    Science.gov (United States)

    Kim, Byungjoon B J; Delbridge, Theodore R; Kendrick, Dawn B

    2017-07-10

    Purpose Two different systems for streaming patients were considered to improve efficiency measures such as waiting times (WTs) and length of stay (LOS) for a current emergency department (ED). A typical fast track area (FTA) and a fast track with a wait time threshold (FTW) were designed and compared effectiveness measures from the perspective of total opportunity cost of all patients' WTs in the ED. The paper aims to discuss these issues. Design/methodology/approach This retrospective case study used computerized ED patient arrival to discharge time logs (between July 1, 2009 and June 30, 2010) to build computer simulation models for the FTA and fast track with wait time threshold systems. Various wait time thresholds were applied to stream different acuity-level patients. National average wait time for each acuity level was considered as a threshold to stream patients. Findings The fast track with a wait time threshold (FTW) showed a statistically significant shorter total wait time than the current system or a typical FTA system. The patient streaming management would improve the service quality of the ED as well as patients' opportunity costs by reducing the total LOS in the ED. Research limitations/implications The results of this study were based on computer simulation models with some assumptions such as no transfer times between processes, an arrival distribution of patients, and no deviation of flow pattern. Practical implications When the streaming of patient flow can be managed based on the wait time before being seen by a physician, it is possible for patients to see a physician within a tolerable wait time, which would result in less crowded in the ED. Originality/value A new streaming scheme of patients' flow may improve the performance of fast track system.

  10. Effect of emergency physician burnout on patient waiting times.

    Science.gov (United States)

    De Stefano, Carla; Philippon, Anne-Laure; Krastinova, Evguenia; Hausfater, Pierre; Riou, Bruno; Adnet, Frederic; Freund, Yonathan

    2017-07-04

    Burnout is common in emergency physicians. This syndrome may negatively affect patient care and alter work productivity. We seek to assess whether burnout of emergency physicians impacts waiting times in the emergency department. Prospective study in an academic ED. All patients who visited the main ED for a 4-month period in 2016 were included. Target waiting times are assigned by triage nurse to patients on arrival depending on their severity. The primary endpoint was an exceeded target waiting time for ED patients. All emergency physicians were surveyed by a psychologist to assess their level of burnout using the Maslach Burnout Inventory. We defined the level of burnout of the day in the ED as the mean burnout level of the physicians working that day (8:30 to the 8:30 the next day). A logistic regression model was performed to assess whether burnout level of the day was independently associated with prolonged waiting times, along with previously reported predictors. Target waiting time was exceeded in 7524 patients (59%). Twenty-six emergency physicians were surveyed. Median burnout score was 35 [Interquartile (24-49)]. A burnout level of the day higher than 35 was independently associated with an exceeded target waiting time (adjusted odds ratio 1.54, 95% confidence interval 1.39-1.70), together with previously reported predictors (i.e., day of the week, time of the day, trauma, age and daily census). Burnout of emergency physicians was independently associated with a prolonged waiting time for patients visiting the ED.

  11. Patient satisfaction with ambulatory healthcare services: waiting time and filling time.

    Science.gov (United States)

    Dansky, K H; Miles, J

    1997-01-01

    Customer satisfaction is an important measure of service quality in healthcare organizations. This study investigated the relationship between patient waiting and satisfaction with ambulatory healthcare services, with waiting times divided into segments of the patient-care episode. Two management techniques to alter perceptions of waiting were also examined. Regression models measuring the effect of waiting times on satisfaction found that the total time spent waiting for the clinician was the most significant predictor of patient satisfaction. Informing patients how long their wait would be and being occupied during the wait were also significant predictors of patient satisfaction. These results show that waiting times, even if they cannot be shortened, can be managed more effectively to improve patient satisfaction.

  12. Waiting Time as an Index of Quality of Nursing Care

    Science.gov (United States)

    Haussmann, R. K. Dieter

    1970-01-01

    A model of the patient care process, based on queueing theory, is described and its parameters defined empirically for application to a burn unit. For the particular case, the model is shown to provide a close approximation to observed data. The model is descriptive, with an output of expected waiting times for various priorities of patient demand. The waiting times so estimated constitute an index of the quality of nursing care and afford a means of predicting changes in quality with changes in staffing or inpatient load. The model facilitates investigation of the relationships among three factors: patient condition, nurses' activity priorities, and patient load per nurse. PMID:5482376

  13. Waiting Time Policies in the Health Care Sector. What Works?

    DEFF Research Database (Denmark)

    Christiansen, Terkel; Bech, Mickael

    2013-01-01

    times. In addition, a range of other measures may indirectly have affected waiting times, such as a general increase in spending on health care, the general practitioners’ role as gate-keepers, increased use of activity-based hospital reimbursement, increasing use of private heath insurance and private...

  14. Satisfaction and Wait Time of Patients Visiting a Family Practice Clinic

    Science.gov (United States)

    Bestvater, David; Dunn, Earl V.; Townsend, Connie; Nelson, Wendy

    1988-01-01

    Data relating to wait times and time spent with nurses and physicians were recorded for 656 patients visiting a large family-practice unit. Patients were asked to provide estimates of their wait times and ratings of the acceptability of these wait intervals. Actual wait times were usually longer than those estimated by the patient, and total wait times were considered reasonable. The results of the study show high levels of patient satisfaction and indicate that few patients are dissatisfied until total wait time exceeds forty-five minutes. Different age groups appear to have different expectations, however, and younger patients are more likely to be dissatisfied with their wait times. PMID:21264021

  15. Using Queuing Theory and Simulation Modelling to Reduce Waiting Times in An Iranian Emergency Department.

    Science.gov (United States)

    Haghighinejad, Hourvash Akbari; Kharazmi, Erfan; Hatam, Nahid; Yousefi, Sedigheh; Hesami, Seyed Ali; Danaei, Mina; Askarian, Mehrdad

    2016-01-01

    Hospital emergencies have an essential role in health care systems. In the last decade, developed countries have paid great attention to overcrowding crisis in emergency departments. Simulation analysis of complex models for which conditions will change over time is much more effective than analytical solutions and emergency department (ED) is one of the most complex models for analysis. This study aimed to determine the number of patients who are waiting and waiting time in emergency department services in an Iranian hospital ED and to propose scenarios to reduce its queue and waiting time. This is a cross-sectional study in which simulation software (Arena, version 14) was used. The input information was extracted from the hospital database as well as through sampling. The objective was to evaluate the response variables of waiting time, number waiting and utilization of each server and test the three scenarios to improve them. Running the models for 30 days revealed that a total of 4088 patients left the ED after being served and 1238 patients waited in the queue for admission in the ED bed area at end of the run (actually these patients received services out of their defined capacity). The first scenario result in the number of beds had to be increased from 81 to179 in order that the number waiting of the "bed area" server become almost zero. The second scenario which attempted to limit hospitalization time in the ED bed area to the third quartile of the serving time distribution could decrease the number waiting to 586 patients. Doubling the bed capacity in the emergency department and consequently other resources and capacity appropriately can solve the problem. This includes bed capacity requirement for both critically ill and less critically ill patients. Classification of ED internal sections based on severity of illness instead of medical specialty is another solution.

  16. Quality Improvement Cycles that Reduced Waiting Times at ...

    African Journals Online (AJOL)

    Surveys were done in May and September to analyse the problems causing prolonged waiting times. The implemented change included instituting a functional triage system, improvement of the process of up- and down-referrals to and from the tertiary hospital, easy access to stock, reorganisation of doctors' duty roster, ...

  17. Potential impact of enhanced practice efficiency on endoscopy waiting times.

    LENUS (Irish Health Repository)

    Harewood, G C

    2009-06-01

    With the growing demand on endoscopy services, optimising practice efficiency has assumed increasing importance. Prior research has identified practice changes, which increase the efficiency in endoscopy. In this study, the potential impact of these practice changes on the current and projected future endoscopy waiting times at our institution was assessed.

  18. EVALUTION OF THE SINGLE INTERCITY FREIGHT TRANSPORTATION WAITING TIME

    Directory of Open Access Journals (Sweden)

    N. Ponomariova

    2015-07-01

    Full Text Available The example of vechicle operation on the pendulum intercity route during single freightages processing is considered. Two approaches to the definition of the single freightage waiting time by the carrier are proposed. These approaches allow to take into account the probability of the single freightage obtaining by the carrier during the different load level of the transport enterprise capacity.

  19. Public Mode Access And Waiting Time Variability In Maiduguri ...

    African Journals Online (AJOL)

    This work examines public mode access and waiting time variations in Maiduguri Metropolitan Area. Data for the study were sought through a comprehensive field survey using a travel diary questionnaire. A total of 623 households were surveyed in 342 dwelling units. The results indicate that variations in modal access and ...

  20. Time to Endoscopy in Patients with Colorectal Cancer: Analysis of Wait-Times

    Directory of Open Access Journals (Sweden)

    Renée M. Janssen

    2016-01-01

    Full Text Available Objective. The Canadian Association of Gastroenterology Wait Time Consensus Group recommends that patients with symptoms associated with colorectal cancer (CRC should have an endoscopic examination within 2 months. However, in a recent survey of Canadian gastroenterologists, wait-times for endoscopy were considerably longer than the current guidelines recommend. The purpose of this study was to evaluate wait-times for colonoscopy in patients who were subsequently found to have CRC through the Division of Gastroenterology at St. Paul’s Hospital (SPH. Methods. This study was a retrospective chart review of outpatients seen for consultation and endoscopy ultimately diagnosed with CRC. Subjects were identified through the SPH pathology database for the inclusion period 2010 through 2013. Data collected included wait-times, subject characteristics, cancer characteristics, and outcomes. Results. 246 subjects met inclusion criteria for this study. The mean wait-time from primary care referral to first office visit was 63 days; the mean wait-time to first endoscopy was 94 days. Patients with symptoms waited a mean of 86 days to first endoscopy, considerably longer than the national recommended guideline of 60 days. There was no apparent effect of length of wait-time on node positivity or presence of distant metastases at the time of diagnosis. Conclusion. Wait-times for outpatient consultation and endoscopic evaluation at the St. Paul’s Hospital Division of Gastroenterology exceed current guidelines.

  1. On the control, stability, and waiting time in a slotted ALOHA random-access system

    Science.gov (United States)

    Ferguson, M. J.

    1975-01-01

    This paper explores some of the boundaries in performance of slotted ALOHA systems by analyzing a simple and almost optimal centrally supervised control. The control results in a very simple Markov chain model and allows an examination of stability, conditional waiting time distribution of transmitting terminals, and many other system measures. The key to the simplicity is to have a probability of successful packet transmission that is independent of the number of transmitting terminals. In considering waiting time, we calculate the mean and other moments of the waiting time of a terminal when it enters the system to find (n - 1) other terminals already there competing for the channel. Under this control, the average time is proportional to n. The control requires exact knowledge of the number of terminals contending for the channel, and hence is not implementable, except as an approximation.

  2. Patient Satisfaction Is Associated With Time With Provider But Not Clinic Wait Time Among Orthopedic Patients.

    Science.gov (United States)

    Patterson, Brendan M; Eskildsen, Scott M; Clement, R Carter; Lin, Feng-Chang; Olcott, Christopher W; Del Gaizo, Daniel J; Tennant, Joshua N

    2017-01-01

    Clinic wait time is considered an important predictor of patient satisfaction. The goal of this study was to determine whether patient satisfaction among orthopedic patients is associated with clinic wait time and time with the provider. The authors prospectively enrolled 182 patients at their outpatient orthopedic clinic. Clinic wait time was defined as the time between patient check-in and being seen by the surgeon. Time spent with the provider was defined as the total time the patient spent in the examination room with the surgeon. The Consumer Assessment of Healthcare Providers and Systems survey was used to measure patient satisfaction. Factors associated with increased patient satisfaction included patient age and increased time with the surgeon (P=.024 and P=.037, respectively), but not clinic wait time (P=.625). Perceived wait time was subject to a high level of error, and most patients did not accurately report whether they had been waiting longer than 15 minutes to see a provider until they had waited at least 60 minutes (P=.007). If the results of the current study are generalizable, time with the surgeon is associated with patient satisfaction in orthopedic clinics, but wait time is not. Further, the study findings showed that patients in this setting did not have an accurate perception of actual wait time, with many patients underestimating the time they waited to see a provider. Thus, a potential strategy for improving patient satisfaction is to spend more time with each patient, even at the expense of increased wait time. [Orthopedics. 2017; 40(1):43-48.]. Copyright 2016, SLACK Incorporated.

  3. Using Queuing Theory and Simulation Modelling to Reduce Waiting Times in An Iranian Emergency Department

    Directory of Open Access Journals (Sweden)

    Hourvash Akbari Haghighinejad

    2016-01-01

    Full Text Available Background: Hospital emergencies have an essential role in health care systems. In the last decade, developed countries have paid great attention to overcrowding crisis in emergency departments. Simulation analysis of complex models for which conditions will change over time is much more effective than analytical solutions and emergency department (ED is one of the most complex models for analysis. This study aimed to determine the number of patients who are waiting and waiting time in emergency department services in an Iranian hospital ED and to propose scenarios to reduce its queue and waiting time. Methods: This is a cross-sectional study in which simulation software (Arena, version 14 was used. The input information was extracted from the hospital database as well as through sampling. The objective was to evaluate the response variables of waiting time, number waiting and utilization of each server and test the three scenarios to improve them. Results: Running the models for 30 days revealed that a total of 4088 patients left the ED after being served and 1238 patients waited in the queue for admission in the ED bed area at end of the run (actually these patients received services out of their defined capacity. The first scenario result in the number of beds had to be increased from 81 to179 in order that the number waiting of the “bed area” server become almost zero. The second scenario which attempted to limit hospitalization time in the ED bed area to the third quartile of the serving time distribution could decrease the numberwaiting to 586 patients. Conclusion: Doubling the bed capacity in the emergency department and consequently other resources and capacity appropriately can solve the problem. This includes bed capacity requirement for both critically ill and less critically ill patients. Classification of ED internal sections based on severity of illness instead of medical specialty is another solution.

  4. Reducing wait time in a hospital pharmacy to promote customer service.

    Science.gov (United States)

    Slowiak, Julie M; Huitema, Bradley E; Dickinson, Alyce M

    2008-01-01

    The purpose of this study was to compare the effects of 2 different interventions on wait times at a hospital outpatient pharmacy: (1) giving feedback to employees about customer satisfaction with wait times and (2) giving a combined intervention package that included giving more specific feedback about actual wait times and goal setting for wait time reduction in addition to the customer satisfaction feedback. The relationship between customer satisfaction ratings and wait times was examined to determine whether wait times affected customer service satisfaction. Participants were 10 employees (4 pharmacists and 6 technicians) of an outpatient pharmacy. Wait times and customer satisfaction ratings were collected for "waiting customers." An ABCBA' within-subjects design was used to assess the effects of the interventions on both wait time and customer satisfaction, where A was the baseline (no feedback and no goal setting); B was the customer satisfaction feedback; C was the customer satisfaction feedback, the wait time feedback, and the goal setting for wait time reduction; and A' was a follow-up condition that was similar to the original baseline condition. Wait times were reduced by approximately 20%, and there was concomitant increased shift in levels of customer satisfaction, as indicated by the correlation between these variables (r = -0.57 and P customer's wait time. Data from this study may provide useful preliminary benchmarking data for standard pharmacy wait times.

  5. Patient Satisfaction with Wait-Times for Breast Cancer Surgery in Newfoundland and Labrador.

    Science.gov (United States)

    Mathews, Maria; Ryan, Dana; Gadag, Vereesh; West, Roy

    2016-02-01

    Do shorter waits for breast cancer surgery lead to greater wait-related patient satisfaction? Using survey and cancer clinic chart data of 99 patients with breast cancer from Newfoundland and Labrador, we found that median wait-time from first visit to a surgeon to surgery was 22.0 days and 87% were satisfied with their wait-time. Wait-related satisfaction was not associated with the length of wait but rather with the stage, severity of treatment, wait-time for a diagnosis and satisfaction with diagnosis-related wait. These findings highlight the importance of an early and timely diagnosis in patients' perceptions of breast cancer care wait-times. Copyright © 2016 Longwoods Publishing.

  6. The effect of superfluid hydrodynamics on pulsar glitch sizes and waiting times

    Science.gov (United States)

    Haskell, B.

    2016-09-01

    Pulsar glitches, sudden jumps in frequency observed in many radio pulsars, may be the macroscopic manifestation of superfluid vortex avalanches on the microscopic scale. Small-scale quantum mechanical simulations of vortex motion in a decelerating container have shown that such events are possible and predict power-law distributions for the size of the events, and exponential distributions for the waiting time. Despite a paucity of data, this prediction is consistent with the size and waiting time distributions of most glitching pulsars. Nevertheless, a few object appear to glitch quasi-periodically, and exhibit many large glitches, while a recent study of the Crab pulsar has suggested deviations from a power-law distribution for smaller glitches. In this Letter, we incorporate the results of quantum mechanical simulations in a macroscopic superfluid hydrodynamics simulation. We show that the effect of vortex coupling to the neutron and proton fluids in the star naturally leads to deviations from power-law distributions for sizes, and from exponential distributions for waiting times, and we predict a cutoff in the size distribution for small glitches.

  7. Computation and evaluation of scheduled waiting time for railway networks

    DEFF Research Database (Denmark)

    Landex, Alex

    2010-01-01

    Timetables are affected by scheduled waiting time (SWT) that prolongs the travel times for trains and thereby passengers. SWT occurs when a train hinders another train to run with the wanted speed. The SWT affects both the trains and the passengers in the trains. The passengers may be further...... affected due to longer transfer times to other trains. SWT can be estimated analytically for a given timetable or by simulation of timetables and/or plans of operation. The simulation of SWT has the benefit that it is possible to examine the entire network. This makes it possible to improve the future...

  8. In the queue for total joint replacement: patients' perspectives on waiting times. Ontario Hip and Knee Replacement Project Team.

    Science.gov (United States)

    Llewellyn-Thomas, H A; Arshinoff, R; Bell, M; Williams, J I; Naylor, C D

    1998-02-01

    We assessed patients on the waiting lists of a purposive sample of orthopaedic surgeons in Ontario, Canada, to determine patients' attitudes towards time waiting for hip or knee replacement. We focused on 148 patients who did not have a definite operative date, obtaining complete information on 124 (84%). Symptom severity was assessed with the Western Ontario/McMaster Osteoarthritis Index and a disease-specific standard gamble was used to elicit patients' overall utility for their arthritic state. Next, in a trade-off task, patients considered a hypothetical choice between a 1-month wait for a surgeon who could provide a 2% risk of post-operative mortality, or a 6-month wait for joint replacement with a 1% risk of post-operative mortality. Waiting times were then shifted systematically until the patient abandoned his/her initial choice, generating a conditional maximal acceptable wait time. Patients were divided in their attitudes, with 57% initially choosing a 6-month wait with a 1% mortality risk. The overall distribution of conditional maximum acceptable wait time scores ranged from 1 to 26 months, with a median of 7 months. Utility values were independently but weakly associated with patients' tolerance of waiting times (adjusted R-square = 0.059, P = 0.004). After splitting the sample along the median into subgroups with a relatively 'low' and 'high' tolerance for waiting, the subgroup with the apparently lower tolerance for waiting reported lower utility scores (z = 2.951; P = 0.004) and shorter times since their surgeon first advised them of the need for surgery (z = 3.014; P = 0.003). These results suggest that, in the establishment and monitoring of a queue management system for quality-of-life-enhancing surgery, patients' own perceptions of their overall symptomatic burden and ability to tolerate delayed relief should be considered along with information derived from clinical judgements and pre-weighted health status instruments.

  9. Asymptotic inference for waiting times and patiences in queues with abandonment

    DEFF Research Database (Denmark)

    Gorst-Rasmussen, Anders; Hansen, Martin Bøgsted

    2009-01-01

    Motivated by applications in call center management, we propose a framework based on empirical process techniques for inference about waiting time and patience distributions in multiserver queues with abandonment. The framework rigorises heuristics based on survival analysis of independent and id...... and statistical tests, including a simple bootstrap two-sample test for comparing patience distributions. A small simulation study and a real data example are presented....

  10. Using probability of drug use as independent variable in a register-based pharmacoepidemiological cause-effect study-An application of the reverse waiting time distribution.

    Science.gov (United States)

    Hallas, Jesper; Pottegård, Anton; Støvring, Henrik

    2017-12-01

    In register-based pharmacoepidemiological studies, each day of follow-up is usually categorized either as exposed or unexposed. However, there is an underlying continuous probability of exposure, and by insisting on a dichotomy, researchers unwillingly force a nondifferential misclassification into their analyses. We have recently developed a model whereby probability of exposure can be modeled, and we tested this on an empirical case of nonsteroidal anti-inflammatory drug (NSAID)-induced upper gastrointestinal bleeding (UGIB). We used a case-controls data set, consisting of 3568 cases of severe UGIB and 35 552 matched controls. Exposure to NSAID was based on 3 different conventional dichotomous measures. In addition, we tested 3 probabilistic exposure measures, a simple univariate backward-recurrence model, a "full" multivariable model, and a "reduced" multivariable model. Odds ratios (ORs) and 95% confidence intervals for the association between NSAID use and UGIB were calculated by conditional logistic regression, while adjusting for preselected confounders. Compared to the conventional dichotomous exposure measures, the probabilistic exposure measures generated adjusted ORs in the upper range (4.37-4.75) while at the same time having the most narrow confidence intervals (ratio between upper and lower confidence limit, 1.46-1.50). Some ORs generated by conventional measures were higher than the probabilistic ORs, but only when the assumed period of intake was unrealistically short. The pattern of high ORs and narrow confidence intervals in probabilistic exposure measures is compatible with less nondifferential misclassification of exposure than in a dichotomous exposure model. Probabilistic exposure measures appear to be an attractive alternative to conventional exposure measures. Copyright © 2017 John Wiley & Sons, Ltd.

  11. Perceptions of cardiac rehabilitation patients, specialists and rehabilitation programs regarding cardiac rehabilitation wait times

    Directory of Open Access Journals (Sweden)

    Grace Sherry L

    2012-08-01

    Full Text Available Abstract Background In 2006, the Canadian Cardiovascular Society (CCS Access to Care Working Group recommended a 30-day wait time benchmark for cardiac rehabilitation (CR. The objectives of the current study were to: (1 describe cardiac patient perceptions of actual and ideal CR wait times, (2 describe and compare cardiac specialist and CR program perceptions of wait times, as well as whether the recommendations are appropriate and feasible, and (3 investigate actual wait times and factors that CR programs perceive to affect these wait times. Methods Postal and online surveys to assess perceptions of CR wait times were administered to CR enrollees at intake into 1 of 8 programs, all CCS member cardiac specialists treating patients indicated for CR, and all CR programs listed in Canadian directories. Actual wait times were ascertained from the Canadian Cardiac Rehabilitation Registry. The design was cross-sectional. Responses were described and compared. Results Responses were received from 163 CR enrollees, 71 cardiac specialists (9.3% response rate, and 92 CR programs (61.7% response rate. Patients reported that their wait time from hospital discharge to CR initiation was 65.6 ± 88.4 days (median, 42 days, while their ideal median wait time was 28 days. Most patients (91.5% considered their wait to be acceptable, but ideal wait times varied significantly by the type of cardiac indication for CR. There were significant differences between specialist and program perceptions of the appropriate number of days to wait by most indications, with CR programs perceiving shorter waits as appropriate (p  Conclusions Wait times following access to cardiac rehabilitation are prolonged compared with consensus recommendations, and yet are generally acceptable to most patients. Wait times following percutaneous coronary intervention in particular may need to be shortened. Future research is required to provide an evidence base for wait time

  12. Joint optimisation of transmission and waiting times in cognitive radio

    Science.gov (United States)

    Amini, Mohammadreza; Samimi, Abouzar; Mirzavandi, Asra

    2016-04-01

    Transmission time optimisation is one of the key considerations of cognitive network design. There are many studies in cognitive radio networks (CRNs) focusing on finding the best transmission time for secondary users (SUs) to maximise transmission or energy efficiency. While longer sensing duration leads to a higher sensing accuracy and causes less interference, the SU spends less time for transmission and more energy on sensing spectrum. On the other hand, when the transmission duration becomes longer, although the SU has more opportunities to access the channel, it may encounter higher interference due to primary user (PU) returns and the probability of collision becomes higher. In this article, in a decentralised slotted protocol for CRN, the SU spectrum access is proved as a renewal process, then the interference due to PU return during SU transmission, the missed opportunities due to waiting for the channel to become idle and the energy consumed by the SU in the whole spectrum access process including idling energy, transmission energy and sensing energy consumption are formulated and integrated into newly defined efficiency to obtain the optimum transmission time and waiting time.

  13. Continuous time random walk with generic waiting time and external force.

    Science.gov (United States)

    Fa, Kwok Sau; Wang, K G

    2010-05-01

    We derive an integrodifferential diffusion equation for decoupled continuous time random walk that is valid for a generic waiting time probability density function and external force. Using this equation we also study diffusion behaviors for a couple of specific waiting time probability density functions such as exponential, a combination of power law and generalized Mittag-Leffler function and a sum of exponentials under the influence of a harmonic trap. We show that first two waiting time probability density functions can reproduce the results of the ordinary and fractional diffusion equations for all the time regions from small to large times. But the third one shows a much more complicated pattern. Furthermore, from the integrodifferential diffusion equation we show that the second Einstein relation can hold for any waiting time probability density function.

  14. The effect of waiting time and distance on hospital choice for English cataract patients.

    Science.gov (United States)

    Sivey, Peter

    2012-04-01

    This paper applies latent-class multinomial logit models to the choice of hospital for cataract operations in the UK NHS. We concentrate on the effects of travel time and waiting time and especially on estimating the waiting time elasticity of demand. Models including hospital fixed effects rely on changes over time in waiting time to indentify coefficients. We show how using a latent-class multinomial logit model characterises the unobserved heterogeneity in GP practices' choice behaviour and affects the estimated elasticities of travel time and waiting time. The models estimate waiting time elasticities of demand of approximately -0.1, comparable with previous waiting time-demand models. For the average waiting time elasticity, the simple multinomial logit models are good approximations of the latent-class logit results. Copyright © 2011 John Wiley & Sons, Ltd.

  15. An automaton approach for waiting times in DNA evolution

    CERN Document Server

    Behrens, S; Nicodeme, P

    2011-01-01

    In a recent article, Behrens and Vingron (JCB 17, 12, 2010) compute waiting times for k-mers to appear during DNA evolution under the assumption that the considered k-mers do not occur in the initial DNA sequence, an issue arising when studying the evolution of regulatory DNA sequences with regard to transcription factor (TF) binding site emergence. The mathematical analysis underlying their computation assumes that occurrences of words under interest do not overlap. We relax here this assumption by use of an automata approach. In an alphabet of size 4 like the DNA alphabet, most words have no or a low autocorrelation; therefore, globally, our results confirm those of Behrens and Vingron. The outcome is quite different when considering highly autocorrelated k-mers; in this case, the autocorrelation pushes down the probability of occurrence of these k-mers at generation 1 and, consequently, increases the waiting time for apparition of these k-mers up to 40%. An analysis of existing TF binding sites unveils a s...

  16. An Estimation Method of Waiting Time for Health Service at Hospital by Using a Portable RFID and Robust Estimation

    Science.gov (United States)

    Ishigaki, Tsukasa; Yamamoto, Yoshinobu; Nakamura, Yoshiyuki; Akamatsu, Motoyuki

    Patients that have an health service by doctor have to wait long time at many hospitals. The long waiting time is the worst factor of patient's dissatisfaction for hospital service according to questionnaire for patients. The present paper describes an estimation method of the waiting time for each patient without an electronic medical chart system. The method applies a portable RFID system to data acquisition and robust estimation of probability distribution of the health service and test time by doctor for high-accurate waiting time estimation. We carried out an health service of data acquisition at a real hospital and verified the efficiency of the proposed method. The proposed system widely can be used as data acquisition system in various fields such as marketing service, entertainment or human behavior measurement.

  17. Reducing pharmacy wait time to promote customer service: a follow-up study.

    Science.gov (United States)

    Slowiak, Julie M; Huitema, Bradley E

    2015-01-01

    The present study had 3 objectives: (1) to evaluate the effects of 2 different interventions (feedback regarding customer satisfaction with wait time and combined feedback and goal setting) on wait time in a hospital outpatient pharmacy; (2) to assess the extent to which the previously applied interventions maintained their effects; and (3) to evaluate the differences between the effects of the original study and those of the present follow-up study. Participants were 10 employees (4 pharmacists and 6 technicians) of an outpatient pharmacy. Wait times and customer satisfaction ratings were collected for "waiting customers." An ABCB within-subjects design was used to assess the effects of the interventions on both wait time and customer satisfaction, where A was the baseline (no feedback and no goal setting); B was the customer satisfaction feedback; and C was the customer satisfaction feedback, the wait time feedback, and the goal setting for wait time reduction. Wait time decreased after baseline when the combined intervention was introduced, and wait time increased with the reintroduction of satisfaction feedback (alone). The results of the replication study confirm the pattern of the results of the original study and demonstrate high sensitivity of levels of customer satisfaction with wait time. The most impressive result of the replication is the nearly 2-year maintenance of lower wait time between the end of the original study and the beginning (baseline) of the replication.

  18. Reading of Waiting, Time and Social Change in S. N. A. Agoro's ...

    African Journals Online (AJOL)

    The act of waiting as a critical feature of the human condition is the most significant and intense thematic engagement in Beckett's Waiting for Godot. The study notes that aside the circle of the absurd art in drama, the subject of waiting and time has not been given adequate dramatic representation by dramatists outside the ...

  19. Pooled Open Blocks Shorten Wait Times for Nonelective Surgical Cases.

    Science.gov (United States)

    Zenteno, Ana C; Carnes, Tim; Levi, Retsef; Daily, Bethany J; Price, Devon; Moss, Susan C; Dunn, Peter F

    2015-07-01

    Assess the impact of the implementation of a data-driven scheduling strategy that aimed to improve the access to care of nonelective surgical patients at Massachusetts General Hospital (MGH). Between July 2009 and June 2010, MGH experienced increasing throughput challenges in its perioperative environment: approximately 30% of the nonelective patients were waiting more than the prescribed amount of time to get to surgery, hampering access to care and aggravating the lack of inpatient beds. This work describes the design and implementation of an "open block" strategy: operating room (OR) blocks were reserved for nonelective patients during regular working hours (prime time) and their management centralized. Discrete event simulation showed that 5 rooms would decrease the percentage of delayed patients from 30% to 2%, assuming that OR availability was the only reason for preoperative delay. Implementation began in January 2012. We compare metrics for June through December of 2012 against the same months of 2011. The average preoperative wait time of all nonelective surgical patients decreased by 25.5% (P < 0.001), even with a volume increase of 9%. The number of bed-days occupied by nonurgent patients before surgery declined by 13.3% whereas the volume increased by 4.5%. The large-scale application of an open-block strategy significantly improved the flow of nonelective patients at MGH when OR availability was a major reason for delay. Rigorous metrics were developed to evaluate its performance. Strong managerial leadership was crucial to enact the new practices and turn them into organizational change.

  20. Turn to staff for dramatic improvement in wait times, productivity.

    Science.gov (United States)

    2011-09-01

    Baylor Medical Center in Garland,TX, has been able to drastically reduce ED wait times, as well as the LWBS rate by streamlining the triage process and implementing a staff-driven improvement effort aimed at identifying inefficiencies and replacing them with solutions that work. The result is 11 beds of added capacity just from changes in patient flow. A cross section of volunteers from the ED staff reviewed metrics and devised solutions that they felt would work best to boost efficiency and eliminate bottlenecks. Solutions included letting low-acuity patients move themselves between care settings, freeing the charge nurse from patient care duties so that he or she could oversee patient flow, and empowering physician-nurse teams to see patients more quickly. ED managers say leadership is important, but letting staff drive the improvement process is key to their success.

  1. SU-F-P-20: Predicting Waiting Times in Radiation Oncology Using Machine Learning

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, A; Herrera, D; Hijal, T; Kildea, J [McGill University Health Centre, Montreal, Quebec (Canada); Hendren, L; Leung, A; Wainberg, J; Sawaf, M; Gorshkov, M; Maglieri, R; Keshavarz, M [McGill University, Montreal, Quebec (Canada)

    2016-06-15

    Purpose: Waiting times remain one of the most vexing patient satisfaction challenges facing healthcare. Waiting time uncertainty can cause patients, who are already sick or in pain, to worry about when they will receive the care they need. These waiting periods are often difficult for staff to predict and only rough estimates are typically provided based on personal experience. This level of uncertainty leaves most patients unable to plan their calendar, making the waiting experience uncomfortable, even painful. In the present era of electronic health records (EHRs), waiting times need not be so uncertain. Extensive EHRs provide unprecedented amounts of data that can statistically cluster towards representative values when appropriate patient cohorts are selected. Predictive modelling, such as machine learning, is a powerful approach that benefits from large, potentially complex, datasets. The essence of machine learning is to predict future outcomes by learning from previous experience. The application of a machine learning algorithm to waiting time data has the potential to produce personalized waiting time predictions such that the uncertainty may be removed from the patient’s waiting experience. Methods: In radiation oncology, patients typically experience several types of waiting (eg waiting at home for treatment planning, waiting in the waiting room for oncologist appointments and daily waiting in the waiting room for radiotherapy treatments). A daily treatment wait time model is discussed in this report. To develop a prediction model using our large dataset (with more than 100k sample points) a variety of machine learning algorithms from the Python package sklearn were tested. Results: We found that the Random Forest Regressor model provides the best predictions for daily radiotherapy treatment waiting times. Using this model, we achieved a median residual (actual value minus predicted value) of 0.25 minutes and a standard deviation residual of 6.5 minutes

  2. Delay decomposition at a single server queue with constant service time and multiple inputs. [Waiting time on computer network

    Science.gov (United States)

    Ziegler, C.; Schilling, D. L.

    1977-01-01

    Two networks consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivalencies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self delay and interference delay.

  3. Associations Between Waiting Times, Service Times, and Patient Satisfaction in an Endocrinology Outpatient Department: A Time Study and Questionnaire Survey.

    Science.gov (United States)

    Xie, Zhenzhen; Or, Calvin

    2017-01-01

    The issue of long patient waits has attracted increasing public attention due to the negative effects of waiting on patients' satisfaction with health care. The present study examined the associations between actual waiting time, perceived acceptability of waiting time, actual service time, perceived acceptability of service time, actual visit duration, and the level of patient satisfaction with care. We conducted a cross-sectional time study and questionnaire survey of endocrinology outpatients visiting a major teaching hospital in China. Our results show that actual waiting time was negatively associated with patient satisfaction regarding several aspects of the care they received. Also, patients who were less satisfied with the sociocultural atmosphere and the identity-oriented approach to their care tended to perceive the amounts of time they spent waiting and receiving care as less acceptable. It is not always possible to prevent dissatisfaction with waiting, or to actually reduce waiting times by increasing resources such as increased staffing. However, several improvements in care services can be considered. Our suggestions include providing clearer, more transparent information to keep patients informed about the health care services that they may receive, and the health care professionals who are responsible for those services. We also suggest that care providers are encouraged to continue to show empathy and respect for patients, that patients are provided with private areas where they can talk with health professionals and no one can overhear, and that hospital staff treat the family members or friends who accompany patients in a courteous and friendly way.

  4. The effect of waiting times on demand and supply for elective surgery: Evidence from Italy.

    Science.gov (United States)

    Riganti, Andrea; Siciliani, Luigi; Fiorio, Carlo V

    2017-09-01

    Waiting times are a major policy concern in publicly funded health systems across OECD countries. Economists have argued that, in the presence of excess demand, waiting times act as nonmonetary prices to bring demand for and supply of health care in equilibrium. Using administrative data disaggregated by region and surgical procedure over 2010-2014 in Italy, we estimate demand and supply elasticities with respect to waiting times. We employ linear regression models with first differences and instrumental variables to deal with endogeneity of waiting times. We find that demand is inelastic to waiting times while supply is more elastic. Estimates of demand elasticity are between -0.15 to -0.24. Our results have implications on the effectiveness of policies aimed at increasing supply and their ability to reduce waiting times. Copyright © 2017 John Wiley & Sons, Ltd.

  5. The surgical waiting time initiative: A review of the Nigerian situation.

    Science.gov (United States)

    Abdulkareem, Imran Haruna

    2014-11-01

    The concept of surgical waiting time initiative (SWAT) was introduced in developed countries to reduce elective surgery waiting lists and increase efficiency of care. It was supplemented by increasing popularity of day surgery, which shortens elective waiting lists and minimises cancellations. It is established in Western countries, but not in developing countries like Nigeria where it is still evolving. A search was carried out in Pub Med, Google, African journals online (AJOL), Athens and Ovid for relevant publications on elective surgery waiting list in Nigeria, published in English language. Words include waiting/wait time, waiting time initiative, time to surgery, waiting for operations, waiting for intervention, waiting for procedures and time before surgery in Nigeria. A total of 37 articles published from Nigeria in relation to various waiting times were found from the search and fulfilled the inclusion criteria. Among them, 11 publications (29.7%) were related to emergency surgery waiting times, 10 (27%) were related to clinic waiting times, 9 (24.3%) were related to day case surgery, 2 (5.5%) were related to investigation waiting times and only 5 (13.5%) articles were specifically published on elective surgery waiting times. A total of 9 articles (24.5%) were published from obstetrics and gynaecology (OG), 7 (19%) from general surgery, 5 (13.5%) from public health, 3 (8%) from orthopaedics, 3 (8%) from general practice (GP), 3 (8%) from paediatrics/paediatric surgery, 2 (5.5%) from ophthalmology, 1 (2.7%) from ear, nose and throat (ENT), 1 (2.7%) from plastic surgery, 1 (2.7%) from urology and only 1 (2.7%) article was published from dental/maxillofacial surgery. Waiting times mean different things to different health practitioners in Nigeria. There were only 5/37 articles (13.5%) specifically related to elective surgery waiting times in Nigerian hospitals, which show that the concept of the SWAT is still evolving in Nigeria. Of the 37, 11 (24

  6. Kramers' escape problem for fractional Klein-Kramers equation with tempered α-stable waiting times.

    Science.gov (United States)

    Gajda, Janusz; Magdziarz, Marcin

    2011-08-01

    In this paper we extend the subdiffusive Klein-Kramers model, in which the waiting times are modeled by the α-stable laws, to the case of waiting times belonging to the class of tempered α-stable distributions. We introduce a generalized version of the Klein-Kramers equation, in which the fractional Riemman-Liouville derivative is replaced with a more general integro-differential operator. This allows a transition from the initial subdiffusive character of motion to the standard diffusion for long times to be modeled. Taking advantage of the corresponding Langevin equation, we study some properties of the tempered dynamics, in particular, we approximate solutions of the tempered Klein-Kramers equation via Monte Carlo methods. Also, we study the distribution of the escape time from the potential well and compare it to the classical results in the Kramers escape theory. Finally, we derive the analytical formula for the first-passage-time distribution for the case of free particles. We show that the well-known Sparre Andersen scaling holds also for the tempered subdiffusion.

  7. Models of emergency departments for reducing patient waiting times.

    Directory of Open Access Journals (Sweden)

    Marek Laskowski

    Full Text Available In this paper, we apply both agent-based models and queuing models to investigate patient access and patient flow through emergency departments. The objective of this work is to gain insights into the comparative contributions and limitations of these complementary techniques, in their ability to contribute empirical input into healthcare policy and practice guidelines. The models were developed independently, with a view to compare their suitability to emergency department simulation. The current models implement relatively simple general scenarios, and rely on a combination of simulated and real data to simulate patient flow in a single emergency department or in multiple interacting emergency departments. In addition, several concepts from telecommunications engineering are translated into this modeling context. The framework of multiple-priority queue systems and the genetic programming paradigm of evolutionary machine learning are applied as a means of forecasting patient wait times and as a means of evolving healthcare policy, respectively. The models' utility lies in their ability to provide qualitative insights into the relative sensitivities and impacts of model input parameters, to illuminate scenarios worthy of more complex investigation, and to iteratively validate the models as they continue to be refined and extended. The paper discusses future efforts to refine, extend, and validate the models with more data and real data relative to physical (spatial-topographical and social inputs (staffing, patient care models, etc.. Real data obtained through proximity location and tracking system technologies is one example discussed.

  8. The acceptability of waiting times for elective general surgery and the appropriateness of prioritising patients

    Directory of Open Access Journals (Sweden)

    Knol Dirk L

    2007-02-01

    Full Text Available Abstract Background Problematic waiting lists in public health care threaten the equity and timeliness of care provision in several countries. This study assesses different stakeholders' views on the acceptability of waiting lists in health care, their preferences for priority care of patients, and their judgements on acceptable waiting times for surgical patients. Methods A questionnaire survey was conducted among 257 former patients (82 with varicose veins, 86 with inguinal hernia, and 89 with gallstones, 101 surgeons, 95 occupational physicians, and 65 GPs. Judgements on acceptable waiting times were assessed using vignettes of patients with varicose veins, inguinal hernia, and gallstones. Results Participants endorsed the prioritisation of patients based on clinical need, but not on ability to benefit. The groups had significantly different opinions (p Acceptable waiting times ranged between 2 and 25 weeks depending on the type of disorder (p Conclusion The explicit prioritisation of patients seems an accepted means for reducing the overall burden from waiting lists. The disagreement about appropriate prioritisation criteria and the need for uniformity, however, raises concern about equity when implementing prioritisation in daily practice. Single factor waiting time thresholds seem insufficient for securing timely care provision in the presence of long waiting lists as they do not account for the different consequences of waiting between patients.

  9. The surgical waiting time initiative: A review of the Nigerian situation

    OpenAIRE

    Imran Haruna Abdulkareem

    2014-01-01

    SUMMARY The concept of surgical waiting time initiative (SWAT) was introduced in developed countries to reduce elective surgery waiting lists and increase efficiency of care. It was supplemented by increasing popularity of day surgery, which shortens elective waiting lists and minimises cancellations. It is established in Western countries, but not in developing countries like Nigeria where it is still evolving. A search was carried out in Pub Med, Google, African journals online (AJOL), Athe...

  10. Effects of Wait Time When Communicating with Children Who Have Sensory and Additional Disabilities

    Science.gov (United States)

    Johnson, Nicole; Parker, Amy T.

    2013-01-01

    Introduction: This study utilized wait-time procedures to determine if they are effective in helping children with deafblindness or multiple disabilities that include a visual impairment communicate in their home. Methods: A single subject with an alternating treatment design was used for the study. Zero- to one-second wait time was utilized…

  11. Client waiting time in an urban primary health care centre in Lagos ...

    African Journals Online (AJOL)

    Background: Primary Health Care is the usual entry point into the health system and has the potential to touch the lives of most people. However one of the reasons for poor uptake of health services at primary health care facilities in Nigeria is long waiting time. This study was carried out to assess client waiting time and ...

  12. Access to Specialist Gastroenterology Care in Canada: The Practice Audit in Gastroenterology (PAGE Wait Times Program

    Directory of Open Access Journals (Sweden)

    David Armstrong

    2008-01-01

    Full Text Available BACKGROUND: Canadian wait time data are available for the treatment of cancer and heart disease, as well as for joint replacement, cataract surgery and diagnostic imaging procedures. Wait times for gastroenterology consultation and procedures have not been studied, although digestive diseases pose a greater economic burden in Canada than cancer or heart disease.

  13. Synchronization Control of Scheduled Train Services to Minimize Passenger Waiting Times

    NARCIS (Netherlands)

    Goverde, R.M.P.

    1998-01-01

    During operation a transportation service may wait on delayed feeder services to secure scheduled transfers. For low-frequent connecting services this has a major positive impact on the transfer waiting times. However, the resulting synchronization control time of the connecting service also affects

  14. Customer waiting times in an (R,S) inventory system with compound Poisson demand

    NARCIS (Netherlands)

    van der Heijden, Matthijs C.; de Kok, A.G.

    1992-01-01

    Besides service level and mean physical stock, customer waiting time is an important performance characteristic for an inventory system. In this paper we discuss the calculation of this waiting time in case a periodic review control policy with order-up-to-levelS is used and customers arrive

  15. First in Line Waiting Times as a Tool for Analysing Queueing Systems

    DEFF Research Database (Denmark)

    Koole, G. M.; Nielsen, Bo Friis; Nielsen, Thomas Bang

    2012-01-01

    We introduce a new approach to modelling queueing systems where the priority or the routing of customers depends on the time the first customer has waited in the queue. This past waiting time of the first customer in line, WFIL, is used as the primary variable for our approach. A Markov chain...

  16. Cigarette smoking and waiting time to pregnancy: results of a pilot study.

    Science.gov (United States)

    Zilaitiene, Birute; Dirzauskas, Marius; Preiksa, Romualdas Tomas; Matulevicius, Valentinas

    2007-01-01

    Waiting time to pregnancy is an important characteristic of human reproductive health, which has not been investigated in Lithuania until now. Data on waiting time to pregnancy have been collected from medical records of 111 women admitted to the Department of Obstetrics, Klaipeda Hospital. Seven women in whom pregnancy was the result of infertility treatment were excluded from the analysis, and the rest 104 cases were analyzed. We evaluated waiting time to pregnancy in respect to the age of couples, contraceptive use, cigarette smoking of both partners, and some other features of obstetric history. The mean waiting time to pregnancy in the cohort was 5.21+/-7.03 months. If both partners smoked, the mean waiting time to pregnancy was significantly longer than in nonsmoking couples (7.68+/-9.41 vs. 4.30+/-5.73, P<0.05). Risk to have waiting time to pregnancy longer than 6 months was significantly higher if both partners smoked as compared to nonsmoking couples (OR 3.32, 95% CI 1.07-10.30, P=0.03), while paternal smoking and smoking of any partner did not increase this risk significantly. The other possible factors - age, living place (rural or city), previous contraceptive use, regularity of menstrual cycle, and frequency of intercourse - did not influence waiting time to pregnancy significantly. Results obtained from this pilot study enable us to plan and implement a larger-scale study of waiting time to pregnancy in Lithuanian population.

  17. The relationship between educational attainment and waiting time among the elderly in Norway.

    Science.gov (United States)

    Carlsen, Fredrik; Kaarboe, Oddvar Martin

    2015-11-01

    We investigate whether educational attainment affects waiting time of elderly patients in somatic hospitals. We consider three distinct pathways; that patients with different educational attainment have different disease patterns, that patients with different levels of education receive treatments at different hospitals, and that patient choice and supply of local health services within hospital catchment areas explain unequal waiting time of different educational groups. We find evidence of an educational gradient in waiting time for male patients, but not for female patients. Conditional on age, male patients with tertiary education wait 45% shorter than male patients with secondary or primary education. The first pathway is not quantitatively important as controlling for disease patters has little effect on relative waiting times. The second pathway is important. Relative to patients with primary education, variation in waiting time and education level across local hospitals contributes to higher waiting time for male patients with secondary education and female patients with secondary or tertiary education and lower waiting time for male patients with tertiary education. These effects are in the order of 15-20%. The third pathway is also quantitatively important. The educational gradients within catchment areas disappear when we control for travel distance and supply of private specialists. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. Waiting time among acute abdominal emergencies in a Nigerian ...

    African Journals Online (AJOL)

    Background-In many patients presenting with an acute surgical abdomen, the outcome of management is determined by the promptness of the appropriate surgical intervention. The average interval the patient has to spent waiting for treatment at first presentation to hospital with an acute abdominal emergency is unknown ...

  19. Waiting time analysis for MX/G/1 priority queues with/without vacations under random order of service discipline

    Directory of Open Access Journals (Sweden)

    Norikazu Kawasaki

    2000-01-01

    Full Text Available We study MX/G/1 nonpreemptive and preemptive-resume priority queues with/without vacations under random order of service (ROS discipline within each class. By considering the conditional waiting times given the states of the system, which an arbitrary message observes upon arrival, we derive the Laplace-Stieltjes transforms of the waiting time distributions and explicitly obtain the first two moments. The relationship for the second moments under ROS and first-come first-served disciplines extends the one found previously by Takacs and Fuhrmann for non-priority single arrival queues.

  20. An investigation of the relationship between cataract surgery wait times and rates of surgery.

    Science.gov (United States)

    Hodge, William G; Ramsay, Timothy; Fergusson, Dean; Si, Francie; Pan, Irene; Su, Yinghua; Buhrmann, Ralf

    2012-02-01

    The relationship between cataract surgery wait times and rates of surgery was investigated to determine whether wait times correlate with rates of surgery. Cross-sectional study. We collected 2 Ontario registries for cataract surgeries: (i) Cancer Care Ontario wait time registry; and (ii) The Ontario Health Insurance Plan billing records. Both registries were used to determine whether wait times correlated with rates of surgery, and the data were then stratified by region of the province, priority (severity) of cases, age, and sex. The total number of surgeries performed between April 2, 2007, and March 31, 2008, was 65,520. The overall mean number of wait days was 69.8 days; the mean patient age was 72.5 years; and the surgery rate was 540.3 per 100,000 members of the population. For high-priority cases (priorities 1 and 2), there was a very weak inverse correlation (p = -0.27 and -0.21) between wait time and surgery rate, whereas the overall correlation between wait time and surgical rate was close to zero in both databases, regardless of the region, the patients' ages, and the patients' genders. This study demonstrates a very weak correlation between wait times for and rates of cataract surgery, and this should be a concern for policy makers. Further study is needed to see whether this null relationship persists over time and whether it exists for other monitored wait time procedures. Reasons for this null relationship will have to be determined and remedied as the use of wait times becomes a more widespread outcome in Canadian Healthcare. Copyright © 2012 Canadian Ophthalmological Society. All rights reserved.

  1. Waiting Time: The De-Subjectification of Children in Danish Asylum Centres

    Science.gov (United States)

    Vitus, Kathrine

    2010-01-01

    This article analyses the relationship between time and subjectification, focusing on the temporal structures created within Danish asylum centres and politics, and on children's experiences of and reactions to open-ended waiting. Such waiting leads to existential boredom which manifests in the children as restlessness, fatigue and despair. The…

  2. General practice cooperatives: long waiting times for home visits due to long distances?

    Science.gov (United States)

    Giesen, Paul; van Lin, Nieke; Mokkink, Henk; van den Bosch, Wil; Grol, Richard

    2007-02-12

    The introduction of large-scale out-of-hours GP cooperatives has led to questions about increased distances between the GP cooperatives and the homes of patients and the increasing waiting times for home visits in urgent cases. We studied the relationship between the patient's waiting time for a home visit and the distance to the GP cooperative. Further, we investigated if other factors (traffic intensity, home visit intensity, time of day, and degree of urgency) influenced waiting times. Cross-sectional study at four GP cooperatives. We used variance analysis to calculate waiting times for various categories of traffic intensity, home visit intensity, time of day, and degree of urgency. We used multiple logistic regression analysis to calculate to what degree these factors affected the ability to meet targets in urgent cases. The average waiting time for 5827 consultations was 30.5 min. Traffic intensity, home visit intensity, time of day and urgency of the complaint all seemed to affect waiting times significantly. A total of 88.7% of all patients were seen within 1 hour. In the case of life-threatening complaints (U1), 68.8% of the patients were seen within 15 min, and 95.6% of those with acute complaints (U2) were seen within 1 hour. For patients with life-threatening complaints (U1) the percentage of visits that met the time target of 15 minutes decreased from 86.5% (less than 2.5 km) to 16.7% (equals or more than 20 km). Although home visits waiting times increase with increasing distance from the GP cooperative, it appears that traffic intensity, home visit intensity, and urgency also influence waiting times. For patients with life-threatening complaints waiting times increase sharply with the distance.

  3. Survey of Access to GastroEnterology in Canada: The SAGE wait times program

    Science.gov (United States)

    Leddin, Desmond; Bridges, Ronald J; Morgan, David G; Fallone, Carlo; Render, Craig; Plourde, Victor; Gray, Jim; Switzer, Connie; McHattie, Jim; Singh, Harminder; Walli, Eric; Murray, Iain; Nestel, Anthony; Sinclair, Paul; Chen, Ying; Irvine, E Jan

    2010-01-01

    BACKGROUND: Assessment of current wait times for specialist health services in Canada is a key method that can assist government and health care providers to plan wisely for future health needs. These data are not readily available. A method to capture wait time data at the time of consultation or procedure has been developed, which should be applicable to other specialist groups and also allows for assessment of wait time trends over intervals of years. METHODS: In November 2008, gastroenterologists across Canada were asked to complete a questionnaire (online or by fax) that included personal demographics and data from one week on at least five consecutive new consultations and five consecutive procedure patients who had not previously undergone a procedure for the same indication. Wait times were collected for 18 primary indications and results were then compared with similar survey data collected in 2005. RESULTS: The longest wait times observed were for screening colonoscopy (201 days) and surveillance of previous colon cancer or polyps (272 days). The shortest wait times were for cancer-likely based on imaging or physical examination (82 days), severe or rapidly progressing dysphagia or odynophagia (83 days), documented iron-deficiency anemia (90 days) and dyspepsia with alarm symptoms (99 days). Compared with 2005 data, total wait times in 2008 were lengthened overall (127 days versus 155 days; Pgastroenterology services continue to exceed consensus conference recommended targets and have significantly worsened since 2005. PMID:20186352

  4. Public views on a wait time management initiative: a matter of communication.

    Science.gov (United States)

    Bruni, Rebecca A; Laupacis, Andreas; Levinson, Wendy; Martin, Douglas K

    2010-08-05

    Many countries have tried to reduce waiting times for health care through formal wait time reduction strategies. Our paper describes views of members of the public about a wait time management initiative--the Ontario Wait Time Strategy (OWTS) (Canada). Scholars and governmental reports have advocated for increased public involvement in wait time management. We provide empirically derived recommendations for public engagement in a wait time management initiative. Two qualitative studies: 1) an analysis of all emails sent by the public to the (OWTS) email address; and 2) in-depth interviews with members of the Ontario public. Email correspondents and interview participants supported the intent of the OWTS. However they wanted more information about the Strategy and its actions. Interview participants did not feel they were sufficiently made aware of the Strategy and email correspondents requested additional information beyond what was offered on the Strategy's website. Moreover, the email correspondents believed that some of the information that was provided on the Strategy's website and through the media was inaccurate, misleading, and even dishonest. Interview participants strongly supported public involvement in the OWTS priority setting. Findings suggest the public wanted increased communication from and with the OWTS. Effective communication can facilitate successful public engagement, and in turn fair and legitimate priority setting. Based on the study's findings we developed concrete recommendations for improving public involvement in wait time management.

