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. 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.

  7. 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…

  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. 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.

  10. 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…

  11. 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…

  12. 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.

  13. 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…

  14. 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…

  15. When times get tough, what happens to TQM? Case study.

    PubMed

    Niven, D

    1993-01-01

    When Mueller Chemical Company's biggest customer, Ameriton, demanded that MCC install a total quality management system five years ago, the effort seemed worth it. Morale improved dramatically at the German company, as did quality and productivity. But now, in this fictional case study, Ameriton has gone bankrupt. As a result, MCC has had to cut its work force, and senior managers are meeting to decide whether TQM should be part of the downsized MCC. Horst Koblitz, director of TQM, and Division Manager Eva Stichen both vote yes. Stichen's division, which never supplied Ameriton, has turned its process-control system into the company's best thanks to TQM. The division is more cost-efficient, product defects are nearly nonexistent, and its safety record is spotless. As Koblitz notes, Ameriton's failure is no reason to abandon all that MCC has built. Furthermore, shareholders and customers would think that MCC was panicking. MCC just needs to tailor its TQM program to a smaller organization. But CFO Georg Becker doesn't think MCC has the time or resources for fine-tuning. And as he sees it, that might be just as well. The distractions that came with TQM took MCC away from its goal of becoming the chemicals market leader in Europe. While the company organized teams, developed measurement systems, and filled out quality reports, its competitors took away much of the market share MCC was after. TQM was a good long-term approach, but it didn't come with a plan for MCC's current situation. And CEO and Chairman Dieter Mueller won't compromise; TQM must either stay or go.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:10126153

  16. [Survival time without food and drink].

    PubMed

    Kottusch, Pia; Tillmann, Miriam; Püschel, Klaus

    2009-01-01

    After accidents, in which victims were trapped or buried alive, the question how long one can survive without eating and drinking often becomes a subject of public interest. Experiments with humans are ethically unacceptable. As an approach to the issue, this article also takes reports from the popular press into account. Altogether, it seems possible to survive without food and drink within a time span of 8 to 21 days. If a person is only deprived of food, the survival time may even go up to about two months, although this is influenced by many factors. The article describes the impressive case of a handcuffed 81-year-old man, in which the external circumstances are known. PMID:20069776

  17. Effect of holding time in the ({alpha} + {gamma}) temperature range on toughness of specially austempered ductile iron

    SciTech Connect

    Kobayashi, T.; Yamada, S.

    1996-07-01

    Austempered ductile iron (ADI) finds wide application in the industry because of its high strength and toughness. The QB{prime} process has been developed to produce a fine microstructure with high fracture toughness in ADI. This process involves reaustenitizing a prequenched ductile iron in the ({alpha} + {gamma}) temperature range followed by an isothermal treatment in the bainitic transformation temperature range. In the present work, the effect of holding time in the ({alpha} + {gamma}) temperature range on the structure and un-notched toughness of ADI has been studied. Prior to the austempering treatment, the as-cast ductile iron was heat treated to obtain martensitic, ferritic, and pearlitic matrix structures. In the case of prequenched material (martensitic matrix), the un-notched impact toughness increased as a function of holding time in the ({alpha} + {gamma}) temperature range. The reaustenitization heat treatment also resulted in the precipitation of fine carbide particles, identified as (Fe,Cr,Mn){sub 3}C. It was shown that the increase in holding time in the ({alpha} + {gamma}) temperature range leads to a reduction in the number of carbide particles. In the case of a ferritic prior structure, a long duration hold in the ({alpha} + {gamma}) temperature range resulted in the coarsening of the structure with a marginal increase in the toughness. In the case of a pearlitic prior structure, the toughness increased with holding time. This was attributed to the decomposition of the relatively stable carbide around the eutectic cell boundary with longer holding times.

  18. Risk-adjusted monitoring of survival times

    SciTech Connect

    Sego, Landon H.; Reynolds, Marion R.; Woodall, William H.

    2009-02-26

    We consider the monitoring of clinical outcomes, where each patient has a di®erent risk of death prior to undergoing a health care procedure.We propose a risk-adjusted survival time CUSUM chart (RAST CUSUM) for monitoring clinical outcomes where the primary endpoint is a continuous, time-to-event variable that may be right censored. Risk adjustment is accomplished using accelerated failure time regression models. We compare the average run length performance of the RAST CUSUM chart to the risk-adjusted Bernoulli CUSUM chart, using data from cardiac surgeries to motivate the details of the comparison. The comparisons show that the RAST CUSUM chart is more efficient at detecting a sudden decrease in the odds of death than the risk-adjusted Bernoulli CUSUM chart, especially when the fraction of censored observations is not too high. We also discuss the implementation of a prospective monitoring scheme using the RAST CUSUM chart.

  19. 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.

  20. Time series modeling of system self-assessment of survival

    SciTech Connect

    Lu, H.; Kolarik, W.J.

    1999-06-01

    Self-assessment of survival for a system, subsystem or component is implemented by assessing conditional performance reliability in real-time, which includes modeling and analysis of physical performance data. This paper proposes a time series analysis approach to system self-assessment (prediction) of survival. In the approach, physical performance data are modeled in a time series. The performance forecast is based on the model developed and is converted to the reliability of system survival. In contrast to a standard regression model, a time series model, using on-line data, is suitable for the real-time performance prediction. This paper illustrates an example of time series modeling and survival assessment, regarding an excessive tool edge wear failure mode for a twist drill operation.

  1. Scaling of expected survival time in a stochastic harvesting model

    NASA Astrophysics Data System (ADS)

    Hastings, Harold; Radin, Michael; Wiandt, Tamas

    We explore the dynamics of modified version of a standard fishery model (Gordon-Schafer-Munro), with additive and multiplicative noise, under a quota-based harvest. A harvest quota induces an effective strong Allee effect (a positive unstable steady state population level, below which populations die out), with expected survival time following generalized Ornstein-Uhlenbeck dynamics. In particular, for additive noise, the expected survival time is exponential in s3/σ2, where s is the difference between stable and unstable steady state populations and σ the noise level. Thus survival time depends sensitively upon harvest quota (which determines steady state population), perhaps a warning to avoid future collapses such as that of the Atlantic cod fishery.

  2. Aggregation increases prey survival time in group chase and escape

    NASA Astrophysics Data System (ADS)

    Yang, Sicong; Jiang, Shijie; Jiang, Li; Li, Geng; Han, Zhangang

    2014-08-01

    Recently developed chase-and-escape models have addressed a fascinating pursuit-and-evasion problem that may have both theoretical significance and potential applications. We introduce three aggregation strategies for the prey in a group chase model on a lattice. Simulation results show that aggregation dramatically increases the group survival time, even allowing immortal prey. The average survival time τ and the aggregation probability P have a power-law dependence of \\tau \\sim {{(1-P)}^{-1}} for P\\in [0.9,0.997]. With increasing numbers of predators, there is still a phase transition. When the number of predators is less than the critical point value, the prey group survival time increases significantly.

  3. Survival-time statistics for sample space reducing stochastic processes

    NASA Astrophysics Data System (ADS)

    Yadav, Avinash Chand

    2016-04-01

    Stochastic processes wherein the size of the state space is changing as a function of time offer models for the emergence of scale-invariant features observed in complex systems. I consider such a sample-space reducing (SSR) stochastic process that results in a random sequence of strictly decreasing integers {x (t )},0 ≤t ≤τ , with boundary conditions x (0 )=N and x (τ ) = 1. This model is shown to be exactly solvable: PN(τ ) , the probability that the process survives for time τ is analytically evaluated. In the limit of large N , the asymptotic form of this probability distribution is Gaussian, with mean and variance both varying logarithmically with system size: <τ >˜lnN and στ2˜lnN . Correspondence can be made between survival-time statistics in the SSR process and record statistics of independent and identically distributed random variables.

  4. 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…

  5. Tough by name, tough by nature.

    PubMed

    Baillie, Jonathan

    2015-04-01

    Few beds, one would imagine, could withstand three-quarters of a ton landing on them, but this was the challenge successfully met by a box bed from a furniture manufacturer for challenging behaviour environments, Tough Furniture, when, to reassure a customer that the bed could accommodate 30-stone patients, 13 of the company's staff jumped repeatedly on it to ensure that it would survive intact in a real-world setting. Such testing may seem extreme, but is vital, since much of the company's furniture is destined for environments where patients will abuse, and indeed attempt to destroy, components. As MD David Vesty explained to HEJ editor, Jonathan Baillie, when he visited the company's Shropshire headquarters, it is through manufacturing premium quality cabinet furniture that is both attractive and distinctly non-institutional, but will equally withstand the harshest use, that the company has ensured that its products can live up to the brand name. PMID:26281428

  6. Cranial trauma and the assessment of posttraumatic survival time.

    PubMed

    Steyn, M; De Boer, H H; Van der Merwe, A E

    2014-11-01

    Assessment of trauma on skeletal remains can be very difficult, especially when it comes to the estimation of posttraumatic survival time in partially healed lesions. The ability to reliably estimate the time an individual has survived after sustaining an injury is especially important in cases of child abuse and torture, but can also aid in determining the association between an injury and eventual death. Here a case from South Africa is reported, where the skeletal remains of an unknown individual were found with cranial and scapular fractures. These fractures all presented with macroscopic features indicative of healing. Using recently published data on the timing of fractures by De Boer et al., the two sets of cranial trauma and the scapular fracture were assessed by means of radiology, histology and microCT scanning. This was primarily done in order to obtain more information on the events surrounding the death of this individual, but also to assess the usability of the published methods on cranial fractures. It was found that the initial trauma was most likely sustained at least two weeks before death, whilst a neurosurgical procedure was performed at least one week before death. It seems that cranial fractures, especially if stable, may show some different healing features than postcranial fractures. The individual has since been identified, but unfortunately as is often the case in South Africa, limited information is available and the medical records could not be found. PMID:25217847

  7. 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.

