Science.gov

Sample records for surviving tough times

  1. Lessons from Cacti: How to Survive the Prickles of Life during Tough Times

    ERIC Educational Resources Information Center

    Bigger, Alan S.; Bigger, Linda B.

    2009-01-01

    The saguaro cactus looked a little like humans, in different shapes and sizes. How on earth do they survive in a climate that seems so inhospitable? It is possible to learn lessons for life from a cactus, if one can only get beyond the thorns, and that these lessons will assist one to survive during tough or prickly times. These plants survive…

  2. Tough Questions for Tough Times

    ERIC Educational Resources Information Center

    Parrett, William; Budge, Kathleen

    2009-01-01

    Six high-performing/high-poverty schools provide insights into what it takes to make a dramatic turnaround. School leaders had to make tough calls--and many of those decisions were about how to use resources. The budget in a high-performing, high-poverty school is a moral document, reflective of the school's beliefs about the conditions necessary…

  3. Four Takes on Tough Times

    ERIC Educational Resources Information Center

    Rebell, Michael A.; Odden, Allan; Rolle, Anthony; Guthrie, James W.

    2012-01-01

    Educational Leadership talks with four experts in the fields of education policy and finance about how schools can weather the current financial crisis. Michael A. Rebell focuses on the recession and students' rights; Allan Odden suggests five steps schools can take to improve in tough times; Anthony Rolle describes the tension between equity and…

  4. Refinery suppliers face tough times

    SciTech Connect

    Rotman, D.; Walsh, K.

    1997-03-12

    Despite a handful of bright spots in hydroprocessing and petrochemical sectors, economic woes plague much of the refinery and petrochemical catalysts business, as suppliers are feeling the impact of mature markets and refiners` ongoing cost cutting. Industry experts say the doldrums could spur further restructuring in the catalyst business, with suppliers scrambling for market share and jockeying for position in growing sectors. Expect further consolidation over the next several years, says Pierre Bonnifay, president of IFP Enterprises (New York). {open_quotes}There are still too many players for the mature [refinery catalyst] markets.{close_quotes} Others agree. {open_quotes}Only about seven [or] eight major suppliers will survive,{close_quotes} says Robert Allsmiller, v.p./refinery and petrochemical catalysts at United Catalysts Inc. (UCI; Louisville, KY). {open_quotes}Who they [will be] is still up in the air.{close_quotes}

  5. Staying Motivated During Tough Times

    NASA Technical Reports Server (NTRS)

    Cole, Jennifer H.

    2008-01-01

    This paper describes the problem of team motivation on a project. Our team was working with the Department of Homeland Security (DHS). The task consisted of figuring out how to safely control and land an airliner using just the thrust from the engines. This is called Throttles-Only Control (TOC). We weren't allowed to modify the airliner in any way, given the time and cost involved, and we had to use a stock airliner with line pilots. The idea was to give the pilots an emergency checklist which would provide them with the most useful information in the shortest time to learn how to fly TOC. The DHS Program office that was supporting us had its funding redirected, due to new priorities. The process of staying motivated for finishing as much of the project as possible is described.

  6. Surviving Tough Times: From Administrative Reorganizations to Finding New Streams of Revenue, Some Historically Black Colleges and Universities Are Determined to Stay Afloat

    ERIC Educational Resources Information Center

    Powell, Tracie

    2004-01-01

    Overall, historically Black colleges and universities' compassionate and noble mission of educating and nurturing young African American minds has not changed over the years, but leaders at Black campuses are now increasingly having to temper that with tough business decisions. Streamlining, attracting executive leadership and finding new revenue…

  7. Survivability Versus Time

    NASA Technical Reports Server (NTRS)

    Joyner, James J., Sr.

    2014-01-01

    Develop Survivability vs Time Model as a decision-evaluation tool to assess various emergency egress methods used at Launch Complex 39B (LC 39B) and in the Vehicle Assembly Building (VAB) on NASAs Kennedy Space Center. For each hazard scenario, develop probability distributions to address statistical uncertainty resulting in survivability plots over time and composite survivability plots encompassing multiple hazard scenarios.

  8. Sharing Ideas: Tough Times Encourage Colleges to Collaborate

    ERIC Educational Resources Information Center

    Fain, Paul; Blumenstyk, Goldie; Sander, Libby

    2009-01-01

    Tough times are encouraging colleges to share resources in a variety of areas, including campus security, research, and degree programs. Despite its veneer of cooperation, higher education is a competitive industry, where resource sharing is eyed warily. But the recession is chipping away at that reluctance, and institutions are pursuing…

  9. Tough Times: Strategic Planning as a War Canoe

    ERIC Educational Resources Information Center

    Seymour, Daniel

    2011-01-01

    In this article, the author discusses how to make strategic planning a more valuable tool for higher education in today's tough times. Strategic planning is really the answer to five straightforward questions. The first three represent the plan itself, while the last two are what makes the plan vital and dynamic: (1) Why do we exist?; (2) What do…

  10. Professional Development in Tough Financial Times

    ERIC Educational Resources Information Center

    Gandel, Paul B.; Golden, Cynthia

    2004-01-01

    The authors asked a diverse cross-section of their colleagues how they were addressing professional development in tight economic times, when they are all being asked to work more effectively across organizational boundaries. While the survey was informal and not scientific, the authors found that many organizations have maintained strong…

  11. The effect of magnetic field intensity and treatment time on graphene / epoxy composites’ fracture toughness

    NASA Astrophysics Data System (ADS)

    Tian, Z. Q.; Zhang, L.; Fu, S.; Yuan, R. H.; Dong, Z. W.; Ren, X. M.

    2016-07-01

    The effect of the intensity of the magnetic field and the treatment time on the fracture toughness of graphene/epoxy composites is researched. Also, the mechanism of the effect of the magnetic field on the fracture toughness of graphene/epoxy composites and a method to improve the impact resistance is explored. Then, three-point bending tests are employed to characterize the fracture toughness of graphene/epoxy composite. The results show that the intervention of magnetic field could induce GNS to generated orientation arrangement, improving the fracture toughness of the graphene/epoxy composite. When the intensity of the magnetic field was increased, the growth rate of the fracture toughness slowed. However, when 2T magnetic was used to synthetically process the material, and when the processing time was less than 50 min, the fracture toughness of the composite material increased significantly.

  12. Surviving Tight Times.

    ERIC Educational Resources Information Center

    Neugebauer, Roger

    2002-01-01

    Discusses several strategies recommended by small business experts to help for-profit and non-profit child care centers survive a financial crisis. Strategies include: identifying the source of the problem, monitoring cash flow, reducing or deferring expenditures, expediting regular income and exploring new sources of income, patiently working…

  13. Tough Choices or Tough Times: Bolder Steps for Education Philanthropy? Notes and Resources from the GFE Foundation Leaders Institute (Tamaya, New Mexico, October 19, 2007)

    ERIC Educational Resources Information Center

    Mackinnon, Anne

    2007-01-01

    In late 2006, the National Center on Education and the Economy released "Tough Choices or Tough Times: The Report of the New Commission on the Skills of the American Workforce." With compelling language, the report updated and sharpened the findings of the center's influential 1990 report, "America's Choice: High Skills or Low Wages," which called…

  14. Probabilistic Survivability Versus Time Modeling

    NASA Technical Reports Server (NTRS)

    Joyner, James J., Sr.

    2015-01-01

    This technical paper documents Kennedy Space Centers Independent Assessment team work completed on three assessments for the Ground Systems Development and Operations (GSDO) Program to assist the Chief Safety and Mission Assurance Officer (CSO) and GSDO management during key programmatic reviews. The assessments provided the GSDO Program with an analysis of how egress time affects the likelihood of astronaut and worker survival during an emergency. For each assessment, the team developed probability distributions for hazard scenarios to address statistical uncertainty, resulting in survivability plots over time. The first assessment developed a mathematical model of probabilistic survivability versus time to reach a safe location using an ideal Emergency Egress System at Launch Complex 39B (LC-39B); the second used the first model to evaluate and compare various egress systems under consideration at LC-39B. The third used a modified LC-39B model to determine if a specific hazard decreased survivability more rapidly than other events during flight hardware processing in Kennedys Vehicle Assembly Building (VAB).Based on the composite survivability versus time graphs from the first two assessments, there was a soft knee in the Figure of Merit graphs at eight minutes (ten minutes after egress ordered). Thus, the graphs illustrated to the decision makers that the final emergency egress design selected should have the capability of transporting the flight crew from the top of LC 39B to a safe location in eight minutes or less. Results for the third assessment were dominated by hazards that were classified as instantaneous in nature (e.g. stacking mishaps) and therefore had no effect on survivability vs time to egress the VAB. VAB emergency scenarios that degraded over time (e.g. fire) produced survivability vs time graphs that were line with aerospace industry norms.

  15. Mental Toughness Moderates Social Loafing in Cycle Time-Trial Performance

    ERIC Educational Resources Information Center

    Haugen, Tommy; Reinboth, Michael; Hetlelid, Ken J.; Peters, Derek M.; Høigaard, Rune

    2016-01-01

    Purpose: The purpose of this study was to determine if mental toughness moderated the occurrence of social loafing in cycle time-trial performance. Method: Twenty-seven men (M[subscript age] = 17.7 years, SD = 0.6) completed the Sport Mental Toughness Questionnaire prior to completing a 1-min cycling trial under 2 conditions: once with individual…

  16. Helping States, Helping Students: Improving Education in Tough Times. 2011 Annual Report

    ERIC Educational Resources Information Center

    Southern Regional Education Board (SREB), 2011

    2011-01-01

    The 2011 Southern Regional Education Board annual report describes SREB's recent achievements and how the organization has helped its 16 member states improve education in tough economic times. The report highlights program activities and also includes remarks from the Board Chair and President, acknowledgment of financial contributors, and lists…

  17. The Frugal Librarian: Thriving in Tough Economic Times

    ERIC Educational Resources Information Center

    Smallwood, Carol, Ed.

    2011-01-01

    Fewer employees, shorter hours, diminished collection budgets, reduced programs and services--all at a time of record library usage. In this book, library expert Carol Smallwood demonstrates that despite the obvious downsides, the necessity of doing business differently can be positive, leading to partnering, sharing, and innovating. This…

  18. Leveraging Resources and Sustaining Partnerships in Tough Economic Times

    ERIC Educational Resources Information Center

    Booth, Cheryl N.; Vaidya, Shruti J.; Farrell, Patricia A.; Bokemeier, Janet L.

    2004-01-01

    During times of economic uncertainty, how can universities develop and sustain resources for engagement efforts? This article focuses on how a university-wide research and outreach coalition at Michigan State University called Families and Communities Together (FACT) is exploring a variety of funding approaches and implementing successful…

  19. Collection Development "Personal Finance": Thrift for Tough Times

    ERIC Educational Resources Information Center

    Heckman, Lucy

    2009-01-01

    The current economic crisis has naturally reached into one's pocket and made many people anxious about their own finances. As consumers ride out these treacherous times, where can they go to find advice on managing and paying down their debt, protecting their investments, incomes, and retirement plans, and applying for mortgages in a tight credit…

  20. Linking age, survival, and transit time distributions

    NASA Astrophysics Data System (ADS)

    Calabrese, Salvatore; Porporato, Amilcare

    2015-10-01

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

  1. A snapshot in the effect of time of day on herbage toughness and chemical composition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Herbage chemical composition varies diurnally; however, it is not known if this variation affects herbage biomechanical properties. The objective of this study was to evaluate potential changes in herbage toughness and particle size reduction index (PSR) in relation to diurnal fluctuations of herbag...

  2. Predicting survival time for cold exposure

    NASA Astrophysics Data System (ADS)

    Tikuisis, Peter

    1995-06-01

    The prediction of survival time (ST) for cold exposure is speculative as reliable controlled data of deep hypothermia are unavailable. At best, guidance can be obtained from case histories of accidental exposure. This study describes the development of a mathematical model for the prediction of ST under sedentary conditions in the cold. The model is based on steady-state heat conduction in a single cylinder comprised of a core and two concentric annular shells representing the fat plus skin and the clothing plus still boundary layer, respectively. The ambient condition can be either air or water; the distinction is made by assigning different values of insulation to the still boundary layer. Metabolic heat production ( M) is comprised of resting and shivering components with the latter predicted by temperature signals from the core and skin. Where the cold exposure is too severe for M to balance heat loss, ST is largely determined by the rate of heat loss from the body. Where a balance occurs, ST is governed by the endurance time for shivering. End of survival is marked by the deep core temperature reaching a value of 30° C. The model was calibrated against survival data of cold water (0 to 20° C) immersion and then applied to cold air exposure. A sampling of ST predictions for the nude exposure of an average healthy male in relatively calm air (1 km/h wind speed) are the following: 1.8, 2.5, 4.1, 9.0, and >24 h for -30, -20, -10, 0, and 10° C, respectively. With two layers of loose clothing (average thickness of 1 mm each) in a 5 km/h wind, STs are 4.0, 5.6, 8.6, 15.4, and >24 h for -50, -40, -30, -20, and -10° C. The predicted STs must be weighted against the extrapolative nature of the model. At present, it would be prudent to use the predictions in a relative sense, that is, to compare or rank-order predicted STs for various combinations of ambient conditions and clothing protection.

  3. Improved survival time trends in Hodgkin's lymphoma.

    PubMed

    Koshy, Matthew; Fairchild, Andrew; Son, Christina H; Mahmood, Usama

    2016-06-01

    There have been dramatic changes in the staging and treatment of Hodgkin's lymphoma (HL) over the past 30 years. We undertook this study to determine if a stage migration had occurred and also examined if treatment associated with later years has improved survival. Patients with stage I-IV HL between 1983 and 2011 were selected from the Surveillance, Epidemiology, and End Results database. Multivariable analysis (MVA) was performed using Cox proportional hazards modeling. The study cohort included 35,680 patients. The stage breakdown in 1983 according to A and B symptoms was follows: 18%, 21%, 12%, and 5% for stage IA, IIA, IIIA, and IVA disease, respectively, and 6%, 11%, 12%, and 15% for stage IB, IIB, IIIB, and IVB disease. The stage breakdown in 2011 according to A and B symptoms was follows: 9%, 29%, 10%, and 6% for stage IA, IIA, IIIA, and IVA disease, respectively, and 4%, 16%, 12%, and 13% for stage IB, IIB, IIIB, and IVB disease. The median follow-up for the entire cohort is 6.1 years. On MVA, the HR for mortality of patients diagnosed in 2006 was 0.60 (95% Confidence Interval (CI): 0.52-0.70) compared to 1983. For stage I and II patients diagnosed in 2006 the HR was 0.62 (95% CI: 0.44-0.87) and 0.40 (95% CI: 0.30-0.55), respectively, compared to patients diagnosed in 1983. For stage III and IV patients diagnosed in 2006 the HR was 0.72 (95% CI: 0.53-0.98) and 0.74 (95% CI: 0.56-0.99), respectively, compared to patients diagnosed in 1983. This is the first study to demonstrate a significant stage migration in early stage Hodgkin's lymphoma. Furthermore, these results demonstrate an improvement in survival over time for patients with Hodgkin's lymphoma which was particularly notable for those with early stage disease.

  4. Operative timing and patient survival following distal splenorenal shunt.

    PubMed

    Pomerantz, R A; Eckhauser, F E; Knol, J A; Guirre, K; Raper, S E; Turcotte, J G

    1989-06-01

    The importance of "operative timing" in cirrhotic patients with variceal hemorrhage is often underemphasized. To evaluate the effects of immediate versus delayed selective portasystemic decompression on hepatic function, operative mortality, and long-term patient survival, we reviewed the records of 77 patients who underwent distal splenorenal shunts (DSRS) over a 14-year period. A hepatic risk status score was calculated at the time of the index bleed (HRS1) or presentation and again just prior to operation (HRS2). Variables analyzed included age, sex, prior bleeding episodes, time from index bleed to operation, transfusion requirements, and etiology of cirrhosis. Operative mortality rates for immediate versus delayed DSRS were 46.2 per cent and 17 per cent, respectively. HRS improved significantly in elective DSRS patients from 1.46 to 1.30. Predictors of HRS2 included HRS1 and time in days from the index bleed to operation. The most important predictor of early survival for all patients after elective DSRS was the HRS2; however, for patients who underwent elective DSRS and survived, HRS1 was a better predictor of length of survival than HRS2. No other variable analyzed accurately predicted survival. We conclude that HRS can be expected to improve with supportive inhospital therapy; improved HRS at the time of operation is associated with decreased operative mortality; and the extent of liver disease as determined by HRS1 appears to be the chief determinant of long-term patient survival.

  5. A Note on Standard Errors for Survival Curves in Discrete-Time Survival Analysis

    ERIC Educational Resources Information Center

    Zwick, Rebecca; Sklar, Jeffrey C.

    2005-01-01

    Cox (1972) proposed a discrete-time survival model that is somewhat analogous to the proportional hazards model for continuous time. Efron (1988) showed that this model can be estimated using ordinary logistic regression software, and Singer and Willett (1993) provided a detailed illustration of a particularly flexible form of the model that…

  6. Transformation or Decline? Using Tough Times to Create Higher-Performing Schools

    ERIC Educational Resources Information Center

    Miles, Karen Hawley

    2011-01-01

    Instead of doing less with less during these fiscally challenging times, school districts can seize the moment to usher in school transformation that will leave the schools, families, and communities better off. They could follow the lead of districts such as Baltimore City, Syracuse, and Charlotte-Mecklenburg to think outside traditional cost…

  7. Indiana Emergent Bilingual Student Time to Reclassification: A Survival Analysis

    ERIC Educational Resources Information Center

    Burke, April M.; Morita-Mullaney, Trish; Singh, Malkeet

    2016-01-01

    In this study, we employed a discrete-time survival analysis model to examine Indiana emergent bilingual time to reclassification as fluent English proficient. The data consisted of five years of statewide English language proficiency scores. Indiana has a large and rapidly growing Spanish-speaking emergent bilingual population, and these students…

  8. Triumph in Tough Times

    ERIC Educational Resources Information Center

    Ponder, Anne

    2009-01-01

    The downturn in the economy of the author's state, North Carolina, so far is less severe than that of much of the rest of the nation, due to their diversified economy, financial discipline, constitutional mandate for a balanced budget, "rainy day" fund, and many years of consistent investment in higher education. In the University of…

  9. Survival times of pre-1950 US women radium dial workers

    SciTech Connect

    Stehney, A.F.

    1994-05-01

    Survival times of US women radium dial workers to the end of 1989 were examined by life table methods. Included were 1301 women rust employed before 1930 and 1242 first employed in 1930-1949. Expected numbers of deaths were estimated from age- and time-specific death rates for US white females. In the early group, 85 deaths from the well-known radium-induced cancers - bone sarcomas and head carcinomas - were observed, but only 724 deaths from aH other causes were observed vs 755 expected. Life shortening ({plus_minus}S.E.) of 1.8 {plus_minus}0.5 y compared to the general population of US white females was calculated from the time distribution of all deaths in the pre-1930 group. In the 1930--1949 group, 350 deaths were observed vs 343 expected and no bone sarcomas or head carcinomas occurred. Among women who survived at least 2 y after rust measurement of body radium, a significant excess of observed vs expected deaths was found only for radium intakes greater than 1.85 MBq of {sup 226}Ra + {sup 228}Ra, and no trend of deaths or reduction of life expectancy was found with length of employment.

  10. Toughness amplification in natural composites

    NASA Astrophysics Data System (ADS)

    Barthelat, Francois; Rabiei, Reza

    2011-04-01

    Natural structural materials such as bone and seashells are made of relatively weak building blocks, yet they exhibit remarkable combinations of stiffness, strength and toughness. This performance can be largely explained by their "staggered microstructure": stiff inclusions of high aspect ratio are laid parallel to each other with some overlap, and bonded by a softer matrix. While stiffness and strength are now well understood for staggered composites, the mechanisms involved in fracture are still largely unknown. This is a significant lack since the amplification of toughness with respect to their components is by far the most impressive feature in natural staggered composites such as nacre or bone. Here a model capturing the salient mechanisms involved in the cracking of a staggered structure is presented. We show that the pullout of inclusions and large process zones lead to tremendous toughness by far exceeding that of individual components. The model also suggests that a material like nacre cannot reach steady state cracking, with the implication that the toughness increases indefinitely with crack advance. These findings agree well with existing fracture data, and for the first time relate microstructural parameters with overall toughness. These insights will prove useful in the design of biomimetic materials, and provide clues on how bone fractures at the nano and microscales.

  11. Test-Free Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C. (Technical Monitor)

    2003-01-01

    Computational simulation results can give the prediction of damage growth and progression and fracture toughness of composite structures. The experimental data from literature provide environmental effects on the fracture behavior of metallic or fiber composite structures. However, the traditional experimental methods to analyze the influence of the imposed conditions are expensive and time consuming. This research used the CODSTRAN code to model the temperature effects, scaling effects and the loading effects of fiberbraided composite specimens with and without fiber-optic sensors on the damage initiation and energy release rates. The load-displacement relationship and fracture toughness assessment approach is compared with the test results from literature and it is verified that the computational simulation, with the use of established material modeling and finite element modules, adequately tracks the changes of fracture toughness and subsequent fracture propagation for any fiberbraided composite structure due to the change of fiber orientations, presence of large diameter optical fibers, and any loading conditions.

  12. Bayesian accelerated failure time model for space-time dependency in a geographically augmented survival model

    PubMed Central

    Onicescu, Georgiana; Lawson, Andrew; Zhang, Jiajia; Gebregziabher, Mulugeta; Wallace, Kristin; Eberth, Jan M

    2016-01-01

    In this paper, we extend the spatially explicit survival model for small area cancer data by allowing dependency between space and time and using accelerated failure time models. Spatial dependency is modeled directly in the definition of the survival, density, and hazard functions. The models are developed in the context of county level aggregated data. Two cases are considered: the first assumes that the spatial and temporal distributions are independent; the second allows for dependency between the spatial and temporal components. We apply the models to prostate cancer data from the Louisiana SEER cancer registry. PMID:26220537

  13. Mean exit time and survival probability within the CTRW formalism

    NASA Astrophysics Data System (ADS)

    Montero, M.; Masoliver, J.

    2007-05-01

    An intense research on financial market microstructure is presently in progress. Continuous time random walks (CTRWs) are general models capable to capture the small-scale properties that high frequency data series show. The use of CTRW models in the analysis of financial problems is quite recent and their potentials have not been fully developed. Here we present two (closely related) applications of great interest in risk control. In the first place, we will review the problem of modelling the behaviour of the mean exit time (MET) of a process out of a given region of fixed size. The surveyed stochastic processes are the cumulative returns of asset prices. The link between the value of the MET and the timescale of the market fluctuations of a certain degree is crystal clear. In this sense, MET value may help, for instance, in deciding the optimal time horizon for the investment. The MET is, however, one among the statistics of a distribution of bigger interest: the survival probability (SP), the likelihood that after some lapse of time a process remains inside the given region without having crossed its boundaries. The final part of the manuscript is devoted to the study of this quantity. Note that the use of SPs may outperform the standard “Value at Risk" (VaR) method for two reasons: we can consider other market dynamics than the limited Wiener process and, even in this case, a risk level derived from the SP will ensure (within the desired quintile) that the quoted value of the portfolio will not leave the safety zone. We present some preliminary theoretical and applied results concerning this topic.

  14. Project Rescue! Helping a Lost but Determined CIO Navigate the Tough New World of Higher Education IT

    ERIC Educational Resources Information Center

    Laster, Stephen

    2011-01-01

    This column explores the world of Gene, a composite CIO who leads a sizable IT organization for a top 100 university somewhere in America. The author's goal is to help him navigate the tough times ahead of higher education IT. The author peeks into Gene's daily goings-on, investigates his problems, and helps him to not only survive, but prosper.

  15. Fracture toughness of silicon

    NASA Technical Reports Server (NTRS)

    Chen, C. P.; Leipold, M. H.

    1980-01-01

    The paper presents a study to determine the fracture toughness and to characterize fracture modes of silicon as a function of the orientation of single-crystal and polycrystalline material. It is shown that bar specimens cracked by Knoop microhardness indentation and tested to fracture under four-point bending at room temperature were used to determine the fracture toughness values. It is found that the lowest fracture toughness value of single crystal silicon was 0.82 MN/m to the 3/2 in the 111 plane type orientation, although the difference in values in the 111, 110, and 100 planes was small.

  16. Modeling discrete survival time using genomic feature data.

    PubMed

    Ferber, Kyle; Archer, Kellie J

    2015-01-01

    Researchers have recently shown that penalized models perform well when applied to high-throughput genomic data. Previous researchers introduced the generalized monotone incremental forward stagewise (GMIFS) method for fitting overparameterized logistic regression models. The GMIFS method was subsequently extended by others for fitting several different logit link ordinal response models to high-throughput genomic data. In this study, we further extended the GMIFS method for ordinal response modeling using a complementary log-log link, which allows one to model discrete survival data. We applied our extension to a publicly available microarray gene expression dataset (GSE53733) with a discrete survival outcome. The dataset included 70 primary glioblastoma samples from patients of the German Glioma Network with long-, intermediate-, and short-term overall survival. We tested the performance of our method by examining the prediction accuracy of the fitted model. The method has been implemented as an addition to the ordinalgmifs package in the R programming environment.

  17. Generating survival times to simulate Cox proportional hazards models with time-varying covariates.

    PubMed

    Austin, Peter C

    2012-12-20

    Simulations and Monte Carlo methods serve an important role in modern statistical research. They allow for an examination of the performance of statistical procedures in settings in which analytic and mathematical derivations may not be feasible. A key element in any statistical simulation is the existence of an appropriate data-generating process: one must be able to simulate data from a specified statistical model. We describe data-generating processes for the Cox proportional hazards model with time-varying covariates when event times follow an exponential, Weibull, or Gompertz distribution. We consider three types of time-varying covariates: first, a dichotomous time-varying covariate that can change at most once from untreated to treated (e.g., organ transplant); second, a continuous time-varying covariate such as cumulative exposure at a constant dose to radiation or to a pharmaceutical agent used for a chronic condition; third, a dichotomous time-varying covariate with a subject being able to move repeatedly between treatment states (e.g., current compliance or use of a medication). In each setting, we derive closed-form expressions that allow one to simulate survival times so that survival times are related to a vector of fixed or time-invariant covariates and to a single time-varying covariate. We illustrate the utility of our closed-form expressions for simulating event times by using Monte Carlo simulations to estimate the statistical power to detect as statistically significant the effect of different types of binary time-varying covariates. This is compared with the statistical power to detect as statistically significant a binary time-invariant covariate.

  18. Smart textiles: Tough cotton

    NASA Astrophysics Data System (ADS)

    Avila, Alba G.; Hinestroza, Juan P.

    2008-08-01

    Cotton is an important raw material for producing soft textiles and clothing. Recent discoveries in functionalizing cotton fibres with nanotubes may offer a new line of tough, wearable, smart and interactive garments.

  19. Tough Composite Materials

    NASA Technical Reports Server (NTRS)

    Vosteen, L. F. (Compiler); Johnson, N. J. (Compiler); Teichman, L. A. (Compiler)

    1984-01-01

    Papers and working group summaries are presented which address composite material behavior and performance improvement. Topic areas include composite fracture toughness and impact characterization, constituent properties and interrelationships, and matrix synthesis and characterization.

  20. TOUGH2 software qualification

    SciTech Connect

    Pruess, K.; Simmons, A.; Wu, Y.S.; Moridis, G.

    1996-02-01

    TOUGH2 is a numerical simulation code for multi-dimensional coupled fluid and heat flow of multiphase, multicomponent fluid mixtures in porous and fractured media. It belongs to the MULKOM ({open_quotes}MULti-KOMponent{close_quotes}) family of codes and is a more general version of the TOUGH simulator. The MULKOM family of codes was originally developed with a focus on geothermal reservoir simulation. They are suited to modeling systems which contain different fluid mixtures, with applications to flow problems arising in the context of high-level nuclear waste isolation, oil and gas recovery and storage, and groundwater resource protection. TOUGH2 is essentially a subset of MULKOM, consisting of a selection of the better tested and documented MULKOM program modules. The purpose of this package of reports is to provide all software baseline documents necessary for the software qualification of TOUGH2.

  1. Accelerating Child Survival and Development in Dark Times.

    ERIC Educational Resources Information Center

    Grant, James P.

    Measures were proposed that would enable UNICEF, in association with others and despite prevailing difficult economic circumstances, to more effectively bring well-being and hope to hundreds of millions of children. Specific proposals were designed to help most countries accelerate child survival and development. Most particularly, it was…

  2. Crunch Time for the Diplomas: Will They Survive?

    ERIC Educational Resources Information Center

    Baker, Mike

    2009-01-01

    This article looks at the introduction of the diplomas as part of the 14-19 reforms in England. It questions whether they can survive the low initial take-up from students, the lack of interest from key parts of the schools sector, and the confusing messages about what sort of qualification they are meant to be. It also asks whether the diplomas…

  3. Circadian timing of single daily 'meal' affects survival of mice

    NASA Technical Reports Server (NTRS)

    Nelson, W.; Cadotte, L.; Halberg, F.

    1973-01-01

    It is shown that the survival of young mice after abrupt restriction to a single 4-hr span of daily food accessibility can depend on the temporal placement of this feeding span in relation to the lighting regimen. Housing conditions are an important codeterminant of this response.

  4. Rubber dam may increase the survival time of dental restorations.

    PubMed

    Keys, William; Carson, Susan J

    2017-03-01

    Data sourcesCochrane Oral Health's Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, LILACS, SciELO, Chinese BioMedical Literature Database, VIP, China National Knowledge Infrastructure, ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform, OpenGrey and Sciencepaper Online databases. Handsearches in a number of journals.Study selectionRandomised controlled trials, including split-mouth studies assessing the effects of rubber dam isolation for restorative treatments in dental patients.Data extraction and synthesisTwo review authors independently screened the results of the electronic searches, extracted data and assessed the risk of bias of the included studies.ResultsFour studies involving a total of 1,270 patients were included. The studies were at high risk of bias. One trial was excluded from the analysis due to inconsistencies in the presented data. Restorations had a significantly higher survival rate in the rubber dam isolation group compared to the cotton roll isolation group at six months in participants receiving composite restorative treatment of non-carious cervical lesions (risk ratio (RR) 1.19, 95% confidence interval (CI) 1.04 to 1.37, very low-quality evidence). The rubber dam group had a lower risk of failure at two years in children undergoing proximal atraumatic restorative treatment in primary molars (hazard ratio (HR) 0.80, 95% CI 0.66 to 0.97, very low-quality evidence). One trial reported limited data showing that rubber dam usage during fissure sealing might shorten the treatment time. None of the included studies mentioned adverse effects or reported the direct cost of the treatment, or the level of patient acceptance/satisfaction. There was also no evidence evaluating the effects of rubber dam usage on the quality of the restorations.ConclusionsWe found some very low-quality evidence, from single studies, suggesting that rubber dam usage in dental direct

  5. TOUGH-Fx

    SciTech Connect

    Moridis, George Julius; Kowalsky, Michael; Finsterle, Stefan

    2005-09-01

    TOUGH-Fx represents the next generation of family of codes for the solution of problems of fluid flow and heat transport in complex geologic media. TOUGH-Fx is the successor to the TOUGH2 family of codes developed by LBNL and used extensively all over the world, It is written in FORTRAN 9512003, uses the advanced capabilities of the new language, and was designed to take advantage of the benefits of object-oriented programming. The code can simulate flow and transport of important (economically and environmentally) fluids in the subsurface, as well as heat transport and any changes of phase that occur within the temperature range of the process/phenomenon under study. TOUGH-Fx is the generic name that describes the main components of the computational engine used by the code. For the simulation of a particular process. TOUGH-Fx needs a module (or modules) that describe the equation of state (EOS) of the fluids involved in the process. Thus, simulation of different processes are possible by using the main TOUGH-Fx and invoking the corresponding EOS modules. Such modules include the EOS of water, the EQS of air and other gases, the EOS of volatile organic substances, the EOS or liquid hydrocarbons, etc.

  6. Tough, bio-inspired hybrid materials

    SciTech Connect

    Munch, Etienne; Launey, Maximimilan E.; Alsem, Daan H.; Saiz, Eduardo; Tomsia, Antoni P.; Ritchie, Robert O.

    2008-10-06

    The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs extremely difficult to replicate synthetically. Here we emulate Nature's toughening mechanisms through the combination of two ordinary compounds, aluminum oxide and polymethylmethacrylate, into ice-templated structures whose toughness can be over 300 times (in energy terms) that of their constituents. The final product is a bulk hybrid ceramic material whose high yield strength and fracture toughness ({approx}200 MPa and {approx}30 MPa{radical}m) provide specific properties comparable to aluminum alloys. These model materials can be used to identify the key microstructural features that should guide the synthesis of bio-inspired ceramic-based composites with unique strength and toughness.

  7. Tough and tender: embodied categorization of gender.

    PubMed

    Slepian, Michael L; Weisbuch, Max; Rule, Nicholas O; Ambady, Nalini

    2011-01-01

    Emerging evidence has shown that human thought can be embodied within physical sensations and actions. Indeed, abstract concepts such as morality, time, and interpersonal warmth can be based on metaphors that are grounded in bodily experiences (e.g., physical temperature can signal interpersonal warmth). We hypothesized that social-category knowledge is similarly embodied, and we tested this hypothesis by examining a sensory metaphor related to categorical judgments of gender. We chose the dimension of "toughness" (ranging from tough to tender), which is often used to characterize differences between males and females. Across two studies, the proprioceptive experience of toughness (vs. tenderness) was manipulated as participants categorized sex-ambiguous faces as male or female. Two different manipulations of proprioceptive toughness predictably biased the categorization of faces toward "male." These findings suggest that social-category knowledge is at least partially embodied.

  8. Genetic Influences on Survival Time After Severe Hemorrhage in Inbred Rat Strains

    DTIC Science & Technology

    2011-04-12

    previously found to be divergent in survival time. NBV differed by 20% (P 0.01; BN SS FHH LEW DA) and had a heritability (h2) of 0.56. Hence...responses. These data indicate that both blood volume and survival time after hemorrhage in rats are heritable quantitative traits, and continue to suggest... Heritability of blood volume was determined using with and between variance components from ANOVA (21). Heritability of survival times was obtained

  9. Test-Free Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Minnetyan, Levon; Chamis, Christos C. (Technical Monitor)

    2003-01-01

    Computational simulation results can give the prediction of damage growth and progression and fracture toughness of composite structures. The experimental data from literature provide environmental effects on the fracture behavior of metallic or fiber composite structures. However, the traditional experimental methods to analyze the influence of the imposed conditions are expensive and time consuming. This research used the CODSTRAN code to model the temperature effects, scaling effects and the loading effects of fiber/braided composite specimens with and without fiber-optic sensors on the damage initiation and energy release rates. The load-displacement relationship and fracture toughness assessment approach is compared with the test results from literature and it is verified that the computational simulation, with the use of established material modeling and finite element modules, adequately tracks the changes of fracture toughness and subsequent fracture propagation for any fiber/braided composite structure due to the change of fiber orientations, presence of large diameter optical fibers, and any loading conditions.

  10. Predicting survival time for metastatic castration resistant prostate cancer: An iterative imputation approach

    PubMed Central

    Deng, Detian; Du, Yu; Ji, Zhicheng; Rao, Karthik; Wu, Zhenke; Zhu, Yuxin; Coley, R. Yates

    2016-01-01

    In this paper, we present our winning method for survival time prediction in the 2015 Prostate Cancer DREAM Challenge, a recent crowdsourced competition focused on risk and survival time predictions for patients with metastatic castration-resistant prostate cancer (mCRPC). We are interested in using a patient's covariates to predict his or her time until death after initiating standard therapy. We propose an iterative algorithm to multiply impute right-censored survival times and use ensemble learning methods to characterize the dependence of these imputed survival times on possibly many covariates. We show that by iterating over imputation and ensemble learning steps, we guide imputation with patient covariates and, subsequently, optimize the accuracy of survival time prediction. This method is generally applicable to time-to-event prediction problems in the presence of right-censoring. We demonstrate the proposed method's performance with training and validation results from the DREAM Challenge and compare its accuracy with existing methods. PMID:28299176

  11. A Straight-Talk Survival Guide for Colleges

    ERIC Educational Resources Information Center

    Facione, Peter A.

    2009-01-01

    Times are very tough. The great majority of colleges are looking at 2009 and 2010 and beyond, in anticipation of the deepest budget cuts in more than a generation. But as bad as the financial situation may be, colleges can survive if they take swift and strong emergency action. It is time for some straight talk, starting with the realization that…

  12. A Multivariate Model for the Meta-Analysis of Study Level Survival Data at Multiple Times

    ERIC Educational Resources Information Center

    Jackson, Dan; Rollins, Katie; Coughlin, Patrick

    2014-01-01

    Motivated by our meta-analytic dataset involving survival rates after treatment for critical leg ischemia, we develop and apply a new multivariate model for the meta-analysis of study level survival data at multiple times. Our data set involves 50 studies that provide mortality rates at up to seven time points, which we model simultaneously, and…

  13. Non-parametric estimation of gap time survival functions for ordered multivariate failure time data.

    PubMed

    Schaubel, Douglas E; Cai, Jianwen

    2004-06-30

    Times between sequentially ordered events (gap times) are often of interest in biomedical studies. For example, in a cancer study, the gap times from incidence-to-remission and remission-to-recurrence may be examined. Such data are usually subject to right censoring, and within-subject failure times are generally not independent. Statistical challenges in the analysis of the second and subsequent gap times include induced dependent censoring and non-identifiability of the marginal distributions. We propose a non-parametric method for constructing one-sample estimators of conditional gap-time specific survival functions. The estimators are uniformly consistent and, upon standardization, converge weakly to a zero-mean Gaussian process, with a covariance function which can be consistently estimated. Simulation studies reveal that the asymptotic approximations are appropriate for finite samples. Methods for confidence bands are provided. The proposed methods are illustrated on a renal failure data set, where the probabilities of transplant wait-listing and kidney transplantation are of interest.

  14. Power Analysis for Trials with Discrete-Time Survival Endpoints

    ERIC Educational Resources Information Center

    Jozwiak, Katarzyna; Moerbeek, Mirjam

    2012-01-01

    Studies on event occurrence aim to investigate if and when subjects experience a particular event. The timing of events may be measured continuously using thin precise units or discretely using time periods. The latter metric of time is often used in social science research and the generalized linear model (GLM) is an appropriate model for data…

  15. Two-Sample Inference for Median Survival Times Based on One-Sample Procedures for Censored Survival Data

    DTIC Science & Technology

    1988-08-01

    BTI ..iLi. CoP The Pennsylvania State University Department of Statistics V111 University Park, Pennsylvania TECHNICAL REPORTS AND PREPRINTS Number...compare confidence intervals for the median survival times of four dosage regimens 5-fluorouracil. Refer to Brookmeyer and Crowley (1982a) for a...ANSFIELD, F., KLOTZ, J., and THE CENTRAL ONCOLOGY GROUP (1977), "A Phase III 4-. Study Comparing the Clincial Utility of Four- Dosage Regimens of 5

  16. Survival time estimation using Injury Severity Score (ISS) in homicide cases.

    PubMed

    Cros, Jérôme; Alvarez, Jean-Claude; Sbidian, Emilie; Charlier, Philippe; de la Grandmaison, Geoffroy Lorin

    2013-12-10

    The aim of our study was to assess the value of ISS to estimate survival time in a retrospective study of all homicidal deaths in the Western suburbs of Paris between 1994 and 2008. Stab wounds were the most common cause of death. Survival time between assault and death, determined in 107 cases out of 511 homicide cases, ranged from 0 min to 25 days (mean 39 h). There was an overall significant association between the survival time and the ISS score. ISS and survival time were strongly associated with male victims and a clear trend was seen with women. Regarding the type of wounds, a trend was seen with gunshot wounds and blunt injuries, but not with stab wounds. There was no influence of blood toxicological results and resuscitation attempts. Overall, ISS was a good predictor of a survival under 30 min.

  17. Tactics for Tough Budget Times

    ERIC Educational Resources Information Center

    Martin, Ann M.

    2011-01-01

    How does one maintain high goals for instruction with dwindling funds? On a district level, the ability to do more with less is just not possible. It is the capability to reposition available resources that achieves critical goals. One way to visualize this concept is to think of a stretched elastic band. When that band is extended, it changes its…

  18. Fracture toughness of fibrous composite materials

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1984-01-01

    Laminates with various proportions of 0 deg, 45 deg, and 90 deg plies were fabricated from T300/5208 and T300/BP-907 graphite/epoxy prepreg tape material. The fracture toughness of each laminate orientation or lay-up was determined by testing center-cracked specimens, and it was also predicted with the general fracture-toughness parameter. The predictions were good except when crack-tip splitting was large, at which time the toughness and strengths tended to be underpredicted. By using predictions, a parametric study was also made of factors that influence fracture toughness. Fiber and matrix properties as well as lay-up were investigated. Without crack-tip splitting, fracture toughness increases in proportion to fiber strength and fiber volume fraction, increases linearly with E(22)/E(11), is largest when the modulus for non-0 deg fibers is greater than that of 0 deg fibers, and is smallest for 0(m)/90(p)(s) lay-ups. (The E(11) and E(22) are Young's moduli of the lamina parallel to and normal to the direction of the fibers, respectively). For a given proportion of 0 deg plies, the most notch-sensitive lay-ups are 0(m)/90(p)(s) and the least sensitive are 0(m)/45(n)(s) and alpha(s). Notch sensitivity increases with the proportion of 0 deg plies and decreases with alpha. Strong, tough matrix materials, which inhibit crack-tip splitting, generally lead to minimum fracture toughness.

  19. Predicted Water Immersion Survival Times for Anti-Exposure Ensembles

    DTIC Science & Technology

    2005-10-01

    level of garment insulation and anthropometrics to provide guidelines for safe immersed exposure times. 176 Report Documentation Page Form ApprovedOMB...males only. The model can account for variations in weight, body fat (BF), and metabolic rate. For this study, three anthropometric cases were used: (1...chest, abdomen, right and left thighs, calves, feet, biceps, forearms and hands. A clo value can be specified for each area. Clo is a measure of

  20. Proceedings of the TOUGH workshop

    SciTech Connect

    Pruess, K.

    1990-09-01

    A workshop on applications and enhancements of the TOUGH/MULKOM family of multiphase fluid and heat flow simulation programs was held at Lawrence Berkeley Laboratory on September 13--14, 1990. The workshop was attended by 62 scientists from seven countries with interests in geothermal reservoir engineering, nuclear waste isolation, unsaturated zone hydrology, environmental problems, and laboratory and field experimentation. The meeting featured 21 technical presentations, extended abstracts of which are reproduced in the present volume in unedited form. Simulator applications included processes on a broad range of space scales, from centimeters to kilometers, with transient times from seconds to geologic time scales. A number of code enhancements were reported that increased execution speeds for large 3-D problems by factors of order 20, reduced memory requirements, and improved user-friendliness. The workshop closed with an open discussion session that focussed on future needs and means for interaction in the TOUGH user community. Input from participants was gathered by means of a questionnaire that is reproduced in the appendix. 171 refs., 91 figs., 16 tabs.

  1. Estimating latent time of maturation and survival costs of reproduction in continuous time from capture-recapture data

    USGS Publications Warehouse

    Ergon, T.; Yoccoz, N.G.; Nichols, J.D.; Thomson, David L.; Cooch, Evan G.; Conroy, Michael J.

    2009-01-01

    In many species, age or time of maturation and survival costs of reproduction may vary substantially within and among populations. We present a capture-mark-recapture model to estimate the latent individual trait distribution of time of maturation (or other irreversible transitions) as well as survival differences associated with the two states (representing costs of reproduction). Maturation can take place at any point in continuous time, and mortality hazard rates for each reproductive state may vary according to continuous functions over time. Although we explicitly model individual heterogeneity in age/time of maturation, we make the simplifying assumption that death hazard rates do not vary among individuals within groups of animals. However, the estimates of the maturation distribution are fairly robust against individual heterogeneity in survival as long as there is no individual level correlation between mortality hazards and latent time of maturation. We apply the model to biweekly capture?recapture data of overwintering field voles (Microtus agrestis) in cyclically fluctuating populations to estimate time of maturation and survival costs of reproduction. Results show that onset of seasonal reproduction is particularly late and survival costs of reproduction are particularly large in declining populations.

  2. Pore size distribution, survival probability, and relaxation time in random and ordered arrays of fibers

    NASA Astrophysics Data System (ADS)

    Tomadakis, Manolis M.; Robertson, Teri J.

    2003-07-01

    We present a random walk based investigation of the pore size probability distribution and its moments, the survival probability and mean survival time, and the principal relaxation time, for random and ordered arrays of cylindrical fibers of various orientation distributions. The dimensionless mean survival time, principal relaxation time, mean pore size, and mean square pore size are found to increase with porosity, remain practically independent of the directionality of random fiber beds, and attain lower values for ordered arrays. Wide pore size distributions are obtained for random fiber structures and relatively narrow for ordered square arrays, all in very good agreement with theoretically predicted limiting values. Analytical results derived for the pore size probability and its lower moments for square arrays of fibers practically coincide with the corresponding simulation results. Earlier variational bounds on the mean survival time and principal relaxation time are obeyed by our numerical results in all cases, and are found to be quite sharp up to very high porosities. Dimensionless groups representing the deviation of such bounds from our simulation results vary in practically the same range as the corresponding values reported earlier for beds of spherical particles. A universal scaling expression of the literature relating the mean survival time to the mean pore size [S. Torquato and C. L. Y. Yeong, J. Chem. Phys. 106, 8814 (1997)] agrees very well with our results for all types of fiber structures, thus validated for the first time for anisotropic porous media.

  3. Matching methods for obtaining survival functions to estimate the effect of a time-dependent treatment

    PubMed Central

    Li, Yun; Schaubel, Douglas E.; He, Kevin

    2013-01-01

    In observational studies of survival time featuring a binary time-dependent treatment, the hazard ratio (an instantaneous measure) is often used to represent the treatment effect. However, investigators are often more interested in the difference in survival functions. We propose semiparametric methods to estimate the causal effect of treatment among the treated with respect to survival probability. The objective is to compare post-treatment survival with the survival function that would have been observed in the absence of treatment. For each patient, we compute a prognostic score (based on the pre-treatment death hazard) and a propensity score (based on the treatment hazard). Each treated patient is then matched with an alive, uncensored and not-yet-treated patient with similar prognostic and/or propensity scores. The experience of each treated and matched patient is weighted using a variant of Inverse Probability of Censoring Weighting to account for the impact of censoring. We propose estimators of the treatment-specific survival functions (and their difference), computed through weighted Nelson-Aalen estimators. Closed-form variance estimators are proposed which take into consideration the potential replication of subjects across matched sets. The proposed methods are evaluated through simulation, then applied to estimate the effect of kidney transplantation on survival among end-stage renal disease patients using data from a national organ failure registry. PMID:25309633

  4. Is Survival Time After Hemorrhage a Heritable, Quantitative Trait?: An Initial Assessment

    DTIC Science & Technology

    2008-06-01

    that in turn was connected to a Differential DC Amplifier and Signal Conditioner (Ectron Corp., San Diego, Calif). Blood pressure was measured and...calculated blood volume was removed during a 26-min period from conscious unrestrained animals. Rats were observed for a maximum of 6 h. Survival time...the Surviving Blood Loss Program of the Defense Advanced Research Projects Agency. DOI: 10.1097/SHK.0b013e31815cfe30 Copyright 2008 by the Shock

  5. Estimating survival rates with time series of standing age-structure data

    USGS Publications Warehouse

    Udevitz, Mark S.; Gogan, Peter J.

    2014-01-01

    It has long been recognized that age-structure data contain useful information for assessing the status and dynamics of wildlife populations. For example, age-specific survival rates can be estimated with just a single sample from the age distribution of a stable, stationary population. For a population that is not stable, age-specific survival rates can be estimated using techniques such as inverse methods that combine time series of age-structure data with other demographic data. However, estimation of survival rates using these methods typically requires numerical optimization, a relatively long time series of data, and smoothing or other constraints to provide useful estimates. We developed general models for possibly unstable populations that combine time series of age-structure data with other demographic data to provide explicit maximum likelihood estimators of age-specific survival rates with as few as two years of data. As an example, we applied these methods to estimate survival rates for female bison (Bison bison) in Yellowstone National Park, USA. This approach provides a simple tool for monitoring survival rates based on age-structure data.

  6. Median Survival Time of Endometrial Cancer Patients with Lymphovascular Invasion at the Hospital Universiti Sains Malaysia

    PubMed Central

    Asyikeen, Wan Adnan Wan Nor; Siti-Azrin, Ab Hamid; Jalil, Nur Asyilla Che; Zin, Anani Aila Mat; Othman, Nor Hayati

    2016-01-01

    Background Endometrial cancer is the most common gynaecologic malignancy among females worldwide. The purpose of this study was to determine the median survival time of endometrial cancer patients at the Hospital Universiti Sains Malaysia (USM). Methods A list of 121 endometrial cancer cases registered at Hospital USM between 2000 until 2011 was retrospectively reviewed. The survival time of the endometrial cancer patients was estimated by Kaplan-Meier survival analysis. Log-rank tests were performed to compare the survival of the patients based on socio-demographics and clinical presentation. Results Only 108 patients, 87.0%, were included who were of Malay ethnicity. Previous history included menopause in 67.6% of patients and diabetes mellitus in 39.8% of patients; additionally, 63.4% of patients were nulliparous. Tumour staging was as follows: 24.5% stage I, 10.8% stage II, 26.5% stage III and 38.2% stage IV. The overall median survival time of the endometrial cancer patients was 70.20 months (95% confidence interval (CI): 51.79, 88.61). The significant factors were age, the presence of lymphovascular invasion and treatment received. Conclusion The overall survival of endometrial cancer was low. A prospective study needs to be carried out to discover more effective and accurate tests for the early detection of endometrial cancer. PMID:28090178

  7. Time-course regulation of quercetin on cell survival/proliferation pathways in human hepatoma cells.

    PubMed

    Granado-Serrano, Ana Belén; Angeles Martín, María; Bravo, Laura; Goya, Luis; Ramos, Sonia

    2008-04-01

    Quercetin, a dietary flavonoid, has been shown to possess anticarcinogenic properties, but the precise molecular mechanisms of action are not thoroughly elucidated. This study was aimed at investigating the time-course regulation effect of quercetin on survival/proliferation pathways in a human hepatoma cell line (HepG2). Quercetin induced a significant time-dependent inactivation of the major survival signaling proteins, i. e., phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B (AKT), extracellular regulated kinase (ERK), protein kinase C-alpha (PKC-alpha), in concert with a time-dependent activation of key death-related signals: c-jun amino-terminal kinase (JNK) and PKC-delta. These data suggest that quercetin exerts a tight regulation of survival/proliferation pathways that requires the integration of different signals and persists over time, being the balance of these regulatory signals what determines the fate of HepG2 cells.

  8. User's Guide for TOUGH2-MP - A Massively Parallel Version of the TOUGH2 Code

    SciTech Connect

    Earth Sciences Division; Zhang, Keni; Zhang, Keni; Wu, Yu-Shu; Pruess, Karsten

    2008-05-27

    TOUGH2-MP is a massively parallel (MP) version of the TOUGH2 code, designed for computationally efficient parallel simulation of isothermal and nonisothermal flows of multicomponent, multiphase fluids in one, two, and three-dimensional porous and fractured media. In recent years, computational requirements have become increasingly intensive in large or highly nonlinear problems for applications in areas such as radioactive waste disposal, CO2 geological sequestration, environmental assessment and remediation, reservoir engineering, and groundwater hydrology. The primary objective of developing the parallel-simulation capability is to significantly improve the computational performance of the TOUGH2 family of codes. The particular goal for the parallel simulator is to achieve orders-of-magnitude improvement in computational time for models with ever-increasing complexity. TOUGH2-MP is designed to perform parallel simulation on multi-CPU computational platforms. An earlier version of TOUGH2-MP (V1.0) was based on the TOUGH2 Version 1.4 with EOS3, EOS9, and T2R3D modules, a software previously qualified for applications in the Yucca Mountain project, and was designed for execution on CRAY T3E and IBM SP supercomputers. The current version of TOUGH2-MP (V2.0) includes all fluid property modules of the standard version TOUGH2 V2.0. It provides computationally efficient capabilities using supercomputers, Linux clusters, or multi-core PCs, and also offers many user-friendly features. The parallel simulator inherits all process capabilities from V2.0 together with additional capabilities for handling fractured media from V1.4. This report provides a quick starting guide on how to set up and run the TOUGH2-MP program for users with a basic knowledge of running the (standard) version TOUGH2 code, The report also gives a brief technical description of the code, including a discussion of parallel methodology, code structure, as well as mathematical and numerical methods used

  9. Survival time of the susceptible-infected-susceptible infection process on a graph.

    PubMed

    van de Bovenkamp, Ruud; Van Mieghem, Piet

    2015-09-01

    The survival time T is the longest time that a virus, a meme, or a failure can propagate in a network. Using the hitting time of the absorbing state in an uniformized embedded Markov chain of the continuous-time susceptible-infected-susceptible (SIS) Markov process, we derive an exact expression for the average survival time E[T] of a virus in the complete graph K_{N} and the star graph K_{1,N-1}. By using the survival time, instead of the average fraction of infected nodes, we propose a new method to approximate the SIS epidemic threshold τ_{c} that, at least for K_{N} and K_{1,N-1}, correctly scales with the number of nodes N and that is superior to the epidemic threshold τ_{c}^{(1)}=1/λ_{1} of the N-intertwined mean-field approximation, where λ_{1} is the spectral radius of the adjacency matrix of the graph G. Although this new approximation of the epidemic threshold offers a more intuitive understanding of the SIS process, it remains difficult to compare outbreaks in different graph types. For example, the survival in an arbitrary graph seems upper bounded by the complete graph and lower bounded by the star graph as a function of the normalized effective infection rate τ/τ_{c}^{(1)}. However, when the average fraction of infected nodes is used as a basis for comparison, the virus will survive in the star graph longer than in any other graph, making the star graph the worst-case graph instead of the complete graph. Finally, in non-Markovian SIS, the distribution of the spreading attempts over the infectious period of a node influences the survival time, even if the expected number of spreading attempts during an infectious period (the non-Markovian equivalent of the effective infection rate) is kept constant. Both early and late infection attempts lead to shorter survival times. Interestingly, just as in Markovian SIS, the survival times appear to be exponentially distributed, regardless of the infection and curing time distributions.

  10. Intraspecific variation in desiccation survival time of Aedes aegypti (L.) mosquito eggs of Australian origin.

    PubMed

    Faull, Katherine J; Williams, Craig R

    2015-12-01

    Aedes aegypti (L.) mosquitoes preferentially oviposit in natural and artificial receptacles where their eggs are able to withstand drying as water levels fluctuate. Desiccation-resistant eggs also increase the potential for establishment in non-native habitats while providing logistical impediments to control programs. Viability and mean survival times of eggs stored under three dryness conditions for up to 367 days were investigated among three field-derived colonies of Australian Ae. aegypti to understand variation in desiccation survival. Further investigations compared egg survival between an established colony and its wild counterpart. Our results confirmed that Ae. aegypti eggs can withstand desiccation for extended periods of time with approximately 2-15% egg viability recorded after one year and viability remaining above 88% under all conditions through 56 days. Intraspecific variations in egg survival times were recorded, suggesting local adaptation while each of the colonies demonstrated a consistent preference for higher humidity. Egg volume varied between the populations, suggesting a relationship between egg volume and survival time, with the marginally larger eggs (Charters Towers and Innisfail) having greater desiccation resistance over the range of conditions. The strong survivorship of Charters Towers eggs in dry, warm conditions demonstrates the adaptive significance of a desiccation-resistant egg.

  11. The survival time of chocolates on hospital wards: covert observational study

    PubMed Central

    Moualed, Daniel J; Nicolson, Phillip L R; Adjei, Felicia D; Cakebread, Holly E; Duehmke, Rudolf M; Martin, Claire A

    2013-01-01

    Objective To quantify the consumption of chocolates in a hospital ward environment. Design Multicentre, prospective, covert observational study. Setting Four wards at three hospitals (where the authors worked) within the United Kingdom. Participants Boxes of Quality Street (Nestlé) and Roses (Cadbury) on the ward and anyone eating these chocolates. Intervention Observers covertly placed two 350 g boxes of Quality Street and Roses chocolates on each ward (eight boxes were used in the study containing a total of 258 individual chocolates). These boxes were kept under continuous covert surveillance, with the time recorded when each chocolate was eaten. Main outcome measure Median survival time of a chocolate. Results 191 out of 258 (74%) chocolates were observed being eaten. The mean total observation period was 254 minutes (95% confidence interval 179 to 329). The median survival time of a chocolate was 51 minutes (39 to 63). The model of chocolate consumption was non-linear, with an initial rapid rate of consumption that slowed with time. An exponential decay model best fitted these findings (model R2=0.844, P<0.001), with a survival half life (time taken for 50% of the chocolates to be eaten) of 99 minutes. The mean time taken to open a box of chocolates from first appearance on the ward was 12 minutes (95% confidence interval 0 to 24). Quality Street chocolates survived longer than Roses chocolates (hazard ratio for survival of Roses v Quality Street 0.70, 95% confidence interval 0.53 to 0.93, P=0.014). The highest percentages of chocolates were consumed by healthcare assistants (28%) and nurses (28%), followed by doctors (15%). Conclusions From our observational study, chocolate survival in a hospital ward was relatively short, and was modelled well by an exponential decay model. Roses chocolates were preferentially consumed to Quality Street chocolates in a ward setting. Chocolates were consumed primarily by healthcare assistants and nurses, followed by doctors

  12. PMR Composites Of Increased Toughness

    NASA Technical Reports Server (NTRS)

    Vannucci, Raymond D.; Bowles, Kenneth J.

    1988-01-01

    Toughness increased without sacrificing processability or hot strength. Resin composition provides best overall balance of composite toughness and retention of mechanical properties at 600 degree F (316 degree C) with processability obtained by substituting 20 mole percent of diamine used in PMR-15 resins with diamine containing twice number of flexible phenyl connecting groups.

  13. On "Tough" Movement in Spanish.

    ERIC Educational Resources Information Center

    Reider, Michael

    1993-01-01

    A survey of native Spanish speakers from both Spain and Latin America found that the choice of predicate adjectives governing "tough" constructions in Spanish (e.g., "el libro es facil de leer") varies by individual, but some patterns did emerge that suggest "tough" constructions and "it is" constructions…

  14. Kernel Smoothed Profile Likelihood Estimation in the Accelerated Failure Time Frailty Model for Clustered Survival Data

    PubMed Central

    Liu, Bo; Lu, Wenbin; Zhang, Jiajia

    2013-01-01

    Summary Clustered survival data frequently arise in biomedical applications, where event times of interest are clustered into groups such as families. In this article we consider an accelerated failure time frailty model for clustered survival data and develop nonparametric maximum likelihood estimation for it via a kernel smoother aided EM algorithm. We show that the proposed estimator for the regression coefficients is consistent, asymptotically normal and semiparametric efficient when the kernel bandwidth is properly chosen. An EM-aided numerical differentiation method is derived for estimating its variance. Simulation studies evaluate the finite sample performance of the estimator, and it is applied to the Diabetic Retinopathy data set. PMID:24443587

  15. Effect of spaying and timing of spaying on survival of dogs with mammary carcinoma.

    PubMed

    Sorenmo, K U; Shofer, F S; Goldschmidt, M H

    2000-01-01

    The risk of developing mammary gland tumors in dogs is significantly decreased by ovariohysterectomy at an early age. However, previous studies have not found a benefit to ovariohysterectomy concurrent with tumor removal in dogs with established mammary gland tumors, suggesting that the progression of these tumors is independent of continued estrogen stimulation. The purpose of this study was to evaluate the effect of spaying and of the timing of spaying on survival in dogs with mammary gland carcinoma. Signalment, spay status and spay age, tumor characteristics, treatment. survival, and cause of death of 137 dogs with mammary gland carcinoma were analyzed. The dogs were classified into 3 groups according to spay status and spay time: intact dogs, dogs spayed less than 2 years before tumor surgery (SPAY 1), and dogs spayed more than 2 years before their tumor surgery (SPAY 2). Dogs in the SPAY 1 group lived significantly longer than dogs in SPAY 2 and intact dogs (median survival of 755 days, versus 301 and 286 days, respectively, P = .02 and .03). After adjusting for differences between the spay groups with regard to age, histologic differentiation, and vascular invasion, SPAY 1 dogs survived 45% longer compared to dogs that were either intact or in the SPAY 2 group (RR = .55; 95% CI .32-.93; P = .03). This study reveals ovariohysterectomy to be an effective adjunct to tumor removal in dogs with mammary gland carcinoma and that the timing of ovariohysterectomy is important in influencing survival.

  16. Survival and relaxation time, pore size distribution moments, and viscous permeability in random unidirectional fiber structures

    NASA Astrophysics Data System (ADS)

    Tomadakis, Manolis M.; Robertson, Teri J.

    2005-03-01

    Computer simulation results are presented for the mean survival time, principal relaxation time, mean pore size, and mean square pore size, for random porous structures consisting of parallel nonoverlapping or partially overlapping fibers. The numerical procedure is based on a discrete step-by-step random walk mechanism simulating the Brownian diffusion trajectories of molecules in the porous media. Numerical results on the viscous permeability of these structures are computed with a method based on electrical conduction principles and compared to a variational bound derived from the mean survival time. The results show that nonoverlapping fiber structures exhibit lower values of the dimensionless mean survival time, principal relaxation time, mean pore size, and mean square pore size than randomly overlapping fiber structures of the same porosity, while partially overlapping fiber structures show behavior intermediate to those of the two extreme cases. The mean square pore size (second moment of the pore size distribution) is found to be a very good predictor of the mean survival time for non-, partially, and randomly overlapping fiber structures. Dimensionless groups representing the deviation of variational bounds from our simulation results vary in practically the same range as the corresponding values reported earlier for beds of spherical particles. A universal scaling expression of the literature relating the mean survival time to structural properties [S. Torquato and C. L. Y. Yeong, J. Chem. Phys. 106, 8814 (1997)] agrees very well with our results for all examined fiber structures, thus validated for the first time for porous media formed by partially overlapping particles. The permeability behavior of partially overlapping fiber structures resembles that of nonoverlapping fiber structures for flow parallel to the fibers, but not for transverse flow, where percolation phenomena prevail. The permeability results for beds of unidirectional partially

  17. Survival and relaxation time, pore size distribution moments, and viscous permeability in random unidirectional fiber structures.

    PubMed

    Tomadakis, Manolis M; Robertson, Teri J

    2005-03-01

    Computer simulation results are presented for the mean survival time, principal relaxation time, mean pore size, and mean square pore size, for random porous structures consisting of parallel nonoverlapping or partially overlapping fibers. The numerical procedure is based on a discrete step-by-step random walk mechanism simulating the Brownian diffusion trajectories of molecules in the porous media. Numerical results on the viscous permeability of these structures are computed with a method based on electrical conduction principles and compared to a variational bound derived from the mean survival time. The results show that nonoverlapping fiber structures exhibit lower values of the dimensionless mean survival time, principal relaxation time, mean pore size, and mean square pore size than randomly overlapping fiber structures of the same porosity, while partially overlapping fiber structures show behavior intermediate to those of the two extreme cases. The mean square pore size (second moment of the pore size distribution) is found to be a very good predictor of the mean survival time for non-, partially, and randomly overlapping fiber structures. Dimensionless groups representing the deviation of variational bounds from our simulation results vary in practically the same range as the corresponding values reported earlier for beds of spherical particles. A universal scaling expression of the literature relating the mean survival time to structural properties [S. Torquato and C. L. Y. Yeong, J. Chem. Phys. 106, 8814 (1997)] agrees very well with our results for all examined fiber structures, thus validated for the first time for porous media formed by partially overlapping particles. The permeability behavior of partially overlapping fiber structures resembles that of nonoverlapping fiber structures for flow parallel to the fibers, but not for transverse flow, where percolation phenomena prevail. The permeability results for beds of unidirectional partially

  18. Examining the Influence of Campus Climate on Students' Time to Degree: A Multilevel Discrete-Time Survival Analysis

    ERIC Educational Resources Information Center

    Zhou, Ji; Castellanos, Michelle

    2013-01-01

    Utilizing longitudinal data of 3477 students from 28 institutions, we examine the effects of structural diversity and quality of interracial relation on students' persistence towards graduation within six years. We utilize multilevel discrete-time survival analysis to account for the longitudinal persistence patterns as well as the nested…

  19. iMatTOUGH: An open-source Matlab-based graphical user interface for pre- and post-processing of TOUGH2 and iTOUGH2 models

    NASA Astrophysics Data System (ADS)

    Tran, Anh Phuong; Dafflon, Baptiste; Hubbard, Susan

    2016-04-01

    TOUGH2 and iTOUGH2 are powerful models that simulate the heat and fluid flows in porous and fracture media, and perform parameter estimation, sensitivity analysis and uncertainty propagation analysis. However, setting up the input files is not only tedious, but error prone, and processing output files is time consuming. In this study, we present an open source Matlab-based tool (iMatTOUGH) that supports the generation of all necessary inputs for both TOUGH2 and iTOUGH2 and visualize their outputs. The tool links the inputs of TOUGH2 and iTOUGH2, making sure the two input files are consistent. It supports the generation of rectangular computational mesh, i.e., it automatically generates the elements and connections as well as their properties as required by TOUGH2. The tool also allows the specification of initial and time-dependent boundary conditions for better subsurface heat and water flow simulations. The effectiveness of the tool is illustrated by an example that uses TOUGH2 and iTOUGH2 to estimate soil hydrological and thermal properties from soil temperature data and simulate the heat and water flows at the Rifle site in Colorado.

