WorldWideScience

Sample records for high attrition rates

  1. Attrition and success rates of accelerated students in nursing courses: a systematic review.

    Science.gov (United States)

    Doggrell, Sheila Anne; Schaffer, Sally

    2016-01-01

    There is a comprehensive literature on the academic outcomes (attrition and success) of students in traditional/baccalaureate nursing programs, but much less is known about the academic outcomes of students in accelerated nursing programs. The aim of this systematic review is to report on the attrition and success rates (either internal examination or NCLEX-RN) of accelerated students, compared to traditional students. For the systematic review, the databases (Pubmed, Cinahl and PsychINFO) and Google Scholar were searched using the search terms 'accelerated' or 'accreditation for prior learning', 'fast-track' or 'top up' and 'nursing' with 'attrition' or 'retention' or 'withdrawal' or 'success' from 1994 to January 2016. All relevant articles were included, regardless of quality. The findings of 19 studies of attrition rates and/or success rates for accelerated students are reported. For international accelerated students, there were only three studies, which are heterogeneous, and have major limitations. One of three studies has lower attrition rates, and one has shown higher success rates, than traditional students. In contrast, another study has shown high attrition and low success for international accelerated students. For graduate accelerated students, most of the studies are high quality, and showed that they have rates similar or better than traditional students. Thus, five of six studies have shown similar or lower attrition rates. Four of these studies with graduate accelerated students and an additional seven studies of success rates only, have shown similar or better success rates, than traditional students. There are only three studies of non-university graduate accelerated students, and these had weaknesses, but were consistent in reporting higher attrition rates than traditional students. The paucity and weakness of information available makes it unclear as to the attrition and/or success of international accelerated students in nursing programs. The

  2. How can attrition rates be reduced in cancer drug discovery?

    Science.gov (United States)

    Moreno, Lucas; Pearson, Andrew D J

    2013-04-01

    Attrition is a major issue in anticancer drug development with up to 95% of drugs tested in Phase I trials not reaching a marketing authorisation making the drug development process enormously costly and inefficient. It is essential that this problem is addressed throughout the whole drug development process to improve efficiency which will ultimately result in increased patient benefit with more profitable drugs. The approach to reduce cancer drug attrition rates must be based on three pillars. The first of these is that there is a need for new pre-clinical models which can act as better predictors of success in clinical trials. Furthermore, clinical trials driven by tumour biology with the incorporation of predictive and pharmacodynamic biomarkers would be beneficial in drug development. Finally, there is a need for increased collaboration to combine the unique strengths between industry, academia and regulators to ensure that the needs of all stakeholders are met.

  3. Are pilot trials useful for predicting randomisation and attrition rates in definitive studies: A review of publicly funded trials

    Science.gov (United States)

    Whitehead, Amy; Pottrill, Edward; Julious, Steven A; Walters, Stephen J

    2018-01-01

    Background/aims: External pilot trials are recommended for testing the feasibility of main or confirmatory trials. However, there is little evidence that progress in external pilot trials actually predicts randomisation and attrition rates in the main trial. To assess the use of external pilot trials in trial design, we compared randomisation and attrition rates in publicly funded randomised controlled trials with rates in their pilots. Methods: Randomised controlled trials for which there was an external pilot trial were identified from reports published between 2004 and 2013 in the Health Technology Assessment Journal. Data were extracted from published papers, protocols and reports. Bland–Altman plots and descriptive statistics were used to investigate the agreement of randomisation and attrition rates between the full and external pilot trials. Results: Of 561 reports, 41 were randomised controlled trials with pilot trials and 16 met criteria for a pilot trial with sufficient data. Mean attrition and randomisation rates were 21.1% and 50.4%, respectively, in the pilot trials and 16.8% and 65.2% in the main. There was minimal bias in the pilot trial when predicting the main trial attrition and randomisation rate. However, the variation was large: the mean difference in the attrition rate between the pilot and main trial was −4.4% with limits of agreement of −37.1% to 28.2%. Limits of agreement for randomisation rates were −47.8% to 77.5%. Conclusion: Results from external pilot trials to estimate randomisation and attrition rates should be used with caution as comparison of the difference in the rates between pilots and their associated full trial demonstrates high variability. We suggest using internal pilot trials wherever appropriate. PMID:29361833

  4. Attrition and success rates of accelerated students in nursing courses: a systematic review

    OpenAIRE

    Doggrell, Sheila Anne; Schaffer, Sally

    2016-01-01

    Background There is a comprehensive literature on the academic outcomes (attrition and success) of students in traditional/baccalaureate nursing programs, but much less is known about the academic outcomes of students in accelerated nursing programs. The aim of this systematic review is to report on the attrition and success rates (either internal examination or NCLEX-RN) of accelerated students, compared to traditional students. Methods For the systematic review, the databases (Pubmed, Cinah...

  5. A Correlational Study of a Reading Comprehension Program and Attrition Rates of ESL Nursing Students in Texas.

    Science.gov (United States)

    Donnell, Wendy M

    The purpose of this study was to examine the associations between English as a second language (ESL), a reading comprehension program, and attrition rates of nursing students. Higher attrition rates of ESL nursing students are an assumption, seemingly based on anecdotal evidence. Data reflecting ESL student attrition should be measured and analyzed so that students can be identified prior to attrition. A secondary analysis of a large database of 27 initial licensure programs in Texas was completed. Data analysis identified that ESL students who used a reading comprehension program were almost twice as likely to be off track or out of the program as ESL students who did not use the program. Nurse educators need to evaluate student profile characteristics in a comprehensive way when determining risk of attrition.

  6. Non-Rated Air Force Line Officer Attrition Rates Using Survival Analysis

    Science.gov (United States)

    2015-03-26

    Further complicating human resourcing, all Air Force members–enlisted and officer–start at entry-level. Personnel entering the Air Force inventory are...the system [8]. Chi-squared automatic interaction detection (CHAID) is an algorithm “to predict the response behaviour [sic] of individuals as...branches with the highest probability may require incentives to increase attrition. The branches could be defined by gender, career field, religion

  7. Attrition Cost Model Instruction Manual

    Science.gov (United States)

    Yanagiura, Takeshi

    2012-01-01

    This instruction manual explains in detail how to use the Attrition Cost Model program, which estimates the cost of student attrition for a state's higher education system. Programmed with SAS, this model allows users to instantly calculate the cost of attrition and the cumulative attrition rate that is based on the most recent retention and…

  8. High attrition among HIV-infected patients with advanced disease treated in an intermediary referral center in Maputo, Mozambique

    Directory of Open Access Journals (Sweden)

    Lucas Molfino

    2014-04-01

    Full Text Available Background: In Mozambique, antiretroviral therapy (ART scale-up has been successfully implemented. However, attrition in care remains a major programmatic challenge. In 2009, an intermediary-level HIV referral center was created in Maputo to ensure access to specialized care for HIV-infected patients with complications (advanced clinical-immunological stage, Kaposi sarcoma, or suspected ART failure. Objective: To determine the attrition from care and to identify risk factors that lead to high attrition among patients referred to an intermediary-level HIV referral center. Design: This was a retrospective cohort study from 2009 to 2011. Results: A total of 1,657 patients were enrolled, 847 (51% were men, the mean age was 36 years (standard deviation: 11, the mean CD4 count was 27 cells/µl (interquartile range: 11–44, and one-third were severely malnourished. The main reasons for referral were advanced clinical stages (WHO stages 3 and 4, and CD4 count <50 cells/µl in 70% of the cases, and 19% had Kaposi sarcoma. The overall attrition rate was 28.7 per 100 person-years (PYs – the mortality rate was 5.0 (95% confidence interval [CI]: 4.2–5.9 per 100 PYs, and the loss-to-follow-up rate was 23.7 (95% CI: 21.9–25.6 per 100 PYs. There were 793 attritions – 137 deaths and 656 lost to follow-up (LTFU; 77% of all attrition happened within the first year. The factors independently associated with attrition were male sex (adjusted hazard ratio [aHR]: 1.15, 95% CI: 1.0–1.3, low body mass index (aHR: 1.51, 95% CI: 1.2–1.8, WHO clinical stage 3 or 4 (aHR: 1.30, 95% CI: 1.0–1.6; and aHR: 1.91, 95% CI: 1.4–2.5, later year of enrollment (aHR 1.61, 95% CI 1.3–1.9, and ‘being already on ART’ at enrollment (aHR 13.71, 95% CI 11.4–16.4. Conclusions: Attrition rates among HIV-infected patients enrolled in an intermediary referral center were high, mainly related to advanced stage of clinical disease. Measures are required to address this

  9. An Exploration of Teacher Attrition and Mobility in High Poverty Racially Segregated Schools

    Science.gov (United States)

    Djonko-Moore, Cara M.

    2016-01-01

    The purpose of this study was to examine the mobility (movement to a new school) and attrition (quitting teaching) patterns of teachers in high poverty, racially segregated (HPRS) schools in the US. Using 2007-9 survey data from the National Center for Education Statistics, a multi-level multinomial logistic regression was performed to examine the…

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

    DEFF Research Database (Denmark)

    Linnet, Jakob; Pedersen, Anders Sune

    2014-01-01

    Attrition is a well known problem in psychotherapeutic treatment. Patients with addiction have high attrition rates, and it is therefore important to identify factors that can improve completion rates in addiction. Here, we investigated the influence of waiting time as a predictor of treatment...

  11. Texas Public School Attrition Study, 2011-12. IDRA Report

    Science.gov (United States)

    Johnson, Roy L.; Montes, Felix

    2012-01-01

    This document contains 3 statistical reports. The first report, "Attrition Rate Decline Seems Promising--Though High Schools are Still Losing One in Four Students" (by Roy L. Johnson), presents results of long-term trend assessments of attrition data in Texas public high schools. The second report, "Slow Declining Pace Keeps Zero…

  12. Limestone particle attrition and size distribution in a small circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Zhongxiang Chen; John R. Grace; C. Jim Lim [University of British Columbia, Vancouver, BC (Canada). Department of Chemical and Biological Engineering

    2008-06-15

    Limestone particle attrition was investigated in a small circulating fluidized bed reactor at temperatures from 25 to 850{sup o}C, 1 atm pressure and superficial gas velocities from 4.8 to 6.2 m/s. The effects of operating time, superficial gas velocity and temperature were studied with fresh limestone. No calcination or sulfation occurred at temperatures {le} 580{sup o}C, whereas calcination and sulfation affected attrition at 850{sup o}C. Increasing the temperature (while maintaining the same superficial gas velocity) reduced attrition if there was negligible calcination. Attrition was high initially, but after about 24 h, the rate of mass change became constant. The ratio of initial mean particle diameter to that at later times increased linearly with time and with (U{sub g} - U{sub mf}){sup 2}, while decreasing exponentially with temperature, with an activation energy for fresh limestone of -4.3 kJ/mol. The attrition followed Rittinger's surface theory. The change of surface area of limestone particles was proportional to the total excess kinetic energy consumed and to the total attrition time, whereas the change of surface area decreased exponentially with increasing temperature. At 850{sup o}C, the attrition rate of calcined lime was highest, whereas the attrition rate was lowest for sulfated particles. When online impact attrition was introduced, the attrition rate was about an order of magnitude higher than without impacts. 25 refs., 14 figs., 4 tabs.

  13. The Case for Increasing Workplace Decision-Making: Proposing a Model for Special Educator Attrition Research

    Science.gov (United States)

    Tyler, Teresa A.; Brunner, C. Cryss

    2014-01-01

    The chronically high rate of special educator attrition across U.S. schools creates a dilemma for educational leaders because special educators provide direct services to students with special needs. Attrition exacerbates already high special educator shortages reported in most districts, and nearly one million schoolchildren with disabilities…

  14. A review of trends in attrition rates for surgical faculty: a case for a sustainable retention strategy to cope with demographic and economic realities.

    Science.gov (United States)

    Satiani, Bhagwan; Williams, Thomas E; Brod, Heather; Way, David P; Ellison, E Christopher

    2013-05-01

    Our aim was to compare trends in retention of academic surgeons by reviewing surgical faculty attrition rates (leaving academic surgery for any reason) of 3 cohorts at 5-year intervals between 1996 and 2011. The Association of American Medical Colleges' Faculty Administrative Management On-Line User System database was queried for a retention report of all tenure/clinical track full-time MD faculty within our academic medical center on July 1, 1996 (group 1), July 1, 2001 (group 2), and July 1, 2006 (group 3). Retention was tracked for 5 years post snapshot. The individual 5-year cohort attrition rates (observed frequencies) were compared with combined attrition rates for all 3 groups (expected frequencies). Overall, attrition trends for groups 2 (lower) and 3 (higher) were significantly different than the trends for all groups combined. Minorities and professors at the full or associate rank in group 3 contributed to this difference. Faculty in group 3 leaving our academic medical center were significantly more likely to transition into nonacademic practice compared with the other 2 groups. Greater attrition in the last 5-year cohort, despite the increase in faculty positions, is worrisome. A continuous retention life cycle is critical if academic medical centers hope to compete for talent. Retention planning should include on-boarding programs for enculturation, monitoring of professional satisfaction, formalized mentoring of younger surgeons, retaining academic couples and a part-time workforce, leadership and talent management, exit interviews, and competitive financial packages. Copyright © 2013 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  15. Attrition of Dolomitic Lime in a Fluidized-Bed at High Temperature

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Šyc, Michal; Jeremiáš, Michal

    2013-01-01

    Roč. 67, č. 2 (2013), s. 164-172 ISSN 0366-6352 R&D Projects: GA AV ČR IAA400720701; GA MŠk(CZ) 7C11009 Grant - others:RFCS(XE) RFCR-CT-2010-00009 Institutional support: RVO:67985858 Keywords : attrition * catalytic gasification * dolomitic lime Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.193, year: 2013

  16. Understanding attrition from international Internet health interventions: a step towards global eHealth.

    Science.gov (United States)

    Geraghty, Adam W A; Torres, Leandro D; Leykin, Yan; Pérez-Stable, Eliseo J; Muñoz, Ricardo F

    2013-09-01

    Worldwide automated Internet health interventions have the potential to greatly reduce health disparities. High attrition from automated Internet interventions is ubiquitous, and presents a challenge in the evaluation of their effectiveness. Our objective was to evaluate variables hypothesized to be related to attrition, by modeling predictors of attrition in a secondary data analysis of two cohorts of an international, dual language (English and Spanish) Internet smoking cessation intervention. The two cohorts were identical except for the approach to follow-up (FU): one cohort employed only fully automated FU (n = 16 430), while the other cohort also used 'live' contact conditional upon initial non-response (n = 1000). Attrition rates were 48.1 and 10.8% for the automated FU and live FU cohorts, respectively. Significant attrition predictors in the automated FU cohort included higher levels of nicotine dependency, lower education, lower quitting confidence and receiving more contact emails. Participants' younger age was the sole predictor of attrition in the live FU cohort. While research on large-scale deployment of Internet interventions is at an early stage, this study demonstrates that differences in attrition from trials on this scale are (i) systematic and predictable and (ii) can largely be eliminated by live FU efforts. In fully automated trials, targeting the predictors we identify may reduce attrition, a necessary precursor to effective behavioral Internet interventions that can be accessed globally.

  17. The effects of experience and attrition for novice high-school science and mathematics teachers.

    Science.gov (United States)

    Henry, Gary T; Fortner, C Kevin; Bastian, Kevin C

    2012-03-02

    Because of the current high proportion of novice high-school teachers, many students' mastery of science and mathematics depends on the effectiveness of early-career teachers. In this study, which used value-added models to analyze high-school teachers' effectiveness in raising test scores on 1.05 million end-of-course exams, we found that the effectiveness of high-school science and mathematics teachers increased substantially with experience but exhibited diminishing rates of return by their fourth year; that teachers of algebra 1, algebra 2, biology, and physical science who continued to teach for at least 5 years were more effective as novice teachers than those who left the profession earlier; and that novice teachers of physics, chemistry, physical science, geometry, and biology exhibited steeper growth in effectiveness than did novice non-science, technology, engineering, and mathematics teachers.

  18. Association of General Surgery Resident Remediation and Program Director Attitudes With Resident Attrition.

    Science.gov (United States)

    Schwed, Alexander C; Lee, Steven L; Salcedo, Edgardo S; Reeves, Mark E; Inaba, Kenji; Sidwell, Richard A; Amersi, Farin; Are, Chandrakanth; Arnell, Tracey D; Damewood, Richard B; Dent, Daniel L; Donahue, Timothy; Gauvin, Jeffrey; Hartranft, Thomas; Jacobsen, Garth R; Jarman, Benjamin T; Melcher, Marc L; Mellinger, John D; Morris, Jon B; Nehler, Mark; Smith, Brian R; Wolfe, Mary; Kaji, Amy H; de Virgilio, Christian

    2017-12-01

    Previous studies of resident attrition have variably included preliminary residents and likely overestimated categorical resident attrition. Whether program director attitudes affect attrition has been unclear. To determine whether program director attitudes are associated with resident attrition and to measure the categorical resident attrition rate. This multicenter study surveyed 21 US program directors in general surgery about their opinions regarding resident education and attrition. Data on total resident complement, demographic information, and annual attrition were collected from the program directors for the study period of July 1, 2010, to June 30, 2015. The general surgery programs were chosen on the basis of their geographic location, previous collaboration with some coauthors, prior work in surgical education and research, or a program director willing to participate. Only categorical surgical residents were included in the study; thus, program directors were specifically instructed to exclude any preliminary residents in their responses. Five-year attrition rates (2010-2011 to 2014-2015 academic years) as well as first-time pass rates on the General Surgery Qualifying Examination and General Surgery Certifying Examination of the American Board of Surgery (ABS) were collected. High- and low-attrition programs were compared. The 21 programs represented different geographic locations and 12 university-based, 3 university-affiliated, and 6 independent program types. Programs had a median (interquartile range [IQR]) number of 30 (20-48) categorical residents, and few of those residents were women (median [IQR], 12 [5-17]). Overall, 85 of 966 residents (8.8%) left training during the study period: 15 (17.6%) left after postgraduate year 1, 34 (40.0%) after postgraduate year 2, and 36 (42.4%) after postgraduate year 3 or later. Forty-four residents (51.8%) left general surgery for another surgical discipline, 21 (24.7%) transferred to a different surgery

  19. Personal, Situational, and Organizational Determinants of Navy Enlisted Attrition

    Science.gov (United States)

    1980-06-01

    of regular high school instruction. The GED test battery contains five testsz writing skills, social studies, science, reading skills, and mathematics ...expanded apprentice train- ing program for airmen and seamen might, ceteris paribus, bring the GENDET attrition rate closer to acceptable lvels . 13 ] KN

  20. High population increase rates.

    Science.gov (United States)

    1991-09-01

    In addition to its economic and ethnic difficulties, the USSR faces several pressing demographic problems, including high population increase rates in several of its constituent republics. It has now become clear that although the country's rigid centralized planning succeeded in covering the basic needs of people, it did not lead to welfare growth. Since the 1970s, the Soviet economy has remained sluggish, which as led to increase in the death and birth rates. Furthermore, the ideology that held that demography could be entirely controlled by the country's political and economic system is contradicted by current Soviet reality, which shows that religion and ethnicity also play a significant role in demographic dynamics. Currently, Soviet republics fall under 2 categories--areas with high or low natural population increase rates. Republics with low rates consist of Christian populations (Armenia, Moldavia, Georgia, Byelorussia, Russia, Lithuania, Estonia, Latvia, Ukraine), while republics with high rates are Muslim (Tadzhikistan, Uzbekistan, Turkmenistan, Kirgizia, Azerbaijan Kazakhstan). The later group has natural increase rates as high as 3.3%. Although the USSR as a whole is not considered a developing country, the later group of republics fit the description of the UNFPA's priority list. Another serious demographic issue facing the USSR is its extremely high rate of abortion. This is especially true in the republics of low birth rates, where up to 60% of all pregnancies are terminated by induced abortions. Up to 1/5 of the USSR's annual health care budget is spent on clinical abortions -- money which could be better spent on the production of contraceptives. Along with the recent political and economic changes, the USSR is now eager to deal with its demographic problems.

  1. The Dissertation Story: What Is the Relationship between the Officer Candidate School Attrition Rate and Officer Training Command, Naval Service Training Command and Navy Recruiting Command Leadership Intervention?

    Science.gov (United States)

    2013-03-01

    attrition (Goodstadt, 1981). Kubisiak, et al. contend that leaders should consider attrition a negative occurrence and that each leader should develop...related to the information, and the consequences associated with the options. The ability to ruminate before acting when presented with new information or

  2. Development of an attrition risk prediction tool.

    Science.gov (United States)

    Fowler, John; Norrie, Peter

    To review lecturers' and students' perceptions of the factors that may lead to attrition from pre-registration nursing and midwifery programmes and to identify ways to reduce the impact of such factors on the student's experience. Comparable attrition rates for nursing and midwifery students across various universities are difficult to monitor accurately; however, estimates that there is approximately a 25% national attrition rate are not uncommon. The financial and human implications of this are significant and worthy of investigation. A study was carried out in one medium-sized UK school of nursing and midwifery, aimed at identifying perceived factors associated with attrition and retention. Thirty-five lecturers were interviewed individually; 605 students completed a questionnaire, and of these, 10 were individually interviewed. Attrition data kept by the student service department were reviewed. Data were collected over an 18-month period in 2007-2008. Regression analysis of the student data identified eight significant predictors. Four of these were 'positive' factors in that they aided student retention and four were 'negative' in that they were associated with students' thoughts of resigning. Student attrition and retention is multifactorial, and, as such, needs to be managed holistically. One aspect of this management could be an attrition risk prediction tool.

  3. Attrition of Tyee Formation Sandstone in a Natural Fluvial System

    Science.gov (United States)

    brandes, J. B.; Sanfilippo, J. D.; Lancaster, S. T.

    2013-12-01

    The data from this study will provide a rate of attrition with respect to change in volume, time and distance in a natural stream setting. Sandstone gravel attrition has been observed in previous studies with the use of rock tumblers, but measurements in natural systems are rare or absent. This study will use rocks with implanted passive integrated transponders (PIT) tags to track sediment movement. The study area is a natural mountain stream of approximately 4m width and 1m depth. This study is part of larger study of sediment transport. The rock volumes will be recorded prior to placement in an active channel using water displacement, the specific location along the channel will be recorded, and each tracer rock will be tracked using its individual radio frequency identification (RFID) number. Tracer rock deployment will occur before the annual high-water season. After one rainy season, the rocks will be located and removed from the stream using a radio frequency mobile radio frequency tracker. Their travel distances will be recorded and final volumes determined. Differences between initial and final volumes and travel distances will yield a distribution of attrition rates and, therefore, a mean gravel attrition rate.

  4. Regional Disparities in Apprentice Attrition Rates: Heat and Quarter Four's Significance in Northern Australia

    Science.gov (United States)

    Zoellner, Don; Brearley, Matt; Oppermann, Elspeth

    2017-01-01

    Apprenticeship completion rates have remained persistently low for decades in spite of broad agreement over the causes of non-completions. A possible factor missing from these explanations is climate, particularly in northern Australia where traditional trade apprentices are exposed to extreme conditions and exert themselves. We hypothesize that:…

  5. Navy Recruit Attrition Prediction Modeling

    Science.gov (United States)

    2014-09-01

    have high correlation with attrition, such as age, job characteristics, command climate, marital status, behavior issues prior to recruitment, and the...the additive model. glm(formula = Outcome ~ Age + Gender + Marital + AFQTCat + Pay + Ed + Dep, family = binomial, data = ltraining) Deviance ...0.1 ‘ ‘ 1 (Dispersion parameter for binomial family taken to be 1) Null deviance : 105441 on 85221 degrees of freedom Residual deviance

  6. Retention and Attrition Among African Americans in the STAR*D Study: What Causes Research Volunteers to Stay or Stray?

    Science.gov (United States)

    Murphy, Eleanor J; Kassem, Layla; Chemerinski, Anat; Rush, A. John; Laje, Gonzalo; McMahon, Francis J.

    2013-01-01

    Background High attrition rates among African-Americans (AA) volunteers are a persistent problem that makes clinical trials less representative and complicates estimation of treatment outcomes. Many studies contrast AA with other ethnic/racial groups, but few compare the AA volunteers who remain in treatment with those who leave. Here, in addition to comparing patterns of attrition between African Americans and whites, we identify predictors of overall and early attrition among African Americans. Method Sample comprised non-Hispanic African-American (n=673) and white (n=2,549) participants in the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study. Chi-square tests were used to examine racial group differences in reasons for exit. Multivariate logistic regression was used to examine predictors of overall attrition, early attrition (by Level 2) and top reasons cited for attrition among African Americans. Results For both African-American and white dropouts, non-compliance reasons for attrition were most commonly cited during the earlier phases of the study while reasons related to efficacy and medication side effects were cited later in the study. Satisfaction with treatment strongly predicted overall attrition among African Americans independent of socioeconomic, clinical, medical or psychosocial factors. Early attrition among African American dropouts was associated with less psychiatric comorbidity, and higher perceived physical functioning but greater severity of clinician-rated depression. Conclusions The decision to drop out is a dynamic process that changes over the course of a clinical trial. Strategies aimed at retaining African Americans in such trials should emphasize engagement with treatment and patient satisfaction immediately following enrollment and after treatment initiation. PMID:23723044

  7. Self-esteem and self-efficacy as predictors of attrition in associate degree nursing students.

    Science.gov (United States)

    Peterson-Graziose, Virginia; Bryer, Jennifer; Nikolaidou, Maria

    2013-06-01

    There is a serious and growing shortage of nurses in the United States, and the high rate of student attrition from nursing programs has further added to this problem. The challenge for schools of nursing is to recruit increased numbers of qualified candidates into their programs and to determine ways to decrease the rate of student attrition. The purpose of this study was to determine whether self-esteem, self-efficacy, and life stressors were significantly related to student attrition in first-semester associate degree nursing students. A descriptive correlational design and nonprobability convenience sample of first-semester associate degree nursing students was used. Data were gathered using the Rosenberg Self-Esteem Scale, the General Self-Efficacy Scale, and the Holmes and Rahe Social Readjustment Rating Scale. Findings indicated that self-esteem was significantly associated with student attrition. Results from this study provide the basis for targeted interventions designed to decrease student attrition rates in associate degree nursing programs. Copyright 2013, SLACK Incorporated.

  8. Issues concerning recruitment, retention and attrition of student nurses in the 1950/60s: a comparative study.

    Science.gov (United States)

    Jinks, Annette M; Richardson, Kathleen; Jones, Chris; Kirton, Jennifer A

    2014-11-01

    To investigate student nurse recruitment and attrition in the 1950' and 1960s and undertake comparisons to modern day concerns. The study was set in one hospital in the U.K. In the period studied nursing was unpopular as a profession and there were difficulties surrounding recruitment. Attrition rates were high. Documentary analysis of 641 training records dating 1955 to 1968 was undertaken. Attrition rates, reasons for non-completion and employment following successful completion were determined. Most recruits were young, unmarried, females and had overseas addresses. The majority (n = 88) had prior nursing experience. Over 69% (n = 443) successfully completed their training. Attrition rates were over 30% (n = 198), the main reason being academic failure. Following completion over 40% (n = 183) undertook midwifery training (n = 183) or secured a staff nurse post (n = 153). Issues relating to recruitment, retention and attrition in the 1950s and 1960s put into context present day issues. Recent attrition rates from pre-registration nurse education have fallen, nevertheless some of the issues of yesteryear remain problematic. In the present study significant numbers of entrants left due to domestic and ill-health problems resonates with many modern day studies. Also failure to complete due to academic shortcomings continues to be a concern. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Study of Navy Enlisted Attrition: Race, Ethnicity, and Type of Occupation

    National Research Council Canada - National Science Library

    Carroll, James M

    2008-01-01

    The primary objective of this study is to gain a better understanding of Navy first-term enlisted attrition among racial/ethnic minorities by comparing attrition rates in technical and nontechnical occupations...

  10. Examining the Relationship Between Mental, Physical, and Organizational Factors Associated With Attrition During Maritime Forces Training.

    Science.gov (United States)

    Binsch, Olaf; Banko, Katherine M; Veenstra, Bertil J; Valk, Pierre J L

    2015-11-01

    For infantry units of the Dutch Ministry of Defence, high attrition rates (varying from 42 to 68%) during initial training are a persisting problem. The reasons for this attrition are diverse. Having better insight into the causes of attrition is a prerequisite for implementing preventive measures. To achieve this, a monitoring assessment system was developed that integrated the effects of physical, mental, and organizational determinants on operational readiness. The aim of this study was to implement the monitoring tools and to establish the set of determinants that best predicted attrition during infantry training of new recruits. Eighty-five recruits were monitored over a 24-week infantry training course. Before the training, recruits were screened for medical, psychological, and physical wellness. During the monitoring phase, mental, physiological, and organizational indicants were obtained using an array of tools such as questionnaires, chest belt monitors (for heart rate, acceleration, and skin temperature measurements), and computerized tests (e.g., vigilance, long-term memory). Survival analyses were used to tease out the determinants of individual and grouped predictors of attrition. Nearly half the recruits (47%) failed the training. Attrition was predicted by both physiological and mental determinants. However, the organizational determinant "trainers' judgment" on the "recruits' military quality" dominated the physiological and mental determinants. It was concluded that the monitoring system was successfully implemented during infantry training, and that the survival analysis method emphasized on single effects and interactions between the different determinants. Based on the current findings, we recommend several steps to successfully implement a monitoring method in settings with high demands.

  11. High Rate Digital Demodulator ASIC

    Science.gov (United States)

    Ghuman, Parminder; Sheikh, Salman; Koubek, Steve; Hoy, Scott; Gray, Andrew

    1998-01-01

    The architecture of High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation in other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA's Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an over-view of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

  12. Limestone fragmentation and attrition during fluidized bed oxyfiring

    Energy Technology Data Exchange (ETDEWEB)

    Fabrizio Scala; Piero Salatino [Istituto di Ricerche sulla Combustione - CNR, Napoli (Italy)

    2010-04-15

    Attrition/fragmentation of limestone under simulated fluidized bed oxyfiring conditions was investigated by means of an experimental protocol that had been previously developed for characterization of attrition/fragmentation of sorbents in air-blown atmospheric fluidized bed combustors. The protocol was based on the use of different and mutually complementary techniques. The extent and pattern of attrition by surface wear in the dense phase of a fluidized bed were assessed in experiments carried out with a bench scale fluidized bed combustor under simulated oxyfiring conditions. Sorbent samples generated during simulated oxyfiring tests were further characterized from the standpoint of fragmentation upon high velocity impact by means of a purposely designed particle impactor. Results showed that under calcination-hindered conditions attrition and fragmentation patterns are much different from those occurring under air-blown atmospheric combustion conditions. Noteworthy, attrition/fragmentation enhanced particle sulfation by continuously regenerating the exposed particle surface. 13 refs., 8 figs.

  13. Language Attrition: The Fate of the Start.

    Science.gov (United States)

    Hansen, Lynne

    2001-01-01

    Reviews the literature on psycholinguistic aspects of language attrition over the past half decade. Discusses evidence from studies on hesitation phenomena in attriter speech, variables affecting language attrition, and relearning. (Author/VWL)

  14. Factors Associated with Veterinary Clinical Faculty Attrition.

    Science.gov (United States)

    Furr, Martin

    Faculty attrition and recruitment for veterinary clinical faculty positions have been reported as significant problems in veterinary medical education. To investigate the factors that may be important in veterinary clinical faculty retention, the perceptions and views of veterinary clinical academic faculty were determined using a web-distributed electronic survey. Responses were dichotomized by whether the respondent had or had not left an academic position and were analyzed for their association with faculty attrition. A total of 1,226 responses were recorded, and results demonstrated that factors other than compensation were associated with veterinary clinical faculty attrition, including departmental culture, work-life balance, and recognition and support of clinical medicine by the administration. Forty-four percent of respondents who had held a faculty appointment reported leaving academia either voluntarily or for non-voluntary reasons such as failure to achieve tenure, retirement, or having their position closed. Attention to correcting deficiencies in workplace culture and professional rewards could be a beneficial means by which to decrease the faculty attrition rates currently observed in clinical academic veterinary medicine.

  15. Factors affecting attrition from associate degree nursing programs in North Carolina.

    Science.gov (United States)

    Fraher, Erin; Belsky, Daniel W; Gaul, Katie; Carpenter, Jessica

    2010-01-01

    Projected nursing shortfalls have spurred the state of North Carolina to initiate a series of strategies to increase the number of graduates from pre-licensure Registered Nurse (RN) programs. These efforts have been largely successful, but attrition rates from Associate Degree Nursing (ADN) programs remain high. Only 58% of students entering ADN programs complete the degree. While policy makers are keenly aware that attrition from ADN programs is problematic, there is a lack of empirical evidence to identify the specific factors contributing to student attrition. In late 2007, the North Carolina Community College System (NCCCS) asked the Cecil G. Sheps Center for Health Services Research to conduct a study of Associate Degree Nursing program attrition and its causes. This paper summarizes the findings from that study and identifies the student- and program-level characteristics associated with more and less successful ADN programs. While this study was conducted in a single state in the US, the substantive findings--as well as the methodological approach--may be useful to other states and other countries. The study revealed that socioeconomically disadvantaged students (those with GEDs and those who received Pell Grants), non-white students, and younger and older students were less likely to graduate on-time. When programs were grouped into high and low performance categories on the basis of risk adjusted graduation rates, high performing programs were distinguished by more stringent admissions policies and better educated faculties. Nursing shortages have garnered significant attention and resources from state and national workforce planners in recent years. But to date, investments in expanding program capacity have not been matched by attention to program completion rates, with the result that we have enlarged the pipeline without fixing the leaks. Faculty shortages and recession-induced resource constraints limit further program expansion. Addressing attrition

  16. Military Personnel Attrition and Retention: Research in Progress

    Science.gov (United States)

    1981-10-01

    NATIONAL ANALYSES OF ATTRITION 13 H. Wallace Sinaiko and Kenneth C. Scheflen AIR FORCE ATTRITION RESEARCH: ANALISIS OF PRE- AND POST- 15 ENLISTMENT FACTORS...are specific types ot codes used, to icdentity categories of reenlistments, extensions, and losses. These SPD codes will be clustered in various ways...two enlistment terms in the Navy. The Navy’s 110 ratings were grouped into 24 occupational tields which represented clusters of similar skills, similar

  17. Workshop on Language Student Attrition

    National Research Council Canada - National Science Library

    Whelan, Bree

    2001-01-01

    Seventy individuals from Government agencies (military and civilian), academia, and contractor organizations attended all or parts of a Workshop on student Attrition held at the Defense Language Institute Foreign Language Center (DLIFLC...

  18. Web-Based Alcohol Intervention: Study of Systematic Attrition of Heavy Drinkers.

    Science.gov (United States)

    Radtke, Theda; Ostergaard, Mathias; Cooke, Richard; Scholz, Urte

    2017-06-28

    Web-based alcohol interventions are a promising way to reduce alcohol consumption because of their anonymity and the possibility of reaching a high numbers of individuals including heavy drinkers. However, Web-based interventions are often characterized by high rates of attrition. To date, very few studies have investigated whether individuals with higher alcohol consumption show higher attrition rates in Web-based alcohol interventions as compared with individuals with lower alcohol consumption. The aim of this study was to examine the attrition rate and predictors of attrition in a Web-based intervention study on alcohol consumption. The analysis of the predictors of attrition rate was performed on data collected in a Web-based randomized control trial. Data collection took place at the University of Konstanz, Germany. A total of 898 people, which consisted of 46.8% males (420/898) and 53.2% females (478/898) with a mean age of 23.57 years (SD 5.19), initially volunteered to participate in a Web-based intervention study to reduce alcohol consumption. Out of the sample, 86.9% (781/898) were students. Participants were classified as non-completers (439/898, 48.9%) if they did not complete the Web-based intervention. Potential predictors of attrition were self-reported: alcohol consumption in the last seven days, per week, from Monday to Thursday, on weekends, excessive drinking behavior measured with the Alcohol Use Disorder Identification Test (AUDIT), and drinking motives measured by the Drinking Motive Questionnaire (DMQ-R SF). Significant differences between completers and non-completers emerged regarding alcohol consumption in the last seven days (B=-.02, P=.05, 95% CI [0.97-1.00]), on weekends (B=-.05, P=.003, 95% CI [0.92-0.98]), the AUDIT (B=-.06, P=.007, 95% CI [0.90-0.98], and the status as a student (B=.72, P=.001, 95% CI [1.35-3.11]). Most importantly, non-completers had a significantly higher alcohol consumption compared with completers. Hazardous

  19. Predictors of early faculty attrition at one Academic Medical Center.

    Science.gov (United States)

    Bucklin, Brenda A; Valley, Morgan; Welch, Cheryl; Tran, Zung Vu; Lowenstein, Steven R

    2014-02-10

    Faculty turnover threatens the research, teaching and clinical missions of medical schools. We measured early attrition among newly-hired medical school faculty and identified personal and institutional factors associated with early attrition. This retrospective cohort study identified faculty hired during the 2005-2006 academic year at one school. Three-year attrition rates were measured. A 40-question electronic survey measured demographics, career satisfaction, faculty responsibilities, institutional/departmental support, and reasons for resignation. Odds ratios (ORs) and 95 percent confidence intervals (95% CI) identified variables associated with early attrition. Of 139 faculty, 34% (95% CI = 26-42%) resigned within three years of hire. Attrition was associated with: perceived failure of the Department Chair to foster a climate of teaching, research, and service (OR = 6.03; 95% CI: 1.84, 19.69), inclusiveness, respect, and open communication (OR = 3.21; 95% CI: 1.04, 9.98). Lack of professional development of the faculty member (OR = 3.84; 95% CI: 1.25, 11.81); institutional recognition and support for excellence in teaching (OR = 2.96; 95% CI: 0.78, 11.19) and clinical care (OR = 3.87; 95% CI: 1.04, 14.41); and >50% of professional time devoted to patient care (OR = 3.93; 95% CI: 1.29, 11.93) predicted attrition. Gender, race, ethnicity, academic degree, department type and tenure status did not predict early attrition. Of still-active faculty, an additional 27 (48.2%, 95% CI: 35.8, 61.0) reported considering resignation within the 5 years. In this pilot study, one-third of new faculty resigned within 3 years of hire. Greater awareness of predictors of early attrition may help schools identify threats to faculty career satisfaction and retention.

  20. ART Attrition across Health Facilities Implementing Option B+ in Haiti.

    Science.gov (United States)

    Myrtil, Martine Pamphile; Puttkammer, Nancy; Gloyd, Stephen; Robinson, Julia; Yuhas, Krista; Domercant, Jean Wysler; Honoré, Jean Guy; Francois, Kesner

    2018-01-01

    Describing factors related to high attrition is important in order to improve the implementation of the Option B+ strategy in Haiti. We conducted a retrospective cohort study to describe the variability of antiretroviral therapy (ART) retention across health facilities among pregnant and lactating women and assess for differences in ART retention between Option B+ clients and other ART patients. There were 1989 Option B+ clients who initiated ART in 45 health facilities. The percentage of attrition varied from 9% to 81% across the facilities. The largest health facilities had 38% higher risk of attrition (relative risk [RR]: 1.38, 95% confidence interval [CI]: 1.08-1.77, P = .009). Private institutions had 18% less risk of attrition (RR: 0.82, 95% CI: 0.70-0.96, P = .020). Health facilities located in the West department and the South region had lower risk of attrition. Being on treatment in a large or public health facility or a facility located in the North region was a significant risk factor associated with high attrition among Option B+ clients. The implementation of the Option B+ strategy must be reevaluated in order to effectively eliminate mother-to-child HIV transmission.

  1. The nature and causes of attrition in the British Household Panel Study

    OpenAIRE

    Uhrig, S.C. Noah

    2008-01-01

    Panel attrition is a process producing data absent from panel records due to survey non-participation or other data unavailability. I examine the nature and causes of attrition resulting from non-contact and survey refusal in the British Household Panel Study. Focusing on non-response transitions amongst Wave 1 respondents using discrete time transition models, I locate attrition at first non-response over the first 14 waves. Physical impediments to contact, less time spent at home and high l...

  2. Medical school attrition-beyond the statistics a ten year retrospective study.

    Science.gov (United States)

    Maher, Bridget M; Hynes, Helen; Sweeney, Catherine; Khashan, Ali S; O'Rourke, Margaret; Doran, Kieran; Harris, Anne; Flynn, Siun O'

    2013-01-31

    Medical school attrition is important--securing a place in medical school is difficult and a high attrition rate can affect the academic reputation of a medical school and staff morale. More important, however, are the personal consequences of dropout for the student. The aims of our study were to examine factors associated with attrition over a ten-year period (2001-2011) and to study the personal effects of dropout on individual students. The study included quantitative analysis of completed cohorts and qualitative analysis of ten-year data. Data were collected from individual student files, examination and admission records, exit interviews and staff interviews. Statistical analysis was carried out on five successive completed cohorts. Qualitative data from student files was transcribed and independently analysed by three authors. Data was coded and categorized and key themes were identified. Overall attrition rate was 5.7% (45/779) in 6 completed cohorts when students who transferred to other medical courses were excluded. Students from Kuwait and United Arab Emirates had the highest dropout rate (RR = 5.70, 95% Confidence Intervals 2.65 to 12.27;p psychological morbidity in 40% (higher than other studies). Qualitative analysis revealed recurrent themes of isolation, failure, and despair. Student Welfare services were only accessed by one-third of dropout students. While dropout is often multifactorial, certain red flag signals may alert us to risk of dropout including non-EU origin, academic struggling, absenteeism, social isolation, depression and leave of absence. Psychological morbidity amongst dropout students is high and Student Welfare services should be actively promoted. Absenteeism should prompt early intervention. Behind every dropout statistic lies a personal story. All medical schools have a duty of care to support students who leave the medical programme.

  3. Medical School Attrition-Beyond the Statistics A Ten Year Retrospective Study

    Directory of Open Access Journals (Sweden)

    Maher Bridget M

    2013-01-01

    Full Text Available Abstract Background Medical school attrition is important - securing a place in medical school is difficult and a high attrition rate can affect the academic reputation of a medical school and staff morale. More important, however, are the personal consequences of dropout for the student. The aims of our study were to examine factors associated with attrition over a ten-year period (2001–2011 and to study the personal effects of dropout on individual students. Methods The study included quantitative analysis of completed cohorts and qualitative analysis of ten-year data. Data were collected from individual student files, examination and admission records, exit interviews and staff interviews. Statistical analysis was carried out on five successive completed cohorts. Qualitative data from student files was transcribed and independently analysed by three authors. Data was coded and categorized and key themes were identified. Results Overall attrition rate was 5.7% (45/779 in 6 completed cohorts when students who transferred to other medical courses were excluded. Students from Kuwait and United Arab Emirates had the highest dropout rate (RR = 5.70, 95% Confidence Intervals 2.65 to 12.27;p  Absenteeism was documented in 30% of students, academic difficulty in 55.7%, social isolation in 20%, and psychological morbidity in 40% (higher than other studies. Qualitative analysis revealed recurrent themes of isolation, failure, and despair. Student Welfare services were only accessed by one-third of dropout students. Conclusions While dropout is often multifactorial, certain red flag signals may alert us to risk of dropout including non-EU origin, academic struggling, absenteeism, social isolation, depression and leave of absence. Psychological morbidity amongst dropout students is high and Student Welfare services should be actively promoted. Absenteeism should prompt early intervention. Behind every dropout statistic lies a personal story. All

  4. Factors Influencing Students' Attrition at Sultan Qaboos University (SQU)

    Science.gov (United States)

    Al Ghanboosi, Salim Saleen

    2013-01-01

    The students' attrition rates among students enrolled at SQU ranged between 6.8% (1998), 7.8% (1999), and 7.9% (2000). However, the drop-out rate at the Sultan Qaboos University is increasing gradually, and this increase represents a problem for the university that provides free education and financial aid for all male students coming from areas…

  5. A systematic review of satisfaction and pediatric obesity treatment: new avenues for addressing attrition.

    Science.gov (United States)

    Skelton, Joseph A; Irby, Megan Bennett; Geiger, Ann M

    2014-01-01

    Pediatric obesity treatment programs report high attrition rates, but it is unknown if family experience and satisfaction contributes. This review surveys the literature regarding satisfaction in pediatric obesity and questions used in measurement. A systematic review of the literature was conducted using Medline, PsychINFO, and CINAHL. Studies of satisfaction in pediatric weight management were reviewed, and related studies of obesity were included. Satisfaction survey questions were obtained from the articles or from the authors. Eighteen studies were included; 14 quantitative and 4 qualitative. Only one study linked satisfaction to attrition, and none investigated the association of satisfaction and weight outcomes. Most investigations included satisfaction as a secondary aim or used single-item questions of overall satisfaction; only one assessed satisfaction in noncompleters. Overall, participants expressed high levels of satisfaction with obesity treatment or prevention programs. Surveys focused predominantly on overall satisfaction or specific components of the program. Few in-depth studies of satisfaction with pediatric obesity treatment have been conducted. Increased focus on family satisfaction with obesity treatment may provide an avenue to lower attrition rates and improve outcomes. Enhancing measurement of satisfaction to yield actionable responses could positively influence outcomes, and a framework, via patient-centered care principles, is provided. © 2013 National Association for Healthcare Quality.

  6. Causes of Teacher Attrition of First, Second, and Third Year Teachers in Rural Middle Schools

    Science.gov (United States)

    Thompson, Arkeco Lashay Lewis

    2012-01-01

    Early attrition from teaching bears enormous costs. High attrition means that schools must take funds urgently needed for school improvements and spend them instead in a manner that produces little long-term payoff for student learning (Kain & Singleton, 1996). Keeping highly qualified teachers should always be at the top of the priority list…

  7. Attrition of undergraduate nursing students at selected South African universities

    Directory of Open Access Journals (Sweden)

    Erna Roos

    2016-08-01

    Full Text Available Background: The nursing profession forms the backbone of many healthcare systems. It therefore needs a consistent supply of registered nurses to deliver continuous and safe quality healthcare, and to replace the nurses leaving or retiring from the profession. Attrition actively occurs among nursing students in South Africa and threatens the future supply of registered nurses. Aim: The aim of the study was to describe the attrition rate at selected South African universities and the factors influencing undergraduate nursing students to discontinue their nursing studies at these universities. Method: A quantitative descriptive design was followed. Heads of the nursing departments at the selected universities captured data with a specifically designed questionnaire. Thereafter their former nursing students provided information via a structured telephonic interview on the reasons why they discontinued the nursing programme. Results: The study revealed that attrition of undergraduate nursing students for three intake years (2007, 2008 and 2009 at the participating universities was between 39.3% and 58.7%. Academic and financial reasons as well as poor wellness and health were the main causes for attrition. Another factor was failure to cope with the demands of the clinical environment. Conclusion: Attrition might not occur immediately when a nursing student is challenged, as the student might exploit the various types of support offered. Although some nursing students do benefit from the offered support, a large number of nursing students still discontinue the undergraduate nursing programme.

  8. Increased prevalence of pregnancy and comparative risk of program attrition among individuals starting HIV treatment in East Africa.

    Directory of Open Access Journals (Sweden)

    Charles B Holmes

    Full Text Available The World Health Organization now recommends initiating all pregnant women on life-long antiretroviral therapy (ART, yet there is limited information about the characteristics and program outcomes of pregnant women already on ART in Africa. Our hypothesis was that pregnant women comprised an increasing proportion of those starting ART, and that sub-groups of these women were at higher risk for program attrition.We used the International Epidemiology Databases to Evaluate AIDS- East Africa (IeDEA-EA to conduct a retrospective cohort study including HIV care and treatment programs in Kenya, Uganda, and Tanzania. The cohort consecutively included HIV-infected individuals 13 years or older starting ART 2004-2014. We examined trends over time in the proportion pregnant, their characteristics and program attrition rates compared to others initiating and already receiving ART. 156,474 HIV-infected individuals (67.0% women started ART. The proportion of individuals starting ART who were pregnant women rose from 5.3% in 2004 to 12.2% in 2014. Mean CD4 cell counts at ART initiation, weighted for annual program size, increased from 2004 to 2014, led by non-pregnant women (annual increase 20 cells/mm3 and men (17 cells/mm3 annually, with lower rates of change in pregnant women (10 cells/mm3 per year (p<0.0001. There was no significant difference in the cumulative incidence of program attrition at 6 months among pregnant women starting ART and non-pregnant women. However, healthy pregnant women starting ART (WHO stage 1/2 had a higher rate of attrition rate (9.6%, compared with healthy non-pregnant women (6.5%; in contrast among women with WHO stage 3/4 disease, pregnant women had lower attrition (8.4% than non-pregnant women (14.4%. Among women who initiated ART when healthy and remained in care for six months, subsequent six-month attrition was slightly higher among pregnant women at ART start (3.5% compared to those who were not pregnant (2.4%, (absolute

  9. Increased prevalence of pregnancy and comparative risk of program attrition among individuals starting HIV treatment in East Africa.

    Science.gov (United States)

    Holmes, Charles B; Yiannoutsos, Constantin T; Elul, Batya; Bukusi, Elizabeth; Ssali, John; Kambugu, Andrew; Musick, Beverly S; Cohen, Craig; Williams, Carolyn; Diero, Lameck; Padian, Nancy; Wools-Kaloustian, Kara K

    2018-01-01

    The World Health Organization now recommends initiating all pregnant women on life-long antiretroviral therapy (ART), yet there is limited information about the characteristics and program outcomes of pregnant women already on ART in Africa. Our hypothesis was that pregnant women comprised an increasing proportion of those starting ART, and that sub-groups of these women were at higher risk for program attrition. We used the International Epidemiology Databases to Evaluate AIDS- East Africa (IeDEA-EA) to conduct a retrospective cohort study including HIV care and treatment programs in Kenya, Uganda, and Tanzania. The cohort consecutively included HIV-infected individuals 13 years or older starting ART 2004-2014. We examined trends over time in the proportion pregnant, their characteristics and program attrition rates compared to others initiating and already receiving ART. 156,474 HIV-infected individuals (67.0% women) started ART. The proportion of individuals starting ART who were pregnant women rose from 5.3% in 2004 to 12.2% in 2014. Mean CD4 cell counts at ART initiation, weighted for annual program size, increased from 2004 to 2014, led by non-pregnant women (annual increase 20 cells/mm3) and men (17 cells/mm3 annually), with lower rates of change in pregnant women (10 cells/mm3 per year) (p<0.0001). There was no significant difference in the cumulative incidence of program attrition at 6 months among pregnant women starting ART and non-pregnant women. However, healthy pregnant women starting ART (WHO stage 1/2) had a higher rate of attrition rate (9.6%), compared with healthy non-pregnant women (6.5%); in contrast among women with WHO stage 3/4 disease, pregnant women had lower attrition (8.4%) than non-pregnant women (14.4%). Among women who initiated ART when healthy and remained in care for six months, subsequent six-month attrition was slightly higher among pregnant women at ART start (3.5%) compared to those who were not pregnant (2.4%), (absolute

  10. Attrition from surgical residency training: perspectives from those who left.

    Science.gov (United States)

    Bongiovanni, Tasce; Yeo, Heather; Sosa, Julie A; Yoo, Peter S; Long, Theodore; Rosenthal, Marjorie; Berg, David; Curry, Leslie; Nunez-Smith, Marcella

    2015-10-01

    High rates of attrition from general surgery residency may threaten the surgical workforce. We sought to gain further insight regarding resident motivations for leaving general surgery residency. We conducted in-depth interviews to generate rich narrative data that explored individual experiences. An interdisciplinary team used the constant comparative method to analyze the data. Four themes characterized experiences of our 19 interviewees who left their residency program. Participants (1) felt an informal contract was breached when clinical duties were prioritized over education, (2) characterized a culture in which there was no safe space to share personal and programmatic concerns, (3) expressed a scarcity of role models who demonstrated better work-life balance, and (4) reported negative interactions with authority resulting in a profound loss of commitment. As general surgery graduate education continues to evolve, our findings may inform interventions and policies regarding programmatic changes to boost retention in surgical residency. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Retention and risk factors for attrition in a large public health ART program in Myanmar: a retrospective cohort analysis.

    Directory of Open Access Journals (Sweden)

    Aye Thida

    Full Text Available BACKGROUND: The outcomes from an antiretroviral treatment (ART program within the public sector in Myanmar have not been reported. This study documents retention and the risk factors for attrition in a large ART public health program in Myanmar. METHODS: A retrospective analysis of a cohort of adult patients enrolled in the Integrated HIV Care (IHC Program between June 2005 and October 2011 and followed up until April 2012 is presented. The primary outcome was attrition (death or loss-follow up; a total of 10,223 patients were included in the 5-year cumulative survival analysis. Overall 5,718 patients were analyzed for the risk factors for attrition using both logistic regression and flexible parametric survival models. RESULT: The mean age was 36 years, 61% of patients were male, and the median follow up was 13.7 months. Overall 8,564 (84% patients were retained in ART program: 750 (7% were lost to follow-up and 909 (9% died. During the 3 years follow-up, 1,542 attritions occurred over 17,524 person years at risk, giving an incidence density of 8.8% per year. The retention rates of participants at 12, 24, 36, 48 and 60 months were 86, 82, 80, 77 and 74% respectively. In multivariate analysis, being male, having high WHO staging, a low CD4 count, being anaemic or having low BMI at baseline were independent risk factors for attrition; tuberculosis (TB treatment at ART initiation, a prior ART course before program enrollment and literacy were predictors for retention in the program. CONCLUSION: High retention rate of IHC program was documented within the public sector in Myanmar. Early diagnosis of HIV, nutritional support, proper investigation and treatment for patients with low CD4 counts and for those presenting with anaemia are crucial issues towards improvement of HIV program outcomes in resource-limited settings.

  12. Retention and risk factors for attrition in a large public health ART program in Myanmar: a retrospective cohort analysis.

    Science.gov (United States)

    Thida, Aye; Tun, Sai Thein Than; Zaw, Sai Ko Ko; Lover, Andrew A; Cavailler, Philippe; Chunn, Jennifer; Aye, Mar Mar; Par, Par; Naing, Kyaw Win; Zan, Kaung Nyunt; Shwe, Myint; Kyaw, Thar Tun; Waing, Zaw Htoon; Clevenbergh, Philippe

    2014-01-01

    The outcomes from an antiretroviral treatment (ART) program within the public sector in Myanmar have not been reported. This study documents retention and the risk factors for attrition in a large ART public health program in Myanmar. A retrospective analysis of a cohort of adult patients enrolled in the Integrated HIV Care (IHC) Program between June 2005 and October 2011 and followed up until April 2012 is presented. The primary outcome was attrition (death or loss-follow up); a total of 10,223 patients were included in the 5-year cumulative survival analysis. Overall 5,718 patients were analyzed for the risk factors for attrition using both logistic regression and flexible parametric survival models. The mean age was 36 years, 61% of patients were male, and the median follow up was 13.7 months. Overall 8,564 (84%) patients were retained in ART program: 750 (7%) were lost to follow-up and 909 (9%) died. During the 3 years follow-up, 1,542 attritions occurred over 17,524 person years at risk, giving an incidence density of 8.8% per year. The retention rates of participants at 12, 24, 36, 48 and 60 months were 86, 82, 80, 77 and 74% respectively. In multivariate analysis, being male, having high WHO staging, a low CD4 count, being anaemic or having low BMI at baseline were independent risk factors for attrition; tuberculosis (TB) treatment at ART initiation, a prior ART course before program enrollment and literacy were predictors for retention in the program. High retention rate of IHC program was documented within the public sector in Myanmar. Early diagnosis of HIV, nutritional support, proper investigation and treatment for patients with low CD4 counts and for those presenting with anaemia are crucial issues towards improvement of HIV program outcomes in resource-limited settings.

  13. Attrition during graduate medical education: medical school perspective.

    Science.gov (United States)

    Andriole, Dorothy A; Jeffe, Donna B; Hageman, Heather L; Klingensmith, Mary E; McAlister, Rebecca P; Whelan, Alison J

    2008-12-01

    To identify predictors of attrition during graduate medical education (GME) in a single medical school cohort of contemporary US medical school graduates. Retrospective cohort study. Single medical institution. Recent US allopathic medical school graduates. Attrition from initial GME program. Forty-seven of 795 graduates (6%) did not complete the GME in their initial specialty of choice. At bivariate analysis, attrition was associated with election to the Alpha Omega Alpha Honor Medical Society, being an MD-PhD degree holder, and specialty choice (all P PhD degree holder (odds ratio, 3.43; 95% confidence interval, 1.27-9.26; P = .02), election to Alpha Omega Alpha (2.19; 1.04-4.66; P = .04), choice of general surgery for GME (5.32; 1.98-14.27; P < .001), and choice of 5-year surgical specialty including those surgical specialties with a GME training requirement of 5 years or longer (2.74; 1.16-6.44; P = .02) each independently predicted greater likelihood of attrition. Academically highly qualified graduates and graduates who chose training in general surgery or in a 5-year surgical specialty were at increased risk of attrition during GME.

  14. Understanding High Rate Behavior Through Low Rate Analog

    Science.gov (United States)

    2014-04-28

    challenges in high rate character- isation of polymers. The most important is that, owing to their low stress wavespeed, the structural response of...box’ tool, to provide supporting date for the rate dependent mechanical character- isation . Experiments were performed on a TA instruments Q800

  15. High burn rate solid composite propellants

    Science.gov (United States)

    Manship, Timothy D.