  8. Fracture toughness and time-dependent strength behavior of low-doped silicon nitrides for applications at 1400 C

    SciTech Connect

    Klemm, H. ); Pezzotti, G. )

    1994-02-01

    The influence of small additions of three selected oxides on the microstructure and the mechanical behavior of high-purity silicon nitride was systematically investigated. Dense silicon nitride bodies doped respectively with SiO[sub 2], Y[sub 2]O[sub 3], and Yb[sub 2]O[sub 3] were fabricated by hot isostatic pressing (HIP). Two different compositions of the intergranular phase were examined for Y[sub 2]O[sub 3] and Yb[sub 2]O[sub 3] in comparison with the same volume of pure SiO[sub 2]. Only in the material with the higher Y[sub 2]O[sub 3] and Yb[sub 2]O[sub 3] content was an improved level of fracture toughness obtained. The mechanical properties at 1,400 C were evaluated with emphasis placed on time-dependent strength and deformation behavior. The materials containing only SiO[sub 2] or doped with the small amount of Y[sub 2]O[sub 3] showed linear elastic K[sub I]-controlled fracture behavior of 1,400 C and the critical phenomenon for failure was subcritical crack growth (SCG) from preexisting defects. In the materials with additions of Yb[sub 2]O[sub 3] or the larger amount of Y[sub 2]O[sub 3], crack extension was governed by creep crack growth as a result of the exhibited strong creep effects. In the silicon nitride doped with 1.7 vol% Yb[sub 2]O[sub 3], however, a considerably improved creep behavior as a consequence of crystallization processes in the intergranular phase (Yb[sub 2]Si[sub 2]O[sub 7]) caused by both thermal treatment and stress-initiated effects during the mechanical testing at 1,400 C was found.

  9. 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 North…

  10. Retention in Tough Times.

    ERIC Educational Resources Information Center

    Kaye, Beverly; Jordan-Evans, Sharon

    2002-01-01

    Interviews with 25 global talent leaders discuss keeping good people and the challenges and emerging practices for retaining employees. Sidebars discuss retention tips and what keeps people on the job. (JOW)

  11. These Tough Economic Times

    ERIC Educational Resources Information Center

    Desrochers, John E.; Cowan, Katherine C.; Christner, Ray W.

    2009-01-01

    Research has shown that students' social, emotional, and behavioral health affects their academic achievement. This has enormous implications for teachers, school mental health providers, and the students themselves. A student who is hungry, disengaged, preoccupied, or behaviorally disruptive simply is not going to respond as well to even the best…

  12. 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.

  13. 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.

  14. 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…

  15. 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…

  16. 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.

  17. Genetic influences on survival time after severe hemorrhage in inbred rat strains.

    PubMed

    Klemcke, Harold G; Joe, Bina; Calderon, Mariam L; Rose, Rajiv; Oh, Thomas; Aden, James; Ryan, Kathy L

    2011-06-28

    To find a genetic basis for differential ability to survive severe hemorrhage, we previously showed eightfold differences in survival times among inbred rat strains. We assumed that rat strains had similar normalized blood volumes (NBV; ml/100 g body wt). As NBV might vary among strains and constitute one genetic variable affecting survival time to hemorrhage, in experiment 1 of the current studies we first measured total blood volumes and calculated NBV in specific inbred rat strains (Brown Norway/Medical College of Wisconsin, BN; Dark Agouti, DA; Fawn Hooded Hypertensive, FHH; Lewis, LEW; and Dahl Salt-Sensitive, SS) previously found to be divergent in survival time. NBV differed by 20% (P < 0.01; BN > SS > FHH = LEW = DA) and had a heritability (h(2)) of 0.56. Hence, differential survival times in our previously published study might reflect strain-dependent differences in NBV. Then studies were conducted wherein rats were catheterized and, ∼24 h later, 47% of their blood volume was removed; these rats were observed for a maximum of 4 h. In experiment 2, blood volumes were measured the day prior to hemorrhage. Percent survival and survival time did not differ among strains. To obviate possible confounding effects of blood volume determination, in experiment 3 the average NBV for each strain was used to determine hemorrhage volumes. Percent survival (P < 0.01) and survival times (P < 0.001) were different with DA demonstrating the best (62.5%, 190 ± 29 min) and BN the worst (0%, 52 ± 5 min) survival responses. These data indicate that both blood volume and survival time after hemorrhage in rats are heritable quantitative traits, and continue to suggest that genetic assessment of these phenotypes might lead to novel therapeutics to improve survival to hemorrhage. PMID:21487033

  18. 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.

  19. 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…

  20. Semiparametric methods to contrast gap time survival functions: Application to repeat kidney transplantation.

    PubMed

    Shu, Xu; Schaubel, Douglas E

    2016-06-01

    Times between successive events (i.e., gap times) are of great importance in survival analysis. Although many methods exist for estimating covariate effects on gap times, very few existing methods allow for comparisons between gap times themselves. Motivated by the comparison of primary and repeat transplantation, our interest is specifically in contrasting the gap time survival functions and their integration (restricted mean gap time). Two major challenges in gap time analysis are non-identifiability of the marginal distributions and the existence of dependent censoring (for all but the first gap time). We use Cox regression to estimate the (conditional) survival distributions of each gap time (given the previous gap times). Combining fitted survival functions based on those models, along with multiple imputation applied to censored gap times, we then contrast the first and second gap times with respect to average survival and restricted mean lifetime. Large-sample properties are derived, with simulation studies carried out to evaluate finite-sample performance. We apply the proposed methods to kidney transplant data obtained from a national organ transplant registry. Mean 10-year graft survival of the primary transplant is significantly greater than that of the repeat transplant, by 3.9 months (p=0.023), a result that may lack clinical importance. PMID:26501480

  1. Surviving in a metastable de Sitter space-time

    NASA Astrophysics Data System (ADS)

    Kashyap, Sitender Pratap; Mondal, Swapnamay; Sen, Ashoke; Verma, Mritunjay

    2015-09-01

    In a metastable de Sitter space any object has a finite life expectancy beyond which it undergoes vacuum decay. However, by spreading into different parts of the universe which will fall out of causal contact of each other in future, a civilization can increase its collective life expectancy, defined as the average time after which the last settlement disappears due to vacuum decay. We study in detail the collective life expectancy of two comoving objects in de Sitter space as a function of the initial separation, the horizon radius and the vacuum decay rate. We find that even with a modest initial separation, the collective life expectancy can reach a value close to the maximum possible value of 1.5 times that of the individual object if the decay rate is less than 1% of the expansion rate. Our analysis can be generalized to any number of objects, general trajectories not necessarily at rest in the comoving coordinates and general FRW space-time. As part of our analysis we find that in the current state of the universe dominated by matter and cosmological constant, the vacuum decay rate is increasing as a function of time due to accelerated expansion of the volume of the past light cone. Present decay rate is about 3.7 times larger than the average decay rate in the past and the final decay rate in the cosmological constant dominated epoch will be about 56 times larger than the average decay rate in the past. This considerably weakens the lower bound on the half-life of our universe based on its current age.

  2. Time-specific variation in passerine nest survival: new insights for old questions

    USGS Publications Warehouse

    Grant, T.A.; Shaffer, T.L.; Madden, E.M.; Pietz, P.J.

    2005-01-01

    Nest survival likely varies with nest age and date, but until recently researchers had only limited tools to efficiently address those sources of variability. Beginning with Mayfield (1961), many researchers have averaged survival rates within time-specific categories (e.g. egg and nestling stages; early and late nesting dates). However, Mayfield's estimator assumes constant survival within categories, and violations of that assumption can lead to biased estimates. We used the logistic-exposure method to examine nest survival as a function of nest age and date in Clay-colored Sparrows (Spizella pallida) and Vesper Sparrows (Pooecetes gramineus) breeding in north-central North Dakota. Daily survival rates increased during egg laying, decreased during incubation to a low shortly after hatch, and then increased during brood rearing in both species. Variation in survival with nest age suggests that traditional categorical averaging using Mayfield's or similar methods would have been inappropriate for this study; similar variation may bias results of other studies. Nest survival also varied with date. For both species, survival was high during the peak of nest initiations in late May and early June and declined throughout the remainder of the nesting season. Models of nest survival that incorporate time-specific information may provide insights that are unavailable from averaged data.

  3. 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…

  4. A discrete-time Multiple Event Process Survival Mixture (MEPSUM) model.

    PubMed

    Dean, Danielle O; Bauer, Daniel J; Shanahan, Michael J

    2014-06-01

    Traditional survival analysis was developed to investigate the occurrence and timing of a single event, but researchers have recently begun to ask questions about the order and timing of multiple events. A multiple event process survival mixture model is developed here to analyze nonrepeatable events measured in discrete-time that may occur at the same point in time. Building on both traditional univariate survival analysis and univariate survival mixture analysis, the model approximates the underlying multivariate distribution of hazard functions via a discrete-point finite mixture in which the mixing components represent prototypical patterns of event occurrence. The model is applied in an empirical analysis concerning transitions to adulthood, where the events under study include parenthood, marriage, beginning full-time work, and obtaining a college degree. Promising opportunities, as well as possible limitations of the model and future directions for research, are discussed. PMID:24079930

  5. Survival is linked with reaction time and spatial memory in African striped mice.

    PubMed

    Maille, Audrey; Schradin, Carsten

    2016-08-01

    Studying the association between fitness and cognition in free-living animals is a fundamental step in the elucidation of the evolution of cognition. We assessed whether survival until the onset of the breeding season was related to reaction time or spatial memory in the African striped mouse Rhabdomys pumilio, a rodent that has to survive summer drought before breeding. We tested a total of 90 individuals at the beginning of summer. Female survival was related to a faster response to predation stimuli. Male survival increased with greater spatial memory, possibly because it is important for males to remember the configuration of the environment during dispersal. This study revealed that individual variation in reaction time and spatial memory can be related to survival probability, which is important for understanding the selection pressures acting on basic cognitive traits. PMID:27484646

  6. Proportional exponentiated link transformed hazards (ELTH) models for discrete time survival data with application

    PubMed Central

    Joeng, Hee-Koung; Chen, Ming-Hui; Kang, Sangwook

    2015-01-01

    Discrete survival data are routinely encountered in many fields of study including behavior science, economics, epidemiology, medicine, and social science. In this paper, we develop a class of proportional exponentiated link transformed hazards (ELTH) models. We carry out a detailed examination of the role of links in fitting discrete survival data and estimating regression coefficients. Several interesting results are established regarding the choice of links and baseline hazards. We also characterize the conditions for improper survival functions and the conditions for existence of the maximum likelihood estimates under the proposed ELTH models. An extensive simulation study is conducted to examine the empirical performance of the parameter estimates under the Cox proportional hazards model by treating discrete survival times as continuous survival times, and the model comparison criteria, AIC and BIC, in determining links and baseline hazards. A SEER breast cancer dataset is analyzed in details to further demonstrate the proposed methodology. PMID:25772374