  5. Improving wait times to care for individuals with multimorbidities and complex conditions using value stream mapping.

    Science.gov (United States)

    Sampalli, Tara; Desy, Michel; Dhir, Minakshi; Edwards, Lynn; Dickson, Robert; Blackmore, Gail

    2015-04-05

    Recognizing the significant impact of wait times for care for individuals with complex chronic conditions, we applied a LEAN methodology, namely - an adaptation of Value Stream Mapping (VSM) to meet the needs of people with multiple chronic conditions and to improve wait times without additional resources or funding. Over an 18-month time period, staff applied a patient-centric approach that included LEAN methodology of VSM to improve wait times to care. Our framework of evaluation was grounded in the needs and perspectives of patients and individuals waiting to receive care. Patient centric views were obtained through surveys such as Patient Assessment of Chronic Illness Care (PACIC) and process engineering based questions. In addition, LEAN methodology, VSM was added to identify non-value added processes contributing to wait times. The care team successfully reduced wait times to 2 months in 2014 with no wait times for care anticipated in 2015. Increased patient engagement and satisfaction are also outcomes of this innovative initiative. In addition, successful transformations and implementation have resulted in resource efficiencies without increase in costs. Patients have shown significant improvements in functional health following Integrated Chronic Care Service (ICCS) intervention. The methodology will be applied to other chronic disease management areas in Capital Health and the province. Wait times to care in the management of multimoribidities and other complex conditions can add a significant burden not only on the affected individuals but also on the healthcare system. In this study, a novel and modified LEAN methodology has been applied to embed the voice of the patient in care delivery processes and to reduce wait times to care in the management of complex chronic conditions. © 2015 by Kerman University of Medical Sciences.

  6. Improving wait times to care for individuals with multimorbidities and complex conditions using value stream mapping

    Science.gov (United States)

    Sampalli, Tara; Desy, Michel; Dhir, Minakshi; Edwards, Lynn; Dickson, Robert; Blackmore, Gail

    2015-01-01

    Background: Recognizing the significant impact of wait times for care for individuals with complex chronic conditions, we applied a LEAN methodology, namely – an adaptation of Value Stream Mapping (VSM) to meet the needs of people with multiple chronic conditions and to improve wait times without additional resources or funding. Methods: Over an 18-month time period, staff applied a patient-centric approach that included LEAN methodology of VSM to improve wait times to care. Our framework of evaluation was grounded in the needs and perspectives of patients and individuals waiting to receive care. Patient centric views were obtained through surveys such as Patient Assessment of Chronic Illness Care (PACIC) and process engineering based questions. In addition, LEAN methodology, VSM was added to identify non-value added processes contributing to wait times. Results: The care team successfully reduced wait times to 2 months in 2014 with no wait times for care anticipated in 2015. Increased patient engagement and satisfaction are also outcomes of this innovative initiative. In addition, successful transformations and implementation have resulted in resource efficiencies without increase in costs. Patients have shown significant improvements in functional health following Integrated Chronic Care Service (ICCS) intervention. The methodology will be applied to other chronic disease management areas in Capital Health and the province. Conclusion: Wait times to care in the management of multimoribidities and other complex conditions can add a significant burden not only on the affected individuals but also on the healthcare system. In this study, a novel and modified LEAN methodology has been applied to embed the voice of the patient in care delivery processes and to reduce wait times to care in the management of complex chronic conditions. PMID:26188810

  7. Wait-time, classroom discourse, and the influence of sociocultural factors in science teaching

    Science.gov (United States)

    Jegede, Olugbemiro J.; Olajide, Janet O.

    Wait-time, a variable related to questioning in a teaching-learning situation, has been found to have implications for the inquiry mode of science teaching especially in Western classroom environments. Aside from the fact that the literature is very sparse in this area about what obtains in developing countries, nothing appears to be available with regard to how wait-time interacts with the sociocultural factors within non-Western science classrooms. In a non-Western country such as Nigeria where most science programs in schools are inquiry-oriented, do teachers take notice of, and effectively use, wait-time in the teaching-learning process? Are science teachers able to effectively use the mediating role of sociocultural factors in science teaching in a traditional environment which expects children to be seen only and not heard? The main purpose of this study was to investigate the wait-time of Nigerian integrated science teachers in relation to the amount of students' participation in inquiry. This study also investigated the relationship between wait-time and sociocultural attitudinal factors prevalent in traditional societies. The instruments used for data collection were the Hough's Observational Schedule and a modified version of the Socio-Cultural Environment Scale (SCES); a stop-watch was used to measure the wait-time of audio-recorded integrated science lessons of 37 integrated science teachers from selected junior secondary schools in Kaduna State, Nigeria. The results showed that the average wait-time TT and wait-time ST of the integrated science teachers was 3.0 seconds and 0.7 seconds, respectively. The study reported the amount of student participation in the student-teacher classroom discourse to be very low. Wait-time was also shown to have a strong relationship with sociocultural factors of authoritarianism, goal structure, societal expectation, and traditional worldview. The pedagogical and curricular implications of the results have been

  8. Improving Wait Times to Care for Individuals with Multimorbidities and Complex Conditions Using Value Stream Mapping

    Directory of Open Access Journals (Sweden)

    Tara Sampalli

    2015-07-01

    Full Text Available Background Recognizing the significant impact of wait times for care for individuals with complex chronic conditions, we applied a LEAN methodology, namely – an adaptation of Value Stream Mapping (VSM to meet the needs of people with multiple chronic conditions and to improve wait times without additional resources or funding. Methods Over an 18-month time period, staff applied a patient-centric approach that included LEAN methodology of VSM to improve wait times to care. Our framework of evaluation was grounded in the needs and perspectives of patients and individuals waiting to receive care. Patient centric views were obtained through surveys such as Patient Assessment of Chronic Illness Care (PACIC and process engineering based questions. In addition, LEAN methodology, VSM was added to identify non-value added processes contributing to wait times. Results The care team successfully reduced wait times to 2 months in 2014 with no wait times for care anticipated in 2015. Increased patient engagement and satisfaction are also outcomes of this innovative initiative. In addition, successful transformations and implementation have resulted in resource efficiencies without increase in costs. Patients have shown significant improvements in functional health following Integrated Chronic Care Service (ICCS intervention. The methodology will be applied to other chronic disease management areas in Capital Health and the province. Conclusion Wait times to care in the management of multimoribidities and other complex conditions can add a significant burden not only on the affected individuals but also on the healthcare system. In this study, a novel and modified LEAN methodology has been applied to embed the voice of the patient in care delivery processes and to reduce wait times to care in the management of complex chronic conditions.

  9. Radiotherapy waiting times for women with breast cancer: a population-based cohort study.

    OpenAIRE

    Jack, RH; Davies, EA; Robinson, D; Sainsbury, R.; Moller, H.

    2007-01-01

    Abstract Background Waiting times for cancer patients are a national priority in the UK. Previous studies have shown variation between cancer networks in the time between diagnosis and start of radiotherapy for all cancer patients. Studies of the relationship between delay in receiving treatment and survival of breast cancer patients have been inconsistent. This study aimed to examine factors associated with waiting times for radiotherapy for breast cancer patients. Methods 35,354 women resid...

  10. Radiotherapy waiting times for women with breast cancer: a population-based cohort study

    OpenAIRE

    Jack, R H; Davies, E A; Robinson, D; Sainsbury, R.; Møller, H

    2007-01-01

    Background: Waiting times for cancer patients are a national priority in the UK. Previous studies have shown variation between cancer networks in the time between diagnosis and start of radiotherapy for all cancer patients. Studies of the relationship between delay in receiving treatment and survival of breast cancer patients have been inconsistent. This study aimed to examine factors associated with waiting times for radiotherapy for breast cancer patients. Methods: 35,354 women r...

  11. Waiting times and output process of a server computed via Wiener-Hopf factorization

    Science.gov (United States)

    Hasslinger, Gerhard

    1998-10-01

    Non-renewal processes are relevant in queueing analysis to include various types of traffic arising in integrated services communication networks. We consider a workload based approach to the single server queue in discrete time domain with semi-Markov arrivals (SMP/G/1). Starting from a subdivision of the busy periods, we generalize a computationally attractive algorithm for the discrete time GI/G/1 queue. The stationary distributions of the waiting and idle time as well as the moments of the busy period are computed. Performance results are given for deterministic servers with autoregressive input and the output process of a server is modeled by adapting a SMP of small size.

  12. Waiting times for diagnosis and treatment of head and neck cancer in Denmark in 2010 compared to 1992 and 2002

    DEFF Research Database (Denmark)

    Lyhne, N M; Christensen, A; Alanin, M C

    2012-01-01

    BACKGROUND AND AIM: Significant tumour progression was observed during waiting time for treatment of head and neck cancer. To reduce waiting times, a Danish national policy of fast track accelerated clinical pathways was introduced in 2007. This study describes changes in waiting time and the pot...

  13. Application of a Quality Control Circle to Reduce the Wait Times between Continuous Surgeries.

    Science.gov (United States)

    Zhang, Hairong; Wang, Li; Cai, Yueye; Ye, Ronghua; Lin, Jingyi; Jiang, Dongdong

    2015-06-01

    To investigate how to shorten patient wait times between continuous ocular operations and to evaluate the influence of a quality control circle (QCC) on operating room management. QCC management was established to conduct activities. Clinical data were collected to analyze the causes of long wait times between continuous surgeries. Effective measures were undertaken correspondingly. The staff from QCC actively undertook measures that would significantly shorten patient wait times between continuous ocular surgeries (P < 0.05). Multiple measures, such as setting up a QCC, enhancing the arrangement of surgical procedures, establishing effective communication channels, optimizing human resources, and integrating the use of instruments, can effectively shorten patient wait times between continuous vitreous or retinal surgeries.

  14. Improvement of Waiting Time for Patients Referring to Emergency Room Using Discrete Event Simulation

    Directory of Open Access Journals (Sweden)

    Y Zare Mehrjardi

    2011-07-01

    Full Text Available Introduction: Many simulation studies have been conducted in the hospitals and first in the emergency departments to increase the productivity. The first issue in the field of service quality and hence the patient right is “waiting time”. The goal of this study was to reduce patients waiting times, emergency service timing, modeling and improving using discrete event simulation. Methods: This was a descriptive - analytical study by the cross-sectional method on 150 patients referred to the emergency department in a public hospital. All necessary data were collected using questionnaire and through observation. Simulation model was designed using Arena software. Results: Our computer simulation model indicates that the maximum waiting time is the time waited for the test request till the results are received by the MD and also the time is necessary for the consultation and examination purposes. Among the five different scenarios, alternative 5 is more interesting economically since it requires only three additional staffs to bring down waiting times. Conclusion: According to research results, to reduce patient waiting time, the Triage processing in the emergency departments and the employment of emergency medicine expert, and the ordering of the diagnostic processes in the early stages of treatment as such as laboratory ordering for emergency patients are of main necessity.

  15. Intake of wine, beer and spirits and waiting time to pregnancy

    DEFF Research Database (Denmark)

    Juhl, Mette; Olsen, Jørn; Andersen, Anne-Marie Nybo

    2003-01-01

    A high intake of alcohol may prolong waiting time to pregnancy, whereas a moderate intake may have no or perhaps even a positive effect on fecundity. In previous studies on fecundity, different types of beverages have not been taken into consideration, although moderate wine drinkers appear to ha...... fewer strokes, lung and digestive tract cancers, and overall mortality than both abstainers and moderate drinkers of beer or spirits. We examined the association between different types of alcoholic beverages and waiting time to pregnancy....

  16. Waiting times for surgical and diagnostic procedures in public hospitals in Mexico.

    Science.gov (United States)

    Contreras-Loya, David; Gómez-Dantés, Octavio; Puentes, Esteban; Garrido-Latorre, Francisco; Castro-Tinoco, Manuel; Fajardo-Dolci, Germán

    2015-01-01

    A retrospective evaluation of waiting times for elective procedures was conducted in a sample of Mexican public hospitals from the following institutions: the Mexican Institute for Social Security (IMSS), the Institute for Social Security and Social Services for Civil Servants (ISSSTE) and the Ministry of Health (MoH). Our aim was to describe current waiting times and identify opportunities to redistribute service demand among public institutions. We examined current waiting times and productivity for seven elective surgical and four diagnostic imaging procedures, selected on the basis of their relative frequency and comparability with other national health systems. Mean waiting time for the seven surgical procedures in the three institutions was 14 weeks. IMSS and ISSSTE hospitals showed better performance (12 and 13 weeks) than the MoH hospitals (15 weeks). Mean waiting time for the four diagnostic procedures was 11 weeks. IMSS hospitals (10 weeks) showed better average waiting times than ISSSTE (12 weeks) and MoH hospitals (11 weeks). Substantial variations were revealed, not only among institutions but also within the same institution. These variations need to be addressed in order to improve patient satisfaction.

  17. Waiting times for surgical and diagnostic procedures in public hospitals in Mexico

    Directory of Open Access Journals (Sweden)

    David Contreras-Loya

    2015-01-01

    Full Text Available Objective. A retrospective evaluation of waiting times for elective procedures was conducted in a sample of Mexican public hospitals from the following institutions: the Mexican Institute for Social Security (IMSS, the Institute for Social Security and Social Services for Civil Servants (ISSSTE and the Ministry of Health (MoH. Our aim was to describe current waiting times and identify opportunities to redistribute service demand among public institutions. Materials and methods. We examined current waiting times and productivity for seven elective surgical and four diagnostic imaging procedures, selected on the basis of their relative frequency and comparability with other national health systems. Results. Mean waiting time for the seven surgical procedures in the three institutions was 14 weeks. IMSS and ISSSTE hospitals showed better performance (12 and 13 weeks than the MoH hospitals (15 weeks. Mean waiting time for the four diagnostic procedures was 11 weeks. IMSS hospitals (10 weeks showed better average waiting times than ISSSTE (12 weeks and MoH hospitals (11 weeks. Conclusion. Substantial variations were revealed, not only among institutions but also within the same institution. These variations need to be addressed in order to improve patient satisfaction.

  18. Patient waiting time in the outpatient clinic at a central surgical hospital of Vietnam: Implications for resource allocation [version 3; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Tho Dinh Tran

    2017-06-01

    Full Text Available Background: Patient waiting time is considered as a crucial parameter in the assessment of healthcare quality and patients’ satisfaction towards healthcare services. Data concerning this has remained limited in Vietnam. Thus, this study aims to assess patient waiting time in the outpatient clinic in Viet Duc Hospital (Hanoi, Vietnam in order to enable stakeholders to inform evidence-based interventions to improve the quality of healthcare services. Methods: A cross-sectional study was conducted from June 2014 to June 2015 in the outpatient clinic at Viet Duc Hospital. Waiting time stratified by years (2014 and 2015, months of the year, weekdays, and hours of the day were extracted from Hospital Management software and carefully calculated. Stata 12.0 was employed to analyze data, including the average time (M± SD, frequencies and percentage (%. Results: There was a total of 137,881 patients involved in the study. The average waiting time from registration to preliminary diagnosis in 2014 was 50.41 minutes, and in 2015 was 42.05 minutes. A longer waiting time was recorded in the morning and in those having health insurance. Conclusions: Our results provided evidence that despite the decrease of waiting time from 2014 to 2015, waiting time was much higher among patients having health insurance compared to their counterparts. The findings suggest that human resources promotion and distribution should be emphasized in outpatient clinics and health insurance-related administrative procedures should be simplified.

  19. The pattern for waiting time in the context of multiple stochastic process

    CERN Document Server

    Jamali, Tayeb; Farahani, S Vasheghani

    2015-01-01

    The aim here is to provide a deeper understanding on the concept of waiting time in application to multiple stochastic processes. This obliges us to work with the vector stochastic process which enables considering at least two stochastic process at simultaneous time instances. In the present study the plan is to master vector stochastic processes by developing the level crossing method. The reason that the previous level-crossing methods lack generality is based on their individual element studies, where the coupling between the components of the vector stochastic process had been simply neglected. In the present work by introducing the generalized level crossing method, consideration of coupling between the components has become possible. This enables analyzing and hence extracting information out of coupled processes usually faced when working in tensor environments. The results obtained by this technique state that in addition to the point distribution of the vector stochastic process, the coupling plays ...

  20. The effects of publishing emergency department wait time on patient utilization patterns in a community with two emergency department sites: a retrospective, quasi-experiment design.

    Science.gov (United States)

    Xie, Bin; Youash, Sabrina

    2011-06-14

    Providing emergency department (ED) wait time information to the public has been suggested as a mechanism to reduce lengthy ED wait times (by enabling patients to select the ED site with shorter wait time), but the effects of such a program have not been evaluated. We evaluated the effects of such a program in a community with two ED sites. Descriptive statistics for wait times of the two sites before and after the publication of wait time information were used to evaluate the effects of the publication of wait time information on wait times. Multivariate logistical regression was used to test whether or not individual patients used published wait time to decide which site to visit. We found that the rates of wait times exceeding 4 h, and the 95th percentile of wait times in the two sites decreased after the publication of wait time information, even though the average wait times experienced a slight increase. We also found that after controlling for other factors, the site with shorter wait time had a higher likelihood of being selected after the publication of wait time information, but there was no such relationship before the publication. These findings were consistent with the hypothesis that the publication of wait time information leads to patients selecting the site with shorter wait time. While publishing ED wait time information did not improve average wait time, it reduced the rates of lengthy wait times.

  1. [Reducing patient waiting time for the outpatient phlebotomy service using six sigma].

    Science.gov (United States)

    Kim, Yu Kyung; Song, Kyung Eun; Lee, Won Kil

    2009-04-01

    One of the challenging issues of the outpatient phlebotomy services at most hospitals is that patients have a long wait. The outpatient phlebotomy team of Kyungpook National University Hospital applied six sigma breakthrough methodologies to reduce the patient waiting time. The DMAIC (Define, Measure, Analyze, Improve, and Control) model was employed to approach the project. Two hundred patients visiting the outpatient phlebotomy section were asked to answer the questionnaires at inception of the study to ascertain root causes. After correction, we surveyed 285 patients for same questionnaires again to follow-up the effects. A defect was defined as extending patient waiting time so long and at the beginning of the project, the performance level was 2.61 sigma. Using fishbone diagram, all the possible reasons for extending patient waiting time were captured, and among them, 16 causes were proven to be statistically significant. Improvement plans including a new receptionist, automatic specimen transport system, and adding one phlebotomist were put into practice. As a result, the number of patients waited more than 5 min significantly decreased, and the performance level reached 3.0 sigma in December 2007 and finally 3.35 sigma in July 2008. Applying the six sigma, the performance level of waiting times for blood drawing exceeding five minutes were improved from 2.61 sigma to 3.35 sigma.

  2. Emergency department waiting times: Do the raw data tell the whole story?

    Science.gov (United States)

    Green, Janette; Dawber, James; Masso, Malcolm; Eagar, Kathy

    2014-02-01

    To determine whether there are real differences in emergency department (ED) performance between Australian states and territories. Cross-sectional analysis of 2009-10 attendances at an ED contributing to the Australian non-admitted patient ED care database. The main outcome measure was difference in waiting time across triage categories. There were more than 5.8 million ED attendances. Raw ED waiting times varied by a range of factors including jurisdiction, triage category, geographic location and hospital peer group. All variables were significant in a model designed to test the effect of jurisdiction on ED waiting times, including triage category, hospital peer group, patient socioeconomic status and patient remoteness. When the interaction between triage category and jurisdiction entered the model, it was found to have a significant effect on ED waiting times (P<0.001) and triage was also significant (P<0.001). Jurisdiction was no longer statistically significant (P=0.248 using all triage categories and 0.063 using only Australian Triage Scale 2 and 3). Although the Council of Australian Governments has adopted raw measures for its key ED performance indicators, raw waiting time statistics are misleading. There are no consistent differences in ED waiting times between states and territories after other factors are accounted for. WHAT IS KNOWN ABOUT THE TOPIC? The length of time patients wait to be treated after presenting at an ED is routinely used to measure ED performance. In national health agreements with the federal government, each state and territory in Australia is expected to meet waiting time performance targets for the five ED triage categories. The raw data indicate differences in performance between states and territories. WHAT DOES THIS PAPER ADD? Measuring ED performance using raw data gives misleading results. There are no consistent differences in ED waiting times between the states and territories after other factors are taken into account

  3. List and liver transplant survival according to waiting time in patients with hepatocellular carcinoma.

    Science.gov (United States)

    Salvalaggio, P R; Felga, G; Axelrod, D A; Della Guardia, B; Almeida, M D; Rezende, M B

    2015-03-01

    The time that patients with hepatocellular carcinoma (HCC) can safely remain on the waiting list for liver transplantation (LT) is unknown. We investigated whether waiting time on the list impacts transplant survival of HCC candidates and transplant recipients. This is a single-center retrospective study of 283 adults with HCC. Patients were divided in groups according to waiting-list time. The main endpoint was survival. The median waiting time for LT was 4.9 months. The dropout rates at 3-, 6-, and 12-months were 6.4%, 12.4%, and 17.7%, respectively. Mortality on the list was 4.8%, but varied depending of the time on the list. Patients who waited less than 3-months had an inferior overall survival when compared to the other groups (p = 0.027). Prolonged time on the list significantly reduced mortality in this analysis (p = 0.02, HR = 0.28). Model for End Stage Liver Disease (MELD) score at transplantation did also independently impact overall survival (p = 0.03, HR = 1.06). MELD was the only factor that independently impacted posttransplant survival (p = 0.048, HR = 1.05). We conclude that waiting time had no relation with posttransplant survival. It is beneficial to prolong the waiting list time for HCC candidates without having a negative impact in posttransplant survival. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

  4. Radiotherapy waiting times for women with breast cancer: a population-based cohort study.

    Science.gov (United States)

    Jack, Ruth H; Davies, Elizabeth A; Robinson, David; Sainsbury, Richard; Møller, Henrik

    2007-05-01

    Waiting times for cancer patients are a national priority in the UK. Previous studies have shown variation between cancer networks in the time between diagnosis and start of radiotherapy for all cancer patients. Studies of the relationship between delay in receiving treatment and survival of breast cancer patients have been inconsistent. This study aimed to examine factors associated with waiting times for radiotherapy for breast cancer patients. 35,354 women resident in South East England and diagnosed with breast cancer between 1992 and 2001 who received radiotherapy within six months of diagnosis were identified from the Thames Cancer Registry. Time to radiotherapy was measured from either the date of diagnosis or the start of the previous treatment, whichever was shorter. Unadjusted and adjusted logistic regression models were fitted to examine whether patients received radiotherapy within 60 days of their diagnosis or previous treatment. The adjusted proportions of patients receiving radiotherapy within 60 days varied significantly between different cancer networks (range: 43% to 81%), and decreased from 68% in 1992 to 33% in 2001. After adjustment there was no association between deprivation of area of residence, age or stage and radiotherapy wait. Median time waited to radiotherapy increased over the study period whether measured from the start of chemotherapy, hormone therapy, surgery or the date of diagnosis. This study covered a period of time before the investment following the Cancer Plan of 2000. Results are consistent with other findings suggesting variation between cancer networks and increasing waits over time. Further studies should examine different methods of measuring waiting time, the causes and consequences of waits for radiotherapy and the effect of current initiatives and investments.

  5. Radiotherapy waiting times for women with breast cancer: a population-based cohort study

    Directory of Open Access Journals (Sweden)

    Sainsbury Richard

    2007-05-01

    Full Text Available Abstract Background Waiting times for cancer patients are a national priority in the UK. Previous studies have shown variation between cancer networks in the time between diagnosis and start of radiotherapy for all cancer patients. Studies of the relationship between delay in receiving treatment and survival of breast cancer patients have been inconsistent. This study aimed to examine factors associated with waiting times for radiotherapy for breast cancer patients. Methods 35,354 women resident in South East England and diagnosed with breast cancer between 1992 and 2001 who received radiotherapy within six months of diagnosis were identified from the Thames Cancer Registry. Time to radiotherapy was measured from either the date of diagnosis or the start of the previous treatment, whichever was shorter. Unadjusted and adjusted logistic regression models were fitted to examine whether patients received radiotherapy within 60 days of their diagnosis or previous treatment. Results The adjusted proportions of patients receiving radiotherapy within 60 days varied significantly between different cancer networks (range: 43% to 81%, and decreased from 68% in 1992 to 33% in 2001. After adjustment there was no association between deprivation of area of residence, age or stage and radiotherapy wait. Median time waited to radiotherapy increased over the study period whether measured from the start of chemotherapy, hormone therapy, surgery or the date of diagnosis. Conclusion This study covered a period of time before the investment following the Cancer Plan of 2000. Results are consistent with other findings suggesting variation between cancer networks and increasing waits over time. Further studies should examine different methods of measuring waiting time, the causes and consequences of waits for radiotherapy and the effect of current initiatives and investments.

  6. Waiting times for cancer patients in Sweden: A nationwide population-based study.

    Science.gov (United States)

    Robertson, Stephanie; Adolfsson, Jan; Stattin, Pär; Sjövall, Annika; Winnersjö, Rocio; Hanning, Marianne; Sandelin, Kerstin

    2017-05-01

    The reported long waiting times for cancer patients have mostly been related to prognostic outcome and less to patient-related experience to outcome. We assessed waiting times for patients with cancer of the breast, prostate, colon or rectum in Sweden. The median time from referral to start of treatment was assessed using data from clinical cancer registers for patients who received curative treatment during 2011, 2012 and 2013. The median overall waiting time in different counties ranged from 7 to 28 days for breast cancer, from 117 to 280 days for prostate cancer, from 27 to 64 days for colon cancer and from 48 to 80 days for rectal cancer. For the entire nation, the median time from referral to start of treatment remained unchanged from 2011 to 2013 for each cancer diagnosis. Large variations were found in waiting times between different counties in Sweden and between different types of cancer. The long waiting times identified in this study emphasize the need to improve national programmes for more rapid diagnosis and treatment.

  7. The 2012 SAGE wait times program: Survey of Access to GastroEnterology in Canada

    Science.gov (United States)

    Leddin, Desmond; Armstrong, David; Borgaonkar, Mark; Bridges, Ronald J; Fallone, Carlo A; Telford, Jennifer J; Chen, Ying; Colacino, Palma; Sinclair, Paul

    2013-01-01

    BACKGROUND: Periodically surveying wait times for specialist health services in Canada captures current data and enables comparisons with previous surveys to identify changes over time. METHODS: During one week in April 2012, Canadian gastroenterologists were asked to complete a questionnaire (online or by fax) recording demographics, reason for referral, and dates of referral and specialist visits for at least 10 consecutive new patients (five consultations and five procedures) who had not been seen previously for the same indication. Wait times were determined for 18 indications and compared with those from similar surveys conducted in 2008 and 2005. RESULTS: Data regarding adult patients were provided by 173 gastroenterologists for 1374 consultations, 540 procedures and 293 same-day consultations and procedures. Nationally, the median wait times were 92 days (95% CI 85 days to 100 days) from referral to consultation, 55 days (95% CI 50 days to 61 days) from consultation to procedure and 155 days (95% CI 142 days to 175 days) (total) from referral to procedure. Overall, wait times were longer in 2012 than in 2005 (Pgastroenterology services continue to exceed recommended targets, remain unchanged since 2008 and exceed wait times reported in 2005. PMID:23472243

  8. In the queue for coronary artery bypass grafting: patients' perceptions of risk and 'maximal acceptable waiting time'.

    Science.gov (United States)

    Llewellyn-Thomas, H; Thiel, E; Paterson, M; Naylor, D

    1999-04-01

    To elicit patients' maximal acceptable waiting times (MAWT) for non-urgent coronary artery bypass grafting (CABG), and to determine if MAWT is related to prior expectations of waiting times, symptom burden, expected relief, or perceived risks of myocardial infarction while waiting. Seventy-two patients on an elective CABG waiting list chose between two hypothetical but plausible options: a 1-month wait with 2% risk of surgical mortality, and a 6-month wait with 1% risk of surgical mortality. Waiting time in the 6-month option was varied up if respondents chose the 6-month/lower risk option, and down if they chose the 1-month/higher risk option, until the MAWT switch point was reached. Patients also reported their expected waiting time, perceived risks of myocardial infarction while waiting, current function, expected functional improvement and the value of that improvement. Only 17 (24%) patients chose the 6-month/1% risk option, while 55 (76%) chose the 1-month/2% risk option. The median MAWT was 2 months; scores ranged from 1 to 12 months (with two outliers). Many perceived high cumulative risks of myocardial infarction if waiting for 1 (upper quartile, > or = 1.45%) or 6 (upper quartile, > or = 10%) months. However, MAWT scores were related only to expected waiting time (r = 0.47; P queue. These results suggest a need for interventions to modify patients' inaccurate risk perceptions, particularly if a scheduled surgical date must be deferred.

  9. Intake of wine, beer and spirits and waiting time to pregnancy

    DEFF Research Database (Denmark)

    Juhl, Mette; Olsen, Jørn; Andersen, Anne-Marie Nybo

    2003-01-01

    ,844 pregnant women, recruited to the Danish National Birth Cohort in 1997-2000. Main outcome measures were odds ratios for a prolonged waiting time to pregnancy according to consumption of wine, beer and spirits. RESULTS: All levels of wine intake compared with non-wine drinking or with consumption of beer...... appear to have fewer strokes, lung and digestive tract cancers, and overall mortality than both abstainers and moderate drinkers of beer or spirits. We examined the association between different types of alcoholic beverages and waiting time to pregnancy. METHODS: Self-reported data were used for 29...... or spirits had subfecundity odds ratios between 0.7 and 0.9. No association was seen regarding beer drinking, while the association with spirits was J-shaped. CONCLUSION: Our findings suggest that wine drinkers have slightly shorter waiting times to pregnancy than both non-wine drinkers and consumers...

  10. Interventions to reduce wait times for primary care appointments: a systematic review.

    Science.gov (United States)

    Ansell, Dominique; Crispo, James A G; Simard, Benjamin; Bjerre, Lise M

    2017-04-20

    Accessibility and availability are important characteristics of efficient and effective primary healthcare systems. Currently, timely access to a family physician is a concern in Canada. Adverse outcomes are associated with longer wait times for primary care appointments and often leave individuals to rely on urgent care. When wait times for appointments are too long patients may experience worse health outcomes and are often left to use emergency department resources. The primary objective of our study was to systematically review the literature to identify interventions designed to reduce wait times for primary care appointments. Secondary objectives were to assess patient satisfaction and reduction of no-show rates. We searched multiple databases, including: Medline via Ovid SP (1947 to present), Embase (from 1980 to present), PsychINFO (from 1806 to present), Cochrane Central Register of Controlled Trials (CENTRAL; all dates), Cumulative Index to Nursing and Allied Health (CINAHL; 1937 to present), and Pubmed (all dates) to identify studies that reported outcomes associated with interventions designed to reduce wait times for primary care appointments. Two independent reviewers assessed all identified studies for inclusion using pre-defined inclusion/exclusion criteria and a multi-level screening approach. Our study methods were guided by the Cochrane Handbook for Systematic Reviews of Interventions. Our search identified 3,960 articles that were eligible for inclusion, eleven of which satisfied all inclusion/exclusion criteria. Data abstraction of included studies revealed that open access scheduling is the most commonly used intervention to reduce wait times for primary care appointments. Additionally, included studies demonstrated that dedicated telephone calls for follow-up consultation, presence of nurse practitioners on staff, nurse and general practitioner triage, and email consultations were effective at reducing wait times. To our knowledge, this is

  11. Appoximation Formula for Estimation of Waiting-Time in Multiple-Channel Queuing Systems

    DEFF Research Database (Denmark)

    Maaløe, Erik

    1973-01-01

    The article deals with two approxiamation formulae for estimation of W, Waiting-times in a M/E/R queuing system.m First is shown how W for the multiple-channel system is approximately an Rth part of the mean waiting time in a single channel system. A second approximation applies the exact ratio...... for W(multi-channel/W(single channel) and M/M/1-systems to general M/Ek/R-systems. This is particularly illustrated in the case og M/M/R and M/D/R-systems as a general warning against general practices...

  12. Wait Time and Service Satisfaction at the Outpatient Clinic of a ...

    African Journals Online (AJOL)

    Background: In February 2006, Neuropsychiatric Hospital, Aro, Abeokuta launched the local charter of SERVICOM and promised the clients timely and quality services delivered with fairness, honesty, courtesy, and transparency. Implementation of this promise is yet to be evaluated. Objectives: To determine the wait time ...

  13. Patterns for the waiting time in the context of discrete-time stochastic processes.

    Science.gov (United States)

    Jamali, Tayeb; Jafari, G R; Vasheghani Farahani, S

    2016-09-01

    The aim of this study is to extend the scope and applicability of the level-crossing method to discrete-time stochastic processes and generalize it to enable us to study multiple discrete-time stochastic processes. In previous versions of the level-crossing method, problems with it correspond to the fact that this method had been developed for analyzing a continuous-time process or at most a multiple continuous-time process in an individual manner. However, since all empirical processes are discrete in time, the already-established level-crossing method may not prove adequate for studying empirical processes. Beyond this, due to the fact that most empirical processes are coupled; their individual study could lead to vague results. To achieve the objectives of this study, we first find an analytical expression for the average frequency of crossing a level in a discrete-time process, giving the measure of the time experienced for two consecutive crossings named as the "waiting time." We then introduce the generalized level-crossing method by which the consideration of coupling between the components of a multiple process becomes possible. Finally, we provide an analytic solution when the components of a multiple stochastic process are independent Gaussian white noises. The comparison of the results obtained for coupled and uncoupled processes measures the strength and efficiency of the coupling, justifying our model and analysis. The advantage of the proposed method is its sensitivity to the slightest coupling and shortest correlation length.

  14. Spatial structure increases the waiting time for cancer

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Kostadinov, Rumen; Maley, Carlo C

    2011-01-01

    epithelial tissues. In this study, we propose a novel model of cancer progression that considers a spatially structured cell population where clones expand via adaptive waves. This model is used to asses two different paradigms of asexual evolution that have been suggested to delineate the process of cancer...... progression. The standard scenario of periodic selection assumes that driver mutations are accumulated strictly sequentially over time. However, when the mutation supply is sufficiently high, clones may arise simultaneously on distinct genetic backgrounds, and clonal adaptation waves interfere with each other......Cancer results from a sequence of genetic and epigenetic changes which lead to a variety of abnormal phenotypes including increased proliferation and survival of somatic cells, and thus, to a selective advantage of pre-cancerous cells. The notion of cancer progression as an evolutionary process has...

  15. Access to specialist gastroenterology care in Canada: Comparison of wait times and consensus targets

    Science.gov (United States)

    Leddin, Desmond; Armstrong, David; Barkun, Alan NG; Chen, Ying; Daniels, Sandra; Hollingworth, Roger; Hunt, Richard H; Paterson, William G

    2008-01-01

    BACKGROUND: Monitoring wait times and defining targets for care have been advocated to improve health care delivery related to cancer, heart, diagnostic imaging, joint replacements and sight restoration. There are few data on access to care for digestive diseases, although they pose a greater economic burden than cancer or heart disease in Canada. The present study compared wait times for specialist gastroenterology care with recent, evidence-based, consensus-defined benchmark wait times for a range of digestive diseases. METHODS: Total wait times from primary care referral to investigation were measured for seven digestive disease indications by using the Practice Audit in Gastroenterology program, and were benchmarked against consensus recommendations. RESULTS: Total wait times for 1903 patients who were undergoing investigation exceeded targets for those with probable cancer (median 26 days [25th to 75th percentiles eight to 56 days] versus target of two weeks); probable inflammatory bowel disease (101 days [35 to 209 days] versus two weeks); documented iron deficiency anemia (71 days [19 to 142 days] versus two months); positive fecal occult blood test (73 days [36 to 148 days] versus two months); dyspepsia with alarm symptoms (60 days [23 to 140 days] versus two months); refractory dyspepsia without alarm symptoms (126 days [42 to 225 days] versus two months); and chronic constipation and diarrhea (141 days [68 to 264 days] versus two months). A minority of patients were seen within target times: probable cancer (33% [95% CI 20% to 47%]); probable inflammatory bowel disease (12% [95% CI 1% to 23%]); iron deficiency anemia (46% [95% CI 37% to 55%]); positive occult blood test (41% [95% CI 28% to 54%]); dyspepsia with alarm symptoms (51% [95% CI 41% to 60%]); refractory dyspepsia without alarm symptoms (33% [95% CI 19% to 47%]); and chronic constipation and diarrhea (21% [95% CI 14% to 29%]). DISCUSSION: Total wait times for the seven indications exceeded the

  16. Patients\\' response to waiting time in an out-patient pharmacy in ...

    African Journals Online (AJOL)

    Purpose: To identify the dispensing procedure at a pharmacy, investigate the possible operational problems that may lead to excessive patient waiting times as prescriptions are filled and to examine patient disposition to perceived delays at the pharmacy. Methods: The study was carried out in a 574-bed university teaching ...

  17. Wait watchers. Smart organizations are demonstrating that while they can't erase ED wait times, they can leverage technology to keep patients better informed.

    Science.gov (United States)

    Gamble, Kate Huvane

    2010-04-01

    Increases in ED visits are significantly affecting patient access, quality, cost and care management--a trend that is expected to continue. A number of organizations are dealing with the increased demand for services by implementing technologies to keep patients better informed of wait times. Publishing ED wait times online offers hospitals a way to communicate information to patients quickly without requiring a significant investment from the IT staff. Hospitals are also utilizing visibility boards to keep both patients and staff updated on patient conditions and room status.

  18. Assessing the impact of a waiting time survey on reducing waiting times in urban primary care clinics in Cape Town, South Africa

    Directory of Open Access Journals (Sweden)

    Johann Daniels

    2017-09-01

    Full Text Available A waiting time survey (WTS conducted in several clinics in Cape Town, South Africa provided recommendations on how to shorten waiting times (WT. A follow-up study was conducted to assess whether WT had reduced. Using a stratified sample of 22 clinics, a before and after study design assessed changes in WT. The WT was measured and perceptions of clinic managers were elicited, about the previous survey’s recommendations. The overall median WT decreased by 21 minutes (95%CI: 11.77- 30.23, a 28% decrease from the previous WTS. Although no specific factor was associated with decreases in WT, implementation of recommendations to reduce WT was 2.67 times (95%CI: 1.33-5.40 more likely amongst those who received written recommendations and 2.3 times (95%CI: 1.28- 4.19 more likely amongst managers with 5 or more years’ experience. The decrease in WT found demonstrates the utility of a WTS in busy urban clinics in developing country contexts. Experienced facility managers who timeously receive customised reports of their clinic’s performance are more likely to implement changes that positively impact on reducing WT.

  19. Application of Queueing Theory to the Analysis of Changes in Outpatients' Waiting Times in Hospitals Introducing EMR.

    Science.gov (United States)

    Cho, Kyoung Won; Kim, Seong Min; Chae, Young Moon; Song, Yong Uk

    2017-01-01

    This research used queueing theory to analyze changes in outpatients' waiting times before and after the introduction of Electronic Medical Record (EMR) systems. We focused on the exact drawing of two fundamental parameters for queueing analysis, arrival rate (λ) and service rate (µ), from digital data to apply queueing theory to the analysis of outpatients' waiting times. We used outpatients' reception times and consultation finish times to calculate the arrival and service rates, respectively. Using queueing theory, we could calculate waiting time excluding distorted values from the digital data and distortion factors, such as arrival before the hospital open time, which occurs frequently in the initial stage of a queueing system. We analyzed changes in outpatients' waiting times before and after the introduction of EMR using the methodology proposed in this paper, and found that the outpatients' waiting time decreases after the introduction of EMR. More specifically, the outpatients' waiting times in the target public hospitals have decreased by rates in the range between 44% and 78%. It is possible to analyze waiting times while minimizing input errors and limitations influencing consultation procedures if we use digital data and apply the queueing theory. Our results verify that the introduction of EMR contributes to the improvement of patient services by decreasing outpatients' waiting time, or by increasing efficiency. It is also expected that our methodology or its expansion could contribute to the improvement of hospital service by assisting the identification and resolution of bottlenecks in the outpatient consultation process.

  20. Evaluating Distributed Timing Constraints

    DEFF Research Database (Denmark)

    Kristensen, C.H.; Drejer, N.

    1994-01-01

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

  1. Decreasing laboratory turnaround time and patient wait time by implementing process improvement methodologies in an outpatient oncology infusion unit.

    Science.gov (United States)

    Gjolaj, Lauren N; Gari, Gloria A; Olier-Pino, Angela I; Garcia, Juan D; Fernandez, Gustavo L

    2014-11-01

    Prolonged patient wait times in the outpatient oncology infusion unit indicated a need to streamline phlebotomy processes by using existing resources to decrease laboratory turnaround time and improve patient wait time. Using the DMAIC (define, measure, analyze, improve, control) method, a project to streamline phlebotomy processes within the outpatient oncology infusion unit in an academic Comprehensive Cancer Center known as the Comprehensive Treatment Unit (CTU) was completed. Laboratory turnaround time for patients who needed same-day lab and CTU services and wait time for all CTU patients was tracked for 9 weeks. During the pilot, the wait time from arrival to CTU to sitting in treatment area decreased by 17% for all patients treated in the CTU during the pilot. A total of 528 patients were seen at the CTU phlebotomy location, representing 16% of the total patients who received treatment in the CTU, with a mean turnaround time of 24 minutes compared with a baseline turnaround time of 51 minutes. Streamlining workflows and placing a phlebotomy station inside of the CTU decreased laboratory turnaround times by 53% for patients requiring same day lab and CTU services. The success of the pilot project prompted the team to make the station a permanent fixture. Copyright © 2014 by American Society of Clinical Oncology.

  2. Using administrative databases to measure waiting times for patients undergoing major cancer surgery in Ontario, 1993-2000.

    Science.gov (United States)

    Simunovic, Marko; Thériault, Marc-Erick; Paszat, Lawrence; Coates, Angela; Whelan, Timothy; Holowaty, Eric; Levine, Mark

    2005-04-01

    To determine how long patients in Ontario waited for major breast, colorectal, lung or prostate cancer surgery in the years 1993-2000. "Surgical waiting time" was defined as the interval from date of preoperative surgeon consult to date of hospital admission for surgery. We created patient cohorts by linking appropriate diagnosis and procedure codes from Canadian Institutes of Health Information data. Scrambled unique surgeon identifiers were obtained from Ontario Health Insurance Plan data. Changes in median surgical waiting times were assessed with univariate time-trend analyses and multilevel models. Models were controlled for year of surgery and other patient (age, gender, comorbid conditions, income level, area of residence) and hospital level characteristics (teaching status, procedure volume status). Compared with 1993, median surgical waiting times in the year 2000 increased 36% for patients with breast cancer (to 19 d), 46% with colorectal (to 19 d), 36% with lung (to 34 d) and 4% with prostate cancer (to 83 d). Multilevel models confirmed significant increases in waiting times for all procedures. There were no concerning or consistent differences in waiting times among the categories of hospitals and patients examined. There were significant increases in surgical waiting times among patients undergoing breast, colorectal, lung or prostate cancer surgery in Ontario over years 1993-2000. Administrative databases can be used to efficiently measure such waits.

  3. Determinants of treatment waiting times for head and neck cancer in the Netherlands and their relation to survival.

    Science.gov (United States)

    van Harten, Michel C; Hoebers, Frank J P; Kross, Kenneth W; van Werkhoven, Erik D; van den Brekel, Michiel W M; van Dijk, Boukje A C

    2015-03-01

    Waiting to start treatment has been shown to be associated with tumor progression and upstaging in head and neck squamous cell carcinomas (HNSCCs). This diminishes the chance of cure and might lead to unnecessary mortality. We investigated the association between waiting times and survival in the Netherlands and assessed which factors were associated to longer waiting times. Patient (age, sex, socioeconomic status (SES), tumor (site, stage) and treatment (type, of institute of diagnosis/treatment) characteristics for patients with HNSCC who underwent treatment were extracted from the Netherlands Cancer Registry (NCR) for 2005-2011. Waiting time was defined as the number of days between histopathological diagnosis and start of treatment. Univariable and multivariable Cox regression was used to evaluate survival. In total, 13,140 patients were included, who had a median waiting time of 37days. Patients who were more likely to wait longer were men, patients with a low SES, oropharynx tumors, stage IV tumors, patients to be treated with radiotherapy or chemoradiation, and patients referred for treatment to a Head and Neck Oncology Center (HNOC) from another hospital. The 5-year overall survival was 58% for all patients. Our multivariable Cox regression model showed that longer waiting time, was significantly related to a higher hazard of dying (p<0.0001). This is the first large population-based study showing that longer waiting time for surgery, radiotherapy or chemoradiation is a significant negative prognostic factor for HNSCC patients. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Specific timely appointments for triage reduced waiting lists in an outpatient physiotherapy service.

    Science.gov (United States)

    Harding, K E; Bottrell, J

    2016-12-01

    Waiting lists with triage systems are commonly used in outpatient physiotherapy but may not be effective. Could an alternative model of access and triage reduce waiting times over a sustained period with no additional resources? Observational study comparing retrospective data for 11 months prior to the introduction of a new model of access compared with data for the equivalent 11 months afterwards. Patients referred to a physiotherapy outpatient department at an outer metropolitan hospital before (n=721) and after (n=707) the introduction of the new model. A model of access and triage known as 'specific timely appointments for triage' (STAT), in which appointment slots are preserved in advance specifically for new patients based on calculation of average demand. Time from referral to first assessment, number of appointments per patient, occasions of non-attendance and total length of stay in the service. Median time from referral to first appointment was 18 days [interquartile range (IQR) 11 to 33 days] in the pre-intervention group, compared with 14 days (IQR 9 to 21 days) in the post-intervention group (Pphysiotherapy appointments also reduced (IQR 2 to 6 vs IQR 1 to 4; Pphysiotherapy was 22% lower in the year following the introduction of the STAT model. While acknowledging the limitations of a pre- and post-measurement design, this model may have potential for reducing waiting times for outpatient physiotherapy without additional resources. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  5. The influence of deterministic and stochastic waiting time for triggering mortality and colonization events on the coexistence of cooperators and defectors in an evolutionary game model

    Directory of Open Access Journals (Sweden)

    YouHua Chen

    2014-06-01

    Full Text Available In the present report, the coexistence of Prisoners' Dilemma game players (cooperators and defectors were explored in an individual-based framework with the consideration of the impacts of deterministic and stochastic waiting time (WT for triggering mortality and/or colonization events. For the type of deterministic waiting time, the time step for triggering a mortality and/or colonization event is fixed. For the type of stochastic waiting time, whether a mortality and/or colonization event should be triggered for each time step of a simulation is randomly determined by a given acceptance probability (the event takes place when a variate drawn from a uniform distribution [0,1] is smaller than the acceptance probability. The two strategies of modeling waiting time are considered simultaneously and applied to both quantities (mortality: WTm, colonization: WTc. As such, when WT (WTm and/or WTc is an integral >=1, it indicated a deterministically triggering strategy. In contrast, when 1>WT>0, it indicated a stochastically triggering strategy and the WT value itself is used as the acceptance probability. The parameter space between the waiting time for mortality (WTm-[0.1,40] and colonization (WTc-[0.1,40] was traversed to explore the coexistence and non-coexistence regions. The role of defense award was evaluated. My results showed that, one non-coexistence region is identified consistently, located at the area where 1>=WTm>=0.3 and 40>=WTc>=0.1. As a consequence, it was found that the coexistence of cooperators and defectors in the community is largely dependent on the waiting time of mortality events, regardless of the defense or cooperation rewards. When the mortality events happen in terms of stochastic waiting time (1>=WTm>=0.3, extinction of either cooperators or defectors or both could be very likely, leading to the emergence of non-coexistence scenarios. However, when the mortality events occur in forms of relatively long deterministic

  6. [Patients' satisfaction and waiting time in oncology day care centers in Champagne-Ardenne].

    Science.gov (United States)

    Debreuve-Theresette, A; Jovenin, N; Stona, A C; Kraïem-Leleu, M; Burde, F; Parent, D; Hettler, D; Rey, J B

    2015-12-01

    Quality of life of patients suffering from cancer may be influenced by the way healthcare is organized and by patient experiences. Nowadays, chemotherapy is often provided in day care centers. This study aimed to assess patient waiting time and satisfaction in oncology day care centers in Champagne-Ardenne, France. This cross-sectional survey involved all patients receiving ambulatory chemotherapy during a one-week period in day care centers of Champagne-Ardenne public and private healthcare institutions participating in the study. Sociodemographic, medical and outpatient data were collected. Patient satisfaction was measured using the Out-Patsat35 questionnaire. Eleven (out of 16) oncology day care centers and 441 patients participated in the study. Most of the patients were women (n=252, 57.1%) and the mean age was 61±12 years. The mean satisfaction score was 82±14 (out of 100) and the mean waiting time between the assigned appointment time and administration of chemotherapy was 97±60 min. This study has shown that waiting times are important. However, patients are satisfied with the healthcare organization, especially regarding nursing support. Early preparation of chemotherapy could improve these parameters. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  7. How do Patients Trade-Off Surgeon Choice and Waiting Times for Total Joint Replacement: A Discrete Choice Experiment.

    Science.gov (United States)

    Marshall, Deborah A; Deal, Ken; Conner-Spady, Barbara; Bohm, Eric; Hawker, Gillian; Loucks, Lynda; MacDonald, Karen V; Noseworthy, Tom

    2018-02-06

    Patients face significant waiting times for hip and knee total joint replacement (TJR) in publicly funded healthcare systems. We aimed to assess how surgeon selection and reputation affect patients' willingness to wait for TJR. We assessed patient preferences using a discrete choice experiment questionnaire with 12 choice scenarios administered to patients referred for TJR. Based on qualitative research, pre- and pilot-testing, we characterized each scenario by five attributes: surgeon reputation, surgeon selection, waiting time to surgeon visit (initial consultation), waiting time to surgery, and travel time to hospital. Preferences were assessed using hierarchical Bayes analysis and evaluated for goodness-of-fit. We conducted simulation analyses to understand how patients value surgeon reputation and surgeon selection in terms of willingness to wait for surgeon visit and surgery. Of 422 participants, 68% were referred for knee TJR. The most important attribute was surgeon reputation followed by waiting times, surgeon selection process and travel time. Patients appear willing to wait 10 months for a visit with an excellent reputation surgeon before switching to a good reputation surgeon. Patients in the highest pain category were willing to wait 7.3 months before accepting the next available surgeon, compared to 12 months for patients experiencing the least pain. Our findings confirm that patients value surgeon reputation in the context of wait times and surgeon selection. We suggest opportunities to reduce wait times by explicitly offering the next available surgeon to increase patient choice, and by reporting surgeon performance to reduce potential misinformation about reputation. Copyright © 2018 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  8. A marketing perspective on the influences of waiting time and servicescape on perceived value

    OpenAIRE

    Costinel DOBRE; Anca Cristina DRAGOMIR; Anca-Maria MILOVAN-CIUTA

    2013-01-01

    Customer’s value perception of products and services is a variable with important implications on the marketing performance of the organizations. In this article we intend to analyse influences of waiting time and servicescape perception on the perceived value of customers of a dental clinic. The empirical research carried out for the elaboration of this article is part of a wider research concerning the multidimensional approach of the service value perceived by clients. Survey findings show...

  9. A Scheduling Method to Reduce Waiting Time for Close-Range Broadcasting

    Directory of Open Access Journals (Sweden)

    Yusuke Gotoh

    2012-01-01

    Full Text Available Due to the recent popularization of digital broadcasting systems, close-range broadcasting using continuous media data, i.e. audio and video, has attracted great attention. For example, in a drama, after a user watches interesting content such as a highlight scene, he/she will watch the main program continuously. In close-range broadcasting, the necessary bandwidth for continuously playing the two types of data increases. Conventional methods reduce the necessary bandwidth by producing an effective broadcast schedule for continuous media data. However, these methods do not consider the broadcast schedule for two types of continuous media data. When the server schedules two types of continuous media data, waiting time that occurs from finishing the highlight scene to starting the main scene, may increase. In this paper, we propose a scheduling method to reduce the waiting time for close-range broadcasting. In our proposed method, by dividing two types of data and producing an effective broadcast schedule considering the available bandwidth, we can reduce the waiting time.

  10. Act-and-wait time-delayed feedback control of autonomous systems

    Science.gov (United States)

    Pyragas, Viktoras; Pyragas, Kestutis

    2018-02-01

    Recently an act-and-wait modification of time-delayed feedback control has been proposed for the stabilization of unstable periodic orbits in nonautonomous dynamical systems (Pyragas and Pyragas, 2016 [30]). The modification implies a periodic switching of the feedback gain and makes the closed-loop system finite-dimensional. Here we extend this modification to autonomous systems. In order to keep constant the phase difference between the controlled orbit and the act-and-wait switching function an additional small-amplitude periodic perturbation is introduced. The algorithm can stabilize periodic orbits with an odd number of real unstable Floquet exponents using a simple single-input single-output constraint control.

  11. A Cross-Sectional Survey of Population-Wide Wait Times for Patients Seeking Medical vs. Cosmetic Dermatologic Care.

    Science.gov (United States)

    Yadav, Geeta; Goldberg, Hanna R; Barense, Morgan D; Bell, Chaim M

    2016-01-01

    Though previous work has examined some aspects of the dermatology workforce shortage and access to dermatologic care, little research has addressed the effect of rising interest in cosmetic procedures on access to medical dermatologic care. Our objective was to determine the wait times for Urgent and Non-Urgent medical dermatologic care and Cosmetic dermatology services at a population level and to examine whether wait times for medical care are affected by offering cosmetic services. A population-wide survey of dermatology practices using simulated calls asking for the earliest appointment for a Non-Urgent, Urgent and Cosmetic service. Response rates were greater than 89% for all types of care. Wait times across all types of care were significantly different from each other (all P Cosmetic care was associated with the shortest wait times (3.0 weeks; Interquartile Range (IQR) = 0.4-3.4), followed by Urgent care (9.0 weeks; IQR = 2.1-12.9), then Non-Urgent Care (12.7 weeks; IQR = 4.4-16.4). Wait times for practices offering only Urgent care were not different from practices offering both Urgent and Cosmetic care (10.3 vs. 7.0 weeks). Longer wait times and greater variation for Urgent and Non-Urgent dermatologic care and shorter wait times and less variation for Cosmetic care. Wait times were significantly longer in regions with lower dermatologist density. Provision of Cosmetic services did not increase wait times for Urgent care. These findings suggest an overall dermatology workforce shortage and a need for a more streamlined referral system for dermatologic care.