    High burn rate propellants help maintain high levels of thrust without requiring complex, high surface area grain geometries. Utilizing high burn rate propellants allows for simplified grain geometries that not only make production of the grains easier, but the simplified grains tend to have better mechanical strength, which is important in missiles undergoing high-g accelerations. Additionally, high burn rate propellants allow for a higher volumetric loading which reduces the overall missile's size and weight. The purpose of this study is to present methods of achieving a high burn rate propellant and to develop a composite propellant formulation that burns at 1.5 inches per second at 1000 psia. In this study, several means of achieving a high burn rate propellant were presented. In addition, several candidate approaches were evaluated using the Kepner-Tregoe method with hydroxyl terminated polybutadiene (HTPB)-based propellants using burn rate modifiers and dicyclopentadiene (DCPD)-based propellants being selected for further evaluation. Propellants with varying levels of nano-aluminum, nano-iron oxide, FeBTA, and overall solids loading were produced using the HTPB binder and evaluated in order to determine the effect the various ingredients have on the burn rate and to find a formulation that provides the burn rate desired. Experiments were conducted to compare the burn rates of propellants using the binders HTPB and DCPD. The DCPD formulation matched that of the baseline HTPB mix. Finally, GAP-plasticized DCPD gumstock dogbones were attempted to be made for mechanical evaluation. Results from the study show that nano-additives have a substantial effect on propellant burn rate with nano-iron oxide having the largest influence. Of the formulations tested, the highest burn rate was a 84% solids loading mix using nano-aluminum nano-iron oxide, and ammonium perchlorate in a 3:1(20 micron: 200 micron) ratio which achieved a burn rate of 1.2 inches per second at 1000

  16. Attrition from Web-Based Cognitive Testing: A Repeated Measures Comparison of Gamification Techniques.

    Science.gov (United States)

    Lumsden, Jim; Skinner, Andy; Coyle, David; Lawrence, Natalia; Munafo, Marcus

    2017-11-22

    The prospect of assessing cognition longitudinally and remotely is attractive to researchers, health practitioners, and pharmaceutical companies alike. However, such repeated testing regimes place a considerable burden on participants, and with cognitive tasks typically being regarded as effortful and unengaging, these studies may experience high levels of participant attrition. One potential solution is to gamify these tasks to make them more engaging: increasing participant willingness to take part and reducing attrition. However, such an approach must balance task validity with the introduction of entertaining gamelike elements. This study aims to investigate the effects of gamelike features on participant attrition using a between-subjects, longitudinal Web-based testing study. We used three variants of a common cognitive task, the Stop Signal Task (SST), with a single gamelike feature in each: one variant where points were rewarded for performing optimally; another where the task was given a graphical theme; and a third variant, which was a standard SST and served as a control condition. Participants completed four compulsory test sessions over 4 consecutive days before entering a 6-day voluntary testing period where they faced a daily decision to either drop out or continue taking part. Participants were paid for each session they completed. A total of 482 participants signed up to take part in the study, with 265 completing the requisite four consecutive test sessions. No evidence of an effect of gamification on attrition was observed. A log-rank test showed no evidence of a difference in dropout rates between task variants (χ 2 2 =3.0, P=.22), and a one-way analysis of variance of the mean number of sessions completed per participant in each variant also showed no evidence of a difference (F 2,262 =1.534, P=.21, partial η 2 =0.012). Our findings raise doubts about the ability of gamification to reduce attrition from longitudinal cognitive testing studies

  17. Attrition, burnout, job dissatisfaction and occupational therapy managers.

    Science.gov (United States)

    Kraeger, M M; Walker, K F

    1992-01-01

    At a time when there is growing concern about the person-power shortages in occupational therapy, there is a need to address reasons why therapists leave the job market. Two job-related reasons for attrition are burnout and job dissatisfaction. The burnout phenomenon occurs as a result of personnel shortages, high-stress demands on therapists, the severity and complexity of client's problems, and the therapist's own ''worker personality.'' Bureaucratic constraints, limited advancement, issues related to a profession which is made up predominantly of women, lack of autonomy, and type of management and supervision are factors that contribute to job dissatisfaction. Occupational therapy managers can consider the causes of burnout and job dissatisfaction and initiate resources to retain therapists. Managers can increase the job benefits, such as flexible working hours, take steps to reduce stress in the workplace, offer career laddering opportunities, and promote staff development. By identifying the causes for attrition and by addressing those causes, the threat of losing therapists from the work force may be averted. Respondents (n = 106) to a survey of occupational therapy managers indicated that job dissatisfaction, burnout, and attrition of registered occupational therapists were not major problems in their settings. They reported a variety of strategies to reduce job dissatisfaction, burnout, and attrition. When these problems were present, managers cited bureaucratic red tape, lack of opportunity for advancement, and increasing role demands as contributing factors.

  18. A Comparative Study of Administrator and Special Education Teacher Perceptions of Special Education Teacher Attrition and Retention

    Science.gov (United States)

    Sheldrake, Danielle Angelina

    2013-01-01

    This mixed methods study identifies perceived causes of and solutions to the attrition of special education teachers. Researchers have documented that special education teaching positions encounter higher attrition rates than their general education peers (Katsiyannis, Zhang, & Conroy in Olivarez & Arnold, 2006; Mitchell & Arnold,…

  19. High-rate lithium thionyl chloride cells

    Science.gov (United States)

    Goebel, F.

    1982-03-01

    A high-rate C cell with disc electrodes was developed to demonstrate current rates which are comparable to other primary systems. The tests performed established the limits of abuse beyond which the cell becomes hazardous. Tests include: impact, shock, and vibration tests; temperature cycling; and salt water immersion of fresh cells.

  20. Lithium thionyl chloride high rate discharge

    Science.gov (United States)

    Klinedinst, K. A.

    1980-04-01

    Improvements in high rate lithium thionyl chloride power technology achieved by varying the electrolyte composition, operating temperature, cathode design, and cathode composition are discussed. Discharge capacities are plotted as a function of current density, cell voltage, and temperature.

  1. Concomitant chemoradiotherapy with high dose rate brachytherapy ...

    African Journals Online (AJOL)

    Concomitant chemoradiotherapy with high dose rate brachytherapy as a definitive treatment modality for locally advanced cervical cancer. T Refaat, A Elsaid, N Lotfy, K Kiel, W Small Jr, P Nickers, E Lartigau ...

  2. Attrition in a 30-year follow-up of a perinatal birth risk cohort: factors change with age

    Directory of Open Access Journals (Sweden)

    Jyrki Launes

    2014-07-01

    Full Text Available Background. Attrition is a major cause of potential bias in longitudinal studies and clinical trials. Attrition rate above 20% raises concern of the reliability of the results. Few studies have looked at the factors behind attrition in follow-ups spanning decades.Methods. We analyzed attrition and associated factors of a 30-year follow-up cohort of subjects who were born with perinatal risks for neurodevelopmental disorders. Attrition rates were calculated at different stages of follow-up and differences between responders and non-responders were tested. To find combinations of variables influencing attrition and investigate their relative importance at birth, 5, 9, 16 and 30 years of follow-up we used the random forest classification.Results. Initial loss of potential participants was 13%. Attrition was 16% at five, 24% at nine, 35% at 16 and 46% at 30 years. The only group difference that emerged between responders and non-responders was in socioeconomic status (SES. The variables identified by random forest classification analysis were classified into Birth related, Development related and SES related. Variables from all these categories contributed to attrition, but SES related variables were less important than birth and development associated variables. Classification accuracy ranged between 0.74 and 0.96 depending on age.Discussion. Lower SES is linked to attrition in many studies. Our results point to the importance of the growth and development related factors in a longitudinal study. Parents’ decisions to participate depend on the characteristics of the child. The same association was also seen when the child, now grown up, decided to participate at 30 years. In addition, birth related medical variables are associated with the attrition still at the age of 30. Our results using a data mining approach suggest that attrition in longitudinal studies is influenced by complex interactions of a multitude of variables, which are not

  3. Lanchester's attrition models and fights among social animals

    OpenAIRE

    Eldridge S. Adams; Michael Mesterton-Gibbons

    2003-01-01

    Lanchester's models of attrition during warfare have served as the basis for several predictions about conflicts between groups of animals. These models and their extensions describe rates of mortality during battles as functions of the number and fighting abilities of individuals in each group, allowing analysis of the determinants of group strength and of the cumulative numbers of casualties. We propose modifications to Lanchester's models to improve their applicability to social animals. I...

  4. Military Enlistment and Attrition. An Analysis of Decision Reversal

    Science.gov (United States)

    1987-06-01

    instability, defined as being unemployed at the time of enlistment or having had a spell of jobless- ness within the past 12 months. For graduates, attrition...opportunities. The level of education an individual obtains is related to the value of higher education to the individual (both monetary and psychic ...value, does suggest that unemployed graduates are more likely to enlist, all other things equal, the higher their previous wage rate. The previous

  5. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    -reinforced polymers, were considered, and it was first shown that the loading history controls equilibrium process. Then the High-speed servo-hydraulic test machine was analysed in terms its ability to create a state of constant strain rate in the specimen. The invertible inertial forces in the load train prevented...... from designing and constructing a high-speed servo-hydraulic test machine and by performing a comprehensive test series. The difficulties encountered in the test work could be addressed with the developed analysis. The conclusion was that the High-speed servo-hydraulic test machine is less suited...... for testing fibre-reinforced polymers due to their elastic behaviour and low strain to failure. This is problematic as the High-speed servo-hydraulic test machine closes the gap between quasi-static tests rates and lower strain rates, which are achievable with the Split Hopkinson Pressure Bar. The Split...

  6. Thrombus Formation at High Shear Rates.

    Science.gov (United States)

    Casa, Lauren D C; Ku, David N

    2017-06-21

    The final common pathway in myocardial infarction and ischemic stroke is occlusion of blood flow from a thrombus forming under high shear rates in arteries. A high-shear thrombus forms rapidly and is distinct from the slow formation of coagulation that occurs in stagnant blood. Thrombosis at high shear rates depends primarily on the long protein von Willebrand factor (vWF) and platelets, with hemodynamics playing an important role in each stage of thrombus formation, including vWF binding, platelet adhesion, platelet activation, and rapid thrombus growth. The prediction of high-shear thrombosis is a major area of biofluid mechanics in which point-of-care testing and computational modeling are promising future directions for clinically relevant research. Further research in this area will enable identification of patients at high risk for arterial thrombosis, improve prevention and treatment based on shear-dependent biological mechanisms, and improve blood-contacting device design to reduce thrombosis risk.

  7. High frame rate synthetic aperture duplex imaging

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Pihl, Michael Johannes

    2013-01-01

    aperture flow imaging as demonstrated in this paper. Synthetic aperture, directional beamforming, and cross-correlation are used to produce B-mode and vector velocity images at high frame rates. The frame rate equals the effective pulse repetition frequency of each imaging mode. Emissions for making the B...... estimation is −1.8% and the relative standard deviation 5.4%. The approach can thus estimate both high and low velocities with equal accuracy and thereby makes it possible to present vector flow images with a high dynamic range. Measurements are made using the SARUS research scanner, a linear array......Conventional color flow images are limited in velocity range and can either show the high velocities in systole or be optimized for the lower diastolic velocities. The full dynamics of the flow is, thus, hard to visualize. The dynamic range can be significantly increased by employing synthetic...

  8. Attrition in longitudinal randomized controlled trials: home visits make a difference

    Directory of Open Access Journals (Sweden)

    Peterson Janey C

    2012-11-01

    Full Text Available Abstract Background Participant attrition in longitudinal studies can introduce systematic bias, favoring participants who return for follow-up, and increase the likelihood that those with complications will be underestimated. Our aim was to examine the effectiveness of home follow-up (Home F/U to complete the final study evaluation on potentially “lost” participants by: 1 evaluating the impact of including and excluding potentially “lost” participants (e.g., those who required Home F/U to complete the final evaluation on the rates of study complications; 2 examining the relationship between timing and number of complications on the requirement for subsequent Home F/U; and 3 determining predictors of those who required Home F/U. Methods We used data from a randomized controlled trial (RCT conducted from 1991–1994 among coronary artery bypass graft surgery patients that investigated the effect of High mean arterial pressure (MAP (intervention vs. Low MAP (control during cardiopulmonary bypass on 5 complications: cardiac morbidity/mortality, neurologic morbidity/mortality, all-cause mortality, neurocognitive dysfunction and functional decline. We enhanced completion of the final 6-month evaluation using Home F/U. Results Among 248 participants, 61 (25% required Home F/U and the remaining 187 (75% received Routine F/U. By employing Home F/U, we detected 11 additional complications at 6 months: 1 major neurologic complication, 6 cases of neurocognitive dysfunction and 4 cases of functional decline. Follow-up of 61 additional Home F/U participants enabled us to reach statistical significance on our main trial outcome. Specifically, the High MAP group had a significantly lower rate of the Combined Trial Outcome compared to the Low MAP group, 16.1% vs. 27.4% (p=0.032. In multivariate analysis, participants who were ≥ 75 years (OR=3.23, 95% CI 1.52-6.88, p=0.002 or on baseline diuretic therapy (OR=2.44, 95% CI 1.14-5.21, p=0.02 were more

  9. The Canadian Forces Recruitment/Attrition Model

    National Research Council Canada - National Science Library

    Wait, Tracey

    1998-01-01

    ...), as part of its mandate to provide analysis of potential impacts of trends and change on defense and defense related issues, has designed a prototype model of recruitment and attrition of the Canadian Forces (C F...

  10. Baltimore District Tackles High Suspension Rates

    Science.gov (United States)

    Maxwell, Lesli A.

    2007-01-01

    This article reports on how the Baltimore District tackles its high suspension rates. Driven by an increasing belief that zero-tolerance disciplinary policies are ineffective, more educators are embracing strategies that do not exclude misbehaving students from school for offenses such as insubordination, disrespect, cutting class, tardiness, and…

  11. Endorectal high dose rate brachytherapy quality assurance

    International Nuclear Information System (INIS)

    Devic, S.; Vuong, T.; Evans, M.; Podgorsak, E.

    2008-01-01

    We describe our quality assurance method for preoperative high dose rate (HDR) brachytherapy of endorectal tumours. Reproduction of the treatment planning dose distribution on a daily basis is crucial for treatment success. Due to the cylindrical symmetry, two types of adjustments are necessary: applicator rotation and dose distribution shift along the applicator axis. (author)

  12. Attrition during a randomized controlled trial of reduced nicotine content cigarettes as a proxy for understanding acceptability of nicotine product standards.

    Science.gov (United States)

    Mercincavage, Melissa; Wileyto, E Paul; Saddleson, Megan L; Lochbuehler, Kirsten; Donny, Eric C; Strasser, Andrew A

    2017-06-01

    To determine (1) if nicotine content affects study attrition-a potential behavioral measure of acceptability-in a trial that required compliance with three levels of reduced nicotine content (RNC) cigarettes, and (2) if attrition is associated with subjective and behavioral responses to RNC cigarettes. Secondary analysis of a 35-day, parallel-design, open-label, randomized controlled trial. After a 5-day baseline period, participants were randomized to smoke for three 10-day periods: their preferred brand (control group) or RNC cigarettes with three nicotine levels in a within-subject stepdown (one group: high-moderate-low) or non-stepdown (five groups: high-low-moderate, low-moderate-high, low-high-moderate, moderate-low-high, moderate-high-low) fashion. A single site in Philadelphia, PA, USA. A total of 246 non-treatment-seeking daily smokers [mean age = 39.52, cigarettes per day (CPD) = 20.95, 68.3% white] were recruited from October 2007 to June 2013. The primary outcome was attrition. Key predictors were nicotine content transition and study period. Exploratory predictors were taste and strength subjective ratings, total puff volume and carbon monoxide (CO) boost. Covariates included: age, gender, race, education and nicotine dependence. Overall attrition was 31.3% (n = 77): 24.1% of the control and 25.0% of the stepdown RNC cigarette groups dropped out versus 44.6% of non-stepdown groups (P = 0.006). Compared with controls, attrition odds were 4.5 and 4.7 times greater among smokers transitioning from preferred and the highest RNC cigarettes to the lowest RNC cigarettes, respectively (P = 0.001 and 0.003). Providing more favorable initial taste ratings of study cigarettes decreased attrition odds by 2% (P = 0.012). The majority of participants completed a 35-day trial of varying levels of reduced nicotine content cigarettes. Participant dropout was greater for cigarettes with lower nicotine content and less in smokers reporting more favorable

  13. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    Martínez A.B.

    2012-08-01

    Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  14. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  15. High dose rate endobronchial brachytherapy - treatment technique

    International Nuclear Information System (INIS)

    Carvalho, Heloisa de Andrade; Aisen, Salim; Haddad, Cecilia Maria Kalil; Nadalin, Wladimir; Pedreira Junior, Wilson Leite; Chavantes, Maria Cristina

    1998-01-01

    High dose rate endobronchial brachytherapy is efficient in symptom relief due to obstructive endobronchial malignancies. However, it's role in survival improvement for patients with lung cancer is not yet established. The use of this treatment in increasing, specially in the developing countries. The purpose of this paper is to present the treatment technique used in the Radiotherapy Department of the Hospital da Clinicas, University of Sao Paulo, based on an experience of 60 cases treated with 180 procedures. Some practical suggestions and rules adopted in the Department are described. The severe complications rate is 6.7%, demonstrating an adequate patient selection associated with the technique utilized. (author)

  16. Electronics for very high rate tracking detectors

    International Nuclear Information System (INIS)

    Williams, H.H.; Dressnandt, N.; Ekenberg, T.; Gerds, E.J.; Newcomer, F.M.; Tedja, S.; Van Berg, R.; Van der Speigel, J.

    1995-01-01

    Results are presented on a system of electronics designed for very high rate tracking detectors at the SSC and LHC. The primary goal was a system for signal detection, time measurement, and readout for the straw tracker for SDC. An integrated circuit incorporating eight channels of amplifier-shaper-discriminator (including detector tail cancellation), and two different integrated circuits for time measurement are described. The performance of tracking measurements up to counting rates of 8 MHz per wire is reported, as well as preliminary results from a baseline restoration circuit. (orig.)

  17. High strain rate studies in rock

    International Nuclear Information System (INIS)

    Grady, D.

    1977-01-01

    Dynamic compression studies using high velocity impact are usually considered to involve a catastrophic process of indeterminate loading rate by which a material is brough to a shock compressed state. Although this is frequently the case, methods are also available to control the rate of strain during the shock compression process. One of the most accurate of these methods makes use of the anomalous nonlinear elastic property of glass to transform an initial shock or step wave input into a ramp wave of known amplitude and duration. Fused silica is the most carefully calibrated material for this purpose and, when placed between the test specimen and the impact projectile, can provide loading strain rates in the range of 10 4 /s to 10 6 /s for final stress states of approximately 3.9 GPa or less.Ramp wave compression experiments have been conducted on dolomite at strain rates of 3 x 10 4 /s. Both initial yielding and subsequent deformation at this strain rate agrees well with previous shock wave studies (epsilon-dotapprox.10 6 /s) and differs substantially from quasi-static measurements (epsilon-dotapprox.10 -4 /s). The ramp wave studies have also uncovered a pressure-induced phase transition in dolomite initiating at 4.0 GPa

  18. Unemployment, the Great Recession, and Apprenticeship Attrition in the U.S.

    Science.gov (United States)

    Bilginsoy, Cihan

    2018-01-01

    The author estimates the impacts of the local rate of unemployment and the Great Recession on the quit and graduation rates of the U.S. construction trade apprentices over the 2001-2014 period. Trade union participation in training sponsorship had a strong influence on attrition rates. The impacts of the business cycle and the Great Recession on…

  19. High repetition rate intense ion beam source

    International Nuclear Information System (INIS)

    Hammer, D.A.; Glidden, S.C.; Noonan, B.

    1992-01-01

    This final report describes a ≤ 150kV, 40kA, 100ns high repetition rate pulsed power system and intense ion beam source which is now in operation at Cornell University. Operation of the Magnetically-controlled Anode Plasma (MAP) ion diode at > 100Hz (burst mode for up to 10 pulse bursts) provides an initial look at repetition rate limitations of both the ion diode and beam diagnostics. The pulsed power systems are capable of ≥ 1kHz operation (up to 10 pulse bursts), but ion diode operation was limited to ∼100Hz because of diagnostic limitations. By varying MAP diode operating parameters, ion beams can be extracted at a few 10s of keV or at up to 150keV, the corresponding accelerating gap impedance ranging from about 1Ω to about 10Ω. The ability to make hundreds of test pulses per day at an average repetition rate of about 2 pulses per minute permits statistical analysis of diode operation as a function of various parameters. Most diode components have now survived more than 10 4 pulses, and the design and construction of the various pulsed power components of the MAP diode which have enabled us to reach this point are discussed. A high speed data acquisition system and companion analysis software capable of acquiring pulse data at 1ms intervals (in bursts of up to 10 pulses) and processing it in ≤ min is described

  20. High strain rate deformation of layered nanocomposites.

    Science.gov (United States)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A; Thomas, Edwin L

    2012-01-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  1. High strain rate deformation of layered nanocomposites

    Science.gov (United States)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  2. High-frame-rate digital radiographic videography

    Science.gov (United States)

    King, Nicholas S. P.; Cverna, Frank H.; Albright, Kevin L.; Jaramillo, Steven A.; Yates, George J.; McDonald, Thomas E.; Flynn, Michael J.; Tashman, Scott

    1994-10-01

    High speed x-ray imaging can be an important tool for observing internal processes in a wide range of applications. In this paper we describe preliminary implementation of a system having the eventual goal of observing the internal dynamics of bone and joint reactions during loading. Two Los Alamos National Laboratory (LANL) gated and image intensified camera systems were used to record images from an x-ray image convertor tube to demonstrate the potential of high frame-rate digital radiographic videography in the analysis of bone and joint dynamics of the human body. Preliminary experiments were done at LANL to test the systems. Initial high frame-rate imaging (from 500 to 1000 frames/s) of a swinging pendulum mounted to the face of an X-ray image convertor tube demonstrated high contrast response and baseline sensitivity. The systems were then evaluated at the Motion Analysis Laboratory of Henry Ford Health Systems Bone and Joint Center. Imaging of a 9 inch acrylic disk with embedded lead markers rotating at approximately 1000 RPM, demonstrated the system response to a high velocity/high contrast target. By gating the P-20 phosphor image from the X-ray image convertor with a second image intensifier (II) and using a 100 microsecond wide optical gate through the second II, enough prompt light decay from the x-ray image convertor phosphor had taken place to achieve reduction of most of the motion blurring. Measurement of the marker velocity was made by using video frames acquired at 500 frames/s. The data obtained from both experiments successfully demonstrated the feasibility of the technique. Several key areas for improvement are discussed along with salient test results and experiment details.

  3. Determination of the attrition resistance of granular charcoals

    International Nuclear Information System (INIS)

    Dietz, V.R.

    1979-01-01

    A laboratory procedure has been developed to evaluate the attrition of granular adsorbent charcoals on passing an air flow through the bed. Two factors observed in plant operations were selected as relevant: (1) the characteristic structural vibrations in plant scale equipment (motors, fans, etc.) that are transmitted to charcoal particles and cause the particles to move and rub each other, and (2) the rapid air flow that results in the movement of the attrited dust. In the test a container for charcoal [50 mm diameter and 50 mm high] was vibrated at a frequency of 60 Hz and at a constant energy input manually controlled using a vibration meter in the acceleration mode. Simultaneously, air was applied and exited through glass fiber filter paper. The quantity of dust trapped on the exit filter was then determined, either optically or gravimetrically. The dust formed per minute (attrition coefficient) was found to approach a constant value. The plateau-values from sequential determinations varied with the source of the charcoal; a 5-fold difference was found among a large variety of commercial products. The first testing of a sample released the excess dust accumulated in previous handling of the charcoal. The plateau values were then attained in the succeeding tests and these were characteristic of the material. The results were compared with those obtained for the same charcoals using older test methods such as the Ball and Pan Hardness Test described in RDTM16-1T

  4. Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

    Energy Technology Data Exchange (ETDEWEB)

    Adeyiga, Adeyinka

    2010-02-05

    Commercial spent fluid catalytic cracking (FCC) catalysts provided by Engelhard and Albemarle were used as supports for Fe-based catalysts with the goal of improving the attrition resistance of typical F-T catalysts. Catalysts with the Ruhrchemie composition (100 Fe/5 Cu/4.2 K/25 spent FCC on mass basis) were prepared by wet impregnation. XRD and XANES analysis showed the presence of Fe{sub 2}O{sub 3} in calcined catalysts. FeC{sub x} and Fe{sub 3}O{sub 4} were present in the activated catalysts. The metal composition of the catalysts was analyzed by ICP-MS. F-T activity of the catalysts activated in situ in CO at the same conditions as used prior to the attrition tests was measured using a fixed bed reactor at T = 573 K, P = 1.38 MPa and H{sub 2}:CO ratio of 0.67. Cu and K promoted Fe supported over Engelhard provided spent FCC catalyst shows relatively good attrition resistance (8.2 wt% fines lost), high CO conversion (81%) and C{sub 5}+ hydrocarbons selectivity (18.3%).

  5. A Self-Regulation-Based eHealth Intervention to Promote a Healthy Lifestyle: Investigating User and Website Characteristics Related to Attrition.

    Science.gov (United States)

    Van der Mispel, Celien; Poppe, Louise; Crombez, Geert; Verloigne, Maïté; De Bourdeaudhuij, Ilse

    2017-07-11

    eHealth interventions can reach large populations and are effective in increasing physical activity (PA) and fruit and vegetable intake. Nevertheless, the effects of eHealth interventions are overshadowed by high attrition rates. Examining more closely when users decide to leave the intervention can help eHealth developers to make informed decisions about which intervention components should be reshaped or simply removed. Investigating which users are more likely to quit an intervention can inform developers about whether and how their intervention should be adapted to specific subgroups of users. This study investigated the pattern of attrition in a Web-based intervention to increase PA, fruit, and vegetable intake. The first aim was to describe attrition rates according to different self-regulation components. A second aim was to investigate whether certain user characteristics are predictors for start session completion, returning to a follow-up session and intervention completion. The sample consisted of 549 adults who participated in an online intervention, based on self-regulation theory, to promote PA and fruit and vegetable intake, called "MyPlan 1.0." Using descriptive analysis, attrition was explored per self-regulation component (eg, action planning and coping planning). To identify which user characteristics predict completion, logistic regression analyses were conducted. At the end of the intervention program, there was an attrition rate of 78.2% (330/422). Attrition rates were very similar for the different self-regulation components. However, attrition levels were higher for the fulfillment of questionnaires (eg, to generate tailored feedback) than for the more interactive components. The highest amount of attrition could be observed when people were asked to make their own action plan. There were no significant predictors for first session completion. Yet, two subgroups had a lower chance to complete the intervention, namely male users (OR: 2.24, 95

  6. High counting rate resistive-plate chamber

    International Nuclear Information System (INIS)

    Peskov, V.; Anderson, D.F.; Kwan, S.

    1993-05-01

    Parallel-plate avalanche chambers (PPAC) are widely used in physics experiments because they are fast ( 5 counts/mm 2 . A resistive-plate chamber (RPC) is similar to the PPAC in construction except that one or both of the electrodes are made from high resistivity (≥10 10 Ω·cm) materials. In practice RPCs are usually used in the spark mode. Resistive electrodes are charged by sparks, locally reducing the actual electric field in the gap. The size of the charged surface is about 10 mm 2 , leaving the rest of the detector unaffected. Therefore, the rate capability of such detectors in the spark mode is considerably higher than conventional spark counters. Among the different glasses tested the best results were obtained with electron type conductive glasses, which obey Ohm's law. Most of the work with such glasses was done with high pressure parallel-plate chambers (10 atm) for time-of-flight measurements. Resistive glasses have been expensive and produced only in small quantities. Now resistive glasses are commercially available, although they are still expensive in small scale production. From the positive experience of different groups working with the resistive glasses, it was decided to review the old idea to use this glass for the RPC. This work has investigated the possibility of using the RPC at 1 atm and in the avalanche mode. This has several advantages: simplicity of construction, high rate capability, low voltage operation, and the ability to work with non-flammable gases

  7. On high interest rates in Brazil

    Directory of Open Access Journals (Sweden)

    Francisco Lafaiete Lopes

    2014-03-01

    Full Text Available This article examines the question of why interest rates are so high in Brazil as compared to the international average. It looks at theoretical arguments based on excessive government deficits, structural lack of private savings, inflation bias, excessive investment demand and fear of floating. An informal look at the evidence does not strongly corroborate any of these arguments. Hence a wise central bank should consider "testing" the market to make sure it is not dealing with an extreme equilibrium configuration or a long standing disequilibrium.

  8. Flashing motor at high transition rate

    International Nuclear Information System (INIS)

    Ai Baoquan; Wang Liqiu; Liu Lianggang

    2007-01-01

    The movement of a Brownian particle in a fluctuating two-state periodic potential is investigated. At high transition rate, we use a perturbation method to obtain the analytical solution of the model. It is found that the net current is a peaked function of thermal noise, barrier height and the fluctuation ratio between the two states. The thermal noise may facilitate the directed motion at a finite intensity. The asymmetry parameter of the potential is sensitive to the direction of the net current

  9. No differential attrition was found in randomized controlled trials published in general medical journals: a meta-analysis.

    Science.gov (United States)

    Crutzen, Rik; Viechtbauer, Wolfgang; Kotz, Daniel; Spigt, Mark

    2013-09-01

    Differential attrition is regarded as a major threat to the internal validity of a randomized controlled trial (RCT). This study identifies the degree of differential attrition in RCTs covering a broad spectrum of clinical areas and factors that are related to this. A PubMed search was conducted to obtain a random sample of 100 RCTs published between 2008 and 2010 in journals from the ISI Web of Knowledge(SM) category of medicine, general and internal. Eligibility criteria for selecting studies were primary publications of two-arm parallel randomized clinical trials, containing human participants and one or multiple follow-up measurements whose availability depended on the patients' willingness to participate. A significant amount of differential attrition was observed in 8% of the trials. The average differential attrition rate was 0.99 (95% confidence interval: 0.97-1.01), indicating no general difference in attrition rates between intervention and control groups. Moreover, no indication of heterogeneity was found, suggesting that the occurrence of differential attrition in the published literature is mostly a chance finding, unrelated to any particular design factors. Differential attrition did not generally occur in RCTs covering a broad spectrum of clinical areas within general and internal medicine. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. High dose rate brachytherapy for oral cancer

    International Nuclear Information System (INIS)

    Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Koizumi, Masahiko; Ogawa, Kazuhiko; Furukawa, Souhei

    2013-01-01

    Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. (author)

  11. High dose rate brachytherapy for oral cancer.

    Science.gov (United States)

    Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

    2013-01-01

    Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer.

  12. Ultra Fast, High Rep Rate, High Voltage Spark Gap Pulser

    Science.gov (United States)

    1995-07-01

    current rise time. The spark gap was designed to have a coaxial geometry reducing its inductance. Provisions were made to pass flowing gas between the...ULTRA FAST, HIGH REP RATE, HIGH VOLTAGE SPARK GAP PULSER Robert A. Pastore Jr., Lawrence E. Kingsley, Kevin Fonda, Erik Lenzing Electrophysics and...Modeling Branch AMSRL-PS-EA Tel.: (908)-532-0271 FAX: (908)-542-3348 U.S. Army Research Laboratory Physical Sciences Directorate Ft. Monmouth

  13. The implications of selective attrition for estimates of intergenerational elasticity of family income.

    Science.gov (United States)

    Schoeni, Robert F; Wiemers, Emily E

    2015-09-01

    Numerous studies have estimated a high intergenerational correlation in economic status. Such studies do not typically attend to potential biases that may arise due to survey attrition. Using the Panel Study of Income Dynamics - the data source most commonly used in prior studies - we demonstrate that attrition is particularly high for low-income adult children with low-income parents and particularly low for high-income adult children with high-income parents. Because of this pattern of attrition, intergenerational upward mobility has been overstated for low-income families and downward mobility has been understated for high-income families. The bias among low-income families is greater than the bias among high-income families implying that intergenerational elasticity in family income is higher than previous estimates with the Panel Study of Income Dynamics would suggest.

  14. Incorporating direct marketing activity into latent attrition models

    NARCIS (Netherlands)

    Schweidel, David A.; Knox, George

    2013-01-01

    When defection is unobserved, latent attrition models provide useful insights about customer behavior and accurate forecasts of customer value. Yet extant models ignore direct marketing efforts. Response models incorporate the effects of direct marketing, but because they ignore latent attrition,

  15. Operation of high rate microstrip gas chambers

    CERN Document Server

    Barr, A J; Bouclier, Roger; Capéans-Garrido, M; Dominik, Wojciech; Manzin, G; Million, Gilbert; Hoch, M; Ropelewski, Leszek; Sauli, Fabio; Sharma, A

    1996-01-01

    We describe recent measurements carried out in well controlled and reproducible conditions to help understanding the factors affecting the short and long term behaviour of Microstrip Gas Chambers. Special care has been taken concerning the gas purity and choice of materials used in the system and for the detectors construction. Detectors built on glasses with surface resistivity in the range $10^{13}-10^{15} \\Omega/\\Box$ have shown satisfactory performance as they do not show charging-up process at high rate and stand the large doses required for the future high luminosity experiments (~10 mC·cm-1·yr-1). Concerning the lifetime measurements, it has been observed that chambers manufactured on high-resistivity glass are far more susceptible of suffering ageing than detectors made on low resistivity, electron-conducting supports, independently of the metal used for the artwork (chromium or gold) at least in clean gas conditions. The successfully operation in the laboratory of detectors manufactured on diamond-...

  16. An experimental study on the primary fragmentation and attrition of limestones in a fluidized bed

    International Nuclear Information System (INIS)

    Yao, Xuan; Zhang, Hai; Yang, Hairui; Liu, Qing; Wang, Jinwei; Yue, Guangxi

    2010-01-01

    In this paper, an experimental study on the primary fragmentation and attrition of 5 limestones in a fluidized bed was conducted. The intensity of fragmentation and attrition were measured in the same apparatus but at different fluidizing velocities. It was found that the averaged size of the particles decreased by about 10-20% during the fragmentation process. The important factors for particle comminution include limestone types, heating rate, calcination condition and ambient CO 2 concentration. Fragmentation mainly occurred in the first a few minutes in the fluidized bed and it was more intense than that in the muffle furnace at the same temperature. The original size effect was ambiguous, depending on the limestone type. The comminution caused by attrition mainly occurred during calcination process rather than sulphation process. The sulphation process was fragmentation and attrition resisted. The attrition rate of sulphate was similar to that of lime in trend, decaying exponentially with time, but was one-magnitude-order smaller than that of lime. Present experimental results indicate that fragmentation mechanism of the limestone is dominated by CO 2 release instead of thermal stress. (author)

  17. Consideration of wear rates at high velocity

    Science.gov (United States)

    Hale, Chad S.

    The development of the research presented here is one in which high velocity relative sliding motion between two bodies in contact has been considered. Overall, the wear environment is truly three-dimensional. The attempt to characterize three-dimensional wear was not economically feasible because it must be analyzed at the micro-mechanical level to get results. Thus, an engineering approximation was carried out. This approximation was based on a metallographic study identifying the need to include viscoplasticity constitutive material models, coefficient of friction, relationships between the normal load and velocity, and the need to understand wave propagation. A sled test run at the Holloman High Speed Test Track (HHSTT) was considered for the determination of high velocity wear rates. In order to adequately characterize high velocity wear, it was necessary to formulate a numerical model that contained all of the physical events present. The experimental results of a VascoMax 300 maraging steel slipper sliding on an AISI 1080 steel rail during a January 2008 sled test mission were analyzed. During this rocket sled test, the slipper traveled 5,816 meters in 8.14 seconds and reached a maximum velocity of 1,530 m/s. This type of environment was never considered previously in terms of wear evaluation. Each of the features of the metallography were obtained through micro-mechanical experimental techniques. The byproduct of this analysis is that it is now possible to formulate a model that contains viscoplasticity, asperity collisions, temperature and frictional features. Based on the observations of the metallographic analysis, these necessary features have been included in the numerical model, which makes use of a time-dynamic program which follows the movement of a slipper during its experimental test run. The resulting velocity and pressure functions of time have been implemented in the explicit finite element code, ABAQUS. Two-dimensional, plane strain models

  18. Factors of Attrition in Cohort Doctoral Education: A Self-Determination Theory Perspective

    Science.gov (United States)

    Garcia, Linda Ann

    2013-01-01

    Attrition rates, completion rates, and time to degree are the key areas researchers have sought to examine influencing factors and patterns of behavior that describe the departure process of students in doctoral study. Through the lens of self-determination theory (Deci & Ryan, 1985), the purpose of this phenomenological qualitative study was…

  19. Reducing Nursing Student Attrition: The Search for Effective Strategies

    Science.gov (United States)

    Kubec, Cathy

    2017-01-01

    This review of the literature summarizes recent exploration of nursing student attrition. Attrition places financial burdens on students who leave a program, results in lost revenue for the college, and compounds the existing nursing shortage. Some research investigated the student selection process, which seeks to decrease attrition by admitting…

  20. Exploring Beginning Teachers' Attrition in the Netherlands

    Science.gov (United States)

    den Brok, Perry; Wubbels, Theo; van Tartwijk, Jan

    2017-01-01

    Based on a review of recent studies and reports, this research investigates attrition among beginning teachers in the Netherlands as well as reasons for teacher attrition, and compares the finding with studies on this topic conducted elsewhere in the world. The findings suggest that attrition among beginning teachers in the Netherlands with a…

  1. High Data Rate Architecture (HiDRA)

    Science.gov (United States)

    Hylton, Alan; Raible, Daniel

    2016-01-01

    high-rate laser terminals. These must interface with the existing, aging data infrastructure. The High Data Rate Architecture (HiDRA) project is designed to provide networked store, carry, and forward capability to optimize data flow through both the existing radio frequency (RF) and new laser communications terminal. The networking capability is realized through the Delay Tolerant Networking (DTN) protocol, and is used for scheduling data movement as well as optimizing the performance of existing RF channels. HiDRA is realized as a distributed FPGA memory and interface controller that is itself controlled by a local computer running DTN software. Thus HiDRA is applicable to other arenas seeking to employ next-generation communications technologies, e.g. deep space. In this paper, we describe HiDRA and its far-reaching research implications.

  2. Attrition resistant gamma-alumina catalyst support

    Science.gov (United States)

    Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

    2006-03-14

    A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

  3. Predicting Student Attrition with Data Mining Methods

    Science.gov (United States)

    Delen, Dursun

    2012-01-01

    Affecting university rankings, school reputation, and financial well-being, student retention has become one of the most important measures of success for higher education institutions. From the institutional perspective, improving student retention starts with a thorough understanding of the causes behind the attrition. Such an understanding is…

  4. Photocathodes for High Repetition Rate Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, Ilan [Stony Brook Univ., NY (United States). Dept. of Physics and Astronomy. Center for Accelerator Science and Education

    2014-04-20

    This proposal brought together teams at Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL) and Stony Brook University (SBU) to study photocathodes for high repetition rate light sources such as Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). Below details the Principal Investigators and contact information. Each PI submits separately for a budget through his corresponding institute. The work done under this grant comprises a comprehensive program on critical aspects of the production of the electron beams needed for future user facilities. Our program pioneered in situ and in operando diagnostics for alkali antimonide growth. The focus is on development of photocathodes for high repetition rate Free Electron Lasers (FELs) and Energy Recovery Linacs (ERLs), including testing SRF photoguns, both normal-­conducting and superconducting. Teams from BNL, LBNL and Stony Brook University (SBU) led this research, and coordinated their work over a range of topics. The work leveraged a robust infrastructure of existing facilities and the support was used for carrying out the research at these facilities. The program concentrated in three areas: a) Physics and chemistry of alkali-­antimonide cathodes (BNL – LBNL) b) Development and testing of a diamond amplifier for photocathodes (SBU -­ BNL) c) Tests of both cathodes in superconducting RF photoguns (SBU) and copper RF photoguns (LBNL) Our work made extensive use of synchrotron radiation materials science techniques, such as powder-­ and single-­crystal diffraction, x-­ray fluorescence, EXAFS and variable energy XPS. BNL and LBNL have many complementary facilities at the two light sources associated with these laboratories (NSLS and ALS, respectively); use of these will be a major thrust of our program and bring our understanding of these complex materials to a new level. In addition, CHESS at Cornell will be used to continue seamlessly throughout the NSLS dark period and

  5. DEVELOPMENT OF ATTRITION RESISTANT IRON-BASED FISCHER-TROPSCH CATALYSTS

    International Nuclear Information System (INIS)

    Adeyinka A. Adeyiga

    2001-01-01

    The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H 2 ) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. The use of iron-based catalysts is attractive not only due to their low cost and ready availability, but also due to their high water-gas shift activity which makes it possible to use these catalysts with low H 2 /CO ratios. However, a serious problem with use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, makes the separation of catalyst from the oil/wax product very difficult if not impossible, and results in a steady loss of catalyst from the reactor. Recently, fundamental understanding of physical attrition is being addressed by incorporating suitable binders into the catalyst recipe. This has resulted in the preparation of a spray dried Fe-based catalyst having aps of 70 mm with high attrition resistance. This Fe-based attrition resistant, active and selective catalyst gave 95% CO conversion through 125 hours of testing in a fixed-bed at 270 C, 1.48 MPa, H 2 /CO=0.67 and 2.0 NL/g-cat/h with C 5 + selectivity of >78% and methane selectivity of <5%. However, further development of the catalyst is needed to address the chemical attrition due to phase changes that any Fe-catalyst goes through potentially causing internal stresses within the particle and resulting in weakening, spalling or cracking. The objective of this research is to develop robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry bubble column reactor. Specifically we aim to develop to: (i) improve the performance and preparation procedure of the high activity, high attrition resistant, high alpha iron

  6. Brachytherapy treatment with high dose rate

    International Nuclear Information System (INIS)

    Santana Rodriguez, Sergio Marcelino; Rodriguez Rodriguez, Lissi Lisbet; Ciscal Chiclana, Onelio Alberto

    2009-01-01

    Retrospectively analyze results and prognostic factors of cervical cancer patients treated with radio concomitant cisplatin-based chemotherapy, radiation therapy combined modality. Methods: From January 2003 to December 2007, 198 patients with invasive cervical cancer were treated at the Oncology Department of Hospital Robau Celestino Hernandez (brachytherapy performed at INOR). The most common age group was 31 to 40 years. The histology in squamous cell carcinoma accounted for 84.3% of cases. The treatment consisted of external pelvic irradiation and vaginal brachytherapy, high dose rate. Concomitant chemotherapy consisted of cisplatin 40 mg/m2 weekly with a maximum of 70 mg for 5 weeks. Results: 66.2% of patients completed 5 cycles of chemotherapy. The median overall survival was 39 months, overall survival, disease-free survival and survival free of locoregional recurrence at 5 years of 78%, 76% and 78.6% respectively .. We found that clinical stage, histological type (adenocarcinoma worst outcome) were statistically related to level of response. Conclusions: Treatment with external pelvic radiation, brachytherapy and concurrent weekly cisplatin in patients with stage IIIB cervical cancer is feasible in the Chilean public health system, well tolerated and results comparable to international literature. (Author)

  7. High mitogenomic evolutionary rates and time dependency.

    NARCIS (Netherlands)

    Subramanian, S.; Denver, D.R.; Millar, C.D.; Heupink, T.; Aschrafi, A.; Emslie, S.D.; Baroni, C.; Lambert, D.M.

    2009-01-01

    Using entire modern and ancient mitochondrial genomes of Adelie penguins (Pygoscelis adeliae) that are up to 44000 years old, we show that the rates of evolution of the mitochondrial genome are two to six times greater than those estimated from phylogenetic comparisons. Although the rate of

  8. Confusing similar words: ERP correlates of lexical-semantic processing in first language attrition and late second language acquisition.

    Science.gov (United States)

    Kasparian, Kristina; Steinhauer, Karsten

    2016-12-01

    First language (L1) attrition is a socio-linguistic circumstance where second language (L2) learning coincides with changes in exposure and use of the native-L1. Attriters often report experiencing a decline in automaticity or proficiency in their L1 after a prolonged period in the L2 environment, while their L2 proficiency continues to strengthen. Investigating the neurocognitive correlates of attrition alongside those of late L2 acquisition addresses the question of whether the brain mechanisms underlying both L1 and L2 processing are strongly determined by proficiency, irrespective of whether the language was acquired from birth or in adulthood. Using event-related-potentials (ERPs), we examined lexical-semantic processing in Italian L1 attriters, compared to adult Italian L2 learners and to Italian monolingual native speakers. We contrasted the processing of classical lexical-semantic violations (Mismatch condition) with sentences that were equally semantically implausible but arguably trickier, as the target-noun was "swapped" with an orthographic neighbor that differed only in its final vowel and gender-marking morpheme (e.g., cappello (hat) vs. cappella (chapel)). Our aim was to determine whether sentences with such "confusable nouns" (Swap condition) would be processed as semantically correct by late L2 learners and L1 attriters, especially for those individuals with lower Italian proficiency scores. We found that lower-proficiency Italian speakers did not show significant N400 effects for Swap violations relative to correct sentences, regardless of whether Italian was the L1 or the L2. Crucially, N400 response profiles followed a continuum of "nativelikeness" predicted by Italian proficiency scores - high-proficiency attriters and high-proficiency Italian learners were indistinguishable from native controls, whereas attriters and L2 learners in the lower-proficiency range showed significantly reduced N400 effects for "Swap" errors. Importantly, attriters

  9. Cheetah: A high frame rate, high resolution SWIR image camera

    Science.gov (United States)

    Neys, Joel; Bentell, Jonas; O'Grady, Matt; Vermeiren, Jan; Colin, Thierry; Hooylaerts, Peter; Grietens, Bob

    2008-10-01

    A high resolution, high frame rate InGaAs based image sensor and associated camera has been developed. The sensor and the camera are capable of recording and delivering more than 1700 full 640x512pixel frames per second. The FPA utilizes a low lag CTIA current integrator in each pixel, enabling integration times shorter than one microsecond. On-chip logics allows for four different sub windows to be read out simultaneously at even higher rates. The spectral sensitivity of the FPA is situated in the SWIR range [0.9-1.7 μm] and can be further extended into the Visible and NIR range. The Cheetah camera has max 16 GB of on-board memory to store the acquired images and transfer the data over a Gigabit Ethernet connection to the PC. The camera is also equipped with a full CameralinkTM interface to directly stream the data to a frame grabber or dedicated image processing unit. The Cheetah camera is completely under software control.

  10. Vocabulary Attrition among Adult English as a Foreign Language Persian Learners

    Science.gov (United States)

    Asgari, Azadeh; Bin Mustapha, Ghazali

    2010-01-01

    This study aims to investigate the attrition rate of EFL concrete and abstract vocabulary among continuing and non-continuing Iranian female and male English language learners across different proficiency levels. They are students of a University and majored in different fields (between 20 and 25 years old). There was no treatment in this study…

  11. The measurement of change in functional ability: dealing with attrition and the floor/ceiling effect

    DEFF Research Database (Denmark)

    Holstein, Bjørn E; Avlund, Kirsten; Due, Pernille

    2006-01-01

    , functional ability at baseline, relative wealth, social network, self-rated health, and life-satisfaction. Inclusion of the dead in statistical models for the study of change in functional ability reduced the attrition problem. A logistic model for paired observations of functional ability at two points...

  12. Special Education Teacher Perception of Administrative Supports That Encourage, Decrease Burnout, and Reduce Attrition

    Science.gov (United States)

    Beebe, Jay

    2017-01-01

    The field of special education is facing a shortage of teachers. A shortage of special education teachers is an example of a pressing issue within education. The problem is that teacher attrition rates are among the highest within special education. Many special education teachers are leaving the profession after a few years of teaching for varied…

  13. Ceramic high-rate timing RPCs

    International Nuclear Information System (INIS)

    Lopes, L.; Ferreira Marques, R.; Fonte, P.; Hennetier, L.; Pereira, A.; Sousa Correia, A.M.

    2006-01-01

    Following some previous work, we report here considerable improvements on the counting rate capability of timing RPCs by the use of ceramic electrodes with a resistivity of 10 9 Ω.cm. The X-ray sensitivity of the detector depends linearly on the counting rate with a slope of 9% per 100 kHz/cm 2 , free from charge depletion effects, while keeping a timing accuracy, measured with 511 keV synchronous photon pairs, around 90 ps σ up to 75 kHz/cm 2

  14. Reliability and Cost Impacts for Attritable Systems

    Science.gov (United States)

    2017-03-23

    on reliability and cost: a probabilistic model. Electric Power Systems Research, 72(3), 213-224. Kalbfleisch, J.D. & Prentice, R.L. (1980). The...copyright protection in the United States. AFIT-ENV-MS-17-M-172 RELIABILITY AND COST IMPACTS FOR ATTRITABLE SYSTEMS THESIS Presented to... power of discrete time Markov chains, whether homogeneous or non-homogeneous, to model the reliability and dependability of repairable systems should

  15. A qualitative and quantitative study of the reasons of attrition in an Indian hospital

    Directory of Open Access Journals (Sweden)

    Kasturi Shukla

    2017-01-01

    Full Text Available Background: The study attempts to evaluate the reasons of attrition in the organization from the perspective of the existing as well as the leaving employees; compare and identify the gaps, if any between the perspectives of these two employees groups. The study also aims to critically analyze the utility of ′exit interviews′ for analyzing the reasons of attrition. Methods: This cross-sectional study was conducted in a 150-bedded hospital in Ahmedabad, India, during May-July 2015. Exit interview data of forty leaving employees were collected and reviewed. One hundred existing employees were interviewed through quantitative and qualitative methods to understand their perceptions about attrition in the organization. Results: Attrition rate of 26% was observed in the study and 57% leaving employees were nurses. 70% leaving employees cite "blanket reasons" such as better opportunity and personal reasons during exit interviews. 72.5% leaving employees believed that exit interview is largely for record purpose and 11% were unsure of its utility. However, when existing employees were probed qualitatively, a variety of responses were received. 65% existing employees quoted salary issues, partiality/poor recognition, improper assignment of tasks, and monotonous work as reasons for attrition in the organization. Conclusion: Exit interviews somewhere fail to probe into the real reasons of attrition. To improve retention, organizations must monitor their existing employee′s intention to continue working in the organization and any sign indicating a poor intention to continue must be addressed immediately to avoid ripple effects. Moreover, to use exit interview as a tool to improve employee retention, leaving employees must be interviewed in-depth to uncover the actual reasons for quitting the job.

  16. Analytical modelling for ultrasonic surface mechanical attrition treatment

    Directory of Open Access Journals (Sweden)

    Guan-Rong Huang

    2015-07-01

    Full Text Available The grain refinement, gradient structure, fatigue limit, hardness, and tensile strength of metallic materials can be effectively enhanced by ultrasonic surface mechanical attrition treatment (SMAT, however, never before has SMAT been treated with rigorous analytical modelling such as the connection among the input energy and power and resultant temperature of metallic materials subjected to SMAT. Therefore, a systematic SMAT model is actually needed. In this article, we have calculated the averaged speed, duration time of a cycle, kinetic energy and kinetic energy loss of flying balls in SMAT for structural metallic materials. The connection among the quantities such as the frequency and amplitude of attrition ultrasonic vibration motor, the diameter, mass and density of balls, the sample mass, and the height of chamber have been considered and modelled in details. And we have introduced the one-dimensional heat equation with heat source within uniform-distributed depth in estimating the temperature distribution and heat energy of sample. In this approach, there exists a condition for the frequency of flying balls reaching a steady speed. With these known quantities, we can estimate the strain rate, hardness, and grain size of sample.

  17. The Surgical Personality: Does Surgery Resident Motivation Predict Attrition?

    Science.gov (United States)

    Symer, Matthew M; Abelson, Jonathan S; Yeo, Heather L; Sosa, Julie A; Rosenthal, M Zachary

    2018-05-01

    There is limited understanding of the wide variation in attrition rates among general surgery residencies. We used the validated Behavior Inhibitory System/Behavior Approach System (BIS/BAS) instrument to compare motivational traits among residents who did and not complete surgical training. All US general surgery categorical interns in the class of 2007-2008 were surveyed with a validated motivational trait assessment tool. American Board of Surgery records from 2008-2016 were used to determine who completed training. Motivation, an aspect of personality, was assessed with the BIS/BAS, which correlates with an individual's tendency to approach pleasant stimuli (BAS) or avoid negative stimuli (BIS). Subscale mean scores were compared with regard to the primary end point, attrition. Eight hundred and one (76.5%) interns completed the survey and had matching records. Six hundred and forty-five (80.5%) completed training. Men had lower scores than women in the BAS Drive subscale (12.0 vs 12.5; p scale (19.3 vs 20.9; p academic 17.3 vs community 17.6 vs military 16.6; p motivational personality traits. Copyright © 2018 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  18. Expectations and voluntary attrition in nursing students.

    Science.gov (United States)

    O'Donnell, Hugh

    2011-01-01

    This paper presents a series of findings generated during a larger study which aimed to develop a theoretical understanding of the reasons why nursing students voluntarily leave pre-registration nursing programmes. In this study, significant incongruence was found to exist between student expectations of pre-registration nursing programmes and the reality of these programmes following entry. The resulting dissonance was identified as an important factor in student decisions to voluntarily withdraw. A single case study design was selected to explore the causes of voluntary attrition in nursing students within a School of Nursing and Midwifery. The study population was obtained through purposeful sampling and consisted of 15 students who had previously voluntarily withdrawn from pre-registration nursing programmes. A semi-structured interview method was used to collect data from study participants. The interview schedule developed for use in the study reflected the key components of the conceptual model of higher education (HE) student attrition (Tinto, 1975, 1987, 1993). All interviews were tape recorded to facilitate later transcription. The Cyclical or Interactive Model of Qualitative Research (Miles and Huberman, 1994) was used to analyse data collected from study participants. This paper describes the unrealistic range of expectations which nursing students have of nursing, the information sources and experiences which inform student expectations and how ambiguous expectations contributed to voluntarily attrition. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Factors related to attrition from trauma-focused cognitive behavioral therapy.

    Science.gov (United States)

    Wamser-Nanney, Rachel; Steinzor, Cazzie E

    2017-04-01

    Attrition from child trauma-focused treatments such as Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) is common; yet, the factors of children who prematurely terminate are unknown. The aim of the current study was to identify risk factors for attrition from TF-CBT. One hundred and twenty-two children (ages 3-18; M=9.97, SD=3.56; 67.2% females; 50.8% Caucasian) who received TF-CBT were included in the study. Demographic and family variables, characteristics of the trauma, and caregiver- and child-reported pretreatment symptoms levels were assessed in relation to two operational definitions of attrition: 1) clinician-rated dropout, and 2) whether the child received an adequate dose of treatment (i.e., 12 or more sessions). Several demographic factors, number of traumatic events, and children's caregiver-rated pretreatment symptoms were related to clinician-rated dropout. Fewer factors were associated with the adequate dose definition. Child Protective Services involvement, complex trauma exposure, and child-reported pretreatment trauma symptoms were unrelated to either attrition definition. Demographics, trauma characteristics, and level of caregiver-reported symptoms may help to identify clients at risk for premature termination from TF-CBT. Clinical and research implications for different operational definitions and suggestions for future work will be presented. Published by Elsevier Ltd.

  20. Transition to high rate aerospace NDI processes

    Science.gov (United States)

    Vanderheiden, Bert; Thomson, Clint; Ivakhnenko, Igor; Garner, Chuck

    2018-04-01

    With the rapidly expanding use of carbon fiber composite materials in military and commercial aircraft, processes to manufacture and inspect the structural components must evolve to ensure economic viability. Inspection techniques which were developed to inspect products produced at a rate of one or two structures a month are not fast or flexible enough to inspect more than 8500 parts per month. This presentation describes the evolution of phased array ultrasonic inspection systems to provide the increased rate capacity, the flexibility to accommodate multiple unique designs, and the ability to rapidly adjust to product design changes. The paper will describe how system developments were made in response to new programs resulting in a much less expensive, higher degree of accuracy, increased flexibility, and lower cycle time inspections.

  1. High exposure rate hardware ALARA plan

    International Nuclear Information System (INIS)

    Nellesen, A.L.

    1996-10-01

    This as low as reasonably achievable review provides a description of the engineering and administrative controls used to manage personnel exposure and to control contamination levels and airborne radioactivity concentrations. HERH waste is hardware found in the N-Fuel Storage Basin, which has a contact dose rate greater than 1 R/hr and used filters. This waste will be collected in the fuel baskets at various locations in the basins

  2. Why Are Real Interest Rates So High?

    OpenAIRE

    Zvi Bodie; Alex Kane; Robert L. McDonald

    1983-01-01

    This paper applies the Capital Asset Pricing Model to help explain the anomalous behavior of real interest rates during the last several years. Specifically,we are able to show that the increased volatility of bond prices since the change in Federal Reserve operating procedure in October 1979 has substantially increased the required real risk premium on long term bonds. We also consider and reject the possibility that increased risk alone accounts for the recent increase in the short-term rea...

  3. High readmission rate after heart valve surgery

    DEFF Research Database (Denmark)

    Sibilitz, K L; Berg, S K; Thygesen, L C

    2015-01-01

    investigated. RESULTS: After valve surgery, the self-reported health was lower (Short Form-36 (SF-36) Physical Component Scale (PCS): 44.5 vs. 50.6 and Mental Component Scale (MCS): 51.9 vs. 55.0, pClinical signs......BACKGROUND: After heart valve surgery, knowledge on long-term self-reported health status and readmission is lacking. Thus, the optimal strategy for out-patient management after surgery remains unclear. METHODS: Using a nationwide survey with linkage to Danish registers with one year follow-up, we...... included all adults 6-12months after heart valve surgery irrespective of valve procedure, during Jan-June 2011 (n=867). Participants completed a questionnaire regarding health-status (n=742), and answers were compared with age- and sex-matched healthy controls. Readmission rates and mortality were...

  4. Demographic and psychological predictors of panel attrition: evidence from the New Zealand attitudes and values study.

    Directory of Open Access Journals (Sweden)

    Nicole Satherley

    Full Text Available This study examines attrition rates over the first four years of the New Zealand Attitudes and Values Study, a longitudinal national panel sample of New Zealand adults. We report the base rate and covariates for the following four distinct classes of respondents: explicit withdrawals, lost respondents, intermittent respondents and constant respondents. A multinomial logistic regression examined an extensive range of demographic and socio-psychological covariates (among them the Big-Six personality traits associated with membership in these classes (N = 5,814. Results indicated that men, Māori and Asian peoples were less likely to be constant respondents. Conscientiousness and Honesty-Humility were also positively associated with membership in the constant respondent class. Notably, the effect sizes for the socio-psychological covariates of panel attrition tended to match or exceed those of standard demographic covariates. This investigation broadens the focus of research on panel attrition beyond demographics by including a comprehensive set of socio-psychological covariates. Our findings show that core psychological covariates convey important information about panel attrition, and are practically important to the management of longitudinal panel samples like the New Zealand Attitudes and Values Study.

  5. The network of corporate clients: customer attrition at commercial banks

    Science.gov (United States)

    Lublóy, Á.; Szenes, M.

    2008-12-01

    Commercial banks might profit from the adoption of methods widely used in network theory. A decision making process might become biased if one disregards network effects within the corporate client portfolio. This paper models the phenomenon of customer attrition by generating a weighted and directed network of corporate clients linked by financial transactions. During the numerical study of the agent-based toy model we demonstrate that multiple steady states may exist. The statistical properties of the distinct steady states show similarities. We show that most companies of the same community choose the same bank in the steady state. In contrast to the case for the steady state of the Barabási-Albert network, market shares in this model equalize by network size. When modeling customer attrition in the network of 3 × 105 corporate clients, none of the companies followed the behavior of the initial switcher in three quarters of the simulations. The number of switchers exceeded 20 in 1% of the cases. In the worst-case scenario a total of 688 companies chose a competitor bank. Significant network effects have been discovered; high correlation prevailed between the degree of the initial switcher and the severity of the avalanche effect. This suggests that the position of the corporate client in the network might be much more important than the underlying properties (industry, size, profitability, etc) of the company.

  6. The management of over closured anterior teeth due to attrition

    OpenAIRE

    Eha Djulaeha; Sukaedi Sukaedi

    2009-01-01

    Background: Tooth is the hardest tissue in human body, that can be injured because of attrition process. For old people, denture attrition process is caused by psysiological process relating with the mastication function which also supported by some bad habits such an bruxism, premature contact, and consuming habit of abrasive food. Attrition or abrasion can also be happened with patien’t dentition who does not have teeth subtutition for long time due the lost of their maxillary as well as ma...