  7. Radiographic Response to Locoregional Therapy in Hepatocellular Carcinoma Predicts Patient Survival Times

    PubMed Central

    Memon, Khairuddin; Kulik, Laura; Lewandowski, Robert J; Wang, Edward; Riaz, Ahsun; Ryu, Robert K; Sato, Kent T; Marshall, Karen; Gupta, Ramona; Nikolaidis, Paul; Miller, Frank H; Yaghmai, Vahid; Senthilnathan, Seanthan; Baker, Talia; Gates, Vanessa L; Abecassis, Michael; Benson, Al B; Mulcahy, Mary F; Omary, Reed A; Salem, Riad

    2011-01-01

    Background & Aims It is not clear whether survival times of patients with hepatocellular carcinoma (HCC) are associated with their response to therapy. We analyzed the association between tumor response and survival times of patients with HCC who were treated with locoregional therapies (LRTs; chemoembolization and radioembolization). Methods Patients received LRTs over a 9-year period (n=463). Patients with metastases, portal venous thrombosis, or who had received transplants were excluded; 159 patients with Child-Pugh≤B7 were analyzed. Response (based on European Association for Study of the Liver [EASL] or World Health Organization [WHO] criteria) was associated with survival times using the landmark, risk-of-death, and Mantel-Byar methodologies. In a subanalysis, survival times of responders were compared to those of patients with stable disease (SD) and progressive disease (PD). Results Based on 6-month data, in landmark analysis, responders survived longer than nonresponders (based on EASL but not WHO criteria: P=0.002 and 0.0694). The risk of death was also lower for responders (based on EASL but not WHO criteria: P=0.0463 and 0.707). Landmark analysis of 12-month data showed that responders survived longer than nonresponders (P=<0.0001 and 0.004, based on EASL and WHO criteria, respectively). The risk of death was lower for responders (P=0.0132 and 0.010, based on EASL and WHO criteria, respectively). By the Mantel-Byar method, responders had longer survival than nonresponders, based on EASL criteria (P<0.0001; P=0.596 with WHO criteria). In the subanalysis, responders lived longer than patients with SD or PD. Conclusion Radiographic response to LRTs predicts survival time. EASL criteria for response more consistently predicted survival times than WHO criteria. The goal of LRT should be to achieve a radiologic response, rather than to stabilize disease. PMID:21664356

  8. Recycling: Surviving and thriving through the down times

    SciTech Connect

    Heumann, J.M.

    1997-09-01

    Over the past year, since the decrease in market value of recyclable materials, recycling`s detractors have been coming out of the woodwork. Critics of recycling, through newspaper and magazine articles, policy papers, and other venues, have used many arguments to discredit current recycling efforts. Their arguments range from claiming that recycling is not a cost-effective waste management option, to saying recycling is a panacea by which people feel they can ignore larger environmental problems. Recyclables collection programs have had periods where they were considerably more cost-effective than they are today. During the summer and fall of 1995, the market prices paid by processors and end users for recovered materials reached new heights unseen before--and unseen since. Recycling programs have felt the heat of criticism over the past year. Yet, at the same time, state recycling rates continue to increase, states put more programs in place, and recycling overall continues to thrive. This article examines why recycling programs are still successful, and how they can live up to their potential.

  9. Nonparametric estimation of the survival function for ordered multivariate failure time data: A comparative study.

    PubMed

    Meira-Machado, Luís; Sestelo, Marta; Gonçalves, Andreia

    2016-05-01

    In longitudinal studies of disease, patients may experience several events through a follow-up period. In these studies, the sequentially ordered events are often of interest and lead to problems that have received much attention recently. Issues of interest include the estimation of bivariate survival, marginal distributions, and the conditional distribution of gap times. In this work, we consider the estimation of the survival function conditional to a previous event. Different nonparametric approaches will be considered for estimating these quantities, all based on the Kaplan-Meier estimator of the survival function. We explore the finite sample behavior of the estimators through simulations. The different methods proposed in this article are applied to a dataset from a German Breast Cancer Study. The methods are used to obtain predictors for the conditional survival probabilities as well as to study the influence of recurrence in overall survival. PMID:26455826

  10. 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.

    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.

  11. 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.

  12. 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.

  13. 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.

  14. Dynamic fracture toughness

    NASA Technical Reports Server (NTRS)

    Kobayashi, A. S.; Ramulu, M.; Dadkhah, M. S.; Yang, K.-H.; Kang, B. S. J.

    1986-01-01

    Dynamic fracture toughness versus crack velocity relations of Homalite-100, polycarbonate, hardened 4340 steel and reaction bonded silicon nitride are reviewed and discrepancies with published data and their probable causes are discussed. Data scatter in published data are attributed in part to the observed fluctuations in crack velocities. The results reaffirmed our previous conclusion that the dynamic fracture toughness versus crack velocity relation is specimen dependent and that the dynamic arrest stress intensity factor is not a unique material property.

  15. TOUGH Short Course for Scientists and Engineers

    SciTech Connect

    Kowalsky, Michael B.; Finsterle, Stefan

    2006-08-01

    The TOUGH family of codes is a suite of computer programs for the simulation of multiphase fluid and heat flows in porous and fractured media with applications to geothermal reservoir engineering, nuclear waste disposal in geologic formations, geologic carbon sequestration, gas hydrate research, vadose zone hydrology, environmental remediation, oil and gas reservoir engineering, and other mass transport and energy transfer problems in complex geologic settings. TOUGH has been developed in the Earth Sciences Division of the Lawrence Berkeley National Laboratory (LBNL). Many modifications and enhancements have been made to TOUGH (at LBNL and elsewhere) from the time it was first released in 1987. TOUGH and its various descendants (such as iTOUGH2, T2VOC, TMVOC, EWASG, TOUGHREACT, TOUGH+ and many more) are currently in use in approximately 300 research laboratories, private companies, and universities in 33 countries. The LBNL group, headed by Karsten Pruess, serves as custodian of the code. The TOUGH simulators were developed for problems involving strongly heat-driven flow. To describe these phenomena a multi-phase approach to fluid and heat flow is used, which fully accounts for the movement of gaseous and liquid phases, their transport of latent and sensible heat, and phase transitions between liquid and vapor. TOUGH takes account of fluid flow in both liquid and gaseous phases--and, in certain modules, a non-aqueous phase liquid (NAPL)--occurring under pressure, viscous, and gravity forces according to Darcy's law. Interference between the phases is represented by means of relative permeability functions. The code includes Klinkenberg effects and binary diffusion in the gas phase, and capillary and phase adsorption effects for the liquid phase. Heat transport occurs by means of conduction (with thermal conductivity dependent on water saturation), convection, and binary diffusion, which includes both sensible and latent heat. The goal of this training course is to

  16. TOUGH-Fx

    Energy Science and Technology Software Center (ESTSC)

    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 flowmore » 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.« less

  17. A survival tree method for the analysis of discrete event times in clinical and epidemiological studies.

    PubMed

    Schmid, Matthias; Küchenhoff, Helmut; Hoerauf, Achim; Tutz, Gerhard

    2016-02-28

    Survival trees are a popular alternative to parametric survival modeling when there are interactions between the predictor variables or when the aim is to stratify patients into prognostic subgroups. A limitation of classical survival tree methodology is that most algorithms for tree construction are designed for continuous outcome variables. Hence, classical methods might not be appropriate if failure time data are measured on a discrete time scale (as is often the case in longitudinal studies where data are collected, e.g., quarterly or yearly). To address this issue, we develop a method for discrete survival tree construction. The proposed technique is based on the result that the likelihood of a discrete survival model is equivalent to the likelihood of a regression model for binary outcome data. Hence, we modify tree construction methods for binary outcomes such that they result in optimized partitions for the estimation of discrete hazard functions. By applying the proposed method to data from a randomized trial in patients with filarial lymphedema, we demonstrate how discrete survival trees can be used to identify clinically relevant patient groups with similar survival behavior. PMID:26358826

  18. 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.

  19. Time Dependence of the Survival Probability of AN Opinion in a Closed Community

    NASA Astrophysics Data System (ADS)

    Aydiner, Ekrem; Gönülol, Meltem

    The time dependence of the survival probability of an opinion in a closed community has been investigated in accordance with social temperature by using the Kawasaki-exchange dynamics based on previous study in Ref. 1. It is shown that the survival probability of opinion decays with stretched exponential law consistent with previous static model. However, the crossover regime in the decay of the survival probability has been observed in this dynamic model unlike previous model. The decay characteristics of both regimes obey to stretched exponential.

  20. Postmortem serum erythropoietin level as a marker of survival time in injury deaths.

    PubMed

    Quan, L; Zhu, B-L; Ishikawa, T; Michiue, T; Zhao, D; Ogawa, M; Maeda, H

    2010-07-15

    Circulating erythropoietin (EPO) is mainly derived from the kidneys, and the serum concentration is rapidly increased in response to anemia and hypoxia. The present study investigated postmortem serum EPO levels in injury death cases (n=185, postmortem time<48 h, survival time <7 days: sharp instrument injury, n=44 and blunt injury, n=141) with regard to survival time, compared with C-reactive protein (CRP) as a marker of inflammation. Serum levels of both markers were independent of postmortem time. A survival time-dependent increase in serum EPO up to about 100 mU/ml was seen within 6h of sharp instrument injury to the heart or a proximal major vessel (thoracic aorta or subclavian/carotid artery) and blunt injury with massive hemorrhages, showing high correlations (r=0.957 and r=0.822, respectively, P<0.0001), whereas the increase was insignificant (P>0.05) for sharp instrument injury to a peripheral vessel or lungs/abdominal viscera and blunt injury with minor hemorrhages over the same survival period. A further increase (>100 mU/ml) was often detected in cases of death about 24h after blunt injury, irrespective of the type of injury. In contrast, a gradual increase in serum CRP level was seen about 12-24h after blunt injury. These findings suggest that serum EPO can be a marker for investigating survival time within 6h of major injury involving acute massive hemorrhaging. PMID:20430543

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    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 KN and the star graph K1 ,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 τc that, at least for KN and K1 ,N -1, correctly scales with the number of nodes N and that is superior to the epidemic threshold τc(1 )=1/λ1 of the N-intertwined mean-field approximation, where λ1 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/τc(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.