  12. A model to prioritize access to elective surgery on the basis of clinical urgency and waiting time

    Directory of Open Access Journals (Sweden)

    Santori Gregorio

    2009-01-01

    Full Text Available Abstract Background Prioritization of waiting lists for elective surgery represents a major issue in public systems in view of the fact that patients often suffer from consequences of long waiting times. In addition, administrative and standardized data on waiting lists are generally lacking in Italy, where no detailed national reports are available. This is true although since 2002 the National Government has defined implicit Urgency-Related Groups (URGs associated with Maximum Time Before Treatment (MTBT, similar to the Australian classification. The aim of this paper is to propose a model to manage waiting lists and prioritize admissions to elective surgery. Methods In 2001, the Italian Ministry of Health funded the Surgical Waiting List Info System (SWALIS project, with the aim of experimenting solutions for managing elective surgery waiting lists. The project was split into two phases. In the first project phase, ten surgical units in the largest hospital of the Liguria Region were involved in the design of a pre-admission process model. The model was embedded in a Web based software, adopting Italian URGs with minor modifications. The SWALIS pre-admission process was based on the following steps: 1 urgency assessment into URGs; 2 correspondent assignment of a pre-set MTBT; 3 real time prioritization of every referral on the list, according to urgency and waiting time. In the second project phase a prospective descriptive study was performed, when a single general surgery unit was selected as the deployment and test bed, managing all registrations from March 2004 to March 2007 (1809 ordinary and 597 day cases. From August 2005, once the SWALIS model had been modified, waiting lists were monitored and analyzed, measuring the impact of the model by a set of performance indexes (average waiting time, length of the waiting list and Appropriate Performance Index (API. Results The SWALIS pre-admission model was used for all registrations in the

  13. Wait times and volume of cataract surgery in Ontario: 2000-2012.

    Science.gov (United States)

    Szigiato, Andrei-Alexandru; Trope, Graham E; Jin, Yaping; Buys, Yvonne M

    2016-02-01

    To review cataract surgery trends and wait times in Ontario. Retrospective analysis of health records. Ontario Health Insurance Plan billing service claims between 2000 and 2012 were analyzed for the yearly number of cataract surgeries, alone and in combination with other procedures. The number of Ontarians with cataracts was estimated by applying composite prevalence curves derived from published population data. This was then used to calculate the yearly number of procedures per 1000 Ontarians with cataracts. Per 1000 people with cataract, the rate of cataract extraction increased 18.9% overall from 2000 to 2012, increasing by 38.3% from 2000 to 2006 and decreasing by 14.6% from 2006 to 2012. Mean wait times for cataract surgery decreased by 45.8% from 2006 to 2009 and increased 28.5% from 2009 to 2013. The proportion of surgeries that were same-day bilateral cataract extraction increased 2.21-fold from 2000 to 2012 but represented only 0.82% of total cataract surgeries in 2012. In 2000, 3% of cataract surgeries were combined with other procedures, and this decreased to 1.8% in 2012. Of these combinations, the rates of combined glaucoma filtration procedures decreased by 44.3%, anterior vitrectomy decreased by 32.5%, posterior vitrectomy increased by 58.3%, and corneal transplantation decreased by 10.7% during this time period. The yearly rate of cataract surgery has decreased since 2006, and wait times have increased from 2009. Same-day bilateral cataract extraction represented less than 1% of the total cataract surgical volume. Rates of cataract combined with posterior vitrectomy have increased (58%), whereas anterior vitrectomy at the time of cataract surgery decreased (33%). Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  14. Impact of Lean on patient cycle and waiting times at a rural district hospital in KwaZulu-Natal

    Science.gov (United States)

    Naidoo, Logandran

    2016-01-01

    Background Prolonged waiting time is a source of patient dissatisfaction with health care and is negatively associated with patient satisfaction. Prolonged waiting times in many district hospitals result in many dissatisfied patients, overworked and frustrated staff, and poor quality of care because of the perceived increased workload. Aim The aim of the study was to determine the impact of Lean principles techniques, and tools on the operational efficiency in the outpatient department (OPD) of a rural district hospital. Setting The study was conducted at the Catherine Booth Hospital (CBH) – a rural district hospital in KwaZulu-Natal, South Africa. Methods This was an action research study with pre-, intermediate-, and post-implementation assessments. Cycle and waiting times were measured by direct observation on two occasions before, approximately two-weekly during, and on two occasions after Lean implementation. A standardised data collection tool was completed by the researcher at each of the six key service nodes in the OPD to capture the waiting times and cycle times. Results All six service nodes showed a reduction in cycle times and waiting times between the baseline assessment and post-Lean implementation measurement. Significant reduction was achieved in cycle times (27%; p Consulting Room node, there was a significant reduction in waiting times from 80.95 to 74.43 min, (p post-intervention). Conclusion The application of Lean principles, tools and techniques provides hospital managers with an evidence-based management approach to resolving problems and improving quality indicators. PMID:27543283

  15. Improved functional outcome after hip fracture is associated with duration of rehabilitation, but not with waiting time for rehabilitation

    DEFF Research Database (Denmark)

    Pedersen, Tonny Jaeger; Bogh, Louise Nicole Bie; Lauritsen, Jens Martin

    2017-01-01

    INTRODUCTION: The aim of this study was to explore the relationship between “waiting time to onset of municipal rehabilitation”, “length of municipal rehabilitation” and the attained level of function four months after the hip fracture. METHODS: Among a consecutive series of 156 patients, the 116...... patients who were recommended a municipal rehabilitation sequence after discharge were included. The exposures were waiting time in days and duration in hours of the municipal rehabilitation. The outcome was lower-extremity functional level as measured with the Short Physical Performance Battery. Effects...... were assessed with non-parametric gamma coefficients. RESULTS: The median waiting time to initiation of rehabilitation was ten days. A weak and insignificant correlation was observed between waiting time and outcome at four months, and a statistically significant correlation was recorded between...

  16. Applying the Lean principles of the Toyota Production System to reduce wait times in the emergency department

    National Research Council Canada - National Science Library

    Ng, David; Vail, Gord; Thomas, Sophia; Schmidt, Nicki

    2010-01-01

    ...) without adding any new funding or beds. In 2005 all staff in the ED at Hôtel-Dieu Grace Hospital began a transformation, employing Toyota Lean manufacturing principles to improve ED wait times and quality of care...

  17. ADAPTATION OF JOHNSON SEQUENCING ALGORITHM FOR JOB SCHEDULING TO MINIMISE THE AVERAGE WAITING TIME IN CLOUD COMPUTING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    SOUVIK PAL

    2016-09-01

    Full Text Available Cloud computing is an emerging paradigm of Internet-centric business computing where Cloud Service Providers (CSPs are providing services to the customer according to their needs. The key perception behind cloud computing is on-demand sharing of resources available in the resource pool provided by CSP, which implies new emerging business model. The resources are provisioned when jobs arrive. The job scheduling and minimization of waiting time are the challenging issue in cloud computing. When a large number of jobs are requested, they have to wait for getting allocated to the servers which in turn may increase the queue length and also waiting time. This paper includes system design for implementation which is concerned with Johnson Scheduling Algorithm that provides the optimal sequence. With that sequence, service times can be obtained. The waiting time and queue length can be reduced using queuing model with multi-server and finite capacity which improves the job scheduling model.

  18. Improved functional outcome after hip fracture is associated with duration of rehabilitation, but not with waiting time for rehabilitation

    OpenAIRE

    Pedersen, Tonny Jaeger; Bogh, Louise Nicole Bie; Lauritsen, Jens Martin

    2017-01-01

    INTRODUCTION: The aim of this study was to explore the relationship between “waiting time to onset of municipal rehabilitation”, “length of municipal rehabilitation” and the attained level of function four months after the hip fracture. METHODS: Among a consecutive series of 156 patients, the 116 patients who were recommended a municipal rehabilitation sequence after discharge were included. The exposures were waiting time in days and duration in hours of the municipal rehabilitation. The out...

  19. Transition path time distributions

    Science.gov (United States)

    Laleman, M.; Carlon, E.; Orland, H.

    2017-12-01

    Biomolecular folding, at least in simple systems, can be described as a two state transition in a free energy landscape with two deep wells separated by a high barrier. Transition paths are the short part of the trajectories that cross the barrier. Average transition path times and, recently, their full probability distribution have been measured for several biomolecular systems, e.g., in the folding of nucleic acids or proteins. Motivated by these experiments, we have calculated the full transition path time distribution for a single stochastic particle crossing a parabolic barrier, including inertial terms which were neglected in previous studies. These terms influence the short time scale dynamics of a stochastic system and can be of experimental relevance in view of the short duration of transition paths. We derive the full transition path time distribution as well as the average transition path times and discuss the similarities and differences with the high friction limit.

  20. On the virtual waiting time for an M/G/1 retrial queue with two types of calls

    Directory of Open Access Journals (Sweden)

    Bong Dae Choi

    1993-01-01

    Full Text Available We consider an M/G/1 retrial queueing system with two types of calls which models a telephone switching system. In the case that arriving calls are blocked due to the channel being busy, the outgoing calls are queued in priority group whereas the incoming calls enter the retrial group in order to try service again after a random amount of time. In this paper we find the Laplace-Stieltjes transform of the distribution of the virtual waiting time for an incoming call. When the arrival rate of outgoing calls is zero, it is shown that our result is consistent with the known result for a retrial queueing system with one type of call.

  1. Functional Status, Time to Transplantation, and Survival Benefit of Kidney Transplantation Among Wait-Listed Candidates

    Science.gov (United States)

    Reese, Peter P.; Shults, Justine; Bloom, Roy D.; Mussell, Adam; Harhay, Meera N.; Abt, Peter; Levine, Matthew; Johansen, Kirsten L.; Karlawish, Jason T.; Feldman, Harold I.

    2015-01-01

    Background In the context of an aging end-stage renal disease population with multiple comorbidities, transplantation professionals face challenges in evaluating the global health of patients awaiting kidney transplantation. Functional status might be useful for identifying which patients will derive a survival benefit from transplantation versus dialysis. Study Design Retrospective cohort study of wait-listed patients using data on functional status from a national dialysis provider linked to United Network for Organ Sharing registry data. Setting & Participants Adult kidney transplant candidates added to the waiting list between the years 2000 and 2006. Predictor Physical function scale of the Medical Outcomes Study 36-Item Short Form Healthy Survey, analyzed as a time-varying covariate. Outcomes Kidney transplantation; Survival benefit of transplantation versus remaining wait-listed. Measurements We used multivariable Cox regression to assess the association between physical function with study outcomes. In survival benefit analyses, transplant status was modeled as a time-varying covariate. Results The cohort comprised 19,242 kidney transplant candidates (median age, 51 years; 36% black race) receiving maintenance dialysis. Candidates in the lowest baseline physical function quartile were more likely to be inactivated (adjusted HR vs. highest quartile, 1.30; 95% CI, 1.21-1.39) and less likely to undergo transplantation (adjusted HR vs. highest quartile, 0.64; 95% CI, 0.61-0.68). After transplantation, worse physical function was associated with shorter 3-year survival (84% vs. 92% for the lowest vs. highest function quartiles). However, compared to dialysis, transplantation was associated with a statistically significant survival benefit by 9 months for patients in every function quartile. Limitations Functional status is self-reported. Conclusions Even patients with low function appear to live longer with kidney transplantation versus dialysis. For waitlisted

  2. Tempos de espera no Supremo Tribunal Federal Waiting times in the Brazilian Supreme Court

    Directory of Open Access Journals (Sweden)

    Claudio Weber Abramo

    2010-12-01

    Full Text Available Expõe-se um método de medir o desempenho de magistrados na decisão de processos judiciais. A estratégia é usada para construir uma ferramenta de monitoramento voltada para o Supremo Tribunal Federal brasileiro. A medida de tempos médios de espera na decisão de causas que tramitam na Corte pode ajudar na formulação de intervenções administrativas destinadas a reduzi-los. A comparação entre as médias observadas em diferentes classes processuais e ramos do Direito pode ajudar a compreender melhor os fatores subjetivos em jogo nas decisões judiciais. A comparação dos desempenhos de magistrados individuais ajuda a melhorar o sistema pelo uso de penalidades reputacionais. A partir do método constata-se que juízes reagem a processos judiciais da mesma forma que sistemas biológicos, mecânicos e eletrônicos reagem a estímulos. A forma assumida pelas distribuições de tempo de decisão medidas ajuda a explicar o pessimismo das percepções populares a respeito da celeridade do judiciário.A method for measuring and monitoring the numerical performance of judges in deciding cases is presented. The strategy has been used to build an internet monitoring tool aimed at the members of the Brazilian Supreme Court. Measuring the expectations for judicial cases to be decided permits drafting administrative interventions aimed at reducing waiting times. Comparing expectations according to types of cases may help to better understand the subjective factors that are in play in judicial decisions. Comparing individual magistrates' performances helps to improve the system by using reputational penalties. It is found that judges react to cases in the same general manner as biological, electronic and mechanical systems react to stimuli. The form of the time distributions measured helps to explain popular perceptions (pessimistic, in the case of Brazil about the judiciary's efficiency.

  3. Functional status, time to transplantation, and survival benefit of kidney transplantation among wait-listed candidates.

    Science.gov (United States)

    Reese, Peter P; Shults, Justine; Bloom, Roy D; Mussell, Adam; Harhay, Meera N; Abt, Peter; Levine, Matthew; Johansen, Kirsten L; Karlawish, Jason T; Feldman, Harold I

    2015-11-01

    In the context of an aging end-stage renal disease population with multiple comorbid conditions, transplantation professionals face challenges in evaluating the global health of patients awaiting kidney transplantation. Functional status might be useful for identifying which patients will derive a survival benefit from transplantation versus dialysis. Retrospective cohort study of wait-listed patients using data for functional status from a national dialysis provider linked to United Network for Organ Sharing registry data. Adult kidney transplantation candidates added to the waiting list between 2000 and 2006. Physical Functioning scale of the Medical Outcomes Study 36-Item Short Form Health Survey, analyzed as a time-varying covariate. Kidney transplantation; survival benefit of transplantation versus remaining wait-listed. We used multivariable Cox regression to assess the association between physical function with study outcomes. In survival benefit analyses, transplantation status was modeled as a time-varying covariate. The cohort comprised 19,242 kidney transplantation candidates (median age, 51 years; 36% black race) receiving maintenance dialysis. Candidates in the lowest baseline Physical Functioning score quartile were more likely to be inactivated (adjusted HR vs highest quartile, 1.30; 95% CI, 1.21-1.39) and less likely to undergo transplantation (adjusted HR vs highest quartile, 0.64; 95% CI, 0.61-0.68). After transplantation, worse Physical Functioning score was associated with shorter 3-year survival (84% vs 92% for the lowest vs highest function quartiles). However, compared to dialysis, transplantation was associated with a statistically significant survival benefit by 9 months for patients in every function quartile. Functional status is self-reported. Even patients with low function appear to live longer with kidney transplantation versus dialysis. For wait-listed patients, global health measures such as functional status may be more useful in

  4. Gender and socioeconomic status as determinants of waiting time for inpatient surgery in a system with implicit queue management.

    Science.gov (United States)

    Arnesen, Kjell E; Erikssen, Jan; Stavem, Knut

    2002-12-01

    In a system with implicit queue management, to examine gender and socioeconomic status as determinants of waiting time for inpatient surgery, after adjusting for other potential predictors. A cohort of 452 subjects was examined in outpatient clinics of a general hospital and referred to inpatient surgery. They were followed until scheduled hospital admission (n=396) or until the requested procedure no longer was relevant (n=56). We compared waiting time between groups from referral date until hospital admission, using Kaplan-Meier estimates of waiting times and log rank test. A Cox proportional hazards model was used for assessing the risk ratio (RR) of hospital admission for scheduled surgery. Gender and socioeconomic status could not explain variations in waiting time. However, patients with suspected/verified neoplastic disease or a risk of serious deterioration without treatment had markedly shorter waiting times than the reference groups, with adjusted RR (95% confidence intervals (95%CI)) of time to receiving in-patient surgery of 2.3 (1.7-3.0) and 2.0 (1.3-3.0), respectively. Being on sick leave was associated with shorter waiting time, adjusted RR of 1.7 (1.2-2.5). Referrals from within the hospital or other hospitals had also shorter waiting times than referrals from primary health care physicians, adjusted RR=1.4 (1.1-1.8). There was no evidence of bias against women or people in lower socioeconomic classes in this implicit queue management system. However, patients' access to inpatient surgery was associated with malignancy, prognosis, sick leave status, physician experience, referral pattern and the major diagnosis category.

  5. Tumor progression in waiting time for radiotherapy in head and neck cancer

    DEFF Research Database (Denmark)

    Jensen, Anni Ravnsbaek; Nellemann, Hanne Marie; Overgaard, Jens

    2007-01-01

    INTRODUCTION: Waiting-time prior to radiotherapy is a well-known problem. This study aims to determine the impact of time on tumor growth in a patient population with squamous-cell carcinoma of the head and neck (SCCHN). MATERIAL AND METHODS: In a consecutive cohort, all patients with both...... a diagnostic scan and a treatment-planning scan were identified. In total 648 patients were seen, and 414 treated with primary radiotherapy. Ninety-five had two scans and 61 sets were eligible for comparison. Endpoints were change in tumor volume, tumor volume doubling time (TVD) and disease progression...... measured by TNM-classification and RECIST criteria. RESULTS: Median interval between eligible scans was 28 (5-95) days. Thirty-eight (62%) had measurable increase in tumor volume, median 46% (6-495%). For all patients TVD was median 99 days, but for the half of patients with fastest growing tumors TVD...

  6. Waiting times before dental care under general anesthesia in children with special needs in the Children's Hospital of Casablanca.

    Science.gov (United States)

    Badre, Bouchra; Serhier, Zineb; El Arabi, Samira

    2014-01-01

    Oral diseases may have an impact on quality of children's life. The presence of severe disability requires the use of care under general anesthesia (GA). However, because of the limited number of qualified health personnel, waiting time before intervention can be long. To evaluate the waiting time before dental care under general anesthesia for children with special needs in Morocco. A retrospective cohort study was carried out in pediatric dentistry unit of the University Hospital of Casablanca. Data were collected from records of patients seen for the first time between 2006 and 2011. The waiting time was defined as the time between the date of the first consultation and intervention date. 127 children received dental care under general anesthesia, 57.5% were male and the average age was 9.2 (SD = 3.4). Decay was the most frequent reason for consultation (48%), followed by pain (32%). The average waiting time was 7.6 months (SD = 4.2 months). The average number of acts performed per patient was 13.5. Waiting times were long, it is necessary to take measures to reduce delays and improve access to oral health care for this special population.

  7. Fractal Time Random Walk and Subrecoil Laser Cooling Considered as Renewal Processes with Infinite Mean Waiting Times

    Science.gov (United States)

    Bardou, F.

    There exist important stochastic physical processes involving infinite mean waiting times. The mean divergence has dramatic consequences on the process dynamics. Fractal time random walks, a diffusion process, and subrecoil laser cooling, a concentration process, are two such processes that look qualitatively dissimilar. Yet, a unifying treatment of these two processes, which is the topic of this pedagogic paper, can be developed by combining renewal theory with the generalized central limit theorem. This approach enables to derive without technical difficulties the key physical properties and it emphasizes the role of the behaviour of sums with infinite means.

  8. Did waiting times really decrease following a service reorganization? Results from a retrospective study in a pediatric rehabilitation program in Québec.

    Science.gov (United States)

    Camden, Chantal; Swaine, Bonnie; Levasseur, Mélanie

    2013-05-01

    To examine changes in waiting times and types of services received before, during and after a pediatric rehabilitation service reorganization including new admission procedures; To compare waiting time data available in the program's administrative database and children's medical files. Waiting time was defined as the time elapsed between referral and accessing a service provided by any clinician in the program (program waiting time) or by any clinician within a discipline (discipline-specific waiting time). Services were categorized as individual, group treatment, or other. ANOVAs and χ(2) tests were used to examine changes in waiting times and type of services, respectively. Paired T-tests compared the program waiting times from the two databases. Data were collected on 188 children (mean age: 4 years and 1 month). The program and occupational therapy waiting times were shorter following the service reorganization. For two disciplines, the proportion of children receiving individual treatment diminished over time, while group and other types of interventions increased. Program waiting times calculated using the two data sources did not differ significantly but differences in the available data highlighted administrative issues. Service reorganization can decrease waiting times and change the type of services offered over time.

  9. Wait time management strategies for scheduled care: what makes them succeed?

    Science.gov (United States)

    Pomey, Marie-Pascale; Forest, Pierre-Gerlier; Sanmartin, Claudia; De Coster, Carolyn; Drew, Madeleine

    2010-02-01

    To assess experts' perceptions of the contextual and local factors that promote or inhibit the implementation of waiting time management strategies (WTMS) in Canadian healthcare organizations. We conducted 16 semi-structured interviews and one focus group with individuals involved in WTMS at the federal, provincial or organizational level. The most frequently cited local factor was physicians' participation. Physicians' leadership made the greatest difference in bringing resistant physicians on board. To be effective, however, local leadership had to be supported by senior management. Alignment of financial incentives between the contextual and local levels was also frequently cited, and interviewees stressed the importance of tools used to design, monitor, evaluate and prioritize WTMS. Finding the right balance between supportive resources and tools and an effective management system is a tough challenge. But achieving this balance will help reconcile contradictions between top-down and bottom-up WTMS.

  10. A template for reducing ophthalmology outpatient waiting times: community ophthalmic care.

    Science.gov (United States)

    Goetz, R K; Hughes, F E; Duignan, E S; O'Neill, E C; Connell, P P; Fulcher, T P; Treacy, M P

    2018-02-01

    Through an Irish Health Service Executive (HSE) initiative to tackle excessive hospital outpatient waiting times, 996 patients referred to the Ophthalmology Outpatient Department (OPD) of the Mater Misericordiae University Hospital (MMUH), Eccles Street, Dublin 7, Ireland, were outsourced to a community medical eye clinic (CMEC) for consultation with specialist-registered ophthalmologists. The study aims to determine if patients referred as routine to the OPD department could be managed in a community setting. 996 patients were reviewed in the CMEC, and their data was collected and placed into a spreadsheet for analysis. 61.2% of patients referred to the OPD were fully managed in the community clinic, and 34.9% required ophthalmic surgery in hospital. By facilitating direct listing of some of the surgical patients to the hospital theatre list, 89.8% of the 996 referrals received treatment without needing to attend the hospital outpatients department.

  11. Lean-driven improvements slash wait times, drive up patient satisfaction scores.

    Science.gov (United States)

    2012-07-01

    Administrators at LifePoint Hospitals, based in Brentwood, TN, used lean manufacturing techniques to slash wait times by as much as 30 minutes and achieve double-digit increases in patient satisfaction scores in the EDs at three hospitals. In each case, front-line workers took the lead on identifying opportunities for improvement and redesigning the patient-flow process. As a result of the new efficiencies, patient volume is up by about 25% at all three hospitals. At each hospital, the improvement process began with Kaizen, a lean process that involves bringing personnel together to flow-chart the current system, identify problem areas, and redesign the process. Improvement teams found big opportunities for improvement at the front end of the flow process. Key to the approach was having a plan up front to deal with non-compliance. To sustain improvements, administrators gather and disseminate key metrics on a daily basis.

  12. Consequences of the prolonged waiting time for patient candidates for heart surgery.

    Science.gov (United States)

    Haddad, Nagib; Bittar, Olímpio J N V; Pereira, Ana A M; da Silva, Maria Barbosa; Amato, Vivian L; Farsky, Pedro S; Ramos, Auristela I O; Sampaio, Marcelo; Almeida, Tarcísio L V; Armaganijan, Dikran; Sousa, José Eduardo M R

    2002-05-01

    To assess mortality and the psychological repercussions of the prolonged waiting time for candidates for heart surgery. From July 1999 to May 2000, using a standardized questionnaire, we carried out standardized interviews and semi-structured psychological interviews with 484 patients with coronary heart disease, 121 patients with valvular heart diseases, and 100 patients with congenital heart diseases. The coefficients of mortality (deaths per 100 patients/year) were as follows: patients with coronary heart disease, 5.6; patients with valvular heart diseases, 12.8; and patients with congenital heart diseases, 3.1 (pvalvular heart diseases than in patients with coronary heart disease and congenital heart diseases (pvalvular heart diseases than in the other patients (pvalvular heart diseases, this probability was higher in females than in males (pvalvular heart diseases, with negative psychological and social repercussions.

  13. [Waiting lists in public systems: from expanding supply to timely access? Reflections on Spain's National Health System].

    Science.gov (United States)

    Conill, Eleonor Minho; Giovanella, Lígia; de Almeida, Patty Fidelis

    2011-06-01

    The paper discusses the issue of waiting times based on a study of Spain's National Health System (Sistema Nacional de Salud, SNS), focusing on the national context, management issues and local practices. Observation visits and interviews with health personnel and managers conducted in the metropolitan areas of the Autonomous Communities of Madrid, Andalusia, Catalonia and Basque Country were complemented by secondary data and a review of the literature. There is unanimity as to the positive results of the SNS, but cutting waiting times seems to be one key aspect requiring improvement. Two directions were identified for complementary measures: guaranteed maximum waiting times in the macro-social sphere associated with local measures to increase service integration and primary care resolution rates. The peculiarities of the Spanish decentralisation process and the existence of economic, political and health profession corporate interests were mentioned as factors hampering waiting list regulation, transparency and management. A comprehensive approach to this issue shows the need to shift discussion from waiting list monitoring and/or expanded supply to guaranteed timely access. That is the quality differential that primary care-oriented systems must bring to public health systems.

  14. Seasonality of service provision in hip and knee surgery: A possible contributor to waiting times? A time series analysis

    Directory of Open Access Journals (Sweden)

    Upshur Ross EG

    2006-03-01

    Full Text Available Abstract Background The question of how best to reduce waiting times for health care, particularly surgical procedures such as hip and knee replacements is among the most pressing concern of the Canadian health care system. The objective of this study was to test the hypothesis that significant seasonal variation exists in the performance of hip and knee replacement surgery in the province of Ontario. Methods We performed a retrospective, cross-sectional time series analysis examining all hip and knee replacement surgeries in people over the age of 65 in the province of Ontario, Canada between 1992 and 2002. The main outcome measure was monthly hospitalization rates per 100 000 population for all hip and knee replacements. Results There was a marked increase in the rate of hip and knee replacement surgery over the 10-year period as well as an increasing seasonal variation in surgeries. Highly significant (Fisher Kappa = 16.05, p 2Autoreg = 0.85 seasonality was identified in the data. Conclusion Holidays and utilization caps appear to exert a significant influence on the rate of service provision. It is expected that waiting times for hip and knee replacement could be reduced by reducing seasonal fluctuations in service provision and benchmarking services to peak delivery. The results highlight the importance of system behaviour in seasonal fluctuation of service delivery.

  15. Wait times for breast surgical operations, 2003-2011: a report from the National Cancer Data Base.

    Science.gov (United States)

    Liederbach, Erik; Sisco, Mark; Wang, Chihsiung; Pesce, Catherine; Sharpe, Susan; Winchester, David J; Yao, Katharine

    2015-03-01

    Few large-scale multicenter studies have examined wait times for breast surgery and no benchmarks exist. Using the National Cancer Data Base, we analyzed time from diagnosis to first surgery for 819,175 non-neoadjuvant AJCC stage 0-III breast cancer patients treated from 2003 to 2011. Chi-square tests and logistic regression models were used to examine factors associated with delays to surgery and adjuvant chemotherapy. Seventy percent of patients underwent an initial lumpectomy (LP), 22% a mastectomy (MA), and 8% a mastectomy with reconstruction (MR). The median time from diagnosis to first surgery significantly increased by approximately 1 week for all three procedures over the study period. In a multivariate analysis, the following variables were independent predictors of a longer wait time to first surgery: increasing age, black or Hispanic race, Medicaid or no insurance, low-education communities and metropolitan areas, increasing comorbidities, stage 0 and grade 1 disease, academic/research facilities, high-volume facilities, and facilities located in the New England, Mid-Atlantic, and Pacific regions. In 2010-2011, patients who waited >30 days for surgery were 1.36 times more likely (OR = 1.36, 95% CI 1.30-1.43) to experience a delay to adjuvant chemotherapy >60 days compared with patients who were surgically treated within 30 days of diagnosis. Facility and socioeconomic factors are most strongly associated with longer wait times for breast operations, and delays to surgery are associated with delays to adjuvant chemotherapy initiation.

  16. The waiting time of the ship on port entrance at required water level

    Directory of Open Access Journals (Sweden)

    Wiesław GALOR

    2008-01-01

    Full Text Available The safety of a ship which manoeuvres within a port area depends to a large extent on the underkeel clearance (UKC. Ports have been built to handle ships of specific maximum parameters. In many cases, however, the existing ports face the need to accept ships larger than those they were designed for. The construction of newharbours is limited by both natural conditions and exceedingly high estimated costs. The main restriction for handling larger ships is the depth of port basins, directly affecting the safety of the manoeuvring ship. The minimum underkeel clearance is most often specified by port regulations as a constant value. However, depending on the prevailingconditions, mainly water level, this required UKC value can be reduced. Thus, ships of larger draft will be allowed to enter. This article / paper present a method of UKC optimization with two restrictions: maximum permitted navigational risk and the time ofwaiting for sufficient water level. An example has been given in reference to ship’s waiting time probability for the port of Świnoujście.

  17. Portuguese Society of Cardiothoracic and Vascular Surgery/Portuguese Society of Cardiology recommendations for waiting times for cardiac surgery.

    Science.gov (United States)

    Neves, José; Pereira, Hélder; Sousa Uva, Miguel; Gavina, Cristina; Leite Moreira, Adelino; Loureiro, Maria José

    2015-11-01

    Appointed jointly by the Portuguese Society of Cardiothoracic and Vascular Surgery (SPCCTV) and the Portuguese Society of Cardiology (SPC), the Working Group on Waiting Times for Cardiac Surgery was established with the aim of developing practical recommendations for clinically acceptable waiting times for the three critical phases of the care of adults with heart disease who require surgery or other cardiological intervention: cardiology appointments; the diagnostic process; and invasive treatment. Cardiac surgery has specific characteristics that are not comparable to other surgical specialties. It is important to reduce maximum waiting times and to increase the efficacy of systems for patient monitoring and tracking. The information in this document is mainly based on available clinical information. The methodology used to establish the criteria was based on studies on the natural history of heart disease, clinical studies comparing medical treatment with intervention, retrospective and prospective analyses of patients on waiting lists, and the opinions of experts and working groups. Following the first step, represented by publication of this document, the SPCCTV and SPC, as the bodies best suited to oversee this process, are committed to working together to define operational strategies that will reconcile the clinical evidence with the actual situation and with available resources. Copyright © 2015 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  18. Utilizing lean tools to improve value and reduce outpatient wait times in an Indian hospital.

    Science.gov (United States)

    Miller, Richard; Chalapati, Nirisha

    2015-01-01

    This paper aims to demonstrate how lean tools were applied to some unique issues of providing healthcare in a developing country where many patients face challenges not found in developed countries. The challenges provide insight into how lean tools can be utilized to provide similar results across the world. This paper is based on a qualitative case study carried out by a master's student implementing lean at a hospital in India. This paper finds that lean tools such as value-stream mapping and root cause analysis can lead to dramatic reductions in waste and improvements in productivity. The problems of the majority of patients paying for their own healthcare and lacking transportation created scheduling problems that required patients to receive their diagnosis and pay for treatment within a single day. Many additional wastes were identified that were significantly impacting the hospital's ability to provide care. As a result of this project, average outpatient wait times were reduced from 1 hour to 15 minutes along with a significant increase in labor productivity. The results demonstrate how lean tools can increase value to the patients. It also provides are framework that can be utilized for healthcare providers in developed and developing countries to analyze their value streams to reduce waste. This paper is one of the first to address the unique issues of implementing lean to a healthcare setting in a developing country.

  19. Improving Customer Waiting Time at a DMV Center Using Discrete-Event Simulation

    Science.gov (United States)

    Arnaout, Georges M.; Bowling, Shannon

    2010-01-01

    Virginia's Department of Motor Vehicles (DMV) serves a customer base of approximately 5.6 million licensed drivers and ID card holders and 7 million registered vehicle owners. DMV has more daily face-to-face contact with Virginia's citizens than any other state agency [1]. The DMV faces a major difficulty in keeping up with the excessively large customers' arrival rate. The consequences are queues building up, stretching out to the entrance doors (and sometimes even outside) and customers complaining. While the DMV state employees are trying to serve at their fastest pace, the remarkably large queues indicate that there is a serious problem that the DMV faces in its services, which must be dealt with rapidly. Simulation is considered as one of the best tools for evaluating and improving complex systems. In this paper, we use it to model one of the DMV centers located in Norfolk, VA. The simulation model is modeled in Arena 10.0 from Rockwell systems. The data used is collected from experts of the DMV Virginia headquarter located in Richmond. The model created was verified and validated. The intent of this study is to identify key problems causing the delays at the DMV centers and suggest possible solutions to minimize the customers' waiting time. In addition, two tentative hypotheses aiming to improve the model's design are tested and validated.

  20. Consequences of the Prolonged Waiting Time for Patients Candidates for Heart Surgery

    Directory of Open Access Journals (Sweden)

    Haddad Nagib

    2002-01-01

    Full Text Available OBJECTIVE - To assess mortality and the psychological repercussions of the prolonged waiting time for candidates for heart surgery. METHODS - From July 1999 to May 2000, using a standardized questionnaire, we carried out standardized interviews and semi-structured psychological interviews with 484 patients with coronary heart disease, 121 patients with valvular heart diseases, and 100 patients with congenital heart diseases. RESULTS - The coefficients of mortality (deaths per 100 patients/year were as follows: patients with coronary heart disease, 5.6; patients with valvular heart diseases, 12.8; and patients with congenital heart diseases, 3.1 (p<0.0001. The survival curve was lower in patients with valvular heart diseases than in patients with coronary heart disease and congenital heart diseases (p<0.001. The accumulated probability of not undergoing surgery was higher in patients with valvular heart diseases than in the other patients (p<0.001, and, among the patients with valvular heart diseases, this probability was higher in females than in males (p<0.01. Several patients experienced intense anxiety and attributed their adaptive problems in the scope of love, professional, and social lives, to not undergoing surgery. CONCLUSION - Mortality was high, and even higher among the patients with valvular heart diseases, with negative psychological and social repercussions.

  1. Effect of Lean Processes on Surgical Wait Times and Efficiency in a Tertiary Care Veterans Affairs Medical Center.

    Science.gov (United States)

    Valsangkar, Nakul P; Eppstein, Andrew C; Lawson, Rick A; Taylor, Amber N

    2017-01-01

    There are an increasing number of veterans in the United States, and the current delay and wait times prevent Veterans Affairs institutions from fully meeting the needs of current and former service members. Concrete strategies to improve throughput at these facilities have been sparse. To identify whether lean processes can be used to improve wait times for surgical procedures in Veterans Affairs hospitals. Databases in the Veterans Integrated Service Network 11 Data Warehouse, Veterans Health Administration Support Service Center, and Veterans Information Systems and Technology Architecture/Dynamic Host Configuration Protocol were queried to assess changes in wait times for elective general surgical procedures and clinical volume before, during, and after implementation of lean processes over 3 fiscal years (FYs) at a tertiary care Veterans Affairs medical center. All patients evaluated by the general surgery department through outpatient clinics, clinical video teleconferencing, and e-consultations from October 2011 through September 2014 were included. Patients evaluated through the emergency department or as inpatient consults were excluded. The surgery service and systems redesign service held a value stream analysis in FY 2013, culminating in multiple rapid process improvement workshops. Multidisciplinary teams identified systemic inefficiencies and strategies to improve interdepartmental and patient communication to reduce canceled consultations and cases, diagnostic rework, and no-shows. High-priority triage with enhanced operating room flexibility was instituted to reduce scheduling wait times. General surgery department pilot projects were then implemented mid-FY 2013. Planned outcome measures included wait time, clinic and telehealth volume, number of no-shows, and operative volume. Paired t tests were used to identify differences in outcome measures after the institution of reforms. Following rapid process improvement workshop project rollouts, mean

  2. Waiting times for prostate cancer diagnosis in KwaZulu-Natal, South ...

    African Journals Online (AJOL)

    Background. There is currently no evidence in the South African (SA) literature to suggest how long patients with clinically suspected prostate cancer (an elevated prostate-specific antigen level or abnormal findings on digital rectal examination) wait to have a prostate biopsy. Objectives. To improve the overall efficiency of ...

  3. A prospective study on the impact of waiting times for radiotherapy ...

    African Journals Online (AJOL)

    Background: Radiotherapy plays a vital role in the management of cervical cancer. However, because of high patient load and limited resources, waiting lists are unacceptably long. This is a highly curable malignancy that often occurs in economically active, relatively young women. The impact of treatment delays on society ...

  4. Quantitative modelling for wait time reduction: A comprehensive simulation applied in general surgery

    NARCIS (Netherlands)

    Vanberkel, Peter T.; Blake, J.T.

    2008-01-01

    This thesis describes the use of operational research techniques to analyze the wait list for the division of general surgery at the Capital District Health Authority (CDHA) in Halifax, Nova Scotia, Canada. A comprehensive simulation model was developed to facilitate capacity planning decisions and

  5. A comprehensive simulation for wait time reduction and capacity planning applied in general surgery

    NARCIS (Netherlands)

    Vanberkel, P.T.; Blake, John T.

    2007-01-01

    This paper describes the use of operational research techniques to analyze the wait list for the Division of General Surgery at the Capital District Health Authority in Halifax, Nova Scotia, Canada. A discrete event simulation model was developed to aid capacity planning decisions and to analyze the

  6. A prospective study on the impact of waiting times for radiotherapy ...

    African Journals Online (AJOL)

    Background. Radiotherapy plays a vital role in the management of cervical cancer. However, because of high patient load and limited resources, waiting lists are unacceptably long. This is a highly curable malignancy that often occurs in economically active, relatively young women. The impact of treatment delays on society ...

  7. Association between age older than 75 years and exceeded target waiting times in the emergency department: a multicenter cross-sectional survey in the Paris metropolitan area, France.

    Science.gov (United States)

    Freund, Yonathan; Vincent-Cassy, Christophe; Bloom, Benjamin; Riou, Bruno; Ray, Patrick

    2013-11-01

    We seek to evaluate whether age greater than 75 years is an independent predictor of prolonged waiting time in the emergency department (ED). We retrospectively analyzed all adult attendances to 9 EDs within the Paris area during 2011. The primary endpoint was target waiting time exceeded, defined as a waiting time for medical assessment longer than the maximal recommended waiting time according to triage level. To assess our primary objective, we performed logistic regression using patient- and ED-related variables to determine whether age greater than 75 years was independently associated with higher rate of target waiting time exceeded. A total of 317,793 patients were included, of whom 173,629 (55%) had an exceeded target waiting time. Mean age was 45.8 years and 12.7% were older than 75 years. Target waiting time was exceeded for 55% of patients: 53% for patients younger than 75 years (95% confidence interval [CI] 53% to 54%) versus 64% for older patients (95% CI 63% to 65%), relative risk 1.20. In the multivariate analysis, age greater than 75 years was independently associated with an exceeded target waiting time (odds ratio [OR] 1.30; 95% CI 1.27 to 1.33). Other variables associated with exceeded target waiting time were triage level (OR 5.45 [95% CI 5.32 to 5.60] for triage level 2 versus triage level 4), high daily occupancy (OR 3.78 [95% CI 3.53 to 4.03]), day of the week (OR 1.12 [95% CI 1.09 to 1.14] for Monday), and time of the visit (OR 1.79 [95% CI 1.76 to 1.82] from 6 pm to 8 am). Patients older than 75 years are less likely to be seen within the target waiting time. Copyright © 2013 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

  8. Waiting Time for Coronal Preparation and the Influence of Different Cements on Tensile Strength of Metal Posts

    Directory of Open Access Journals (Sweden)

    Ilione Kruschewsky Costa Sousa Oliveira

    2012-01-01

    Full Text Available This study aimed to assess the effect of post-cementation waiting time for core preparation of cemented cast posts and cores had on retention in the root canal, using two different luting materials. Sixty extracted human canines were sectioned 16 mm from the root apex. After cast nickel-chromium metal posts and cores were fabricated and luted with zinc phosphate (ZP cement or resin cement (RC, the specimens were divided into 3 groups (n = 10 according to the waiting time for core preparation: no preparation (control, 15 minutes, or 1 week after the core cementation. At the appropriate time, the specimens were subjected to a tensile load test (0.5 mm/min until failure. Two-way ANOVA (time versus cement and the Tukey tests (P < 0.05 showed significantly higher (P < 0.05 tensile strength values for the ZP cement groups than for the RC groups. Core preparation and post-cementation waiting time for core recontouring did not influence the retention strength. ZP was the best material for intraradicular metal post cementation.

  9. Prototype of a Questionnaire and Quiz System for Supporting Increase of Health Awareness During Wait Time in Dispensing Pharmacy

    Science.gov (United States)

    Toda, Takeshi; Chen, Poa-Min; Ozaki, Shinya; Ideguchi, Naoko; Miyaki, Tomoko; Nanbu, Keiko; Ikeda, Keiko

    For quit-smoking clinic and its campaign, there was a need for pharmacists to investigate pediatric patient's parent consciousness to tobacco harm utilizing wait time in a pediatric dispensing pharmacy. In this research, we developed the questionnaire and quiz total system using the tablet for user interface, in which people can easily answer the questionnaire/quiz and quickly see the total results on the spot in order to enhance their consciousness to the tobacco harm. The system also provides their tobacco dependence level based on the questionnaire results and some advice for their health and dietary habits due to the tobacco dependence level. From a field trial with one hundred four examinees in the pediatric dispensing pharmacy, the user interface was useful compared to conventional questionnaire form. The system could enhance their consciousness to tobacco harm and make their beneficial use of waiting time in dispensing pharmacy. Some interesting suggestions for improvement and new services were also obtained.

  10. The impact of travel distance, travel time and waiting time on health-related quality of life of diabetes patients: An investigation in six European countries.

    Science.gov (United States)

    Konerding, Uwe; Bowen, Tom; Elkhuizen, Sylvia G; Faubel, Raquel; Forte, Paul; Karampli, Eleftheria; Mahdavi, Mahdi; Malmström, Tomi; Pavi, Elpida; Torkki, Paulus

    2017-04-01

    The effects of travel distance and travel time to the primary diabetes care provider and waiting time in the practice on health-related quality of life (HRQoL) of patients with type 2 diabetes are investigated. Survey data of 1313 persons with type 2 diabetes from six regions in England (274), Finland (163), Germany (254), Greece (165), the Netherlands (354), and Spain (103) were analyzed. Various multiple linear regression analyses with four different EQ-5D-3L indices (English, German, Dutch and Spanish index) as target variables, with travel distance, travel time, and waiting time in the practice as focal predictors and with control for study region, patient's gender, patient's age, patient's education, time since diagnosis, thoroughness of provider-patient communication were computed. Interactions of regions with the remaining five control variables and the three focal predictors were also tested. There are no interactions of regions with control variables or focal predictors. The indices decrease with increasing travel time to the provider and increasing waiting time in the provider's practice. HRQoL of patients with type 2 diabetes might be improved by decreasing travel time to the provider and waiting time in the provider's practice. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Quality management: reduction of waiting time and efficiency enhancement in an ENT-university outpatients' department

    Directory of Open Access Journals (Sweden)

    Helbig Matthias

    2009-01-01

    Full Text Available Abstract Background Public health systems are confronted with constantly rising costs. Furthermore, diagnostic as well as treatment services become more and more specialized. These are the reasons for an interdisciplinary project on the one hand aiming at simplification of planning and scheduling patient appointments, on the other hand at fulfilling all requirements of efficiency and treatment quality. Methods As to understanding procedure and problem solving activities, the responsible project group strictly proceeded with four methodical steps: actual state analysis, analysis of causes, correcting measures, and examination of effectiveness. Various methods of quality management, as for instance opinion polls, data collections, and several procedures of problem identification as well as of solution proposals were applied. All activities were realized according to the requirements of the clinic's ISO 9001:2000 certified quality management system. The development of this project is described step by step from planning phase to inauguration into the daily routine of the clinic and subsequent control of effectiveness. Results Five significant problem fields could be identified. After an analysis of causes the major remedial measures were: installation of a patient telephone hotline, standardization of appointment arrangements for all patients, modification of the appointments book considering the reason for coming in planning defined working periods for certain symptoms and treatments, improvement of telephonic counselling, and transition to flexible time planning by daily updates of the appointments book. After implementation of these changes into the clinic's routine success could be demonstrated by significantly reduced waiting times and resulting increased patient satisfaction. Conclusion Systematic scrutiny of the existing organizational structures of the outpatients' department of our clinic by means of actual state analysis and analysis of

  12. Patient age, ethnicity and waiting times determine the likelihood of non-attendance at a first specialist rheumatology assessment.

    Science.gov (United States)

    Milne, Valerie; Kearns, Robin; Harrison, Andrew

    2014-01-01

    To identify demographic and geographic factors associated with non-attendance for first specialist assessment (FSA) at a publicly funded rheumatology clinic and identify changes in service provision that might improve attendance rates. Administrative data for 1953 new referrals over a 2-year period was collected from a New Zealand public rheumatology unit. Patient characteristics and location variables were tested for significance and odds ratios were generated to determine the relationship between non-attendance and referrals data. Patients in the 20-29 years age-group were least likely to attend appointments (P ≤ 0.001, OR 2.81, 95%CI 1.59-4.98). Māori and Pacific Peoples were each almost twice as likely to miss a FSA (P = 0.02, OR 1.87, 95%CI 1.11-3.15 and OR 1.89, 95%CI 1.11-3.22) as New Zealand Europeans. Non-attendance was independently associated with longer waiting times to FSA; with residential location and the uneven provision of services being strong predictors of longer waiting times (P ≤ 0.001). Non-attendance is associated with ethnicity, age and waiting times. It is likely that high deprivation influences ethnic variations in attendance but reasons for young people's non-attendance were difficult to identify. Patients domiciled further from the main rheumatology clinic were also less likely to attend. The influence of ethnicity and deprivation may be underestimated in this study as high Maori and Pacific ethnic populations live closer to well-resourced clinics. Focusing administrative resources on at-risk groups and restructuring the clinical service to improve uneven waiting times would be expected to improve attendance rates across the region. © 2013 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

  13. Impact of clinical urgency, physician supply and procedural capacity on regional variations in wait times for coronary angiography

    Directory of Open Access Journals (Sweden)

    Natarajan Madhu K

    2010-01-01

    Full Text Available Abstract Background Despite universal health care, there continues to be regional access disparities to coronary angiography in Canada. Our objective was to evaluate the extent to which demand-side factors such as clinical urgency/need, and supply-side factors, as reflected by differences in physician and procedural supply account for these inequalities. Methods Our cohort consisted of 74,254 consecutive patients referred for coronary angiography in Ontario, Canada between April 1st 2005 and March 31st 2006, divided into three urgency strata based on a clinical urgency scale. Cox-proportional hazard models were developed, adjusting for age, gender, socioeconomic status (SES, region, and urgency score, with greater hazard ratios (HR indicating shorter wait times. To evaluate mediators of any residual wait-time differences, we examined the influence of the regional supply of cath lab facilities, invasive cardiologists and general practitioners (GP. Results We found that the urgency score was a significant predictor of wait time in all three strata (urgent patients: HR 1.61 for each unit increase in patient urgency (95% Confidence interval (CI 1.55-1.67; semi-urgent patients: HR 1.55 (95% CI 1.44-1.68; elective patients: HR 1.13 (95% CI 1.08-1.18. After accounting for clinical need/urgency, regional wait time differences persisted; these were most consistently associated with variation in cath lab supply. The impact of invasive cardiologist supply was restricted to urgent patients while that of GP supply was confined to semi-urgent and elective patients. Conclusion We found that there remained significant regional disparities in access to coronary angiography after accounting for clinical need. These disparities are partially explained by variations in supply of both procedural capacity and physician services, most notably in elective and semi-urgent patients.

  14. Detailed Performance and Waiting-Time Predictability Analysis of Scheduling Options in On-Demand Video Streaming

    Directory of Open Access Journals (Sweden)

    Alsmirat MohammadA

    2010-01-01

    Full Text Available The number of on-demand video streams that can be supported concurrently is highly constrained by the stringent requirements of real-time playback and high transfer rates. To address this problem, stream merging techniques utilize the multicast facility to increase resource sharing. The achieved resource sharing depends greatly on how the waiting requests are scheduled for service. We investigate the effectiveness of the recently proposed cost-based scheduling in detail and analyze opportunities for further tunings and enhancements. In particular, we analyze alternative ways to compute the delivery cost. In addition, we propose a new scheduling policy, called Predictive Cost-Based Scheduling (PCS, which applies a prediction algorithm to predict future scheduling decisions and then uses the prediction results to potentially alter its current scheduling decisions. Moreover, we propose an enhancement technique, called Adaptive Regular Stream Triggering (ART, which significantly enhances stream merging behavior by selectively delaying the initiation of full-length video streams. We analyze the effectiveness of the proposed strategies in terms of their performance effectiveness and impacts on waiting-time predictability through extensive simulation. The results show that significant performance benefits as well as better waiting-time predictability can be attained.

  15. Donor Heart Utilization following Cardiopulmonary Arrest and Resuscitation: Influence of Donor Characteristics and Wait Times in Transplant Regions

    Directory of Open Access Journals (Sweden)

    Mohammed Quader

    2014-01-01

    Full Text Available Background. Procurement of hearts from cardiopulmonary arrest and resuscitated (CPR donors for transplantation is suboptimal. We studied the influences of donor factors and regional wait times on CPR donor heart utilization. Methods. From UNOS database (1998 to 2012, we identified 44,744 heart donors, of which 4,964 (11% received CPR. Based on procurement of heart for transplantation, CPR donors were divided into hearts procured (HP and hearts not procured (HNP groups. Logistic regression analysis was used to identify predictors of heart procurement. Results. Of the 4,964 CPR donors, 1,427 (28.8% were in the HP group. Donor characteristics that favored heart procurement include younger age (25.5 ± 15 yrs versus 39 ± 18 yrs, P≤0.0001, male gender (34% versus 23%, P≤0.0001, shorter CPR duration (30 min, P≤0.0001, and head trauma (60% versus 15%. Among the 11 UNOS regions, the highest procurement was in Region 1 (37% and the lowest in Region 3 (24%. Regional transplant volumes and median waiting times did not influence heart procurement rates. Conclusions. Only 28.8% of CPR donor hearts were procured for transplantation. Factors favoring heart procurement include younger age, male gender, short CPR duration, and traumatic head injury. Heart procurement varied by region but not by transplant volumes or wait times.

  16. NHS Scotland reduces the postcode lottery for hip arthroplasty: an ecological study of the impact of waiting time initiatives.

    Science.gov (United States)

    Kirkwood, Graham; Pollock, Allyson M; Howie, Colin; Wild, Sarah

    2014-06-01

    Following the election of the Labour government in 1997, policies were developed in England to reduce waiting times for NHS treatment with commitments to reduce health inequalities. Similar policies were adopted in Scotland but with less emphasis on the use of the private sector to deliver NHS treatments than in England. This study uses routinely collected NHS Scotland data to analyse geographical and socioeconomic inequalities in elective hip arthroplasty treatment before and after the introduction of the waiting time initiatives in Scotland in 2003. Ecological study design. Scotland. NHS-funded patients receiving elective hip arthroplasty delivered by the NHS and private hospitals between 1 April 1998 and 31 March 2008. Directly standardised treatment rates and incidence rate ratios calculated using Poisson regression. There was a 42% increase in NHS-funded hip arthroplasties carried out in Scotland from 4095 in 2002-2003 (1 April 2002-31 March 2003) to 5829 in 2007-2008. There is evidence of a statistically significant reduction in geographical inequality (likelihood ratio test p lottery', in hip arthroplasty treatment in Scotland may be due to increased NHS capacity, in particular the development of the NHS Golden Jubilee National Hospital in Clydebank, Greater Glasgow as a dedicated centre to reduce surgery waiting times. © The Royal Society of Medicine.

  17. A "package solution" fast track program can reduce the diagnostic waiting time in head and neck cancer

    DEFF Research Database (Denmark)

    Sørensen, Jesper Roed; Johansen, Jørgen; Gano, Lars

    2014-01-01

    In 2007, a fast track program for patients with suspicion of head and neck cancer (HNC) was introduced in Denmark to reduce unnecessary waiting time. The program was based on so called "package solutions" including pre-booked slots for outpatient evaluation, imaging, and diagnostic surgical...... procedures. The purpose of this study is to present a model for fast track handling of patients suspicious of cancer in the head and neck region and to evaluate the effect of implementation on the diagnostic work up time. Patients with suspicion of HNC referred to the same university department of ENT Head...

  18. Use of queue modelling in the analysis of elective patient treatment governed by a maximum waiting time policy

    DEFF Research Database (Denmark)

    Kozlowski, Dawid; Worthington, Dave

    2015-01-01

    chain and discrete event simulation models, to provide an insightful analysis of the public hospital performance under the policy rules. The aim of this paper is to support the enhancement of the quality of elective patient care, to be brought about by better understanding of the policy implications...... on the utilization of public hospital resources. This paper illustrates the use of a queue modelling approach in the analysis of elective patient treatment governed by the maximum waiting time policy. Drawing upon the combined strengths of analytic and simulation approaches we develop both continuous-time Markov...

  19. Two definitions of waiting well.

    Science.gov (United States)

    Sweeny, Kate; Reynolds, Chandra A; Falkenstein, Angelica; Andrews, Sara E; Dooley, Michael D

    2016-02-01

    Waiting for uncertain news is often distressing, at times even more distressing than facing bad news. The goal of this article was to investigate strategies for "waiting well" during these periods of uncertainty. Specifically, we propose 2 definitions of waiting well. First, people can wait in such a way as to ease their distress during the waiting period. Second, people could wait in such a way as to ease the pain of bad news or enhance the thrill of good news. We conducted a longitudinal study of law graduates (N = 230) awaiting their result on the California bar exam. Participants completed questionnaires prior to the exam, every 2 weeks during the 4-month waiting period, and shortly after learning whether they passed or failed. Cross-lagged models revealed that participants were quite unsuccessful at waiting well by our first definition. That is, their coping strategies were ineffective for reducing distress associated with uncertainty, apparently even backfiring in some cases. However, multiple regression analyses examining relationships between waiting experiences and responses to good and bad news found that many participants were successful at waiting well according to our second definition: Participants who suffered through a waiting period marked by anxiety, rumination, and pessimism responded more productively to bad news and more joyfully to good news, as compared with participants who suffered little during the wait. These findings substantiate the difficulty of enduring a stressful waiting period but suggest that this difficulty may pay off once the news arrives. (c) 2016 APA, all rights reserved).

  20. No More Waits and Delays: Streamlining Workflow to Decrease Patient Time of Stay for Image-guided Musculoskeletal Procedures.

    Science.gov (United States)

    Cheung, Yvonne Y; Goodman, Eric M; Osunkoya, Tomiwa O

    2016-01-01

    Long wait times limit our ability to provide the right care at the right time and are commonly products of inefficient workflow. In 2013, the demand for musculoskeletal (MSK) procedures increased beyond our department's ability to provide efficient and timely service. We initiated a quality improvement (QI) project to increase efficiency and decrease patient time of stay. Our project team included three MSK radiologists, one senior resident, one technologist, one administrative assistant/scheduler, and the lead technologist. We adopted and followed the Lean Six Sigma DMAIC (define, measure, analyze, improve, and control) approach. The team used tools such as voice of the customer (VOC), along with affinity and SIPOC (supplier, input, process, output, customer) diagrams, to understand the current process, identify our customers, and develop a project charter in the define stage. During the measure stage, the team collected data, created a detailed process map, and identified wastes with the value stream mapping technique. Within the analyze phase, a fishbone diagram helped the team to identify critical root causes for long wait times. Scatter plots revealed relationships among time variables. Team brainstorming sessions generated improvement ideas, and selected ideas were piloted via plan, do, study, act (PDSA) cycles. The control phase continued to enable the team to monitor progress using box plots and scheduled reviews. Our project successfully decreased patient time of stay. The highly structured and logical Lean Six Sigma approach was easy to follow and provided a clear course of action with positive results. (©)RSNA, 2016.