  20. Measurement of Survival Time in Brachionus Rotifers: Synchronization of Maternal Conditions.

    PubMed

    Kaneko, Gen; Yoshinaga, Tatsuki; Gribble, Kristin E; Welch, David M; Ushio, Hideki

    2016-07-22

    Rotifers are microscopic cosmopolitan zooplankton used as models in ecotoxicological and aging studies due to their several advantages such as short lifespan, ease of culture, and parthenogenesis that enables clonal culture. However, caution is required when measuring their survival time as it is affected by maternal age and maternal feeding conditions. Here we provide a protocol for powerful and reproducible measurement of the survival time in Brachionus rotifers following a careful synchronization of culture conditions over several generations. Empirically, poor synchronization results in early mortality and a gradual decrease in survival rate, thus resulting in weak statistical power. Indeed, under such conditions, calorie restriction (CR) failed to significantly extend the lifespan of B. plicatilis although CR-induced longevity has been demonstrated with well-synchronized rotifer samples in past and present studies. This protocol is probably useful for other invertebrate models, including the fruitfly Drosophila melanogaster and the nematode Caenorhabditis elegans, because maternal age effects have also been reported in these species.

  1. Survival time of endodontically treated teeth: a 7-year retrospective clinical study

    NASA Astrophysics Data System (ADS)

    Baldea, Bogdan; Canjau, Silvana; Popescu, Dragos; Tudor, Anca; Todea, Carmen

    2014-01-01

    The aim of this retrospective clinical study was to examine the survival time of endodontically treated teeth (ETT) and the factors that may influence the failure risk, over a period of up to 7 years. The files of 67 patients that received metal free post and core restorations using a standardized technique were analyzed. The survival probability was assessed using Kaplan-Meyer analysis and Log Rank (Matel-Cox). Cox regression was used to assess the risk of failure and to identify possible covariates. The average survival time of the ETT was 6.6 Years. The cumulative failure rate was 5.82% for all type of the restored endodontically treated teeth. The main failure type was encountered in the cervical area of the teeth, and due to the extensive hard tissue loss, the teeth were extracted.

  2. Time-course regulation of survival pathways by epicatechin on HepG2 cells.

    PubMed

    Granado-Serrano, Ana Belén; Angeles Martín, María; Goya, Luis; Bravo, Laura; Ramos, Sonia

    2009-02-01

    Polyphenols, such as epicatechin, have been reported to exhibit a wide range of biological activities. The objective of the present study was to investigate the time-dependent regulation by epicatechin of survival/proliferation pathways in HepG2 cells. Treatment of HepG2 cells with 10 micromol/L epicatechin did not result in any cell damage up to 18 h, as evaluated by the lactate dehydrogenase assay. Moreover, the enhanced cell death evoked by an oxidative stress induced with tert-butyl hydroperoxide was prevented in the cells pretreated 4 or 18 h with epicatechin. Epicatechin-induced survival was a rapid event that was accompanied by early and sustained activation of major survival signaling proteins, such as AKT/phosphatidylinositol 3-kinase and extracellular-regulated kinase (activated from 5 min to 18 h), as well as protein kinase C (PKC)-alpha (30 min to 18 h), in concert with unaltered c-jun N-amino terminal kinase levels and early inactivation of key death-related signals like PKC-delta (5 min to 18 h). Additionally, reactive oxygen species generation was transiently reduced when cells were treated with 10 micromol/L epicatechin (15-240 min). These data suggest that epicatechin induces cellular survival through a tight regulation of survival/proliferation pathways that requires the integration of different signals and persists over time, the ultimate effect on HepG2 cells being regulated by the balance among these signals.

  3. Survival trees for left-truncated and right-censored data, with application to time-varying covariate data.

    PubMed

    Fu, Wei; Simonoff, Jeffrey S

    2016-12-26

    SUMMARYTree methods (recursive partitioning) are a popular class of nonparametric methods for analyzing data. One extension of the basic tree methodology is the survival tree, which applies recursive partitioning to censored survival data. There are several existing survival tree methods in the literature, which are mainly designed for right-censored data. We propose two new survival trees for left-truncated and right-censored (LTRC) data, which can be seen as a generalization of the traditional survival tree for right-censored data. Further, we show that such trees can be used to analyze survival data with time-varying covariates, essentially building a time-varying covariates survival tree. Implementation of the methods is easy, and simulations and real data analysis results show that the proposed methods work well for LTRC data and survival data with time-varying covariates, respectively.

  4. Effects of hyperbaric oxygenation on survival time of aluminum phosphide intoxicated rats

    PubMed Central

    Saidi, Hossein; Shokraneh, Farhad; Ghafouri, Hamed-Basir; Shojaie, Shayan

    2011-01-01

    BACKGROUND: Aluminium phosphide (AlP) is used as a fumigant. It produces phosphine gas which is a mitochondrial poison. Although this poisoning has been repeatedly reported in literature with a high mortality rate, there is no known antidote for AlP intoxication. In the present study, we studied the effects of hyperbaric oxygenation (HBO) on the survival time of AlP intoxicated rats. METHODS: Intoxicated rats with AlP (11.5 mg/kg, oral gavage) were placed in hyperbaric oxygenation with different concentrations of compressed air and oxygen. RESULTS: All the animals exposed to AlP died within 5 days. The mean survival times of rats exposed to AlP without any intervention, treated with hyperbaric condition by compressed air, and treated with hyperbaric condition by pure O2 were 91 ± 1, 262 ± 8, and 276 ± 6 minutes, respectively. In analysis of survival times, there was a significant difference between Group 2 which received AlP and the groups which underwent intervention (Groups 2 and 3, p < 0.001; Groups 2 and 4, p < 0.001). CONCLUSIONS: Hyperbaric oxygenation may probably improve the survival time of the intoxicated rats with aluminium phosphide, but it may not decrease the mortality rate. PMID:22973324

  5. Parental Monitoring during Early Adolescence Deters Adolescent Sexual Initiation: Discrete-Time Survival Mixture Analysis

    ERIC Educational Resources Information Center

    Huang, David Y. C.; Murphy, Debra A.; Hser, Yih-Ing

    2011-01-01

    We used discrete-time survival mixture modeling to examine 5,305 adolescents from the 1997 National Longitudinal Survey of Youth regarding the impact of parental monitoring during early adolescence (ages 14-16) on initiation of sexual intercourse and problem behavior engagement (ages 14-23). Four distinctive parental-monitoring groups were…

  6. Identifying novel clinical surrogates to assess human bone fracture toughness

    PubMed Central

    Granke, Mathilde; Makowski, Alexander J; Uppuganti, Sasidhar; Does, Mark D; Nyman, Jeffry S

    2015-01-01

    Fracture risk does not solely depend on strength but also on fracture toughness, i.e. the ability of bone material to resist crack initiation and propagation. Because resistance to crack growth largely depends on bone properties at the tissue level including collagen characteristics, current X-ray based assessment tools may not be suitable to identify age-, disease-, or treatment-related changes in fracture toughness. To identify useful clinical surrogates that could improve the assessment of fracture resistance, we investigated the potential of 1H nuclear magnetic resonance spectroscopy (NMR) and reference point indentation (RPI) to explain age-related variance in fracture toughness. Harvested from cadaveric femurs (62 human donors), single-edge notched beam (SENB) specimens of cortical bone underwent fracture toughness testing (R-curve method). NMR-derived bound water showed the strongest correlation with fracture toughness properties (r=0.63 for crack initiation, r=0.35 for crack growth, and r=0.45 for overall fracture toughness; p<0.01). Multivariate analyses indicated that the age-related decrease in different fracture toughness properties were best explained by a combination of NMR properties including pore water and RPI-derived tissue stiffness with age as a significant covariate (adjusted R2 = 53.3%, 23.9%, and 35.2% for crack initiation, crack growth, and overall toughness, respectively; p<0.001). These findings reflect the existence of many contributors to fracture toughness and emphasize the utility of a multimodal assessment of fracture resistance. Exploring the mechanistic origin of fracture toughness, glycation-mediated, non-enzymatic collagen crosslinks and intra-cortical porosity are possible determinants of bone fracture toughness and could explain the sensitivity of NMR to changes in fracture toughness. Assuming fracture toughness is clinically important to the ability of bone to resist fracture, our results suggest that improvements in fracture

  7. Identifying Novel Clinical Surrogates to Assess Human Bone Fracture Toughness.

    PubMed

    Granke, Mathilde; Makowski, Alexander J; Uppuganti, Sasidhar; Does, Mark D; Nyman, Jeffry S

    2015-07-01

    Fracture risk does not solely depend on strength but also on fracture toughness; ie, the ability of bone material to resist crack initiation and propagation. Because resistance to crack growth largely depends on bone properties at the tissue level, including collagen characteristics, current X-ray based assessment tools may not be suitable to identify age-related, disease-related, or treatment-related changes in fracture toughness. To identify useful clinical surrogates that could improve the assessment of fracture resistance, we investigated the potential of (1)H nuclear magnetic resonance spectroscopy (NMR) and reference point indentation (RPI) to explain age-related variance in fracture toughness. Harvested from cadaveric femurs (62 human donors), single-edge notched beam (SENB) specimens of cortical bone underwent fracture toughness testing (R-curve method). NMR-derived bound water showed the strongest correlation with fracture toughness properties (r = 0.63 for crack initiation, r = 0.35 for crack growth, and r = 0.45 for overall fracture toughness; p < 0.01). Multivariate analyses indicated that the age-related decrease in different fracture toughness properties were best explained by a combination of NMR properties including pore water and RPI-derived tissue stiffness with age as a significant covariate (adjusted R(2)  = 53.3%, 23.9%, and 35.2% for crack initiation, crack growth, and overall toughness, respectively; p < 0.001). These findings reflect the existence of many contributors to fracture toughness and emphasize the utility of a multimodal assessment of fracture resistance. Exploring the mechanistic origin of fracture toughness, glycation-mediated nonenzymatic collagen crosslinks and intracortical porosity are possible determinants of bone fracture toughness and could explain the sensitivity of NMR to changes in fracture toughness. Assuming fracture toughness is clinically important to the ability of bone to resist fracture

  8. A multivariate model for the meta-analysis of study level survival data at multiple times.

    PubMed

    Jackson, Dan; Rollins, Katie; Coughlin, Patrick

    2014-09-01

    Motivated by our meta-analytic dataset involving survival rates after treatment for critical leg ischemia, we develop and apply a new multivariate model for the meta-analysis of study level survival data at multiple times. Our data set involves 50 studies that provide mortality rates at up to seven time points, which we model simultaneously, and we compare the results to those obtained from standard methodologies. Our method uses exact binomial within-study distributions and enforces the constraints that both the study specific and the overall mortality rates must not decrease over time. We directly model the probabilities of mortality at each time point, which are the quantities of primary clinical interest. We also present I(2) statistics that quantify the impact of the between-study heterogeneity, which is very considerable in our data set.

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

    PubMed Central

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

    2015-01-01

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

  10. Tough choices in tough times: debt and medication nonadherence.

    PubMed

    Kalousova, Lucie; Burgard, Sarah A

    2014-04-01

    Debt is a ubiquitous component of households' financial portfolios. Yet we have scant understanding of how household debt constrains spending on needed health care. Diverse types of debt have different financial properties and recent work has shown that they may have varying implications for spending on needed health care. In this article, we explore the associations between indebtedness and medication nonadherence. First, we consider overall debt levels and then we disaggregate debt into types. We use a population-based sample of 434 residents of southeast Michigan who had been prescribed medications, collected in 2009-2010, the wake of the Great Recession. We find no association between medication nonadherence and total indebtedness. However, when we assess each type of debt separately, we find that having medical or credit card debt is positively associated with medication nonadherence, even net of household income, net worth, and other characteristics. Furthermore, patients with greater amounts of medical or credit card debt are more likely to be nonadherent than those with less. Our results suggest that credit card debt and medical debt may have serious implications for the relative affordability of prescription medications. These associations have been overlooked in past research and deserve further examination.

  11. Tough Choices in Tough Times: Debt and Medication Nonadherence

    ERIC Educational Resources Information Center

    Kalousova, Lucie; Burgard, Sarah A.

    2014-01-01

    Debt is a ubiquitous component of households' financial portfolios. Yet we have scant understanding of how household debt constrains spending on needed health care. Diverse types of debt have different financial properties and recent work has shown that they may have varying implications for spending on needed health care. In this article, we…

  12. Sampling-time effects for persistence and survival in step structural fluctuations.

    PubMed

    Dougherty, D B; Tao, C; Bondarchuk, O; Cullen, W G; Williams, E D; Constantin, M; Dasgupta, C; Das Sarma, S

    2005-02-01

    The effects of sampling rate and total measurement time have been determined for single-point measurements of step fluctuations within the context of first-passage properties. Time dependent scanning tunneling microscopy has been used to evaluate step fluctuations on Ag(111) films grown on mica as a function of temperature (300-410 K) , on screw dislocations on the facets of Pb crystallites at 320 K , and on Al-terminated Si(111) over the temperature range 770-970 K . Although the fundamental time constant for step fluctuations on Ag and Al/Si varies by orders of magnitude over the temperature ranges of measurement, no dependence of the persistence amplitude on temperature is observed. Instead, the persistence probability is found to scale directly with t/delta t where delta t is the time interval used for sampling. Survival probabilities show a more complex scaling dependence, which includes both the sampling interval and the total measurement time t(m) . Scaling with t/delta t occurs only when delta t/ t(m) is a constant. We show that this observation is equivalent to theoretical predictions that the survival probability will scale as delta t/ L(z) , where L is the effective length of a step. This implies that the survival probability for large systems, when measured with fixed values of t(m) or delta t , should also show little or no temperature dependence.

  13. Super-tough carbon-nanotube fibres

    NASA Astrophysics Data System (ADS)

    Dalton, Alan B.; Collins, Steve; Muñoz, Edgar; Razal, Joselito M.; Ebron, Von Howard; Ferraris, John P.; Coleman, Jonathan N.; Kim, Bog G.; Baughman, Ray H.

    2003-06-01

    The energy needed to rupture a fibre (its toughness) is five times higher for spider silk than for the same mass of steel wire, which has inspired efforts to produce spider silk commercially. Here we spin 100-metre-long carbon-nanotube composite fibres that are tougher than any natural or synthetic organic fibre described so far, and use these to make fibre supercapacitors that are suitable for weaving into textiles.

  14. Time and size at seaward migration influence the sea survival of Salmo salar.

    PubMed

    Jonsson, N; Jonsson, B

    2014-05-01

    Whether time of seaward migration of young Atlantic salmon Salmo salar influences their subsequent survival and growth was investigated in the River Imsa, south-western Norway. Salmo salar were tagged when moving downstream through a trap near the outlet between 1976 and 2010 and recaptured on their adult return. Most descended as smolts in April and May, but some descended during the other months of the year. Annual variation in timing of the smolt migration was significantly correlated with variation in water temperature during spring. Mean total body length of the descending S. salar varied with month of seaward migration. The sea survival of S. salar emigrating from the River Imsa between January and May was 2·8 times higher than for those descending between June and December. The sea survival of the various cohorts decreased with increasing river temperature in April to May, prior to the smolt migration, and decreasing day number when the smolts moved to sea. The size of smolts descending the river between April and May did not affect the survival at sea as much as it affected the survival of migrants descending in any other month of the year. The majority of the downstream migrating S. salar were 2 years old, but proportionally, more 1 year olds moved downstream in the autumn than in the rest of the year. Mean duration between downstream migration of the young and the return migration of the grilse was shortest (12·7 months) for those descending in July and August and longest for those descending in October (21 months). Mean monthly specific growth rate was highest for those migrating downstream between May and July and lowest for those emigrating in September. Based on the present results, it was hypothesized that S. salar emigrating between April and August migrated directly out into the ocean, while those that emigrated between October and March stayed in the estuary until the subsequent spring.

  15. Toughness Properties of Nodular Iron

    NASA Astrophysics Data System (ADS)

    Bradley, Walter L.

    1985-01-01

    The German government recently certified ductile iron for construction of nuclear waste transport containers. This approved use of ductile iron for such a critical application represents the culmination of ten years worth of research bringing to light the surprising toughness of ductile iron. This article explains how modern fracture mechanics and microstructure/property relationships have altered the stereotype of ductile iron as a low toughness material.

  16. Predicting the Survival Time for Bladder Cancer Using an Additive Hazards Model in Microarray Data

    PubMed Central

    TAPAK, Leili; MAHJUB, Hossein; SADEGHIFAR, Majid; SAIDIJAM, Massoud; POOROLAJAL, Jalal

    2016-01-01

    Background: One substantial part of microarray studies is to predict patients’ survival based on their gene expression profile. Variable selection techniques are powerful tools to handle high dimensionality in analysis of microarray data. However, these techniques have not been investigated in competing risks setting. This study aimed to investigate the performance of four sparse variable selection methods in estimating the survival time. Methods: The data included 1381 gene expression measurements and clinical information from 301 patients with bladder cancer operated in the years 1987 to 2000 in hospitals in Denmark, Sweden, Spain, France, and England. Four methods of the least absolute shrinkage and selection operator, smoothly clipped absolute deviation, the smooth integration of counting and absolute deviation and elastic net were utilized for simultaneous variable selection and estimation under an additive hazards model. The criteria of area under ROC curve, Brier score and c-index were used to compare the methods. Results: The median follow-up time for all patients was 47 months. The elastic net approach was indicated to outperform other methods. The elastic net had the lowest integrated Brier score (0.137±0.07) and the greatest median of the over-time AUC and C-index (0.803±0.06 and 0.779±0.13, respectively). Five out of 19 selected genes by the elastic net were significant (P<0.05) under an additive hazards model. It was indicated that the expression of RTN4, SON, IGF1R and CDC20 decrease the survival time, while the expression of SMARCAD1 increase it. Conclusion: The elastic net had higher capability than the other methods for the prediction of survival time in patients with bladder cancer in the presence of competing risks base on additive hazards model. PMID:27114989

  17. Role of Survival Time and Injury Severity in Fatal Pulmonary Fat Embolism.

    PubMed

    Jarmer, Juliane; Ampanozi, Garyfalia; Thali, Michael J; Bolliger, Stephan A

    2017-03-01

    Pulmonary fat embolism (PFE) is frequent in blunt trauma and may occasionally lead to death. A correlation between fracture grade and severity and PFE grade has been described before, but no correlation between PFE and survival time, fat crushing extent, fat crush grade, or number of body regions with fractures could be noted in this small study. To further examine this, we decided to examine the aforementioned points in a far larger study group.Autopsy protocols of 188 nonresuscitated fatalities with blunt trauma and without right heart injury, which underwent whole body dissection, were retrospectively reviewed concerning the presence and the severity of PFE, injuries, survival time, age, sex, and the body mass index.The fracture grade, the fracture severity, and the number of the fractured regions correlated very well with the grade of PFE, but the crushed regions, crush grade, and crush severity did not. We observed a time correlation between survival time and PFE only in the sense that very rapid deaths were often PFE negative. High-grade PFE was observed most often in patients having died less than 6 hours after the incident, and PFE grades of 2 or more were occasionally noted even after 48 hours.

  18. Warming affects hatching time and early season survival of eastern tent caterpillars.

    PubMed

    Abarca, Mariana; Lill, John T

    2015-11-01

    Climate change is disrupting species interactions by altering the timing of phenological events such as budburst for plants and hatching for insects. We combined field observations with laboratory manipulations to investigate the consequences of climate warming on the phenology and performance of the eastern tent caterpillar (Malacosoma americanum). We evaluated the effects of warmer winter and spring regimes on caterpillar hatching patterns and starvation endurance, traits likely to be under selection in populations experiencing phenological asynchrony, using individuals from two different populations (Washington, DC, and Roswell, GA). We also quantified the proximate and extended fitness effects of early food deprivation and recorded spring phenology of local caterpillars and their host plants. In addition, we conducted laboratory assays to determine if caterpillars are using plant chemical cues to fine-tune their hatching times. Warmer winter temperatures induced earlier hatching and caterpillars from GA survived starvation for periods that were 30% longer than caterpillars from DC. Warmer spring regimes reduced the starvation endurance of caterpillars overwintering in the wild but not in the laboratory. Early starvation dramatically reduced hatchling survival; however, surviving caterpillars did not show detrimental effects on pupal mass or development time. In the field, hatching preceded budburst in both 2013 and 2014 and the period of optimal foliage quality was 2 weeks shorter in 2013. Hatching time was unaffected by exposure to plant volatiles. Overall, we found that warmer temperatures can trigger late-season asynchrony by accelerating plant phenology and caterpillars from different populations exhibit differential abilities to cope with environmental unreliability.

  19. Reduction in predicted survival times in cold water due to wind and waves.

    PubMed

    Power, Jonathan; Simões Ré, António; Barwood, Martin; Tikuisis, Peter; Tipton, Michael

    2015-07-01

    Recent marine accidents have called into question the level of protection provided by immersion suits in real (harsh) life situations. Two immersion suit studies, one dry and the other with 500 mL of water underneath the suit, were conducted in cold water with 10-12 males in each to test body heat loss under three environmental conditions: calm, as mandated for immersion suit certification, and two combinations of wind plus waves to simulate conditions typically found offshore. In both studies mean skin heat loss was higher in wind and waves vs. calm; deep body temperature and oxygen consumption were not different. Mean survival time predictions exceeded 36 h for all conditions in the first study but were markedly less in the second in both calm and wind and waves. Immersion suit protection and consequential predicted survival times under realistic environmental conditions and with leakage are reduced relative to calm conditions.

  20. Does induction time of mild hypothermia influence the survival duration of septic rats?

    PubMed

    Léon, Karelle; Pichavant-Rafini, Karine; Ollivier, Hélène; Monbet, Valérie; L'Her, Erwan

    2015-06-01

    The relationship between hypothermia induction time and survival duration following sepsis was studied on 31 male Sprague-Dawley rats (median weight 311 g, range 260-356 g). After anesthesia and when the target temperature was reached (normothermia: 38°C or mild induced hypothermia: 34°C), sepsis was induced by cecal ligation and perforation. Five experimental groups were used. In groups 1 and 2, temperature of septic rats was maintained throughout the experiment at 38°C (seven rats) or 34°C (six rats), respectively. In groups 3, 4, and 5, septic rats (six per group) were maintained at 38°C for 1, 2, and 3 hours, respectively, and then placed in mild hypothermia (34°C). For each group, the survival duration was determined and blood samples were performed at the tail to measure tumor necrosis factor-α (TNF-α) plasma concentration. Whatever the experimental group, a decrease in temperature from 38°C to 34°C significantly increased the survival duration of septic rats compared with those maintained at 38°C throughout the experiment. The delay between the onset of sepsis and induction of hypothermia was also crucial. Thus, hypothermia induced after 1 hour of sepsis at 38°C significantly increased the survival duration of septic rats (12 hours 37 minutes±1 hour 4 minutes; group 3) compared with hypothermia induced after 3 hours of sepsis (8 hours 56 minutes±1 h 20 minutes; group 5). Moreover, except for group 5, survival duration improvement of septic rats observed in hypothermia was related to a lower increase of TNF-α plasma concentration compared with septic rats in normothermia. During sepsis, mild induced hypothermia significantly increased the survival duration of septic rats. The earlier hypothermia was applied, the longer the septic rats survived. According to these results, hypothermia may therefore provide the necessary time to apply a proper treatment.

  1. Survivable architectures for time and wavelength division multiplexed passive optical networks

    NASA Astrophysics Data System (ADS)

    Wong, Elaine

    2014-08-01

    The increased network reach and customer base of next-generation time and wavelength division multiplexed PON (TWDM-PONs) have necessitated rapid fault detection and subsequent restoration of services to its users. However, direct application of existing solutions for conventional PONs to TWDM-PONs is unsuitable as these schemes rely on the loss of signal (LOS) of upstream transmissions to trigger protection switching. As TWDM-PONs are required to potentially use sleep/doze mode optical network units (ONU), the loss of upstream transmission from a sleeping or dozing ONU could erroneously trigger protection switching. Further, TWDM-PONs require its monitoring modules for fiber/device fault detection to be more sensitive than those typically deployed in conventional PONs. To address the above issues, three survivable architectures that are compliant with TWDM-PON specifications are presented in this work. These architectures combine rapid detection and protection switching against multipoint failure, and most importantly do not rely on upstream transmissions for LOS activation. Survivability analyses as well as evaluations of the additional costs incurred to achieve survivability are performed and compared to the unprotected TWDM-PON. Network parameters that impact the maximum achievable network reach, maximum split ratio, connection availability, fault impact, and the incremental reliability costs for each proposed survivable architecture are highlighted.

  2. Effect of loading time on the survival rate of anodic oxidized implants: prospective multicenter study

    PubMed Central

    Kim, Seok-Gyu; Yun, Pil-Young; Park, Hyun-Sik; Shim, June-Sung; Hwang, Jung-Won

    2012-01-01

    PURPOSE The purpose of this prospective study was to evaluate the effect of early loading on survival rate or clinical parameter of anodic oxidized implants during the 12-month postloading period. MATERIALS AND METHODS Total 69 implants were placed in 42 patients. Anodic oxidized implants (GS II, Osstem Cor., Busan, Korea) placed on the posterior mandibles were divided into two groups, according to their prosthetic loading times: test group (2 to 6 weeks), and control group (3 to 4 months). The implant survival rates were determined during one-year postloading period and analyzed by Kaplan-Meier method. The radiographic peri-implant bone loss and periodontal parameters were also evaluated and statistically analyzed by unpaired t-test. RESULTS Total 69 implants were placed in 42 patients. The cumulative postloading implant survival rates were 88.89% in test group, compared to 100% in control group (P<.05). Periimplant marginal bone loss (T: 0.27±0.54 mm, C: 0.40±0.55 mm) and periodontal parameters showed no significant difference between the groups (P>.05). CONCLUSION Within the limitation of the present study, implant survival was affected by early loading on the anodic oxidized implants placed on posterior mandibles during one-year follow-up. Early implant loading did not influence peri-implant marginal bone loss, and periodontal parameters. PMID:22439096

  3. Mediation Analysis with Survival Outcomes: Accelerated Failure Time vs. Proportional Hazards Models

    PubMed Central

    Gelfand, Lois A.; MacKinnon, David P.; DeRubeis, Robert J.; Baraldi, Amanda N.

    2016-01-01

    Objective: Survival time is an important type of outcome variable in treatment research. Currently, limited guidance is available regarding performing mediation analyses with survival outcomes, which generally do not have normally distributed errors, and contain unobserved (censored) events. We present considerations for choosing an approach, using a comparison of semi-parametric proportional hazards (PH) and fully parametric accelerated failure time (AFT) approaches for illustration. Method: We compare PH and AFT models and procedures in their integration into mediation models and review their ability to produce coefficients that estimate causal effects. Using simulation studies modeling Weibull-distributed survival times, we compare statistical properties of mediation analyses incorporating PH and AFT approaches (employing SAS procedures PHREG and LIFEREG, respectively) under varied data conditions, some including censoring. A simulated data set illustrates the findings. Results: AFT models integrate more easily than PH models into mediation models. Furthermore, mediation analyses incorporating LIFEREG produce coefficients that can estimate causal effects, and demonstrate superior statistical properties. Censoring introduces bias in the coefficient estimate representing the treatment effect on outcome—underestimation in LIFEREG, and overestimation in PHREG. With LIFEREG, this bias can be addressed using an alternative estimate obtained from combining other coefficients, whereas this is not possible with PHREG. Conclusions: When Weibull assumptions are not violated, there are compelling advantages to using LIFEREG over PHREG for mediation analyses involving survival-time outcomes. Irrespective of the procedures used, the interpretation of coefficients, effects of censoring on coefficient estimates, and statistical properties should be taken into account when reporting results. PMID:27065906

  4. Factors affecting survival time of cholangiocarcinoma patients: a prospective study in Northeast Thailand.

    PubMed

    Woradet, Somkiattiyos; Promthet, Supannee; Songserm, Nopparat; Parkin, Donald Maxwell

    2013-01-01

    Cholangiocarcinoma (CCA) is a major health problem and cause of death among people in Northeastern Thailand. In this prospective study 171 patients newly diagnosed with CCA by physicians in 5 tertiary hospitals in four provinces of northeastern of Thailand between February and July 2011 were followed up to January 2012. The outcome was survival time from diagnosis to death. A total of 758.4 person-months of follow-up were available. The mortality rate was 16.9 per 100 person-months (95%CI: 14.1-20.1). The median survival time among CCA patients was 4.3 months (95%CI: 3.3-5.1). Cox's proportional hazard model was used to study the independent effects of factors affecting survival time among patients. Statistically significant factors included advanced stage at diagnosis (HR: 2.5, 95%CI: 1.7-3.8), presentation with jaundice (HR: 1.7, 95%CI: 1.1-2.4) or ascites (HR: 2.8, 95%CI: 1.8-4.4), and positive serum carcinoembryonic antigen (HR: 2.3, 95%CI: 1.2-4.3). Patients who had received standard treatment had a better prognosis that those who did not (HR: 0.5, 95%CI: 0.3-0.7).

  5. Non-parametric estimation of the post-lead-time survival distribution of screen-detected cancer cases.

    PubMed

    Xu, J L; Prorok, P C

    1995-12-30

    The goal of screening programmes for cancer is early detection and treatment with a consequent reduction in mortality from the disease. Screening programmes need to assess the true benefit of screening, that is, the length of time of extension of survival beyond the time of advancement of diagnosis (lead-time). This paper presents a non-parametric method to estimate the survival function of the post-lead-time survival (or extra survival time) of screen-detected cancer cases based on the observed total life time, namely, the sum of the lead-time and the extra survival time. We apply the method to the well-known data set of the HIP (Health Insurance Plan of Greater New York) breast cancer screening study. We make comparisons with the survival of other groups of cancer cases not detected by screening such as interval cases, cases among individuals who refused screening, and randomized control cases. As compared with Walter and Stitt's model, in which they made parametric assumptions for the extra survival time, our non-parametric method provides a better fit to HIP data in the sense that our estimator for the total survival time has a smaller sum of squares of residuals.

  6. Time-dependent endpoints as predictors of overall survival in multiple myeloma

    PubMed Central

    2013-01-01

    Background Supporting health care sector decisions using time-dependent endpoints (TDEs) such as time to progression (TTP), progression-free survival (PFS), and event-free survival (EFS) remains controversial. This study estimated the quantitative relationship between median TDE and median overall survival (OS) in multiple myeloma (MM) patients. Methods Studies (excluding allogeneic transplantation) published from 1970 to 2011 were systematically searched (PubMed). The nonparametric Spearman’s rank correlation coefficient measured the association between median TDE and OS. The quantitative relationship between TDEs and OS was estimated with a two-step approach to a simultaneous Tobit model. Results We identified 153 studies: 230 treatment arms, 22,696 patients and mean study duration of 3.8 years. Mean of median TDEs was 22.5 months and median OS was 39.1 months. Correlation coefficients of median TTP, PFS, and EFS with median OS were 0.51 (P = 0.003), 0.75 (P < 0.0001), and 0.84 (P < 0.0001), respectively. We estimate a 2.5 month (95% confidence interval, 1.7–3.2) increase in median OS for each additional month reported for median TDEs. There was no evidence that this relationship differed by type of surrogate. Conclusion TDEs predict OS in MM patients; this relationship may be valuable in clinical trial design, drug comparisons, and economic evaluation. PMID:23497363

  7. Measurement of Survival Time in Brachionus Rotifers: Synchronization of Maternal Conditions

    PubMed Central

    Kaneko, Gen; Yoshinaga, Tatsuki; Gribble, Kristin E.; Welch, David M.; Ushio, Hideki

    2017-01-01

    Rotifers are microscopic cosmopolitan zooplankton used as models in ecotoxicological and aging studies due to their several advantages such as short lifespan, ease of culture, and parthenogenesis that enables clonal culture. However, caution is required when measuring their survival time as it is affected by maternal age and maternal feeding conditions. Here we provide a protocol for powerful and reproducible measurement of the survival time in Brachionus rotifers following a careful synchronization of culture conditions over several generations. Empirically, poor synchronization results in early mortality and a gradual decrease in survival rate, thus resulting in weak statistical power. Indeed, under such conditions, calorie restriction (CR) failed to significantly extend the lifespan of B. plicatilis although CR-induced longevity has been demonstrated with well-synchronized rotifer samples in past and present studies. This protocol is probably useful for other invertebrate models, including the fruitfly Drosophila melanogaster and the nematode Caenorhabditis elegans, because maternal age effects have also been reported in these species. PMID:27500471

  8. Tough Blends of Polylactide and Castor Oil

    SciTech Connect

    Robertson, Megan L.; Paxton, Jessica M.; Hillmyer, Marc A.

    2012-10-10

    Poly(l-lactide) (PLLA) is a renewable resource polymer derived from plant sugars with several commercial applications. Broader implementation of the material is limited due to its inherent brittleness. We show that the addition of 5 wt % castor oil to PLLA significantly enhances the overall tensile toughness with minimal reductions in the modulus and no plasticization of the PLLA matrix. In addition, we used poly(ricinoleic acid)-PLLA diblock copolymers, synthesized entirely from renewable resources, as compatibilizers for the PLLA/castor oil blends. Ricinoleic acid, the majority fatty acid comprising castor oil, was polymerized through a lipase-catalyzed condensation reaction. The resulting polymers contained a hydroxyl end-group that was subsequently used to initiate the ring-opening polymerization of L-lactide. The binary PLLA/castor oil blend exhibited a tensile toughness seven times greater than neat PLLA. The addition of block copolymer allowed for control over the morphology of the blends, and even further improvement in the tensile toughness was realized - an order of magnitude larger than that of neat PLLA.

  9. Tough blends of polylactide and castor oil.

    PubMed

    Robertson, Megan L; Paxton, Jessica M; Hillmyer, Marc A

    2011-09-01

    Poly(l-lactide) (PLLA) is a renewable resource polymer derived from plant sugars with several commercial applications. Broader implementation of the material is limited due to its inherent brittleness. We show that the addition of 5 wt % castor oil to PLLA significantly enhances the overall tensile toughness with minimal reductions in the modulus and no plasticization of the PLLA matrix. In addition, we used poly(ricinoleic acid)-PLLA diblock copolymers, synthesized entirely from renewable resources, as compatibilizers for the PLLA/castor oil blends. Ricinoleic acid, the majority fatty acid comprising castor oil, was polymerized through a lipase-catalyzed condensation reaction. The resulting polymers contained a hydroxyl end-group that was subsequently used to initiate the ring-opening polymerization of l-lactide. The binary PLLA/castor oil blend exhibited a tensile toughness seven times greater than neat PLLA. The addition of block copolymer allowed for control over the morphology of the blends, and even further improvement in the tensile toughness was realized-an order of magnitude larger than that of neat PLLA.

  10. Fracture toughness design in horse hoof keratin.

    PubMed

    Bertram, J E; Gosline, J M

    1986-09-01

    An engineering fracture mechanics approach was applied to the analysis of the fracture resistance of equine hoof-wall. The relationship between fracture toughness and the morphological organization of the keratin hoof tissue was investigated. Fracture toughness was evaluated using the J-integral analysis method which employs the compact tension test geometry. Tensile tests were also conducted to evaluate the effect of the morphological organization on the stress-strain behaviour. Hoof-wall has greatest fracture resistance for cracks running proximally, parallel to the tubular component of the wall keratin. For fully hydrated material tested in this direction the mean critical J-integral value at failure was 1.19 X 10(4)J m-2. This was nearly three times greater than the value determined for the weakest orientation, in which the crack ran parallel to the material between the tubules. The lower fracture toughness of the intertubular material dominates the fracture behaviour of this tissue. The tubular components of the wall appear to reinforce against fracture along the weak plane and the entire wall organization provides the mechanical capability for limiting and controlling fracture in this tissue.

  11. Time-Dependent Tree-Structured Survival Analysis with Unbiased Variable Selection through Permutation Tests

    PubMed Central

    Wallace, M. L.

    2014-01-01

    Incorporating time-dependent covariates into tree-structured survival analysis (TSSA) may result in more accurate prognostic models than if only baseline values are used. Available time-dependent TSSA methods exhaustively test every binary split on every covariate; however, this approach may result in selection bias towards covariates with more observed values. We present a method that uses unbiased significance levels from newly proposed permutation tests to select the time-dependent or baseline covariate with the strongest relationship with the survival outcome. The specific splitting value is identified using only the selected covariate. Simulation results show that the proposed time-dependent TSSA method produces tree models of equal or greater accuracy as compared to baseline TSSA models, even with high censoring rates and large within-subject variability in the time-dependent covariate. To illustrate, the proposed method is applied to data from a cohort of bipolar youth to identify subgroups at risk for self-injurious behavior. PMID:25043382

  12. Anomalous scaling law of strength and toughness of cellulose nanopaper

    PubMed Central

    Zhu, Hongli; Zhu, Shuze; Jia, Zheng; Parvinian, Sepideh; Li, Yuanyuan; Vaaland, Oeyvind; Hu, Liangbing; Li, Teng

    2015-01-01

    The quest for both strength and toughness is perpetual in advanced material design; unfortunately, these two mechanical properties are generally mutually exclusive. So far there exists only limited success of attaining both strength and toughness, which often needs material-specific, complicated, or expensive synthesis processes and thus can hardly be applicable to other materials. A general mechanism to address the conflict between strength and toughness still remains elusive. Here we report a first-of-its-kind study of the dependence of strength and toughness of cellulose nanopaper on the size of the constituent cellulose fibers. Surprisingly, we find that both the strength and toughness of cellulose nanopaper increase simultaneously (40 and 130 times, respectively) as the size of the constituent cellulose fibers decreases (from a mean diameter of 27 μm to 11 nm), revealing an anomalous but highly desirable scaling law of the mechanical properties of cellulose nanopaper: the smaller, the stronger and the tougher. Further fundamental mechanistic studies reveal that reduced intrinsic defect size and facile (re)formation of strong hydrogen bonding among cellulose molecular chains is the underlying key to this new scaling law of mechanical properties. These mechanistic findings are generally applicable to other material building blocks, and therefore open up abundant opportunities to use the fundamental bottom-up strategy to design a new class of functional materials that are both strong and tough. PMID:26150482

  13. Time-Dependence of the Survival Probability of Quarkonia in Quark-Gluon Plasma

    NASA Astrophysics Data System (ADS)

    Mah Hussin, Noor Sabrina; Shalaby, Asmaa; Petridis, Athanasios

    2015-10-01

    The time-dependent Schrödinger equation is used to study the formation of quarkonia and their propagation in Quark-Gluon Plasma (QGP). The initial bound (ground) state is computed using imaginary-time propagation in a confining potential. The QGP is simulated with a confining potential of an extended asymptotic freedom region. The interior of the QGP potential may correspond to a vacuum that differs from that of the exterior region. The initial state propagates through this potential in real time. The survival probability is calculated versus time for various potential parameters and relative momenta of the quarkonium by projecting the interacting wavefunction onto its freely-propagating counterpart. In these calculations the staggered-leap frog method is used with special attention paid to the issue of stability. It is found that quarkonium decay is typically non-exponential. Fast moving states decay faster. Connection with experimental results is done by means of cross-section ratios.

  14. Nest survival patterns in Eurasian Bittern: effect of nest age, time and habitat variables.

    PubMed

    Polak, Marcin

    2016-01-01

    Determining the key factors affecting the reproductive success of nesting birds is crucial in order to better understand the population dynamics of endangered species and to introduce effective conservation programmes for them. Inhabiting a variety of wetland habitats, aquatic birds actively select safe nesting sites so as to protect their nests against predators. The main aim of the present work was to assess the effect of temporal and habitat variables on the daily nest survival rate of Eurasian Bitterns colonizing semi-natural fishpond habitat in eastern Poland. MARK software was used for the modelling. Eurasian Bittern nests were most vulnerable to depredation at the beginning of the breeding season. This was probably because the reedbed vegetation at this time was not yet dense enough to effectively conceal the nests. There was a positive relationship between nest age and the daily survival rate. Two of the habitat variables analysed were of the greatest significance: water depth and vegetation density. In the Eurasian Bittern population studied here, nests built over deep water and in dense vegetation had the best chances of survival. The results of this work may be useful in the preparation of plans for the conservation and management of populations of this rare and endangered species. Conservation and restoration efforts that attempt to maintain high water levels will be especially beneficial to this avian species that is dependent on wetland ecosystems for breeding.

  15. A Parallelized Pumpless Artificial Placenta System Significantly Prolonged Survival Time in a Preterm Lamb Model.

    PubMed

    Miura, Yuichiro; Matsuda, Tadashi; Usuda, Haruo; Watanabe, Shimpei; Kitanishi, Ryuta; Saito, Masatoshi; Hanita, Takushi; Kobayashi, Yoshiyasu

    2016-05-01

    An artificial placenta (AP) is an arterio-venous extracorporeal life support system that is connected to the fetal circulation via the umbilical vasculature. Previously, we published an article describing a pumpless AP system with a small priming volume. We subsequently developed a parallelized system, hypothesizing that the reduced circuit resistance conveyed by this modification would enable healthy fetal survival time to be prolonged. We conducted experiments using a premature lamb model to test this hypothesis. As a result, the fetal survival period was significantly prolonged (60.4 ± 3.8 vs. 18.2 ± 3.2 h, P < 0.01), and circuit resistance and minimal blood lactate levels were significantly lower in the parallel circuit group, compared with our previous single circuit group. Fetal physiological parameters remained stable until the conclusion of the experiments. In summary, parallelization of the AP system was associated with reduced circuit resistance and lactate levels and allowed preterm lamb fetuses to survive for a significantly longer period when compared with previous studies.

  16. Nest survival patterns in Eurasian Bittern: effect of nest age, time and habitat variables

    PubMed Central

    2016-01-01

    Determining the key factors affecting the reproductive success of nesting birds is crucial in order to better understand the population dynamics of endangered species and to introduce effective conservation programmes for them. Inhabiting a variety of wetland habitats, aquatic birds actively select safe nesting sites so as to protect their nests against predators. The main aim of the present work was to assess the effect of temporal and habitat variables on the daily nest survival rate of Eurasian Bitterns colonizing semi–natural fishpond habitat in eastern Poland. MARK software was used for the modelling. Eurasian Bittern nests were most vulnerable to depredation at the beginning of the breeding season. This was probably because the reedbed vegetation at this time was not yet dense enough to effectively conceal the nests. There was a positive relationship between nest age and the daily survival rate. Two of the habitat variables analysed were of the greatest significance: water depth and vegetation density. In the Eurasian Bittern population studied here, nests built over deep water and in dense vegetation had the best chances of survival. The results of this work may be useful in the preparation of plans for the conservation and management of populations of this rare and endangered species. Conservation and restoration efforts that attempt to maintain high water levels will be especially beneficial to this avian species that is dependent on wetland ecosystems for breeding. PMID:27350897

  17. Adjuvant Radiation Therapy Treatment Time Impacts Overall Survival in Gastric Cancer

    SciTech Connect

    McMillan, Matthew T.; Ojerholm, Eric; Roses, Robert E.; Plastaras, John P.; Metz, James M.; Mamtani, Ronac; Stripp, Diana; Ben-Josef, Edgar; Datta, Jashodeep

    2015-10-01

    Purpose: Prolonged radiation therapy treatment time (RTT) is associated with worse survival in several tumor types. This study investigated whether delays during adjuvant radiation therapy impact overall survival (OS) in gastric cancer. Methods and Materials: The National Cancer Data Base was queried for patients with resected gastric cancer who received adjuvant radiation therapy with National Comprehensive Cancer Network–recommended doses (45 or 50.4 Gy) between 1998 and 2006. RTT was classified as standard (45 Gy: 33-36 days, 50.4 Gy: 38-41 days) or prolonged (45 Gy: >36 days, 50.4 Gy: >41 days). Cox proportional hazards models evaluated the association between the following factors and OS: RTT, interval from surgery to radiation therapy initiation, interval from surgery to radiation therapy completion, radiation therapy dose, demographic/pathologic and operative factors, and other elements of adjuvant multimodality therapy. Results: Of 1591 patients, RTT was delayed in 732 (46%). Factors associated with prolonged RTT were non-private health insurance (OR 1.3, P=.005) and treatment at non-academic facilities (OR 1.2, P=.045). Median OS and 5-year actuarial survival were significantly worse in patients with prolonged RTT compared with standard RTT (36 vs 51 months, P=.001; 39 vs 47%, P=.005); OS worsened with each cumulative week of delay (P<.0004). On multivariable analysis, prolonged RTT was associated with inferior OS (hazard ratio 1.2, P=.002); the intervals from surgery to radiation therapy initiation or completion were not. Prolonged RTT was particularly detrimental in patients with node positivity, inadequate nodal staging (<15 nodes examined), and those undergoing a cycle of chemotherapy before chemoradiation therapy. Conclusions: Delays during adjuvant radiation therapy appear to negatively impact survival in gastric cancer. Efforts to minimize cumulative interruptions to <7 days should be considered.

  18. Survival Times of Meter-Sized Rock Boulders on the Surface of Airless Bodies

    NASA Technical Reports Server (NTRS)

    Basilevsky, A. T.; Head, J. W.; Horz, F.; Ramsley, K.

    2015-01-01

    This study considers the survival times of meter-sized rock boulders on the surfaces of several airless bodies. As the starting point, we employ estimates of the survival times of such boulders on the surface of the Moon by[1], then discuss the role of destruction due to day-night temperature cycling, consider the meteorite bombardment environment on the considered bodies in terms of projectile flux and velocities and finally estimate the survival times. Survival times of meter-sized rocks on lunar surface: The survival times of hand specimen-sized rocks exposed to the lunar surface environment were estimated based on experiments modeling the destruction of rocks by meteorite impacts, combined with measurements of the lunar surface meteorite flux, (e.g.,[2]). For estimations of the survival times of meter-sized lunar boulders, [1] suggested a different approach based on analysis of the spatial density of boulders on the rims of small lunar craters of known absolute age. It was found that for a few million years, only a small fraction of the boulders ejected by cratering process are destroyed, for several tens of million years approx.50% are destroyed, and for 200-300 Ma, 90 to 99% are destroyed. Following [2] and other works, [1] considered that the rocks are mostly destroyed by meteorite impacts. Destruction of rocks by thermal-stress. However, high diurnal temperature variations on the surface of the Moon and other airless bodies imply that thermal stresses may also be a cause of surface rock destruction. Delbo et al. [3] interpreted the observed presence of fine debris on the surface of small asteroids as due to thermal surface cycling. They stated that because of the very low gravity on the surface of these bodies, ejecta from meteorite impacts should leave the body, so formation there of fine debris has to be due to thermal cycling. Based on experiments on heating-cooling of cm-scale pieces of ordinary and carbonaceous chondrites and theoretical modeling of

  19. Analysis of Crack Arrest Toughness.

    DTIC Science & Technology

    1988-01-15

    vload(m) vp tn(m) Vertical Source Load (kN) on wedge HY80 Finite Element 0.0122 0.0099 3.81x10 -4 144 Steel Calculations Experiment 0.0122 --- 3.74x10-4...curve, are bona fide measures of the fracture arrest capability of tough ductile steels . The second is that the J-values represent the crack driving...fibrous mode of crack extension. (b) A new test method for studying fast fracture and arrest in tough steels . (c) Measurements of fast fracture and crack

  20. Ferrofluid flow for TOUGH2

    SciTech Connect

    Oldenburg, Curtis; Moridis, George

    1998-03-24

    We have developed EOS7M, a ferrofluid flow and transport module for TOUGH2. EOS7M calculates the magnetic forces on ferrofluid caused by an external magnetic field and allows simulation of flow and advective transport of ferrofluid-water mixtures through porous media. Such flow problems are strongly coupled and well suited to the TOUGH2 framework. Preliminary applications of EOS7M to some simple pressure and flow problems for which experiments were carried out in the lab show good qualitative agreement with the laboratory results.

  1. Nutritional status of patients with alcoholic cirrhosis undergoing liver transplantation: time trends and impact on survival.

    PubMed

    Singal, Ashwani K; Kamath, Patrick S; Francisco Ziller, Nickie; DiCecco, Sara; Shoreibah, M; Kremers, Walter; Charlton, Michael R; Heimbach, Julie K; Watt, Kymberly D; Shah, Vijay H

    2013-08-01

    Alcoholic cirrhotics evaluated for liver transplantation are frequently malnourished or obese. We analyzed alcoholic cirrhotics undergoing transplantation to examine time trends of nutrition/weight, transplant outcome, and effects of concomitant hepatitis C virus (HCV) and/or hepatocellular carcinoma (HCC). Nutrition and transplant outcomes were reviewed for alcoholic cirrhosis with/without HCV/HCC. Malnutrition was defined by subjective global assessment. Body mass index (BMI) classified obesity. A total of 261 patients receiving transplants were separated (1988-2000, 2001-2006, and 2007-2011) to generate similar size cohorts. Mean BMI for the whole cohort was 28 ± 6 with 68% classified as overweight/obese. Mean BMI did not vary among cohorts and was not affected by HCV/HCC. While prevalence of malnutrition did not vary among cohorts, it was lower in patients with HCV/HCC (P < 0.01). One-year graft/patient survival was 90% and not impacted by time period, HCV/HCC, or malnutrition after adjusting for demographics and model end-stage liver disease (MELD). Alcoholic cirrhotics undergoing transplantation are malnourished yet frequently overweight/obese. Among patients selected for transplantation, 1-year post-transplant graft/patient survival is excellent, have not changed over time, and do not vary by nutrition/BMI. Our findings support feasibility of liver transplantation for alcoholic cirrhotics with obesity and malnutrition.

  2. Using Concurrent Cardiovascular Information to Augment Survival Time Data from Orthostatic Tilt Tests

    NASA Technical Reports Server (NTRS)

    Feiveson, Alan H.; Fiedler, James; Lee, Stuart M. M.; Westby, Christian M.; Stenger, Michael B.; Platts, Steven H.

    2014-01-01

    Orthostatic Intolerance (OI) is the propensity to develop symptoms of fainting during upright standing. OI is associated with changes in heart rate, blood pressure and other measures of cardiac function. Problem: NASA astronauts have shown increased susceptibility to OI on return from space missions. Current methods for counteracting OI in astronauts include fluid loading and the use of compression garments. Multivariate trajectory spread is greater as OI increases. Pairwise comparisons at the same time within subjects allows incorporation of pass/fail outcomes. Path length, convex hull area, and covariance matrix determinant do well as statistics to summarize this spread Missing data problems Time series analysis need many more time points per OTT session treatment of trend? how incorporate survival information?

  3. Integrated survival analysis using an event-time approach in a Bayesian framework

    USGS Publications Warehouse

    Walsh, Daniel P.; Dreitz, VJ; Heisey, Dennis M.

    2015-01-01

    Event-time or continuous-time statistical approaches have been applied throughout the biostatistical literature and have led to numerous scientific advances. However, these techniques have traditionally relied on knowing failure times. This has limited application of these analyses, particularly, within the ecological field where fates of marked animals may be unknown. To address these limitations, we developed an integrated approach within a Bayesian framework to estimate hazard rates in the face of unknown fates. We combine failure/survival times from individuals whose fates are known and times of which are interval-censored with information from those whose fates are unknown, and model the process of detecting animals with unknown fates. This provides the foundation for our integrated model and permits necessary parameter estimation. We provide the Bayesian model, its derivation, and use simulation techniques to investigate the properties and performance of our approach under several scenarios. Lastly, we apply our estimation technique using a piece-wise constant hazard function to investigate the effects of year, age, chick size and sex, sex of the tending adult, and nesting habitat on mortality hazard rates of the endangered mountain plover (Charadrius montanus) chicks. Traditional models were inappropriate for this analysis because fates of some individual chicks were unknown due to failed radio transmitters. Simulations revealed biases of posterior mean estimates were minimal (≤ 4.95%), and posterior distributions behaved as expected with RMSE of the estimates decreasing as sample sizes, detection probability, and survival increased. We determined mortality hazard rates for plover chicks were highest at <5 days old and were lower for chicks with larger birth weights and/or whose nest was within agricultural habitats. Based on its performance, our approach greatly expands the range of problems for which event-time analyses can be used by eliminating the

  4. Integrated survival analysis using an event-time approach in a Bayesian framework

    PubMed Central

    Walsh, Daniel P; Dreitz, Victoria J; Heisey, Dennis M

    2015-01-01

    Event-time or continuous-time statistical approaches have been applied throughout the biostatistical literature and have led to numerous scientific advances. However, these techniques have traditionally relied on knowing failure times. This has limited application of these analyses, particularly, within the ecological field where fates of marked animals may be unknown. To address these limitations, we developed an integrated approach within a Bayesian framework to estimate hazard rates in the face of unknown fates. We combine failure/survival times from individuals whose fates are known and times of which are interval-censored with information from those whose fates are unknown, and model the process of detecting animals with unknown fates. This provides the foundation for our integrated model and permits necessary parameter estimation. We provide the Bayesian model, its derivation, and use simulation techniques to investigate the properties and performance of our approach under several scenarios. Lastly, we apply our estimation technique using a piece-wise constant hazard function to investigate the effects of year, age, chick size and sex, sex of the tending adult, and nesting habitat on mortality hazard rates of the endangered mountain plover (Charadrius montanus) chicks. Traditional models were inappropriate for this analysis because fates of some individual chicks were unknown due to failed radio transmitters. Simulations revealed biases of posterior mean estimates were minimal (≤ 4.95%), and posterior distributions behaved as expected with RMSE of the estimates decreasing as sample sizes, detection probability, and survival increased. We determined mortality hazard rates for plover chicks were highest at <5 days old and were lower for chicks with larger birth weights and/or whose nest was within agricultural habitats. Based on its performance, our approach greatly expands the range of problems for which event-time analyses can be used by eliminating the

  5. A semiparametrically efficient estimator of the time-varying effects for survival data with time-dependent treatment.

    PubMed

    Lin, Huazhen; Fei, Zhe; Li, Yi

    2016-09-01

    The timing of a time-dependent treatment-e.g., when to perform a kidney transplantation-is an important factor for evaluating treatment efficacy. A naïve comparison between the treated and untreated groups, while ignoring the timing of treatment, typically yields biased results that might favor the treated group because only patients who survive long enough will get treated. On the other hand, studying the effect of a time-dependent treatment is often complex, as it involves modeling treatment history and accounting for the possible time-varying nature of the treatment effect. We propose a varying-coefficient Cox model that investigates the efficacy of a time-dependent treatment by utilizing a global partial likelihood, which renders appealing statistical properties, including consistency, asymptotic normality and semiparametric efficiency. Extensive simulations verify the finite sample performance, and we apply the proposed method to study the efficacy of kidney transplantation for end-stage renal disease patients in the U.S. Scientific Registry of Transplant Recipients (SRTR).

  6. Tolazoline decreases survival time during microwave-induced lethal heat stress in anesthetized rats

    SciTech Connect

    Jauchem, J.R.; Chang, K.S.; Frei, M.R.

    1996-03-01

    Effects of {alpha}-adrenergic antagonists have been studied during environmental heating but not during microwave-induced heating. Tolazoline may exert some of its effects via {alpha}-adrenergic blockade. In the present study, ketamine-anesthetized Sprague-Dawley rats were exposed to 2450-MHz microwaves at an average power density of 60 mW/cm{sup 2} (whole-body specific absorption rate of approximately 14 W/kg) until lethal temperatures were attained. The effects of tolazoline (10 mg/kg body weight) on physiological responses (including changes in body temperature, heart rate, blood pressure, and respiratory rate) were examined. Survival time was significantly shorter in the tolazoline group than in saline-treated animals. In general, heart rate and blood pressure responses were similar to those that occur during environmental heat stress. Heart rate, however, was significantly elevated in animals that received tolazoline, both before and during terminal microwave exposure. It is possible that changes associated with the elevated heart rate (e.g., less cardiac filling) in tolazoline-treated animals resulted in greater susceptibility to microwave-induced heating and the lower survival time. 47 refs., 3 figs., 2 tabs.

  7. 46 CFR 154.605 - Toughness test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Toughness test. 154.605 Section 154.605 Shipping COAST....605 Toughness test. (a) Each toughness test under §§ 154.610 through 154.625 must meet Subpart 54.05 of this chapter. (b) If subsize test specimens are used for the Charpy V-notch toughness test,...

  8. Fracture toughness of polyimide films

    NASA Technical Reports Server (NTRS)

    Hinkley, J. A.; Mings, S. L.

    1989-01-01

    Two aromatic polyimides and an aromatic polyamide-imide were tested in single edge notched tension. Fracture toughnesses, normalized to 25 micron film thickness ranged from 1.65 to 5.4 MPa m sup 1/2. LARC-TPI, a thermoplastic polyimide, showed evidence of crazing ahead of a growing crack whereas the other materials formed a shear yielded zone.

  9. iTOUGH2 Sample Problems

    SciTech Connect

    Finsterle, Stefan

    2002-06-18

    iTOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase flow in fractured and porous media. This report contains a collection of iTOUGH2 sample problems.

  10. Improving the toughness of ultrahigh strength steel

    SciTech Connect

    Soto, Koji

    2002-01-01

    The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the toughening mechanism of the Fe/Co/Ni/Cr/Mo/C steel, AerMet 100, which has the highest toughness/strength combination among all commercial ultrahigh strength steels. The possibility of improving the toughness of this steel was examined by considering several relevant factors.

  11. A latent pharmacokinetic time profile to model dose-response survival data.

    PubMed

    Jacobs, Tom; Straetemans, Roel; Molenberghs, Geert; Adriaan Bouwknecht, J; Bijnens, Luc

    2010-07-01

    The accelerating rotarod test is a preclinical pharmacodynamic test to assess the effect of a treatment on an animal's motor coordination. Two models are proposed to analyze the dose-response time-to-event data that typically result from such experiments: (1) a linear regression model and (2) an E(max) model with latent drug concentration at the site of action. Both cope with the survival character of the data. The latter model allows a direct comparison of compounds, but raises the question of whether the study design would benefit from the inclusion of additional mice for plasma concentration sampling on the one hand or whether additional time-to-event data without plasma concentration sampling should be ascertained from these additional mice on the other hand. A simulation study explores the impact on operational characteristics of this change of study design.

  12. Frozen in Time? Microbial strategies for survival and carbon metabolism over geologic time in a Pleistocene permafrost chronosequence

    NASA Astrophysics Data System (ADS)

    Mackelprang, R.; Douglas, T. A.; Waldrop, M. P.

    2014-12-01

    Permafrost soils have received tremendous interest due to their importance as a global carbon store with the potential to be thawed over the coming centuries. Instead of being 'frozen in time,' permafrost contains active microbes. Most metagenomic studies have focused on Holocene aged permafrost. Here, we target Pleistocene aged ice and carbon rich permafrost (Yedoma), which can differ in carbon content and stage of decay. Our aim was to understand how microbes in the permafrost transform organic matter over geologic time and to identify physiological and biochemical adaptations that enable long-term survival. We used next-generation sequencing to characterize microbial communities along a permafrost age gradient. Samples were collected from the Cold Regions Research and Engineering Laboratory (CRREL) Permafrost Tunnel near Fox, AK, which penetrates a hillside providing access to permafrost ranging in age from 12 to 40 kyr. DNA was extracted directly from unthawed samples. 16S rRNA amplicon (16S) and shotgun metagenome sequencing revealed significant age-driven differences. First, microbial diversity declines with permafrost age, likely due to long-term exposure to environmental stresses and a reduction in metabolic resources. Second, we observed taxonomic differences among ages, with an increasing abundance of Firmicutes (endospore-formers) in older samples, suggesting that dormancy is a common survival strategy in older permafrost. Ordination of 16S and metagenome data revealed age-based clustering. Genes differing significantly between age categories included those involved in lipopolysaccharide assembly, cold-response, and carbon processing. These data point to the physiological adaptations to long-term frozen conditions and to the metabolic processes utilized in ancient permafrost. In fact, a gene common in older samples is involved in cadaverine production, which could potentially explain the putrefied smell of Pleistocene aged permafrost. Coupled with soil

  13. Time-Dependence Of The Survival Probality Of Charmonia In Heavy ION Collisions

    NASA Astrophysics Data System (ADS)

    Petridis, Athanasios; Mah Hussin, Noor Sabrina; Shalaby, Asmaa

    2016-09-01

    The time-dependent Schrödinger equation is used to study the formation of charmonium in heavy ion collisions and its propagation in Quark-Gluon Plasma (QGP) and free space. The initial bound (ground) state is computed using imaginary-time propagation in a confining potential. The QGP is simulated with a confining potential of an extended asymptotic-freedom region. The initial state propagates in real time but the charmonium bound state may become fully developed before or after the QGP formation. To this end the formation-time scales determine the kind of potential in which the quark-antiquark pair propagates and may necessitate the introduction of dissociating potentials. The survival probability is calculated versus time for various potential parameters and relative momenta of the charmonium by projecting the interacting wavefunction onto its freely-propagating counterpart. In these calculations the staggered-leap frog method is used with special attention paid to the issue of stability. It is found that charmonium decay is typically non-exponential. Fast moving states Connection with experimental results is done by means of cross-section ratios. It is shown that suppression and enhancement are both possible depending on the time-scales.

  14. Toughness of fiber reinforced shotcrete

    SciTech Connect

    Morgan, D.R.; Chen, L.; Beaupre, D.

    1995-12-31

    Fibers are added to shotcrete to improve energy absorption and impact resistance, to provide crack resistance and crack control, and to provide apparent ductility, i.e., an ability to continue to carry load after the shotcrete matrix has cracked. In order to be able to quantify the benefits of fiber addition, a variety of different toughness measuring systems have been developed in different countries. Most commonly used are flexural toughness systems which determine load vs. deflection responses and relate the area under the curve to some absolute or dimensionless index energy parameter. In North America the ASTM C1018 test method is most commonly used. In Japan the JSCE-SF4 test procedure is used. A variety of procedures have been used in Europe, but the template approach of the Norwegian Guidelines NBP No. 7, seems to be finding favor. This paper briefly assesses the relative advantages and disadvantages of the various methods of characterizing toughness. It then provides recommendations for a new procedure which uses the ASTM C1018 test method for generating the flexural load vs. deflection curve, but analyzes the data using a modified version of the Norwegian template approach. The load vs. deflection curve is directly compared against four residual strength curves and the fiber reinforced shotcrete assigned one of four toughness performance levels. It is believed that this new procedure should provide suitable within and between laboratory reproducibility and be more suitable for purposes of differentiating between different fiber types and addition rates and specifying toughness for fiber reinforced shotcrete products than any of the existing methods.