  4. Survival probabilities with time-dependent treatment indicator: quantities and non-parametric estimators.

    PubMed

    Bernasconi, Davide Paolo; Rebora, Paola; Iacobelli, Simona; Valsecchi, Maria Grazia; Antolini, Laura

    2016-03-30

    The 'landmark' and 'Simon and Makuch' non-parametric estimators of the survival function are commonly used to contrast the survival experience of time-dependent treatment groups in applications such as stem cell transplant versus chemotherapy in leukemia. However, the theoretical survival functions corresponding to the second approach were not clearly defined in the literature, and the use of the 'Simon and Makuch' estimator was criticized in the biostatistical community. Here, we review the 'landmark' approach, showing that it focuses on the average survival of patients conditional on being failure free and on the treatment status assessed at the landmark time. We argue that the 'Simon and Makuch' approach represents counterfactual survival probabilities where treatment status is forced to be fixed: the patient is thought as under chemotherapy without possibility to switch treatment or as under transplant since the beginning of the follow-up. We argue that the 'Simon and Makuch' estimator leads to valid estimates only under the Markov assumption, which is however less likely to occur in practical applications. This motivates the development of a novel approach based on time rescaling, which leads to suitable estimates of the counterfactual probabilities in a semi-Markov process. The method is also extended to deal with a fixed landmark time of interest. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26503800

  5. Hyperferritinemia is associated with short survival time in dogs with multicentric lymphoma

    PubMed Central

    CHIKAZAWA, Seishiro; HORI, Yasutomo; HOSHI, Fumio; KANAI, Kazutaka; ITO, Naoyuki

    2015-01-01

    In the present study, we examined the relationship between serum ferritin concentration before treatment and survival time in dogs with multicentric lymphoma. Eighteen dogs with multicentric lymphoma were enrolled in the study. When the dogs were classified into high and low ferritin groups on the basis of their serum ferritin concentration (3,000 ng/ml cut-off value), the median survival time of dogs with high concentrations (≥3,000 ng/ml, n=7) was 40 days, whereas it was 360 days among dogs with low concentrations (<3,000 ng/ml, n=11). This difference was statistically significant (P=0.001). This finding suggests that the initial high level of serum ferritin indicates short survival time in dogs with multicentric lymphoma. Large-scale research is necessary to confirm this finding. PMID:25715650

  6. 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…

  7. 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. PMID:10830539

  8. TOUGH User's Guide

    SciTech Connect

    Pruess, K.

    1987-08-01

    This document contains a technical description of the TOUGH computer program, which was developed at Lawrence Berkeley Laboratory for simulating the coupled transport of water, vapor, air and heat in porous and fractured media. The physical processes taken into account in TOUGH are discussed, and the governing equations actually solved by the simulator are stated in full detail. A brief overview is given of the mathematical and numerical methods, and the code architecture. The report provides detailed instructions for preparing input decks. Code applications are illustrated by means of six sample problems.

  9. Estimation of time-shift models with application to survival calibration in health technology assessment.

    PubMed

    Titman, Andrew C

    2016-09-10

    The incremental life expectancy, defined as the difference in mean survival times between two treatment groups, is a crucial quantity of interest in cost-effectiveness analyses. Usually, this quantity is very difficult to estimate from censored survival data with a limited follow-up period. The paper develops estimation procedures for a time-shift survival model that, provided model assumptions are met, gives a reliable estimate of incremental life expectancy without extrapolation beyond the study period. Methods for inference are developed both for individual patient data and when only published Kaplan-Meier curves are available. Through simulation, the estimators are shown to be close to unbiased and constructed confidence intervals are shown to have close to nominal coverage for small to moderate sample sizes. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27037680

  10. 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.

  11. 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…

  12. Recidivism and Survival Time: Racial Disparity among Jail Ex-Inmates

    ERIC Educational Resources Information Center

    Jung, Hyunzee; Spjeldnes, Solveig; Yamatani, Hide

    2010-01-01

    Incarcerated men, most of whom are recidivists, are disproportionately black. Much literature about prison ex-inmates reports on this disparity, yet little is known about racial disparity in recidivism rates among jail ex-inmates. This study examined recidivism rates and survival time (period from release date to rearrest) among male ex-inmates…

  13. It's Deja Vu All over Again: Using Multiple-Spell Discrete-Time Survival Analysis.

    ERIC Educational Resources Information Center

    Willett, John B.; Singer, Judith D.

    1995-01-01

    The multiple-spell discrete-time survival analysis method is introduced and illustrated using longitudinal data on exit from and reentry into the teaching profession. The method is applicable to many educational problems involving the sequential occurrence of disparate events or episodes. (SLD)

  14. Increasing Metal Fracture Toughness

    NASA Technical Reports Server (NTRS)

    Lawing, P. L.; Wood, W. H.; Sandefur, P. G. J.

    1982-01-01

    In technique developed at Langley Research Center several thin sheets of metal are diffusion-brazed together in vacuum furnace to create thick piece of metal that retains much of fracture toughness of its thin components. Technique is expected to make many of high-strength stainless steels, not currently suitable, usable at cryogenic temperatures.

  15. Survival Rates with Time Course of Frozen-thawed Pacific Oyster Larvae in Indoor Rearing System

    PubMed Central

    Kim, Ki Tae; Lim, Han Kyu; Chang, Young Jin

    2013-01-01

    Post-thawed larval rearing in Pacific oyster Crassostrea gigas was performed to investigate the survival rate with time course in three kinds of larvae cryopreserved. The highest survival rate and larval activity index (LAI) of post-thawed larvae were obtained from the permeation in 0.2 M sucrose and 2.0 M ethylene glycol (EG) at -1°C/min in freezing speed showing the survival rates just after thawing of 63.8% in trochophore, 84.1% in D-shaped veliger and 56.3% in early umbo veliger. In post-thawed larval rearing with food supply, the larvae lasted their lives until 24 hours in trochophore, 75 hours in D-shaped veliger and 57 hours in early umbo veliger. The results suggested that each larval stage post-thawed revealed no more further development to subsequent respective stage. PMID:25949149

  16. 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.

  17. Relationship of Tricuspid Repair at the time of Left Ventricular Assist Device Implantation and Survival

    PubMed Central

    Brewer, Robert J.; Cabrera, Rafael; El-Atrache, Mazen; Zafar, Amna; Hrobowski, Tara N.; Nemeh, Hassan M.; Selektor, Yelena; Paone, Gaetano; Williams, Celeste T.; Velez, Mauricio; Tita, Cristina; Morgan, Jeffrey A.; Lanfear, David E.

    2015-01-01

    Purpose Tricuspid regurgitation contributes to right ventricular failure (RVF) and is associated with worse clinical outcomes in patients undergoing Left Ventricular Assist Device (LVAD). However, whether tricuspid valve repair (TVR) at the time of LVAD implantation improves outcomes is not clear. Methods We identified all patients undergoing initial implantation of a long-term continuous flow LVAD at our institution from 3/2006 to 8/2011. We assessed the impact of TVR on survival and incidence of RVF using Kaplan-Meier curves and proportional hazards regression adjusted for age, gender, baseline tricuspid regurgitation, RV function, MELD score, albumin, and indication (bridge vs. destination). Results A total of 101 patients were included in the analysis, of which 14 patients underwent TVR concomitant LVAD. All TVR patients had moderate or severe baseline regurgitation. Crude survival was not different between groups. In multivariable models adjusted for confounding factors, TVR showed a significant association with improved survival (HR=0.1, p=0.049). Adjusted models showed no difference in RVF. Conclusions In this cohort of patients TVR at the time of LVAD implantation appears associated with better survival. Additional larger studies are needed to verify the effect of TVR at the time of LVAD implantation, and whether it should be utilized more frequently. PMID:25450319

  18. Sex, Race, and Age Disparities in the Improvement of Survival for Gastrointestinal Cancer over Time

    PubMed Central

    Wan, Jue-feng; Yang, Li-feng; Shen, Yun-zhu; Jia, Hui-xun; Zhu, Ji; Li, Gui-chao; Zhang, Zhen

    2016-01-01

    There have been notable improvements in survival over the past 2 decades for gastrointestinal (GI) cancer. However, the degree of improvement by age, race, and sex remains unclear. We analyzed data from 9 population-based cancer registries included in the SEER program of the National Cancer Institute (SEER 9) in 1990 to 2009 (n = 288,337). The degree of survival improvement over time by age, race, and sex was longitudinally measured. From 1990 to 2009, improvements in survival were greater for younger age groups. For patients aged 20 to 49 years and diagnosed from 2005 to 2009, adjusted HRs (95% CIs) were 0.74 (95% CI, 0.66–0.83), 0.49 (95% CI, 0.37–0.64), 0.69 (95% CI, 0.65–0.76), 0.62 (95% CI, 0.54–0.69), and 0.56 (95% CI, 0.42–0.76), for cancer of the stomach, small intestine, colon, rectum and anus, respectively, compared with the same age groups of patients diagnosed during 1990 to 1994. Compared with African Americans, whites experienced greater improvement in small intestinal and anal cancer survival. Female anal cancer and regional anal cancer patients experienced no improvement. Our data suggest that different improvement in survival in age, sex and race exists. PMID:27406065

  19. Pancreatic cancer: Wait times from presentation to treatment and survival in a population-based study.

    PubMed

    Jooste, Valérie; Dejardin, Olivier; Bouvier, Véronique; Arveux, Patrick; Maynadie, Marc; Launoy, Guy; Bouvier, Anne-Marie