  1. Does rapid HIV testing result in an early diagnosis and reduce the waiting time for patients to receive medical care?

    Science.gov (United States)

    Melo, Magaly Carvalho Vieira de; Ximenes, Ricardo Arraes de Alencar; Falcão, Ilka Veras; Miranda-Filho, Demócrito de Barros

    2018-01-01

    The implementation of rapid HIV testing in Brazil began in 2006 for specific groups, and from 2009 was extended to the Counseling and Testing Centers (CTC) in certain Brazilian capitals. The aim of this study was to compare two groups of individuals: those diagnosed with HIV infection by conventional testing and those diagnosed with rapid testing, with respect to: the waiting time before receiving medical care, the time of the first laboratory tests and the virological, immune and clinical status. This is a cross-sectional study to compare a group with individuals diagnosed by conventional testing (2006-2008) and another with those diagnosed by rapid testing (2010-2011).The median time between blood collection and diagnosis of HIV in the conventional test group was 76 days, while in the rapid test group 94.2% of the subjects received their results on the same day of blood collection (p test group, the median period of time before the first consultation with an infectious disease specialist was 99 days, and for the rapid test group the time was 14 days (p test group (p test group (472) was higher than in the conventional test group (397) (p = 0.01). The introduction of rapid HIV testing as a diagnostic strategy has reduced the waiting times for medical care and laboratory tests and also allowed earlier diagnosis of HIV infection than with the conventional test.

  2. Waiting Time for Start of Outpatient Cardiac Rehabilitation: Correlations of Non Compliance to Systematic Referral After Coronary Artery Bypass Surgery

    Directory of Open Access Journals (Sweden)

    Ali Soroush

    2016-04-01

    Full Text Available Objectives To assess the waiting time, number of delays, and correlations of non-commitment to the systematic referral to the outpatient cardiac rehabilitation (CR among coronary artery bypass surgery (CABG patients. Methods The cross-sectional study data were gathered through evaluations related to 1,187 CABG patients who were referred to the outpatient CR of 1 hospital in western Iran during 2010 to 2014. The instruments included were demographics and actual risk factors checklist, single item of perceived risk factors, and Beck depression inventory (BDI. Data was analyzed via chi-square test, ANOVA, Bonferroni post hoc test, and binary logistic regression analysis. Results Among 1 187 patients (830 male, 27% had delayed referral, and the number of delays decreased from 2010 (49.3% to 2014 (7.6% (P < 0.001. The mean of the waiting time to receive outpatient CR in western Iran was an estimated 59 days. This mean has been reduced from 66 days (2010 to 53 days (2014 (P < 0.001. After adjustment for all demographics, the results indicated that diabetic patients (P = 0.002 and patients with biological (P = 0.002, behavioral (P = 0.003, or psychological (P = 0.002 perceived risk factors have less commitment. In addition, a family history of cardiac increases the possibility of commitment as 2.41 times (P < 0.001. Conclusions Despite the progressive process of patients’ admittance and acceptability of the present waiting time, especially after 2014, it seems that more attention to diabetic patients and patients without a family history of cardiac, and modification of attitudes about multiple risk factors can associate the self-care with more responsibility and it may also be affective in the control of harm consequences through commitment to the systematic referral.

  3. Pharmacy Wait Time and Prescription Errors at the Dwight D. Eisenhower Army Medical Center Outpatient Pharmacy: A Study of Manpower and Customer Service Initiatives

    National Research Council Canada - National Science Library

    Bonds, Kevin M

    2004-01-01

    A retrospective study was undertaken at the Eisenhower Army Medical Center to investigate the probable cause and possible solutions to increased waiting room time for patients and prescription errors...

  4. Analysis of bluetooth and wi-fi technology to measure wait times of personal vehicles at Arizona-Mexico ports of entry : [executive summary].

    Science.gov (United States)

    2015-11-01

    The Arizona Department of Transportation (ADOT), Office of P3 Initiatives and International : Affairs selected Lee Engineering to analyze the penetration rate of Anonymous Re-Identification : (ARID) technology to measure wait time of U.S. and Mexico ...

  5. Applying the Lean principles of the Toyota Production System to reduce wait times in the emergency department.

    Science.gov (United States)

    Ng, David; Vail, Gord; Thomas, Sophia; Schmidt, Nicki

    2010-01-01

    In recognition of patient wait times, and deteriorating patient and staff satisfaction, we set out to improve these measures in our emergency department (ED) without adding any new funding or beds. In 2005 all staff in the ED at Hôtel-Dieu Grace Hospital began a transformation, employing Toyota Lean manufacturing principles to improve ED wait times and quality of care. Lean techniques such as value-stream mapping, just-in-time delivery techniques, workplace organization, reduction of systemic wastes, use of the worker as the source of quality improvement and ongoing refinement of our process steps formed the basis of our project. Our ED has achieved major improvements in departmental flow without adding any additional ED or inpatient beds. The mean registration to physician time has decreased from 111 minutes to 78 minutes. The number of patients who left without being seen has decreased from 7.1% to 4.3%. The length of stay (LOS) for discharged patients has decreased from a mean of 3.6 to 2.8 hours, with the largest decrease seen in our patients triaged at levels 4 or 5 using the Canadian Emergency Department Triage and Acuity Scale. We noted an improvement in ED patient satisfaction scores following the implementation of Lean principles. Lean manufacturing principles can improve the flow of patients through the ED, resulting in greater patient satisfaction along with reduced time spent by the patient in the ED.

  6. Managing patients' wait time in specialist out-patient clinic using real-time data from existing queue management and ADT systems.

    Science.gov (United States)

    Ju, John Chen; Gan, Soon Ann; Tan Siew Wee, Justine; Huang Yuchi, Peter; Mei Mei, Chan; Wong Mei Mei, Sharon; Fong, Kam Weng

    2013-01-01

    In major cancer centers, heavy patients load and multiple registration stations could cause significant wait time, and can be result in patient complains. Real-time patient journey data and visual display are useful tools in hospital patient queue management. This paper demonstrates how we capture patient queue data without deploying any tracing devices; and how to convert data into useful patient journey information to understand where interventions are likely to be most effective. During our system development, remarkable effort has been spent on resolving data discrepancy and balancing between accuracy and system performances. A web-based dashboard to display real-time information and a framework for data analysis were also developed to facilitate our clinics' operation. Result shows our system could eliminate more than 95% of data capturing errors and has improved patient wait time data accuracy since it was deployed.

  7. Patient perceptions regarding physician reimbursements, wait times, and out-of-pocket payments for anterior cruciate ligament reconstruction in Ontario.

    Science.gov (United States)

    Memon, Muzammil; Ginsberg, Lydia; de Sa, Darren; Nashed, Andrew; Simunovic, Nicole; Phillips, Mark; Denkers, Matthew; Ogilvie, Rick; Peterson, Devin; Ayeni, Olufemi R

    2017-12-01

    Currently, there is a lack of knowledge regarding patient perceptions surrounding physician reimbursements, appropriate wait times, and out-of-pocket payment options for anterior cruciate ligament reconstruction (ACLR). Our objective was to determine the current state of these perceptions in an Ontario setting. A survey was developed and pretested to address patient perceptions about physician reimbursements, appropriate wait times, and out-of-pocket payment options for ACLR using a focus group of experts and by reviewing prior surveys. The survey was administered to patients in a waiting room setting. Two hundred and fifty completed surveys were obtained (79.9% response rate). Participants responded that an appropriate physician reimbursement for ACLR was $1000.00 and that the Ontario Health Insurance Plan (OHIP) reimbursed physicians $700.00 for ACLR. Seventy-four percent of participants responded that the OHIP reimbursement of $615.20 for the procedure was either lower or much lower than what they considered to be an appropriate reimbursement for ACLR. Over 90% of participants responded that an ACLR should occur within 90 days of injury. Thirty-five percent of participants were willing to pay $750.00 out-of-pocket to have an ACLR done sooner, while 16.4% of participants were willing to pay $2500.00 out-of-pocket to travel outside of Canada for expedited surgery. This survey study demonstrates that patients' estimates of both appropriate and actual physician reimbursements were greater than the current reimbursement for ACLR. Further, the majority of individuals report that the surgical fee for ACLR is lower than what they consider to be an appropriate amount of compensation for the procedure. Additionally, nearly all respondents believe that a ruptured ACL should be reconstructed within 90 days of injury. Consequently, a number of patients are willing to pay out-of-pocket for expedited surgery either in Canada or abroad. However, patients' preferences for

  8. Using lean manufacturing principles to evaluate wait times for HIV-positive patients in an urban clinic in Kenya.

    Science.gov (United States)

    Monroe-Wise, Aliza; Reisner, Elizabeth; Sherr, Kenneth; Ojakaa, David; Mbau, Lilian; Kisia, Paul; Muhula, Samuel; Farquhar, Carey

    2017-12-01

    As human immunodeficiency virus (HIV) treatment programs expand in Africa, delivery systems must be strengthened to support patient retention. Clinic characteristics may affect retention, but a relationship between clinic flow and attrition is not established. This project characterized HIV patient experience and flow in an urban Kenyan clinic to understand how these may affect retention. We used Toyota's lean manufacturing principles to guide data collection and analysis. Clinic flow was evaluated using value stream mapping and time and motion techniques. Clinic register data were analyzed. Two focus group discussions were held to characterize HIV patient experience. Results were shared with clinic staff. Wait times in the clinic were highly variable. We identified four main barriers to patient flow: inconsistent patient arrivals, inconsistent staffing, filing system defects, and serving patients out of order. Focus group participants explained how clinic operations affected their ability to engage in care. Clinic staff were eager to discuss the problems identified and identified numerous low-cost potential solutions. Lean manufacturing methodologies can guide efficiency interventions in low-resource healthcare settings. Using lean techniques, we identified bottlenecks to clinic flow and low-cost solutions to improve wait times. Improving flow may result in increased patient satisfaction and retention.

  9. Failure to cope: the hidden curriculum of emergency department wait times and the implications for clinical training.

    Science.gov (United States)

    Webster, Fiona; Rice, Kathleen; Dainty, Katie N; Zwarenstein, Merrick; Durant, Steve; Kuper, Ayelet

    2015-01-01

    The study explored optimal intraprofessional collaboration between physicians in the emergency department (ED) and those from general internal medicine (GIM). Prior to the study, a policy was initiated that mandated reductions in ED wait times. The researchers examined the impact of these changes on clinical practice and trainee education. In 2010-2011, an ethnographic study was undertaken to observe consults between GIM and ED at an urban teaching hospital in Ontario, Canada. Additional ad hoc interviews were conducted with residents, nurses, and faculty from both departments as well as formal one-on-one interviews with 12 physicians. Data were coded and analyzed using concepts of institutional ethnography. Participants perceived that efficiency was more important than education and was in fact the new definition of "good" patient care. The informal label "failure to cope" to describe high-needs patients suggested that in many instances, patients were experienced as a barrier to optimal efficiency. This resulted in tension during consults as well as reduced opportunities for education. The authors suggest that the emphasis on wait times resulted in more importance being placed on "getting the patient out" of the ED than on providing safe, compassionate, person-centered medical care. Resource constraints were hidden within a discourse that shifted the problem of overcrowding in the ED to patients with complex chronic conditions. The term "failure to cope" became activated when overworked physicians tried to avoid assuming care for high-needs patients, masking institutionally produced stress and possibly altering the way patients are perceived.

  10. The waiting time for inter-country spread of pandemic influenza.

    Directory of Open Access Journals (Sweden)

    Peter Caley

    Full Text Available BACKGROUND: The time delay between the start of an influenza pandemic and its subsequent initiation in other countries is highly relevant to preparedness planning. We quantify the distribution of this random time in terms of the separate components of this delay, and assess how the delay may be extended by non-pharmaceutical interventions. METHODS AND FINDINGS: The model constructed for this time delay accounts for: (i epidemic growth in the source region, (ii the delay until an infected individual from the source region seeks to travel to an at-risk country, (iii the chance that infected travelers are detected by screening at exit and entry borders, (iv the possibility of in-flight transmission, (v the chance that an infected arrival might not initiate an epidemic, and (vi the delay until infection in the at-risk country gathers momentum. Efforts that reduce the disease reproduction number in the source region below two and severe travel restrictions are most effective for delaying a local epidemic, and under favourable circumstances, could add several months to the delay. On the other hand, the model predicts that border screening for symptomatic infection, wearing a protective mask during travel, promoting early presentation of cases arising among arriving passengers and moderate reduction in travel volumes increase the delay only by a matter of days or weeks. Elevated in-flight transmission reduces the delay only minimally. CONCLUSIONS: The delay until an epidemic of pandemic strain influenza is imported into an at-risk country is largely determined by the course of the epidemic in the source region and the number of travelers attempting to enter the at-risk country, and is little affected by non-pharmaceutical interventions targeting these travelers. Short of preventing international travel altogether, eradicating a nascent pandemic in the source region appears to be the only reliable method of preventing country-to-country spread of a

  11. Modeling the impact of integrating HIV and outpatient health services on patient waiting times in an urban health clinic in Zambia.

    Directory of Open Access Journals (Sweden)

    Sarang Deo

    Full Text Available Rapid scale up of HIV treatment programs in sub-Saharan Africa has refueled the long-standing health policy debate regarding the merits and drawbacks of vertical and integrated system. Recent pilots of integrating outpatient and HIV services have shown an improvement in some patient outcomes but deterioration in waiting times, which can lead to worse health outcomes in the long run.A pilot intervention involving integration of outpatient and HIV services in an urban primary care facility in Lusaka, Zambia was studied. Data on waiting time of patients during two seven-day periods before and six months after the integration were collected using a time and motion study. Statistical tests were conducted to investigate whether the two observation periods differed in operational details such as staffing, patient arrival rates, mix of patients etc. A discrete event simulation model was constructed to facilitate a fair comparison of waiting times before and after integration. The simulation model was also used to develop alternative configurations of integration and to estimate the resulting waiting times.Comparison of raw data showed that waiting times increased by 32% and 36% after integration for OPD and ART patients respectively (p<0.01. Using simulation modeling, we found that a large portion of this increase could be explained by changes in operational conditions before and after integration such as reduced staff availability (p<0.01 and longer breaks between consecutive patients (p<0.05. Controlling for these differences, integration of services, per se, would have resulted in a significant decrease in waiting times for OPD and a moderate decrease for HIV services.Integrating health services has the potential of reducing waiting times due to more efficient use of resources. However, one needs to ensure that other operational factors such as staff availability are not adversely affected due to integration.

  12. Fractional Fokker-Planck equation with tempered α-stable waiting times: langevin picture and computer simulation.

    Science.gov (United States)

    Gajda, Janusz; Magdziarz, Marcin

    2010-07-01

    In this paper we introduce a Langevin-type model of subdiffusion with tempered α-stable waiting times. We consider the case of space-dependent external force fields. The model displays subdiffusive behavior for small times and it converges to standard Gaussian diffusion for large time scales. We derive general properties of tempered anomalous diffusion from the theory of tempered α-stable processes, in particular we find the form of the fractional Fokker-Planck equation corresponding to the tempered subdiffusion. We also construct an algorithm of simulation of sample paths of the introduced process. We apply the algorithm to approximate solutions of the fractional Fokker-Planck equation and to study statistical properties of the tempered subdiffusion via Monte Carlo methods.

  13. The current duration design for estimating the time to pregnancy distribution

    DEFF Research Database (Denmark)

    Gasbarra, Dario; Arjas, Elja; Vehtari, Aki

    2015-01-01

    times are only rarely selected into the sample of current durations, and this renders their estimation unstable. We introduce here a Bayesian method for this estimation problem, prove its asymptotic consistency, and compare the method to some variants of the non-parametric maximum likelihood estimators......This paper was inspired by the studies of Niels Keiding and co-authors on estimating the waiting time-to-pregnancy (TTP) distribution, and in particular on using the current duration design in that context. In this design, a cross-sectional sample of women is collected from those who are currently...... attempting to become pregnant, and then by recording from each the time she has been attempting. Our aim here is to study the identifiability and the estimation of the waiting time distribution on the basis of current duration data. The main difficulty in this stems from the fact that very short waiting...

  14. Analysis and prediction of effects of the Manchester Triage System on patient waiting times in an emergency department by means of agent-based simulation

    Directory of Open Access Journals (Sweden)

    Schaaf, Michael

    2014-02-01

    Full Text Available [english] A simulation of complex clinical processes is a challenging task and suitable methods need to be found which can capture the influence of relevant factors and their relationships. The Manchester triage system (MTS is widely used in German emergency departments (ED, however the impact on patient waiting times remain difficult to predict. The purpose of this work is the assessment of MTS particularly with regard to the waiting times of different degrees of severity. The methodology of agent based simulation was found suitable for the ED domain and the agent based simulation tool SeSAm was chosen due to its intuitive user interface and easy adaption of the simulation models. Altogether four agent classes could be implemented based on the information derived from a process model. The model permits a dynamic simulation of the ED processes and a reliable assessment of patient waiting times. In addition, the implementation of a triage nurse allowed the simulation of the triage process and a direct comparison to the current state without a standardized triage procedure. Essential influencing factors (e.g. number of patients, manning level were implemented and their effects on the ED processes and patient waiting times assessed. The simulation runs delivered correct results based on the underlying process model and the collected statistical data. The process flow and the waiting times of an ED could be mapped exactly. In all simulation runs the waiting times of high triage levels (MTS-levels 1 and 2 could be reduced. Especially patients of MTS-level 2 in the waiting area of the ED benefit significantly from the implementation of a standardized triage procedure and the associated permanent monitoring.

  15. Evaluating wait times from screening to breast cancer diagnosis among women undergoing organised assessment vs usual care.

    Science.gov (United States)

    Chiarelli, Anna M; Muradali, Derek; Blackmore, Kristina M; Smith, Courtney R; Mirea, Lucia; Majpruz, Vicky; O'Malley, Frances P; Quan, May Lynn; Holloway, Claire Mb

    2017-05-09

    Timely coordinated diagnostic assessment following an abnormal screening mammogram reduces patient anxiety and may optimise breast cancer prognosis. Since 1998, the Ontario Breast Screening Program (OBSP) has offered organised assessment through Breast Assessment Centres (BACs). For OBSP women seen at a BAC, an abnormal mammogram is followed by coordinated referrals through the use of navigators for further imaging, biopsy, and surgical consultation as indicated. For OBSP women seen through usual care (UC), further diagnostic imaging is arranged directly from the screening centre and/or through their physician; results must be communicated to the physician who is then responsible for arranging any necessary biopsy and/or surgical consultation. This study aims to evaluate factors associated with diagnostic wait times for women undergoing assessment through BAC and UC. Of the 2 147 257 women aged 50-69 years screened in the OBSP between 1 January 2002 and 31 December 2009, 155 866 (7.3%) had an abnormal mammogram. A retrospective design identified two concurrent cohorts of women diagnosed with screen-detected breast cancer at a BAC (n=4217; 47%) and UC (n=4827; 53%). Multivariable logistic regression analyses examined associations between wait times and assessment and prognostic characteristics by pathway. A two-sided 5% significance level was used. Screened women with breast cancer were two times more likely to be diagnosed within 7 weeks when assessed through a BAC vs UC (OR=1.91, 95% CI=1.73-2.10). In addition, compared with UC, women assessed through a BAC were significantly more likely to have their first assessment procedure within 3 weeks of their abnormal mammogram (OR=1.25, 95% CI=1.12-1.39), ⩽3 assessment procedures (OR=1.54, 95% CI=1.41-1.69), ⩽2 assessment visits (OR=1.86, 95% CI=1.70-2.05), and ⩾2 procedures per visit (OR=1.41, 95% CI=1.28-1.55). Women diagnosed through a BAC were also more likely than those in UC to have imaging (OR=1.99, 95

  16. Toward Implementing Patient Flow in a Cancer Treatment Center to Reduce Patient Waiting Time and Improve Efficiency.

    Science.gov (United States)

    Suss, Samuel; Bhuiyan, Nadia; Demirli, Kudret; Batist, Gerald

    2017-06-01

    Outpatient cancer treatment centers can be considered as complex systems in which several types of medical professionals and administrative staff must coordinate their work to achieve the overall goals of providing quality patient care within budgetary constraints. In this article, we use analytical methods that have been successfully employed for other complex systems to show how a clinic can simultaneously reduce patient waiting times and non-value added staff work in a process that has a series of steps, more than one of which involves a scarce resource. The article describes the system model and the key elements in the operation that lead to staff rework and patient queuing. We propose solutions to the problems and provide a framework to evaluate clinic performance. At the time of this report, the proposals are in the process of implementation at a cancer treatment clinic in a major metropolitan hospital in Montreal, Canada.

  17. Waiting for scheduled surgery: A complex patient experience.

    Science.gov (United States)

    Carr, Tracey; Teucher, Ulrich; Casson, Alan G

    2017-03-01

    The aim of this study was to understand experiences of wait time among patients awaiting scheduled orthopaedic or cardiac surgery. Using a qualitative approach, 32 patients completed two interviews each regarding their wait time experiences, including effects of waiting. Patient experiences of wait time varied regardless of actual wait time and included reports of restriction, uncertainty, resignation, coping and opportunity. Participants' waiting experiences indicate a complex relationship between greater symptom severity and less tolerance for wait time. We suggest healthcare resources focus on alleviating the deleterious effects of waiting for certain patients rather than reducing absolute wait times.

  18. Distributed space-time coding

    CERN Document Server

    Jing, Yindi

    2014-01-01

    Distributed Space-Time Coding (DSTC) is a cooperative relaying scheme that enables high reliability in wireless networks. This brief presents the basic concept of DSTC, its achievable performance, generalizations, code design, and differential use. Recent results on training design and channel estimation for DSTC and the performance of training-based DSTC are also discussed.

  19. Waiting experience in railway environments

    NARCIS (Netherlands)

    van Hagen, M.; Galetzka, Mirjam; Pruyn, Adriaan T.H.

    2014-01-01

    At railway stations, waiting time is usually an unavoidable aspect of the journey for train passengers. According to the attentional model of time, pleasant surroundings and other forms of distraction reduce perceived waiting time. Not every individual reacts identically in the same surroundings.

  20. Improvement in obstructive sleep apnea diagnosis and management wait times: A retrospective analysis of home management pathway for obstructive sleep apnea.

    Science.gov (United States)

    Stewart, Samuel Alan; Skomro, Robert; Reid, John; Penz, Erika; Fenton, Mark; Gjevre, John; Cotton, David

    2015-01-01

    Obstructive sleep apnea is a common condition within the Canadian population. The current gold standard for diagnosis and management of patients is in-laboratory (in-lab) polysomnography; however, the limited availability of testing options for patients has led to long wait times and increased disease burden within the population. The Sleep Research Laboratory in Saskatoon (Saskatchewan) implemented a home management program to run in parallel with the in-lab system several years ago in an effort to increase their capacity and reduce wait times. The present study was a retrospective analysis of all patients referred to the program between 2009 and 2012. The home management system has improved wait times by diagnosing and managing up to one-half of the referred patient population, reducing the wait for in-lab treatment from a median of 152 days in 2009 to 92 days in 2012 (Pmanagement can provide a viable alternative to in-lab testing for patients who meet strict entry criteria, reducing the in-lab workload and, ultimately, reducing wait times.

  1. Improvement in Obstructive Sleep Apnea Diagnosis and Management Wait Times: A Retrospective Analysis of a Home Management Pathway for Obstructive Sleep Apnea

    Directory of Open Access Journals (Sweden)

    Samuel Alan Stewart

    2015-01-01

    Full Text Available Obstructive sleep apnea is a common condition within the Canadian population. The current gold standard for diagnosis and management of patients is in-laboratory (in-lab polysomnography; however, the limited availability of testing options for patients has led to long wait times and increased disease burden within the population. The Sleep Research Laboratory in Saskatoon (Saskatchewan implemented a home management program to run in parallel with the in-lab system several years ago in an effort to increase their capacity and reduce wait times. The present study was a retrospective analysis of all patients referred to the program between 2009 and 2012. The home management system has improved wait times by diagnosing and managing up to one-half of the referred patient population, reducing the wait for in-lab treatment from a median of 152 days in 2009 to 92 days in 2012 (P<0.0001. Moving forward, home management can provide a viable alternative to in-lab testing for patients who meet strict entry criteria, reducing the in-lab workload and, ultimately, reducing wait times.

  2. Cost-Effectiveness of Reduced Waiting Time for Head and Neck Cancer Patients due to a Lean Process Redesign.

    Science.gov (United States)

    Simons, Pascale A M; Ramaekers, Bram; Hoebers, Frank; Kross, Kenneth W; Marneffe, Wim; Pijls-Johannesma, Madelon; Vandijck, Dominique

    2015-07-01

    Compared with new technologies, the redesign of care processes is generally considered less attractive to improve patient outcomes. Nevertheless, it might result in better patient outcomes, without further increasing costs. Because early initiation of treatment is of vital importance for patients with head and neck cancer (HNC), these care processes were redesigned. This study aimed to assess patient outcomes and cost-effectiveness of this redesign. An economic (Markov) model was constructed to evaluate the biopsy process of suspicious lesion under local instead of general anesthesia, and combining computed tomography and positron emission tomography for diagnostics and radiotherapy planning. Patients treated for HNC were included in the model stratified by disease location (larynx, oropharynx, hypopharynx, and oral cavity) and stage (I-II and III-IV). Probabilistic sensitivity analyses were performed. Waiting time before treatment start reduced from 5 to 22 days for the included patient groups, resulting in 0.13 to 0.66 additional quality-adjusted life-years. The new workflow was cost-effective for all the included patient groups, using a ceiling ratio of €80,000 or €20,000. For patients treated for tumors located at the larynx and oral cavity, the new workflow resulted in additional quality-adjusted life-years, and costs decreased compared with the regular workflow. The health care payer benefited €14.1 million and €91.5 million, respectively, when individual net monetary benefits were extrapolated to an organizational level and a national level. The redesigned care process reduced the waiting time for the treatment of patients with HNC and proved cost-effective. Because care improved, implementation on a wider scale should be considered. Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

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

    Data.gov (United States)

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

  4. Speeding Products to Market: Waiting Time to First Product Introduction in New Firms.

    Science.gov (United States)

    Schoonhoven, Claudia Bird; And Others

    1990-01-01

    Using event-history analysis techniques, a longitudinal study of the semiconductor industry found that substantial technological innovation lengthens development times and reduces the speed with which first products reach the marketplace. Organizations that undertook lower levels of technological innovation had relatively lower monthly…

  5. Investigating the Relationship between Customer Wait Time and Operational Availability through Simulation Modeling

    Science.gov (United States)

    2012-12-01

    large jug of sweet tea), Mr. Darrell Waters, and Major Huntley Bodden from Marine Corps Logistics Command for their expert knowledge and data that made...ensure operability of equipment, Combat Essentiality Codes (CEC) are assigned to each NSN to identify its criticality. Filtering requisition data by...requisitions for all AAVs in I MEF during the 2009 – 2011 time period. When we filtered the data to only include deadlining maintenance actions, we

  6. Spatio-Temporally Adaptive Waiting Time for Cell Phone Sensor Networks

    OpenAIRE

    Deepthi Chander; Bhushan Jagyasi; Desai, U. B.; Merchant, S N

    2011-01-01

    In cell phone sensor networks (CpSN), sensor-embedded cell phones communicate sensor data using Near Field Communication outlets such as Wi-Fi or Bluetooth. This paper considers a query dissemination application of CpSN, where sensor data belonging to a certain time window [ts,min, ts,max] is needed from a region of interest. Existing approaches, such as ADAPT, use adaptive broadcast ranges at the Wireless Access Point (WAP) for query dissemination. This paper proposes the adaptation of waiti...

  7. Real-Time Wait-Free Queues using Micro-Transactions

    DEFF Research Database (Denmark)

    Meawad, Fadi; Iyer, Karthik; Schoeberl, Martin

    2011-01-01

    This paper evaluates the applicability of transactional mem- ory to the implementation of dierent non-blocking data structures in the context of the Real-time Specication for Java. In particular, we argue that hardware support for micro-transaction allows us to implement eciently data structures...... that are often dicult to realize with the atomic operations provided by stock hardware. Our main imple- mentation platform is the Java Optimized Processor sys- tem. We report on the performance of data structures imple- mented with locks, compare and swap and micro-transactions. Our results conrm...... that transactional memory is an inter- esting alternative to traditional concurrency control mecha- nisms....

  8. Waiting time to radiotherapy as a prognostic factor for glioblastoma patients in a scenario of medical disparities

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, Luiz Victor Maia; Callegaro-Filho, Donato; Koch, Ludmila de Oliveira; Weltman, Eduardo; Victor, Elivane da Silva; Malheiros, Suzana Maria Fleury, E-mail: lvmaia@gmail.com [Hospital Israelita Albert Einstein, Sao Paulo, SP (Brazil); Santos, Adrialdo Jose; Borges, Lia Raquel Rodrigues; Segreto, Roberto Araujo [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil). Escola paulista de Medicina; Pontes, Luciola de Barros [Hospital do Coracao, Sao Paulo, SP (Brazil). Dept. de Oncologia

    2015-02-15

    Objective: to evaluate the effect of waiting time (WT) to radiotherapy (RT) on overall survival (OS) of glioblastoma (GBM) patients as a reliable prognostic variable in Brazil, a scenario of medical disparities. Method: retrospective study of 115 GBM patients from two different health-care institutions (one public and one private) in Brazil who underwent post-operative RT. Results: Median WT to RT was 6 weeks (range,1.3-17.6). The median OS for WT ≤ 6 weeks was 13.5 months (95%CI , 9.1-17.9) and for WT . 6 weeks was 14.2 months (95%CI, 11.2-17.2) (HR 1.165, 95%CI 0.770-1.762; p = 0.470). In the multivariate analysis, the variables associated with survival were KPS (p , 0.001), extent of resection (p = 0.009) and the adjuvant treatment (p = 0.001). The KPS interacted with WT to RT (HR 0.128, 95%CI 0.034-0.476; p = 0.002), showing that the benefit of KPS on OS depends on the WT to RT. Conclusion: no prognostic impact of WT to RT could be detected on the OS. Although there are no data to ensure that delays to RT are tolerable, we may reassure patients that the time-length to initiate treatment does not seem to influence the control of the disease, particularly in face of other prognostic factors. (author)

  9. The Effect of the Transition to Home Monitoring for the Diagnosis of OSAS on Test Availability, Waiting Time, Patients’ Satisfaction, and Outcome in a Large Health Provider System

    Directory of Open Access Journals (Sweden)

    Ahmad Safadi

    2014-01-01

    Full Text Available During 2009, the Haifa district of Clalit Health Services (CHS has switched from in-lab polysomnography (PSG to home studies for the diagnosis of obstructive sleep apnea (OSA. We assessed the effects of this change on accessibility, waiting time, satisfaction, costs, and CPAP purchase by the patients. Data regarding sleep studies, CPAP purchase, and waiting times were collected retrospectively from the computerized database of CHS. Patients’ satisfaction was assessed utilizing a telephone questionnaire introduced to a randomized small sample of 70 patients. Comparisons were made between 2007 and 2008 (in-lab PSGs and 2010 and 2011 (when most studies were ambulatory. Of about 650000 insured individuals in the Haifa district of CHS, 1471 sleep studies were performed during 2007-2008 compared to 2794 tests during 2010-2011. The average waiting time was 9.9 weeks in 2007-2008 compared to 1.1 weeks in 2010-2011 (P<0.05. 597 CPAPs were purchased in 2007-2008 compared to 831 in 2010-2011. The overall patients’ satisfaction was similar, but discomfort tended to be higher in the in-laboratory group (4.1 vs 2.7 in a scale of 0–10; P=0.11. Switching to ambulatory diagnosis improved the test accessibility and reduced the waiting times. Patients’ satisfaction remained similarly high. The total direct cost of OSA management was reduced.

  10. Waiting time - an offence?

    DEFF Research Database (Denmark)

    Ludvigsen, Mette Spliid

    2004-01-01

    fieldwork is set up consisting of participant observation and interviews.   Based on the qualitative analysis completed to date on a data set consisting of field notes from participant observations and informal interviews I explore patients' social interactions in their day-to-day lives on two adult...

  11. The distribution of first-passage times and durations in FOREX and future markets

    Science.gov (United States)

    Sazuka, Naoya; Inoue, Jun-ichi; Scalas, Enrico

    2009-07-01

    Possible distributions are discussed for intertrade durations and first-passage processes in financial markets. The view-point of renewal theory is assumed. In order to represent market data with relatively long durations, two types of distributions are used, namely a distribution derived from the Mittag-Leffler survival function and the Weibull distribution. For the Mittag-Leffler type distribution, the average waiting time (residual life time) is strongly dependent on the choice of a cut-off parameter tmax, whereas the results based on the Weibull distribution do not depend on such a cut-off. Therefore, a Weibull distribution is more convenient than a Mittag-Leffler type if one wishes to evaluate relevant statistics such as average waiting time in financial markets with long durations. On the other hand, we find that the Gini index is rather independent of the cut-off parameter. Based on the above considerations, we propose a good candidate for describing the distribution of first-passage time in a market: The Weibull distribution with a power-law tail. This distribution compensates the gap between theoretical and empirical results more efficiently than a simple Weibull distribution. It should be stressed that a Weibull distribution with a power-law tail is more flexible than the Mittag-Leffler distribution, which itself can be approximated by a Weibull distribution and a power-law. Indeed, the key point is that in the former case there is freedom of choice for the exponent of the power-law attached to the Weibull distribution, which can exceed 1 in order to reproduce decays faster than possible with a Mittag-Leffler distribution. We also give a useful formula to determine an optimal crossover point minimizing the difference between the empirical average waiting time and the one predicted from renewal theory. Moreover, we discuss the limitation of our distributions by applying our distribution to the analysis of the BTP future and calculating the average waiting

  12. Quality of hub-and-spoke networks; the effects of time-table co-ordination on waiting time and rescheduling time

    NARCIS (Netherlands)

    Brons, M.R.E.; Rietveld, P.

    2001-01-01

    Low frequencies of aircraft may have substantial negative effects on scheduling costs and waiting costs at hub airports. Appropriate timetabling of carriers will reduce these costs. In this paper we propose a measure for the quality of the co-ordination of timetables by carriers in hub airports. An

  13. Correlation analysis for energy losses, waiting times and durations of type I edge-localized modes in the Joint European Torus

    Science.gov (United States)

    Shabbir, A.; Verdoolaege, G.; Hornung, G.; Kardaun, O. J. W. F.; Zohm, H.; Contributors, JET

    2017-03-01

    Several important ELM control techniques are in large part motivated by the empirically observed inverse relationship between average ELM energy loss and ELM frequency in a plasma. However, to ensure a reliable effect on the energy released by the ELMs, it is important that this relation is verified for individual ELM events. Therefore, in this work the relation between ELM energy loss ≤ft({{W}\\text{ELM}}\\right) and waiting time ≤ft(Δ {{t}\\text{ELM}}\\right) is investigated for individual ELMs in a set of ITER-like wall plasmas in JET. A comparison is made with the results from a set of carbon-wall and nitrogen-seeded ITER-like wall JET plasmas. It is found that the correlation between W ELM and Δ {{t}\\text{ELM}} for individual ELMs varies from strongly positive to zero. Furthermore, the effect of the extended collapse phase often accompanying ELMs from unseeded JET ILW plasmas and referred to as the slow transport event (STE) is studied on the distribution of ELM durations, and on the correlation between W ELM and Δ {{t}\\text{ELM}} . A high correlation between W ELM and Δ {{t}\\text{ELM}} , comparable to CW plasmas is only found in nitrogen-seeded ILW plasmas. Finally, a regression analysis is performed using plasma engineering parameters as predictors for determining the region of the plasma operational space with a high correlation between W ELM and Δ {{t}\\text{ELM}} .

  14. Ambulatory health service users' experience of waiting time and expenditure and factors associated with the perception of low quality of care in Mexico.

    Science.gov (United States)

    Sauceda-Valenzuela, Alma Lucila; Wirtz, Veronika J; Santa-Ana-Téllez, Yared; de la Luz Kageyama-Escobar, Maria

    2010-06-23

    A principal reason for low use of public health care services is the perception of inferior quality of care. Studying health service user (HSU) experiences with their care and their perception of health service quality is critical to understanding health service utilization. The aim of this study was to define reference points for some aspects of health care quality and to analyze which HSU experiences resulted in perceptions of overall low quality of care. Data from the National Health Survey 2006 were used to compare the experiences of HSUs with their ambulatory care at Ministry of Health and affiliated institutions (MOH), social security institutions (SSI) and private institutions (PrivI). Reference points of quality of care related to waiting time and expenditure were defined for each of the three types of institutions by analyzing HSU experiences rated as 'acceptable'. A multivariable logistic regression model was used to identify the principal factors associated with the general perception of low quality of care. A total of 11,959 HSUs were included in the analysis, of whom 37.6% (n = 4,500) HSUs received care at MOH facilities; 31.2% (n = 3,730) used SSI and 31.2% (n = 3,729) PrivI. An estimated travel and waiting time of 10 minutes respectively was rated as acceptable by HSUs from all institutions. The differences between the waiting time rated as acceptable and the actual waiting time were the largest for SSI (30 min) in comparison to MoH (20 min) and PrivI (5 min) users. The principal factors associated with an overall perception of low quality of care are type of institution (OR 4.36; 95% CI 2.95-6.44), waiting time (OR 3.20; 95% CI 2.35-4.35), improvement of health after consultation (OR 2.93; CI 2.29-3.76) and consultation length of less than 20 minutes (2.03; 95% CI 1.60-2.57). The reference points derived by the HSUs' own ratings are useful in identifying where quality improvements are required. Prioritizing the reduction of waiting times and

  15. Ambulatory health service users' experience of waiting time and expenditure and factors associated with the perception of low quality of care in Mexico

    Directory of Open Access Journals (Sweden)

    Santa-Ana-Téllez Yared

    2010-06-01

    Full Text Available Abstract Background A principal reason for low use of public health care services is the perception of inferior quality of care. Studying health service user (HSU experiences with their care and their perception of health service quality is critical to understanding health service utilization. The aim of this study was to define reference points for some aspects of health care quality and to analyze which HSU experiences resulted in perceptions of overall low quality of care. Methods Data from the National Health Survey 2006 were used to compare the experiences of HSUs with their ambulatory care at Ministry of Health and affiliated institutions (MOH, social security institutions (SSI and private institutions (PrivI. Reference points of quality of care related to waiting time and expenditure were defined for each of the three types of institutions by analyzing HSU experiences rated as 'acceptable'. A multivariable logistic regression model was used to identify the principal factors associated with the general perception of low quality of care. Results A total of 11,959 HSUs were included in the analysis, of whom 37.6% (n = 4,500 HSUs received care at MOH facilities; 31.2% (n = 3,730 used SSI and 31.2% (n = 3,729 PrivI. An estimated travel and waiting time of 10 minutes respectively was rated as acceptable by HSUs from all institutions. The differences between the waiting time rated as acceptable and the actual waiting time were the largest for SSI (30 min in comparison to MoH (20 min and PrivI (5 min users. The principal factors associated with an overall perception of low quality of care are type of institution (OR 4.36; 95% CI 2.95-6.44, waiting time (OR 3.20; 95% CI 2.35-4.35, improvement of health after consultation (OR 2.93; CI 2.29-3.76 and consultation length of less than 20 minutes (2.03; 95% CI 1.60-2.57. Conclusions The reference points derived by the HSUs' own ratings are useful in identifying where quality improvements are required

  16. A renal colic fast track pathway to improve waiting times and outcomes for patients presenting to the emergency department

    Directory of Open Access Journals (Sweden)

    Al Kadhi O

    2017-07-01

    Full Text Available Omar Al Kadhi,1 Kate Manley,1 Madhavi Natarajan,1 Valmiki Lutchmedial,2 Abbi Forsyth,2 Kate Tabrett,2 Jonathan Betteridge,2 William Finch,3 Heinrich Hollis4 1Department of Urology, Norfolk and Norwich University Hospitals NHS Foundation Trust, 2Faculty of Medicine and Health Sciences, University of East Anglia, 3Department of Urology, 4Department of Emergency Medicine, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK Introduction: Renal colic is commonly encountered in the emergency department (ED. We validated a fast track renal colic (FTRC initiative to decrease patient waiting times and streamline patient flow.Method: The FTRC pathway was devised according to the National Institute for Health and Care Excellence clinical summary criteria for the management of patients with suspected renal colic. ED triage nurses use the pathway to identify patients with likely renal colic suitable for fast track to analgesia, investigation and management. Investigations, diagnosis and patient demographics were recorded for 1157 consecutive patients coded as renal colic at a single-center ED over 12 months.Results: Three hundred and two patients were suitable for the FTRC pathway (26.1%, while 855 were seen by the ED clinicians prior to onward referral. Also, 83.9% of patients underwent computed tomography scan. In the FTRC group, 57.3% of patients had radiologically confirmed calculi versus 53.8% in the non-FTRC group (p=0.31. Alternative diagnoses among FTRC patients (2.6% included ovarian pathology (n=1, diverticulitis (n=2 and incidental renal cell carcinoma (n=2, while 26.1% had no identifiable pathology. No immediately life-threatening diagnoses were identified on imaging. Computed tomography scans performed in the non-FTRC group identified two ruptured abdominal aortic aneurysms and alternative diagnoses (2.57% including ovarian pathology (n=7, cholecystitis (n=2, incidental renal cell carcinoma (n=3 and inflammatory bowel

  17. Cardiac EASE (Ensuring Access and Speedy Evaluation) – the impact of a single-point-of-entry multidisciplinary outpatient cardiology consultation program on wait times in Canada

    Science.gov (United States)

    Bungard, Tammy J; Smigorowsky, Marcie J; Lalonde, Lucille D; Hogan, Terry; Doliszny, Katharine M; Gebreyesus, Ghirmay; Garg, Sipi; Archer, Stephen L

    2009-01-01

    BACKGROUND: Universal access to health care is valued in Canada but increasing wait times for services (eg, cardiology consultation) raise safety questions. Observations suggest that deficiencies in the process of care contribute to wait times. Consequently, an outpatient clinic was designed for Ensuring Access and Speedy Evaluation (Cardiac EASE) in a university group practice, providing cardiac consultative services for northern Alberta. Cardiac EASE has two components: a single-point-of-entry intake service (prospective testing using physician-approved algorithms and previsit triage) and a multidisciplinary clinic (staffed by cardiologists, nurse practitioners and doctoral-trained pharmacists). OBJECTIVES: It was hypothesized that Cardiac EASE would reduce the time to initial consultation and a definitive diagnosis, and also increase the referral capacity. METHODS: The primary and secondary outcomes were time from referral to initial consultation, and time to achieve a definitive diagnosis and management plan, respectively. A conventionally managed historical control group (three-month pre-EASE period in 2003) was compared with the EASE group (2004 to 2006). The conventional referral mechanism continued concurrently with EASE. RESULTS: A comparison between pre-EASE (n=311) and EASE (n=3096) revealed no difference in the mean (± SD) age (60±16 years), sex (55% and 52% men, respectively) or reason for referral, including chest pain (31% and 40%, respectively) and arrhythmia (27% and 29%, respectively). Cardiac EASE reduced the time to initial cardiac consultation (from 71±45 days to 33±19 days) and time to a definitive diagnosis (from 120±86 days to 51±58 days) (P<0.0001). The annual number of new referrals increased from 1512 in 2002 to 2574 in 2006 due to growth in the Cardiac EASE clinic. The number of patients seen through the conventional referral mechanism and their wait times remained constant during the study period. CONCLUSIONS: Cardiac EASE reduced

  18. Waiting for a hand: saccadic reaction time increases in proportion to hand reaction time when reaching under a visuomotor reversal

    Directory of Open Access Journals (Sweden)

    Irene eArmstrong

    2013-07-01

    Full Text Available Although eye movement onset typically precedes hand movement onset when reaching to targets presented in peripheral vision, arm motor commands appear to be issued at around the same time, and possibly in advance, of eye motor commands. A fundamental question, therefore, is whether eye movement initiation is linked or yoked to hand movement. We addressed this issue by having participants reach to targets after adapting to a visuomotor reversal (or 180° rotation between the position of the unseen hand and the position of a cursor controlled by the hand. We asked whether this reversal, which we expected to increase hand reaction time (HRT, would also increase saccadic reaction time (SRT. As predicted, when moving the cursor to targets under the reversal, HRT increased in all participants. SRT also increased in all but one participant, even though the task for the eyes – shifting gaze to the target – was unaltered by the reversal of hand position feedback. Moreover, the effects of the reversal on SRT and HRT were positively correlated across participants; those who exhibited the greatest increases in HRT also showed the greatest increases in SRT. These results indicate that the mechanisms underlying the initiation of eye and hand movements are linked. In particular, the results suggest that the initiation of an eye movement to a manual target depends, at least in part, on the specification of hand movement.

  19. Waiting when hospitalised

    DEFF Research Database (Denmark)

    Ludvigsen, Mette Spliid

    2004-01-01

    , and interpret the meaning of having fellow-patients during hospitalisation. Three main dimensions are explored; attitudes toward own illness, interpersonal relationships and environmental factors. Questions such as how do patients pass time, find out about illnesses, examinations, treatment, and staff members...... increasingly important in today's health care environment. The indicative conclusions form this study suggest that nurses play an important role in ensuring that patients are satisfied and receive quality care when waiting....

  20. ¿Ha llegado la hora de la gestión de las listas de espera? Has the time arrived for the management of waiting lists?

    Directory of Open Access Journals (Sweden)

    E. Bernal

    2002-10-01

    Full Text Available Las personas que ocupan una lista de espera sufren a menudo un riesgo adicional derivado del tiempo que pasa hasta que obtienen tratamiento; sin embargo, en otras ocasiones, las personas en lista no tienen necesidad del tratamiento por el que esperan. Ambos argumentos, contrastables con evidencias empíricas, serían suficientes para afirmar que debe llegar la gestión a las listas de espera dejando a un lado políticas más o menos oportunistas. Por políticas oportunistas se entiende mantener la mala información sobre listas o su "maquillaje", utilizar programas de autoconcertación sin más horizonte que llegar a final de año sin lista de más de seis meses, etcétera. El panorama no es del todo oscuro. Algunas iniciativas de gestión (incluso de Política con mayúscula se van abriendo paso y pueden entrar en la agenda de los próximos años. Así, cabe destacar la aplicación de tiempos de atención garantizada o la priorización de las listas en función de criterios explícitos. En todo caso, conviene recordar que, con la excepción de las colas producidas en las salas de espera de los centros de salud y aquéllas que se producen en las puertas de urgencias, el resto de colas del sistema están mediadas por la decisión de un médico. Así que una estrategia ineludible para gestionar las listas de espera consiste en atenuar los problemas derivados de la incertidumbre (o ignorancia con respecto al diagnóstico o al pronóstico de los pacientes.Individuals on the waiting list frequently suffer an additional risk caused by the mean time until they receive treatment; however, other individuals do not need the treatment for which they are waiting. Both arguments, which can be contrasted with empirical evidence, would be sufficient to affirm that waiting list management should be implemented, leaving aside policies that are more of less opportunistic. Opportunistic policies are understood as those providing misinformation on waiting lists or

  1. Reducing Patient Waiting Times for Radiation Therapy and Improving the Treatment Planning Process: a Discrete-event Simulation Model (Radiation Treatment Planning).

    Science.gov (United States)

    Babashov, V; Aivas, I; Begen, M A; Cao, J Q; Rodrigues, G; D'Souza, D; Lock, M; Zaric, G S

    2017-06-01

    We analysed the radiotherapy planning process at the London Regional Cancer Program to determine the bottlenecks and to quantify the effect of specific resource levels with the goal of reducing waiting times. We developed a discrete-event simulation model of a patient's journey from the point of referral to a radiation oncologist to the start of radiotherapy, considering the sequential steps and resources of the treatment planning process. We measured the effect of several resource changes on the ready-to-treat to treatment (RTTT) waiting time and on the percentage treated within a 14 calendar day target. Increasing the number of dosimetrists by one reduced the mean RTTT by 6.55%, leading to 84.92% of patients being treated within the 14 calendar day target. Adding one more oncologist decreased the mean RTTT from 10.83 to 10.55 days, whereas a 15% increase in arriving patients increased the waiting time by 22.53%. The model was relatively robust to the changes in quantity of other resources. Our model identified sensitive and non-sensitive system parameters. A similar approach could be applied by other cancer programmes, using their respective data and individualised adjustments, which may be beneficial in making the most effective use of limited resources. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  2. Waiting for permission to enter the labour ward world: first time parents' experiences of the first encounter on a labour ward.

    Science.gov (United States)

    Nyman, Viola; Downe, Soo; Berg, Marie

    2011-08-01

    For women and their partners, the first meeting with professional staff on the labour ward is important. This initial encounter is a short but sensitive meeting. It may be particularly crucial for first time parents, most of whom have no prior experience of the birth environment. The objective of this study was to explore the meaning of first time mothers' and their partners' first encounter with midwives and other maternity care staff when they arrive on a hospital labour ward. A hermeneutic, reflective lifeworld research approach was chosen to identify patterns of meanings, comprehension and explanations. Participants from Western Sweden were interviewed in the postnatal period; 37 individually, and 28 in focus groups. Four themes were identified: 'timing it right ', 'waiting to be informed', 'being in an inferior position', and 'facing reality with a mosaic of emotions'. The final interpretation of the phenomenon is captured as 'waiting for permission to enter the labour ward world'. The findings demonstrate the parents' efforts trying to determine the appropriateness of arrival to the labour ward. An asymmetric power relationship was expressed in the obedient acceptance of the waiting for attention in an unfamiliar situation. These findings suggest that the labour ward entry process is not parent centred. As entry to the labour ward sets the tone for the rest of the birth, this period in the labour process needs more attention in future research and practice from the maternity care professionals perspective. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Distributed synthesis in continuous time

    DEFF Research Database (Denmark)

    Hermanns, Holger; Krčál, Jan; Vester, Steen

    2016-01-01

    . The flow of time is modelled explicitly based on continuous-time randomness, with two natural implications: First, the non-determinism stemming from interleaving disappears. Second, when we restrict to a subclass of non-urgent models, the quantitative value problem for two players can be solved in EXPTIME....... Indeed, the explicit continuous time enables players to communicate their states by delaying synchronisation (which is unrestricted for non-urgent models). In general, the problems are undecidable already for two players in the quantitative case and three players in the qualitative case. The qualitative...

  4. Real-time modeling of heat distributions

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, Hendrik F.; Li, Hongfei; Yarlanki, Srinivas

    2018-01-02

    Techniques for real-time modeling temperature distributions based on streaming sensor data are provided. In one aspect, a method for creating a three-dimensional temperature distribution model for a room having a floor and a ceiling is provided. The method includes the following steps. A ceiling temperature distribution in the room is determined. A floor temperature distribution in the room is determined. An interpolation between the ceiling temperature distribution and the floor temperature distribution is used to obtain the three-dimensional temperature distribution model for the room.

  5. Consumer behaviour in the waiting area.

    Science.gov (United States)

    Mobach, Mark P

    2007-02-01

    To determine consumer behaviour in the pharmacy waiting area. The applied methods for data-collection were direct observations. Three Dutch community pharmacies were selected for the study. The topics in the observation list were based on available services at each waiting area (brochures, books, illuminated new trailer, children's play area, etc.). Per patient each activity was registered, and at each pharmacy the behaviour was studied for 2 weeks. Most patients only waited during the waiting time at the studied pharmacies. Few consumers obtained written information during their wait. The waiting area may have latent possibilities to expand the information function of the pharmacy and combine this with other activities that distract the consumer from the wait. Transdisciplinary research, combining knowledge from pharmacy practice research with consumer research, has been a useful approach to add information on queueing behaviour of consumers.

  6. Whittling Down the Wait Time: Exploring Models to Minimize the Delay from Initial Concern to Diagnosis and Treatment of Autism Spectrum Disorder.

    Science.gov (United States)

    Gordon-Lipkin, Eliza; Foster, Jessica; Peacock, Georgina

    2016-10-01

    The process from initial concerns to diagnosis of autism spectrum disorder (ASD) can be a long and complicated process. The traditional model for evaluation and diagnosis of ASD often consists of long wait-lists and evaluations that result in a 2-year difference between the earliest signs of ASD and mean age of diagnosis. Multiple factors contribute to this diagnostic bottleneck, including time-consuming evaluations, cost of care, lack of providers, and lack of comfort of primary care providers to diagnose autism. This article explores innovative clinical models that have been implemented to address this as well as future directions and opportunities. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. M-machine, no-wait flowshop scheduling with sequence dependent setup times and truncated learning function to minimize the makespan

    Directory of Open Access Journals (Sweden)

    V. Azizi

    2016-04-01

    Full Text Available Recently, learning effects have been studied as an interesting topic for scheduling problems, however, most researches have considered single or two-machine settings. Moreover, learning factor has been considered for job times instead of setup times and the same learning effect has been used for all machines. This paper studies the m-machine no-wait flowshop scheduling problem considering truncated learning effect in no-wait flowshop environment. In this problem, setup time is a function of job position in the sequence with a learning truncation parameter and each machine has its own learning effect. In this paper, a mixed integer linear programming is proposed for the problem to solve such problem. This problem is NP-hard so an improved genetic algorithm (GA and a simulated annealing (SA algorithm are developed to find near optimal solutions. The accuracy and efficiency of the proposed procedures are tested against different criteria on various instances. Numerical experiments approve that SA outperforms in most instances.