  15. Survival of Bacillus pumilus spores for a prolonged period of time in real space conditions.

    PubMed

    Vaishampayan, Parag A; Rabbow, Elke; Horneck, Gerda; Venkateswaran, Kasthuri J

    2012-05-01

    To prevent forward contamination and maintain the scientific integrity of future life-detection missions, it is important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory spacecraft and landing vehicles. Among the organisms isolated from spacecraft-associated surfaces, spores of Bacillus pumilus SAFR-032 exhibited unusually high resistance to decontamination techniques such as UV radiation and peroxide treatment. Subsequently, B. pumilus SAFR-032 was flown to the International Space Station (ISS) and exposed to a variety of space conditions via the European Technology Exposure Facility (EuTEF). After 18 months of exposure in the EXPOSE facility of the European Space Agency (ESA) on EuTEF under dark space conditions, SAFR-032 spores showed 10-40% survivability, whereas a survival rate of 85-100% was observed when these spores were kept aboard the ISS under dark simulated martian atmospheric conditions. In contrast, when UV (>110 nm) was applied on SAFR-032 spores for the same time period and under the same conditions used in EXPOSE, a ∼7-log reduction in viability was observed. A parallel experiment was conducted on Earth with identical samples under simulated space conditions. Spores exposed to ground simulations showed less of a reduction in viability when compared with the "real space" exposed spores (∼3-log reduction in viability for "UV-Mars," and ∼4-log reduction in viability for "UV-Space"). A comparative proteomics analysis indicated that proteins conferring resistant traits (superoxide dismutase) were present in higher concentration in space-exposed spores when compared to controls. Also, the first-generation cells and spores derived from space-exposed samples exhibited elevated UVC resistance when compared with their ground control counterparts. The data generated are important for calculating the probability and mechanisms of microbial survival in space conditions and assessing microbial contaminants

  16. Psychosocial predictors of outcome: time to relapse and survival in patients with early stage melanoma

    PubMed Central

    Brown, J E; Butow, P N; Culjak, G; Coates, A S; Dunn, S M

    2000-01-01

    This study explored psychosocial predictors of relapse and survival in early stage melanoma patients. Patients with locoregional melanoma whose tumour thickness exceeded 0.69 mm, seen at the Sydney Melanoma Unit between 1991 and 1996 participated in the study. Questionnaires were sent to participating patients every 3 months for 2 years. Domains measured included cognitive appraisal of threat, coping, psychological adjustment, quality of life and perceived aim of treatment. Disease and demographic data were obtained from medical records. Multivariate analyses from baseline data used the Cox proportional hazards model. Of the 682 patients invited to participate 426 (62%) agreed. 91 (21%) relapsed and 60 (14%) died within the follow-up period, that ended in October 1997. After controlling for known prognostic indicators, several psychosocial variables predicted time to relapse and/or survival duration. Patients who perceived their aim of treatment to be cured, who did not use avoidance as a coping strategy or who were concerned about their disease experienced longer periods without relapse. Shorter survival duration was associated with a positive mood, the use of avoidance as a coping strategy, not being concerned with their disease and concern about the impact of the disease on family. There is still much to learn about the potential relationships between psychological well being, human behaviours and cancer outcome. Research in this area needs to clarify the psychological processes, as well as understand the biological and/or behavioural mechanisms that may link them to outcome. © 2000 Cancer Research Campaign http://www.bjcancer.com PMID:11076652

  17. Survival time of cardiac allografts prolonged by isogeneic BMT in mice.

    PubMed

    Chen, Z; Jiang, H; Chen, R; Feng, S; Jin, J; Bi, Y; Yang, H; Chen, J

    2012-08-01

    To find an approach to prolong the survival time of cardiac allografts in a BALB/c-to-C57/BL6 heterotopic heart transplant model and to try to figure out related chemokines and cytokines, isogeneic and allogeneic BM cells were obtained from pregnant C57/BL6 (♀C57/BL6 × ♂BALB/c) and regular BALB/c mice and injected to the half lethally irradiated C57/BL6 mice 1 day before heart transplantation. Recipients were treated with CsA or phosphate-buffered saline for 7 days. Isogeneic BMT (iBMT) from pregnant C57/BL6 mice was observed to significantly prolong the survival of BALB/c allografts and reduce the lymphocyte infiltration. Allogeneic BMT (aBMT) and iBMT both exhibited signicantly less T-cell proliferation reactivity and the similar degree of chimerism. There was no significant difference in these groups of IFN-γ and IL-4 production. The level of chemokine MIG (CXCL9) dramatically decreased in aBMT and iBMT groups compared with the control group. But there were no significant differences between aBMT and iBMT group. IL-17 and RORγ(t) (receptor-related orphan receptor) production were downregulated in iBMT recipients. These results indicate that iBMT can prolong the survival of cardiac allografts. IL-17 production downregulated in iBMT recipients. This means that iBMT may have important therapeutic implications.

  18. Growing up tough: Comparing the effects of food toughness on juvenile feeding in Sapajus libidinosus and Trachypithecus phayrei crepusculus.

    PubMed

    Chalk-Wilayto, Janine; Ossi-Lupo, Kerry; Raguet-Schofield, Melissa

    2016-09-01

    Studies of primate feeding ontogeny provide equivocal support for reduced juvenile proficiency. When immatures exhibit decreased feeding competency, these differences are attributed to a spectrum of experience- and strength-related constraints and are often linked to qualitative assessments of food difficulty. However, few have investigated age-related differences in feeding ability relative to mechanical property variation across the diet, both within and among food types. In this study, we combined dietary toughness and feeding behavior data collected in the wild from cross-sectional samples of two primate taxa, Sapajus libidinosus and Trachypithecus phayrei crepusculus, to test the prediction that small-bodied juveniles are less efficient at processing tough foods than adults. We defined feeding efficiency as the time spent to ingest and masticate one food item (item bout length) and quantified the toughness and size of foods processed during those feeding bouts. To make the datasets comparable, we limited the dataset to foods processed by more than one age class and opened without tools. The overall toughness of foods processed by both species overlapped considerably, and juveniles and adults in both taxa processed foods of comparable toughness. Feeding efficiency decreased in response to increasing food toughness in leaf monkeys and in response to food size in both taxa. Age was found to be a significant predictor of bout length in leaf monkeys, but not in bearded capuchins. Juvenile S. libidinosus processed smaller fruits than adults, suggesting they employ behavioral strategies to mitigate the effect of consuming large (and occasionally large and tough) foods. We suggest future intra- and interspecific research of juvenile feeding competency utilize intake rates scaled by food size and geometry, as well as by detailed measures of feeding time (e.g., ingestion vs. mastication), in addition to food mechanical properties to facilitate comparisons across

  19. Chaotic dynamics of Halley's comet: Lyapunov exponents and survival-time prospects

    NASA Astrophysics Data System (ADS)

    Muñoz-Gutiérrez, M.; Reyes-Ruiz, M.; Pichardo, B.

    2014-07-01

    We have explored the dynamical evolution of the comet 1P/Halley over 1 Myr with detailed numerical simulations, under the gravitational influence of all the planets in the present-day Solar System (except Mercury). To this purpose, we have employed the Mercury 6.2 code, including, in addition to the planets, the 9 largest minor bodies (among them those known as dwarf planets except for Sedna) to conduct the N-body simulation. The comet's fiduciary orbit, and a set of orbits surrounding it in the phase space (a-e), are solved as test particles in this problem. The ensemble of orbits explored is constructed as a mesh of 10,000 particles with different initial conditions covering the observational error of the orbit in the semimajor axis and eccentricity (± 10^{-6} au and ± 10^{-6}, respectively). We find that the comet's fate is highly sensitive to initial conditions. Survival time maps from the simulations and Laskar frequency analysis maps for the vicinity of Halley's comet are shown. Also, the maximum Lyapunov exponent for neighboring orbits is calculated. This shows that chaos is dominant for these highly eccentric orbits as found by Chirikov & Vecheslavov (1989) and produces large non-stable regions for the comet's surrounding phase space. We provide estimations of the probability of survival of Halley's comet and a general perspective about the dynamical evolution of comets on a wider region of phase-space which covers several currently known Halley-type comets.

  20. Time to lowest postoperative carcinoembryonic antigen level is predictive on survival outcome in rectal cancer

    PubMed Central

    Yu, Huichuan; Luo, Yanxin; Wang, Xiaolin; Bai, Liangliang; Huang, Pinzhu; Wang, Lei; Huang, Meijin; Deng, Yanhong; Wang, Jianping

    2016-01-01

    This study was to investigate whether the time to the lowest postoperative CEA can predict cancer survival. We enrolled 155 rectal cancer patients in this retrospective and longitudinal cohort study. Deepness of response (DpR) of CEA refers to the relative change of the lowest postoperative CEA level from baseline, and time to DpR (TTDpR) refers to the time from surgery to the lowest postoperative CEA level. The median of TTDpR and DpR was 4.5 (range, 3.0–18.0) weeks and −67% (range, −99% to 114%) respectively. Patients with TTDpR 4.5 weeks. Using TTDpR as a continuous variable, the HR of DFS and OS was 1.13 (95% CI 1.06–1.22, P = 0.001) and 1.17 (95% CI 1.07–1.29, P = 0.001) respectively. On multivariate analysis, the predictive value of prolonged TTDpR remained [adjusted HRs: 1.12 (95% CI 1.03–1.21, P = 0.006) and 1.17 (95% CI 1.06–1.28, P = 0.001)]. These findings remained significant in patients with normal preoperative CEA. Our results showed prolonged TTDpR of CEA independently predicted unfavorable survival outcomes, regardless of whether preoperative CEA was elevated or not. PMID:27658525

  1. Indium-111 labeled platelet survival time studies in patients with prosthetic heart valves

    SciTech Connect

    Martinovitch, U.; Carrick, P.; Lieberman, L.M.

    1985-05-01

    Platelet survival time (PST) studies are useful to demonstrate whether or not patients with prosthetic heart valves have normal or shortened PST. During treatment for recurrent TIAs the PST will signal whether the patient is returning towards a normal PST. Using Indium-111 labeled platelets (ILP) the authors studied 10 patients suffering recurrent TIAs after prosthetic valve surgery to determine whether low dose aspirin increased their PST toward normal and whether the treatment had a beneficial effect on their TIA episodes. The authors conclude that low dose aspirin therapy as studied by ILP has no beneficial effect on PST or in preventing recurrent TIA. ILP is an important technique that allows the physician to identify those patients with shortened PST and to determine response to therapy.

  2. Ultrasonic ranking of toughness of tungsten carbide

    NASA Technical Reports Server (NTRS)

    Vary, A.; Hull, D. R.

    1983-01-01

    The feasibility of using ultrasonic attenuation measurements to rank tungsten carbide alloys according to their fracture toughness was demonstrated. Six samples of cobalt-cemented tungsten carbide (WC-Co) were examined. These varied in cobalt content from approximately 2 to 16 weight percent. The toughness generally increased with increasing cobalt content. Toughness was first determined by the Palmqvist and short rod fracture toughness tests. Subsequently, ultrasonic attenuation measurements were correlated with both these mechanical test methods. It is shown that there is a strong increase in ultrasonic attenuation corresponding to increased toughness of the WC-Co alloys. A correlation between attenuation and toughness exists for a wide range of ultrasonic frequencies. However, the best correlation for the WC-Co alloys occurs when the attenuation coefficient measured in the vicinity of 100 megahertz is compared with toughness as determined by the Palmqvist technique.

  3. Time-specific patterns of nest survival for ducks and passerines breeding in North Dakota

    USGS Publications Warehouse

    Shaffer, Terry L.; Grant, Todd A.

    2012-01-01

    In many bird species, survival can vary with the age of the nest, with the date a nest was initiated, or among years within the same nesting area. A literature review showed that patterns of survival vary in relation to nest age and date and are often contradictory. Inconsistencies could be a result of temporal variation in the environment or life-history differences among species. We examined patterns of nest survival in relation to nest age, date, and year for several duck and passerine species nesting at a single location in North Dakota during 1998–2003. We predicted that if environment shaped nest survival patterns, then temporal patterns in survival might be similar among three species of upland nesting ducks, and also among three species of grassland passerines nesting at the same site. We expected that survival patterns would differ between ducks and passerines because of relatively disparate life histories and differences in predators that prey on their nests. Nest survival was rarely constant among years, seasonally, or with age of the nest for species that we studied. As predicted, the pattern of survival was similar among duck species, driven mainly by differences in nest survival associated with nest initiation date. The pattern of survival also was similar among passerine species, but nest survival was more influenced by nest age than by date. Our findings suggest that some but not all variation in temporal patterns of nest survival in grassland birds reported in the literature can be explained on the basis of temporal environmental variation. Because patterns of survival were dissimilar among ducks and passerines, it is likely that mechanisms such as predation or brood parasitism have variable influences on productivity of ducks and passerines nesting in the same area. Our results indicate that biologists and managers should not assume that temporal environmental variations, especially factors that affect nest survival, act similarly on all

  4. High Fracture Toughness Bearing Development

    DTIC Science & Technology

    1981-12-01

    AFWAL-TR-81-2042 C• ) HIGH FRACTURE TOUGHNESS BEARING DEVELOPMENT SKF Industries, Inc. King of Prussia, PA 19406 December 1981 Final Report for...withthe contractor SKF who wrote the report and found that the inclusion of the proprietary notice was ati oversight on their part. The con-tractor and...TASK SKF Industries, Inc . AREA & WORK UNIT NUMBERS 1100 First Avenue 3048 06 07 King of Prussia, PA 19406 It. CONTROLLING OFFICE NAME AND ADDRESS 12

  5. Tough high performance composite matrix

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor); Johnston, Norman J. (Inventor)

    1994-01-01

    This invention is a semi-interpentrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. Provided is an improved high temperature matrix resin which is capable of performing in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance, and moisture and solvent resistances.

  6. Tough, Soluble, Aromatic, Thermoplastic Copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    1998-01-01

    Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

  7. Fracture toughness anisotropy in shale

    NASA Astrophysics Data System (ADS)

    Chandler, Michael R.; Meredith, Philip G.; Brantut, Nicolas; Crawford, Brian R.

    2016-03-01

    The use of hydraulic fracturing to recover shale gas has focused attention on the fundamental fracture properties of gas-bearing shales, but there remains a paucity of available experimental data on their mechanical and physical properties. Such shales are strongly anisotropic, so that their fracture propagation trajectories depend on the interaction between their anisotropic mechanical properties and the anisotropic in situ stress field in the shallow crust. Here we report fracture toughness measurements on Mancos shale determined in all three principal fracture orientations: Divider, Short Transverse, and Arrester, using a modified short-rod methodology. Experimental results for a range of other sedimentary and carbonate rocks are also reported for comparison purposes. Significant anisotropy is observed in shale fracture toughness measurements at ambient conditions, with values, as high as 0.72 MPa m1/2 where the crack plane is normal to the bedding, and values as low as 0.21 MPa m1/2 where the crack plane is parallel to the bedding. For cracks propagating nonparallel to bedding, we observe a tendency for deviation toward the bedding-parallel orientation. Applying a maximum energy release rate criterion, we determined the conditions under which such deviations are more or less likely to occur under more generalized mixed-mode loading conditions. We find for Mancos shale that the fracture should deviate toward the plane with lowest toughness regardless of the loading conditions.

  8. Differences in the timing of cardio-respiratory development determine whether marine gastropod embryos survive or die in hypoxia.

    PubMed

    Rudin-Bitterli, Tabitha S; Spicer, John I; Rundle, Simon D

    2016-04-01

    Physiological plasticity of early developmental stages is a key way by which organisms can survive and adapt to environmental change. We investigated developmental plasticity of aspects of the cardio-respiratory physiology of encapsulated embryos of a marine gastropod, Littorina obtusata, surviving exposure to moderate hypoxia (PO2 =8 kPa) and compared the development of these survivors with that of individuals that died before hatching. Individuals surviving hypoxia exhibited a slower rate of development and altered ontogeny of cardio-respiratory structure and function compared with normoxic controls (PO2 >20 kPa). The onset and development of the larval and adult hearts were delayed in chronological time in hypoxia, but both organs appeared earlier in developmental time and cardiac activity rates were greater. The velum, a transient, 'larval' organ thought to play a role in gas exchange, was larger in hypoxia but developed more slowly (in chronological time), and velar cilia-driven, rotational activity was lower. Despite these effects of hypoxia, 38% of individuals survived to hatching. Compared with those embryos that died during development, these surviving embryos had advanced expression of adult structures, i.e. a significantly earlier occurrence and greater activity of their adult heart and larger shells. In contrast, embryos that died retained larval cardio-respiratory features (the velum and larval heart) for longer in chronological time. Surviving embryos came from eggs with significantly higher albumen provisioning than those that died, suggesting an energetic component for advanced development of adult traits.

  9. Impact of collaborative care on survival time for dogs with congestive heart failure and revenue for attending primary care veterinarians.

    PubMed

    Lefbom, Bonnie K; Peckens, Neal K

    2016-07-01

    OBJECTIVE To assess the effects of in-person collaborative care by primary care veterinarians (pcDVMs) and board-certified veterinary cardiologists (BCVCs) on survival time of dogs after onset of congestive heart failure (CHF) and on associated revenue for the attending pcDVMs. DESIGN Retrospective cohort study. ANIMALS 26 small-breed dogs treated for naturally occurring CHF secondary to myxomatous mitral valve disease at a multilocation primary care veterinary hospital between 2008 and 2013. PROCEDURES Electronic medical records were reviewed to identify dogs with confirmed CHF secondary to myxomatous mitral valve disease and collect information on patient care, survival time, and pcDVM revenue. Data were compared between dogs that received collaborative care from the pcDVM and a BCVC and dogs that received care from the pcDVM alone. RESULTS Dogs that received collaborative care had a longer median survival time (254 days) than did dogs that received care from the pcDVM alone (146 days). A significant positive correlation was identified between pcDVM revenue and survival time for dogs that received collaborative care (ie, the longer the dog survived, the greater the pcDVM revenue generated from caring for that patient). CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that collaborative care provided to small-breed dogs with CHF by a BCVC and pcDVM could result in survival benefits for affected dogs and increased revenue for pcDVMs, compared with care provided by a pcDVM alone.

  10. The interlaminar fracture toughness of woven graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Funk, Joan G.; Deaton, Jerry W.

    1989-01-01

    The interlaminar fracture toughness of 2-D graphite/epoxy woven composites was determined as a function of stacking sequence, thickness, and weave pattern. Plain, oxford, 5-harness satin, and 8-harness satin weaves of T300/934 material were evaluated by the double cantilever beam test. The fabric material had a G (sub Ic) ranging from 2 to 8 times greater than 0 degrees unidirectional T300/934 tape material. The interlaminar fracture toughness of a particular weave style was dependent on whether the stacking sequence was symmetric or asymmetric and, in some cases, on the fabric orientation.

  11. Tough Like Metal

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Under an SBIR (Small Business Innovative Research) with Lewis Research Center, Advanced Ceramics Corporation developed a family of high temperature and doped boron nitride coating that offer improvement in interface durability of SiC/SiC composites. The new materials are 1,000 times more durable and greatly extend composite lifetimes. The development of this was commercialized with assistance from Lewis and Advanced Ceramic's own money and is supplying several composites manufacturers with new interface coating from an expanded in-line tow coating facility.

  12. TRITIUM EFFECTS ON WELDMENT FRACTURE TOUGHNESS

    SciTech Connect

    Morgan, M; Michael Tosten, M; Scott West, S

    2006-07-17

    The effects of tritium on the fracture toughness properties of Type 304L stainless steel and its weldments were measured. Fracture toughness data are needed for assessing tritium reservoir structural integrity. This report provides data from J-Integral fracture toughness tests on unexposed and tritium-exposed weldments. The effect of tritium on weldment toughness has not been measured until now. The data include tests on tritium-exposed weldments after aging for up to three years to measure the effect of increasing decay helium concentration on toughness. The results indicate that Type 304L stainless steel weldments have high fracture toughness and are resistant to tritium aging effects on toughness. For unexposed alloys, weldment fracture toughness was higher than base metal toughness. Tritium-exposed-and-aged base metals and weldments had lower toughness values than unexposed ones but still retained good toughness properties. In both base metals and weldments there was an initial reduction in fracture toughness after tritium exposure but little change in fracture toughness values with increasing helium content in the range tested. Fracture modes occurred by the dimpled rupture process in unexposed and tritium-exposed steels and welds. This corroborates further the resistance of Type 304L steel to tritium embrittlement. This report fulfills the requirements for the FY06 Level 3 milestone, TSR15.3 ''Issue summary report for tritium reservoir material aging studies'' for the Enhanced Surveillance Campaign (ESC). The milestone was in support of ESC L2-1866 Milestone-''Complete an annual Enhanced Surveillance stockpile aging assessment report to support the annual assessment process''.

  13. How cellulose-based leaf toughness and lamina density contribute to long leaf lifespans of shade-tolerant species.

    PubMed

    Kitajima, Kaoru; Llorens, Anna-Maria; Stefanescu, Carla; Timchenko, Marta Vargas; Lucas, Peter W; Wright, S Joseph

    2012-08-01

    Cell wall fibre and lamina density may interactively affect leaf toughness and leaf lifespan. Here, we tested this with seedlings of 24 neotropical tree species differing in shade tolerance and leaf lifespan under standardized field conditions (140-867 d in gaps; longer in shade). We quantified toughness with a cutting test, explicitly seeking a mechanistic linkage to fibre. Lamina density, but not fracture toughness, exhibited a plastic response to gaps vs shade, while neither trait was affected by leaf age. Toughness corrected for lamina density, a recently recognized indicator of material strength per unit mass, was linearly correlated with cellulose content per unit dry mass. Leaf lifespan was positively correlated with cellulose and toughness in shade-tolerant species but only weakly in gap-dependent species. Leaf lifespan was uncorrelated with lamina thickness, phenolics and tannin concentrations. In path analysis including all species, leaf lifespan was directly enhanced by density and toughness, and indirectly by cellulose via its effect on toughness. Different suites of leaf traits were correlated with early seedling survival in gaps vs shade. In conclusion, cellulose and lamina density jointly enhance leaf fracture toughness, and these carbon-based physical traits, rather than phenolic-based defence, explain species differences in herbivory, leaf lifespan and shade survival.

  14. Sugar concentration and timing of feeding affect feeding characteristics and survival of a parasitic wasp

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The availability of food sources is critical for parasitoid survival, especially for those that do not host-feed, or in agroecosystems where nectar and honeydew are sometimes spatially and temporally scarce. Therefore, the value of even a single meal can be crucial for survival. Psyttalia lounsbur...

  15. The Health Rationale for Family Planning: Timing of Births and Child Survival.

    ERIC Educational Resources Information Center

    United Nations, New York, NY. Population Div.

    Among the most influential findings from the World Fertility Survey (WFS) were those linking fertility patterns to child survival, in particular the findings concerning the high infant and child mortality for children born after a short birth interval. This study examined the relations between fertility and child survival based on more recent data…

  16. In a Tough Economy, Charlotte Makes a Play for Football

    ERIC Educational Resources Information Center

    Sander, Libby

    2008-01-01

    Despite tough economic times, the University of North Carolina at Charlotte hopes to win trustees' approval to raise funds to field a Division I-AA football team. Athletics officials and supporters at Charlotte are hopeful that they will raise the more than $45-million in capital expenses necessary to get the program up and running. However, the…

  17. Mentally Tough: The Power To Do Your Best.

    ERIC Educational Resources Information Center

    McLaughlin, Peter J.; And Others

    The principles of Mentally Tough were developed to help professional athletes to do their best each time they went out to play. This book brings these strategies to junior and senior high school students. The exercises and activities are intended to teach students how to control their energy level and emotional states so they can always perform…

  18. Survival times of meter-sized rock boulders on the surface of airless bodies

    NASA Astrophysics Data System (ADS)

    Basilevsky, A. T.; Head, J. W.; Horz, F.; Ramsley, K.

    2015-11-01

    Rock boulders are typical features of the surfaces of many airless bodies, so the possibility of estimating their potential survival times may provide insights into the rates of surface-modification processes. As an opening point of this study we employ estimates of the survival times of meter-sized boulders on the surface of the Moon based on analysis of the spatial density of boulders on the rims of small lunar craters of known absolute age (Basilevsky et al., 2013), and apply them, with necessary corrections, to boulders on other bodies. In this approach the major factor of rock destruction is considered to be impacts of meteorites. However another factor of the rock destruction, thermal fatigue due to day-night cycling, does exist and it was claimed by Delbo et al. (2014) as being more important than meteorite impacts. They concluded this on the basis of known presence of fine material on the surface of small asteroids, claiming that due to extremely low gravity on those bodies, the products of meteorite bombardment should leave these bodies, and thus their presence indicates that the process of thermal fatigue should be much more effective there. Delbo et al. (2014) made laboratory experiments on heating-cooling centimeter-sized samples of chondrites and, applying some assumptions and theoretical modeling concluded that, for example, at 1 AU distance from the Sun, the lifetime of 10 cm rock fragments on asteroids with period of rotation from 2.2 to 6 h should be only ~103 to 104 years (that is ~3.5×106 to 1.5×107 thermal cycles) and the larger the rock, the faster it should be destroyed. In response to those conclusions we assessed the results of earlier laboratory experiments, which show that only a part of comminuted material produced by high-velocity impacts into solid rocks is ejected from the crater while another part is not ejected but stays exposed on the target surface and is present in its subsurface. This means that the presence of

  19. Fracture toughness testing of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.

    1992-01-01

    A review of the interlaminar fracture indicates that a standard specimen geometry is needed to obtain consistent fracture toughness measurements in polymer matrix composites. In general, the variability of measured toughness values increases as the toughness of the material increases. This variability could be caused by incorrect sizing of test specimens and/or inconsistent data reduction procedures. A standard data reduction procedure is therefore needed as well, particularly for the tougher materials. Little work has been reported on the effects of fiber orientation, fiber architecture, fiber surface treatment or interlaminar fracture toughness, and the mechanisms by which the fibers increase fracture toughness are not well understood. The little data that is available indicates that woven fiber reinforcement and fiber sizings can significantly increase interlaminar fracture toughness.

  20. Dietary magnesium and copper affect survival time and neuroinflammation in chronic wasting disease

    PubMed Central

    Nichols, Tracy A.; Spraker, Terry R.; Gidlewski, Thomas; Cummings, Bruce; Hill, Dana; Kong, Qingzhong; Balachandran, Aru; VerCauteren, Kurt C.; Zabel, Mark D.

    2016-01-01

    ABSTRACT Chronic wasting disease (CWD), the only known wildlife prion disease, affects deer, elk and moose. The disease is an ongoing and expanding problem in both wild and captive North American cervid populations and is difficult to control in part due to the extreme environmental persistence of prions, which can transmit disease years after initial contamination. The role of exogenous factors in CWD transmission and progression is largely unexplored. In an effort to understand the influence of environmental and dietary constituents on CWD, we collected and analyzed water and soil samples from CWD-negative and positive captive cervid facilities, as well as from wild CWD-endozootic areas. Our analysis revealed that, when compared with CWD-positive sites, CWD-negative sites had a significantly higher concentration of magnesium, and a higher magnesium/copper (Mg/Cu) ratio in the water than that from CWD-positive sites. When cevidized transgenic mice were fed a custom diet devoid of Mg and Cu and drinking water with varied Mg/Cu ratios, we found that higher Mg/Cu ratio resulted in significantly longer survival times after intracerebral CWD inoculation. We also detected reduced levels of inflammatory cytokine gene expression in mice fed a modified diet with a higher Mg/Cu ratio compared to those on a standard rodent diet. These findings indicate a role for dietary Mg and Cu in CWD pathogenesis through modulating inflammation in the brain. PMID:27216881

  1. A dynamic Bayesian network approach for time-specific survival probability prediction in patients after ventricular assist device implantation.

    PubMed

    Exarchos, Themis P; Rigas, George; Goletsis, Yorgos; Stefanou, Kostas; Jacobs, Steven; Trivella, Maria-Giovanna; Fotiadis, Dimitrios I

    2014-01-01

    In this work we present a decision support tool for the calculation of time-dependent survival probability for patients after ventricular assist device implantation. Two different models have been developed, a short term one which predicts survival for the first three months and a long term one that predicts survival for one year after implantation. In order to model the time dependencies between the different time slices of the problem, a dynamic Bayesian network (DBN) approach has been employed. DBNs order to capture the temporal events of the patient disease and the temporal data availability. High accuracy results have been reported for both models. The short and long term DBNs reached an accuracy of 96.97% and 93.55% respectively.

  2. Formation of tough composite joints

    SciTech Connect

    Brun, M.K.

    1997-05-01

    Joints which exhibit tough fracture behavior were formed in a composite with a Si/SiC matrix reinforced with Textron SCS-6 fibers with either boron nitride or silicon nitride fiber coatings. In composites with BN coatings fibers were aligned uniaxially, while composites with Si{sub 3}N{sub 4}-coated fibers had a 0/90{degree} architecture. Lapped joints (joints with overlapping fingers) were necessary to obtain tough behavior. Geometrical requirements necessary to avoid brittle joint failure have been proposed. Joints with a simple overlap geometry (only a few fingers) would have to be very long in order to prevent brittle failure. Typical failure in these joints is caused by a crack propagating along the interfaces between the joint fingers. Joints of the same overall length, but with geometry changed to be symmetric about the joint centerline and with an extra shear surface exhibited tough fractures accompanied with extensive fiber pullout. The initial matrix cracking of these joints was relatively low because cracks propagated easily through the ends of the fingers. Joints with an optimized stepped sawtooth geometry produced composite-like failures with the stress/strain curves containing an elastic region followed by a region of rising stress with an increase of strain. Increasing the fiber/matrix interfacial strength from 9 to 25 MPa, by changing the fiber coating, increased matrix cracking and ultimate strength of the composite significantly. The best joints had matrix cracking stress and ultimate strength of 138 and 240 MPa, respectively. Joint failure was preceded by multiple matrix cracking in the entire composite. The high strength of the joints will permit building of structures containing joints with only a minor reduction of design stresses.

  3. Hydrogen fracture toughness tester completion

    SciTech Connect

    Morgan, Michael J.

    2015-09-30

    The Hydrogen Fracture Toughness Tester (HFTT) is a mechanical testing machine designed for conducting fracture mechanics tests on materials in high-pressure hydrogen gas. The tester is needed for evaluating the effects of hydrogen on the cracking properties of tritium reservoir materials. It consists of an Instron Model 8862 Electromechanical Test Frame; an Autoclave Engineering Pressure Vessel, an Electric Potential Drop Crack Length Measurement System, associated computer control and data acquisition systems, and a high-pressure hydrogen gas manifold and handling system.

  4. High strength, tough alloy steel

    DOEpatents

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  5. Staying True?: Progressive Leadership in Tough Times

    ERIC Educational Resources Information Center

    Pignatelli, Frank

    2012-01-01

    A system of accountability in public schools predicated upon standardized testing accompanied by high-stakes consequences for leaders, as well as teachers and students, has posed a daunting challenge to educational leaders who align themselves with core tenets of progressive education. This essay explores what it might mean--and take--to stay true…

  6. E-Resources in Tough Times

    ERIC Educational Resources Information Center

    Tenopir, Carol

    2004-01-01

    Librarians must get the most for their money and look to technology for new solutions. Several respondents think poor budgets mean more reliance on online databases and electronic full texts with less purchase of print. Companies that produce both media are likely to continue as long as there is a market for both, but they are gearing up for the…

  7. University Technology Transfer: In Tough Economic Times

    ERIC Educational Resources Information Center

    Powers, Joshua B.; Campbell, Eric G.

    2009-01-01

    In 1907, Frederick Cottrell, professor of chemistry at the University of California-Berkeley and father of the modern academic patent, worried that if universities became too directly involved in patenting and licensing operations, their thirst for profits could lead to the erosion of the openness necessary for academic science to flourish. For…

  8. Entrepreneurial Aussies--Success in Tough Times.

    ERIC Educational Resources Information Center

    Rudolph, John; Barnaart, Antoine; Smith, Mike

    This presentation describes the entrepreneurial and intrapreneurial strategies being adopted by two Technical and Further Education (TAFE) institutions in Australia, Northern Territory University and the Victoria University of Technology. The similarities are stressed between TAFE institutions, North American community and technical colleges, and…

  9. Raising Resilient Children during Tough Economic Times

    ERIC Educational Resources Information Center

    Tom, A.; Yuen, S.; Fong, G.; Nemoto, M.; Hisatake, T.; Choy, A.; Chang, W.

    2009-01-01

    Financial hardship can result from many different circumstances--a poor economy, the loss of a job, underemployment, the prolonged illness of a family member, divorce, poor money management, or a combination of several factors. Whatever the cause, the resulting impact on a family can be stressful for all members, including children. Stress from…

  10. Multi-scale Multi-mechanism Design of Tough Hydrogels: Building Dissipation into Stretchy Networks

    PubMed Central

    Zhao, Xuanhe

    2014-01-01

    As swollen polymer networks in water, hydrogels are usually brittle. However, hydrogels with high toughness play critical roles in many plant and animal tissues as well as in diverse engineering applications. Here we review the intrinsic mechanisms of a wide variety of tough hydrogels developed over past few decades. We show that tough hydrogels generally possess mechanisms to dissipate substantial mechanical energy but still maintain high elasticity under deformation. The integrations and interactions of different mechanisms for dissipating energy and maintaining elasticity are essential to the design of tough hydrogels. A matrix that combines various mechanisms is constructed for the first time to guide the design of next-generation tough hydrogels. We further highlight that a particularly promising strategy for the design is to implement multiple mechanisms across multiple length scales into nano-, micro-, meso-, and macro-structures of hydrogels. PMID:24834901

  11. Mental toughness in sport: motivational antecedents and associations with performance and psychological health.

    PubMed

    Mahoney, John W; Gucciardi, Daniel F; Ntoumanis, Nikos; Mallett, Cliff J; Mallet, Cliff J

    2014-06-01

    We argue that basic psychological needs theory (BPNT) offers impetus to the value of mental toughness as a mechanism for optimizing human functioning. We hypothesized that psychological needs satisfaction (thwarting) would be associated with higher (lower) levels of mental toughness, positive affect, and performance and lower (higher) levels of negative affect. We also expected that mental toughness would be associated with higher levels of positive affect and performance and lower levels of negative affect. Further, we predicted that coaching environments would be related to mental toughness indirectly through psychological needs and that psychological needs would indirectly relate with performance and affect through mental toughness. Adolescent cross-country runners (136 male and 85 female, M(age) = 14.36) completed questionnaires pertaining to BPNT variables, mental toughness, and affect. Race times were also collected. Our findings supported our hypotheses. We concluded that BPNT is generative in understanding some of the antecedents and consequences of mental toughness and is a novel framework useful for understanding mental toughness.

  12. Correlation of Biological Characteristics of Smolts with Survival and Travel Time, 1987 Technical Report.

    SciTech Connect

    Rondorf, Dennis W.; Beeman, John W.; Free, Mary E.

    1988-06-01

    The biological characteristics of smolts were examined to determine their effect on estimates of survival in the Columbia and Snake rivers. Freeze branded groups of steelhead trout (Salmo gairdneri) from Lyons Ferry State Fish Hatchery (SFH) and Wells SFH and spring chinook salmon (Oncorhynchus tshawytscha) from Winthrop National Fish Hatchery (NFH) were used to estimate survival. Past estimates of survival, using a ratio of test and control fish recaptured at McNary Dam, have resulted in estimates > 100%, presumably due to some unknown bias. Study objectives were to determine if stress and descaling, degree of smoltification, and prevalence of bacterial kidney disease (BKD) differed among test and control groups of fish, thereby biasing survival estimates. 19 refs., 20 figs., 10 tabs.

  13. Breast cancer and leptomeningeal disease (LMD): hormone receptor status influences time to development of LMD and survival from LMD diagnosis.

    PubMed

    Yust-Katz, S; Garciarena, P; Liu, D; Yuan, Y; Ibrahim, N; Yerushalmi, R; Penas-Prado, M; Groves, M D

    2013-09-01

    Leptomeningeal disease (LMD) occurs in 5 % of breast cancer patients. The aim of this study was to identify risk factors related to survival and time to development of LMD in breast cancer patients. A retrospective analysis of breast cancer patients with LMD, evaluated in MDACC between 1995 and 2011. 103 patients with diagnosis of breast cancer and LMD were identified (one male). The median age at LMD diagnosis was 49.2 years. 78.2 % had invasive ductal carcinoma. Hormone receptors (HRs) were positive in 55.3 % of patients, 47.4 % were human epidermal growth factor receptor 2-positive and 22.8 % were triple negative. 52 % of the patients were treated with WBRT, 19 % with spinal radiation, 36 % with systemic chemotherapy and 55 % with intrathecal chemotherapy. Estimated median overall survival from time of breast cancer diagnosis was 3.66 years. Median survival from time of LMD diagnosis was 4.2 months. Time from breast cancer diagnosis to LMD was 2.48 years. In multivariate analysis, HR status and stage at diagnosis were significantly associated with time to LMD diagnosis (p < 0.05). In triple negative patients, time to LMD was shorter. In patients who were HR positive, time to LMD was longer. Survival from LMD diagnosis was significantly associated with both treatment, as well as positive HR status (multivariate analysis p < 0.05). In conclusion LMD has dismal prognosis in breast cancer patients. HR status contributes to time to LMD diagnosis and survival from LMD diagnosis. The impact of treatment aimed at LMD cannot be ascertained in our retrospective study due to the inherent bias associated with the decision to treat.

  14. Flow cytometric and radioisotopic determinations of platelet survival time in normal cats and feline leukemia virus-infected cats

    SciTech Connect

    Jacobs, R.M.; Boyce, J.T.; Kociba, G.J.

    1986-01-01

    This study demonstrates the potential usefulness of a flow cytometric technique to measure platelet survival time in cats utilizing autologous platelets labeled in vitro with fluorescein isothiocyanate (FITC). When compared with a 51Cr method, no significant differences in estimated survival times were found. Both the 51Cr and FITC-labeling procedures induced similar changes in platelet shape and collagen-induced aggregation. Platelets labeled with FITC had significantly greater volumes compared with those of glutaraldehyde-fixed platelets. These changes were primarily related to the platelet centrifugation and washing procedures rather than the labels themselves. This novel technique potentially has wide applicability to cell circulation time studies as flow cytometry equipment becomes more readily available. Problems with the technique are discussed. In a preliminary study of the platelet survival time in feline leukemia virus (FeLV)-infected cats, two of three cats had significantly reduced survival times using both flow cytometric and radioisotopic methods. These data suggest increased platelet turnover in FeLV-infected cats.

  15. Collagen IV-modified scaffolds improve islet survival and function and reduce time to euglycemia.

    PubMed

    Yap, Woon Teck; Salvay, David M; Silliman, Michael A; Zhang, Xiaomin; Bannon, Zachary G; Kaufman, Dixon B; Lowe, William L; Shea, Lonnie D

    2013-11-01

    Islet transplantation on extracellular matrix (ECM) protein-modified biodegradable microporous poly(lactide-co-glycolide) scaffolds is a potential curative treatment for type 1 diabetes mellitus (T1DM). Collagen IV-modified scaffolds, relative to control scaffolds, significantly decreased the time required to restore euglycemia from 17 to 3 days. We investigated the processes by which collagen IV-modified scaffolds enhanced islet function and mediated early restoration of euglycemia post-transplantation. We characterized the effect of collagen IV-modified scaffolds on islet survival, metabolism, and insulin secretion in vitro and early- and intermediate-term islet mass and vascular density post-transplantation and correlated these with early restoration of euglycemia in a syngeneic mouse model. Control scaffolds maintained native islet morphologies and architectures as well as collagen IV-modified scaffolds in vivo. The islet size and vascular density increased, while β-cell proliferation decreased from day 16 to 113 post-transplantation. Collagen IV-modified scaffolds promoted islet cell viability and decreased early-stage apoptosis in islet cells in vitro-phenomena that coincided with enhanced islet metabolic function and glucose-stimulated insulin secretion. These findings suggest that collagen IV-modified scaffolds promote the early restoration of euglycemia post-transplantation by enhancing islet metabolism and glucose-stimulated insulin secretion. These studies of ECM proteins, in particular collagen IV, and islet function provide key insights for the engineering of a microenvironment that would serve as a platform for enhancing islet transplantation as a viable clinical therapy for T1DM.

  16. Individual quality, survival variation and patterns of phenotypic selection on body condition and timing of nesting in birds

    USGS Publications Warehouse

    Blums, P.; Nichols, J.D.; Hines, J.E.; Lindberg, M.; Mednis, A.

    2005-01-01

    Questions about individual variation in 'quality' and fitness are of great interest to evolutionary and population ecologists. Such variation can be investigated using either a random effects approach or an approach that relies on identifying observable traits that are themselves correlated with fitness components. We used the latter approach with data from 1,925 individual females of three species of ducks (tufted duck, Aythya fuligula; common pochard, Aythya ferina; northern shoveler, Anas clypeata) sampled on their breeding grounds at Engure Marsh, Latvia, for over 15 years. Based on associations with reproductive output, we selected two traits, one morphological (relative body condition) and one behavioral (relative time of nesting), that can be used to characterize individual females over their lifetimes. We then asked whether these traits were related to annual survival probabilities of nesting females. We hypothesized quadratic, rather than monotonic, relationships based loosely on ideas about the likely action of stabilizing selection on these two traits. Parameters of these relationships were estimated directly using ultrastructural models embedded within capture-recapture-band-recovery models. Results provided evidence that both traits were related to survival in the hypothesized manner. For all three species, females that tended to nest earlier than the norm exhibited the highest survival rates, but very early nesters experienced reduced survival and late nesters showed even lower survival. For shovelers, females in average body condition showed the highest survival, with lower survival rates exhibited by both heavy and light birds. For common pochard and tufted duck, the highest survival rates were associated with birds of slightly above-average condition, with somewhat lower survival for very heavy birds and much lower survival for birds in relatively poor condition. Based on results from this study and previous work on reproduction, we conclude that

  17. Analysis of individual- and time-specific covariate effects on survival of Serinus serinus in north-eastern Spain

    USGS Publications Warehouse

    Conroy, M.J.; Senar, J.C.; Domenech, J.

    2002-01-01

    We developed models for the analysis of recapture data for 2678 serins (Serinus serinus) ringed in north-eastern Spain since 1985. We investigated several time- and individual-specific factors as potential predictors of overall mortality and dispersal patterns, and of gender and age differences in these patterns. Time-specific covariates included minimum daily temperature, days below freezing, and abundance of a strong competitor, siskins (Carduelis spinus) during winter, and maximum temperature and rainfall during summer. Individual covariates included body mass (i.e. body condition), and wing length (i.e. flying ability), and interactions between body mass and environmental factors. We found little support of a predictive relationship between environmental factors and survival, but good evidence of relationships between body mass and survival, especially for juveniles. Juvenile survival appears to vary in a curvilinear manner with increasing mass, suggesting that there may exist an optimal mass beyond which increases are detrimental. The mass-survival relationship does seem to be influenced by at least one environmental factor, namely the abundance of wintering siskins. When siskins are abundant, increases in body mass appear to relate strongly to increasing survival. When siskin numbers are average or low the relationship is largely reversed, suggesting that the presence of strong competition mitigates the otherwise largely negative aspects of greater body mass. Wing length in juveniles also appears to be related positively to survival, perhaps largely due to the influence of a few unusually large juveniles with adult-like survival. Further work is needed to test these relationships, ideally under experimentation.

  18. Determine the Influence of Time Held in “Knockdown” Anesthesia on Survival and Stress of Surgically Implanted Juvenile Salmonids

    SciTech Connect

    Woodley, Christa M.; Wagner, Katie A.; Knox, Kasey M.

    2012-01-31

    The Juvenile Salmon Acoustic Telemetry System (JSATS) was developed for the U.S. Army Corp of Engineers Portland District (USACE) to address questions related to survival and performance measures of juvenile salmonids as they pass through the Federal Columbia River Power System (FCRPS). Researchers using JSATS acoustic transmitters (ATs) were tasked with standardizing the surgical implantation procedure to ensure that the stressors of handling and surgery on salmonids were consistent and less likely to cause effects of tagging in survival studies. Researchers questioned whether the exposure time in 'knockdown' anesthesia (or induction) to prepare fish for surgery could influence the survival of study fish (CBSPSC 2011). Currently, fish are held in knockdown anesthesia after they reach Stage 4 anesthesia until the completion of the surgical implantation of a transmitter, varies from 5 to 15 minutes for studies conducted in the Columbia Basin. The Columbia Basin Surgical Protocol Steering Committee (CBSPSC ) expressed concern that its currently recommended 10-minute maximum time limit during which fish are held in anesthetic - tricaine methanesulfonate (MS-222, 80 mg L-1 water) - could increase behavioral and physiological costs, and/or decrease survival of outmigrating juvenile salmonids. In addition, the variability in the time fish are held at Stage 4 could affect the data intended for direct comparison of fish within or among survival studies. Under the current recommended protocol, if fish exceed the 10-minute time limit, they are to be released without surgical implantation, thereby increasing the number of fish handled and endangered species 'take' at the bypass systems for FCRPS survival studies.

  19. Disease-specific survival for patients with multiple myeloma: significant improvements over time in all age groups.

    PubMed

    Libby, Edward; Garcia, David; Quintana, Dulcinea; Fekrazad, M Houman; Bauman, Julie; Ebaid, Ala; Hromas, Robert; Rabinowitz, Ian; Wiggins, Charles

    2014-12-01

    This study analyzed the survival of patients with multiple myeloma. Surveillance, Epidemiology, and End Results (SEER) and Centers for Disease Control and Prevention (CDC) databases were queried to calculate myeloma cause-specific survival curves by the Kaplan and Meier product-limit method. The Cox proportional hazards model was used to assess univariate and multivariate predictors of myeloma cause-specific survival. The outcome of interest was death due to myeloma. Results from a Cox proportional hazards model restricted to age and time period at diagnosis demonstrated that the magnitude of improvement in survival by time period varied by age at diagnosis. Among patients under 60 years at diagnosis, hazard ratios for myeloma cause-specific death decreased by more 50% from the first interval of observation to the last. Hazard ratios decreased during the study period by 39% among patients 60-69 years of age and by 27% among patients who were 70 years of age and older. Survival is improving in patients with myeloma of all ages.

  20. Time trends in breast cancer survival: experience in a single centre, 1975-89.

    PubMed Central

    Bradburn, M. J.; Altman, D. G.; Smith, P.; Fentiman, I. S.; Rubens, R. D.

    1998-01-01

    The aim of this retrospective cohort study was to investigate whether survival of patients with breast cancer has changed over the period 1975-89. A total of 2604 women diagnosed as having invasive breast cancer at a clinical oncology unit in London were followed up for between 5 and 20 years. Patients were divided into four groups according to menstrual status (pre or post) and the staging of cancer (operable or inoperable). For each group, survival from diagnosis was compared between three consecutive 5-year cohorts, both with and without adjustments made for relevant prognostic factors. No temporal patterns were found in patients with inoperable cancer, in whom the survival rate was consistently low. Of women with operable cancers, differences were seen only among post-menopausal women, for whom the best survival patterns were seen in patients diagnosed between 1985-89. This is probably due to tamoxifen being commonly prescribed as adjuvant treatment for this cohort of patients. We cannot explain an apparently worse survival in the group of patients presenting in the early 1980s compared with that observed in the late 1970s. PMID:9667672

  1. Time to Thrive, Not Just Survive: Accumulating Advantage for Women in Science

    NASA Astrophysics Data System (ADS)

    Rolison, Debra

    2005-04-01

    Our departments of science, technology, mathematics, and engineering (STEM) need more women as faculty, and not only to show their undergraduates that a career in academia is a viable path. Their absence warns us that an unhealthy environment exists: unhealthy to those scientists who want fulfilling lives beyond academe and unhealthy to those women, who once they demonstrate productivity, scholarship, and mentorship, still reap less respect, space, salary, funding, and awards than their male colleagues. The recalcitrance of too many of our research universities toward diversifying their faculty is a national disgrace in that these universities covet a diversified student body, but do not reflect that pool of talent onto their faculty. Similar difficulties are apparent among the staff of National and Federal laboratories. Self-reform is not getting it done, and is especially frustrating in light of the historic opportunity to change the demographics as scientists and engineers hired in the 1960s retire. Is it time to apply the logic of Title IX--the loss of Federal funds--for the entrenched inability to increase the number of women represented on STEM faculties? Such a threat may be the impetus necessary for university administrators to create departmental environments that women are willing to call home. The July 2004 release of the GAO report on Women's Participation in the Sciences (which also surveyed DOE facilities) reminded those Federal agencies that fund scientific research that Title IX is the law and that these agencies must begin Title IX assessments of compliance in the STEM departments and institutions they fund. It is past time that women thrive, not just survive in their career homes. Using the mechanistic philosophy of Title IX--denial of resources to recalacitrant departments and laboratories--may be the start of a truly inclusive scientific enterprise in the United States. We must accept this opportunity to redirect the nature of the research

  2. "Under the Tough Old Stars": Ecopedagogical Essays.

    ERIC Educational Resources Information Center

    Jardine, David W.

    This book reviews the pedagogy and ecology of education and the philosophical and historical conditions of these theories, and discusses problems of the curriculum. Contents include: (1) "Introduction: Learning to Work Under the Tough Old Stars"; (2) "Under the Tough Old Stars: Meditation on Pedagogical Hyperactivity and the Mood of Environmental…

  3. Fracture toughness of hot-pressed beryllium

    NASA Technical Reports Server (NTRS)

    Lemon, D. D.; Brown, W. F., Jr.

    1985-01-01

    This paper presents the results of an investigation into the fracture toughness, sustained-load flaw growth, and fatigue-crack propagation resistance of S200E hot-pressed beryllium at room temperature. It also reviews the literature pertaining to the influence of various factors on the fracture toughness of hot-pressed beryllium determined using fatigue-cracked specimens.

  4. Two-step feature selection for predicting survival time of patients with metastatic castrate resistant prostate cancer

    PubMed Central

    Shiga, Motoki

    2016-01-01

    Metastatic castrate resistant prostate cancer (mCRPC) is the major cause of death in prostate cancer patients. Even though some options for treatment of mCRPC have been developed, the most effective therapies remain unclear. Thus finding key patient clinical variables related with mCRPC is an important issue for understanding the disease progression mechanism of mCRPC and clinical decision making for these patients. The Prostate Cancer DREAM Challenge is a crowd-based competition to tackle this essential challenge using new large clinical datasets. This paper proposes an effective procedure for predicting global risks and survival times of these patients, aimed at sub-challenge 1a and 1b of the Prostate Cancer DREAM challenge. The procedure implements a two-step feature selection procedure, which first implements sparse feature selection for numerical clinical variables and statistical hypothesis testing of differences between survival curves caused by categorical clinical variables, and then implements a forward feature selection to narrow the list of informative features. Using Cox’s proportional hazards model with these selected features, this method predicted global risk and survival time of patients using a linear model whose input is a median time computed from the hazard model. The challenge results demonstrated that the proposed procedure outperforms the state of the art model by correctly selecting more informative features on both the global risk prediction and the survival time prediction. PMID:27990267

  5. Effect of coenzyme Q10 on the survival time and lipid peroxidation of adriamycin (doxorubicin) treated mice.

    PubMed

    Shinozawa, S; Etowo, K; Araki, Y; Oda, T

    1984-02-01

    The effect of coenzyme Q10 (Co Q10) was examined on the survival time and lipid peroxidation of adriamycin (ADM)-treated ICR mice. Co Q10 showed a protective effect against a subacute toxicity in mice induced by two intraperitoneal administrations of ADM (15 mg/kg). The group treated orally with 10 mg/kg of Co Q10 showed the longest survival time of all the groups studied (16.81 +/- 10.29 days, mean +/- S.D.) and a significantly longer survival time (p less than 0.001) than the ADM-alone group (7.48 +/- 1.99 days). The inhibitory effect of Co Q10 on the plasma and tissue lipid peroxidation levels did not correlate with the effect of prolonging the survival time of mice. Co Q10 tended to inhibit rises in plasma and liver lipid peroxidation levels induced by ADM administration, but there was no statistically significant difference between treatments. There was a statistically significant different inhibitory effect in the kidney lipid peroxidation levels, but was not in those of the heart.

  6. Relationships of survival time, productivity and cause of death with telomere lengths of cows produced by somatic cell nuclear transfer.

    PubMed

    Konishi, Kazuyuki; Yonai, Miharu; Kaneyama, Kanako; Ito, Satoshi; Matsuda, Hideo; Yoshioka, Hajime; Nagai, Takashi; Imai, Kei

    2011-10-01

    The reproductive ability, milk-producing capacity, survival time and relationships of these parameters with telomere length were investigated in 4 groups of cows produced by somatic cell nuclear transfer (SCNT). Each group was produced using the same donor cells (6 Holstein (1H), 3 Holstein (2H), 4 Jersey (1J) and 5 Japanese Black (1B) cows). As controls, 47 Holstein cows produced by artificial insemination were used. The SCNT cows were artificially inseminated, and multiple deliveries were performed after successive rounds of breeding and conception. No correlation was observed between the telomere length and survival time in the SCNT cows. Causes of death of SCNT cows included accidents, accident-associated infections, inappropriate management, acute mastitis and hypocalcemia. The lifetime productivity of SCNT cows was superior to those of the controls and cell donor cows. All SCNT beef cows with a relatively light burden of lactation remained alive and showed significantly prolonged survival time compared with the cows in the SCNT dairy breeds. These results suggest that the lifetime productivity of SCNT cows was favorable, and their survival time was more strongly influenced by environmental burdens, such as pregnancy, delivery, lactation and feeding management, than by the telomere length.

  7. A laboratory means to produce tough aluminum sheet from powder

    NASA Technical Reports Server (NTRS)

    Singleton, O. R.; Royster, D. M.; Thomas, J. R.

    1990-01-01

    The rapid solidification of aluminum alloys as powder and the subsequent fabrication processes can be used to develop and tailor alloys to satisfy specific aerospace design requirements, including high strength and toughness. Laboratory procedures to produce aluminum powder-metallurgy (PM) materials are efficient but require evidence that the laboratory methods used can produce a product with superior properties. This paper describes laboratory equipment and procedures which can be used to produce tough aluminum PM sheet. The processing of a 2124 + 0.9 percent Zr aluminum alloy powder is used as an example. The fully hardened sheet product is evaluated in terms of properties and microstructure. The key features of the vacuum hot press pressing operation used to consolidate the powder are described. The 2124 + 0.9 percent Zr - T8 temper aluminum sheet produced was both strong (460-490 MPa yield strength) and tough (Kahn Tear unit-propagation- energy values over three times those typical for ingot metallurgy 2024-T81). Both the longitudinal and longitudinal-transverse directions of the sheet were tested. The microstructure was well refined with subgrains of one or two micrometers. Fine dispersoids of Al3Zr in the precipitate free regions adjacent to boundaries are believed to contribute to the improved toughness.

  8. On the development of a new fracture toughness procedure

    NASA Astrophysics Data System (ADS)

    Bernard, M.; Provan, J. W.

    1989-05-01

    The present ASTM test procedure for plane strain fracture toughness is time consuming, expensive, includes specimen thickness requirements, and provides no assurance of a valid K(sub IC). An attempt to circumvent the thickness limitations and to develop a simple, inexpensive method to determine plane strain fracture toughness is reported. A novel disc-shaped specimen geometry was investigated for the determination of the plane strain fracture toughness of metallic materials. The specimen has an axisymmetric notch on its upper face, is clamped on its periphery and is uniformly and perpendicularly loaded around the notch. The frozen stress photoelasticity method was applied to Araldite specimens with fatigue precracked notches to determine the stress intensity factors and the fracture mode. One configuration was retained and using the crack profile from the test, a finite element study was performed to determine the compliance of the specimen geometry. Finally, the fracture toughness of aluminium Al7075-T651 was determined by applying the critical load obtained from rupture tests.

  9. Effects of direct and indirect bleach on dentin fracture toughness.

    PubMed

    Tam, L E; Noroozi, A

    2007-12-01

    There are concerns that tooth-whitening procedures irreversibly damage tooth structure. We investigated the hypothesis that dental bleaches significantly affect dentin structural integrity. The objective was to evaluate the effects of peroxide bleaches on dentin fracture toughness. Compact test specimens, composed of human dentin, were used (n = 10/group). Bleach (16% or 10% carbamide peroxide or 3% hydrogen peroxide) or control material, containing 0.1% sodium fluoride, was applied directly or indirectly to dentin through enamel (6 hrs/day) for 2 or 8 weeks. Fracture toughness results were analyzed by ANOVA and Fisher's LSD test (p < 0.05). There were significant decreases in mean fracture toughness after two- and eight-week direct (19-34% and 61-68%, respectively) and indirect (up to 17% and 37%, respectively) bleach application. The in vitro reduction in dentin fracture toughness caused by the application of peroxide bleaches was greater for the direct application method, longer application time, and higher bleach concentration.

  10. The influence of zinc chloride and zinc oxide nanoparticles on air-time survival in freshwater mussels.

    PubMed

    Gagné, François; Auclair, Joëlle; Peyrot, Caroline; Wilkinson, Kevin J

    2015-01-01

    The purpose of this study was to determine the cumulative effects of exposure to either dissolved zinc or nanozinc oxide (nanoZnO) and air-time survival in freshwater mussels. Mussels were exposed to each forms of zinc for 96h then placed in air to determine survival time. A sub-group of mussels before and after 7days of exposure to air were kept aside for the determination of the following biomarkers: arachidonate-dependent cyclooxygenase (COX) and peroxidase (inflammation and oxidative stress), lipid metabolism (total lipids, esterases activity, HO-glycerol, acetyl CoA and phospholipase A2) and lipid damage (lipid peroxidation [LPO]). The results showed that air-time survival was decreased from a mean value of 18.5days to a mean value of 12days in mussels exposed to 2.5mg/L of nanoZnO although it was not lethal based on shell opening at concentrations below 50mg/L after 96h. In mussels exposed to zinc only, the median lethal concentration was estimated at 16mg/L (10-25 95% CI). The air-time survival did not significantly change in mussels exposed to the same concentration of dissolved Zn. Significant weight losses were observed at 0.5mg/L of nanoZnO and at 2.5mg/L for dissolved zinc chloride, and were also significantly correlated with air-time survival (r=0.53; p<0.01). Air exposure significantly increased COX activity in control mussels and in mussels exposed to 0.5mg/L of nanoZnO and zinc chloride. The data also suggested fatty acid breakdown and β-oxidation. Mussels exposed to contaminants are more susceptible to prolonged exposure to air during low water levels.

  11. Time for College: The Adult Student's Guide to Survival and Success! Second Edition.

    ERIC Educational Resources Information Center

    Siebert, Al; Gilpin, Bernadine

    This guide is designed to help adult students survive and succeed in their college studies. Its 15 chapters contain practical advice on the following topics: obtaining the help available to adult students, confronting and overcoming fears and concerns, enrolling in a program and financing its costs, getting acquainted with the campus during…

  12. Surviving Tight Times or What to Do When the Money Runs Out.

    ERIC Educational Resources Information Center

    Neugebauer, Roger

    1987-01-01

    Recommends strategies to help for-profit and non-profit child care centers survive financial crises. These strategies include discovering the source of the problem; monitoring cash flow; trimming the budget; slowing cash outflow; speeding cash inflow; exploring new income sources; enduring the strain effectively; and avoiding crisis repetition.…

  13. Effect of Elevated Temperature and Loading Rate on Delamination Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Reeder, J. R.; Allen, D. H.; Bradley, W. L.

    2003-01-01

    The effects of temperature and loading rate on delamination growth were studied. The delamination fracture toughness of IM7/K3B was measured at 149 C, 177 C, and 204 C. At each temperature the tests were performed with a variety of loading rates so that the delamination initiated over the range of time from 0.5 sec to 24 hrs. The double cantilever beam (DCB) test was used to measure fracture toughness. The results showed that the delamination resistance is a complicated function of both time and temperature with the effect of temperature either increasing or decreasing the fracture toughness depending on the time scale. The results also showed that the fracture toughness changed by as much as a factor of three as the time scale changed over the five orders of magnitude tested.

  14. Tough soluble aromatic thermoplastic copolyimides

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    2000-01-01

    Tough, soluble, aromatic, thermoplastic copolyimides were prepared by reacting 4,4'-oxydiphthalic anhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydianiline. Alternatively, these copolyimides may be prepared by reacting 4,4'-oxydiphthalic anhydride with 3,4,3',4'-biphenyltetracarboxylic dianhydride and 3,4'-oxydiisocyanate. Also, the copolyimide may be prepared by reacting the corresponding tetra acid and ester precursors of 4,4'-oxydiphthalic anhydride and 3,4,3',4'-biphenyltetracarboxylic dianhydride with 3,4'-oxydianiline. These copolyimides were found to be soluble in common amide solvents such as N,N'-dimethyl acetamide, N-methylpyrrolidinone, and dimethylformamide allowing them to be applied as the fully imidized copolymer and to be used to prepare a wide range of articles.

  15. Continuum Damage Modeling for Dynamic Fracture Toughness of Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Lee, Intaek; Ochi, Yasuo; Bae, Sungin; Song, Jungil

    Short fiber reinforced metal-matrix composites (MMCs) have widely adopted as structural materials and many experimental researches have been performed to study fracture toughness of it. Fracture toughness is often referred as the plane strain(maximum constraint) fracture toughness KIc determined by the well-established standard test method, such as ASTM E399. But the application for dynamic fracture toughness KId has not been popular yet, because of reliance in capturing the crack propagating time. This paper deals with dynamic fracture toughness testing and simulation using finite element method to evaluate fracture behaviors of MMCs manufactured by squeeze casting process when material combination is varied with the type of reinforcement (appearance, size), volume fraction and combination of reinforcements, and the matrix alloy. The instrumented Charphy impact test was used for KId determination and continuum damage model embedded in commercial FE program is used to investigate the dynamic fracture toughness with the influence of elasto-visco-plastic constitutive relation of quasi-brittle fracture that is typical examples of ceramics and some fibre reinforced composites. With Compared results between experimental method and FE simulation, the determination process for KId is presented. FE simulation coupled with continuum damage model is emphasized single shot simulation can predict the dynamic fracture toughness, KId and real time evolution of that directly.

  16. Enhancements to the TOUGH2 Simulator as Implemented in iTOUGH2

    SciTech Connect

    Finsterle, Stefan

    2015-03-01

    iTOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase, multicomponent flow and transport in fractured and porous media [Pruess, 1987, 1991, 2005, 2011; Falta et al., 1995; Pruess et al., 1999, 2002, 2012; Doughty, 2013]. The core of iTOUGH2 contains slightly modified versions of TOUGH2 modules. Most code modifications are editorial and do not affect the simulation results. As a result, standard TOUGH2 input files can be used in iTOUGH2, and identical results are obtained if iTOUGH2 is run in forward mode. However, a number of modifications have been made as described in this report. They enhance the functionality, flexibilitu, and eas-of-use of the forward simulator. This report complements the reports iTOUGH2 User's Guide, iTOUGH2 Command Referecne, and the collection of tutorial examples in iTOUGH2 Sample Problems.

  17. The fracture toughness of borides formed on boronized cold work tool steels

    SciTech Connect

    Sen, Ugur; Sen, Saduman

    2003-06-15

    In this study, the fracture toughness of boride layers of two borided cold work tool steels have been investigated. Boriding was carried out in a salt bath consisting of borax, boric acid, ferro-silicon and aluminum. Boriding was performed at 850 and 950 deg. C for 2 to 7 h. The presence of boride phases were determined by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of borides were measured via Vickers indenter. Increasing of boriding time and temperature leads to reduction of fracture toughness of borides. Metallographic examination showed that boride layer formed on cold work tool steels was compact and smooth.