    2016-09-01

    Pancreatic survival is one of the worst in oncology. To what extent wait times affect outcomes in unknown No population-based study has previously explored patient and treatment delays among individuals with pancreatic cancer. The aim of this study was to estimate patient and treatment delays in patients with pancreatic cancer and to measure their association with survival in a nonselected population. All patients diagnosed with pancreatic cancer for the first time between 2009 and 2011 and registered in two French digestive cancer registries were included. Patient delay (time from onset of symptoms until the first consultation categorized into <1 or ≥1 month), and treatment delay (time between the first consultation and treatment categorized into less or more than 29 days, the median time) were collected. Overall delay was used to test associations between survival and the timeliness of care by combining patient delay and treatment delay. Patient delay was longer than 1 month in 46% of patients. A patient delay longer than one month was associated with the absence of jaundice (p < 0.001) and the presence of metastasis (p = 0.003). After adjusting for other covariates, such as symptoms and treatment, the presence of metastasis was negatively associated with treatment delay longer than 29 days (p = 0.025). After adjustment for other covariates, especially metastatic dissemination and the result of the resection, overall delay was not significantly associated with prognosis. We found little evidence to suggest that timely care was associated with the survival of patients. PMID:27130333

  20. A Simple Scoring System Predicting the Survival Time of Patients with Bone Metastases after RT

    PubMed Central

    Zhang, Wen-Yi; Li, Hui-Fang; Su, Meng; Lin, Rui-Fang; Chen, Xing-Xing; Zhang, Ping; Zou, Chang-Lin

    2016-01-01

    Objectives This study aimed to develop a scoring system to predict the survival time of patients with bone metastases after radiation therapy (RT). The scoring system can guide physicians to a better selection of appropriate treatment regimens. Materials and Methods The medical records of 125 patients with bone metastases treated with RT between January 2007 and September 2010 were reviewed retrospectively. Fifteen potential prognostic factors were investigated: sex, age, Karnofsky performance score (KPS), type of primary tumor, resection of tumor before bone metastases, interval between primary tumor diagnosis and diagnosis of bone metastases, Carcinoembryonic Antigen(CEA), lung metastases before bone metastases, liver metastases before bone metastases, brain metastases before bone metastases, stage, T, N, M, and degree of cellular differentiation. Results In an univariate analysis, 10 factors were significantly associated with survival time after bone metastasis: sex, KPS, breast cancer, esophageal cancer, colorectal cancer, interval between tumor diagnosis and diagnosis of bone metastases, CEA, lung metastases before bone metastases, T-staging, and differentiation. In a multivariate analysis, 7 factors were found to be significant: sex, KPS, esophageal cancer, colorectal cancer, interval between tumor diagnosis and diagnosis of bone metastases, T-staging, and differentiation. The median survival of all patients with bone metastases after RT was 14.1 months. There were significant differences in the median survival of patients with bone metastases after RT of 4.9 months, 10.5 months, and 29.7 months in groups 1, 2, and 3, respectively (P<0.001). Conclusion According to this scoring system, the survival time of patients after bone metastasis can be estimated. PMID:27438606

  1. 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

  2. Postmortem serum erythropoietin levels in establishing the cause of death and survival time at medicolegal autopsy.

    PubMed

    Quan, L; Zhu, B-L; Ishikawa, T; Michiue, T; Zhao, D; Li, D-R; Ogawa, M; Maeda, H

    2008-11-01

    Circulating erythropoietin (EPO) is mainly produced in the kidneys, depending on blood oxygen level. The present study investigated the postmortem serum EPO levels with regard to the cause of death and survival time. Serial medicolegal autopsy cases of postmortem time within 48 h (n = 536) were examined. Serum EPO levels were within the clinical reference range in most cases. Uremic patients with medical administration of an EPO agent (n = 11) showed a markedly high level (140-4,850 mU/ml; median, 1,798 mU/ml). Otherwise, an elevation in serum EPO level (>30 mU/ml) was mainly seen in protracted deaths due to blunt injury and fire fatality, depending on the survival time (r = 0.69, p < 0.0001, and r = 0.45, p < 0.0001, respectively), and in subacute deaths from gastrointestinal bleeding and infectious diseases. However, mildly to moderately elevated serum EPO levels were sporadically found in acute deaths due to mechanical asphyxiation, fire fatality, and acute ischemic heart disease, and in fatal hypothermia cases, especially for elderly subjects. Protracted deaths due to mechanical asphyxiation and ischemic heart disease did not show any survival time-dependent increase in serum EPO level (p > 0.05). EPO was immunohistochemically detected in the tubular epithelia and interstitial cells, showing no evident difference among the causes of death, independent of survival time or serum level. These findings suggest that serum EPO can be used as a marker for investigating anemia and/or hypoxia as a consequence of fatal insult in subacute or prolonged deaths, or a predisposition to traumatic deaths or fatal heart attacks in acute deaths. PMID:18682967

  3. 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.

  4. 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. PMID:25766418

  5. 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.

  6. 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

  7. Daily controlled physiotherapy increases survival time in dogs with suspected degenerative myelopathy.

    PubMed

    Kathmann, I; Cizinauskas, S; Doherr, M G; Steffen, F; Jaggy, A

    2006-01-01

    The purposes of the study reported here were to evaluate the signalment and clinical presentation in 50 dogs with degenerative myelopathy, to evaluate whether mean survival time was significantly affected by various means of physiotherapy performed in 22 dogs, and to determine whether neurologic status, anatomic localization, or age at onset had an influence on survival time in dogs that received physiotherapy. We found a significant (P < .05) breed predisposition for the German Shepherd Dog, Kuvasz, Hovawart, and Bernese Mountain Dog. Mean age at diagnosis was 9.1 years, and both sexes were affected equally. The anatomic localization of the lesion was spinal cord segment T3-L3 in 56% (n = 28) and L3-S3 in 44% (n = 22) of the dogs. Animals that received intensive (n = 9) physiotherapy had longer (P < .05) survival time (mean 255 days), compared with that for animals with moderate (n = 6; mean 130 days) or no (n = 7; mean 55 days) physiotherapy. In addition, our results indicate that affected dogs which received physiotherapy remained ambulatory longer than did animals that did not receive physical treatment. PMID:16955818

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

    PubMed

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

    2016-01-01

    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

  9. Extended survival times of Mycoplasma gallisepticum and Mycoplasma synoviae on kanekalon synthetic hair fibres.

    PubMed

    Abolnik, Celia; Gouws, Johan

    2014-01-01

    The survival times of Mycoplasma gallisepticum (Mg) and Mycoplasma synoviae (Ms) on washed and unwashed natural and synthetic kanekalon hair samples over a 5-d period were evaluated using the color changing unit method for comparison with results of previous studies conducted on natural hair. Regardless of whether synthetic or natural hair samples prewashed with a disinfectant shampoo were spiked with Mg or Ms, all viable organisms rapidly dropped below a count of 1 × 10(1)/mL of culture. Unwashed natural hair seeded with a titer of approximately 1 × 10(6)/mL of viable Mg or Ms decreased to 6 × 10(5)/mL and 6 × 10(3)/mL, respectively, by 4 h postseeding, but no viable Mg or Ms were detected on natural hair from 8 h onwards. By contrast, the titers of Mg and Ms on synthetic hair did not decline from the initial 1 × 10(6)/mL seed dose up to 96 h postseeding, and, in fact, viable Mg and Ms was still detectable at 9 d postinfection. Application of a real-time quantitative single-tube duplex PCR assay confirmed that no proliferation of Mg or Ms had occurred on the synthetic hair samples, the cells simply remained viable. The unexpected finding that Mg and Ms survive for extended periods on synthetic kanekalon hair fibers raises the question of whether attachment to a surface is a prerequisite for the survival and persistence of Mg and Ms in the extra-host environment. Future studies should be aimed at determining whether other synthetic hair types or indeed other types of plastics commonly found in the poultry house offer similar survival advantages to mycoplasmas. PMID:24570416

  10. It's About Time: A Survival Approach to Gestational Weight Gain and Preterm Delivery.

    PubMed

    Mitchell, Emily M; Hinkle, Stefanie N; Schisterman, Enrique F

    2016-03-01

    There is substantial interest in understanding the impact of gestational weight gain on preterm delivery (delivery <37 weeks). The major difficulty in analyzing the association between gestational weight gain and preterm delivery lies in their mutual dependence on gestational age, as weight naturally increases with increasing pregnancy duration. In this study, we untangle this inherent association by reframing preterm delivery as time to delivery and assessing the relationship through a survival framework, which is particularly amenable to dealing with time-dependent covariates, such as gestational weight gain. We derive the appropriate analytical model for assessing the relationship between weight gain and time to delivery when weight measurements at multiple time points are available. Since epidemiologic data may be limited to weight gain measurements taken at only a few time points or at delivery only, we conduct simulation studies to illustrate how several strategically timed measurements can yield unbiased risk estimates. Analysis of the study of successive small-for-gestational-age births demonstrates that a naive analysis that does not account for the confounding effect of time on gestational weight gain suggests a strong association between higher weight gain and later delivery (hazard ratio: 0.89, 95% confidence interval = 0.84, 0.93). Properly accounting for the confounding effect of time using a survival model, however, mitigates this bias (hazard ratio: 0.98, 95% confidence interval = 0.97, 1.00). These results emphasize the importance of considering the effect of gestational age on time-varying covariates during pregnancy, and the proposed methods offer a convenient mechanism to appropriately analyze such data.See Video Abstract at http://links.lww.com/EDE/B13. PMID:26489043

  11. 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

  12. 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. PMID:26093630

  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 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

  15. 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. PMID:27350897

  16. 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. PMID:26644374

  17. Chaotic dynamics of Comet 1P/Halley: Lyapunov exponent and survival time expectancy

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    The orbital elements of Comet Halley are known to a very high precision, suggesting that the calculation of its future dynamical evolution is straightforward. In this paper we seek to characterize the chaotic nature of the present day orbit of Comet Halley and to quantify the time-scale over which its motion can be predicted confidently. In addition, we attempt to determine the time-scale over which its present day orbit will remain stable. Numerical simulations of the dynamics of test particles in orbits similar to that of Comet Halley are carried out with the MERCURY 6.2 code. On the basis of these we construct survival time maps to assess the absolute stability of Halley's orbit, frequency analysis maps to study the variability of the orbit, and we calculate the Lyapunov exponent for the orbit for variations in initial conditions at the level of the present day uncertainties in our knowledge of its orbital parameters. On the basis of our calculations of the Lyapunov exponent for Comet Halley, the chaotic nature of its motion is demonstrated. The e-folding time-scale for the divergence of initially very similar orbits is approximately 70 yr. The sensitivity of the dynamics on initial conditions is also evident in the self-similarity character of the survival time and frequency analysis maps in the vicinity of Halley's orbit, which indicates that, on average, it is unstable on a time-scale of hundreds of thousands of years. The chaotic nature of Halley's present day orbit implies that a precise determination of its motion, at the level of the present-day observational uncertainty, is difficult to predict on a time-scale of approximately 100 yr. Furthermore, we also find that the ejection of Halley from the Solar system or its collision with another body could occur on a time-scale as short as 10 000 yr.