  8. A Distributed Representation of Remembered Time

    Science.gov (United States)

    2015-11-19

    AFRL-AFOSR-VA-TR-2015-0393 A Distributed Representation of Remembered Time Marc Howard TRUSTEES OF BOSTON UNIVERSITY Final Report 11/19/2015...SUBTITLE A Distributed Representation of Remembered Time 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-12-1-0369 5c.  PROGRAM ELEMENT NUMBER 61102F 6...the award was to extend a mathematical framework for representing time to also construct scale-invariant representations of space. The extensive

  9. Waiting for care

    Science.gov (United States)

    Goel, Ritika; Bloch, Gary; Caulford, Paul

    2013-01-01

    Abstract Objective To describe the experiences of a group of new immigrants and caregivers of new immigrants who were subject to the 3-month waiting period for the Ontario Health Insurance Plan and needed to access health care services during that time. Design Qualitative study using a phenomenologic framework. Setting Participants were recruited through the Scarborough Community Volunteer Clinic in Toronto, Ont. Interviews were conducted in person at the clinic or by telephone. Participants Seven participants were interviewed who themselves needed to access health care during the 3-month waiting period for the Ontario Health Insurance Plan or who were caring for someone who did. Methods Seven semistructured, in-depth interviews were conducted using an interview guide; these were recorded and transcribed verbatim. Data were analyzed for themes to arrive at the essence of the participants’ experiences. Main findings Participants believed that there was a lack of clear information and a lack of help from officials. Other common themes included poor social situations, financial loss or threat of financial loss related to health care, a choice to delay seeking care owing to cost, difficulty accessing alternative care, and appreciation for those who advocated on their behalf. Other themes that arose included emotional hardship, poor health outcomes or threat of poor health outcomes resulting from not seeking care, the importance and unpredictability of health, as well as negative impressions of Canada as a country as a result of the negative experience of seeking care. Conclusion New immigrants to Ontario who need to access health care services during the 3-month waiting period for provincial health insurance and the caregivers of such newcomers can have potentially very negative experiences. They might be unable to access care without financial barriers and might, therefore, choose to delay seeking health care until the end of the waiting period; this can lead to

  10. Distributed Algorithms for Time Optimal Reachability Analysis

    DEFF Research Database (Denmark)

    Zhang, Zhengkui; Nielsen, Brian; Larsen, Kim Guldstrand

    2016-01-01

    Time optimal reachability analysis is a novel model based technique for solving scheduling and planning problems. After modeling them as reachability problems using timed automata, a real-time model checker can compute the fastest trace to the goal states which constitutes a time optimal schedule....... We propose distributed computing to accelerate time optimal reachability analysis. We develop five distributed state exploration algorithms, implement them in \\uppaal enabling it to exploit the compute resources of a dedicated model-checking cluster. We experimentally evaluate the implemented...

  11. [The international adoption waiting period: waiting experience and coping strategies].

    Science.gov (United States)

    Pedro-Viejo, Ana Berástegui

    2008-11-01

    The adoption waiting period is a powerful stressor that can affect the well-being and configuration of future family life. Adoption research and practice have not paid enough attention to this phase. The principal aim of this study is to address prospective adoptive parents' experience of and coping with this period. For this purpose, 63 families answered a feelings scale, a coping resources scale and a needs questionnaire, all elaborated for the study. Results show that a shorter length of waiting time, using cognitive and learning coping strategies and associative participation were related to a better general experience of adoption whereas process-centred strategies were related to a worse experience of adoption. Families would like to see more speed in the process, more warmth and humanity in their relation with institutions and better information about their expedients. We conclude by proposing some activities and services during the waiting period that could be useful for post adoption.

  12. Waiting for a pacemaker

    DEFF Research Database (Denmark)

    Risgaard, B.; Elming, H.; Jensen, G.V.

    2012-01-01

    to implantation. A lack of implantation capacity was responsible for 4.5 of the waiting days. Twenty-nine patients (11.2) developed infection while waiting, primarily urinary tract infections. Thirteen patients (5.0) suffered non-sustained ventricular tachycardia, and eight patients (3.1) suffered clinical...... event during the waiting period. The present study indicates that a waiting period is dangerous as it is associated with an increased risk of adverse events. Acute PPMs should be implanted with a 24-h pacemaker implantation service capacity. Published on behalf of the European Society of Cardiology. All...

  13. Time distributions in satellite constellation design

    Science.gov (United States)

    Arnas, David; Casanova, Daniel; Tresaco, Eva

    2017-06-01

    The aim of the time distribution methodology presented in this paper is to generate constellations whose satellites share a set of relative trajectories in a given time, and maintain that property over time without orbit corrections. The model takes into account a series of orbital perturbations such as the gravitational potential of the Earth, the atmospheric drag, the Sun and the Moon as disturbing third bodies and the solar radiation pressure. These perturbations are included in the design process of the constellation. Moreover, the whole methodology allows to design constellations with multiple relative trajectories that can be distributed in a minimum number of inertial orbits.

  14. Femtosecond Timing Distribution Using Optical Pulses

    CERN Document Server

    Winter, A; Winter, A

    2005-01-01

    Fourth-generation light sources, such as the European X-ray Free Electron Laser (XFEL) require timing signals distributed over distances of several kilometers with a stability in the order of femtoseconds. A promising approach is the use of a mode-locked laser that generates sub-picosecond pulses which are distributed in timing stabilized optical fiber links. A good candidate for a laser master oscillator (LMO) is a mode-locked Erbium-doped fiber laser, featuring extremely low phase noise far from the carrier. Results on the development of the LMO locked to an external reference microwave oscillator to suppress low frequency jitter, the distribution via timing stabilized optical fiber links and the reconversion of the optical pulses to a low phase noise microwave RF signals with overall femtosecond stability are presented.

  15. Residence time distribution of a cylindrical microreactor.

    Science.gov (United States)

    Hsu, Jyh-Ping; Wei, Tzu-Hsuan

    2005-05-12

    The residence time distribution for the flow of liquid reactants containing electrolytes in a cylindrical microreactor is derived under the conditions of constant surface potential and negligible end effects. The influences of the key parameters, including the thickness of the double layer, the strength of the applied electric field, and the magnitude of the applied pressure gradient, on the behavior of residence time distribution are discussed. The results obtained provide necessary information for the design and optimization of microreactors which involve liquid electrolyte reactants. The results of the numerical simulation reveal that a thin double layer, a strong applied electric field, and a greater applied pressure gradient lead to a faster fluid flow and, therefore, a short residence time. We show that if kappaa residence time distribution can be approximated by that for the case of a laminar flow, and if kappaa >/= 500, the residence time distribution can be approximated by that for the case of a plug flow, with kappa and a being the reciprocal Debye length and the radius of the microreactor, respectively.

  16. Linking age, survival, and transit time distributions

    Science.gov (United States)

    Calabrese, Salvatore; Porporato, Amilcare

    2015-10-01

    Although the concepts of age, survival, and transit time have been widely used in many fields, including population dynamics, chemical engineering, and hydrology, a comprehensive mathematical framework is still missing. Here we discuss several relationships among these quantities by starting from the evolution equation for the joint distribution of age and survival, from which the equations for age and survival time readily follow. It also becomes apparent how the statistical dependence between age and survival is directly related to either the age dependence of the loss function or the survival-time dependence of the input function. The solution of the joint distribution equation also allows us to obtain the relationships between the age at exit (or death) and the survival time at input (or birth), as well as to stress the symmetries of the various distributions under time reversal. The transit time is then obtained as a sum of the age and survival time, and its properties are discussed along with the general relationships between their mean values. The special case of steady state case is analyzed in detail. Some examples, inspired by hydrologic applications, are presented to illustrate the theory with the specific results. This article was corrected on 11 Nov 2015. See the end of the full text for details.

  17. Right On Time Distributed Shared Memory

    OpenAIRE

    Guerraoui, Rachid; Kozhaya, David; Pignolet-Oswald, Yvonne-Anne

    2016-01-01

    The demand for real-time data storage in distributed control systems (DCSs) is growing. Yet, providing real- time DCS guarantees is challenging, especially when more and more sensor and actuator devices are connected to industrial plants and message loss needs to be taken into account. In this paper, we investigate how to build a shared memory abstraction for DCSs as a first step towards implementing different shared storage systems in a DCS context. We first prove that, in the presence of ho...

  18. Commercial border crossing and wait time measurement at Laredo World Trade Bridge and the Colombia-Solidarity Bridge.

    Science.gov (United States)

    2012-03-01

    This research is to establish a baseline and on-going measurement of border crossing times and : delay by measuring travel times for commercial trucks crossing the port of entry (POE) from : Mexico into Texas at the Laredo World Trade Bridge and the ...

  19. Indefinite waitings in MIRELA systems

    Directory of Open Access Journals (Sweden)

    Johan Arcile

    2015-06-01

    Full Text Available MIRELA is a high-level language and a rapid prototyping framework dedicated to systems where virtual and digital objects coexist in the same environment and interact in real time. Its semantics is given in the form of networks of timed automata, which can be checked using symbolic methods. This paper shows how to detect various kinds of indefinite waitings in the components of such systems. The method is experimented using the PRISM model checker.

  20. Implementing wait-time reductions under Ontario government benchmarks (Pay-for-Results): a Cluster Randomized Trial of the Effect of a Physician-Nurse Supplementary Triage Assistance team (MDRNSTAT) on emergency department patient wait times.

    Science.gov (United States)

    Cheng, Ivy; Lee, Jacques; Mittmann, Nicole; Tyberg, Jeffrey; Ramagnano, Sharon; Kiss, Alex; Schull, Michael; Kerr, Fergus; Zwarenstein, Merrick

    2013-11-11

    Internationally, emergency departments are struggling with crowding and its associated morbidity, mortality, and decreased patient and health-care worker satisfaction. The objective was to evaluate the addition of a MDRNSTAT (Physician (MD)-Nurse (RN) Supplementary Team At Triage) on emergency department patient flow and quality of care. Pragmatic cluster randomized trial. From 131 weekday shifts (8:00-14:30) during a 26-week period, we randomized 65 days (3173 visits) to the intervention cluster with a MDRNSTAT presence, and 66 days (3163 visits) to the nurse-only triage control cluster. The primary outcome was emergency department length-of-stay (EDLOS) for patients managed and discharged only by the emergency department. Secondary outcomes included EDLOS for patients initially seen by the emergency department, and subsequently consulted and admitted, patients reaching government-mandated thresholds, time to initial physician assessment, left-without being seen rate, time to investigation, and measurement of harm. The intervention's median EDLOS for discharged, non-consulted, high acuity patients was 4:05 [95th% CI: 3:58 to 4:15] versus 4:29 [95th% CI: 4:19-4:38] during comparator shifts. The intervention's median EDLOS for discharged, non-consulted, low acuity patients was 1:55 [95th% CI: 1:48 to 2:05] versus 2:08 [95th% CI: 2:02-2:14]. The intervention's median physician initial assessment time was 0:55 [95th% CI: 0:53 to 0:58] versus 1:21 [95th% CI: 1:18 to 1:25]. The intervention's left-without-being-seen rate was 1.5% versus 2.2% for the control (p = 0.06). The MDRNSTAT subgroup analysis resulted in significant decreases in median EDLOS for discharged, non-consulted high (4:01 [95th% CI: 3:43-4:16]) and low acuity patients (1:10 95th% CI: 0:58-1:19]), as well as physician initial assessment time (0:25 [95th% CI: 0:23-0:26]). No patients returned to the emergency department after being discharged by the MDRNSTAT at triage. The intervention reduced delays

  1. Satisfacción de las mujeres con la duración del proceso de valoración adicional en el cribado mamográfico Women's satisfaction with waiting times for further investigation in breast cancer screening

    Directory of Open Access Journals (Sweden)

    Ana Molina-Barceló

    2011-10-01

    Full Text Available Objetivos: Conocer los factores asociados a la satisfacción con la duración del proceso de valoración adicional en el cribado mamográfico. Métodos: Estudio transversal descriptivo y multivariado mediante encuesta telefónica a una muestra representativa de mujeres (N=316 participantes en el Programa de Prevención del Cáncer de Mama de la Comunidad Valenciana, que requirieron valoración adicional mediante pruebas complementarias para confirmar el diagnóstico. Análisis descriptivo mediante tablas de contingencia (pObjectives: To determine the factors associated with satisfaction with waiting times for further investigation in breast cancer screening. Methods: We carried out a cross-sectional study by telephone survey of a representative sample of women (N=316 participating in the breast cancer screening program of the autonomous region of Valencia (Spain who required additional tests to confirm the diagnosis. Descriptive analysis was performed by contingency tables (p<0.05 and multivariate association by odds ratios (OR of logistic regression models (95%CI. Results: Satisfaction with the waiting time was 78.6%. A higher risk of dissatisfaction was found in women from a "high" social class (OR=3.17; 95% CI: 1.10-9.14, those who perceived that the waiting time was "more than 2 weeks", both "since the notification of the need for further investigation until completion of the first test" (OR=15,54; 95%CI: 5,87-41,12 and "since the completion of the last test until notification of the final result" (OR=11.57; 95% CI: 2.96-45.19, and in women who experienced the attention as "worse than expected" (OR=15.40; 95% CI: 1.41-168.64. The maximum waiting time acceptable to the highest percentage of women was "up to 1 week" for each waiting period (n=47, 73.5%; n=14, 45.2%. Conclusions: Waiting times of no more than 1 week and never more than 2 weeks for each waiting period are recommended. Women should be given an approximate waiting time, paying

  2. The Relationship between Wait Time after Triage and Show Rate for Intake in a Nonurgent Student Population

    Science.gov (United States)

    DiMino, John; Blau, Gary

    2012-01-01

    Ideally, students requesting services should be seen quickly at their university counseling center to increase the likelihood of a successful treatment outcome. However, in these times of ever-increasing demand for university counseling services and the challenges of securing resources to keep up with that demand, the reality of prompt…

  3. How Does the Supply Requisitioning Process Affect Average Customer Wait Time Onboard U.S. Navy Destroyers?

    Science.gov (United States)

    2013-06-01

    firm’s degree of success will improve. 2. Quality Control The quality control method is a continuation of the work simplification rooted in the work...highly utilized tool that monitors the health of a ship’s supply department metrics. The CMP extractor retrieves real-time data from surface ships in...the latest extractor software, view current DLR carcass charge data, and respond to data calls by COMNAVSURFOR. We obtained one year of historical

  4. The Wait Calculation: The Broader Consequences of the Minimum Time from Now to Interstellar Destinations and its Significance to the Space Economy

    Science.gov (United States)

    Kennedy, A.

    This paper summarises the wait calculation [1] of interstellar voyagers which finds the minimum time to destination given exponential growth in the rate of travel available to a civilisation. The minimum time obliges stellar system colonisers to consider departure times a significant risk factor in their voyages since a departure then to a destination will beat a departure made at any other time before or after. Generalised conclusions will be drawn about the significant impact that departures to interstellar destinations before, at, or after the minimum time will have on the economic potential of missions and on the inevitability of competition between them. There will be no international law operating in interstellar space and an ability to escape predatory actions en route, or at the destination, can only be done by precise calculations of departure times. Social and economic forces affecting the factors in the growth equation are discussed with reference to the probability of accelerating growth reaching the technological Singularity and strengthening the growth incentive trap. Islamic banking practices are discussed as a credible alternative to compounding interest bearing paper for funding the space economy in the long term and for supporting stakeholder investment in such long term mission development. The paper considers the essential free productivity of the Earth's biosphere and the capital accumulations made possible by land productivity are essential components to a viable long term space economy and that research into re-creating the costless productivity of the biosphere at a destination will determine both the mission's ultimate success and provide means of returns for stakeholders during the long build up. Conclusions of these arguments suggest that the Icarus project should ignore a robotic interstellar mission concept and develop a manned colonising mission from now.

  5. The One-stop trial: Does electronic referral and booking by the general practitioner (GPs to outpatient day case surgery reduce waiting time and costs? A randomized controlled trial protocol

    Directory of Open Access Journals (Sweden)

    Vonen Barthold

    2008-08-01

    Full Text Available Abstract Background Waiting time and costs from referral to day case outpatient surgery are at an unacceptably high level. The waiting time in Norway averages 240 days for common surgical conditions. Furthermore, in North Norway the population is scattered throughout a large geographic area, making the cost of travel to a specialist examination before surgery considerable. Electronic standardised referrals and booking of day case outpatient surgery by GPs are possible through the National Health Network, which links all health care providers in an electronic network. New ways of using this network might reduce the waiting time and cost of outpatient day case surgery. Materials and Methods In a randomised controlled trial, selected patients (inguinal hernia, gallstone disease and pilonidal sinus referred to the university hospital are either randomised to direct electronic referral and booking for outpatient surgery (one stop, or to the traditional patient pathway where all patients are seen at the outpatient clinic several weeks ahead of surgery. Consultants in gastrointestinal surgery designed standardised referral forms and guidelines. New software has been designed making it possible to implement referral forms, guidelines and patient information in the GP's electronic health record. For "one-stop" referral, GPs must provide mandatory information about the specific condition. Referrals were linked to a booking system, enabling the GPs to book the hospital, day and time for outpatient surgery. The primary endpoints are waiting time and costs. The sample size calculation was based on waiting time. A reduction in waiting time of 60 days (effect size, 25%, is significant, resulting in a sample size of 120 patients in total. Discussion Poor communication between primary and secondary care often results in inefficiencies and unsatisfactory outcomes. We hypothesised that standardised referrals would improve the quality of information, making it

  6. The Effect of 5S-Continuous Quality Improvement-Total Quality Management Approach on Staff Motivation, Patients' Waiting Time and Patient Satisfaction with Services at Hospitals in Uganda.

    Science.gov (United States)

    Take, Naoki; Byakika, Sarah; Tasei, Hiroshi; Yoshikawa, Toru

    2015-03-31

    This study aimed at analyzing the effect of 5S practice on staff motivation, patients' waiting time and patient satisfaction with health services at hospitals in Uganda. Double-difference estimates were measured for 13 Regional Referral Hospitals and eight General Hospitals implementing 5S practice separately. The study for Regional Referral Hospitals revealed 5S practice had the effect on staff motivation in terms of commitment to work in the current hospital and waiting time in the dispensary in 10 hospitals implementing 5S, but significant difference was not identified on patient satisfaction. The study for General Hospitals indicated the effect of 5S practice on patient satisfaction as well as waiting time, but staff motivation in two hospitals did not improve. 5S practice enables the hospitals to improve the quality of services in terms of staff motivation, waiting time and patient satisfaction and it takes as least four years in Uganda. The fourth year since the commencement of 5S can be a threshold to move forward to the next step, Continuous Quality Improvement.

  7. Development of a minimization instrument for allocation of a hospital-level performance improvement intervention to reduce waiting times in Ontario emergency departments

    Directory of Open Access Journals (Sweden)

    Anderson Geoff

    2009-06-01

    Full Text Available Abstract Background Rigorous evaluation of an intervention requires that its allocation be unbiased with respect to confounders; this is especially difficult in complex, system-wide healthcare interventions. We developed a short survey instrument to identify factors for a minimization algorithm for the allocation of a hospital-level intervention to reduce emergency department (ED waiting times in Ontario, Canada. Methods Potential confounders influencing the intervention's success were identified by literature review, and grouped by healthcare setting specific change stages. An international multi-disciplinary (clinical, administrative, decision maker, management panel evaluated these factors in a two-stage modified-delphi and nominal group process based on four domains: change readiness, evidence base, face validity, and clarity of definition. Results An original set of 33 factors were identified from the literature. The panel reduced the list to 12 in the first round survey. In the second survey, experts scored each factor according to the four domains; summary scores and consensus discussion resulted in the final selection and measurement of four hospital-level factors to be used in the minimization algorithm: improved patient flow as a hospital's leadership priority; physicians' receptiveness to organizational change; efficiency of bed management; and physician incentives supporting the change goal. Conclusion We developed a simple tool designed to gather data from senior hospital administrators on factors likely to affect the success of a hospital patient flow improvement intervention. A minimization algorithm will ensure balanced allocation of the intervention with respect to these factors in study hospitals.

  8. Weakest-Link Scaling and Finite Size Effects on Recurrence Times Distribution

    CERN Document Server

    Hristopulos, Dionissios T; Kaniadakis, Giorgio

    2013-01-01

    Tectonic earthquakes result from the fracturing of the Earth's crust due to the loading induced by the motion of the tectonic plates. Hence, the statistical laws of earthquakes must be intimately connected to the statistical laws of fracture. The Weibull distribution is a commonly used model of earthquake recurrence times (ERT). Nevertheless, deviations from Weibull scaling have been observed in ERT data and in fracture experiments on quasi-brittle materials. We propose that the weakest-link-scaling theory for finite-size systems leads to the kappa-Weibull function, which implies a power-law tail for the ERT distribution. We show that the ERT hazard rate function decreases linearly after a waiting time which is proportional to the system size (in terms of representative volume elements) raised to the inverse of the Weibull modulus. We also demonstrate that the kappa-Weibull can be applied to strongly correlated systems by means of simulations of a fiber bundle model.

  9. Time Optimal Run-time Evaluation of Distributed Timing Constraints in Process Control Software

    DEFF Research Database (Denmark)

    Drejer, N.; Kristensen, C.H.

    1993-01-01

    This paper considers run-time evaluation of an important class of constraints; Timing constraints. These appear extensively in process control systems. Timing constraints are considered in distributed systems, i.e. systems consisting of multiple autonomous nodes.........This paper considers run-time evaluation of an important class of constraints; Timing constraints. These appear extensively in process control systems. Timing constraints are considered in distributed systems, i.e. systems consisting of multiple autonomous nodes......

  10. Colour Consideration for Waiting areas in hospitals

    Science.gov (United States)

    Zraati, Parisa

    2012-08-01

    Colour is one the most important factors in the nature that can have some affects on human behaviour. Many years ago, it was proven that using colour in public place can have some affect on the users. Depend of the darkness and lightness; it can be vary from positive to negative. The research will mainly focus on the colour and psychological influences and physical factors. The statement of problem in this research is what is impact of colour usually applied to waiting area? The overall aim of the study is to explore the visual environment of hospitals and to manage the colour psychological effect of the hospital users in the waiting area by creating a comfortable, pleasant and cozy environment for users while spend their time in waiting areas. The analysisconcentrate on satisfaction and their interesting regarding applied colour in two private hospital waiting area in Malaysia.

  11. Who breaches the four-hour emergency department wait time target? A retrospective analysis of 374,000 emergency department attendances between 2008 and 2013 at a type 1 emergency department in England.

    Science.gov (United States)

    Bobrovitz, Niklas; Lasserson, Daniel S; Briggs, Adam D M

    2017-11-02

    The four-hour target is a key hospital emergency department performance indicator in England and one that drives the physical and organisational design of the ED. Some studies have identified time of presentation as a key factor affecting waiting times. Few studies have investigated other determinants of breaching the four-hour target. Therefore, our objective was to describe patterns of emergency department breaches of the four-hour wait time target and identify patients at highest risk of breaching. This was a retrospective cohort study of a large type 1 Emergency department at an NHS teaching hospital in Oxford, England. We analysed anonymised individual level patient data for 378,873 emergency department attendances, representing all attendances between April 2008 and April 2013. We examined patient characteristics and emergency department presentation circumstances associated with the highest likelihood of breaching the four-hour wait time target. We used 374,459 complete cases for analysis. In total, 8.3% of all patients breached the four-hour wait time target. The main determinants of patients breaching the four-hour wait time target were hour of arrival to the ED, day of the week, patient age, ED referral source, and the types of investigations patients receive (p breach the four-hour target were older, presented at night, presented on Monday, received multiple types of investigation in the emergency department, and were not self-referred (p breaching compared to those attending from March to September (OR 1.63, 95% CI 1.59 to 1.66). There are a number of independent patient and circumstantial factors associated with the probability of breaching the four-hour ED wait time target including patient age, ED referral source, the types of investigations patients receive, as well as the hour, day, and month of arrival to the ED. Efforts to reduce the number of breaches could explore late-evening/overnight staffing, access to diagnostic tests, rapid discharge

  12. Solving no-wait two-stage flexible flow shop scheduling problem with unrelated parallel machines and rework time by the adjusted discrete Multi Objective Invasive Weed Optimization and fuzzy dominance approach

    Directory of Open Access Journals (Sweden)

    Hassan Jafarzadeh

    2017-11-01

    Full Text Available Purpose: Adjusted discrete Multi-Objective Invasive Weed Optimization (DMOIWO algorithm, which uses fuzzy dominant approach for ordering, has been proposed to solve No-wait two-stage flexible flow shop scheduling problem. Design/methodology/approach: No-wait two-stage flexible flow shop scheduling problem by considering sequence-dependent setup times and probable rework in both stations, different ready times for all jobs and rework times for both stations as well as unrelated parallel machines with regards to the simultaneous minimization of maximum job completion time and average latency functions have been investigated in a multi-objective manner. In this study, the parameter setting has been carried out using Taguchi Method based on the quality indicator for beater performance of the algorithm. Findings: The results of this algorithm have been compared with those of conventional, multi-objective algorithms to show the better performance of the proposed algorithm. The results clearly indicated the greater performance of the proposed algorithm. Originality/value: This study provides an efficient method for solving multi objective no-wait two-stage flexible flow shop scheduling problem by considering sequence-dependent setup times, probable rework in both stations, different ready times for all jobs, rework times for both stations and unrelated parallel machines which are the real constraints.

  13. Challenging "Waiting for Superman"

    Science.gov (United States)

    Bruhn, Molle

    2014-01-01

    A group of New York City public school teachers, angry about the depiction of public schools in 'Waiting for Superman," decide to make their own film about the realities of the current education reform movement. They persevered even though they had no budget when they started and lacked a background in filmmaking. "The Inconvenient Truth…

  14. Emergency department waiting room nurse role: A key informant perspective.

    Science.gov (United States)

    Innes, Kelli; Jackson, Debra; Plummer, Virginia; Elliott, Doug

    2017-02-01

    Emergency departments have become overcrowded with increased waiting times. Strategies to decrease waiting times include time-based key performance indicators and introduction of a waiting room nurse role. The aim of the waiting room nurse role is to expedite care by assessing and managing patients in the waiting room. There is limited literature examining this role. This paper presents results of semi-structured interviews with five key informants to explore why and how the waiting room nurse role was implemented in Australian emergency departments. Data were thematically analysed. Five key informants from five emergency departments across two Australian jurisdictions (Victoria and New South Wales) reported that the role was introduced to reduce waiting times and improve quality and safety of care in the ED waiting room. Critical to introducing the role was defining and supporting the scope of practice, experience and preparation of the nurses. Role implementation required champions to overcome identified challenges, including funding. There has been limited evaluation of the role. The waiting room nurse role was introduced to decrease waiting times and contributed to risk mitigation. Common to all roles was standing orders, while preparation and experience varied. Further research into the role is required. Copyright © 2016 College of Emergency Nursing Australasia. Published by Elsevier Ltd. All rights reserved.

  15. Extending the absorbing boundary method to fit dwell-time distributions of molecular motors with complex kinetic pathways.

    Science.gov (United States)

    Liao, Jung-Chi; Spudich, James A; Parker, David; Delp, Scott L

    2007-02-27

    Dwell-time distributions, waiting-time distributions, and distributions of pause durations are widely reported for molecular motors based on single-molecule biophysical experiments. These distributions provide important information concerning the functional mechanisms of enzymes and their underlying kinetic and mechanical processes. We have extended the absorbing boundary method to simulate dwell-time distributions of complex kinetic schemes, which include cyclic, branching, and reverse transitions typically observed in molecular motors. This extended absorbing boundary method allows global fitting of dwell-time distributions for enzymes subject to different experimental conditions. We applied the extended absorbing boundary method to experimental dwell-time distributions of single-headed myosin V, and were able to use a single kinetic scheme to fit dwell-time distributions observed under different ligand concentrations and different directions of optical trap forces. The ability to use a single kinetic scheme to fit dwell-time distributions arising from a variety of experimental conditions is important for identifying a mechanochemical model of a molecular motor. This efficient method can be used to study dwell-time distributions for a broad class of molecular motors, including kinesin, RNA polymerase, helicase, F(1) ATPase, and to examine conformational dynamics of other enzymes such as ion channels.

  16. Reconfigurable real-time distributed processing network

    Science.gov (United States)

    Page, S. F.; Seely, R. D.; Hickman, D.

    2011-06-01

    This paper describes a novel real-time image and signal processing network, RONINTM, which facilitates the rapid design and deployment of systems providing advanced geospatial surveillance and situational awareness capability. RONINTM is a distributed software architecture consisting of multiple agents or nodes, which can be configured to implement a variety of state-of-the-art computer vision and signal processing algorithms. The nodes operate in an asynchronous fashion and can run on a variety of hardware platforms, thus providing a great deal of scalability and flexibility. Complex algorithmic configuration chains can be assembled using an intuitive graphical interface in a plug-and- play manner. RONINTM has been successfully exploited for a number of applications, ranging from remote event detection to complex multiple-camera real-time 3D object reconstruction. This paper describes the motivation behind the creation of the network, the core design features, and presents details of an example application. Finally, the on-going development of the network is discussed, which is focussed on dynamic network reconfiguration. This allows to the network to automatically adapt itself to node or communications failure by intelligently re-routing network communications and through adaptive resource management.

  17. Comparison of Traditional and Open-Access Appointment Scheduling for Exponentially Distributed Service Time

    Directory of Open Access Journals (Sweden)

    Chongjun Yan

    2015-01-01

    Full Text Available This paper compares the performance measures of traditional appointment scheduling (AS with those of an open-access appointment scheduling (OA-AS system with exponentially distributed service time. A queueing model is formulated for the traditional AS system with no-show probability. The OA-AS models assume that all patients who call before the session begins will show up for the appointment on time. Two types of OA-AS systems are considered: with a same-session policy and with a same-or-next-session policy. Numerical results indicate that the superiority of OA-AS systems is not as obvious as those under deterministic scenarios. The same-session system has a threshold of relative waiting cost, after which the traditional system always has higher total costs, and the same-or-next-session system is always preferable, except when the no-show probability or the weight of patients’ waiting is low. It is concluded that open-access policies can be viewed as alternative approaches to mitigate the negative effects of no-show patients.

  18. Waiting list in a public health facility in Santiago, Chile

    Directory of Open Access Journals (Sweden)

    Alejandro Letelier

    2014-07-01

    Full Text Available Introduction Waiting lists are a well-known problem in public healthcare systems worldwide. For instance, England had over one million people in waiting lists for elective surgical procedures in 2000. Spain had over 360 000 patients in surgical waiting lists in 2007. Chile has been trying to manage waiting times through the GES (Explicit Guarantees in Healthcare plan, which was established by the Chilean government in 2005. Waiting lists for the guaranteed-care diseases in the GES plan had 380 000 patients at the beginning of 2010, and that number was reduced to zero in 2011. Internationally, there are some descriptive studies about waiting lists that focus on variables such as waiting times and number of patients in the list. In Chile, however, this type of study is lacking. Purpose This study aims to describe the characteristics of waiting lists for medical specialties between April and October 2011. It also aims to identify the components of management models in public healthcare centers, and to identify and analyze waiting-time frames of patients referred to a secondary or tertiary healthcare public center from a public primary healthcare center. Methods A descriptive cross-sectional study of the waiting list for first-time consultations for medical specialties was carried out. Referred patients were described and grouped using indicators of access to healthcare and waiting time between April and October 2011. Each consultation request or referral of a new patient was included in the waiting list and analyzed. Results There were 15 935 requests for consultations; 5 717 requests were resolved, and 8 544 were not (54% of the total requests for consultation. There was a mean waiting time of 498 days for non-resolved requests for consultation, and a mean of 141 days for resolved requests. The specialties in highest demand were orthopedic surgery and ophthalmology. The main waiting-list management processes were referral and reception of requests

  19. Waiting for coronary angiography: is there a clinically ordered queue?

    Science.gov (United States)

    Hemingway, H; Crook, A M; Feder, G; Dawson, J R; Timmis, A

    2000-03-18

    Among over 3000 patients undergoing coronary angiography in the absence of a formal queue-management system, we found that a-priori urgency scores were strongly associated with waiting times, prevalence of coronary-artery disease, rate of revascularisation, and mortality. These data challenge the widely held assumption that such waiting lists are not clinically ordered; however, the wide variation in waiting times within urgency categories suggests the need for further improvements in clinical queueing.

  20. Stress Caused by Waiting: A Theoretical Evaluation of a Mathematical Model

    Science.gov (United States)

    Suck; Holling

    1997-09-01

    According to cognitive stress theories, stress caused by waiting is influenced by two components, the (psychological) cost of waiting, that is, a function C of time, and a probability distribution over waiting times. Osuna (1985a) suggested a model by which stress as a function of time could be calculated from these constituents. The aim of this paper is (1) to generalize the model, (2) to investigate its mathematical properties, (3) to derive predictions for experimental tests of the model, and (4) to give a precise meaning to the variability and duration hypothesis discussed in the experimental literature. In particular, several theorems are derived which specify situations in which the model enables the user to compare conditions for their stress inducing potential. Such conditions are the duration of the waiting time and the predictability of the length of a waiting period. The core of the mathematical derivations is an identity for expected stress which simplifies the calculations of the Osuna model considerably. Copyright 1997 Academic Press

  1. Catchment mixing processes and travel time distributions

    National Research Council Canada - National Science Library

    Botter, Gianluca

    2012-01-01

    ...) of travel, residence and evapotranspiration times, which are comprehensive descriptors of the fate of rainfall water particles traveling through catchments, and provide key information on hydrologic...

  2. Waiting time for radiation therapy after breast-conserving surgery in early breast cancer: a retrospective analysis of local relapse and distant metastases in 615 patients.

    Science.gov (United States)

    Caponio, Raffaella; Ciliberti, Maria Paola; Graziano, Giusi; Necchia, Rocco; Scognamillo, Giovanni; Pascali, Antonio; Bonaduce, Sabino; Milella, Anna; Matichecchia, Gabriele; Cristofaro, Cristian; Di Fatta, Davide; Tamborra, Pasquale; Lioce, Marco

    2016-08-11

    Postoperative radiotherapy after breast-conserving surgery (BCS) is the standard in the management of breast cancer. The optimal timing for starting postoperative radiation therapy has not yet been well defined. In this study, we aimed to evaluate if the time interval between BCS and postoperative radiotherapy is related to the incidence of local and distant relapse in women with early node-negative breast cancer not receiving chemotherapy. We retrospectively analyzed clinical data concerning 615 women treated from 1984 to 2010, divided into three groups according to the timing of radiotherapy: ≤60, 61-120, and >120 days. To estimate the presence of imbalanced distribution of prognostic and treatment factors among the three groups, the χ2 test or the Fisher exact test were performed. Local relapse-free survival, distant metastasis-free survival (DMFS), and disease-free survival (DFS) were estimated with the Kaplan-Meier method, and multivariate Cox regression was used to test for the independent effect of timing of RT after adjusting for known confounding factors. The median follow-up time was 65.8 months. Differences in distribution of age, type of hormone therapy, and year of diagnosis were statistically significant. At 15-year follow-up, we failed to detect a significant correlation between time interval and the risk of local relapse (p = 0.09) both at the univariate and the multivariate analysis. The DMFS and the DFS univariate analysis showed a decreased outcome when radiotherapy was started early (p = 0.041 and p = 0.046), but this was not confirmed at the multivariate analysis (p = 0.406 and p = 0.102, respectively). Our results show that no correlation exists between the timing of postoperative radiotherapy and the risk of local relapse or distant metastasis development in a particular subgroup of women with node-negative early breast cancer.

  3. Protocol to Exploit Waiting Resources for UASNs

    Directory of Open Access Journals (Sweden)

    Li-Ling Hung

    2016-03-01

    Full Text Available The transmission speed of acoustic waves in water is much slower than that of radio waves in terrestrial wireless sensor networks. Thus, the propagation delay in underwater acoustic sensor networks (UASN is much greater. Longer propagation delay leads to complicated communication and collision problems. To solve collision problems, some studies have proposed waiting mechanisms; however, long waiting mechanisms result in low bandwidth utilization. To improve throughput, this study proposes a slotted medium access control protocol to enhance bandwidth utilization in UASNs. The proposed mechanism increases communication by exploiting temporal and spatial resources that are typically idle in order to protect communication against interference. By reducing wait time, network performance and energy consumption can be improved. A performance evaluation demonstrates that when the data packets are large or sensor deployment is dense, the energy consumption of proposed protocol is less than that of existing protocols as well as the throughput is higher than that of existing protocols.

  4. Tunneling time distribution by means of Nelson's quantum ...

    Indian Academy of Sciences (India)

    We construct a tunneling time distribution by means of Nelson's quantum mechanics and investigate statistical properties of the tunneling time distribution. As a result, we find that the relationship between the average and the variance of the tunneling time shows 'wave-particle duality'.

  5. "Waiting and the waiting room: how do you experience them?" emotional implications and suggestions from patients with cancer.

    Science.gov (United States)

    Catania, Chiara; De Pas, Tommaso; Minchella, Ida; De Braud, Filippo; Micheli, Daniela; Adamoli, Laura; Spitaleri, Gianluca; Noberasco, Cristina; Milani, Alessandra; Zampino, Maria Giulia; Toffalorio, Francesca; Radice, Davide; Goldhirsch, Aron; Nolè, Franco

    2011-06-01

    Waiting can increase discomfort. The goal of this study was to identify moods and fears of cancer patients while in a waiting room and to capture their concrete suggestions for an anthropocentric transformation of waiting itself. A 15-item questionnaire was given to 355 patients who came to our Out-patient Oncology Clinic. Eighty-three percent of patients felt that waiting has an emotional cost, 35% were upset by talking about their condition with others while waiting, and 26% suffered a major emotional impact seeing other sick people and witnessing their clinical decline. Eighty-nine percent of patients suggested that alternative activities, such as meetings with professionals, doctors, and psychologists, be organized during the waiting period; 65% suggested fun activities (music therapy, drawing courses, library, TV). Most patients asked to have the freedom to leave the waiting room. This option, feasibly by means of IMs/"beepers," would limit their sense of having a lack of freedom or being robbed of their time. This study highlighted the complexity and heterogeneity of emotional implications that waiting causes in patients with cancer and collected many patients' suggestions about how to create a constructive, free, and personalized waiting period, overcoming the boredom, distress, and psychological suffering it causes.

  6. Quantifying catchment-scale mixing and its effect on time-varying travel time distributions

    NARCIS (Netherlands)

    Velde, van der Y.; Torfs, P.J.J.F.; Zee, van der S.E.A.T.M.; Uijlenhoet, R.

    2012-01-01

    Travel time distributions are often used to characterize catchment discharge behavior, catchment vulnerability to pollution and pollutant loads from catchments to downstream waters. However, these distributions vary with time because they are a function of rainfall and evapotranspiration. It is

  7. Quantifying catchment-scale mixing and its effects on time varying travel time distributions

    NARCIS (Netherlands)

    Velde, Y. van der; Torfs, P.J.J.F.; Zee, S.E.A.T.M. van der; Uijlenhoet, R.

    2012-01-01

    Travel time distributions are often used to characterize catchment discharge behavior, catchment vulnerability to pollution and pollutant loads from catchments to downstream waters. However, these distributions vary with time because they are a function of rainfall and evapotranspiration. It is

  8. Charged fluid distribution in higher dimensional spheroidal space-time

    Indian Academy of Sciences (India)

    A general solution of Einstein field equations corresponding to a charged fluid distribution on the background of higher dimensional spheroidal space-time is obtained. The solution generates several known solutions for superdense star having spheroidal space-time geometry.

  9. Continuous Time Random Walks with memory and financial distributions

    Science.gov (United States)

    Montero, Miquel; Masoliver, Jaume

    2017-11-01

    We study financial distributions from the perspective of Continuous Time Random Walks with memory. We review some of our previous developments and apply them to financial problems. We also present some new models with memory that can be useful in characterizing tendency effects which are inherent in most markets. We also briefly study the effect on return distributions of fractional behaviors in the distribution of pausing times between successive transactions.

  10. Investigation of the delay time distribution of high power microwave surface flashover

    Science.gov (United States)

    Foster, J.; Krompholz, H.; Neuber, A.

    2011-01-01

    Characterizing and modeling the statistics associated with the initiation of gas breakdown has proven to be difficult due to a variety of rather unexplored phenomena involved. Experimental conditions for high power microwave window breakdown for pressures on the order of 100 to several 100 torr are complex: there are little to no naturally occurring free electrons in the breakdown region. The initial electron generation rate, from an external source, for example, is time dependent and so is the charge carrier amplification in the increasing radio frequency (RF) field amplitude with a rise time of 50 ns, which can be on the same order as the breakdown delay time. The probability of reaching a critical electron density within a given time period is composed of the statistical waiting time for the appearance of initiating electrons in the high-field region and the build-up of an avalanche with an inherent statistical distribution of the electron number. High power microwave breakdown and its delay time is of critical importance, since it limits the transmission through necessary windows, especially for high power, high altitude, low pressure applications. The delay time distribution of pulsed high power microwave surface flashover has been examined for nitrogen and argon as test gases for pressures ranging from 60 to 400 torr, with and without external UV illumination. A model has been developed for predicting the discharge delay time for these conditions. The results provide indications that field induced electron generation, other than standard field emission, plays a dominant role, which might be valid for other gas discharge types as well.

  11. Analysis of emergency department waiting lines

    Directory of Open Access Journals (Sweden)

    Urška Močnik

    2014-10-01

    Full Text Available Background: Steady increase in the numbers of patients seeking medical assistance has recently been observed at the emergency department of the health center under study. This has led to increases in waiting times for patients. The management of the health center has been considering to implement certain measures to remedy this situation. One proposed solution is to add an additional physician to the emergency department. A computer model was constructed to simulate waiting lines and analyze the economic feasibility of employing an additional physician.Aim: This paper analyzes the waiting lines at the emergency department and performs an economic feasibility study to determine whether adding an additional physician to the department would be economically justified.Methods: Data about waiting times at the emergency department were collected to study the situation. For each patient, the arrival time at the waiting room and the starting and ending times of the examination were registered. The data were collected from 13 June 2011 to 25 September 2011. The sample included data on 65 nightly standbys, nine standbys on Saturdays, and 16 standbys on Sundays. Due to incomplete entries, data for nine weekly standbys and six Saturday standbys were excluded from the sample. Based on the data collected, we calculated the waiting and examination times per patient, average number of patients, average waiting time, average examination time, share of active standby teams in total standby time, and number of patients in different time periods. The study involved 1,039 patients. Using a synthesis method, we designed a computer model of waiting lines and economic feasibility. The model was validated using comparative analysis. A what-if analysis was performed using various computer simulations with various scenarios to consider the outcomes of decision alternatives. We applied economic analysis to select the best possible solution.Results: The research results

  12. Sensor distribution design of travel time tomography in explosion.

    Science.gov (United States)

    Guo, Yali; Han, Yan; Wang, Liming; Liu, Linmao

    2014-07-15

    Optimal sensor distribution in explosion testing is important in saving test costs and improving experiment efficiency. Aiming at travel time tomography in an explosion, an optimizing method in sensor distribution is proposed to improve the inversion stability. The influence factors of inversion stability are analyzed and the evaluating function on optimizing sensor distribution is proposed. This paper presents a sub-region and multi-scale cell partition method, according to the characteristics of a shock wave in an explosion. An adaptive escaping particle swarm optimization algorithm is employed to achieve the optimal sensor distribution. The experimental results demonstrate that optimal sensor distribution has improved both indexes and inversion stability.

  13. How Tolerable is Delay? Consumers' Evaluations of Internet Web Sites After Waiting

    NARCIS (Netherlands)

    Dellaert, B.G.C.; Kahn, B.

    1998-01-01

    How consumers’ waiting times affect their retrospective evaluations of Internet Web Sites is investigated in four computer-based experiments. Results show that waiting can but does not always negatively affect evaluations of Web Sites. Results also show that the potential negative effects of waiting

  14. Response Time Analysis of Distributed Web Systems Using QPNs

    Directory of Open Access Journals (Sweden)

    Tomasz Rak

    2015-01-01

    Full Text Available A performance model is used for studying distributed Web systems. Performance evaluation is done by obtaining load test measurements. Queueing Petri Nets formalism supports modeling and performance analysis of distributed World Wide Web environments. The proposed distributed Web systems modeling and design methodology have been applied in the evaluation of several system architectures under different external loads. Furthermore, performance analysis is done to determine the system response time.

  15. Investigating the distribution of the value of travel time savings

    DEFF Research Database (Denmark)

    Fosgerau, Mogens

    2006-01-01

    The distribution of the value of travel time savings (VTTS) is investigated employing various nonparametric techniques to a large dataset originating from a stated choice experiment. The data contain choices between a fast and more expensive alternative and a slow and less expensive alternative....... Increasing the implicit price of time leads to an increased share of respondents who decline to pay to save time. But a significant proportion of respondents, 13%, remain willing to pay to save time at the highest price of time in the design. This means that the right tail of the VTTS distribution...

  16. Valuing travel time variability: Characteristics of the travel time distribution on an urban road

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Fukuda, Daisuke

    2012-01-01

    This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time...... variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized...... travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution...

  17. Prediction of residence time distributions in food processing machinery

    DEFF Research Database (Denmark)

    Karlson, Torben; Friis, Alan; Szabo, Peter

    1996-01-01

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

  18. Eqüidade no tempo de espera para determinadas cirurgias eletivas segundo o tipo de hospital em Sorocaba, SP Equity in waiting time for some elective surgeries according to hospital type in Sorocaba, SP

    Directory of Open Access Journals (Sweden)

    Thiago Caldi de Carvalho

    2008-09-01

    Full Text Available INTRODUÇÃO: A eqüidade na atenção à saúde tem sido alvo de grande preocupação, incluindo países em desenvolvimento e desenvolvidos. A eqüidade horizontal, entendida como tratamento igual de indivíduos que se encontram na mesma situação de saúde, tem sido investigada nos diferentes níveis de atenção à saúde. OBJETIVOS: O presente estudo busca verificar se existem disparidades no tempo de espera para cirurgias eletivas (safenectomia, colecistectomia, hemorroidectomia e histerectomia segundo o tipo de hospital, público ou privado. METODOLOGIA: Realizou-se, em Sorocaba, um estudo transversal com 40 pacientes atendidos por hospital privado e 40 atendidos por hospital público, no período de outubro e novembro de 2005. Além do tempo de espera e tipo de hospital, foram pesquisados sexo, idade, escolaridade, renda, situação conjugal, procedência, tipo de cirurgia realizada e presença de determinadas comorbidades. RESULTADOS: Observou-se um tempo de espera maior nas categorias: hospital público (5,5 meses; pINTRODUCTION: Analyzing the waiting time for certain elective surgeries (saphenectomy, cholecystectomy, hemorrhoidectomy, and hysterectomy according to hospital type, the present study intends to find if there are differences in health care. METHODS: A cross-sectional study was performed in Sorocaba with 40 individuals from a private hospital and 40 from a public hospital, interviewed in October and November 2005. RESULTS: A longer waiting time was observed for the following categories: public hospital (5.5 months; p<0.001, lower education (3.5 months; p<0.001, lower income (Spearman=-0.4426; p<0.001, residence out of Sorocaba (2 months; p=0.009, and saphenectomy (5 to 7 months; p=0.04. Adjusted for confounding, comorbidity, income, education, or residence variables, waiting time in public hospitals still was significantly longer (a difference of at least 4.93 months, when adjusted for income; 95%CI 3.4-6.4; p<0

  19. The effect of waiting: A meta-analysis of wait-list control groups in trials for tinnitus distress.

    Science.gov (United States)

    Hesser, Hugo; Weise, Cornelia; Rief, Winfried; Andersson, Gerhard

    2011-04-01

    The response rates and effects of being placed on a wait-list control condition are well documented in psychiatric populations. Despite the usefulness of such estimates and the frequent use of no-treatment controls in clinical trials for tinnitus, the effect of waiting in a tinnitus trial has not been investigated systematically. The aim of the present study was to quantify the overall effect of wait-list control groups on tinnitus distress. Studies were retrieved via a systematic review of randomised controlled trials of cognitive behaviour therapy for tinnitus distress. Outcomes of psychometrically robust tinnitus-specific measures (Tinnitus Handicap Inventory, Tinnitus Questionnaire, Tinnitus Reaction Questionnaire) from wait-list control groups were quantified using meta-analytic techniques. Percentage of change and standard mean difference effect sizes were calculated using the pre and post wait period. Eleven studies involving 314 wait-list subjects with tinnitus were located. The analysis for a waiting period of 6 to 12 weeks revealed a mean decrease in scores on tinnitus-specific measures of 3% to 8%. Across studies, a statically significant small mean within-group effect size was obtained (Hedges' g=.17). The effects were moderated by methodological quality of the trial, sample characteristics (i.e., age, tinnitus duration), time of the wait-list and how diagnosis was established. Subjects in a tinnitus trial improve in tinnitus distress over a short waiting phase. The effects of waiting are highly variable and depend on the characteristics of the sample and of the trial. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Use of gamma distributed residence times in pharmacokinetics.

    Science.gov (United States)

    Weiss, M

    1983-01-01

    Using a nonclassical statistically based pharmacokinetic concept, a theory is presented which can be applied to the analysis of concentration-time data fitted by power functions of time C = At-ae-bt, which is shown to be equivalent to the assumption of gamma distributed residence times of drugs. The shape and scale parameters a and b, respectively, are interpreted physiologically in terms of a recirculatory model. It is shown how the shape parameter a, which is only dependent on the coefficient of variation of residence times, is affected by the processes of drug distribution and elimination. The time course of the blood concentration following multiple doses and continuous infusion is predicted for gamma-like drug disposition curves. The assumption of gamma distributed disposition residence times is theoretically based on a random walk model of circulatory drug transport, and the conditions are investigated under which gamma curves can be empirically fitted to oral concentration-time data. The parameters of concentration-time profiles following solid dosage forms, for example, are explained by the means and coefficients of variation of the disposition residence time and dissolution time distribution, respectively. The advantages of this concept compared to the conventional method of fitting sums of exponentials to the data are described.

  1. Long-waiting outpatients: target audience for health education.

    Science.gov (United States)

    Bamgboye, E A; Jarallah, J S

    1994-04-01

    The study examines the meaning of waiting time in an outpatient department. Attention is payed to the activities of the patients and companions during the waiting time, the potential for health education programmes during the waiting time and the form such a health education programme should take. The setting was the King Khalid University Hospital Outpatient Department, Riyadh, Saudi Arabia. The study sample was selected by a systematic random sample approach of one in every 10 patients or companions visiting the clinic in a period of 2 weeks. The results showed an average waiting time of 148 min with a standard deviation of 11 min. Patients currently engage in reading, sleeping or talking during long waiting time. However, they showed a preference for health education programmes for specific diseases such as heart disease, diabetes mellitus and bowel diseases during the waiting time. Leaflets were favoured to be the most preferred mode for disseminating such information. A sizeable proportion of patients also wanted religious programmes included. We conclude that education programmes for preferred specific health topics at outpatient clinic services would be of potential benefit to patients' overall health.

  2. Time at your service : schedulability analysis of real-time and distributed services

    NARCIS (Netherlands)

    Jaghoori, Mohammad Mahdi

    2010-01-01

    The software today is distributed over several processing units. At a large scale this may span over the globe via the internet, or at the micro scale, a software may be distributed on several small processing units embedded in one device. Real-time distributed software and services need to be

  3. Real Time Synchronization for Creativity in Distributed Innovation Teams

    DEFF Research Database (Denmark)

    Peitersen, Dennis Kjaersgaard; Dolog, Peter; Pedersen, Esben Staunsbjerg

    2009-01-01

    In this paper we introduce a synchronization approach for real time collaborative sketching for creativity in distributed innovation teams. We base our approach on reverse AJAX. This way we ensure scalable solution for real time drawing and sketching important in creativity settings....

  4. Properties of Distributed Timed-Arc Petri Nets

    DEFF Research Database (Denmark)

    Nielsen, M.; Sassone, V.; Srba, J.

    2001-01-01

    In [12] we started a research on a distributed-timed extension of Petri nets where time parameters are associated with tokens and arcs carry constraints that qualify the age of tokens required for enabling. This formalism enables to model e.g. hardware architectures like GALS. We give a formal...

  5. Quantum arrival-time distributions from intensity functions

    DEFF Research Database (Denmark)

    Wlodarz, Joachim

    2002-01-01

    The quantum time-of-arrival problem is discussed within the standard formulation of nonrelativistic quantum mechanics with parametric time. It is shown that a general class of arrival-time probability distributions results from the assumption that the arrival process of a quantum particle...... is similar in nature to other time-dependent arrival-type processes occurring, e.g., in population biology or queue theory. A simple but illustrative example related to the well-known Wigner discussion of the time-energy uncertainty relation is given and the numerical results obtained are compared...... with Kijowski's distribution [Rep. Math. Phys. 6, 362 (1974)] of arrival times for a free quantum particle....

  6. Analysis of bluetooth and wi-fi technology to measure wait times of personal vehicles at Arizona-Mexico ports of entry.

    Science.gov (United States)

    2015-11-01

    Robust travel time data collection is possible using Bluetooth or Wi-Fi technology that : matches anonymous MAC addresses from discoverable electronic devices (e.g., smart phones) : to determine travel time along a roadway segment. Several hundred...

  7. Time dependent temperature distribution in pulsed Ti:sapphire lasers

    Science.gov (United States)

    Buoncristiani, A. Martin; Byvik, Charles E.; Farrukh, Usamah O.

    1988-01-01

    An expression is derived for the time dependent temperature distribution in a finite solid state laser rod for an end-pumped beam of arbitrary shape. The specific case of end pumping by circular (constant) or Gaussian beam is described. The temperature profile for a single pump pulse and for repetitive pulse operation is discussed. The particular case of the temperature distribution in a pulsed titanium:sapphire rod is considered.

  8. Execution time support for scientific programs on distributed memory machines

    Science.gov (United States)

    Berryman, Harry; Saltz, Joel; Scroggs, Jeffrey

    1990-01-01

    Optimizations are considered that are required for efficient execution of code segments that consists of loops over distributed data structures. The PARTI (Parallel Automated Runtime Toolkit at ICASE) execution time primitives are designed to carry out these optimizations and can be used to implement a wide range of scientific algorithms on distributed memory machines. These primitives allow the user to control array mappings in a way that gives an appearance of shared memory. Computations can be based on a global index set. Primitives are used to carry out gather and scatter operations on distributed arrays. Communications patterns are derived at runtime, and the appropriate send and receive messages are automatically generated.

  9. Modeling highway travel time distribution with conditional probability models

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira Neto, Francisco Moraes [ORNL; Chin, Shih-Miao [ORNL; Hwang, Ho-Ling [ORNL; Han, Lee [University of Tennessee, Knoxville (UTK)

    2014-01-01

    ABSTRACT Under the sponsorship of the Federal Highway Administration's Office of Freight Management and Operations, the American Transportation Research Institute (ATRI) has developed performance measures through the Freight Performance Measures (FPM) initiative. Under this program, travel speed information is derived from data collected using wireless based global positioning systems. These telemetric data systems are subscribed and used by trucking industry as an operations management tool. More than one telemetric operator submits their data dumps to ATRI on a regular basis. Each data transmission contains truck location, its travel time, and a clock time/date stamp. Data from the FPM program provides a unique opportunity for studying the upstream-downstream speed distributions at different locations, as well as different time of the day and day of the week. This research is focused on the stochastic nature of successive link travel speed data on the continental United States Interstates network. Specifically, a method to estimate route probability distributions of travel time is proposed. This method uses the concepts of convolution of probability distributions and bivariate, link-to-link, conditional probability to estimate the expected distributions for the route travel time. Major contribution of this study is the consideration of speed correlation between upstream and downstream contiguous Interstate segments through conditional probability. The established conditional probability distributions, between successive segments, can be used to provide travel time reliability measures. This study also suggests an adaptive method for calculating and updating route travel time distribution as new data or information is added. This methodology can be useful to estimate performance measures as required by the recent Moving Ahead for Progress in the 21st Century Act (MAP 21).