  7. High dose rate brachytherapy source measurement intercomparison.

    Science.gov (United States)

    Poder, Joel; Smith, Ryan L; Shelton, Nikki; Whitaker, May; Butler, Duncan; Haworth, Annette

    2017-06-01

    This work presents a comparison of air kerma rate (AKR) measurements performed by multiple radiotherapy centres for a single HDR 192 Ir source. Two separate groups (consisting of 15 centres) performed AKR measurements at one of two host centres in Australia. Each group travelled to one of the host centres and measured the AKR of a single 192 Ir source using their own equipment and local protocols. Results were compared to the 192 Ir source calibration certificate provided by the manufacturer by means of a ratio of measured to certified AKR. The comparisons showed remarkably consistent results with the maximum deviation in measurement from the decay-corrected source certificate value being 1.1%. The maximum percentage difference between any two measurements was less than 2%. The comparisons demonstrated the consistency of well-chambers used for 192 Ir AKR measurements in Australia, despite the lack of a local calibration service, and served as a valuable focal point for the exchange of ideas and dosimetry methods.

  8. Undergraduate Navigator Training Attrition Study

    Science.gov (United States)

    1975-11-01

    stabilization. The Masculinity- Feminity Scale (SVIB), significant at the .05 level, contributed 1.73% to the predicted variance. High scores (those...8217 a iiiftihlilfft-tMJ ^^mm^mmmwm^mmmmm mmmmm Do you have extensive experience in athletic competition? If so, what sport (s) and what kind of...machinery? For example, farm equipment, construction equipment. Do you have extensive experience in athletic competition? If so, what sport (s) and what

  9. High-deposition-rate ceramics synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, M.D.; Osterheld, T.H.; Outka, D.A. [Sandia National Laboratories, Livermore, CA (United States)] [and others

    1995-05-01

    Parallel experimental and computational investigations are conducted in this project to develop validated numerical models of ceramic synthesis processes. Experiments are conducted in the High-Temperature Materials Synthesis Laboratory in Sandia`s Combustion Research Facility. A high-temperature flow reactor that can accommodate small preforms (1-3 cm diameter) generates conditions under which deposition can be observed, with flexibility to vary both deposition temperature (up to 1500 K) and pressure (as low as 10 torr). Both mass spectrometric and laser diagnostic probes are available to provide measurements of gas-phase compositions. Experiments using surface analytical techniques are also applied to characterize important processes occuring on the deposit surface. Computational tools developed through extensive research in the combustion field are employed to simulate the chemically reacting flows present in typical industrial reactors. These include the CHEMKIN and Surface-CHEMKIN suites of codes, which permit facile development of complex reaction mechanisms and vastly simplify the implementation of multi-component transport and thermodynamics. Quantum chemistry codes are also used to estimate thermodynamic and kinetic data for species and reactions for which this information is unavailable.

  10. Liquid Argon Calorimeter performance at High Rates

    CERN Document Server

    Seifert, F; The ATLAS collaboration

    2013-01-01

    The expected increase of luminosity at HL-LHC by a factor of ten with respect to LHC luminosities has serious consequences for the signal reconstruction, radiation hardness requirements and operations of the ATLAS liquid argon calorimeters in the endcap, respectively forward region. Small modules of each type of calorimeter have been built and exposed to a high intensity proton beam of 50 GeV at IHEP/Protvino. The beam is extracted via the bent crystal technique, offering the unique opportunity to cover intensities ranging from $10^6$ p/s up to $3\\cdot10^{11}$ p/s. This exceeds the deposited energy per time expected at HL-LHC by more than a factor of 100. The correlation between beam intensity and the read-out signal has been studied. The data show clear indications of pulse shape distortion due to the high ionization build-up, in agreement with MC expectations. This is also confirmed from the dependence of the HV currents on beam intensity.

  11. Career Stories of Israeli Teachers Who Left Teaching: A Salutogenic View of Teacher Attrition

    Science.gov (United States)

    Yinon, Hayuta; Orland-Barak, Lily

    2017-01-01

    Many countries experience a high percentage of teachers who leave the profession before retirement. Most of the explanations, such as teacher burnout, adopt a pathogenic point of view which perceives attrition as a negative work outcome. In contrast, the qualitative project that this article is based on, which characterizes the career…

  12. Disappearing Act: Persistence and Attrition of Uniform Resource Locators (URLs) in an Open Access Medical Journal

    Science.gov (United States)

    Nagaraja, Aragudige; Joseph, Shine A.; Polen, Hyla H.; Clauson, Kevin A.

    2011-01-01

    Purpose: The aim of this paper is to assess and catalogue the magnitude of URL attrition in a high-impact, open access (OA) general medical journal. Design/methodology/approach: All "Public Library of Science Medicine (PLoS Medicine)" articles for 2005-2007 were evaluated and the following items were assessed: number of entries per issue; type of…

  13. Flue gas desulfurization under simulated oxyfiring fluidized bed combustion conditions: The influence of limestone attrition and fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Scala, F.; Salatino, P. [CNR, Naples (Italy)

    2010-01-01

    Flue gas desulfurization by means of limestone injection under simulated fluidized bed oxyfiring conditions was investigated, with a particular focus on particle attrition and fragmentation phenomena. An experimental protocol was applied, based on the use of complementary techniques that had been previously developed for the characterization of attrition of sorbents in air-blown atmospheric fluidized bed combustors. The extent and pattern of limestone attrition by surface wear in the dense phase of a fluidized bed were assessed in bench scale fluidized bed experiments under simulated oxyfiring conditions. Sorbent samples generated during the oxyfiring tests were further characterized from the standpoint of fragmentation upon high velocity impact by means of a particle impactor. The experimental results were compared with those previously obtained with the same limestone under air-blown atmospheric fluidized bed combustion conditions. The profound differences in the attrition and fragmentation extents and patterns associated with oxyfiring as compared to air-blown atmospheric combustion and the role played by the different attrition/fragmentation paths were highlighted. In particular, it was noted that attrition could effectively enhance particle sulfation under oxyfiring conditions by continuously disclosing unconverted calcium to the sulfur-bearing atmosphere.

  14. High School Graduation Rates:Alternative Methods and Implications

    OpenAIRE

    Jing Miao; Walt Haney

    2004-01-01

    The No Child Left Behind Act has brought great attention to the high school graduation rate as one of the mandatory accountability measures for public school systems. However, there is no consensus on how to calculate the high school graduation rate given the lack of longitudinal databases that track individual students. This study reviews literature on and practices in reporting high school graduation rates, compares graduation rate estimates yielded from alternative methods, and estimates d...

  15. Improving retention and graduation rates for black students in nursing education: a developmental model.

    Science.gov (United States)

    Jones, S H

    1992-01-01

    High attrition rates among black students are a significant factor in the decline in graduation rates from nursing programs. Nursing education needs a program to address problems of anger, frustration, and loneliness and to develop the black student as a whole person.

  16. High School Graduation Rates:Alternative Methods and Implications

    Directory of Open Access Journals (Sweden)

    Jing Miao

    2004-10-01

    Full Text Available The No Child Left Behind Act has brought great attention to the high school graduation rate as one of the mandatory accountability measures for public school systems. However, there is no consensus on how to calculate the high school graduation rate given the lack of longitudinal databases that track individual students. This study reviews literature on and practices in reporting high school graduation rates, compares graduation rate estimates yielded from alternative methods, and estimates discrepancies between alternative results at national, state, and state ethnic group levels. Despite the graduation rate method used, results indicate that high school graduation rates in the U.S. have been declining in recent years and that graduation rates for black and Hispanic students lag substantially behind those of white students. As to graduation rate method preferred, this study found no evidence that the conceptually more complex methods yield more accurate or valid graduation rate estimates than the simpler methods.

  17. Survey on workforce retention and attrition

    Science.gov (United States)

    Showstack, Randy

    2013-03-01

    The Society of Petroleum Engineers (SPE) is conducting a survey to gather information on why technical professionals change jobs or quit working. The survey, prompted by concern about the retention of skilled workers, aims to provide information to employers that can assist them in addressing practices that can lead to significant workforce attrition. To participate in the survey, which is open to everyone (including those who are not SPE members), go to http://research.spe.org/se.ashx?s=705E3F1335720258 through 15 May 2013. For more information, contact speresearch@spe.org.

  18. The Rapier or the Club: The Relationship between Attrition and Maneuver Warfare

    National Research Council Canada - National Science Library

    Springman, Jeffrey A

    2006-01-01

    ...? This project compares the relationship between attrition and maneuver warfare. The study considers whether there are times when wars of attrition should be fought, and whether there are conditions that force wars of attrition...

  19. A Qualitative Evaluation of Engagement and Attrition in a Nurse Home Visiting Program: From the Participant and Provider Perspective.

    Science.gov (United States)

    Beasley, Lana O; Ridings, Leigh E; Smith, Tyler J; Shields, Jennifer D; Silovsky, Jane F; Beasley, William; Bard, David

    2018-05-01

    Beginning parenting programs in the prenatal and early postnatal periods have a large potential for impact on later child and maternal outcomes. Home-based parenting programs, such as the Nurse Family Partnership (NFP), have been established to help address this need. Program reach and impact is dependent on successful engagement of expecting mothers with significant risks; however, NFP attrition rates remain high. The current study qualitatively examined engagement and attrition from the perspectives of NFP nurses and mothers in order to identify mechanisms that enhance service engagement. Semi-structured interviews were conducted in focus groups composed of either engaged (27 total mothers) or unengaged (15 total mothers) mothers from the NFP program. NFP nurses (25 total nurses) were recruited for individual semi-structured interviews. Results suggest that understanding engagement in the NFP program requires addressing both initial and sustained engagement. Themes associated with enhanced initial engagement include nurse characteristics (e.g., flexible, supportive, caring) and establishment of a solid nurse-family relationship founded on these characteristics. Factors impacting sustained engagement include nurse characteristics, provision of educational materials on child development, individualized services for families, and available family support. Identified barriers to completing services include competing demands and lack of support. Findings of this study have direct relevance for workforce planning, including hiring and training through integrating results regarding effective nurse characteristics. Additional program supports to enhance parent engagement may be implemented across home-based parenting programs in light of the current study's findings.

  20. The influence of temperature on limestone sulfation and attrition under fluidized bed combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Montagnaro, Fabio [Dipartimento di Chimica - Universita degli Studi di Napoli Federico II, Complesso Universitario del Monte di Sant' Angelo, 80126 Napoli (Italy); Salatino, Piero [Istituto di Ricerche sulla Combustione - CNR, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Dipartimento di Ingegneria Chimica - Universita degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Scala, Fabrizio [Istituto di Ricerche sulla Combustione - CNR, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy)

    2010-04-15

    The influence of temperature on attrition of two limestones during desulfurization in a fluidized bed reactor was investigated. Differences in the microstructure of the two limestones were reflected by a different thickness of the sulfate shell formed upon sulfation and by a different value of the ultimate calcium conversion degree. Particle attrition and fragmentation were fairly small under moderately bubbling fluidization conditions for both limestones. An increase of temperature from 850 C to 900 C led to an increase of the attrition rate, most likely because of a particle weakening effect caused by a faster CO{sub 2} evolution during calcination. This weakening effect, however, was not sufficiently strong to enhance particle fragmentation in the bed. The progress of sulfation, associated to the build-up of a hard sulfate shell around the particles, led in any case to a decrease of the extent of attrition. Sulfation at 900 C was less effective than at 850 C, and this was shown to be related to the porosimetric features of the different samples. (author)

  1. The Effect of Minimum Wage Rates on High School Completion

    Science.gov (United States)

    Warren, John Robert; Hamrock, Caitlin

    2010-01-01

    Does increasing the minimum wage reduce the high school completion rate? Previous research has suffered from (1. narrow time horizons, (2. potentially inadequate measures of states' high school completion rates, and (3. potentially inadequate measures of minimum wage rates. Overcoming each of these limitations, we analyze the impact of changes in…

  2. High regression rate, high density hybrid fuels, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR program will investigate high energy density novel nanofuels combined with high density binders for use with an N2O oxidizer. Terves has developed...

  3. The american high school graduation rate : trends and levels

    OpenAIRE

    Heckman, James J.; LaFontaine, Paul A.

    2008-01-01

    This paper uses multiple data sources and a unified methodology to estimate the trends and levels of the U.S. high school graduation rate. Correcting for important biases that plague previous calculations, we establish that (a) the true high school graduation rate is substantially lower than the official rate issued by the National Center for Educational Statistics; (b) it has been declining over the past 40 years; (c) majority/minority graduation rate differentials are substantial and have n...

  4. Attrition resistant Fischer-Tropsch catalyst and support

    Science.gov (United States)

    Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

    2004-05-25

    A catalyst support having improved attrition resistance and a catalyst produced therefrom. The catalyst support is produced by a method comprising the step of treating calcined .gamma.-alumina having no catalytic material added thereto with an acidic aqueous solution having an acidity level effective for increasing the attrition resistance of the calcined .gamma.-alumina.

  5. Early Career Teacher Attrition: Intentions of Teachers Beginning

    Science.gov (United States)

    Clandinin, D. Jean; Long, Julie; Schaefer, Lee; Downey, C. Aiden; Steeves, Pam; Pinnegar, Eliza; McKenzie Robblee, Sue; Wnuk, Sheri

    2015-01-01

    Early career teacher attrition has most often been conceptualized as either a problem associated with individual factors (e.g. burnout) or a problem associated with contextual factors (e.g. support and salary). This study considered early career teacher attrition as an identity making process that involves a complex negotiation between individual…

  6. Obstacles to Success--Doctoral Student Attrition in South Africa

    Science.gov (United States)

    Herman, Chaya

    2011-01-01

    The article explores doctoral attrition in South Africa, investigating and comparing the attributions of attrition of doctoral students and PhD programme leaders. The article is based on secondary data analysis of two large studies on doctoral education in South Africa. The main point of the article is that the different understandings of the…

  7. Temporal dynamics of high repetition rate pulsed single longitudinal ...

    Indian Academy of Sciences (India)

    ing (GIG) cavity, single-mode dye laser pumped by high repetition rate ... in a high loss cavity, a detailed theoretical study and optimization of cavity ..... rate for high conversion efficiency and longer pulse width of the single-mode dye laser.

  8. Quantum data locking for high-rate private communication

    OpenAIRE

    Lupo, Cosmo; Lloyd, Seth

    2015-01-01

    We show that, if the accessible information is used as a security quantifier, quantum channels with a certain symmetry can convey private messages at a tremendously high rate, as high as less than one bit below the rate of non-private classical communication. This result is obtained by exploiting the quantum data locking effect. The price to pay to achieve such a high private communication rate is that accessible information security is in general not composable. However, composable security ...

  9. High-Rate Strong-Signal Quantum Cryptography

    Science.gov (United States)

    Yuen, Horace P.

    1996-01-01

    Several quantum cryptosystems utilizing different kinds of nonclassical lights, which can accommodate high intensity fields and high data rate, are described. However, they are all sensitive to loss and both the high rate and the strong-signal character rapidly disappear. A squeezed light homodyne detection scheme is proposed which, with present-day technology, leads to more than two orders of magnitude data rate improvement over other current experimental systems for moderate loss.

  10. The pattern of attrition from an antiretroviral treatment program in Nigeria.

    Directory of Open Access Journals (Sweden)

    Solomon Odafe

    Full Text Available To evaluate the rate and factors associated with attrition of patients receiving ART in tertiary and secondary hospitals in Nigeria.We reviewed patient level data collected between 2007 and 2010 from 11 hospitals across Nigeria. Kaplan-Meier product-limit and Cox regression were used to determine probability of retention in care and risk factors for attrition respectively. Of 6,408 patients in the cohort, 3,839 (59.9% were females, median age of study population was 33years (IQR: 27-40 and 4,415 (69% were from secondary health facilities. The NRTI backbone was Stavudine (D4T in 3708 (57.9% and Zidovudine (ZDV in 2613 (40.8% of patients. Patients lost to follow up accounted for 62.7% of all attrition followed by treatment stops (25.3% and deaths (12.0%. Attrition was 14.1 (N = 624 and 15.1% (N = 300 in secondary and tertiary hospitals respectively (p = 0.169 in the first 12 months on follow up. During the 13 to 24 months follow up period, attrition was 10.7% (N = 407 and 19.6% (N = 332 in secondary and tertiary facilities respectively (p<0.001. Median time to lost to follow up was 11.1 (IQR: 6.1 to 18.5 months in secondary compared with 13.6 (IQR: 9.9 to 17.0 months in tertiary sites (p = 0.002. At 24 months follow up, male gender [AHR 1.18, 95% CI: 1.01-1.37, P = 0.038]; WHO clinical stage III [AHR 1.30, 95%CI: 1.03-1.66, P = 0.03] and clinical stage IV [AHR 1.90, 95%CI: 1.20-3.02, p = 0.007] and care in a tertiary hospital [AHR 2.21, 95% CI: 1.83-2.67, p<0.001], were associated with attrition.Attrition could potentially be reduced by decentralizing patients on ART after the first 12 months on therapy to lower level facilities, earlier initiation on treatment and strengthening adherence counseling amongst males.

  11. Limestone attrition under simulated oxyfiring Fluidized-Bed combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Scala, F. [Istituto di Ricerche sulla Combustione - CNR, Napoli (Italy); Salatino, P. [Dipartimento di Ingegneria Chimica - Universita degli Studi di Napoli Federico II, Napoli (Italy)

    2009-03-15

    Limestone attrition by surface wear was studied during the flue gas desulfurization under simulated fluidized-bed (FB) oxyfiring conditions and hindered calcination. Bench-scale experimental tests were carried out using well-established techniques previously developed for the characterization of sulfation and attrition of sorbents in air-blown atmospheric FB combustors. The experimental limestone conversion and attrition results were compared with those previously obtained with the same limestone under simulated air-blown combustion conditions. The differences in the conversion and attrition extents and patterns associated with oxyfiring as compared to air-blown atmospheric combustion were highlighted and related to the different particle morphologies and thicknesses of the sulfate layer. It was noted that attrition could play an important role in practical circulating FB combustor operation, by effectively enhancing particle sulfation under both oxyfiring and air-blown combustion conditions. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  12. High rate flame synthesis of highly crystalline iron oxide nanorods

    International Nuclear Information System (INIS)

    Merchan-Merchan, W; Taylor, A M; Saveliev, A V

    2008-01-01

    Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe 3 O 4 ) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks

  13. HIGH-RATE DISINFECTION TECHNIQUES FOR COMBIND SEWER OVERFLOW

    Science.gov (United States)

    This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH )...

  14. High Graduate Unemployment Rate and Taiwanese Undergraduate Education

    Science.gov (United States)

    Wu, Chih-Chun

    2011-01-01

    An expansion in higher education in combination with the recent global economic recession has resulted in a high college graduate unemployment rate in Taiwan. This study investigates how the high unemployment rate and financial constraints caused by economic cutbacks have shaped undergraduates' class choices, job needs, and future income…

  15. Circuit and interconnect design for high bit-rate applications

    NARCIS (Netherlands)

    Veenstra, H.

    2006-01-01

    This thesis presents circuit and interconnect design techniques and design flows that address the most difficult and ill-defined aspects of the design of ICs for high bit-rate applications. Bottlenecks in interconnect design, circuit design and on-chip signal distribution for high bit-rate

  16. Task shifting for cataract surgery in eastern Africa: productivity and attrition of non-physician cataract surgeons in Kenya, Malawi and Tanzania.

    Science.gov (United States)

    Eliah, Edson; Lewallen, Susan; Kalua, Khumbo; Courtright, Paul; Gichangi, Michael; Bassett, Ken

    2014-01-01

    This project examined the surgical productivity and attrition of non-physician cataract surgeons (NPCSs) in Tanzania, Malawi, and Kenya. Baseline (2008-9) data on training, support, and productivity (annual cataract surgery rate) were collected from officially trained NPCSs using mailed questionnaires followed by telephone interviews. Telephone interviews were used to collect follow-up data annually on productivity and semi-annually on attrition. A detailed telephone interview was conducted if a surgeon left his/her post. Data were entered into and analysed using STATA. Among the 135 NPCSs, 129 were enrolled in the study (Kenya 88, Tanzania 38, and Malawi 3) mean age 42 years; average time since completing training 6.6 years. Employment was in District 44%, Regional 24% or mission/ private 32% hospitals. Small incision cataract surgery was practiced by 38% of the NPCSs. The mean cataract surgery rate was 188/year, median 76 (range 0-1700). For 39 (31%) NPCSs their surgical rate was more than 200/year. Approximately 22% in Kenya and 25% in Tanzania had years where the cataract surgical rate was zero. About 11% of the surgeons had no support staff. High quality training is necessary but not sufficient to result in cataract surgical activity that meets population needs and maintains surgical skill. Needed are supporting institutions and staff, functioning equipment and programs to recruit and transport patients.

  17. Attrition of Knowledge Workforce in Healthcare in Northern parts of India – Health Information Technology as a Plausible Retention Strategy

    Directory of Open Access Journals (Sweden)

    Indrajit Bhattacharya

    2012-06-01

    Full Text Available Faced with a global shortage of skilled health workers due to attrition, countries are struggling to build and maintain optimum knowledge workforce in healthcare for delivering quality healthcare services. Forces that affect healthcare professionals’ turnover needs to be addressed before a competent uniformly adoptable strategy could be proposed for mitigating the problem. In this study we investigate the effects of the socio–demographic characteristics on attrition of healthcare knowledge workforce in northern parts of India that have a wide gradient of rural and urban belt, taking into account both public and private healthcare organizations. For this purpose healthcare professional attrition tracking survey (HATS was designed. The data has been collected from a random sample of 807 respondents consisting of doctors, nurses, paramedics and administrators to explore the relationships between various factors acting as antecedents in affecting the job satisfaction, commitment and intention of a healthcare professional to stay in the job. Structured questionnaires were utilized as the data collection tools. Descriptive statistics, factor analysis and path analysis were carried out using multiple regression and correlation to propose a model that best explains the theoretical assumption of factors leading to attrition. Six factors of attrition namely compensation and perks, work life balance, sense of accomplishment, work load, need for automation and technology improvement, substandard nature of work have been identified as the main factors with a data reliability of 0.809%. It has also been identified that the intention to shift is a major decision maker that affects attrition and in turn affected by job satisfaction dimensions. Based on the survey response and analysis, a highly possible strategy of utilizing information technology implementation for increasing worker motivation, job satisfaction and commitment to reduce attrition has been

  18. Introduction to State Estimation of High-Rate System Dynamics.

    Science.gov (United States)

    Hong, Jonathan; Laflamme, Simon; Dodson, Jacob; Joyce, Bryan

    2018-01-13

    Engineering systems experiencing high-rate dynamic events, including airbags, debris detection, and active blast protection systems, could benefit from real-time observability for enhanced performance. However, the task of high-rate state estimation is challenging, in particular for real-time applications where the rate of the observer's convergence needs to be in the microsecond range. This paper identifies the challenges of state estimation of high-rate systems and discusses the fundamental characteristics of high-rate systems. A survey of applications and methods for estimators that have the potential to produce accurate estimations for a complex system experiencing highly dynamic events is presented. It is argued that adaptive observers are important to this research. In particular, adaptive data-driven observers are advantageous due to their adaptability and lack of dependence on the system model.

  19. Processing of high-temperature superconductors at high strain rates

    International Nuclear Information System (INIS)

    Mamalis, A.G.; Pantazsopoulos, G.; Manolakos, D.E.; Szalay, A.

    2000-01-01

    This new book provides, for the first time, a systematic, unified presentation of all steps in the processing of high-temperature superconductor materials, ranging from synthesis of various systems to fabrication and industrial applications. Also covered are characterization techniques and current directions in research and development. The authors are leading specialists who bring to this new book their many years of experience in research, education and industrial engineering work in superconductor materials. This book is primarily focused on the bulk-fabrication techniques of high-temperature ceramic superconducting components, especially on the combination of dynamic powder-consolidation and subsequent deformation processing. The properties of these ceramics, which are difficult-to-form materials by applying conventional techniques, are combined for the net-shape manufacturing of such components for the construction of HTS deviceshor e llipsis. However, very important topics such as superconducting structures, chemical synthesis, film fabrication and characterization techniques are also reviewedhor e llipsis to provide a complete, comprehensive view of superconductors engineering

  20. High dose rate brachytherapy in treatment of high grade astrocytomas

    International Nuclear Information System (INIS)

    Garcia-Alejo, R.; Delgado, J.M.; Cerro, E. del; Torres, J.J.; Martinez, R.

    1996-01-01

    From May 1994 to June 1995, 18 patients with high grade astrocytomas were entered prospectively on a selective protocol combining surgery, external beam radiotherapy, stereotactic interstitial implantation with HDR Iridium 192 and chemotherapy. Only those patients with tumor size 100cc or less average dimension, high grade astrocytoma, Karnofsky 70 or greater, unilateral, circumscribed, unifocal, tumor stable or responding to external radiation and supratentorial were included in the study. Ages ranged from 16 to 69 years. There were 13 males and 5 females. Surgery consisted of biopsy only in 3 patients, subtotal resection in 11, and gross total resection in 4 patients. Focal external beam radiation portals included the contrast enhancing mass on CT scan plus a 3 cm margin. The protocol called for minimum tumor dose of 60 Gy to be given in 2 Gy daily fractions. An interstitial brachytherapy boost was to be performed two weeks after the conclusion of external beam radiation. The dose was 30 Gy in 4 fractions. The authors analyze on basis on their personal experience, the possibilities and the limits offered by this therapeutic procedure in neuro-oncology. Using stereotactic techniques, interstitial brachytherapy of brain tumors was technically possible with negligible acute morbidity and mortality, and appeared to be effective and may provide for an increase in tumor control in selected cases

  1. Predicting Active Duty Air Force Pilot Attrition Given an Anticipated Increase in Major Airline Pilot Hiring

    Science.gov (United States)

    2015-01-01

    the Air Force in addressing some quality-of-life issues, such as updating 3,800 family housing units, 21 dormitories, and building three child ...of pilots into the airlines (Air Force Personnel Center, FY 07). By allowing this crop of pilots to leave on the Air Force’s terms, the service felt...attrition rates compared with pilots with more general skills (flying mobility aircraft) (Stephen P. Barrows, 1993). This may be due to the phenomenon in

  2. Influence of attrition variables on iron ore flotation

    Directory of Open Access Journals (Sweden)

    Fabiana Fonseca Fortes

    Full Text Available Abstract The presence of slimes is harmful to the flotation process: the performance and consumption of reagents are negatively affected. Traditionally, the desliming stage has been responsible for removing slimes. However, depending on the porosity of the mineral particles, desliming may not be sufficient to maximize the concentration results. An attrition process before the desliming operation can improve the removal of slime, especially when slimes cover the surface and/or are confined to the cavities/pores of the mineral particles. Attrition is present in the flowcharts of the beneficiation process of phosphate and industrial sand (silica sand. Research has been undertaken for its application to produce pre-concentrates of zircon and iron ore. However, there is still little knowledge of the influence of the attrition variables on the beneficiation process of iron ore. This study presents a factorial design and analysis of the effects of these variables on the reverse flotation of iron ore. The standard of the experimental procedures for all tests included the attrition of pulp, under the conditions of dispersion, desliming and flotation. The parameter analysed (variable response was the metallurgical recovery in reverse flotation tests. The planning and analysis of the full factorial experiment indicated that with 95% reliability, the rotation speed of the attrition cell impeller was the main variable in the attrition process of the iron ore. The percentage of solid variables in the pulp and the time of the attrition, as well as their interactions, were not indicated to be significant.

  3. Quantum data locking for high-rate private communication

    International Nuclear Information System (INIS)

    Lupo, Cosmo; Lloyd, Seth

    2015-01-01

    We show that, if the accessible information is used as a security quantifier, quantum channels with a certain symmetry can convey private messages at a tremendously high rate, as high as less than one bit below the rate of non-private classical communication. This result is obtained by exploiting the quantum data locking effect. The price to pay to achieve such a high private communication rate is that accessible information security is in general not composable. However, composable security holds against an eavesdropper who is forced to measure her share of the quantum system within a finite time after she gets it. (paper)

  4. Effectiveness of high interest rate policy on exchange rates: A reexamination of the Asian financial crisis

    Directory of Open Access Journals (Sweden)

    Chin Diew Lai

    2006-09-01

    Full Text Available One of the most controversial issues in the aftermath of the Asian financial crisis has been the appropriate response of monetary policy to a sharp decline in the value of some currencies. In this paper, we empirically examine the effects on Asian exchange rates of sharply higher interest rates during the Asian financial crisis. Taking account of the currency contagion effect, our results indicate that sharply higher interest rates helped to support the exchange rates of South Korea, the Philippines, and Thailand. For Malaysia, no significant causal relation is found from the rate of interest to exchange rates, as the authorities in Malaysia did not actively adopt a high interest rate policy to defend the currency.

  5. How Did Successful High Schools Improve Their Graduation Rates?

    Science.gov (United States)

    Robertson, Janna Siegel; Smith, Robert W.; Rinka, Jason

    2016-01-01

    The researchers surveyed 23 North Carolina high schools that had markedly improved their graduation rates over the past five years. The administrators reported on the dropout prevention practices and programs to which they attributed their improved graduation rates. The majority of schools reported policy changes, especially with suspension. The…

  6. Factors associated with attrition, mortality, and loss to follow up after antiretroviral therapy initiation: data from an HIV cohort study in India

    Directory of Open Access Journals (Sweden)

    Gerardo Alvarez-Uria

    2013-09-01

    Full Text Available Background: Studies from sub-Saharan Africa have shown high incidence of attrition due to mortality or loss to follow-up (LTFU after initiating antiretroviral therapy (ART. India is the third largest country in the world in terms of HIV infected people, but predictors of attrition after ART initiation are not well known. Design: We describe factors associated with attrition, mortality, and LTFU in 3,159 HIV infected patients who initiated ART between 1 January 2007 and 4 November 2011 in an HIV cohort study in India. The study included 6,852 person-years with a mean follow-up of 2.17 years. Results: After 5 years of follow-up, the estimated cumulative incidence of attrition was 37.7%. There was no significant difference between attrition due to mortality and attrition due to LTFU. Having CD4 counts <100 cells/µl and being homeless [adjusted hazard ratio (aHR 3.1, 95% confidence interval (CI 2.6–3.8] were associated with a higher risk of attrition, and female gender (aHR 0.64, 95% CI 0.6–0.8 was associated with a reduced risk of attrition. Living near a town (aHR 0.82, 95% CI 0.7–0.999 was associated with a reduced risk of mortality. Being single (aHR 1.6, 95% CI 1.2–2.3, illiteracy (aHR 1.3, 95% CI 1.1–1.6, and age <25 years (aHR 1.3, 95% CI 1–1.8 were associated with an increased risk of LTFU. Although the cumulative incidence of attrition in patients diagnosed with tuberculosis after ART initiation was 47.4%, patients who started anti-tuberculous treatment before ART had similar attrition to patients without tuberculosis (36 vs. 35.2%, P=0.19 after four years of follow-up. Conclusions: In this cohort study, the attrition was similar to the one found in sub-Saharan Africa. Earlier initiation of ART, improving the diagnosis of tuberculosis before initiating ART, and giving more support to those patients at higher risk of attrition could potentially reduce the mortality and LTFU after ART initiation.

  7. Effect of high heating rate on thermal decomposition behaviour of ...

    Indian Academy of Sciences (India)

    the thermal decomposition behaviour of the aforementioned powder at high heating rates was taken into considera- ... does not change the process of releasing hydrogen from titanium hydride ... from titanium hydride in a sequence of steps.

  8. Treatment of the prostate cancer with high dose rate brachytherapy

    International Nuclear Information System (INIS)

    Martinez, Alvaro; Torres Silva, Felipe

    2002-01-01

    The prostate cancer treatment in early stages is controversial. The high dose rate brachytherapy has been used like monotherapy or boost with external beam radiotherapy in advanced disease. This paper describes the technique and the advantages over other modalities

  9. Effect of high heating rate on thermal decomposition behaviour of ...

    Indian Academy of Sciences (India)

    Effect of high heating rate on thermal decomposition behaviour of titanium hydride ... hydride powder, while switching it from internal diffusion to chemical reaction. ... TiH phase and oxides form on the powder surface, controlling the process.

  10. Influence of attrition scrubbing, ultrasonic treatment, and oxidant additions on uranium removal from contaminated soils

    International Nuclear Information System (INIS)

    Timpson, M.E.; Elless, M.P.; Francis, C.W.

    1994-01-01

    As part of the Uranium in Soils Integrated Demonstration Project being conducted by the US Department of Energy, bench-scale investigations of selective leaching of uranium from soils at the Fernald Environmental Management Project site in Ohio were conducted at Oak Ridge National Laboratory. Two soils (storage pad soil and incinerator soil), representing the major contaminant sources at the site, were extracted using carbonate- and citric acid-based lixiviants. Physical and chemical processes were used in combination with the two extractants to increase the rate of uranium release from these soils. Attrition scrubbing and ultrasonic dispersion were the two physical processes utilized. Potassium permanganate was used as an oxidizing agent to transform tetravalent uranium to the hexavalent state. Hexavalent uranium is easily complexed in solution by the carbonate radical. Attrition scrubbing increased the rate of uranium release from both soils when compared with rotary shaking. At equivalent extraction times and solids loadings, however, attrition scrubbing proved effective only on the incinerator soil. Ultrasonic treatments on the incinerator soil removed 71% of the uranium contamination in a single extraction. Multiple extractions of the same sample removed up to 90% of the uranium. Additions of potassium permanganate to the carbonate extractant resulted in significant changes in the extractability of uranium from the incinerator soil but had no effect on the storage pad soil

  11. Increased strength of concrete subject to high loading rates

    International Nuclear Information System (INIS)

    Curbach, M.

    1987-01-01

    Within the scope of this work various problems are discussed which occur in connection with concrete under high tensile loading rates (e.g. when a plane crashes on a nuclear power plant very high loads occur which act only for a very short time). Particularly the causes for the already frequently noticed increases in strength with increasing loading rates are investigated and also the question whether this increased strength can be taken into account when dimensioning a construction. (MM) [de

  12. Quantum Communication with a High-Rate Entangled Photon Source

    Science.gov (United States)

    Wilson, Nathaniel C.; Chaffee, Dalton W.; Lekki, John D.; Wilson, Jeffrey D.

    2016-01-01

    A high generation rate photon-pair source using a dual element periodically-poled potassium titanyl phosphate (PP KTP) waveguide is described. The photon-pair source features a high pair generation rate, a compact power-efficient package, and continuous wave (CW) or pulsed operation. Characterization and test results are presented. Details and preliminary results of a laboratory free-space QKD experiment with the B92 protocol are also presented.

  13. Attitudes towards attrition among UK trainees in obstetrics and gynaecology.

    Science.gov (United States)

    Gafson, Irene; Currie, Jane; O'Dwyer, Sabrina; Woolf, Katherine; Griffin, Ann

    2017-06-02

    Physician dissatisfaction in the workplace has consequences for patient safety. Currently in the UK, 1 in 5 doctors who enter specialist training in obstetrics and gynaecology leave the programme before completion. Trainee attrition has implications for workforce planning, organization of health-care services and patient care. The authors conducted a survey of current trainees' and former trainees' views concerning attrition and 'peri-attrition' - a term coined to describe the trainee who has seriously considered leaving the specialty. The authors identified six key themes which describe trainees' feelings about attrition in obstetrics and gynaecology: morale and undermining; training processes and paperwork; support and supervision; work-life balance and realities of life; NHS environment; and job satisfaction. This article discusses themes of an under-resourced health service, bullying, lack of work-life balance and poor personal support.

  14. Could Realistic Job Previews Reduce First-Term Attrition

    National Research Council Canada - National Science Library

    Brose, Gary

    1999-01-01

    .... The military's use of educational screens, trends and costs of first-term attrition, and labor market theories of turnover are discussed to provide a common frame of reference within which to view...

  15. Averting the Train Wreck of Captain Attrition - A Leadership Solution

    National Research Council Canada - National Science Library

    Weafer, Thomas

    2001-01-01

    .... This paper looks at officer attrition in the context of a leadership challenge - it examines current perceived problems in leadership culture and command climate and recommends several changes focused on improving morale and retention of young officers.

  16. Attitudes towards attrition among UK trainees in obstetrics and gynaecology

    OpenAIRE

    Gafson, I.; Currie, J.; O Dwyer, S.; Woolf, K.; Griffin, A.

    2017-01-01

    Physician dissatisfaction in the workplace has consequences for patient safety. Currently in the UK, 1 in 5 doctors who enter specialist training in obstetrics and gynaecology leave the programme before completion. Trainee attrition has implications for workforce planning, organization of health-care services and patient care. The authors conducted a survey of current trainees' and former trainees' views concerning attrition and ‘peri-attrition’ – a term coined to describe the trainee who has...

  17. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli

    Science.gov (United States)

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S.; Iguaz, Asunción; Periago, Paula M.; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  18. Posttreatment attrition and its predictors, attrition bias, and treatment efficacy of the anxiety online programs.

    Science.gov (United States)

    Al-Asadi, Ali M; Klein, Britt; Meyer, Denny

    2014-10-14

    Although relatively new, the field of e-mental health is becoming more popular with more attention given to researching its various aspects. However, there are many areas that still need further research, especially identifying attrition predictors at various phases of assessment and treatment delivery. The present study identified the predictors of posttreatment assessment completers based on 24 pre- and posttreatment demographic and personal variables and 1 treatment variable, their impact on attrition bias, and the efficacy of the 5 fully automated self-help anxiety treatment programs for generalized anxiety disorder (GAD), social anxiety disorder (SAD), panic disorder with or without agoraphobia (PD/A), obsessive-compulsive disorder (OCD), and posttraumatic stress disorder (PTSD). A complex algorithm was used to diagnose participants' mental disorders based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition, Text Revision; DSM-IV-TR). Those who received a primary or secondary diagnosis of 1 of 5 anxiety disorders were offered an online 12-week disorder-specific treatment program. A total of 3199 individuals did not formally drop out of the 12-week treatment cycle, whereas 142 individuals formally dropped out. However, only 347 participants who completed their treatment cycle also completed the posttreatment assessment measures. Based on these measures, predictors of attrition were identified and attrition bias was examined. The efficacy of the 5 treatment programs was assessed based on anxiety-specific severity scores and 5 additional treatment outcome measures. On average, completers of posttreatment assessment measures were more likely to be seeking self-help online programs; have heard about the program from traditional media or from family and friends; were receiving mental health assistance; were more likely to learn best by reading, hearing and doing; had a lower pretreatment Kessler-6 total score; and were older

  19. Why do faculty leave? Reasons for attrition of women and minority faculty from a medical school: four-year results.

    Science.gov (United States)

    Cropsey, Karen L; Masho, Saba W; Shiang, Rita; Sikka, Veronica; Kornstein, Susan G; Hampton, Carol L

    2008-09-01

    Faculty attrition, particularly among female and minority faculty, is a serious problem in academic medical settings. The reasons why faculty in academic medical settings choose to leave their employment are not well understood. Further, it is not clear if the reasons why women and minority faculty leave differ from those of other groups. One hundred sixty-six medical school faculty who left the School of Medicine (SOM) between July 1, 2001, and June 30, 2005, completed a survey about their reasons for leaving. The three most common overall reasons for leaving the institution included career/professional advancement (29.8%), low salary (25.5%), and chairman/departmental leadership issues (22.4%). The ranking of these reasons varied slightly across racial and gender groups, with women and minority faculty also citing personal reasons for leaving. Women and minority faculty were at lower academic ranks at the time they left the SOM compared with male and majority groups. Although salary differences were not present at the time of initial hire, sex was a significant predictor of lower salary at the start of the new position. Opportunity for advancement and the rate of promotion were significantly different between women and men. Job characteristics prior to leaving that were rated most poorly were protected time for teaching and research, communication across the campus, and patient parking. Harassment and discrimination were reported by a small number of those surveyed, particularly women and minority faculty. The majority of reasons for faculty attrition are amenable to change. Retaining high-quality faculty in medical settings may justify the costs of faculty development and retention efforts.

  20. Stretching of red blood cells at high strain rates

    Science.gov (United States)

    Mancuso, J. E.; Ristenpart, W. D.

    2017-10-01

    Most work on the mechanical behavior of red blood cells (RBCs) in flow has focused on simple shear flows. Relatively little work has examined RBC deformations in the physiologically important extensional flow that occurs at the entrance to a constriction. In particular, previous work suggests that RBCs rapidly stretch out and then retract upon entering the constriction, but to date no model predicts this behavior for the extremely high strain rates typically experienced there. In this Rapid Communication, we use high speed video to perform systematic measurements of the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We demonstrate that both the Kelvin-Voigt and Skalak viscoelastic models capture the observed stretching dynamics, up to strain rates as high as 2000 s-1. The results indicate that the effective elastic modulus of the RBC membrane at these strain rates is an order of magnitude larger than moduli measured by micropipette aspiration or other low strain rate techniques.

  1. Attrition, elutriation, and growth of particles produced in fluidized-bed waste calciners

    International Nuclear Information System (INIS)

    McDonald, F.N.

    1982-09-01

    The Idaho Chemical Processing Plant reduces the volume of high-level liquid radioactive wastes in a fluidized bed to produce a granular calcine product. In the past, difficulties have been experienced in controlling the product's particle size when processing certain blends of sodium-bearing waste. Therefore, experiments in attrition, elutriation, and particle growth were done to characterize how best to control these three parameters. 15 figures, 16 tables

  2. Solidification at the High and Low Rate Extreme

    Energy Technology Data Exchange (ETDEWEB)

    Meco, Halim [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The microstructures formed upon solidification are strongly influenced by the imposed growth rates on an alloy system. Depending on the characteristics of the solidification process, a wide range of growth rates is accessible. The prevailing solidification mechanisms, and thus the final microstructure of the alloy, are governed by these imposed growth rates. At the high rate extreme, for instance, one can have access to novel microstructures that are unattainable at low growth rates. While the low growth rates can be utilized for the study of the intrinsic growth behavior of a certain phase growing from the melt. Although the length scales associated with certain processes, such as capillarity, and the diffusion of heat and solute, are different at low and high rate extremes, the phenomena that govern the selection of a certain microstructural length scale or a growth mode are the same. Consequently, one can analyze the solidification phenomena at both high and low rates by using the same governing principles. In this study, we examined the microstructural control at both low and high extremes. For the high rate extreme, the formation of crystalline products and factors that control the microstructure during rapid solidification by free-jet melt spinning are examined in Fe-Si-B system. Particular attention was given to the behavior of the melt pool at different quench-wheel speeds. Since the solidification process takes place within the melt-pool that forms on the rotating quench-wheel, we examined the influence of melt-pool dynamics on nucleation and growth of crystalline solidification products and glass formation. High-speed imaging of the melt-pool, analysis of ribbon microstructure, and measurement of ribbon geometry and surface character all indicate upper and lower limits for melt-spinning rates for which nucleation can be avoided, and fully amorphous ribbons can be achieved. Comparison of the relevant time scales reveals that surface-controlled melt

  3. Pedalling rate affects endurance performance during high-intensity cycling

    DEFF Research Database (Denmark)

    Nielsen, Jens Steen; Hansen, Ernst Albin; Sjøgaard, Gisela

    2004-01-01

    The purpose of this study into high-intensity cycling was to: (1) test the hypothesis that endurance time is longest at a freely chosen pedalling rate (FCPR), compared to pedalling rates 25% lower (FCPR-25) and higher (FCPR+25) than FCPR, and (2) investigate how physiological variables......, and endurance time at W90 with FCPR-25, FCPR, and FCPR+25. Power reserve was calculated as the difference between applied power output at a given pedalling rate and peak crank power at this same pedalling rate. W90 was 325 (47) W. FCPR at W90 was 78 (11) rpm, resulting in FCPR-25 being 59 (8) rpm and FCPR+25...... time was negatively related to VO(2max), W90 and % MHC I, while positively related to power reserve. In conclusion, at group level, endurance time was longer at FCPR and at a pedalling rate 25% lower compared to a pedalling rate 25% higher than FCPR. Further, inter-individual physiological variables...

  4. Parents' Perceptions of Teacher Support at a Cyber Charter High School

    Science.gov (United States)

    Borup, Jered; Stevens, Mark A.

    2016-01-01

    Despite high growth rates, cyber charter schools experience higher attrition rates than their brick-and-mortar counterparts. Students' reasons for failing an online course are complex and students may require a high level of teacher support to be successful online. Research examining effective teacher engagement has relied heavily on teacher…

  5. Decay rate of the false vacuum at high temperatures

    International Nuclear Information System (INIS)

    Eboli, O.J.P.; Marques, G.C.

    1986-01-01

    We investigate, within the semiclassical approach, the high temperature behaviour of the decay rate (Γ) of the metastable vacuum in Field Theory. We exhibit some exactly soluble (1+1) and (3+1) dimensional examples and develop a formal expression for γ in the high temperature limit. (Author) [pt

  6. Authoritative School Climate and High School Dropout Rates

    Science.gov (United States)

    Jia, Yuane; Konold, Timothy R.; Cornell, Dewey

    2016-01-01

    This study tested the association between school-wide measures of an authoritative school climate and high school dropout rates in a statewide sample of 315 high schools. Regression models at the school level of analysis used teacher and student measures of disciplinary structure, student support, and academic expectations to predict overall high…

  7. High-repetition-rate short-pulse gas discharge.

    Science.gov (United States)

    Tulip, J; Seguin, H; Mace, P N

    1979-09-01

    A high-average-power short-pulse gas discharge is described. This consists of a volume-preionized transverse discharge of the type used in gas lasers driven by a Blumlein energy storage circuit. The Blumlein circuit is fabricated from coaxial cable, is pulse-charged from a high-repetition-rate Marx-bank generator, and is switched by a high-repetition-rate segmented rail gap. The operation of this discharge under conditions typical of rare-gas halide lasers is described. A maximum of 900 pps was obtained, giving a power flow into the discharge of 30 kW.

  8. Factors affecting the attrition of community-directed distributors of ivermectin, in an onchocerciasis-control programme in the Imo and Abia states of south-eastern Nigeria.

    Science.gov (United States)

    Emukah, E C; Enyinnaya, U; Olaniran, N S; Akpan, E A; Hopkins, D R; Miri, E S; Amazigo, U; Okoronkwo, C; Stanley, A; Rakers, L; Richards, F O; Katabarwa, M N

    2008-01-01

    In areas of Nigeria where onchocerciasis is endemic, community-directed distributors (CDD) distribute ivermectin annually, as part of the effort to control the disease. Unfortunately, it has been reported that at least 35% of the distributors who have been trained in Nigeria are unwilling to participate further as CDD. The selection and training of new CDD, to replace those unwilling to continue, leads to annual expense that the national onchocerciasis-programme is finding difficult to meet, given other programme priorities and the limited resources. If the reported levels of attrition are true, they seriously threaten the sustainability of community-directed treatment with ivermectin (CDTI) in Nigeria. In 2002, interviews were held with 101 people who had been trained as CDD, including those who had stopped serving their communities, from 12 communities in south-eastern Nigeria that had high rates of CDD attrition. The results showed that, although the overall reported CDD attrition was 40.6%, the actual rate was only 10.9%. The CDD who had ceased participating in the annual rounds of ivermectin blamed a lack of incentives (65.9%), the demands of other employment (14.6%), the long distances involved in the house-to-house distribution (12.2%) or marital duties (7.3%). Analysis of the data obtained from all the interviewed CDD showed that inadequate supplies of ivermectin (P<0.01), lack of supervision (P<0.05) and a lack of monetary incentives (P<0.001) led to significant increases in attrition. Conversely, CDD retention was significantly enhanced when the distributors were selected by their community members (P<0.001), supervised (P<0.001), supplied with adequate ivermectin tablets (P<0.05), involved in educating their community members (P<0.05), and/or involved in other health programmes (P<0.001). Although CDD who were involved in other health programmes were relatively unlikely to cease participating in the distributions, they were more likely to take longer

  9. Authoritative school climate and high school dropout rates.

    Science.gov (United States)

    Jia, Yuane; Konold, Timothy R; Cornell, Dewey

    2016-06-01

    This study tested the association between school-wide measures of an authoritative school climate and high school dropout rates in a statewide sample of 315 high schools. Regression models at the school level of analysis used teacher and student measures of disciplinary structure, student support, and academic expectations to predict overall high school dropout rates. Analyses controlled for school demographics of school enrollment size, percentage of low-income students, percentage of minority students, and urbanicity. Consistent with authoritative school climate theory, moderation analyses found that when students perceive their teachers as supportive, high academic expectations are associated with lower dropout rates. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  10. Evolution of high tooth replacement rates in sauropod dinosaurs.

    Science.gov (United States)

    D'Emic, Michael D; Whitlock, John A; Smith, Kathlyn M; Fisher, Daniel C; Wilson, Jeffrey A

    2013-01-01

    Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates. We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days). Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section. Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size), and derived titanosaurs and diplodocoids independently evolved the highest known tooth replacement rates among archosaurs.

  11. Evolution of high tooth replacement rates in sauropod dinosaurs.

    Directory of Open Access Journals (Sweden)

    Michael D D'Emic

    Full Text Available BACKGROUND: Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates. METHODOLOGY/PRINCIPAL FINDINGS: We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days. Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section. CONCLUSIONS/SIGNIFICANCE: Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size, and derived titanosaurs and

  12. Low dose rate and high dose rate intracavitary treatment for cervical cancer

    International Nuclear Information System (INIS)

    Hareyama, Masato; Oouchi, Atsushi; Shidou, Mitsuo

    1997-01-01

    From 1984 through 1993, 144 previous untreated patients with carcinoma of uterine cervix were treated with either low dose rate 137 Cs therapy (LDR) or high dose rate 60 Co therapy (HDR). The local failure rates for more than 2-years for the primary lesions were 11.8% (8 of 63 patients) for LDR and 18.0% (11 of 61 patients). Rectal complication rates were significantly lower for HDR versus LDR (14.3% VS. 32.8%. p<0.01). Also, bladder complication rates were significantly lower for HDR versus LDR (0% VS. 10.4%, p<0.005). Treatment results in term of local control were equivalent for HDR and LDR treatment. However, the incidence of complications was higher for the LDR group than for the HDR group. (author)

  13. Measurement of viscosity of slush at high shear rates

    OpenAIRE

    小林, 俊一; 川村, 公之; 津川, 圭一; 和泉, 薫; Kobayashi, Shun'ichi; Kawamura, Kimiyuki; Tugawa, Keiichi; Izumi, Kaoru

    1988-01-01

    Measurements of viscosity of slush were carried out using a method of flow along an inclined smooth surface in a 0℃cold room. The method was used to get the values of viscosity under high shear rates (25 and 75s^). From our experiments two important results were obtained: 1) the viscosity of slush decreases with increasing shear rates; 2) The fluid behavior is pseudoplastic that the values of non-Newtonian index of viscosity were less than unity.

  14. Radiobiological aspects of continuous low dose-rate irradiation and fractionated high dose-rate irradiation

    International Nuclear Information System (INIS)

    Turesson, I.

    1990-01-01

    The biological effects of continuous low dose-rate irradiation and fractionated high dose-rate irradiation in interstitial and intracavitary radiotherapy and total body irradiation are discussed in terms of dose-rate fractionation sensitivity for various tissues. A scaling between dose-rate and fraction size was established for acute and late normal-tissue effects which can serve as a guideline for local treatment in the range of dose rates between 0.02 and 0.005 Gy/min and fraction sizes between 8.5 and 2.5 Gy. This is valid provided cell-cycle progression and proliferation can be ignored. Assuming that the acute and late tissue responses are characterized by α/β values of about 10 and 3 Gy and a mono-exponential repair half-time of about 3 h, the same total doses given with either of the two methods are approximately equivalent. The equivalence for acute and late non-hemopoietic normal tissue damage is 0.02 Gy/min and 8.5 Gy per fraction; 0.01 Gy/min and 5.5 Gy per fraction; and 0.005 Gy/min and 2.5Gy per fraction. A very low dose rate, below 0.005 Gy/min, is thus necessary to simulate high dose-rate radiotherapy with fraction sizes of about 2Gy. The scaling factor is, however, dependent on the repair half-time of the tissue. A review of published data on dose-rate effects for normal tissue response showed a significantly stronger dose-rate dependence for late than for acute effects below 0.02 Gy/min. There was no significant difference in dose-rate dependence between various acute non-hemopoietic effects or between various late effects. The consistent dose-rate dependence, which justifies the use of a general scaling factor between fraction size and dose rate, contrasts with the wide range of values for repair half-time calculated for various normal-tissue effects. This indicates that the model currently used for repair kinetics is not satisfactory. There are also few experimental data in the clinical dose-rate range, below 0.02 Gy/min. It is therefore

  15. U.S. High School Graduation Rates: Patterns and Explanations

    OpenAIRE

    Richard J. Murnane

    2013-01-01

    I survey the evidence on patterns in U.S. high school graduation rates over the period 1970–2010 and report the results of new research conducted to fill in holes in the evidence. I begin by pointing out the strengths and limitations of existing data sources. I then describe six striking patterns in graduation rates. They include stagnation over the last three decades of the twentieth century, significant race-, income-, and gender-based gaps, and significant increases in graduation rates o...

  16. THE AMERICAN HIGH SCHOOL GRADUATION RATE: TRENDS AND LEVELS*

    Science.gov (United States)

    Heckman, James J.; LaFontaine, Paul A.

    2009-01-01

    This paper applies a unified methodology to multiple data sets to estimate both the levels and trends in U.S. high school graduation rates. We establish that (a) the true rate is substantially lower than widely used measures; (b) it peaked in the early 1970s; (c) majority/minority differentials are substantial and have not converged for 35 years; (d) lower post-1970 rates are not solely due to increasing immigrant and minority populations; (e) our findings explain part of the slowdown in college attendance and rising college wage premiums; and (f) widening graduation differentials by gender help explain increasing male-female college attendance gaps. PMID:20625528

  17. THE AMERICAN HIGH SCHOOL GRADUATION RATE: TRENDS AND LEVELS.

    Science.gov (United States)

    Heckman, James J; Lafontaine, Paul A

    2010-05-01

    This paper applies a unified methodology to multiple data sets to estimate both the levels and trends in U.S. high school graduation rates. We establish that (a) the true rate is substantially lower than widely used measures; (b) it peaked in the early 1970s; (c) majority/minority differentials are substantial and have not converged for 35 years; (d) lower post-1970 rates are not solely due to increasing immigrant and minority populations; (e) our findings explain part of the slowdown in college attendance and rising college wage premiums; and (f) widening graduation differentials by gender help explain increasing male-female college attendance gaps.

  18. A review of reaction rates in high temperature air

    Science.gov (United States)

    Park, Chul

    1989-01-01

    The existing experimental data on the rate coefficients for the chemical reactions in nonequilibrium high temperature air are reviewed and collated, and a selected set of such values is recommended for use in hypersonic flow calculations. For the reactions of neutral species, the recommended values are chosen from the experimental data that existed mostly prior to 1970, and are slightly different from those used previously. For the reactions involving ions, the recommended rate coefficients are newly chosen from the experimental data obtained more recently. The reacting environment is assumed to lack thermal equilibrium, and the rate coefficients are expressed as a function of the controlling temperature, incorporating the recent multitemperature reaction concept.

  19. High rate tests of the LHCb RICH Upgrade system

    CERN Multimedia

    Blago, Michele Piero

    2016-01-01

    One of the biggest challenges for the upgrade of the LHCb RICH detectors from 2020 is to readout the photon detectors at the full 40 MHz rate of the LHC proton-proton collisions. A test facility has been setup at CERN with the purpose to investigate the behaviour of the Multi Anode PMTs, which have been proposed for the upgrade, and their readout electronics at high trigger rates. The MaPMTs are illuminated with a monochromatic laser that can be triggered independently of the readout electronics. A first series of tests, including threshold scans, is performed at low trigger rates (20 kHz) for both the readout and the laser with the purpose to characterise the behaviour of the system under test. Then the trigger rate is increased in two separate steps. First the MaPMTs are exposed to high illumination by triggering the pulsed laser at a high (20 MHz) repetition rate while the DAQ is readout at the same low rate as before. In this way the performance of the MaPMTs and the attached electronics can be evaluated ...

  20. Semi-solid electrodes having high rate capability

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Yet-Ming; Duduta, Mihai; Holman, Richard; Limthongkul, Pimpa; Tan, Taison

    2017-11-28

    Embodiments described herein relate generally to electrochemical cells having high rate capability, and more particularly to devices, systems and methods of producing high capacity and high rate capability batteries having relatively thick semi-solid electrodes. In some embodiments, an electrochemical cell includes an anode, a semi-solid cathode that includes a suspension of an active material and a conductive material in a liquid electrolyte, and an ion permeable membrane disposed between the anode and the cathode. The semi-solid cathode has a thickness in the range of about 250 .mu.m-2,500 .mu.m, and the electrochemical cell has an area specific capacity of at least 5 mAh/cm.sup.2 at a C-rate of C/2.

  1. Effect of acidity upon attrition-corrosion of human dental enamel.

    Science.gov (United States)

    Wu, Yun-Qi; Arsecularatne, Joseph A; Hoffman, Mark

    2015-04-01

    Attrition-corrosion is a synthesized human enamel wear process combined mechanical effects (attrition) with corrosion. With the rising consumption of acidic food and beverages, attrition-corrosion is becoming increasingly common. Yet, research is limited and the underlying mechanism remains unclear. In this study, in vitro wear loss of human enamel was investigated and the attrition-corrosion process and wear mechanism were elucidated by the analysis of the wear scar and its subsurface using focused ion beam (FIB) sectioning and scanning electron microscopy (SEM). Human enamel flat-surface samples were prepared with enamel cusps as the wear antagonists. Reciprocating wear testing was undertaken under load of 5N at the speed of 66 cycle/min for 2250 cycles with lubricants including citric acid (at pH 3.2 and 5.5), acetic acid (at pH 3.2 and 5.5) and distilled water. All lubricants were used at 37°C. Similar human enamel flat-surface samples were also exposed to the same solutions as a control group. The substance loss of enamel during wear can be linked to the corrosion potential of a lubricant used. Using a lubricant with very low corrosion potential (such as distilled water), the wear mechanism was dominated by delamination with high wear loss. Conversely, the wear mechanism changed to shaving of the softened layer with less material loss in an environment with medium corrosion potential such as citric acid at pH 3.2 and 5.5 and acetic acid at pH 5.5. However, a highly corrosive environment (e.g., acetic acid at pH 3.2) caused the greatest loss of substance during wear. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Computational toxicology: Its essential role in reducing drug attrition.

    Science.gov (United States)

    Naven, R T; Louise-May, S

    2015-12-01

    Predictive toxicology plays a critical role in reducing the failure rate of new drugs in pharmaceutical research and development. Despite recent gains in our understanding of drug-induced toxicity, however, it is urgent that the utility and limitations of our current predictive tools be determined in order to identify gaps in our understanding of mechanistic and chemical toxicology. Using recently published computational regression analyses of in vitro and in vivo toxicology data, it will be demonstrated that significant gaps remain in early safety screening paradigms. More strategic analyses of these data sets will allow for a better understanding of their domain of applicability and help identify those compounds that cause significant in vivo toxicity but which are currently mis-predicted by in silico and in vitro models. These 'outliers' and falsely predicted compounds are metaphorical lighthouses that shine light on existing toxicological knowledge gaps, and it is essential that these compounds are investigated if attrition is to be reduced significantly in the future. As such, the modern computational toxicologist is more productively engaged in understanding these gaps and driving investigative toxicology towards addressing them. © The Author(s) 2015.