  18. 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.

  19. 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

  20. Diabetes Mellitus as a Risk Factor in Glaucoma's Physiopathology and Surgical Survival Time: A Literature Review.

    PubMed

    Costa, Lívio; Cunha, João Paulo; Amado, Duarte; Pinto, Luís Abegão; Ferreira, Joana

    2015-01-01

    Glaucoma is a multifactorial condition under serious influence of many risk factors. The role of diabetes mellitus (DM) in glaucoma etiology or progression remains inconclusive. Although, the diabetic patients have different healing mechanism comparing to the general population and it has a possible-negative role on surgical outcomes. This review article attempts to analyze the association of both diseases, glaucoma and DM, before and after the surgery. The epidemiological studies, based mainly in population prevalence analyzes, have shown opposite outcomes in time and even in the most recent articles also the association remains inconclusive. On the contrary, the experimental models based on animal induced chronic hyperglycemia have shown an important association of both diseases, explained by common neurodegenerative mechanisms. Diabetic patients have a different wound healing process in the eye viz-a-viz other organs. The healing process is more and it results in lower surgical survival time, higher intraocular pressure (IOP) levels and, therefore, these patients usually need more medication to lower the IOP. Both randomized and nonrandomized retrospective and experimental molecular studies have shown the association between DM and glaucoma. Further studies are needed to get better explanations about outcomes on more recent surgical procedures and with the exponential use of antifibrotics. How to cite this article: Costa L, Cunha JP, Amado D, Pinto LA, Ferreira J. Diabetes Mellitus as a Risk Factor in Glaucoma's Physiopathology and Surgical Survival Time: A Literature Review. J Curr Glaucoma Pract 2015;9(3):81-85. PMID:26997842

  1. 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?

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

    PubMed

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

    2015-02-01

    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

  3. 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

  4. Fracture toughness of anisotropic graphites

    SciTech Connect

    Kennedy, C.R.; Kehne, M.T.

    1985-01-01

    Fracture toughness measurements have been made at 0, 30, 45, 60, and 90/sup 0/ from the extrusion axis on a reasonably anisotropic graphite, grade AGOT. It was found that the fracture toughness did not vary appreciably with orientation. An observed variation in strength was found to be the result of defect orientation.

  5. 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 are transformationally related. (17…

  6. 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.

  7. Age and Sex of Mice Markedly Affect Survival Times Associated with Hyperoxic Acute Lung Injury

    PubMed Central

    Prows, Daniel R.; Gibbons, William J.; Smith, Jessica J.; Pilipenko, Valentina; Martin, Lisa J.

    2015-01-01

    Mortality associated with acute lung injury (ALI) remains substantial, with recent estimates of 35–45% similar to those obtained decades ago. Although evidence for sex-related differences in ALI mortality remains equivocal, death rates differ markedly for age, with more than 3-fold increased mortality in older versus younger patients. Strains of mice also show large differences in ALI mortality. To tease out genetic factors affecting mortality, we established a mouse model of differential hyperoxic ALI (HALI) survival. Separate genetic analyses of backcross and F2 populations generated from sensitive C57BL/6J (B) and resistant 129X1/SvJ (X1) progenitor strains identified two quantitative trait loci (QTLs; Shali1 and Shali2) with strong, equal but opposite, within-strain effects on survival. Congenic lines confirmed these opposing QTL effects, but also retained the low penetrance seen in the 6–12 week X1 control strain. Sorting mice into distinct age groups revealed that ‘age at exposure’ inversely correlated with survival time and explained reduced penetrance of the resistance trait. While B mice were already sensitive by 6 weeks old, X1 mice maintained significant resistance up to 3–4 weeks longer. Reanalysis of F2 data gave analogous age-related findings, and also supported sex-specific linkage for Shali1 and Shali2. Importantly, we have demonstrated in congenic mice that these age effects on survival correspond with B alleles for Shali1 (6-week old mice more sensitive) and Shali2 (10-week old mice more resistant) placed on the X1 background. Further studies revealed significant sex-specific survival differences in subcongenics for both QTLs. Accounting for age and sex markedly improved penetrance of both QTLs, thereby reducing trait variability, refining Shali1 to <8.5Mb, and supporting several sub-QTLs within the Shali2 interval. Together, these congenics will allow age- and sex-specific studies to interrogate myriad subphenotypes affected during ALI

  8. 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.

  9. Survival time prediction of patients with glioblastoma multiforme tumors using spatial distance measurement

    NASA Astrophysics Data System (ADS)

    Zhou, Mu; Hall, Lawrence O.; Goldgof, Dmitry B.; Gillies, Robert J.; Gatenby, Robert A.

    2013-02-01

    Regional variations in tumor blood flow and necrosis are commonly observed in cross sectional imaging of clinical cancers. We hypothesize that radiologically-defined regional variations in tumor characteristics can be used to define distinct "habitats" that reflect the underlying evolutionary dynamics. Here we present an experimental framework to extract spatially-explicit variations in tumor features (habitats) from multiple MRI sequences performed on patients with Glioblastoma Multiforme (GBM). The MRI sequences consist of post gadolinium T1-weighted, FLAIR, and T2-weighted images from The Cancer Genome Atlas (TCGA). Our strategy is to identify spatially distinct, radiologically-defined intratumoral habitats by characterizing each small tumor regions based on their combined properties in 3 different MRI sequences. Initial tumor identification was performed by manually drawing a mask on a T1-weighted post contrast image slice. The extracted tumor was segmented into an enhancing and non-enhancing region by the Otsu segmentation algorithm, followed by a mask mapping procedure onto the corresponding FLAIR and T2-weighted images. Then Otsu was applied on the FLAIR and T2 images separately. We find that tumor heterogeneity measured through Distance Features (DF) can be used as a strong predictor of survival time. In an initial cohort of 16 cases slow progressing tumors have lower DF values (are less heterogeneous) compared to those with fast progression and short survival times.

  10. 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.

  11. 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

  12. 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

  13. 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. PMID:23855019

  14. 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…

  15. Fracture toughness of metallic glasses: annealing-induced embrittlement.

    PubMed

    Rycroft, Chris H; Bouchbinder, Eran

    2012-11-01

    Quantitative understanding of the fracture toughness of metallic glasses, including the associated ductile-to-brittle (embrittlement) transitions, is not yet available. Here, we use a simple model of plastic deformation in glasses, coupled to an advanced Eulerian level set formulation for solving complex free-boundary problems, to calculate the fracture toughness of metallic glasses as a function of the degree of structural relaxation corresponding to different annealing times near the glass temperature. Our main result indicates the existence of an elastoplastic crack tip instability for sufficiently relaxed glasses, resulting in a marked drop in the toughness, which we interpret as annealing-induced embrittlement transition similar to experimental observations. PMID:23215386

  16. 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

  17. 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

  18. TOUGH V2.1

    Energy Science and Technology Software Center (ESTSC)

    2011-06-01

    TOUGH2 is a numerical simulator for nonisothermal flows of multicomponent, multiphase fluids in one-, two-, and three-dimensional porous and fracture media. The chief applications for which TOUGH2 is designed are in geothermal reservoir engineering, nuclear waste disposal, environmental assessment and remediation, geologic carbon sequestration, and unsaturated and saturated zone hydrology. The TOUGH2 V2.1 package is an upgrade of TOUGH2 V2.0 (CR-1574) and includes the following improvements and enhancements relative to TOUGH2 V2.0: - Includes allmore » known bug fixes - The module TMVOC (CR-1820) is fully integrated - The module ECO2N (CR-2202) is fully integrated - A fluid property module ECO2M has been added, that can seamlessly model CO2 storage and leakage scenarios, including transitions between super- and sub-critical fluids, and phase changes between liquid and gaseous CO2. The TOUGH2 V2.1 package also supports all legacy fluid property modules, i.e., those packaged into TOUGH2 V2.0 (CR-1574), which includes T2VOC (CR-1254).« less

  19. TOUGH V2.1

    SciTech Connect

    2011-06-01

    TOUGH2 is a numerical simulator for nonisothermal flows of multicomponent, multiphase fluids in one-, two-, and three-dimensional porous and fracture media. The chief applications for which TOUGH2 is designed are in geothermal reservoir engineering, nuclear waste disposal, environmental assessment and remediation, geologic carbon sequestration, and unsaturated and saturated zone hydrology. The TOUGH2 V2.1 package is an upgrade of TOUGH2 V2.0 (CR-1574) and includes the following improvements and enhancements relative to TOUGH2 V2.0: - Includes all known bug fixes - The module TMVOC (CR-1820) is fully integrated - The module ECO2N (CR-2202) is fully integrated - A fluid property module ECO2M has been added, that can seamlessly model CO2 storage and leakage scenarios, including transitions between super- and sub-critical fluids, and phase changes between liquid and gaseous CO2. The TOUGH2 V2.1 package also supports all legacy fluid property modules, i.e., those packaged into TOUGH2 V2.0 (CR-1574), which includes T2VOC (CR-1254).

  20. EFFECT OF TRITIUM AND DECAY HELIUM ON WELDMENT FRACTURE TOUGHNESS

    SciTech Connect

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

    2006-09-26

    The fracture toughness data collected in this study are needed to assess the long-term effects of tritium and its decay product on tritium reservoirs. The results show that tritium and decay helium have negative effects on the fracture toughness properties of stainless steel and its weldments. The data and report from this study has been included in a material property database for use in tritium reservoir modeling efforts like the Technology Investment Program ''Lifecycle Engineering for Tritium Reservoirs''. A number of conclusions can be drawn from the data: (1) For unexposed Type 304L stainless steel, the fracture toughness of weldments was two to three times higher than the base metal toughness. (2) Tritium exposure lowered the fracture toughness properties of both base metals and weldments. This was characterized by lower J{sub Q} values and lower J-da curves. (3) Tritium-exposed-and-aged base metals and weldments had lower fracture toughness values than unexposed ones but still retained good toughness properties.