  18. Managing hospitals in turbulent times: do organizational changes improve hospital survival?

    PubMed Central

    Lee, S Y; Alexander, J A

    1999-01-01

    OBJECTIVE: To examine (1) the degree to which organizational changes affected hospital survival; (2) whether core and peripheral organizational changes affected hospital survival differently; and (3) how simultaneous organizational changes affected hospital survival. DATA SOURCES: AHA Hospital Surveys, the Area Resource File, and the AHA Hospital Guides, Part B: Multihospital Systems. STUDY DESIGN: The study employed a longitudinal panel design. We followed changes in all community hospitals in the continental United States from 1981 through 1994. The dependent variable, hospital closure, was examined as a function of multiple changes in a hospital's core and peripheral structures as well as the hospital's organizational and environmental characteristics. Cox regression models were used to test the expectations that core changes increased closure risk while peripheral changes decreased such risk, and that simultaneous core and peripheral changes would lead to higher risk of closure. PRINCIPAL FINDINGS: Results indicated more peripheral than core changes in community hospitals. Overall, findings contradicted our expectations. Change in specialty, a core change, was beneficial for hospitals, because it reduced closure risk. The two most frequent peripheral changes, downsizing and leadership change, were positively associated with closure. Simultaneous organizational changes displayed a similar pattern: multiple core changes reduced closure risk, while multiple peripheral changes increased the risk. These patterns held regardless of the level of uncertainty in hospital environments. CONCLUSIONS: Organizational changes are not all beneficial for hospitals, suggesting that hospital leaders should be both cautious and selective in their efforts to turn their hospitals around. PMID:10536977

  19. fur (-) mutation increases the survival time of Escherichia coli under photooxidative stress in aquatic environments.

    PubMed

    Darcan, C; Aydin, Ebru

    2012-09-01

    We investigated the survival of the wild type Escherichia coli (QC771) and fur- mutant strain (QC1732) under photooxidative stress in different water sources. The survival of fur- mutant and wild type E. coli was seen as a significant decrease in the visible light samples in the presence of methylene blue (MB). The fur-E. coli strain lived longer than the wild type E. coli strain on exposure to MB and visible light, which generates singlet oxygen, in both lake water (48-h) and pure water (16-h). It is interesting to note that the survival of both wild type and the fur- mutant strain was more protected at 24 °C than at other temperatures. The Fur protein does not have any relation to the entry of E. coli into the viable but nonculturable state (VBNC) under photooxidative stress. This is the first study which shows that fur- mutation increases the resistance of E. coli to photooxidative stress in aquatic environments, and the Fur protein does not have any relation to the entry of E. coli into the VBNC state.

  20. Time-related survival effects of two gluconasturtiin hydrolysis products on the terrestrial isopod Porcellio scaber.

    PubMed

    van Ommen Kloeke, A E Elaine; Jager, Tjalling; van Gestel, Cornelis A M; Ellers, Jacintha; van Pomeren, Marinda; Krommenhoek, Thibault; Styrishave, Bjarne; Hansen, Martin; Roelofs, Dick

    2012-11-01

    Glucosinolates are compounds produced by commercial crops which can hydrolyse in a range of natural toxins that may exert detrimental effects on beneficial soil organisms. This study examined the effects of 2-phenylethyl isothiocyanate and 3-phenylpropionitrile on the survival and growth of the woodlouse Porcellio scaber exposed for 28 d. 2-Phenylethyl isothiocyanate dissipated from the soil with half-lives ranging from 19 to 96 h. Exposure through soil showed toxic effects only on survival. The LC50s after 28 d were significantly different at 65.3 mg kg(-1) for 2-phenylethyl isothiocyanate and 155 mg kg(-1) for 3-phenylpropionitrile. A toxicokinetic-toxicodynamic (TKTD) approach, however, revealed that both compounds in fact have very similar effect patterns. The TKTD model was better suited to interpret the survival data than descriptive dose-response analysis (LC(x)), accounting for the fast dissipation of the compounds in the soil. Found effects were within environmentally relevant concentrations. Care should therefore be taken before allowing these natural toxins to enter soil ecosystems in large quantities.

  1. Patients with type 2 diabetes benefit from primary care-based disease management: a propensity score matched survival time analysis.

    PubMed

    Drabik, Anna; Büscher, Guido; Thomas, Karsten; Graf, Christian; Müller, Dirk; Stock, Stephanie

    2012-08-01

    This study aimed to assess the impact of a nationwide German diabetes mellitus disease management program (DMP) on survival time and costs in comparison to routine care. The authors conducted a retrospective observational cohort study using routine administration data from Germany's largest sickness fund to identify insured suffering from diabetes in 2002. A total of 95,443 insured with type 2 diabetes mellitus who were born before January 1, 1962 met the defined inclusion criteria, resulting in 19,888 pairs of DMP participants and nonparticipants matched for socioeconomic and health status using propensity score matching methods. This is the first time propensity score matching has been used to evaluate a survival benefit of DMPs. In the time frame analyzed (3 years), mean survival time for the DMP group was 1045 days vs. 985 days for the routine care group (P<0.001). Mean daily hospital and total costs (including DMP administration and medical costs) were lower for the DMP group in the case of deceased insureds (92€ vs. 139€ and 122€ vs. 169€, respectively) as well as for censored observations (6€ vs. 7€ and 12.9€ vs. 13.4€, respectively). Mean daily drug costs were slightly lower for deceased insured in the DMP group (difference 0.6€), while no identifiable difference was found for censored observations. In this study, insured who were enrolled in a DMP for diabetes mellitus in the German Statutory Health Insurance showed a significant benefit in survival time. They also incurred lower costs compared to propensity score matched insured in routine care.

  2. Using Simulation to Interpret a Discrete Time Survival Model in a Complex Biological System: Fertility and Lameness in Dairy Cows

    PubMed Central

    Hudson, Christopher D.; Huxley, Jonathan N.; Green, Martin J.

    2014-01-01

    The ever-growing volume of data routinely collected and stored in everyday life presents researchers with a number of opportunities to gain insight and make predictions. This study aimed to demonstrate the usefulness in a specific clinical context of a simulation-based technique called probabilistic sensitivity analysis (PSA) in interpreting the results of a discrete time survival model based on a large dataset of routinely collected dairy herd management data. Data from 12,515 dairy cows (from 39 herds) were used to construct a multilevel discrete time survival model in which the outcome was the probability of a cow becoming pregnant during a given two day period of risk, and presence or absence of a recorded lameness event during various time frames relative to the risk period amongst the potential explanatory variables. A separate simulation model was then constructed to evaluate the wider clinical implications of the model results (i.e. the potential for a herd’s incidence rate of lameness to influence its overall reproductive performance) using PSA. Although the discrete time survival analysis revealed some relatively large associations between lameness events and risk of pregnancy (for example, occurrence of a lameness case within 14 days of a risk period was associated with a 25% reduction in the risk of the cow becoming pregnant during that risk period), PSA revealed that, when viewed in the context of a realistic clinical situation, a herd’s lameness incidence rate is highly unlikely to influence its overall reproductive performance to a meaningful extent in the vast majority of situations. Construction of a simulation model within a PSA framework proved to be a very useful additional step to aid contextualisation of the results from a discrete time survival model, especially where the research is designed to guide on-farm management decisions at population (i.e. herd) rather than individual level. PMID:25101997

  3. Juvenile Passage Program : A Plan for Estimating Smolt Travel Time and Survival in the Snake and Columbia Rivers

    SciTech Connect

    Skalski, J. R.; Giorgi, Albert E.

    1993-10-01

    A plan for developing a program to evaluate juvenile salmon passage is presented that encompasses the Snake (Lower Granite to McNary Dams), Mid-Columbia (Wells to McNary Dams), and Lower Columbia (McNary to Bonneville Dams) segments of the Snake/Columbia River system. This plan focuses on the use of PIT-tag technology to routinely estimate travel times and reach survival of outmigrating yearling and subyearling Chinook, sockeye, and steelhead during spring and summer months. The proposed program outlines tagging studies that could be implemented in (a) 1992, (b) near term (1993--94), and (c) long term (1995 to the next decade). The evolution of this program over time parallels plans to establish additional PIT-tag detector and slide-gate systems at Little Goose, Lower Monumental, McNary, John Day, and Bonneville Dams. The eventual ability to concurrently estimate travel time and survival of release groups will permit evaluation of travel time-survival-flow relationships and identify possible mortality {open_quotes}hot spots{close_quotes} for remediation.

  4. COMPARATIVE STUDY ON LIVER TRANSPLANTATION WITH AND WITHOUT HEPATOCELLULAR CARCINOMA WITH CIRRHOSIS: ANALYSIS OF MELD, WAITING TIME AND SURVIVAL

    PubMed Central

    de FREITAS, Alexandre Coutinho Teixeira; SHIGUIHARA, Rafael Shinmi; MONTEIRO, Ruan Teles; PAZETO, Thiago Linck; COELHO, Júlio Cezar Uili

    2016-01-01

    Background : Liver transplantation is the usual treatment for hepatocellular carcinoma. Aim: To analyze the MELD score, waiting time and three month and one year survival for liver transplantation in cirrhotic patients affected by hepatocellular carcinoma or not. Methods : This was a retrospective, observational and analytical study of 93 patients submitted to liver transplantation. Results : There were 28 hepatocellular carcinoma and 65 non-hepatocellular carcinoma patients with no differences related to age and sex distribution. The main causes of cirrhosis on hepatocellular carcinoma were hepatitis C virus (57.1%) and hepatitis B virus (28.5%), more frequent than non-hepatocellular carcinoma patients, which presented 27.7% and 4.6% respectively. The physiological and exception MELD score on hepatocellular carcinoma were 11.9 and 22.3 points. On non-hepatocellular carcinoma, it was 19.4 points, higher than the physiological MELD and lower than the exception MELD on hepatocellular carcinoma. The waiting time for transplantation was 96.2 days for neoplasia, shorter than the waiting time for non-neoplasia patients, which was 165.6 days. Three month and one year survival were 85.7% and 78.6% for neoplasia patients, similar to non-neoplasia, which were 77% and 75.4%. Conclusion: Hepatocellular carcinoma patients presented lower physiological MELD score, higher exception MELD score and shorter waiting time for transplantation when compared to non-hepatocellular carcinoma patients. Three month and one year survival were the same between the groups. PMID:27120734

  5. Cyclicality, Mortality, and the Value of Time: The Case of Coffee Price Fluctuations and Child Survival in Colombia

    PubMed Central

    Miller, Grant; Urdinola, B. Piedad

    2011-01-01

    Recent studies demonstrate procyclical mortality in wealthy countries, but there are reasons to expect a countercyclical relationship in developing nations. We investigate how child survival in Colombia responds to fluctuations in world Arabica coffee prices – and document starkly procyclical child deaths. In studying this result’s behavioral underpinnings, we highlight that: (1) The leading determinants of child health are inexpensive but require considerable time, and (2) As the value of time declines with falling coffee prices, so does the relative price of health. We find a variety of direct evidence consistent with the primacy of time in child health production. PMID:22090662

  6. Effects of flavorings, storage conditions, and storage time on survival of Staphylococcus aureus in Sürk cheese.

    PubMed

    Masatcioğlu, Tuğrul M; Avşar, Yahya K

    2005-07-01

    The objectives of this study were to determine the cumulative effects of flavorings (chili pepper, thyme, mint, cumin, nutmeg, allspice, clove, cinnamon, black pepper, salt, and hot red pepper paste), storage conditions, and storage time on the survival of Staphylococcus aureus in Sürk cheese and to monitor the associated chemical changes. Sürk cheese, a traditional Turkish cheese, was produced by heating diluted nonfat yogurt and adding flavorings to the resultant acid-heat curd. The cheese was later inoculated with S. aureus, shaped conically, and stored aerobically for mold growth and anaerobically in olive oil for 30 days at room temperature. The moisture content of aerobically stored cheese decreased over time and led to increases in total solids, salt, salt-in-moisture, and ash content during ripening (P < 0.05). The presence or absence of the flavorings had no significant effect, whereas storage conditions and storage duration decreased the survival of S. aureus (P < 0.05).

  7. Investigating Progression in Substance Use Initiation Using a Discrete-Time Multiple Event Process Survival Mixture (MEPSUM) Approach

    PubMed Central

    Richmond-Rakerd, Leah S.; Fleming, Kimberly A.; Slutske, Wendy S.

    2015-01-01

    The order and timing of substance initiation has significant implications for later problematic patterns of use. Despite the need to study initiation from a multivariate framework, survival analytic methods typically cannot accommodate more than two substances in one model. The Discrete-Time Multiple Event Process Survival Mixture (MEPSUM; Dean, Bauer, & Shanahan, 2014) model represents an advance by incorporating more than two outcomes and enabling establishment of latent classes within a multivariate hazard distribution. Employing a MEPSUM approach, we evaluated patterns of tobacco, alcohol, and cannabis initiation in the National Longitudinal Study of Adolescent to Adult Health (N=18,923). We found four classes that differed in their ages and ordering of peak initiation risk. Demographics, externalizing psychopathology, and personality significantly predicted class membership. Sex differences in the association between delinquency and initiation patterns also emerged. Findings support the utility of the MEPSUM approach in elucidating developmental pathways underlying clinically relevant phenomena. PMID:27127730

  8. Mycobacterium avium subsp. paratuberculosis survival during fermentation of soured milk products detected by culture and quantitative real time PCR methods.

    PubMed

    Klanicova, B; Slana, I; Roubal, P; Pavlik, I; Kralik, P

    2012-07-02

    Mycobacterium avium paratuberculosis (MAP), etiological agent of paratuberculosis in ruminants, is able to survive extreme conditions like very low pH (stomach), high temperature (pasteurization) or low temperature (refrigerated storage). Cheese, infant powder milk, cream and other milk and dairy products might thus be considered as possible sources of MAP for humans. The aim of this study was to investigate the survival of two MAP field isolates during fermentation of three different types of soured milk products (SMP; yogurt, acidophilus milk and kefir) under laboratory conditions. Pasteurized MAP-free milk was artificially contaminated with 10(6)MAPcells/mL and survival and absolute numbers of MAP were monitored during fermentation (4 or 16 h) and after six weeks of storage at 4°C by culture and quantitative real time PCR (qPCR). Viability of MAP was determined by culture using Herrold's egg yolk medium and Middlebrook 7H10 with antibiotics, supplemented with Mycobactin J and incubated at 37°C for up to 12 weeks. The absolute numbers of MAP were quantified by previously published qPCR assays targeting F57 and IS900 loci in MAP genome. We herein confirm that MAP can survive pH reduction, however, longer exposure to pH below 4 in SMP seems to be critical because it inhibits growth. Therefore, it is suggested that probiotic cultures that can decrease pH below 4 during fermentation could provide better inactivation of MAP in SMP.

  9. 46 CFR 54.05-6 - Toughness test temperatures.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Toughness test temperatures. 54.05-6 Section 54.05-6... Toughness Tests § 54.05-6 Toughness test temperatures. Each toughness test must be conducted at temperatures not warmer than −20 °F or 10 °F below the minimum service temperature, whichever is lower, except...

  10. 46 CFR 54.05-6 - Toughness test temperatures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Toughness test temperatures. 54.05-6 Section 54.05-6... Toughness Tests § 54.05-6 Toughness test temperatures. Each toughness test must be conducted at temperatures not warmer than −20 °F or 10 °F below the minimum service temperature, whichever is lower, except...

  11. 46 CFR 54.05-6 - Toughness test temperatures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Toughness test temperatures. 54.05-6 Section 54.05-6... Toughness Tests § 54.05-6 Toughness test temperatures. Each toughness test must be conducted at temperatures not warmer than −20 °F or 10 °F below the minimum service temperature, whichever is lower, except...

  12. 46 CFR 54.05-6 - Toughness test temperatures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Toughness test temperatures. 54.05-6 Section 54.05-6... Toughness Tests § 54.05-6 Toughness test temperatures. Each toughness test must be conducted at temperatures not warmer than −20 °F or 10 °F below the minimum service temperature, whichever is lower, except...

  13. 46 CFR 54.05-6 - Toughness test temperatures.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Toughness test temperatures. 54.05-6 Section 54.05-6... Toughness Tests § 54.05-6 Toughness test temperatures. Each toughness test must be conducted at temperatures not warmer than −20 °F or 10 °F below the minimum service temperature, whichever is lower, except...

  14. 10 CFR Appendix G to Part 50 - Fracture Toughness Requirements

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Fracture Toughness Requirements G Appendix G to Part 50..., App. G Appendix G to Part 50—Fracture Toughness Requirements I. Introduction and scope. II. Definitions. III. Fracture toughness tests. IV. Fracture toughness requirements. I. Introduction and...

  15. 10 CFR Appendix G to Part 50 - Fracture Toughness Requirements

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Fracture Toughness Requirements G Appendix G to Part 50..., App. G Appendix G to Part 50—Fracture Toughness Requirements I. Introduction and scope. II. Definitions. III. Fracture toughness tests. IV. Fracture toughness requirements. I. Introduction and...

  16. Low expansion superalloy with improved toughness

    DOEpatents

    Smith, Darrell F.; Stein, Larry I.; Hwang, Il S.

    1995-01-01

    A high strength, low coefficient of thermal expansion superalloy exhibiting improved toughness over a broad temperature range down to about 4.degree. K. The composition is adapted for use with wrought superconducting sheathing.

  17. Toughness and strength of nanocrystalline graphene

    PubMed Central

    Shekhawat, Ashivni; Ritchie, Robert O.

    2016-01-01

    Pristine monocrystalline graphene is claimed to be the strongest material known with remarkable mechanical and electrical properties. However, graphene made with scalable fabrication techniques is polycrystalline and contains inherent nanoscale line and point defects—grain boundaries and grain-boundary triple junctions—that lead to significant statistical fluctuations in toughness and strength. These fluctuations become particularly pronounced for nanocrystalline graphene where the density of defects is high. Here we use large-scale simulation and continuum modelling to show that the statistical variation in toughness and strength can be understood with ‘weakest-link' statistics. We develop the first statistical theory of toughness in polycrystalline graphene, and elucidate the nanoscale origins of the grain-size dependence of its strength and toughness. Our results should lead to more reliable graphene device design, and provide a framework to interpret experimental results in a broad class of two-dimensional materials. PMID:26817712

  18. Low expansion superalloy with improved toughness

    DOEpatents

    Smith, D.F.; Stein, L.I.; Hwang, I.S.

    1995-06-20

    A high strength, low coefficient of thermal expansion superalloy exhibiting improved toughness over a broad temperature range down to about 4 K is disclosed. The composition is adapted for use with wrought superconducting sheathing.

  19. Toughness and strength of nanocrystalline graphene

    DOE PAGES

    Shekhawat, Ashivni; Ritchie, Robert O.

    2016-01-28

    Pristine monocrystalline graphene is claimed to be the strongest material known with remarkable mechanical and electrical properties. However, graphene made with scalable fabrication techniques is polycrystalline and contains inherent nanoscale line and point defects—grain boundaries and grain-boundary triple junctions—that lead to significant statistical fluctuations in toughness and strength. These fluctuations become particularly pronounced for nanocrystalline graphene where the density of defects is high. Here we use large-scale simulation and continuum modelling to show that the statistical variation in toughness and strength can be understood with ‘weakest-link’ statistics. We develop the first statistical theory of toughness in polycrystalline graphene, and elucidatemore » the nanoscale origins of the grain-size dependence of its strength and toughness. Lastly, our results should lead to more reliable graphene device design, and provide a framework to interpret experimental results in a broad class of two-dimensional materials.« less

  20. Toughness and strength of nanocrystalline graphene

    SciTech Connect

    Shekhawat, Ashivni; Ritchie, Robert O.

    2016-01-28

    Pristine monocrystalline graphene is claimed to be the strongest material known with remarkable mechanical and electrical properties. However, graphene made with scalable fabrication techniques is polycrystalline and contains inherent nanoscale line and point defects—grain boundaries and grain-boundary triple junctions—that lead to significant statistical fluctuations in toughness and strength. These fluctuations become particularly pronounced for nanocrystalline graphene where the density of defects is high. Here we use large-scale simulation and continuum modelling to show that the statistical variation in toughness and strength can be understood with ‘weakest-link’ statistics. We develop the first statistical theory of toughness in polycrystalline graphene, and elucidate the nanoscale origins of the grain-size dependence of its strength and toughness. Lastly, our results should lead to more reliable graphene device design, and provide a framework to interpret experimental results in a broad class of two-dimensional materials.

  1. Tough, High-Performance, Thermoplastic Addition Polymers

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H.; Proctor, K. Mason; Gleason, John; Morgan, Cassandra; Partos, Richard

    1991-01-01

    Series of addition-type thermoplastics (ATT's) exhibit useful properties. Because of their addition curing and linear structure, ATT polymers have toughness, like thermoplastics, and easily processed, like thermosets. Work undertaken to develop chemical reaction forming stable aromatic rings in backbone of ATT polymer, combining high-temperature performance and thermo-oxidative stability with toughness and easy processibility, and minimizing or eliminating necessity for tradeoffs among properties often observed in conventional polymer syntheses.

  2. Evaluation of prognostic factors effect on survival time in patients with colorectal cancer, based on Weibull Competing-Risks Model

    PubMed Central

    Moamer, Soraya; Baghestani, Ahmadreza; Pourhoseingholi, Mohamad Amin; Hajizadeh, Nastaran; Ahmadi, Farzaneh; Norouzinia, Mohsen

    2017-01-01

    Aim: The aim of this study was to assess the association between survival of patients with colorectal cancer and prognostic factors in a competing risk parametric model using Weibull distribution. Background: The prognosis of colorectal cancer is relatively good in terms of survival time. In many prognostic studies, patients may be exposed to several types of competing events. These different causes of death are called competing risks. Methods: Data was recorded from 372 patients with colorectal cancer who registered in the Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences (Tehran, Iran) from 2004 to 2015 in a retrospective study. Analysis was performed using competing risks model and Weibull distribution. Software used for data analysis was R, and significance level was regarded as 0.05. Results: The result indicated that, at the end of follow-up, 111 (29.8%) deaths were from colorectal cancer and 14 (3.8%) deaths were due to other diseases. The average body mass index (BMI) was 24.61(SD 3.98). The mean survival time for a patient in 372 was 62.05(SD 48.78) month with median equals to 48 months. According to competing-risks method, only stageIII (HR, 1.69; 95% CI, 1.246-2.315 ), stageIV( HR, 4.51; 95% CI,2.91-6.99 ) and BMI( HR, 0.96; 95% CI, 0.96-0.975) have a significant effect on patient’s survival time. Conclusion: This study indicated pathologic stage (III,IV) and BMI as the prognosis, using a Weibull model with competing risks analysis, while other models without the competing events lead to significant predictors which may be due to over-estimation.

  3. Comparing proportional hazards and accelerated failure time models for survival analysis.

    PubMed

    Orbe, Jesus; Ferreira, Eva; Núñez-Antón, Vicente

    2002-11-30

    This paper describes a method proposed for a censored linear regression model that can be used in the context of survival analysis. The method has the important characteristic of allowing estimation and inference without knowing the distribution of the duration variable. Moreover, it does not need the assumption of proportional hazards. Therefore, it can be an interesting alternative to the Cox proportional hazards models when this assumption does not hold. In addition, implementation and interpretation of the results is simple. In order to analyse the performance of this methodology, we apply it to two real examples and we carry out a simulation study. We present its results together with those obtained with the traditional Cox model and AFT parametric models. The new proposal seems to lead to more precise results.

  4. A new plateau in the dose-survival-time response of the golden hamster (Mesocricetus auratus) from whole body irradiation.

    PubMed

    Tsubouchi, S; Matsuzawa, T

    1981-07-01

    The survival time of golden hamsters (Mesocricetus auratus) after whole-body 60Co-gamma-irradiation in the range of 600 to 200 000 rad was investigated. The two plateaus of the dose-survival curve which correspond to bone marrow and gastrointestinal death are similar to those of other species such as mice, rats and mongolian gerbils. A new plateau occurring 40-57 hours after doses of 30 000 to 60 000 rad, where there is a little reduction in survival time, has been found. It is in addition to the well recognized central nevous system (CNS) syndrome. This plateau is observed only in golden hamsters, presumably because of their relatively high resistence to CNS syndrome. Experiments involved partial body irradiation of the animals indicate that the target is in the cephalic one-third of abdomen. The new segment may well indicate a new type of acute somatic radiation injury different from the well known bone marrow, gastrointestinal and CNS syndromes.

  5. Clinical patterns in extremely preterm (22 to 24 weeks of gestation) infants in relation to survival time and prognosis.

    PubMed

    Iijima, Shigeo; Arai, Hiroko; Ozawa, Yuri; Kawase, Yasuhiro; Uga, Naoki

    2009-06-01

    We investigated time-related predictors of death or neurological sequelae in extremely preterm infants (EPI) born at 22 to 24 weeks' gestation by categorizing clinical patterns according to their survival time and morbidity. Data on 113 infants born at 22 to 24 weeks' gestation from January 1991 through April 2006 were analyzed by a case-control approach. Cesarean section, Apgar score survived >or= 24 hours, pulmonary hemorrhage and intraventricular hemorrhage (IVH) were significantly associated with death by day 6. Among those surviving >or= 7 days, sepsis and severe IVH were significantly associated with death. Assessment of survivors at a minimum follow-up period of 2 years revealed that protracted mechanical ventilation was significantly associated with a poor neurological outcome. There are various characteristic key events in relation to the outcome at different ages of life in EPI born at 22 to 24 weeks' gestation. Clinicians and parents should discuss management options for the infant on the basis of these findings.

  6. Wind Speed during Migration Influences the Survival, Timing of Breeding, and Productivity of a Neotropical Migrant, Setophaga petechia

    PubMed Central

    Drake, Anna; Rock, Christine A.; Quinlan, Sam P.; Martin, Michaela; Green, David J.

    2014-01-01

    Over the course of the annual cycle, migratory bird populations can be impacted by environmental conditions in regions separated by thousands of kilometers. We examine how climatic conditions during discrete periods of the annual cycle influence the demography of a nearctic-neotropical migrant population of yellow warblers (Setophaga petechia), that breed in western Canada and overwinter in Mexico. We demonstrate that wind conditions during spring migration are the best predictor of apparent annual adult survival, male arrival date, female clutch initiation date and, via these timing effects, annual productivity. We find little evidence that conditions during the wintering period influence breeding phenology and apparent annual survival. Our study emphasizes the importance of climatic conditions experienced by migrants during the migratory period and indicates that geography may play a role in which period most strongly impacts migrant populations. PMID:24828427

  7. Method to increase the toughness of aluminum-lithium alloys at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Sankaran, Krishnan K. (Inventor); Sova, Brian J. (Inventor); Babel, Henry W. (Inventor)

    2006-01-01

    A method to increase the toughness of the aluminum-lithium alloy C458 and similar alloys at cryogenic temperatures above their room temperature toughness is provided. Increasing the cryogenic toughness of the aluminum-lithium alloy C458 allows the use of alloy C458 for cryogenic tanks, for example for launch vehicles in the aerospace industry. A two-step aging treatment for alloy C458 is provided. A specific set of times and temperatures to age the aluminum-lithium alloy C458 to T8 temper is disclosed that results in a higher toughness at cryogenic temperatures compared to room temperature. The disclosed two-step aging treatment for alloy 458 can be easily practiced in the manufacturing process, does not involve impractical heating rates or durations, and does not degrade other material properties.

  8. Improving the toughness of ultrahigh strength steel

    NASA Astrophysics Data System (ADS)

    Sato, Koji

    2002-01-01

    The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the toughening mechanism of the Fe/Co/Ni/Cr/Mo/C steel, AerMet 100, which has the highest toughness/strength combination among all commercial ultrahigh strength steels. The possibility of improving the toughness of this steel was examined by considering several relevant factors. Chapter 1 reviews the mechanical properties of ultrahigh strength steels and the physical metallurgy of AerMet 100. It also describes the fracture mechanisms of steel, i.e. ductile microvoid coalescence, brittle transgranular cleavage, and intergranular separation. Chapter 2 examines the strength-toughness relationship for three heats of AerMet 100. A wide variation of toughness is obtained at the same strength level. The toughness varies despite the fact that all heat fracture in the ductile fracture mode. The difference originates from the inclusion content. Lower inclusion volume fraction and larger inclusion spacing gives rise to a greater void growth factor and subsequently a higher fracture toughness. The fracture toughness value, JIc, is proportional to the particle spacing of the large non-metallic inclusions. Chapter 3 examines the ductile-brittle transition of AerMet 100 and the effect of a higher austenitization temperature, using the Charpy V-notch test. The standard heat treatment condition of AerMet 100 shows a gradual ductile-brittle transition due to its fine effective grain size. Austenitization at higher temperature increases the prior austenite grain size and packet size, leading to a steeper transition at a higher temperature. Both transgranular cleavage and intergranular separation are observed in the brittle fracture mode. Chapter 4 examines the effect of inclusion content, prior austenite grain size, and the amount of austenite on the strength-toughness relationship. The highest toughness is achieved by low inclusion content, small prior austenite grain size

  9. On the fracture toughness of advanced materials

    SciTech Connect

    Launey, Maximilien E.; Ritchie, Robert O.

    2008-11-24

    Few engineering materials are limited by their strength; rather they are limited by their resistance to fracture or fracture toughness. It is not by accident that most critical structures, such as bridges, ships, nuclear pressure vessels and so forth, are manufactured from materials that are comparatively low in strength but high in toughness. Indeed, in many classes of materials, strength and toughness are almost mutually exclusive. In the first instance, such resistance to fracture is a function of bonding and crystal structure (or lack thereof), but can be developed through the design of appropriate nano/microstructures. However, the creation of tough microstructures in structural materials, i.e., metals, polymers, ceramics and their composites, is invariably a compromise between resistance to intrinsic damage mechanisms ahead of the tip of a crack (intrinsic toughening) and the formation of crack-tip shielding mechanisms which principally act behind the tip to reduce the effective 'crack-driving force' (extrinsic toughening). Intrinsic toughening is essentially an inherent property of a specific microstructure; it is the dominant form of toughening in ductile (e.g., metallic) materials. However, for most brittle (e.g., ceramic) solids, and this includes many biological materials, it is largely ineffective and toughening conversely must be developed extrinsically, by such shielding mechanisms as crack bridging. From a fracture mechanics perspective, this results in toughening in the form of rising resistance-curve behavior where the fracture resistance actually increases with crack extension. The implication of this is that in many biological and high-strength advanced materials, toughness is developed primarily during crack growth and not for crack initiation. This is an important realization yet is still rarely reflected in the way that toughness is measured, which is invariably involves the use of single-value (crack-initiation) parameters such as the

  10. TOUGH+ v1.5 Core Code

    SciTech Connect

    Moridis, George J.

    2015-08-27

    TOUGH+ v1.5 is a numerical code for the simulation of multi-phase, multi-component flow and transport of mass and heat through porous and fractured media, and represents the third update of the code since its first release [Moridis et al., 2008]. TOUGH+ is a successor to the TOUGH2 [Pruess et al., 1991; 2012] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95/2003, and can be run on any computational platform (workstations, PC, Macintosh). TOUGH+ v1.5 employs dynamic memory allocation, thus minimizing storage requirements. It has a completely modular structure, follows the tenets of Object-Oriented Programming (OOP), and involves the advanced features of FORTRAN 95/2003, i.e., modules, derived data types, the use of pointers, lists and trees, data encapsulation, defined operators and assignments, operator extension and overloading, use of generic procedures, and maximum use of the powerful intrinsic vector and matrix processing operations. TOUGH+ v1.5 is the core code for its family of applications, i.e., the part of the code that is common to all its applications. It provides a description of the underlying physics and thermodynamics of non-isothermal flow, of the mathematical and numerical approaches, as well as a detailed explanation of the general (common to all applications) input requirements, options, capabilities and output specifications. The core code cannot run by itself: it needs to be coupled with the code for the specific TOUGH+ application option that describes a particular type of problem. The additional input requirements specific to a particular TOUGH+ application options and related illustrative examples can be found in the corresponding User’s Manual.

  11. Neurogenesis and the Spacing Effect: Learning over Time Enhances Memory and the Survival of New Neurons

    ERIC Educational Resources Information Center

    Sisti, Helene M.; Glass, Arnold L.; Shors, Tracey J.

    2007-01-01

    Information that is spaced over time is better remembered than the same amount of information massed together. This phenomenon, known as the spacing effect, was explored with respect to its effect on learning and neurogenesis in the adult dentate gyrus of the hippocampal formation. Because the cells are generated over time and because learning…

  12. Trichinella spiralis infection changes immune response in mice performed abdominal heterotopic cardiac transplantation and prolongs cardiac allograft survival time.

    PubMed

    Deng, Gengguo; Deng, Ronghai; Yao, Jianping; Liao, Bing; Chen, Yinghua; Wu, Zhongdao; Hu, Hongxing; Zhou, Xingwang; Ma, Yi

    2016-01-01

    Allograft rejection has been an obstacle for long-term survival of patients for many years. Current strategies for transplant rejection are not as optimal as we expected, especially for long-term treatments. Trichinella spiralis, a nematode parasitized in mammalian muscle and as an invader, maintains harmonious with host in the long term by evading host immune attack. To determine whether T. spiralis infection impacts on allograft rejection, we performed mice cardiac allograft transplantation model by using BALB/c (H-2(b)) mice as donors and C57BL/6 (H-2(b)) mice orally infected with 300 muscle larvae for 28 days as recipients. Graft survival was monitored by daily palpation of the abdomen; histologic change was observed by H&E stain; and CD4(+), CD8(+), CD4(+)IFN-γ(+), and CD4(+)IL-17(+) T cells and regulatory T cells were examined with the use of flow cytometry. Serum cytokine levels were measured by Luminex. Finally, we found that mean survival time of cardiac allografts in T. spiralis group was 23.40 ± 1.99 days, while the vehicle control group was 10.60 ± 0.75 days. Furthermore, we observed alleviated histological changes in the heart allograft, decreased corresponding CD8(+) T cells, suppressed Th1 and Th17 responses, and increased regulatory T cell frequency in a murine cardiac transplantation model at day 7 post-transplantation in experimental group. These data suggest that T. spiralis infection resulted in prolonged allograft survival following murine cardiac transplantation, with suppressed Th1/Th17 responses and augmented regulatory T cells.

  13. Vitamin D Depletion in Pregnancy Decreases Survival Time, Oxygen Saturation, Lung Weight and Body Weight in Preterm Rat Offspring

    PubMed Central

    Lykkedegn, Sine; Sorensen, Grith Lykke; Beck-Nielsen, Signe Sparre; Pilecki, Bartosz; Duelund, Lars; Marcussen, Niels; Christesen, Henrik Thybo

    2016-01-01

    Animal studies suggest a role of vitamin D in fetal lung development although not studied in preterm animals. We tested the hypothesis that vitamin D depletion aggravates respiratory insufficiency in preterm rat offspring. Furthermore, the effects of vitamin D depletion on growth and lung surfactant were investigated. Female Sprague-Dawley rats were randomly assigned low vitamin D (VDL) or control diet before mating and followed with serum 25-hydroxyvitamin D (s-25(OH)D) determinations. After cesarean section at gestational day 19 (E19) or day 22 (E22), placental weight, birth weight, crown-rump-length (CRL), oxygenation (SaO2) at 30 min and survival time were recorded. The pup lungs were analyzed for phospholipid levels, surfactant protein A-D mRNA and the expression of the vitamin D receptor (VDR). S-25(OH)D was significantly lower in the VDL group at cesarean section (12 vs. 30nmol/L, p<0.0001). Compared to the controls, E19 VDL pups had lower birth weight (2.13 vs. 2.29g, p<0.001), lung weight (0.09 vs. 0.10g, p = 0.002), SaO2 (54% vs. 69%, p = 0.002) as well as reduced survival time (0.50 vs. 1.25h, p<0.0001). At E22, the VDL-induced pulmonary differences were leveled out, but VDL pups had lower CRL (4.0 vs. 4.5cm, p<0.0001). The phospholipid levels and the surfactant protein mRNA expression did not differ between the dietary groups. In conclusion, Vitamin D depletion led to lower oxygenation and reduced survival time in the preterm offspring, associated with reduced lung weight and birth weight. Further studies of vitamin D depletion in respiratory insufficiency in preterm neonates are warranted. PMID:27571350

  14. Influence of application sequence and timing of eugenol and lauric arginate (LAE) on survival of spoilage organisms.

    PubMed

    Manrique, Yudith; Gibis, Monika; Schmidt, Herbert; Weiss, Jochen

    2017-06-01

    The effectiveness of sequential applications of the antimicrobials eugenol and lauric arginate (LAE) was investigated against Staphylococcus carnosus, Listeria innocua, Escherichia coli K12, and Pseudomonas fluorescens. The antimicrobials were applied simultaneously at half of their minimum lethal concentrations (MLC) or sequentially at t = 0 h and t = 3, 4, 6 or 8 h. Bacterial survival was determined by direct plate counts. Survivals kinetic were fitted to a growth and mortality model to obtain characteristic parameters that described time-dependent changes from growth to mortality or vice versa. The most effective was a simultaneous exposure of both antimicrobials to the spoilage organisms at the beginning of the incubation period. Efficiency decreases depending on order and timing of the two antimicrobials were observed upon sequential treatments. These were most effective when antimicrobials where applied within a short time period (3-4 h) and when eugenol was first applied against S. carnosus and P. fluorescens. No sequence effects were observed for L. innocua, and sequential treatments proved to be ineffective against E. coli K12. These results were attributed to cells adapting to the first applied antimicrobial. In some cases, this provided protection against the second antimicrobial rendering the overall treatment less effective.

  15. 3D Deep Learning for Multi-modal Imaging-Guided Survival Time Prediction of Brain Tumor Patients

    PubMed Central

    Nie, Dong; Zhang, Han; Adeli, Ehsan; Liu, Luyan

    2016-01-01

    High-grade glioma is the most aggressive and severe brain tumor that leads to death of almost 50% patients in 1–2 years. Thus, accurate prognosis for glioma patients would provide essential guidelines for their treatment planning. Conventional survival prediction generally utilizes clinical information and limited handcrafted features from magnetic resonance images (MRI), which is often time consuming, laborious and subjective. In this paper, we propose using deep learning frameworks to automatically extract features from multi-modal preoperative brain images (i.e., T1 MRI, fMRI and DTI) of high-grade glioma patients. Specifically, we adopt 3D convolutional neural networks (CNNs) and also propose a new network architecture for using multi-channel data and learning supervised features. Along with the pivotal clinical features, we finally train a support vector machine to predict if the patient has a long or short overall survival (OS) time. Experimental results demonstrate that our methods can achieve an accuracy as high as 89.9% We also find that the learned features from fMRI and DTI play more important roles in accurately predicting the OS time, which provides valuable insights into functional neuro-oncological applications. PMID:28149967

  16. 3D Deep Learning for Multi-modal Imaging-Guided Survival Time Prediction of Brain Tumor Patients.

    PubMed

    Nie, Dong; Zhang, Han; Adeli, Ehsan; Liu, Luyan; Shen, Dinggang

    2016-10-01

    High-grade glioma is the most aggressive and severe brain tumor that leads to death of almost 50% patients in 1-2 years. Thus, accurate prognosis for glioma patients would provide essential guidelines for their treatment planning. Conventional survival prediction generally utilizes clinical information and limited handcrafted features from magnetic resonance images (MRI), which is often time consuming, laborious and subjective. In this paper, we propose using deep learning frameworks to automatically extract features from multi-modal preoperative brain images (i.e., T1 MRI, fMRI and DTI) of high-grade glioma patients. Specifically, we adopt 3D convolutional neural networks (CNNs) and also propose a new network architecture for using multi-channel data and learning supervised features. Along with the pivotal clinical features, we finally train a support vector machine to predict if the patient has a long or short overall survival (OS) time. Experimental results demonstrate that our methods can achieve an accuracy as high as 89.9% We also find that the learned features from fMRI and DTI play more important roles in accurately predicting the OS time, which provides valuable insights into functional neuro-oncological applications.

  17. Perioperative blood transfusion is not associated with overall survival or time to recurrence after resection of perihilar cholangiocarcinoma

    PubMed Central

    Dekker, Annemiek M.; Wiggers, Jimme K.; Coelen, Robert J.; van Golen, Rowan F.; Besselink, Marc G.H.; Busch, Olivier R.C.; Verheij, Joanne; Hollmann, Markus W.; van Gulik, Thomas M.

    2016-01-01

    Background Perioperative blood transfusions have been associated with worse oncological outcome in several types of cancer. The objective of this study was to assess the effect of perioperative blood transfusions on time to recurrence and overall survival (OS) in patients who underwent curative-intent resection of perihilar cholangiocarcinoma (PHC). Methods This retrospective cohort study included consecutive patients with resected PHC between 1992 and 2013 in a specialized center. Patients with 90-day mortality after surgery were excluded. Patients who did and did not receive perioperative blood transfusions were compared using univariable Kaplan–Meier analysis and multivariable Cox regression. Results Of 145 included patients, 80 (55.2%) received perioperative blood transfusions. The median OS was 49 months for patients without and 41 months for patients with blood transfusions (P = 0.46). In risk-adjusted multivariable Cox regression analysis, blood transfusion was not associated with OS (HR 1.00, 95% CI 0.59–1.68, P = 0.99) or time to recurrence (HR 1.00, 95% CI 0.57–1.78, P = 0.99). In addition, no differences in effect were found between different types of blood products transfused. Conclusion Blood transfusion was not associated with survival or time to recurrence after curative resection of PHC in this series. The alleged association is presumably related to the circumstances necessitating blood transfusions. PMID:27017166

  18. Software qualification of selected TOUGH2 modules

    SciTech Connect

    Wu, Y.S.; Ahlers, C.F.; Fraser, P.; Simmons, A.; Pruess, K.

    1996-10-01

    The purpose of this package of reports is to provide all software baseline documents necessary for the software qualification of the single-phase Gas (EOS1G), Effective Continuum Method (ECM), Saturated/Unsaturated Flow (EOS9), and Radionuclide Transport (T2R3D) modules of TOUGH2, a numerical simulation code for multi-dimensional coupled fluid and heat flow of multiphase, multicomponent fluid mixtures in porous and fractured media. This report contains the following sections: (1) Requirements Specification, (2) Design Description, (3) Software Validation Test Plan and Report, (4) Software User Documentation, and (5) Appendices. These sections comprise sequential parts of the Software Life Cycle, and are not intended to stand alone but should be used in conjunction with the TOUGH User`s Guide (Pruess, 1987), TOUGH2--A General Purpose Numerical Simulator for Multiphase Fluid and Heat Flow (Pruess, 1991), and the above-referenced TOUGH2 software qualification document. The qualification package is complete with the attached Software Identification Form and executable source code for the single-phase Gas, Effective Continuum method, Saturated/Unsaturated Flow, and Radionuclide Transport modules of TOUGH2.

  19. THE RELATIONSHIP BETWEEN MENTAL TOUGHNESS, STRESS, AND BURNOUT AMONG ADOLESCENTS: A LONGITUDINAL STUDY WITH SWISS VOCATIONAL STUDENTS (.).

    PubMed

    Gerber, Markus; Feldmeth, Anne Karina; Lang, Christin; Brand, Serge; Elliot, Catherine; Holsboer-Trachsler, Edith; Pühse, Uwe

    2015-12-01

    Past research has shown that higher stress is associated with increased burnout symptoms. The purpose of this study was to test whether mental toughness protects against symptoms of burnout and whether mental toughness moderates the relationship between perceived stress and burnout over time. Fifty-four vocational students (M age = 18.1 yr., SD = 1.2; 27 males, 27 females) completed self-report questionnaires twice, 10 mo. apart. Perceived stress, mental toughness, and burnout were measured using the Adolescent Stress Questionnaire (ASQ), the Mental Toughness Questionnaire (MTQ), and the Shirom-Melamed Burnout Measure (SMBM). Students who perceived higher stress and lower mental toughness scores reported higher burnout symptoms. Although no significant interaction effects were found between stress and mental toughness in the prediction of burnout, the graphical inspection of the interactions indicated that among students with high stress, those with high mental toughness remained below the cutoff for mild burnout, whereas an increase in burnout symptoms was observable among peers with low mental toughness.

  20. Design of stiff, tough and stretchy hydrogel composites via nanoscale hybrid crosslinking and macroscale fiber reinforcement.

    PubMed

    Lin, Shaoting; Cao, Changyong; Wang, Qiming; Gonzalez, Mark; Dolbow, John E; Zhao, Xuanhe

    2014-10-14

    Hydrogels' applications are usually limited by their weak mechanical properties. Despite recent great progress in developing tough hydrogels, it is still challenging to achieve high values of , toughness and modulus all together in synthetic hydrogels. In this paper, we designed highly stretchable, tough, yet stiff hydrogel composites via a combination of nanoscale hybrid crosslinking and macroscale fiber reinforcement. The hydrogel composites were constructed by impregnating a 3D-printed thermoplastic-fiber mesh with a tough hydrogel crosslinked both covalently and ionically. The hydrogel composites can achieve a fracture energy of over 30,000 J m(-2), a modulus of over 6 MPa, and can be stretched over 2.8 times even in the presence of large structural defects. The enhancement of toughness in the new hydrogel composites relies on multiple pairs of toughening mechanisms which span over multiple length scales. A theoretical model is further developed to predict the toughness and modulus of the hydrogel composites and guide the design of future materials.

  1. Survival time analysis of least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis) in acute exposures to endosulfan sulfate.

    PubMed

    Carriger, John F; Hoang, Tham C; Rand, Gary M

    2010-05-01

    Single-species flow-through toxicity tests were conducted to determine the times-to-death of two indigenous fish to South Florida--least killifish (Heterandria formosa) and mosquitofish (Gambusia affinis)--from acute exposure to endosulfan sulfate. Mortalities were recorded within 8-h periods from test initiation to termination at 96 h. The 96-h LC(50)s for least killifish and mosquitofish estimated using the trimmed-Spearman-Karber method were 2.0 and 2.3 microg/l, respectively. An accelerated failure time model was used to estimate times to death at selected concentrations. Data were fit to log-normal, log-logistic, and Weibull distributions. Acute toxicity data fit to the Weibull distribution produced a better relative fit than log-normal or log-logistic distributions for both toxicity tests. The survival-time profiles and associated statistics illustrate the benefit of considering exposure duration as well as concentration when predicting acute risk to species' populations. Both toxicity tests had similar outcomes from exposure to endosulfan sulfate, with least killifish being slightly more likely to die at lower concentrations and shorter time periods than mosquitofish. From the models generated by the toxicity tests, times-to-death for least killifish and mosquitofish were estimated for environmentally relevant concentrations of total endosulfan at a site of concern in South Florida. When the results from the current toxicity tests were compared to environmental concentrations from previous screening-level ecological risk assessments, the durations necessary to potentially kill 10% or more of the populations of the two native south Florida fish species were estimated to be 77 and 96 h for least killifish and mosquitofish, respectively. However, the exposure values included the alpha and beta isomers as well as endosulfan sulfate; therefore, an understanding of their toxicity might be important in understanding the survival dynamics of fish species in

  2. Estimation of total genetic effects for survival time in crossbred laying hens showing cannibalism, using pedigree or genomic information.

    PubMed

    Brinker, T; Raymond, B; Bijma, P; Vereijken, A; Ellen, E D

    2017-02-01

    Mortality of laying hens due to cannibalism is a major problem in the egg-laying industry. Survival depends on two genetic effects: the direct genetic effect of the individual itself (DGE) and the indirect genetic effects of its group mates (IGE). For hens housed in sire-family groups, DGE and IGE cannot be estimated using pedigree information, but the combined effect of DGE and IGE is estimated in the total breeding value (TBV). Genomic information provides information on actual genetic relationships between individuals and might be a tool to improve TBV accuracy. We investigated whether genomic information of the sire increased TBV accuracy compared with pedigree information, and we estimated genetic parameters for survival time. A sire model with pedigree information (BLUP) and a sire model with genomic information (ssGBLUP) were used. We used survival time records of 7290 crossbred offspring with intact beaks from four crosses. Cross-validation was used to compare the models. Using ssGBLUP did not improve TBV accuracy compared with BLUP which is probably due to the limited number of sires available per cross (~50). Genetic parameter estimates were similar for BLUP and ssGBLUP. For both BLUP and ssGBLUP, total heritable variance (T(2) ), expressed as a proportion of phenotypic variance, ranged from 0.03 ± 0.04 to 0.25 ± 0.09. Further research is needed on breeding value estimation for socially affected traits measured on individuals kept in single-family groups.

  3. Expectation-maximization algorithms for learning a finite mixture of univariate survival time distributions from partially specified class values

    SciTech Connect

    Lee, Youngrok

    2013-05-15

    Heterogeneity exists on a data set when samples from di erent classes are merged into the data set. Finite mixture models can be used to represent a survival time distribution on heterogeneous patient group by the proportions of each class and by the survival time distribution within each class as well. The heterogeneous data set cannot be explicitly decomposed to homogeneous subgroups unless all the samples are precisely labeled by their origin classes; such impossibility of decomposition is a barrier to overcome for estimating nite mixture models. The expectation-maximization (EM) algorithm has been used to obtain maximum likelihood estimates of nite mixture models by soft-decomposition of heterogeneous samples without labels for a subset or the entire set of data. In medical surveillance databases we can find partially labeled data, that is, while not completely unlabeled there is only imprecise information about class values. In this study we propose new EM algorithms that take advantages of using such partial labels, and thus incorporate more information than traditional EM algorithms. We particularly propose four variants of the EM algorithm named EM-OCML, EM-PCML, EM-HCML and EM-CPCML, each of which assumes a specific mechanism of missing class values. We conducted a simulation study on exponential survival trees with five classes and showed that the advantages of incorporating substantial amount of partially labeled data can be highly signi cant. We also showed model selection based on AIC values fairly works to select the best proposed algorithm on each specific data set. A case study on a real-world data set of gastric cancer provided by Surveillance, Epidemiology and End Results (SEER) program showed a superiority of EM-CPCML to not only the other proposed EM algorithms but also conventional supervised, unsupervised and semi-supervised learning algorithms.

  4. Assessment of chronic effects of tebuconazole on survival, reproduction and growth of Daphnia magna after different exposure times.

    PubMed

    Sancho, E; Villarroel, M J; Ferrando, M D

    2016-02-01

    The effect of the fungicide tebuconazole (0.41, 0.52, 0.71 and 1.14mg/L) on survival, reproduction and growth of Daphnia magna organisms was monitored using 14 and 21 days exposure tests. A third experiment was performed by exposing D. magna to the fungicide for 14 days followed by 7 days of recovery (14+7). In order to test fungicide effects on D. magna, parameters as survival, mean whole body length, mean total number of neonates per female, mean number of broods per female, mean brood size per female, time to first brood/reproduction and intrinsic rate of natural increase (r) were used. Reproduction was seriously affected by tebuconazole. All tebuconazole concentrations tested affected the number of broods per female and day to first brood. At 14-days test, number of neonates per female and body size decreased by concentrations of tebuconazole higher than 0.52mg/L, whereas at 21-days test both parameters were affected at all the concentrations tested. Survival of the daphnids after 14 days fungicide exposure did not exhibited differences among experimental and control groups. In this experiment r value was reduced (in a 22%) when animals were exposed to concentrations of 0.71mg/L and 1.14mg/L. Survival of daphnids exposed during 21 days to 1.14mg/L declined, and the intrinsic rate of natural increase (r) decreased in a 30 % for tebuconazole concentrations higher than 0.41mg/L. Longevity of daphnids pre-exposed to tebuconazole for 14 days and 7 days in clean water did not show differences from control values and all of them survived the 21 days of the test. However, after 7 days in fungicide free medium animals were unable to restore control values for reproductive parameters and length. The maximum acceptable toxicant concentration (MATC) was calculated using the r values as parameter of evaluation. MATC estimations were 0.61mg/L and 0.46mg/L for 14 and 21 days, respectively. Results showed that the number of neonates per female was the highest sensitive

  5. TOUGH2 User's Guide Version 2

    SciTech Connect

    Pruess, K.; Oldenburg, C.M.; Moridis, G.J.

    1999-11-01

    TOUGH2 is a numerical simulator for nonisothermal flows of multicomponent, multiphase fluids in one, two, and three-dimensional porous and fractured media. The chief applications for which TOUGH2 is designed are in geothermal reservoir engineering, nuclear waste disposal, environmental assessment and remediation, and unsaturated and saturated zone hydrology. TOUGH2 was first released to the public in 1991; the 1991 code was updated in 1994 when a set of preconditioned conjugate gradient solvers was added to allow a more efficient solution of large problems. The current Version 2.0 features several new fluid property modules and offers enhanced process modeling capabilities, such as coupled reservoir-wellbore flow, precipitation and dissolution effects, and multiphase diffusion. Numerous improvements in previously released modules have been made and new user features have been added, such as enhanced linear equation solvers, and writing of graphics files. The T2VOC module for three-phase flows of water, air and a volatile organic chemical (VOC), and the T2DM module for hydrodynamic dispersion in 2-D flow systems have been integrated into the overall structure of the code and are included in the Version 2.0 package. Data inputs are upwardly compatible with the previous version. Coding changes were generally kept to a minimum, and were only made as needed to achieve the additional functionalities desired. TOUGH2 is written in standard FORTRAN77 and can be run on any platform, such as workstations, PCs, Macintosh, mainframe and supercomputers, for which appropriate FORTRAN compilers are available. This report is a self-contained guide to application of TOUGH2 to subsurface flow problems. It gives a technical description of the TOUGH2 code, including a discussion of the physical processes modeled, and the mathematical and numerical methods used. Illustrative sample problems are presented along with detailed instructions for preparing input data.

  6. Modified 43XX Steels for High Toughness

    DTIC Science & Technology

    1980-04-01

    AL AMMRC TR 80-20 MODIFIED 43XX STEELS FOR HIGH TOUGHNESS T CS.,•, °x ,•, o o,,o,,,sD T I W4 AftELECTE APRIL 1980 J N.J. Kar, V.F. Zackay and E.R...carried out. Isohra tasomions in these steels resulted inn bbaainni 11-v DI FOR Z 47 RITIOW OF I NOV695 IS OBSOLETE UCASFE SECURITY UCLASSIFIEDINOFTI PAGE...this investigation for Si-modified AISI 4330 steel appear to be superior to those for unmodified AISI 4340 and 300-M steels , whilst the strength-tough

  7. Increasing the Cryogenic Toughness of Steels

    NASA Technical Reports Server (NTRS)

    Rush, H. F.

    1986-01-01

    Grain-refining heat treatments increase toughness without substantial strength loss. Five alloys selected for study, all at or near technological limit. Results showed clearly grain sizes of these alloys refined by such heat treatments and grain refinement results in large improvement in toughness without substantial loss in strength. Best improvements seen in HP-9-4-20 Steel, at low-strength end of technological limit, and in Maraging 200, at high-strength end. These alloys, in grain refined condition, considered for model applications in high-Reynolds-number cryogenic wind tunnels.

  8. Fracture Toughness Prediction for MWCNT Reinforced Ceramics

    SciTech Connect

    Henager, Charles H.; Nguyen, Ba Nghiep

    2013-09-01

    This report describes the development of a micromechanics model to predict fracture toughness of multiwall carbon nanotube (MWCNT) reinforced ceramic composites to guide future experimental work for this project. The modeling work described in this report includes (i) prediction of elastic properties, (ii) development of a mechanistic damage model accounting for matrix cracking to predict the composite nonlinear stress/strain response to tensile loading to failure, and (iii) application of this damage model in a modified boundary layer (MBL) analysis using ABAQUS to predict fracture toughness and crack resistance behavior (R-curves) for ceramic materials containing MWCNTs at various volume fractions.

  9. Heat loss and hypothermia in free diving: Estimation of survival time under water

    NASA Astrophysics Data System (ADS)

    Aguilella-Arzo, Marcel; Alcaraz, Antonio; Aguilella, Vicente M.

    2003-04-01

    The heat exchange between a diver and the colder surrounding water is analyzed on the basis of the fundamental equations of thermal transport. To estimate the decrease in the diver's body temperature as a function of time, we discuss the complex interplay of several factors including the body heat production rate, the role of the diver's wet suit, and the way different heat exchange mechanisms (conduction, convection, and radiation) contribute to thermal transport. This knowledge could be useful to prevent physiological disorders that occur when the human body temperature drops below 35 °C.

  10. The health care market: can hospitals survive?

    PubMed

    Goldsmith, J C

    1980-01-01

    Does it sound familiar? Resources are scarce, competition is tough, and government regulations and a balanced budget are increasingly hard to meet at the same time. This is not the automobile or oil industry but the health care industry, and hospital managers are facing the same problems. And, maintains the author of this article, they must borrow some proven marketing techniques from business to survive in the new health care market. He first describes the features of the new market (the increasing economic power of physicians, new forms of health care delivery, prepaid health plans, and the changing regulatory environment) and then the possible marketing strategies for dealing with them (competing hard for physicians who control the patient flow and diversifying and promoting the mix of services). He also describes various planning solutions that make the most of a community's hospital facilities and affiliations.

  11. Effect of Migration Pathway on Travel Time and Survival of Acoustic-Tagged Juvenile Salmonids in the Columbia River Estuary

    SciTech Connect

    Harnish, Ryan A.; Johnson, Gary E.; McMichael, Geoffrey A.; Hughes, Michael S.; Ebberts, Blaine D.

    2012-02-01

    Off-channel areas (side channels, tidal flats, sand bars, and shallow-water bays) may serve as important migration corridors through estuarine environments for salmon and steelhead smolts. Relatively large percentages (21-33%) of acoustic-tagged yearling and subyearling Chinook salmon and steelhead smolts were detected migrating through off-channel areas of the Columbia River estuary in 2008. The probability of survival for off-channel migrants (0.78-0.94) was similar to or greater than the survival probability of main channel migrants (0.67-0.93). Median travel times were similar for all species or run types and migration pathways we examined, ranging from 1-2 d. The route used by smolts to migrate through the estuary may affect their vulnerability to predation. Acoustic-tagged steelhead that migrated nearest to avian predator nesting colonies experienced higher predation rates (24%) than those that migrated farthest from the colonies (10%). The use of multiple migration pathways may be advantageous to out-migrating smolts because it helps to buffer against high rates of mortality, which may occur in localized areas, and helps to minimize inter- and intraspecific competition.

  12. Nonparametric inference for the joint distribution of recurrent marked variables and recurrent survival time.

    PubMed

    Yee, Laura M; Chan, Kwun Chuen Gary

    2017-04-01

    Time between recurrent medical events may be correlated with the cost incurred at each event. As a result, it may be of interest to describe the relationship between recurrent events and recurrent medical costs by estimating a joint distribution. In this paper, we propose a nonparametric estimator for the joint distribution of recurrent events and recurrent medical costs in right-censored data. We also derive the asymptotic variance of our estimator, a test for equality of recurrent marker distributions, and present simulation studies to demonstrate the performance of our point and variance estimators. Our estimator is shown to perform well for a wide range of levels of correlation, demonstrating that our estimators can be employed in a variety of situations when the correlation structure may be unknown in advance. We apply our methods to hospitalization events and their corresponding costs in the second Multicenter Automatic Defibrillator Implantation Trial (MADIT-II), which was a randomized clinical trial studying the effect of implantable cardioverter-defibrillators in preventing ventricular arrhythmia.

  13. 33 CFR 150.503 - What are the time interval requirements for maintenance on survival craft falls?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... requirements for maintenance on survival craft falls? 150.503 Section 150.503 Navigation and Navigable Waters... maintenance on survival craft falls? (a) Each fall used in a launching device for survival craft or rescue boats must be turned end-for-end at intervals of not more than 30 months. (b) Each fall must be...

  14. Racial Disparities in Colorectal Carcinoma Incidence, Severity and Survival Times Over 10 Years: A Retrospective Single Center Study

    PubMed Central

    Arshad, Hafiz Muhammad Sharjeel; Tetangco, Eula; Shah, Natasha; Kabir, Christopher; Raddawi, Hareth

    2016-01-01

    Background Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in the United States. Although studies have been performed on malignancy behavior in African Americans and Caucasians, scant data are present on other minority racial groups. Methods A retrospective single center study was performed where 1,860 patient charts with a diagnosis of CRC from January 1, 2004 to December 31, 2014 were reviewed. Data collected on each patient included age, gender, ethnicity, primary site and histological stage at the time of diagnosis. Survival time over the course of 5 years was documented for patients from January 1, 2004 to December 31, 2009. Comparisons were made amongst different racial groups for the above mentioned factors. Results Study population consisted of 27.09% African Americans, 65.61% Caucasians, 3.86% Hispanics, 0.54% South Asians, 1.03% Arabs, 0.54% Asians and 0.22% American Indians. Mean age of CRC presentation was found to be significantly different (P < 0.05) between the three largest racial groups: 71 years for Caucasians, 69 years for African Americans, and 61 years for Hispanics. African Americans (27.09%) and Hispanics (28.79%) presented predominantly at stage IV in comparison to other racial groups. Caucasians presented predominantly at stage III (24.84%). The rectum was the most common site of CRC across all racial groups with the exception of Asians, where sigmoid colon was the predominant site (30%). Adenocarcinoma remained the predominant cancer type in all groups. Hispanics had relatively higher incidence rate of carcinoid tumor (12.68%). Survival time analysis showed that Caucasians tend to have better survival probability over 5 years after initial diagnosis as compared to African Americans and Hispanic (P < 0.05). Conclusion There is lack of studies performed on minority racial groups in North America. Our study highlighted some important clinical differences of CRC presentation in different racial groups which are not

  15. The forecast of the postoperative survival time of patients suffered from non-small cell lung cancer based on PCA and extreme learning machine.

    PubMed

    Han, Fei; Huang, De-Shuang; Zhu, Zhi-Hua; Rong, Tie-Hua

    2006-02-01

    In this paper, a new effective model is proposed to forecast how long the postoperative patients suffered from non-small cell lung cancer will survive. The new effective model which is based on the extreme learning machine (ELM) and principal component analysis (PCA) can forecast successfully the postoperative patients' survival time. The new model obtains better prediction accuracy and faster convergence rate which the model using backpropagation (BP) algorithm and the Levenberg-Marquardt (LM) algorithm to forecast the postoperative patients' survival time can not achieve. Finally, simulation results are given to verify the efficiency and effectiveness of our proposed new model.

  16. Survival analysis of timing of first marriage among women of reproductive age in Nigeria: regional differences.

    PubMed

    Adebowale, Stephen A; Fagbamigbe, Francis A; Okareh, Titus O; Lawal, Ganiyu O

    2012-12-01

    Early marriage is common among women in developing countries. Age at first marriage (AFM) has health implication on women and their under-five children. In Nigeria, few studies have explored AFM; the current study was designed to fill the gap. Nigeria Demographic and Health Survey, 2008 dataset on married women aged 15-49 (N = 24,986) was used. Chi-square, OLS regression and Cox proportional hazard models were used in the analysis. The mean AFM was 17.8 +/- 4.8 years and significant difference existed between the mean AFM of women in the North (16.0 +/- 3.6) and South (20.4 +/- 5.0) (p < 0.001). Region, education, religion, residence, nutritional status, age at first sexual intercourse and children ever born were significantly associated with timing of first marriage (p < 0.001). Majority of the women married between ages 15-19 years (43.1%), while very few married late (2.3%) and about 27.0% married too early (less than 15 years). Early marriage was more common in all the regions in the North than the South and the hazard was highest in the North West and North East. Women who reside in rural area (H.R = 1.15; C.I = 1.11-1.18) married early than their counterparts in the urban area. Age at first marriage was directly related to levels of education (p < 0.001). Muslim women married early (H.R = 1.34; C.I = 1.29-1.39) than Christians. Three models were generated from the data. Women married too early in Nigeria with Teenage marriage more common in the North than the South. Education has influence on AFM; therefore, women should have at least secondary education before marriage in Nigeria.

  17. Proceedings of the TOUGH Symposium 2009

    SciTech Connect

    Moridis, George J.; Doughty, Christine; Finsterle, Stefan; Sonnenthal, Eric

    2009-10-01

    Welcome to the TOUGH Symposium 2009. Within this volume are the Symposium Program for eighty-nine papers to be presented in both oral and poster formats. The full papers are available as pdfs linked from the Symposium Program posted on the TOUGH Symposium 2009 website http://esd.lbl.gov/newsandevents/events/toughsymposium09/program.html Additional updated information including any changes to the Program will also be available at the website. The papers cover a wide range of application areas and reflect the continuing trend toward increased sophistication of the TOUGH codes. A CD containing the proceedings papers will be published immediately following the Symposium and sent to all participants. As in the prior Symposium, selected papers will be invited for submission to a number of journals for inclusion in Special Issues focused on applications and developments of the TOUGH codes. These journals include, Transport in Porous Media, Geothermics, Energy Conversion and Management, Journal of Nuclear Science and Technology, and the Vadose Zone Journal.