  3. The management of over closured anterior teeth due to attrition

    Directory of Open Access Journals (Sweden)

    Eha Djulaeha

    2009-12-01

    Full Text Available Background: Tooth is the hardest tissue in human body, that can be injured because of attrition process. For old people, denture attrition process is caused by psysiological process relating with the mastication function which also supported by some bad habits such an bruxism, premature contact, and consuming habit of abrasive food. Attrition or abrasion can also be happened with patien’t dentition who does not have teeth subtutition for long time due the lost of their maxillary as well as mandibulary. The pasient will loose their vertical dimension of occlusion, injure, and the lower jaw becomes over closed which is called over closure. Purpose: This article reported the management of over closured anterior teeth due to attrition. Case: a seventy six year old woman patient came to Prosthodontic Clinic in Faculty of Dentistry, Airlangga University, to rehabilitate her upper and lower severe attrited anterior teeth and her posterior teeth. The patient has experienced of wearing acrylic removable mandibular partial denture ten years ago. Unfortunaly, the denture was uncomfortable, and she did not wear it anymore since five years ago. Case management: The severe attrition of anterior teeth with the lost of occlusal vertical dimension can be treated by improving the occlusal vertical dimension gradually. The treatment is then followed by the increasing of the height of the anterior teeth by lengthening the crown teeth of upper jaw with 12 units of span bridge and the acrylic removable partial denture of lower jaw. Conclusion: The severe attrition of anterior teeth with the lost of occlusal vertical dimension can be treated by improving the occlusal vertical dimension gradually, using long span bridge and acrylic removable partial denture.

  4. High-rate performance of muon drift tube detectors

    International Nuclear Information System (INIS)

    Schwegler, Philipp

    2014-01-01

    The Large Hadron Collider (LHC) at the European Centre for Particle Physics, CERN, collides protons with an unprecedentedly high centre-of-mass energy and luminosity. The collision products are recorded and analysed by four big experiments, one of which is the ATLAS detector. In parallel with the first LHC run from 2009 to 2012, which culminated in the discovery of the last missing particle of the Standard Model of particle physics, the Higgs boson, planning of upgrades of the LHC for higher instantaneous luminosities (HL-LHC) is already progressing. The high instantaneous luminosity of the LHC puts high demands on the detectors with respect to radiation hardness and rate capability which are further increased with the luminosity upgrade. In this thesis, the limitations of the Muon Drift Tube (MDT) chambers of the ATLAS Muon Spectrometer at the high background counting rates at the LHC and performance of new small diameter muon drift tube (sMDT) detectors at the even higher background rates at HL-LHC are studied. The resolution and efficiency of sMDT chambers at high γ-ray and proton irradiation rates well beyond the ones expected at HL-LHC have been measured and the irradiation effects understood using detailed simulations. The sMDT chambers offer an about an order of magnitude better rate capability and are an ideal replacement for the MDT chambers because of compatibility of services and read-out. The limitations of the sMDT chambers are now in the read-out electronics, taken from the MDT chambers, to which improvements for even higher rate capability are proposed.

  5. High Strain Rate Tensile Testing of Silver Nanowires: Rate-Dependent Brittle-to-Ductile Transition.

    Science.gov (United States)

    Ramachandramoorthy, Rajaprakash; Gao, Wei; Bernal, Rodrigo; Espinosa, Horacio

    2016-01-13

    The characterization of nanomaterials under high strain rates is critical to understand their suitability for dynamic applications such as nanoresonators and nanoswitches. It is also of great theoretical importance to explore nanomechanics with dynamic and rate effects. Here, we report in situ scanning electron microscope (SEM) tensile testing of bicrystalline silver nanowires at strain rates up to 2/s, which is 2 orders of magnitude higher than previously reported in the literature. The experiments are enabled by a microelectromechanical system (MEMS) with fast response time. It was identified that the nanowire plastic deformation has a small activation volume (ductile failure mode transition was observed at a threshold strain rate of 0.2/s. Transmission electron microscopy (TEM) revealed that along the nanowire, dislocation density and spatial distribution of plastic regions increase with increasing strain rate. Furthermore, molecular dynamic (MD) simulations show that deformation mechanisms such as grain boundary migration and dislocation interactions are responsible for such ductility. Finally, the MD and experimental results were interpreted using dislocation nucleation theory. The predicted yield stress values are in agreement with the experimental results for strain rates above 0.2/s when ductility is pronounced. At low strain rates, random imperfections on the nanowire surface trigger localized plasticity, leading to a brittle-like failure.

  6. Attrition and bias in the MRC cognitive function and ageing study: an epidemiological investigation

    Directory of Open Access Journals (Sweden)

    Matthews Fiona E

    2004-04-01

    Full Text Available Abstract Background Any hypothesis in longitudinal studies may be affected by attrition and poor response rates. The MRC Cognitive Function and Ageing study (MRC CFAS is a population based longitudinal study in five centres with identical methodology in England and Wales each recruiting approximately 2,500 individuals. This paper aims to identify potential biases in the two-year follow-up interviews. Methods Initial non-response: Those not in the baseline interviews were compared in terms of mortality to those who were in the baseline interviews at the time of the second wave interviews (1993–1996. Longitudinal attrition: Logistic regression analysis was used to examine baseline differences between individuals who took part in the two-year longitudinal wave compared with those who did not. Results Initial non-response: Individuals who moved away after sampling but before baseline interview were 1.8 times more likely to die by two years (95% Confidence interval(CI 1.3–2.4 compared to respondents, after adjusting for age. The refusers had a slightly higher, but similar mortality pattern to responders (Odds ratio 1.2, 95%CI 1.1–1.4. Longitudinal attrition: Predictors for drop out due to death were being older, male, having impaired activities of daily living, poor self-perceived health, poor cognitive ability and smoking. Similarly individuals who refused were more likely to have poor cognitive ability, but had less years of full-time education and were more often living in their own home though less likely to be living alone. There was a higher refusal rate in the rural centres. Individuals who moved away or were uncontactable were more likely to be single, smokers, demented or depressed and were less likely to have moved if in warden-controlled accommodation at baseline. Conclusions Longitudinal estimation of factors mentioned above could be biased, particularly cognitive ability and estimates of movements from own home to residential homes

  7. High data rate coding for the space station telemetry links.

    Science.gov (United States)

    Lumb, D. R.; Viterbi, A. J.

    1971-01-01

    Coding systems for high data rates were examined from the standpoint of potential application in space-station telemetry links. Approaches considered included convolutional codes with sequential, Viterbi, and cascaded-Viterbi decoding. It was concluded that a high-speed (40 Mbps) sequential decoding system best satisfies the requirements for the assumed growth potential and specified constraints. Trade-off studies leading to this conclusion are viewed, and some sequential (Fano) algorithm improvements are discussed, together with real-time simulation results.

  8. Predicting High Frequency Exchange Rates using Machine Learning

    OpenAIRE

    Palikuca, Aleksandar; Seidl,, Timo

    2016-01-01

    This thesis applies a committee of Artificial Neural Networks and Support Vector Machines on high-dimensional, high-frequency EUR/USD exchange rate data in an effort to predict directional market movements on up to a 60 second prediction horizon. The study shows that combining multiple classifiers into a committee produces improved precision relative to the best individual committee members and outperforms previously reported results. A trading simulation implementing the committee classifier...

  9. Decay rate of the false vacuum at high tempratures

    International Nuclear Information System (INIS)

    Eboli, O.J.P.; Marques, G.C.

    1984-01-01

    Within the semiclassical approach, the high temperaure behaviour of the decay rate of the metastable vacuum in Field Theory is investigated. It is shown that, contrarily to what has been proposed in the literature, the pre-exponential factor exhibits a nontrivial dependence on the temperature. Furthermore, this dependence is such that at very high temperatures it is as important as the exponential factor and consequently it spoils many conclusions drawn up to now on Cosmological Phase Transitions. (Author) [pt

  10. Electrophoretic Deposition of Gallium with High Deposition Rate

    Directory of Open Access Journals (Sweden)

    Hanfei Zhang

    2014-12-01

    Full Text Available In this work, electrophoretic deposition (EPD is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher than the typical value reported for electroplating, is obtained when employing a set of proper deposition parameters. The thickness of the film is shown to increase with deposition time when sequential deposition is employed. The concentration of Mg(NO32, the charging salt, is also found to be a critical factor to control the deposition rate. Various gallium micropatterns are obtained by masking the substrate during the process, demonstrating process compatibility with microfabrication. The reported novel approach can potentially be employed in a broad range of applications with Ga as a raw material, including microelectronics, photovoltaic cells, and flexible liquid metal microelectrodes.

  11. READOUT ELECTRONICS FOR A HIGH-RATE CSC DETECTOR

    International Nuclear Information System (INIS)

    OCONNOR, P.; GRATCHEV, V.; KANDASAMY, A.; POLYCHRONAKOS, V.; TCHERNIATINE, V.; PARSONS, J.; SIPPACH, W.

    1999-01-01

    A readout system for a high-rate muon Cathode Strip Chamber (CSC) is described. The system, planned for use in the forward region of the ATLAS muon spectrometer, uses two custom CMOS integrated circuits to achieve good position resolution at a flux of up to 2,500 tracks/cm 2 /s

  12. Digital approach to high rate gamma-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Korolczuk, Stefan; Mianowski, Slawomir; Rzadkiewicz, Jacek; Sibczynski, Pawel; Swiderski, Lukasz; Szewinski, Jaroslaw; Zychor, Izabella [Narodowe Centrum Badan Jadrowych (NCBJ), 05-400 Otwock, (Poland)

    2015-07-01

    Basic concepts and preliminary results of creating high rate digital spectrometry system using efficient ADCs and latest FPGA are presented as well as a comparison with commercially available devices. The possibility to use such systems, coupled to scintillators, in plasma experiments is discussed. (authors)

  13. High rate of teenage pregnancy and sexually transmitted infections ...

    African Journals Online (AJOL)

    There is increased in teenage pregnancy despite the presence of dual protection practice and health care awareness programmes related to health and sexuality education in South Africa. The present study explores the underlying causes of high teenage pregnancy and sexually transmitted diseases rates, including HIV ...

  14. Twinning in copper deformed at high strain rates

    Indian Academy of Sciences (India)

    Abstract. Copper samples having varying microstructures were deformed at high strain rates using a split-. Hopkinson pressure bar. Transmission electron microscopy results show deformation twins present in samples that were both annealed and strained, whereas samples that were annealed and left unstrained, as well ...

  15. High Frame Rate Synthetic Aperture 3D Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Holbek, Simon; Stuart, Matthias Bo

    2016-01-01

    , current volumetric ultrasonic flow methods are limited to one velocity component or restricted to a reduced field of view (FOV), e.g. fixed imaging planes, in exchange for higher temporal resolutions. To solve these problems, a previously proposed accurate 2-D high frame rate vector flow imaging (VFI...

  16. Sphaleron rate at high temperature in 1+1 dimensions

    International Nuclear Information System (INIS)

    Smit, Jan; Tang, W.H.

    1999-01-01

    We resolve the controversy in the high temperature behavior of the sphaleron rate in the abelian Higgs model in 1+1 dimensions. The T 2 behavior at intermediate lattice spacings is found to change into T ((2)/(3)) behavior in the continuum limit. The results are supported by analytic arguments that the classical approximation is good for this model

  17. Attrition, occlusion, (dys)function, and intervention: a systematic review.

    Science.gov (United States)

    van 't Spijker, Arie; Kreulen, Cees M; Creugers, Nico H J

    2007-06-01

    Attrition and occlusal factors and masticatory function or dysfunction are thought to be related. This study aims to systematically review the literature on this topic with the emphasis to find evidence for occlusion-based treatment protocols for attrition. Literature was searched using PubMed (1980 to 2/2006) and the Cochrane Library of Clinical Trials with the keywords 'tooth' and 'wear'. Five steps were followed. Exclusion was based on the following: (1) reviews, case-reports, studies on non-human tooth material, and studies not published in English and (2) historical or forensic studies. Included were (3) in vivo studies. Next, studies on (4) occlusal factors, function or dysfunction [temporomandibular disorders (TMD), bruxism], or intervention, and (5) attrition were included. Two investigators independently assessed the abstracts; measure of agreement was calculated using Cohen's kappa; disagreement was resolved by discussion. Full-text articles were obtained and correlation between outcomes on occlusal factors, (dys)function, treatment, and attrition were retrieved. References in the papers included in the final analysis were cross-matched with the original list of references to add references that met the inclusion criteria. The search procedure revealed 1289 references on tooth wear. The numbers of included studies after each step were (1) 345 (kappa=0.8), (2) 287 (kappa=0.87), (3) 174 (kappa=0.99), (4) 81 (kappa=0.71), and (5) 27 (kappa=0.68). Hand searches through the reference lists revealed six additional papers to be included. Analysis of the 33 included papers failed to find sound evidence for recommending a certain occlusion-based treatment protocol above another in the management of attrition. Some studies reported correlations between attrition and anterior spatial relationships. No studies were found suggesting that absent posterior support necessarily leads to increased attrition, though one study found that fewer number of teeth resulted in

  18. High production rate of IBAD-MgO buffered substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizumi, M., E-mail: myoshizumi@istec.or.j [Superconductivity Research Laboratory, ISTEC, Shinonome 1-10-13, Koto-ku, Tokyo 135-0062 (Japan); Miyata, S.; Ibi, A.; Fukushima, H.; Yamada, Y.; Izumi, T.; Shiohara, Y. [Superconductivity Research Laboratory, ISTEC, Shinonome 1-10-13, Koto-ku, Tokyo 135-0062 (Japan)

    2009-10-15

    The conventional IBAD (Ion Beam Assisted Deposition) process using fluorite materials yields low production rates, resulting in high production cost, which reduces the motivation for practical application in spite of its high quality. The IBAD process using rock salt materials, e.g. MgO, is well known as a strong candidate of practical application due to its potential of high production rate and high in-plane grain alignment. In this work, the IBAD-MgO process was investigated for a newly developed architecture of PLD (Pulsed Laser Deposition)-CeO{sub 2}/sputter-LMO (LaMnO{sub 3})/IBAD-MgO/sputter-GZO (Gd{sub 2}Zr{sub 2}O{sub 7})/Hastelloy{sup TM} to make long buffered metal tapes with high properties and a high production rate. The 50 m-long IBAD-MgO substrates with about 4 deg. of DELTAphiCeO{sub 2} in an XRD phi scan could be fabricated repeatedly. A GdBCO (GdBa{sub 2}Cu{sub 3}O{sub x}) layer deposited on the buffered substrate showed the minimum I{sub c} value of 325 A/cm-w in a 41 m-long tape. Almost of the tape showed 500-600 A/cm-w of I{sub c} value. The deposition time for the IBAD-MgO layer was 60 s which was about 2 orders of magnitude shorter than the conventional IBAD process. The production rate of 24 m/h was realized at the IBAD-MgO process to fabricate the GdBCO coated conductor with high J{sub c} and I{sub c} properties.

  19. Australian aboriginal tooth succession, interproximal attrition, and Begg's theory.

    Science.gov (United States)

    Corruccini, R S

    1990-04-01

    In 1954, P.R. Begg analyzed interproximal attrition as a prehistorically universal mechanism to reduce tooth size. With modern processed diets and the virtual disappearance of constant interproximal attrition, Begg asserted, teeth remain too large for the arches and become crowded. Later investigators have questioned Begg's estimate of attritional tooth-size reduction, as well as aspects of his theory relating the succession sequence of permanent teeth to different malocclusions. The present paper examines the theory using longitudinal casts and records of modern Australian aborigines who are among the first generation lacking notable interproximal attrition thanks to a "modernized" diet. Deciduous and permanent tooth size, arch size, and occlusal relational variables were analyzed with respect to the expected occlusal outcomes in the absence of attritional tooth reduction. Permanent incisor overjet correlated with crowding status, as predicted by Begg. On the other hand, longer teeth did not relate to crowding in general nor to crowding in relevant local areas or during developmental stages. Unfavorable leeway space did not relate clearly to crowding or other malocclusions. Lowered correlations among structures and narrowness of the maxilla related more significantly to malocclusion. These results are in keeping with recent thinking that small jaws rather than large teeth underlie tooth/arch discrepancy.

  20. Physical nature of strain rate sensitivity of metals and alloys at high strain rates

    Science.gov (United States)

    Borodin, E. N.; Gruzdkov, A. A.; Mayer, A. E.; Selyutina, N. S.

    2018-04-01

    The role of instabilities of plastic flow at plastic deformation of various materials is one of the important cross-disciplinary problems which is equally important in physics, mechanics and material science. The strain rate sensitivities under slow and high strain rate conditions of loading have different physical nature. In the case of low strain rate, the sensitivity arising from the inertness of the defect structures evolution can be expressed by a single parameter characterizing the plasticity mechanism. In our approach, this is the value of the characteristic relaxation time. In the dynamic case, there are additional effects of “high-speed sensitivity” associated with the micro-localization of the plastic flow near the stress concentrators. In the frames of mechanical description, this requires to introduce additional strain rate sensitivity parameters, which is realized in numerous modifications of Johnson–Cook and Zerilli–Armstrong models. The consideration of both these factors is fundamental for an adequate description of the problems of dynamic deformation of highly inhomogeneous metallic materials such as steels and alloys. The measurement of the dispersion of particle velocities on the free surface of a shock-loaded material can be regarded as an experimental expression of the effect of micro-localization. This is also confirmed by our results of numerical simulation of the propagation of shock waves in a two-dimensional formulation and analytical estimations.

  1. Radiation shielding and dose rate distribution for the building of the high dose rate accelerator

    International Nuclear Information System (INIS)

    Matsuda, Koji; Takagaki, Torao; Nakase, Yoshiaki; Nakai, Yohta.

    1984-03-01

    A high dose rate electron accelerator was established at Osaka Laboratory for Radiation Chemistry, Takasaki Establishment, JAERI in the fiscal year of 1975. This report shows the fundamental concept for the radiation shielding of the accelerator building and the results of their calculations which were evaluated through the model experiments. After the construction of the building, the leak radiation was measured in order to evaluate the calculating method of radiation shielding. Dose rate distribution of X-rays was also measured in the whole area of the irradiation room as a data base. (author)

  2. High strain-rate soft material characterization via inertial cavitation

    Science.gov (United States)

    Estrada, Jonathan B.; Barajas, Carlos; Henann, David L.; Johnsen, Eric; Franck, Christian

    2018-03-01

    Mechanical characterization of soft materials at high strain-rates is challenging due to their high compliance, slow wave speeds, and non-linear viscoelasticity. Yet, knowledge of their material behavior is paramount across a spectrum of biological and engineering applications from minimizing tissue damage in ultrasound and laser surgeries to diagnosing and mitigating impact injuries. To address this significant experimental hurdle and the need to accurately measure the viscoelastic properties of soft materials at high strain-rates (103-108 s-1), we present a minimally invasive, local 3D microrheology technique based on inertial microcavitation. By combining high-speed time-lapse imaging with an appropriate theoretical cavitation framework, we demonstrate that this technique has the capability to accurately determine the general viscoelastic material properties of soft matter as compliant as a few kilopascals. Similar to commercial characterization algorithms, we provide the user with significant flexibility in evaluating several constitutive laws to determine the most appropriate physical model for the material under investigation. Given its straightforward implementation into most current microscopy setups, we anticipate that this technique can be easily adopted by anyone interested in characterizing soft material properties at high loading rates including hydrogels, tissues and various polymeric specimens.

  3. Miniaturized Stretchable and High-Rate Linear Supercapacitors

    Science.gov (United States)

    Zhu, Wenjun; Zhang, Yang; Zhou, Xiaoshuang; Xu, Jiang; Liu, Zunfeng; Yuan, Ningyi; Ding, Jianning

    2017-07-01

    Linear stretchable supercapacitors have attracted much attention because they are well suited to applications in the rapidly expanding field of wearable electronics. However, poor conductivity of the electrode material, which limits the transfer of electrons in the axial direction of the linear supercapacitors, leads to a serious loss of capacity at high rates. To solve this problem, we use gold nanoparticles to decorate aligned multiwall carbon nanotube to fabricate stretchable linear electrodes. Furthermore, we have developed fine stretchable linear supercapacitors, which exhibited an extremely high elasticity up to 400% strain with a high capacitance of about 8.7 F g-1 at the discharge current of 1 A g-1.

  4. HIGH-RATE ANAEROBIC TREATMENT OF ALCOHOLIC WASTEWATERS

    Directory of Open Access Journals (Sweden)

    Florencio L.

    1997-01-01

    Full Text Available Modern high-rate anaerobic wastewater treatment processes are rapidly becoming popular for industrial wastewater treatment. However, until recently stable process conditions could not be guaranteed for alcoholic wastewaters containing higher concentrations of methanol. Although methanol can be directly converted into methane by methanogens, under specific conditions it can also be converted into acetate and butyrate by acetogens. The accumulation of volatile fatty acids can lead to reactor instability in a weakly buffered reactor. Since this process was insufficiently understood, the application of high-rate anaerobic reactors was highly questionable. This research investigated the environmental factors that are of importance in the predominance of methylotrophic methanogens over acetogens in a natural mixed culture during anaerobic wastewater treatment in upflow anaerobic sludge bed reactors. Technological and microbiological aspects were investigated. Additionally, the route by which methanol is converted into methane is also presented

  5. Spallation model for the high strain rates range

    Science.gov (United States)

    Dekel, E.; Eliezer, S.; Henis, Z.; Moshe, E.; Ludmirsky, A.; Goldberg, I. B.

    1998-11-01

    Measurements of the dynamic spall strength in aluminum and copper shocked by a high power laser to pressures of hundreds of kbars show a rapid increase in the spall strength with the strain rate at values of about 107 s-1. We suggest that this behavior is a result of a change in the spall mechanism. At low strain rates the spall is caused by the motion and coalescence of material's initial flaws. At high strain rates there is not enough time for the flaws to move and the spall is produced by the formation and coalescence of additional cavities where the interatomic forces become dominant. Material under tensile stress is in a metastable condition and cavities of a critical radius are formed in it due to thermal fluctuations. These cavities grow due to the tension. The total volume of the voids grow until the material disintegrates at the spall plane. Simplified calculations based on this model, describing the metal as a viscous liquid, give results in fairly good agreement with the experimental data and predict the increase in spall strength at high strain rates.

  6. Highly variable rates of genome rearrangements between hemiascomycetous yeast lineages.

    Directory of Open Access Journals (Sweden)

    2006-03-01

    Full Text Available Hemiascomycete yeasts cover an evolutionary span comparable to that of the entire phylum of chordates. Since this group currently contains the largest number of complete genome sequences it presents unique opportunities to understand the evolution of genome organization in eukaryotes. We inferred rates of genome instability on all branches of a phylogenetic tree for 11 species and calculated species-specific rates of genome rearrangements. We characterized all inversion events that occurred within synteny blocks between six representatives of the different lineages. We show that the rates of macro- and microrearrangements of gene order are correlated within individual lineages but are highly variable across different lineages. The most unstable genomes correspond to the pathogenic yeasts Candida albicans and Candida glabrata. Chromosomal maps have been intensively shuffled by numerous interchromosomal rearrangements, even between species that have retained a very high physical fraction of their genomes within small synteny blocks. Despite this intensive reshuffling of gene positions, essential genes, which cluster in low recombination regions in the genome of Saccharomyces cerevisiae, tend to remain syntenic during evolution. This work reveals that the high plasticity of eukaryotic genomes results from rearrangement rates that vary between lineages but also at different evolutionary times of a given lineage.

  7. Precise muon drift tube detectors for high background rate conditions

    Energy Technology Data Exchange (ETDEWEB)

    Engl, Albert

    2011-08-04

    The muon spectrometer of the ATLAS-experiment at the Large Hadron Collider consists of drift tube chambers, which provide the precise measurement of trajectories of traversing muons. In order to determine the momentum of the muons with high precision, the measurement of the position of the muon in a single tube has to be more accurate than {sigma}{<=}100 {mu}m. The large cross section of proton-proton-collisions and the high luminosity of the accelerator cause relevant background of neutrons and {gamma}s in the muon spectrometer. During the next decade a luminosity upgrade to 5.10{sup 34} cm{sup -2}s{sup -1} is planned, which will increase the background counting rates considerably. In this context this work deals with the further development of the existing drift chamber technology to provide the required accuracy of the position measurement under high background conditions. Two approaches of improving the drift tube chambers are described: - In regions of moderate background rates a faster and more linear drift gas can provide precise position measurement without changing the existing hardware. - At very high background rates drift tube chambers consisting of tubes with a diameter of 15 mm are a valuable candidate to substitute the CSC muon chambers. The single tube resolution of the gas mixture Ar:CO{sub 2}:N{sub 2} in the ratio of 96:3:1 Vol %, which is more linear and faster as the currently used drift gas Ar:CO{sub 2} in the ratio of 97:3 Vol %, was determined at the Cosmic Ray Measurement Facility at Garching and at high {gamma}-background counting rates at the Gamma Irradiation Facility at CERN. The alternative gas mixture shows similar resolution without background. At high background counting rates it shows better resolution as the standard gas. To analyse the data the various parts of the setup have to be aligned precisely to each other. The change to an alternative gas mixture allows the use of the existing hardware. The second approach are drift tubes

  8. Iodine laser of high efficiency and fast repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Hohla, K; Witte, K J

    1976-07-01

    The scaling laws of an iodine laser of high efficiency and fast repetition rate are reported. The laser is pumped with a new kind of low pressure Hg-UV-lamps which convert 32% of the electrical input in UV-light in the absorption band of the iodine laser and which can be fired up to 100 Hz. Details of a 10 kJ/1 nsec system as dimensions, energy density, repetition rate, flow velocity, gas composition and gas pressure and the overall efficiency are given which is expected to be about 2%.

  9. Study of magnetorheological fluids at high shear rates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojie; Gordaninejad, Faramarz [University of Nevada, Department of Mechanical Engineering, Reno, NV (United States)

    2006-08-15

    The tunable rheological properties of magnetorheological (MR) materials at high shear rates are studied using a piston-driven flow-mode-type rheometer. The proposed method provides measurement of the apparent viscosity and yield stress of MR fluids for a shear rate range of 50 to 40,000 s{sup -1}. The rheological properties of a commercial MR fluid, as well as a newly developed MR polymeric gel, and a ferrofluid-based MR fluid are investigated. The results for apparent viscosity and dynamic and static shear stresses under different applied magnetic fields are reported. (orig.)

  10. Palaeohistological Evidence for Ancestral High Metabolic Rate in Archosaurs.

    Science.gov (United States)

    Legendre, Lucas J; Guénard, Guillaume; Botha-Brink, Jennifer; Cubo, Jorge

    2016-11-01

    Metabolic heat production in archosaurs has played an important role in their evolutionary radiation during the Mesozoic, and their ancestral metabolic condition has long been a matter of debate in systematics and palaeontology. The study of fossil bone histology provides crucial information on bone growth rate, which has been used to indirectly investigate the evolution of thermometabolism in archosaurs. However, no quantitative estimation of metabolic rate has ever been performed on fossils using bone histological features. Moreover, to date, no inference model has included phylogenetic information in the form of predictive variables. Here we performed statistical predictive modeling using the new method of phylogenetic eigenvector maps on a set of bone histological features for a sample of extant and extinct vertebrates, to estimate metabolic rates of fossil archosauromorphs. This modeling procedure serves as a case study for eigenvector-based predictive modeling in a phylogenetic context, as well as an investigation of the poorly known evolutionary patterns of metabolic rate in archosaurs. Our results show that Mesozoic theropod dinosaurs exhibit metabolic rates very close to those found in modern birds, that archosaurs share a higher ancestral metabolic rate than that of extant ectotherms, and that this derived high metabolic rate was acquired at a much more inclusive level of the phylogenetic tree, among non-archosaurian archosauromorphs. These results also highlight the difficulties of assigning a given heat production strategy (i.e., endothermy, ectothermy) to an estimated metabolic rate value, and confirm findings of previous studies that the definition of the endotherm/ectotherm dichotomy may be ambiguous. © The Author(s) 2016. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. High Data Rate Optical Wireless Communications Based on Ultraviolet Band

    KAUST Repository

    Sun, Xiaobin

    2017-10-01

    Optical wireless communication systems based on ultraviolet (UV)-band has a lot inherent advantages, such as low background solar radiation, low device dark noise. Besides, it also has small restrictive requirements for PAT (pointing, acquisition, and tracking) because of its high atmospheric scattering with molecules and aerosols. And these advantages are driving people to explore and utilize UV band for constructing and implementing a high-data-rate, less PAT communication links, such as diffuse-line-of-sight links (diffuse-LOS) and non-line-of-sight (NLOS). The responsivity of the photodetector at UV range is far lower than that of visible range, high power UV transmitters which can be easily modulated are under investigation. These factors make it is hard to realize a high-data-rate diffuse-LOS or NLOS UV communication links. To achieve a UV link mentioned above with current devices and modulation schemes, this thesis presents some efficient modulation schemes and available devices for the time being. Besides, a demonstration of ultraviolet-B (UVB) communication link is implemented utilizing quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM). The demonstration is based on a 294-nm UVB-light-emitting-diode (UVB-LED) with a full-width at half-maximum (FWHM) of 9 nm, and according to the measured L-I-V curve, we set the bias voltage as 7V for maximum the ac amplitude and thus get a high signal-noise-ratio (SNR) channel, and the light output power is 190 μW with such bias voltage. Besides, there is a unique silica gel lens on top of the LED to concentrate the beam. A -3-dB bandwidth of 29 MHz was measured and a high-speed near-solar-blind communication link with a data rate of 71 Mbit/s was achieved using 8-QAM-OFDM at perfect alignment, and 23.6 Mbit/s using 2-QAM-OFDM when the angle subtended by the pointing direction of the UVB-LED and photodetector (PD) is 12 degrees, thus establishing a diffuse-line-of-sight (LOS) link

  12. High-Rate Performance of Muon Drift Tube Detectors

    CERN Document Server

    Schwegler, Philipp

    The Large Hadron Collider (LHC) at the European Centre for Particle Physics, CERN, collides protons with an unprecedentedly high centre-of-mass energy and luminosity. The collision products are recorded and analysed by four big experiments, one of which is the ATLAS detector. In parallel with the first LHC run from 2009 to 2012, which culminated in the discovery of the last missing particle of the Standard Model of particle physics, the Higgs boson, planning of upgrades of the LHC for higher instantaneous luminosities (HL-LHC) is already progressing. The high instantaneous luminosity of the LHC puts high demands on the detectors with respect to radiation hardness and rate capability which are further increased with the luminosity upgrade. In this thesis, the limitations of the Muon Drift Tube (MDT) chambers of the ATLAS Muon Spectrometer at the high background counting rates at the LHC and performance of new small diameter muon drift tube (sMDT) detectors at the even higher background rates at HL-LHC are stud...

  13. Dynamic High-Temperature Characterization of an Iridium Alloy in Compression at High Strain Rates

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Experimental Environment Simulation Dept.; Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.; Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Fuel Cycle Technology Dept.; Bignell, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Structural and Thermal Analysis Dept.; Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program; George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program

    2014-06-01

    Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzed the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s-1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.

  14. Mechanical characterization of rocks at high strain rate

    Directory of Open Access Journals (Sweden)

    Konstantinov A.

    2012-08-01

    Full Text Available The paper presents the dynamic characterization in tension and compression of three rocks, Carrara marble, Onsernone gneiss and Peccia Marble, at high strain-rates. Two versions of a Split Hopkinson Bar have been used. The version for direct tension tests is installed at the DynaMat Laboratory of the University of Applied Sciences of Southern Switzerland, while the traditional version in compression is installed at the Laboratory of Dynamic Investigation of Materials of Lobachevsky State University. Results of the tests show a significantly strain-rate sensitive behaviour, exhibiting dynamic strength increasing with strain-rate. The experimental research has been developed in the frame of the Swiss-Russian Joint Research Program.

  15. High freight rates hinder oil markets' return to equilibrium

    International Nuclear Information System (INIS)

    Anon

    2005-01-01

    Hurricane damage to refineries in the US has created shortages of refined products there, boosting imports and sending freight rates across the Atlantic to record levels. The situation was made worse for a time by a strike at France's main oil terminals in the Mediterranean, which prevented some oil tankers from being rapidly redeployed to routes across the Atlantic. Worldscale (WS) rates for routes from the UK and Europe to the US Atlantic and Gulf Coasts rose well above WS500 for clean tonnage during October. High rates were nevertheless not simply confined to product tankers crossing the Atlantic. Rates for crude tankers to the US have also risen, and tightness has begun to appear in some other markets as well. The net result has been to slow down the movement of oil from regions of surplus to those of scarcity, depressing prices in the former and keeping them at high levels in the latter. Atlantic tanker markets look like remaining tight for the rest of the year and perhaps beyond. (author)

  16. Investigation of high-rate lithium-thionyl chloride cells

    Science.gov (United States)

    Hayes, Catherine A.; Gust, Steven; Farrington, Michael D.; Lockwood, Judith A.; Donaldson, George J.

    Chemical analysis of a commercially produced high-rate D-size lithium-thionyl cell was carried out, as a function of rate of discharge (1 ohm and 5 ohms), depth of discharge, and temperature (25 C and -40 C), using specially developed methods for identifying suspected minor cell products or impurities which may effect cell performance. These methods include a product-retrieval system which involves solvent extraction to enhance the recovery of suspected semivolatile minor chemicals, and methods of quantitative GC analysis of volatile and semivolatile products. The nonvolatile products were analyzed by wet chemical methods. The results of the analyses indicate that the predominant discharge reaction in this cell is 4Li + 2SOCl2 going to 4LiCl + S + SO2, with SO2 formation decreasing towards the end of cell life (7 to 12 Ah). The rate of discharge had no effect on the product distribution. Upon discharge of the high-rate cell at -40 C, one cell exploded, and all others exhibited overheating and rapid internal pressure rise when allowed to warm up to room temperature.

  17. Development of amplifier and shaper for high-rate MWPC

    International Nuclear Information System (INIS)

    Kamiji, Ichinori; Nanjo, Hajime; Kawasaki, Naoki; Maeda, Yosuke; Naito, Daichi; Seki, Shigeto; Nakagiri, Kota; Sasao, Noboru; Nomura, Tadashi

    2015-01-01

    A multi-wire proportional chamber (MWPC) will be used as an in-beam charged particle detector for the J-PARC E14 (KOTO) experiment. The maximum counting rate of the MWPC is expected to be up to 1 MHz per channel due to the high neutron and photon flux, expected to be 1 GHz for the 30 x 30 cm"2 area. An amplifier to cope with such high counting-rate is required. We developed a prototype of such amplifier, which has a charge preamplifier with the integration time of 3 ns and a pulse shaping part with three pole-zero cancellation networks. The shaper reduced the characteristic long tail lasting tens of microseconds in the signal of MWPC to 150 ns. Its performance has been tested by using a single-channel MWPC which has almost the same geometrical parameters as the MWPC to be installed in the KOTO experiment. (author)

  18. Characteristics of Multiplexed Grooved Nozzles for High Flow Rate Electrospray

    International Nuclear Information System (INIS)

    Kim, Kyoung Tae; Kim, Woo Jin; Kim, Sang Soo

    2007-01-01

    The electrospray operated in the cone-jet mode can generate highly charged micro droplets in an almost uniform size at flow rates. Therefore, the multiplexing system which can retain the characteristics of the cone-jet mode is inevitable for the electrospray application. This experiment reports the multiplexed grooved nozzle system with the extractor. The effects of the grooves and the extractor on the performance of the electrospray were evaluated through experiments. Using the grooved nozzle, the stable cone-jet mode can be achieved at the each groove in the grooved mode. Furthermore, the number of nozzles per unit area is increased by the extractor. The multiplexing density is 12 jets per cm 2 at 30 mm distance from the nozzle tip to the ground plate. The multiplexing system for the high flow rate electrospray is realized with the extractor which can diminish the space charge effect without sacrificing characteristics of the cone-jet mode

  19. Miniaturized Stretchable and High-Rate Linear Supercapacitors

    OpenAIRE

    Zhu, Wenjun; Zhang, Yang; Zhou, Xiaoshuang; Xu, Jiang; Liu, Zunfeng; Yuan, Ningyi; Ding, Jianning

    2017-01-01

    Linear stretchable supercapacitors have attracted much attention because they are well suited to applications in the rapidly expanding field of wearable electronics. However, poor conductivity of the electrode material, which limits the transfer of electrons in the axial direction of the linear supercapacitors, leads to a serious loss of capacity at high rates. To solve this problem, we use gold nanoparticles to decorate aligned multiwall carbon nanotube to fabricate stretchable linear electr...

  20. High repetition rate burst-mode spark gap

    International Nuclear Information System (INIS)

    Faltens, A.; Reginato, L.; Hester, R.; Chesterman, A.; Cook, E.; Yokota, T.; Dexter, W.

    1978-01-01

    Results are presented on the design and testing of a pressurized gas blown spark gap switch capable of high repetition rates in a burst mode of operation. The switch parameters which have been achieved are as follows: 220-kV, 42-kA, a five pulse burst at 1-kHz, 12-ns risetime, 2-ns jitter at a pulse width of 50-ns

  1. High rate multiplicity detector for relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Beavis, D.; Bennett, M.J.; Carroll, J.B.; Chiba, J.; Chikanian, A.; Crawford, H.J.; Cronqvist, M.; Dardenne, Y.; Debbe, R.; Doke, T.; Engelage, J.; Flores, I.; Greiner, L.; Hayano, R.S.; Hallman, T.J.; Heckman, H.H.; Kashiwagi, T.; Kikuchi, J.; Kumar, B.S.; Kuo, C.; Lindstrom, P.J.; Mitchell, J.W.; Nagamiya, S.; Nagle, J.L.; Pope, J.K.; Stankus, P.; Tanaka, K.H.; Welsh, R.C.; Zhan, W.

    1995-01-01

    We have constructed and operated a detector to measure the multiplicity of secondary particles produced in nucleus-nucleus collisions in the E878 experiment at the Brookhaven National Laboratory AGS facility. We describe the operation and performance of the detector in a high rate Au beam environment, and interpret the multiplicity data in terms of the impact parameters of the nucleus-nucleus collisions. ((orig.))

  2. High rate multiplicity detector for relativistic heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Beavis, D [Brookhaven National Lab., Upton, NY (United States); Bennett, M J [Yale University, A.W. Wright Nuclear Structure Laboratory, New Haven, CT 06511 (United States); Carroll, J B [University of California at Los Angeles, Los Angeles, CA (United States); Chiba, J [KEK National High Energy Physics, Tsukuba (Japan); Chikanian, A [Yale University, A.W. Wright Nuclear Structure Laboratory, New Haven, CT 06511 (United States); Crawford, H J [University of California Space Sciences Laboratory, Berkeley, CA (United States); Cronqvist, M [University of California Space Sciences Laboratory, Berkeley, CA (United States); Dardenne, Y [University of California Space Sciences Laboratory, Berkeley, CA (United States); Debbe, R [Brookhaven National Lab., Upton, NY (United States); Doke, T [Waseda University, Science and Engineering Research Institute, Waseda (Japan); Engelage, J [University of California Space Sciences Laboratory, Berkeley, CA (United States); Flores, I [University of California Space Sciences Laboratory, Berkeley, CA (United States); Greiner, L [University of California Space Sciences Laboratory, Berkeley, CA (United States); Hayano, R S [University of Tokyo, Tokyo (Japan); Hallman, T J [University of California at Los Angeles, Los Angeles, CA (United States); Heckman, H H [Lawrence Berkeley Lab., CA (United States); Kashiwagi, T [Waseda University, Science and Engineering Research Institute, Waseda (Japan); Kikuchi, J [Waseda University, Science and Engineering Research Institute, Waseda (Japan); Kumar, B S [Yale University, A.W. Wright Nuclear Structure Laboratory, New Haven, CT 06511 (United States); Kuo, C [University of California Space Sciences Laboratory, Berkeley, CA (United States); Lindstrom, P J [Lawrence Berkeley Lab., CA (United States); Mitchell, J W [Universities Space Research Association/Goddard Space Flight Center, Greenbelt, MD (United States); Nagamiya, S; E878 Collaboration

    1995-04-21

    We have constructed and operated a detector to measure the multiplicity of secondary particles produced in nucleus-nucleus collisions in the E878 experiment at the Brookhaven National Laboratory AGS facility. We describe the operation and performance of the detector in a high rate Au beam environment, and interpret the multiplicity data in terms of the impact parameters of the nucleus-nucleus collisions. ((orig.)).

  3. MDT Performance in a High Rate Background Environment

    CERN Document Server

    Aleksa, Martin; Hessey, N P; Riegler, W

    1998-01-01

    A Cs137 gamma source with different lead filters in the SPS beam-line X5 has been used to simulate the ATLAS background radiation. This note shows the impact of high background rates on the MDT efficiency and resolution for three kinds of pulse shaping and compares the results with GARFIELD simulations. Furthermore it explains how the performance can be improved by time slewing corrections and double track separation.

  4. Study of Attrition Documentation at the U.S. Navy Recruit Training Command

    National Research Council Canada - National Science Library

    Condon, Nancy K; Eckenrode, John E

    2006-01-01

    .... Navy's Recruit Training Command (RTC). A random sample of 754 "retained files" from Customer Service Desk RTC was examined for attrition documentation and the information obtained was compared with attrition documentation contained...

  5. A Longitudinal Examination of First Term Attrition and Reenlistment among FY1999 Enlisted Accessions

    National Research Council Canada - National Science Library

    Strickland, William J

    2005-01-01

    ... the service, completed training segments, conducted duty assignments, and left the service. These models explored reasons for attrition and reenlistment intentions, and suggested management strategies that might be employed to reduce attrition...

  6. Blood Telomere Length Attrition and Cancer Development in the Normative Aging Study Cohort

    Directory of Open Access Journals (Sweden)

    Lifang Hou

    2015-06-01

    Interpretation: Age-related BTL attrition was faster in cancer cases but their age-adjusted BTL attrition began decelerating as diagnosis approached. This may explain prior inconsistencies and help develop BTL as a cancer detection biomarker.

  7. High rate amplifier-digitizer system for liquid argon calorimeters

    International Nuclear Information System (INIS)

    Droege, T.F.; Lobkowicz, F.; Fukushima, Y.

    1978-01-01

    A low-cost charge amplifier for a liquid argon photon detector and a new method for pulse height analysis are described. This scheme is suitable for high-energy photon detection with high counting rate. Samples of preamplifer output are taken just before and just after the arrival of the charge from the detector. The difference of these samples provides a stable pedestal and rejects low frequency noise. Short two-pulse resolving time (approximately equal to 200ns) is achieved. 6 refs

  8. Abuse resistant high rate lithium/thionyl chloride cells

    Energy Technology Data Exchange (ETDEWEB)

    Surprenant, J.; Snuggerud, D.

    1982-08-01

    A compact, disc shaped lithium/thionyl chloride cell has been developed by Altus Corporation. The cell has a 6 Amphr capacity and is capable of high rate discharge at high voltage. Discharge data is presented over the range of 0.07 to 1.1 Amperes. The cell is operable over the temperature range of -40/sup 0/C to +70/sup 0/C, and has a 10 year shelf life at 20/sup 0/C. Safety features allow the cells to withstand fire, puncture, shock, spin, forced discharge or forced charge without dangerous reactions.

  9. Abuse resistant high rate lithium/thionyl chloride cells

    Science.gov (United States)

    Surprenant, J.; Snuggerud, D.

    A compact, disk shaped lithium/thionyl chloride cell has been developed. The cell has a 6 Amphr capacity and is capable of high rate discharge at high voltage. Discharge data are presented over the range of 0.07 to 1.1 amperes. The cell is operable over the temperature range of -40 C to +70 C, and has a 10 year shelf life at 20 C. Safety features allow the cells to withstand fire, puncture, shock, spin, forced discharge or forced charge without dangerous reactions.

  10. Semi-solid electrodes having high rate capability

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Yet-Ming; Duduta, Mihai; Holman, Richard; Limthongkul, Pimpa; Tan, Taison

    2017-11-28

    Embodiments described herein relate generally to electrochemical cells having high rate capability, and more particularly to devices, systems and methods of producing high capacity and high rate capability batteries having relatively thick semi-solid electrodes. In some embodiments, an electrochemical cell includes an anode and a semi-solid cathode. The semi-solid cathode includes a suspension of an active material of about 35% to about 75% by volume of an active material and about 0.5% to about 8% by volume of a conductive material in a non-aqueous liquid electrolyte. An ion-permeable membrane is disposed between the anode and the semi-solid cathode. The semi-solid cathode has a thickness of about 250 .mu.m to about 2,000 .mu.m, and the electrochemical cell has an area specific capacity of at least about 7 mAh/cm.sup.2 at a C-rate of C/4. In some embodiments, the semi-solid cathode slurry has a mixing index of at least about 0.9.

  11. High Strain Rate and Shock-Induced Deformation in Metals

    Science.gov (United States)

    Ravelo, Ramon

    2012-02-01

    Large-scale non-equilibrium molecular Dynamics (MD) simulations are now commonly used to study material deformation at high strain rates (10^9-10^12 s-1). They can provide detailed information-- such as defect morphology, dislocation densities, and temperature and stress profiles, unavailable or hard to measure experimentally. Computational studies of shock-induced plasticity and melting in fcc and bcc single, mono-crystal metals, exhibit generic characteristics: high elastic limits, large directional anisotropies in the yield stress and pre-melting much below the equilibrium melt temperature for shock wave propagation along specific crystallographic directions. These generic features in the response of single crystals subjected to high strain rates of deformation can be explained from the changes in the energy landscape of the uniaxially compressed crystal lattice. For time scales relevant to dynamic shock loading, the directional-dependence of the yield strength in single crystals is shown to be due to the onset of instabilities in elastic-wave propagation velocities. The elastic-plastic transition threshold can accurately be predicted by a wave-propagation stability analysis. These strain-induced instabilities create incipient defect structures, which can be quite different from the ones, which characterize the long-time, asymptotic state of the compressed solid. With increase compression and strain rate, plastic deformation via extended defects gives way to amorphization associated with the loss in shear rigidity along specific deformation paths. The hot amorphous or (super-cooled liquid) metal re-crystallizes at rates, which depend on the temperature difference between the amorphous solid and the equilibrium melt line. This plastic-amorphous transition threshold can be computed from shear-waves stability analyses. Examples from selected fcc and bcc metals will be presented employing semi-empirical potentials of the embedded atom method (EAM) type as well as

  12. Scale dependence of rock friction at high work rate.

    Science.gov (United States)

    Yamashita, Futoshi; Fukuyama, Eiichi; Mizoguchi, Kazuo; Takizawa, Shigeru; Xu, Shiqing; Kawakata, Hironori

    2015-12-10

    Determination of the frictional properties of rocks is crucial for an understanding of earthquake mechanics, because most earthquakes are caused by frictional sliding along faults. Prior studies using rotary shear apparatus revealed a marked decrease in frictional strength, which can cause a large stress drop and strong shaking, with increasing slip rate and increasing work rate. (The mechanical work rate per unit area equals the product of the shear stress and the slip rate.) However, those important findings were obtained in experiments using rock specimens with dimensions of only several centimetres, which are much smaller than the dimensions of a natural fault (of the order of 1,000 metres). Here we use a large-scale biaxial friction apparatus with metre-sized rock specimens to investigate scale-dependent rock friction. The experiments show that rock friction in metre-sized rock specimens starts to decrease at a work rate that is one order of magnitude smaller than that in centimetre-sized rock specimens. Mechanical, visual and material observations suggest that slip-evolved stress heterogeneity on the fault accounts for the difference. On the basis of these observations, we propose that stress-concentrated areas exist in which frictional slip produces more wear materials (gouge) than in areas outside, resulting in further stress concentrations at these areas. Shear stress on the fault is primarily sustained by stress-concentrated areas that undergo a high work rate, so those areas should weaken rapidly and cause the macroscopic frictional strength to decrease abruptly. To verify this idea, we conducted numerical simulations assuming that local friction follows the frictional properties observed on centimetre-sized rock specimens. The simulations reproduced the macroscopic frictional properties observed on the metre-sized rock specimens. Given that localized stress concentrations commonly occur naturally, our results suggest that a natural fault may lose its

  13. Team-Based Learning Reduces Attrition in a First-Semester General Chemistry Course

    Science.gov (United States)

    Comeford, Lorrie

    2016-01-01

    Team-based learning (TBL) is an instructional method that has been shown to reduce attrition and increase student learning in a number of disciplines. TBL was implemented in a first-semester general chemistry course, and its effect on attrition was assessed. Attrition from sections before implementing TBL (fall 2008 to fall 2009) was compared with…

  14. A new high rate positron lifetime measurement system

    International Nuclear Information System (INIS)

    Bedwell, M.O.; Paulus, T.J.

    1979-01-01

    Positron lifetime measuring system, a technique to perform non-destructive studies on the internal structure of materials, has many components common to those used for nuclear time spectroscopy systems. In each case, a timing coincidence curve is measured for the energy range of interest, and this is accomplished in a typical timing coincidence system. The paper first describes the conventional timing coincidence system, then a new fast timing system is introduced. Comparing to the conventional fast/slow timing system, the fast timing technique offers reduced complexity, lower system cost, and improved high data rate capability. Experimental results show that the FWHM timing resolution ranges from 190 ps for a 1.1 : 1 dynamic range to 337 ps for a 100 : 1 dynamic range of signals with 60 Co. As for the timing resolution as a function of energy, the FWHM resolution for each channel ranges from 124 ps at 1 MeV to 400 ps at 100 keV. Since the excellent timing performance is maintained even at very high input rate, the experimenters can use much more active sources to increase the true coincidence rate and reduce data accumulation time. This method has the added advantage of minimizing long term drift effects since the experiments can be conducted in less time. (Wakatsuki, Y.)

  15. Miniaturized Stretchable and High-Rate Linear Supercapacitors.

    Science.gov (United States)

    Zhu, Wenjun; Zhang, Yang; Zhou, Xiaoshuang; Xu, Jiang; Liu, Zunfeng; Yuan, Ningyi; Ding, Jianning

    2017-12-01

    Linear stretchable supercapacitors have attracted much attention because they are well suited to applications in the rapidly expanding field of wearable electronics. However, poor conductivity of the electrode material, which limits the transfer of electrons in the axial direction of the linear supercapacitors, leads to a serious loss of capacity at high rates. To solve this problem, we use gold nanoparticles to decorate aligned multiwall carbon nanotube to fabricate stretchable linear electrodes. Furthermore, we have developed fine stretchable linear supercapacitors, which exhibited an extremely high elasticity up to 400% strain with a high capacitance of about 8.7 F g -1 at the discharge current of 1 A g -1 .

  16. High Dose-Rate Versus Low Dose-Rate Brachytherapy for Lip Cancer

    International Nuclear Information System (INIS)

    Ghadjar, Pirus; Bojaxhiu, Beat; Simcock, Mathew; Terribilini, Dario; Isaak, Bernhard; Gut, Philipp; Wolfensberger, Patrick; Brömme, Jens O.; Geretschläger, Andreas; Behrensmeier, Frank; Pica, Alessia; Aebersold, Daniel M.

    2012-01-01

    Purpose: To analyze the outcome after low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy for lip cancer. Methods and Materials: One hundred and three patients with newly diagnosed squamous cell carcinoma of the lip were treated between March 1985 and June 2009 either by HDR (n = 33) or LDR brachytherapy (n = 70). Sixty-eight patients received brachytherapy alone, and 35 received tumor excision followed by brachytherapy because of positive resection margins. Acute and late toxicity was assessed according to the Common Terminology Criteria for Adverse Events 3.0. Results: Median follow-up was 3.1 years (range, 0.3–23 years). Clinical and pathological variables did not differ significantly between groups. At 5 years, local recurrence-free survival, regional recurrence-free survival, and overall survival rates were 93%, 90%, and 77%. There was no significant difference for these endpoints when HDR was compared with LDR brachytherapy. Forty-two of 103 patients (41%) experienced acute Grade 2 and 57 of 103 patients (55%) experienced acute Grade 3 toxicity. Late Grade 1 toxicity was experienced by 34 of 103 patients (33%), and 5 of 103 patients (5%) experienced late Grade 2 toxicity; no Grade 3 late toxicity was observed. Acute and late toxicity rates were not significantly different between HDR and LDR brachytherapy. Conclusions: As treatment for lip cancer, HDR and LDR brachytherapy have comparable locoregional control and acute and late toxicity rates. HDR brachytherapy for lip cancer seems to be an effective treatment with acceptable toxicity.

  17. Brachytherapy for early oral tongue cancer. Low dose rate to high dose rate

    International Nuclear Information System (INIS)

    Yamazaki, Hideya; Inoue, Takehiro; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Inoue, Toshihiko; Furukawa, Souhei; Kakimoto, Naoya

    2003-01-01

    To examine the compatibility of low dose rate (LDR) with high dose rate (HDR) brachytherapy, we reviewed 399 patients with early oral tongue cancer (T1-2N0M0) treated solely by brachytherapy at Osaka University Hospital between 1967 and 1999. For patients in the LDR group (n=341), the treatment sources consisted of Ir-192 pin for 227 patients (1973-1996; irradiated dose, 61-85 Gy; median, 70 Gy), Ra-226 needle for 113 patients (1967-1986; 55-93 Gy; median, 70 Gy). Ra-226 and Ir-192 were combined for one patient. Ir-192 HDR (microSelectron-HDR) was used for 58 patients in the HDR group (1991-present; 48-60 Gy; median, 60 Gy). LDR implantations were performed via oral and HDR via a submental/submandibular approach. The dose rates at the reference point for the LDR group were 0.30 to 0.8 Gy/h, and for the HDR group 1.0 to 3.4 Gy/min. The patients in the HDR group received a total dose of 48-60 Gy (8-10 fractions) during one week. Two fractions were administered per day (at least a 6-h interval). The 3- and 5-year local control rates for patients in the LDR group were 85% and 80%, respectively, and those in the HDR group were both 84%. HDR brachytherapy showed the same lymph-node control rate as did LDR brachytherapy (67% at 5 years). HDR brachytherapy achieved the same locoregional result as did LDR brachytherapy. A converting factor of 0.86 is applicable for HDR in the treatment of early oral tongue cancer. (author)

  18. High Dose-Rate Versus Low Dose-Rate Brachytherapy for Lip Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ghadjar, Pirus, E-mail: pirus.ghadjar@insel.ch [Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern (Switzerland); Bojaxhiu, Beat [Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern (Switzerland); Simcock, Mathew [Swiss Group for Clinical Cancer Research Coordinating Center, Bern (Switzerland); Terribilini, Dario; Isaak, Bernhard [Division of Medical Radiation Physics, Inselspital, Bern University Hospital, and University of Bern, Bern (Switzerland); Gut, Philipp; Wolfensberger, Patrick; Broemme, Jens O.; Geretschlaeger, Andreas; Behrensmeier, Frank; Pica, Alessia; Aebersold, Daniel M. [Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern (Switzerland)

    2012-07-15

    Purpose: To analyze the outcome after low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy for lip cancer. Methods and Materials: One hundred and three patients with newly diagnosed squamous cell carcinoma of the lip were treated between March 1985 and June 2009 either by HDR (n = 33) or LDR brachytherapy (n = 70). Sixty-eight patients received brachytherapy alone, and 35 received tumor excision followed by brachytherapy because of positive resection margins. Acute and late toxicity was assessed according to the Common Terminology Criteria for Adverse Events 3.0. Results: Median follow-up was 3.1 years (range, 0.3-23 years). Clinical and pathological variables did not differ significantly between groups. At 5 years, local recurrence-free survival, regional recurrence-free survival, and overall survival rates were 93%, 90%, and 77%. There was no significant difference for these endpoints when HDR was compared with LDR brachytherapy. Forty-two of 103 patients (41%) experienced acute Grade 2 and 57 of 103 patients (55%) experienced acute Grade 3 toxicity. Late Grade 1 toxicity was experienced by 34 of 103 patients (33%), and 5 of 103 patients (5%) experienced late Grade 2 toxicity; no Grade 3 late toxicity was observed. Acute and late toxicity rates were not significantly different between HDR and LDR brachytherapy. Conclusions: As treatment for lip cancer, HDR and LDR brachytherapy have comparable locoregional control and acute and late toxicity rates. HDR brachytherapy for lip cancer seems to be an effective treatment with acceptable toxicity.

  19. High rate 4π β-γ coincidence counting system

    International Nuclear Information System (INIS)

    Johnson, L.O.; Gehrke, R.J.

    1978-01-01

    A high count rate 4π β-γ coincidence counting system for the determination of absolute disintegration rates of short half-life radionuclides is described. With this system the dead time per pulse is minimized by not stretching any pulses beyond the width necessary to satisfy overlap coincidence requirements. The equations used to correct for the β, γ, and coincidence channel dead times and for accidental coincidences are presented but not rigorously developed. Experimental results are presented for a decaying source of 56 Mn initially at 2 x 10 6 d/s and a set of 60 Co sources of accurately known source strengths varying from 10 3 to 2 x 10 6 d/s. A check of the accidental coincidence equation for the case of two independent sources with varying source strengths is presented

  20. Miniaturized star tracker for micro spacecraft with high angular rate

    Science.gov (United States)

    Li, Jianhua; Li, Zhifeng; Niu, Zhenhong; Liu, Jiaqi

    2017-10-01

    There is a clear need for miniaturized, lightweight, accurate and inexpensive star tracker for spacecraft with large anglar rate. To face these new constraints, the Beijing Institute of Space Long March Vehicle has designed, built and flown a low cost miniaturized star tracker that provides autonomous ("Lost in Space") inertial attitude determination, 2 Hz 3-axis star tracking, and digital imaging with embedded compression. Detector with high sensitivity is adopted to meet the dynamic and miniature requirement. A Sun and Moon avoiding method based on the calculation of Sun and Moon's vector by astronomical theory is proposed. The produced prototype weight 0.84kg, and can be used for a spacecraft with 6°/s anglar rate. The average angle measure error is less than 43 arc second. The ground verification and application of the star tracker during the pick-up flight test showed that the capability of the product meet the requirement.

  1. Development of miniature γ dose rate monitor with high sensitivity

    International Nuclear Information System (INIS)

    Shi Huilu; Tuo Xianguo; Xi Dashun; Tang Rong; Mu Keliang; Yang Jianbo

    2009-01-01

    This paper introduces a miniature γ dose rate monitor with high sensitivity which design based on single chip microcomputer, it can continue monitoring γ dose rate and then choose wire or wireless communications to sent the monitoring data to host according to the actual conditions. It has two kinds of power supply system, AC power supply system and battery which can be chose by concrete circumstances. The design idea and implementation technology of hardware and software and the system structure of the monitor are detailed illustrated in this paper. The experimental results show that measurable range is 0.1 mR/h-200 mR/h, the sensitivity of γ is 90 cps/mR/h, dead time below 200 us, error of stability below ±10%. (authors)

  2. Low resistance bakelite RPC study for high rate working capability

    International Nuclear Information System (INIS)

    Dai, T.; Han, L.; Hou, S.; Liu, M.; Li, Q.; Song, H.; Xia, L.; Zhang, Z.

    2014-01-01

    This paper presents series efforts to lower resistance of bakelite electrode plate to improve the RPC capability under high rate working condition. New bakelite material with alkali metallic ion doping has been manufactured and tested. This bakelite is found unstable under large charge flux and need further investigation. A new structure of carbon-embedded bakelite RPC has been developed, which can reduce the effective resistance of electrode by a factor of 10. The prototype of the carbon-embedded chamber could function well under gamma radiation source at event rate higher than 10 kHz/cm 2 . The preliminary tests show that this kind of new structure performs as efficiently as traditional RPCs

  3. High and low dose-rate brachytherapy for cervical carcinoma

    International Nuclear Information System (INIS)

    Orton, C.G.