  10. Consequences of mixing assumptions for time-variable travel time distributions

    NARCIS (Netherlands)

    Velde, van der Y.; Heidbüchel, I.; Lyon, S.W.; Nyberg, L.; Rodhe, A.; Bishop, K.; Troch, P.A.

    2015-01-01

    The current generation of catchment travel time distribution (TTD) research, integrating nearly three decades of work since publication of Water's Journey from Rain to Stream, seeks to represent the full distribution in catchment travel times and its temporal variability. Here, we compare

  11. Sample path analysis and distributions of boundary crossing times

    CERN Document Server

    Zacks, Shelemyahu

    2017-01-01

    This monograph is focused on the derivations of exact distributions of first boundary crossing times of Poisson processes, compound Poisson processes, and more general renewal processes.  The content is limited to the distributions of first boundary crossing times and their applications to various stochastic models. This book provides the theory and techniques for exact computations of distributions and moments of level crossing times. In addition, these techniques could replace simulations in many cases, thus providing more insight about the phenomenona studied. This book takes a general approach for studying telegraph processes and is based on nearly thirty published papers by the author and collaborators over the past twenty five years.  No prior knowledge of advanced probability is required, making the book widely available to students and researchers in applied probability, operations research, applied physics, and applied mathematics. .

  12. Poverty Index With Time Varying Consumption and Income Distributions

    CERN Document Server

    Chattopadhyay, Amit K; Mallick, Sushanta K

    2016-01-01

    In a recent work (Chattopadhyay, A. K. et al, Europhys. Lett. {\\bf 91}, 58003, 2010) based on food consumption statistics, we showed how a stochastic agent based model could represent the time variation of the income distribution statistics in a developing economy, thereby defining an alternative \\enquote{poverty index} (PI) that largely agreed with poverty gap index data. This PI used two variables, the probability density function of the income statistics and a consumption deprivation (CD) function, representing the shortfall in the minimum consumption needed for survival. Since the time dependence of the CD function was introduced there through data extrapolation only and not through an endogenous time dependent series, this model left unexplained how the minimum consumption needed for survival varies with time. The present article overcomes these limitations and arrives at a new unified theoretical structure through time varying consumption and income distributions where trade is only allowed when the inc...

  13. Real-time systems design principles for distributed embedded applications

    CERN Document Server

    Kopetz, Hermann

    1997-01-01

    The book explains the relevance of recent scientific insights to the solution of everyday problems in the design and implementation of distributed and embedded real-time systems. Thus, as a reference source the book presents real-time technology in a concise and understandable manner. Because the cost-effectiveness of a particular method is of major concern in an industrial setting, design decisions are examined from an economic viewpoint. The recent appearance of cost-effective powerful system chips has tremendous influence on the architecture and economics of future distributed system soluti

  14. Time Synchronization and Distribution Mechanisms for Space Networks

    Science.gov (United States)

    Woo, Simon S.; Gao, Jay L.; Clare, Loren P.; Mills, David L.

    2011-01-01

    This work discusses research on the problems of synchronizing and distributing time information between spacecraft based on the Network Time Protocol (NTP), where NTP is a standard time synchronization protocol widely used in the terrestrial network. The Proximity-1 Space Link Interleaved Time Synchronization (PITS) Protocol was designed and developed for synchronizing spacecraft that are in proximity where proximity is less than 100,000 km distant. A particular application is synchronization between a Mars orbiter and rover. Lunar scenarios as well as outer-planet deep space mother-ship-probe missions may also apply. Spacecraft with more accurate time information functions as a time-server, and the other spacecraft functions as a time-client. PITS can be easily integrated and adaptable to the CCSDS Proximity-1 Space Link Protocol with minor modifications. In particular, PITS can take advantage of the timestamping strategy that underlying link layer functionality provides for accurate time offset calculation. The PITS algorithm achieves time synchronization with eight consecutive space network time packet exchanges between two spacecraft. PITS can detect and avoid possible errors from receiving duplicate and out-of-order packets by comparing with the current state variables and timestamps. Further, PITS is able to detect error events and autonomously recover from unexpected events that can possibly occur during the time synchronization and distribution process. This capability achieves an additional level of protocol protection on top of CRC or Error Correction Codes. PITS is a lightweight and efficient protocol, eliminating the needs for explicit frame sequence number and long buffer storage. The PITS protocol is capable of providing time synchronization and distribution services for a more general domain where multiple entities need to achieve time synchronization using a single point-to-point link.

  15. First-Passage-Time Distribution for Variable-Diffusion Processes

    Science.gov (United States)

    Barney, Liberty; Gunaratne, Gemunu H.

    2017-05-01

    First-passage-time distribution, which presents the likelihood of a stock reaching a pre-specified price at a given time, is useful in establishing the value of financial instruments and in designing trading strategies. First-passage-time distribution for Wiener processes has a single peak, while that for stocks exhibits a notable second peak within a trading day. This feature has only been discussed sporadically—often dismissed as due to insufficient/incorrect data or circumvented by conversion to tick time—and to the best of our knowledge has not been explained in terms of the underlying stochastic process. It was shown previously that intra-day variations in the market can be modeled by a stochastic process containing two variable-diffusion processes (Hua et al. in, Physica A 419:221-233, 2015). We show here that the first-passage-time distribution of this two-stage variable-diffusion model does exhibit a behavior similar to the empirical observation. In addition, we find that an extended model incorporating overnight price fluctuations exhibits intra- and inter-day behavior similar to those of empirical first-passage-time distributions.

  16. MicROS-drt: supporting real-time and scalable data distribution in distributed robotic systems.

    Science.gov (United States)

    Ding, Bo; Wang, Huaimin; Fan, Zedong; Zhang, Pengfei; Liu, Hui

    A primary requirement in distributed robotic software systems is the dissemination of data to all interested collaborative entities in a timely and scalable manner. However, providing such a service in a highly dynamic and resource-limited robotic environment is a challenging task, and existing robot software infrastructure has limitations in this aspect. This paper presents a novel robot software infrastructure, micROS-drt, which supports real-time and scalable data distribution. The solution is based on a loosely coupled data publish-subscribe model with the ability to support various time-related constraints. And to realize this model, a mature data distribution standard, the data distribution service for real-time systems (DDS), is adopted as the foundation of the transport layer of this software infrastructure. By elaborately adapting and encapsulating the capability of the underlying DDS middleware, micROS-drt can meet the requirement of real-time and scalable data distribution in distributed robotic systems. Evaluation results in terms of scalability, latency jitter and transport priority as well as the experiment on real robots validate the effectiveness of this work.

  17. Dwell time distributions of the molecular motor myosin V.

    Science.gov (United States)

    Bierbaum, Veronika; Lipowsky, Reinhard

    2013-01-01

    The dwell times between two successive steps of the two-headed molecular motor myosin V are governed by non-exponential distributions. These distributions have been determined experimentally for various control parameters such as nucleotide concentrations and external load force. First, we use a simplified network representation to determine the dwell time distributions of myosin V, with the associated dynamics described by a Markov process on networks with absorbing boundaries. Our approach provides a direct relation between the motor's chemical kinetics and its stepping properties. In the absence of an external load, the theoretical distributions quantitatively agree with experimental findings for various nucleotide concentrations. Second, using a more complex branched network, which includes ADP release from the leading head, we are able to elucidate the motor's gating effect. This effect is caused by an asymmetry in the chemical properties of the leading and the trailing head of the motor molecule. In the case of an external load acting on the motor, the corresponding dwell time distributions reveal details about the motor's backsteps.

  18. Distribution of residence times in bistable noisy systems with time-delayed feedback

    OpenAIRE

    Curtin, D.

    2004-01-01

    We analyze theoretically and experimentally the residence time distribution of bistable systems in the presence of noise and time-delayed feedback. We explain various nonexponential features of the residence time distribution using a two-state model and obtain a quantitative agreement with an experiment based on a Schmitt trigger. The limitations of the two-state model are also analyzed theoretically and experimentally using a semiconductor laser with optoelectronic feedback.

  19. Review of "Waiting for Superman"

    Science.gov (United States)

    Dutro, Elizabeth

    2011-01-01

    "Waiting for Superman" offers what appear to be straightforward, commonsense solutions to inequities in schooling. The film argues that heroic action can be taken to fix what it portrays as the disaster of public schooling. The film disregards poverty as a factor in school performance and connection--and therefore never addresses anti-poverty…

  20. The Design of a Real-Time Distributed System

    NARCIS (Netherlands)

    Hertzberger, L.O.; Mullender, S.J.; Poletiek, G.; van Renesse, R.; Tanenbaum, A.S.; Tuynman, F.; Vermeulen, J.C.

    1986-01-01

    In modern physics experiments an increasing number and variety of programmable processors is used. As a consequence, a software environment is needed that provides an integrated approach to development, testing and use of real-time distributed software. This contribution is based on work being done

  1. The shifted Wald distribution for response time data analysis

    NARCIS (Netherlands)

    Anders, R.; Alario, F.-X.; van Maanen, L.

    2016-01-01

    We propose and demonstrate the shifted Wald (SW) distribution as both a useful measurement tool and intraindividual process model for psychological response time (RT) data. Furthermore, we develop a methodology and fitting approach that readers can easily access. As a measurement tool, the SW

  2. ON THE RESIDENCE TIME DISTRIBUTION IN IDEALIZED GROUNDWATERSHEDS

    Science.gov (United States)

    The relative cumulative frequency distribution of residence times F(T) is calculated for an entire groundwatershed under steady-state conditions and assuming Dupuit-Forchheimer flow. It appears that F(T) is always the same: , provided that the aquifer recharge rate and are cons...

  3. Resource Optimization in Distributed Real-Time Multimedia Applications

    NARCIS (Netherlands)

    Yang, R.; van der Mei, R.D.; Roubos, D.; Seinstra, F.J.; Bal, H.E.

    2012-01-01

    The research area of multimedia content analysis (MMCA) considers all aspects of the automated extraction of knowledge from multimedia archives and data streams. To adhere to strict time constraints, large-scalemultimedia applications typically are being executed on distributed systems consisting of

  4. Interior effects on comfort in healthcare waiting areas.

    Science.gov (United States)

    Bazley, C; Vink, P; Montgomery, J; Hedge, A

    2016-07-21

    This study compared the effects of pre-experience and expectations on participant comfort upon waking, arrival to, and after an appointment, as well as the assessment of properly placed Feng Shui elements in three healthcare waiting rooms. Participants assessed comfort levels using self-report surveys. The researcher conducted 'intention interviews' with each doctor to assess the goals of each waiting area design, and conducted a Feng Shui assessment of each waiting area for properly placed Feng Shui elements. The waiting area designed by the Feng Shui expert rated 'most comfortable', followed by the waiting area design by a doctor, and the lowest comfort rating for the conventional waiting room design. Results show a sufficiently strong effect to warrant further research. Awareness of the external environment, paired with pre-experience and expectation, influences comfort for people over time. Fostering and encouraging a holistic approach to comfort utilizing eastern and western concepts and ergonomic principles creates a sense of "placeness" and balance in the design for comfort in built environments. This is new research information on the influences of the comfort experience over time, to include pre-experience, expectations and the placement of elements in the external environment.

  5. Real-time modeling and simulation of distribution feeder and distributed resources

    Science.gov (United States)

    Singh, Pawan

    The analysis of the electrical system dates back to the days when analog network analyzers were used. With the advent of digital computers, many programs were written for power-flow and short circuit analysis for the improvement of the electrical system. Real-time computer simulations can answer many what-if scenarios in the existing or the proposed power system. In this thesis, the standard IEEE 13-Node distribution feeder is developed and validated on a real-time platform OPAL-RT. The concept and the challenges of the real-time simulation are studied and addressed. Distributed energy resources include some of the commonly used distributed generation and storage devices like diesel engine, solar photovoltaic array, and battery storage system are modeled and simulated on a real-time platform. A microgrid encompasses a portion of an electric power distribution which is located downstream of the distribution substation. Normally, the microgrid operates in paralleled mode with the grid; however, scheduled or forced isolation can take place. In such conditions, the microgrid must have the ability to operate stably and autonomously. The microgrid can operate in grid connected and islanded mode, both the operating modes are studied in the last chapter. Towards the end, a simple microgrid controller modeled and simulated on the real-time platform is developed for energy management and protection for the microgrid.

  6. Distributed, Embedded and Real-time Java Systems

    CERN Document Server

    Wellings, Andy

    2012-01-01

    Research on real-time Java technology has been prolific over the past decade, leading to a large number of corresponding hardware and software solutions, and frameworks for distributed and embedded real-time Java systems.  This book is aimed primarily at researchers in real-time embedded systems, particularly those who wish to understand the current state of the art in using Java in this domain.  Much of the work in real-time distributed, embedded and real-time Java has focused on the Real-time Specification for Java (RTSJ) as the underlying base technology, and consequently many of the Chapters in this book address issues with, or solve problems using, this framework. Describes innovative techniques in: scheduling, memory management, quality of service and communication systems supporting real-time Java applications; Includes coverage of multiprocessor embedded systems and parallel programming; Discusses state-of-the-art resource management for embedded systems, including Java’s real-time garbage collect...

  7. Solving no-wait two-stage flexible flow shop scheduling problem with unrelated parallel machines and rework time by the adjusted discrete Multi Objective Invasive Weed Optimization and fuzzy dominance approach

    National Research Council Canada - National Science Library

    Hassan Jafarzadeh; Nazanin Moradinasab; Ali Gerami

    2017-01-01

    Purpose: Adjusted discrete Multi-Objective Invasive Weed Optimization (DMOIWO) algorithm, which uses fuzzy dominant approach for ordering, has been proposed to solve No-wait two-stage flexible flow shop scheduling problem...

  8. On response time and cycle time distributions in a two-stage cyclic queue

    NARCIS (Netherlands)

    Boxma, O.J.; Donk, P.

    1982-01-01

    We consider a two-stage closed cyclic queueing model. For the case of an exponential server at each queue we derive the joint distribution of the successive response times of a custumer at both queues, using a reversibility argument. This joint distribution turns out to have a product form. The

  9. Small dead-time expansion in counting distributions and moments

    Science.gov (United States)

    Ackermann, J.; Hogreve, H.

    2010-03-01

    Considering type I counters affected by a dead-time τ, we study the τ expansion of the probabilities and moments of the underlying stochastic renewal process. For the counting distributions and probabilities we extend results from the literature and analyse their approximation properties. Our results show, in particular, that for increasing counting numbers ever larger orders of the τ expansion are required for accurate approximations. Furthermore, the τ expansion for the first and second moments are obtained; their series is proved to coincide with the respective long time asymptotics. This asymptotics is demonstrated to converge exponentially fast to the exact quantities for growing time.

  10. Time series power flow analysis for distribution connected PV generation.

    Energy Technology Data Exchange (ETDEWEB)

    Broderick, Robert Joseph; Quiroz, Jimmy Edward; Ellis, Abraham; Reno, Matthew J.; Smith, Jeff; Dugan, Roger

    2013-01-01

    Distributed photovoltaic (PV) projects must go through an interconnection study process before connecting to the distribution grid. These studies are intended to identify the likely impacts and mitigation alternatives. In the majority of the cases, system impacts can be ruled out or mitigation can be identified without an involved study, through a screening process or a simple supplemental review study. For some proposed projects, expensive and time-consuming interconnection studies are required. The challenges to performing the studies are twofold. First, every study scenario is potentially unique, as the studies are often highly specific to the amount of PV generation capacity that varies greatly from feeder to feeder and is often unevenly distributed along the same feeder. This can cause location-specific impacts and mitigations. The second challenge is the inherent variability in PV power output which can interact with feeder operation in complex ways, by affecting the operation of voltage regulation and protection devices. The typical simulation tools and methods in use today for distribution system planning are often not adequate to accurately assess these potential impacts. This report demonstrates how quasi-static time series (QSTS) simulation and high time-resolution data can be used to assess the potential impacts in a more comprehensive manner. The QSTS simulations are applied to a set of sample feeders with high PV deployment to illustrate the usefulness of the approach. The report describes methods that can help determine how PV affects distribution system operations. The simulation results are focused on enhancing the understanding of the underlying technical issues. The examples also highlight the steps needed to perform QSTS simulation and describe the data needed to drive the simulations. The goal of this report is to make the methodology of time series power flow analysis readily accessible to utilities and others responsible for evaluating

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

    Science.gov (United States)

    Mangal, Haress; Kleinebudde, Peter

    2017-05-30

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

  12. Real-time dynamic imaging of virus distribution in vivo.

    Directory of Open Access Journals (Sweden)

    Sean E Hofherr

    2011-02-01

    Full Text Available The distribution of viruses and gene therapy vectors is difficult to assess in a living organism. For instance, trafficking in murine models can usually only be assessed after sacrificing the animal for tissue sectioning or extraction. These assays are laborious requiring whole animal sectioning to ascertain tissue localization. They also obviate the ability to perform longitudinal or kinetic studies in one animal. To track viruses after systemic infection, we have labeled adenoviruses with a near-infrared (NIR fluorophore and imaged these after intravenous injection in mice. Imaging was able to track and quantitate virus particles entering the jugular vein simultaneous with injection, appearing in the heart within 500 milliseconds, distributing in the bloodstream and throughout the animal within 7 seconds, and that the bulk of virus distribution was essentially complete within 3 minutes. These data provide the first in vivo real-time tracking of the rapid initial events of systemic virus infection.

  13. Real-time Control Mediation in Agile Distributed Software Development

    DEFF Research Database (Denmark)

    Persson, John Stouby; Aaen, Ivan; Mathiassen, Lars

    2008-01-01

    Agile distributed environments pose particular challenges related to control of quality and collaboration in software development. Moreover, while face-to-face interaction is fundamental in agile development, distributed environments must rely extensively on mediated interactions. On this backdrop......-time mediated control exchanges; and, that the actors, despite distances in space and culture, developed a clan-like pattern mediated by technology to help control quality and collaboration in software development......., we report from an in-depth case study of an agile distributed software project. Applying Kirsch’s elements of control framework, we analyze how actors in this context used different elements of control. We offer a description of the general management context and provide a detailed analysis of how...

  14. Implementation of a Wireless Time Distribution Testbed Protected with Quantum Key Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Bonior, Jason D [ORNL; Evans, Philip G [ORNL; Sheets, Gregory S [ORNL; Jones, John P [ORNL; Flynn, Toby H [ORNL; O' Neil, Lori Ross [Pacific Northwest National Laboratory (PNNL); Hutton, William [Pacific Northwest National Laboratory (PNNL); Pratt, Richard [Pacific Northwest National Laboratory (PNNL); Carroll, Thomas E. [Pacific Northwest National Laboratory (PNNL)

    2017-01-01

    Secure time transfer is critical for many timesensitive applications. the Global Positioning System (GPS) which is often used for this purpose has been shown to be susceptible to spoofing attacks. Quantum Key Distribution offers a way to securely generate encryption keys at two locations. Through careful use of this information it is possible to create a system that is more resistant to spoofing attacks. In this paper we describe our work to create a testbed which utilizes QKD and traditional RF links. This testbed will be used for the development of more secure and spoofing resistant time distribution protocols.

  15. Strength statistics and the distribution of earthquake interevent times

    Science.gov (United States)

    Hristopulos, Dionissios T.; Mouslopoulou, Vasiliki

    2013-02-01

    The Weibull distribution is often used to model the earthquake interevent times distribution (ITD). We propose a link between the earthquake ITD on single faults with the Earth’s crustal shear strength distribution by means of a phenomenological stick-slip model. For single faults or fault systems with homogeneous strength statistics and power-law stress accumulation we obtain the Weibull ITD. We prove that the moduli of the interevent times and crustal shear strength are linearly related, while the time scale is an algebraic function of the scale of crustal shear strength. We also show that logarithmic stress accumulation leads to the log-Weibull ITD. We investigate deviations of the ITD tails from the Weibull model due to sampling bias, magnitude cutoff thresholds, and non-homogeneous strength parameters. Assuming the Gutenberg-Richter law and independence of the Weibull modulus on the magnitude threshold, we deduce that the interevent time scale drops exponentially with the magnitude threshold. We demonstrate that a microearthquake sequence from the island of Crete and a seismic sequence from Southern California conform reasonably well to the Weibull model.

  16. Lightweight distributed computing for intraoperative real-time image guidance

    Science.gov (United States)

    Suwelack, Stefan; Katic, Darko; Wagner, Simon; Spengler, Patrick; Bodenstedt, Sebastian; Röhl, Sebastian; Dillmann, Rüdiger; Speidel, Stefanie

    2012-02-01

    In order to provide real-time intraoperative guidance, computer assisted surgery (CAS) systems often rely on computationally expensive algorithms. The real-time constraint is especially challenging if several components such as intraoperative image processing, soft tissue registration or context aware visualization are combined in a single system. In this paper, we present a lightweight approach to distribute the workload over several workstations based on the OpenIGTLink protocol. We use XML-based message passing for remote procedure calls and native types for transferring data such as images, meshes or point coordinates. Two different, but typical scenarios are considered in order to evaluate the performance of the new system. First, we analyze a real-time soft tissue registration algorithm based on a finite element (FE) model. Here, we use the proposed approach to distribute the computational workload between a primary workstation that handles sensor data processing and visualization and a dedicated workstation that runs the real-time FE algorithm. We show that the additional overhead that is introduced by the technique is small compared to the total execution time. Furthermore, the approach is used to speed up a context aware augmented reality based navigation system for dental implant surgery. In this scenario, the additional delay for running the computationally expensive reasoning server on a separate workstation is less than a millisecond. The results show that the presented approach is a promising strategy to speed up real-time CAS systems.

  17. Towards the distribution network of time and frequency

    Science.gov (United States)

    Lipiński, M.; Krehlik, P.; Śliwczyński, Ł.; Buczek, Ł.; Kołodziej, J.; Nawrocki, J.; Nogaś, P.; Dunst, P.; Lemański, D.; Czubla, A.; Pieczerak, J.; Adamowicz, W.; Pawszak, T.; Igalson, J.; Binczewski, A.; Bogacki, W.; Ostapowicz, P.; Stroiński, M.; Turza, K.

    2014-05-01

    In the paper the genesis, current stage and perspectives of the OPTIME project are described. The main goal of the project is to demonstrate that the newdeveloped at AGH technology of fiber optic transfer of the atomic clocks reference signals is ready to be used in building the domestic Time and Frequency distribution network. In the first part we summarize the two-year continuous operation of 420 kmlong link connecting the Laboratory of Time and Frequency at Central Office of Measures GUM in Warsaw and Time Service Laboratory at Astrogeodynamic Obserwatory AOS in Borowiec near Poznan. For the first time, we are reporting the two year comparison of UTC(PL) and UTC(AOS) atomic timescales with this link, and we refer it to the results of comparisons performed by GPS-based methods. We also address some practical aspects of maintaining time and frequency dissemination over fiber optical network. In the second part of the paper the concept of the general architecture of the distribution network with two Reference Time and Frequency Laboratories and local repositories is proposed. Moreover the brief project of the second branch connecting repositories in Poznan Polish Supercomputing and Networking Center and Torun Nicolaus Copernicus University with the first end-users in Torun such as National Laboratory of Atomic, Molecular and Optical Physics and Nicolaus Copernicus Astronomical Center is described. In the final part the perspective of developing the network both in the domestic range as far as extention with the international connections possibilities are presented.

  18. Analysis and Optimization of Distributed Real-Time Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    2006-01-01

    characteristic to this class of systems: mapping of functionality, the optimization of the access to the communication channel, and the assignment of scheduling policies to processes. Optimization heuristics aiming at producing a schedulable system, with a given amount of resources, are presented....... and scheduling policies. In this context, the task of designing such systems is becoming increasingly difficult. The success of new adequate design methods depends on the availability of efficient analysis as well as optimization techniques. In this paper, we present both analysis and optimization approaches...... for such heterogeneous distributed real-time embedded systems. More specifically, we discuss the schedulability analysis of hard real-time systems, highlighting particular aspects related to the heterogeneous and distributed nature of the applications. We also introduce several design optimization problems...

  19. A time reference distribution concept for a time division communication network

    Science.gov (United States)

    Stover, H. A.

    1973-01-01

    Starting with an assumed ideal network having perfect clocks at every node and known fixed transmission delays between nodes, the effects of adding tolerances to both transmission delays and nodal clocks is described. The advantages of controlling tolerances on time rather than frequency are discussed. Then a concept is presented for maintaining these tolerances on time throughout the network. This concept, called time reference distribution, is a systematic technique for distributing time reference to all nodes of the network. It is reliable, survivable and possesses many other desirable characteristics. Some of its features such as an excellent self monitoring capability will be pointed out. Some preliminary estimates of the accuracy that might be expected are developed and there is a brief discussion of the impact upon communication system costs. Time reference distribution is a concept that appears very attractive. It has not had experimental evaluation and has not yet been endorsed for use in any communication network.

  20. Blind Reverberation Time Estimation Based on Laplace Distribution

    OpenAIRE

    Jan, Tariqullah; Wang, Wenwu

    2012-01-01

    We propose an algorithm for the estimation of reverberation time (RT) from the reverberant speech signal by using a maximum likelihood (ML) estimator. Based on the analysis of an existing RT estimation method, which models the reverberation decay as a Gaussian random process modulated by a deterministic envelope, a Laplacian distribution based decay model is proposed in which an efficient procedure for locating free decay from reverberant speech is also incorporated. Then the RT is estimated ...

  1. The relationship between health locus of control, depression, and sociodemographic factors and amount of time breast cancer patients wait before seeking diagnosis and treatment.

    Science.gov (United States)

    Marijanović, Inga; Pavleković, Gordana; Buhovac, Teo; Martinac, Marko

    2017-09-01

    In the Federation of Bosnia and Herzegovina, the prevalence and incidence of breast cancer has been increasing, and the national programme of early prevention, administered locally, is sporadic and without quality assurance. While many factors may influence women's decision to adopt prevention-oriented behaviours regarding breast cancer, this study has emphasised the importance of sociodemographic factors, psychological factors and mental wellbeing. Participants in the study were all patients who, during one year, were admitted for the first time for diagnosis and treatment in the biggest Clinical hospitals of the Herzegovina-Neretva region Patients were divided into two groups based on their TNM classification: "early stage" and "late stage". Three instruments were used in this study: an individual questionnaire about demographic and socioeconomic characteristics of the woman, the Multidimensional Health Locus of Control scales, and the Hamilton Depression Rating Scale. The majority of patients diagnosed with advanced disease were admitted to hospital in the late/advanced stages of the disease. Multi-variant analysis showed that the most statistically significant positive predictor for early admittance in hospital is living with family and marital status while religiosity has a negative predictive value. The results indicate that 59.7% of respondents do not have depression, while the remainder do have some degree of depression. There was no statistically significant difference in the degree of depression between women who were diagnosed and treated early and those who were not. The employment status of the respondents was the only significant factor related to degree of depression. Although health locus of control and depression are not statistically significant predictors of early hospital treatment, the recommendation is that further studies focus on the implementation of MHLC and HDRS scales within the community. This could be useful in planning appropriate and

  2. On enhanced time-varying distributed H systems

    Directory of Open Access Journals (Sweden)

    Sergey Verlan

    2002-11-01

    Full Text Available An enhanced time-varying distributed H system (ETVDH system is a slightly different definition of the time-varying distributed H system (TVDH system [9] and it was proposed by M. Margenstern and Yu. Rogozhin in [4] under the name of "extended time-varying distributed H system''. The main difference is that the components of the ETVDH system are H systems and therefore splicing rules may be applied more than once as it is done in TVDH systems. This leads to difficulties in investigating the behavior of such systems because they have a higher level of parallelism. It is proved that ETVDH systems of degree 2 (i.e. with 2 components generate all recursively enumerable languages in a sequential way [7] and that ETVDH systems of degree 4 generate all recursively enumerable languages in a "parallel'' way, modelling a formal type-0 grammar [11]. In this paper we improve the last result and we present an ETVDH system of degree 3 which generates all recursively enumerable languages modelling type-0 formal grammars. The problem of the existence of ETVDH systems of degree 2 which generate all recursively enumerable languages in a "parallel'' way is left open.

  3. Time-Mean Helicity Distribution in Turbulent Swirling Jets

    Directory of Open Access Journals (Sweden)

    V. Tesař

    2005-01-01

    Full Text Available Helicity offers an alternative approach to investigations of the structure of turbulent flows. Knowledge of the spatial distribution of the time-mean component of helicity is the starting point. Yet very little is known even about basic cases in which Helicity plays important role, such as the case of a swirling jet. This is the subject of the present investigations, based mainly on numerical flowfield computations. The region of significantly large time-mean helicity density is found only in a rather small region reaching to several nozzle diameters downstream from the exit. The most important result is the similarity of the helicity density profiles. 

  4. Reliability of Distribution Systems with Effect of Time-Varying-Repair Time and Time-Varying Weight Factors

    Science.gov (United States)

    Eshtehardiha, S.; Poudeh, M. Bayati

    2008-10-01

    Reliable evaluation of distribution systems is of high importance in the maintenance and expansion of these systems. A time-sequential simulation technique is presented in this paper in which the effects of weather conditions and maintenance methods in the assessment of reliable cost of integrated distribution systems are provided. Time-Varying Weight Factors (TVWF) are defined to investigate the effect of weather conditions and present maintenance methods on Failure rates (FR). In fact, the average Failure Rate (FR) is combined with TVWF to provide time-varying repair times (TVRT) for each component. Similarly, the average Repair Time (RT) is also combined with TVWF to produce Time-Varying-Repair Time (TVRT). An experimental distribution system showed that TVFR has more effects on the interruption costs of the sensitive costumers. It has also significant effects on the indices of all costumers. So, it is necessary to consider TVRT in evaluating the reliability of the network cost.

  5. Earthquake interevent time distribution in Kachchh, Northwestern India

    Science.gov (United States)

    Pasari, Sumanta; Dikshit, Onkar

    2015-08-01

    Statistical properties of earthquake interevent times have long been the topic of interest to seismologists and earthquake professionals, mainly for hazard-related concerns. In this paper, we present a comprehensive study on the temporal statistics of earthquake interoccurrence times of the seismically active Kachchh peninsula (western India) from thirteen probability distributions. Those distributions are exponential, gamma, lognormal, Weibull, Levy, Maxwell, Pareto, Rayleigh, inverse Gaussian (Brownian passage time), inverse Weibull (Frechet), exponentiated exponential, exponentiated Rayleigh (Burr type X), and exponentiated Weibull distributions. Statistical inferences of the scale and shape parameters of these distributions are discussed from the maximum likelihood estimations and the Fisher information matrices. The latter are used as a surrogate tool to appraise the parametric uncertainty in the estimation process. The results were found on the basis of two goodness-of-fit tests: the maximum likelihood criterion with its modification to Akaike information criterion (AIC) and the Kolmogorov-Smirnov (K-S) minimum distance criterion. These results reveal that (i) the exponential model provides the best fit, (ii) the gamma, lognormal, Weibull, inverse Gaussian, exponentiated exponential, exponentiated Rayleigh, and exponentiated Weibull models provide an intermediate fit, and (iii) the rest, namely Levy, Maxwell, Pareto, Rayleigh, and inverse Weibull, fit poorly to the earthquake catalog of Kachchh and its adjacent regions. This study also analyzes the present-day seismicity in terms of the estimated recurrence interval and conditional probability curves (hazard curves). The estimated cumulative probability and the conditional probability of a magnitude 5.0 or higher event reach 0.8-0.9 by 2027-2036 and 2034-2043, respectively. These values have significant implications in a variety of practical applications including earthquake insurance, seismic zonation

  6. The Influence of Ambient Scent and Music on Patients' Anxiety in a Waiting Room of a Plastic Surgeon

    NARCIS (Netherlands)

    Fenko, Anna; Loock, Caroline

    2014-01-01

    OBJECTIVE: This study investigates the influence of ambient scent and music, and their combination, on patients' anxiety in a waiting room of a plastic surgeon. BACKGROUND: Waiting for an appointment with a plastic surgeon can increase a patient's anxiety. It is important to make the waiting time

  7. Time-optimal control of infinite order distributed parabolic systems involving time lags

    Directory of Open Access Journals (Sweden)

    G.M. Bahaa

    2014-06-01

    Full Text Available A time-optimal control problem for linear infinite order distributed parabolic systems involving constant time lags appear both in the state equation and in the boundary condition is presented. Some particular properties of the optimal control are discussed.

  8. Generalized Poisson-Lindely Distribution in Promotion Time Cure Model

    Directory of Open Access Journals (Sweden)

    Ahmad Reza Baghestani

    2014-12-01

    Full Text Available 1024x768 Long-term survival analysis has been improved in the last decade and most of the models concentrate on the promotion time cure model that proposed by Chen (1999. These models are based on the distribution of latent variable N, number of initiated node cells. In this paper we proposed a Generalized Poisson-Lindely distribution that is another option instead of Negative Binomial distribution when there is overdispersion. The results indicated a better fitness compared to others, because of its more flexibility. Parameter estimation has been done by Bayesian approach, in a real data set and a simulation study has shown the advantages of proposed model. Normal 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}

  9. Regional differences in waiting time to pregnancy

    DEFF Research Database (Denmark)

    Juul, Svend; Karmaus, W; Olsen, Jørn

    1999-01-01

    of the pregnancies were planned (64%) and approximately 14% were the result of contraceptive failures. The study shows that smoking, body mass index, age and parity did not explain the differences in fecundity found between the centres. Regional differences in fecundity exist and the causes may be genetic or due...

  10. Analysis and Synthesis of Distributed Real-Time Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    Embedded computer systems are now everywhere: from alarm clocks to PDAs, from mobile phones to cars, almost all the devices we use are controlled by embedded computers. An important class of embedded computer systems is that of hard real-time systems, which have to fulfill strict timing requireme......Embedded computer systems are now everywhere: from alarm clocks to PDAs, from mobile phones to cars, almost all the devices we use are controlled by embedded computers. An important class of embedded computer systems is that of hard real-time systems, which have to fulfill strict timing....... The systems are heterogeneous not only in terms of hardware components, but also in terms of communication protocols and scheduling policies. Regarding this last aspect, time-driven and event-driven systems, as well as a combination of the two, are considered. Such systems are used in many application areas...... of the communication infrastructure, which has a significant impact on the overall system performance and cost. Analysis and Synthesis of Distributed Real-Time Embedded Systems considers the mapping and scheduling tasks within an incremental design process. To reduce the time-to-market of products, the design of real...

  11. A Distributed Synchronization and Timing System on the EAST Tokamak

    Science.gov (United States)

    Luo, Jiarong; Wu, Yichun; Shu, Yantai

    2008-08-01

    A key requirement for the EAST distributed control system (EASTDCS) is time synchronization to an accuracy of AVR microcontroller and the Nut/OS embedded Real Time Operating System (RTOS). The DSTS provides the control and the data acquisition systems with reference clocks (0.01 Hz 10 MHz) and delayed trigger times ( 1 mus 4294 s). These are produced by a Core Module Unit (CMU) connected by optical fibres to many Local Synchronized Node Units (LSNU). The fibres provide immunity from electrical noise and are of equal length to match clock and trigger delays between systems. This paper describes the architecture of the DSTS on the EAST tokamak and provides an overview of the characteristics of the main and local units.

  12. 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-burner ......, well characterised flow pattern makes it possible to investigate the importance of mixing intensity on the (pollution) chemistry in furnaces. The reactor model developed here will be the basis for the development of a chemical reaction engineering combustion model....

  13. UASB reactor hydrodynamics: residence time distribution and proposed modelling tools.

    Science.gov (United States)

    López, I; Borzacconi, L

    2010-05-01

    The hydrodynamic behaviour of UASB (Up Flow Anaerobic Sludge Blanket) reactors based on residence time distribution curves allows the implementation of global models, including the kinetic aspects of biological reactions. The most relevant hydrodynamic models proposed in the literature are discussed and compared with the extended tanks in series (ETIS) model. Although derived from the tanks in series model, the ETIS model's parameter is not an integer. The ETIS model can be easily solved in the Laplace domain and applied to a two-stage anaerobic digestion linear model. Experimental data from a 250 m3 UASB reactor treating malting wastewater are used to calibrate and validate the proposed model.

  14. Directional short-time Fourier transform of distributions

    Directory of Open Access Journals (Sweden)

    Katerina Hadzi-Velkova Saneva

    2016-04-01

    Full Text Available Abstract In this paper we consider the directional short-time Fourier transform (DSTFT that was introduced and investigated in (Giv in J. Math. Anal. Appl. 399:100-107, 2013. We analyze the DSTFT and its transpose on test function spaces S ( R n $\\mathcal {S}(\\mathbb {R}^{n}$ and S ( Y 2 n $\\mathcal {S}(\\mathbb {Y}^{2n}$ , respectively, and prove the continuity theorems on these spaces. Then the obtained results are used to extend the DSTFT to spaces of distributions.

  15. Fission product studies at WAIT

    Energy Technology Data Exchange (ETDEWEB)

    De Laeter, J.R.; Rosman, K.J.R.; Loss, R.D. (Western Australian Inst. of Tech., South Bentley)

    1985-07-01

    A general review of fission yields is presented. The Mass Spectrometry Laboratory in the Department of Applied Physics at WAIT has been involved in a continuing programme of measuring the cumulative fission yields of the elements palladium, silver, cadmium, tin and tellurium for a variety of fissile materials (/sup 233/U, /sup 235/U, /sup 238/U and /sup 239/Pu) over a range of neutron energies. Results of studies into the isotopic composition and fission yields of samples from the Oklo natural reactor in Gabon, West Africa are summarised.

  16. Modeling residence-time distribution in horizontal screw hydrolysis reactors

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, David A.; Stickel, Jonathan J.

    2018-01-01

    The dilute-acid thermochemical hydrolysis step used in the production of liquid fuels from lignocellulosic biomass requires precise residence-time control to achieve high monomeric sugar yields. Difficulty has been encountered reproducing residence times and yields when small batch reaction conditions are scaled up to larger pilot-scale horizontal auger-tube type continuous reactors. A commonly used naive model estimated residence times of 6.2-16.7 min, but measured mean times were actually 1.4-2.2 the estimates. This study investigated how reactor residence-time distribution (RTD) is affected by reactor characteristics and operational conditions, and developed a method to accurately predict the RTD based on key parameters. Screw speed, reactor physical dimensions, throughput rate, and process material density were identified as major factors affecting both the mean and standard deviation of RTDs. The general shape of RTDs was consistent with a constant value determined for skewness. The Peclet number quantified reactor plug-flow performance, which ranged between 20 and 357.

  17. Time and temporality: linguistic distribution in human life-games

    DEFF Research Database (Denmark)

    Cowley, Stephen

    2014-01-01

    While clock-time can be used to clarify facts, all living systems construct their own temporalities. Having illustrated the claim for foxtail grasses, it is argued that, with motility and brains, organisms came to use temporalities that build flexibility into behavior. With the rise of human...... culture, individuals developed a knack of using linguistic distribution to link metabolism with collective ways of assessing and managing experience. Of human temporal management, the best known case is the mental time travel enabled by, among other functions, autobiographical memory. One contribution...... of this special issue is to show many ways in which temporality connects up circumstances, goals, perception, attention and modes of recall. It can be hypothesized that temporalities evolve because the relevant skills reduce uncertainties. Using cases from blogging, problem solving and doctor-patient interaction...

  18. Integrodifferential diffusion equation for continuous-time random walk.

    Science.gov (United States)

    Fa, Kwok Sau; Wang, K G

    2010-01-01

    In this paper, we present an integrodifferential diffusion equation for continuous-time random walk that is valid for a generic waiting time probability density function. Using this equation, we also study diffusion behaviors for a couple of specific waiting time probability density functions such as exponential and a combination of power law and generalized Mittag-Leffler function. We show that for the case of the exponential waiting time probability density function, a normal diffusion is generated and the probability density function is Gaussian distribution. In the case of the combination of a power law and generalized Mittag-Leffler waiting probability density function, we obtain the subdiffusive behavior for all the time regions from small to large times and probability density function is non-Gaussian distribution.

  19. Real-time Trading Strategies for Proactive Distribution Company with Distributed Generation and Demand Response

    DEFF Research Database (Denmark)

    Wang, Qi

    ) directly procuring capacities from local DG and DR. In this situation, a hierarchical market structure is achieved comprising the transmission-level (TL) and distribution-level (DL) markets. Focusing on the real-time process, as the interface actor, the DISCO's behavior covers downwardly procuring DL DG...... and DR resources, and upwardly trading in the TL real-time market, resulting in a proactive manner. The DL aggregator (DA) is dened to manage these small-scale and dispersed DGs and DRs. A methodology is proposed in this thesis for a proactive DISCO (PDISCO) to strategically trade with DAs...... in the presented DL market and transact with TL real-time market. A one-leader multi-follower-type bi-level model is proposed to indicate the PDISCO's trading strategies. To participate in the TL real-time market, a methodology is presented to derive continuous bidding/offering strategies for a PDISCO. A bi...

  20. Real-time and fault tolerance in distributed control software

    NARCIS (Netherlands)

    Orlic, B.; Broenink, Johannes F.

    2003-01-01

    Closed loop control systems typically contain multitude of spatially distributed sensors and actuators operated simultaneously. So those systems are parallel and distributed in their essence. But mapping this parallelism onto the given distributed hardware architecture, brings in some additional

  1. Reasons military patients with primary care access leave an emergency department waiting room before seeing a provider.

    Science.gov (United States)

    Varney, Shawn M; Vargas, Toni E; Pitotti, Rebecca L; Bebarta, Vikhyat S

    2012-10-01

    Our objective was to assess patients' understanding of emergency department (ED) wait times and why patients may leave the waiting room before seeing a provider. Survey of patients in the ED waiting room of an urban tertiary care military hospital where civilian and military patients are treated. A total of 508/517 surveys (98%) were completed. Age ranges were 18 to 35 years (49%), 36 to 60 (31%), or older than 60 (20%). Education levels were high school (20%), some college (37%), or college graduate (39%). Of 503 respondents, 125 (25%) had left an ED waiting room before seeing a provider. The reasons included excessive wait times (91%) and family responsibilities (5%). Five hundred eight reported the factors that would motivate them to wait to see the physician (not leave without being seen [LWOBS]) were the severity of illness (64%), and if they received an update of wait times (26%); 82% (391/480) understood that severely ill patients were seen first. Patients attributed long wait times to doctors and nurses caring for other patients (292/583, 50%) and insufficient physician and nurse staffing (245, 42%). Of 802 responses for ideas to improve the wait, 34% said regular updates on estimated wait times, 21% said television shows or movies to view, 20% said books and magazines to read, and 11% said computers to access. Long wait times were the primary reason that patients left before seeing a provider, despite having ready access to care. Respondents attributed long wait times to patient volume and inadequate staffing. Regular updates on wait times and material for entertainment may improve the waiting experience and reduce LWOBS.

  2. Reevaluation of transit time distributions, mean transit times and their relation to catchment topography

    Science.gov (United States)

    Seeger, S.; Weiler, M.

    2014-12-01

    The transit time of water is a fundamental property of catchments, revealing information about the flow pathways, source of water and storage in a single integrated measure. While several studies have investigated the relationship between catchment topography and transit times, few studies expanded the analysis to a wide range of catchment properties and assessed the influence of the selected transfer function (TF) model. We used stable water isotopes from mostly baseflow samples with lumped convolution models of time-invariant TFs to estimate the transit time distributions of 24 meso-scale catchments covering different geomorphic and geologic regions in Switzerland. The sparse network of 13 precipitation isotope sampling sites required the development of a new spatial interpolation method for the monthly isotopic composition of precipitation. A point-energy-balance based snow model was adapted to account for the seasonal water isotope storage in snow dominated catchments. Transit time distributions were estimated with three established TFs (exponential, gamma distribution and two parallel linear reservoirs). While the exponential TF proved to be less suitable to simulate the isotopic signal in most of the catchments, the gamma distribution and the two parallel linear reservoirs transfer function reached similarly good model fits to the fortnightly observed isotopic compositions in discharge, although in many catchments the transit time distributions implied by equally well fitted models differed markedly from each other and in extreme cases, the resulting mean transit time (MTT) differed by orders of magnitude. A more thorough comparison showed that equally suited models corresponded to agreeing values of cumulated transit time distributions only between 3 and 6 months. The short-term ( 3 years) could hardly be assessed by means of stable water isotopes, resulting in ambiguous MTT and hence questioning the relevance of an MTT determined with stable isotopes

  3. Timing Analysis of Mixed-Criticality Hard Real-Time Applications Implemented on Distributed Partitioned Architectures

    DEFF Research Database (Denmark)

    Marinescu, Sorin Ovidiu; Tamas-Selicean, Domitian; Acretoaie, Vlad

    In this paper we are interested in the timing analysis of mixed-criticality embedded real-time applications mapped on distributed heterogeneous architectures. Mixedcriticality tasks can be integrated onto the same architecture only if there is enough spatial and temporal separation among them. We...... in partitions using fixedpriority preemptive scheduling. We have extended the stateof- the-art algorithms for schedulability analysis to take into account the partitions. The proposed algorithm has been evaluated using several synthetic and real-life benchmarks....

  4. Watchful Waiting Strategy May Reduce Low-Value Diagnostic Testing.

    Science.gov (United States)

    May, Larissa; Franks, Peter; Jerant, Anthony; Fenton, Joshua

    PCPs need effective communication strategies to address patient requests for low-value testing while sustaining patient-provider partnerships. Watchful waiting - allowing a negotiated period of time to pass before making a firm testing decision - shows promise as a tool for addressing patient requests for low-value testing. Observational analysis of data from a randomized controlled trial of a communication intervention designed to boost patient-centeredness and reduce low-value test ordering among 61 resident primary care physicians. Intervention effectiveness was assessed during follow-up encounters of unannounced standardized patients (SPs) who requested low-value tests. We examined associations between five physician counseling behaviors and overall patient-centeredness (Measure of Patient-Centered Communication) and requested test ordering. During 155 SP encounters, residents most commonly used reassurance (96% of encounters), evidence-based recommendations (97%), and watchful waiting (68 %). Resident advice to pursue watchful waiting was associated with 39% lower likelihood of test ordering (adjusted marginal effect of -38.6% [95% CI -43.6 to -33.6]). When all communication behaviors were examined together, only watchful waiting was significantly associated with test ordering (marginal effect of -38% [95% CI -44.3% to -31.7%]). Overall patient-centeredness was not associated with low-value testing. Resident physician counseling to pursue watchful waiting was associated with less ordering of requested low-value diagnostic tests, while overall patient-centeredness was not. © Copyright 2016 by the American Board of Family Medicine.

  5. Handgun waiting periods reduce gun deaths.

    Science.gov (United States)

    Luca, Michael; Malhotra, Deepak; Poliquin, Christopher

    2017-11-14

    Handgun waiting periods are laws that impose a delay between the initiation of a purchase and final acquisition of a firearm. We show that waiting periods, which create a "cooling off" period among buyers, significantly reduce the incidence of gun violence. We estimate the impact of waiting periods on gun deaths, exploiting all changes to state-level policies in the Unites States since 1970. We find that waiting periods reduce gun homicides by roughly 17%. We provide further support for the causal impact of waiting periods on homicides by exploiting a natural experiment resulting from a federal law in 1994 that imposed a temporary waiting period on a subset of states. Copyright © 2017 the Author(s). Published by PNAS.

  6. Stability of stationary and time-varying nongyrotropic particle distributions

    Directory of Open Access Journals (Sweden)

    A. L. Brinca

    Full Text Available The ubiquity of nongyrotropic particle populations in space plasmas warrants the study of their characteristics, in particular their stability. The unperturbed nongyrotropic distribution functions in homogeneous media without sources and sinks (closed phase space must be rotating and time-varying (TNG, whereas consideration of open phase spaces allows for the occurrence of homogeneous and stationary distributions (SNG. The free energy brought about by the introduction of gyrophase organization in a particle population can destabilize otherwise thoroughly stable magnetoplasmas (or, a fortiori, enhance pre-existing gyrotropic instabilities and feed intense wave growth both in TNG and SNG environments: The nongyrotropic (electron or ion species can originate unstable coupling among the gyrotropic characteristic waves. The stability properties of these two types of homogeneous nongyrotropy shall be contrasted for parallel (with respect to the ambient magnetic field and perpendicular propagation, and their potential role as wave activity sources shall be illustrated resorting to solutions of the appropriate dispersion equations and numerical simulations.

    Key words. Space plasma physics (waves and instabilities · Magnetospheric physics (plasma waves and instabilities · Interplanetary physics (plasma waves and turbulence

  7. Specificity and completion time distributions of biochemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Munsky, Brian [Los Alamos National Laboratory; Nemenman, Ilya [Los Alamos National Laboratory; Bel, Golan [Los Alamos National Laboratory

    2009-01-01

    In order to produce specific complex structures from a large set of similar biochemical building blocks, many biochemical systems require high sensitivity to small molecular differences. The first and most common mqdel used to explain this high specificity is kinetic proofreading, which has been extended to a variety of systems from detection of DNA mismatch to cell signaling processes. While the specification properties of the kinetic proofreading model are well known and were studied in various contexts, very little is known about its temporal behavior. In this work, we study the dynamical properties of discrete stochastic two-branch kinetic proofreading schemes. Using the Laplace transform of the corresponding chemical master equation, we obtain an analytical solution for the completion time distribution. In particular we provide expressions for the specificity and the mean and the variance of the process completion times. We also show that, for a wide range of parameters a process distinguishing between two different products can be reduced to a much simpler three point process. Our results allow for the systematic study of the interplay between specificity and completion times as well as testing the validity of the kinetic proofreading model in biological systems.

  8. Continuous time modelling of dynamical spatial lattice data observed at sparsely distributed times

    DEFF Research Database (Denmark)

    Rasmussen, Jakob Gulddahl; Møller, Jesper

    2007-01-01

    Summary. We consider statistical and computational aspects of simulation-based Bayesian inference for a spatial-temporal model based on a multivariate point process which is only observed at sparsely distributed times. The point processes are indexed by the sites of a spatial lattice......, and they exhibit spatial interaction. For specificity we consider a particular dynamical spatial lattice data set which has previously been analysed by a discrete time model involving unknown normalizing constants. We discuss the advantages and disadvantages of using continuous time processes compared...

  9. The shifted Wald distribution for response time data analysis.

    Science.gov (United States)

    Anders, Royce; Alario, F-Xavier; Van Maanen, Leendert

    2016-09-01

    We propose and demonstrate the shifted Wald (SW) distribution as both a useful measurement tool and intraindividual process model for psychological response time (RT) data. Furthermore, we develop a methodology and fitting approach that readers can easily access. As a measurement tool, the SW provides a detailed quantification of the RT data that is more sophisticated than mean and SD comparisons. As an intraindividual process model, the SW provides a cognitive model for the response process in terms of signal accumulation and the threshold needed to respond. The details and importance of both of these features are developed, and we show how the approach can be easily generalized to a variety of experimental domains. The versatility and usefulness of the approach is demonstrated on 3 published data sets, each with a different canonical mode of responding: manual, vocal, and oculomotor modes. In addition, model-fitting code is included with the article. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  10. How Long Are Patients Willing to Wait in the Emergency Department Before Leaving Without Being Seen?

    Directory of Open Access Journals (Sweden)

    Michael N Brodeur

    2012-12-01

    Full Text Available Introduction: Our goal was to evaluate patients’ threshold for waiting in an emergency department(ED waiting room before leaving without being seen (LWBS. We analyzed whether willingness to wait was influenced by perceived illness severity, age, race, triage acuity level, or insurance status.Methods: We conducted this survey-based study from March to July 2010 at an urban academic medical center. After triage, patients were given a multiple-choice questionnaire, designed to as certain how long they would wait for medical care. We collected data including age, gender, race,insurance status, and triage acuity level. We looked at the association between willingness to wait and these variables, using stratified analysis and logistic regression.Results: Of the 375 patients who were approached, 340 (91% participated. One hundred seventy one(51% were willing to wait up to 2 hours before leaving, 58 (17% would wait 2 to 8 hours, and110 (32% would wait indefinitely. No association was found between willingness to wait and race,gender, insurance status, or perceived symptom severity. Patients willing to wait >2 hours tended to be older than 25, have higher acuity, and prefer the study site ED.Conclusion: Many patients have a defined, limited period that they are willing to wait for emergency care. In our study, 50% of patients were willing to wait up to 2 hours before leaving the ED without being seen. This result suggests that efforts to reduce the percentage of patients who LWBS must factor in time limits.

  11. The transient analysis of the queue-length distribution in the batch arrival system with N-policy, multiple vacations and setup times

    Science.gov (United States)

    Kempa, Wojciech M.

    2010-10-01

    A batch arrival queueing system of the MX/G/1 type with unlimited queue is considered. After each busy period the server begins a multiple vacation period, consisting of independent single vacations, when the service process is blocked. The server begins successive single vacations as far as at the end of one of them the number of customers waiting in the queue equals at least N. The service of the first customer after the vacation period is preceded by a setup time. The analysis of the queue-size distribution on the first vacation cycle is directed to the analysis of the same characteristic in the corresponding "usual" system with unremovable server on its first busy period. The renewal-theory approach is used to obtain results in the general case. As main result the explicit representation for the LT of queue-size distribution is derived for the original system.

  12. Wait too long to talk about kidney disease and you could be waiting for a kidney.

    Science.gov (United States)

    ... Home Current Issue Past Issues Public Service Announcement Kidney Disease Past Issues / Summer 2006 Table of Contents ... Javascript on. Wait too long to talk about kidney disease and you could be waiting for a ...

  13. Distributed digital real-time control system for TCV tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Le, H.B. [École Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association EURATOM-Confédération Suisse, CH-1015 Lausanne (Switzerland); Felici, F. [Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Paley, J.I.; Duval, B.P.; Moret, J.-M.; Coda, S.; Sauter, O.; Fasel, D.; Marmillod, P. [École Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association EURATOM-Confédération Suisse, CH-1015 Lausanne (Switzerland)

    2014-03-15

    Highlights: • A new distributed digital control system for the TCV tokamak has been commissioned. • Data is shared in real-time between all nodes using the reflective memory. • The customised Linux OS allows achieving deterministic and low latency behaviour. • The control algorithm design in Simulink together with the automatic code generation using Embedded Coder allow rapid algorithm development. • Controllers designed outside the TCV environment can be ported easily. • The previous control system functions have been emulated and improved. • New capabilities include MHD control, profile control, equilibrium reconstruction. - Abstract: A new digital feedback control system (named the SCD “Système de Contrôle Distribué”) has been developed, integrated and used successfully to control TCV (Tokamak à Configuration Variable) plasmas. The system is designed to be modular, distributed, and scalable, accommodating hundreds of diagnostic inputs and actuator outputs. With many more inputs and outputs available than previously possible, it offers the possibility to design advanced control algorithms with better knowledge of the plasma state and to coherently control all TCV actuators, including poloidal field (PF) coils, gas valves, the gyrotron powers and launcher angles of the electron cyclotron heating and current drive system (ECRH/ECCD) together with diagnostic triggering signals. The system consists of multiple nodes; each is a customised Linux desktop or embedded PC which may have local ADC and DAC cards. Each node is also connected to a memory network (reflective memory) providing a reliable, deterministic method of sharing memory between all nodes. Control algorithms are programmed as block diagrams in Matlab-Simulink providing a powerful environment for modelling and control design. The C code is generated automatically from the Simulink block diagram and compiled, with the Simulink Embedded Coder (SEC, formerly Real-Time Workshop Embedded

  14. Waiting for the Russians: Coetzee's The Master of Petersburg and ...

    African Journals Online (AJOL)

    A meditation on transition time and on the protracted dimension of waiting for a new world to be born, the novel also presents a model of connectivity between Russia and South Africa. It places post-apartheid culture in a special relationship to postcolonialism and the global configuration born at the end of the Cold War.