  18. TOUGH3 v1.0

    SciTech Connect

    PAU, GEORGE; JUNG, YOOJIN; FINSTERLE, STEFAN; ZHANG, YINGQI

    2016-09-14

    TOUGH3 V1.0 capabilities to simulate multi-dimensional, multi-phase, multi-component, non-isothermal flow and transport in fractured porous media, with applications geosciences and reservoir engineering and other application areas. TOUGH3 V1.0 supports a number of different combinations of fluids and components (updated equation-of-state (EOS) modules from previous versions of TOUGH, including EOS1, EOS2, EOS3, EOS4, EOS5, EOS7, EOS7R, EOS7C, EOS7CA, EOS8, EOS9, EWASG, TMVOC, ECO2N, and ECO2M). This upgrade includes (a) expanded list of updated equation-of-state (EOS) modules, (b) new hysteresis models, (c) new implementation of parallel and solver functionalities, (d) new linear solver options based on PETSc libraries, (e) new automatic build system that automatically downloads and builds third-party libraries and TOUGH3, (f) new printout in CSV format, (g) dynamic memory allocation, (h) various user features, and (i) bug fixes.

  19. Tough Ceramic Mimics Mother of Pearl

    ScienceCinema

    Ritchie, Robert

    2016-07-12

    Berkeley Lab scientists have mimicked the structure of mother of pearl to create what may well be the toughest ceramic ever produced. http://newscenter.lbl.gov/press-releases/2008/12/05/scientists-create-tough-ceramic-that-mimics-mother-of-pearl/

  20. Laboratory Powder Metallurgy Makes Tough Aluminum Sheet

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Thomas, J. R.; Singleton, O. R.

    1993-01-01

    Aluminum alloy sheet exhibits high tensile and Kahn tear strengths. Rapid solidification of aluminum alloys in powder form and subsequent consolidation and fabrication processes used to tailor parts made of these alloys to satisfy such specific aerospace design requirements as high strength and toughness.

  1. Veins improve fracture toughness of insect wings.

    PubMed

    Dirks, Jan-Henning; Taylor, David

    2012-01-01

    During the lifetime of a flying insect, its wings are subjected to mechanical forces and deformations for millions of cycles. Defects in the micrometre thin membranes or veins may reduce the insect's flight performance. How do insects prevent crack related material failure in their wings and what role does the characteristic vein pattern play? Fracture toughness is a parameter, which characterises a material's resistance to crack propagation. Our results show that, compared to other body parts, the hind wing membrane of the migratory locust S. gregaria itself is not exceptionally tough (1.04±0.25 MPa√m). However, the cross veins increase the wing's toughness by 50% by acting as barriers to crack propagation. Using fracture mechanics, we show that the morphological spacing of most wing veins matches the critical crack length of the material (1132 µm). This finding directly demonstrates how the biomechanical properties and the morphology of locust wings are functionally correlated in locusts, providing a mechanically 'optimal' solution with high toughness and low weight. The vein pattern found in insect wings thus might inspire the design of more durable and lightweight artificial 'venous' wings for micro-air-vehicles. Using the vein spacing as indicator, our approach might also provide a basis to estimate the wing properties of endangered or extinct insect species.

  2. Animacy and the Acquisition of "Tough" Adjectives

    ERIC Educational Resources Information Center

    Becker, Misha

    2015-01-01

    This article reports on two novel word-learning experiments examining children's use of subject animacy to categorize novel adjectives as either "tough" adjectives (e.g., "easy," "hard") or control adjectives ("afraid," "eager"). In Experiment 1, a group of 4- to 7-year-olds watched videos…

  3. Fracture toughness testing of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.

    1992-01-01

    The experimental techniques and associated data analysis methods used to measure the resistance to interlaminar fracture, or 'fracture toughness', of polymer matrix composite materials are described. A review in the use of energy techniques to characterize fracture behavior in elastic solids is given. An overview is presented of the types of approaches employed in the design of delamination-resistant composite materials.

  4. Tough Ceramic Mimics Mother of Pearl

    SciTech Connect

    Ritchie, Robert

    2009-01-01

    Berkeley Lab scientists have mimicked the structure of mother of pearl to create what may well be the toughest ceramic ever produced. http://newscenter.lbl.gov/press-releases/2008/12/05/scientists-create-tough-ceramic-that-mimics-mother-of-pearl/

  5. 46 CFR 154.605 - Toughness test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Toughness test. 154.605 Section 154.605 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Materials §...

  6. Mechanical Behavior of Tough Hydrogels for Structural Applications

    NASA Astrophysics Data System (ADS)

    Illeperuma, Widusha Ruwangi Kaushalya

    Hydrogels are widely used in many commercial products including Jell-O, contact lenses, and superabsorbent diapers. In recent decades, hydrogels have been under intense development for biomedical applications, such as scaffolds in tissue engineering, carriers for drug delivery, and valves in microfluidic systems. But the scope is severely limited as conventional hydrogels are weak and brittle and are not very stretchable. This thesis investigates the approaches that enhance the mechanical properties of hydrogels and their structural applications. We discov¬ered a class of exceptionally stretchable and tough hydrogels made from poly-mers that form networks via ionic and covalent crosslinks. Although such a hydrogel contains ~90% water, it can be stretched beyond 20 times its initial length, and has a fracture energy of ~9000 J/m2. The combination of large stretchability, remarkable toughness, and recoverability of stiffness and toughness, along with easy synthesis makes this material much superior over existing hydrogels. Extreme stretchability and blunted crack tips of these hydrogels question the validity of traditional fracture testing methods. We re-examine a widely used pure shear test method to measure the fracture energy. With the experimental and simulation results, we conclude that the pure shear test method can be used to measure fracture energy of extremely stretchable materials. Even though polyacrylamide-alginate hydrogels have an extremely high toughness, it has a relatively low stiffness and strength. We improved the stiffness and strength by embedding fibers. Most hydrogels are brittle, allowing the fibers to cut through the hydrogel when the composite is loaded. But tough hydrogel composites do not fail by the fibers cutting the hydrogel; instead, it undergoes large deforming by fibers sliding through the matrix. Hydrogels were not considered as materials for structural applications. But with enhanced mechanical properties, they have opened up

  7. A new proposal for multivariable modelling of time-varying effects in survival data based on fractional polynomial time-transformation.

    PubMed

    Sauerbrei, Willi; Royston, Patrick; Look, Maxime

    2007-06-01

    The Cox proportional hazards model has become the standard for the analysis of survival time data in cancer and other chronic diseases. In most studies, proportional hazards (PH) are assumed for covariate effects. With long-term follow-up, the PH assumption may be violated, leading to poor model fit. To accommodate non-PH effects, we introduce a new procedure, MFPT, an extension of the multivariable fractional polynomial (MFP) approach, to do the following: (1) select influential variables; (2) determine a sensible dose-response function for continuous variables; (3) investigate time-varying effects; (4) model such time-varying effects on a continuous scale. Assuming PH initially, we start with a detailed model-building step, including a search for possible non-linear functions for continuous covariates. Sometimes a variable with a strong short-term effect may appear weak or non-influential if 'averaged' over time under the PH assumption. To protect against omitting such variables, we repeat the analysis over a restricted time-interval. Any additional prognostic variables identified by this second analysis are added to create our final time-fixed multivariable model. Using a forward-selection algorithm we search for possible improvements in fit by adding time-varying covariates. The first part to create a final time-fixed model does not require the use of MFP. A model may be given from 'outside' or a different strategy may be preferred for this part. This broadens the scope of the time-varying part. To motivate and illustrate the methodology, we create prognostic models from a large database of patients with primary breast cancer. Non-linear time-fixed effects are found for progesterone receptor status and number of positive lymph nodes. Highly statistically significant time-varying effects are present for progesterone receptor status and tumour size.

  8. Notch Fracture Toughness of Glasses: Dependence on Rate, Age, and Geometry

    NASA Astrophysics Data System (ADS)

    Vasoya, Manish; Rycroft, Chris H.; Bouchbinder, Eran

    2016-08-01

    Understanding the fracture toughness (resistance) of glasses is a fundamental problem of prime theoretical and practical importance. Here we theoretically study its dependence on the loading rate, the age (history) of the glass, and the notch radius ρ . Reduced-dimensionality analysis suggests that the notch fracture toughness results from a competition between the initial, age- and history-dependent, plastic relaxation time scale τ0pl and an effective loading time scale τext(K˙ I,ρ ) , where K˙ I is the tensile stress-intensity-factor rate. The toughness is predicted to scale with √{ρ } independently of ξ ≡τext/τ0pl for ξ ≪1 , to scale as T √{ρ }log (ξ ) for ξ ≫1 (related to thermal activation, where T is the temperature), and to feature a nonmonotonic behavior in the crossover region ξ ˜O (1 ) (related to plastic yielding dynamics). These predictions are verified using 2D computations, providing a unified picture of the notch fracture toughness of glasses. The theory highlights the importance of time-scale competition and far-from-steady-state elasto-viscoplastic dynamics for understanding the toughness and shows that the latter varies quite significantly with the glass age (history) and applied loading rate. Experimental support for bulk metallic glasses is presented, and possible implications for applications are discussed.

  9. Fracture toughness testing data: A technology survey and bibliography

    NASA Technical Reports Server (NTRS)

    Stuhrke, W. F.; Carpenter, J. L., Jr.; Moya, N.; Mandel, G.

    1975-01-01

    Announced survey includes reports covering fracture toughness testing for various structural materials including information on plane strain and developing areas of mixed mode and plane strain test conditions. Bibliography references cite work and conclusions in fracture toughness testing and application of fracture toughness test data, and in fracture mechanics analysis.

  10. The limit of strength and toughness of steel

    SciTech Connect

    Guo, Zhen

    2001-12-01

    The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the governing principles of strength and toughness, along with the approaches that can be used to improve these properties and the inherent limits to how strong and tough a steel can be.

  11. Fracture toughness of dental restorative materials.

    PubMed

    Ilie, Nicoleta; Hickel, Reinhard; Valceanu, Anca Silvia; Huth, Karin Christine

    2012-04-01

    The ability of a restorative material to withstand fracture is of crucial importance especially in stress-bearing area. Therefore, the study aims to analyse the fracture toughness of a large number of dental restorative materials categories. The fracture toughness (K(IC)) of 69 restorative materials belonging to ten materials categories-micro-hybrid, nanofilled, microfilled, packable, ormocer-based, and flowable resin-based composites (RBC), compomers and flowable compomers, as well as glass ionomer cements (GIC) and resin-modified GIC was measured by means of the single-edge notched-beam method after storing the samples (n = 8) for 24 h in distilled water. Data were analyzed with the one-way analysis of variance (ANOVA) followed by the Tukey's test and partial eta-squared statistics (p < 0.05). Large variations between the tested materials within a material category were found. The lowest fracture toughness was reached in the GIC group, followed by the microfilled RBCs, resin-modified GIC, and flowable compomers, which do not differ significantly among each other as a material group. The ormocer-based, packable, and micro-hybrid RBCs performed statistically similar, reaching the highest fracture toughness values. Between the two categories of flowables-composites and compomers-no differences were measured. The correlation between K(IC) and filler volume (0.34) and respective filler weight (0.40) was low. K(IC) increased with the volume fraction of fillers until a critical value of 57%, following with a plateau, with constant values until ca. 65% volume fraction. Above this value, K(IC) decreased slightly. Due to the very large variability of the fracture toughness within a material type, the selection of a suitable restorative material should have not been done with respect to a specific material category, especially in stress-bearing areas, but by considering the individual measured material properties.

  12. Impact of the model-building strategy on inference about nonlinear and time-dependent covariate effects in survival analysis.

    PubMed

    Wynant, Willy; Abrahamowicz, Michal

    2014-08-30

    Cox's proportional hazards (PH) model assumes constant-over-time covariate effects. Furthermore, most applications assume linear effects of continuous covariates on the logarithm of the hazard. Yet, many prognostic factors have time-dependent (TD) and/or nonlinear (NL) effects, that is, violate these conventional assumptions. Detection of such complex effects could affect prognosis and clinical decisions. However, assessing the effects of each of the multiple, often correlated, covariates in flexible multivariable analyses is challenging. In simulations, we investigated the impact of the approach used to build the flexible multivariable model on inference about the TD and NL covariate effects. Results demonstrate that the conclusions regarding the statistical significance of the TD/NL effects depend heavily on the strategy used to decide which effects of the other covariates should be adjusted for. Both a failure to adjust for true TD and NL effects of relevant covariates and inclusion of spurious effects of covariates that conform to the PH and linearity assumptions increase the risk of incorrect conclusions regarding other covariates. In this context, iterative backward elimination of nonsignificant NL and TD effects from the multivariable model, which initially includes all these effects, may help discriminate between true and spurious effects. The practical importance of these issues was illustrated in an example that reassessed the predictive ability of selected biomarkers for survival in advanced non-small-cell lung cancer. In conclusion, a careful model-building strategy and flexible modeling of multivariable survival data can yield new insights about predictors' roles and improve the validity of analyses.

  13. Polygenic Score × Intervention Moderation: an Application of Discrete-Time Survival Analysis to Model the Timing of First Marijuana Use Among Urban Youth.

    PubMed

    Musci, Rashelle J; Fairman, Brian; Masyn, Katherine E; Uhl, George; Maher, Brion; Sisto, Danielle Y; Kellam, Sheppard G; Ialongo, Nicholas S

    2016-11-05

    The present study examines the interaction between a polygenic score and an elementary school-based universal preventive intervention trial and its effects on a discrete-time survival analysis of time to first smoking marijuana. Research has suggested that initiation of substances is both genetically and environmentally driven (Rhee et al., Archives of general psychiatry 60:1256-1264, 2003; Verweij et al., Addiction 105:417-430, 2010). A previous work has found a significant interaction between the polygenic score and the same elementary school-based intervention with tobacco smoking (Musci et al., in press). The polygenic score reflects the contribution of multiple genes and has been shown in prior research to be predictive of smoking cessation, tobacco use, and marijuana use (Uhl et al., Molecular Psychiatry 19:50-54, 2014). Using data from a longitudinal preventive intervention study (N = 678), we examined age of first marijuana use from sixth grade to age 18. Genetic data were collected during emerging adulthood and were genotyped using the Affymetrix 6.0 microarray (N = 545). The polygenic score was computed using these data. Discrete-time survival analysis was employed to test for intervention main and interaction effects with the polygenic score. We found main effect of the polygenic score approaching significance, with the participants with higher polygenic scores reporting their first smoking marijuana at an age significantly later than controls (p = .050). We also found a significant intervention × polygenic score interaction effect at p = .003, with participants at the higher end of the polygenic score benefiting the most from the intervention in terms of delayed age of first use. These results suggest that genetics may play an important role in the age of first use of marijuana and that differences in genetics may account for the differential effectiveness of classroom-based interventions in delaying substance use experimentation.

  14. Gas pressure sintering of silicon nitride to optimize fracture toughness

    SciTech Connect

    Tiegs, T.N.; Nunn, S.D.; Beavers, T.M.; Menchhofer, P.A.; Barker, D.L.; Coffey, D.W.

    1995-06-01

    Gas-pressure sintering (GPS) can be used to densify silicon nitride containing a wide variety of sintering additives. Parameters affecting the sintering behavior include densification temperature, densification time, grain growth temperature, grain growth time and heating rates. The Si{sub 3}N{sub 4}-6% Y{sub 2}O{sub 3}-2% A1{sub 2}O{sub 3} samples sintered to high densities at all conditions used in the present study, whereas the Si{sub 3}N{sub 4}-Sr{sub 2}La{sub 4}Yb{sub 4}(SiO{sub 4}){sub 6}O{sub 2} samples required the highest temperatures and longest times to achieve densities {ge}98 % T. D. The main effect on the fracture toughness for Si{sub 3}N{sub 4}-6% Y{sub 2}O{sub 3}-2% A1{sub 2}O{sub 3} samples was the use of a lower densification temperature, which was 1900C in the present study. For the Si{sub 3}N{sub 4}-Sr{sub 2}La{sub 4}Yb{sub 4}SiO4{sub 4}){sub 6}O{sub 2} composition, fracture toughness was sensitive to and improved by a slower heating rate (10c/min), a lower densification temperature (1900`), a higher grain growth temperature (2000C), and a longer grain growth time (2 h).

  15. Dynamic Fracture Initiation Toughness of a Gamma (Met-PX) Titanium Aluminide at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Shazly, Mostafa; Prakash, Vikas; Draper, Susan

    2009-06-01

    Recently, a new generation of titanium aluminide alloy named Gamma-Met PX (GKSS, Geesthacht, Germany) has been developed with better rolling and postrolling characteristics. Previous work on this alloy has shown the material to have higher strengths at room and elevated temperatures when compared with other gamma titanium aluminides. In particular, this new alloy has shown increased ductility at elevated temperatures under both quasistatic and high-strain-rate uniaxial compressive loading. However, its high-strain-rate tensile ductility at room and elevated temperatures is limited to ~1 pct. In the present article, the results of a study investigating the effects of the loading rate and test temperature on the dynamic fracture initiation toughness in Gamma-Met PX are presented. A modified split Hopkinson pressure bar (MSHPB) was used along with high-speed photography, to determine the dynamic fracture initiation toughness. Three-point-bend fracture tests were conducted at impact speeds in the range 1 to 3.6 m/s and at test temperatures up to 1200 °C. Furthermore, the effect of long-time high-temperature air exposure on the fracture toughness was investigated. The results show that the dynamic fracture initiation toughness decreases at test temperatures beyond 600 °C. Moreover, the dynamic fracture initiation toughness was found to decrease with increasing exposure time. The reasons behind this drop are analyzed and discussed.

  16. Effect of weld thermal cycles on the HAZ toughness of SQV-2A pressure vessel steel

    SciTech Connect

    Matsuda, F.; Ikeuchi, K.; Liao, J.

    1996-12-31

    The toughness of coarse grained heat affected zone (CGHAZ) and intercritically reheated CGHAZ of SQV-2A pressure vessel steel has been investigated with particular attention to the behavior of M-A constituents. The effect of temper-bead thermal cycles on the toughness improvement in ICCGHAZs and temper-bead process. The occurrence of embrittlement in CGHAZs and ICCGHAZs was accompanied by the formation of the M-A constituent. Observations with a scanning electron microscope (SEM) showed that the M-A constituent acted as an initiation site of cleavage facets or secondary cracks. Temper-bead thermal cycles could improve the toughness of ICCGHAZs due to the decomposition of M-A constituents, but the toughness improvement by the temper-bead thermal cycle was influenced strongly by the cooling time {Delta}t{sub 8/5(2)eff} of the second thermal cycle. For short cooling time {Delta}t{sub 8/5(2)eff}, namely for low welding heat-input, the toughness improvement was significant.

  17. Studying DDT susceptibility at discriminating time interval focusing maximum limit of exposure time survived by DDT resistant Phlebotomus argentipes (Diptera: Psychodidae) - an investigatory report.

    PubMed

    Rama, Aarti; Kesari, Shreekant; Das, Pradeep; Kumar, Vijay

    2017-02-28

    Extensive application of routine insecticide i.e., Dichlorodiphenyltrichloroethane (DDT) to control Phlebotomus argentipes (Diptera: Psychodidae), the proven vector of Visceral leishmaniasis (VL) in India, had evoked the problem of resistance/ tolerance against DDT, eventually nullifying the DDT dependent strategies to handle the nuisance caused by them. Because tolerating an hour exposure of DDT is not so challenging for resistant P. argentipes, estimating susceptibility by exposing sand flies to insecticide for just an hour becomes trivial and futile task.Therefore, present bioassay study was carried out to investigate the maximum limit of exposure time to which DDT resistant P. argentipes combat its effect for their survival. The mortality rate of laboratory reared DDT resistant strain P. argentipes exposed to DDT was studied at discriminating time intervals of 60 minutes and concluded that highly resistant sand flies can withstand up to 420 minutes of this insecticide exposure. Also, the Lethal time (LT) for female P. argentipes were observed to be higher than that of male suggesting its nature of being highly resistant to its toxicity. The result is supportive for monitoring the tolerance limit with respect to time and hence attribute towards an urgent need of change in rhetoric form of WHO protocol for susceptibility identification in resistant P. argentipes.

  18. Comparative survival of commercial probiotic formulations: tests in biorelevant gastric fluids and real-time measurements using microcalorimetry.

    PubMed

    Fredua-Agyeman, M; Gaisford, S

    2015-03-01

    The large number of probiotic products now available makes the decision about which product to choose difficult both for the consumer and for the specialist providing dietary/nutritional advice. Data on the viability of the bacteria in these products, in an in vivo situation, are therefore important. This study was designed to explore the comparative health and survival of probiotic species in various commercial formulations, using more realistic test systems. This might allow further understanding of factors that must be controlled to optimise the delivery of live healthy bacteria to the lower gut. A total of eight commercially available probiotic preparations were selected for enumeration tests and in vitro gastric tolerance tests. Tolerance assays were conducted in porcine gastric fluid (PGF) fed and fasted state (pH 3.4±0.04), simulated gastric fluid (SGF, pH adjusted to 1.2 and 3.4) and fasted state simulated gastric fluid (FaSSGF, pH adjusted to 1.6 and 3.4). Isothermal microcalorimetry was also used to measure real-time growth of probiotics after exposure to simulated gastric fluid. Results from the enumeration tests indicated that recovery of viable organisms per dose is the same as or better than the stated label claims for liquid-based formulations, but lower than the stated claim for freeze-dried products. Results from the in vitro tolerance tests overall suggest that the PGF provided a harsher environment than the simulated systems at similar pH. In general, liquid-based products tested tended to give superior results in terms of survival compared with the freeze-dried products tested. Results from tests in the fed state in PGF suggested that food greatly affects viability. Microcalorimetric data showed that for some products probiotic species were able to grow following exposure to gastric fluid, suggesting that viable bacteria reach the gut in vivo.

  19. Is Leptospira able to survive in raw milk? Study on the inactivation at different storage times and temperatures.

    PubMed

    Fratini, Filippo; Turchi, Barbara; Ferrone, Martina; Galiero, Alessia; Nuvoloni, Roberta; Torracca, Beatrice; Cerri, Domenico

    2016-09-01

    The consumption of raw milk is currently increasing due to several beneficial aspects, such as nutritional qualities, taste, and health benefits. However, some authors highlight the potential risk associated with raw milk consumption. In Italy, while the absence of some pathogen microorganisms is set by the regional regulation DGR 381/2007, for other microorganisms, such as Leptospira, no recommendations are provided. Leptospira is not ascribed among classical milk pathogens; however, it can potentially be present in raw milk. The aim of this study was to evaluate the survival in raw milk of six serovars of Leptospira after storage at different temperatures (4 °C ± 2 °C, 20 °C ± 2 °C, and 30 °C ± 2 °C) for different incubation times (20 min, 45 min, 1 h, and 1 h and 30 min), in order to determine the potential risk for consumers. Moreover, the immediate effect of bovine, goat, and donkey raw milk on tested Leptospira serovars was visually evaluated. After incubation, all samples were subcultured in EMJH and incubated aerobically at 30 °C for 3 months. All inoculated media were weekly examined by dark-field microscope in order to assess Leptospira survival. Extemporary observation of strains' behavior in milk allowed to detect an almost immediate motility loss, and no leptospires were detected by microscopic observations carried out weekly during the trial period. According to our results, it could be possible to exclude raw milk as a source of Leptospira infection for consumers.

  20. Technology Tools for the Tough Tasks: Plug in for Great Outcomes

    ERIC Educational Resources Information Center

    Simon, Fran

    2012-01-01

    There are a lot of easy-to-use online tools that can help teachers and administrators with the tough tasks involved in running efficient, responsive, and intentional programs. The efficiencies offered through these systems allow busy educators to spend less time managing information and more time doing the work that matters the most--working with…

  1. Increasing pipeline mechanical integrity through the management of mechanical and toughness data

    SciTech Connect

    Biagiotti, S.F. Jr.; Battisti, J.A.

    1996-07-01

    On October 22, 1991, prompted by two brittle fractures that initiated after pipe movement events, the Office of Pipeline Safety (OPS) issued an Alert Notice requiring pipeline owners and operators of gas or hazardous liquid pipeline facilities to conduct analyses before moving pipelines, whether or not the pipelines are pressurized at the time of movement. Since most operators have not typically maintained detailed information on the material characteristics of all steel pipelines in operation (i.e. fracture toughness properties), the OPS recommended that samples of new pipe, stock pipe, and pipe removed from service should be tested and the results accumulated into a database. To this end, Marathon Pipe Line (MPL) Company developed an in-house database system to manage mechanical, toughness, and weldability properties of pipeline materials. Marathon`s approach to the management of pipeline toughness and mechanical data is presented herein. During the design phase of a planned pipe movement, such as a line lowering, engineers consult the database for mechanical and toughness information related to the grade, size, and line section of interest. Based on the mechanical and toughness historical data, a safe line lowering condition is recommended. Over the last two years, more than 1,200 sets of data on more than 200 line sections have been entered into the database.

  2. Tough photoluminescent hydrogels doped with lanthanide.

    PubMed

    Wang, Mei Xiang; Yang, Can Hui; Liu, Zhen Qi; Zhou, Jinxiong; Xu, Feng; Suo, Zhigang; Yang, Jian Hai; Chen, Yong Mei

    2015-03-01

    Photoluminescent hydrogels have emerged as novel soft materials with potential applications in many fields. Although many photoluminescent hydrogels have been fabricated, their scope of usage has been severely limited by their poor mechanical performance. Here, a facile strategy is reported for preparing lanthanide (Ln)-alginate/polyacrylamide (PAAm) hydrogels with both high toughness and photoluminescence, which has been achieved by doping Ln(3+) ions (Ln = Eu, Tb, Eu/Tb) into alginate/PAAm hydrogel networks, where Ln(3+) ions serve as both photoluminescent emitters and physical cross-linkers. The resulting hydrogels exhibit versatile advantages including excellent mechanical properties (∼ MPa strength, ≈ 20 tensile strains, ≈ 10(4) kJ m(-3) energy dissipation), good photoluminescent performance, tunable emission color, excellent processability, and cytocompatibility. The developed tough photoluminescent hydrogels hold great promises for expanding the usage scope of hydrogels.

  3. Advanced Vadose Zone Simulations Using TOUGH

    SciTech Connect

    Finsterle, S.; Doughty, C.; Kowalsky, M.B.; Moridis, G.J.; Pan,L.; Xu, T.; Zhang, Y.; Pruess, K.

    2007-02-01

    The vadose zone can be characterized as a complex subsurfacesystem in which intricate physical and biogeochemical processes occur inresponse to a variety of natural forcings and human activities. Thismakes it difficult to describe, understand, and predict the behavior ofthis specific subsurface system. The TOUGH nonisothermal multiphase flowsimulators are well-suited to perform advanced vadose zone studies. Theconceptual models underlying the TOUGH simulators are capable ofrepresenting features specific to the vadose zone, and of addressing avariety of coupled phenomena. Moreover, the simulators are integratedinto software tools that enable advanced data analysis, optimization, andsystem-level modeling. We discuss fundamental and computationalchallenges in simulating vadose zone processes, review recent advances inmodeling such systems, and demonstrate some capabilities of the TOUGHsuite of codes using illustrative examples.

  4. Tough germanium nanoparticles under electrochemical cycling.

    PubMed

    Liang, Wentao; Yang, Hui; Fan, Feifei; Liu, Yang; Liu, Xiao Hua; Huang, Jian Yu; Zhu, Ting; Zhang, Sulin

    2013-04-23

    Mechanical degradation of the electrode materials during electrochemical cycling remains a serious issue that critically limits the capacity retention and cyclability of rechargeable lithium-ion batteries. Here we report the highly reversible expansion and contraction of germanium nanoparticles under lithiation-delithiation cycling with in situ transmission electron microscopy (TEM). During multiple cycles to the full capacity, the germanium nanoparticles remained robust without any visible cracking despite ∼260% volume changes, in contrast to the size-dependent fracture of silicon nanoparticles upon the first lithiation. The comparative in situ TEM study of fragile silicon nanoparticles suggests that the tough behavior of germanium nanoparticles can be attributed to the weak anisotropy of the lithiation strain at the reaction front. The tough germanium nanoparticles offer substantial potential for the development of durable, high-capacity, and high-rate anodes for advanced lithium-ion batteries.

  5. Effect of groove on bone fracture toughness.

    PubMed

    Norman, T L; Vashishth, D; Burr, D B

    1992-12-01

    When testing for the effects of bone orientation on mode I fracture toughness, compact tension specimens are grooved with a V-notch to provide a crack guide. The effect of grooving on the expressions for the critical stress intensity factor (Kc) and the critical strain energy release rate (Gc) for mode I fracture toughness was investigated. Experiments were performed using grooved and ungrooved bovine compact tension specimens. The results indicate that the standard expression used to determine Kc for a compact tension specimen requires modification. The thickness (B) must be modified to account for the thickness between the grooves (Bn). The thickness used in the standard expression is replaced by an effective thickness written as (BBn)0.5. It was also found that the thickness between the grooves should be used in the standard formula for Gc.

  6. Influence of estrus expression prior to fixed-time AI on embryo survival to maternal recognition of pregnancy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estradiol has been reported to play a critical role in pregnancy establishment and embryonic survival. Our objective was to focus on the role of preovulatory estradiol in embryo survival from fertilization to maternal recognition of pregnancy. Beef cows (n = 29) were synchronized with the CO-Synch p...

  7. Tough Polymer Alloys via Chemically Controlled Morphology

    DTIC Science & Technology

    2007-11-02

    involved the use of polyamides , polyesters and polycarbonates as one component in the blend. The other component was a reactive elastomer , an ABS...material, a core-shell impact modifier, or polypropylene. The end group configuration of the polyamide was shown to be an important consideration in...producing super-tough polyamide blends with low ductile-brittle transition temperatures are described. Cavitation of the rubber phase was shown to be an important part of the toughening mechanism in certain cases.

  8. High toughness-high strength iron alloy

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R. (Inventor)

    1980-01-01

    An iron alloy is provided which exhibits strength and toughness characteristics at cryogenic temperatures. The alloy consists essentially of about 10 to 16 percent by weight nickel, about 0.1 to 1.0 percent by weight aluminum, and 0 to about 3 percent by weight copper, with the balance being essentially iron. The iron alloy is produced by a process which includes cold rolling at room temperature and subsequent heat treatment.

  9. Fracture toughness testing data. A bibliography

    NASA Technical Reports Server (NTRS)

    Carpenter, J. L., Jr.; Moya, N.; Stuhrke, W. F.

    1975-01-01

    This bibliography is comprised of approximately 800 reference citations related to the mechanics of failure in aerospace structures. Most of the references are for documents that include fracture toughness testing data and its application or documents on the availability and usefulness of fracture mechanics analysis methodology. The bibliography represents a search of the literature published in the period April 1962 through April 1974 and is largely limited to documents published in the United States.

  10. High strength and high toughness steel

    DOEpatents

    Parker, Earl R.; Zackay, Victor F.

    1979-01-01

    A structural steel which possess both high strength and high toughness and has particular application of cryogenic uses. The steel is produced by the utilization of thermally induced phase transformation following heating in a three-phase field in iron-rich alloys of the Fe-Ni-Ti system, with a preferred composition of 12% nickel, 0.5% titanium, the remainder being iron.

  11. An exploratory discrete-time multilevel analysis of the effect of social support on the survival of elderly people in China.

    PubMed

    Feng, Zhixin; Jones, Kelvyn; Wang, Wenfei Winnie

    2015-04-01

    This study undertakes a survival analysis of elderly persons in China using Chinese Longitudinal Healthy Longevity Survey 2002-2008. Employing discrete-time multilevel models, we explored the effect of social support on the survival of elderly people in China. This study focuses on objective (living arrangements and received support) and subjective activities (perceived support) of social support, finding that the effect of different activities of social support on the survival of elderly people varies according to the availability of different support resources. Specifically, living with a spouse, financial independence, perceiving care support from any resource is associated with higher survival rates for elderly people. Separate analysis focusing on urban elderly and rural elderly revealed broadly similar results. There is a larger difference between those perceiving care support from family or social service and not perceiving care support in urban areas comparing to those in rural areas. Those who cannot pay medical expenses are the least likely to survive. The higher level of economic development in province has no significant effect on the survival of elderly people for the whole sample model and the elderly people in urban areas; however, there is a negative influence on the survival of the rural elderly people.

  12. An exploratory discrete-time multilevel analysis of the effect of social support on the survival of elderly people in China

    PubMed Central

    Feng, Zhixin; Jones, Kelvyn; Wang, Wenfei Winnie

    2015-01-01

    This study undertakes a survival analysis of elderly persons in China using Chinese Longitudinal Healthy Longevity Survey 2002–2008. Employing discrete-time multilevel models, we explored the effect of social support on the survival of elderly people in China. This study focuses on objective (living arrangements and received support) and subjective activities (perceived support) of social support, finding that the effect of different activities of social support on the survival of elderly people varies according to the availability of different support resources. Specifically, living with a spouse, financial independence, perceiving care support from any resource is associated with higher survival rates for elderly people. Separate analysis focusing on urban elderly and rural elderly revealed broadly similar results. There is a larger difference between those perceiving care support from family or social service and not perceiving care support in urban areas comparing to those in rural areas. Those who cannot pay medical expenses are the least likely to survive. The higher level of economic development in province has no significant effect on the survival of elderly people for the whole sample model and the elderly people in urban areas; however, there is a negative influence on the survival of the rural elderly people. PMID:25703671

  13. Greatly Increased Toughness of Infiltrated Spider Silk

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Mo; Pippel, Eckhard; Gösele, Ulrich; Dresbach, Christian; Qin, Yong; Chandran, C. Vinod; Bräuniger, Thomas; Hause, Gerd; Knez, Mato

    2009-04-01

    In nature, tiny amounts of inorganic impurities, such as metals, are incorporated in the protein structures of some biomaterials and lead to unusual mechanical properties of those materials. A desire to produce these biomimicking new materials has stimulated materials scientists, and diverse approaches have been attempted. In contrast, research to improve the mechanical properties of biomaterials themselves by direct metal incorporation into inner protein structures has rarely been tried because of the difficulty of developing a method that can infiltrate metals into biomaterials, resulting in a metal-incorporated protein matrix. We demonstrated that metals can be intentionally infiltrated into inner protein structures of biomaterials through multiple pulsed vapor-phase infiltration performed with equipment conventionally used for atomic layer deposition (ALD). We infiltrated zinc (Zn), titanium (Ti), or aluminum (Al), combined with water from corresponding ALD precursors, into spider dragline silks and observed greatly improved toughness of the resulting silks. The presence of the infiltrated metals such as Al or Ti was verified by energy-dispersive x-ray (EDX) and nuclear magnetic resonance spectra measured inside the treated silks. This result of enhanced toughness of spider silk could potentially serve as a model for a more general approach to enhance the strength and toughness of other biomaterials.

  14. Investigating Whether and When English Learners are Reclassified into Mainstream Classrooms in the United States: A Discrete-Time Survival Analysis

    ERIC Educational Resources Information Center

    Slama, Rachel B.

    2014-01-01

    Using eight waves of longitudinal data on a statewide kindergarten cohort of English learners (ELs), I examined ELs' tenure in language-learning programs and their academic performance following reclassification as fluent English proficient. I employed discrete-time survival analysis to estimate the average time to and grade of reclassification…

  15. Adipose-derived Stem Cell Conditioned Media Extends Survival time of a mouse model of Amyotrophic Lateral Sclerosis

    PubMed Central

    Fontanilla, Christine V.; Gu, Huiying; Liu, Qingpeng; Zhu, Timothy Z.; Zhou, Changwei; Johnstone, Brian H.; March, Keith L.; Pascuzzi, Robert M.; Farlow, Martin R.; Du, Yansheng

    2015-01-01

    Adipose stromal cells (ASC) secrete various trophic factors that assist in the protection of neurons in a variety of neuronal death models. In this study, we tested the effects of human ASC conditional medium (ASC-CM) in human amyotrophic lateral sclerosis (ALS) transgenic mouse model expressing mutant superoxide dismutase (SOD1G93A). Treating symptomatic SOD1G93A mice with ASC-CM significantly increased post-onset survival time and lifespan. Moreover, SOD1G93A mice given ASC-CM treatment showed high motor neuron counts, less activation of microglia and astrocytes at an early symptomatic stage in the spinal cords under immunohistochemical analysis. SOD1G93A mice treated with ASC-CM for 7 days showed reduced levels of phosphorylated p38 (pp38) in the spinal cord, a mitogen-activated protein kinase that is involved in both inflammation and neuronal death. Additionally, the levels of α-II spectrin in spinal cords were also inhibited in SOD1G93A mice treated with ASC-CM for 3 days. Interestingly, nerve growth factor (NGF), a neurotrophic factor found in ASC-CM, played a significant role in the protection of neurodegeneration inSOD1G93A mouse. These results indicate that ASC-CM has the potential to develop into a novel and effective therapeutic treatment for ALS. PMID:26586020

  16. Expression of S1P metabolizing enzymes and receptors correlate with survival time and regulate cell migration in glioblastoma multiforme.

    PubMed

    Bien-Möller, Sandra; Lange, Sandra; Holm, Tobias; Böhm, Andreas; Paland, Heiko; Küpper, Johannes; Herzog, Susann; Weitmann, Kerstin; Havemann, Christoph; Vogelgesang, Silke; Marx, Sascha; Hoffmann, Wolfgang; Schroeder, Henry W S; Rauch, Bernhard H

    2016-03-15

    A signaling molecule which is involved in proliferation and migration of malignant cells is the lipid mediator sphingosine-1-phosphate (S1P). There are hints for a potential role of S1P signaling in malignant brain tumors such as glioblastoma multiforme (GBM) which is characterized by a poor prognosis. Therefore, a comprehensive expression analysis of S1P receptors (S1P1-S1P5) and S1P metabolizing enzymes in human GBM (n = 117) compared to healthy brain (n = 10) was performed to evaluate their role for patient´s survival. Furthermore, influence of S1P receptor inhibition on proliferation and migration were studied in LN18 GBM cells. Compared to control brain, mRNA levels of S1P1, S1P2, S1P3 and S1P generating sphingosine kinase-1 were elevated in GBM. Kaplan-Meier analyses demonstrated an association between S1P1 and S1P2 with patient´s survival times. In vitro, an inhibitory effect of the SphK inhibitor SKI-II on viability of LN18 cells was shown. S1P itself had no effect on viability but stimulated LN18 migration which was blocked by inhibition of S1P1 and S1P2. The participation of S1P1 and S1P2 in LN18 migration was further supported by siRNA-mediated silencing of these receptors. Immunoblots and inhibition experiments suggest an involvement of the PI3-kinase/AKT1 pathway in the chemotactic effect of S1P in LN18 cells.In summary, our data argue for a role of S1P signaling in proliferation and migration of GBM cells. Individual components of the S1P pathway represent prognostic factors for patients with GBM. Perspectively, a selective modulation of S1P receptor subtypes could represent a therapeutic approach for GBM patients and requires further evaluation.

  17. Use of Synergistic Interactions to Fabricate Strong, Tough, and Conductive Artificial Nacre Based on Graphene Oxide and Chitosan.

    PubMed

    Wan, Sijie; Peng, Jingsong; Li, Yuchen; Hu, Han; Jiang, Lei; Cheng, Qunfeng

    2015-10-27

    Graphene is the strongest and stiffest material, leading to the development of promising applications in many fields. However, the assembly of graphene nanosheets into macrosized nanocomposites for practical applications remains a challenge. Nacre in its natural form sets the "gold standard" for toughness and strength, which serves as a guide to the assembly of graphene nanosheets into high-performance nanocomposites. Here we show the strong, tough, conductive artificial nacre based on graphene oxide through synergistic interactions of hydrogen and covalent bonding. Tensile strength and toughness was 4 and 10 times higher, respectively, than that of natural nacre. The exceptional integrated strong and tough artificial nacre has promising applications in aerospace, artificial muscle, and tissue engineering, especially for flexible supercapacitor electrodes due to its high electrical conductivity. The use of synergistic interactions is a strategy for the development of high-performance nanocomposites.

  18. Anuran larval developmental plasticity and survival in response to variable salinity of ecologically relevant timing and magnitude.

    PubMed

    Kearney, Brian D; Pell, Rebecca J; Byrne, Phillip G; Reina, Richard D

    2014-12-01

    Salinity in affected freshwater ecosystems fluctuates with seasonal rainfall, tidal flux, rates of evaporation, chemical runoff and the influence of secondary salinization. Environmental stressors such as salinity can have lasting effects on anuran development, yet little is known about the effects of fluctuating salinity on tadpole ontogeny or the effects of differing magnitudes of salinity exposure, as would occur in natural wetland systems. We examined how salinity fluctuations affected survival, growth and development of Litoria ewingii by exposing tadpoles to a range of salinity concentrations (5.6-10.85 ppt) at three different stages of development (hind limb-bud formation; toe differentiation and forearm development). We also investigated the plasticity of tadpole growth rates in response to non-lethal, transient salinity influxes, specifically examining the capacity for compensatory growth and its relationship to the timing, magnitude or frequency of salinity exposure. Our results show that later-stage tadpoles are more tolerant to elevated salinity than those exposed at a younger age, and that exposure to high salinity later in life suppresses the potential for compensatory growth. Tadpoles exposed to transient low salinity lost less mass during metamorphosis than animals in constant salinity treatments, indicating a possible alternate to compensatory growth. Exposure to near-lethal salinities early in development did not alter tadpole responses to subsequent salinity stress. Our results provide some of the first evidence that both the timing and magnitude of transient environmental stressors can have an effect on anuran development and developmental trade-offs in a stressful environment.

  19. iTOUGH2 Universal Optimization Using the PEST Protocol

    SciTech Connect

    Finsterle, S.A.

    2010-07-01

    iTOUGH2 (http://www-esd.lbl.gov/iTOUGH2) is a computer program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis [Finsterle, 2007a, b, c]. iTOUGH2 contains a number of local and global minimization algorithms for automatic calibration of a model against measured data, or for the solution of other, more general optimization problems (see, for example, Finsterle [2005]). A detailed residual and estimation uncertainty analysis is conducted to assess the inversion results. Moreover, iTOUGH2 can be used to perform a formal sensitivity analysis, or to conduct Monte Carlo simulations for the examination for prediction uncertainties. iTOUGH2's capabilities are continually enhanced. As the name implies, iTOUGH2 is developed for use in conjunction with the TOUGH2 forward simulator for nonisothermal multiphase flow in porous and fractured media [Pruess, 1991]. However, iTOUGH2 provides FORTRAN interfaces for the estimation of user-specified parameters (see subroutine USERPAR) based on user-specified observations (see subroutine USEROBS). These user interfaces can be invoked to add new parameter or observation types to the standard set provided in iTOUGH2. They can also be linked to non-TOUGH2 models, i.e., iTOUGH2 can be used as a universal optimization code, similar to other model-independent, nonlinear parameter estimation packages such as PEST [Doherty, 2008] or UCODE [Poeter and Hill, 1998]. However, to make iTOUGH2's optimization capabilities available for use with an external code, the user is required to write some FORTRAN code that provides the link between the iTOUGH2 parameter vector and the input parameters of the external code, and between the output variables of the external code and the iTOUGH2 observation vector. While allowing for maximum flexibility, the coding requirement of this approach limits its applicability to those users with FORTRAN coding knowledge. To make iTOUGH2 capabilities accessible to many application models

  20. The relationship between annual survival rate and migration distance in mallards: an examination of the time-allocation hypothesis for the evolution of migration

    USGS Publications Warehouse

    Hestbeck, J.B.; Nichols, J.D.; Hines, J.E.

    1992-01-01

    Predictions of the time-allocation hypothesis were tested with several a posteriori analyses of banding data for the mallard (Anas platyrhynchos). The time-allocation hypothesis states that the critical difference between resident and migrant birds is their allocation of time to reproduction on the breeding grounds and survival on the nonbreeding grounds. Residents have higher reproduction and migrants have higher survival. Survival and recovery rates were estimated by standard band-recovery methods for banding reference areas in the central United States and central Canada. A production-rate index was computed for each reference area with data from the U.S. Fish and Wildlife Service May Breeding Population Survey and July Production Survey. An analysis of covariance was used to test for the effects of migration distance and time period (decade) on survival, recovery, and production rates. Differences in migration chronology were tested by comparing direct-recovery distributions for different populations during the fall migration. Differences in winter locations were tested by comparing distributions of direct recoveries reported during December and January. A strong positive relationship was found between survival rate, and migration distance for 3 of the 4 age and sex classes. A weak negative relationship was found between recovery rate and migration distance. No relationship was found between production rate and migration distance. During the fall migration, birds from the northern breeding populations were located north of birds from the southern breeding populations. No pattern could be found in the relative locations of breeding and wintering areas. Although our finding that survival rate increased with migration distance was consistent with the time-allocation hypothesis, our results on migration chronology and location of wintering areas were not consistent with the mechanism underlying the time-allocation hypothesis. Neither this analysis nor other recent

  1. 'Diamond Jenness': A Tough Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic of the target area called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  2. Evaluation of the 2008 Predictions of Run-Timing and Survival of Wild Migrant Yearling Chinook and Steelhead on the Columbia and Snake Rivers.

    SciTech Connect

    Beer, W. Nicholas; Iltis, Susannah; Anderson, James J.

    2009-01-01

    Columbia Basin Research uses the COMPASS model on a daily basis during the outmigration of Snake River Chinook and steelhead smolts to predict downstream passage and survival. Fish arrival predictions and observations from program RealTime along with predicted and observed environmental conditions are used to make in-season predictions of arrival and survival to various dams in the Columbia and Snake Rivers. For 2008, calibrations of travel and survival parameters for two stocks of fish-Snake River yearling PIT-tagged wild chinook salmon (chin1pit) and Snake River PIT-tagged steelhead (lgrStlhd)-were used to model travel and survival of steelhead and chinook stocks from Lower Granite Dam (LWG) or McNary Dam (MCN) to Bonneville Dam (BON). This report summarizes the success of the COMPASS/RealTime process to model these migrations as they occur. We compared model results on timing and survival to data from two sources: stock specific counts at dams and end-of-season control survival estimates (Jim Faulkner, NOAA, pers. comm. Dec. 16, 2008). The difference between the predicted and observed day of median passage and the Mean Absolute Deviation (MAD) between predicted and observed arrival cumulative distributions are measures of timing accuracy. MAD is essentially the average percentage error over the season. The difference between the predicted and observed survivals is a measure of survival accuracy. Model results and timing data were in good agreement from LWG to John Day Dam (JDA). Predictions of median passage days for the chin1pit and lgrStlhd stocks were 0 and 2 days (respectively) later than observed. MAD for chin1pit and lgrStlhd stocks at JDA were 2.3% and 5.9% (respectively). Between JDA and BON modeling and timing data were not as well matched. At BON, median passage predictions were 6 and 10 days later than observed and MAD values were 7.8% and 16.0% respectively. Model results and survival data were in good agreement from LWG to MCN. COMPASS predicted

  3. Estimating plane strain fracture toughness of high strength aluminum alloys from crack arrest toughness

    NASA Technical Reports Server (NTRS)

    Dorward, R. C.; Hasse, K. R.

    1977-01-01

    A comparison is made between fracture toughness KIc as measured by recommended ASTM procedures and crack arrest toughness KIa as measured on more than 100 bolt-loaded double-cantilever beam (DCB) specimens from 7075, 7050, and 7049 alloy plates. Close agreement was found between the two values, KIa being on the average less than KIc over a specified range. This indicates that a simplified test based on a bolt-loaded DCB specimen could be used for quality control, lot release, and screening purposes. Measurements of crack length and specimen deflection are all that are required. The specimens do not have to be fatigue precracked, nor is a tensile machine needed.

  4. Low-Temperature Toughness of the Austempered Offshore Steel

    NASA Astrophysics Data System (ADS)

    Yu, C.; Yang, T. C.; Huang, C. Y.; Shiue, R. K.

    2016-10-01

    This study investigates low-temperature toughness of the offshore steel with two different austempering heat treatments. Toughness of upper bainite is significantly lower than that of lower bainite. Low impact toughness of the upper bainite is caused by the presence of martensite-austenite (MA) and increasing the amount of low-angle lath boundaries in upper bainite package. EBSD equipped in the SEM demonstrates an effective approach to analyze the misorientation angle of lath boundaries in upper bainite packet.

  5. Marine Structural Steel Toughness Data Bank (Abridged Edition)

    DTIC Science & Technology

    1990-08-31

    August 28, 1991 SR-1311 MARINE STRUCTURAL STEEL TOUGHNESS DATA BANK (ABRIDGED EDITION) A substantial amount of toughness data for commonly used marine... steels is available to ship designers. The information, however, did not exist in a comprehensive database that users could access. The Ship Structure...Committee recognized the need for a conve -ent source of materials design data and sponsored the development of the Marine Structural Steel Toughness

  6. The effects of ambient temperature and mixing time of glass ionomer cement material on the survival rate of proximal ART restorations in primary molars

    PubMed Central

    Kemoli, Arthur M

    2014-01-01

    Objective: Temperature fluctuations and material mixing times are likely to affect the consistency and integrity of the material mixture, and hence the restoration made out of it. The purpose of the present study was to determine the influence of the ambient temperature and the mixing time of glass ionomer cement (GIC) restorative material on the survival rate of proximal atraumatic restorative treatment (ART) restorations placed in primary molars. Materials and Methods: A total of 804 restorations were placed in the primary molars of 6-8-year-olds using the ART approach. The restorations were then followed for a period of 2 years and evaluated at given intervals. The data collected were analyzed using SPSS computer statistical program, and the results tested and compared using the Chi-square, Kaplan Meier survival analysis and Cox Proportional hazard statistical tests. Results: The cumulative survival rate of the restorations dropped from the initial 94.4% to 30.8% at the end of 2 years. The higher survival rate of the restorations was associated with the experienced operators and assistants when using the rubber dam isolation method. However, there was no statistically significant difference in the survival rate of the restorations when related to the room temperature and the mixing time of the GIC materials used in spite of the variations in the temperature recoded and the methods used in mixing the materials. Conclusion: The ambient temperature and mixing time of GIC did not have a significant effect on the survival of the proximal ART restorations. PMID:24808692

  7. The effect of electric discharge machined notches on the fracture toughness of several structural alloys

    SciTech Connect

    Joyce, J.A.; Link, R.E.

    1993-09-01

    Recent computational studies of the stress and strain fields at the tip of very sharp notches have shown that the stress and strain fields are very weakly dependent on the initial geometry of the notch once the notch has been blunted to a radius that is 6 to 10 times the initial root radius. It follows that if the fracture toughness of a material is sufficiently high so that fracture initiation does not occur in a specimen until the crack-tip opening displacement (CTOD) reaches a value from 6 to 10 times the size of the initial notch tip diameter, then the fracture toughness will be independent of whether a fatigue crack or a machined notch served as the initial crack. In this experimental program the fracture toughness (J{sub Ic} and J resistance (J-R) curve, and CTOD) for several structure alloys was measured using specimens with conventional fatigue cracks and with EDM machined notches. The results of this program have shown, in fact, that most structural materials do not achieve initiation CTOD values on the order of 6 to 10 times the radius of even the smallest EDM notch tip presently achievable. It is found furthermore that tougher materials do not seem to be less dependent on the type of notch tip present. Some materials are shown to be much more dependent on the type of notch tip used, but no simple pattern is found that relates this observed dependence to the material strength toughness, or strain hardening rate.

  8. Survival of timber rattlesnakes (Crotalus horridus) estimated by capture-recapture models in relation to age, sex, color morph, time, and birthplace

    USGS Publications Warehouse

    Brown, W.S.; Kery, M.; Hines, J.E.

    2007-01-01

    Juvenile survival is one of the least known elements of the life history of many species, in particular snakes. We conducted a mark–recapture study of Crotalus horridus from 1978–2002 in northeastern New York near the northern limits of the species' range. We marked 588 neonates and estimated annual age-, sex-, and morph-specific recapture and survival rates using the Cormack-Jolly-Seber (CJS) model. Wild-caught neonates (field-born, n  =  407) and neonates produced by captive-held gravid females (lab-born, n  =  181) allowed comparison of the birthplace, or lab treatment effect, in estimated survival. Recapture rates declined from about 10–20% over time while increasing from young to older age classes. Estimated survival rates (S ± 1 SE) in the first year were significantly higher among field-born (black morph: S  =  0.773 ± 0.203; yellow morph: S  =  0.531 ± 0.104) than among lab-born snakes (black morph: S  =  0.411 ± 0.131; yellow morph: S  =  0.301 ± 0.081). Lower birth weights combined with a lack of field exposure until release apparently contributed to the lower survival rate of lab-born snakes. Subsequent survival estimates for 2–4-yr-old snakes were S  =  0.845 ± 0.084 for the black morph and S  =  0.999 (SE not available) for the yellow morph, and for ≥5-yr-old snakes S  =  0.958 ± 0.039 (black morph) and S  =  0.822 ± 0.034 (yellow morph). The most parsimonious model overall contained an independent time trend for survival of each age, morph, and lab-treatment group. For snakes of the first two age groups (ages 1 yr and 2–4 yr), survival tended to decline over the years for both morphs, while for adult snakes (5 yr and older), survival was constant or even slightly increased. Our data on survival and recapture are among the first rigorous estimates of these parameters in a rattlesnake and among the few yet available for any viperid snake. These data are useful for analyses of the life

  9. Fracture toughness properties of welded stainless steels for tritium service

    SciTech Connect

    Morgan, M.

    1994-10-01

    Studies to determine tritium exposure effects on the properties of welded steels are being conducted. In this investigation, the effects of tritium and decay helium on the fracture toughness properties of high-energy-rate-forged (HERF) Incoloy 903 were. Fracture toughness measurements were conducted for tritium-exposed samples in the as-forged condition and compared with welded samples. Tritium-exposed HERF Incoloy 903 had fracture toughness values that were 33% lower than those for unexposed HERF Incoloy 903. Tritium-exposed welded samples had fracture toughness values that were just 8% of the unexposed HERF alloys and 28% of unexposed welded alloys.

  10. iTOUGH2 v7.1

    SciTech Connect

    FINSTERLE, STEFAN; JUNG, YOOJIN; KOWALSKY, MICHAEL; MAGNUSDOTTIR, LILJA; PAU, GEORGE; WAINWRIGHT, HARUKO; ZHANG, YINGQI

    2016-09-15

    iTOUGH2 (inverse TOUGH2) provides inverse modeling capabilities for TOUGH2, a simulator for multi-dimensional, multi-phase, multi-component, non-isothermal flow and transport in fractured porous media. iTOUGH2 performs sensitivity analyses, data-worth analyses, parameter estimation, and uncertainty propagation analyses in geosciences and reservoir engineering and other application areas. iTOUGH2 supports a number of different combinations of fluids and components (equation-of-state (EOS) modules). In addition, the optimization routines implemented in iTOUGH2 can also be used for sensitivity analysis, automatic model calibration, and uncertainty quantification of any external code that uses text-based input and output files using the PEST protocol. iTOUGH2 solves the inverse problem by minimizing a non-linear objective function of the weighted differences between model output and the corresponding observations. Multiple minimization algorithms (derivative-free, gradient-based, and second-order; local and global) are available. iTOUGH2 also performs Latin Hypercube Monte Carlo simulations for uncertainty propagation analyses. A detailed residual and error analysis is provided. This upgrade includes (a) global sensitivity analysis methods, (b) dynamic memory allocation (c) additional input features and output analyses, (d) increased forward simulation capabilities, (e) parallel execution on multicore PCs and Linux clusters, and (f) bug fixes. More details can be found at http://esd.lbl.gov/iTOUGH2.

  11. Modifications and additions to selected TOUGH2 modules

    SciTech Connect

    Wu, Y.S.; Mishra, A.K.

    1998-01-01

    The purpose of this report is to provide all software baseline documents necessary for the software qualification of the revised versions of the selected TOUGH2 modules, which include single-phase gas (EOS1G), effective continuum method (EOS3/ECM), saturated/unsaturated flow (EOS9), and radionuclide transport (T2R3D) modules of the TOUGH2 code. TOUGH2 is a numerical simulation code for multi-dimensional, coupled fluid and heat flow of multiphase, multicomponent fluid mixtures in porous and fractured media. This report augments the document Software Qualification of Selected TOUGH2 modules. This report contains the following sections: (1) requirement specifications and code development and (2) software validation test plan and results. These sections comprise sequential parts of Software Lifecycle, and should be used in conjunction with the TOUGH User`s Guide, TOUGH2 documentation, TOUGH2 Software Qualification, and Software Qualification of Selected TOUGH2 modules. The version of TOUGH2 used with the software being qualified herein is the October 1996 Standard Version 1.2, as qualified in Wu et al. (1996) and housed at the Department of Energy`s Energy Science and Technology Software Center (ESTSC) in Oak Ridge, Tennessee.

  12. Enhanced low-temperature impact toughness of nanostructured Ti

    SciTech Connect

    Stolyarov, V.V.; Valiev, R.Z.; Zhu, Y.T.

    2006-01-23

    Impact toughness is one of the major mechanical properties for structural materials. It is generally observed that in coarse-grained materials the impact toughness decreases with decreasing testing temperature. Here, we report that the impact toughness of nanostructured Ti processed by severe plastic deformation is enhanced at low temperatures of -70 deg. C and -196 deg. C, a unique phenomenon that contradicts the observations in coarse-grained materials. The enhanced impact toughness is attributed to the increased strength and ductility of nanostructured Ti as well as smaller fracture dimples at lower temperatures. This result demonstrates the advantage of using nanostructured Ti in low-temperature applications.

  13. Interphase effect on intralaminar fracture toughness

    SciTech Connect

    Hrivnak, J.A.; Dagastine, R.R.; McCullough, R.L.

    1996-12-31

    In fiber reinforced thermoset composites there is a growing body of experimental evidence which has pointed to a region at the fiber/matrix boundary with properties that differ from the fiber or matrix. This region extends beyond the two dimensional interface at the fiber/matrix boundary to have a finite thickness with chemical and structural property gradients. This leads to the concept of an interphase region. The interphase has a large effect on the thermal and mechanical properties of the composite such as fracture toughness, glass transition temperature and the coefficient of thermal expansion. Understanding the interphase region becomes crucial to tailoring a composite to a desired set of properties.

  14. Fracture toughness testing data: A technology survey

    NASA Technical Reports Server (NTRS)

    Stuhrke, W. F.; Carpenter, J. L., Jr.

    1975-01-01

    Technical abstracts for about 90 significant documents relating to fracture toughness testing for various structural materials including information on plane strain and the developing areas of mixed mode and plane stress test conditions are presented. An overview of the state-of-the-art represented in the documents that have been abstracted is included. The abstracts in the report are mostly for publications in the period April 1962 through April 1974. The purpose of this report is to provide, in quick reference form, a dependable source for current information in the subject field.

  15. Numerical Analysis Of Interlaminar-Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.

    1988-01-01

    Finite-element analysis applied in conjunction with strain-energy and micromechanical concepts. Computational procedure involves local, local-crack-closure, and/or the "unique" local-crack-closure method developed at NASA Lewis Research Center, for mathematical modeling of ENF and MMF. Methods based on three-dimensional finite-element analysis in conjunction with concept of strain-energy-release rate and with micromechanics of composite materials. Assists in interpretation of ENF and MMF fracture tests performed to obtain fracture-toughness parameters, by enabling evaluation of states of stress likely to induce interlaminar fractures.

  16. Time trends in prevalence of activities of daily living (ADL) disability and survival: comparing two populations (aged 78+ years) living in a rural area in Sweden.

    PubMed

    Sjölund, Britt-Marie; Wimo, Anders; Qiu, Chengxuan; Engström, Maria; von Strauss, Eva

    2014-01-01

    The aim was to study time trends in prevalence of disability in ADL and survival among men and women 78 years and older comparing two cohorts. The study was a time trend study based on two population-based community cohorts, the Nordanstig Project (NP), collected 1995-1998 and the Swedish National Study on Aging and Care in Nordanstig (SNAC-N), collected 2001-2003. The participants were people aged 78 years and older from the NP cohort (N=303) and from the SNAC-N cohort (N=406). All were clinically examined by physicians and nurses using standardized protocols. Disability was defined as a need for assistance in one or more ADL activities. The prevalence of disability and survival were compared using logistic and Cox models. The prevalence of ADL disability was stable for men, while women became more disabled in ADL during the time period, OR 2.36 (1.12-4.94). There was no significant difference in survival time between the cohorts in either ADL disabled persons or non-disabled persons. There was a tendency for increased survival for non-disabled persons in SNAC-N compared with NP, although not significant; this was particularly true for women. In general, women survived longer than men did regardless of whether they were ADL disabled or not. The time trends for ADL disability found in the study show that ADL disability had increased in women but not in men. More studies are needed to identify risk factors for ADL disability with a view to preventing it in time.

  17. Risk of Early Onset Substance Use among Students with and without Mild Academic Disabilities: Results of a Discrete-Time Survival Analysis

    ERIC Educational Resources Information Center

    Kepper, Annelies; Koning, Ina; Vollebergh, Wilma; Monshouwer, Karin

    2014-01-01

    This study investigated the age of onset of substance use among 536 students with mild academic disabilities and 906 students without academic disabilities, and the extent to which emotional, conduct, and hyperactivity problems explain the differences between these two groups. Using discrete-time survival analysis, the results of this study showed…

  18. The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical bone

    SciTech Connect

    Zimmermann, Elizabeth A.; Launey, Maximilien E.; Ritchie, Robert O.

    2010-03-25

    The majority of fracture mechanics studies on the toughness of bone have been performed under tensile loading. However, it has recently been shown that the toughness of human cortical bone in the transverse (breaking) orientation is actually much lower in shear (mode II) than in tension (mode I); a fact that is physiologically relevant as in vivo bone is invariably loaded multiaxially. Since bone is a material that derives its fracture resistance primarily during crack growth through extrinsic toughening mechanisms, such as crack deflection and bridging, evaluation of its toughness is best achieved through measurements of the crack-resistance or R-curve, which describes the fracture toughness as a function of crack extension. Accordingly, in this study, we attempt to measure for the first time the R-curve fracture toughness of human cortical bone under physiologically relevant mixed-mode loading conditions. We show that the resulting mixed-mode (mode I + II) toughness depends strongly on the crack trajectory and is the result of the competition between the paths of maximum mechanical driving force and 'weakest' microstructural resistance.

  19. The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical bone

    PubMed Central

    Zimmermann, Elizabeth A.; Launey, Maximilien E.; Ritchie, Robert O.

    2011-01-01

    The majority of fracture mechanics studies on the toughness of bone have been performed under tensile loading. However, it has recently been shown that the toughness of human cortical bone in the transverse (breaking) orientation is actually much lower in shear (mode II) than in tension (mode I); a fact that is physiologically relevant as in vivo bone is invariably loaded multiaxially. Since bone is a material that derives its fracture resistance primarily during crack growth through extrinsic toughening mechanisms, such as crack deflection and bridging, evaluation of its toughness is best achieved through measurements of the crack-resistance or R-curve, which describes the fracture toughness as a function of crack extension. Accordingly, in this study, we attempt to measure for the first time the R-curve fracture toughness of human cortical bone under physiologically relevant mixed-mode loading conditions. We show that the resulting mixed-mode (mode I + II) toughness depends strongly on the crack trajectory and is the result of the competition between the paths of maximum mechanical driving force and “weakest” microstructural resistance. PMID:20409579

  20. The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical bone.

    PubMed

    Zimmermann, Elizabeth A; Launey, Maximilien E; Ritchie, Robert O

    2010-07-01

    The majority of fracture mechanics studies on the toughness of bone have been performed under tensile loading. However, it has recently been shown that the toughness of human cortical bone in the transverse (breaking) orientation is actually much lower in shear (mode II) than in tension (mode I); a fact that is physiologically relevant as in vivo bone is invariably loaded multiaxially. Since bone is a material that derives its fracture resistance primarily during crack growth through extrinsic toughening mechanisms, such as crack deflection and bridging, evaluation of its toughness is best achieved through measurements of the crack-resistance or R-curve, which describes the fracture toughness as a function of crack extension. Accordingly, in this study, we attempt to measure for the first time the R-curve fracture toughness of human cortical bone under physiologically relevant mixed-mode loading conditions. We show that the resulting mixed-mode (mode I+II) toughness depends strongly on the crack trajectory and is the result of the competition between the paths of maximum mechanical driving force and "weakest" microstructural resistance.