    1998-01-01

    For the brachytherapy component of the r[iation treatment of cervical carcinoma, high dose rate (HDR) is slowly replacing conventional low dose rate (LDR) due primarily to r[iation safety and other physical benefits attributed to the HDR modality. Many r[iation oncologists are reluctant to make this change because of perceived r[iobiological dis[vantages of HDR. However, in clinical practice HDR appears to be as effective as LDR but with a lower risk of late complications, as demonstrated by one randomized clinical trial and two comprehensive literature and practice surveys. The reason for this appears to be that the r[iobiological dis[vantages of HDR are outweighed by the physical [vantages. (orig.)

  4. High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors

    OpenAIRE

    Ho, Dang; Jensen, Paul; Gutierrez-Zamora, Maria-Luisa; Beckmann, Sabrina; Manefield, Mike; Batstone, Damien

    2016-01-01

    A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA-stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste...

  5. Nanocrystalline-grained tungsten prepared by surface mechanical attrition treatment: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Guo, Hong-Yan; Xia, Min; Wu, Zheng-Tao; Chan, Lap-Chung; Dai, Yong; Wang, Kun; Yan, Qing-Zhi; He, Man-Chao; Ge, Chang-Chun; Lu, Jian

    2016-01-01

    A nanostructured surface layer was fabricated on commercial pure tungsten using the method of surface mechanical attrition treatment (SMAT). The microstructure evolution of the surface layer was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and its formation mechanism was discussed as well. Both refinement and elongation of the brittle W grains were confirmed. The elongated SMATed W was heavily strained, the maximum value of the strain at the grain boundaries reaches as high as 3–5%. Dislocation density in the SMATed W nanograins was found to be 5 × 10 12  cm −2 . The formation of the nanograins in the top surface layer of the W was ascribed to the extremely high strain and strain rate, as well as the multidirectional repetitive loading. Bending strength of commercial W could be improved from 825 MPa to 1850 MPa by SMAT process. Microhardness results indicated the strain range in SMATed W can reach up to 220 μm beneath the top surface. The notched Charpy testing results demonstrated that SMATed W possess higher ductility than that of commercial W. The top surface of the W plates with and without SMATe processing possesses residual compressive stress of about −881 MPa and −234 MPa in y direction, and −872 MPa and −879 MPa in x direction respectively. The improvement of toughness (DBTT shift) of SMATed W may be the synergistic effect of residual compressive stress, dislocation density improvement and microstructure refinement induced by SMAT processing. SMAT processing could be a complementary method to further decrease the DBTT value of tungsten based materials.

  6. Nanocrystalline-grained tungsten prepared by surface mechanical attrition treatment: Microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hong-Yan [State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tae Chee Avenue Kowloon, Hong Kong 999077 (China); Xia, Min, E-mail: xmdsg@ustb.edu.cn [Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); Wu, Zheng-Tao [College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chan, Lap-Chung [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tae Chee Avenue Kowloon, Hong Kong 999077 (China); Dai, Yong; Wang, Kun [Laboratory for Nuclear Materials, Paul Scherrer Institut, 5323 Villigen PSI (Switzerland); Yan, Qing-Zhi [Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); He, Man-Chao [State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); Ge, Chang-Chun, E-mail: ccge@mater.ustb.edu.cn [Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); Lu, Jian, E-mail: jianlu@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tae Chee Avenue Kowloon, Hong Kong 999077 (China)

    2016-11-15

    A nanostructured surface layer was fabricated on commercial pure tungsten using the method of surface mechanical attrition treatment (SMAT). The microstructure evolution of the surface layer was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and its formation mechanism was discussed as well. Both refinement and elongation of the brittle W grains were confirmed. The elongated SMATed W was heavily strained, the maximum value of the strain at the grain boundaries reaches as high as 3–5%. Dislocation density in the SMATed W nanograins was found to be 5 × 10{sup 12} cm{sup −2}. The formation of the nanograins in the top surface layer of the W was ascribed to the extremely high strain and strain rate, as well as the multidirectional repetitive loading. Bending strength of commercial W could be improved from 825 MPa to 1850 MPa by SMAT process. Microhardness results indicated the strain range in SMATed W can reach up to 220 μm beneath the top surface. The notched Charpy testing results demonstrated that SMATed W possess higher ductility than that of commercial W. The top surface of the W plates with and without SMATe processing possesses residual compressive stress of about −881 MPa and −234 MPa in y direction, and −872 MPa and −879 MPa in x direction respectively. The improvement of toughness (DBTT shift) of SMATed W may be the synergistic effect of residual compressive stress, dislocation density improvement and microstructure refinement induced by SMAT processing. SMAT processing could be a complementary method to further decrease the DBTT value of tungsten based materials.

  7. Handling high data rate detectors at Diamond Light Source

    Science.gov (United States)

    Pedersen, U. K.; Rees, N.; Basham, M.; Ferner, F. J. K.

    2013-03-01

    An increasing number of area detectors, in use at Diamond Light Source, produce high rates of data. In order to capture, store and process this data High Performance Computing (HPC) systems have been implemented. This paper will present the architecture and usage for handling high rate data: detector data capture, large volume storage and parallel processing. The EPICS area Detector frame work has been adopted to abstract the detectors for common tasks including live processing, file format and storage. The chosen data format is HDF5 which provides multidimensional data storage and NeXuS compatibility. The storage system and related computing infrastructure include: a centralised Lustre based parallel file system, a dedicated network and a HPC cluster. A well defined roadmap is in place for the evolution of this to meet demand as the requirements and technology advances. For processing the science data the HPC cluster allow efficient parallel computing, on a mixture of ×86 and GPU processing units. The nature of the Lustre storage system in combination with the parallel HDF5 library allow efficient disk I/O during computation jobs. Software developments, which include utilising optimised parallel file reading for a variety of post processing techniques, are being developed in collaboration as part of the Pan-Data EU Project (www.pan-data.eu). These are particularly applicable to tomographic reconstruction and processing of non crystalline diffraction data.

  8. Precise muon drift tube detectors for high background rate conditions

    CERN Document Server

    Engl, Albert; Dünnweber, Wolfgang

    The muon spectrometer of the ATLAS-experiment at the Large H adron Collider consists of drift tube chambers, which provide the precise m easurement of trajec- tories of traversing muons. In order to determine the moment um of the muons with high precision, the measurement of the position of the m uon in a single tube has to be more accurate than σ ≤ 100 m. The large cross section of proton-proton-collisions and th e high luminosity of the accelerator cause relevant background of neutrons and γ s in the muon spectrome- ter. During the next decade a luminosity upgrade [1] to 5 10 34 cm − 2 s − 1 is planned, which will increase the background counting rates consider ably. In this context this work deals with the further development of the existing drift chamber tech- nology to provide the required accuracy of the position meas urement under high background conditions. Two approaches of improving the dri ft tube chambers are described: • In regions of moderate background rates a faster and more lin ear ...

  9. Proportional chambers and multiwire drift chambers at high rates

    International Nuclear Information System (INIS)

    Walenta, A.H.

    1977-01-01

    The high event and particle rates expected for ISABELLE intersecting storage rings raise the question whether PWC's and drift chambers, now widely in use in experiments, still can operate under such conditions. Various effects depend on the number of avalanches produced per length of wire N and the size of the avalanche Q, i.e., on the number of positive ions created in an avalanche. Therefore the important parameter for the following discussion is the product QN. The minimum Q is determined by the type and noise level of preamplifiers used. Examples are given for a typical low noise amplifier as well as for a typical integrated ''cheap'' amplifier. The rate/wire length N depends on the chamber arrangement, wire spacing, etc. In multiwire drift chambers, a single wire shows space-charge effects reducing the pulse height by 1% at a rate of N = 7 x 10 3 mm -1 sec -1 . At a rate of N approximately equal to 10 5 mm -1 sec -1 an efficiency loss of the order of 1% was noticed. The aging effect due to deposits on the anode wire can be reduced using low noise amplifiers and low gas gain to such an extent that a lifetime of about half a year at ISABELLE can be expected. The use of conventional cheap preamplifiers will result in a typical lifetime of about 30 days. Improvements are probable. The time resolution of Δt/sub r/ = 4 nsec fwhm seems adequate for event rates of 10 7 sec -1 . The memory time Δt/sub m/ greater than or equal to 100 nsec may cause serious problems for pattern recognition depending on layout and readout. The use of induced signals on cathode pads, thus reading out shorter parts of the wire, can solve the problem

  10. Experimental investigation of bond strength under high loading rates

    Directory of Open Access Journals (Sweden)

    Michal Mathias

    2015-01-01

    Full Text Available The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw and the Joint Research Centre (JRC in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

  11. A Conceptual Framework for Evaluating Attrition in Online Courses

    Science.gov (United States)

    Laing, C. Linda; Laing, Gregory K.

    2015-01-01

    The purpose of this paper is to develop a conceptual framework that considers the role that the sense of isolation and alienation play in contributing to attrition in online courses in the higher education sector. The approach adopted in this paper is a theoretical study aimed at synthesizing existing theories. The ultimate contribution of this…

  12. Evaluation of the Dehulling Efficiency of Soybean Using Attrition and ...

    African Journals Online (AJOL)

    Conditioned seeds were dehulled in the huller section of commercial rice milling machine and attrition milling machine. A dehulling efficiency (e) value of 55%, which corresponded to an extraction yield (E) of 44% was achieved using the huller section of a commercial rice milling machine, while 90% dehulling efficiency (e), ...

  13. Texas Public School Attrition Study, 2013-14. IDRA Report

    Science.gov (United States)

    Johnson, Roy L.; Montes, Felix

    2014-01-01

    Since 1986, Intercultural Development Research Association (IDRA) has conducted an annual attrition study to track the number and percent of students in Texas who are lost from public secondary school enrollment prior to graduation. The study builds on the series of studies that began when IDRA conducted the first comprehensive study of school…

  14. Texas Public School Attrition Study, 2016-17. IDRA Report

    Science.gov (United States)

    Johnson, Roy L.; Montes, Felix

    2017-01-01

    Since 1986, Intercultural Development Research Association (IDRA) has conducted an annual attrition study to track the number and percent of students in Texas who are lost from public secondary school enrollment prior to graduation. The study builds on the series of studies that began when IDRA conducted the first comprehensive study of school…

  15. Texas Public School Attrition Study, 2014-15. IDRA Report

    Science.gov (United States)

    Johnson, Roy L.; Montes, Felix

    2015-01-01

    Since 1986, Intercultural Development Research Association (IDRA) has conducted an annual attrition study to track the number and percent of students in Texas who are lost from public secondary school enrollment prior to graduation. The study builds on the series of studies that began when IDRA conducted the first comprehensive study of school…

  16. Texas Public School Attrition Study, 2015-16. IDRA Report

    Science.gov (United States)

    Johnson, Roy L.; Montes, Felix; Hinojosa, David

    2016-01-01

    Since 1986, Intercultural Development Research Association (IDRA) has conducted an annual attrition study to track the number and percent of students in Texas who are lost from public secondary school enrollment prior to graduation. The study builds on the series of studies that began when IDRA conducted the first comprehensive study of school…

  17. Attrition of Women Business Majors in an Urban Community College.

    Science.gov (United States)

    Karlen, Janice M.

    2004-01-01

    Identified intervention protocols that could help reduce the attrition of women business majors at an urban community college. Review of academic progress data and data from student surveys which examined students' reasons for leaving the institution indicated that there was a need for support mechanisms throughout the freshman year and extending…

  18. The Effects of Turnover: What We Know about Teacher Attrition

    Science.gov (United States)

    DeAngelis, Karen

    2012-01-01

    School business officials are likely to know better than anyone else about the financial costs to districts and schools associated with teacher attrition. Perhaps less well-known, though, is what else has been learned about this issue in recent years--information that may affect how one thinks about teacher turnover. Here is some of that research:…

  19. Teacher Attrition Variables That Influence Retention and Job Satisfaction

    Science.gov (United States)

    Butler, Leslie Garmon

    2014-01-01

    Teacher attrition is a major problem. According to researchers at North Carolina State University, more teachers are leaving the profession than staying or entering. Accordingly, school systems in the United States find themselves in the predicament where they must hire teachers who have little teaching experience or who have not been adequately…

  20. The Career Officer Attrition Dilemma: An Underlying Cause

    Science.gov (United States)

    2002-04-09

    BOOMER, XER, & MILLENIAL TRAITS COMPARISON ..................................... 23 vii viii THE CAREER OFFICER ATTRITION DILEMMA: AN UNDERLYING...provide a sustainable solution. Multiple generations in the military will always be present. What will change, however, is which generation will be in the... MILLENIAL TRAITS COMPARISON cause serious frustration both for the senior leadership and their subordinates. Even as the Xers begin to take over from

  1. Evolutionary dynamics of a smoothed war of attrition game.

    Science.gov (United States)

    Iyer, Swami; Killingback, Timothy

    2016-05-07

    In evolutionary game theory the War of Attrition game is intended to model animal contests which are decided by non-aggressive behavior, such as the length of time that a participant will persist in the contest. The classical War of Attrition game assumes that no errors are made in the implementation of an animal׳s strategy. However, it is inevitable in reality that such errors must sometimes occur. Here we introduce an extension of the classical War of Attrition game which includes the effect of errors in the implementation of an individual׳s strategy. This extension of the classical game has the important feature that the payoff is continuous, and as a consequence admits evolutionary behavior that is fundamentally different from that possible in the original game. We study the evolutionary dynamics of this new game in well-mixed populations both analytically using adaptive dynamics and through individual-based simulations, and show that there are a variety of possible outcomes, including simple monomorphic or dimorphic configurations which are evolutionarily stable and cannot occur in the classical War of Attrition game. In addition, we study the evolutionary dynamics of this extended game in a variety of spatially and socially structured populations, as represented by different complex network topologies, and show that similar outcomes can also occur in these situations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Accuracy assessment of high-rate GPS measurements for seismology

    Science.gov (United States)

    Elosegui, P.; Davis, J. L.; Ekström, G.

    2007-12-01

    Analysis of GPS measurements with a controlled laboratory system, built to simulate the ground motions caused by tectonic earthquakes and other transient geophysical signals such as glacial earthquakes, enables us to assess the technique of high-rate GPS. The root-mean-square (rms) position error of this system when undergoing realistic simulated seismic motions is 0.05~mm, with maximum position errors of 0.1~mm, thus providing "ground truth" GPS displacements. We have acquired an extensive set of high-rate GPS measurements while inducing seismic motions on a GPS antenna mounted on this system with a temporal spectrum similar to real seismic events. We found that, for a particular 15-min-long test event, the rms error of the 1-Hz GPS position estimates was 2.5~mm, with maximum position errors of 10~mm, and the error spectrum of the GPS estimates was approximately flicker noise. These results may however represent a best-case scenario since they were obtained over a short (~10~m) baseline, thereby greatly mitigating baseline-dependent errors, and when the number and distribution of satellites on the sky was good. For example, we have determined that the rms error can increase by a factor of 2--3 as the GPS constellation changes throughout the day, with an average value of 3.5~mm for eight identical, hourly-spaced, consecutive test events. The rms error also increases with increasing baseline, as one would expect, with an average rms error for a ~1400~km baseline of 9~mm. We will present an assessment of the accuracy of high-rate GPS based on these measurements, discuss the implications of this study for seismology, and describe new applications in glaciology.

  3. Australian high-dose-rate brachytherapy protocols for gynaecological malignancy

    International Nuclear Information System (INIS)

    MacLeod, C.; Dally, M.; Stevens, M.; Thornton, D.; Carruthers, S.; Jeal, P.

    2001-01-01

    There is no consensus over the optimal dose fractionation schedules for high-dose-rate (HDR) brachytherapy used for gynaecological malignancy. In Australian public hospital departments of radiation oncology, HDR brachytherapy for gynaecological cancer is being more commonly used. A survey of public departments that are using this technology, or that plan to introduce this technology, was performed. Their current protocols are presented. In general, protocols are similar biologically; however, the practical aspects such as the number of fractions given do vary and may reflect resource restrictions or, alternatively, differences in interpretations of the literature and of the best protocols by clinicians. Copyright (2001) Blackwell Science Pty Ltd

  4. Development of ultra high speed photographic system using high repetition rate visible laser

    International Nuclear Information System (INIS)

    Lee, Jong Min; Cha, Byung Hun; Kim, Sung Ho; Kim, Jung Bog; Lim, Chang Hwan; Cha, Hyung Ki; Song, Kyu Seok; Lee, Byung Deok; Rhi, Jong Hoon; Baik, Dae Hyun; Han, Jae Min; Rho, Si Pyo; Lee, Byung Cheol; Jeong, Do Yung; Choi, An Seong; Jeong, Chan Ik; Park, Dae Ung; Jeong, Sung Min; Lee, Sang Kil; Kim, Heon Jun; Jang, Rae gak; Jo, Do Hun; Park, Min Young

    1992-12-01

    The goal of this project is to develop and commercialize a high speed photographic system equipped with a high repetition rate visible laser. The developed system provides the characteristics of high time resolution and large number of frames. The system consists of 10 W air cooled CVL or a 30 W water cooled CVL, a rotating drum-type high speed camera with the framing rate of 35,000 fps, and a automatic control device. The system has the performance of 10 nsec time resolution, 35,000 fps framing rate, and 250 picture frames. The high speed photographic systems are widely applied to the fields such as high-efficient engine development, high-speed vibration analysis, shock wave propagation study, flow visualization analysis, weapon development, etc. (Author)

  5. High dose rate versus low dose rate interstitial radiotherapy for carcinoma of the floor of mouth

    International Nuclear Information System (INIS)

    Inoue, Takehiro; Inoue, Toshihiko; Yamazaki, Hideya; Koizumi, Masahiko; Kagawa, Kazufumi; Yoshida, Ken; Shiomi, Hiroya; Imai, Atsushi; Shimizutani, Kimishige; Tanaka, Eichii; Nose, Takayuki; Teshima, Teruki; Furukawa, Souhei; Fuchihata, Hajime

    1998-01-01

    Purpose: Patients with cancer of the floor of mouth are treated with radiation because of functional and cosmetic reasons. We evaluate the treatment results of high dose rate (HDR) and low dose rate (LDR) interstitial radiation for cancer of the floor of mouth. Methods and Materials: From January 1980 through March 1996, 41 patients with cancer of the floor of mouth were treated with LDR interstitial radiation using 198 Au grains, and from April 1992 through March 1996 16 patients with HDR interstitial radiation. There were 26 T1 tumors, 30 T2 tumors, and 1 T3 tumor. For 21 patients treated with interstitial radiation alone, a total radiation dose of interstitial therapy was 60 Gy/10 fractions/6-7 days in HDR and 85 Gy within 1 week in LDR. For 36 patients treated with a combination therapy, a total dose of 30 to 40 Gy of external radiation and a total dose of 48 Gy/8 fractions/5-6 days in HDR or 65 Gy within 1 week in LDR were delivered. Results: Two- and 5-year local control rates of patients treated with HDR interstitial radiation were 94% and 94%, and those with LDR were 75% and 69%, respectively. Local control rate of patients treated with HDR brachytherapy was slightly higher than that with 198 Au grains (p = 0.113). For late complication, bone exposure or ulcer occurred in 6 of 16 (38%) patients treated with HDR and 13 of 41 (32%) patients treated with LDR. Conclusion: HDR fractionated interstitial brachytherapy can be an alternative to LDR brachytherapy for cancer of the floor of mouth and eliminate radiation exposure for the medical staff

  6. Automated Production of High Rep Rate Foam Targets

    Science.gov (United States)

    Hall, F.; Spindloe, C.; Haddock, D.; Tolley, M.; Nazarov, W.

    2016-04-01

    Manufacturing low density targets in the numbers needed for high rep rate experiments is highly challenging. This report summarises advances from manual production to semiautomated and the improvements that follow both in terms of production time and target uniformity. The production process is described and shown to be improved by the integration of an xyz robot with dispensing capabilities. Results are obtained from manual and semiautomated production runs and compared. The variance in the foam thickness is reduced significantly which should decrease experimental variation due to target parameters and could allow for whole batches to be characterised by the measurement of a few samples. The work applies to both foil backed and free standing foam targets.

  7. New Approach to reduce High School Dropout Rates

    Directory of Open Access Journals (Sweden)

    Mauricio Cristhian Portillo-Torres

    2015-05-01

    Full Text Available From 2006 to 2014, the Ministry of Public Education of Costa Rica implemented four strategic actions to reduce high school dropout rates. The main purpose of these actions was to promote student participation and student identification with their school. Studies prepared by the Ministry of Education and the Comptroller of the Republic were revised to assess the impact of these actions. The result of these actions does not show an actual decrease in the number of students who leave high school. Therefore, a more holistic view is necessary to ensure the students’ stay. This review suggests using use the concept of student engagement and applying a three tier system-wide dropout preventive actions: universal, targeted and intensive.

  8. High repetition rate driver circuit for modulation of injection lasers

    International Nuclear Information System (INIS)

    Dornan, B.R.; Goel, J.; Wolkstein, H.J.

    1981-01-01

    An injection laser modulator comprises a self-biased field effect transistor (FET) and an injection laser to provide a quiescent state during which lasing of the injection laser occurs in response to a high repetition rate signal of pulse coded modulation (pcm). The modulator is d.c. coupled to an input pulse source of pcm rendering it compatible with an input pulse referenced to ground and not being subject to voltage level shifting of the input pulse. The modulator circuit in its preferred and alternate embodiments provides various arrangements for high impedance input and low impedance output matching. In addition, means are provided for adjusting the bias of the FET as well as the bias of the injection laser

  9. High-rate lithium thionyl-chloride battery development

    Energy Technology Data Exchange (ETDEWEB)

    Cieslak, W.R.; Weigand, D.E.

    1993-12-31

    We have developed a lithium thionyl-chloride cell for use in a high rate battery application to provide power for a missile computer and stage separation detonators. The battery pack contains 20 high surface area ``DD`` cells wired in a series-parallel configuration to supply a nominal 28 volts with a continuous draw of 20 amperes. The load profile also requires six squib firing pulses of one second duration at a 20 ampere peak. Performance and safety of the cells were optimized in a ``D`` cell configuration before progressing to the longer ``DD` cell. Active surface area in the ``D`` cell is 735 cm{sup 2}, and 1650 cm{sup 2} in the ``DD`` cell. The design includes 1.5M LiAlCl{sub 4}/SOCl{sub 2} electrolyte, a cathode blend of Shawinigan Acetylene Black and Cabot Black Pearls 2000 carbons, Scimat ETFE separator, and photoetched current collectors.

  10. On the response of rubbers at high strain rates.

    Energy Technology Data Exchange (ETDEWEB)

    Niemczura, Johnathan Greenberg (University of Texas-Austin)

    2010-02-01

    In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between the experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.

  11. High rate capability of lithium/silver vanadium oxide cells

    International Nuclear Information System (INIS)

    Takeuchi, E.S.; Zelinsky, M.A.; Keister, P.

    1986-01-01

    High rate characteristics of the lithium/silver vanadium oxide system were investigated in test cells providing four different limiting surface areas. The cells were tested by constant current and constant resistance discharge with current densities ranging from 0.04 to 6.4 mA/cm/sup 2/. The maximum current density under constant resistance and constant current discharges which would deliver 50% of theoretical capacity was determined. The ability of the cells to deliver high current pulses was evaluated by application of 10 second pulses with current densities ranging from 3 to 30 mA/cm/sup 2/. The voltage delay characteristics of the cells were determined after 1 to 3 months of storage at open circuit voltage or under low level background currents. The volumetric and gravimetric energy density of the SVO system is compared to other cathode materials

  12. Low power ion spectrometer for high counting rates

    International Nuclear Information System (INIS)

    Klein, J.W.; Dullenkopf, P.; Glasmachers, A.; Melbert, J.; Winkelnkemper, W.

    1980-01-01

    This report describes in detail the electronic concept for a time-of-flight (TOF) ion spectrometer for high counting rates and high dynamic range which can be used as a satellite instrument. The detection principle of the spectrometer is based on a time-of-flight and energy measurement for each incident ion. The ionmass is related to these two quantities by a simple equation. The described approach for the mass identification systems is using an analog fast-slow concept: The fast TOF-signal preselects the gainstep in the much slower energy channel. The conversion time of the mass identifier is approximately 10 -6 s and the dynamic range of the energy channel is better than 10 3 (20 keV to 25 MeV). The purpose of this study was to demonstrate the feasibility of a TOF-spectrometer capable to measure the ion composition in planetary magnetospheres. (orig.) [de

  13. Radiation Parameters of High Dose Rate Iridium -192 Sources

    Science.gov (United States)

    Podgorsak, Matthew B.

    A lack of physical data for high dose rate (HDR) Ir-192 sources has necessitated the use of basic radiation parameters measured with low dose rate (LDR) Ir-192 seeds and ribbons in HDR dosimetry calculations. A rigorous examination of the radiation parameters of several HDR Ir-192 sources has shown that this extension of physical data from LDR to HDR Ir-192 may be inaccurate. Uncertainty in any of the basic radiation parameters used in dosimetry calculations compromises the accuracy of the calculated dose distribution and the subsequent dose delivery. Dose errors of up to 0.3%, 6%, and 2% can result from the use of currently accepted values for the half-life, exposure rate constant, and dose buildup effect, respectively. Since an accuracy of 5% in the delivered dose is essential to prevent severe complications or tumor regrowth, the use of basic physical constants with uncertainties approaching 6% is unacceptable. A systematic evaluation of the pertinent radiation parameters contributes to a reduction in the overall uncertainty in HDR Ir-192 dose delivery. Moreover, the results of the studies described in this thesis contribute significantly to the establishment of standardized numerical values to be used in HDR Ir-192 dosimetry calculations.

  14. High-rep-rate Thomson scattering for LHD

    Science.gov (United States)

    den Hartog, D. J.; Borchardt, M. T.; Holly, D. J.; Schmitz, O.; Yasuhara, R.; Yamada, I.; Funaba, H.; Osakabe, M.; Morisaki, T.

    2017-10-01

    A high-rep-rate pulse-burst laser system is being built for the LHD Thomson scattering (TS) diagnostic. This laser will have two operating scenarios, a fast-burst sequence of 15 kHz rep rate for at least 15 ms, and a slow-burst sequence of 1 kHz for at least 50 ms. There will be substantial flexibility in burst sequences for tailoring to experimental requirements. This new laser system will operate alongside the existing lasers in the LHD TS diagnostic, and will use the same beamline. This increase in temporal resolution capability complements the high spatial resolution (144 points) of the LHD TS diagnostic, providing unique measurement capability unmatched on any other fusion experiment. The new pulse-burst laser is a straightforward application of technology developed at UW-Madison, consisting of a Nd:YAG laser head with modular flashlamp drive units and a customized control system. Variable pulse-width drive of the flashlamps is accomplished by IGBT (insulated gate bipolar transistor) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, producing >1.5 J q-switched pulses with 20 ns FWHM. Burst operation of this laser system will be used to capture fast time evolution of the electron temperature and density profiles during events such as ELMs, RMP perturbations, and various MHD modes. This work is supported by the U. S. Department of Energy and the National Institute for Fusion Science (Japan).

  15. Radiation safety program in a high dose rate brachytherapy facility

    International Nuclear Information System (INIS)

    Rodriguez, L.V.; Hermoso, T.M.; Solis, R.C.

    2001-01-01

    The use of remote afterloading equipment has been developed to improve radiation safety in the delivery of treatment in brachytherapy. Several accidents, however, have been reported involving high dose-rate brachytherapy system. These events, together with the desire to address the concerns of radiation workers, and the anticipated adoption of the International Basic Safety Standards for Protection Against Ionizing Radiation (IAEA, 1996), led to the development of the radiation safety program at the Department of Radiotherapy, Jose R. Reyes Memorial Medical Center and at the Division of Radiation Oncology, St. Luke's Medical Center. The radiation safety program covers five major aspects: quality control/quality assurance, radiation monitoring, preventive maintenance, administrative measures and quality audit. Measures for evaluation of effectiveness of the program include decreased unnecessary exposures of patients and staff, improved accuracy in treatment delivery and increased department efficiency due to the development of staff vigilance and decreased anxiety. The success in the implementation required the participation and cooperation of all the personnel involved in the procedures and strong management support. This paper will discuss the radiation safety program for a high dose rate brachytherapy facility developed at these two institutes which may serve as a guideline for other hospitals intending to install a similar facility. (author)

  16. Portable radiation meters evaluation in high rates of air kerma

    International Nuclear Information System (INIS)

    Damatto, Willian B.; Potiens, Maria da Penha A.; Vivolo, Vitor

    2015-01-01

    A set of portable meters of ionizing radiation high rates of air kerma (teletectors) commonly used in emergencies in Brazil and sent to the Calibration Laboratory of IPEN were under several tests and analyst is parameters for the detectors behavior were established, specifying their sensitivities and operating characteristics. Applied tests were: reading equipment variation with battery voltage, geotropism effect, energy dependence, the angular dependence and overload. Thus it was possible to determine the most common characteristic found in these equipment (quality control programs). The behavior of 17 portable meters was analyzed and in this study, 10 of them have been tested. It was performed to characterize the gamma irradiating system (radiation dosimetry field) that possesses higher activity in teletectors for testing of larger measuring range. New calibration criteria were established following international recommendations. Therefore, it was made the improvement of the quality control programme of portable meters of ionizing radiation high rates of air kerma calibration laboratory, benefiting the users of such equipment with better consistent calibration measurements. (author)

  17. Audits in high dose rate brachytherapy in Brazil

    International Nuclear Information System (INIS)

    Marechal, M.H.; Rosa, L.A.; Velasco, A.; Paiva, E. de; Goncalves, M.; Castelo, L.C.

    2002-01-01

    The lack of well established dosimetry protocols for HDR sources is a point of great concern regarding the uniformity of procedures within a particular country. The main objective of this paper is to report the results of an implementation of the audit program in dosimetry of high dose rate brachytherapy sources used by the radiation therapy centers in Brazil. In Brazil, among 169 radiotherapy centers, 35 have HDR brachytherapy systems. This program started in August 2001 and until now eight radiotherapy services were audited. The audit program consists of the visit in loco to each center and the evaluation of the intensity of the source with a well type chamber specially design for HDR 192 Ir sources. The measurements was carried out with a HDR1000PLUS Brachytherapy Well Type Chamber and a MAX 4000 Electrometer, both manufactured by Standard Imaging Inc. The chamber was calibrated in air kerma strength by the Accredited Dosimetry Calibration Laboratory, Department of Medical Physics, University of Wisconsin in the USA. The same chamber was calibrated in Brazil using a 192 lr high dose rate source whose intensity was determined by 60 Co gamma rays and 250 kV x rays interpolation methodology. The Nk of 60 Co and 250 kV x rays were provided by the Brazilian National Standard Laboratory for Ionizing Radiation (LMNRI)

  18. High-temperature rate constant measurements for OH+xylenes

    KAUST Repository

    Elwardani, Ahmed Elsaid

    2015-06-01

    The overall rate constants for the reactions of hydroxyl (OH) radicals with o-xylene (k 1), m-xylene (k 2), and p-xylene (k 3) were measured behind reflected shock waves over 890-1406K at pressures of 1.3-1.8atm using OH laser absorption near 306.7nm. Measurements were performed under pseudo-first-order conditions. The measured rate constants, inferred using a mechanism-fitting approach, can be expressed in Arrhenius form as:k1=2.93×1013exp(-1350.3/T)cm3mol-1s-1(890-1406K)k2=3.49×1013exp(-1449.3/T)cm3mol-1s-1(906-1391K)k3=3.5×1013exp(-1407.5/T)cm3mol-1s-1(908-1383K)This paper presents, to our knowledge, first high-temperature measurements of the rate constants of the reactions of xylene isomers with OH radicals. Low-temperature rate-constant measurements by Nicovich et al. (1981) were combined with the measurements in this study to obtain the following Arrhenius expressions, which are applicable over a wider temperature range:k1=2.64×1013exp(-1181.5/T)cm3mol-1s-1(508-1406K)k2=3.05×109exp(-400/T)cm3mol-1s-1(508-1391K)k3=3.0×109exp(-440/T)cm3mol-1s-1(526-1383K) © 2015 The Combustion Institute.

  19. A high repetition rate XUV seeding source for FLASH2

    International Nuclear Information System (INIS)

    Willner, Arik

    2012-05-01

    Improved performance of free-electron laser (FEL) light sources in terms of timing stability, pulse shape and spectral properties of the amplified FEL pulses is of interest in material science, the fields of ultrafast dynamics, biology, chemistry and even special branches in industry. A promising scheme for such an improvement is direct seeding with high harmonic generation (HHG) in a noble gas target. A free-electron laser seeded by an external extreme ultraviolet (XUV) source is planned for FLASH2 at DESY in Hamburg. The requirements for the XUV/soft X-ray source can be summarized as follows: A repetition rate of at least 100 kHz in a 10 Hz burst is needed at variable wavelengths from 10 to 40 nm and pulse energies of several nJ within a single laser harmonic. This application requires a laser amplifier system with exceptional parameters, mJ-level pulse energy, 10-15 fs pulse duration at 100 kHz (1 MHz) burst repetition rate. A new optical parametric chirped-pulse amplification (OPCPA) system is under development in order to meet these requirements, and very promising results have been achieved in the last three years. In parallel to this development, a new HHG concept is necessary to sustain high average power of the driving laser system and to generate harmonics with high conversion efficiencies. Currently, the highest conversion efficiency with HHG has been demonstrated using gas-filled capillary targets. For our application, only a free-jet target can be used for HHG, in order to overcome damage threshold limitations of HHG target optics at a high repetition rate. A novel dual-gas multijet gas target has been developed and first experiments show remarkable control of the degree of phase matching forming the basis for improved control of the harmonic photon flux and the XUV pulse characteristics. The basic idea behind the dual-gas concept is the insertion of matching zones in between multiple HHG sources. These matching sections are filled with hydrogen which

  20. A high repetition rate XUV seeding source for FLASH2

    Energy Technology Data Exchange (ETDEWEB)

    Willner, Arik

    2012-05-15

    Improved performance of free-electron laser (FEL) light sources in terms of timing stability, pulse shape and spectral properties of the amplified FEL pulses is of interest in material science, the fields of ultrafast dynamics, biology, chemistry and even special branches in industry. A promising scheme for such an improvement is direct seeding with high harmonic generation (HHG) in a noble gas target. A free-electron laser seeded by an external extreme ultraviolet (XUV) source is planned for FLASH2 at DESY in Hamburg. The requirements for the XUV/soft X-ray source can be summarized as follows: A repetition rate of at least 100 kHz in a 10 Hz burst is needed at variable wavelengths from 10 to 40 nm and pulse energies of several nJ within a single laser harmonic. This application requires a laser amplifier system with exceptional parameters, mJ-level pulse energy, 10-15 fs pulse duration at 100 kHz (1 MHz) burst repetition rate. A new optical parametric chirped-pulse amplification (OPCPA) system is under development in order to meet these requirements, and very promising results have been achieved in the last three years. In parallel to this development, a new HHG concept is necessary to sustain high average power of the driving laser system and to generate harmonics with high conversion efficiencies. Currently, the highest conversion efficiency with HHG has been demonstrated using gas-filled capillary targets. For our application, only a free-jet target can be used for HHG, in order to overcome damage threshold limitations of HHG target optics at a high repetition rate. A novel dual-gas multijet gas target has been developed and first experiments show remarkable control of the degree of phase matching forming the basis for improved control of the harmonic photon flux and the XUV pulse characteristics. The basic idea behind the dual-gas concept is the insertion of matching zones in between multiple HHG sources. These matching sections are filled with hydrogen which

  1. High rate response of ultra-high-performance fiber-reinforced concretes under direct tension

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Ngoc Thanh [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Tran, Tuan Kiet [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Department of Civil Engineering and Applied Mechanics, Ho Chi Minh City University of Technology and Education, 01 Vo Van Ngan, Thu Duc District, Ho Chi Minh City (Viet Nam); Kim, Dong Joo, E-mail: djkim75@sejong.ac.kr [Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of)

    2015-03-15

    The tensile response of ultra-high-performance fiber-reinforced concretes (UHPFRCs) at high strain rates (5–24 s{sup −} {sup 1}) was investigated. Three types of steel fibers, including twisted, long and short smooth steel fibers, were added by 1.5% volume content in an ultra high performance concrete (UHPC) with a compressive strength of 180 MPa. Two different cross sections, 25 × 25 and 25 × 50 mm{sup 2}, of tensile specimens were used to investigate the effect of the cross section area on the measured tensile response of UHPFRCs. Although all the three fibers generated strain hardening behavior even at high strain rates, long smooth fibers produced the highest tensile resistance at high rates whereas twisted fiber did at static rate. The breakages of twisted fibers were observed from the specimens tested at high strain rates unlike smooth steel fibers. The tensile behavior of UHPFRCs at high strain rates was clearly influenced by the specimen size, especially in post-cracking strength.

  2. High Data Rate Satellite Communications for Environmental Remote Sensing

    Science.gov (United States)

    Jackson, J. M.; Munger, J.; Emch, P. G.; Sen, B.; Gu, D.

    2014-12-01

    Satellite to ground communication bandwidth limitations place constraints on current earth remote sensing instruments which limit the spatial and spectral resolution of data transmitted to the ground for processing. Instruments such as VIIRS, CrIS and OMPS on the Soumi-NPP spacecraft must aggregate data both spatially and spectrally in order to fit inside current data rate constraints limiting the optimal use of the as-built sensors. Future planned missions such as HyspIRI, SLI, PACE, and NISAR will have to trade spatial and spectral resolution if increased communication band width is not made available. A number of high-impact, environmental remote sensing disciplines such as hurricane observation, mega-city air quality, wild fire detection and monitoring, and monitoring of coastal oceans would benefit dramatically from enabling the downlinking of sensor data at higher spatial and spectral resolutions. The enabling technologies of multi-Gbps Ka-Band communication, flexible high speed on-board processing, and multi-Terabit SSRs are currently available with high technological maturity enabling high data volume mission requirements to be met with minimal mission constraints while utilizing a limited set of ground sites from NASA's Near Earth Network (NEN) or TDRSS. These enabling technologies will be described in detail with emphasis on benefits to future remote sensing missions currently under consideration by government agencies.

  3. High fall incidence and fracture rate in elderly dialysis patients.

    Science.gov (United States)

    Polinder-Bos, H A; Emmelot-Vonk, M H; Gansevoort, R T; Diepenbroek, A; Gaillard, C A J M

    2014-12-01

    Although it is recognised that the dialysis population is ageing rapidly, geriatric complications such as falls are poorly appreciated, despite the many risk factors for falls in this population. The objective of this study was to determine the incidence, complications and risk factors for falls in an elderly dialysis population. A one-year observational study of chronic dialysis patients aged ≥ 70 years. At baseline, patient characteristics were noted and during follow-up the vital parameters and laboratory values were recorded. Patients were questioned weekly about falls, fall circumstances and consequences by trained nurses. 49 patients were included with a median age of 79.3 years (70-89 years). During follow-up 40 fall accidents occurred in 27 (55%) patients. Falls resulted in fractures in 15% of cases and in hospital admissions in 15%. In haemodialysis (HD) patients, the mean systolic blood pressure (SBP) before HD was lower in fallers compared with non-fallers (130 vs. 143 mmHg). Several patients in the lower blood pressure category received antihypertensive medication. For every 5 mmHg lower SBP (before HD) the fall risk increased by 30% (hazard ratio (HR) 1.30, 95% CI 1.03-1.65, p = 0.03). Furthermore, fall risk increased by 22% for every 10 pmol/l rise of parathyroid hormone (HR 1.22, 95% CI 1.06-1.39, p = 0.004). Elderly dialysis patients have a high incidence of falls accompanied by a high fracture rate. Given the high complication rate, elderly patients at risk of falling should be identified and managed. Reduction of blood pressure-lowering medication might be a treatment strategy to reduce falls.

  4. Cosmological Evolution of the Central Engine in High-Luminosity, High-Accretion Rate AGN

    Directory of Open Access Journals (Sweden)

    Matteo Guainazzi

    2014-12-01

    Full Text Available In this paper I discuss the status of observational studies aiming at probing the cosmological evolution of the central engine in high-luminosity, high-accretion rate Active Galactic Nuclei (AGN. X-ray spectroscopic surveys, supported by extensive multi-wavelength coverage, indicate a remarkable invariance of the accretion disk plus corona system, and of their coupling up to redshifts z≈6. Furthermore, hard X-ray (E >10 keV surveys show that nearby Seyfert Galaxies share the same central engine notwithstanding their optical classication. These results suggest that the high-luminosity, high accretion rate quasar phase of AGN evolution is homogeneous over cosmological times.

  5. High bit rate germanium single photon detectors for 1310nm

    Science.gov (United States)

    Seamons, J. A.; Carroll, M. S.

    2008-04-01

    There is increasing interest in development of high speed, low noise and readily fieldable near infrared (NIR) single photon detectors. InGaAs/InP Avalanche photodiodes (APD) operated in Geiger mode (GM) are a leading choice for NIR due to their preeminence in optical networking. After-pulsing is, however, a primary challenge to operating InGaAs/InP single photon detectors at high frequencies1. After-pulsing is the effect of charge being released from traps that trigger false ("dark") counts. To overcome this problem, hold-off times between detection windows are used to allow the traps to discharge to suppress after-pulsing. The hold-off time represents, however, an upper limit on detection frequency that shows degradation beginning at frequencies of ~100 kHz in InGaAs/InP. Alternatively, germanium (Ge) single photon avalanche photodiodes (SPAD) have been reported to have more than an order of magnitude smaller charge trap densities than InGaAs/InP SPADs2, which allowed them to be successfully operated with passive quenching2 (i.e., no gated hold off times necessary), which is not possible with InGaAs/InP SPADs, indicating a much weaker dark count dependence on hold-off time consistent with fewer charge traps. Despite these encouraging results suggesting a possible higher operating frequency limit for Ge SPADs, little has been reported on Ge SPAD performance at high frequencies presumably because previous work with Ge SPADs has been discouraged by a strong demand to work at 1550 nm. NIR SPADs require cooling, which in the case of Ge SPADs dramatically reduces the quantum efficiency of the Ge at 1550 nm. Recently, however, advantages to working at 1310 nm have been suggested which combined with a need to increase quantum bit rates for quantum key distribution (QKD) motivates examination of Ge detectors performance at very high detection rates where InGaAs/InP does not perform as well. Presented in this paper are measurements of a commercially available Ge APD

  6. A digital approach for real time high-rate high-resolution radiation measurements

    International Nuclear Information System (INIS)

    Gerardi, G.; Abbene, L.

    2014-01-01

    Modern spectrometers are currently developed by using digital pulse processing (DPP) systems, showing several advantages over traditional analog electronics. The aim of this work is to present digital strategies, in a time domain, for the development of real time high-rate high-resolution spectrometers. We propose a digital method, based on the single delay line (SDL) shaping technique, able to perform multi-parameter analysis with high performance even at high photon counting rates. A robust pulse shape and height analysis (PSHA), applied on single isolated time windows of the detector output waveforms, is presented. The potentialities of the proposed strategy are highlighted through both theoretical and experimental approaches. To strengthen our approach, the implementation of the method on a real-time system together with some experimental results are presented. X-ray spectra measurements with a semiconductor detector are performed both at low and high photon counting rates (up to 1.1 Mcps)

  7. A digital approach for real time high-rate high-resolution radiation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gerardi, G.; Abbene, L., E-mail: leonardo.abbene@unipa.it

    2014-12-21

    Modern spectrometers are currently developed by using digital pulse processing (DPP) systems, showing several advantages over traditional analog electronics. The aim of this work is to present digital strategies, in a time domain, for the development of real time high-rate high-resolution spectrometers. We propose a digital method, based on the single delay line (SDL) shaping technique, able to perform multi-parameter analysis with high performance even at high photon counting rates. A robust pulse shape and height analysis (PSHA), applied on single isolated time windows of the detector output waveforms, is presented. The potentialities of the proposed strategy are highlighted through both theoretical and experimental approaches. To strengthen our approach, the implementation of the method on a real-time system together with some experimental results are presented. X-ray spectra measurements with a semiconductor detector are performed both at low and high photon counting rates (up to 1.1 Mcps)

  8. High dose rate versus medium dose rate intraluminal brachytherapy in inoperable esophageal carcinoma

    International Nuclear Information System (INIS)

    Langendijk, J.; Jager, J.; Jong, J. de; Rijken, J.; Pannebakker, M.

    1996-01-01

    Introduction: The purpose of this study was to compare the results of medium dose rate (MDR) intraluminal brachytherapy (ILBT) and high dose rate (HDR) ILBT in patients with inoperable esophageal carcinoma, with regard to dysphagia, complication rate and survival. Material and methods: Included were 114 patients with inoperable esophageal cancer who were treated with a single session of ILBT. In all cases a single dose of 15 Gy was administered, calculated at a 1 cm radius. Forty-eight patients were treated with MDR ( 137 Cs)ILBT. In June 1990 MDR was replaced by HDR and from then 66 patients were treated with HDR ( 192 Ir). Dysphagia was prospectively scored using a 5-point scale at 6 weeks, 3, 6, 9 and 12 months. Results: No significant differences were noted between the two groups with regard to pretreatment variables. In patients treated with MDR-ILBT improvement of swallowing ability was noted in 30 out of 42 evaluable patients (71%), no change in 9 (21%) and progression of dysphagia in 3 patients (8%), as compared to 34 out of 59 evaluable patients (58%), 16 (27%) and 6 (15%) resp. in de HDR-ILBT group. In the latter category, progression of dysphagia was caused by fistulae in 2 patients. The differences were not significant (ns). Additional treatment in case of recurrent or persistent dysphagia was needed in 50% of the cases in the MDR-ILBT group as compared to 41% in the HDR-ILBT group (ns). The median survival of the MDR-ILBT group was 3.9 months as compared to 4.3 months in the HDR-ILBT group (ns). In 2 patients (4%) treated with MDR-ILBT bronchio-oesphageal fistulae developed at 6 weeks and 2 months. In the HDR-ILBT group fistulae were noted in 7 cases (11%) at 2 weeks, 4 weeks, 2, 3, 3, 4 and 9 months (ns). In all of these cases persistent of recurrent tumour was present. Conclusions: No significant differences were noted with regard to palliation of dysphagia, survival and complication rate between MDR-ILBT and HDR-ILBT in the management of esophageal

  9. High-rate fermentative hydrogen production from beverage wastewater

    International Nuclear Information System (INIS)

    Sivagurunathan, Periyasamy; Sen, Biswarup; Lin, Chiu-Yue

    2015-01-01

    Highlights: • Hybrid immobilized-bacterial cells show stable operation over 175 days. • Low HRT of 1.5 h shows peak hydrogen production rate of 55 L/L-d. • Electricity generation is 9024 kW-d from 55 L/L-d hydrogen using beverage wastewater. • Granular sludge formed only at 2–3 h HRT with presence of Selenomonas sp. - Abstract: Hydrogen production from beverage industry wastewater (20 g/L hexose equivalent ) using an immobilized cell reactor with a continuous mode of operation was studied at various hydraulic retention times (HRT, 8–1.5 h). Maximum hydrogen production rate (HPR) of 55 L/L-d was obtained at HRT 1.5 h (an organic loading of 320 g/L-d hexose equivalent ). This HPR value is much higher than those of other industrial wastewaters employed in fermentative hydrogen production. The cell biomass concentration peaked at 3 h HRT with a volatile suspended solids (VSS) concentration of 6.31 g/L (with presence of self-flocculating Selenomonas sp.), but it dropped to 3.54 gVSS/L at 1.5 h HRT. With the shortening of HRT, lactate concentration increased but the concentration of the dominant metabolite butyrate did not vary significantly. The Clostridium species dynamics was not significantly affected, but total microbial community structure changed with respect to HRT variation as evident from PCR–DGGE analyses. Analysis of energy production rate suggests that beverage wastewater is a high energy yielding feedstock, and can replace 24% of electricity consumption in a model beverage industry

  10. RCS Leak Rate Calculation with High Order Least Squares Method

    International Nuclear Information System (INIS)

    Lee, Jeong Hun; Kang, Young Kyu; Kim, Yang Ki

    2010-01-01

    As a part of action items for Application of Leak before Break(LBB), RCS Leak Rate Calculation Program is upgraded in Kori unit 3 and 4. For real time monitoring of operators, periodic calculation is needed and corresponding noise reduction scheme is used. This kind of study was issued in Korea, so there have upgraded and used real time RCS Leak Rate Calculation Program in UCN unit 3 and 4 and YGN unit 1 and 2. For reduction of the noise in signals, Linear Regression Method was used in those programs. Linear Regression Method is powerful method for noise reduction. But the system is not static with some alternative flow paths and this makes mixed trend patterns of input signal values. In this condition, the trend of signal and average of Linear Regression are not entirely same pattern. In this study, high order Least squares Method is used to follow the trend of signal and the order of calculation is rearranged. The result of calculation makes reasonable trend and the procedure is physically consistence

  11. High dose rate brachytherapy for the palliation of malignant dysphagia

    International Nuclear Information System (INIS)

    Homs, Marjolein Y.V.; Eijkenboom, Wilhelmina M.H.; Coen, Veronique L.M.A.; Haringsma, Jelle; Blankenstein, Mark van; Kuipers, Ernst J.; Siersema, Peter D.

    2003-01-01

    Background and purpose: High dose rate (HDR) brachytherapy is a commonly used palliative treatment for esophageal carcinoma. We evaluated the outcome of HDR brachytherapy in patients with malignant dysphagia. Material and methods: A retrospective analysis over a 10-year period was performed of 149 patients treated with HDR brachytherapy, administered in one or two sessions, at a median dose of 15 Gy. Patients were evaluated for functional outcome, complications, recurrent dysphagia, and survival. Results: At 6 weeks after HDR brachytherapy, dysphagia scores had improved from a median of 3 to 2 (n=104; P<0.001), however, dysphagia had not improved in 51 (49%) patients. Procedure-related complications occurred in seven (5%) patients. Late complications, including fistula formation or bleeding, occurred in 11 (7%) patients. Twelve (8%) patients experienced minor retrosternal pain. Median survival of the patients was 160 days with a 1-year survival rate of 15%. Procedure-related mortality was 2%. At follow-up, 55 (37%) patients experienced recurrent dysphagia. In 34 (23%) patients a metal stent was placed to relieve persistent or recurrent dysphagia. Conclusion: HDR brachytherapy is a moderately effective treatment for the palliation of malignant dysphagia. The incidence of early major complications is low, however, persistent and recurrent dysphagia occur frequently, and require often additional treatment

  12. Decay rates of resonance states at high level density

    International Nuclear Information System (INIS)

    Persson, E.; Technische Univ. Dresden; Gorin, T.; Technische Univ. Dresden; Rotter, I.; Technische Univ. Dresden

    1996-05-01

    The time dependent Schroedinger equation of an open quantum mechanical system is solved by using the stationary bi-orthogonal eigenfunctions of the non-Hermitean time independent Hamilton operator. We calculate the decay rates at low and high level density in two different formalism. The rates are, generally, time dependent and oscillate around an average value due to the non-orthogonality of the wavefunctions. The decay law is studied disregarding the oscillations. In the one-channel case, it is proportional to t -b with b∼3/2 in all cases considered, including the critical region of overlapping where the non-orthogonality of the wavefunctions is large. Starting from the shell model, we get b∼2 for 2 and 4 open decay channels and all coupling strengths to the continuum. When the closed system is described by a random matrix, b∼1+K/2 for K=2 and 4 channels. This law holds in a limited time interval. The distribution of the widths is different in the two models when more than one channel are open. This leads to the different exponents b in the power law. Our calculations are performed with 190 and 130 states, respectively, most of them in the critical region. The theoretical results should be proven experimentally by measuring the time behaviour of de-excitation of a realistic quantum system. (orig.)

  13. Routine quality control of high dose rate brachytherapy equipment

    International Nuclear Information System (INIS)

    Guzman Calcina, Carmen S.; Almeida, Adelaide de; Rocha, Jose R. Oliveira

    2001-01-01

    A Quality Assurance program should be installed also for High Dose Rate brachytherapy, in the order to achieve a correct dose administration to the patient and for the safety to those involved directly with the treatment. The work presented here has the following purposes: Analyze the types of equipment tests presented by the official protocols (TG40, TG56 e ARCAL XXX), evaluate the brachytherapy routine tests of protocols from various national and international radiotherapy services and compare the latter with those presented in the official protocols. As a result, we conclude the following: TG56 presents a higher number of tests when compared to the other official protocols and most of the tests presented by the analyzed services are present in TG56. A suggestion for a basic protocol is presented, emphasizing the periodicity and tolerance level of each of the tests. (author)

  14. Behavior of fiber reinforced metal laminates at high strain rate

    Science.gov (United States)

    Newaz, Golam; Sasso, Marco; Amodio, Dario; Mancini, Edoardo

    2018-05-01

    Carbon Fiber Reinforced Aluminum Laminate (CARALL) is a good system for energy absorption through plastic deformation in aluminum and micro-cracking in the composite layers. Moreover, CARALL FMLs also provide excellent impact resistance due to the presence of aluminum layer. The focus of this research is to characterize the CARALL behavior under dynamic conditions. High strain rate tests on sheet laminate samples have been carried out by means of direct Split Hopkinson Tension Bar. The sample geometry and the clamping system were optimized by FEM simulations. The clamping system has been designed and optimized in order reduce impedance disturbance due to the fasteners and to avoid the excessive plastic strain outside the gauge region of the samples.

  15. Safety handling manual for high dose rate remote afterloading system

    International Nuclear Information System (INIS)

    1999-01-01

    This manual is mainly for safety handling of 192 Ir-RALS (remote afterloading system) of high dose rate and followings were presented: Procedure and document format for the RALS therapy and for handling of its radiation source with the purpose of prevention of human errors and unexpected accidents, Procedure for preventing errors occurring in the treatment schedule and operation, and Procedure and format necessary for newly introducing the system into a facility. Consistency was intended in the description with the quality assurance guideline for therapy with small sealed radiation sources made by JASTRO (Japan Society for Therapeutic Radiology and Oncology). Use of the old type 60 Co-RALS was pointed out to be a serious problem remained and its safety handling procedure was also presented. (K.H.)

  16. Calibration of {sup 192}Ir high dose rate brachytherapy sources

    Energy Technology Data Exchange (ETDEWEB)

    Marechal, M H [Instituto de Radioprotecao e Dozimetria, Rio de Jainero (Brazil); Almeida, C.E. de [Laboratorio de Ciencias Radiologicas, UERL, Rio de Janeiro (Brazil); Sibata, C H [Roswell Park Cancer Inst., Buffalo, NY (United States)

    1996-08-01

    A method for calibration of high dose rate sources used in afterloading brachytherapy systems is described. The calibration for {sup 192}Ir is determined by interpolating {sup 60}Co gamma-rays and 250 kV x-rays calibration factors. All measurements were done using the same build up caps as described by Goetsch et al and recommended by AAPM. The attenuation correction factors were determined to be 0.9903, 0.9928 and 0.9993 for {sup 192}Ir, {sup 60}Co and 250 kV x-ray, respectively. A wall + cap thickness of 0.421 g.cm{sup -2} is recommended for all measurements to ensure electronic equilibrium for {sup 60}Co and {sup 192}Ir gamma-ray beams. A mathematical formalism is described for determination of (N{sub x}){sub Ir}. (author). 5 refs, 1 fig.

  17. Closed cycle high-repetition-rate pulsed HF laser

    Science.gov (United States)

    Harris, Michael R.; Morris, A. V.; Gorton, Eric K.

    1997-04-01

    The design and performance of a closed cycle high repetition rate HF laser is described. A short pulse, glow discharge is formed in a 10 SF6:1 H2 gas mixture at a total pressure of approximately 110 torr within a 15 by 0.5 by 0.5 cm3 volume. Transverse, recirculated gas flow adequate to enable repetitive operation up to 3 kHz is imposed by a centrifugal fan. The fan also forces the gas through a scrubber cell to eliminate ground state HF from the gas stream. An automated gas make-up system replenishes spent gas removed by the scrubber. Typical mean laser output powers up to 3 W can be maintained for extended periods of operation.

  18. Pulsed dose rate and fractionated high dose rate brachytherapy: choice of brachytherapy schedules to replace low dose rate treatments

    International Nuclear Information System (INIS)

    Visser, Andries G.; Aardweg, Gerard J.M.J. van den; Levendag, Peter C.