  15. Info card for surgery waiting room improves satisfaction.

    Science.gov (United States)

    2015-11-01

    A hospital is reporting improved patient satisfaction from providing an information card in the surgery department. The card includes expected wait times. The card is provided by the patient transport team. Telephone numbers are included for more information. Staff update family members hourly during surgery.

  16. Strategic Attention Deployment for Delay of Gratification in Working and Waiting Situations.

    Science.gov (United States)

    Peake, Philip K.; Hebl, Michelle; Mischel, Walter

    2002-01-01

    Two studies examined whether effects of attention to rewards during a delay of gratification task in waiting situations affects preschoolers' ability to delay gratification in working situations. Findings show that when work provides distraction, attention on rewards reduces delay time whether working or waiting; when work is not engaging,…

  17. How tolerable is delay? : Consumers' evaluations of internet web sites after waiting

    NARCIS (Netherlands)

    B.G.C. Dellaert (Benedict); B.E. Kahn

    1998-01-01

    textabstractHow consumer's waiting times affect their retrospective evaluations of Internet Web Sites is investigated in four computer-based experiments. Results show that waiting can but does not always negatively affect evaluations of Web Sites. Results also show that the potential negative

  18. Spatially Distributed Characterization of Catchment Dynamics Using Travel-Time Distributions

    Science.gov (United States)

    Heße, F.; Zink, M.; Attinger, S.

    2015-12-01

    The description of storage and transport of both water and solved contaminants in catchments is very difficult due to the high heterogeneity of the subsurface properties that govern their fate. This heterogeneity, combined with a generally limited knowledge about the subsurface, results in high degrees of uncertainty. As a result, stochastic methods are increasingly applied, where the relevant processes are modeled as being random. Within these methods, quantities like the catchment travel or residence time of a water parcel are described using probability density functions (PDF). The derivation of these PDF's is typically done by using the water fluxes and states of the catchment. A successful application of such frameworks is therefore contingent on a good quantification of these fluxes and states across the different spatial scales. The objective of this study is to use travel times for the characterization of an ca. 1000 square kilometer, humid catchment in Central Germany. To determine the states and fluxes, we apply the mesoscale Hydrological Model mHM, a spatially distributed hydrological model to the catchment. Using detailed data of precipitation, land cover, morphology and soil type as inputs, mHM is able to determine fluxes like recharge and evapotranspiration and states like soil moisture as outputs. Using these data, we apply the above theoretical framework to our catchment. By virtue of the aforementioned properties of mHM, we are able to describe the storage and release of water with a high spatial resolution. This allows for a comprehensive description of the flow and transport dynamics taking place in the catchment. The spatial distribution of such dynamics is then compared with land cover and soil moisture maps as well as driving forces like precipitation and temperature to determine the most predictive factors. In addition, we investigate how non-local data like the age distribution of discharge flows are impacted by, and therefore allow to infer

  19. Spatially Distributed Characterization of Soil Dynamics Using Travel-Time Distributions

    Science.gov (United States)

    Hesse, Falk; Zink, Matthias; Attinger, Sabine

    2016-04-01

    The description of storage and transport of both water and solved contaminants in catchments is very difficult due to the high heterogeneity of the subsurface properties that govern their fate. This heterogeneity, combined with a generally limited knowledge about the subsurface, results in high degrees of uncertainty. As a result, stochastic methods are increasingly applied, where the relevant processes are modeled as being random. Within these methods, quantities like the catchment travel or residence time of a water parcel are described using probability density functions (PDF). The derivation of these PDF's is typically done by using the water fluxes and states of the catchment. A successful application of such frameworks is therefore contingent on a good quantification of these fluxes and states across the different spatial scales. The objective of this study is to use travel times for the characterization of an ca. 1000 square kilometer, humid catchment in Central Germany. To determine the states and fluxes, we apply the mesoscale Hydrological Model mHM, a spatially distributed hydrological model to the catchment. Using detailed data of precipitation, land cover, morphology and soil type as inputs, mHM is able to determine fluxes like recharge and evapotranspiration and states like soil moisture as outputs. Using these data, we apply the above theoretical framework to our catchment. By virtue of the aforementioned properties of mHM, we are able to describe the storage and release of water with a high spatial resolution. This allows for a comprehensive description of the flow and transport dynamics taking place in the catchment. The spatial distribution of such dynamics is then compared with land cover and soil moisture maps as well as driving forces like precipitation and potential evapotranspiration to determine the most predictive factors. In addition, we investigate how non-local data like the age distribution of discharge flows are impacted by, and

  20. Using probability of drug use as independent variable in a register-based pharmacoepidemiological cause-effect study-An application of the reverse waiting time distribution

    DEFF Research Database (Denmark)

    Hallas, Jesper; Pottegård, Anton; Støvring, Henrik

    2017-01-01

    . Odds ratios (ORs) and 95% confidence intervals for the association between NSAID use and UGIB were calculated by conditional logistic regression, while adjusting for preselected confounders. RESULTS: Compared to the conventional dichotomous exposure measures, the probabilistic exposure measures...

  1. Fatores associados ao tempo de espera e ao acesso ao transplante renal em Belo Horizonte, Minas Gerais, Brasil Factors associated with waiting time and access to kidney transplants in Belo Horizonte, Minas Gerais State, Brazil'

    Directory of Open Access Journals (Sweden)

    Elaine Leandro Machado

    2012-12-01

    Full Text Available O objetivo deste artigo foi analisar os fatores associados ao acesso ao transplante renal com doador vivo e cadáver em Belo Horizonte, Minas Gerais, Brasil. Foi realizado um estudo de coorte não concorrente com pacientes inscritos na lista de espera por transplante renal, entre 2000 e 2004, os quais foram acompanhados até o transplante, óbito, exclusão ou permanência na fila de espera ao fim do estudo em 31 de dezembro de 2005. Utilizou-se o modelo de Cox para riscos competitivos. Dos 835 pacientes, 22,7% foram transplantados. Apresentaram menor risco de transplante por doador cadáver e vivo os pacientes com maior tempo em diálise e tipo sanguíneo O. Observou-se menor risco de transplante intervivos para residentes em uma área de alto risco à saúde e portadores de diabetes. A maior disparidade de acesso foi para transplante renal intervivos, uma vez que não houve diferenças sociodemográficas significativas para transplante por doador cadáver. Pode-se inferir que o sistema de alocação de órgãos contribuiu para amenizar desigualdades sociodemográficas, sendo as questões clínicas mais relevantes no acesso ao transplante com doador cadáver.The objective of this study was to analyze factors associated with access to kidney transplants from living and cadaver donors in Belo Horizonte, Minas Gerais State, Brazil. The authors conducted a non-concurrent cohort study of patients on the waiting list for kidney transplants from 2000 to 2004 and followed until transplantation, death, exclusion, or continued presence on the line at the end of the study on December 31, 2005. The Cox model was used for competing risks. Of the 835 patients, 22.7% were transplanted. Lower risk of transplantation from living donors and cadavers was observed in patients with more time on dialysis and blood type O. Lower risk of transplantation from living donors was observed in residents in a high health risk area and in recipients with diabetes. The

  2. Distributed Velocity-Dependent Protocol for Multihop Cellular Sensor Networks

    Directory of Open Access Journals (Sweden)

    Deepthi Chander

    2009-01-01

    Full Text Available Cell phones are embedded with sensors form a Cellular Sensor Network which can be used to localize a moving event. The inherent mobility of the application and of the cell phone users warrants distributed structure-free data aggregation and on-the-fly routing. We propose a Distributed Velocity-Dependent (DVD protocol to localize a moving event using a Multihop Cellular Sensor Network (MCSN. DVD is based on a novel form of connectivity determined by the waiting time of nodes for a Random Waypoint (RWP distribution of cell phone users. This paper analyzes the time-stationary and spatial distribution of the proposed waiting time to explain the superior event localization and delay performances of DVD over the existing Randomized Waiting (RW protocol. A sensitivity analysis is also performed to compare the performance of DVD with RW and the existing Centralized approach.

  3. Distributed Velocity-Dependent Protocol for Multihop Cellular Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jagyasi Bhushan

    2009-01-01

    Full Text Available Abstract Cell phones are embedded with sensors form a Cellular Sensor Network which can be used to localize a moving event. The inherent mobility of the application and of the cell phone users warrants distributed structure-free data aggregation and on-the-fly routing. We propose a Distributed Velocity-Dependent (DVD protocol to localize a moving event using a Multihop Cellular Sensor Network (MCSN. DVD is based on a novel form of connectivity determined by the waiting time of nodes for a Random Waypoint (RWP distribution of cell phone users. This paper analyzes the time-stationary and spatial distribution of the proposed waiting time to explain the superior event localization and delay performances of DVD over the existing Randomized Waiting (RW protocol. A sensitivity analysis is also performed to compare the performance of DVD with RW and the existing Centralized approach.

  4. Cybersecurity through Real-Time Distributed Control Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kisner, Roger A [ORNL; Manges, Wayne W [ORNL; MacIntyre, Lawrence Paul [ORNL; Nutaro, James J [ORNL; Munro Jr, John K [ORNL; Ewing, Paul D [ORNL; Howlader, Mostofa [ORNL; Kuruganti, Phani Teja [ORNL; Wallace, Richard M [ORNL; Olama, Mohammed M [ORNL

    2010-04-01

    Critical infrastructure sites and facilities are becoming increasingly dependent on interconnected physical and cyber-based real-time distributed control systems (RTDCSs). A mounting cybersecurity threat results from the nature of these ubiquitous and sometimes unrestrained communications interconnections. Much work is under way in numerous organizations to characterize the cyber threat, determine means to minimize risk, and develop mitigation strategies to address potential consequences. While it seems natural that a simple application of cyber-protection methods derived from corporate business information technology (IT) domain would lead to an acceptable solution, the reality is that the characteristics of RTDCSs make many of those methods inadequate and unsatisfactory or even harmful. A solution lies in developing a defense-in-depth approach that ranges from protection at communications interconnect levels ultimately to the control system s functional characteristics that are designed to maintain control in the face of malicious intrusion. This paper summarizes the nature of RTDCSs from a cybersecurity perspec tive and discusses issues, vulnerabilities, candidate mitigation approaches, and metrics.

  5. LPI Radar Waveform Recognition Based on Time-Frequency Distribution

    Directory of Open Access Journals (Sweden)

    Ming Zhang

    2016-10-01

    Full Text Available In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM, BPSK (Barker code modulation, Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4. The classifier is Elman neural network (ENN, and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA, image binarization algorithm and Pseudo–Zernike moments, etc., the features are extracted from the Choi–Williams time-frequency distribution (CWD image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR is 94.7% at signal-to-noise ratio (SNR of −2 dB.

  6. 1 / f β noise for scale-invariant processes: how long you wait matters

    Science.gov (United States)

    Leibovich, Nava; Barkai, Eli

    2017-11-01

    We study the power spectrum which is estimated from a nonstationary signal. In particular we examine the case when the signal is observed in a measurement time window [tw, tw + tm], namely the observation started after a waiting time tw, and tm is the measurement duration. We introduce a generalized aging Wiener-Khinchin theorem which relates between the spectrum and the time- and ensemble-averaged correlation functions for arbitrary tm and tw. Furthermore we provide a general relation between the non-analytical behavior of the scale-invariant correlation function and the aging 1/fβ noise. We illustrate our general results with two-state renewal models with sojourn times' distributions having a broad tail. Contribution to the Topical Issue "Continuous Time Random Walk Still Trendy: Fifty-year History, Current State and Outlook", edited by Ryszard Kutner and Jaume Masoliver.

  7. Estimation Accuracy on Execution Time of Run-Time Tasks in a Heterogeneous Distributed Environment

    Directory of Open Access Journals (Sweden)

    Qi Liu

    2016-08-01

    Full Text Available Distributed Computing has achieved tremendous development since cloud computing was proposed in 2006, and played a vital role promoting rapid growth of data collecting and analysis models, e.g., Internet of things, Cyber-Physical Systems, Big Data Analytics, etc. Hadoop has become a data convergence platform for sensor networks. As one of the core components, MapReduce facilitates allocating, processing and mining of collected large-scale data, where speculative execution strategies help solve straggler problems. However, there is still no efficient solution for accurate estimation on execution time of run-time tasks, which can affect task allocation and distribution in MapReduce. In this paper, task execution data have been collected and employed for the estimation. A two-phase regression (TPR method is proposed to predict the finishing time of each task accurately. Detailed data of each task have drawn interests with detailed analysis report being made. According to the results, the prediction accuracy of concurrent tasks’ execution time can be improved, in particular for some regular jobs.

  8. Estimation Accuracy on Execution Time of Run-Time Tasks in a Heterogeneous Distributed Environment

    Science.gov (United States)

    Liu, Qi; Cai, Weidong; Jin, Dandan; Shen, Jian; Fu, Zhangjie; Liu, Xiaodong; Linge, Nigel

    2016-01-01

    Distributed Computing has achieved tremendous development since cloud computing was proposed in 2006, and played a vital role promoting rapid growth of data collecting and analysis models, e.g., Internet of things, Cyber-Physical Systems, Big Data Analytics, etc. Hadoop has become a data convergence platform for sensor networks. As one of the core components, MapReduce facilitates allocating, processing and mining of collected large-scale data, where speculative execution strategies help solve straggler problems. However, there is still no efficient solution for accurate estimation on execution time of run-time tasks, which can affect task allocation and distribution in MapReduce. In this paper, task execution data have been collected and employed for the estimation. A two-phase regression (TPR) method is proposed to predict the finishing time of each task accurately. Detailed data of each task have drawn interests with detailed analysis report being made. According to the results, the prediction accuracy of concurrent tasks’ execution time can be improved, in particular for some regular jobs. PMID:27589753

  9. Event-Triggered Discrete-Time Distributed Consensus Optimization over Time-Varying Graphs

    Directory of Open Access Journals (Sweden)

    Qingguo Lü

    2017-01-01

    Full Text Available This paper focuses on a class of event-triggered discrete-time distributed consensus optimization algorithms, with a set of agents whose communication topology is depicted by a sequence of time-varying networks. The communication process is steered by independent trigger conditions observed by agents and is decentralized and just rests with each agent’s own state. At each time, each agent only has access to its privately local Lipschitz convex objective function. At the next time step, every agent updates its state by applying its own objective function and the information sent from its neighboring agents. Under the assumption that the network topology is uniformly strongly connected and weight-balanced, the novel event-triggered distributed subgradient algorithm is capable of steering the whole network of agents asymptotically converging to an optimal solution of the convex optimization problem. Finally, a simulation example is given to validate effectiveness of the introduced algorithm and demonstrate feasibility of the theoretical analysis.

  10. Extending the duration of the voluntary waiting period from 60 to 88 days in cows that received timed artificial insemination after the Double-Ovsynch protocol affected the reproductive performance, herd exit dynamics, and lactation performance of dairy cows.

    Science.gov (United States)

    Stangaferro, M L; Wijma, R W; Masello, M; Thomas, Mark J; Giordano, J O

    2017-10-18

    This experiment evaluated the reproductive performance, herd exit dynamics, and lactation performance of dairy cows managed with a voluntary waiting period (VWP) of 60 or 88 d. Secondary objectives were evaluating VWP effect on cyclicity status, uterine health, systemic inflammation, and body condition score (BCS) before first service. Lactating Holstein cows from 3 commercial farms in New York State cows were blocked by parity group and total milk yield in their previous lactation and then randomly assigned to VWP of 60 (VWP60; n = 1,352) or 88 (VWP88; n = 1,359) days in milk (DIM). All cows received the Double-Ovsynch protocol (GnRH-7 d-PGF2α-3 d-GnRH-7 d-GnRH-7 d-PGF2α-56 h-GnRH-16 to 20 h-timed artificial insemination; TAI) for synchronization of ovulation and TAI. For second and greater artificial insemination (AI), cows received AI after detection of estrus or the Ovsynch protocol (GnRH-7 d-PGF2α-56 h-GnRH-16 to 20 h-TAI) initiated 32 ± 3 d after AI for cows not re-inseminated at detected estrus. Cyclicity status (progesterone concentration), uterine health (vaginal discharge and uterine cytology), BCS, and systemic inflammation (haptoglobin concentration) were evaluated at baseline (33 ± 3 DIM for both treatments), beginning of the Double-Ovsynch protocol, and 10 d before TAI. Effects of treatments were assessed with multivariable statistical methods relevant for each outcome variable. Extending duration of VWP from 60 to 88 DIM increased pregnancies per AI (P/AI) to first service (VWP60 = 41%; VWP88 = 47%). Nonetheless, the greatest benefit of extending VWP on first-service P/AI was for primiparous cows (VWP60 = 46%; VWP88 = 55%), as P/AI did not differ within the multiparous cow group (VWP60 = 36%; VWP88 = 40%). Physiological status more conducive to pregnancy-characterized by improved uterine health, greater BCS, reduced systemic inflammation, and to a lesser extent more time to resume ovarian cyclicity-explained the increment in P/AI to first

  11. Time-variant Catchment Transit Time Distribution and StorAge Selection Functions in Neighbouring Catchments

    Science.gov (United States)

    Klaus, J.; Rodriguez, N. B.; McGuire, K. J.

    2016-12-01

    The understanding of the catchment functions of storage, mixing, and release is a major research challenge as their behavior is fundamental for understanding water quality and flow quantity and timing. Generally, the complexity of the flow paths and associated mixing processes is still a major hindrance to a thorough understanding of catchment functions. Catchment transit time distributions can be used as an integrative descriptor of catchment functions. Here we aim to understand these fundamental catchment functions in four neighboring catchments of the HJA Experimental Forest in Oregon, USA. The areas of the four catchments (WS2, WS3, WS9, WS10) range from 0.085 to 1.011 km2. The catchments are fully forested with Douglas fir, western hemlock, and western redcedar dominating the lower elevations, and noble fir, Pacific silver fir, Douglas fir dominating higher elevations. Geology is dominated by volcaniclastics, covering 68% to 99% of the catchments. We employed a two storage conceptual model in each catchment for stream flow and transport modeling. We used solutions of the Master Equation to determine transit time distributions. We assumed randomly sampled/fully mixed conditions in each storage to model 18Oxygen in stream flow over a two year period. For example, modeling results for WS10 yielded a Nash-Sutcliffe efficiency (NSE) of 0.84 for stream flow of and a NSE of 0.7 for the (volume weighted) 18O in stream flow. Furthermore, we derived the master transit time distribution (mttd) for the catchments. Eventually we investigated the landscape controls (topography, geology, morphology) on mttd and the dynamics of storage selection functions of each catchment.

  12. Climatic and landscape controls on travel time distributions across Europe

    Science.gov (United States)

    Kumar, Rohini; Rao, Suresh; Hesse, Falk; Borchardt, Dietrich; Fleckenstein, Jan; Jawitz, James; Musolff, Andreas; Rakovec, Oldrich; Samaniego, Luis; Yang, Soohyun; Zink, Matthias; Attinger, Sabine

    2017-04-01

    Travel time distributions (TTDs) are fundamental descriptors to characterize the functioning of storage, mixing and release of water and solutes in a river basin. Identifying the relative importance (and controls) of climate and landscape attributes on TDDs is fundamental to improve our understanding of the underlying mechanism controlling the spatial heterogeneity of TTDs, and their moments (e.g., mean TT). Studies aimed at elucidating such controls have focused on either theoretical developments to gain (physical) insights using mostly synthetic datasets or empirical relationships using limited datasets from experimental sites. A study painting a general picture of emerging controls at a continental scale is still lacking. In this study, we make use of spatially resolved hydrologic fluxes and states generated through an observationally driven, mesoscale Hydrologic Model (mHM; www.ufz.de/mhm) to comprehensively characterize the dominant controls of climate and landscape attributes on TDDs in the vadose zone across the entire European region. mHM uses a novel Multiscale Parameter Regionalization (MPR; Samaniego et al., 2010 and Kumar et al., 2013) scheme that encapsulates fine scale landscape attributes (e.g., topography, soil, and vegetation characteristics) to account for the sub-grid variability in model parameterization. The model was established at 25 km spatial resolution to simulate the daily gridded fluxes and states over Europe for the period 1955-2015. We utilized recent developments in TTDs theory (e.g., Botter et al., 2010, Harman et al., 2011) to characterize the stationary and non-stationary behavior of water particles transported through the vadose zone at every grid cell. Our results suggest a complex set of interactions between climate and landscape properties controlling the spatial heterogeneity of the mean travel time (TT). The spatial variability in the mean TT across the Pan-EU generally follows the climatic gradient with lower values in humid

  13. Distributed energy resources scheduling considering real-time resources forecast

    DEFF Research Database (Denmark)

    Silva, M.; Sousa, T.; Ramos, S.

    2014-01-01

    Energy resource scheduling is becoming increasingly important, such as the use of more distributed generators and electric vehicles connected to the distribution network. This paper proposes a methodology to be used by Virtual Power Players (VPPs), regarding the energy resource scheduling in smar...

  14. Wave characterization for mammalian cell culture: residence time distribution.

    Science.gov (United States)

    Rodrigues, Maria Elisa; Costa, Ana Rita; Henriques, Mariana; Azeredo, Joana; Oliveira, Rosário

    2012-02-15

    The high dose requirements of biopharmaceutical products led to the development of mammalian cell culture technologies that increase biomanufacturing capacity. The disposable Wave bioreactor is one of the most promising technologies, providing ease of operation and no cross-contamination, and using an innovative undulation movement that ensures good mixing and oxygen transfer without cell damage. However, its recentness demands further characterization. This study evaluated the residence time distribution (RTD) in Wave, allowing the characterization of mixing and flow and the comparison with ideal models and a Stirred tank reactor (STR) used for mammalian cell culture. RTD was determined using methylene blue with pulse input methodology, at three flow rates common in mammalian cell culture (3.3×10(-5)m(3)/h, 7.9×10(-5)m(3)/h, and 1.25×10(-4)m(3)/h) and one typical of microbial culture (5×10(-3)m(3)/h). Samples were taken periodically and the absorbance read at 660nm. It was observed that Wave behavior diverted from ideal models, but was similar to STR. Therefore, the deviations are not related to the particular Wave rocking mechanism, but could be associated with the inadequacy of these reactors to operate in continuous mode or to a possible inability of the theoretical models to properly describe the behavior of reactors designed for mammalian cell culture. Thus, the development of new theoretical models could better characterize the performance of these reactors. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Waiting for care: effects of Ontario's 3-month waiting period for OHIP on landed immigrants.

    Science.gov (United States)

    Goel, Ritika; Bloch, Gary; Caulford, Paul

    2013-06-01

    To describe the experiences of a group of new immigrants and caregivers of new immigrants who were subject to the 3-month waiting period for the Ontario Health Insurance Plan and needed to access health care services during that time. Qualitative study using a phenomenologic framework. Participants were recruited through the Scarborough Community Volunteer Clinic in Toronto, Ont. Interviews were conducted in person at the clinic or by telephone. Seven participants were interviewed who themselves needed to access health care during the 3-month waiting period for the Ontario Health Insurance Plan or who were caring for someone who did. Seven semistructured, in-depth interviews were conducted using an interview guide; these were recorded and transcribed verbatim. Data were analyzed for themes to arrive at the essence of the participants' experiences. Participants believed that there was a lack of clear information and a lack of help from officials. Other common themes included poor social situations, financial loss or threat of financial loss related to health care, a choice to delay seeking care owing to cost, difficulty accessing alternative care, and appreciation for those who advocated on their behalf. Other themes that arose included emotional hardship, poor health outcomes or threat of poor health outcomes resulting from not seeking care, the importance and unpredictability of health, as well as negative impressions of Canada as a country as a result of the negative experience of seeking care. New immigrants to Ontario who need to access health care services during the 3-month waiting period for provincial health insurance and the caregivers of such newcomers can have potentially very negative experiences. They might be unable to access care without financial barriers and might, therefore, choose to delay seeking health care until the end of the waiting period; this can lead to emotional hardship for themselves and their caregivers as well as to potentially poor

  16. Migrating to a real-time distributed parallel simulator architecture- An update

    CSIR Research Space (South Africa)

    Duvenhage, B

    2007-09-01

    Full Text Available A legacy non-distributed logical time simulator was previously migrated to a distributed architecture to parallelise execution. The existing Discrete Time System Specification (DTSS) modelling formalism was retained to simplify the reuse of existing...

  17. Measuring border delay and crossing times at the US-Mexico border : part II. Step-by-step guidelines for implementing a radio frequency identification (RFID) system to measure border crossing and wait times.

    Science.gov (United States)

    2012-06-01

    The purpose of these step-by-step guidelines is to assist in planning, designing, and deploying a system that uses radio frequency identification (RFID) technology to measure the time needed for commercial vehicles to complete the northbound border c...

  18. Distributed Issues for Ada Real-Time Systems

    Science.gov (United States)

    1990-07-23

    distribution of a single Ada program over a network of three Intel 80386 processors connected by an Ethernet. The results of the benchmarks were...Operator Interface (peak data rate of 500Hz) - Using current technology: 32-bit Microprocessors ( 80386 -16MHz) I - Initially a separate program was designated...controlling) CPU and which arc the Slaves. The Master is distinguished from the Slaves in that it is responsible for the distributed system Configuration

  19. Deepwater Horizon - Estimating surface oil volume distribution in real time

    Science.gov (United States)

    Lehr, B.; Simecek-Beatty, D.; Leifer, I.

    2011-12-01

    Spill responders to the Deepwater Horizon (DWH) oil spill required both the relative spatial distribution and total oil volume of the surface oil. The former was needed on a daily basis to plan and direct local surface recovery and treatment operations. The latter was needed less frequently to provide information for strategic response planning. Unfortunately, the standard spill observation methods were inadequate for an oil spill this size, and new, experimental, methods, were not ready to meet the operational demands of near real-time results. Traditional surface oil estimation tools for large spills include satellite-based sensors to define the spatial extent (but not thickness) of the oil, complemented with trained observers in small aircraft, sometimes supplemented by active or passive remote sensing equipment, to determine surface percent coverage of the 'thick' part of the slick, where the vast majority of the surface oil exists. These tools were also applied to DWH in the early days of the spill but the shear size of the spill prevented synoptic information of the surface slick through the use small aircraft. Also, satellite images of the spill, while large in number, varied considerably in image quality, requiring skilled interpretation of them to identify oil and eliminate false positives. Qualified staff to perform this task were soon in short supply. However, large spills are often events that overcome organizational inertia to the use of new technology. Two prime examples in DWH were the application of hyper-spectral scans from a high-altitude aircraft and more traditional fixed-wing aircraft using multi-spectral scans processed by use of a neural network to determine, respectively, absolute or relative oil thickness. But, with new technology, come new challenges. The hyper-spectral instrument required special viewing conditions that were not present on a daily basis and analysis infrastructure to process the data that was not available at the command

  20. Tunneling time distribution by means of Nelson's quantum ...

    Indian Academy of Sciences (India)

    It was suggested that there is a time associated with the passage of a particle under a tunneling barrier, the so-called tunneling time [1]. The existence of such a time is now accepted. In fact, the time has been measured experimentally. However, there is no clear consensus about the existence of a simple expression for this ...

  1. Effect of organic manure application on yield distribution over time ...

    African Journals Online (AJOL)

    Temporal distribution of yield over harvests and yield in various truss positions on the main stem in three West African eggplants were studied in the field under five poultry manure rates. Fruit yields were spread over 12-15 weeks, unless where the life of the crop was cut short due to insect pest or disease attack. Two peaks ...

  2. Marketing and Distribution: Entrepreneurship Education--The Time Has Come.

    Science.gov (United States)

    Furtado, Lorraine T.; Haines, Peter G.

    1980-01-01

    It is important that the concept of entrepreneurship be infused into business and distributive education instructional programs. The authors discuss why there is a special need for this type of program, the idea of small business, what an entrepreneur is, the concept of profit, and the availability of instructional materials. (CT)

  3. Sharing Real-Time Objects in Distributed Embedded Systems

    DEFF Research Database (Denmark)

    Larsen, Erland Ketil; Havn, Ib

    2015-01-01

    microcontrollers connected by a RS-485 bus. The demo system shows that it is relatively simple to implement a distributed embedded system with the provided API, and the latency of the communication service is predictable. A low coupling to hardware makes it easy to port to another platform and/or another network...

  4. Catchment residence and travel time distributions: The master equation

    National Research Council Canada - National Science Library

    Gianluca Botter; Enrico Bertuzzo; Andrea Rinaldo

    2011-01-01

      Travel/residence time pdf's are related objects with different physical meaning A Master Equation for the residence time pdf is derived and solved analytically We develop a mathematical framework...

  5. Real-time Distributed Economic Dispatch forDistributed Generation Based on Multi-Agent System

    DEFF Research Database (Denmark)

    Luo, Kui; Wu, Qiuwei; Nielsen, Arne Hejde

    2015-01-01

    The distributed economic dispatch for distributed generation is formulated as a optimization problem with equality and inequality constraints. An effective distributed approach based on multi-agent system is proposed for solving the economic dispatch problem in this paper. The proposed approach...... consists of two stages. In the first stage, an adjacency average allocation algorithm is proposed to ensure the generation-demand equality. In the second stage, a local replicator dynamics algorithm is applied to achieve nash equilibrium for the power dispatch game. The approach is implemented in a fully...

  6. Real Time Emulation of Dynamic Tariff for Congestion Management in Distribution Networks

    DEFF Research Database (Denmark)

    Rasmussen, Theis Bo; Wu, Qiuwei; Huang, Shaojun

    2016-01-01

    This paper presents the real time evaluation of the dynamic tariff (DT) method for alleviating congestion in a distribution networks with high penetration of distributed energy resources (DERs). The DT method is implemented in a real time digital testing platform that emulates a real distribution...

  7. 7 CFR 1435.504 - Timing of distribution of CCC-owned sugar.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Timing of distribution of CCC-owned sugar. 1435.504... CORPORATION, DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS SUGAR PROGRAM Processor Sugar Payment-In-Kind (PIK) Program § 1435.504 Timing of distribution of CCC-owned sugar. Distribution of sugar...

  8. RESIDENCE TIME DISTRIBUTION OF FLUIDS IN STIRRED ANNULAR PHOTOREACTORS

    Science.gov (United States)

    When gases flow through an annular photoreactor at constant rate, some of the gas spends more or less than the average residence time in the reactor. This spread of residence time can have an important effect on the performance of the reactor. this study tested how the residence...

  9. Towards a Notion of Distributed Time for Petri Nets

    DEFF Research Database (Denmark)

    Nielsen, Mogens; Sassone, Vladimiro; Srba, Jiří

    2001-01-01

    We set the ground for research on a timed extension of Petri nets where time parameters are associated with tokens and arcs carry constraints that qualify the age of tokens required for enabling. The novelty is that, rather than a single global clock, we use a set of unrelated clocks — possibly one...

  10. Storm blueprints patterns for distributed real-time computation

    CERN Document Server

    Goetz, P Taylor

    2014-01-01

    A blueprints book with 10 different projects built in 10 different chapters which demonstrate the various use cases of storm for both beginner and intermediate users, grounded in real-world example applications.Although the book focuses primarily on Java development with Storm, the patterns are more broadly applicable and the tips, techniques, and approaches described in the book apply to architects, developers, and operations.Additionally, the book should provoke and inspire applications of distributed computing to other industries and domains. Hadoop enthusiasts will also find this book a go

  11. Comprehensive Cost Minimization in Distribution Networks Using Segmented-time Feeder Reconfiguration and Reactive Power Control of Distributed Generators

    DEFF Research Database (Denmark)

    Chen, Shuheng; Hu, Weihao; Chen, Zhe

    2016-01-01

    In this paper, an efficient methodology is proposed to deal with segmented-time reconfiguration problem of distribution networks coupled with segmented-time reactive power control of distributed generators. The target is to find the optimal dispatching schedule of all controllable switches...... and distributed generators’ reactive powers in order to minimize comprehensive cost. Corresponding constraints, including voltage profile, maximum allowable daily switching operation numbers (MADSON), reactive power limits, and so on, are considered. The strategy of grouping branches is used to simplify...... (FAHPSO) is implemented in VC++ 6.0 program language. A modified version of the typical 70-node distribution network and several real distribution networks are used to test the performance of the proposed method. Numerical results show that the proposed methodology is an efficient method for comprehensive...

  12. Heterogeneous Data Fusion Method to Estimate Travel Time Distributions in Congested Road Networks.

    Science.gov (United States)

    Shi, Chaoyang; Chen, Bi Yu; Lam, William H K; Li, Qingquan

    2017-12-06

    Travel times in congested urban road networks are highly stochastic. Provision of travel time distribution information, including both mean and variance, can be very useful for travelers to make reliable path choice decisions to ensure higher probability of on-time arrival. To this end, a heterogeneous data fusion method is proposed to estimate travel time distributions by fusing heterogeneous data from point and interval detectors. In the proposed method, link travel time distributions are first estimated from point detector observations. The travel time distributions of links without point detectors are imputed based on their spatial correlations with links that have point detectors. The estimated link travel time distributions are then fused with path travel time distributions obtained from the interval detectors using Dempster-Shafer evidence theory. Based on fused path travel time distribution, an optimization technique is further introduced to update link travel time distributions and their spatial correlations. A case study was performed using real-world data from Hong Kong and showed that the proposed method obtained accurate and robust estimations of link and path travel time distributions in congested road networks.

  13. Timing and Spatial Distribution of Loess in Xinjiang, NW China.

    Science.gov (United States)

    Li, Yun; Song, Yougui; Yan, Libin; Chen, Tao; An, Zhisheng

    2015-01-01

    Central Asia is one of the most significant loess regions on Earth, with an important role in understanding Quaternary climate and environmental change. However, in contrast to the widely investigated loess deposits in the Chinese Loess Plateau, the Central Asian loess-paleosol sequences are still insufficiently known and poorly understood. Through field investigation and review of the previous literature, the authors have investigated the distribution, thickness and age of the Xinjiang loess, and analyzed factors that control these parameters in the Xinjiang in northwest China, Central Asia. The loess sediments cover river terraces, low uplands, the margins of deserts and the slopes of the Tianshan Mountains and Kunlun Mountains and are also present in the Ili Basin. The thickness of the Xinjiang loess deposits varies from several meters to 670 m. The variation trend of the sand fraction (>63 μm) grain-size contour can indicate the local major wind directions, so we conclude that the NW and NE winds are the main wind directions in the North and South Xinjiang, and the westerly wind mainly transport dust into the Ili basin. We consider persistent drying, adequate regional wind energy and well-developed river terraces to be the main factors controlling the distribution, thickness and formation age of the Xinjiang loess. The well-outcropped loess sections have mainly developed since the middle Pleistocene in Xinjiang, reflecting the appearance of the persistent drying and the present air circulation system. However, the oldest loess deposits are as old as the beginning of the Pliocene in the Tarim Basin, which suggests that earlier aridification occurred in the Tarim Basin rather than in the Ili Basin and the Junggar Basin.

  14. Timing and Spatial Distribution of Loess in Xinjiang, NW China.

    Directory of Open Access Journals (Sweden)

    Yun Li

    Full Text Available Central Asia is one of the most significant loess regions on Earth, with an important role in understanding Quaternary climate and environmental change. However, in contrast to the widely investigated loess deposits in the Chinese Loess Plateau, the Central Asian loess-paleosol sequences are still insufficiently known and poorly understood. Through field investigation and review of the previous literature, the authors have investigated the distribution, thickness and age of the Xinjiang loess, and analyzed factors that control these parameters in the Xinjiang in northwest China, Central Asia. The loess sediments cover river terraces, low uplands, the margins of deserts and the slopes of the Tianshan Mountains and Kunlun Mountains and are also present in the Ili Basin. The thickness of the Xinjiang loess deposits varies from several meters to 670 m. The variation trend of the sand fraction (>63 μm grain-size contour can indicate the local major wind directions, so we conclude that the NW and NE winds are the main wind directions in the North and South Xinjiang, and the westerly wind mainly transport dust into the Ili basin. We consider persistent drying, adequate regional wind energy and well-developed river terraces to be the main factors controlling the distribution, thickness and formation age of the Xinjiang loess. The well-outcropped loess sections have mainly developed since the middle Pleistocene in Xinjiang, reflecting the appearance of the persistent drying and the present air circulation system. However, the oldest loess deposits are as old as the beginning of the Pliocene in the Tarim Basin, which suggests that earlier aridification occurred in the Tarim Basin rather than in the Ili Basin and the Junggar Basin.

  15. Poverty index with time-varying consumption and income distributions

    Science.gov (United States)

    Chattopadhyay, Amit K.; Kumar, T. Krishna; Mallick, Sushanta K.

    2017-03-01

    Starting from a stochastic agent-based model to represent market exchange in a developing economy, we study time variations of the probability density function of income with simultaneous variation of the consumption deprivation (CD), where CD represents the shortfall in consumption from the saturation level of an essential commodity, cereal. Together, these two models combine income-expenditure-based market dynamics with time variations in consumption due to income. In this new unified theoretical structure, exchange of trade in assets is only allowed when the income exceeds consumption-deprivation while CD itself is endogenously obtained from a separate kinetic model. Our results reveal that the nature of time variation of the CD function leads to a downward trend in the threshold level of consumption of basic necessities, suggesting a possible dietary transition in terms of lower saturation level of food-grain consumption, possibly through an improvement in the level of living. The new poverty index, defined as CD, is amenable to approximate probabilistic prediction within a short time horizon. A major achievement of this work is the intrinsic independence of the poverty index from an exogenous poverty line, making it more objective for policy formulation as opposed to existing poverty indices in the literature.

  16. Representing real time semantics for distributed application integration

    NARCIS (Netherlands)

    Poon, P.M.S.; Dillon, T.S.; Chang, E.; Feng, L.

    Traditional real time system design and development are driven by technological requirements. With the ever growing complexity of requirements and the advances in software design, the alignment of focus has gradually been shifted to the perspective of business and industrial needs. This paper

  17. 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

  18. A distributed real-time Java system based on CSP

    NARCIS (Netherlands)

    Bakkers, André; Hilderink, G.H.; Broenink, Johannes F.

    1999-01-01

    Real-time embedded systems in general require a reliability that is orders of magnitude higher than what is presently obtainable with state of the art C programs. The reason for the poor reliability of present day software is the unavailability of a formalism to design sequential C programs. The use

  19. Scheduling and Communication Synthesis for Distributed Real-Time Systems

    DEFF Research Database (Denmark)

    Pop, Paul

    2000-01-01

    proposed a less pessimistic schedulability analysis that is able to handle both control and data dependencies. Moreover, we have provided a schedulability analysis for the time-triggered protocol, and we have proposed several optimization strategies for the synthesis of communication protocol parameters...

  20. Design Methodology for Real-Time Distributed Systems.

    Science.gov (United States)

    1983-12-01

    a methodology for the design of complex real-time digital systems. These systems are dedicated to a single objective, such as flight -guidace...evelp etopent ertan s~etected acquizition pLog’%w in .6uppo’tt o6 Command, ContLot Cornmuncaton, and In-tetJigence (C31) activitieA. Technc.. .and

  1. Fission Fragment Angular Distributions measured with a Time Projection Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Kleinrath, Verena [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-28

    The subject is presented in a series of slides with the following organization: Introduction (What is anisotropy? Relevance (Theory and ratio cross section), Previous measurements); Experiment (Particle tracking in the fissionTPC, Neutron time of flight, Data analysis & uncertainty calculation, Preliminary result for 235U); and Future Work (Refine 235U result, Process 239Pu data).

  2. Time for sex: nycthemeral distribution of human sexual behavior

    Directory of Open Access Journals (Sweden)

    Refinetti Roberto

    2005-03-01

    Full Text Available Abstract Background Nycthemeral (daily oscillation has been documented in a variety of physiological and behavioral processes. The present study was carried out to evaluate the existence of a nycthemeral rhythm of human sexual behavior and to identify environmental factors responsible for the rhythmic pattern. Methods Non-traditional university students (ages 18 to 51 years recorded the times of day when they went to sleep, when they woke up, and when they had sex for 3 consecutive weeks. They also answered a questionnaire designed to identify the causes of their selection of time for sex. Results The majority of sexual encounters took place at bedtime (11 pm to 1 am. The most common explanations for this temporal pattern were the rigidity of the professional work schedule and family obligations and the availability of the partner, which reduced the opportunity for sexual encounters at other times of the day. Conclusion Most sexual encounters take place around bedtime. Although the presence of an endogenous component responsible for this temporal pattern cannot be excluded, the evidence indicates strong environmental forcing, particularly from the work/family schedule of the individuals and from partner availability.

  3. The MX/G/1 queue with queue length dependent service times

    Directory of Open Access Journals (Sweden)

    Bong Dae Choi

    2001-01-01

    Full Text Available We deal with the MX/G/1 queue where service times depend on the queue length at the service initiation. By using Markov renewal theory, we derive the queue length distribution at departure epochs. We also obtain the transient queue length distribution at time t and its limiting distribution and the virtual waiting time distribution. The numerical results for transient mean queue length and queue length distributions are given.

  4. Lower bounds on the run time of the univariate marginal distribution algorithm on OneMax

    DEFF Research Database (Denmark)

    Krejca, Martin S.; Witt, Carsten

    2017-01-01

    The Univariate Marginal Distribution Algorithm (UMDA), a popular estimation of distribution algorithm, is studied from a run time perspective. On the classical OneMax benchmark function, a lower bound of Ω(μ√n + n log n), where μ is the population size, on its expected run time is proved. This is......The Univariate Marginal Distribution Algorithm (UMDA), a popular estimation of distribution algorithm, is studied from a run time perspective. On the classical OneMax benchmark function, a lower bound of Ω(μ√n + n log n), where μ is the population size, on its expected run time is proved...

  5. RTD (residence time distribution) predictions in large mechanically aerated lagoons.

    Science.gov (United States)

    Stropky, D; Pougatch, K; Nowak, P; Salcudean, M; Pagori, P; Gartshore, I; Yuan, J

    2007-01-01

    Mechanically aerated lagoons (used for wastewater treatment in the pulp and paper industry) are typically very large (>500,000 m3) and have complex three-dimensional fluid flow patterns due to mechanical agitation, sludge accumulation, internal baffling, and confined inlet/outlet flow channels. RTD data is frequently used for evaluation of hydraulic performance, however, obtaining accurate data with traditional dye measurements is a difficult and time-consuming process. Moreover, the mixing impact of factors such as aerator positions, sludge accumulation, and internal baffles would require a significant and costly number of local field measurements. Recent applications of CFD to mechanically aerated lagoons have helped engineers to understand the complex flow interactions. This paper provides a practical method for the evaluation of the hydraulic performance of large mechanically aerated lagoons using CFD. A method, based on random-walk Lagrangian particle tracking, has been developed to significantly shorten the computational time needed to produce RTD curves for these lagoons. Comparison of the particle method with the more conventional scalar transport yields excellent results. These methods allow wastewater engineers to combine their existing knowledge and expertise with the established power of CFD. The results quantify the hydraulic impact of different inlet/outlet configurations, aerator configurations, influent flow rates, and bottom sludge profiles.

  6. Controlled, distributed data management of an Antarctic time series

    Science.gov (United States)

    Leadbetter, Adam; Connor, David; Cunningham, Nathan; Reynolds, Sarah

    2010-05-01

    The Rothera Time Series (RaTS) presents over ten years of oceanographic data collected off the Antarctic Peninsula comprising conductivity, temperature, depth cast data; current meter data; and bottle sample data. The data set has been extensively analysed and is well represented in the scientific literature. However, it has never been available to browse as a coherent entity. Work has been undertaken by both the data collecting organisation (the British Antarctic Survey, BAS) and the associated national data centre (the British Oceanographic Data Centre, BODC) to describe the parameters comprising the dataset in a consistent manner. To this end, each data point in the RaTS dataset has now been ascribed a parameter usage term, selected from the appropriate controlled vocabulary of the Natural Environment Research Council's Data Grid (NDG). By marking up the dataset in this way the semantic richness of the NDG vocabularies is fully accessible, and the dataset can be then explored using the Global Change Master Directory keyword set, the International Standards Organisation topic categories, SeaDataNet disciplines and agreed parameter groups, and the NDG parameter discovery vocabulary. We present a single data discovery and exploration tool, a web portal which allows the user to drill down through the dataset using their chosen keyword set. The spatial coverage of the chosen data is displayed through a Google Earth web plugin. Finally, as the time series data are held at BODC and the discrete sample data held at BAS (which are separate physical locations), a mechanism has been established to provide metadata from one site to another. This takes the form of an Open Geospatial Consortium Web Map Service server at BODC feeding information into the portal hosted at BAS.

  7. Scaling laws of ambush predator 'waiting' behaviour are tuned to a common ecology.

    Science.gov (United States)

    Wearmouth, Victoria J; McHugh, Matthew J; Humphries, Nicolas E; Naegelen, Aurore; Ahmed, Mohammed Z; Southall, Emily J; Reynolds, Andrew M; Sims, David W

    2014-05-07

    The decisions animals make about how long to wait between activities can determine the success of diverse behaviours such as foraging, group formation or risk avoidance. Remarkably, for diverse animal species, including humans, spontaneous patterns of waiting times show random 'burstiness' that appears scale-invariant across a broad set of scales. However, a general theory linking this phenomenon across the animal kingdom currently lacks an ecological basis. Here, we demonstrate from tracking the activities of 15 sympatric predator species (cephalopods, sharks, skates and teleosts) under natural and controlled conditions that bursty waiting times are an intrinsic spontaneous behaviour well approximated by heavy-tailed (power-law) models over data ranges up to four orders of magnitude. Scaling exponents quantifying ratios of frequent short to rare very long waits are species-specific, being determined by traits such as foraging mode (active versus ambush predation), body size and prey preference. A stochastic-deterministic decision model reproduced the empirical waiting time scaling and species-specific exponents, indicating that apparently complex scaling can emerge from simple decisions. Results indicate temporal power-law scaling is a behavioural 'rule of thumb' that is tuned to species' ecological traits, implying a common pattern may have naturally evolved that optimizes move-wait decisions in less predictable natural environments.

  8. Estimation of Bimodal Urban Link Travel Time Distribution and Its Applications in Traffic Analysis

    Directory of Open Access Journals (Sweden)

    Yuxiong Ji

    2015-01-01

    Full Text Available Vehicles travelling on urban streets are heavily influenced by traffic signal controls, pedestrian crossings, and conflicting traffic from cross streets, which would result in bimodal travel time distributions, with one mode corresponding to travels without delays and the other travels with delays. A hierarchical Bayesian bimodal travel time model is proposed to capture the interrupted nature of urban traffic flows. The travel time distributions obtained from the proposed model are then considered to analyze traffic operations and estimate travel time distribution in real time. The advantage of the proposed bimodal model is demonstrated using empirical data, and the results are encouraging.

  9. Time-Frequency Distribution of Music based on Sparse Wavelet Packet Representations

    DEFF Research Database (Denmark)

    Endelt, Line Ørtoft

    the minimization methods basis pursuit and best orthogonal basis. Visualizations of the time-frequency distribution are constructed based on a simplified energy distribution in the wavelet packet decomposition. The time-frequency distributions emphasizes structured musical content, including non-stationary content......, by masking the energy from less structured music instruments. We present four examples for visualizing structured content, including vocal and single instrument.......We introduce a new method for generating time-frequency distributions, which is particularly useful for the analysis of music signals. The method presented here is based on $\\ell1$ sparse representations of music signals in a redundant wavelet packet dictionary. The representations are found using...

  10. Seismic random noise attenuation by time-frequency peak filtering based on joint time-frequency distribution

    Science.gov (United States)

    Zhang, Chao; Lin, Hong-bo; Li, Yue; Yang, Bao-jun

    2013-09-01

    Time-Frequency Peak Filtering (TFPF) is an effective method to eliminate pervasive random noise when seismic signals are analyzed. In conventional TFPF, the pseudo Wigner-Ville distribution (PWVD) is used for estimating instantaneous frequency (IF), but is sensitive to noise interferences that mask the borderline between signal and noise and detract the energy concentration on the IF curve. This leads to the deviation of the peaks of the pseudo Wigner-Ville distribution from the instantaneous frequency, which is the cause of undesirable lateral oscillations as well as of amplitude attenuation of the highly varying seismic signal, and ultimately of the biased seismic signal. With the purpose to overcome greatly these drawbacks and increase the signal-to-noise ratio, we propose in this paper a TFPF refinement that is based upon the joint time-frequency distribution (JTFD). The joint time-frequency distribution is obtained by the combination of the PWVD and smooth PWVD (SPWVD). First we use SPWVD to generate a broad time-frequency area of the signal. Then this area is filtered with a step function to remove some divergent time-frequency points. Finally, the joint time-frequency distribution JTFD is obtained from PWVD weighted by this filtered distribution. The objective pursued with all these operations is to reduce the effects of the interferences and enhance the energy concentration around the IF of the signal in the time-frequency domain. Experiments with synthetic and real seismic data demonstrate that TFPF based on the joint time-frequency distribution can effectively suppress strong random noise and preserve events of interest.

  11. Cost benefits of postponing time-based maintenance under lifetime distribution uncertainty

    NARCIS (Netherlands)

    de Jonge, Bram; Dijkstra, Arjan; Romeijnders, Ward

    We consider the problem of scheduling time-based preventive maintenance under uncertainty in the lifetime distribution of a unit, with the understanding that every time a maintenance action is carried out, additional information on the lifetime distribution becomes available. Under such

  12. Consumer behaviour in the waiting area

    NARCIS (Netherlands)

    Mobach, M.P.

    Objective of the study: To determine consumer behaviour in the pharmacy waiting area. Method: The applied methods for data-collection were direct observations. Three Dutch community pharmacies were selected for the study. The topics in the observation list were based on available services at each

  13. An approach to the residence time distribution for stochastic multi-compartment models.

    Science.gov (United States)

    Yu, Jihnhee; Wehrly, Thomas E

    2004-10-01

    Stochastic compartmental models are widely used in modeling processes such as drug kinetics in biological systems. This paper considers the distribution of the residence times for stochastic multi-compartment models, especially systems with non-exponential lifetime distributions. The paper first derives the moment generating function of the bivariate residence time distribution for the two-compartment model with general lifetimes and approximates the density of the residence time using the saddlepoint approximation. Then, it extends the distributional approach to the residence time for multi-compartment semi-Markov models combining the cofactor rule for a single destination and the analytic approach to the two-compartment model. This approach provides a complete specification of the residence time distribution based on the moment generating function and thus facilitates an easier calculation of high-order moments than the approach using the coefficient matrix. Applications to drug kinetics demonstrate the simplicity and usefulness of this approach.

  14. Radar signal analysis of ballistic missile with micro-motion based on time-frequency distribution

    Science.gov (United States)

    Wang, Jianming; Liu, Lihua; Yu, Hua

    2015-12-01

    The micro-motion of ballistic missile targets induces micro-Doppler modulation on the radar return signal, which is a unique feature for the warhead discrimination during flight. In order to extract the micro-Doppler feature of ballistic missile targets, time-frequency analysis is employed to process the micro-Doppler modulated time-varying radar signal. The images of time-frequency distribution (TFD) reveal the micro-Doppler modulation characteristic very well. However, there are many existing time-frequency analysis methods to generate the time-frequency distribution images, including the short-time Fourier transform (STFT), Wigner distribution (WD) and Cohen class distribution, etc. Under the background of ballistic missile defence, the paper aims at working out an effective time-frequency analysis method for ballistic missile warhead discrimination from the decoys.

  15. Estimating medication stopping fraction and real-time prevalence of drug use in pharmaco-epidemiologic databases

    DEFF Research Database (Denmark)

    Støvring, Henrik; Pottegård, Anton; Hallas, Jesper

    2017-01-01

    Purpose: To introduce the reverse waiting time distribution (WTD) and show how it can be used to estimate stopping fractions and real-time prevalence of treatment in pharmacoepidemiological studies. Methods: The reverse WTD is the distribution of time from the last dispensed prescription of each ...

  16. Not all waits are equal: an exploratory investigation of emergency care patient pathways.

    Science.gov (United States)

    Swancutt, Dawn; Joel-Edgar, Sian; Allen, Michael; Thomas, Daniel; Brant, Heather; Benger, Jonathan; Byng, Richard; Pinkney, Jonathan

    2017-06-24

    Increasing pressure in the United Kingdom (UK) urgent care system has led to Emergency Departments (EDs) failing to meet the national requirement that 95% of patients are admitted, discharged or transferred within 4-h of arrival. Despite the target being the same for all acute hospitals, individual Trusts organise their services in different ways. The impact of this variation on patient journey time and waiting is unknown. Our study aimed to apply the Lean technique of Value Stream Mapping (VSM) to investigate care processes and delays in patient journeys at four contrasting hospitals. VSM timing data were collected for patients accessing acute care at four hospitals in South West England. Data were categorised according to waits and activities, which were compared across sites to identify variations in practice from the patient viewpoint. We included Public and Patient Involvement (PPI) to fully interpret our findings; observations and initial findings were considered in a PPI workshop. One hundred eight patients were recruited, comprising 25,432 min of patient time containing 4098 episodes of care or waiting. The median patient journey was 223 min (3 h, 43 min); just within the 4-h target. Although total patient journey times were similar between sites, the stage where the greatest proportion of waiting occurred varied. Reasons for waiting were dominated by waits for beds, investigations or results to be available. From our sample we observed that EDs without a discharge/clinical decision area exhibited a greater proportion of waiting time following an admission or discharge decision. PPI interpretation indicated that patients who experience waits at the beginning of their journey feel more anxious because they are 'not in the system yet'. The novel application of VSM analysis across different hospitals, coupled with PPI interpretation, provides important insight into the impact of care provision on patient experience. Measures that could reduce patient

  17. Optimal methods for fitting probability distributions to propagule retention time in studies of zoochorous dispersal.