  1. Surviving death-anxieties in liquid modern times: examining Zygmunt Bauman's cultural theory of death and dying.

    PubMed

    Higo, Masa

    2012-01-01

    Despite his prominence as a leading contemporary social theorist, Zygmunt Bauman's long-term writing on the cultural theory of death and dying has largely been overlooked in the sociological literature of death and dying, particularly in the United States. Bauman uniquely theorizes how we survive death-anxieties today: Contemporary, liquid modern culture has engaged us in ceaseless pursuit of the unattainable consumer sensation of bodily fitness as a way to suppress and thus survive our death-anxieties. Bauman also argues that the prevalence of this cultural formula to survive death-anxieties has simultaneously increased, more than ever before in social history, the volume of individual responsibility for restlessly coping with existential anxieties in the societies of consumers. While unique and insightful, his theoretical argument has a limitation; largely succeeding Freud's classic view of mortality, Bauman's contemporary theory may lead us to neglect potentially important social, cultural, and historical variations in how mortality has been understood.

  2. Effect of radiotherapy delay in overall treatment time on local control and survival in head and neck cancer: Review of the literature

    PubMed Central

    González Ferreira, José A.; Jaén Olasolo, Javier; Azinovic, Ignacio; Jeremic, Branislav

    2015-01-01

    Treatment delays in completing radiotherapy (RT) for many neoplasms are a major problem affecting treatment outcome, as increasingly shown in the literature. Overall treatment time (OTT) could be a critical predictor of local tumor control and/or survival. In an attempt to establish a protocol for managing delays during RT, especially for heavily overloaded units, we have extensively reviewed the available literature on head and neck cancer. We confirmed a large deleterious effect of prolonged OTT on both local control and survival of these patients. PMID:26549990

  3. Shape effect of ultrafine-grained structure on static fracture toughness in low-alloy steel

    PubMed Central

    Inoue, Tadanobu; Kimura, Yuuji; Ochiai, Shojiro

    2012-01-01

    A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength–toughness balance of the developed steels was markedly better than that of conventionally quenched and tempered steel with a martensitic structure. In particular, the static fracture toughness of the UFEG steel, having a yield strength of 1.86 GPa at ambient temperature, was improved by more than 40 times compared with conventional steel having a yield strength of 1.51 GPa. Furthermore, even at 77 K, the fracture toughness of the UFEG steel was about eight times higher than that of the conventional and UFG steels, despite the high strength of the UFEG steel (2.26 GPa). The UFG steel exhibited brittle fracture behavior at 77 K, as did the conventional steel, and no dimple structure was observed on the fracture surface. Therefore, it is difficult to improve the low-temperature toughness of the UFG steel by grain refinement only. The shape of crystal grains plays an important role in delamination toughening, as do their refinement and orientation. PMID:27877493

  4. Shape effect of ultrafine-grained structure on static fracture toughness in low-alloy steel.

    PubMed

    Inoue, Tadanobu; Kimura, Yuuji; Ochiai, Shojiro

    2012-06-01

    A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength-toughness balance of the developed steels was markedly better than that of conventionally quenched and tempered steel with a martensitic structure. In particular, the static fracture toughness of the UFEG steel, having a yield strength of 1.86 GPa at ambient temperature, was improved by more than 40 times compared with conventional steel having a yield strength of 1.51 GPa. Furthermore, even at 77 K, the fracture toughness of the UFEG steel was about eight times higher than that of the conventional and UFG steels, despite the high strength of the UFEG steel (2.26 GPa). The UFG steel exhibited brittle fracture behavior at 77 K, as did the conventional steel, and no dimple structure was observed on the fracture surface. Therefore, it is difficult to improve the low-temperature toughness of the UFG steel by grain refinement only. The shape of crystal grains plays an important role in delamination toughening, as do their refinement and orientation.

  5. TOUGH+/GasH20 study of the effects of a heat source buried in theMartian permafrost

    SciTech Connect

    Moridis, George J.; Pruess, Karsten

    2006-05-12

    We use TOUGH+/GasH2O to study the effects of a heat sourceburied in the Martian permafrost to evaluate the possibility ofestablishing a wet zone of liquid water, in which terrestrialmicroorganisms could survive and multiply. Analysis of the problemindicates that (1) only a limited permafrost volume (not exceeding 0.35 min radius) is affected, (2) a "wet" zone with limited amounts of liquidwater de-velops (not exceeding 8 and 0.7 kg for a 250 W and a 62.5 Wsource, respectively), (3) the wet zone per-sists for a long time,becomes practically stationary after t = 20 sols because of venting intothe Martian atmosphere, and its thickness is limited and decreases slowlyover time, (4) a "dry" zone (where SG>0.9) evolves, continues toexpand (albeit slowly) with time, but its extent remains limited, and (5)the ice front surrounding the wet zone is self-sharpening. For a range ofinitial conditions investigated, evolution of the liquid water massoccurs at approximately the same rate, reaches roughly the same maximum,and occurs at about the same time (10 to 20 sols; 1 sol = 24.39hours).

  6. Influence of length of time to diagnosis and treatment on the survival of children with acute lymphoblastic leukemia: a population-based study.

    PubMed

    Baker, Jillian M; To, Teresa; Beyene, Joseph; Zagorski, Brandon; Greenberg, Mark L; Sung, Lillian

    2014-02-01

    The objectives were to describe times to diagnosis and initiation of treatment in pediatric ALL in Ontario from 1997 to 2007, and to measure their impact on OS and EFS. In 1000 children, the median times to diagnosis and treatment were both 1 day (IQR = 1-2). Those who began treatment >3 days after diagnosis had inferior OS (AHR = 2.49; 95% CI = 1.40-4.43; p = 0.002), and inferior EFS (AHR = 1.73; 95% CI = 1.01-2.96; p = 0.047) compared to those who began treatment ≤ 3 days after diagnosis. There was no statistically significant relationship between time to diagnosis and survival. Longer time to treatment was associated with worse survival in pediatric ALL; reasons for this relationship may be multi-factorial.

  7. Determining Ductile Fracture Toughness in Metals

    SciTech Connect

    Chen, Xiang; Nanstad, Randy K; Sokolov, Mikhail A; Manneschmidt, Eric T

    2014-01-01

    Ductile fracture toughness determination, such as the J-integral versus crack growth resistance (J-R) curve, is a useful tool for evaluating material structural integrity in the presence of pre-existing defects. The J-R curve represents a way to calculate the work (energy) per unit fracture surface area needed to drive the crack growth. A typical J-R curve is shown in Fig. 1 from which the material fracture toughness near the initiation of stable crack growth (Jq) can be derived. In addition, tearing modulus (TR), representing the material resistance to stable crack growth, can be calculated based on the slope of the J-R curve between two exclusion lines (red dashed lines in Fig. 1). Since the introduction of the J-R curve, extensive efforts have been continuously devoted to develop simplified and reliable methods for determining the material J-R curve. This article briefly reviews three widely-used J-R curve test methods in metals, i.e. elastic unloading compliance (EUC), normalization, and direct current potential drop (DCPD). The main difference in these methods relates to the determination of the crack size. More details of performing the J-R curve determination can be found in ASTM standard E1820-11.

  8. Evaluation of Fracture Toughness of Porous Ceramics

    NASA Astrophysics Data System (ADS)

    Sakaida, Yoshihisa; Tanaka, Keisuke

    The indentation fracture (IF) method, the single-edge precracked beam (SEPB) method, and the single-edge V-notched beam (SEVNB) method were applied to evaluate the fracture toughness of four kinds of porous ceramics of SiC, Al2O3 and Mg2Al4Si5O18 with porosity ranging from 37 to 43%. The microstructures of these materials were composed of ceramics grains, glassy grain boundaries and pores. Each grain was joined together with the glassy grain boundary phase. The IF and SEPB methods were not applicable because both precracks and indenter traces were not visible. On the other hand, the SEVNB method was applicable because the V-notch could be easily machined by grinding. In the case of the SEVNB method, the applied load versus back-face strain plots under four-point bending showed nonlinearity prior to the maximum load. The R-curve behavior was estimated from the compliance change of specimens. The fracture toughness of porous ceramics was smaller than that of dense ceramics, and increased with increasing crack extension. Since the stable crack predominantly propagated along glassy grain boundaries, the R-curve behavior depended on the loading rate and matrix grain size. The increment of the R-curve by grain bridging became larger for coarser-grain sized ceramics.

  9. Application of Survival Analysis to Study Timing and Probability of Outcome Attainment by a Community College Student Cohort

    ERIC Educational Resources Information Center

    Mourad, Roger; Hong, Ji-Hee

    2008-01-01

    This study applies competing risks survival analysis to describe outcome attainment for an entire cohort of students who first attended a Midwestern community college in the Fall Semester 2001. Outcome attainment included transfer to a four-year institution, degree/ certificate attainment from the community college under study, and transfer to a…

  10. Survival analysis and extrapolation modeling of time-to-event clinical trial data for economic evaluation: an alternative approach.

    PubMed

    Bagust, Adrian; Beale, Sophie

    2014-04-01

    A recent publication includes a review of survival extrapolation methods used in technology appraisals of treatments for advanced cancers. The author of the article also noted shortcomings and inconsistencies in the analytical methods used in appraisals. He then proposed a survival model selection process algorithm to guide modelers' choice of projective models for use in future appraisals. This article examines the proposed algorithm and highlights various shortcomings that involve questionable assumptions, including researchers' access to patient-level data, the relevance of proportional hazards modeling, and the appropriateness of standard probability functions for characterizing risk, which may mislead practitioners into employing biased structures for projecting limited data in decision models. An alternative paradigm is outlined. This paradigm is based on the primacy of the experimental data and adherence to the scientific method through hypothesis formulation and validation. Drawing on extensive experience of survival modeling and extrapolation in the United Kingdom, practical advice is presented on issues of importance when using data from clinical trials terminated without complete follow-up as a basis for survival extrapolation.

  11. Simulation Study of Estimators for the Survival Probability of a First Passage Time for a Semi-Markov Process Using Censored Data

    DTIC Science & Technology

    1988-09-01

    Finite state space semi-Markov process find application in many areas. Often interest centers on whether or not the process has hit a particular state before a time t. This thesis reports results of a simulation study of the small behavior for three estimators of the survival probability of a first passage time for a semi-Markov process using censored data. Keywords: Semi- Markov; Kaplan Meier estimator; Confidence interval ; Jackknife; Problem; Theses.

  12. p53 and bcl-2 expression in high-grade B-cell lymphomas: correlation with survival time.

    PubMed Central

    Piris, M. A.; Pezzella, F.; Martinez-Montero, J. C.; Orradre, J. L.; Villuendas, R.; Sanchez-Beato, M.; Cuena, R.; Cruz, M. A.; Martinez, B.; Pezella F [corrected to Pezzella, F. ].

    1994-01-01

    B-cell high-grade lymphomas are heterogeneous in terms of histology, clinical presentation, treatment response and prognosis. As bcl-2 and p53 gene deregulations are frequently involved in several types of lymphoid malignancies, we aimed our investigation at the study of the relation between bcl-2 and p53 expression and survival probability in a group of 119 patients with B-cell high-grade lymphoma. These were obtained from the Virgen de la Salud Hospital, Toledo, Spain (73 cases), John Radcliffe Hospital, Oxford, UK (31 cases), and the Istituto Nazionale dei Tumori, Milan, Italy (15 cases). The relation between bcl-2 protein expression and survival was small, depending on the primary localisation of the tumour (in lymph node of mucosae), and lacked a significant correlation with overall survival. In contrast with this, p53 expression was related to survival probability in our series, this relation being both significant and independent of histological diagnosis. p53-positive patients showed a sudden decrease in life expectancy in the first months after diagnosis. Multivariant regression analysis confirmed that the only parameters significantly related with survival were extranodal origin, which is associated with a better prognosis, and p53 expression, which indicates a poor prognosis. Simultaneous expression of bcl-2 and p53 was associated with a poorer prognosis than p53 alone. This is particularly significant for large B-cell lymphomas presenting in lymph nodes. The cumulative poor effect of both p53 and bcl-2 in large B-cell lymphomas, which is more significant in nodal tumours, could confirm the existence of a multistep genetic deregulation in non-Hodgkin's lymphoma. This indicates that the genetic mechanisms controlling apoptosis and their disregulation are critical steps in the progression of lymphomas. PMID:8297731

  13. Crack toughness evaluation of hot pressed and forged beryllium

    NASA Technical Reports Server (NTRS)

    Jones, M. H.; Bubsey, R. T.; Brown, W. F., Jr.

    1971-01-01

    Beryllium fracture toughness test specimens were fatigue cracked using reversed cycling with a compression load two to three times the tension load. In worked beryllium, textures may be produced which result in fatigue cracks that are out of plane with the starter notch. Specimens of hot pressed stock exhibited load displacement records which were nonlinear throughout their course. Fracture specimens of both hot pressed and forged stock showed essentially no reduction of thickness and the fracture surfaces were flat and normal to the load axis. However, the stress intensity factor at maximum load increased with decreasing thickness. Load-displacement and electric potential records for the hot pressed beryllium specimens exhibited several anomalies such as negative residual crack mouth displacements and a decrease in electrical potential with increasing load.

  14. 46 CFR 57.06-5 - Production toughness testing.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Production toughness testing. 57.06-5 Section 57.06-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Production Tests § 57.06-5 Production toughness testing. (a) In addition to the test specimens required...

  15. 46 CFR 57.06-5 - Production toughness testing.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Production toughness testing. 57.06-5 Section 57.06-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Production Tests § 57.06-5 Production toughness testing. (a) In addition to the test specimens required...

  16. 46 CFR 57.06-5 - Production toughness testing.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Production toughness testing. 57.06-5 Section 57.06-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Production Tests § 57.06-5 Production toughness testing. (a) In addition to the test specimens required...

  17. 46 CFR 57.06-5 - Production toughness testing.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Production toughness testing. 57.06-5 Section 57.06-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Production Tests § 57.06-5 Production toughness testing. (a) In addition to the test specimens required...

  18. US EPA, Pesticide Product Label, TOUGH STAIN REMOVING ...

    EPA Pesticide Factsheets

    2011-04-21

    ... 1i~~~~~M~T"~C~H~~~~R~I~NO~L~~O~~~~~iil i _L~=_===7 USE COMET ~ ~ FOR THESE TOUGH ~ ... t\\t'6\\\\$ , USE COMET FOR THESE TOUGH ...

  19. 46 CFR 57.06-5 - Production toughness testing.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Production toughness testing. 57.06-5 Section 57.06-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING WELDING AND BRAZING Production Tests § 57.06-5 Production toughness testing. (a) In addition to the test specimens required...

  20. Impact of on-site care, prehospital time, and level of in-hospital care on survival in severely injured patients.

    PubMed

    Sampalis, J S; Lavoie, A; Williams, J I; Mulder, D S; Kalina, M

    1993-02-01

    A sample of 360 severely injured patients was selected from a cohort of 8007 trauma victims followed prospectively from the time of injury to death or discharge. A case referent study was used to test the association between on-site care, total prehospital time, and level of care at the receiving hospital with short-term survival. Multiple logistic regression analyses showed that use of Advanced Life Support (ALS) at the scene was not associated with survival, whereas treatment at a level I compatible hospital was associated with a 38% reduction in the odds of dying, which approached statistical significance. Total prehospital time over 60 minutes was associated with a statistically significant adjusted relative odds of dying (OR = 3.0). The results of this study support the need for regionalization of trauma care and fail to show a benefit associated with ALS.

  1. How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks

    SciTech Connect

    Ritchie, Robert O; Koester, K. J.; Ager III, J. W.; Ritchie, R.O.

    2008-05-10

    Bone is more difficult to break than to split. Although this is well known, and many studies exist on the behavior of long cracks in bone, there is a need for data on the orientation-dependent crack-growth resistance behavior of human cortical bone which accurately assesses its toughness at appropriate size-scales. Here we use in-situ mechanical testing in the scanning electron microscope and x-ray computed tomography to examine how physiologically-pertinent short (<600 mu m) cracks propagate in both the transverse and longitudinal orientations in cortical bone, using both crack-deflection/twist mechanics and nonlinear-elastic fracture mechanics to determine crack-resistance curves. We find that after only 500 mu m of cracking, the driving force for crack propagation was more than five times higher in the transverse (breaking) direction than in the longitudinal (splitting) direction due to major crack deflections/twists principally at cement sheathes. Indeed, our results show that the true transverse toughness of cortical bone is far higher than previously reported. However, the toughness in the longitudinal orientation, where cracks tend to follow the cement lines, is quite low at these small crack sizes; it is only when cracks become several millimeters in length that bridging mechanisms can develop leading to the (larger-crack) toughnesses generally quoted for bone.

  2. Hydrogen embrittlement and fracture toughness of a titanium alloy with surface modification by hard coatings

    NASA Astrophysics Data System (ADS)

    Lee, S.-C.; Ho, W.-Y.; Huang, C.-C.; Meletis, E. I.; Liu, Y.

    1996-02-01

    The effect of hydrogen embrittlement on the fracture toughness of a titanium alloy with different surface modifications was investigated. Disk- shaped compact- tension specimens were first coated with different .hard films and then hydrogen charged by an electrochemical method. Glow discharge optical spectrometry (GDOS), scanning electron microscopy (SEM), and x- ray diffractometry (XRD) were applied to analyze the surface characteristics. The results revealed that fracture toughness of the as- received titanium alloy decreased with the increase of hydrogen charging time. Fracture toughness of the alloy after plasma nitriding or ion implantation, which produced a TiN x layer, decreased as well, but to a lesser extent after cathodic charging. The best result obtained was for the alloy coated with a CrN film where fracture toughness was sustained even after hydrogen charging for 144 h. Obviously, the CrN film acted as a better barrier to retard hydrogen permeation, but it was at the sacrifice of the CrN film itself.

  3. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels.

    PubMed

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-02-02

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400-450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0-1.2 GPa at room temperature, which is nearly 3-5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

  4. Effect of Powder Injection on the Interfacial Fracture Toughness of Plasma-Sprayed Zirconia

    NASA Astrophysics Data System (ADS)

    Okajima, Yoshifumi; Nakamura, Toshio; Sampath, Sanjay

    2013-03-01

    Adhesive strength of the plasma-sprayed thermal barrier coating is one of the most important parameters which influence their durability and reliability during service. While many methods exist to measure the adhesive strength, in general, they require cumbersome and time-consuming specimen preparation. Furthermore, considerations of the adhesion strength from the point-of-view of fracture toughness or for that matter, their systematic correlation to both processing variances are limited. Consequently, there is an opportunity to both simplify the measurement procedure and establish correlations among methods and linkages between processing parameters and interfacial fracture toughness. In this paper, we report results on adhesion strength of plasma-sprayed yttria-stabilized zirconia (YSZ) coating on aluminum substrates based on both interfacial indentation test (to measure interfacial fracture toughness) and the modified tensile adhesive test. Carrier gas flow for powder injection into the plasma torch was systematically varied to introduce variances in particle melting with concomitant impact on the measured adhesive strength. The results indicate the correlation between the particle melting index and the measured interfacial fracture toughness.

  5. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

    PubMed Central

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-01-01

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry. PMID:28150692

  6. Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

    NASA Astrophysics Data System (ADS)

    Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

    2017-02-01

    Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

  7. Laser notching ceramics for reliable fracture toughness testing

    DOE PAGES

    Barth, Holly D.; Elmer, John W.; Freeman, Dennis C.; ...

    2015-09-19

    A new method for notching ceramics was developed using a picosecond laser for fracture toughness testing of alumina samples. The test geometry incorporated a single-edge-V-notch that was notched using picosecond laser micromachining. This method has been used in the past for cutting ceramics, and is known to remove material with little to no thermal effect on the surrounding material matrix. This study showed that laser-assisted-machining for fracture toughness testing of ceramics was reliable, quick, and cost effective. In order to assess the laser notched single-edge-V-notch beam method, fracture toughness results were compared to results from other more traditional methods, specificallymore » surface-crack in flexure and the chevron notch bend tests. Lastly, the results showed that picosecond laser notching produced precise notches in post-failure measurements, and that the measured fracture toughness results showed improved consistency compared to traditional fracture toughness methods.« less

  8. Laser notching ceramics for reliable fracture toughness testing

    SciTech Connect

    Barth, Holly D.; Elmer, John W.; Freeman, Dennis C.; Schaefer, Ronald D.; Derkach, Oleg; Gallegos, Gilbert F.

    2015-09-19

    A new method for notching ceramics was developed using a picosecond laser for fracture toughness testing of alumina samples. The test geometry incorporated a single-edge-V-notch that was notched using picosecond laser micromachining. This method has been used in the past for cutting ceramics, and is known to remove material with little to no thermal effect on the surrounding material matrix. This study showed that laser-assisted-machining for fracture toughness testing of ceramics was reliable, quick, and cost effective. In order to assess the laser notched single-edge-V-notch beam method, fracture toughness results were compared to results from other more traditional methods, specifically surface-crack in flexure and the chevron notch bend tests. Lastly, the results showed that picosecond laser notching produced precise notches in post-failure measurements, and that the measured fracture toughness results showed improved consistency compared to traditional fracture toughness methods.

  9. Extrusion process optimization for toughness in balloon films

    NASA Technical Reports Server (NTRS)

    Cantor, K. M.; Harrison, I. R.

    1993-01-01

    An experimental optimization process for blown film extrusion is described and examined in terms of the effects of the technique on the toughness of balloon films. The optimization technique by Cantor (1990) is employed which involves the identification of key process variables including screw speed, nip speed, bubble diameter, and frost-line height for analysis to optimize the merit function. The procedure is employed in the extrusion of a low-density polyethylene polymer, and the resulting optimized materials are toughness- and puncture-tested. Balloon toughness is optimized in the analytical relationship, and the process parameters are modified to attain optimal toughness. The film produced is shown to have an average toughness of 24.5 MPa which is a good value for this key property of balloon materials for high-altitude flights.

  10. Linking reproduction and survival can improve model estimates of vital rates derived from limited time-series counts of pinnipeds and other species.

    PubMed

    Battaile, Brian C; Trites, Andrew W

    2013-01-01

    We propose a method to model the physiological link between somatic survival and reproductive output that reduces the number of parameters that need to be estimated by models designed to determine combinations of birth and death rates that produce historic counts of animal populations. We applied our Reproduction and Somatic Survival Linked (RSSL) method to the population counts of three species of North Pacific pinnipeds (harbor seals, Phoca vitulina richardii (Gray, 1864); northern fur seals, Callorhinus ursinus (L., 1758); and Steller sea lions, Eumetopias jubatus (Schreber, 1776))--and found our model outperformed traditional models when fitting vital rates to common types of limited datasets, such as those from counts of pups and adults. However, our model did not perform as well when these basic counts of animals were augmented with additional observations of ratios of juveniles to total non-pups. In this case, the failure of the ratios to improve model performance may indicate that the relationship between survival and reproduction is redefined or disassociated as populations change over time or that the ratio of juveniles to total non-pups is not a meaningful index of vital rates. Overall, our RSSL models show advantages to linking survival and reproduction within models to estimate the vital rates of pinnipeds and other species that have limited time-series of counts.

  11. Effect of Polyprenyl Immunostimulant on the survival times of three cats with the dry form of feline infectious peritonitis.

    PubMed

    Legendre, Alfred M; Bartges, Joseph W

    2009-08-01

    Feline infectious peritonitis (FIP) is considered a fatal disease. Three cats with dry form FIP were treated with Polyprenyl Immunostimulant. Two of the three cats are still on treatment and are alive and well 2 years after diagnosis. The third cat survived 14 months but was treated for only 4.5 months. Further studies are necessary to assess the potential of the Polyprenyl Immunostimulant.

  12. 75 FR 72653 - Alternate Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-26

    ... RIN 3150-AI01 Alternate Fracture Toughness Requirements for Protection Against Pressurized Thermal... Regulations (10 CFR) part 50, section 61a to provide alternate fracture toughness requirements for...

  13. Mercury and drought along the lower Carson River, Nevada: IV. Snowy egret post-fledging dispersal, timing of migration and survival, 2002-2004.

    PubMed

    Henny, Charles J; Hill, Elwood F; Grove, Robert A; Chelgren, Nathan D; Haggerty, Patricia K

    2017-01-01

    This telemetry study is an extension of our 1997-2006 research on historical mercury contamination on snowy egrets (Egretta thula) up to ~ 20 days of age. Findings from initial studies at the mercury-contaminated Carson River colony at Lahontan Reservoir (LR) and a similar-sized reference (REF) colony on the Humboldt River included mercury-related physiological, biochemical, histopathological and reproductive effects up to ~20 days of age; with poor water years (2000-04), i.e., reduced prey availability, exacerbating effects. Herein, we compare timing of dispersal and migration at LR vs. REF, but the primary question now addressed is "whether survival of young mercury-exposed snowy egrets from LR would be further compromised beyond ~20 days of age? " Based upon telemetry signals until 90-110 days of age (including dead bird counts and survival rate estimates), we conclude that mercury did not further compromise survival. Dead bird counts and survival rate estimates included time in the colony when fed by adults, plus the critical period when young dispersed from the colony to forage independently. The extended drought during this 3-year study was most critical in 2002 when production of ~20d old egrets at LR was only 0.24 young/nest. In 2002, survival rates were low at both colonies and we documented the highest counts of dead egrets for both colonies. We suggest the losses in 2002 beyond 20 days of age were more a function of prey availability influenced by drought than exposure to mercury, especially at LR, because higher mercury concentrations, higher survival rates and fewer dead birds were documented at LR in 2003 when water conditions improved. Furthermore, total mercury (THg) in blood in 2003 was more than double 2002 (geometric mean, 3.39 vs 1.47µg/g wet weight (ww). This higher THg exposure at LR in 2003 was associated with a redistribution of parent and post-dispersal feeding activities upstream (where there was higher mercury from historic mining

  14. Mercury and drought along the lower Carson River, Nevada: IV. Snowy egret post-fledging dispersal, timing of migration and survival, 2002–2004

    USGS Publications Warehouse

    Henny, Charles J.; Hill, Elwood F.; Grove, Robert A.; Chelgren, Nathan; Haggerty, Patricia K.

    2017-01-01

    This telemetry study is an extension of our 1997–2006 research on historical mercury contamination on snowy egrets (Egretta thula) up to ~ 20 days of age. Findings from initial studies at the mercury-contaminated Carson River colony at Lahontan Reservoir (LR) and a similar-sized reference (REF) colony on the Humboldt River included mercury-related physiological, biochemical, histopathological and reproductive effects up to ~20 days of age; with poor water years (2000–04), i.e., reduced prey availability, exacerbating effects. Herein, we compare timing of dispersal and migration at LR vs. REF, but the primary question now addressed is “whether survival of young mercury-exposed snowy egrets from LR would be further compromised beyond ~20 days of age? ” Based upon telemetry signals until 90–110 days of age (including dead bird counts and survival rate estimates), we conclude that mercury did not further compromise survival. Dead bird counts and survival rate estimates included time in the colony when fed by adults, plus the critical period when young dispersed from the colony to forage independently. The extended drought during this 3-year study was most critical in 2002 when production of ~20 d old egrets at LR was only 0.24 young/nest. In 2002, survival rates were low at both colonies and we documented the highest counts of dead egrets for both colonies. We suggest the losses in 2002 beyond 20 days of age were more a function of prey availability influenced by drought than exposure to mercury, especially at LR, because higher mercury concentrations, higher survival rates and fewer dead birds were documented at LR in 2003 when water conditions improved. Furthermore, total mercury (THg) in blood in 2003 was more than double 2002 (geometric mean, 3.39 vs 1.47 µg/g wet weight (ww). This higher THg exposure at LR in 2003 was associated with a redistribution of parent and post-dispersal feeding activities upstream (where there was higher mercury from historic

  15. Tough, processable simultaneous semi-interpenetrating polyimides

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1996-01-01

    A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance and mechanical performance, when compared to the commercial Thermid.RTM. materials. This simultaneous semi-IPN was prepared by mixing a thermosetting polyimide with a thermoplastic monomer precursor solution (NR-15082) and allowing them to react upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene endcapped polyimides which were previously inherently brittle and difficult to process.

  16. Development of tough, moisture resistant laminating resins

    NASA Technical Reports Server (NTRS)

    Brand, R. A.; Harrison, E. S.

    1982-01-01

    Tough, moisture resistant laminating resins for employment with graphite fibers were developed. The new laminating resins exhibited cost, handleability and processing characteristics equivalent to 394K (250 F) curing epoxies. The laminating resins were based on bisphenol A dicyanate and monofunctional cyanates with hydrophobic substituents. These resins sorb only small quantities of moisture at equilibrium (0.5% or less) with minimal glass transition temperature depression and represent an improvement over epoxies which sorb around 2% moisture at equilibrium. Toughening was accomplished by the precipitation of small diameter particles of butadiene nitrile rubber throughout the resin matrix. The rubber domains act as microcrack termini and energy dissipation sites, allowing increased stress accommodation prior to catastrophic failure. A unique blend of amine terminated butadiene nitrile elastomer (MW 2,000) and a high nitrile content butadiene nitrile rubber yielded the desired resin morphology.

  17. Fracture toughness for copper oxide superconductors

    DOEpatents

    Goretta, Kenneth C.; Kullberg, Marc L.

    1993-01-01

    An oxide-based strengthening and toughening agent, such as tetragonal Zro.sub.2 particles, has been added to copper oxide superconductors, such as superconducting YBa.sub.2 Cu.sub.3 O.sub.x (123) to improve its fracture toughness (K.sub.IC). A sol-gel coating which is non-reactive with the superconductor, such as Y.sub.2 BaCuO.sub.5 (211) on the ZrO.sub.2 particles minimized the deleterious reactions between the superconductor and the toughening agent dispersed therethrough. Addition of 20 mole percent ZrO.sub.2 coated with 211 yielded a 123 composite with a K.sub.IC of 4.5 MPa(m).sup.0.5.

  18. Fracture toughness for copper oxide superconductors

    DOEpatents

    Goretta, K.C.; Kullberg, M.L.

    1993-04-13

    An oxide-based strengthening and toughening agent, such as tetragonal ZrO[sub 2] particles, has been added to copper oxide superconductors, such as superconducting YBa[sub 2]Cu[sub 3]O[sub x] (123) to improve its fracture toughness (K[sub IC]). A sol-gel coating which is non-reactive with the superconductor, such as Y[sub 2]BaCuO[sub 5] (211) on the ZrO[sub 2] particles minimized the deleterious reactions between the superconductor and the toughening agent dispersed therethrough. Addition of 20 mole percent ZrO[sub 2] coated with 211 yielded a 123 composite with a K[sub IC] of 4.5 MPa(m)[sup 0.5].

  19. The loss of activating transcription factor 4 (ATF4) reduces bone toughness and fracture toughness.

    PubMed

    Makowski, Alexander J; Uppuganti, Sasidhar; Wadeer, Sandra A; Whitehead, Jack M; Rowland, Barbara J; Granke, Mathilde; Mahadevan-Jansen, Anita; Yang, Xiangli; Nyman, Jeffry S

    2014-05-01

    Even though age-related changes to bone tissue affecting fracture risk are well characterized, only a few matrix-related factors have been identified as important to maintaining fracture resistance. As a gene critical to osteoblast differentiation, activating transcription factor 4 (ATF4) is possibly one of these important factors. To test the hypothesis that the loss of ATF4 affects the fracture resistance of bone beyond bone mass and structure, we harvested bones from Atf4+/+ and Atf4-/- littermates at 8 and 20 weeks of age (n≥9 per group) for bone assessment across several length scales. From whole bone mechanical tests in bending, femurs from Atf4-/- mice were found to be brittle with reduced toughness and fracture toughness compared to femurs from Atf4+/+ mice. However, there were no differences in material strength and in tissue hardness, as determined by nanoindentation, between the genotypes, irrespective of age. Tissue mineral density of the cortex at the point of loading as determined by micro-computed tomography was also not significantly different. However, by analyzing local composition by Raman Spectroscopy (RS), bone tissue of Atf4-/- mice was found to have higher mineral to collagen ratio compared to wild-type tissue, primarily at 20 weeks of age. From RS analysis of intact femurs at 2 orthogonal orientations relative to the polarization axis of the laser, we also found that the organizational-sensitive peak ratio, ν1Phosphate per Amide I, changed to a greater extent upon bone rotation for Atf4-deficient tissue, implying bone matrix organization may contribute to the brittleness phenotype. Target genes of ATF4 activity are not only important to osteoblast differentiation but also in maintaining bone toughness and fracture toughness.

  20. The Loss of Activating Transcription Factor 4 (ATF4) Reduces Bone Toughness and Fracture Toughness

    PubMed Central

    Makowski, Alexander J.; Uppuganti, Sasidhar; Waader, Sandra A.; Whitehead, Jack M.; Rowland, Barbara J.; Granke, Mathilde; Mahadevan-Jansen, Anita; Yang, Xiangli; Nyman, Jeffry S.

    2014-01-01

    Even though age-related changes to bone tissue affecting fracture risk are well characterized, only a few matrix-related factors have been identified as important to maintaining fracture resistance. As a gene critical to osteoblast differentiation, activating transcription factor 4 (ATF4) is possibly one of the seimportant factors. To test the hypothesis that the loss of ATF4 affects the fracture resistance of bone beyond bone mass and structure, we harvested bones from Atf4+/+ and Atf4−/− littermates at 8 and 20 weeks of age (n≥9 per group) for bone assessment across several length scales. From whole bone mechanical tests in bending, femurs from Atf4−/− mice were found to be brittle with reduced toughness and fracture toughness compared to femurs from Atf4+/+ mice. However, there were no differences in material strength and in tissue hardness, as determined by nanoindentation, between the genotypes, irrespective age. Tissue mineral density of the cortex at the point of loading as determined by micro-computed tomography was also not significantly different. However, by analyzing local composition by Raman Spectroscopy (RS), bone tissue of Atf4−/− mice was found to have higher mineral to collagen ratio compared to wild-type tissue, primarily at 20 weeks of age. From RS analysis of intact femurs at 2 orthogonal orientations relative to the polarization axis of the laser, we also found that the organizational-sensitive peak ratio, ν1 Phosphate per Amide I, changed to a greater extent upon bone rotation for Atf4-deficient tissue, implying bone matrix organization may contribute to the brittleness phenotype. Target genes of ATF4 activity are not only important to osteoblast differentiation but also maintaining bone toughness and fracture toughness. PMID:24509412

  1. Duration-dependent effects of clinically relevant oral alendronate doses on cortical bone toughness in beagle dogs.

    PubMed

    Burr, David B; Liu, Ziyue; Allen, Matthew R

    2015-02-01

    Bisphosphonates (BPs) have been shown to significantly reduce bone toughness in vertebrae within one year when given at clinical doses to dogs. Although BPs also reduce toughness in the cortical bone when given at high doses, their effect on cortical bone material properties when given at clinical doses is less clear. In part, this may be due to the use of small sample sizes that were powered to demonstrate differences in bone mineral density rather than the bone's material properties. Our lab has conducted several studies in which dogs were treated with alendronate at a clinically relevant dose. The goal of this study was to examine these published and unpublished data collectively to determine whether there is a significant time-dependent effect of alendronate on toughness of the cortical bone. This analysis seemed particularly relevant given the recent occurrence of atypical femoral fractures in humans. Differences in the toughness of ribs taken from dogs derived from five separate experiments were measured. The dogs were orally administered saline (CON, 1ml/kg/day) or alendronate (ALN) at a clinical dose (0.2mg/kg/day). Treatment duration ranged from 3months to 3years. Groups were compared using ANOVA, and time trends analyzed with linear regression analysis. Linear regressions of the percent difference in toughness between CON and ALN at each time point revealed a significant reduction in toughness with longer exposure to ALN. The downward trend was primarily driven by a downward trend in post-yield toughness, whereas toughness in the pre-yield region was not changed relative to CON. These data suggest that a longer duration of treatment with clinical doses of ALN results in deterioration of cortical bone toughness in a time-dependent manner. As the duration of treatment is lengthened, the cortical bone exhibits increasingly brittle behavior. This may be important in assessing the role that long-term BP treatments play in the risk of atypical fractures of the

  2. A novel pillar indentation splitting test for measuring fracture toughness of thin ceramic coatings

    DOE PAGES

    Sebastiani, Marco; Johanns, K. E.; Herbert, Erik G.; ...

    2014-05-16

    Fracture toughness is an important material property that plays a role in determining the in-service mechanical performance and adhesion of thin ceramic films. Unfortunately, measuring thin film fracture toughness is affected by influences from the substrate and the large residual stresses that can exist in the films. In this paper, we explore a promising new technique that potentially overcomes these problems based on nanoindentation testing of micro-pillars produced by focused ion beam milling of the films. By making the pillar diameter approximately equal to its length, the residual stress in the pillar’s upper portion is almost fully relaxed, and whenmore » indented with a sharp Berkovich indenter, the pillars fracture by splitting at reproducible loads that are readily quantified by a sudden displacement excursion in the load displacement behavior. Cohesive finite element simulations are used to analyze and develop, for a given material, a simple relation between the critical load at failure, pillar radius, and fracture toughness. The main novel aspect of this work is that neither crack geometries nor crack sizes need to be measured post test. Furthermore, the residual stress can be measured at the same time with toughness, by comparing the indentation results from the stress-free pillars and the as-deposited film. The method is tested on three different hard coatings formed by physical vapor deposition: titanium nitride, chromium nitride, and a CrAlN/Si3N4 nanocomposite. Results compare well to independently measured values of fracture toughness for the three brittle films. The technique offers several benefits over existing methods.« less

  3. The influence of water removal on the strength and toughness of cortical bone

    PubMed Central

    Nyman, Jeffry S.; Roy, Anuradha; Shen, Xinmei; Acuna, Rae L.; Tyler, Jerrod H.; Wang, Xiaodu

    2007-01-01

    Although the effects of dehydration on the mechanical behavior of cortical bone are known, the underlying mechanisms for such effects are not clear. We hypothesize that the interactions of water with the collagen and mineral phases each have a unique influence on mechanical behavior. To study this, strength, toughness, and stiffness were measured with three-point bend specimens made from the mid-diaphysis of human cadaveric femurs and divided into six test groups: control (hydrated), drying in a vacuum oven at room temperature (21 °C) for 30 min and at 21, 50, 70, or 110 °C for 4 h. The experimental data indicated that water loss significantly increased with each increase in drying condition. Bone strength increased with a 5% loss of water by weight, which was caused by drying at 21 °C for 4 h. With water loss exceeding 9%, caused by higher drying temperatures (≥70 °C), strength actually decreased. Drying at 21 °C (irrespective of time in vacuum) significantly decreased bone toughness through a loss of plasticity. However, drying at 70 °C and above caused toughness to decrease through decreases in strength and fracture strain. Stiffness linearly increased with an increase in water loss. From an energy perspective, the water–mineral interaction is removed at higher temperatures than the water–collagen interaction. Therefore, we speculate that loss of water in the collagen phase decreases the toughness of bone, whereas loss of water associated with the mineral phase decreases both bone strength and toughness. PMID:16488231

  4. A novel pillar indentation splitting test for measuring fracture toughness of thin ceramic coatings

    SciTech Connect

    Sebastiani, Marco; Johanns, K. E.; Herbert, Erik G.; Carassiti, Fabio; Pharr, George Mathews

    2014-05-16

    Fracture toughness is an important material property that plays a role in determining the in-service mechanical performance and adhesion of thin ceramic films. Unfortunately, measuring thin film fracture toughness is affected by influences from the substrate and the large residual stresses that can exist in the films. In this paper, we explore a promising new technique that potentially overcomes these problems based on nanoindentation testing of micro-pillars produced by focused ion beam milling of the films. By making the pillar diameter approximately equal to its length, the residual stress in the pillar’s upper portion is almost fully relaxed, and when indented with a sharp Berkovich indenter, the pillars fracture by splitting at reproducible loads that are readily quantified by a sudden displacement excursion in the load displacement behavior. Cohesive finite element simulations are used to analyze and develop, for a given material, a simple relation between the critical load at failure, pillar radius, and fracture toughness. The main novel aspect of this work is that neither crack geometries nor crack sizes need to be measured post test. Furthermore, the residual stress can be measured at the same time with toughness, by comparing the indentation results from the stress-free pillars and the as-deposited film. The method is tested on three different hard coatings formed by physical vapor deposition: titanium nitride, chromium nitride, and a CrAlN/Si3N4 nanocomposite. Results compare well to independently measured values of fracture toughness for the three brittle films. The technique offers several benefits over existing methods.

  5. Abundance, Timing of Migration, and Egg-to-Smolt Survival of Juvenile Chum Salmon, Kwethluk River, Alaska, 2007 and 2008

    USGS Publications Warehouse

    Burril, Sean E.; Zimmerman, Christian E.; Finn, James E.; ,; Gillikin, Daniel; ,

    2010-01-01

    To better understand and partition mortality among life stages of chum salmon (Oncorhynchus keta), we used inclined-plane traps to monitor the migration of juveniles in the Kwethluk River, Alaska in 2007 and 2008. The migration of juvenile chum salmon peaked in mid-May and catch rates were greatest when water levels were rising. Movement of chum salmon was diurnal with highest catch rates occurring during the hours of low light (that is, 22:00 to 10:00). Trap efficiency ranged from 0.37 to 4.04 percent (overall efficiency = 1.94 percent). Total abundance of juvenile chum salmon was estimated to be 2.0 million fish in 2007 and 2.9 million fish in 2008. On the basis of the estimate of chum salmon females passing the Kwethluk River weir and age-specific fecundity, we estimated the potential egg deposition (PED) upstream of the weir and trapping site. Egg-to-smolt survival, calculated by dividing the estimate of juvenile chum salmon emigrating past the weir site by the estimate of PED, was 4.6 percent in 2007 and 5.2 percent in 2008. In addition to chum salmon, Chinook salmon O. tshawytscha), coho salmon (O. kisutch), sockeye salmon (O. nerka), and pink salmon (O. gorbuscha), as well as ten other fish species, were captured in the traps. As with chum salmon, catch of these species increased during periods of increasing discharge and peaked during hours of low light. This study successfully determined the characteristics of juvenile salmon migrations and estimated egg-to-smolt survival for chum salmon. This is the first estimate of survival for any juvenile salmon in the Arctic-Yukon-Kuskokwim region of Alaska and demonstrates an approach that can help to partition mortality between freshwater and marine life stages, information critical to understanding the dynamics of salmon in this region.

  6. Aging effects on the fracture toughness of SiC whisker reinforced 2XXX aluminum alloys

    NASA Technical Reports Server (NTRS)

    Ratnaparkhi, P. L.; Rack, H. J.

    1989-01-01

    The effect of aging (at 150 C) time on the fracture toughness behavior of a 2XXX alloy (Al-3.55Cu-1.29Mg-0.01Fe-trace Mn) reinforced with 5 vol pct F-8 SiC whiskers was investigated by measuring hardness and electrical conductivity followed by fracture toughness tests on center-cracked specimens. The ageing time-hardening response plots showed that, independent of whisker orientation, the initial rapid increase in hardness was followed by a more gradual increase, with a broad hardness peak between 32 and 128 hrs of aging. Coincident with the hardness changes, the electrical conductivity initially decreased, reached a minimum, and then increased at aging times beyond 32 hrs. Examination by SEM indicated that the initial increase in hardness and decrease in conductivity was due to the GPB zone formation, while the subsequent increase in electrical conductivity and decrease in hardness (overaging) was due to S nucleation and growth.

  7. Effect of minor reactive metal additions on fracture toughness of iron: 12-percent nickel alloy at-196 deg and 25 deg C

    NASA Technical Reports Server (NTRS)

    Witzke, W. R.; Stephens, J. R.

    1976-01-01

    The slow bend precracked Charpy fracture toughness and tensile behavior of arc-melted and hot-rolled Fe-12Ni alloys containing up to 4 atomic percent reactive metal additions were determined at -196 C and 25 C after water quenching from three annealing temperatures. The fracture toughness of Fe-12Ni at -196 C was improved by small amounts of Al, Ce, Hf, La, Nb, Ta, Ti, V, Y, and Zr, but not by Si. Cryogenic toughness was improved up to 7.5 times that of binary Fe-12Ni and varied with the reactive metal, its concentration, and the annealing temperature.

  8. THE EFFECTS OF HYDROGEN, TRITIUM, AND HEAT TREATMENT ON THE DEFORMATION AND FRACTURE TOUGHNESS PROPERTIES OF STAINLESS STEEL

    SciTech Connect

    Morgan, M.; Tosten, M.; Chapman, G.

    2013-09-06

    The deformation and fracture toughness properties of forged stainless steels pre-charged with tritium were compared to the deformation and fracture toughness properties of the same steels heat treated at 773 K or 873 K and precharged with hydrogen. Forged stainless steels pre-charged with tritium exhibit an aging effect: Fracture toughness values decrease with aging time after precharging because of the increase in concentration of helium from tritium decay. This study shows that forged stainless steels given a prior heat treatment and then pre-charged with hydrogen also exhibit an aging effect: Fracture toughness values decrease with increasing time at temperature. A microstructural analysis showed that the fracture toughness reduction in the heat-treated steels was due to patches of recrystallized grains that form within the forged matrix during the heat treatment. The combination of hydrogen and the patches of recrystallized grains resulted in more deformation twinning. Heavy deformation twinning on multiple slip planes was typical for the hydrogen-charged samples; whereas, in the non-charged samples, less twinning was observed and was generally limited to one slip plane. Similar effects occur in tritium pre-charged steels, but the deformation twinning is brought on by the hardening associated with decay helium bubbles in the microstructure.

  9. Tritium Effects on Fracture Toughness of Stainless Steel Weldments

    SciTech Connect

    MORGAN, MICHAEL; CHAPMAN, G. K.; TOSTEN, M. H.; WEST, S. L.

    2005-05-12

    The effects of tritium on the fracture toughness properties of Type 304L and Type 21-6-9 stainless steel weldments were measured. Weldments were tritium-charged-and-aged and then tested in order to measure the effect of the increasing decay helium content on toughness. The results were compared to uncharged and hydrogen-charged samples. For unexposed weldments having 8-12 volume percent retained delta ferrite, fracture toughness was higher than base metal toughness. At higher levels of weld ferrite, the fracture toughness decreased to values below that of the base metal. Hydrogen-charged and tritium-charged weldments had lower toughness values than similarly charged base metals and toughness decreased further with increasing weld ferrite content. The effect of decay helium content was inconclusive because of tritium off-gassing losses during handling, storage and testing. Fracture modes were dominated by the dimpled rupture process in unexposed weldments. In hydrogen and tritium-exposed weldments, the fracture modes depended on the weld ferrite content. At high ferrite contents, hydrogen-induced transgranular fracture of the weld ferrite phase was observed.

  10. Kidney pathology and parasite intensity in rainbow trout Oncorhynchus mykiss surviving proliferative kidney disease: time course and influence of temperature.

    PubMed

    Schmidt-Posthaus, Heike; Bettge, Kathrin; Forster, Ursula; Segner, Helmut; Wahli, Thomas

    2012-01-24

    Proliferative kidney disease (PKD) is an endoparasitic disease of salmonids caused by the myxozoan parasite Tetracapsuloides bryosalmonae. We recently described the development of the disease from initial infection until manifestation of clinical disease signs in rainbow trout held at 2 water temperatures, 12 and 18°C. The aim of the present study is to investigate whether (1) infected fish surviving the clinical phase would recover from renal pathological changes, (2) whether they would be able to reduce the parasite load in the kidneys, and (3) whether water temperatures would influence renal recovery and parasite clearance. At 18°C, fish showed a gradual recovery of normal kidney morphology which was associated with a decline in parasite numbers and infection prevalence. Fish kept at 12°C initially showed an enhancement of kidney lesions before recovery of normal kidney morphology took place. The decrease in renal parasite load was retarded compared to 18°C. The results from the present study provide evidence that rainbow trout surviving the clinical phase of PKD are able to (1) fully restore renal structure, and (2) significantly reduce renal parasite loads, although 100% clearance was not achieved within the experimental period of this study. Water temperature influences the rate but not the outcome of the recovery process.

  11. Crack-shape effects for indentation fracture toughness measurements

    SciTech Connect

    Smith, S.M.; Scattergood, R.O. . Dept. of Materials Science and Engineering)

    1992-02-01

    Various methods to measure fracture toughness using indentation precracks were compared using soda-lime glass as a test material. In situ measurements of crack size as a function of applied stress allow both the toughness K[sub c] and the residual-stress factor [chi] to be independently determined. Analysis of the data showed that stress intensity factors based on classical half-penny crack shapes overestimate toughness values and produce an apparent R-curve effect. This is due to a constraint on crack shape imposed by primary lateral cracks in soda-lime glass. Models based on elliptical cracks were developed to account for the crack-shape effects.

  12. Fracture toughness of oxide-dispersion strengthened copper

    SciTech Connect

    Alexander, D.J.

    1996-10-01

    The fracture toughness of an oxide-dispersion strengthened copper alloy AL-15 has been examined at room temperature and 250{degrees}C, in air and in vacuum (< 10{sup {minus}6} torr). Increasing test temperature causes a significant decrease in the fracture toughness of this material, in either air or vacuum environments. In addition, specimens oriented in the T-L orientation (crack growth parallel to the extrusion direction) show significantly lower toughness than those in the L-T orientation (crack growth perpendicular to the extrusion direction).

  13. Marine Structural Steel Toughness Data Bank. Volume 2

    DTIC Science & Technology

    1991-01-01

    A514, HY80 and HY100 containing primarily Ni, Cr, Mn and Mo; * High strength, low alloy steel A710 and HSLA 80 containing primarily Cu, Ni, Cr and Mo...S SC 3:52 MARNE STRUCTURAL STEEL TOUGHNESS DATA, BANK,’ (Vol ’ue2 u- t. 2). DTI A ELCT ~k, Ibis doc tuent has been appcove4 for public release an d...Structures SSC-352 August 28, 1991 SR-1311 MARINE STRUCTURAL STEEL TOUGHNESS DATA BANK A substantial amount of toughness data for commonly used marine

  14. Graphite/PMR polyimide composites with improved toughness

    NASA Technical Reports Server (NTRS)

    Vannucci, R. D.; Bowles, K. J.

    1985-01-01

    The toughness of composites made with modified PMR (polymerization of monomer reactants) polyimides and Celion 6000 graphite fibers was studied. Various types/levels of monomer reactants containing flexible links were incorporated into PMR resin compositions used to prepare composites. The composites were evaluated for toughness using instrumented drop weight and 10 deg off axis tensile tests at room temperature, and for strength using flexure and short beam shear tests at room temperature and at elevated temperature. The effect of resin composition on composite processability, thermo-oxidative stability, toughness and mechanical properties are discussed.

  15. Bioinspired fully physically cross-linked double network hydrogels with a robust, tough and self-healing structure.

    PubMed

    Sabzi, Mohammad; Samadi, Navid; Abbasi, Farhang; Mahdavinia, Gholam Reza; Babaahmadi, Masoud

    2017-05-01

    The conventional covalently cross-linked double network (DN) hydrogels with high stiffness often show low toughness and self-healing property due to the irreversible bond breakages in their networks. Therefore, scarcity of hydrogels that possess simultaneous features of stiffness, toughness, and autonomous self-healing properties at the same time remains a great challenge and seriously limits their biomedical applications. While, many natural materials acquire these features from their dynamic sacrificial bonds. Inspired by biomaterials, herein we propose a novel strategy to design stiff, tough and self-healing DN gels by substitution of both covalently cross-linked networks with strong, dynamic hydrogen bond cross-linked networks. The prepared fully physically cross-linked DN gels composed of strong agar biopolymer gel as the first network and tough polyvinyl alcohol (PVA) biopolymer gel as the second network. The DN gels demonstrated multiple-energy dissipating mechanisms with a high modulus up to 2200kPa, toughness up to 2111kJm(-3), and ability to self-heal quickly and autonomously with regaining 67% of original strength only after 10min. The developed DN gels will open a new avenue to hydrogel research and holds high potential for diverse biomedical applications, such as scaffold, cartilage, tendon and muscle.

  16. Improved adhesive strength and toughness of polyvinyl acetate glue on addition of small quantities of graphene.

    PubMed

    Khan, Umar; May, Peter; Porwal, Harshit; Nawaz, Khalid; Coleman, Jonathan N

    2013-02-01

    We have prepared composites of polyvinyl acetate (PVAc) reinforced with solution exfoliated graphene. We observe a 50% increase in stiffness and a 100% increase in tensile strength on addition of 0.1 vol % graphene compared to the pristine polymer. As PVAc is commonly used commercially as a glue, we have tested such composites as adhesives. The adhesive strength and toughness of the composites were up to 4 and 7 times higher, respectively, than the pristine polymer.

  17. Obesity May Make Rheumatoid Arthritis Tough to Spot, Track

    MedlinePlus

    ... gov/news/fullstory_164558.html Obesity May Make Rheumatoid Arthritis Tough to Spot, Track Inflammation from excess weight ... HealthDay News) -- Blood tests to diagnose and monitor rheumatoid arthritis may be thrown off by obesity in women, ...

  18. Hold That Pose: Yoga May Ease Tough Depression

    MedlinePlus

    ... html Hold That Pose: Yoga May Ease Tough Depression Study finds weekly sessions, plus deep breathing, helped ... the doctor ordered when it comes to beating depression, new research suggests. Researchers found that weekly sessions ...

  19. Aircraft Survivability. Summer 2011

    DTIC Science & Technology

    2011-01-01

    Survivability Program Office SUMMER 2011 craShworthineSS & personnel casualties Report Documentation Page Form ApprovedOMB No. 0704-0188 Public...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Aircraft Survivability is published three times a year by the Joint...and stroking seats. The knowledge gained from studying Vietnam crash data was consolidated into the Crash Survival Design Guide (CSDG), which

  20. Prostate-specific antigen doubling time predicts clinical outcome and survival in prostate cancer patients treated with combined radiation and hormone therapy

    SciTech Connect

    Lee, Andrew K. . E-mail: aklee@mdanderson.org; Levy, Larry B.; Cheung, Rex; Kuban, Deborah

    2005-10-01

    Purpose: To determine whether prostate-specific antigen (PSA) doubling time predicts clinical outcomes in patients with prostate cancer that has been treated with combined radiation and hormone therapy. Methods and Materials: We reviewed the medical records of 621 men with nonmetastatic prostate cancer treated with radiation therapy and hormone therapy between 1989 and 2003. 'Any' clinical failure was defined as any distant, nodal, or local failure, or the use of salvage therapy. 'True' clinical failure was defined as any distant, nodal, or local failure. PSA doubling time was calculated by using the log PSA values from patients with a PSA failure as defined by the American Society of Therapeutic Radiology Oncology consensus statement. One hundred thirty-seven men were at intermediate risk for PSA failure (as determined by T2b, Gleason score of 7, or PSA 10.1-0 ng/mL) and 484 men were at high risk for failure (T2c-4; Gleason 8-10; or PSA >20 ng/mL). Pretreatment PSA value, Gleason score, tumor stage, timing and duration of hormone therapy, radiation therapy dose, and PSA doubling time were analyzed for any associations with time to clinical failure by using Cox regression analysis. Estimates of survival were calculated by using the Kaplan-Meier method. Pairwise comparisons were made by using the log-rank test. Results: Sixty-two men experienced any clinical failure, and 22 men experienced true clinical failure. Multivariate analysis revealed that pretreatment PSA (p = 0.013), Gleason score (p = 0.0019), and a PSA doubling time (PSADT) {<=}8 months (p < 0.001) were independently associated with time to any clinical failure. Tumor stage, hormone therapy timing, hormone therapy duration, and radiation therapy dose were not statistically significant on multivariate or univariate analysis. Only hormone therapy duration (p 0.008) and PSADT {<=}8 months (<0.001) were significantly associated with time to true clinical failure. The estimated 5-year rate of any clinical

  1. The shear fracture toughness, KIIc, of graphite

    DOE PAGES

    Burchell, Timothy D.; Erdman, III, Donald L.

    2015-11-05

    In this study, the critical shear stress intensity factor, KIIc, here-in referred to as the shear fracture toughness, KIIc (MPa m), of two grades of graphite are reported. The range of specimen volumes was selected to elucidate any specimen size effect, but smaller volume specimen tests were largely unsuccessful, shear failure did not occur between the notches as expected. This was probably due to the specimen geometry causing the shear fracture stress to exceed the compressive failure stress. In subsequent testing the specimen geometry was altered to reduce the compressive footprint and the notches (slits) made deeper to reduce themore » specimen's ligament length. Additionally, we added the collection of Acoustic Emission (AE) during testing to assist with the identification of the shear fracture load. The means of KIIc from large specimens for PCEA and NBG-18 are 2.26 MPa m with an SD of 0.37 MPa m and 2.20 MPa m with an SD of 0.53 MPa m, respectively. The value of KIIc for both graphite grades was similar, although the scatter was large. In this work we found the ratio of KIIc/KIc ≈ 1.6. .« less

  2. Cool Tools, Tough Times: Maintaining a Focus on Technology Infusion

    ERIC Educational Resources Information Center

    Britten, Jody S.; Clausen, Jon M.

    2009-01-01

    Nationwide the effects of the current economic situation are trickling down to impact our schools. School transportation options are narrowing, the housing market is impacting property taxes, and efforts in technology are at a stand still (Bobkoff, 2009; Hopkinson, 2009; Mummolo, 2008). Simultaneously there is a need for schools to meet society's…

  3. Six Preparedness Strategies for Librarians in Tough Economic Times

    ERIC Educational Resources Information Center

    MacKellar, Pamela

    2010-01-01

    It is no secret that library budgets are in a downward spiral like the rest of the economy. The recent annual budget survey by the "Library Journal" indicates that per capita funding for libraries will decline 1.6%, and total library budgets will be reduced by 2.6% in FY 2010. Librarians are all too familiar with this bad news, and some of them…

  4. Negotiating in School Districts when Times Are Tough

    ERIC Educational Resources Information Center

    Dolph, David

    2012-01-01

    When the economy is depressed, resources are limited, mandates are overwhelming, and the organizational climate in the district is souring, education leaders and teachers union officials often brace themselves for contentious negotiations. Poor economic conditions affect the district's ability to offer raises, maintain current benefit levels, and…

  5. Advancing the Public Value Movement: Sustaining Extension during Tough Times

    ERIC Educational Resources Information Center

    Franz, Nancy K.

    2011-01-01

    Extension must more fully and adeptly embrace the public value movement to be sustainable as a publicly funded organization, or our demise as an organization will continue. The public value steps outlined here and piloted with several Extension systems and national work groups can be informative for others interested in capturing and sharing the…

  6. Tough Times Push More Small Colleges to Join Forces

    ERIC Educational Resources Information Center

    Carlson, Scott

    2013-01-01

    The author reports on how colleges could work together more closely in areas like the library, the colleges' technology infrastructure, human resources and payroll, and, ultimately, their academic programs. Higher education has some famous collaborations--the best-known among them are the Claremont Colleges, where seven institutions, each with a…

  7. Being Relevant in Tough Times: TRIUMF's Five-Year Plan

    ScienceCinema

    Tim, Mayer [TRIUMF

    2016-07-12

    Perhaps better known to the international community than its own neighbors, TRIUMF is Canada's national laboratory for particle and nuclear physics.  Working with the Canadian scientific community, TRIUMF has formulated a new vision to transform the laboratory and deliver a whole new level of performance and impact.  The plan capitalizes on platform technologies (superconducting RF cavities for accelerator physics and radiotracers in nuclear medicine) and exploits Canada's role in ATLAS and the LHC.  I will describe the key elements of the plan and discuss the science-policy landscape in which TRIUMF must make its case.

  8. Engineering of High-Toughness Carbon Nanotubes Hierarchically Laminated Composites

    DTIC Science & Technology

    2012-01-27

    REPORT TYPE Final 3. DATES COVERED (From - To) Jul-10 - Jul-11 4. TITLE AND SUBTITLE Program Title: ENGINEERING OF HIGH-TOUGHNESS CARBON NANOTUBES ...LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON Program Title: ENGINEERING OF HIGH-TOUGHNESS CARBON NANOTUBES ...Ashby plots can be attained (Fig. 2B). 5. New doping method of carbon nanotubes was developed. Funding Profile: (Give the fiscal year funding

  9. Critical Fracture Toughness Measurements of an Antarctic Ice Core

    NASA Astrophysics Data System (ADS)

    Christmann, Julia; Müller, Ralf; Webber, Kyle; Isaia, Daniel; Schader, Florian; Kippstuhl, Sepp; Freitag, Johannes; Humbert, Angelika

    2014-05-01

    Fracture toughness is a material parameter describing the resistance of a pre-existing defect in a body to further crack extension. The fracture toughness of glacial ice as a function of density is important for modeling efforts aspire to predict calving behavior. In the presented experiments this fracture toughness is measured using an ice core from Kohnen Station, Dronning Maud Land, Antarctica. The samples were sawed in an ice lab at the Alfred Wegener Institute in Bremerhaven at -20°C and had the dimensions of standard test samples with thickness 14 mm, width 28 mm and length 126 mm. The samples originate from a depth of 94.6 m to 96 m. The grain size of the samples was also identified. The grain size was found to be rather uniform. The critical fracture toughness is determined in a four-point bending approach using single edge V-notch beam samples. The initial notch length was around 2.5 mm and was prepared using a drilling machine. The experimental setup was designed at the Institute of Materials Science at Darmstadt. In this setup the force increases linearly, until the maximum force is reached, where the specific sample fractures. This procedure was done in an ice lab with a temperature of -15°C. The equations to calculate the fracture toughness for pure bending are derived from an elastic stress analysis and are given as a standard test method to detect the fracture toughness. An X-ray computer tomography (CT scanner) was used to determine the ice core densities. The tests cover densities from 843 kg m-3 to 871 kg m-3. Thereby the influence of the fracture toughness on the density was analyzed and compared to previous investigations of this material parameter. Finally the dependence of the measured toughness on thickness, width, and position in the core cross-section was investigated.

  10. Fracture toughness of advanced ceramics at room temperature

    NASA Technical Reports Server (NTRS)

    Quinn, George D.; Salem, Jonathan; Bar-On, Isa; Cho, Kyu; Foley, Michael; Fang, HO

    1992-01-01

    Results of round-robin fracture toughness tests on advanced ceramics are reported. A gas-pressure silicon nitride and a zirconia-toughened alumina were tested using three test methods: indentation fracture, indentation strength, and single-edge precracked beam. The latter two methods have produced consistent results. The interpretation of fracture toughness test results for the zirconia alumina composite is shown to be complicated by R-curve and environmentally assisted crack growth phenomena.

  11. Fracture toughness of woven kenaf fibre reinforced composites

    NASA Astrophysics Data System (ADS)

    Ismail, AE; Masran, SH; Jamian, S.; Kamarudin, KA; Mohd Nor, MK; Muhd Nor, NH; Mohd Tobi, AL; Awang, MK

    2016-11-01

    This paper presents the role of fibre orientations on the woven-type kenaf fibre reinforced composites. According to literature survey, lack of information regarding to the fracture toughness of woven kenaf fibre reinforced composites. Fracture toughness tests were performed using ASTM D5045. Four fibre orientations were used such as 0/15/0/-15/0, 0/30/0/-30/0, 0/45/0/-45/0 and 0/90/0/-90/0 and on the other hand virgin polyester and unidirectional fibre reinforced composites were also used for comparisons. Based on the experimental works, woven-typed composites produced lower fracture toughness compared with the unidirectional fiber composite. Fracture toughness obtained from different fibre orientations composites are almost identical however 0/30/0/-30/0 and 0/90/0/-90/0 produced higher toughness relative with others. Fracture mechanisms revealed that as expected the fibres aligned along the stress direction capable to sustain better mechanical deformation and therefore producing higher fracture toughness.