    1996-01-01

    Purpose: Pulsed dose rate (PDR) brachytherapy is a new type of afterloading brachytherapy (BT) in which a continuous low dose rate (LDR) treatment is simulated by a series of 'pulses,' i.e., fractions of short duration (less than 0.5 h) with intervals between fractions of 1 to a few hours. At the Dr. Daniel den Hoed Cancer Center, the term 'PDR brachytherapy' is used for treatment schedules with a large number of fractions (at least four per day), while the term 'fractionated high dose rate (HDR) brachytherapy' is used for treatment schedules with just one or two brachytherapy fractions per day. Both treatments can be applied as alternatives for LDR BT. This article deals with the choice between PDR and fractionated HDR schedules and proposes possible fractionation schedules. Methods and Materials: To calculate HDR and PDR fractionation schedules with the intention of being equivalent to LDR BT, the linear-quadratic (LQ) model has been used in an incomplete repair formulation as given by Brenner and Hall, and by Thames. In contrast to earlier applications of this model, both the total physical dose and the overall time were not kept identical for LDR and HDR/PDR schedules. A range of possible PDR treatment schedules is presented, both for booster applications (in combination with external radiotherapy (ERT) and for BT applications as a single treatment. Because the knowledge of both α/β values and the half time for repair of sublethal damage (T (1(2)) ), which are required for these calculations, is quite limited, calculations regarding the equivalence of LDR and PDR treatments have been performed for a wide range of values of α/β and T (1(2)) . The results are presented graphically as PDR/LDR dose ratios and as ratios of the PDR/LDR tumor control probabilities. Results: If the condition that total physical dose and overall time of a PDR treatment must be exactly identical to the values for the corresponding LDR treatment regimen is not applied, there appears

  19. Performance of high-rate gravel-packed oil wells

    Energy Technology Data Exchange (ETDEWEB)

    Unneland, Trond

    2001-05-01

    Improved methods for the prediction, evaluation, and monitoring of performance in high-rate cased-hole gravel-packed oil wells are presented in this thesis. The ability to predict well performance prior to the gravel-pack operations, evaluate the results after the operation, and monitor well performance over time has been improved. This lifetime approach to performance analysis of gravel-packed oil wells contributes to increase oil production and field profitability. First, analytical models available for prediction of performance in gravel-packed oil wells are reviewed, with particular emphasis on high-velocity flow effects. From the analysis of field data from three North Sea oil fields, improved and calibrated cased-hole gravel-pack performance prediction models are presented. The recommended model is based on serial flow through formation sand and gravel in the perforation tunnels. In addition, new correlations for high-velocity flow in high-rate gravel-packed oil wells are introduced. Combined, this improves the performance prediction for gravel-packed oil wells, and specific areas can be targeted for optimized well design. Next, limitations in the current methods and alternative methods for evaluation and comparison of well performance are presented. The most widely used parameter, the skin factor, remains a convenient and important parameter. However, using the skin concept in direct comparisons between wells with different reservoir properties may result in misleading or even invalid conclusions. A discussion of the parameters affecting the skin value, with a clarification of limitations, is included. A methodology for evaluation and comparison of gravel-packed well performance is presented, and this includes the use of results from production logs and the use of effective perforation tunnel permeability as a parameter. This contributes to optimized operational procedures from well to well and from field to field. Finally, the data sources available for

  20. HIGH-DOSE RATE BRACHYTHERAPY IN CARCINOMA CERVIX STAGE IIIB

    Directory of Open Access Journals (Sweden)

    Sathya Maruthavanan

    2016-07-01

    Full Text Available INTRODUCTION Radiotherapy is the standard treatment in locally advanced (IIB-IVA and early inoperable cases. The current standard of practice with curable intent is concurrent chemoradiation in which intracavitary brachytherapy is an integral component of radiotherapy. This study aims at assessing the efficacy of HDR ICBT (High-dose rate intracavitary brachytherapy in terms local response, normal tissue reactions, and feasibility. METHODS AND MATERIALS A total of 20 patients of stage IIIB cancer of the uterine cervix were enrolled in the study and were planned to receive concurrent chemotherapy weekly along with EBRT (external beam radiotherapy to a dose of 50 Gy/25 Fr. Suitability for ICBT was assessed at 40 Gy/20 Fr. 6/20 patients were suitable at 40 Gy and received HDR ICBT with a dose of 5.5 Gy to point A in 4 sessions (5.5 Gy/4 Fr. The remaining 14/20 patients completed 50 Gy and received HDR ICBT with a dose of 6 Gy to point A in 3 sessions (6 Gy/3 Fr. RESULTS A total of 66 intracavitary applications were done and only one application required dose modification due to high bladder dose, the pelvic control rate was 85% (17/20. 10% (2/20 had stable disease and 5% (1/20 had progressive disease at one year of follow up. When toxicity was considered only 15% developed grade I and grade II rectal complications. Patient compliance and acceptability was 100%. Patients were very comfortable with the short treatment time as compared with patients on LDR ICBT (low-dose rate intracavitary brachytherapy treatment interviewed during the same period. CONCLUSION This study proves that HDR brachytherapy is efficacious and feasible in carcinoma of cervix stage IIIB. It also proves that good dose distribution can be achieved with HDR intracavitary facility by the use of dose optimization. The short treatment time in HDR ICBT makes it possible to maintain this optimised dose distribution throughout the treatment providing a gain in the therapeutic ratio and

  1. Rocket propellants with reduced smoke and high burning rates

    Energy Technology Data Exchange (ETDEWEB)

    Menke, K.; Eisele, S. [Fraunhofer-Institut fuer Chemische Technologie (ICT), Pfinztal-Berghausen (Germany)

    1997-07-01

    Rocket propellants with reduced smoke and high burning rates recommend themselves for use in a rocket motor for high accelerating tactical missiles. They serve for an improved camouflage on the battle field and may enable guidance control due to the higher transmission of their rocket plume compared to traditional aluminized composite propellants. In this contribution the material based ranges of performance and properties of three non aluminized rocket propellants will be introduced and compared to each other. The selected formulations based on AP/HTPB; AP/PU/TMETN and AP/HMX/GAP/TMETN have roughly the same specific impulse of I{sub SP}=2430 Ns/kg at 70:1 expansion ratio. The burning rates in the pressure range from 10-18 MPa vary from to 26-33 mm/s for the AP/HTPB propellant, 52-68 mm/s for the formulation based on AP/PU/TMETN and 28-39 mm/s for the propellant based on AP/HMX/GAP. With 58% and 20% AP-contents the propellants with nitrate ester plasticizers create a much smaller secondary signature than the AP/HTPB representative containing 85% AP. Their disadvantage, however, is the connection of high performance to a high level of energetic plasticizer. For this reason, the very fast burning propellant based on AP/PU/TMETN is endowed with a low elastic modulus and is limited to a grain configuration which isn`t exposed too much to the fast and turbulent airstream. The mechanical properties of the AP/HMX/GAP-propellant are as good or better as those of the AP/HTPB propellant. The first one exhibits the same performance and burn rates as the composite representative but produces only one fifth of HCl exhaust. For this reason it is recommended for missile applications, which must have high accelerating power together with a significantly reduced plume signature and smoke production. (orig.) [Deutsch] Rauchreduzierte Festtreibstoffe mit hohen Abbrandgeschwindigkeiten bieten sich fuer den Antrieb hochbeschleunigender taktischer Flugkoerper an, da sie gegenueber

  2. Attitudes of non-practicing chiropractors: a pilot survey concerning factors related to attrition

    Directory of Open Access Journals (Sweden)

    Wyatt Lawrence H

    2010-11-01

    Full Text Available Abstract Background Research into attitudes about chiropractors who are no longer engaged in active clinical practice is non-existent. Yet non-practicing chiropractors (NPCs represent a valid sub-group worthy of study. Aim The purpose of this research was to assess attrition attitudes of NPCs about the chiropractic profession and develop a scale to assess such attitudes. Methods A 48 item survey was developed using the PsychData software. This survey included 35 Likert-style items assessing various aspects of the profession namely financial, educational, psychosocial and political. An internet discussion site where NPCs may be members was accessed for recruitment purposes. Results A total of 70 valid responses were received for analysis. A majority of respondents were male with 66% being in non-practice status for 3 to 5 years and less with 43% indicating that they had graduated since the year 2000. Most respondents were employed either in other healthcare professions and non-chiropractic education. A majority of NPCs believed that business ethics in chiropractic were questionable and that overhead expense and student loans were factors in practice success. A majority of NPCs were in associate practice at one time with many believing that associates were encouraged to prolong the care of patients and that associate salaries were not fair. Most NPCs surveyed believed that chiropractic was not a good career choice and would not recommend someone to become a chiropractor. From this survey, a 12 item scale was developed called the "chiropractor attrition attitude scale" for future research. Reliability analysis of this novel scale demonstrated a coefficient alpha of 0.90. Conclusion The low response rate indicates that findings cannot be generalized to the NPC population. This study nonetheless demonstrates that NPCs attrition attitudes can be assessed. The lack of a central database of NPCs is a challenge to future research. Appropriate

  3. High repetition rate, high energy, actively Q-switched all-in-fiber laser

    Science.gov (United States)

    Lecourt, J. B.; Bertrand, A.; Guillemet, S.; Hernandez, Y.; Giannone, D.

    2010-05-01

    We report an actively Q-switched Ytterbium-doped all-in-fibre laser delivering 10ns pulses with high repetition rate (from 100kHz to 1MHz). The laser operation has been validated at three different wavelengths (1040, 1050 and 1064nm). The laser can deliver up to 20Watts average power with an high beam quality (M2 = 1).

  4. Listen-Identify-Brainstorm-Reality-Test-Encourage (LIBRE) Problem-Solving Model: Addressing Special Education Teacher Attrition through a Cognitive-Behavioral Approach to Teacher Induction

    Science.gov (United States)

    Guerra, Norma S.; Hernandez, Art; Hector, Alison M.; Crosby, Shane

    2015-01-01

    Special education teacher attrition rates continue to challenge the profession. A cognitive-behavioral problem-solving approach was used to examine three alternative certification program special education teachers' professional development through a series of 41 interviews conducted over a 2-year period. Beginning when they were novice special…

  5. High-power pre-chirp managed amplification of femtosecond pulses at high repetition rates

    International Nuclear Information System (INIS)

    Liu, Yang; Li, Wenxue; Zhao, Jian; Bai, Dongbi; Luo, Daping; Zeng, Heping

    2015-01-01

    Femtosecond pulses at 250 MHz repetition rate from a mode-locked fiber laser are amplified to high power in a pre-chirp managed amplifier. The experimental strategy offers a potential towards high-power ultrashort laser pulses at high repetition rates. By investigating the laser pulse evolution in the amplification processes, we show that self-similar evolution, finite gain bandwidth and mode instabilities determine pulse characteristics in different regimes. Further average power scaling is limited by the mode instabilities. Nevertheless, this laser system enables us to achieve sub-50 fs pulses with an average power of 93 W. (letter)

  6. Sexting Rates and Predictors From an Urban Midwest High School.

    Science.gov (United States)

    Gregg, David; Somers, Cheryl L; Pernice, Francesca Maria; Hillman, Stephen B; Kernsmith, Poco

    2018-06-01

    Risks associated with teen sexting draw increasing concern from teachers and communities as developments in communication software and devices make sharing private content faster and simpler each year. We examined rates, recipients, and predictors of teen sexting to better plan education and preventative policies and strategies. A comprehensive literature review was conducted to determine the most likely predictors of teen sexting using prior survey studies and theoretical conceptions. We surveyed 314 high school students in an urban area of a large Midwestern city. Males were found to more frequently report sexting. Impulsivity, frequency of electronic communication, peer pressure, peer sexting, and social learning significantly predicted sexting beyond age, race, and sex. Self-esteem did not moderate the effect of peer pressure to sext. Structural predictive models attained good fit to the data, and neither were moderated by sex. Sexting was highly associated with reported peer pressure, perceived norms, and impulsive decision making. Adolescents in relationships may be at particular risk of sexting. These findings will help parents, teens, and educators take appropriate measures to inform about and encourage the safe use of technology. © 2018, American School Health Association.

  7. Optimized dose distribution of a high dose rate vaginal cylinder

    International Nuclear Information System (INIS)

    Li Zuofeng; Liu, Chihray; Palta, Jatinder R.

    1998-01-01

    Purpose: To present a comparison of optimized dose distributions for a set of high-dose-rate (HDR) vaginal cylinders calculated by a commercial treatment-planning system with benchmark calculations using Monte-Carlo-calculated dosimetry data. Methods and Materials: Optimized dose distributions using both an isotropic and an anisotropic dose calculation model were obtained for a set of HDR vaginal cylinders. Mathematical optimization techniques available in the computer treatment-planning system were used to calculate dwell times and positions. These dose distributions were compared with benchmark calculations with TG43 formalism and using Monte-Carlo-calculated data. The same dwell times and positions were used for a quantitative comparison of dose calculated with three dose models. Results: The isotropic dose calculation model can result in discrepancies as high as 50%. The anisotropic dose calculation model compared better with benchmark calculations. The differences were more significant at the apex of the vaginal cylinder, which is typically used as the prescription point. Conclusion: Dose calculation models available in a computer treatment-planning system must be evaluated carefully to ensure their correct application. It should also be noted that when optimized dose distribution at a distance from the cylinder surface is calculated using an accurate dose calculation model, the vaginal mucosa dose becomes significantly higher, and therefore should be carefully monitored

  8. High detection rate of dog circovirus in diarrheal dogs.

    Science.gov (United States)

    Hsu, Han-Siang; Lin, Ting-Han; Wu, Hung-Yi; Lin, Lee-Shuan; Chung, Cheng-Shu; Chiou, Ming-Tang; Lin, Chao-Nan

    2016-06-17

    Diarrhea is one of the most common clinical symptoms reported in companion animal clinics. Dog circovirus (DogCV) is a new mammalian circovirus that is considered to be a cause of alimentary syndromes such as diarrhea, vomiting and hemorrhagic enteritis. DogCV has previously only been identified in the United States, Italy, Germany (GeneBank accession number: KF887949) and China (GeneBank accession number: KT946839). Therefore, the aims of this study were to determine the prevalence of DogCV in Taiwan and to explore the correlation between diarrhea and DogCV infection. Clinical specimens were collected between 2012 and 2014 from 207 dogs suffering from diarrhea and 160 healthy dogs. In this study, we developed a sensitive and specific SYBR Green-based real-time PCR assays to detected DogCV in naturally infected animals. Of the analyzed fecal samples from diarrheal dogs and health dogs, 58 (28.0 %) and 19 (11.9 %), respectively, were DogCV positive. The difference in DogCV prevalence was highly significant (P = 0.0002755) in diarrheal dogs. This is the first study to reveal that DogCV is currently circulating in domestic dogs in Taiwan and to demonstrate its high detection rate in dogs with diarrhea.

  9. An integrated CMOS high data rate transceiver for video applications

    International Nuclear Information System (INIS)

    Liang Yaping; Sun Lingling; Che Dazhi; Liang Cheng

    2012-01-01

    This paper presents a 5 GHz CMOS radio frequency (RF) transceiver built with 0.18 μm RF-CMOS technology by using a proprietary protocol, which combines the new IEEE 802.11n features such as multiple-in multiple-out (MIMO) technology with other wireless technologies to provide high data rate robust real-time high definition television (HDTV) distribution within a home environment. The RF frequencies cover from 4.9 to 5.9 GHz: the industrial, scientific and medical (ISM) band. Each RF channel bandwidth is 20 MHz. The transceiver utilizes a direct up transmitter and low-IF receiver architecture. A dual-quadrature direct up conversion mixer is used that achieves better than 35 dB image rejection without any on chip calibration. The measurement shows a 6 dB typical receiver noise figure and a better than 33 dB transmitter error vector magnitude (EVM) at −3 dBm output power. (semiconductor integrated circuits)

  10. Metrology challenges for high-rate nanomanufacturing of polymer structures

    Science.gov (United States)

    Mead, Joey; Barry, Carol; Busnaina, Ahmed; Isaacs, Jacqueline

    2012-10-01

    The transfer of nanoscience accomplishments into commercial products is hindered by the lack of understanding of barriers to nanoscale manufacturing. We have developed a number of nanomanufacturing processes that leverage available high-rate plastics fabrication technologies. These processes include directed assembly of a variety of nanoelements, such as nanoparticles and nanotubes, which are then transferred onto a polymer substrate for the fabrication of conformal/flexible electronic materials, among other applications. These assembly processes utilize both electric fields and/or chemical functionalization. Conducting polymers and carbon nanotubes have been successfully transferred to a polymer substrate in times less than 5 minutes, which is commercially relevant and can be utilized in a continuous (reel to reel/roll to roll) process. Other processes include continuous high volume mixing of nanoelements (CNTs, etc) into polymers, multi-layer extrusion and 3D injection molding of polymer structures. These nanomanufacturing processes can be used for wide range of applications, including EMI shielding, flexible electronics, structural materials, and novel sensors (specifically for chem/bio detection). Current techniques to characterize the quality and efficacy of the processes are quite slow. Moreover, the instrumentation and metrology needs for these manufacturing processes are varied and challenging. Novel, rapid, in-line metrology to enable the commercialization of these processes is critically needed. This talk will explore the necessary measurement needs for polymer based nanomanufacturing processes for both step and continuous (reel to reel/roll to roll) processes.

  11. High Rate Micromechanical Behavior of Grafted Polymer Nanoparticle Films

    Science.gov (United States)

    Thomas, Edwin

    We report the ultra high strain rate behavior of films comprised of polymer grafted nanoparticles (NPs) and compare the results to homopolymer films. The films are formed by flow coating a suspension of polystyrene (PS) chains of 230 kg/mol grafted to 16nm diameter SiO2\\ at a graft density of 0.6 chains/nm2 resulting a film with 1 vol % SiO2. Films of 267 kg/mol PS were also flow coated and both films were impacted at velocities 350-700 ms-1 using 3.7 micron SiO2\\ projectiles to achieve increments in kinetic energy (KE) of 1:2:4. The KE of the projectiles before and after penetration was measured to determine the penetration energy. TEM and SEM suggest the projectile initially induces plastic flow due to the adiabatic temperature rise from impact. As the projectile deforms the film, the lower magnitude, biaxial stress state in the peripherial regions causes material microvoid formation and initiation of craze growth in the radial and tangential directions. The anchoring of the grafted polymer chains to the NPs increases the penetration energy relative to the pure homopolymer by 50% and the films capacity to delocalize the impact by 200%. These results suggest that highly grafted NP films may be useful in lightweight protection systems. In collaboration with Omri Fried, Olawale Lawal, Yang Jiao, Victor Hsaio, Thevamaran Ramathasan, Mujin Zhou, Richard Vaia.

  12. The status of low dose rate and future of high dose rate Cf-252 brachytherapy

    International Nuclear Information System (INIS)

    Rivard, M.J.; Wierzbicki, J.G.; Van den Heuvel, F.; Chuba, P.J.; Fontanesi, J.

    1997-12-01

    This work describes the current status of the US low dose rate (LDR) Cf-252 brachytherapy program. The efforts undertaken towards development of a high dose rate (HDR) remotely after loaded Cf-252 source, which can accommodate 1 mg or greater Cf-252, are also described. This HDR effort is a collaboration between Oak Ridge National Laboratory (ORNL), commercial remote after loader manufactures, the Gershenson Radiation Oncology Center (ROC), and Wayne State University. To achieve this goal, several advances in isotope chemistry and source preparation at ORNL must be achieved to yield a specific material source loading of greater than or equal 1 mg Cf-252 per mm3. Development work with both radioactive and non-radioactive stand-ins for Cf-252 have indicated the feasibility of fabricating such sources. As a result, the decreased catheter diameter and computer controlled source placement will permit additional sites (e.g. brain, breast, prostate, lung, parotid, etc.) to be treated effectively with Cf-252 sources. Additional work at the Radiochemical Engineering and Development Center (REDC) remains in source fabrication, after loader modification, and safe design. The current LDR Cf-252 Treatment Suite at the ROC is shielded and licensed to hold up to 1 mg of Cf-252. This was designed to maintain cumulative personnel exposure, both external to the room and in direct isotope handling, at less than 20 microSv/hr. However, cumulative exposure may be greatly decreased if a Cf-252 HDR unit is employed which would eliminate direct isotope handling and decrease treatment times from tilde 3 hours to an expected range of 3 to 15 minutes. Such a Cf-252 HDR source will also demonstrate improved dose distributions over current LDR treatments due to the ability to step the point-like source throughout the target volume and weight the dwell time accordingly

  13. Yield strength of molybdenum, tantalum and tungsten at high strain rates and very high temperatures

    International Nuclear Information System (INIS)

    Škoro, G.P.; Bennett, J.R.J.; Edgecock, T.R.; Booth, C.N.

    2012-01-01

    Highlights: ► New experimental data on the yield strength of molybdenum, tantalum and tungsten. ► High strain rate effects at record high temperatures (up to 2700 K). ► Test of the consistency of the Zerilli–Armstrong model at very high temperatures. - Abstract: Recently reported results of the high strain rate, high temperature measurements of the yield strength of tantalum and tungsten have been analyzed along with new experimental results on the yield strength of molybdenum. Thin wires are subjected to high stress by passing a short, fast, high current pulse through a thin wire; the amplitude of the current governs the stress and the repetition rate of the pulses determines the temperature of the wire. The highest temperatures reached in the experiments were 2100 °C (for molybdenum), 2250 °C (for tantalum) and 2450 °C (for tungsten). The strain-rates in the tests were in the range from 500 to 1500 s −1 . The parameters for the constitutive equation developed by Zerilli and Armstrong have been determined from the experimental data and the results have been compared with the data obtained at lower temperatures. An exceptionally good fit is obtained for the deformation of tungsten.

  14. Differences in reach and attrition between Web-based and print-delivered tailored interventions among adults over 50 years of age: clustered randomized trial.

    Science.gov (United States)

    Peels, Denise Astrid; Bolman, Catherine; Golsteijn, Rianne Henrica Johanna; De Vries, Hein; Mudde, Aart Nicolaas; van Stralen, Maartje Marieke; Lechner, Lilian

    2012-12-17

    The Internet has the potential to provide large populations with individual health promotion advice at a relatively low cost. Despite the high rates of Internet access, actual reach by Web-based interventions is often disappointingly low, and differences in use between demographic subgroups are present. Furthermore, Web-based interventions often have to deal with high rates of attrition. This study aims to assess user characteristics related to participation and attrition when comparing Web-based and print-delivered tailored interventions containing similar content and thereby to provide recommendations in choosing the appropriate delivery mode for a particular target audience. We studied the distribution of a Web-based and a print-delivered version of the Active Plus intervention in a clustered randomized controlled trial (RCT). Participants were recruited via direct mailing within the participating Municipal Health Council regions and randomized to the printed or Web-based intervention by their region. Based on the answers given in a prior assessment, participants received tailored advice on 3 occasions: (1) within 2 weeks after the baseline, (2) 2 months after the baseline, and (3) within 4 months after the baseline (based on a second assessment at 3 months). The baseline (printed or Web-based) results were analyzed using ANOVA and chi-square tests to establish the differences in user characteristics between both intervention groups. We used logistic regression analyses to study the interaction between the user characteristics and the delivery mode in the prediction of dropout rate within the intervention period. The printed intervention resulted in a higher participation rate (19%) than the Web-based intervention (12%). Participants of the Web-based intervention were significantly younger (PWeb-based intervention group (53%) compared to the print-delivered intervention (39%, PWeb-based and the printed intervention was not explained by user characteristics. The

  15. Growth rate of sheep fed high fat ration

    Directory of Open Access Journals (Sweden)

    Darwinsyah Lubis

    1998-10-01

    Full Text Available Incorporating high amount of fats into the ration for ruminants will affect the rumen microbes adversely and will reducefiber digestion potential. To correct such negative effects, the free fatty acids used for feed should be bond with Ca++, so it canpassing through the rumen savely (rumen by-pass fat. To test the Ca-fat utilization biologically, 20 growing male Garut shee pwere used and fed with 4 type of isocaloric-isoprotein concentrate feed which were allotted based on a randomized block desig nwith 5 replications. The concentrate (C-A was a positive control diet, while C-B was substituted with 10% free fatty acids (negative control, C-C was substituted with 10% Ca-fat, and C-D with 15% Ca-fat. The concentrate feed was fed at 500 g/d, while forage (King grass was 4 kg/d. Results of the experiment showed that the negative effect of free fatty acids can be corrected if it was given in the form of Ca-fat. Growth rate curve indicating a good growing pattern, with average daily gain was 100.18, 87.68, 112.86, and 115.00 g/d (P0.05. Carcass production was relatively good, where for C-A, C-B, C-C, and C-D were 14.84, 14.68, 16.34, and 15.72 kg (P<0.05 respectively, with final live weights of 34.00, 31.74, 34.58, and 34.30 kg (P<0.05. It can be concluded that Ca-fat (rumen by-pass fat can be used as an energy source component for growing sheep diet, and give the best result at 10% substitution rate in concentrate feed.

  16. Urethral stricture following high dose rate brachytherapy for prostate cancer

    International Nuclear Information System (INIS)

    Sullivan, Lisa; Williams, Scott G.; Tai, Keen Hun; Foroudi, Farshad; Cleeve, L.; Duchesne, Gillian M.

    2009-01-01

    Purpose: To evaluate the incidence, timing, nature and outcome of urethral strictures following high dose rate brachytherapy (HDRB) for prostate carcinoma. Methods and materials: Data from 474 patients with clinically localised prostate cancer treated with HDRB were analysed. Ninety percent received HDRB as a boost to external beam radiotherapy (HDRBB) and the remainder as monotherapy (HDRBM). Urethral strictures were graded according to the Common Terminology Criteria for Adverse Events v3.0. Results: At a median follow-up of 41 months, 38 patients (8%) were diagnosed with a urethral stricture (6-year actuarial risk 12%). Stricture location was bulbo-membranous (BM) urethra in 92.1%. The overall actuarial rate of grade 2 or more BM urethral stricture was estimated at 10.8% (95% CI 7.0-14.9%), with a median time to diagnosis of 22 months (range 10-68 months). All strictures were initially managed with either dilatation (n = 15) or optical urethrotomy (n = 20). Second line therapy was required in 17 cases (49%), third line in three cases (9%) and 1 patient open urethroplasty (grade 3 toxicity). Predictive factors on multivariate analysis were prior trans-urethral resection of prostate (hazard ratio (HR) 2.81, 95% CI 1.15-6.85, p = 0.023); hypertension (HR 2.83, 95% CI 1.37-5.85, p = 0.005); and dose per fraction used in HDR (HR for 1 Gy increase per fraction 1.33, 95% CI 1.08-1.64, p = 0.008). Conclusions: BM urethral strictures are the most common late grade 2 or more urinary toxicity following HDR brachytherapy for prostate cancer. Most are manageable with minimally invasive procedures. Both clinical and dosimetric factors appear to influence the risk of stricture formation.

  17. Relationship between Academic Performance, Spatial Competence, Learning Styles and Attrition

    Directory of Open Access Journals (Sweden)

    Marianela Noriega Biggio

    2013-04-01

    Full Text Available This paper discusses the results of research on factors affecting academic performance and attrition in a sample of 1,500 freshman students majoring in architecture, design and urbanism at the Universidad de Buenos Aires, Argentina [University of Buenos Aires, Argentina] who were enrolled in a drafting course. The hypotheses we tested concern the mediating role of learning styles on the relationship between spatial competence and academic performance, learning-style differences by gender and cohort, and the relationship between attrition, spatial competence level and learning style. Statistical analysis of the data was performed and spatial competence enhanced by motivational profile was found to predict final achievement. Educational implications are identified, highlighting the need to promote in students those academic behaviors that characterize a self-regulated learning style and encourage the use of specific intellectual abilities.

  18. Ash production by attrition in volcanic conduits and plumes.

    Science.gov (United States)

    Jones, T J; Russell, J K

    2017-07-17

    Tephra deposits result from explosive volcanic eruption and serve as indirect probes into fragmentation processes operating in subsurface volcanic conduits. Primary magmatic fragmentation creates a population of pyroclasts through volatile-driven decompression during conduit ascent. In this study, we explore the role that secondary fragmentation, specifically attrition, has in transforming primary pyroclasts upon transport in volcanic conduits and plumes. We utilize total grain size distributions from a suite of natural and experimentally produced tephra to show that attrition is likely to occur in all explosive volcanic eruptions. Our experimental results indicate that fine ash production and surface area generation is fast (eruption column stability, tephra dispersal, aggregation, volcanic lightening generation, and has concomitant effects on aviation safety and Earth's climate.

  19. High dose rate brachytherapy for superficial cancer of the esophagus

    International Nuclear Information System (INIS)

    Maingon, Philippe; D'Hombres, Anne; Truc, Gilles; Barillot, Isabelle; Michiels, Christophe; Bedenne, Laurent; Horiot, Jean Claude

    2000-01-01

    Purpose: We analyzed our experience with external radiotherapy, combined modality treatment, or HDR brachytherapy alone to limited esophageal cancers. Methods and Materials: From 1991 to 1996, 25 patients with limited superficial esophagus carcinomas were treated by high dose rate brachytherapy. The mean age was 63 years (43-86 years). Five patients showed superficial local recurrence after external radiotherapy. Eleven patients without invasion of the basal membrane were staged as Tis. Fourteen patients with tumors involving the submucosa without spreading to the muscle were staged as T1. Treatment consisted of HDR brachytherapy alone in 13 patients, external radiotherapy and brachytherapy in 8 cases, and concomitant chemo- and radiotherapy in 4 cases. External beam radiation was administered to a total dose of 50 Gy using 2 Gy daily fractions in 5 weeks. In cases of HDR brachytherapy alone (13 patients), 6 applications were performed once a week. Results: The mean follow-up is 31 months (range 24-96 months). Twelve patients received 2 applications and 13 patients received 6 applications. Twelve patients experienced a failure (48%), 11/12 located in the esophagus, all of them in the treated volume. One patient presented an isolated distant metastasis. In the patients treated for superficial recurrence, 4/5 were locally controlled (80%) by brachytherapy alone. After brachytherapy alone, 8/13 patients were controlled (61%). The mean disease-free survival is 14 months (1-36 months). Overall survival is 76% at 1 year, 37% at 2 years, and 14% at 3 years. Overall survival for Tis patients is 24% vs. 20% for T1 (p 0.83). Overall survival for patients treated by HDR brachytherapy alone is 43%. One patient presented with a fistula with local failure after external radiotherapy and brachytherapy. Four stenosis were registered, two were diagnosed on barium swallowing without symptoms, and two required dilatations. Conclusion: High dose rate brachytherapy permits the treating

  20. COMPENSATORY STRATEGIES OF FIRST-LANGUAGE-ATTRITED CHILDREN

    Directory of Open Access Journals (Sweden)

    Syahdan Syahdan

    2012-01-01

    Full Text Available This article explores the compensatory strategies used by two Indonesian children who experienced first language attrition when acquiring English in the English-speaking environment. They use compensatory strategies to compensate for their lack of competence in first language. They employ both interlingual strategies and discourse strategies when they have difficulties in communication. Interlingual strategies used are codeswitching and lexical borrowings and the discourse strategies are overt comments, appeal for assistance, and avoidance.

  1. The Impact of Fund Attrition on Superannuation Returns

    OpenAIRE

    Drew, Michael E.; Stanford, Jon D.

    2001-01-01

    This paper investigates the impact of fund attrition on returns from a sample of superannuation fund managers (specialising in the management of domestic stock portfolios) for the period 1991 through 1999, using a four-factor asset pricing model. Survivorship bias is estimated at 23 basis points per annum. The evidence presented in this study is consistent with recent international evidence that suggests that a sampling technique that excludes terminated funds would result in an overestimatio...

  2. Germanic heritage languages in North America: Acquisition, attrition and change

    OpenAIRE

    Johannessen, Janne Bondi; Salmons, Joseph C.; Westergaard, Marit; Anderssen, Merete; Arnbjörnsdóttir, Birna; Allen, Brent; Pierce, Marc; Boas, Hans C.; Roesch, Karen; Brown, Joshua R.; Putnam, Michael; Åfarli, Tor A.; Newman, Zelda Kahan; Annear, Lucas; Speth, Kristin

    2015-01-01

    This book presents new empirical findings about Germanic heritage varieties spoken in North America: Dutch, German, Pennsylvania Dutch, Icelandic, Norwegian, Swedish, West Frisian and Yiddish, and varieties of English spoken both by heritage speakers and in communities after language shift. The volume focuses on three critical issues underlying the notion of ‘heritage language’: acquisition, attrition and change. The book offers theoretically-informed discussions of heritage language processe...

  3. Predictors of Attrition in the Finnish Conscript Service

    Science.gov (United States)

    2006-11-01

    Dawson et al., 1994; Kassel, Jackson, & Unrod, 2000; Lazarus & Folkman , 1984; Pierce & Lydon, 1998; Thompson & Gignac, 2001). These expectations toward...organizational socialization. USAWC Strategy Research Project Carlisle Barracks, PA: U.S. Army War College. Hicks, J. M., & Nogami, G. Y . (1984...of Navy attrition. II. A demonstration of potential usefulness for screening. (Report No. 01-06). Military Medicine, 167, 770-776. Lazarus , R. S

  4. Taking into account the impact of attrition on the assessment of response shift and true change: a multigroup structural equation modeling approach.

    Science.gov (United States)

    Verdam, Mathilde G E; Oort, Frans J; van der Linden, Yvette M; Sprangers, Mirjam A G

    2015-03-01

    Missing data due to attrition present a challenge for the assessment and interpretation of change and response shift in HRQL outcomes. The objective was to handle such missingness and to assess response shift and 'true change' with the use of an attrition-based multigroup structural equation modeling (SEM) approach. Functional limitations and health impairments were measured in 1,157 cancer patients, who were treated with palliative radiotherapy for painful bone metastases, before [time (T) 0], every week after treatment (T1 through T12), and then monthly for up to 2 years (T13 through T24). To handle missing data due to attrition, the SEM procedure was extended to a multigroup approach, in which we distinguished three groups: short survival (3-5 measurements), medium survival (6-12 measurements), and long survival (>12 measurements). Attrition after third, sixth, and 13th measurement occasions was 11, 24, and 41 %, respectively. Results show that patterns of change in functional limitations and health impairments differ between patients with short, medium, or long survival. Moreover, three response-shift effects were detected: recalibration of 'pain' and 'sickness' and reprioritization of 'physical functioning.' If response-shift effects would not have been taken into account, functional limitations and health impairments would generally be underestimated across measurements. The multigroup SEM approach enables the analysis of data from patients with different patterns of missing data due to attrition. This approach does not only allow for detection of response shift and assessment of true change across measurements, but also allow for detection of differences in response shift and true change across groups of patients with different attrition rates.

  5. High-dose-rate brachytherapy in uterine cervical carcinoma

    International Nuclear Information System (INIS)

    Patel, Firuza D.; Rai, Bhavana; Mallick, Indranil; Sharma, Suresh C.

    2005-01-01

    Purpose: High-dose-rate (HDR) brachytherapy is in wide use for curative treatment of cervical cancer. The American Brachytherapy Society has recommended that the individual fraction size be <7.5 Gy and the range of fractions should be four to eight; however, many fractionation schedules, varying from institution to institution, are in use. We use 9 Gy/fraction of HDR in two to five fractions in patients with carcinoma of the uterine cervix. We found that our results and toxicity were comparable to those reported in the literature and hereby present our experience with this fractionation schedule. Methods and Materials: A total of 121 patients with Stage I-III carcinoma of the uterine cervix were treated with HDR brachytherapy between 1996 and 2000. The total number of patients analyzed was 113. The median patient age was 53 years, and the histopathologic type was squamous cell carcinoma in 93% of patients. The patients were subdivided into Groups 1 and 2. In Group 1, 18 patients with Stage Ib-IIb disease, tumor size <4 cm, and preserved cervical anatomy underwent simultaneous external beam radiotherapy to the pelvis to a dose of 40 Gy in 20 fractions within 4 weeks with central shielding and HDR brachytherapy of 9 Gy/fraction, given weekly, and interdigitated with external beam radiotherapy. The 95 patients in Group 2, who had Stage IIb-IIIb disease underwent external beam radiotherapy to the pelvis to a dose of 46 Gy in 23 fractions within 4.5 weeks followed by two sessions of HDR intracavitary brachytherapy of 9 Gy each given 1 week apart. The follow-up range was 3-7 years (median, 36.4 months). Late toxicity was graded according to the Radiation Therapy Oncology Group criteria. Results: The 5-year actuarial local control and disease-free survival rate was 74.5% and 62.0%, respectively. The actuarial local control rate at 5 years was 100% for Stage I, 80% for Stage II, and 67.2% for Stage III patients. The 5-year actuarial disease-free survival rate was 88.8% for

  6. Managing Clutter in a High Pulse Rate Echolocation System

    Directory of Open Access Journals (Sweden)

    Jacob Isbell

    2018-03-01

    Full Text Available The use of echolocation for navigating in dense, cluttered environments is a challenge due to the need for rapid sampling of nearby objects in the face of delayed echoes from distant objects. In the wild, echolocating bats frequently encounter this situation when leaving the roost or while hunting. If long-delay echoes from a distant object are received after the next pulse is sent out, these “aliased” echoes appear as close-range phantom objects. Little is known about how bats cope with these situations. In this work, we demonstrate a novel strategy to manage aliasing in cases where a single target is actively being tracked at close range. This paper presents three reactive strategies for a high pulse-rate sonar system to combat aliased echoes: (1 changing the interpulse interval to move the aliased echoes away in time from the tracked target, (2 changing positions to create a geometry without aliasing, and (3 a phase-based, transmission beam-shaping strategy to illuminate the target and not the aliasing object.

  7. Pregnancy after kidney transplantation: high rates of maternal complications

    Directory of Open Access Journals (Sweden)

    Cristina Candido

    Full Text Available Abstract Introduction: Women regain fertility a few time after renal transplantation. However, viability of pregnancy and maternal complications are still unclear. Objective: To describe the outcomes of pregnancies in kidney transplanted patients, focusing on maternal complications. Methods: Retrospective study of pregnancies in kidney transplanted patients between 2004 and 2014, followed up 12 months after delivery. Each pregnancy was considered an event. Results: There were 53 pregnancies in 36 patients. Mean age was 28 ± 5years. Pregnancy occurred 4.4 ± 3.0 years post-transplant. Immunosuppression before conception was tacrolimus, azathioprine, and prednisone in 74% of the cases. There were 15% miscarriages in the 1st trimester and 8% in 2nd trimester. In 41% of the cases, it was necessary to induce labor. From all births, 22% were premature and 17% very premature. There were 5% stillbirths and 5% of neonatal deaths. De novo proteinuria occurred in 60%, urinary tract infection in 23%, preeclampsia in 11%, acute rejection in 6%, and graft loss in 2% of the cases. It was observed a significant increase in creatinine at preconception comparing to 3rd trimester and follow-up (1.17 vs. 1.46 vs. 1.59 mg/dL, p < 0.001. Conclusion: Although the sample is limited, the number of miscarriages was higher than in the general population, with high rates of maternal complications. Sustained increase of creatinine suggests increased risk of graft loss in long-term.

  8. MATHEMATICAL MODELING OF HEATING RATE PRODUCT AT HIGH HEAT TREATMENT

    Directory of Open Access Journals (Sweden)

    M. M. Akhmedova

    2014-01-01

    Full Text Available Methods of computing and mathematical modeling are all widely used in the study of various heat exchange processes that provide the ability to study the dynamics of the processes, as well as to conduct a reasonable search for the optimal technological parameters of heat treatment.This work is devoted to the identification of correlations among the factors that have the greatest effect on the rate of heating of the product at hightemperature heat sterilization in a stream of hot air, which are chosen as the temperature difference (between the most and least warming up points and speed cans during heat sterilization.As a result of the experimental data warming of the central and peripheral layers compote of apples in a 3 liter pot at high-temperature heat treatment in a stream of hot air obtained by the regression equation in the form of a seconddegree polynomial, taking into account the effects of pair interaction of these parameters. 

  9. A high rate clarifier for load levelling in sewerage systems.

    Science.gov (United States)

    Jago, R A; Davey, A; Li, H

    2003-01-01

    The combining of chemically assisted clarification with a proprietary physical separation technology has led to a high rate process for clarifying flocculated sewage and other waste streams. This hybrid physico-chemical system, known as the CDS Fine Solids Separation (FSS) System, was developed over a two year period within a sewage treatment plant environment. This paper summarises the results of a recent field trial of the system with a Victorian water authority which experiences heavy loading of sewers in a coastal town during holiday periods. The trial sought to evaluate the FSS as a tool for smoothing the load on the 11 km long sewer to the sewage treatment plant (STP). The FSS system could possibly enable the costly augmentation of the sewer to be deferred, particularly as the capacity of the existing sewer pipe is satisfactory for most of the year. Water quality parameters were determined for a range of flowrates and operational conditions over a two month period. Large reductions were achieved in TSS, TP, FC, turbidity and BOD5, with only minimal reductions in NH3 and TON. These results showed that the FSS could meet the authority's objectives for load levelling and would provide a 20-25% increase in effective sewer capacity. The data are also discussed in terms of possible use of the effluent from the FSS for water reuse applications.

  10. High rate composting of herbal pharmaceutical industry solid waste.

    Science.gov (United States)

    Ali, M; Duba, K S; Kalamdhad, A S; Bhatia, A; Khursheed, A; Kazmi, A A; Ahmed, N

    2012-01-01

    High rate composting studies of hard to degrade herbal wastes were conducted in a 3.5 m(3) capacity rotary drum composter. Studies were spread out in four trials: In trial 1 and 2, one and two turns per day rotation was observed, respectively, by mixing of herbal industry waste with cattle (buffalo) manure at a ratio of 3:1 on wet weight basis. In trial 3 inocula was added in raw waste to enhance the degradation and in trial 4 composting of a mixture of vegetable market waste and herbal waste was conducted at one turn per day. Results demonstrated that the operation of the rotary drum at one turn a day (trial 1) could provide the most conducive composting conditions and co-composting (trial 4) gave better quality compost in terms of temperature, moisture, nitrogen, and Solvita maturity index. In addition a FT-IR study also revealed that trial 1 and trial 4 gave quality compost in terms of stability and maturity due to the presence of more intense peaks in the aromatic region and less intense peaks were found in the aliphatic region compared with trial 2 and trial 3.

  11. High rate of destruction of molecular clouds by hot stars

    International Nuclear Information System (INIS)

    Heydari-Malayeri, M.; Lortet, M.C.; Deharveng, L.

    1980-01-01

    Tenorio-Tagle (1979) first proposed the idea of a third dynamical phase, the champagne phase, following the formation and expansion phases of an HII region. The champagne phase begins when the high pressure gas of an HII region formed inside a molecular cloud reaches the edge of the cloud and bursts into the lower pressure, low density, intercloud medium. One important implication of the model is the prediction of an enormous enhancement of the rate of erosion of the molecular cloud by the ionising radiation of hot stars, which begins as soon as the process of the decrease of the gas density between the star and the cloud is started. The proportion of hydrogen molecules eroded by ionising photons may reach about 10 -2 . The mass eroded may exceed the mass of the ionised gas in the case where the ionisation front reaching the edge of the cloud is of D-type. Additional mechanisms (for instance stellar winds), if at work, may even increase the efficiency of the mechanism. (Auth.)

  12. CMOS pixel sensors on high resistive substrate for high-rate, high-radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Hirono, Toko, E-mail: thirono@uni-bonn.de [Physikalisches Institute der Universität Bonn, Bonn (Germany); Barbero, Marlon; Breugnon, Patrick; Godiot, Stephanie [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Gonella, Laura; Hemperek, Tomasz; Hügging, Fabian; Krüger, Hans [Physikalisches Institute der Universität Bonn, Bonn (Germany); Liu, Jian; Pangaud, Patrick [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Peric, Ivan [IPE, Karlsruher Institut für Technologie, Karlsruhe (Germany); Pohl, David-Leon [Physikalisches Institute der Universität Bonn, Bonn (Germany); Rozanov, Alexandre [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Rymaszewski, Piotr [Physikalisches Institute der Universität Bonn, Bonn (Germany); Wang, Anqing [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Wermes, Norbert [Physikalisches Institute der Universität Bonn, Bonn (Germany)

    2016-09-21

    A depleted CMOS active pixel sensor (DMAPS) has been developed on a substrate with high resistivity in a high voltage process. High radiation tolerance and high time resolution can be expected because of the charge collection by drift. A prototype of DMAPS was fabricated in a 150 nm process by LFoundry. Two variants of the pixel layout were tested, and the measured depletion depths of the variants are 166 μm and 80 μm. We report the results obtained with the prototype fabricated in this technology.

  13. Solid State Track Recorder fission rate measurements at high neutron fluence and high temperature

    International Nuclear Information System (INIS)

    Ruddy, F.H.; Roberts, J.H.; Gold, R.

    1985-01-01

    Solid State Track Recorder (SSTR) techniques have been used to measure 239-Pu, 235-U, and 237-Np fission rates for total neutron fluences approaching 5 x 10 17 n/cm 2 at temperatures in the range 680 to 830 0 F. Natural quartz crystal SSTRs were used to withstand the high temperature environment and ultra low-mass fissionable deposits of the three isotopes were required to yield scannable track densities at the high neutron fluences. The results of these high temperature, high neutron fluence measurements are reported

  14. High mutation rates limit evolutionary adaptation in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Kathleen Sprouffske

    2018-04-01

    Full Text Available Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli's genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild.

  15. States with low non-fatal injury rates have high fatality rates and vice-versa.

    Science.gov (United States)

    Mendeloff, John; Burns, Rachel

    2013-05-01

    State-level injury rates or fatality rates are sometimes used in studies of the impact of various safety programs or other state policies. How much does the metric used affect the view of relative occupational risks among U.S. states? This paper uses a measure of severe injuries (fatalities) and of less severe injuries (non-fatal injuries with days away from work, restricted work, or job transfer-DART) to examine that issue. We looked at the correlation between the average DART injury rate (from the BLS Survey of Occupational Injuries and Illnesses) and an adjusted average fatality rate (from the BLS Census of Fatal Occupational Injuries) in the construction sector for states for 2003-2005 and for 2006-2008. The RAND Human Subjects Protection Committee determined that this study was exempt from review. The correlations between the fatal and non-fatal injury rates were between -0.30 and -0.70 for all construction and for the subsector of special trade contractors. The negative correlation was much smaller between the rate of fatal falls from heights and the rate of non-fatal falls from heights. Adjusting for differences in the industry composition of the construction sector across states had minor effects on these results. Although some have suggested that fatal and non-fatal injury rates should not necessarily be positively correlated, no one has suggested that the correlation is negative, which is what we find. We know that reported non-fatal rates are influenced by workers' compensation benefits and other factors. Fatality rates appear to be a more valid measure of risk. Efforts to explain the variations that we find should be undertaken. Copyright © 2012 Wiley Periodicals, Inc.

  16. Performance of Drift-Tube Detectors at High Counting Rates for High-Luminosity LHC Upgrades

    CERN Document Server

    Bittner, Bernhard; Kortner, Oliver; Kroha, Hubert; Manfredini, Alessandro; Nowak, Sebastian; Ott, Sebastian; Richter, Robert; Schwegler, Philipp; Zanzi, Daniele; Biebel, Otmar; Hertenberger, Ralf; Ruschke, Alexander; Zibell, Andre

    2016-01-01

    The performance of pressurized drift-tube detectors at very high background rates has been studied at the Gamma Irradiation Facility (GIF) at CERN and in an intense 20 MeV proton beam at the Munich Van-der-Graaf tandem accelerator for applications in large-area precision muon tracking at high-luminosity upgrades of the Large Hadron Collider (LHC). The ATLAS muon drifttube (MDT) chambers with 30 mm tube diameter have been designed to cope with and neutron background hit rates of up to 500 Hz/square cm. Background rates of up to 14 kHz/square cm are expected at LHC upgrades. The test results with standard MDT readout electronics show that the reduction of the drift-tube diameter to 15 mm, while leaving the operating parameters unchanged, vastly increases the rate capability well beyond the requirements. The development of new small-diameter muon drift-tube (sMDT) chambers for LHC upgrades is completed. Further improvements of tracking e?ciency and spatial resolution at high counting rates will be achieved with ...

  17. Solid state pump lasers with high power and high repetition rate

    International Nuclear Information System (INIS)

    Oba, Masaki; Kato, Masaaki; Arisawa, Takashi

    1995-01-01

    We built a laser diode pumped solid state green laser (LDPSSGL) rated at high repetition rate. Two laser heads are placed in one cavity with a rotator in between to design to avoid thermal lensing and thermal birefringence effect. Although average green laser power higher than 10 W was obtained at 1 kHz repetition rate with pulse width of 20-30 nsec, the beam quality was so much deteriorated that energy efficiency was as low as 2 %. Learning from this experience that high power oscillator causes a lot of thermal distortion not only in the laser rod but also in the Q-switch device, we proceeded to built a oscillator/amplifier system. A low power oscillator has a slab type crystal in the cavity. As a result spatial distribution of laser power was extremely improved. As we expect that the high repetition rate solid state laser should be CW operated Q-switch type laser from the view point of lifetime of diode lasers, a conventional arc lamp pumped CW Q-switch green YAG laser of which the repetition rate is changeable from 1 kHz to 5 kHz and the pulse width is 250-570 nsec was also tested to obtain pumping characteristics of a dye laser as a function of power, pulse width etc., and dye laser pulse width of 100-130 nsec were obtained. (author)

  18. High resolution gamma-ray spectroscopy at high count rates with a prototype High Purity Germanium detector

    Science.gov (United States)

    Cooper, R. J.; Amman, M.; Vetter, K.

    2018-04-01

    High-resolution gamma-ray spectrometers are required for applications in nuclear safeguards, emergency response, and fundamental nuclear physics. To overcome one of the shortcomings of conventional High Purity Germanium (HPGe) detectors, we have developed a prototype device capable of achieving high event throughput and high energy resolution at very high count rates. This device, the design of which we have previously reported on, features a planar HPGe crystal with a reduced-capacitance strip electrode geometry. This design is intended to provide good energy resolution at the short shaping or digital filter times that are required for high rate operation and which are enabled by the fast charge collection afforded by the planar geometry crystal. In this work, we report on the initial performance of the system at count rates up to and including two million counts per second.

  19. Transistor reset preamplifier for high-rate high-resolution spectroscopy

    International Nuclear Information System (INIS)

    Landis, D.A.; Cork, C.P.; Madden, N.W.; Goulding, F.S.

    1981-10-01

    Pulsed transistor reset of high resolution charge sensitive preamplifiers used in cooled semiconductor spectrometers can sometimes have an advantage over pulsed light reset systems. Several versions of transistor reset spectrometers using both silicon and germanium detectors have been built. This paper discusses the advantages of the transistor reset system and illustrates several configurations of the packages used for the FET and reset transistor. It also describes the preamplifer circuit and shows the performance of the spectrometer at high rates

  20. Physics and quality assurance for high dose rate brachytherapy

    International Nuclear Information System (INIS)

    Anderson, Lowell L.

    1995-01-01

    Purpose: To review the physical aspects of high dose rate (HDR) brachytherapy, including commissioning and quality assurance, source calibration and dose distribution measurements, and treatment planning methods. Following the introduction of afterloading in brachytherapy, development efforts to make it 'remote' culminated in 1964 with the near-simultaneous appearance of remote afterloaders in five major medical centers. Four of these machines were 'high dose rate', three employing 60Co and one (the GammaMed) using a single, cable-mounted 192Ir source. Stepping-motor source control was added to the GammaMed in 1974, making it the precursor of modern remote afterloaders, which are now suitable for interstitial as well as intracavitary brachytherapy by virtue of small source-diameter and indexer-accessed multiple channels. Because the 192Ir sources currently used in HDR remote afterloaders are supplied at a nominal air-kerma strength of 11.4 cGy cm2 s-1 (10 Ci), are not collimated in clinical use, and emit a significant fraction (15%) of photons at energies greater than 600 keV, shielding and facility design must be undertaken as carefully and thoroughly as for external beam installations. Licensing requirements of regulatory agencies must be met with respect both to maximum permissible dose limits and to the existence and functionality of safety devices (door interlocks, radiation monitors, etc.). Commissioning and quality assurance procedures that must be documented for HDR remote afterloading relate to (1) machine, applicator, guide-tube, and facility functionality checks, (2) source calibration, (3) emergency response readiness, (4) planning software evaluation, and (5) independent checks of clinical dose calculations. Source calibration checks must be performed locally, either by in-air measurement of air kerma strength or with a well ionization chamber calibrated (by an accredited standards laboratory) against an in-air measurement of air kerma strength for the

  1. Developing a national computerised absence monitoring and management system to reduce nursing student attrition: evaluation of staff and student perspectives.

    Science.gov (United States)

    Currie, Kay; McCallum, Jacqueline; Murray, John; Scott, Janine; Strachan, Evelyn; Yates, Lynda; Wright, Marty

    2014-05-01

    avoid student frustration. Further research on the longer term impact of CAMMS on attrition rates is warranted. © 2013.

  2. High versus low-dose rate brachytherapy for cervical cancer.

    Science.gov (United States)

    Patankar, Sonali S; Tergas, Ana I; Deutsch, Israel; Burke, William M; Hou, June Y; Ananth, Cande V; Huang, Yongmei; Neugut, Alfred I; Hershman, Dawn L; Wright, Jason D

    2015-03-01

    Brachytherapy plays an important role in the treatment of cervical cancer. While small trials have shown comparable survival outcomes between high (HDR) and low-dose rate (LDR) brachytherapy, little data is available in the US. We examined the utilization of HDR brachytherapy and analyzed the impact of type of brachytherapy on survival for cervical cancer. Women with stages IB2-IVA cervical cancer treated with primary (external beam and brachytherapy) radiotherapy between 2003-2011 and recorded in the National Cancer Database (NCDB) were analyzed. Generalized linear mixed models and Cox proportional hazards regression were used to examine predictors of HDR brachytherapy use and the association between HDR use and survival. A total of 10,564 women including 2681 (25.4%) who received LDR and 7883 (74.6%) that received HDR were identified. Use of HDR increased from 50.2% in 2003 to 83.9% in 2011 (Puse of HDR. While patients in the Northeast were more likely to receive HDR therapy, there were no other clinical or socioeconomic characteristics associated with receipt of HDR. In a multivariable Cox model, survival was similar between the HDR and LDR groups (HR=0.93; 95% CI 0.83-1.03). Similar findings were noted in analyses stratified by stage and histology. Kaplan-Meier analyses demonstrated no difference in survival based on type of brachytherapy for stage IIB (P=0.68), IIIB (P=0.17), or IVA (P=0.16) tumors. The use of HDR therapy has increased rapidly. Overall survival is similar for LDR and HDR brachytherapy. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Do high fetal catecholamine levels affect heart rate variability and ...

    African Journals Online (AJOL)

    Objectives. To deternrine the relationship between Umbilical arterial catecholamine levels and fetal heart rate variability and meconium passage. Study design. A prospective descriptive study was perfonned. Umbilical artery catecholamine levels were measured in 55 newborns and correlated with fetal heart rate before ...

  4. TRP 9904 - Constitutive Behavior of High Strength Multiphase Sheel Steel Under High Strain Rate Deformation

    Energy Technology Data Exchange (ETDEWEB)

    David Matlock; John Speer

    2005-03-31

    The focus of the research project was to systematically assess the strain rate dependence of strengthening mechanisms in new advanced high strength sheet steels. Data were obtained on specially designed and produced Duel Phase and TRIP steels and compared to the properties of automotive steels currently in use.

  5. Special Education Teacher Resilience: A Phenomenological Study of Factors Associated with Retention and Resilience of Highly Resilient Special Educators

    Science.gov (United States)

    Downing, Brienne

    2017-01-01

    Special education teachers are in high demand and greatly needed to meet the needs of the growing population of students qualified for special education services under the Individual with Disabilities Education Act (IDEA) of 2004. The increasing attrition rates of special education teachers are a social justice issue that needs attention. The…

  6. High mutation rates limit evolutionary adaptation in Escherichia coli

    Science.gov (United States)

    Wagner, Andreas

    2018-01-01

    Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli’s genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild. PMID:29702649

  7. Clinical correlates of weight loss and attrition during a 10-week dietary intervention study

    DEFF Research Database (Denmark)

    Handjieva-Darlenska, Teodora; Holst, Claus; Grau, Katrine

    2012-01-01

    clinical centres in 7 European countries, who underwent a 10-week dietary intervention study comparing two hypo-energetic (-600 kcal/day) diets varying in fat content. Results: The multiple regression model showed that weight loss at week 10 was predicted by: 6.55 + 1.27 × early weight loss (kg) at week 1...... kg weight loss at week 5 emerged as an optimal predictor for reaching at least 10% weight loss at week 10. Greater attrition likelihood was predicted by high-fat diet, decreased early and half-way weight losses. Conclusion: Early and half-way weight losses are associated with and could contribute......Objective: The aim of this study was to identify the pre-treatment subject characteristics and weight loss changes as determinants of weight loss and attrition during a 10-week dietary intervention study. Methods: A total of 771 obese subjects (BMI 35.6 kg/m(2)) of both genders were included from 8...

  8. High-Pressure Burning Rate Studies of Solid Rocket Propellants

    Science.gov (United States)

    2013-01-01

    monopropellant burning rate. The self-de§agration rates of neat AP are plotted in Fig. 2 for both pressed pellets and single crystals. There is agreement...rate data from various investigators: 1 ¡ [2]; pressed pellets : 2 ¡ [3], 3 ¡ [4], and 4 ¡ [2]; and single crystals: 5 ¡ [5], and 6 ¡ [6]. Line ¡ AP...7]. Strand or window burners have had more use in the solid propellant community. There are numerous types and styles of combustion vessels, but they

  9. An Analysis of Recruit Training Attrition in the U.S. Marine Corps

    Science.gov (United States)

    1978-02-01

    Administration NR 170-819 I I. CONTROLLING OFFICE NAME AND ADDRESS It. ROILPORT CATS Organizational Effectiveness Research Programs February 1978 / Office of...for over 60% of the administrativo reasons for attrition. This finding underscores the importance of behavioral approaches to understanding and... controlled attrition may serve to confound individual level analyses of attrition. Although the R2 in this study is .10, this is not trivial. This

  10. Mechanical characterization of alloys in extreme conditions of high strain rates and high temperature

    Science.gov (United States)

    Cadoni, Ezio

    2018-03-01

    The aim of this paper is the description of the mechanical characterization of alloys under extreme conditions of temperature and loading. In fact, in the frame of the Cost Action CA15102 “Solutions for Critical Raw Materials Under Extreme Conditions (CRM-EXTREME)” this aspect is crucial and many industrial applications have to consider the dynamic response of materials. Indeed, for a reduction and substitution of CRMs in alloys is necessary to design the materials and understand if the new materials behave better or if the substitution or reduction badly affect their performance. For this reason, a deep knowledge of the mechanical behaviour at high strain-rates of considered materials is required. In general, machinery manufacturing industry or transport industry as well as energy industry have important dynamic phenomena that are simultaneously affected by extended strain, high strain-rate, damage and pressure, as well as conspicuous temperature gradients. The experimental results in extreme conditions of high strain rate and high temperature of an austenitic stainless steel as well as a high-chromium tempered martensitic reduced activation steel Eurofer97 are presented.

  11. Development of a cryogenic hydrogen microjet for high-intensity, high-repetition rate experiments

    Science.gov (United States)

    Kim, J. B.; Göde, S.; Glenzer, S. H.

    2016-11-01

    The advent of high-intensity, high-repetition-rate lasers has led to the need for replenishing targets of interest for high energy density sciences. We describe the design and characterization of a cryogenic microjet source, which can deliver a continuous stream of liquid hydrogen with a diameter of a few microns. The jet has been imaged at 1 μm resolution by shadowgraphy with a short pulse laser. The pointing stability has been measured at well below a mrad, for a stable free-standing filament of solid-density hydrogen.

  12. The High Strain Rate Deformation Behavior of High Purity Magnesium and AZ31B Magnesium Alloy

    Science.gov (United States)

    Livescu, Veronica; Cady, Carl M.; Cerreta, Ellen K.; Henrie, Benjamin L.; Gray, George T.

    The deformation in compression of pure magnesium and AZ31B magnesium alloy, both with a strong basal pole texture, has been investigated as a function of temperature, strain rate, and specimen orientation. The mechanical response of both metals is highly dependent upon the orientation of loading direction with respect to the basal pole. Specimens compressed along the basal pole direction have a high sensitivity to strain rate and temperature and display a concave down work hardening behavior. Specimens loaded perpendicularly to the basal pole have a yield stress that is relatively insensitive to strain rate and temperature and a work hardening behavior that is parabolic and then linearly upwards. Both specimen orientations display a mechanical response that is sensitive to temperature and strain rate. Post mortem characterization of the pure magnesium was conducted on a subset of specimens to determine the microstructural and textural evolution during deformation and these results are correlated with the observed work hardening behavior and strain rate sensitivities were calculated.

  13. The Rate Sensitivity of High Strength Syntactic Foam

    National Research Council Canada - National Science Library

    Doleski, Robert; Plunkett, Stephen; Tucker, Wayne

    2003-01-01

    .... Quasi-static experiments were also conducted in compression, tension, and shear. A comparison of the quasi-static and dynamic properties showed that syntactic foam is mildly dependent on rate in compression...