    Science.gov (United States)

    Viana, Duarte S; Santamaría, Luis; Figuerola, Jordi

    2016-02-01

    Propagule retention time is a key factor in determining propagule dispersal distance and the shape of "seed shadows". Propagules dispersed by animal vectors are either ingested and retained in the gut until defecation or attached externally to the body until detachment. Retention time is a continuous variable, but it is commonly measured at discrete time points, according to pre-established sampling time-intervals. Although parametric continuous distributions have been widely fitted to these interval-censored data, the performance of different fitting methods has not been evaluated. To investigate the performance of five different fitting methods, we fitted parametric probability distributions to typical discretized retention-time data with known distribution using as data-points either the lower, mid or upper bounds of sampling intervals, as well as the cumulative distribution of observed values (using either maximum likelihood or non-linear least squares for parameter estimation); then compared the estimated and original distributions to assess the accuracy of each method. We also assessed the robustness of these methods to variations in the sampling procedure (sample size and length of sampling time-intervals). Fittings to the cumulative distribution performed better for all types of parametric distributions (lognormal, gamma and Weibull distributions) and were more robust to variations in sample size and sampling time-intervals. These estimated distributions had negligible deviations of up to 0.045 in cumulative probability of retention times (according to the Kolmogorov-Smirnov statistic) in relation to original distributions from which propagule retention time was simulated, supporting the overall accuracy of this fitting method. In contrast, fitting the sampling-interval bounds resulted in greater deviations that ranged from 0.058 to 0.273 in cumulative probability of retention times, which may introduce considerable biases in parameter estimates. We

  18. Delay-time distribution in the scattering of time-narrow wave packets (II)—quantum graphs

    Science.gov (United States)

    Smilansky, Uzy; Schanz, Holger

    2018-02-01

    We apply the framework developed in the preceding paper in this series (Smilansky 2017 J. Phys. A: Math. Theor. 50 215301) to compute the time-delay distribution in the scattering of ultra short radio frequency pulses on complex networks of transmission lines which are modeled by metric (quantum) graphs. We consider wave packets which are centered at high wave number and comprise many energy levels. In the limit of pulses of very short duration we compute upper and lower bounds to the actual time-delay distribution of the radiation emerging from the network using a simplified problem where time is replaced by the discrete count of vertex-scattering events. The classical limit of the time-delay distribution is also discussed and we show that for finite networks it decays exponentially, with a decay constant which depends on the graph connectivity and the distribution of its edge lengths. We illustrate and apply our theory to a simple model graph where an algebraic decay of the quantum time-delay distribution is established.

  19. A Time Delay Estimation Method Based on Wavelet Transform and Speech Envelope for Distributed Microphone Arrays

    Directory of Open Access Journals (Sweden)

    YIN, F.

    2013-08-01

    Full Text Available A time delay estimation method based on wavelet transform and speech envelope is proposed for distributed microphone arrays. This method first extracts the speech envelopes of the signals processed with multi-level discrete wavelet transform, and then makes use of the speech envelopes to estimate a coarse time delay. Finally it searches for the accurate time delay near the coarse time delay by the cross-correlation function calculated in time domain. The simulation results illustrate that the proposed method can accurately estimate the time delay between two distributed microphone array signals.

  20. Teaching Evaluation: Waiting for Initiatives

    Directory of Open Access Journals (Sweden)

    Alejandro Canales Sánchez

    2008-08-01

    Full Text Available In this text, it is sustained that, despite the fact that the teaching activity is one of the main functions of higher education institutions or even the only one in most of them, it hasn’t been reflected in the leading initiatives that have been set in motion in this area for the last two decades. In particular, it points out that the wide evaluation politics established in the education system during the late eighties, didn’t consider the teaching activity as a concern issue for the mechanisms or rewards in the evaluation system. Even though the implementation of new actions tried to repair the situation, mainly by improving the quality of working time and the qualifications of the personnel performing these activities; teaching, in strict sense, and the design or application of a new evaluation scheme to strengthen it, didn’t get better.

  1. Effect of an audiovisual message for tetanus booster vaccination broadcast in the waiting room.

    Science.gov (United States)

    Eubelen, Caroline; Brendel, Fannette; Belche, Jean-Luc; Freyens, Anne; Vanbelle, Sophie; Giet, Didier

    2011-09-28

    General practitioners (GPs) often lack time and resources to invest in health education; audiovisual messages broadcast in the waiting room may be a useful educational tool. This work was designed to assess the effect of a message inviting patients to ask for a tetanus booster vaccination. A quasi experimental study was conducted in a Belgian medical practice consisting of 6 GPs and 4 waiting rooms (total: 20,000 contacts/year). A tetanus booster vaccination audiovisual message was continuously broadcast for 6 months in 2 randomly selected waiting rooms (intervention group--3 GPs) while the other 2 waiting rooms remained unequipped (control group--3 GPs). At the end of the 6-month period, the number of vaccine adult-doses delivered by local pharmacies in response to GPs' prescriptions was recorded. As a reference, the same data were also collected retrospectively for the general practice during the same 6-month period of the previous year. During the 6-month reference period where no audiovisual message was broadcast in the 4 waiting rooms, the number of prescriptions presented for tetanus vaccines was respectively 52 (0.44%) in the intervention group and 33 (0.38%) in the control group (p = 0.50). By contrast, during the 6-month study period, the number of prescriptions differed between the two groups (p Broadcasting an audiovisual health education message in the GPs' waiting room was associated with a significant increase in the number of adult tetanus booster vaccination prescriptions delivered by local pharmacies.

  2. VHA Support Service Center Electronic Wait List (EWL)

    Data.gov (United States)

    Department of Veterans Affairs — The goal of the Electronic Wait List (EWL) is to provide care to the patient as quickly as possible. To facilitate this goal, patients may be placed on a Wait List...

  3. Damage Detection Based on Cross-Term Extraction from Bilinear Time-Frequency Distributions

    Directory of Open Access Journals (Sweden)

    Ma Yuchao

    2014-01-01

    Full Text Available Abundant damage information is implicated in the bilinear time-frequency distribution of structural dynamic signals, which could provide effective support for structural damage identification. Signal time-frequency analysis methods are reviewed, and the characters of linear time-frequency distribution and bilinear time-frequency distribution typically represented by the Wigner-Ville distribution are compared. The existence of the cross-term and its application in structural damage detection are demonstrated. A method of extracting the dominant term is proposed, which combines the short-time Fourier spectrum and Wigner-Ville distribution; then two-dimensional time-frequency transformation matrix is constructed and the complete cross-term is extracted finally. The distribution character of which could be applied to the structural damage identification. Through theoretical analysis, model experiment and numerical simulation of the girder structure, the change rate of cross-term amplitude is validated to identify the damage location and degree. The effectiveness of the cross-term of bilinear time-frequency distribution for damage detection is confirmed and the analytical method of damage identification used in structural engineering is available.

  4. Timing System Solution for MedAustron; Real-time Event and Data Distribution Network

    CERN Document Server

    Štefanič, R; Dedič, J; Gutleber, J; Moser, R

    2011-01-01

    MedAustron is an ion beam research and therapy centre under construction in Wiener Neustadt, Austria. The facility features a synchrotron particle accelerator for light ions. The timing system for this class of accelerators has been developed in close collaboration between MedAustron and Cosylab. Mitigating economical and technological risks, we have chosen a proven, widely used Micro Research Finland (MRF) timing equipment and redesigned its FPGA firmware, extending its high-logic services above transport layer, as required by machine specifics. We obtained a generic real-time broadcast network for coordinating actions of a compact, pulse-to-pulse modulation based particle accelerator. High-level services include support for virtual accelerators and a rich selection of event response mechanisms. The system uses a combination of a real-time link for downstream events and a non-real-time link for upstream messaging and non time-critical communication. It comes with National Instruments LabVI...

  5. Quantifying stochastic resonance in bistable systems: Response vs residence-time distribution functions

    Science.gov (United States)

    Choi, Mee H.; Fox, R. F.; Jung, P.

    1998-06-01

    A wealth of research on stochastic resonance (SR) during the past decade has led to different ways of defining this phenomenon. Most prominent are measures based on the response function and on the residence-time distribution function. While the theory for the response functions is well developed, a first fully systematic theory for the residence-time distribution functions is developed in this paper. Subsequently we reconsider formerly introduced measures of SR based on the residence-time distribution and compare with those based on the response function.

  6. Maternity waiting homes in Rural Health Centers of Ethiop: The ...

    African Journals Online (AJOL)

    Background: Maternity waiting homes have been promoted to improve pregnant women's access to quality obstetric care. The main aim of this study was to assess the situation of maternity waiting homes and the experiences and challenges of mothers using waiting homes. Methods: A cross-sectional study was conducted ...

  7. Existence and calculation of the solution to the time distributed order diffusion equation

    Energy Technology Data Exchange (ETDEWEB)

    Atanackovic, T M [Department of Mechanics, Faculty of Technical Sciences, University of Novi Sad, Trg D Obradovica, 6, 21000 Novi Sad (Serbia); Pilipovic, S [Department of Mathematics, Faculty of Natural Sciences and Mathematics, University of Novi Sad, Trg D Obradovica, 3, 21000 Novi Sad (Serbia); Zorica, D [Faculty of Civil Engineering, University of Novi Sad, Kozaracka 2a, 24000 Subotica (Serbia)], E-mail: atanackovic@uns.ns.ac.yu, E-mail: pilipovic@im.ns.ac.yu, E-mail: zorica@gf.su.ac.yu

    2009-10-15

    The aim of this paper is to prove the existence of the solution to the Cauchy problem for the time distributed order diffusion equation as well as to calculate it. The existence is proved in this paper by reducing the Cauchy problem to an abstract Volterra equation in the case where the weight distribution in the distributed order derivative is a finite sum of Dirac distributions. Calculation of the solution is done by the use of Fourier and Laplace transformations in the case where the weight distribution (or function) is not specified. The solution is expressed in terms of heat potential kernel. The solutions for several special cases of the weight distribution, including the case of a finite sum of Dirac distributions, are presented as well.

  8. Identity of distributions of direct uphill and downhill translocation times for particles traversing membrane channels.

    Science.gov (United States)

    Berezhkovskii, Alexander M; Hummer, Gerhard; Bezrukov, Sergey M

    2006-07-14

    We study the distribution of direct translocation times for particles passing through membrane channels connecting two reservoirs. The direct translocation time is a conditional first-passage time defined as the residence time of the particle in the channel while passing to the other side of the membrane directly, i.e., without returning to the reservoir from which it entered. We show that the distributions of direct translocation times are identical for translocation in both directions, independent of any asymmetry in the potential across the channel and, hence, the translocation probabilities.

  9. Photon time interval distributions of cathodoluminescence light from a YVO4 − Eu3+ phosphor

    NARCIS (Netherlands)

    Rijswijk, F.C. van; Zijlstra, R.J.J.

    Measured photon time interval distributions and spectral noise densities justify the assumption of a Poisson distribution for the number of excitations per bombarding electron. A lifetime of 0.50 ± 0.02 ms was found for the 5D0 excited Eu3+ state.

  10. Attention, spatial integration, and the tail of response time distributions in Stroop task performance

    NARCIS (Netherlands)

    Roelofs, A.P.A.

    2012-01-01

    A few studies have examined selective attention in Stroop task performance through ex-Gaussian analyses of response time (RT) distributions. It has remained unclear whether the tail of the RT distribution in vocal responding reflects spatial integration of relevant and irrelevant attributes, as

  11. Validation Support for Distributed Real-Time Embedded Systems in VDM++

    DEFF Research Database (Denmark)

    S. Fitzgerald, John; Gorm Larsen, Peter; Tjell, Simon

    2007-01-01

    We present a tool-supported approach to the validation of system-level timing properties in formal models of distributed real-time embedded systems. Our aim is to provide system architects with rapid feedback on the timing characteristics of alternative designs in the often volatile early stages ...

  12. Design Optimization of Cyber-Physical Distributed Systems using IEEE Time-sensitive Networks (TSN)

    DEFF Research Database (Denmark)

    Pop, Paul; Lander Raagaard, Michael; Craciunas, Silviu S.

    2016-01-01

    In this paper we are interested in safety-critical real-time applications implemented on distributed architectures supporting the Time-SensitiveNetworking (TSN) standard. The ongoing standardization of TSN is an IEEE effort to bring deterministic real-time capabilities into the IEEE 802.1 Ethernet...

  13. Asymptotic distributions of coalescence times and ancestral lineage numbers for populations with temporally varying size.

    Science.gov (United States)

    Chen, Hua; Chen, Kun

    2013-07-01

    The distributions of coalescence times and ancestral lineage numbers play an essential role in coalescent modeling and ancestral inference. Both exact distributions of coalescence times and ancestral lineage numbers are expressed as the sum of alternating series, and the terms in the series become numerically intractable for large samples. More computationally attractive are their asymptotic distributions, which were derived in Griffiths (1984) for populations with constant size. In this article, we derive the asymptotic distributions of coalescence times and ancestral lineage numbers for populations with temporally varying size. For a sample of size n, denote by Tm the mth coalescent time, when m + 1 lineages coalesce into m lineages, and An(t) the number of ancestral lineages at time t back from the current generation. Similar to the results in Griffiths (1984), the number of ancestral lineages, An(t), and the coalescence times, Tm, are asymptotically normal, with the mean and variance of these distributions depending on the population size function, N(t). At the very early stage of the coalescent, when t → 0, the number of coalesced lineages n - An(t) follows a Poisson distribution, and as m → n, $$n\\left(n-1\\right){T}_{m}/2N\\left(0\\right)$$ follows a gamma distribution. We demonstrate the accuracy of the asymptotic approximations by comparing to both exact distributions and coalescent simulations. Several applications of the theoretical results are also shown: deriving statistics related to the properties of gene genealogies, such as the time to the most recent common ancestor (TMRCA) and the total branch length (TBL) of the genealogy, and deriving the allele frequency spectrum for large genealogies. With the advent of genomic-level sequencing data for large samples, the asymptotic distributions are expected to have wide applications in theoretical and methodological development for population genetic inference.

  14. Integrated response and transit time distributions of watersheds by combining hydrograph separation and long-term transit time modeling

    Directory of Open Access Journals (Sweden)

    M. C. Roa-García

    2010-08-01

    Full Text Available We present a new modeling approach analyzing and predicting the Transit Time Distribution (TTD and the Response Time Distribution (RTD from hourly to annual time scales as two distinct hydrological processes. The model integrates Isotope Hydrograph Separation (IHS and the Instantaneous Unit Hydrograph (IUH approach as a tool to provide a more realistic description of transit and response time of water in catchments. Individual event simulations and parameterizations were combined with long-term baseflow simulation and parameterizations; this provides a comprehensive picture of the catchment response for a long time span for the hydraulic and isotopic processes. The proposed method was tested in three Andean headwater catchments to compare the effects of land use on hydrological response and solute transport. Results show that the characteristics of events and antecedent conditions have a significant influence on TTD and RTD, but in general the RTD of the grassland dominated catchment is concentrated in the shorter time spans and has a higher cumulative TTD, while the forest dominated catchment has a relatively higher response distribution and lower cumulative TTD. The catchment where wetlands concentrate shows a flashier response, but wetlands also appear to prolong transit time.

  15. A Real-Time Fault Management Software System for Distributed Environments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — DyMA-FM (Dynamic Multivariate Assessment for Fault Management) is a software architecture for real-time fault management. Designed to run in a distributed...

  16. Integration of real-time mapping technology in disaster relief distribution.

    Science.gov (United States)

    2013-02-01

    Vehicle routing for disaster relief distribution involves many challenges that distinguish this problem from those in commercial settings, given the time sensitive and resource constrained nature of relief activities. While operations research approa...

  17. Distributions of time averages for weakly chaotic systems: the role of infinite invariant density.

    Science.gov (United States)

    Korabel, Nickolay; Barkai, Eli

    2013-09-01

    Distributions of time averaged observables are investigated using deterministic maps with N indifferent fixed points and N-state continuous time random walk processes associated with them. In a weakly chaotic phase, namely when separation of trajectories is subexponential, maps are characterized by an infinite invariant density. We find that the infinite density can be used to calculate the distribution of time averages of integrable observables with a formula recently obtained by Rebenshtok and Barkai. As an example we calculate distributions of the average position of the particle and average occupation fractions. Our work provides the distributional limit theorem for time averages for a wide class of nonintegrable observables with respect to the infinite invariant density, in other words it deals with the situation where the Darling-Kac-Aaronson theorem does not hold.

  18. A Metrics-Based Approach to Intrusion Detection System Evaluation for Distributed Real-Time Systems

    National Research Council Canada - National Science Library

    Fink, G

    2002-01-01

    ...) computer facilities to select the best intrusion detection system for their facilities. The metrics herein are the subset of our general metric set that particularly impact real-time and distributed processing issues...

  19. A Formal Approach to Run-Time Evaluation of Real-Time Behaviour in Distributed Process Control Systems

    DEFF Research Database (Denmark)

    Kristensen, C.H.

    This thesis advocates a formal approach to run-time evaluation of real-time behaviour in distributed process sontrol systems, motivated by a growing interest in applying the increasingly popular formal methods in the application area of distributed process control systems. We propose to evaluate...... a higher confidence in the system behaviour. We have proposed a combination of formal methods and supplemental fault-detection techniques which we call the Complementary Run-Time Evaluation Model. The basic idea in this model is to use the means of verification given by formal methods, to prove...... that the final system design is in accordance with any requirement from the requirement specification. When this is the case, the requirement is transformed by means of a class constraint extractor to a set of constraints. These are then to be evaluated at run-time. This thesis is devoted to temporal behaviour...

  20. EMD-WVD time-frequency distribution for analysis of multi-component signals

    Science.gov (United States)

    Chai, Yunzi; Zhang, Xudong

    2016-10-01

    Time-frequency distribution (TFD) is two-dimensional function that indicates the time-varying frequency content of one-dimensional signals. And The Wigner-Ville distribution (WVD) is an important and effective time-frequency analysis method. The WVD can efficiently show the characteristic of a mono-component signal. However, a major drawback is the extra cross-terms when multi-component signals are analyzed by WVD. In order to eliminating the cross-terms, we decompose signals into single frequency components - Intrinsic Mode Function (IMF) - by using the Empirical Mode decomposition (EMD) first, then use WVD to analyze each single IMF. In this paper, we define this new time-frequency distribution as EMD-WVD. And the experiment results show that the proposed time-frequency method can solve the cross-terms problem effectively and improve the accuracy of WVD time-frequency analysis.

  1. What Are We Waiting For Customer Wait Time, Fill Rate, And Marine Corps Equipment Operational Availability

    Science.gov (United States)

    2016-12-01

    agile solutions to both improve responsiveness and reduce costs with the overall goal of maintaining acceptable AO. Agile logistics solutions focus on...fields and 235,018 service request instances. GCSS2_SR_REPAIR_PART_HST table. This table is intended to provide a transaction cost summary. It...contains a partial historical record of transactions by service request that accounts for the cost of parts and an estimated cost of labor. The cost data

  2. Cumulative Interarrival Time Distributions of Freeway Entrance Ramp Traffic for Traffic Simulations

    Directory of Open Access Journals (Sweden)

    Erdinç Öner

    2013-02-01

    Full Text Available Cumulative interarrival time (IAT distributions for signalized and non-signalized freeway entrance ramps were developed to be used in digital computer traffic simulation models. The data from four different non-signalized entrance ramps (three ramps with a single lane, one ramp with two lanes and two different signalized entrance ramps (both with a single lane were used for developing the cumulative IAT distributions. The cumulative IAT distributions for the signalized and non-signalized entrance ramps were compared with each other and with the cumulative IAT distributions of the lanes for freeways. The comparative results showed that the cumulative IAT distributions for non-signalized entrance ramps are very close to the leftmost lane of a 3-lane freeway where the maximum absolute difference between the cumulative IAT distribution of the leftmost lane of a 3-lane freeway and the entrance ramps cumulative IAT distribution was 3%. The cumulative IAT distribution for the signalized entrance ramps was found to be different from the non-signalized entrance ramp cumulative IAT distribution. The approximated cumulative IAT distributions for signalized and non-signalized entrance ramp traffic for any hourly traffic volume from a few vehicles/hour up to 2,500 vehicles/hour can be obtained at http://www.ohio.edu/orite/research/uitds.cfm.

  3. A double hit model for the distribution of time to AIDS onset

    Science.gov (United States)

    Chillale, Nagaraja Rao

    2013-09-01

    Incubation time is a key epidemiologic descriptor of an infectious disease. In the case of HIV infection this is a random variable and is probably the longest one. The probability distribution of incubation time is the major determinant of the relation between the incidences of HIV infection and its manifestation to Aids. This is also one of the key factors used for accurate estimation of AIDS incidence in a region. The present article i) briefly reviews the work done, points out uncertainties in estimation of AIDS onset time and stresses the need for its precise estimation, ii) highlights some of the modelling features of onset distribution including immune failure mechanism, and iii) proposes a 'Double Hit' model for the distribution of time to AIDS onset in the cases of (a) independent and (b) dependent time variables of the two markers and examined the applicability of a few standard probability models.

  4. Behavior of Time-Resolved Ion Energy Distribution Functions during Ion-Ion Instability

    Science.gov (United States)

    Saitou, Yoshifumi; Nakamura, Yoshiharu; Tanaka, Masayoshi; Komori, Akio; Kawai, Yoshinobu

    1993-10-01

    When an external RF field is applied to an ion beam plasma system, ion-ion instability is suppressed at f/fii≳1, where f and fii are the frequency of the external RF field and the peak frequency of the instability, respectively. It is also observed that the time-averaged energy distribution function of the ion beam broadens when the instability is suppressed. In order to investigate the cause of this broadening, time-resolved energy distribution functions of ions are measured with a boxcar integrator. As a result, it is found that the energy distribution functions periodically change with the external RF field and the above broadening is apparently caused by the time-averaging of the energy distribution functions.

  5. Challenges in reducing the computational time of QSTS simulations for distribution system analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Deboever, Jeremiah [Georgia Inst. of Technology, Atlanta, GA (United States); Zhang, Xiaochen [Georgia Inst. of Technology, Atlanta, GA (United States); Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grijalva, Santiago [Georgia Inst. of Technology, Atlanta, GA (United States); Therrien, Francis [CME International T& D, St. Bruno, QC (Canada)

    2017-06-01

    The rapid increase in penetration of distributed energy resources on the electric power distribution system has created a need for more comprehensive interconnection modelling and impact analysis. Unlike conventional scenario - based studies , quasi - static time - series (QSTS) simulation s can realistically model time - dependent voltage controllers and the diversity of potential impacts that can occur at different times of year . However, to accurately model a distribution system with all its controllable devices, a yearlong simulation at 1 - second resolution is often required , which could take conventional computers a computational time of 10 to 120 hours when an actual unbalanced distribution feeder is modeled . This computational burden is a clear l imitation to the adoption of QSTS simulation s in interconnection studies and for determining optimal control solutions for utility operations . Our ongoing research to improve the speed of QSTS simulation has revealed many unique aspects of distribution system modelling and sequential power flow analysis that make fast QSTS a very difficult problem to solve. In this report , the most relevant challenges in reducing the computational time of QSTS simulations are presented: number of power flows to solve, circuit complexity, time dependence between time steps, multiple valid power flow solutions, controllable element interactions, and extensive accurate simulation analysis.

  6. Are anesthesia start and end times randomly distributed? The influence of electronic records.

    Science.gov (United States)

    Deal, Litisha G; Nyland, Michael E; Gravenstein, Nikolaus; Tighe, Patrick

    2014-06-01

    To perform a frequency analysis of start minute digits (SMD) and end minute digits (EMD) taken from the electronic, computer-assisted, and manual anesthesia billing-record systems. Retrospective cross-sectional review. University medical center. This cross-sectional review was conducted on billing records from a single healthcare institution over a 15-month period. A total of 30,738 cases were analyzed. For each record, the start time and end time were recorded. Distributions of SMD and EMD were tested against the null hypothesis of a frequency distribution equivalently spread between zero and nine. SMD and EMD aggregate distributions each differed from equivalency (P record, no differences were found between the recorded and expected equivalent distribution patterns for electronic anesthesia records for start minute (P records maintained nonequivalent distribution patterns for SMD and EMD (P record system, with automated time capture of events verified by the user, produces a more unified distribution of billing times than do more traditional methods of entering billing times. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Waiting room oral rehydration in the paediatric emergency department.

    Science.gov (United States)

    Craven, J A; Campbell, L; Martin, C T

    2009-03-01

    Oral rehydration is well established in the treatment of acute gastroenteritis, however it is profoundly underutilised as a treatment in the hospital setting. We introduced a protocol of waiting room oral rehydration for children presenting to the Paediatric Emergency Department with vomiting and/or diarrhoea. These children were given oral rehydration from the time of triage prior to medical assessment. During the study period, 251 children presented 269 times with vomiting and/or diarrhoea, of which 205 (76%) were diagnosed with acute gastroenteritis. A similar period 1 year previously was used as comparison, during which 129 children were diagnosed with acute gastroenteritis. During the study period, 58 children (28%) were given intravenous fluids and 47 (23%) were admitted, compared with 72 (56%) given intravenous fluids and 42 (32%) admitted in the comparison group. This protocol is now part of our routine management of children presenting with symptoms of acute gastroenteritis. Waiting room oral rehydration is a simple yet successful intervention that can be implemented in any Emergency Department.

  8. Impact of visual art on patient behavior in the emergency department waiting room.

    Science.gov (United States)

    Nanda, Upali; Chanaud, Cheryl; Nelson, Michael; Zhu, Xi; Bajema, Robyn; Jansen, Ben H

    2012-07-01

    Wait times have been reported to be one of the most important concerns for people visiting emergency departments (EDs). Affective states significantly impact perception of wait time. There is substantial evidence that art depicting nature reduces stress levels and anxiety, thus potentially impacting the waiting experience. To analyze the effect of visual art depicting nature (still and video) on patients' and visitors' behavior in the ED. A pre-post research design was implemented using systematic behavioral observation of patients and visitors in the ED waiting rooms of two hospitals over a period of 4 months. Thirty hours of data were collected before and after new still and video art was installed at each site. Significant reduction in restlessness, noise level, and people staring at other people in the room was found at both sites. A significant decrease in the number of queries made at the front desk and a significant increase in social interaction were found at one of the sites. Visual art has positive effects on the ED waiting experience. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Travel time distributions, soil moisture dynamics and the old water paradox

    Science.gov (United States)

    Botter, G.; Bertuzzo, E.; Rinaldo, A.

    2010-12-01

    We propose a mathematical framework for the general definition and computation of travel time distributions defined by the closure of a catchment control volume, where the input flux is an arbitrary rainfall pattern and the output fluxes are green and blue water flows (namely, evapotranspiration and the hydrologic response embedding runoff production through soil water dynamics). The relevance of the problem is both practical, owing to implications in hydrologic watershed modeling and planning of measurement network, and conceptual, for the linkages and the explanations the theory provides on the dependence of travel time distributions on geomorphology, climate, soils, and vegetation through soil water dynamics. The work focuses in particular on the origins of the conditional and time variant nature of travel time distributions and on the differences between unit hydrographs and travel time distributions. Both carrier flow and solute matter transport in the control volume are accounted for coherently. The key effect of mixing processes occurring within runoff production is also investigated, in particular by a model that assumes that mobilization of soil water involves randomly sampled particles from the available storage. Travel time distributions are thus analytically expressed in terms of the major water fluxes driving soil moisture dynamics (rainfall, streamflows, evapotranpiration), irrespectively of the specific model used to compute such fluxes. Relevant numerical examples and a set of generalized applications are finally provided and discussed.

  10. Fast and accurate calculations for cumulative first-passage time distributions in Wiener diffusion models

    DEFF Research Database (Denmark)

    Blurton, Steven Paul; Kesselmeier, M.; Gondan, Matthias

    2012-01-01

    related work on the density of first-passage times [Navarro, D.J., Fuss, I.G. (2009). Fast and accurate calculations for first-passage times in Wiener diffusion models. Journal of Mathematical Psychology, 53, 222-230]. Two representations exist for the distribution, both including infinite series. We...

  11. Predictive analytics for truck arrival time estimation : a field study at a European distribution center

    NARCIS (Netherlands)

    van der Spoel, Sjoerd; Amrit, Chintan Amrit; van Hillegersberg, Jos

    2017-01-01

    Distribution centres (DCs) are the hubs connecting transport streams in the supply chain. The synchronisation of coming and going cargo at a DC requires reliable arrival times. To achieve this, a reliable method to predict arrival times is needed. A literature review was performed to find the

  12. LHCb : Clock and timing distribution in the LHCb upgraded detector and readout system

    CERN Multimedia

    Alessio, Federico; Barros Marin, M; Cachemiche, JP; Hachon, F; Jacobsson, Richard; Wyllie, Ken

    2014-01-01

    The LHCb experiment is upgrading part of its detector and the entire readout system towards a full 40 MHz readout system in order to run between five and ten times its initial design luminosity and increase its trigger efficiency. In this paper, the new timing, trigger and control distribution system for such an upgrade is reviewed with particular attention given to the distribution of the clock and timing information across the entire readout system, up to the FE and the on-detector electronics. Current ideas are here presented in terms of reliability, jitter, complexity and implementation.

  13. Finite Time Control for Fractional Order Nonlinear Hydroturbine Governing System via Frequency Distributed Model

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2016-01-01

    Full Text Available This paper studies the application of frequency distributed model for finite time control of a fractional order nonlinear hydroturbine governing system (HGS. Firstly, the mathematical model of HGS with external random disturbances is introduced. Secondly, a novel terminal sliding surface is proposed and its stability to origin is proved based on the frequency distributed model and Lyapunov stability theory. Furthermore, based on finite time stability and sliding mode control theory, a robust control law to ensure the occurrence of the sliding motion in a finite time is designed for stabilization of the fractional order HGS. Finally, simulation results show the effectiveness and robustness of the proposed scheme.

  14. Optimal distribution of integration time for intensity measurements in Stokes polarimetry.

    Science.gov (United States)

    Li, Xiaobo; Liu, Tiegen; Huang, Bingjing; Song, Zhanjie; Hu, Haofeng

    2015-10-19

    We consider the typical Stokes polarimetry system, which performs four intensity measurements to estimate a Stokes vector. We show that if the total integration time of intensity measurements is fixed, the variance of the Stokes vector estimator depends on the distribution of the integration time at four intensity measurements. Therefore, by optimizing the distribution of integration time, the variance of the Stokes vector estimator can be decreased. In this paper, we obtain the closed-form solution of the optimal distribution of integration time by employing Lagrange multiplier method. According to the theoretical analysis and real-world experiment, it is shown that the total variance of the Stokes vector estimator can be significantly decreased about 40% in the case discussed in this paper. The method proposed in this paper can effectively decrease the measurement variance and thus statistically improves the measurement accuracy of the polarimetric system.

  15. Optimal distribution of integration time for intensity measurements in degree of linear polarization polarimetry.

    Science.gov (United States)

    Li, Xiaobo; Hu, Haofeng; Liu, Tiegen; Huang, Bingjing; Song, Zhanjie

    2016-04-04

    We consider the degree of linear polarization (DOLP) polarimetry system, which performs two intensity measurements at orthogonal polarization states to estimate DOLP. We show that if the total integration time of intensity measurements is fixed, the variance of the DOLP estimator depends on the distribution of integration time for two intensity measurements. Therefore, by optimizing the distribution of integration time, the variance of the DOLP estimator can be decreased. In this paper, we obtain the closed-form solution of the optimal distribution of integration time in an approximate way by employing Delta method and Lagrange multiplier method. According to the theoretical analyses and real-world experiments, it is shown that the variance of the DOLP estimator can be decreased for any value of DOLP. The method proposed in this paper can effectively decrease the measurement variance and thus statistically improve the measurement accuracy of the polarimetry system.

  16. Predicting Fluid Intelligence by Components of Reaction Time Distributions from Simple Choice Reaction Time Tasks

    Directory of Open Access Journals (Sweden)

    Yoanna Schulz-Zhecheva

    2016-07-01

    Full Text Available Mean reaction times (RT and the intra-subject variability of RT in simple RT tasks have been shown to predict higher-order cognitive abilities measured with psychometric intelligence tests. To further explore this relationship and to examine its generalizability to a sub-adult-aged sample, we administered different choice RT tasks and Cattell’s Culture Fair Intelligence Test (CFT 20-R to n = 362 participants aged eight to 18 years. The parameters derived from applying Ratcliff’s diffusion model and an ex-Gaussian model to age-residualized RT data were used to predict fluid intelligence using structural equation models. The drift rate parameter of the diffusion model, as well as σ of the ex-Gaussian model, showed substantial predictive validity regarding fluid intelligence. Our findings demonstrate that stability of performance, more than its mere speed, is relevant for fluid intelligence and we challenge the universality of the worst performance rule observed in adult samples.

  17. Real-time measurements and their effects on state estimation of distribution power system

    DEFF Research Database (Denmark)

    Han, Xue; You, Shi; Thordarson, Fannar

    2013-01-01

    This paper aims at analyzing the potential value of using different real-time metering and measuring instruments applied in the low voltage distribution networks for state-estimation. An algorithm is presented to evaluate different combinations of metering data using a tailored state estimator....... It is followed by a case study based on the proposed algorithm. A real distribution grid feeder with different types of meters installed either in the cabinets or at the customer side is selected for simulation and analysis. Standard load templates are used to initiate the state estimation. The deviations...... between the estimated values (voltage and injected power) and the measurements are applied to evaluate the accuracy of the estimated grid states. Eventually, some suggestions are provided for the distribution grid operators on placing the real-time meters in the distribution grid....

  18. Real-Time Analysis and Forecasting of Multisite River Flow Using a Distributed Hydrological Model

    Directory of Open Access Journals (Sweden)

    Mingdong Sun

    2014-01-01

    Full Text Available A spatial distributed hydrological forecasting system was developed to promote the analysis of river flow dynamic state in a large basin. The research presented the real-time analysis and forecasting of multisite river flow in the Nakdong River Basin using a distributed hydrological model with radar rainfall forecast data. A real-time calibration algorithm of hydrological distributed model was proposed to investigate the particular relationship between the water storage and basin discharge. Demonstrate the approach of simulating multisite river flow using a distributed hydrological model couple with real-time calibration and forecasting of multisite river flow with radar rainfall forecasts data. The hydrographs and results exhibit that calibrated flow simulations are very approximate to the flow observation at all sites and the accuracy of forecasting flow is gradually decreased with lead times extending from 1 hr to 3 hrs. The flow forecasts are lower than the flow observation which is likely caused by the low estimation of radar rainfall forecasts. The research has well demonstrated that the distributed hydrological model is readily applicable for multisite real-time river flow analysis and forecasting in a large basin.

  19. On the Distribution of Earthquake Interevent Times and the Impact of Spatial Scale

    Science.gov (United States)

    Hristopulos, Dionissios

    2013-04-01

    The distribution of earthquake interevent times is a subject that has attracted much attention in the statistical physics literature [1-3]. A recent paper proposes that the distribution of earthquake interevent times follows from the the interplay of the crustal strength distribution and the loading function (stress versus time) of the Earth's crust locally [4]. It was also shown that the Weibull distribution describes earthquake interevent times provided that the crustal strength also follows the Weibull distribution and that the loading function follows a power-law during the loading cycle. I will discuss the implications of this work and will present supporting evidence based on the analysis of data from seismic catalogs. I will also discuss the theoretical evidence in support of the Weibull distribution based on models of statistical physics [5]. Since other-than-Weibull interevent times distributions are not excluded in [4], I will illustrate the use of the Kolmogorov-Smirnov test in order to determine which probability distributions are not rejected by the data. Finally, we propose a modification of the Weibull distribution if the size of the system under investigation (i.e., the area over which the earthquake activity occurs) is finite with respect to a critical link size. keywords: hypothesis testing, modified Weibull, hazard rate, finite size References [1] Corral, A., 2004. Long-term clustering, scaling, and universality in the temporal occurrence of earthquakes, Phys. Rev. Lett., 9210) art. no. 108501. [2] Saichev, A., Sornette, D. 2007. Theory of earthquake recurrence times, J. Geophys. Res., Ser. B 112, B04313/1-26. [3] Touati, S., Naylor, M., Main, I.G., 2009. Origin and nonuniversality of the earthquake interevent time distribution Phys. Rev. Lett., 102 (16), art. no. 168501. [4] Hristopulos, D.T., 2003. Spartan Gibbs random field models for geostatistical applications, SIAM Jour. Sci. Comput., 24, 2125-2162. [5] I. Eliazar and J. Klafter, 2006

  20. The control of deliberate waiting strategies in a stop-signal task

    Directory of Open Access Journals (Sweden)

    R.P. Sylwan

    2004-06-01

    Full Text Available To inhibit an ongoing flow of thoughts or actions has been largely considered to be a crucial executive function, and the stop-signal paradigm makes inhibitory control measurable. Stop-signal tasks usually combine two concurrent tasks, i.e., manual responses to a primary task (go-task are occasionally countermanded by a stimulus which signals participants to inhibit their response in that trial (stop-task. Participants are always instructed not to wait for the stop-signal, since waiting strategies cause the response times to be unstable, invalidating the data. The aim of the present study was to experimentally control the strategies of waiting deliberately for the stop-signal in a stop-task by means of an algorithm that measured the variation in the reaction times to go-stimuli on-line, and displayed a warning legend urging participants to be faster when their reaction times were more than two standard deviations of the mean. Thirty-four university students performed a stop-task with go- and stop-stimuli, both of which were delivered in the visual modality and were lateralized within the visual field. The participants were divided into two groups (group A, without the algorithm, vs group B, with the algorithm. Group B exhibited lower variability of reaction times to go-stimuli, whereas no significant between-group differences were found in any of the measures of inhibitory control, showing that the algorithm succeeded in controlling the deliberate waiting strategies. Differences between deliberate and unintentional waiting strategies, and anxiety as a probable factor responsible for individual differences in deliberate waiting behavior, are discussed.

  1. Modelling water quality in drinking water distribution networks from real-time direction data

    OpenAIRE

    Nazarovs, S.; Dejus, S.; Juhna, T.

    2012-01-01

    Modelling of contamination spread and location of a contamination source in a water distribution network is an important task. There are several simulation tools developed, however the significant part of them is based on hydraulic models that need node demands as input data that sometimes may result in false negative results and put users at risk. The paper considers applicability of a real-time flow direction data based model for contaminant transport in a distribution network of a city and...

  2. Statistical Timing Modeling Based on a Lognormal Distribution Model for Near-Threshold Circuit Optimization

    OpenAIRE

    SHIOMI, Jun; Ishihara, Tohru; ONODERA, Hidetoshi

    2015-01-01

    Near-threshold computing has emerged as one of the most promising solutions for enabling highly energy efficient and high performance computation of microprocessors. This paper proposes architecture-level statistical static timing analysis (SSTA) models for the near-threshold voltage computing where the path delay distribution is approximated as a lognormal distribution. First, we prove several important theorems that help consider architectural design strategies for high performance and ener...

  3. High-Speed Access to RFID Data: Meeting Real-Time Requirements in Distributed Value Chains

    Science.gov (United States)

    Ziekow, Holger; Fabian, Benjamin; Müller, Cristian

    Using RFID data within operational processes requires fast data access. In distributed value chains, RFID data is not only captured locally, but also accessed from remote locations. However, retrieving data from remote RFID repositories may pose significant delays and slow down the operations. This paper analyses how companies can exchange RFID data in the presence of real-time requirements. We analyze results of performance experiments with globally distributed RFID repositories and propose novel architectures for speeding up data access.

  4. A new model for describing remission times: the generalized beta-generated Lindley distribution

    Directory of Open Access Journals (Sweden)

    MARIA DO CARMO S. LIMA

    Full Text Available New generators are required to define wider distributions for modeling real data in survival analysis. To that end we introduce the four-parameter generalized beta-generated Lindley distribution. It has explicit expressions for the ordinary and incomplete moments, mean deviations, generating and quantile functions. We propose a maximum likelihood procedure to estimate the model parameters, which is assessed through a Monte Carlo simulation study. We also derive an additional estimation scheme by means of least square between percentiles. The usefulness of the proposed distribution to describe remission times of cancer patients is illustrated by means of an application to real data.

  5. Execution time supports for adaptive scientific algorithms on distributed memory machines

    Science.gov (United States)

    Berryman, Harry; Saltz, Joel; Scroggs, Jeffrey

    1990-01-01

    Optimizations are considered that are required for efficient execution of code segments that consists of loops over distributed data structures. The PARTI (Parallel Automated Runtime Toolkit at ICASE) execution time primitives are designed to carry out these optimizations and can be used to implement a wide range of scientific algorithms on distributed memory machines. These primitives allow the user to control array mappings in a way that gives an appearance of shared memory. Computations can be based on a global index set. Primitives are used to carry out gather and scatter operations on distributed arrays. Communications patterns are derived at runtime, and the appropriate send and receive messages are automatically generated.

  6. Application of Choi—Williams Reduced Interference Time Frequency Distribution to Machinery Diagnostics

    Directory of Open Access Journals (Sweden)

    Howard A. Gaberson

    1995-01-01

    Full Text Available This article discusses time frequency analysis of machinery diagnostic vibration signals. The short time Fourier transform, the Wigner, and the Choi–Williams distributions are explained and illustrated with test cases. Examples of Choi—Williams analyses of machinery vibration signals are presented. The analyses detect discontinuities in the signals and their timing, amplitude and frequency modulation, and the presence of different components in a vibration signal.

  7. Donders revisited: Discrete or continuous temporal processing underlying reaction time distributions?

    Science.gov (United States)

    Bao, Yan; Yang, Taoxi; Lin, Xiaoxiong; Pöppel, Ernst

    2016-09-01

    Differences of reaction times to specific stimulus configurations are used as indicators of cognitive processing stages. In this classical experimental paradigm, continuous temporal processing is implicitly assumed. Multimodal response distributions indicate, however, discrete time sampling, which is often masked by experimental conditions. Differences in reaction times reflect discrete temporal mechanisms that are pre-semantically implemented and suggested to be based on entrained neural oscillations. © 2016 The Institute of Psychology, Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  8. Clinical Impact and Risk Factors of Portal Vein Thrombosis for Patients on Wait List for Liver Transplant.

    Science.gov (United States)

    Montenovo, Martin; Rahnemai-Azar, Amir; Reyes, Jorge; Perkins, James

    2017-06-16

    The effect of portal vein thrombosis on the progression of liver disease is controversial, with no consensus on optimal treatment. We aimed to assess how portal vein thrombosis affects wait list outcomes, identify risk factors associated with its development while on a wait list, and assess its effects on patient and graft survival. This US-based retrospective cohort study analyzed 134 109 adult patients on wait lists for or undergoing primary orthotopic liver transplant between January 2002 and June 2014. Rate of portal vein thrombosis development, time from entry on wait list to transplant, comparisons of wait list drop-off rates between patients with versus those without portal vein thrombosis, risk factors associated with its development while on a wait list, and its effects on patient and graft survival were analyzed. We found that the rate of portal vein thrombosis at listing increased. Patients with the disease at listing were more likely to be removed from wait lists because of being too sick. Portal vein thrombosis at listing was an independent risk factor for being removed from a wait list. Of 63 265 patients who underwent primary orthotopic liver transplant, those with the disease were more likely to have higher Model for End-Stage Liver Disease scores and incidence of nonalcoholic steatohepatitis and diabetes mellitus. Portal vein thrombosis had a negative effect on patient and graft survival. Nonalcoholic steatohepatitis, body mass index, diabetes, and hepatocellular carcinoma were identified as risk factors for its development. Portal vein thrombosis represents an increasing management and outcome burden in liver transplant. Having this disease at listing and/or at time of transplant is associated with worse patient and graft survival. Nonalcoholic steatohepatitis and hepatocellular carcinoma are among the biggest risk factors for its development while on a wait list.

  9. A novel method for determining residence time distribution in intricately structured microreactors.

    Science.gov (United States)

    Lohse, Sebastian; Kohnen, Boris Terje; Janasek, Dirk; Dittrich, Petra Stephanie; Franzke, Joachim; Agar, David William

    2008-03-01

    A precise characterisation of microreactors can be achieved by determining the residence time distribution as one of the most important flow characteristics. An approach specially designed for microreactor applications was developed, which employs a tracer 'injection' using the optical activation of a caged fluorescent dye. Furthermore, the effect of the laminar flow on the determination of the residence time distribution in microreactors has been taken into account during the measurements and their interpretation to fulfill the requirements of the so-called 'mixing-cup-problem' on the microscale. Residence time distributions for an intricately structured thin microreactor were determined for different velocities. The ideality of the stimulus signal generated by the newly introduced technique is demonstrated for an analytically well-defined straight channel and compared with a signal derived from deconvolution of non-ideal input signals.

  10. Time-headway distribution for periodic totally asymmetric exclusion process with various updates

    Science.gov (United States)

    Hrabák, P.; Krbálek, M.

    2016-03-01

    The totally asymmetric exclusion process (TASEP) with periodic boundaries is considered as traffic flow model. The large-L approximation of the stationary state is used for the derivation of the time-headway distribution (an important microscopic characteristic of traffic flow) for the model with generalized update (genTASEP) in both, forward- and backward-sequential representations. The usually used updates, fully-parallel and regular forward- and backward-sequential, are analyzed as special cases of the genTASEP. It is shown that only for those cases, the time-headway distribution is determined by the flow regardless to the density. The qualitative comparison of the results with traffic data demonstrates that the genTASEP with backward order and attractive interaction evinces similar properties of time-headway distribution as the real traffic sample.

  11. Characterizing corridor-level travel time distributions based on stochastic flows and segment capacities

    Directory of Open Access Journals (Sweden)

    Hao Lei

    2015-12-01

    Full Text Available Trip travel time reliability is an important measure of transportation system performance and a key factor affecting travelers’ choices. This paper explores a method for estimating travel time distributions for corridors that contain multiple bottlenecks. A set of analytical equations are used to calculate the number of queued vehicles ahead of a probe vehicle and further capture many important factors affecting travel times: the prevailing congestion level, queue discharge rates at the bottlenecks, and flow rates associated with merges and diverges. Based on multiple random scenarios and a vector of arrival times, the lane-by-lane delay at each bottleneck along the corridor is recursively estimated to produce a route-level travel time distribution. The model incorporates stochastic variations of bottleneck capacity and demand and explains the travel time correlations between sequential links. Its data needs are the entering and exiting flow rates and a sense of the lane-by-lane distribution of traffic at each bottleneck. A detailed vehicle trajectory data-set from the Next Generation SIMulation (NGSIM project has been used to verify that the estimated distributions are valid, and the sources of estimation error are examined.

  12. Learning to wait for more likely or just more: greater tolerance to delays of reward with increasingly longer delays.

    Science.gov (United States)

    Rung, Jillian M; Young, Michael E

    2015-01-01

    Little research has focused on training greater tolerance to delays of rewards in the context of delayed gratification. In delayed gratification, waiting for a delayed outcome necessitates the ability to resist defection for a continuously available smaller, immediate outcome. The present research explored the use of a fading procedure for producing greater waiting in a video-game based, delayed gratification task. Participants were assigned to conditions in which either the reward magnitude, or the probability of receiving a reward, was a function of time waited and the delay to the maximum reward was gradually increased throughout this training. Waiting increased for all participants but less for those waiting for a greater reward magnitude than a greater reward probability. All participants showed a tendency to wait in a final testing phase, but training with probabilistic outcomes produced a significantly greater likelihood of waiting during testing. The behavioral requirements of delay discounting versus delay gratification are discussed, as well as the benefits of training greater self-control in a variety of contexts. © Society for the Experimental Analysis of Behavior.

  13. The concept of a waiting period for preoperative patient consent: Prospective study of 51 shoulder arthroscopy cases.

    Science.gov (United States)

    Coudane, H; Mangin, M; Karam, Y; Seivert, V; Mainard, D; Danan, J L; Py, B; Lighezzolo-Alnot, J

    2017-09-01

    The French Code of Public Health (CSP) does not explicitly require that patients should be given a certain amount of time to think about a procedure, except for cosmetic surgery, where 15 days is required (Art. L 6322-2 CSP). We hypothesized that patients require a waiting period during their decision-making process for scheduled shoulder arthroscopy procedure. This prospective observational study of 51 patients analysed the concept of a waiting period based on a 10-item questionnaire. A comparative statistical approach was used and the P values were calculated using a paired Wilcoxon rank-sum test. Of the 51 patients, 42 (82%) rejected the concept of a waiting period before the procedure and 37 patients (73%) did not want a mandatory waiting period imposed by law. This study looked at the decision-making process during scheduled orthopaedic surgery and differentiated between the conscious and unconscious approach corresponding to an active and passive waiting period. A waiting period does not allow patients to make a conceptually deliberative decision that conforms to the criteria defined by the French Health Authority. This study rejects the need for a mandatory waiting period imposed on surgeons and patients as it does not integrate itself into the informative model of ethical decision-making for scheduled shoulder arthroscopy. Prospective, observational; level of evidence IV. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  14. Approximation of sojourn-times via maximal couplings: motif frequency distributions.

    Science.gov (United States)

    Lladser, Manuel E; Chestnut, Stephen R

    2014-07-01

    Sojourn-times provide a versatile framework to assess the statistical significance of motifs in genome-wide searches even under non-Markovian background models. However, the large state spaces encountered in genomic sequence analyses make the exact calculation of sojourn-time distributions computationally intractable in long sequences. Here, we use coupling and analytic combinatoric techniques to approximate these distributions in the general setting of Polish state spaces, which encompass discrete state spaces. Our approximations are accompanied with explicit, easy to compute, error bounds for total variation distance. Broadly speaking, if Tn is the random number of times a Markov chain visits a certain subset T of states in its first n transitions, then we can usually approximate the distribution of Tn for n of order (1 − α)(−m), where m is the largest integer for which the exact distribution of Tm is accessible and 0 ≤ α ≤ 1 is an ergodicity coefficient associated with the probability transition kernel of the chain. This gives access to approximations of sojourn-times in the intermediate regime where n is perhaps too large for exact calculations, but too small to rely on Normal approximations or stationarity assumptions underlying Poisson and compound Poisson approximations. As proof of concept, we approximate the distribution of the number of matches with a motif in promoter regions of C.

  15. Flow Time Analysis of Load Management Late Arrival Discrete Time Queueing System with Dual Service Rate Using Hypogeometrical Distribution

    Directory of Open Access Journals (Sweden)

    Syed Asif Ali Shah

    2012-01-01

    Full Text Available Flow time analysis is a powerful concept to analyze the flow time of any arriving customer in any system at any instant. A load management mechanism can be employed very effectively in any queueing system by utilizing a system which provides probability of dual service rate. In this paper, we develop and demonstrate the flow and service processes transition diagram to determine the flow time of a customer in a load management late arrival state dependent finite discrete time queueing system with dual service rate where customers are hypogeometrically distributed. We compute the probability mass function of each starting state and total probability mass function. The obtained analytical results are validated with simulation results for varying values of arrival and service probabilities.

  16. Timing of pubertal onset in girls: evidence for non-Gaussian distribution.

    Science.gov (United States)

    Papadimitriou, Anastasios; Pantsiotou, Soula; Douros, Konstandinos; Papadimitriou, Dimitrios T; Nicolaidou, Polyxeni; Fretzayas, Andreas

    2008-11-01

    The timing of the onset of puberty is considered to approximate a normal distribution. However, because many more girls present with early than late puberty, we hypothesized that the distribution of the timing of the onset of puberty in girls might have changed. OBJECTIVE/SUBJECTS: The objective of the study was to examine the distribution of the timing of the onset of puberty in normal Greek girls. Onset of puberty, i.e. breast development (B2), was studied longitudinally in 311 prepubertal schoolgirls aged 6.4-8.2 yr until the onset of puberty. We also studied cross-sectionally 126 girls, 6-14 yr old. Clinical examinations took place in the school setting. In the longitudinal study, median of the distribution of age at B2 was 10.0 yr (with the 25th and 75th centiles being 9.2 and 10.6 yr, respectively). Skewness was -0.45 (P=0.001), suggesting a negatively skewed distribution. In the cross-sectional study, 126 subjects were found at B2. The median of the age distribution at B2 was 10.1 yr (with the 25th and 75th centiles being 9.7 and 11.2 years, respectively). Skewness was -0.44 (P=0.03), suggesting a negatively skewed distribution. A non-Gaussian distribution of the age at the onset of puberty in girls was documented. The currently used cutoff ages for precocious and delayed puberty may not be applicable to modern children; therefore, up-to-date studies on pubertal maturation are much needed.

  17. State anxiety during watchful waiting for urinary lithiasis.

    Science.gov (United States)

    Kalaitzi, C; Kalantzis, A; Gravas, S; Georgiadis, J; Christodoulou, C

    2006-01-01

    Guidelines on many disorders recommend a variable period of watchful waiting between diagnosis and indicated action. In this study, we assessed stress during the watchful waiting period for urinary lithiasis, a benign disorder treated with minimally invasive procedures, without the pitfall of the emotional burden of a terminal or debilitating disease or fear of impending major surgery and to assess the distress caused by waiting per se. Furthermore, we attempt to identify individual patients at risk of prolonged or debilitating psychological distress. A total of 112 lithiasis patients with stones pain during the waiting period. Clinicians should be more flexible when they face the above group of patients, as far as the duration of watchful waiting period is concerned, because a long waiting sets those patients under significant emotional burden.

  18. Time-resolved spatial distribution of Balmer alpha line radiation from magnetoplasma compressor

    Science.gov (United States)

    Dojčinović, I. P.; Kuraica, M. M.; Astashynski, V. M.; Cvetanović, N.; Purić, J.

    2002-12-01

    This paper deals with time and spatial resolved spectroscopy of hydrogen Balmer alpha line radiation from MPC plasma. Plasma was observed with a set of 10 optical fibers distributed along z axis starting from the outlet of the cathode with 7 mm separation up to 6.3 cm distance. The radiation was analysed using HR320S spectrometer equipped with and IMACON 790 high speed camera system with appropriated CCD camera for detection. From the registered time and spatially resolved Balmer line images, the Stark profiles of Hα lines were obtained and from them temporal and spatial electron density distribution of MPC plasma was determined.

  19. Continuous monitoring of distributed data streams over a time-based sliding window

    DEFF Research Database (Denmark)

    Chan, Ho-Leung; Lam, Tak-Wah; Lee, Lap Kei

    2012-01-01

    In this paper we extend the study of algorithms for monitoring distributed data streams from whole data streams to a time-based sliding window. The concern is how to minimize the communication between individual streams and the root, while allowing the root, at any time, to report the global...... for frequent items and O(k ε 2 logN k ) words for quantiles, where k is the number of distributed data streams, N is the total number of items in the streams that arrive or expire in the window, and ε... lower bounds. We also show how to generalize these results to streams with out-of-order data....

  20. Methods of Run-Time Error Detection in Distributed Process Control Software

    DEFF Research Database (Denmark)

    Drejer, N.

    In this thesis, methods of run-time error detection in application software for distributed process control is designed. The error detection is based upon a monitoring approach in which application software is monitored by system software during the entire execution. The thesis includes definition...... and constraint evaluation is designed for the modt interesting error types. These include: a) semantical errors in data communicated between application tasks; b) errors in the execution of application tasks; and c) errors in the timing of distributed events emitted by the application software. The design...