  12. Tough bonding of hydrogels to diverse non-porous surfaces

    NASA Astrophysics Data System (ADS)

    Yuk, Hyunwoo; Zhang, Teng; Lin, Shaoting; Parada, German Alberto; Zhao, Xuanhe

    2016-02-01

    In many animals, the bonding of tendon and cartilage to bone is extremely tough (for example, interfacial toughness ~800 J m-2 refs ,), yet such tough interfaces have not been achieved between synthetic hydrogels and non-porous surfaces of engineered solids. Here, we report a strategy to design tough transparent and conductive bonding of synthetic hydrogels containing 90% water to non-porous surfaces of diverse solids, including glass, silicon, ceramics, titanium and aluminium. The design strategy is to anchor the long-chain polymer networks of tough hydrogels covalently to non-porous solid surfaces, which can be achieved by the silanation of such surfaces. Compared with physical interactions, the chemical anchorage results in a higher intrinsic work of adhesion and in significant energy dissipation of bulk hydrogel during detachment, which lead to interfacial toughness values over 1,000 J m-2. We also demonstrate applications of robust hydrogel-solid hybrids, including hydrogel superglues, mechanically protective hydrogel coatings, hydrogel joints for robotic structures and robust hydrogel-metal conductors.

  13. Clinical features, survival times and COX-1 and COX-2 expression in cats with transitional cell carcinoma of the urinary bladder treated with meloxicam.

    PubMed

    Bommer, Nicholas X; Hayes, Alison M; Scase, Timothy J; Gunn-Moore, Danièlle A

    2012-08-01

    Records of 11 cats with transitional cell carcinoma of the urinary bladder, which had been treated with meloxicam, were reviewed for signalment, duration of clinical signs prior to diagnosis, results of diagnostic imaging, whether or not concurrent surgery was performed and survival. Immunohistochemical expression of cyclo-oxygenase-1 (COX-1) and cyclo-oxygenase-2 (COX-2) was assessed in the tumours of seven cats. Tumour location varied greatly. The cats had a mean age of 13 years. Three cats had a previous diagnosis of feline idiopathic cystitis of up to 2008 days duration. Ten of the cats showed clinical improvement (reduction of haematuria and/or dysuria), with a mean survival time (MST) of 311 days (range 10-1064); 1-year survival of 50%. All seven bladders assessed for COX staining were COX-1 positive and five were COX-2 positive. The MST for the COX-2-positive cats was 123 days, the MST for the COX-2-negative cases was 375 days.

  14. Time to retire--time to die? A prospective cohort study of the effects of early retirement on long-term survival.

    PubMed

    Brockmann, Hilke; Müller, Rolf; Helmert, Uwe

    2009-07-01

    In a long-term prospective cohort study we try to assess selective and protective impacts of early retirement on life expectancy. The results are based on the members of a compulsory German health insurance fund (Gmünder Ersatzkasse). We analyzed 88,399 men and 41,276 women who retired between the ages of 50 and 65 from January 1990 to December 2004. Our main outcome measures are hazard ratios for death adjusted for age, sex, marital and socioeconomic status, year of observation, age at retirement, hospitalization, and form of retirement scheme. We found a significantly higher mortality risk among pensioners with reduced earning capacities than among old-age pensioners who either left the labor market between the ages of 56 and 60 or between 61 and 65. The youngest male and female pensioners who left the labor market between the ages of 51 and 55 because of their reduced earning capacity faced the highest mortality risk. But healthy people who retire early do not experience shorter long-term survival than those who retire late. On the contrary, if we take into consideration the amount of days spent in hospital during the last 2 years prior to retirement, early retirement in fact lowers mortality risks significantly by 12% for men and by 23% for women. Thus with respect to mortality, early retirement reflects both selective and protective processes. First of all, individuals with poor health and lower survival chances are filtered out of the labor market. However, healthy pensioners may be protected during retirement. For the former, early retirement is a necessity, for the latter it is an asset. Pension reformers should take health differentials into consideration when cutting back pension programs and increasing retirement age.

  15. Toughness of the Virunga mountain gorilla (Gorilla beringei beringei) diet across an altitudinal gradient.

    PubMed

    Glowacka, Halszka; McFarlin, Shannon C; Vogel, Erin R; Stoinski, Tara S; Ndagijimana, Felix; Tuyisingize, Deo; Mudakikwa, Antoine; Schwartz, Gary T

    2017-04-07

    The robust masticatory system of mountain gorillas is thought to have evolved for the comminution of tough vegetation, yet, compared to other primates, the toughness of the mountain gorilla diet is unremarkable. This may be a result of low plant toughness in the mountain gorilla environment or of mountain gorillas feeding selectively on low-toughness foods. The goal of this paper is to determine how the toughness of the mountain gorilla diet varies across their habitat, which spans a large altitudinal range, and whether there is a relationship between toughness and food selection by mountain gorillas. We collected data on the following variables to determine whether, and if so how, they change with altitude: leaf toughness of two plant species consumed by mountain gorillas, at every 100 m increase in altitude (2,600-3,700 m); toughness of consumed foods comprising over 85% of the gorilla diet across five vegetation zones; and toughness of unconsumed/infrequently consumed plant parts of those foods. Although leaf toughness increased with altitude, the toughness of the gorilla diet remained similar. There was a negative relationship between toughness and consumption frequency, and toughness was a better predictor of consumption frequency than plant frequency, biomass, and density. Consumed plant parts were less tough than unconsumed/infrequently consumed parts and toughness of the latter increased with altitude. Although it is unclear whether gorillas select food based on toughness or use toughness as a sensory cue to impart other plant properties (e.g., macronutrients, chemicals), our results that gorillas maintain a consistent low-toughness dietary profile across altitude, despite toughness increasing with altitude, suggest that the robust gorilla masticatory apparatus evolved for repetitive mastication of foods that are not high in toughness.

  16. The Impact of Alemtuzumab and Basiliximab Induction on Patient Survival and Time to Bronchiolitis Obliterans Syndrome in Double Lung Transplantation Recipients.

    PubMed

    Furuya, Y; Jayarajan, S N; Taghavi, S; Cordova, F C; Patel, N; Shiose, A; Leotta, E; Criner, G J; Guy, T S; Wheatley, G H; Kaiser, L R; Toyoda, Y

    2016-08-01

    We examined the effect of alemtuzumab and basiliximab induction therapy on patient survival and freedom from bronchiolitis obliterans syndrome (BOS) in double lung transplantation. The United Network for Organ Sharing database was reviewed for adult double lung transplant recipients from 2006 to 2013. The primary outcome was risk-adjusted all-cause mortality. Secondary outcomes included time to BOS. There were 6117 patients were identified, of whom 738 received alemtuzumab, 2804 received basiliximab, and 2575 received no induction. Alemtuzumab recipients had higher lung allocation scores compared with basiliximab and no-induction recipients (41.4 versus 37.9 versus 40.7, p < 0.001) and were more likely to require mechanical ventilation before to transplantation (21.7% versus 6.5% versus 6.2%, p < 0.001). Median survival was longer for alemtuzumab and basiliximab recipients compared with patients who received no induction (2321 versus 2352 versus 1967 days, p = 0.001). Alemtuzumab (hazard ratio 0.80, 95% confidence interval 0.67-0.95, p = 0.009) and basiliximab induction (0.88, 0.80-0.98, p = 0.015) were independently associated with survival on multivariate analysis. At 5 years, alemtuzumab recipients had a lower incidence of BOS (22.7% versus 55.4 versus 55.9%), and its use was independently associated with lower risk of developing BOS on multivariate analysis. While both induction therapies were associated with improved survival, patients who received alemtuzumab had greater median freedom from BOS.

  17. The anatomic pattern of biliary atresia identified at time of Kasai hepatoportoenterostomy and early postoperative clearance of jaundice are significant predictors of transplant-free survival

    PubMed Central

    Superina, Riccardo; Magee, John C.; Brandt, Mary L.; Healey, Patrick J.; Tiao, Greg; Ryckman, Fred; Karrer, Frederick M; Iyer, Kishore; Fecteau, Annie; West, Karen; Burns, R. Cartland; Flake, Alan; Lee, Hanmin; Lowell, Jeff A.; Dillon, Pat; Colombani, Paul; Ricketts, Richard; Li, Yun; Moore, Jeffrey; Wang, Kasper S.

    2012-01-01

    Objective The goals of this study were to describe the clinical and anatomic features of infants undergoing Kasai portoenterostomy (KPE) for biliary atresia (BA), and to examine associations between these parameters and outcomes. Methods Infants enrolled in the prospective Childhood Liver Disease Research and Education Network, who underwent KPE were studied. Patients enrolled in a blinded, interventional trial were excluded from survival analysis. Primary end-points were successful surgical drainage (total bilirubin less than 2 mg/dL within the first three months), transplant-free survival (Kaplan-Meier), and time to transplant/death (Cox regression). Results KPE was performed in 244 infants (54% female; mean age 65± 29 days). Transplant-free survival was 53.7% and 46.7% at 1 and 2 years post-KPE. The risk of transplant/death was significantly lower in the 45.6% of patients who achieved successful bile drainage within 3 months post-KPE (HR 0.08, p<0.001). The risk of transplant/death was increased in patients with porta hepatis atresia (Ohi Type II and III vs. Type I; HR 2.03, p=0.030), non-patent common bile duct (Ohi Subtype b, c, and d vs. a; HR 4.31, p=0.022), BA splenic malformation syndrome (HR 1.92, p=0.025), ascites > 20 ml (HR=1.90, p=0.0230), nodular liver appearance compared to firm (HR=1.61, p=0.008), and age at KPE ≥ 75 days (HR 1.73, p<0.002). Outcome was not associated with gestational age, gender, race, ethnicity, or extent of porta hepatis dissection. Conclusion Anatomic pattern of BA, BASM, presence of ascites and nodular liver appearance at KPE, and early postoperative jaundice clearance are significant predictors of transplant-free survival. PMID:21869674

  18. Fracture toughness of calcium-silicate-hydrate from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Bauchy, M.; Laubie, H.; Abdolhosseini Qomi, M. J.; Hoover, C. G.; Ulm, F.-J.; Pellenq, R. J.-M.

    2015-07-01

    Cement is the most widely used manufacturing material in the world and improving its toughness would allow for the design of slender infrastructure, requiring less material. To this end, we investigate by means of molecular dynamics simulations the fracture of calcium-silicate-hydrate (C-S-H), the binding phase of cement, responsible for its mechanical properties. For the first time, we report values of the fracture toughness, critical energy release rate, and surface energy of C-S-H grains. This allows us to discuss the brittleness of the material at the atomic scale. We show that, at this scale, C-S-H breaks in a ductile way, which prevents from using methods based on linear elastic fracture mechanics. Knowledge of the fracture properties of C-S-H at the nanoscale opens the way for an upscaling approach to the design of tougher cement.

  19. Mesenchymal stem cells increase skin graft survival time and up-regulate PD-L1 expression in splenocytes of mice.

    PubMed

    Moravej, Ali; Geramizadeh, Bita; Azarpira, Negar; Zarnani, Amir-Hassan; Yaghobi, Ramin; Kalani, Mehdi; Khosravi, Maryam; Kouhpayeh, Amin; Karimi, Mohammad-Hossein

    2017-02-01

    Recently, mesenchymal stem cells (MSCs) have gained considerable interests as hopeful therapeutic cells in transplantation due to their immunoregulatory functions. But exact mechanisms underlying MSCs immunoregulatory function is not fully understood. Herein, in addition to investigate the ability of MSCs to prolong graft survival time, the effects of them on the expression of PD-L1 and IDO immunomodulatory molecules in splenocytes of skin graft recipient mice was clarified. To achieve this goal, full-thickness skins were transplanted from C57BL/6 to BALB/c mice. MSCs were isolated from bone marrow of BALB/c mice and injected to the recipient mice. Skin graft survival was monitored daily to determine graft rejection time. On days 2, 5 and 10 post skin transplantation, serum cytokine levels and expression of PD-L1 and IDO mRNA and protein in the splenocytes of recipient mice were evaluated. The results showed that administration of MSCs prolonged skin graft survival time from 11 to 14 days. On days 2 and 5 post transplantation, splenocytes PD-L1 expression and IL-10 serum level in MSCs treated mice were higher than those in the controls, while IL-2 and IFN-γ levels were lower. Rejection in MSCs treated mice was accompanied by an increase in IL-2 and IFN-γ, and decrease in PD-L1 expression and IL-10 level. No difference in the expression of IDO between MSCs treated mice and controls was observed. In conclusion, we found that one of the mechanisms underlying MSCs immunomodulatory function could be up-regulating PD-L1 expression.

  20. How tough is bone? Application of elastic-plastic fracture mechanics to bone.

    PubMed

    Yan, Jiahau; Mecholsky, John J; Clifton, Kari B

    2007-02-01

    Bone, with a hierarchical structure that spans from the nano-scale to the macro-scale and a composite design composed of nano-sized mineral crystals embedded in an organic matrix, has been shown to have several toughening mechanisms that increases its toughness. These mechanisms can stop, slow, or deflect crack propagation and cause bone to have a moderate amount of apparent plastic deformation before fracture. In addition, bone contains a high volumetric percentage of organics and water that makes it behave nonlinearly before fracture. Many researchers used strength or critical stress intensity factor (fracture toughness) to characterize the mechanical property of bone. However, these parameters do not account for the energy spent in plastic deformation before bone fracture. To accurately describe the mechanical characteristics of bone, we applied elastic-plastic fracture mechanics to study bone's fracture toughness. The J integral, a parameter that estimates both the energies consumed in the elastic and plastic deformations, was used to quantify the total energy spent before bone fracture. Twenty cortical bone specimens were cut from the mid-diaphysis of bovine femurs. Ten of them were prepared to undergo transverse fracture and the other 10 were prepared to undergo longitudinal fracture. The specimens were prepared following the apparatus suggested in ASTM E1820 and tested in distilled water at 37 degrees C. The average J integral of the transverse-fractured specimens was found to be 6.6 kPa m, which is 187% greater than that of longitudinal-fractured specimens (2.3 kPa m). The energy spent in the plastic deformation of the longitudinal-fractured and transverse-fractured bovine specimens was found to be 3.6-4.1 times the energy spent in the elastic deformation. This study shows that the toughness of bone estimated using the J integral is much greater than the toughness measured using the critical stress intensity factor. We suggest that the J integral method is

  1. Comparison of procedures to assess non-linear and time-varying effects in multivariable models for survival data.

    PubMed

    Buchholz, Anika; Sauerbrei, Willi

    2011-03-01

    The focus of many medical applications is to model the impact of several factors on time to an event. A standard approach for such analyses is the Cox proportional hazards model. It assumes that the factors act linearly on the log hazard function (linearity assumption) and that their effects are constant over time (proportional hazards (PH) assumption). Variable selection is often required to specify a more parsimonious model aiming to include only variables with an influence on the outcome. As follow-up increases the effect of a variable often gets weaker, which means that it varies in time. However, spurious time-varying effects may also be introduced by mismodelling other parts of the multivariable model, such as omission of an important covariate or an incorrect functional form of a continuous covariate. These issues interact. To check whether the effect of a variable varies in time several tests for non-PH have been proposed. However, they are not sufficient to derive a model, as appropriate modelling of the shape of time-varying effects is required. In three examples we will compare five recently published strategies to assess whether and how the effects of covariates from a multivariable model vary in time. For practical use we will give some recommendations.

  2. Effect of time before storage and storage temperature on survival of Salmonella inoculated on fresh-cut melons.

    PubMed

    Ukuku, Dike O; Sapers, Gerald M

    2007-05-01

    The effects of a waiting period at room temperature ( approximately 22 degrees C) before refrigerating fresh-cut watermelon, cantaloupe and honeydew pieces contaminated with Salmonella on survival of the inoculated pathogen were investigated. Whole cantaloupes, honeydew melons and watermelons were washed with water, and fresh-cut pieces from individual melons were prepared and inoculated with a five strain cocktail of Salmonella at 10(5)cfu/ml. Populations of aerobic mesophilic bacteria, yeast and mold and Pseudomonas spp. were higher for fresh-cut cantaloupe than for fresh-cut watermelon and honeydew immediately after preparation. Populations of Salmonella, aerobic mesophilic bacteria, yeast and mold and Pseudomonas ssp. in fresh-cut melons left at room temperature for up to 5h before refrigeration were significantly (P<0.05) higher than populations in fresh-cut melons stored at 5 degrees C immediately after preparation. Populations of Salmonella recovered in fresh-cut melon after inoculation with the cocktail of Salmonella strains averaged 2 log(10)cfu/g for all three types of melons. Populations in fresh-cut watermelon and honeydew pieces declined by 1 log when stored immediately at 5 degrees C for 12 days, while the populations in fresh-cut cantaloupe did not show significant (P>0.05) changes. Populations of Salmonella in fresh-cut melons stored immediately at 10 degrees C for 12 days increased significantly (P<0.05) from 2.0 to 3.0 log(10)cfu/g in watermelon, 1.9 to 3.0 log(10)cfu/g in honeydew and 2.0 to 3.6 log(10)cfu/g in cantaloupe pieces. Holding freshly prepared, contaminated fresh-cut melon pieces at 22 degrees C for 3h or more prior to refrigerated storage would increase the chances of Salmonella proliferation, especially if the fresh-cut melons were subsequently stored at an abusive temperature.

  3. Time to focus child survival programmes on the newborn: assessment of levels and causes of infant mortality in rural Pakistan.

    PubMed Central

    Fikree, Fariyal F.; Azam, Syed Iqbal; Berendes, Heinz W.

    2002-01-01

    OBJECTIVE: Population-based surveys were conducted in selected clusters of Pakistan's least developed provinces, Balochistan and North-West Frontier Province (NWFP), including the Federally Administered Tribal Areas (FATA), to assess levels and causes of neonatal and postneonatal mortality. METHODS: Interviews were conducted in a total of 54 834 households: Balochistan, 20 486; NWFP, 26 175; and FATA, 8173. Trained interviewers administered questionnaires after obtaining verbal informed consent from the respondents. Verbal autopsy interviews were conducted for infant deaths reported for the previous year. FINDINGS: The infant mortality rate based on combined data from the different sites was 99.7 per 1000 live births (range 129.0-70.1). The contribution of neonatal deaths to all infant deaths was much higher for NWFP (67.2%), where the overall rate was lowest, than for Balochistan (50.8%) and FATA (56.8%). Around 70% of all neonatal deaths occurred in the early neonatal period. The three main clinical causes of infant deaths were diarrhoea syndrome (21.6%), tetanus (11.7%) and acute respiratory infections (11.6%). In the neonatal period, however, tetanus (18.3%), small size for gestational age or low birth weight (15.3%), and birth injury (12.0%) accounted for nearly half (45.6%) of all deaths, while the contributions of diarrhoea syndrome (5.1%) and acute respiratory infections (6.0%) were less significant (11.1%). Tetanus was the cause of death for 21.7% and 17.1% of all infant deaths in FATA and NWFP respectively. CONCLUSION: The results suggest that there should be a shift in child survival programmes to give greater emphasis to maternal and neonatal health, in particular to maternal tetanus immunization, safe delivery and cord care. PMID:12075362

  4. TH-E-BRF-05: Comparison of Survival-Time Prediction Models After Radiotherapy for High-Grade Glioma Patients Based On Clinical and DVH Features

    SciTech Connect

    Magome, T; Haga, A; Igaki, H; Sekiya, N; Masutani, Y; Sakumi, A; Mukasa, A; Nakagawa, K

    2014-06-15

    Purpose: Although many outcome prediction models based on dose-volume information have been proposed, it is well known that the prognosis may be affected also by multiple clinical factors. The purpose of this study is to predict the survival time after radiotherapy for high-grade glioma patients based on features including clinical and dose-volume histogram (DVH) information. Methods: A total of 35 patients with high-grade glioma (oligodendroglioma: 2, anaplastic astrocytoma: 3, glioblastoma: 30) were selected in this study. All patients were treated with prescribed dose of 30–80 Gy after surgical resection or biopsy from 2006 to 2013 at The University of Tokyo Hospital. All cases were randomly separated into training dataset (30 cases) and test dataset (5 cases). The survival time after radiotherapy was predicted based on a multiple linear regression analysis and artificial neural network (ANN) by using 204 candidate features. The candidate features included the 12 clinical features (tumor location, extent of surgical resection, treatment duration of radiotherapy, etc.), and the 192 DVH features (maximum dose, minimum dose, D95, V60, etc.). The effective features for the prediction were selected according to a step-wise method by using 30 training cases. The prediction accuracy was evaluated by a coefficient of determination (R{sup 2}) between the predicted and actual survival time for the training and test dataset. Results: In the multiple regression analysis, the value of R{sup 2} between the predicted and actual survival time was 0.460 for the training dataset and 0.375 for the test dataset. On the other hand, in the ANN analysis, the value of R{sup 2} was 0.806 for the training dataset and 0.811 for the test dataset. Conclusion: Although a large number of patients would be needed for more accurate and robust prediction, our preliminary Result showed the potential to predict the outcome in the patients with high-grade glioma. This work was partly supported by

  5. Effect of silica on porosity, strength, and toughness of pressureless sintered calcium phosphate-zirconia bioceramics.

    PubMed

    Schumacher, Thomas C; Treccani, Laura; Rezwan, Kurosch

    2015-08-12

    The preparation of dense, high-strength calcium phosphate-zirconia (CaP-ZrO2) composed bioceramics is realized via versatile pressureless sintering by adding silica nanoparticles. Two different weight ratios of HAp:ZrO2, 9:1 and 1:1, are used with varying silica contents from 5 to 20 wt%. After sintering at 1200 °C, the phase composition, microstructure, porosity, biaxial bending strength, and fracture toughness as well as SBF in vitro bioactivity are characterized. We show that the addition of silica altered the crystal phase composition, inhibiting the formation of non-favourable cubic ZrO2. Furthermore, SiO2 addition leads to an increase of the biaxial bending strength, and the fracture toughness of CaP-ZrO2-containing materials. With the addition of 20 wt% silica we find the highest characteristic strength (268 MPa) and toughness (2.3   ±   0.1 MPam(0.5)) at  <1% porosity. Both mechanical properties are 2 times higher than those of pure hydroxyapatite. At the same time we observe for the very same composition similar bioactivity to that of pure hydroxyapatite.

  6. Deterioration in Fracture Toughness of 304LN Austenitic Stainless Steel Due to Sensitization

    NASA Astrophysics Data System (ADS)

    Ghosh, Swati; Kain, V.; Ray, A.; Roy, H.; Sivaprasad, S.; Tarafder, S.; Ray, K. K.

    2009-12-01

    The aim of this report is to examine the influence of sensitization on the mechanical properties of AISI grade 304LN stainless steel with special emphasis on its fracture toughness. A series of stainless steel samples has been sensitized by holding at 1023 K for different time periods ranging from 1 to 100 hours followed by water quenching. The degree of sensitization (DOS) for each type of the varyingly heat-treated samples has been measured by an electrochemical potentiodynamic reactivation (EPR) test. The microstructures of these samples have been characterized by optical metallography, scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses, together with measurements of their hardness and tensile properties. The fracture toughness of the samples has been measured by the ball indentation (BI) technique and the results are validated by conducting conventional J-integral tests. It is revealed for the first time that the fracture toughness and ductility of AISI 304LN stainless steel deteriorate significantly with increased DOS, while the tensile strength (TS) values remain almost unaltered. The results have been critically discussed in terms of the depletion of solid solution strengtheners, the nature of the grain boundary precipitations, and the strain-induced martensite formation with the increasing DOS of the 304LN stainless steel.

  7. The toughness of secondary cell wall and woody tissue

    PubMed Central

    Lucas, P. W.; Tan, H. T. W.; Cheng, P. Y.

    1997-01-01

    The 'across grain' toughness of 51 woods has been determined on thin wet sections using scissors. The moisture content of sections and the varying sharpness of the scissor blades had little effect on the results. In thin sections (less than 0.6mm), toughness rose linearly with section thickness. The intercept toughness at zero thickness, estimated from regression analysis, was proportional to relative density, consistent with values reported for non-woody plant tissues. Extrapolation of the intercept toughness of these woods and other plant tissues/materials to a relative density of 1.0 predicted a toughness of 3.45kJ m-2 , which we identify with the intrinsic toughness of the cell wall. This quantity appears to predict published results from KIC tests on woods and is related to the propensity for crack deflection. The slope of the relationship between section thickness and toughness, describing the work of plastic buckling of cells, was not proportional to relative density, the lightest (balsa) and heaviest (lignum vitae) woods fracturing with less plastic work than predicted. The size of the plastic zone around the crack tip was estimated to be 0.5mm in size. From this, the hypothetical overall toughness of a thick (greater than 1 mm) block of solid cell wall material was calculated as 39.35 kJ m-2, due to both cell wall resistance (10 per cent) and the plastic buckling of cells (90 per cent). This value successfully predicts the toughness of most commercial woods (of relative densities between 0.2 and 0.8) from 'work area' tests in tension and bending. Though density was the most important factor, both fibre width/fibre length (in hardwoods) and lignin/cellulose ratios were negatively correlated with the work of plastic buckling, after correcting for density. At low densities the work of plastic buckling in the longitudinal radial (LR) direction exceeded that in longitudinal tangential (LT), but the reverse was true for relative densities above 0.25. This could

  8. Effects of stitching on fracture toughness of uniweave textile graphite/epoxy laminates

    NASA Technical Reports Server (NTRS)

    Sankar, Bhavani V.; Sharma, Suresh

    1995-01-01

    The effects of through-the-thickness stitching on impact damage resistance, impact damage tolerance, and Mode 1 and Mode 2 fracture toughness of textile graphite/epoxy laminates were studied experimentally. Graphite/epoxy laminates were fabricated from AS4 graphite uniweave textiles and 3501-6 epoxy using Resin Transfer Molding. The cloths were stitched with Kevlar(tm) and glass yarns before resin infusion. Delamination was implanted during processing to simulate impact damage. Sublaminate buckling tests were performed in a novel fixture to measure Compression After Impact (CAI) strength of stitched laminates. The results show that CAI strength can be improved up to 400% by through-the-thickness stitching. Double Cantilever Beam tests were performed to study the effect of stitching on Mode 1 fracture toughness G(sub 1c). It was found that G(sub 1c) increased 30 times for a low stitching density of 16 stitches/sq in. Mode 2 fracture toughness was measured by testing the stitched beams in End Notch Flexure tests. Unlike in the unstitiched beams, crack propagation in the stitched beams was steady. The current formulas for ENF tests were not found suitable for determining G(sub 2C) for stitched beams. Hence two new methods were developed - one based on crack area measured from ultrasonic C-scanning and the other based on equivalent crack area measured from the residual stiffness of the specimen. The G(sub 2c) was found to be at least 5-15 times higher for the stitched laminates. The mechanisms by which stitching increases the CAI strength and fracture toughness are discussed.

  9. Relationship Between Radiation Treatment Time and Overall Survival After Induction Chemotherapy for Locally Advanced Head-and-Neck Carcinoma: A Subset Analysis of TAX 324

    SciTech Connect

    Sher, David J.; Posner, Marshall R.; Sarlis, Nicholas J.; Haddad, Robert I.; Holupka, Edward J.; Devlin, Phillip M.

    2011-12-01

    Purpose: To analyze the relationship between overall survival (OS) and radiation treatment time (RTT) and overall treatment time (OTT) in a well-described sequential therapy paradigm for locally advanced head-and-neck carcinoma (LAHNC). Methods and Materials: TAX 324 is a Phase III study comparing TPF (docetaxel, cisplatin, and fluorouracil) with PF (cisplatin and fluorouracil) induction chemotherapy (IC) in LAHNC patients; both arms were followed by carboplatin-based chemoradiotherapy (CRT). Prospective radiotherapy quality assurance was performed. This analysis includes all patients who received three cycles of IC and a radiation dose of {>=} 70 Gy. Radiotherapy treatment time was analyzed as binary ({<=} 8 weeks vs. longer) and continuous (number of days beyond 8 weeks) functions. The primary analysis assessed the relationship between RTT, OTT, and OS, and the secondary analysis explored the association between treatment times and locoregional recurrence (LRR). Results: A total of 333 (of 501) TAX 324 patients met the criteria for inclusion in this analysis. There were no significant differences between the treatment arms in baseline or treatment characteristics. On multivariable analysis, PF IC, World Health Organization performance status of 1, non-oropharynx site, T3/4 stage, N3 status, and prolonged RTT (hazard ratio 1.63, p = 0.006) were associated with significantly inferior survival. Performance status, T3/4 disease, and prolonged RTT (odds ratio 1.68, p = 0.047) were independently and negatively related to LRR on multivariable analysis, whereas PF was not. Overall treatment time was not independently associated with either OS or LRR. Conclusions: In this secondary analysis of the TAX 324 trial, TPF IC remains superior to PF IC after controlling for radiotherapy delivery time. Even with optimal IC and concurrent chemotherapy, a non-prolonged RTT is a crucial determinant of treatment success. Appropriate delivery of radiotherapy after IC remains essential

  10. Association of GUCY2C Expression in Lymph Nodes and Time to Recurrence and Disease-Free Survival in pN0 Colorectal Cancer

    PubMed Central

    Waldman, Scott A.; Hyslop, Terry; Schulz, Stephanie; Barkun, Alan; Nielsen, Karl; Haaf, Janis; Bonaccorso, Christine; Li, Yanyan; Weinberg, David S.

    2009-01-01

    Context The established relationship between lymph node metastasis and prognosis in colorectal cancer suggests that recurrence in 25% of patients with lymph nodes free of tumor cells by histopathology (pN0) reflects the presence of occult metastases. GUCY2C is a marker expressed by colorectal tumors that could reveal occult metastases in lymph nodes and better estimate recurrence risk. Objective To examine the association of occult lymph node metastases detected by quantifying GUCY2C mRNA, employing the reverse transcriptase-polymerase chain reaction, with recurrence and survival in patients with colorectal cancer. Design, Setting, and Participants Prospective enrollment of 257 patients with pN0 colorectal cancer enrolled between March 2002 and June 2007 at 9 centers provided 2,570 fresh lymph nodes ≥5 mm for histopathology and GUCY2C mRNA analysis. Patients were followed for a median of 24 months (range: 2–63) for disease recurrence or death. Main Outcome Measures Time to recurrence (primary outcome) and disease-free survival (secondary outcome) relative to expression of GUCY2C in lymph nodes. Results Thirty-two (12.5%) patients had lymph nodes negative for GUCY2C [pN0(mol−)], and all but two remained free of disease during follow-up (recurrence rate 6.3% [95%CI 0.8–20.8%]). Conversely, 225 (87.5%) patients had lymph nodes positive for GUCY2C [pN0(mol+)], and 47 (20.9% [15.8–26.8%]) developed recurrent disease (p=0.006). Multivariable analyses revealed that GUCY2C in lymph nodes was an independent marker of prognosis. Patients who were pN0(mol+) exhibited earlier time to recurrence (adjusted hazard ratio 4.66 [1.11–19.57]; p=0.035) and reduced disease-free survival (adjusted hazard ratio 3.27 [1.15–9.29]; p=0.026). Conclusion Expression of GUCY2C in histologically negative lymph nodes appears to be independently associated with time to recurrence and disease-free survival in patients with pN0 colorectal cancer. PMID:19224751

  11. The use of propensity score methods with survival or time-to-event outcomes: reporting measures of effect similar to those used in randomized experiments.

    PubMed

    Austin, Peter C

    2014-03-30

    Propensity score methods are increasingly being used to estimate causal treatment effects in observational studies. In medical and epidemiological studies, outcomes are frequently time-to-event in nature. Propensity-score methods are often applied incorrectly when estimating the effect of treatment on time-to-event outcomes. This article describes how two different propensity score methods (matching and inverse probability of treatment weighting) can be used to estimate the measures of effect that are frequently reported in randomized controlled trials: (i) marginal survival curves, which describe survival in the population if all subjects were treated or if all subjects were untreated; and (ii) marginal hazard ratios. The use of these propensity score methods allows one to replicate the measures of effect that are commonly reported in randomized controlled trials with time-to-event outcomes: both absolute and relative reductions in the probability of an event occurring can be determined. We also provide guidance on variable selection for the propensity score model, highlight methods for assessing the balance of baseline covariates between treated and untreated subjects, and describe the implementation of a sensitivity analysis to assess the effect of unmeasured confounding variables on the estimated treatment effect when outcomes are time-to-event in nature. The methods in the paper are illustrated by estimating the effect of discharge statin prescribing on the risk of death in a sample of patients hospitalized with acute myocardial infarction. In this tutorial article, we describe and illustrate all the steps necessary to conduct a comprehensive analysis of the effect of treatment on time-to-event outcomes.

  12. Conjugation of a dipicolyl chelate to polypeptide conjugates increases binding affinities for human serum albumin and survival times in human serum.

    PubMed

    Balliu, Aleksandra; Baltzer, Lars

    2017-03-16

    The affinity for human serum albumin (HSA) of a series of 2-5 kDa peptides covalently linked to 3,5-bis[[bis(2-pyridylmethyl)amino]methyl]benzoic acid, a dipicolyl chelator with μM affinity for Zn2+, was found by surface plasmon resonance to increase in the presence of 1μM ZnCl2 at physiological pH. The dependence on polypeptide hydrophobicity was found to be minor, suggesting that the conjugates bound to the metal binding site and not to the fatty acid binding site. The affinity of the conjugates increased strongly with the positive charge of the polypeptides suggesting proximity to the negatively charged protein surface surrounding the metal binding site. The survival times of the peptides in human serum were extended as a consequence of stronger binding to HSA suggesting that Zn2+ ion chelating agents may provide a general route to increased survival times of peptides in serum in therapeutic and diagnostic applications without significantly increasing their molecular weights.

  13. Expression of aldehyde dehydrogenase family 1 member A1 and high mobility group box 1 in oropharyngeal squamous cell carcinoma in association with survival time

    PubMed Central

    Qian, Xu; Coordes, Annekatrin; Kaufmann, Andreas M.; Albers, Andreas E.

    2016-01-01

    Despite the development of novel multimodal treatment combinations in advanced oropharyngeal squamous cell carcinoma (OSCC), outcomes remain poor. The identification of specifically validated biomarkers is required to understand the underlying molecular mechanisms, to evaluate treatment efficiency and to develop novel therapeutic targets. The present study, therefore, examined the presence of aldehyde dehydrogenase family 1 member A1 (ALDH1A1) and high mobility group box 1 (HMGB1) expression in primary OSCC and analyzed the impact on survival time. In 59 patients with OSCC, the expression of ALDH1A1, p16 and HMGB1, and their clinicopathological data were analyzed. HMGB1 positivity was significantly increased in patients with T1-2 stage disease compared with T3-4 stage disease (P<0.001), whereas ALDH1A1 positivity was not. ALDH1A1+ tumors showed significantly lower differentiation than ALDH1A1− tumors (P=0.018). Multivariate analysis showed that ALDH1A1 positivity (P=0.041) and nodal status (N2-3) (P=0.036) predicted a poor prognosis. In this patient cohort, ALDH1A1 and nodal status were identified as independent predictors of a shorter overall survival time. The study results, therefore, provide evidence of the prognostic value of ALDH1A1 as a marker for cancer stem cells and nodal status in OSCC patients. PMID:27900016

  14. Expression of aldehyde dehydrogenase family 1 member A1 and high mobility group box 1 in oropharyngeal squamous cell carcinoma in association with survival time.

    PubMed

    Qian, Xu; Coordes, Annekatrin; Kaufmann, Andreas M; Albers, Andreas E

    2016-11-01

    Despite the development of novel multimodal treatment combinations in advanced oropharyngeal squamous cell carcinoma (OSCC), outcomes remain poor. The identification of specifically validated biomarkers is required to understand the underlying molecular mechanisms, to evaluate treatment efficiency and to develop novel therapeutic targets. The present study, therefore, examined the presence of aldehyde dehydrogenase family 1 member A1 (ALDH1A1) and high mobility group box 1 (HMGB1) expression in primary OSCC and analyzed the impact on survival time. In 59 patients with OSCC, the expression of ALDH1A1, p16 and HMGB1, and their clinicopathological data were analyzed. HMGB1 positivity was significantly increased in patients with T1-2 stage disease compared with T3-4 stage disease (P<0.001), whereas ALDH1A1 positivity was not. ALDH1A1(+) tumors showed significantly lower differentiation than ALDH1A1(-) tumors (P=0.018). Multivariate analysis showed that ALDH1A1 positivity (P=0.041) and nodal status (N2-3) (P=0.036) predicted a poor prognosis. In this patient cohort, ALDH1A1 and nodal status were identified as independent predictors of a shorter overall survival time. The study results, therefore, provide evidence of the prognostic value of ALDH1A1 as a marker for cancer stem cells and nodal status in OSCC patients.

  15. Statistical description for survival data

    PubMed Central

    2016-01-01

    Statistical description is always the first step in data analysis. It gives investigator a general impression of the data at hand. Traditionally, data are described as central tendency and deviation. However, this framework does not fit to the survival data (also termed time-to-event data). Such data type contains two components. One is the survival time and the other is the status. Researchers are usually interested in the probability of event at a given survival time point. Hazard function, cumulative hazard function and survival function are commonly used to describe survival data. Survival function can be estimated using Kaplan-Meier estimator, which is also the default method in most statistical packages. Alternatively, Nelson-Aalen estimator is available to estimate survival function. Survival functions of subgroups can be compared using log-rank test. Furthermore, the article also introduces how to describe time-to-event data with parametric modeling. PMID:27867953

  16. Tough, in-situ thermogelling, injectable hydrogels for biomedical applications.

    PubMed

    Jalani, Ghulam; Rosenzweig, Derek H; Makhoul, Georges; Abdalla, Sherif; Cecere, Renzo; Vetrone, Fiorenzo; Haglund, Lisbet; Cerruti, Marta

    2015-04-01

    Injectable hydrogels are extensively used in drug delivery and tissue engineering to administer drugs, genes, growth factors and live cells. We report a method to produce tough, in-situ thermogelling, non-toxic, injectable hydrogels made of chitosan and hyaluronic acid co-crosslinked with β-glycerophophate and genipin. The gels are highly homogeneous and form within 32 min, i.e., faster than gels crosslinked with either genipin or β-glycerophophate. The shear strength of co-crosslinked hydrogels is 3.5 kPa, higher than any chitosan-based gel reported. Chondrocytes and nucleus pulposus cells thrive inside the gels and produce large amounts of collagen II. Injection in rats shows that the gels form in-vivo within a short time and remain well localized for more than one week while the rats remain healthy and active. The excellent mechanical properties, fast in-situ gelation, good biocompatibility and the ability to encapsulate live cells at physiological conditions make these hydrogels ideal for tissue engineering, especially cartilage regeneration.

  17. Dynamic Fracture Initiation Toughness at Elevated Temperatures With Application to the New Generation of Titanium Aluminide Alloys. Chapter 8

    NASA Technical Reports Server (NTRS)

    Shazly, Mostafa; Prakash, Vikas; Draper, Susan; Shukla, Arun (Editor)

    2006-01-01

    Recently, a new generation of titanium aluminide alloy, named Gamma-Met PX, has been developed with better rolling and post-rolling characteristics. I'revious work on this alloy has shown the material to have higher strengths at room and elevated temperatures when compared with other gamma titanium aluminides. In particular, this new alloy has shown increased ductility at elevated temperatures under both quasi-static and high strain rate uniaxial compressive loading. However, its high strain rate tensile ductility at room and elevated temperatures is limited to approx. 1%. In the present chapter, results of a study to investigate the effects of loading rate and test temperature on the dynamic fracture initiation toughness in Gamma-Met PX are presented. Modified split Hopkinson pressure bar was used along with high-speed photography to determine the crack initiation time. Three-point bend dynamic fracture experiments were conducted at impact speeds of approx. 1 m/s and tests temperatures of up-to 1200 C. The results show that thc dynamic fracture initiation toughness decreases with increasing test temperatures beyond 600 C. Furthermore, thc effect of long time high temperature air exposure on the fracture toughness was investigated. The dynamic fracture initiation toughness was found to decrease with increasing exposure time. The reasons behind this drop are analyzed and discussed.

  18. Microscale resolution fracture toughness profiling at the zirconia-porcelain interface in dental prostheses

    NASA Astrophysics Data System (ADS)

    Lunt, Alexander J. G.; Mohanty, Gaurav; Neo, Tee K.; Michler, Johann; Korsunsky, Alexander M.

    2015-12-01

    The high failure rate of the Yttria Partially Stabilized Zirconia (YPSZ)-porcelain interface in dental prostheses is influenced by the micro-scale mechanical property variation in this region. To improve the understanding of this behavior, micro-scale fracture toughness profiling by nanoindentation micropillar splitting is reported for the first time. Sixty 5 μm diameter micropillars were machined within the first 100 μm of the interface. Berkovich nanoindentation provided estimates of the bulk fracture toughness of YPSZ and porcelain that matched the literature values closely. However, the large included tip angle prevented precise alignment of indenter with the pillar center. Cube corner indentation was performed on the remainder of the pillars and calibration between nanoindentation using different tip shapes was used to determine the associated conversion factors. YPSZ micropillars failed by gradual crack propagation and bulk values persisted to within 15 μm from the interface, beyond which scatter increased and a 10% increase in fracture toughness was observed that may be associated with grain size variation at this location. Micropillars straddling the interface displayed preferential fracture within porcelain parallel to the interface at a location where nano-voiding has previously been observed and reported. Pure porcelain micropillars exhibited highly brittle failure and a large reduction of fracture toughness (by up to ~90%) within the first 50 μm of the interface. These new insights constitute a major advance in understanding the structure-property relationship of this important bi-material interface at the micro-scale, and will improve micromechanical modelling needed to optimize current manufacturing routes and reduce failure.

  19. Liquid crystal self-templating approach to ultrastrong and tough biomimic composites

    NASA Astrophysics Data System (ADS)

    Hu, Xiaozhen; Xu, Zhen; Liu, Zheng; Gao, Chao

    2013-08-01

    Materials with both high strength and toughness are in great demand for a wide range of applications, requiring strict design of ingredients and hierarchically ordered architecture from nano- to macro-scale. Nacre achieves such a target in the long natural evolution by alternative alignment of inorganic nanoplatelets and biomacromolecules. To mimic nacre, various strategies were developed, approaching nacre-comparable performance in limited size. How to remarkably exceed nacre in both property and size is a key issue to further the advancement of composites. Here we present liquid crystal self-templating methodology to make the next generation of ultrastrong and tough nacre-mimics continuously. The hierarchically assembled composites show the highest tensile strength (652 MPa) among nacre mimics, five to eight times as high as that of nacre (80-135 MPa), and excellent ductility with toughness of 18 MJ m-3, one to two orders of magnitude greater than that of nacre (0.1 ~ 1.8 MJ m-3).

  20. Fracture toughness of Alloy 690 and EN52 weld in air and water

    SciTech Connect

    Brown, C.M.; Mills, W.J.

    1999-06-01

    The effect of low and high temperature water with high hydrogen on the fracture toughness of Alloy 690 and its weld, EN52, was characterized using elastic-plastic J{sub IC} methodology. While both materials display excellent fracture resistance in air and elevated temperature (>93 C) water, a dramatic degradation in toughness is observed in 54 C water. The loss of toughness is associated with a hydrogen-induced intergranular cracking mechanism where hydrogen is picked up from the water. Comparison of the cracking behavior in low temperature water with that for hydrogen-precharged specimens tested in air indicates that the critical local hydrogen content required to cause low temperature embrittlement is on the order of 120 to 160 ppm. Loading rate studies show that the cracking resistance is significantly improved at rates above ca. 1000 MPa{radical}m/h because there is insufficient time to produce grain boundary embrittlement. Electron fractographic examinations were performed to correlate cracking behavior with microstructural features and operative fracture mechanics.

  1. Effects of a brain-engraftable microglial cell line expressing anti-prion scFv antibodies on survival times of mice infected with scrapie prions.

    PubMed

    Fujita, Koji; Yamaguchi, Yoshitaka; Mori, Tsuyoshi; Muramatsu, Naomi; Miyamoto, Takahito; Yano, Masashi; Miyata, Hironori; Ootsuyama, Akira; Sawada, Makoto; Matsuda, Haruo; Kaji, Ryuji; Sakaguchi, Suehiro

    2011-10-01

    We first verified that a single chain Fv fragment against prion protein (anti-PrP scFv) was secreted by HEK293T cells and prevented prion replication in infected cells. We then stably expressed anti-PrP scFv in brain-engraftable murine microglial cells and intracerebrally injected these cells into mice before or after infection with prions. Interestingly, the injection before or at an early time point after infection attenuated the infection marginally but significantly prolonged survival times of the mice. These suggest that the ex vivo gene transfer of anti-PrP scFvs using brain-engraftable cells could be a possible immunotherapeutic approach against prion diseases.

  2. Fracture toughness evaluations of TP304 stainless steel pipes

    SciTech Connect

    Rudland, D.L.; Brust, F.W.; Wilkowski, G.M.

    1997-02-01

    In the IPIRG-1 program, the J-R curve calculated for a 16-inch nominal diameter, Schedule 100 TP304 stainless steel (DP2-A8) surface-cracked pipe experiment (Experiment 1.3-3) was considerably lower than the quasi-static, monotonic J-R curve calculated from a C(T) specimen (A8-12a). The results from several related investigations conducted to determine the cause of the observed toughness difference are: (1) chemical analyses on sections of Pipe DP2-A8 from several surface-cracked pipe and material property specimen fracture surfaces indicate that there are two distinct heats of material within Pipe DP2-A8 that differ in chemical composition; (2) SEN(T) specimen experimental results indicate that the toughness of a surface-cracked specimen is highly dependent on the depth of the initial crack, in addition, the J-R curves from the SEN(T) specimens closely match the J-R curve from the surface-cracked pipe experiment; (3) C(T) experimental results suggest that there is a large difference in the quasi-static, monotonic toughness between the two heats of DP2-A8, as well as a toughness degradation in the lower toughness heat of material (DP2-A8II) when loaded with a dynamic, cyclic (R = {minus}0.3) loading history.

  3. Difference in Restricted Mean Survival Time for Cost-Effectiveness Analysis Using Individual Patient Data Meta-Analysis: Evidence from a Case Study

    PubMed Central

    Lueza, Béranger; Mauguen, Audrey; Pignon, Jean-Pierre; Rivero-Arias, Oliver; Bonastre, Julia

    2016-01-01

    Objective In economic evaluation, a commonly used outcome measure for the treatment effect is the between-arm difference in restricted mean survival time (rmstD). This study illustrates how different survival analysis methods can be used to estimate the rmstD for economic evaluation using individual patient data (IPD) meta-analysis. Our aim was to study if/how the choice of a method impacts on cost-effectiveness results. Methods We used IPD from the Meta-Analysis of Radiotherapy in Lung Cancer concerning 2,000 patients with locally advanced non-small cell lung cancer, included in ten trials. We considered methods either used in the field of meta-analysis or in economic evaluation but never applied to assess the rmstD for economic evaluation using IPD meta-analysis. Methods were classified into two approaches. With the first approach, the rmstD is estimated directly as the area between the two pooled survival curves. With the second approach, the rmstD is based on the aggregation of the rmstDs estimated in each trial. Results The average incremental cost-effectiveness ratio (ICER) and acceptability curves were sensitive to the method used to estimate the rmstD. The estimated rmstDs ranged from 1.7 month to 2.5 months, and mean ICERs ranged from € 24,299 to € 34,934 per life-year gained depending on the chosen method. At a ceiling ratio of € 25,000 per life year-gained, the probability of the experimental treatment being cost-effective ranged from 31% to 68%. Conclusions This case study suggests that the method chosen to estimate the rmstD from IPD meta-analysis is likely to influence the results of cost-effectiveness analyses. PMID:26960150

  4. Survival after Abdominoperineal and Sphincter-Preserving Resection in Nonmetastatic Rectal Cancer: A Population-Based Time-Trend and Propensity Score-Matched SEER Analysis

    PubMed Central

    Warschkow, Rene; Ebinger, Sabrina M.; Brunner, Walter; Schmied, Bruno M.

    2017-01-01

    Background. Abdominoperineal resection (APR) has been associated with impaired survival in nonmetastatic rectal cancer patients. It is unclear whether this adverse outcome is due to the surgical procedure itself or is a consequence of tumor-related characteristics. Study Design. Patients were identified from the Surveillance, Epidemiology, and End Results database. The impact of APR compared to coloanal anastomosis (CAA) on survival was assessed by Cox regression and propensity-score matching. Results. In 36,488 patients with rectal cancer resection, the APR rate declined from 31.8% in 1998 to 19.2% in 2011, with a significant trend change in 2004 at 21.6% (P < 0.001). To minimize a potential time-trend bias, survival analysis was limited to patients diagnosed after 2004. APR was associated with an increased risk of cancer-specific mortality after unadjusted analysis (HR = 1.61, 95% CI: 1.28–2.03, P < 0.01) and multivariable adjustment (HR = 1.39, 95% CI: 1.10–1.76, P < 0.01). After optimal adjustment of highly biased patient characteristics by propensity-score matching, APR was not identified as a risk factor for cancer-specific mortality (HR = 0.85, 95% CI: 0.56–1.29, P = 0.456). Conclusions. The current propensity score-adjusted analysis provides evidence that worse oncological outcomes in patients undergoing APR compared to CAA are caused by different patient characteristics and not by the surgical procedure itself. PMID:28197206

  5. Methodology for lognormal modelling of malignant pleural mesothelioma survival time distributions: a study of 5580 case histories from Europe and USA

    NASA Astrophysics Data System (ADS)

    Mould, Richard F.; Lahanas, Michael; Asselain, Bernard; Brewster, David; Burgers, Sjaak A.; Damhuis, Ronald A. M.; DeRycke, Yann; Gennaro, Valerio; Szeszenia-Dabrowska, Neonila

    2004-09-01

    A truncated left-censored and right-censored lognormal model has been validated for representing pleural mesothelioma survival times in the range 5-200 weeks for data subsets grouped by age for males, 40-49, 50-59, 60-69, 70-79 and 80+ years and for all ages combined for females. The cases available for study were from Europe and USA and totalled 5580. This is larger than any other pleural mesothelioma cohort accrued for study. The methodology describes the computation of reference baseline probabilities, 5-200 weeks, which can be used in clinical trials to assess results of future promising treatment methods. This study is an extension of previous lognormal modelling by Mould et al (2002 Phys. Med. Biol. 47 3893-924) to predict long-term cancer survival from short-term data where the proportion cured is denoted by C and the uncured proportion, which can be represented by a lognormal, by (1 - C). Pleural mesothelioma is a special case when C = 0.

  6. Timing of expression of the core clock gene Bmal1 influences its effects on aging and survival

    PubMed Central

    Yang, Guangrui; Chen, Lihong; Grant, Gregory R.; Paschos, Georgios; Song, Wen-Liang; Musiek, Erik S.; Lee, Vivian; McLoughlin, Sarah C.; Grosser, Tilo; Cotsarelis, George; FitzGerald, Garret A.

    2016-01-01

    The absence of Bmal1, a core clock gene, results in a loss of circadian rhythms, an acceleration of aging, and a shortened life span in mice. To address the importance of circadian rhythms in the aging process, we generated conditional Bmal1 knockout mice that lacked the BMAL1 protein during adult life and found that wild-type circadian variations in wheel-running activity, heart rate, and blood pressure were abolished. Ocular abnormalities and brain astrogliosis were conserved irrespective of the timing of Bmal1 deletion. However, life span, fertility, body weight, blood glucose levels, and age-dependent arthropathy - which are altered in standard Bmal1 knockout mice - remained unaltered, while atherosclerosis and hair growth improved, in the conditional adult-life Bmal1 knockout mice, despite abolition of clock function. Hepatic RNA-Seq revealed that expression of oscillatory genes was dampened in the adult-life Bmal1 knockout mice, while overall gene expression was largely unchanged. Thus, many phenotypes in conventional Bmal1 knockout mice, hitherto attributed to disruption of circadian rhythms, reflect the loss of properties of BMAL1 that are independent of its role in the clock. These findings prompt re-evaluation of the systemic consequences of disruption of the molecular clock. PMID:26843191

  7. Tropical tree rings reveal preferential survival of fast-growing juveniles and increased juvenile growth rates over time.

    PubMed

    Rozendaal, Danaë M A; Brienen, Roel J W; Soliz-Gamboa, Claudia C; Zuidema, Pieter A

    2010-02-01

    Long-term juvenile growth patterns of tropical trees were studied to test two hypotheses: fast-growing juvenile trees have a higher chance of reaching the canopy ('juvenile selection effect'); and tree growth has increased over time ('historical growth increase'). Tree-ring analysis was applied to test these hypotheses for five tree species from three moist forest sites in Bolivia, using samples from 459 individuals. Basal area increment was calculated from ring widths, for trees < 30 cm in diameter. For three out of five species, a juvenile selection effect was found in rings formed by small juveniles. Thus, extant adult trees in these species have had higher juvenile growth rates than extant juvenile trees. By contrast, rings formed by somewhat larger juveniles in four species showed the opposite pattern: a historical growth increase. For most size classes of > 10 cm diameter none of the patterns was found. Fast juvenile growth may be essential to enable tropical trees to reach the forest canopy, especially for small juvenile trees in the dark forest understorey. The historical growth increase requires cautious interpretation, but may be partially attributable to CO(2) fertilization.

  8. Empirical study of correlated survival times for recurrent events with proportional hazards margins and the effect of correlation and censoring

    PubMed Central

    2013-01-01

    Background In longitudinal studies where subjects experience recurrent incidents over a period of time, such as respiratory infections, fever or diarrhea, statistical methods are required to take into account the within-subject correlation. Methods For repeated events data with censored failure, the independent increment (AG), marginal (WLW) and conditional (PWP) models are three multiple failure models that generalize Cox’s proportional hazard model. In this paper, we revise the efficiency, accuracy and robustness of all three models under simulated scenarios with varying degrees of within-subject correlation, censoring levels, maximum number of possible recurrences and sample size. We also study the methods performance on a real dataset from a cohort study with bronchial obstruction. Results We find substantial differences between methods and there is not an optimal method. AG and PWP seem to be preferable to WLW for low correlation levels but the situation reverts for high correlations. Conclusions All methods are stable in front of censoring, worsen with increasing recurrence levels and share a bias problem which, among other consequences, makes asymptotic normal confidence intervals not fully reliable, although they are well developed theoretically. PMID:23883000

  9. A joint fracture toughness evaluation of hot-pressed beryllium

    NASA Technical Reports Server (NTRS)

    Conrad, H.; Sargent, G. A.; Brown, W. F., Jr.

    1977-01-01

    Fracture toughness tests at room temperature were made on three-point bend specimens cut from hot-pressed beryllium obtained from two suppliers. The test specimens had dimensions conforming to ASTM fracture toughness standard E399-72. A total of 42 specimens were machined from each batch of material. Six specimens from each batch were then distributed to seven independent laboratories for testing. The test data from the laboratories were collected and analyzed for differences between the laboratories and the two batches of material. It is concluded that ASTM 399-72 can be used as a valid test procedure for determining the fracture toughness of beryllium, providing that Kf(max) in fatigue cracking could be up to 80 percent of the K(0) value.

  10. Improvement of fracture toughness of epoxy resins at cryogenic temperature

    SciTech Connect

    Nishijima, S.; Yamada, K.; Hussain, M.; Honda, Y.

    1997-06-01

    The improvement of the fracture toughness of epoxy resin has been tried to perform from the molecular level with an aim to improve the cryogenic properties of GFRP and/or the stability of superconducting magnets. The ceramic filler, which was formed by hydrolysis of alkoxide, was dispersed in the epoxy and cured. A coupling agent was also used to crosslink the filler and epoxy molecules. The positron annihilation lifetime was measured and the molecular state of the epoxies were evaluated. The thermal contraction and Vickers hardness were also measured. The thermal contraction and hardness were confirmed to reflect the molecular state as evaluated by positron annihilation lifetime. The fracture toughness was also measured down to cryogenic temperatures. It was found that the improvement of the fracture toughness at cryogenic temperatures is possible.

  11. Effect of nanoscale patterned interfacial roughness on interfacial toughness.

    SciTech Connect

    Zimmerman, Jonathan A.; Moody, Neville Reid; Mook, William M.; Kennedy, Marian S.; Bahr, David F.; Zhou, Xiao Wang; Reedy, Earl David, Jr.

    2007-09-01

    The performance and the reliability of many devices are controlled by interfaces between thin films. In this study we investigated the use of patterned, nanoscale interfacial roughness as a way to increase the apparent interfacial toughness of brittle, thin-film material systems. The experimental portion of the study measured the interfacial toughness of a number of interfaces with nanoscale roughness. This included a silicon interface with a rectangular-toothed pattern of 60-nm wide by 90-nm deep channels fabricated using nanoimprint lithography techniques. Detailed finite element simulations were used to investigate the nature of interfacial crack growth when the interface is patterned. These simulations examined how geometric and material parameter choices affect the apparent toughness. Atomistic simulations were also performed with the aim of identifying possible modifications to the interfacial separation models currently used in nanoscale, finite element fracture analyses. The fundamental nature of atomistic traction separation for mixed mode loadings was investigated.

  12. Exceptionally tough and notch-insensitive magnetic hydrogels.

    PubMed

    Haider, Hussain; Yang, Can Hui; Zheng, Wen Jiang; Yang, Jian Hai; Wang, Mei Xiang; Yang, Sen; Zrínyi, Miklós; Osada, Yoshihito; Suo, Zhigang; Zhang, Qiqing; Zhou, Jinxiong; Chen, Yong Mei

    2015-11-14

    Most existing magnetic hydrogels are weak and brittle. The development of strong and tough magnetic hydrogels would extend their applications into uncultivated areas, such as in actuators for soft machines and guided catheters for magnetic navigation systems, which is still a big challenge. Here a facile and versatile approach to fabricating highly stretchable, exceptionally tough and notch-insensitive magnetic hydrogels, Fe(3)O(4)@Fe-alginate/polyacrylamide (PAAm), is developed, by dispersing alginate-coated Fe(3)O(4) nanoparticles into the interpenetrating polymer networks of alginate and PAAm, with hybrid physical and chemical crosslinks. A cantilever bending beam actuator as well as a proof-of-concept magnetically guided hydrogel catheter is demonstrated. The method proposed in this work can be integrated into other strong and tough magnetic hydrogels for the development of novel hydrogel nanocomposites with both desirable functionality and superior mechanical properties.

  13. On fracture toughness evaluation for semi-brittle fracture

    NASA Technical Reports Server (NTRS)

    Eftis, J.; Liebowitz, H.

    1975-01-01

    The existing methods of assessing the fracture toughness of materials exhibiting semi-brittle fracture are critically reviewed. The methods concern the Crack Growth Resistance (R-curve), the Crack Opening Displacement (COD), and the J-integral. An analysis of the shortcomings of the methods described makes it possible to formulate a new definition of fracture toughness appropriate to semi-brittle fracture. An improved simple experimental method for measuring fracture toughness for semi-brittle fracture is proposed which takes into account both crack growth and plastic nonlinear effects at crack front. The proposed method is shown to be free of the theoretical and experimental discrepancies encountered in the R-curve, COD, and J-integral methods.

  14. Fracture toughness of an Al-Li-Cu-In alloy

    NASA Technical Reports Server (NTRS)

    Wagner, John A.; Gangloff, Richard P.

    1992-01-01

    The crack initiation and growth fracture toughness of select AL-Li-Cu alloy variants are characterized and elucidated. Conventionally processed plates form large DC cast ingots are investigated to eliminate the variation in microstructure associated with laboratory scale and SPF-processed material. Fracture resistance is characterized using the J-integral method to establish crack initiation and growth behavior at 25 and -185 C. It is shown that state-of-the-art 2090-T81 has superior toughness compared to 2090 + In-T6 at both test temperatures, with the low toughness of 2090 + In-T6 associated with intersubgranular fracture attributed to a high density of subboundary precipitates.

  15. Experimental study on the survival of the water hyacinth (Eichhornia crassipes (Mart.) Solms--Pontederiaceae) under different oil doses and times of exposure.

    PubMed

    Lopes, Aline; Piedade, Maria Teresa Fernandez

    2014-12-01

    In the last decades, petroleum activities have increased in the Brazilian Amazon where there is oil exploration on the Urucu River, a tributary of the Amazon River, about 600 km from the city of Manaus. Particularly, transportation via the Amazon River to reach the oil refinery in Manaus may compromise the integrity of the large floodplains that flank hundreds of kilometers of this major river. In the Amazon floodplains, plant growth and nutrient cycling are related to the flood pulse. When oil spills occur, floating oil on the water surface is dispersed through wind and wave action in the littoral region, thus affecting the vegetation of terrestrial and aquatic environments. If pollutants enter the system, they are absorbed by plants and distributed in the food chain via plant consumption, mortality, and decomposition. The effect of oil on the growth and survival of vegetation in these environments is virtually unknown. The water hyacinth [Eichhornia crassipes (Mart.) Solms] has a pantropical distribution but is native to the Amazon, often growing in high-density populations in the floodplains where it plays an important role as shelter and food source for aquatic and terrestrial biota. The species is well known for its high capacity to absorb and tolerate high levels of heavy metal ions. To study the survival and response of water hyacinth under six different oil doses, ranging from 0 to 150 ml l(-1), and five exposure times (1, 5, 10, 15, and 20 days), young individuals distributed in a completely randomized design experiment composed of vessels with a single individual each were followed over a 50-day period (30-day acclimatization, 20 days under oil treatments). Growth parameters, biomass, visual changes in the plants, and pH were recorded at 1, 5, 10, 15, and 20 days. Increasing the time of oil exposure caused a decrease in biomass, ratio of live/dead biomass and length of leaves, and an increase in the number of dead leaves. Dose of oil and time of exposure

  16. Micromechanisms and Toughness for Cleavage Fracture of Steel,

    DTIC Science & Technology

    1986-06-01

    AD-A69 916 MICRONECHANISNS AND TOUGHNESS FOR CLEAVAGE FRACTURE OF 1/1 STEEL (U) BATTELLE MEMORIAL INST COLUMBUS OH A R ROSENFIELD ET AL. JUN 86 ARO...OF STEEL 6. PERFORMING ORG. REPORT NUMBER N/A 7. AUTHOR(e) 8. CONTRACT OR GRANT NUMBER(e) K A. R. Rosenfield and B. S. Majumdar DAAG29-85jOO35 9...decision, unless so 9. KEY WORDS (Continue on reveree eide It necesey atd Identify by block number) .L Steel , HSLA Fracture toughness . Ductile fracture

  17. Comparative fracture toughness of multilayer graphenes and boronitrenes.

    PubMed

    Wei, Xianlong; Xiao, Si; Li, Faxin; Tang, Dai-Ming; Chen, Qing; Bando, Yoshio; Golberg, Dmitri

    2015-01-14

    We report the comparative in situ fracture toughness testing on single-edge V/U-notched multilayer graphenes and boronitrenes in a high-resolution transmission electron microscope (HRTEM). The nanostructures of notch tips and fracture edges of the tested specimens are unambiguously resolved using HRTEM. By analyzing the notch tip stresses using finite element method, the fracture toughness of multilayer graphenes and boronitrenes is determined to be 12.0 ± 3.9 and 5.5 ± 0.7 MPa√m, respectively, taking into account the notch tip blunting effects.

  18. Processing and testing of high toughness silicon nitride ceramics

    NASA Technical Reports Server (NTRS)

    Tikare, Veena; Sanders, William A.; Choi, Sung R.

    1993-01-01

    High toughness silicon nitride ceramics were processed with the addition of small quantities of beta-Si3N4 whiskers in a commercially available alpha-Si3N4 powder. These whiskers grew preferentially during sintering resulting in large, elongated beta-grains, which acted to toughen the matrix by crack deflection and grain pullout. The fracture toughness of these samples seeded with beta-Si3N4 whiskers ranged from 8.7 to 9.5 MPa m(exp 0.5) depending on the sintering additives.

  19. Fracture toughness in SiC/Al composite material

    NASA Technical Reports Server (NTRS)

    Flom, Y.; Wu, S. B.; Arsenault, R. J.

    1989-01-01

    Crack initiation fracture toughness does not depend on SiC particle size. Crack growth fracture toughness increases as the size of the SiC particle increases. The fracture process is confined to a very narrow band and takes place within the matrix. In the case of composite reinforced with SiC particles of 20 microns and above, fracture of SiC begins to dominate. The matrix is influenced by a triaxial tension in the matrix and a high density of dislocations generated at SiC/Al interfaces due to the difference in coefficient of thermal expansion between SiC and the Al matrix.