  1. Survive, help, learn: experience of a medical journal in war and post-war times.

    PubMed

    Sambunjak, Dario; Ivanis, Ana

    2006-07-01

    Medical journals and their editors have a unique responsibility in armed conflicts. The experience of the Croatian Medical Journal during and after the 1991-1995 war in Croatia shows how a medical journal can survive, help others and learn in times of war. The first duty of a medical journal in such circumstances is to publish scientific articles on various aspects of war medicine, and to document cases of human rights abuses. In small scientific communities, editors can offer their expertise and assist authors in writing and publishing war-related research and reports. In post-conflict period, medical journals have a responsibility to participate in peace-building and reconciliation efforts. They can do so by publishing good scientific articles regardless of their place or country of origin, re-establishing contacts with colleagues from the opposing sides, striving for the multiethnic or multinational Editorial and Advisory Boards, and engaging in collaborative research and regional initiatives. PMID:16961192

  2. A model of survival times for predator populations: the case of the army ants.

    PubMed

    Britton, N F; Partridge, L W; Franks, N R

    1999-05-01

    We develop a method to estimate the expected time of survival of a predator population as a function of the size of the habitat island on which it lives and the dynamic parameters of the population and its prey. The model may be thought of either as a patch occupancy model for a structured population or as a model of metapopulation type. The method is applied to a keystone predator species, the neotropical army ant Eciton burchelli. Predictions are made as to how many of the islands and habitat islands in and around Gatun Lake in the Panama Canal, most of which were formed when the canal was dug, can be expected to support such a population today, and these are compared with data. PMID:17883227

  3. 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.

  4. Time-varying effects of prognostic factors associated with disease-free survival in breast cancer.

    PubMed

    Natarajan, Loki; Pu, Minya; Parker, Barbara A; Thomson, Cynthia A; Caan, Bette J; Flatt, Shirley W; Madlensky, Lisa; Hajek, Richard A; Al-Delaimy, Wael K; Saquib, Nazmus; Gold, Ellen B; Pierce, John P

    2009-06-15

    Early detection and effective treatments have dramatically improved breast cancer survivorship, yet the risk of relapse persists even 15 years after the initial diagnosis. It is important to identify prognostic factors for late breast cancer events. The authors investigated time-varying effects of tumor characteristics on breast-cancer-free survival using data on 3,088 breast cancer survivors from 4 US states who participated in a randomized dietary intervention trial in 1995-2006, with maximum follow-up through 15 years (median, 9 years). A piecewise constant penalized spline approach incorporating time-varying coefficients was adopted, allowing for deviations from the proportional hazards assumption. This method is more flexible than standard approaches, provides direct estimates of hazard ratios across time intervals, and is computationally tractable. Having a stage II or III tumor was associated with a 3-fold higher hazard of breast cancer than having a stage I tumor during the first 2.5 years after diagnosis; this hazard ratio decreased to 2.1 after 7.7 years, but higher tumor stage remained a significant risk factor. Similar diminishing effects were found for poorly differentiated tumors. Interestingly, having a positive estrogen receptor status was protective up to 4 years after diagnosis but detrimental after 7.7 years (hazard ratio = 1.5). These results emphasize the importance of careful statistical modeling allowing for possibly time-dependent effects in long-term survivorship studies. PMID:19403844

  5. Time-Varying Effects of Prognostic Factors Associated With Disease-Free Survival in Breast Cancer

    PubMed Central

    Natarajan, Loki; Pu, Minya; Parker, Barbara A.; Thomson, Cynthia A.; Caan, Bette J.; Flatt, Shirley W.; Madlensky, Lisa; Hajek, Richard A.; Al-Delaimy, Wael K.; Saquib, Nazmus; Gold, Ellen B.

    2009-01-01

    Early detection and effective treatments have dramatically improved breast cancer survivorship, yet the risk of relapse persists even 15 years after the initial diagnosis. It is important to identify prognostic factors for late breast cancer events. The authors investigated time-varying effects of tumor characteristics on breast-cancer-free survival using data on 3,088 breast cancer survivors from 4 US states who participated in a randomized dietary intervention trial in 1995–2006, with maximum follow-up through 15 years (median, 9 years). A piecewise constant penalized spline approach incorporating time-varying coefficients was adopted, allowing for deviations from the proportional hazards assumption. This method is more flexible than standard approaches, provides direct estimates of hazard ratios across time intervals, and is computationally tractable. Having a stage II or III tumor was associated with a 3-fold higher hazard of breast cancer than having a stage I tumor during the first 2.5 years after diagnosis; this hazard ratio decreased to 2.1 after 7.7 years, but higher tumor stage remained a significant risk factor. Similar diminishing effects were found for poorly differentiated tumors. Interestingly, having a positive estrogen receptor status was protective up to 4 years after diagnosis but detrimental after 7.7 years (hazard ratio = 1.5). These results emphasize the importance of careful statistical modeling allowing for possibly time-dependent effects in long-term survivorship studies. PMID:19403844

  6. Fracture toughness of Alloy 600 and EN82H weld in air and water

    SciTech Connect

    Mills, W.J.; Brown, C.M.

    1999-06-01

    The fracture toughness of Alloy 600 and its weld, EN82H, was characterized in 54 C to 338 C air and hydrogenated water. Elastic-plastic J{sub IC} testing was performed due to the inherent high toughness of these materials. Alloy 600 exhibited excellent fracture toughness under all test conditions. While EN82H welds displayed excellent toughness in air and high temperature water, a dramatic toughness degradation occurred in water at temperatures below 149 C. Comparison of the cracking response in low temperature water with that for hydrogen-precharged specimens tested in air demonstrated that the loss in toughness is due to a hydrogen-induced intergranular cracking mechanism. At loading rates about approx. 1000 MPa {radical}m/h, the toughness in low temperature water is improved because there is insufficient time for hydrogen to embrittle grain boundaries. Electron fractographic examinations were performed to correlate macroscopic properties with key microstructural features and operative fracture mechanisms.

  7. 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. PMID:26896537

  8. 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. PMID:27308884

  9. 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.

  10. TOUGH-Fx/Hydrate

    Energy Science and Technology Software Center (ESTSC)

    2005-02-01

    TOUGH-Fx/HYORATL can model the non-isothermal gas release. phase behavior and flow of fluids and heat in complex geologic media. The code can simulate production from natural gas hydrate deposits in the subsurtace (i.e., in the permafrost and in deep ocean sediments), as well as laboratory experiments of hydrate dissociation/formation in porous/fractured media. T006H-Fx/HYDRATE vi .0 includes both an equilibrium and a kinetic model of hydrate Ibmiation and dissociation. The model accounts for heat and upmore » to four mass components-- i.e., water, CH4, hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dIssociation or formation, phase changes, and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects, and inhibItor-Induced effects.« less

  11. Time Interval between Trauma and Arthroscopic Meniscal Repair Has No Influence on Clinical Survival.

    PubMed

    van der Wal, Robert J P; Thomassen, Bregje J W; Swen, Jan-Willem A; van Arkel, Ewoud R A

    2016-07-01

    Arthroscopic meniscal repair is the gold standard for longitudinal peripheral meniscal tears. The time interval between trauma and meniscal repair remains controversial. The aim of this study was to evaluate failure rates and clinical outcome of arthroscopic meniscal repair in relation to chronicity of injury. A total of 238 meniscal repairs were performed in 234 patients. Anterior cruciate ligament (ACL) was reconstructed in almost all ACL-deficient knees (130 out of 133). Time interval between injury and repair was divided into acute (< 2 weeks), subacute (> 2 to < 12 weeks), and chronic (> 12 weeks). Patients completed postal questionnaires to evaluate clinical outcome and failure rates. Study instruments included Lysholm, Knee injury and Osteoarthritis Outcome Score (KOOS), and Tegner scoring systems. At a median follow-up of 41 months (interquartile range [IQR], 34-53 months) 55 medial and 10 lateral meniscal repairs failed (overall failure rate, 27%). There was a significant higher failure rate for medial meniscal repair (p < 0.05) and ACL-deficient knees without ACL reconstruction. Functional outcome scores showed only significant differences on the KOOS subscale "function in daily living" (95% confidence interval, 1.05-15.27, p < 0.05). No significant difference was found for any interval between trauma and repair. The interval between trauma and arthroscopic meniscal repair has no influence on the failure rate. Differences in survival rate of meniscal repair are more dependent on location of the lesion and ACL status, rather than chronicity of injury. PMID:26516071

  12. 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...

  13. Time preference and its relationship with age, health, and survival probability

    PubMed Central

    Chao, Li-Wei; Szrek, Helena; Pereira, Nuno Sousa; Pauly, Mark V.

    2009-01-01

    Although theories from economics and evolutionary biology predict that one's age, health, and survival probability should be associated with one's subjective discount rate (SDR), few studies have empirically tested for these links. Our study analyzes in detail how the SDR is related to age, health, and survival probability, by surveying a sample of individuals in townships around Durban, South Africa. In contrast to previous studies, we find that age is not significantly related to the SDR, but both physical health and survival expectations have a U-shaped relationship with the SDR. Individuals in very poor health have high discount rates, and those in very good health also have high discount rates. Similarly, those with expected survival probability on the extremes have high discount rates. Therefore, health and survival probability, and not age, seem to be predictors of one's SDR in an area of the world with high morbidity and mortality. PMID:20376300

  14. Tough2{_}MP: A parallel version of TOUGH2

    SciTech Connect

    Zhang, Keni; Wu, Yu-Shu; Ding, Chris; Pruess, Karsten

    2003-04-09

    TOUGH2{_}MP is a massively parallel version of TOUGH2. It was developed for running on distributed-memory parallel computers to simulate large simulation problems that may not be solved by the standard, single-CPU TOUGH2 code. The new code implements an efficient massively parallel scheme, while preserving the full capacity and flexibility of the original TOUGH2 code. The new software uses the METIS software package for grid partitioning and AZTEC software package for linear-equation solving. The standard message-passing interface is adopted for communication among processors. Numerical performance of the current version code has been tested on CRAY-T3E and IBM RS/6000 SP platforms. In addition, the parallel code has been successfully applied to real field problems of multi-million-cell simulations for three-dimensional multiphase and multicomponent fluid and heat flow, as well as solute transport. In this paper, we will review the development of the TOUGH2{_}MP, and discuss the basic features, modules, and their applications.