  14. Experimental characterization and modelling of UO2 mechanical behaviour at high temperatures and high strain rates

    International Nuclear Information System (INIS)

    Salvo, Maxime

    2014-01-01

    The aim of this work is to characterize and model the mechanical behavior of uranium dioxide (UO 2 ) during a Reactivity Initiated Accident (RIA). The fuel loading during a RIA is characterized by high strain rates (up to 1/s) and high temperatures (1000 C - 2500 C). Two types of UO 2 pellets (commercial and high density) were therefore tested in compression with prescribed displacement rates (0.1 to 100 mm/min corresponding to strain rates of 10 -4 - 10 -1 /s) and temperatures (1100 C - 1350 C - 1550 C et 1700 C). Experimental results (geometry, yield stress and microstructure) allowed us to define a hyperbolic sine creep law and a Drucker-Prager criterion with associated plasticity, in order to model grain boundaries fragmentation at the macroscopic scale. Finite Element Simulations of these tests and of more than 200 creep tests were used to assess the model response to a wide range of temperatures (1100 C - 1700 C) and strain rates (10 -9 /s - 10 -1 /s). Finally, a constitutive law called L3F was developed for UO 2 by adding to the previous model irradiation creep and tensile macroscopic cracking. The L3F law was then introduced in the 1.5D scheme of the fuel performance code ALCYONE-RIA to simulate the REP-Na tests performed in the experimental reactor CABRI. Simulation results are in good agreement with post tests examinations. (author) [fr

  15. Modelling of behaviour of metals at high strain rates

    OpenAIRE

    Panov, Vili

    2006-01-01

    The aim of the work presented in this thesis was to produce the improvement of the existing simulation tools used for the analysis of materials and structures, which are dynamically loaded and subjected to the different levels of temperatures and strain rates. The main objective of this work was development of tools for modelling of strain rate and temperature dependant behaviour of aluminium alloys, typical for aerospace structures with pronounced orthotropic properties, and their implementa...

  16. Engagement and Nonusage Attrition With a Free Physical Activity Promotion Program: The Case of 10,000 Steps Australia.

    Science.gov (United States)

    Guertler, Diana; Vandelanotte, Corneel; Kirwan, Morwenna; Duncan, Mitch J

    2015-07-15

    Data from controlled trials indicate that Web-based interventions generally suffer from low engagement and high attrition. This is important because the level of exposure to intervention content is linked to intervention effectiveness. However, data from real-life Web-based behavior change interventions are scarce, especially when looking at physical activity promotion. The aims of this study were to (1) examine the engagement with the freely available physical activity promotion program 10,000 Steps, (2) examine how the use of a smartphone app may be helpful in increasing engagement with the intervention and in decreasing nonusage attrition, and (3) identify sociodemographic- and engagement-related determinants of nonusage attrition. Users (N=16,948) were grouped based on which platform (website, app) they logged their physical activity: Web only, app only, or Web and app. Groups were compared on sociodemographics and engagement parameters (duration of usage, number of individual and workplace challenges started, and number of physical activity log days) using ANOVA and chi-square tests. For a subsample of users that had been members for at least 3 months (n=11,651), Kaplan-Meier survival curves were estimated to plot attrition over the first 3 months after registration. A Cox regression model was used to determine predictors of nonusage attrition. In the overall sample, user groups differed significantly in all sociodemographics and engagement parameters. Engagement with the program was highest for Web-and-app users. In the subsample, 50.00% (5826/11,651) of users stopped logging physical activity through the program after 30 days. Cox regression showed that user group predicted nonusage attrition: Web-and-app users (hazard ratio=0.86, 95% CI 0.81-0.93, Pworkplace challenges (hazard ratio=0.94, 95% CI 0.90-0.97, Pphysical activity logging days (hazard ratio=0.921, 95% CI 0.919-0.922, P<.001), and steps logged per day (hazard ratio=0.99999, 95% CI 0

  17. High birth rates despite easy access to contraception and abortion

    DEFF Research Database (Denmark)

    Hognert, Helena; Skjeldestad, Finn E; Gemzell-Danielsson, Kristina

    2017-01-01

    INTRODUCTION: The aim of this study was to describe and compare contraceptive use, fertility, birth, and abortion rates in the Nordic countries. MATERIAL AND METHODS: National data on births, abortions, fertility rate (1975-2013), redeemed prescriptions of hormonal contraceptives and sales figures...... contraception followed by the levonorgestrel-releasing intrauterine system were the most common methods. During 1975-2013 abortion rates decreased in Denmark (from 27/1000 women to 15/1000 women aged 15-44/1000 women) and Finland (from 20 to 10/1000 women), remained stable in Norway (≈16) and Sweden (≈20......) and increased in Iceland (from 6 to 15/1000 women). Birth rates remained stable around 60/1000 women aged 15-44 in all countries except for Iceland where the birth rate decreased from 95 to 65/1000 women. Abortion rates were highest in the age group 20-24 years. In the same age group, Sweden had a lower...

  18. High speed surface cleaning by a high repetition rated TEA-CO2 laser

    International Nuclear Information System (INIS)

    Tsunemi, Akira; Hirai, Ryo; Hagiwara, Kouji; Nagasaka, Keigo; Tashiro, Hideo

    1994-01-01

    We demonstrated the feasibility of high speed cleaning of solid surfaces by the laser ablation technique using a TEA-CO 2 laser. The laser pulses with the repetition rate of 1 kHz were applied to paint, rust, moss and dirt attached on the surfaces. The attachments were effectively removed without the damage of bulk surfaces by the irradiation of line-focused sequential pulses with an energy of 300 mJ/pulse. A cleaning rate reached to 17 m 2 /hour for the case of paint removal from iron surfaces. (author)

  19. Hazard rate for a two-channel protective system subject to a high demand rate

    International Nuclear Information System (INIS)

    Oliveira, L.F.; Youngblood, R.; Melo, P.F.F.

    1989-01-01

    A basic figure of merit associated with a protective system for an industrial plant is the number of accidents expected to occur in the plant within a given period of time, with the system installed. By definition, in a plant equipped with a protective system, an accident can only happen if an initiating event (a demand) occurs while the protective system is unavailable, that is, while it is in one of its possible failed states. This means that the hazard rate or accident frequency depends on the demand rate and on the unavailability of the protective systems. It has long been recognized that the demand rate influences the unavailability of the protective system, and practical expressions incorporating that effect have been developed for single-channel (Lees, 1982) and multi-channel (Kumamoto and Henley 1978) protective systems. The effect has also been incorporated into a Markovian treatment of a plant protection system (Papazoglou and Cho, 1985). In a previous paper (Oliveira and Netto, 1987) a Markovian approach was used to derive analytical expressions for the evaluation of the plant hazard rate for a single-channel protective system, properly accounting for the effects of the demand and the repair rates. In this paper the authors present an extension of that model to the case of a plant equipped with a two-channel protective system

  20. Initial Entry Training: Reducing First Term Attrition Through Effective Organizational Socialization

    National Research Council Canada - National Science Library

    Hayden, Thomas

    2000-01-01

    .... Behavioral scientist claim that attrition in organizations can be attributed to many factors such as lack of commitment to the organization, poor skill development, mismatch in employee expectations...

  1. Potassium vapor assisted preparation of highly graphitized hierarchical porous carbon for high rate performance supercapacitors

    Science.gov (United States)

    Liu, Zheng; Zeng, Ying; Tang, Qunli; Hu, Aiping; Xiao, Kuikui; Zhang, Shiying; Deng, Weina; Fan, Binbin; Zhu, Yanfei; Chen, Xiaohua

    2017-09-01

    Ultrahigh graphitized carbon microspheres with rich hierarchical pores (AGHPCM-1) have been successfully synthesized through the one-step activation-carbonization strategy (OACS) with porous sulfonated poly-divinylbenzene as the carbon precursor, iron as the hard template and catalyst, and potassium hydroxide (KOH) as activation agent. Through the XRD, TEM, Raman and BET analysis, AGHPCM-1 shows very high graphitization degree and rich micro-, meso- and macro-pores. More importantly, the mechanism for KOH to improve the graphitization degree of carbon materials in OACS has been illustrated by the thermodynamical theory. The tremendous heat releasing from the reaction between the catalyst precursor of Fe2O3 and potassium vapor plays a key role in the formation of graphitized carbon. It may provide a general direction to prepare highly graphitized porous carbon at a moderate temperature. Integrating the advantages of high graphitization degree and rich hierarchical porous structure, the AGHPCM-1 exhibits an excellent rate performance with a response to up to the high current density of 150 A g-1 and high scan rate of 2000 mV s-1. No obvious capacitance decay can be observed after 10000 charge/discharge cycles even at the high current density of 20 A g-1.

  2. Attrition and Rape Case Characteristics: A Profile and Comparison of Female Sex Workers and Non-Sex Workers.

    Science.gov (United States)

    Lea, Susan J; Callaghan, Lynne; Grafton, Iain; Falcone, M Aurora; Shaw, Steve

    2016-07-01

    The attrition of rape cases from the criminal justice system (CJS) remains high and there is a paucity of research in relation to marginalized groups. Sex workers (SWs) are vulnerable to sexual violence due to the nature of their work. They are also unlikely to report such violence to police for a range of reasons. Two stages of research sought to describe the victim, perpetrator, and offense characteristics of SW rape and to examine the attrition of these cases. All rapes and attempted rapes (N = 1,146) reported to police in a large city in the South West of England over a 21-year period were examined; 67 cases involved SWs. Data were extracted from police files in line with the variables of interest. Secondary analysis of the total number of SW rapes (n = 67) resulted in a profile of these cases. A matched pairs study revealed significant differences in victim, perpetrator, and assault characteristics between SW (n = 62) and non-sex-worker (NSW) samples (n = 62). Although no significant difference was found in terms of attrition from the CJS, SW cases were observed to secure more convictions for rape than NSW cases. The implications of the findings for practice and future research are discussed. © The Author(s) 2015.

  3. A multiwire proportional counter for very high counting rates

    International Nuclear Information System (INIS)

    Barbosa, A.F.; Guedes, G.P.; Tamura, E.; Pepe, I.M.; Oliveira, N.B.

    1997-12-01

    Preliminary measurements in a proportional counter with two independently counting wires showed that counting rates up to 10 6 counts/s per wire can be reached without critical loss in the true versus measured linearity relation. Results obtained with a detector containing 30 active wires (2 mm pitch) are presented. To each wire is associated a fast pre-amplifier and a discriminator channel. Global counting rates in excess to 10 7 events/s are reported. Data acquisition systems are described for 1D (real time) and 2D (off-line) position sensitive detection systems. (author)

  4. A multiwire proportional counter for very high counting rates

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, A F; Guedes, G P [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Tamura, E [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil); Pepe, I M; Oliveira, N B [Bahia Univ., Salvador, BA (Brazil). Inst. de Fisica

    1997-12-01

    Preliminary measurements in a proportional counter with two independently counting wires showed that counting rates up to 10{sup 6} counts/s per wire can be reached without critical loss in the true versus measured linearity relation. Results obtained with a detector containing 30 active wires (2 mm pitch) are presented. To each wire is associated a fast pre-amplifier and a discriminator channel. Global counting rates in excess to 10{sup 7} events/s are reported. Data acquisition systems are described for 1D (real time) and 2D (off-line) position sensitive detection systems. (author) 13 refs., 6 figs.

  5. [A preliminary analysis of the high birth rate in India].

    Science.gov (United States)

    Shao, N

    1981-01-01

    The author first provides some basic demographic data for India and points out that the current annual rate of population growth of 2.45 percent is slightly higher than the annual increase in food production. Problems in the areas of employment, education, housing, and transportation, as well as the general problem of poverty, are seen as a consequence of this imbalance. The lack of success of the national family planning program is attributed primarily to the failure to achieve a satisfactory rate of economic growth. Contributory factors include early marriage, the low status of women, the desire for large families, and administrative problems associated with the family planning program.

  6. High dose rate 192Ir calibration: Indonesia experiences

    International Nuclear Information System (INIS)

    Nasukha; Tjiptanto, D.; Darmasyah, R.; Kurniawan, B.

    2002-01-01

    Indonesia with a population of more than 200 Million people which spread on about 5000 islands, up to now only has 23 radiotherapy centers and some not active anymore. As mention by Parkin et al that Cervix/Utery and breast cancer are the most estimated numbers of new cases of cancers in women for developing countries, stomach and lung cancers in men. Indonesia as a developing country is likely similar to other developing countries on numbers of new cases of cancers in women. But quite different in men, in Indonesia the most common cancers are nasopharynx and thyroid cancers. The use of lr-192 sources in high dose-rate (HDR) remotely afterloaded brachytherapy treatments have greatly increased in recent years and variety of such sources are commercially available. Nine radiotherapy centers in Indonesia installed Nucletron microSelectron HDR remote afterloader. Based on the data of CiptoMangunkusurno Hospital, Jakarta that the most common cancers are the cervix, breast, nasopharynx and thyroid cancers which of percentage are about 31%, 25 %, 13%, and 6 % respectively. It means that the use of HDR 192 Ir brachytherapy has to be an effective tool in the treatments. Two methods have been studied and applied to calibrate HDR 192 Ir brachytherapy in Indonesia, especially for Nucletron microSelectron HDR 192 lr remote afterloader brachytherapy. Calibration of HDR 192 Ir brachytherapy source has been done by Cavity lonization Chamber and with Well Type lonization Chamber. First, 0.6 cc of NE Farmer type dosimeter that was calibrated to 60 Co and 250 kV of x-rays in air kerma was used in this experiment. Position of measurement (detector and source) at the center of the room and about 1 meter from the floor. Eight variation of distances from 10 cm to 40 cms have been carried out measurement as recommended by IAEA-TECDOC-1079. Correction have been given for scatters, non-uniformity, and attenuation. To solve the problem of scatter correction factor was used Matlab programming

  7. A system approach to high quality picture-rate conversion

    NARCIS (Netherlands)

    Bartels, C.L.L.; Cordes, C.N.; Riemens, B.; Haan, de G.

    2010-01-01

    Various techniques have been implemented to improve the motion portrayal of flat-panel displays, of which the widespread introduction of motion-compensated picture-rate conversion systems is an essential part. However, a careful design of such systems is critical as they have the potential to

  8. Key requirements for high quality picture-rate conversion.

    NARCIS (Netherlands)

    Cordes, C.N.; Haan, de G.

    2009-01-01

    Past LCD-TV generations suffered from a poor motion portrayal, causing the blurring of moving objects. Hence, various techniques have been implemented to improve their motion portrayal, of which the widespread introduction of motion compensated picture-rate conversion in TV systems is an essential

  9. High triacylglycerol turnover rate in human skeletal muscle

    DEFF Research Database (Denmark)

    Sacchetti, Massimo; Saltin, Bengt; Olsen, David B

    2004-01-01

    In the present study we investigated the relationship between plasma fatty acids (FA) and intramuscular triacylglycerol (IMTAG) kinetics of healthy volunteers. With this aim [U-(13)C]-palmitate was infused for 10 h and FA kinetics determined across the leg. In addition, the rate of FA incorporation...

  10. Anomalous electric field changes and high flash rate beneath a ...

    Indian Academy of Sciences (India)

    In spite of many experimental and theoretical studies the relationships between storm dynamics, severe weather,and lightning activity have been least understood.Measurements of electric field made under a severe thunderstorm at a northeastern Indian station,Guwahati,India are reported. Lightning flash rate increases ...

  11. High-temperature rate constant measurements for OH+xylenes

    KAUST Repository

    Elwardani, Ahmed Elsaid; Badra, Jihad; Farooq, Aamir

    2015-01-01

    The overall rate constants for the reactions of hydroxyl (OH) radicals with o-xylene (k 1), m-xylene (k 2), and p-xylene (k 3) were measured behind reflected shock waves over 890-1406K at pressures of 1.3-1.8atm using OH laser absorption near 306

  12. Development of bonded semiconductor device for high counting rate high efficiency photon detectors

    International Nuclear Information System (INIS)

    Kanno, Ikuo

    2008-01-01

    We are trying to decrease dose exposure in medical diagnosis by way of measuring the energy of X-rays. For this purpose, radiation detectors for X-ray energy measurement with high counting rate should be developed. Direct bonding of Si wafers was carried out to make a radiation detector, which had separated X-ray absorber and detector. The resistivity of bonding interface was estimated with the results of four-probe measurements and model calculations. Direct bonding of high resistivity p and n-Si wafers was also performed. The resistance of the pn bonded diode was 0.7 MΩ. The resistance should be increased in the future. (author)

  13. Attrition of limestone by impact loading in fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Fabrizio Scala; Fabio Montagnaro; Piero Salatino [Consiglio Nazionale delle Ricerche, Napoli (Italy). Istituto di Ricerche sulla Combustione

    2007-09-15

    The present study addresses limestone attrition and fragmentation associated with impact loading, a process which may occur extensively in various regions of fluidized bed (FB) combustors/gasifiers, primarily the jetting region of the bottom bed, the exit region of the riser, and the cyclone. An experimental protocol for the characterization of the propensity of limestone to undergo attrition/fragmentation by impact loading is reported. The application of the protocol is demonstrated with reference to an Italian limestone whose primary fragmentation and attrition by surface wear have already been characterized in previous studies. The experimental procedure is based on the characterization of the amount and particle size distribution of the debris generated upon the impact of samples of sorbent particles against a target. Experiments were carried out at a range of particle impact velocities between 10 and 45 m/s, consistent with jet velocities corresponding to typical pressure drops across FB gas distributors. The protocol has been applied to either raw or preprocessed limestone samples. In particular, the effect of calcination, sulfation, and calcination/recarbonation cycles on the impact damage suffered by sorbent particles has been assessed. The measurement of particle voidage and pore size distribution by mercury intrusion was also accomplished to correlate fragmentation with the structural properties of the sorbent samples. Fragmentation by impact loading of the limestone is significant. Lime displays the largest propensity to undergo impact damage, followed by the sorbent sulfated to exhaustion, the recarbonated sorbent, and the raw limestone. Fragmentation of the raw limestone and of the sulfated lime follows a pattern typical of the failure of brittle materials. The fragmentation behavior of lime and recarbonated lime better conforms to a disintegration failure mode, with an extensive generation of very fine fragments. 27 refs., 9 figs. 1 tab.

  14. Early nurse attrition in New Zealand and associated policy implications.

    Science.gov (United States)

    Walker, L; Clendon, J

    2018-03-01

    To examine the factors contributing to nurses choosing to exit the nursing profession before retirement age. Population growth, ageing and growing demand for health services mean increased demand for nurses. Better retention could help meet this demand, yet little work has been done in New Zealand to understand early attrition. An online survey of registered and enrolled nurses and nurse practitioners who had left nursing was used. This study reports analysis of responses from 285 ex-nurses aged under 55. The primary reasons nurses left the profession were as follows: workplace concerns; personal challenges; career factors; family reasons; lack of confidence; leaving for overseas; unwillingness to complete educational requirements; poor work-life balance; and inability to find suitable nursing work. Most nurses discussed their intentions to leave with a family member or manager and most reported gaining transferrable skills through nursing. Nurses leave for many reasons. Implementing positive practice environments and individualized approaches to retaining staff may help reduce this attrition. Generational changes in the nature of work and careers mean that nurses may continue to leave the profession sooner than anticipated by policymakers. If the nursing workforce is to be able to meet projected need, education, recruitment and retention policies must urgently address issues leading to early attrition. In particular, policies improving the wider environmental context of nursing practice and ensuring that working environments are safe and nurses are well supported must be developed and implemented. Equally, national nursing workforce planning must take into account that nursing is no longer viewed as a career for life. © 2017 International Council of Nurses.

  15. Development of a high-count-rate neutron detector with position sensitivity and high efficiency

    International Nuclear Information System (INIS)

    Nelson, R.; Sandoval, J.

    1996-01-01

    While the neutron scattering community is bombarded with hints of new technologies that may deliver detectors with high-count-rate capability, high efficiency, gamma-ray insensitivity, and high resolution across large areas, only the time-tested, gas-filled 3 He and scintillation detectors are in widespread use. Future spallation sources with higher fluxes simply must exploit some of the advanced detector schemes that are as yet unproved as production systems. Technologies indicating promise as neutron detectors include pixel arrays of amorphous silicon, silicon microstrips, microstrips with gas, and new scintillation materials. This project sought to study the competing neutron detector technologies and determine which or what combination will lead to a production detector system well suited for use at a high-intensity neutron scattering source

  16. High Strain Rate Testing of Welded DOP-26 Iridium

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J. H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Miller, R. G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Carmichael, C. A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fox, E. E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    The iridium alloy DOP-26 is used to produce Clad Vent Set cups that protect the radioactive fuel in radioisotope thermoelectric generators (RTGs) which provide electric power for spacecraft and rovers. In a previous study, the tensile properties of DOP-26 were measured over a wide range of strain rates and temperatures and reported in ORNL/TM-2007/81. While that study established the properties of the base material, the fabrication of the heat sources requires welding, and the mechanical properties of welded DOP-26 have not been extensively characterized in the past. Therefore, this study was undertaken to determine the mechanical properties of DOP-26 specimens containing a transverse weld in the center of their gage sections. Tensile tests were performed at room temperature, 750, 900, and 1090°C and engineering strain rates of 1×10-3 and 10 s-1. Room temperature testing was performed in air, while testing at elevated temperatures was performed in a vacuum better than 1×10-4 Torr. The welded specimens had a significantly higher yield stress, by up to a factor of ~2, than the non-welded base material. The yield stress did not depend on the strain rate except at 1090°C, where it was slightly higher for the faster strain rate. The ultimate tensile stress, on the other hand, was significantly higher for the faster strain rate at temperatures of 750°C and above. At 750°C and above, the specimens deformed at 1×10-3 s-1 showed pronounced necking resulting sometimes in perfect chisel-edge fracture. The specimens deformed at 10 s-1 exhibited this fracture behavior only at the highest test temperature, 1090°C. Fracture occurred usually in the fusion zone of the weld and was, in most cases, primarily intergranular.

  17. High estradiol levels improve false memory rates and meta-memory in highly schizotypal women.

    Science.gov (United States)

    Hodgetts, Sophie; Hausmann, Markus; Weis, Susanne

    2015-10-30

    Overconfidence in false memories is often found in patients with schizophrenia and healthy participants with high levels of schizotypy, indicating an impairment of meta-cognition within the memory domain. In general, cognitive control is suggested to be modulated by natural fluctuations in oestrogen. However, whether oestrogen exerts beneficial effects on meta-memory has not yet been investigated. The present study sought to provide evidence that high levels of schizotypy are associated with increased false memory rates and overconfidence in false memories, and that these processes may be modulated by natural differences in estradiol levels. Using the Deese-Roediger-McDermott paradigm, it was found that highly schizotypal participants with high estradiol produced significantly fewer false memories than those with low estradiol. No such difference was found within the low schizotypy participants. Highly schizotypal participants with high estradiol were also less confident in their false memories than those with low estradiol; low schizotypy participants with high estradiol were more confident. However, these differences only approached significance. These findings suggest that the beneficial effect of estradiol on memory and meta-memory observed in healthy participants is specific to highly schizotypal individuals and might be related to individual differences in baseline dopaminergic activity. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. CU-STARs: Promoting STEM Diversity by Addressing First-year Attrition of Underrepresented Minorities

    Science.gov (United States)

    Battersby, Cara; Silvia, Devin W.; Ellingson, Erica; Sturner, Andrew P.; Peck, Courtney

    2015-01-01

    Upon first entering university, the fraction of students interested in pursuing a STEM major are distributed according to societal demographics (with 25% being underrepresented minorities), but by graduation, the fraction of students receiving STEM degrees is unbalanced, with underrepresented minorities receiving only 15% of STEM bachelor's degrees. The CU-STARs (CU Science, Technology, and Astronomy Recruits) program at the University of Colorado, Boulder is targeted to address the main triggers of early career attrition for underrepresented minorities in STEM disciplines. A select group of students are given financial support through work-study at the Fiske planetarium on campus, while resources to address other triggers of attrition are available to the entire cohort of interested students (typically ~5-10 per year). These resources are designed to promote social engagement and mentorship, while also providing a support network and resources to combat inadequate high school preparation for STEM courses. We achieve these goals through activities that include social events, mentor meetings, free tutoring, and special events to meet and talk with scientists. The culmination of the program for the recruits are a series of high school outreach events in underserved areas (inner city and rural alike), in which they become the expert. The STARs are paid for their time and take the lead in planning, teaching, and facilitating programs for the high school students, including classroom presentations, interactive lab activities, solar observing, and star parties. The high school outreach events provide role models and STEM exposure for the underserved high school community while simultaneously cementing the personal achievements and successes for the STARs. CU-STARs is now in its 4th year and is still growing. We are beginning the process of formal assessments of the program's success. We present details of the program implementation, a discussion of potential obstacles

  19. Application of a Duration Model in Programs for Prevention of University Attrition

    Directory of Open Access Journals (Sweden)

    Verónica Herrero

    2013-12-01

    Full Text Available Institutional practices related to the prevention of desertion of university students increasingly require validated instruments in order to anticipate such behavior. In this regard, different statistical models generated from information related to the students themselves, their homes, their academic performance, among other determinants have demonstrated to be of crucial value. This study aims to demonstrate the importance of a series of determinants explored in other studies. The main objective is to apply a dropout rate predictive model with at risk university students in order to generate early and progressively more effective results. The research demonstrates the usefulness of the duration models in a sample of classroom students and the capacity to anticipate behavior of permanence/attrition across time. This was done with risk estimates using the Cox model.

  20. Fast optical signal processing in high bit rate OTDM systems

    DEFF Research Database (Denmark)

    Poulsen, Henrik Nørskov; Jepsen, Kim Stokholm; Clausen, Anders

    1998-01-01

    As all-optical signal processing is maturing, optical time division multiplexing (OTDM) has also gained interest for simple networking in high capacity backbone networks. As an example of a network scenario we show an OTDM bus interconnecting another OTDM bus, a single high capacity user...

  1. Heavy-duty high-repetition-rate generators

    NARCIS (Netherlands)

    Heesch, van E.J.M.; Yan, K.; Pemen, A.J.M.

    2002-01-01

    We present our results on high-power repetitive pulse sources for continuous operation. Two 1-10-kW systems using advanced spark gap technology and a transmission line transformer have been tested for several hundred hours at a 60-MW pulse level. High reliability and above 90% overall efficiency are

  2. Compact Beamformer Design with High Frame Rate for Ultrasound Imaging

    Directory of Open Access Journals (Sweden)

    Jun Luo

    2014-04-01

    Full Text Available In medical field, two-dimension ultrasound images are widely used in clinical diagnosis. Beamformer is critical in determining the complexity and performance of an ultrasound imaging system. Different from traditional means implemented with separated chips, a compact beamformer with 64 effective channels in a single moderate Field Programmable Gate Array has been presented in this paper. The compactness is acquired by employing receive synthetic aperture, harmonic imaging, time sharing and linear interpolation. Besides that, multi-beams method is used to improve the frame rate of the ultrasound imaging system. Online dynamic configuration is employed to expand system’s flexibility to two kinds of transducers with multi-scanning modes. The design is verified on a prototype scanner board. Simulation results have shown that on-chip memories can be saved and the frame rate can be improved on the case of 64 effective channels which will meet the requirement of real-time application.

  3. High-dose rate fractionated interstitial radiotherapy for oropharyngeal carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Nose, Takayuki; Inoue, Toshihiko; Inoue, Takehiro; Teshima, Teruki; Murayama, Shigeyuki [Osaka Univ. (Japan). Faculty of Medicine

    1995-03-01

    The limitations of treating oropharyngeal cancer patients with definitive external radiotherapy are the complications of salivary glands, taste buds, mandible and temporomandibular joints. To avoid these complications we started interstitial radiotherapy as boost after 46 Gy of external radiotherapy. Ten cases (retromolar trigone; 1, soft palate; 1, base of tongue; 3, lateral wall; 5) were treated with this method and seven cases were controlled locally. With short follow-up period, xerostomia and dysgeusia are less than definitive external radiotherapy as clinical impression and no in-field recurrences have been experienced. With markedly increased tumor dose, the local control rate can be improved. This treatment method will be an alternative to definitive external radiotherapy to gain better QOL and higher control rate. (author).

  4. High repetition rate ultrashort laser cuts a path through fog

    Science.gov (United States)

    de la Cruz, Lorena; Schubert, Elise; Mongin, Denis; Klingebiel, Sandro; Schultze, Marcel; Metzger, Thomas; Michel, Knut; Kasparian, Jérôme; Wolf, Jean-Pierre

    2016-12-01

    We experimentally demonstrate that the transmission of a 1030 nm, 1.3 ps laser beam of 100 mJ energy through fog increases when its repetition rate increases to the kHz range. Due to the efficient energy deposition by the laser filaments in the air, a shockwave ejects the fog droplets from a substantial volume of the beam, at a moderate energy cost. This process opens prospects for applications requiring the transmission of laser beams through fogs and clouds.

  5. Soft X ray spectrometry at high count rates

    International Nuclear Information System (INIS)

    Blanc, P.; Brouquet, P.; Uhre, N.

    1978-06-01

    Two modifications of the classical method of X-ray spectrometry by a semi-conductor diode permit a count rate of 10 5 c/s with an energy resolution of 350 eV. With a specially constructed pulse height analyzer, this detector can measure four spectra of 5 ms each, in the range of 1-30 keV, during a plasma shot

  6. High-repetition-rate hydrogen chamber: Preliminary studies

    International Nuclear Information System (INIS)

    1967-01-01

    This report is a conclusion to the tests realised with an experimental bubbles chamber in view to study the possibilities to increase the repetition rate. The more important parameters (the evolution of the bubbles, the expansion system) are considered in a theoretical way. Then the hardware is described. To end, experimental results are compared with the first evaluations. The calculations and the experimentation are against an oscillation system for the expansion. A system with a locking is to he considered. (authors) [fr

  7. When did they leave, and why? A retrospective case study of attrition on the Nottingham undergraduate medical course

    Directory of Open Access Journals (Sweden)

    Yates Janet

    2012-06-01

    Full Text Available Abstract Background As part of a wider study into students who experience difficulties, we examined the course files of those who had failed to graduate. This was an exploratory, descriptive study investigating how many students left after academic failure or non-academic problems, or simply changed their minds about reading medicine, and at what stage. The aim of the study was to increase our knowledge about the timings of, and reasons for, attrition. This understanding might help to reduce student loss in the future, by informing selection procedures and improving pastoral support at critical times. It might also assist in long-term workforce planning in the NHS. Methods Relevant data on admission and course progress were extracted manually from the archived files of students who had failed to graduate from five recent consecutive cohorts (entry in 2000–2004 inclusive, using a customised Access database. Discrete categories of information were supplemented with free text entries. Results 1188 students registered over the five-year entry period and 73 (6% failed to graduate. The highest rates of attrition (46/1188, 4% occurred during the first two years (largely preclinical studies, with 34 students leaving voluntarily, including 11 within the first semester, and 12 having their courses terminated for academic failure. Seventeen left at the end of the third year (Honours course plus early clinical practice and the remaining ten during the final two clinical years. The reasons for attrition were not always clear-cut and often involved a mixture of academic, personal, social and health factors, especially mental health problems. Conclusions The causes of attrition are complex. A small number of students with clear academic failure might require individual educational interventions for remediation. However, this could have substantial resource implications for the Faculty. Mental health problems predominate in late course attrition and may have

  8. High rate lithium/thionyl chloride bipolar battery development

    Science.gov (United States)

    Russell, P. G.; Goebel, F.

    The lithium/thionyl chloride ( {Li}/{SOCl2}) electrochemistry is capable of providing high power and high specific power, especially under pulse discharge conditions, when cells containing thin components are arranged in a bipolar configuration. This paper describes recent work concerned with bipolar cell design, cathode evaluation, component manufacturing methods, and the assembly and testing of bipolar modules containing up to 150 cells for Sonobuoy application.

  9. High rate lithium-thionyl chloride bipolar battery development

    Energy Technology Data Exchange (ETDEWEB)

    Russell, P.G.; Goebel, F. [Yardney Technical Products, Inc., Pawcatuck, CT (United States)

    1994-12-31

    The lithium/thionyl chloride system is capable of providing both high power and high energy density when cells containing thin components are arranged in a bipolar configuration. Electrode current densities in excess of 300mA/cm{sup 2} are achieved during pulse discharge. The present work is concerned with bipolar cell design, cathode evaluation, component manufacturing methods, and the assembly and testing of bipolar modules containing up to 150 cells.

  10. High rate lithium/thionyl chloride bipolar battery development

    Energy Technology Data Exchange (ETDEWEB)

    Russell, P.G. [Yardney Technical Products, Inc., Pawcatuck, CT (United States); Goebel, F. [Yardney Technical Products, Inc., Pawcatuck, CT (United States)

    1995-04-01

    The lithium/thionyl chloride (Li/SOCl{sub 2}) electrochemistry is capable of providing high power and high specific power, especially under pulse discharge conditions, when cells containing thin components are arranged in a bipolar configuration. This paper describes recent work concerned with bipolar cell design, cathode evaluation, component manufacturing methods, and the assembly and testing of bipolar modules containing up to 150 cells for Sonobuoy application. (orig.)

  11. Exercise Intervention: Attrition, Compliance, Adherence, and Progression Following Hematopoietic Stem Cell Transplantation
.

    Science.gov (United States)

    Peters, Tara; Erdmann, Ruby; Hacker, Eileen Danaher

    2018-02-01

    Exercise is widely touted as an effective intervention to optimize health and well-being after high-dose chemotherapy and hematopoietic stem cell transplantation. 
. This article reports attrition, compliance, adherence, and progression from the strength training arm of the single-blind randomized, controlled trial Strength Training to Enhance Early Recovery (STEER). 
. 37 patients were randomized to the intervention and participated in a structured strength training program introduced during hospitalization and continued for six weeks after release. Research staff and patients maintained exercise logs to document compliance, adherence, and progression. 
. No patients left the study because of burden. Patients were compliant with completion of exercise sessions, and their adherence was high; they also progressed on their exercise prescription. Because STEER balances intervention effectiveness with patient burden, the findings support the likelihood of successful translation into clinical practice.

  12. Carbon nanotubes/cobalt sulfide composites as potential high-rate and high-efficiency supercapacitors

    Science.gov (United States)

    Chen, Chia-Ying; Shih, Zih-Yu; Yang, Zusing; Chang, Huan-Tsung

    2012-10-01

    We have prepared carbon nanotube (CNT)/cobalt sulfide (CoS) composites from cobalt nitrate, thioacetamide, and CNTs in the presence of poly(vinylpyrrolidone). CNT/CoS composites are deposited onto fluorine-doped tin oxide glass substrates and then subjected to simple annealing at 300 °C for 0.5 h to fabricate CNT/CoS electrodes. Data collected from Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and d-spacing reveal the changes in the CoS structures and crystalline lattices after annealing. Cyclic voltammetry results reveal that the annealed CNT/CoS composite electrodes yield values of 2140 ± 90 and 1370 ± 50 F g-1 for specific capacitance at scan rates of 10 and 100 mV s-1, respectively. To the best of our knowledge, the annealed CNT/CoS composite electrodes provide higher specific capacitance relative to other reported ones at a scan rate of 100 mV s-1. CNT/CoS composite electrodes yield a power density of 62.4 kW kg-1 at a constant discharge current density of 217.4 A g-1. With such a high-rate capacity and power density, CNT/CoS composite supercapacitors demonstrate great potential as efficient energy storage devices.

  13. Drift chamber system for use in a high rate environment

    International Nuclear Information System (INIS)

    Etkin, A.

    1978-01-01

    A system of short drift distance (0.125'') drift chambers is described. This system is being built for use in the Brookhaven National Laboratory Multiparticle Spectrometer. These chambers will be able to handle beam rates of several million/pulse and give a spatial resolution of the order of 150 μm. Cathode readout will provide unique 3-dimensional points for each crack. The readout will utilize three custom built integrated circuits, a four channel amplifier-shaper, a four channel discriminator and a four channel shift register delay and time digitizer. A summary of test results on a prototype is also given

  14. [High complication rate after surgical treatment of ankle fractures].

    Science.gov (United States)

    Bjørslev, Naja; Ebskov, Lars; Lind, Marianne; Mersø, Camilla

    2014-08-04

    The purpose of this study was to determine the quality and re-operation rate of the surgical treatment of ankle fractures at a large university hospital. X-rays and patient records of 137 patients surgically treated for ankle fractures were analyzed for: 1) correct classification according to Lauge-Hansen, 2) if congruity of the ankle joint was achieved, 3) selection and placement of the hardware, and 4) the surgeon's level of education. Totally 32 of 137 did not receive an optimal treatment, 11 were re-operated. There was no clear correlation between incorrect operation and the surgeon's level of education.

  15. High energy high repetition-rate thin-disk amplifier for OPCPA pumping

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Michael

    2013-08-15

    The development of a pump laser system for a high power and high repetition rate optical parametric chirped-pulse amplification (OPCPA) is presented in this thesis. The OPCPA system requires pump pulse energies in the range of tens of millijoules at high repetition rates with sub-picosecond pulse durations. This can be achieved to some extend with Innoslab amplifier technology. However, scaling to higher pulse energies at high repetition rates may be problematic. With the thin-disk amplifier presented in this thesis, output energies of 140 mJ at 100 kHz repetition rate could be achieved in burst-mode operation, which is a world record for this type of laser amplifier. Due to its material and spectral properties, ytterbium doped YAG (Yb:YAG) is used as a gain medium for the high power amplifier stages. The low quantum defect and the comparatively large emission bandwidth makes this material the choice for high power operation and sub-picosecond compressed pulse durations. The output beam profile as well as the shape of the output bursts is ideal to pump an OPCPA system. An OPCPA output energy in the millijoule range with repetition rates of 100 kHz to 1 MHz is needed to generate seed pulses for the FEL and for the application as pump-probe laser at the FEL facility. Since the development of this laser system needs to meet requirements set by the Free-Electron Laser in Hamburg (FLASH), the amplifier is conceived for burst-mode operation. The main requirement is a high intra-burst pulse repetition rate of more than 100 kHz and a uniform pulse train (burst) with equal properties for every pulse. The burst-mode is an operation mode where the laser never reaches a lasing equilibrium, which means that the behavior of the amplifier is similar to a switch-on of the laser system for every burst. This makes the development of the amplifier system difficult. Therefore, an analytical model has been developed to study the amplification process during the burst. This includes the

  16. High energy high repetition-rate thin-disk amplifier for OPCPA pumping

    International Nuclear Information System (INIS)

    Schulz, Michael

    2013-08-01

    The development of a pump laser system for a high power and high repetition rate optical parametric chirped-pulse amplification (OPCPA) is presented in this thesis. The OPCPA system requires pump pulse energies in the range of tens of millijoules at high repetition rates with sub-picosecond pulse durations. This can be achieved to some extend with Innoslab amplifier technology. However, scaling to higher pulse energies at high repetition rates may be problematic. With the thin-disk amplifier presented in this thesis, output energies of 140 mJ at 100 kHz repetition rate could be achieved in burst-mode operation, which is a world record for this type of laser amplifier. Due to its material and spectral properties, ytterbium doped YAG (Yb:YAG) is used as a gain medium for the high power amplifier stages. The low quantum defect and the comparatively large emission bandwidth makes this material the choice for high power operation and sub-picosecond compressed pulse durations. The output beam profile as well as the shape of the output bursts is ideal to pump an OPCPA system. An OPCPA output energy in the millijoule range with repetition rates of 100 kHz to 1 MHz is needed to generate seed pulses for the FEL and for the application as pump-probe laser at the FEL facility. Since the development of this laser system needs to meet requirements set by the Free-Electron Laser in Hamburg (FLASH), the amplifier is conceived for burst-mode operation. The main requirement is a high intra-burst pulse repetition rate of more than 100 kHz and a uniform pulse train (burst) with equal properties for every pulse. The burst-mode is an operation mode where the laser never reaches a lasing equilibrium, which means that the behavior of the amplifier is similar to a switch-on of the laser system for every burst. This makes the development of the amplifier system difficult. Therefore, an analytical model has been developed to study the amplification process during the burst. This includes the

  17. High strength semi-active energy absorbers using shear- and mixedmode operation at high shear rates

    Science.gov (United States)

    Becnel, Andrew C.

    This body of research expands the design space of semi-active energy absorbers for shock isolation and crash safety by investigating and characterizing magnetorheological fluids (MRFs) at high shear rates ( > 25,000 1/s) under shear and mixed-mode operation. Magnetorheological energy absorbers (MREAs) work well as adaptive isolators due to their ability to quickly and controllably adjust to changes in system mass or impact speed while providing fail-safe operation. However, typical linear stroking MREAs using pressure-driven flows have been shown to exhibit reduced controllability as impact speed (shear rate) increases. The objective of this work is to develop MREAs that improve controllability at high shear rates by using pure shear and mixed shear-squeeze modes of operation, and to present the fundamental theory and models of MR fluids under these conditions. A proof of concept instrument verified that the MR effect persists in shear mode devices at shear rates corresponding to low speed impacts. This instrument, a concentric cylinder Searle cell magnetorheometer, was then used to characterize three commercially available MRFs across a wide range of shear rates, applied magnetic fields, and temperatures. Characterization results are presented both as flow curves according to established practice, and as an alternate nondimensionalized analysis based on Mason number. The Mason number plots show that, with appropriate correction coefficients for operating temperature, the varied flow curve data can be collapsed to a single master curve. This work represents the first shear mode characterization of MRFs at shear rates over 10 times greater than available with commercial rheometers, as well as the first validation of Mason number analysis to high shear rate flows in MRFs. Using the results from the magnetorheometer, a full scale rotary vane MREA was developed as part of the Lightweight Magnetorheological Energy Absorber System (LMEAS) for an SH-60 Seahawk helicopter

  18. A Lithium-Air Battery Stably Working at High Temperature with High Rate Performance.

    Science.gov (United States)

    Pan, Jian; Li, Houpu; Sun, Hao; Zhang, Ye; Wang, Lie; Liao, Meng; Sun, Xuemei; Peng, Huisheng

    2018-02-01

    Driven by the increasing requirements for energy supply in both modern life and the automobile industry, the lithium-air battery serves as a promising candidate due to its high energy density. However, organic solvents in electrolytes are likely to rapidly vaporize and form flammable gases under increasing temperatures. In this case, serious safety problems may occur and cause great harm to people. Therefore, a kind of lithium-air that can work stably under high temperature is desirable. Herein, through the use of an ionic liquid and aligned carbon nanotubes, and a fiber shaped design, a new type of lithium-air battery that can effectively work at high temperatures up to 140 °C is developed. Ionic liquids can offer wide electrochemical windows and low vapor pressures, as well as provide high thermal stability for lithium-air batteries. The aligned carbon nanotubes have good electric and heat conductivity. Meanwhile, the fiber format can offer both flexibility and weavability, and realize rapid heat conduction and uniform heat distribution of the battery. In addition, the high temperature has also largely improved the specific powers by increasing the ionic conductivity and catalytic activity of the cathode. Consequently, the lithium-air battery can work stably at 140 °C with a high specific current of 10 A g -1 for 380 cycles, indicating high stability and good rate performance at high temperatures. This work may provide an effective paradigm for the development of high-performance energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. From emigrant to expat : Changed perspectives on first language attrition in a digital era

    NARCIS (Netherlands)

    Keijzer, Merel

    2015-01-01

    L1 attrition is the (partial) language loss that is found in healthy individuals who stop routinely using their L1 after moving to an L2 environment. Over the years, the phenomenon has attracted much interest, from the general public who have (directly and indirectly) experienced attrition, but also

  20. "Should I Stay or Should I Go?": Unpacking Teacher Attrition/Retention as an Educational Issue

    Science.gov (United States)

    Kelchtermans, Geert

    2017-01-01

    The paper starts from the observation that teacher attrition/retention seems to be a wicked issue: it seems to have strong face validity and a commonsense meaning, but the literature doesn't provide a clear and distinctive definition. In the first section, the author analyzes the different ways in which the issue of teacher attrition and retention…

  1. Travel time and attrition from VHA care among women veterans: how far is too far?

    Science.gov (United States)

    Friedman, Sarah A; Frayne, Susan M; Berg, Eric; Hamilton, Alison B; Washington, Donna L; Saechao, Fay; Maisel, Natalya C; Lin, Julia Y; Hoggatt, Katherine J; Phibbs, Ciaran S

    2015-04-01

    Travel time, an access barrier, may contribute to attrition of women veterans from Veterans Health Administration (VHA) care. We examined whether travel time influences attrition: (a) among women veterans overall, (b) among new versus established patients, and (c) among rural versus urban patients. This retrospective cohort study used logistic regression to estimate the association between drive time and attrition, overall and for new/established and rural/urban patients. In total, 266,301 women veteran VHA outpatients in the Fiscal year 2009. An "attriter" did not return for VHA care during the second through third years after her first 2009 visit (T0). Drive time (log minutes) was between the patient's residence and her regular source of VHA care. "New" patients had no VHA visits within 3 years before T0. Models included age, service-connected disability, health status, and utilization as covariates. Overall, longer drive times were associated with higher odds of attrition: drive time adjusted odds ratio=1.11 (99% confidence interval, 1.09-1.14). The relationship between drive time and attrition was stronger among new patients but was not modified by rurality. Attrition among women veterans is sensitive to longer drive time. Linking new patients to VHA services designed to reduce distance barriers (telemedicine, community-based clinics, mobile clinics) may reduce attrition among women new to VHA.

  2. High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors.

    Directory of Open Access Journals (Sweden)

    Dang Ho

    Full Text Available A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C, but this capability had not been linked to any key organisms. This study combined RNA-stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate. Acetate uptake and cumulative methane production were determined and kinetic parameters were estimated using model-based analysis. Pyrosequencing performed on 13C- enriched samples indicated that organisms accumulating labelled carbon were Coprothermobacter (all temperatures between 55 and 65°C, acetoclastic Methanosarcina (55 to 60°C and hydrogenotrophic Methanothermobacter (60 to 65°C. The increased relative abundance of Coprothermobacter with increased temperature corresponding with a shift to syntrophic acetate oxidation identified this as a potentially key oxidiser. Methanosarcina likely acts as both a hydrogen utilising and acetoclastic methanogen at 55°C, and is replaced by Methanothermobacter as a hydrogen utiliser at higher temperatures.

  3. High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors.

    Science.gov (United States)

    Ho, Dang; Jensen, Paul; Gutierrez-Zamora, Maria-Luisa; Beckmann, Sabrina; Manefield, Mike; Batstone, Damien

    2016-01-01

    A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA-stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate. Acetate uptake and cumulative methane production were determined and kinetic parameters were estimated using model-based analysis. Pyrosequencing performed on 13C- enriched samples indicated that organisms accumulating labelled carbon were Coprothermobacter (all temperatures between 55 and 65°C), acetoclastic Methanosarcina (55 to 60°C) and hydrogenotrophic Methanothermobacter (60 to 65°C). The increased relative abundance of Coprothermobacter with increased temperature corresponding with a shift to syntrophic acetate oxidation identified this as a potentially key oxidiser. Methanosarcina likely acts as both a hydrogen utilising and acetoclastic methanogen at 55°C, and is replaced by Methanothermobacter as a hydrogen utiliser at higher temperatures.

  4. SAFT Li-ion Technology for High Rate Applications

    National Research Council Canada - National Science Library

    Nechev, Kamen; Deveney, Bridget; Guseynov, Teymur; Erbacher, John; Vukson, Stephen

    2006-01-01

    SAFT will present an update of its state-of-the art Very High Power (VHP) Lithium-ion (Li-ion) technology. The VHP cells are currently being qualified for use in military aircraft applications as well as in future military hybrid vehicles...

  5. High prevalence rate of left superior vena cava determined by ...

    African Journals Online (AJOL)

    2013-10-08

    Oct 8, 2013 ... persistent LSVC (6). There was a similar high prevalence, in the current study, of persistent LSVC in patients with tetralogy of. Fallot and coarctation of the aorta when compared to other studies (6, 8). This can be explained by the fact that the patient sample in the current study with these lesions was small.

  6. Decreased reproductive rates in sheep fed a high selenium diet

    Science.gov (United States)

    High Se-containing forages grow on seleniferous soils in many parts of the United States and throughout the world. Selenium is an essential trace element that is required for many physiological processes but can also be either acutely or chronically toxic to livestock. Anecdotal reports of decrease...

  7. Waiving Away High School Graduation Rate Accountability? Policy Brief

    Science.gov (United States)

    Alliance for Excellent Education, 2012

    2012-01-01

    In November 2011, eleven states submitted applications to the U.S. Department of Education (ED) for waivers from key provisions of the No Child Left Behind Act. Although the waiver process presents an opportunity to strengthen college and career readiness among the nation's high school students, this analysis by the Alliance for Excellent…

  8. The High Cost of South Carolina's Low Graduation Rate. School Choice Issues in the State

    Science.gov (United States)

    Gottlob, Brian J.

    2007-01-01

    Research has documented a crisis in South Carolina's high school graduation rate. While state officials report a graduation rate above 70 percent, researchers from South Carolina and elsewhere place the rate just above 50 percent, with rates among minority students lower than 50 percent. South Carolina's graduation rate is the worst of all 50…

  9. Delayed high school start times later than 8:30am and impact on graduation rates and attendance rates.

    Science.gov (United States)

    McKeever, Pamela Malaspina; Clark, Linda

    2017-04-01

    The first purpose of this study was to investigate changes in high school graduation rates with a delayed school start time of later than 8:30am. The second aim of the study was to analyze the association between a delayed high school start time later than 8:30am and attendance rates. In the current study, a pre-post design using a repeated-measures analysis of variance was used to examine changes in attendance and graduation rates 2 years after a delayed start was implemented. Public high schools from 8 school districts (n=29 high schools) located throughout 7 different states. Schools were identified using previous research from the Children's National Medical Center's Division of Sleep Medicine Research Team. A total membership of more than 30,000 high school students enrolled in the 29 schools identified by the Children's National Medical Center's Research Team. A pre-post design was used for a within-subject design, controlling for any school-to-school difference in the calculation of the response variable. This is the recommended technique for a study that may include data with potential measurement error. Findings from this study linked a start time of later than 8:30am to improved attendance rates and graduation rates. Attendance rates and graduation rates significantly improved in schools with delayed start times of 8:30am or later. School officials need to take special notice that this investigation also raises questions about whether later start times are a mechanism for closing the achievement gap due to improved graduation rates. Copyright © 2017 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.

  10. MERLIN, a new high count rate spectrometer at ISIS

    International Nuclear Information System (INIS)

    Bewley, R.I.; Eccleston, R.S.; McEwen, K.A.; Hayden, S.M.; Dove, M.T.; Bennington, S.M.; Treadgold, J.R.; Coleman, R.L.S.

    2006-01-01

    MERLIN is designed to be a high intensity, medium energy resolution spectrometer. As such, it will complement the high-resolution MAPS spectrometer at ISIS. MERLIN will utilise all the latest advances in technology with a supermirror guide to enhance flux as well as 3 m long position-sensitive detectors in a vacuum making it ideal for single-crystal users. The detector bank will cover a massive π steradians of solid angle with an angular range from -45 o to +135 o degrees in the horizontal plane and ±30 o degrees in the vertical plane. This will allow large swathes of Q,ω space to be accessed in a single run. The instrument will be ready for commissioning in February 2006. This paper presents details of design and performance of this new instrument

  11. Building a Grad Nation: Progress and Challenge in Raising High School Graduation Rates. Annual Update 2016

    Science.gov (United States)

    DePaoli, Jennifer L.; Balfanz, Robert; Bridgeland, John

    2016-01-01

    The nation has achieved an 82.3 percent high school graduation rate--a record high. Graduation rates rose for all student subgroups, and the number of low-graduation-rate high schools and students enrolled in them dropped again, indicating that progress has had far-reaching benefits for all students. This report is the first to analyze 2014…

  12. Complex pulsing schemes for high frame rate imaging

    DEFF Research Database (Denmark)

    Misaridis, Thanassis; Fink, Mathias; Jensen, Jørgen Arendt

    2002-01-01

    up to a pulse train. The acoustically generated high time-bandwidth (TB) product waveforms can be compressed by using a filter bank of matched filters one for every beam direction. Matched filtering compresses the pulse train to a single pulse at the scatterer position plus a number of spike axial...... with linear frequency modulation along the transducer elements, that cover the 70% fractional bandwidth of the 7 MHz transducer. The resulted images (after beamforming and matched filtering) show an axial resolution at the same order as in conventional pulse excitation and axial sidelobes down to -45 d...

  13. High rate, fast timing Glass RPC for the high $\\eta$ CMS muon detectors

    CERN Document Server

    INSPIRE-00185093; Lagarde, François; Laktineh, Imad; Buridon, Victor; Chen, Xiushan; Combaret, Christophe; Eynard, Alexis; Germani, Lionel; Grenier, Gerald; Mathez, Hervé; Mirabito, Laurent; Petrukhin, Alexei; Steen, Arnaud; Tromeur, William; Wang, Yi; Gong, A.; Moreau, Nathalie; de la Taille, Christophe; Dulucq, Fréderic

    2017-02-11

    The HL-LHC phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. To achieve this goal in a reasonable time scale the instantaneous luminosity would also increase by an order of magnitude up to $6 \\cdot 10^{34}$ cm$^{-2}$s$^{-1}$. The region of the forward muon spectrometer ($|\\eta| > 1.6$) is not equipped with RPC stations. The increase of the expected particles rate up to 2 kHz/cm$^2$ ( including a safety factor 3 ) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The actual RPC technology of CMS cannot sustain the expected background level. A new generation Glass-RPC (GRPC) using low resistivity glass (LR) is proposed to equip at least the two most far away of the four high eta muon stations of CMS. The design of small size prototypes and the studies of their performances under high rate particles flux is presented.

  14. High rate, fast timing Glass RPC for the high ${\\eta}$ CMS muon detectors

    CERN Document Server

    Lagarde, F.; Laktineh, I.; Buridon, V.; Chen, X.; Combaret, C.; Eynard, A.; Germani, L.; Grenier, G.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Wang, Y.; Gong, A.; Moreau, N.; de la Taille, C.; Dulucq, F.; Cimmino, A.; Crucy, S.; Fagot, A.; Gul, M.; Rios, A.A.O.; Tytgat, M.; Zaganidis, N.; Aly, S.; Assran, Y.; Radi, A.; Sayed, A.; Singh, G.; Abbrescia, M.; Iaselli, G.; Maggi, M.; Pugliese, G.; Verwilligen, P.; Van Doninck, W.F.; Colafranceschi, S.; Sharmag, A.; Benussi, L.; Bianco, S.; Piccolo, D.; Primavera, F.; Bhatnagar, V.; Kumari, R.; Mehta, A.; Singh, J.; Ahmad, A.; Ahmed, W.; Asghar, M.I.; Awan, I.M.; Hoorani, R.; Muhammad, S.; Shahzad, H.; Shah, M.A.; Cho, S.W.; Choi, S.Y.; Hong, B.; Kang, M.H.; Lee, K.S.; Lim, J.H.; Park, S.K.; Kim, M.S.; Carpinteyro Bernardino, S.; Pedraza, I.; Uribe Estradam, C.; Carrillo Moreno, S.; Vazquez Valencia, F.; Pant, L.M.; Buontempo, S.; Cavallo, N.; Esposito, M.; Fabozzi, F.; Lanza, G.; Orso, I.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Thyssen, F.; Braghieri, A.; Magnani, A.; Montagna, P.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Ban, Y.; Qian, S.J.; Choi, M.; Choi, Y.; Goh, J.; Kim, D.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Litov, L.; Pavlov, B.; Petkov, P.; Bagaturia, I.; Lomidze, D.; Avila, C.; Cabrera, A.; Sanabria, J.C.; Crotty, I.; Vaitkus, J.

    2016-09-09

    The HL-LHC phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. To achieve this goal in a reasonable time scale the instantaneous luminosity would also increase by an order of magnitude up to $6.10^{34} cm^{-2} s^{-1}$ . The region of the forward muon spectrometer ($|{\\eta}| > 1.6$) is not equipped with RPC stations. The increase of the expected particles rate up to $2 kHz/cm^{2}$ (including a safety factor 3) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The actual RPC technology of CMS cannot sustain the expected background level. The new technology that will be chosen should have a high rate capability and provides a good spatial and timing resolution. A new generation of Glass-RPC (GRPC) using low-resistivity (LR) glass is proposed to equip at least the two most far away of the four high ${\\eta}$ muon stations of CMS. First the design of small size prototypes and studies of their perfor...

  15. Attrition-free pyrolysis to produce bio-oil and char.

    Science.gov (United States)

    Mauviel, Guillain; Guillain, Mauviel; Kies, Fairouz; Fairouz, Kies; René, Mar Sans; Mar, Sans Rene; Ferrer, Monique; Monique, Ferrer; Lédé, Jacques; Jacques, Lédé

    2009-12-01

    Experiments are performed on a laboratory scale setup where beech wood chips are heated by gas convection and walls radiation. This study shows that it is possible to obtain high bio-oil and char yields with relatively low external heat transfer coefficients. The main advantage of this convection/radiation heat transfer mode compared to solid-solid collisions, applied in fluidized bed or twin screw reactors, is the reduction of solid attrition (char and sand). Thus tricky gas-solid separation through hot cyclones and/or hot filters could be avoided or reduced. It should be possible to recover directly bio-oil with less char particles and char free of sand dust. These qualities would allow easier use of these bio-products in different applications.

  16. High frame-rate neutron radiography of dynamic events

    International Nuclear Information System (INIS)

    Bossi, R.H.; Robinson, A.H.; Barton, J.P.

    1981-01-01

    A system has been developed to perform neutron radiographic analysis of dynamic events having a duration of several milliseconds. The system has been operated in the range of 2000 to 10,000 frames/second. Synchronization has provided high-speed-motion neutron radiographs for evaluation of the firing cycle of 7.62 mm munition rounds within a steel rifle barrel. The system has also been used to demonstrate the ability to produce neutron radiographic movies of two-phase flow. The equipment uses the Oregon State University TRIGA reactor capable of pulsing to 3000 MW peak power, a neutron beam collimator, a scintillator neutron conversion screen coupled to an image intensifier, and a 16 mm high speed movie camera. The peak neutron flux incident at the object position is approximately 4 x 10 11 n/cm 2 s with a pulse, full width at half maximum, of 9 ms. Special studies have been performed on the scintillator conversion screens and on the effects of statistical limitations on the image quality. Modulation transfer function analysis has been used to assist in the evaluation of the system performance

  17. A High Rated Solar Water Distillation Unit for Solar Homes

    Directory of Open Access Journals (Sweden)

    Abhishek Saxena

    2016-01-01

    Full Text Available India is presently focusing on complete utilization of solar energy and saving fossil fuels, which are limited. Various solar energy systems like solar cookers, solar water heaters, solar lanterns, solar PV lights, and solar lamps are continuously availing by the people of India at a low cost and on good subsidies. Apart from this, India is a solar energy promising country with a good number of solar homes (carrying solar energy systems in its various locations. The present paper focuses on a unique combination of solar dish cooker (SDC and solar water heater (SWH to produce distilled water with a high distillate and a high daily productivity. The procedure has been discussed on the basis of experimental testing to produce distilled water by combining an evacuated type SWH and a SDC. Experimentation has been carried out in MIT, Moradabad (longitude, 28.83°N, and latitude, 78.78°E by developing the same experimental setup on behalf of solar homes. The daily productivity of distilled water was found around 3.66 litres per day in full sunshine hours for an approximated pH value of 7.7 and a ppm value of 21. The payback period (PBP has been estimated around 1.16 years of the present system.

  18. High frame-rate neutron radiography of dynamic events

    International Nuclear Information System (INIS)

    Bossi, R.H.; Robinson, A.H.; Barton, J.P.