  20. Cryogenic Properties of a New Tough-Strong Iron Alloy

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1977-01-01

    A program was undertaken to develop an iron-base alloy having a fracture toughness of 220 MPa. m superscript 1/2 with a corresponding yield stress of 1.4 GPa (200 ksi) at-196 C. An Fe-12Ni alloy was selected as the base alloy. Factors considered included reactive metal additions, effects of interstitial impurities, strengthening mechanisms, and weldability. The goals were met in an Fe-12Ni-0.5Al alloy strengthened by thermomechanical processing or by precipitate strengthening with 2 percent Cu. The alloy is weldable with the weld metal and heat affected zone in the postweld annealed condition having toughness equivalent to the base alloy.

  1. Fracture Toughness of Advanced Ceramics at Room Temperature.

    PubMed

    Quinn, George D; Salem, Jonathan; Bar-On, Isa; Cho, Kyu; Foley, Michael; Fang, Ho

    1992-01-01

    This report presents the results obtained by the five U.S. participating laboratories in the Versailles Advanced Materials and Standards (VAMAS) round-robin for fracture toughness of advanced ceramics. Three test methods were used: indentation fracture, indentation strength, and single-edge pre-cracked beam. Two materials were tested: a gas-pressure sintered silicon nitride and a zirconia toughened alumina. Consistent results were obtained with the latter two test methods. Interpretation of fracture toughness in the zirconia alumina composite was complicated by R-curve and environmentally-assisted crack growth phenomena.

  2. Fracture Toughness of Advanced Ceramics at Room Temperature

    PubMed Central

    Quinn, George D.; Salem, Jonathan; Bar-on, Isa; Cho, Kyu; Foley, Michael; Fang, Ho

    1992-01-01

    This report presents the results obtained by the five U.S. participating laboratories in the Versailles Advanced Materials and Standards (VAMAS) round-robin for fracture toughness of advanced ceramics. Three test methods were used: indentation fracture, indentation strength, and single-edge pre-cracked beam. Two materials were tested: a gas-pressure sintered silicon nitride and a zirconia toughened alumina. Consistent results were obtained with the latter two test methods. Interpretation of fracture toughness in the zirconia alumina composite was complicated by R-curve and environmentally-assisted crack growth phenomena. PMID:28053447

  3. Evidence for a time-dependent association between FOLR1 expression and survival from ovarian carcinoma: implications for clinical testing. An Ovarian Tumour Tissue Analysis consortium study

    PubMed Central

    Köbel, M; Madore, J; Ramus, S J; Clarke, B A; Pharoah, P D P; Deen, S; Bowtell, D D; Odunsi, K; Menon, U; Morrison, C; Lele, S; Bshara, W; Sucheston, L; Beckmann, M W; Hein, A; Thiel, F C; Hartmann, A; Wachter, D L; Anglesio, M S; Høgdall, E; Jensen, A; Høgdall, C; Kalli, K R; Fridley, B L; Keeney, G L; Fogarty, Z C; Vierkant, R A; Liu, S; Cho, S; Nelson, G; Ghatage, P; Gentry-Maharaj, A; Gayther, S A; Benjamin, E; Widschwendter, M; Intermaggio, M P; Rosen, B; Bernardini, M Q; Mackay, H; Oza, A; Shaw, P; Jimenez-Linan, M; Driver, K E; Alsop, J; Mack, M; Koziak, J M; Steed, H; Ewanowich, C; DeFazio, A; Chenevix-Trench, G; Fereday, S; Gao, B; Johnatty, S E; George, J; Galletta, L; Goode, E L; Kjær, S K; Huntsman, D G; Fasching, P A; Moysich, K B; Brenton, J D; Kelemen, L E

    2014-01-01

    Background: Folate receptor 1 (FOLR1) is expressed in the majority of ovarian carcinomas (OvCa), making it an attractive target for therapy. However, clinical trials testing anti-FOLR1 therapies in OvCa show mixed results and require better understanding of the prognostic relevance of FOLR1 expression. We conducted a large study evaluating FOLR1 expression with survival in different histological types of OvCa. Methods: Tissue microarrays composed of tumour samples from 2801 patients in the Ovarian Tumour Tissue Analysis (OTTA) consortium were assessed for FOLR1 expression by centralised immunohistochemistry. We estimated associations for overall (OS) and progression-free (PFS) survival using adjusted Cox regression models. High-grade serous ovarian carcinomas (HGSC) from The Cancer Genome Atlas (TCGA) were evaluated independently for association between FOLR1 mRNA upregulation and survival. Results: FOLR1 expression ranged from 76% in HGSC to 11% in mucinous carcinomas in OTTA. For HGSC, the association between FOLR1 expression and OS changed significantly during the years following diagnosis in OTTA (Pinteraction=0.01, N=1422) and TCGA (Pinteraction=0.01, N=485). In OTTA, particularly for FIGO stage I/II tumours, patients with FOLR1-positive HGSC showed increased OS during the first 2 years only (hazard ratio=0.44, 95% confidence interval=0.20–0.96) and patients with FOLR1-positive clear cell carcinomas (CCC) showed decreased PFS independent of follow-up time (HR=1.89, 95% CI=1.10–3.25, N=259). In TCGA, FOLR1 mRNA upregulation in HGSC was also associated with increased OS during the first 2 years following diagnosis irrespective of tumour stage (HR: 0.48, 95% CI: 0.25–0.94). Conclusions: FOLR1-positive HGSC tumours were associated with an increased OS in the first 2 years following diagnosis. Patients with FOLR1-negative, poor prognosis HGSC would be unlikely to benefit from anti-FOLR1 therapies. In contrast, a decreased PFS interval was observed for FOLR1

  4. Upper-nose temper phenomena and transition behavior of fracture toughness of 2. 25Cr-1Mo pressure vessel steel

    SciTech Connect

    Holzmann, M.; Man, J.; Vlach, B. . Academy of Sciences)

    1993-12-15

    A non-reversible upper-nose temper embrittlement (UNTE) which is characterized by transcrystalline cleavage could occur in low alloy steels when tempered or post-weld heat treated at temperatures ranging between 600 C to A[sub c1] for longer-time period. The deterioration of mechanical properties, in particular toughness, associated with this process, is a very relevant problem for fabricators of large components in petrochemical and power industry. One must be very careful when evaluating the embrittlement of the structure itself, using results of the Charpy test. The authors of the present work have reported in a recent paper that the cleavage fracture stress [sigma][sub CF], due to structural changes during temper treatment, has fallen steadily from the very beginning of tempering and a model has been suggested, explaining the transition behavior in the Charpy test. Even though the Charpy tests provide valuable information regarding impact toughness properties, the fracture toughness is a more exact material characteristic defining the fracture resistance properties. Therefore, the fracture toughness temperature curves, measured for a variety of tempered conditions, aim to reveal to what extent UNTE phenomena can influence the level and transition behavior of this material characteristic. Some representative results are given in the present paper.

  5. Interlaminar shear fracture toughness and fatigue thresholds for composite materials

    NASA Technical Reports Server (NTRS)

    Obrien, T. Kevin; Murri, Gretchen B.; Salpekar, Satish A.

    1987-01-01

    Static and cyclic end notched flexure tests were conducted on a graphite epoxy, a glass epoxy, and graphite thermoplastic to determine their interlaminar shear fracture toughness and fatigue thresholds for delamination in terms of limiting values of the mode II strain energy release rate, G-II, for delamination growth. The influence of precracking and data reduction schemes are discussed. Finite element analysis indicated that the beam theory calculation for G-II with the transverse shear contribution included was reasonably accurate over the entire range of crack lengths. Cyclic loading significantly reduced the critical G-II for delamination. A threshold value of the maximum cyclic G-II below which no delamination occurred after one million cycles was identified for each material. Also, residual static toughness tests were conducted on glass epoxy specimens that had undergone one million cycles without delamination. A linear mixed-mode delamination criteria was used to characterize the static toughness of several composite materials; however, a total G threshold criterion appears to characterize the fatigue delamination durability of composite materials with a wide range of static toughness.

  6. Interlaminar shear fracture toughness and fatigue thresholds for composite materials

    NASA Technical Reports Server (NTRS)

    O'Brien, T. Kevin; Murri, Gretchen B.; Salpekar, Satish A.

    1989-01-01

    Static and cyclic end notched flexure tests were conducted on a graphite epoxy, a glass epoxy, and graphite thermoplastic to determine their interlaminar shear fracture toughness and fatigue thresholds for delamination in terms of limiting values of the mode II strain energy release rate, G-II, for delamination growth. The influence of precracking and data reduction schemes are discussed. Finite element analysis indicated that the beam theory calculation for G-II with the transverse shear contribution included was reasonably accurate over the entire range of crack lengths. Cyclic loading significantly reduced the critical G-II for delamination. A threshold value of the maximum cyclic G-II below which no delamination occurred after one million cycles was identified for each material. Also, residual static toughness tests were conducted on glass epoxy specimens that had undergone one million cycles without delamination. A linear mixed-mode delamination criteria was used to characterize the static toughness of several composite materials; however, a total G threshold criterion appears to characterize the fatigue delamination durability of composite materials with a wide range of static toughness.

  7. Understanding and Supporting Adolescents' Mental Toughness in an Education Context

    ERIC Educational Resources Information Center

    McGeown, Sarah; Putwain, Dave; St. Clair-Thompson, Helen; Clough, Peter

    2017-01-01

    This study sought to explore the concept of mental toughness (comprising the attributes challenge, commitment, control, and confidence) from the perceptions of adolescents, to better understand their views on these attributes and the extent to which each were regarded as important within an educational setting. In total, 54 adolescents (31 female)…

  8. Impact Toughness of Ultrafine-Grained Interstitial-Free Steel

    NASA Astrophysics Data System (ADS)

    Saray, Onur; Purcek, Gencaga; Karaman, Ibrahim; Maier, Hans J.

    2012-11-01

    Impact toughness of an ultrafine-grained (UFG) interstitial-free (IF) steel produced by equal-channel angular extrusion/pressing (ECAE/P) at room temperature was investigated using Charpy impact tests. The UFG IF steel shows an improved combination of strength and impact toughness compared with the corresponding coarse-grained (CG) one. The CG IF steel samples underwent a transition in fracture toughness values with decreasing temperature because of a sudden change in fracture mode from microvoid coalescence (ductile) to cleavage (brittle) fracture. Grain refinement down to the submicron (≈320 nm) levels increased the impact energies in the upper shelf and lower shelf regions, and it considerably decreased the ductile-to-brittle transition temperature (DBTT) from 233 K (-40 °C) for the CG steel to approximately 183 K (-90 °C) for the UFG steel. Also, the sudden drop in DBTT with a small transition range for the CG sample changed to a more gradual decrease in energy for the UFG sample. The improvement in toughness after UFG formation was attributed to the combined effects of grain refinement and delamination and/or separation in the heavily deformed microstructure. Although an obvious change from the ductile fracture by dimples to the brittle fracture by cleavage was recognized at 233 K (-40 °C) for the CG steel, no fully brittle fracture occurred even at 103 K (-170 °C) in the UFG steel.

  9. Hypothesis: Bones Toughness Arises from the Suppression of Elastic Waves

    PubMed Central

    Davies, Benjamin; King, Alice; Newman, Peter; Minett, Andrew; Dunstan, Colin R.; Zreiqat, Hala

    2014-01-01

    Bone and other natural material exhibit a combination of strength and toughness that far exceeds that of synthetic structural materials. Bone's toughness is a result of numerous extrinsic and intrinsic toughening mechanisms that operate synergistically at multiple length scales to produce a tough material. At the system level however no theory or organizational principle exists to explain how so many individual toughening mechanisms can work together. In this paper, we utilize the concept of phonon localization to explain, at the system level, the role of hierarchy, material heterogeneity, and the nanoscale dimensions of biological materials in producing tough composites. We show that phonon localization and attenuation, using a simple energy balance, dynamically arrests crack growth, prevents the cooperative growth of cracks, and allows for multiple toughening mechanisms to work simultaneously in heterogeneous materials. In turn, the heterogeneous, hierarchal, and multiscale structure of bone (which is generic to biological materials such as bone and nacre) can be rationalized because of the unique ability of such a structure to localize phonons of all wavelengths. PMID:25518898

  10. Hypothesis: Bones Toughness Arises from the Suppression of Elastic Waves

    NASA Astrophysics Data System (ADS)

    Davies, Benjamin; King, Alice; Newman, Peter; Minett, Andrew; Dunstan, Colin R.; Zreiqat, Hala

    2014-12-01

    Bone and other natural material exhibit a combination of strength and toughness that far exceeds that of synthetic structural materials. Bone's toughness is a result of numerous extrinsic and intrinsic toughening mechanisms that operate synergistically at multiple length scales to produce a tough material. At the system level however no theory or organizational principle exists to explain how so many individual toughening mechanisms can work together. In this paper, we utilize the concept of phonon localization to explain, at the system level, the role of hierarchy, material heterogeneity, and the nanoscale dimensions of biological materials in producing tough composites. We show that phonon localization and attenuation, using a simple energy balance, dynamically arrests crack growth, prevents the cooperative growth of cracks, and allows for multiple toughening mechanisms to work simultaneously in heterogeneous materials. In turn, the heterogeneous, hierarchal, and multiscale structure of bone (which is generic to biological materials such as bone and nacre) can be rationalized because of the unique ability of such a structure to localize phonons of all wavelengths.

  11. On the in vitro fracture toughness of human dentin

    SciTech Connect

    Imbeni, V.; Nalla, R.K.; Bosi, C.; Kinney, J.H.; Ritchie, R.O.

    2002-02-05

    The in vitro fracture toughness of human dention has been reported to be of the order of 3 MPa sqrt m. This result, however is based on a single study for a single orientation, and furthermore involves notched, rather than fatigue precracked, test samples.

  12. 10 CFR Appendix G to Part 50 - Fracture Toughness Requirements

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... tests and all system leakage and hydrostatic pressure tests performed during the service life of the... material with regard to radiation damage. III. Fracture Toughness Tests A. To demonstrate compliance with... in accordance with the ASME Code and, for the beltline materials, the test requirements of appendix...

  13. The fracture toughness of octet-truss lattices

    NASA Astrophysics Data System (ADS)

    O'Masta, M. R.; Dong, L.; St-Pierre, L.; Wadley, H. N. G.; Deshpande, V. S.

    2017-01-01

    The only engineering materials with both high strength and toughness, and with densities less than 1000 kg m-3, are natural materials (woods) and some plastics. Cellular structures such as the octet lattice, when made from periodic arrangements of strong, low-density metallic trusses, are known to have high specific strengths and elastic moduli. However, much less is known of their resistance to fracture. Here we investigate the fracture toughness of a Ti-6Al-4V alloy octet-lattice truss structure manufactured using a 'snap-fit' method. The samples had densities between 360 and 855 kg m-3 (relative densities of 8-19%) and free truss lengths between 4 and 15 mm. Their fracture resistance was determined using the J-integral compliance method applied to single-edge notched bend specimens. The toughness is shown to increase linearly with the relative density and with the square root of the cell size, while the strength was confirmed to scale only with relative density and the strength of the solid. A moderate increase in resistance with crack length (an R-curve effect) was seen for the higher relative density and larger cell size samples. With a fracture toughness between 2 and 14 MPa m1/2 and a compressive strength between 20 and 70 MPa, these structures offer a new lightweight engineering material solution for use at temperatures up to 450 °C.

  14. 46 CFR 54.05-17 - Weld toughness test acceptance criteria.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Weld toughness test acceptance criteria. 54.05-17... PRESSURE VESSELS Toughness Tests § 54.05-17 Weld toughness test acceptance criteria. (a) For Charpy V-notch impact tests the energy absorbed in both the weld metal and heat affected zone impact tests in...

  15. 3D Printing: 3D Printing of Highly Stretchable and Tough Hydrogels into Complex, Cellularized Structures.

    PubMed

    Hong, Sungmin; Sycks, Dalton; Chan, Hon Fai; Lin, Shaoting; Lopez, Gabriel P; Guilak, Farshid; Leong, Kam W; Zhao, Xuanhe

    2015-07-15

    X. Zhao and co-workers develop on page 4035 a new biocompatible hydrogel system that is extremely tough and stretchable and can be 3D printed into complex structures, such as the multilayer mesh shown. Cells encapsulated in the tough and printable hydrogel maintain high viability. 3D-printed structures of the tough hydrogel can sustain high mechanical loads and deformations.

  16. 46 CFR 54.05-10 - Certification of material toughness tests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Certification of material toughness tests. 54.05-10... PRESSURE VESSELS Toughness Tests § 54.05-10 Certification of material toughness tests. (a) Plate material... pipe or tube may certify such material by reporting the results of tests of one set of Charpy...

  17. 46 CFR 54.05-10 - Certification of material toughness tests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Certification of material toughness tests. 54.05-10... PRESSURE VESSELS Toughness Tests § 54.05-10 Certification of material toughness tests. (a) Plate material... pipe or tube may certify such material by reporting the results of tests of one set of Charpy...

  18. 46 CFR 54.05-10 - Certification of material toughness tests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Certification of material toughness tests. 54.05-10... PRESSURE VESSELS Toughness Tests § 54.05-10 Certification of material toughness tests. (a) Plate material... pipe or tube may certify such material by reporting the results of tests of one set of Charpy...

  19. 46 CFR 54.05-10 - Certification of material toughness tests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Certification of material toughness tests. 54.05-10... PRESSURE VESSELS Toughness Tests § 54.05-10 Certification of material toughness tests. (a) Plate material... pipe or tube may certify such material by reporting the results of tests of one set of Charpy...

  20. 46 CFR 54.05-10 - Certification of material toughness tests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Certification of material toughness tests. 54.05-10... PRESSURE VESSELS Toughness Tests § 54.05-10 Certification of material toughness tests. (a) Plate material... pipe or tube may certify such material by reporting the results of tests of one set of Charpy...

  1. The feasibility of ranking material fracture toughness by ultrasonic attenuation measurements

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1975-01-01

    A preliminary study was conducted to assess the feasibility of ultrasonically ranking material fracture toughness. Specimens of two grades of maraging steel for which fracture toughness values were measured were subjected to ultrasonic probing. The slope of the attenuation coefficient versus frequency curve was empirically correlated with the plane strain fracture toughness value for each grade of steel.

  2. The feasibility of ranking material fracture toughness by ultrasonic attenuation measurements

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1975-01-01

    A preliminary study was conducted to assess the feasibility of ultrasonically ranking material fracture toughness. Specimens of two grades of maraging steel for which fracture toughness values were measured were subjected to ultrasonic probing. The slope of the attenuation coefficient vs frequency curve was empirically correlated with the plane strain fracture toughness value for each grade of steel.

  3. Shear Strength and Interfacial Toughness Characterization of Sapphire-Epoxy Interfaces for Nacre-Inspired Composites.

    PubMed

    Behr, Sebastian; Jungblut, Laura; Swain, Michael V; Schneider, Gerold A

    2016-10-12

    The common tensile lap-shear test for adhesive joints is inappropriate for brittle substrates such as glasses or ceramics where stress intensifications due to clamping and additional bending moments invalidate results. Nevertheless, bonding of glasses and ceramics is still important in display applications for electronics, in safety glass and ballistic armor, for dental braces and restoratives, or in recently developed bioinspired composites. To mechanically characterize adhesive bondings in these fields nonetheless, a novel approach based on the so-called Schwickerath test for dental sintered joints is used. This new method not only matches data from conventional analysis but also uniquely combines the accurate determination of interfacial shear strength and toughness in one simple test. The approach is verified for sapphire-epoxy joints that are of interest for bioinspired composites. For these, the procedure not only provides quantitative interfacial properties for the first time, it also exemplarily suggests annealing of sapphire at 1000 °C for 10 h for mechanically and economically effective improvements of the interfacial bond strength and toughness. With increases of strength and toughness from approximately 8 to 29 MPa and from 2.6 to 35 J/m(2), respectively, this thermal modification drastically enhances the properties of unmodified sapphire-epoxy interfaces. At the same time, it is much more convenient than wet-chemical approaches such as silanization. Hence, besides the introduction of a new testing procedure for adhesive joints of brittle or expensive substrates, a new and facile annealing process for improvements of the adhesive properties of sapphire is suggested and quantitative data for the mechanical properties of sapphire-epoxy interfaces that are common in synthetic nacre-inspired composites are provided for the first time.

  4. Variability and Anisotropy of Fracture Toughness of Cortical Bone Tissue

    NASA Astrophysics Data System (ADS)

    Abdel-Wahab, Adel; Nordin, Norhaziqah; Silberschmidt, Vadim

    2012-08-01

    Bones form protective and load-bearing framework of the body. Therefore, their structural integrity is vital for the quality of life. Unfortunately, bones can only sustain a load until a certain limit, beyond which they fail. Therefore, it is essential to study their mechanical and fracture behaviours in order to get an in-depth understanding of the origins of its fracture resistance that, in turn, can assist diagnosis and prevention of bone's trauma. This can be achieved by studying mechanical properties of bone, such as its fracture toughness. Generally, most of bone fractures occur for long bones that consist mostly of cortical bone. Therefore, in this study, only a cortical bone tissue was studied. Since this tissue has an anisotropic behaviour and possesses hierarchical and complex structure, in this paper, an experimental analysis for the fracture toughness of cortical bone tissue is presented in terms of J-integral. The data was obtained using single-edge-notch bending (SENB) cortical specimens of bone tested in a three-point bending setup. Variability of values of fracture toughness was investigated by testing specimens cut from different cortex positions of bovine femur called anterior, posterior, medial, and lateral. In addition, anisotropy ratios of fracture toughness were considered by examining specimens cut from three different orientations: longitudinal, transverse and radial. Moreover, in order to link cortical bone fracture mechanisms with its underlying microstructure, fracture surfaces of specimens from different cortices and along different orientations were studied. Experimental results of this study provide a clear understanding of both variability and anisotropy of cortical bone tissue with regard to its fracture toughness.

  5. A strong integrated strength and toughness artificial nacre based on dopamine cross-linked graphene oxide.

    PubMed

    Cui, Wei; Li, Mingzhu; Liu, Jiyang; Wang, Ben; Zhang, Chuck; Jiang, Lei; Cheng, Qunfeng

    2014-09-23

    Demands of the strong integrated materials have substantially increased across various industries. Inspired by the relationship of excellent integration of mechanical properties and hierarchical nano/microscale structure of the natural nacre, we have developed a strategy for fabricating the strong integrated artificial nacre based on graphene oxide (GO) sheets by dopamine cross-linking via evaporation-induced assembly process. The tensile strength and toughness simultaneously show 1.5 and 2 times higher than that of natural nacre. Meanwhile, the artificial nacre shows high electrical conductivity. This type of strong integrated artificial nacre has great potential applications in aerospace, flexible supercapacitor electrodes, artificial muscle, and tissue engineering.

  6. Simultaneous enhancement of toughness, ductility, and strength of nanocrystalline ceramics at high strain-rates

    SciTech Connect

    Mo Yifei; Szlufarska, Izabela

    2007-04-30

    Molecular dynamics simulations of tensile testing have been performed on nc-SiC. Reduction of grain size promotes simultaneous enhancement of ductility, toughness, and strength. nc-SiC fails by intergranular fracture preceded by atomic level necking. Conventionally, high strain-rate deformations of ceramics are limited by diffusion time scales, since diffusion prevents premature cavitation and failure. The authors report a nondiffusional mechanism for suppressing premature cavitation, which is based on unconstrained plastic flow at grain boundaries. Based on the composite's rule of mixture, they estimate Young's modulus of random high-angle grain boundaries in nc-SiC to be about 130 GPa.

  7. Glioblastoma brain tumours: estimating the time from brain tumour initiation and resolution of a patient survival anomaly after similar treatment protocols.

    PubMed

    Murray, J D

    2012-01-01

    A practical mathematical model for glioblastomas (brain tumours), which incorporates the two key parameters of tumour growth, namely the cancer cell diffusion and the cell proliferation rate, has been shown to be clinically useful and predictive. Previous studies explain why multifocal recurrence is inevitable and show how various treatment scenarios have been incorporated in the model. In most tumours, it is not known when the cancer started. Based on patient in vivo parameters, obtained from two brain scans, it is shown how to estimate the time, after initial detection, when the tumour started. This is an input of potential importance in any future controlled clinical study of any connection between cell phone radiation and brain tumour incidence. It is also used to estimate more accurately survival times from detection. Finally, based on patient parameters, the solution of the model equation of the tumour growth helps to explain why certain patients live longer than others after similar treatment protocols specifically surgical resection (removal) and irradiation.

  8. The Transcriptional Response of Neurotrophins and Their Tyrosine Kinase Receptors in Lumbar Sensorimotor Circuits to Spinal Cord Contusion is Affected by Injury Severity and Survival Time

    PubMed Central

    Hougland, M. Tyler; Harrison, Benjamin J.; Magnuson, David S. K.; Rouchka, Eric C.; Petruska, Jeffrey C.

    2013-01-01

    Traumatic spinal cord injury (SCI) results in changes to the anatomical, neurochemical, and physiological properties of cells in the central and peripheral nervous system. Neurotrophins, acting by binding to their cognate Trk receptors on target cell membranes, contribute to modulation of anatomical, neurochemical, and physiological properties of neurons in sensorimotor circuits in both the intact and injured spinal cord. Neurotrophin signaling is associated with many post-SCI changes including maladaptive plasticity leading to pain and autonomic dysreflexia, but also therapeutic approaches such as training-induced locomotor improvement. Here we characterize expression of mRNA for neurotrophins and Trk receptors in lumbar dorsal root ganglia (DRG) and spinal cord after two different severities of mid-thoracic injury and at 6 and 12 weeks post-SCI. There was complex regulation that differed with tissue, injury severity, and survival time, including reversals of regulation between 6 and 12 weeks, and the data suggest that natural regulation of neurotrophins in the spinal cord may continue for months after birth. Our assessments determined that a coordination of gene expression emerged at the 12-week post-SCI time point and bioinformatic analyses address possible mechanisms. These data can inform studies meant to determine the role of the neurotrophin signaling system in post-SCI function and plasticity, and studies using this signaling system as a therapeutic approach. PMID:23316162

  9. Time to unrelated donor leukocyte infusion is longer, but incidence of GVHD and overall survival are similar for recipients of unrelated DLI compared to matched sibling DLI.

    PubMed

    Kumar, Anita J; Vassilev, Pavel; Loren, Alison W; Luger, Selina M; Reshef, Ran; Gill, Saar; Smith, Jacqueline; Goldstein, Steven C; Hexner, Elizabeth; Stadtmauer, Edward A; Porter, David; Frey, Noelle V

    2016-06-01

    Donor leukocyte infusion (DLI) is used to treat relapsed leukemia after allogeneic hematopoietic stem cell transplant (HCT). Data comparing outcomes after unrelated DLI (uDLI) to matched sibling DLI (msDLI) are scant. We performed a retrospective analysis to assess differences in time to administer uDLI versus msDLI, and impact on outcomes. Fifty three patients with relapsed acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), or myelodysplastic syndrome (MDS) after allogeneic HCT received uDLI (n = 18) or msDLI (n = 35) from 2000 to 2011. Median time from relapse to uDLI request was 15 days (range 0-66). Median time from relapse to uDLI was 56 days versus 40 days for msDLI patients (p = 0.034). 35% of msDLI and 44% of uDLI patients developed acute GVHD (p = 0.50). There was no significant difference in Grade C/D GVHD among uDLI and msDLI (28% and 21%, p = 0.58) or median OS after DLI between uDLI and msDLI (95 versus 75 days, p = 0.76). For patients with relapsed acute leukemia and MDS after allogeneic HCT, time from relapse to uDLI was longer than to msDLI, but incidence of GVHD and overall survival were similar. Access to uDLI does not appear to be a barrier to DLI administration. Outcomes unfortunately remain poor regardless of donor source.

  10. Survival rate and expression of Heat-shock protein 70 and Frost genes after temperature stress in Drosophila melanogaster lines that are selected for recovery time from temperature coma.

    PubMed

    Udaka, Hiroko; Ueda, Chiaki; Goto, Shin G

    2010-12-01

    In this study, we investigated the physiological mechanisms underlying temperature tolerance using Drosophila melanogaster lines with rapid, intermediate, or slow recovery from heat or chill coma that were established by artificial selection or by free recombination without selection. Specifically, we focused on the relationships among their recovery from heat or chill coma, survival after severe heat or cold, and survival enhanced by rapid cold hardening (RCH) or heat hardening. The recovery time from heat coma was not related to the survival rate after severe heat. The line with rapid recovery from chill coma showed a higher survival rate after severe cold exposure, and therefore the same mechanisms are likely to underlie these phenotypes. The recovery time from chill coma and survival rate after severe cold were unrelated to RCH-enhanced survival. We also examined the expression of two genes, Heat-shock protein 70 (Hsp70) and Frost, in these lines to understand the contribution of these stress-inducible genes to intraspecific variation in recovery from temperature coma. The line showing rapid recovery from heat coma did not exhibit higher expression of Hsp70 and Frost. In addition, Hsp70 and Frost transcription levels were not correlated with the recovery time from chill coma. Thus, Hsp70 and Frost transcriptional regulation was not involved in the intraspecific variation in recovery from temperature coma.

  11. Directionally Solidified NiAl-Based Alloys Studied for Improved Elevated-Temperature Strength and Room-Temperature Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2000-01-01

    Efforts are underway to replace superalloys used in the hot sections of gas turbine engines with materials possessing better mechanical and physical properties. Alloys based on the intermetallic NiAl have demonstrated potential; however, they generally suffer from low fracture resistance (toughness) at room temperature and from poor strength at elevated temperatures. Directional solidification of NiAl alloyed with both Cr and Mo has yielded materials with useful toughness and elevated-temperature strength values. The intermetallic alloy NiAl has been proposed as an advanced material to extend the maximum operational temperature of gas turbine engines by several hundred degrees centigrade. This intermetallic alloy displays a lower density (approximately 30-percent less) and a higher thermal conductivity (4 to 8 times greater) than conventional superalloys as well as good high-temperature oxidation resistance. Unfortunately, unalloyed NiAl has poor elevated temperature strength (approximately 50 MPa at 1027 C) and low room-temperature fracture toughness (about 5 MPa). Directionally solidified NiAl eutectic alloys are known to possess a combination of high elevated-temperature strength and good room-temperature fracture toughness. Research has demonstrated that a NiAl matrix containing a uniform distribution of very thin Cr plates alloyed with Mo possessed both increased fracture toughness and elevated-temperature creep strength. Although attractive properties were obtained, these alloys were formed at low growth rates (greater than 19 mm/hr), which are considered to be economically unviable. Hence, an investigation was warranted of the strength and toughness behavior of NiAl-(Cr,Mo) directionally solidified at faster growth rates. If the mechanical properties did not deteriorate with increased growth rates, directional solidification could offer an economical means to produce NiAl-based alloys commercially for gas turbine engines. An investigation at the NASA Glenn

  12. Time to Let Go of the Illusion that Psychotherapy Extends the Survival of Cancer Patients: Reply to Kraemer, Kuchler, and Spiegel (2009)

    ERIC Educational Resources Information Center

    Coyne, James C.; Thombs, Brett D.; Stefanek, Michael; Palmer, Steven C.

    2009-01-01

    Replies to comments from Kraemer, Kuchler, and Spiegel on the authors original article Psychotherapy and survival in cancer: The conflict between hope and evidence. The authors recently reviewed evidence related to the notion that psychotherapy extends survival in cancer patients (J. C. Coyne, M. Stefanek, & S. C. Palmer, 2007). The authors found…

  13. Non-AIDS defining cancers in the D:A:D Study - time trends and predictors of survival: a cohort study

    PubMed Central

    2013-01-01

    Background Non-AIDS defining cancers (NADC) are an important cause of morbidity and mortality in HIV-positive individuals. Using data from a large international cohort of HIV-positive individuals, we described the incidence of NADC from 2004–2010, and described subsequent mortality and predictors of these. Methods Individuals were followed from 1st January 2004/enrolment in study, until the earliest of a new NADC, 1st February 2010, death or six months after the patient’s last visit. Incidence rates were estimated for each year of follow-up, overall and stratified by gender, age and mode of HIV acquisition. Cumulative risk of mortality following NADC diagnosis was summarised using Kaplan-Meier methods, with follow-up for these analyses from the date of NADC diagnosis until the patient’s death, 1st February 2010 or 6 months after the patient’s last visit. Factors associated with mortality following NADC diagnosis were identified using multivariable Cox proportional hazards regression. Results Over 176,775 person-years (PY), 880 (2.1%) patients developed a new NADC (incidence: 4.98/1000PY [95% confidence interval 4.65, 5.31]). Over a third of these patients (327, 37.2%) had died by 1st February 2010. Time trends for lung cancer, anal cancer and Hodgkin’s lymphoma were broadly consistent. Kaplan-Meier cumulative mortality estimates at 1, 3 and 5 years after NADC diagnosis were 28.2% [95% CI 25.1-31.2], 42.0% [38.2-45.8] and 47.3% [42.4-52.2], respectively. Significant predictors of poorer survival after diagnosis of NADC were lung cancer (compared to other cancer types), male gender, non-white ethnicity, and smoking status. Later year of diagnosis and higher CD4 count at NADC diagnosis were associated with improved survival. The incidence of NADC remained stable over the period 2004–2010 in this large observational cohort. Conclusions The prognosis after diagnosis of NADC, in particular lung cancer and disseminated cancer, is poor but has improved

  14. Neuroblastoma: A Tough Nut to Crack.

    PubMed

    Speleman, Frank; Park, Julie R; Henderson, Tara O

    2016-01-01

    Neuroblastoma, an embryonal tumor arising from neural crest-derived progenitor cells, is the most common solid tumor in childhood, with more than 700 cases diagnosed per year in the United States. In the past several decades, significant advances have been made in the treatment of neuroblastoma. Treatment advances reflect improved understanding of the biology of neuroblastoma. Although amplification of MYCN was discovered in the early 1980s, our understanding of neuroblastoma oncogenesis has advanced in the last decade as a result of high-throughput genomic analysis, exome and whole-genome sequencing, genome-wide association studies, and synthetic lethal drug screens. Our refined understanding of neuroblastoma biology and genetics is reflected in improved prognostic stratification and appropriate tailoring of therapy in recent clinical trials. Moreover, for high-risk neuroblastoma, a disease that was uniformly fatal 3 decades ago, recent clinical trials incorporating autologous hematopoietic transplant and immunotherapy utilizing anti-GD2 antibody plus cytokines have shown improved event-free and overall survival. These advances have resulted in a growing population of long-term survivors of neuroblastoma. Examination of the late effects and second malignant neoplasms (SMNs) in both older generations of survivors and more recently treated survivors will inform both design of future trials and surveillance guidelines for long-term follow-up. As a consequence of advances in understanding of the biology of neuroblastoma, successful clinical trials, and refined understanding of the late effects and SMNs of survivors, the promise of precision medicine is becoming a reality for patients with neuroblastoma.

  15. The survival of human skin stored by refrigeration at 4 degrees C in McCoy's 5A medium: does oxygenation of the medium improve storage time?

    PubMed

    DeBono, R; Rao, G S; Berry, R B

    1998-07-01

    To establish the viable storage time of human skin stored by refrigeration at 4 degrees C in McCoy's 5A medium and to establish whether oxygenating the medium improves the viable storage time, the following experiment was conducted. Eighty discs of human split-thickness skin graft, each 3 mm in diameter, were stored in 40 sterile sealable containers under four different conditions: in 0.9% saline, in McCoy's 5A medium, in oxygenated McCoy's 5A medium, and in carbon dioxide supplemented McCoy's 5A medium. Skin graft viability was assessed using tissue culture. Skin stored in saline was viable for only 1 week, whereas skin stored in McCoy's 5A medium and in oxygenated McCoy's 5A medium was viable for 4 weeks. Skin stored in carbon dioxide supplemented McCoy's 5A solution did not even survive the first week. These findings show that McCoy's 5A medium allows at least 4 weeks of viable human skin storage by refrigeration at 4 degrees C. Furthermore, oxygenating the medium does not seem to improve the viable storage time, and carbon dioxide supplementation is detrimental. The advantages of skin storage by refrigeration and the implications of the above findings are discussed. A clinical case in which split-thickness skin was stored for approximately 5 weeks and still resulted in good graft take is quoted as an example of our experience with the use of McCoy's 5A medium.

  16. AN INNOVATIVE TECHNIQUE FOR THIN FILM INTERFACE TOUGHNESS RESEARCH

    SciTech Connect

    Wang, J.J.

    2004-11-01

    A material configuration of central importance in microelectronics, optoelectronics, and thermal barrier coating technology is a thin or thick film of one material deposited onto a substrate of a different material. Fabrication of such a structure inevitably gives rise to stress in the film due to lattice mismatch, differing coefficients of thermal expansion, chemical reactions, or other physical effects. Therefore, in general, the weakest link in this composite system often resides at the interface between the film and substrate. In order to make multi-layered electronic devices and structural composites with long-term reliability, the fracture behavior of the material interfaces must be known. Unfortunately, none of the state-of-the-art testing methods for evaluating interface fracture toughness is fully conformed to fracture mechanics theory, as is evident from the severe scatter in the existing data and the procedure dependence in film/coating evaluation methods. This project is intended to address the problems associated with this deficiency and offers an innovative testing procedure for the determination of interface fracture toughness applicable to coating materials in general. This new approach and the associated bi-material fracture mechanics development proposed for evaluating interface fracture toughness are described herein. The effort includes development of specimen configuration and related instrumentation set-up, testing procedures, postmortem examination, and analytical evaluation. A spiral notch torsion fracture toughness test system was utilized. The objective of the testing procedure described is to enable the development of new coating materials by providing a reliable method for use in assessing their performance. This innovative technology for measuring interface toughness was demonstrated for oxide scales formed on high-temperature alloys of MA956. The estimated energy release rate (in terms of J-integral) at the interface of the alumina

  17. The Design and Analysis of Salmonid Tagging Studies in the Columbia Basin : Volume XVII : Effects of Ocean Covariates and Release Timing on First Ocean-Year Survival of Fall Chinook Salmon from Oregon and Washington Coastal Hatcheries.

    SciTech Connect

    Burgess, Caitlin; Skalski, John R.

    2001-05-01

    Effects of oceanographic conditions, as well as effects of release-timing and release-size, on first ocean-year survival of subyearling fall chinook salmon were investigated by analyzing CWT release and recovery data from Oregon and Washington coastal hatcheries. Age-class strength was estimated using a multinomial probability likelihood which estimated first-year survival as a proportional hazards regression against ocean and release covariates. Weight-at-release and release-month were found to significantly effect first year survival (p < 0.05) and ocean effects were therefore estimated after adjusting for weight-at-release. Negative survival trend was modeled for sea surface temperature (SST) during 11 months of the year over the study period (1970-1992). Statistically significant negative survival trends (p < 0.05) were found for SST during April, June, November and December. Strong pairwise correlations (r > 0.6) between SST in April/June, April/November and April/December suggest the significant relationships were due to one underlying process. At higher latitudes (45{sup o} and 48{sup o}N), summer upwelling (June-August) showed positive survival trend with survival and fall (September-November) downwelling showed positive trend with survival, indicating early fall transition improved survival. At 45{sup o} and 48{sup o}, during spring, alternating survival trends with upwelling were observed between March and May, with negative trend occurring in March and May, and positive trend with survival occurring in April. In January, two distinct scenarios of improved survival were linked to upwelling conditions, indicated by (1) a significant linear model effect (p < 0.05) showing improved survival with increasing upwelling, and (2) significant bowl-shaped curvature (p < 0.05) of survival with upwelling. The interpretation of the effects is that there was (1) significantly improved survival when downwelling conditions shifted to upwelling conditions in January (i

  18. Variations of motility and survival with storage time at 4°C of epididymal spermatozoa Ouled-Djellal breed rams in Eastern Algeria

    PubMed Central

    Safsaf, B.; Belkadi, S.; Belkacem, L.; Mamache, B.; Tlidjane, M.

    2015-01-01

    Aim: The aim of this study was to evaluate some reproduction performances in Ouled-Djellal rams. Materials and Methods: This study involved genital organs removed after slaughter from 54 rams at the municipal slaughterhouse of Batna (East Algeria). Results: The measurements of survival and mobility of epididymal sperm followed at 0, 24, 48 and 72 h after collection, revealed significant (p<0.05) to highly significant differences (p>0.001) according to time. Thus, concerning the sperm motility the values were 91.00±2.40%, 89.20±2.40%, 77.00±6.20% and 62.60±1.20% at 0, 24, 48 and 72 h, respectively. Indeed, in live sperm, the viability rates were 82.15±1.48%, 77.67±1.74%, 66.56±1.95% and 52.30±1.46% at 0, 24, 48 and 72 h, respectively. Conclusion: This study revealed that epididymal spermatozoa stored at 04°C for 72 h kept their mobility and vitality at nearly a half of their the original parameters. PMID:27047092

  19. The vitamin D analogue EB 1089 prevents skeletal metastasis and prolongs survival time in nude mice transplanted with human breast cancer cells.

    PubMed

    El Abdaimi, K; Dion, N; Papavasiliou, V; Cardinal, P E; Binderup, L; Goltzman, D; Ste-Marie, L G; Kremer, R

    2000-08-15

    1,25-Dihydroxyvitamin D has potent antiproliferative and anti-invasive properties in vitro in cancer cells. However, its calcemic effect in vivo limits its therapeutic applications. Here, we report the efficacy of EB 1089, a low calcemic analogue of vitamin D, on the development of osteolytic bone metastases after intracardiac injection of the human breast cancer cell line MDA-MB-231 in nude mice. Animals injected with tumor cells were implanted simultaneously with osmotic minipumps containing either EB 1089 or vehicle. Both groups remained normocalcemic for the duration of the experiment. The total number of bone metastases, the mean surface area of osteolytic lesions, and tumor burden within bone per animal were markedly decreased in EB1089-treated mice. Furthermore, longitudinal analysis revealed that mice treated with EB1089 displayed a marked increase in survival and developed fewer bone lesions and less hind limb paralysis over time as compared with untreated animals. These results suggest that EB1089 may be beneficial in the prevention of metastatic bone lesions associated with human breast cancer.

  20. Effect of growth on the thermal resistance and survival of Salmonella Tennessee and Oranienburg in peanut butter, measured by a new thin-layer thermal death time device.

    PubMed

    Keller, Susanne E; Grasso, Elizabeth M; Halik, Lindsay A; Fleischman, Gregory J; Chirtel, Stuart J; Grove, Stephen F

    2012-06-01

    In published data the thermal destruction of Salmonella species in peanut butter deviates from pseudo-first-order kinetics. The reasons for such deviation are unknown. This study examined both the method used to measure the thermal destruction rate and the method of growth of the microorganisms to explain variations in destruction kinetics. Growth on a solid matrix results in a different physiological state that may provide greater resistance to adverse environments. In this study, Salmonella Tennessee and Oranienburg were grown for 24 h at 37°C under aerobic conditions in broth and agar media to represent planktonic and sessile cell growth, respectively. Peanut butter was held at 25°C and tested for Salmonella levels immediately after inoculation and at various time intervals up to 2 weeks. Thermal resistance was measured at 85°C by use of a newly developed thin-layer metal sample holder. Although thermal heat transfer through the metal device resulted in longer tau values than those obtained with plastic bags (32.5 ± 0.9 versus 12.4 ± 1.9 s), the bags have a relative variability of about 15 % compared with about 3 % in the plates, allowing improved uniformity of sample treatment. The two serovars tested in the thin-layer device showed similar overall thermal resistance levels in peanut butter regardless of growth in sessile or planktonic states. However, thermal destruction curves from sessile cultures exhibited greater linearity than those obtained from planktonic cells (P = 0.0198 and 0.0047 for Salmonella Oranienburg and Salmonella Tennessee, respectively). In addition, both Salmonella serovars showed significantly higher survival in peanut butter at 25°C when originally grown on solid media (P = 0.001) with a <1-log loss over 2 weeks as opposed to a 1- to 2-log loss when grown in liquid culture. Consequently, the use of cells grown on solid media may more accurately assess the survival of Salmonella at different temperatures in a low

  1. Solute Enhanced Strain Hardening of Aluminum Alloys to Achieve Improved Combinations of Strength and Toughness

    NASA Astrophysics Data System (ADS)

    Hovanec, Christopher James

    2011-12-01

    The feasibility of achieving improved combinations of strength and toughness in aluminum alloy 2524 through solute enhanced strain hardening (SESH) has been explored in this study and shown to be viable. The effectiveness of SESH is directly dependent on the strain hardening rate (SHR) of the material being processed. Aluminum alloy 2524 naturally ages to the T4-temper after solution heat treating and quenching. The SHR of strain free and post cold rolled material as a function of natural aging time has been measured by means of simple compression. It has been determined that the SHR of AA2524 is more effective with solute in solution rather than clustered into GP zones. It has also been shown that the typical rapid formation of GP zones at room temperature (natural aging) is inhibited by moderate cold rolling strains (□CR ≥ 0.2) through dislocation aided vacancy annihilation. The practical limitations of quenching rate have been determined using hardness and eddy current electrical conductivity measurements. It has been shown that too slow of a quench rate results in solute being lost to both the formation of GP zones and embrittling precipitates during the quench, while too rapid of a quench rate results in mid-plane cracking of the work piece during the SESH processing. The mid-plane cracking was overcome by using an uphill quenching procedure to relieve residual stresses within the work piece. Aluminum alloy 2524 strengthened through SESH to a yield strength 11% greater than that in the T6-Temper exhibits: equivalent toughness, 5% greater UTS, 1% greater elongation, 7% greater R.A., and absorbs 15% more energy during tensile testing. At yield strengths comparable to published data for 2x24 alloys, the SESH 2524 exhibited up to a 60% increase in fracture toughness. The fractured surfaces of the SESH material exhibited transgranular dimpled rupture as opposed to the grain boundary ductile fracture (GBPF) observed in the artificially aged material.

  2. Multiparameter structural optimization of single-walled carbon nanotube composites: toward record strength, stiffness, and toughness.

    PubMed

    Shim, Bong Sup; Zhu, Jian; Jan, Edward; Critchley, Kevin; Ho, Szushen; Podsiadlo, Paul; Sun, Kai; Kotov, Nicholas A

    2009-07-28

    Efficient coupling of mechanical properties of SWNTs with the matrix leading to the transfer of unique mechanical properties of SWNTs to the macroscopic composites is a tremendous challenge of today's materials science. The typical mechanical properties of known SWNT composites, such as strength, stiffness, and toughness, are assessed in an introductory survey where we focused on concrete numerical parameters characterizing mechanical properties. Obtaining ideal stress transfer will require fine optimization of nanotube-polymer interface. SWNT nanocomposites were made here by layer-by-layer (LBL) assembly with poly(vinyl alcohol) (PVA), and the first example of optimization in respect to key parameters determining the connectivity at the graphene-polymer interface, namely, degree of SWNT oxidation and cross-linking chemistry, was demonstrated. The resulting SWNT-PVA composites demonstrated tensile strength (σ(ult)) = 504.5 ± 67.3 MPa, stiffness (E) = 15.6 ± 3.8 GPa, and toughness (K) = 121.2 ± 19.2 J/g with maximum values recorded at σ(ult) = 600.1 MPa, E = 20.6 GPa, and K = 152.1 J/g. This represents the strongest and stiffest nonfibrous SWNT composites made to date outperforming other bulk composites by 2-10 times. Its high performance is attributed to both high nanotube content and efficient stress transfer. The resulting LBL composite is also one of the toughest in this category of materials and exceeding the toughness of Kevlar by 3-fold. Our observation suggests that the strengthening and toughening mechanism originates from the synergistic combination of high degree of SWNT exfoliation, efficient SWNT-PVA binding, crack surface roughening, and fairly efficient distribution of local stress over the SWNT network. The need for a multiscale approach in designing SWNT composites is advocated.

  3. RealGasBrine v1.0 option of TOUGH+ v1.5

    SciTech Connect

    Moridis, George

    2015-02-27

    RealGasBrine v1.0 is a numerical code that for the simulation of the behavior of gas-bearing porous and/fractured geologic media. It is an option of TOUGH+ v1.5 [Moridis, 2014], a successor to the TOUGH2 [Pruess et al., 1999; 2012] family of codes for multi-component, multiphase ?uid and heat ?ow developed at the Lawrence Berkeley National Laboratory. RealGasBrine v1.0 needs the TOUGH+ v1.5 core code in order to compile and execute. It is written in standard FORTRAN 95/2003, and can be run on any computational platform (workstation, PC, Macintosh) for which such compilers are available. RealGasBrine v1.0 describes the non-isothermal two- (for pure water) or three-phase (for brine) flow of an aqueous phase and a real gas mixture in a gas-bearing medium, with a particular focus in ultra-tight (such as tight-sand and shale gas) systems. Up to 12 individual real gases can be tracked, and salt can precipitate as solid halite. The capabilities of the code include coupled flow and thermal effects, real gas behavior, Darcy and non-Darcy flow, several isotherm options of gas sorption onto the grains of the porous media, complex fracture descriptions, gas solubility into water, and geomechanical effects on flow properties. RealGasBrine v1.0 allows the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in any problem involving the flow of gases in geologic media, including the geologic storage of greenhouse gas mixtures, the behavior of geothermal reservoirs with multi-component condensable (H2O and CO2) and non-condensable gas mixtures, the transport of water and released H2 in nuclear waste storage applications, etc.

  4. Fracture toughness of brittle materials determined with chevron notch specimens

    NASA Technical Reports Server (NTRS)

    Shannon, J. L., Jr.; Bubsey, R. T.; Pierce, W. S.; Munz, D.

    1981-01-01

    Short bar, short rod, and four-point-bend chevron-notch specimens were used to determine the plane strain fracture toughness of hot-pressed silicon nitride and sintered aluminum oxide brittle ceramics. The unique advantages of this specimen type are: (1) the production of a sharp natural crack during the early stage of test loading, so that no precracking is required, and (2) the load passes through a maximum at a constant, material-independent crack length-to-width ratio for a specific geometry, so that no post-test crack measurement is required. The plane strain fracture toughness is proportional to the maximum test load and functions of the specimen geometry and elastic compliance. Although results obtained for silicon nitride are in good mutual agreement and relatively free of geometry and size effects, aluminum oxide results were affected in both these respects by the rising crack growth resistance curve of the material.

  5. Mental Toughness in Competitive Tennis: Relationships with Resilience and Stress

    PubMed Central

    Cowden, Richard G.; Meyer-Weitz, Anna; Oppong Asante, Kwaku

    2016-01-01

    The present study investigated the relationships between mental toughness (MT), resilience, and stress among competitive South African tennis players. A total of 351 tennis players participating at various competitive standards completed the Sports Mental Toughness Questionnaire, the Resilience Scale for Adults, and a modified version of the Recovery-Stress Questionnaire for Athletes. The results indicated that total MT was positively associated with total resilience (r = 0.59), but negatively associated with total stress (r = -0.44). The resilience subscales of perception of self, perception of future, social competence, and social resources, but not family cohesion, significantly predicted total MT (R2 = 0.35). Both total resilience and total MT significantly predicted total stress (R2 = 0.21). Based on the findings, interrelations between MT and resilience are explored, implications outlined, and additional research is suggested to ascertain the contextual relevance and outcomes associated with each construct in sport. PMID:27014132

  6. Versatile Molding Process for Tough Cellulose Hydrogel Materials

    NASA Astrophysics Data System (ADS)

    Kimura, Mutsumi; Shinohara, Yoshie; Takizawa, Junko; Ren, Sixiao; Sagisaka, Kento; Lin, Yudeng; Hattori, Yoshiyuki; Hinestroza, Juan P.

    2015-11-01

    Shape-persistent and tough cellulose hydrogels were fabricated by a stepwise solvent exchange from a homogeneous ionic liquid solution of cellulose exposure to methanol vapor. The cellulose hydrogels maintain their shapes under changing temperature, pH, and solvents. The micrometer-scale patterns on the mold were precisely transferred onto the surface of cellulose hydrogels. We also succeeded in the spinning of cellulose hydrogel fibers through a dry jet-wet spinning process. The mechanical property of regenerated cellulose fibers improved by the drawing of cellulose hydrogel fibers during the spinning process. This approach for the fabrication of tough cellulose hydrogels is a major advance in the fabrication of cellulose-based structures with defined shapes.

  7. Dynamic fracture toughnesses of reaction-bonded silicon nitride

    NASA Technical Reports Server (NTRS)

    Kobayashi, A. S.; Emery, A. F.; Liaw, B. M.

    1983-01-01

    The room-temperature dynamic fracture response of reaction-bonded silicon nitride is investigated using a hybrid experimental-numerical procedure. In this procedure, experimentally determined crack velocities are utilized to drive a dynamic finite-element code or dynamic finite-difference code in its generation mode in order to extract numerically the dynamic stress intensity factor of the fracturing specimen. Results show that the dynamic fracture toughness vs crack velocity relations of the two reaction-bonded silicon nitrides do not follow the general trend in those relations of brittle polymers and steel. A definite slow crack velocity during the initial phase of dynamic crack propagation is observed in reaction-bonded silicon nitride, which results in a nonunique dynamic fracture toughness vs crack velocity relation. In addition, it is found that a propagating crack will continue to propagate under a static stress intensity factor substantially lower than K(IC).

  8. Versatile Molding Process for Tough Cellulose Hydrogel Materials

    PubMed Central

    Kimura, Mutsumi; Shinohara, Yoshie; Takizawa, Junko; Ren, Sixiao; Sagisaka, Kento; Lin, Yudeng; Hattori, Yoshiyuki; Hinestroza, Juan P.

    2015-01-01

    Shape-persistent and tough cellulose hydrogels were fabricated by a stepwise solvent exchange from a homogeneous ionic liquid solution of cellulose exposure to methanol vapor. The cellulose hydrogels maintain their shapes under changing temperature, pH, and solvents. The micrometer-scale patterns on the mold were precisely transferred onto the surface of cellulose hydrogels. We also succeeded in the spinning of cellulose hydrogel fibers through a dry jet-wet spinning process. The mechanical property of regenerated cellulose fibers improved by the drawing of cellulose hydrogel fibers during the spinning process. This approach for the fabrication of tough cellulose hydrogels is a major advance in the fabrication of cellulose-based structures with defined shapes. PMID:26537533

  9. Process for Preparing a Tough, Soluble, Aromatic, Thermoplastic Copolyimide

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor)

    1997-01-01

    A process for preparing a tough, soluble, aromatic, thermoplastic copolyimide is provided. The process comprises the steps of (a) providing 4.4'-oxydiphthalic anhydride to 3,4,3',4'-biphenyltetracarboxylic dianhydride at a mole ratio ranging from about 25 mole percent to 75 mole percent to 75 mole percent to about 25 mole percent; (b) adding 3,4'-oxydianiline to form a mixture; (c) adding a polar aprotic or polar protic solvent to the mixture to form a solution having a percentage of solids capable of maintaining polymer solubility; (d) stirring the solution to allow it to react; (e) adding an azeotropic solvent to the solution and heating to remove water; (f) cooling the solution of step (e) to room temperature and recovering the tough, soluble, aromatic, thermoplastic copolyimide.

  10. Large-strain deformation and fracture of tough hydrogels

    NASA Astrophysics Data System (ADS)

    Webber, Rebecca; Miquelard, Guillaume; Creton, Costantino; Gong, Jian Ping

    2006-03-01

    Highly-swollen, chemically-crosslinked hydrogels generally behave in a very brittle manner, fracturing suddenly after a small amount of reversible deformation. Because of their importance as biomaterials, it is useful to control and augment the resistance to fracture of these materials. Tougher, stronger hydrogels are emerging, and it is important to understand the structural origins of strength in these relatively robust, highly-swollen, polymer systems. We have investigated the rheological, mechanical and fracture properties of tough hydrogels, using novel testing techniques and focusing on the high-strain compression and tension behavior. Results from large-strain and fracture experiments were correlated to the chemical structure of the hydrogels. Because we believe that the mechanical properties of these tough hydrogels are due to the presence of dissipative mechanisms at the molecular level, we have explored several methods of synthesis to create these materials.

  11. Toughness enhancement in zirconium-tungsten-nitride nanocrystalline hard coatings

    NASA Astrophysics Data System (ADS)

    Dubey, P.; Srivastava, S.; Chandra, R.; Ramana, C. V.

    2016-07-01

    An approach is presented to increase the toughness (KIC) while retaining high hardness (H) of Zr-W-N nanocrystalline coatings using energetic ions bombardment. Tuning KIC and H values was made possible by a careful control over the substrate bias, i.e., the kinetic energy (Uk˜9-99 J/cm3) of the bombarding ions, while keeping the deposition temperature relatively low (200 oC). Structural and mechanical characterization revealed a maximum wear resistance (H/Er˜0.23) and fracture toughness (KIC˜2.25 MPa √{ m } ) of ZrWN coatings at Uk˜72 J/cm3. A direct Uk-microstructure-KIC-H relationship suggests that tailoring mechanical properties for a given application is possible by tuning Uk and, hence, ZrWN-coatings' microstructure.

  12. Mental Toughness in Competitive Tennis: Relationships with Resilience and Stress.

    PubMed

    Cowden, Richard G; Meyer-Weitz, Anna; Oppong Asante, Kwaku

    2016-01-01

    The present study investigated the relationships between mental toughness (MT), resilience, and stress among competitive South African tennis players. A total of 351 tennis players participating at various competitive standards completed the Sports Mental Toughness Questionnaire, the Resilience Scale for Adults, and a modified version of the Recovery-Stress Questionnaire for Athletes. The results indicated that total MT was positively associated with total resilience (r = 0.59), but negatively associated with total stress (r = -0.44). The resilience subscales of perception of self, perception of future, social competence, and social resources, but not family cohesion, significantly predicted total MT (R (2) = 0.35). Both total resilience and total MT significantly predicted total stress (R (2) = 0.21). Based on the findings, interrelations between MT and resilience are explored, implications outlined, and additional research is suggested to ascertain the contextual relevance and outcomes associated with each construct in sport.

  13. Fracture Toughness Effects in Geomaterial Solid Particle Erosion

    NASA Astrophysics Data System (ADS)

    Momber, A. W.

    2015-07-01

    Effects of fracture toughness on the impingement of geomaterials (rocks and cementitious composites) by quartz particles at velocities between 40 and 140 m/s are investigated experimentally and analytically. If schist is excluded, relative erosion (in g/g) reduces according to a reverse power function if fracture toughness increases. The power exponent depends on impingement velocity, and it varies between -0.64 and -1.33. Lateral cracking erosion models, developed for brittle materials, deliver too high values for relative material erosion. This discrepancy is partly attributed to stress rate effects. Effects of R-curve behavior seem to be marginal. An integral approach E R = K 1 · E {R/P} + (1 - K 1) · E {R/L} is introduced, which considers erosion due to plastic deformation and lateral cracking. A transition function is suggested in order to classify geomaterials according to their response against solid particle impingement.

  14. Creep and Toughness of Cryomilled NiAl Containing Cr

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Aikin, Beverly; Salem, Jon

    2000-01-01

    NiAl-AlN + Cr composites were produced by blending cryomilled NiAl powder with approx. 10 vol % Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl-AlN+10.5Cr, however, possessed a toughness twice that determine for the base NiAl-AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl-AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix.

  15. A new basis for the determination of fracture toughness

    NASA Technical Reports Server (NTRS)

    Banerjee, S.

    1979-01-01

    A study is presented which shows that the growth of the plastic zone and the constraint in a compact tension specimen depends significantly on specimen width. The analysis permits the estimation of the contribution of the growth of plastic zone to the deviation from linearity. The contribution of the crack growth to the deviation from linearity is evaluated from the analysis of a typical R-curve data. A combination of these two analyses enables one to define a very simple procedure for the determination of fracture toughness. The fracture toughness is defined as the stress intensity value at which the crack extension starts. The good agreement between analytical results and experimental KQ and KIC values determined over a wide range of thicknesses, widths, and materials justifies the proposed procedures. The KIC determined according to this procedure is independent of specimen width and such a procedure enhances the range of applicability of the K concept to a wider combination of configurations and materials.

  16. Enzymatic mineralization generates ultrastiff and tough hydrogels with tunable mechanics

    NASA Astrophysics Data System (ADS)

    Rauner, Nicolas; Meuris, Monika; Zoric, Mirjana; Tiller, Joerg C.

    2017-03-01

    The cartilage and skin of animals, which are made up of more than fifty per cent water, are rather stiff (having elastic moduli of up to 100 megapascals) as well as tough and hard to break (with fracture energies of up to 9,000 joules per square metre). Such features make these biological materials mechanically superior to existing synthetic hydrogels. Lately, progress has been made in synthesizing tough hydrogels, with double-network hydrogels achieving the toughness of skin and inorganic–organic composites showing even better performance. However, these materials owe their toughness to high stretchability; in terms of stiffness, synthetic hydrogels cannot compete with their natural counterparts, with the best examples having elastic moduli of just 10 megapascals or less. Previously, we described the enzyme-induced precipitation and crystallization of hydrogels containing calcium carbonate, but the resulting materials were brittle. Here we report the enzyme-induced formation of amorphous calcium phosphate nanostructures that are homogenously distributed within polymer hydrogels. Our best materials have fracture energies of 1,300 joules per square metre even in their fully water-swollen state—a value superior to that of most known water-swollen synthetic materials. We are also able to modulate their stiffness up to 440 megapascals, well beyond that of cartilage and skin. Furthermore, the highly filled composite materials can be designed to be optically transparent and to retain most of their stretchability even when notched. We show that percolation drives the mechanical properties, particularly the high stiffness, of our uniformly mineralized hydrogels.

  17. Strength and toughness of monolithic and composite silicon nitrides

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan A.

    1990-01-01

    The strength and toughness of two composite and two monolithic silicon nitrides were measured from 25 to 1400 C. The monolithic and composite materials were made from similar starting powders. Both of the composite materials contained 30 vol percent silicon carbide whiskers. All measurements were made by four point flexure in surrounding air and humidity. The composite and monolithic materials exhibited similar fast fracture properties as a function of temperature.

  18. Advanced Nanocrystalline Ceramic Matrix Composites with Improved Toughness

    DTIC Science & Technology

    2009-01-09

    nanocomposites reinforced with niobium and/or carbon nanotubes were fabricated by advanced powder processing techniques and consolidated by spark plasma...tests were conducted on niobium and/or carbon nanotube-reinforced alumina U 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 09-01-2009 13...Toughness Report Title ABSTRACT Alumina-based nanocomposites reinforced with niobium and/or carbon nanotubes were fabricated by advanced powder processing

  19. Medical Aspects of Survival: Training for Aircrew

    DTIC Science & Technology

    1983-01-01

    availability of technical medical assistance within a reasonable period if time . The Survival Situation. There is no type "survival situation...enhance practicality. Survival Factors . Despite the variation among individual survival situations, factors may be categorized as follows : a...magnitude of the medical problem in survival is indicated by past experiences where some 60 % of all survivors were already injured by the time they

  20. Strength and toughness of structural fibres for composite material reinforcement.

    PubMed

    Herráez, M; Fernández, A; Lopes, C S; González, C

    2016-07-13

    The characterization of the strength and fracture toughness of three common structural fibres, E-glass, AS4 carbon and Kevlar KM2, is presented in this work. The notched specimens were prepared by means of selective carving of individual fibres by means of the focused ion beam. A straight-fronted edge notch was introduced in a plane perpendicular to the fibre axis, with the relative notch depth being a0/D≈0.1 and the notch radius at the tip approximately 50 nm. The selection of the appropriate beam current during milling operations was performed to avoid to as much as possible any microstructural changes owing to ion impingement. Both notched and un-notched fibres were submitted to uniaxial tensile tests up to failure. The strength of the un-notched fibres was characterized in terms of the Weibull statistics, whereas the residual strength of the notched fibres was used to determine their apparent toughness. To this end, the stress intensity factor of a fronted edge crack was computed by means of the finite-element method for different crack lengths. The experimental results agreed with those reported in the literature for polyacrylonitrile-based carbon fibres obtained by using similar techniques. After mechanical testing, the fracture surface of the fibres was analysed to ascertain the failure mechanisms. It was found that AS4 carbon and E-glass fibres presented the lower toughness with fracture surfaces perpendicular to the fibre axis, emanating from the notch tip. The fractured region of Kevlar KM2 fibres extended along the fibre and showed large permanent deformation, which explains their higher degree of toughness when compared with carbon and glass fibres. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.