    1983-01-01

    A system has been developed to perform neutron radiographic analysis of dynamic events having a duration of several milliseconds. The system has been operated in the range of 2000 to 10,000 frames/second. Synchronization has provided high-speed-motion neutron radiographs for evaluation of the firing cycle of 7.62 mm munition rounds within a steel rifle barrel. The system has also been used to demonstrate the ability to produce neutron radiographic movies of two phase flow. The equipment uses the Oregon State University TRIGA reactor capable of pulsing to 3000 MW peak power, a neutron beam collimator, a scintillator neutron conversion screen coupled to an image intensifier, and a 16 mm high speed movie camera. The peak neutron flux incident at the object position is approximately 4 x 10 11 n/cm 2 s with a pulse, full width at half maximum, of 9 ms. Special studies have been performed on the scintillator conversion screens and on the effects of statistical limitations on the image quality. Modulation transfer function analysis has been used to assist in the evaluation of the system performance. (Auth.)

  19. High rate deformation of metallic liner and its dislocation description

    International Nuclear Information System (INIS)

    Prut, V.V.; Shybaev, S.A.

    1996-01-01

    The dynamics of deformation in cylindrical liners are studied experimentally and theoretically in Z-pinch geometry, where the cylinders are deformed by a magnetic field created by a current flowing along the axis. This method allows one to obtain one-dimensional deformation and a reliable recording of magnetic field and cylinder deformation. The experiments are performed with a current amplitude of 0.8-3 MA and a current rise time of 2.5-4 μs. Aluminium and copper tubes, from 4 to 6 mm in diameter and 0.25-1 mm wall thick, are compressed. The deformation rates under study are in the range of 10 5 -10 6 s -1 . The time dependence of the radii of the copper and aluminium tubes are measured with a streak camera and by the pulsed x-ray technique. The time resolution of the streak and x-ray photographs is 10-15 ns, their spatial resolution is 10-15 μm. A rheological model describing the dynamics of compression is developed. The model includes the description of the metal as a plastic medium with moving dislocations in the solid state, and as a viscous medium in the liquid state. The one-dimensional solution to magneto-hydrodynamical equations of the liner dynamics is compared with the experimental results and thus the following rheological parameters of the metal are obtained: β, the probability of dislocation generation in plastic deformation; and σ d , the drag stress, the parameter which characterizes a drag force acting on the dislocation. (Author)

  20. Development of high capacity, high rate lithium ion batteries utilizing metal fiber conductive additives

    Science.gov (United States)

    Ahn, Soonho; Kim, Youngduk; Kim, Kyung Joon; Kim, Tae Hyung; Lee, Hyungkeun; Kim, Myung H.

    As lithium ion cells dominate the battery market, the performance improvement is an utmost concern among developers and researchers. Conductive additives are routinely employed to enhance electrode conductivity and capacity. Carbon particulates—graphite or carbon black powders—are conventional and popular choices as conductive fillers. However, percolation requirements of particles demand significant volumetric content of impalpable, and thereby high area conductive fillers. As might be expected, the electrode active surface area escalates unnecessarily, resulting in overall increase in reaction with electrolytes and organic solvents. The increased reactions usually manifest as an irreversible loss of anode capacity, gradual oxidation and consumption of electrolyte on the cathode—which causes capacity decline during cycling—and an increased threat to battery safety by gas evolution and exothermic solvent oxidation. In this work we have utilized high aspect ratio, flexible, micronic metal fibers as low active area and high conductivity additives. The metal fibers appear well dispersed within the electrode and to satisfy percolation requirements very efficiently at very low volumetric content compared to conventional carbon-based conductive additives. Results from 18650-type cells indicate significant enhancements in electrode capacity and high rate capability while the irreversible capacity loss is negligible.

  1. High-rate behaviour of iron ore pellet

    Science.gov (United States)

    Gustafsson, Gustaf; Häggblad, Hans-Åke; Jonsén, Pär; Nishida, Masahiro

    2015-09-01

    Iron ore pellets are sintered, centimetre-sized spheres of ore with high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. In the transportation from the pelletizing plants to the customers, the iron ore pellets are exposed to different loading situations, resulting in degradation of strength and in some cases fragmentation. For future reliable numerical simulations of the handling and transportation of iron ore pellets, knowledge about their mechanical properties is needed. This paper describes the experimental work to investigate the dynamic mechanical properties of blast furnace iron ore pellets. To study the dynamic fracture of iron ore pellets a number of split Hopkinson pressure bar tests are carried out and analysed.

  2. High Dynamic Optimized Carrier Loop Improvement for Tracking Doppler Rates

    Directory of Open Access Journals (Sweden)

    Amirhossein Fereidountabar

    2015-01-01

    Full Text Available Mathematical analysis and optimization of a carrier tracking loop are presented. Due to fast changing of the carrier frequency in some satellite systems, such as Low Earth Orbit (LEO or Global Positioning System (GPS, or some planes like Unmanned Aerial Vehicles (UAVs, high dynamic tracking loops play a very important role. In this paper an optimized tracking loop consisting of a third-order Phase Locked Loop (PLL assisted by a second-order Frequency Locked Loop (FLL for UAVs is proposed and discussed. Based on this structure an optimal loop has been designed. The main advantages of this approach are the reduction of the computation complexity and smaller phase error. The paper shows the simulation results, comparing them with a previous work.

  3. 192Ir high dose rate (HDR) interstitial brain implant: optimisation

    International Nuclear Information System (INIS)

    Tyagi, Anuj; Singh, Dinesh; Chitra, S.; Gupta, J.P.

    2001-01-01

    The new modality of stepping source dosimetry system (SSDs) illustrates a remarkable improvement in attaining the uniform and homogeneous dose distribution within the target volume. The technique enables the physicist to correct for a certain amount of misplacement or curvature of implant geometry. The short course of brachytherapy provides good palliation in terms of functional improvements with low and acceptable toxicity in high-grade glioma. With continual refinements of the technique, brachytherapy performed by a skilled brachytherapy team offers an opportunity to improve patient survival and quality of life. Since 1997, micro selectron HDR 192 Ir treatments are done including gynecological, oesophageal, breast, surface mould, soft tissue sarcoma (STS) and brain in our hospital. In this paper, procedure of interstitial brain implant in glioma as implant technique, simulation and treatment planning will be discussed

  4. Bringing High Rate, Low Latency Data From Unimak Island, Alaska

    Science.gov (United States)

    Feaux, K.; Jackson, M.; Mencin, D.; Gallaher, W.; Smith, S.; Bohnenstiehl, K.; Borsa, A.; Enders, M.; Coyle, B.; Paskievitch, J.; Read, C.

    2009-05-01

    The Plate Boundary Observatory (PBO), part of the NSF-funded EarthScope project, completed the installation of a fourteen GPS stations, eight tiltmeters, one webcam, and one digital broadband seismometer on Unimak Island, Alaska in August, 2008. PBO collaborated with the USGS, who provided engineering support for this project. Combined with the USGS operated seismic network, the Unimak Island network is a state of the art scientific network. The primary data communications goal of the project was to design and implement a robust data communications network capable of downloading 15-sec daily GPS files and to test the streaming of 1- Hz GPS data at a select set of GPS stations on Unimak Island. As part of the permitting agreement with the landowner, PBO co-located the GPS stations with existing USGS seismic stations. The high-speed radio link deployed allowed the USGS to test the feasibility of broadband seismometer installations on Unimak Island. This collaboration with the USGS was another successful joint operation between PBO and the USGS. The technical and logistical challenges involved in the project as well as some preliminary results of the data communications system will be presented. These challenges include complicated logistics, bad weather, complex network geometries with multiple radio repeaters, long distance RF transmission over water, hardware bandwidth limitations, power limitations, space limitations, as well as working in bear country on an incredibly remote and active volcano.

  5. Tiny timekeepers witnessing high-rate exhumation processes.

    Science.gov (United States)

    Zhong, Xin; Moulas, Evangelos; Tajčmanová, Lucie

    2018-02-02

    Tectonic forces and surface erosion lead to the exhumation of rocks from the Earth's interior. Those rocks can be characterized by many variables including peak pressure and temperature, composition and exhumation duration. Among them, the duration of exhumation in different geological settings can vary by more than ten orders of magnitude (from hours to billion years). Constraining the duration is critical and often challenging in geological studies particularly for rapid magma ascent. Here, we show that the time information can be reconstructed using a simple combination of laser Raman spectroscopic data from mineral inclusions with mechanical solutions for viscous relaxation of the host. The application of our model to several representative geological settings yields best results for short events such as kimberlite magma ascent (less than ~4,500 hours) and a decompression lasting up to ~17 million years for high-pressure metamorphic rocks. This is the first precise time information obtained from direct microstructural observations applying a purely mechanical perspective. We show an unprecedented geological value of tiny mineral inclusions as timekeepers that contributes to a better understanding on the large-scale tectonic history and thus has significant implications for a new generation of geodynamic models.

  6. Ilmenite Nanotubes for High Stability and High Rate Sodium-Ion Battery Anodes.

    Science.gov (United States)

    Yu, Litao; Liu, Jun; Xu, Xijun; Zhang, Liguo; Hu, Renzong; Liu, Jiangwen; Ouyang, Liuzhang; Yang, Lichun; Zhu, Min

    2017-05-23

    To solve the problem of large volume change and low electronic conductivity of earth-abundant ilmenite used in rechargeable Na-ion batteries (SIBs), an anode of tiny ilmenite FeTiO 3 nanoparticle embedded carbon nanotubes (FTO⊂CNTs) has been successfully proposed. By introducing a TiO 2 shell on metal-organic framework (Fe-MOF) nanorods by sol-gel deposition and subsequent solid-state annealing treatment of these core-shell Fe-MOF@TiO 2 , such well-defined FTO⊂CNTs are obtained. The achieved FTO⊂CNT electrode has several distinct advantages including a hollow interior in the hybrid nanostructure, fully encapsulated ultrasmall electroactive units, flexible conductive carbon matrix, and stable solid electrolyte interface (SEI) of FTO in cycles. FTO⊂CNT electrodes present an excellent cycle stability (358.8 mA h g -1 after 200 cycles at 100 mA g -1 ) and remarkable rate capability (201.8 mA h g -1 at 5000 mA g -1 ) with a high Coulombic efficiency of approximately 99%. In addition, combined with the typical Na 3 V 2 (PO 4 ) 3 cathode to constitute full SIBs, the assembled FTO⊂CNT//Na 3 V 2 (PO 4 ) 3 batteries are also demonstrated with superior rate capability and a long cycle life.

  7. DEVELOPMENT OF A HIGH RATE HIGH RESOLUTION DETECTOR FOR EXAFS EXPERIMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    DE GERONIMO,G.; O CONNOR,P.; BEUTTENMULLER,R.H.; LI,Z.; KUCZEWSKI,A.J.; SIDDONS,D.P.

    2002-11-10

    A new detector for EXAFS experiments is being developed. It is based on a multi-element Si sensor and dedicated readout ASICs. The sensor is composed of 384 pixels, each having 1 mm{sup 2} area, arranged in four quadrants of 12 x 8 elements, and wire-bonded to 32-channel front-end ASICs. Each channel implements low noise preamplification with self-adaptive continuous reset, high order shaper, band-gap referenced baseline stabilizer, one threshold comparator and two DAC adjustable window comparators, each followed by a 24-bit counter. Fabricated in 0.35{micro}m CMOS dissipates about 8mW per channel. First measurements show at room temperature a resolution of 14 rms electrons without the detector and of 40 rms electrons (340eV) with the detector connected and biased. Cooling at -35C a FWHM of 205eV (167eV from electronics) was measured at the Mn-K{alpha} line. A resolution of about 300eV was measured for rates approaching 100kcps/cm{sup 2} per channel, corresponding to an overall rate in excess of 10MHz/cm{sup 2}. A channel-to-channel threshold dispersion after DACs adjustment of 2.5 rms electrons was also measured.

  8. Consistent high clinical pregnancy rates and low ovarian hyperstimulation syndrome rates in high-risk patients after GnRH agonist triggering and modified luteal support

    DEFF Research Database (Denmark)

    Iliodromiti, Stamatina; Blockeel, Christophe; Tremellen, Kelton P

    2013-01-01

    Are clinical pregnancy rates satisfactory and the incidence of OHSS low after GnRH agonist trigger and modified intensive luteal support in patients with a high risk of ovarian hyperstimulation syndrome (OHSS)?......Are clinical pregnancy rates satisfactory and the incidence of OHSS low after GnRH agonist trigger and modified intensive luteal support in patients with a high risk of ovarian hyperstimulation syndrome (OHSS)?...

  9. Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-12-01

    Full Text Available The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been found to play an important role for this HSSS due to load transfer and strain partitioning between two phases, and a higher strain rate could cause even higher strain partitioning in the softer austenite grains, delaying the deformation instability. Deformation twins are observed in the austenite grains at all strain rates to facilitate the uniform tensile deformation. The B2 phase (FeAl intermetallic compound is less deformable at higher strain rates, resulting in easier brittle fracture in B2 particles, smaller dimple size and a higher density of phase interfaces in final fracture surfaces. Thus, more energy need be consumed during the final fracture for the experiments conducted at higher strain rates, resulting in better tensile toughness.

  10. Positive predictive value of device-detected atrial high-rate episodes at different rates and durations

    DEFF Research Database (Denmark)

    Kaufman, Elizabeth S; Israel, Carsten W; Nair, Girish M

    2012-01-01

    BACKGROUND: Pacemakers can automatically identify and catalog atrial high-rate episodes (AHREs). While most AHREs represent true atrial tachyarrhythmia/atrial fibrillation (AT/AF), a review of stored electrograms suggests that a substantial proportion do not. As AHREs may lead to the initiation o...

  11. Are Final Comments in Web Survey Panels Associated with Next-Wave Attrition?

    Directory of Open Access Journals (Sweden)

    Cynthia McLauchlan

    2016-12-01

    Full Text Available Near the end of a web survey respondents are often asked whether they have further comments. Such final comments are usually ignored, in part because open-ended questions are challenging to analyse. We explored whether final comments are associated with next-wave attrition in survey panels. We categorized a random sample of final comments in the Longitudinal Studies for the Social Sciences (LISS panel and Dutch Immigrant panel into one of eight categories (neutral, positive, six subcategories of negative and regressed the indicator of next-wave attrition on comment length, comment category and socio-demographic variables. In the Immigrant panel we found shorter final comments (55 words with decreased next-wave attrition relative to making no comment. Comments about unclear survey questions quadruple the odds of attrition and “other” (uncategorized negative comments almost double the odds of attrition. In the LISS panel, making a comment (vs. not and comment length are not associated with attrition. However, when specifying individual comment categories, neutral comments are associated with half the odds of attrition relative to not making a comment.

  12. A novel VLSI processor for high-rate, high resolution spectroscopy

    CERN Document Server

    Pullia, Antonio; Gatti, E; Longoni, A; Buttler, W

    2000-01-01

    A novel time-variant VLSI shaper amplifier, suitable for multi-anode Silicon Drift Detectors or other multi-element solid-state X-ray detection systems, is proposed. The new read-out scheme has been conceived for demanding applications with synchrotron light sources, such as X-ray holography or EXAFS, where both high count-rates and high-energy resolutions are required. The circuit is of the linear time-variant class, accepts randomly distributed events and features: a finite-width (1-10 mu s) quasi-optimal weight function, an ultra-low-level energy discrimination (approx 150 eV), and a full compatibility for monolithic integration in CMOS technology. Its impulse response has a staircase-like shape, but the weight function (which is in general different from the impulse response in time-variant systems) is quasi trapezoidal. The operation principles of the new scheme as well as the first experimental results obtained with a prototype of the circuit are presented and discussed in the work.

  13. Using NIF to Test Theories of High-Pressure, High-Rate Plastic Flow in Metals

    Science.gov (United States)

    Rudd, Robert E.; Arsenlis, A.; Cavallo, R. M.; Huntington, C. M.; McNaney, J. M.; Park, H. S.; Powell, P.; Prisbrey, S. T.; Remington, B. A.; Swift, D.; Wehrenberg, C. E.; Yang, L.

    2017-10-01

    Precisely controlled plasmas are playing key roles both as pump and probe in experiments to understand the strength of solid metals at high energy density (HED) conditions. In concert with theoretical advances, these experiments have enabled a predictive capability to model material strength at Mbar pressures and high strain rates. Here we describe multiscale strength models developed for tantalum starting with atomic bonding and extending up through the mobility of individual dislocations, the evolution of dislocation networks and so on until the ultimate material response at the scale of an experiment. Experiments at the National Ignition Facility (NIF) probe strength in metals ramp compressed to 1-8 Mbar. The model is able to predict 1 Mbar experiments without adjustable parameters. The combination of experiment and theory has shown that solid metals can behave significantly differently at HED conditions. We also describe recent studies of lead compressed to 3-5 Mbar. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  14. WEAK LINE QUASARS AT HIGH REDSHIFT: EXTREMELY HIGH ACCRETION RATES OR ANEMIC BROAD-LINE REGIONS?

    International Nuclear Information System (INIS)

    Shemmer, Ohad; Trakhtenbrot, Benny; Netzer, Hagai; Anderson, Scott F.; Brandt, W. N.; Schneider, Donald P.; Diamond-Stanic, Aleksandar M.; Fan Xiaohui; Lira, Paulina; Plotkin, Richard M.; Richards, Gordon T.; Strauss, Michael A.

    2010-01-01

    We present Gemini-North K-band spectra of two representative members of the class of high-redshift quasars with exceptionally weak rest-frame ultraviolet emission lines (WLQs), SDSS J114153.34+021924.3 at z = 3.55 and SDSS J123743.08+630144.9 at z = 3.49. In both sources, we detect an unusually weak broad Hβ line and place tight upper limits on the strengths of their [O III] lines. Virial, Hβ-based black hole mass determinations indicate normalized accretion rates of L/L Edd =0.4 for these sources, which is well within the range observed for typical quasars with similar luminosities and redshifts. We also present high-quality XMM-Newton imaging spectroscopy of SDSS J114153.34+021924.3 and find a hard-X-ray photon index of Γ = 1.91 +0.24 -0.22 , which supports the virial L/L Edd determination in this source. Our results suggest that the weakness of the broad emission lines in WLQs is not a consequence of an extreme continuum-emission source but instead due to abnormal broad emission line region properties.

  15. Development of Fast High-Resolution Muon Drift-Tube Detectors for High Counting Rates

    CERN Document Server

    INSPIRE-00287945; Dubbert, J.; Horvat, S.; Kortner, O.; Kroha, H.; Legger, F.; Richter, R.; Adomeit, S.; Biebel, O.; Engl, A.; Hertenberger, R.; Rauscher, F.; Zibell, A.

    2011-01-01

    Pressurized drift-tube chambers are e?cient detectors for high-precision tracking over large areas. The Monitored Drift-Tube (MDT) chambers of the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) reach a spatial resolution of 35 micons and almost 100% tracking e?ciency with 6 layers of 30 mm diameter drift tubes operated with Ar:CO2 (93:7) gas mixture at 3 bar and a gas gain of 20000. The ATLAS MDT chambers are designed to cope with background counting rates due to neutrons and gamma-rays of up to about 300 kHz per tube which will be exceeded for LHC luminosities larger than the design value of 10-34 per square cm and second. Decreasing the drift-tube diameter to 15 mm while keeping the other parameters, including the gas gain, unchanged reduces the maximum drift time from about 700 ns to 200 ns and the drift-tube occupancy by a factor of 7. New drift-tube chambers for the endcap regions of the ATLAS muon spectrometer have been designed. A prototype chamber consisting of 12 times 8 l...

  16. Metabolic rate and gross efficiency at high work rates in world class and national level sprint skiers.

    Science.gov (United States)

    Sandbakk, Øyvind; Holmberg, Hans-Christer; Leirdal, Stig; Ettema, Gertjan

    2010-06-01

    The present study investigated metabolic rate (MR) and gross efficiency (GE) at moderate and high work rates, and the relationships to gross kinematics and physical characteristics in elite cross-country skiers. Eight world class (WC) and eight national level (NL) male sprint cross-country skiers performed three 5-min stages using the skating G3 technique, whilst roller skiing on a treadmill. GE was calculated by dividing work rate by MR. Work rate was calculated as the sum of power against gravity and frictional rolling forces. MR was calculated using gas exchange and blood lactate values. Gross kinematics, i.e. cycle length (CL) and cycle rate (CR) were measured by video analysis. Furthermore, the skiers were tested for time to exhaustion (TTE), peak oxygen uptake (VO(2peak)), and maximal speed (V(max)) on the treadmill, and maximal strength in the laboratory. Individual performance level in sprint skating was determined by FIS points. WC skiers did not differ in aerobic MR, but showed lower anaerobic MR and higher GE than NL skiers at a given speed (all P higher V(max) and TTE (all P better technique and to technique-specific power.

  17. Application of high rate, high temperature anaerobic digestion to fungal thermozyme hydrolysates from carbohydrate wastes.

    Science.gov (United States)

    Forbes, C; O'Reilly, C; McLaughlin, L; Gilleran, G; Tuohy, M; Colleran, E

    2009-05-01

    The objective of this study was to examine the feasibility of using a two-step, fully biological and sustainable strategy for the treatment of carbohydrate rich wastes. The primary step in this strategy involves the application of thermostable enzymes produced by the thermophilic, aerobic fungus, Talaromyces emersonii, to carbohydrate wastes producing a liquid hydrolysate discharged at elevated temperatures. To assess the potential of thermophilic treatment of this hydrolysate, a comparative study of thermophilic and mesophilic digestion of four sugar rich thermozyme hydrolysate waste streams was conducted by operating two high rate upflow anaerobic hybrid reactors (UAHR) at 37 degrees C (R1) and 55 degrees C (R2). The operational performance of both reactors was monitored from start-up by assessing COD removal efficiencies, volatile fatty acid (VFA) discharge and % methane of the biogas produced. Rapid start-up of both R1 and R2 was achieved on an influent composed of the typical sugar components of the organic fraction of municipal solid waste (OFMSW). Both reactors were subsequently challenged in terms of volumetric loading rate (VLR) and it was found that a VLR of 9 gCOD l(-1)d(-1) at a hydraulic retention time (HRT) of 1 day severely affected the thermophilic reactor with instability characterised by a build up of volatile fatty acid (VFA) intermediates in the effluent. The influent to both reactors was changed to a simple glucose and sucrose-based influent supplied at a VLR of 4.5 gCOD l(-1)d(-1) and HRT of 2 days prior to the introduction of thermozyme hydrolysates. Four unique thermozyme hydrolysates were subsequently supplied to the reactors, each for a period of 10 HRTs. The applied hydrolysates were derived from apple pulp, bread, carob powder and cardboard, all of which were successfully and comparably converted by both reactors. The % total carbohydrate removal by both reactors was monitored during the application of the sugar rich thermozyme

  18. Health worker attrition at a rural district hospital in Rwanda: a need ...

    African Journals Online (AJOL)

    Health worker attrition at a rural district hospital in Rwanda: a need for improved placement and retention strategies. Jackline Odhiambo, Felix Cyamatare Rwabukwisi, Christian Rusangwa, Vincent Rusanganwa, Lisa Ruth Hirschhorn, Evrard Nahimana, Patient Ngamije, Bethany Lynn Hedt-Gauthier ...

  19. Initial Entry Training: Reducing First Term Attrition Through Effective Organizational Socialization

    National Research Council Canada - National Science Library

    Hayden, Thomas

    2000-01-01

    This paper examines Initial Entry Training (IET) from an organizational behavior perspective to identify if the Army's socialization experience can be enhanced to have a positive impact on first term attrition within the Army...

  20. The relationship between beginning teachers' stress causes, stress responses, teaching behaviour and attrition

    NARCIS (Netherlands)

    Harmsen, Ruth; Lorenz, Michelle; Maulana, Ridwan; van Veen, Klaas

    2018-01-01

    In this study, the relationships between beginning teachers’ perceived stress causes, stress responses, observed teaching behaviour and attrition is investigated employing structural equation modelling (SEM). A total of 143 BTs were surveyed using the Questionnaire on the Experience and Evaluation

  1. Risk Attitudes, Sample Selection and Attrition in a Longitudinal Field Experiment

    DEFF Research Database (Denmark)

    Harrison, Glenn W.; Lau, Morten Igel

    with respect to risk attitudes. Our design builds in explicit randomization on the incentives for participation. We show that there are significant sample selection effects on inferences about the extent of risk aversion, but that the effects of subsequent sample attrition are minimal. Ignoring sample...... selection leads to inferences that subjects in the population are more risk averse than they actually are. Correcting for sample selection and attrition affects utility curvature, but does not affect inferences about probability weighting. Properly accounting for sample selection and attrition effects leads...... to findings of temporal stability in overall risk aversion. However, that stability is around different levels of risk aversion than one might naively infer without the controls for sample selection and attrition we are able to implement. This evidence of “randomization bias” from sample selection...

  2. A Longitudinal Examination of First Term Attrition and Reenlistment among FY1999 Enlisted Accessions

    National Research Council Canada - National Science Library

    Strickland, William J

    2005-01-01

    .... This effort allowed the evaluation of models of attrition and reenlistment intentions based on information contained in personnel records and collected from Soldiers who were surveyed as they entered...

  3. Analysis of Recruit Attrition from the Navy's Delayed Entry Program and Recruit Training Command

    National Research Council Canada - National Science Library

    Neuhalfen, Jon K

    2007-01-01

    .... The analysis uses the PRIDE database, provided by Commander, Navy Recruiting Command. Trend analyses are used to identify significant changes in enlistment and attrition behavior for recruits who joined from fiscal years 1998 through 2005...

  4. Programmable High-Rate Multi-Mission Receiver for Space Communications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Current and upcoming NASA space links require both highly reliable low-rate communications links supporting critical TT&C, ranging and voice services and highly...

  5. Programmable High-Rate Multi-Mission Receiver for Space Communications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Current and upcoming NASA space links require both highly reliable low-rate communications links supporting critical TT&C, ranging and voice services and highly...

  6. 31 CFR 356.21 - How are awards at the high yield or discount rate calculated?

    Science.gov (United States)

    2010-07-01

    ... discount rate calculated? 356.21 Section 356.21 Money and Finance: Treasury Regulations Relating to Money... high yield or discount rate calculated? (a) Awards to submitters. We generally prorate bids at the highest accepted yield or discount rate under § 356.20(a)(2) of this part. For example, if 80.15% is the...

  7. The Impact of High School Exit Exams on Graduation Rates and Achievement

    Science.gov (United States)

    Caves, Katherine; Balestra, Simone

    2018-01-01

    The authors examined the short- and long-term effects of high school exit exams (HSEEs) on graduation rates and achievement using an interrupted time series approach. There is a positive overall effect of HSEE introduction for graduation rate trends, which is heterogeneous over time. HSEEs have a negative impact on graduation rates in the year of…

  8. The Role of Personality Type on Minority Attrition at the US Naval Academy

    Science.gov (United States)

    2002-06-01

    Provost as more likely to attrite were ISTP, ESTP, ISFP, and ENFJ . “These students tend to be less organized, more passive in their relationship to...MBTI ISTP ISTJ ISFP ISFJ INTP INTJ INFP INFJ ESTP ESTJ ESFP ESFJ ENTP ENTJ ENFP ENFJ C ou nt 400 300 200 100 0 33 Table 12: Minority Attrition...reason to believe that all who are admitted have the potential to graduate. B. PURPOSE OF STUDY This thesis examines the relationship

  9. The impact of attrition on the representativeness of cohort studies of older people

    Directory of Open Access Journals (Sweden)

    Brilleman Samuel L

    2010-08-01

    Full Text Available Abstract Background There are well-established risk factors, such as lower education, for attrition of study participants. Consequently, the representativeness of the cohort in a longitudinal study may deteriorate over time. Death is a common form of attrition in cohort studies of older people. The aim of this paper is to examine the effects of death and other forms of attrition on risk factor prevalence in the study cohort and the target population over time. Methods Differential associations between a risk factor and death and non-death attrition are considered under various hypothetical conditions. Empirical data from the Australian Longitudinal Study on Women's Health (ALSWH for participants born in 1921-26 are used to identify associations which occur in practice, and national cross-sectional data from Australian Censuses and National Health Surveys are used to illustrate the evolution of bias over approximately ten years. Results The hypothetical situations illustrate how death and other attrition can theoretically affect changes in bias over time. Between 1996 and 2008, 28.4% of ALSWH participants died, 16.5% withdrew and 10.4% were lost to follow up. There were differential associations with various risk factors, for example, non-English speaking country of birth was associated with non-death attrition but not death whereas being underweight (body mass index Conclusions Deaths occur in both the target population and study cohort, while other forms of attrition occur only in the study cohort. Therefore non-death attrition may cause greater bias than death in longitudinal studies. However although more than a quarter of the oldest participants in the ALSWH died in the 12 years following recruitment, differences from the national population changed only slightly.

  10. National High School Graduation Rate: Are Recent Birth Cohorts Taking More Time to Graduate?

    Science.gov (United States)

    Joo, Myungkook; Kim, Jeounghee

    2016-01-01

    Debates about the national high school graduation rate have heated up as various national high school graduation estimates based on the Common Core of Data (CCD) and the Current Population Survey (CPS) do not coincide with one another partially due to different assumptions about graduation age. This study found that (a) while graduation rate by…

  11. High-Rate Disinfection Techniques for Combined Sewer Overflow (Proceedings Paper)

    Science.gov (United States)

    This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH ), a...

  12. High-Pressure Limit Rate Rules for α-H Isomerization of Hydroperoxyalkylperoxy Radicals

    KAUST Repository

    Mohamed, Samah Y; Davis, Alexander Cory; Al Rashidi, Mariam J; Sarathy, Mani

    2018-01-01

    group. In this work, a combination of high level composite methods - CBS-QB3, G3 and G4 - is used to determine the high-pressure-limit rate parameters for the title reaction. Rate rules for H-migration reactions proceeding through 5-, 6-, 7- and 8

  13. Graduation Rates in South Carolina Public High Schools: The Effect of School Size and Socioeconomic Status

    Science.gov (United States)

    Rivers, Thomas E., Jr.

    2012-01-01

    This study included a comparison of the graduation rates among high schools in South Carolina closely analyzing school size and socioeconomic status. The purpose for the study was to answer two questions: What patterns and relationships exist between school size and graduation rates at high schools in South Carolina? What patterns and…

  14. The Effect of Selected Nonmusical Factors on Adjudicators' Ratings of High School Solo Vocal Performances

    Science.gov (United States)

    Howard, Sandra A.

    2012-01-01

    The purpose of this study was to examine the effect of differentiated performance attire and stage deportment on adjudicators' ratings of high school solo vocal performances. High school choral students (n = 153) and undergraduate (n = 97) and graduate music majors (n = 32) served as adjudicators (N = 282). Adjudicators rated recorded solo vocal…

  15. Flotability Improvement of Ilmenite Using Attrition-Scrubbing as a Pretreatment Method

    Directory of Open Access Journals (Sweden)

    Jihua Zhai

    2017-01-01

    Full Text Available Flotation technology of the recovery and utilization of ilmenite from tailings of iron beneficiated in Panzhihua was investigated based on mineralogical study. The results of mineralogical study show that the main occurrence of the valuable mineral are liberated grains of ilmenite. Experimental results of flotation conditions show that attrition-scrubbing raw ores exhibit good flotability with higher recoveries and a slight decrease in grade compared to ores without attrition-scrubbing. Further, open-circuit experiments also prove the superiority of attrition-scrubbing raw ores. The results of closed-circuit experiments show that qualified ilmenite concentrate can be obtained and the yield, grade, and recovery are 22.26%, 47.06%, and 60.73%, respectively. Theoretical study and analysis show that there are two contributions to superior flotability for attrition-scrubbing samples. The first is that the attrition-scrubbing samples can uncover more ferrous ions on the newly-produced fresh ilmenite surface, resulting in the increase in active sites. The other is that in the process of attrition-scrubbing, the transformation of ferrous ions to ferric ions can be promoted.

  16. Selective attrition and intraindividual variability in response time moderate cognitive change.

    Science.gov (United States)

    Yao, Christie; Stawski, Robert S; Hultsch, David F; MacDonald, Stuart W S

    2016-01-01

    Selection of a developmental time metric is useful for understanding causal processes that underlie aging-related cognitive change and for the identification of potential moderators of cognitive decline. Building on research suggesting that time to attrition is a metric sensitive to non-normative influences of aging (e.g., subclinical health conditions), we examined reason for attrition and intraindividual variability (IIV) in reaction time as predictors of cognitive performance. Three hundred and four community dwelling older adults (64-92 years) completed annual assessments in a longitudinal study. IIV was calculated from baseline performance on reaction time tasks. Multilevel models were fit to examine patterns and predictors of cognitive change. We show that time to attrition was associated with cognitive decline. Greater IIV was associated with declines on executive functioning and episodic memory measures. Attrition due to personal health reasons was also associated with decreased executive functioning compared to that of individuals who remained in the study. These findings suggest that time to attrition is a useful metric for representing cognitive change, and reason for attrition and IIV are predictive of non-normative influences that may underlie instances of cognitive loss in older adults.

  17. Weight Loss Expectations and Attrition in Treatment-Seeking Obese Women

    Directory of Open Access Journals (Sweden)

    Riccardo Dalle Grave

    2015-10-01

    Full Text Available Objective: The analysis of the relation between weight loss goals and attrition in the treatment of obesity has produced conflicting results. The aim of the present study was to investigate the role of weight loss goals on attrition in a cohort of obese women seeking treatment at 8 Italian medical centres. Methods: 634 women with obesity, consecutively enrolled in weight loss programmes, were included in the study. Weight loss goals were evaluated with the Goals and Relative Weights Questionnaire (GRWQ, reporting a sequence of unrealistic (‘dream' and ‘happy' and more realistic (‘acceptable' and ‘disappointing' weight loss goals. Attrition was assessed at 12 months on the basis of patients' medical records. Results: At 12 months, 205/634 patients (32.3% had interrupted their programme and were lost to follow-up. After adjustment for age, baseline weight, education and employment status, attrition was significantly associated with higher percent acceptable and disappointing weight loss targets, not with dream and happy weight loss. Conclusion: In ‘real world' clinical settings, only realistic expectations might favour attrition whenever too challenging, whereas unrealistic weight loss goals have no effect. Future studies should assess the effect of interventions aimed at coping with too challenging weight goals on attrition.

  18. Does Coordinated, Multidisciplinary Treatment Limit Medical Disability and Attrition Related to Spine Conditions in the US Navy?

    Science.gov (United States)

    Ziemke, Gregg; Campello, Marco; Hiebert, Rudi; Weiner, Shira Schecter; Rennix, Chris; Nordin, Margareta

    2015-09-01

    Musculoskeletal conditions account for the largest proportion of cases resulting in early separation from the US Navy. This study evaluates the impact of the Spine Team, a multidisciplinary care group that included physicians, physical therapists, and a clinical psychologist, for the treatment of active-duty service members with work-disabling, nonspecific low back pain at the Naval Medical Center, Portsmouth, VA, USA. We compared the impact of the introduction of the Spine Team in limiting disability and attrition from work-disabling spine conditions with the experience of the Naval Medical Center, San Diego, CA, USA, where there is no comparable spine team. Is a multidisciplinary spine team effective in limiting disability and attrition related to work-disabling spine conditions as compared with the current standard of care for US military active-duty service members? This is a retrospective, pre-/post-study with a separate, concurrent control group using administratively collected data from two large military medical centers during the period 2007 to 2009. In this study, disability is expressed as the proportion of active-duty service members seeking treatment for a work-disabling spine condition that results in the assignment of a first-career limited-duty status. Attrition is expressed as the proportion of individuals assigned a first-career limited-duty status for a work-disabling spine condition who were referred to a Physical Evaluation Board. We analyzed 667 individuals assigned a first-career limited-duty for a work-disabling spine condition between 2007 and 2009 who received care at the Naval Medical Center Portsmouth or Naval Medical Center San Diego. Rates of first-career limited-duty assignments for spine conditions decreased from 2007 to 2009 at both sites, but limited-duty rates decreased to a greater extent at the intervention site (Naval Medical Center Portsmouth; from 8.5 per 100 spine cases in 2007 to 5.1 per 100 cases in 2009, p Team was

  19. High-rate operant behavior in two mouse strains: a response-bout analysis.

    Science.gov (United States)

    Johnson, Joshua E; Pesek, Erin F; Newland, M Christopher

    2009-06-01

    Operant behavior sometimes occurs in bouts characterized by an initiation rate, within-bout response rate, and bout length. The generality of this structure was tested using high-rate nose-poking in mice. Reinforcement of short interresponse times produced high response rates while a random-interval schedule held reinforcement rates constant. BALB/c mice produced bouts that were more frequent, longer, and contained a higher within-bout rate of responding (nine nose-pokes/s) than did the C57BL/6 mice (five nose-pokes/s). Adding a running wheel decreased total nose-pokes and bout length, and increased bout-initiation rate. Free-feeding reduced nose-poking by decreasing bout-initiation rate. Photoperiod reversal decreased bout-initiation rate but not total nose-poke rate. Despite strain differences in bout structure, both strains responded similarly to the interventions. The three bout measures were correlated with overall rate but not with each other. Log-survival analyses provided independent descriptors of the structure of high-rate responding in these two strains.

  20. High frame rate retrospectively triggered Cine MRI for assessment of murine diastolic function.

    Science.gov (United States)

    Coolen, Bram F; Abdurrachim, Desiree; Motaal, Abdallah G; Nicolay, Klaas; Prompers, Jeanine J; Strijkers, Gustav J

    2013-03-01

    To assess left ventricular (LV) diastolic function in mice with Cine MRI, a high frame rate (>60 frames per cardiac cycle) is required. For conventional electrocardiography-triggered Cine MRI, the frame rate is inversely proportional to the pulse repetition time (TR). However, TR cannot be lowered at will to increase the frame rate because of gradient hardware, spatial resolution, and signal-to-noise limitations. To overcome these limitations associated with electrocardiography-triggered Cine MRI, in this paper, we introduce a retrospectively triggered Cine MRI protocol capable of producing high-resolution high frame rate Cine MRI of the mouse heart for addressing left ventricular diastolic function. Simulations were performed to investigate the influence of MRI sequence parameters and the k-space filling trajectory in relation to the desired number of frames per cardiac cycle. An optimized protocol was applied in vivo and compared with electrocardiography-triggered Cine for which a high-frame rate could only be achieved by several interleaved acquisitions. Retrospective high frame rate Cine MRI proved superior to the interleaved electrocardiography-triggered protocols. High spatial-resolution Cine movies with frames rates up to 80 frames per cardiac cycle were obtained in 25 min. Analysis of left ventricular filling rate curves allowed accurate determination of early and late filling rates and revealed subtle impairments in left ventricular diastolic function of diabetic mice in comparison with nondiabetic mice. Copyright © 2012 Wiley Periodicals, Inc.

  1. The role of plasma induced substrate heating during high rate deposition of microcrystalline solar cells

    NARCIS (Netherlands)

    van den Donker, M.N.; Schmitz, R.; Appenzeller, W.; Rech, B.; Kessels, W.M.M.; Sanden, van de M.C.M.

    2006-01-01

    A 13.56 MHz parallel plate hydrogen-dild. silane plasma, operated at high pressure and high power, was used to deposit microcryst. silicon solar cells with efficiencies of 6-9% at high deposition rates of 0.4-1.2 nm/s. In this regime new challenges arise regarding temp. control, since the high

  2. Tone Attrition in Mandarin Speakers of Varying English Proficiency

    Science.gov (United States)

    Creel, Sarah C.

    2017-01-01

    Purpose The purpose of this study was to determine whether the degree of dominance of Mandarin–English bilinguals' languages affects phonetic processing of tone content in their native language, Mandarin. Method We tested 72 Mandarin–English bilingual college students with a range of language-dominance profiles in the 2 languages and ages of acquisition of English. Participants viewed 2 photographs at a time while hearing a familiar Mandarin word referring to 1 photograph. The names of the 2 photographs diverged in tone, vowels, or both. Word recognition was evaluated using clicking accuracy, reaction times, and an online recognition measure (gaze) and was compared in the 3 conditions. Results Relative proficiency in English was correlated with reduced word recognition success in tone-disambiguated trials, but not in vowel-disambiguated trials, across all 3 dependent measures. This selective attrition for tone content emerged even though all bilinguals had learned Mandarin from birth. Lengthy experience with English thus weakened tone use. Conclusions This finding has implications for the question of the extent to which bilinguals' 2 phonetic systems interact. It suggests that bilinguals may not process pitch information language-specifically and that processing strategies from the dominant language may affect phonetic processing in the nondominant language—even when the latter was learned natively. PMID:28124064

  3. Influence of Cooling Rate in High-Temperature Area on Hardening of Deposited High-Cutting Chrome-Tungsten Metal

    International Nuclear Information System (INIS)

    Malushin, N N; Valuev, D V; Valueva, A V; Serikbol, A; Borovikov, I F

    2015-01-01

    The authors study the influence of cooling rate in high-temperature area for thermal cycle of high-cutting chrome-tungsten metal weld deposit on the processes of carbide phase merging and austenite grain growth for the purpose of providing high hardness of deposited metal (HRC 64-66). (paper)

  4. Influence of Cooling Rate in High-Temperature Area on Hardening of Deposited High-Cutting Chrome-Tungsten Metal

    OpenAIRE

    Malushin, N. N.; Valuev, Denis Viktorovich; Valueva, Anna Vladimirovna; Serikbol, A.; Borovikov, I. F.

    2015-01-01

    The authors study the influence of cooling rate in high-temperature area for thermal cycle of high-cutting chrome-tungsten metal weld deposit on the processes of carbide phase merging and austenite grain growth for the purpose of providing high hardness of deposited metal (HRC 64-66).

  5. High dose rate (HDR) and low dose rate (LDR) interstitial irradiation (IRT) of the rat spinal cord

    International Nuclear Information System (INIS)

    Pop, Lucas A.M.; Plas, Mirjam van der; Skwarchuk, Mark W.; Hanssen, Alex E.J.; Kogel, Albert J. van der

    1997-01-01

    Purpose: To describe a newly developed technique to study radiation tolerance of rat spinal cord to continuous interstitial irradiation (IRT) at different dose rates. Material and methods: Two parallel catheters are inserted just laterally on each side of the vertebral bodies from the level of Th 10 to L 4 . These catheters are afterloaded with two 192 Ir wires of 4 cm length each (activity 1-2.3 mCi/cm) for the low dose rate (LDR) IRT or connected to the HDR micro-Selectron for the high dose rate (HDR) IRT. Spinal cord target volume is located at the level of Th 12 -L 2 . Due to the rapid dose fall-off around the implanted sources, a dose inhomogeneity across the spinal cord thickness is obtained in the dorso-ventral direction. Using the 100% reference dose (rate) at the ventral side of the spinal cord to prescribe the dose, experiments have been carried out to obtain complete dose response curves at average dose rates of 0.49, 0.96 and 120 Gy/h. Paralysis of the hind-legs after 5-6 months and histopathological examination of the spinal cord of each irradiated rat are used as experimental endpoints. Results: The histopathological damage seen after irradiation is clearly reflected the inhomogeneous dose distribution around the implanted catheters, with the damage predominantly located in the dorsal tract of the cord or dorsal roots. With each reduction in average dose rate, spinal cord radiation tolerance is significantly increased. When the dose is prescribed at the 100% reference dose rate, the ED 50 (induction of paresis in 50% of the animals) for the HDR-IRT is 17.3 Gy. If the average dose rate is reduced from 120 Gy/h to 0.96 or 0.49 Gy/h, a 2.9- or 4.7-fold increase in the ED 50 values to 50.3 Gy and 80.9 Gy is observed; for the dose prescribed at the 150% reference dose rate (dorsal side of cord) ED 50 values are 26.0, 75.5 and 121.4 Gy, respectively. Using different types of analysis and in dependence of the dose prescription and reference dose rate, the

  6. Microstructural evolution at high strain rates in solution-hardened interstitial free steels

    International Nuclear Information System (INIS)

    Uenishi, A.; Teodosiu, C.; Nesterova, E.V.

    2005-01-01

    Comprehensive transmission electron microscopical studies have been conducted for solution-hardened steels deformed at high (1000 s -1 ) and low (0.001 s -1 ) strain rates, in order to clarify the effects of strain rate and a jump in strain rate on the evolution of the microstructure and its connection with the mechanical response. It was revealed that the various types of microstructure, observed even within the same specimen, depend on the corresponding grain orientations and their evolution with progressive deformation depends on these microstructure types. At high strain rates, the dislocation density increases especially at low strains and the onset of dislocation organization is delayed. A jump in strain rate causes an increase of the dislocation density inside an organized structure. These results corroborated the mechanical behaviour at high strain rates after compensation for the cross-sectional reduction and temperature increase. The higher work-hardening rate at high strain rates could be connected to a delay in the dislocation organization. The high work-hardening rate just after a jump could be due to an increase of the density of dislocations distributed uniformly inside an organized structure

  7. Cost minimization analysis of high-dose-rate versus low-dose-rate brachytherapy in endometrial cancer

    International Nuclear Information System (INIS)

    Pinilla, James

    1998-01-01

    Purpose: Endometrial cancer is a common, usually curable malignancy whose treatment frequently involves low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy. These treatments involve substantial resource commitments and this is increasingly important. This paper presents a cost minimization analysis of HDR versus LDR brachytherapy in the treatment of endometrial cancer. Methods and Materials: The perspective of the analysis is that of the payor, in this case the Ministry of Health. One course of LDR treatment is compared to two courses of HDR treatment. The two alternatives are considered to be comparable with respect to local control, survival, and toxicities. Labor, overhead, and capital costs are accounted for and carefully measured. A 5% inflation rate is used where applicable. A univariate sensitivity analysis is performed. Results: The HDR regime is 22% less expensive compared to the LDR regime. This is $991.66 per patient or, based on the current workload of this department (30 patients per year) over the useful lifetime of the after loader, $297,498 over 10 years in 1997 dollars. Conclusion: HDR brachytherapy minimizes costs in the treatment of endometrial cancer relative to LDR brachytherapy. These results may be used by other centers to make rational decisions regarding brachytherapy equipment replacement or acquisition

  8. Increased effects of machining damage in beryllium observed at high strain rates

    International Nuclear Information System (INIS)

    Beitscher, S.; Brewer, A.W.; Corle, R.R.

    1980-01-01

    Tensile tests at both low and high strain rates, and also impact shear tests, were performed on a weldable grade powder-source beryllium. Impact energies increased by a factor of 2 to 3 from the as-machined level after etching or annealing. Similar increases in the ductility from machining damage removal were observed from the tensile data at the higher strain rate (10 s -1 ) while an insignificant increase in elongation was measured at the lower strain rate (10 -4 s -1 ). High strain-rate tests appear to be more sensitive and reliable for evaluating machining practice and damage removal methods for beryllium components subjected to sudden loads. 2 tables

  9. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    DEFF Research Database (Denmark)

    Blucher, J.T.; Knudsen, Per; Grant, N.J.

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with decre......Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

  10. Transperineal high-dose-rate interstitial radiation therapy in the management of gynecologic malignancies

    Energy Technology Data Exchange (ETDEWEB)

    Itami, Jun; Hara, Ryuseke; Kozuka, Takuyou; Yamashita, Hideomi; Nakajima, Kaori; Shibata, Kouji; Abe, Yoshihisa; Fuse, Masashi; Ito, Masashi [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy and Oncology

    2003-11-01

    Background: High-dose-rate interstitial radiation therapy is a newly introduced modality, and its role in the management of gynecologic malignancies remains to be studied. Clinical experience in high-dose-rate interstitial radiation therapy was retrospectively investigated. Patients and Methods: Eight patients with primary and nine with recurrent gynecologic malignancies underwent high-dose-rate interstitial radiation therapy with/without external-beam irradiation. Fractional dose of the high-dose-rate interstitial radiation therapy ranged between 4 and 6 Gy with total doses of 15-54 Gy. Interstitial irradiation was performed twice daily with an interval of > 6 h. Results: 2-year local control rate was 75% for primary treatment and 47% for treatment of recurrence (p = 0.46). Maximum tumor size had a statistically significant impact on local control (p < 0.002). Grade 2 and 4 late complications were seen in five patients, and the incidence was significantly higher in patients with a larger volume enclosed by the prescribed fractional dose of high-dose-rate interstitial radiation therapy. The incidence of grade 2 and 4 complications at 18 months was 78% and 0% with a volume > 100 cm{sup 3} and {<=} 100 cm{sup 3}, respectively (p < 0.04). Conclusion: Although high-dose-rate interstitial radiation therapy is a promising modality, it must be applied cautiously to patients with bulky tumors because of the high incidence of serious complications. (orig.)

  11. Genotoxic effects of high dose rate X-ray and low dose rate gamma radiation in ApcMin/+ mice.

    Science.gov (United States)

    Graupner, Anne; Eide, Dag M; Brede, Dag A; Ellender, Michele; Lindbo Hansen, Elisabeth; Oughton, Deborah H; Bouffler, Simon D; Brunborg, Gunnar; Olsen, Ann Karin

    2017-10-01

    Risk estimates for radiation-induced cancer in humans are based on epidemiological data largely drawn from the Japanese atomic bomb survivor studies, which received an acute high dose rate (HDR) ionising radiation. Limited knowledge exists about the effects of chronic low dose rate (LDR) exposure, particularly with respect to the application of the dose and dose rate effectiveness factor. As part of a study to investigate the development of colon cancer following chronic LDR vs. acute HDR radiation, this study presents the results of genotoxic effects in blood of exposed mice. CBAB6 F1 Apc +/+ (wild type) and Apc Min/+ mice were chronically exposed to estimated whole body absorbed doses of 1.7 or 3.2 Gy 60 Co-γ-rays at a LDR (2.2 mGy h -1 ) or acutely exposed to 2.6 Gy HDR X-rays (1.3 Gy min -1 ). Genotoxic endpoints assessed in blood included chromosomal damage (flow cytometry based micronuclei (MN) assay), mutation analyses (Pig-a gene mutation assay), and levels of DNA lesions (Comet assay, single-strand breaks (ssb), alkali labile sites (als), oxidized DNA bases). Ionising radiation (ca. 3 Gy) induced genotoxic effects dependent on the dose rate. Chromosomal aberrations (MN assay) increased 3- and 10-fold after chronic LDR and acute HDR, respectively. Phenotypic mutation frequencies as well as DNA lesions (ssb/als) were modulated after acute HDR but not after chronic LDR. The Apc Min/+ genotype did not influence the outcome in any of the investigated endpoints. The results herein will add to the scant data available on genotoxic effects following chronic LDR of ionising radiation. Environ. Mol. Mutagen. 58:560-569, 2017. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

  12. High-Rate Fast-Time GRPC for the high eta CMS muon detectors

    CERN Document Server

    Mirabito, Laurent

    2016-01-01

    CMS detector. In their single-gap version we will show that they can stand rates of few ${\\rm kHz/cm}^2$. We also demonstrate that using multi-gap glass RPC, a time resolution of about 60 ps is achieved.

  13. High and highly variable cooling rates during pyroclastic eruptions on Axial Seamount, Juan de Fuca Ridge

    Science.gov (United States)

    Helo, Christoph; Clague, David A.; Dingwell, Donald B.; Stix, John

    2013-03-01

    We present a calorimetric analysis of pyroclastic glasses and glassy sheet lava flow crusts collected on Axial Seamount, Juan de Fuca Ridge, NE Pacific Ocean, at a water depth of about 1400 m. The pyroclastic glasses, subdivided into thin limu o Pele fragments and angular, blocky clasts, were retrieved from various stratigraphic horizons of volcaniclastic deposits on the upper flanks of the volcanic edifice. Each analysed pyroclastic sample consists of a single type of fragment from one individual horizon. The heat capacity (cp) was measured via differential scanning calorimetry (DSC) and analysed using relaxation geospeedometry to obtain the natural cooling rate across the glass transition. The limu o Pele samples (1 mm grain size fraction) and angular fragments (0.5 mm grain size fraction) exhibit cooling rates of 104.3 to 106.0 K s- 1 and 103.9 to 105.1 K s- 1, respectively. A coarser grain size fraction, 2 mm for limu o Pele and 1 mm for the angular clasts yields cooling rates at the order of 103.7 K s- 1. The range of cooling rates determined for the different pyroclastic deposits presumably relates to the size or intensity of the individual eruptions. The outer glassy crusts of the sheet lava flows were naturally quenched at rates between 63 K s- 1 and 103 K s- 1. By comparing our results with published data on the very slow quenching of lava flow crusts, we suggest that (1) fragmentation and cooling appear to be coupled dynamically and (2) ductile deformation upon the onset of cooling is restricted due to the rapid increase in viscosity. Lastly, we suggest that thermally buoyant plumes that may arise from rapid heat transfer efficiently separate clasts based on their capability to rise within the plume and as they subsequently settle from it.

  14. The impact of assay technology as applied to safety assessment in reducing compound attrition in drug discovery.

    Science.gov (United States)

    Thomas, Craig E; Will, Yvonne

    2012-02-01

    Attrition in the drug industry due to safety findings remains high and requires a shift in the current safety testing paradigm. Many companies are now positioning safety assessment at each stage of the drug development process, including discovery, where an early perspective on potential safety issues is sought, often at chemical scaffold level, using a variety of emerging technologies. Given the lengthy development time frames of drugs in the pharmaceutical industry, the authors believe that the impact of new technologies on attrition is best measured as a function of the quality and timeliness of candidate compounds entering development. The authors provide an overview of in silico and in vitro models, as well as more complex approaches such as 'omics,' and where they are best positioned within the drug discovery process. It is important to take away that not all technologies should be applied to all projects. Technologies vary widely in their validation state, throughput and cost. A thoughtful combination of validated and emerging technologies is crucial in identifying the most promising candidates to move to proof-of-concept testing in humans. In spite of the challenges inherent in applying new technologies to drug discovery, the successes and recognition that we cannot continue to rely on safety assessment practices used for decades have led to rather dramatic strategy shifts and fostered partnerships across government agencies and industry. We are optimistic that these efforts will ultimately benefit patients by delivering effective and safe medications in a timely fashion.

  15. Achieving high mobility ZnO : Al at very high growth rates by dc filtered cathodic arc deposition

    International Nuclear Information System (INIS)

    Mendelsberg, R J; Lim, S H N; Wallig, J; Anders, A; Zhu, Y K; Milliron, D J

    2011-01-01

    Achieving a high growth rate is paramount for making large-area transparent conducting oxide coatings at a low cost. Unfortunately, the quality of thin films grown by most techniques degrades as the growth rate increases. Filtered dc cathodic arc is a lesser known technique which produces a stream of highly ionized plasma, in stark contrast to the neutral atoms produced by standard sputter sources. Ions bring a large amount of potential energy to the growing surface which is in the form of heat, not momentum. By minimizing the distance from cathode to substrate, the high ion flux gives a very high effective growth temperature near the film surface without causing damage from bombardment. The high surface temperature is a direct consequence of the high growth rate and allows for high-quality crystal growth. Using this technique, 500-1300 nm thick and highly transparent ZnO : Al films were grown on glass at rates exceeding 250 nm min -1 while maintaining resistivity below 5 x 10 -4 Ω cm with electron mobility as high as 60 cm 2 V -1 s -1 . (fast track communication)

  16. The Relationships among the Fine Arts, School Culture, and High School Graduation Rates in Georgia

    Science.gov (United States)

    Lovett, Andrew, Jr.

    2014-01-01

    High school graduation is the single largest hurdle that students must achieve to prepare for college and career (National Governor's Association, 2011). Fleischman & Heppen (2009) agree that American high schools must address the problem of declining graduation rate. Approximately 1.28 million students drop out of high school annually (Amos,…

  17. High speed and adaptable error correction for megabit/s rate quantum key distribution.

    Science.gov (United States)

    Dixon, A R; Sato, H

    2014-12-02

    Quantum Key Distribution is moving from its theoretical foundation of unconditional security to rapidly approaching real world installations. A significant part of this move is the orders of magnitude increases in the rate at which secure key bits are distributed. However, these advances have mostly been confined to the physical hardware stage of QKD, with software post-processing often being unable to support the high raw bit rates. In a complete implementation this leads to a bottleneck limiting the final secure key rate of the system unnecessarily. Here we report details of equally high rate error correction which is further adaptable to maximise the secure key rate under a range of different operating conditions. The error correction is implemented both in CPU and GPU using a bi-directional LDPC approach and can provide 90-94% of the ideal secure key rate over all fibre distances from 0-80 km.

  18. Behavior of quenched and tempered steels under high strain rate compression loading

    International Nuclear Information System (INIS)

    Meyer, L.W.; Seifert, K.; Abdel-Malek, S.

    1997-01-01

    Two quenched and tempered steels were tested under compression loading at strain rates of ε = 2.10 2 s -1 and ε = 2.10 3 s -1 . By applying the thermal activation theory, the flow stress at very high strain rates of 10 5 to 10 6 s -1 is derived from low temperature and high strain rate tests. Dynamic true stress - true strain behaviour presents, that stress increases with increasing strain until a maximum, then it decreases. Because of the adiabatic process under dynamic loading the maximum flow stress will occur at a lower strain if the strain rate is increased. Considering strain rate, strain hardening, strain rate hardening and strain softening, a constitutive equation with different additive terms is successfully used to describe the behaviour of material under dynamic compression loading. Results are compared with other models of constitutive equations. (orig.)

  19. Activated carbon derived from melaleuca barks for outstanding high-rate supercapacitors

    Science.gov (United States)

    Luo, Qiu-Ping; Huang, Liang; Gao, Xiang; Cheng, Yongliang; Yao, Bin; Hu, Zhimi; Wan, Jun; Xiao, Xu; Zhou, Jun

    2015-07-01

    Activated carbon (AC) was prepared via carbonizing melaleuca bark in an argon atmosphere at 600 °C followed with KOH activation for high-rate supercapacitors. This AC electrode has a high capacitance of 233 F g-1 at a scan rate of 2 mV s-1 and an excellent rate capability of ˜80% when increasing the sweep rate from 2 to 500 mV s-1. The symmetric supercapacitor assembled by the above electrode can deliver a high energy density of 4.2 Wh kg-1 with a power density of 1500 W kg-1 when operated in the voltage range of 0-1 V in 1 M H2SO4 aqueous electrolyte while maintaining great cycling stability (less than 5% capacitance loss after 10 000 cycles at sweep rate of 100 mV s-1). All the outstanding electrochemical performances make this AC electrode a promising candidate for potential energy storage application.

  20. Generation of µW level plateau harmonics at high repetition rate.

    Science.gov (United States)

    Hädrich, S; Krebs, M; Rothhardt, J; Carstens, H; Demmler, S; Limpert, J; Tünnermann, A

    2011-09-26

    The process of high harmonic generation allows for coherent transfer of infrared laser light to the extreme ultraviolet spectral range opening a variety of applications. The low conversion efficiency of this process calls for optimization or higher repetition rate intense ultrashort pulse lasers. Here we present state-of-the-art fiber laser systems for the generation of high harmonics up to 1 MHz repetition rate. We perform measurements of the average power with a calibrated spectrometer and achieved µW harmonics between 45 nm and 61 nm (H23-H17) at a repetition rate of 50 kHz. Additionally, we show the potential for few-cycle pulses at high average power and repetition rate that may enable water-window harmonics at unprecedented repetition rate. © 2011 Optical Society of America