  15. Meta-analysis of time-to-event outcomes from randomized trials using restricted mean survival time: application to individual participant data.

    PubMed

    Wei, Yinghui; Royston, Patrick; Tierney, Jayne F; Parmar, Mahesh K B

    2015-09-20

    Meta-analysis of time-to-event outcomes using the hazard ratio as a treatment effect measure has an underlying assumption that hazards are proportional. The between-arm difference in the restricted mean survival time is a measure that avoids this assumption and allows the treatment effect to vary with time. We describe and evaluate meta-analysis based on the restricted mean survival time for dealing with non-proportional hazards and present a diagnostic method for the overall proportional hazards assumption. The methods are illustrated with the application to two individual participant meta-analyses in cancer. The examples were chosen because they differ in disease severity and the patterns of follow-up, in order to understand the potential impacts on the hazards and the overall effect estimates. We further investigate the estimation methods for restricted mean survival time by a simulation study. PMID:26099573

  16. 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

  17. 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.

  18. Dynamic fracture toughness determined using molecular dynamics

    SciTech Connect

    Swadener, J. G.; Baskes, M. I.; Nastasi, Michael Anthony,

    2004-01-01

    Molecular dynamics (MD) simulations of fracture in crystalline silicon are conducted in order to determine the dynamic fracture toughness. The MD simulations show how the potential energy released during fracture is partitioned into surface energy, energy stored in defects and kinetic energy. First, the MD fracture simulations are shown to produce brittle fracture and be in reasonable agreement with experimental results. Then dynamic hcture toughness is calculated as the sum of the surface energy and the energy stored as defects directly from the MD models. Models oriented to produce fracture on either (111) or (101) planes are used. For the (101) fracture orientation, equilibrium crack speeds of greater than 80% of the Rayleigh wave speed are obtained. Crack speeds initially show a steep increase with increasing energy release rate followed by a much more gradual increase. No plateau in crack speed is observed for static energy release rates up to 20 J/m{sup 2}. At the point where the change in crack speed behavior occur, the dynamic fracture toughness (J{sub d}) is still within 10% of two times the surface energy (2{gamma}{sub 0}) and changing very slowly. From these MD simulations, it appears that the change in crack speed behavior is due to a change in the kinetic energy generation during dynamic fracture. In addition, MD simulations of facture in silicon with defects were conducted. The addition of defects increases the inelastic dissipation and the energy stored in defects.

  19. 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

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

    PubMed

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

    2016-05-01

    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. Time to benefit for colorectal cancer screening: survival meta-analysis of flexible sigmoidoscopy trials

    PubMed Central

    Boscardin, W John; Stijacic-Cenzer, Irena; Lee, Sei J

    2015-01-01

    Objective To determine the time to benefit of using flexible sigmoidoscopy for colorectal cancer screening. Design Survival meta-analysis. Data sources A Cochrane Collaboration systematic review published in 2013, Medline, and Cochrane Library databases. Eligibility criteria Randomized controlled trials comparing screening flexible sigmoidoscopy with no screening. Trials with fewer than 100 flexible sigmoidoscopy screenings were excluded. Results Four studies were eligible (total n=459 814). They were similar for patients’ age (50-74 years), length of follow-up (11.2-11.9 years), and relative risk for colorectal cancer related mortality (0.69-0.78 with flexible sigmoidoscopy screening). For every 1000 people screened at five and 10 years, 0.3 and 1.2 colorectal cancer related deaths, respectively, were prevented. It took 4.3 years (95% confidence interval 2.8 to 5.8) to observe an absolute risk reduction of 0.0002 (one colorectal cancer related death prevented for every 5000 flexible sigmoidoscopy screenings). It took 9.4 years (7.6 to 11.3) to observe an absolute risk reduction of 0.001 (one colorectal cancer related death prevented for every 1000 flexible sigmoidoscopy screenings). Conclusion Our findings suggest that screening flexible sigmoidoscopy is most appropriate for older adults with a life expectancy greater than approximately 10 years. PMID:25881903

  2. End points for adjuvant therapy trials: has the time come to accept disease-free survival as a surrogate end point for overall survival?

    PubMed

    Gill, Sharlene; Sargent, Daniel

    2006-06-01

    The intent of adjuvant therapy is to eradicate micro-metastatic residual disease following curative resection with the goal of preventing or delaying recurrence. The time-honored standard for demonstrating efficacy of new adjuvant therapies is an improvement in overall survival (OS). This typically requires phase III trials of large sample size with lengthy follow-up. With the intent of reducing the cost and time of completing such trials, there is considerable interest in developing alternative or surrogate end points. A surrogate end point may be employed as a substitute to directly assess the effects of an intervention on an already accepted clinical end point such as mortality. When used judiciously, surrogate end points can accelerate the evaluation of new therapies, resulting in the more timely dissemination of effective therapies to patients. The current review provides a perspective on the suitability and validity of disease-free survival (DFS) as an alternative end point for OS. Criteria for establishing surrogacy and the advantages and limitations associated with the use of DFS as a primary end point in adjuvant clinical trials and as the basis for approval of new adjuvant therapies are discussed. PMID:16794241

  3. The Time to Clearance of Peripheral Blood Blasts Predicts Complete Remission and Survival in Chinese Adults with Acute Myeloid Leukemia.

    PubMed

    Li, Xiaoyang; Zhu, Hongming; Zhang, Yunxiang; Zhao, Weili; Mi, Jianqing; Hu, Jiong; Li, Junmin

    2016-01-01

    The value of clearance of peripheral blood blasts (PBB) as a predictor of outcomes in acute myeloid leukemia (AML) is controversial. To investigate the prognostic significance of the time to clearance of PBB after induction in Chinese patients with AML, a retrospective analysis of 146 patients with newly diagnosed AML at Shanghai Ruijin Hospital was performed. Patients were categorized into early blast clearance (EBC; ≤5 days) and delayed blast clearance (DBC; >5 days) groups based on a receiver operating characteristic analysis. Complete remission (CR) after induction chemotherapy was related to the time to clearance of PBB (p < 0.001). Relapse-free survival (RFS; p = 0.003) and overall survival (p < 0.001) were longer in the EBC group. Multivariate analysis demonstrated that the time to clearance of PBB and cytogenetic risk independently predicted CR and RFS. Early clearance of PBB after induction chemotherapy can be a significant predictor of survival outcomes in AML patients. PMID:26967450

  4. 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

  5. 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.

  6. Entrainment and Survival Time of the Llsvps: Effects of Flow in the Thermochemical Pile Interior

    NASA Astrophysics Data System (ADS)

    Mulyukova, E.; Steinberger, B. M.; Dabrowski, M.; Sobolev, S. V.

    2013-12-01

    One of the most robust results from tomographic studies is the existence of two antipodally located Large Low Shear Velocity Provinces (LLSVPs) at the base of the mantle, which appear to be chemically denser than the ambient mantle. Results from reconstruction studies (Torsvik et al., 2006) infer that the LLSVPs are stable, long-lived, and are sampled by deep mantle plumes that rise predominantly from their margins. The amount of the anomalous LLSVP-material that gets entrained into the rising plumes poses a constraint on the survival time of the LLSVPs, as well as on the plume buoyancy, on the lithospheric uplift associated with plume interaction and geochemical signature of the erupted lavas observed at the Earth's surface. Recent estimates for the plume responsible for the formation of the Siberian Flood Basalts give about 15% of entrained dense recycled oceanic crust, which made the hot mantle plume almost neutrally buoyant (Sobolev et al., 2011). If it wasn't for the destabilizing flow, or entrainment, by the hot rising plumes, the anomalously dense material in the Earth's deep mantle may have never made its way to the surface. In order for the entrainment to take place, the destabilizing viscous stresses acting on a volume of anomalously dense material must exceed the gravitationally stabilizing stresses associated with buoyancy. At what conditions are these criteria met in a dynamically active deep mantle? To investigate this question, we perform numerical simulations of thermal convection with presence of a chemically dense basal layer in a 2D Cartesian box. In agreement with other studies, we find that the governing parameters are the buoyancy ratio between the thermal and the chemical density anomalies, as well as the viscosity variations. We observe that for a range of these parameters, an internal convective flow in the interior of the dense layer can develop. This internal flow has an important effect on the evolution of the entire system. First of all

  7. 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.

  8. 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

  9. Fracture toughness curve shift method

    SciTech Connect

    Nanstad, R.K.; Sokolov, M.A.; McCabe, D.E.

    1995-10-01

    The purpose of this task is to examine the technical basis for the currently accepted methods for shifting fracture toughness curves to account for irradiation damage, and to work through national codes and standards bodies to revise those methods, if a change is warranted. During this reporting period, data from all the relevant HSSI Programs were acquired and stored in a database and evaluated. The results from that evaluation have been prepared in a draft letter report and are summarized here. A method employing Weibull statistics was applied to analyze fracture toughness properties of unirradiated and irradiated pressure vessel steels. Application of the concept of a master curve for irradiated materials was examined and used to measure shifts of fracture toughness transition curves. It was shown that the maximum likelihood approach gave good estimations of the reference temperature, T{sub o}, determined by rank method and could be used for analyzing of data sets where application of the rank method did not prove to be feasible. It was shown that, on average, the fracture toughness shifts generally exceeded the Charpy 41-J shifts; a linear least-squares fit to the data set yielded a slope of 1.15. The observed dissimilarity was analyzed by taking into account differences in effects of irradiation on Charpy impact and fracture toughness properties. Based on these comparisons, a procedure to adjust Charpy 41-J shifts for achieving a more reliable correlation with the fracture toughness shifts was evaluated. An adjustment consists of multiplying the 41-J energy level by the ratio of unirradiated to irradiated Charpy upper shelves to determine an irradiated transition temperature, and then subtracting the unirradiated transition temperature determined at 41 J. For LUS welds, however, an unirradiated level of 20 J (15 ft-1b) was used for the corresponding adjustment for irradiated material.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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. PMID:21666348

  15. Perceived Peer Behavior and the Timing of Sexual Debut in Rwanda: A Survival Analysis of Youth Data.

    ERIC Educational Resources Information Center

    Babalola, Stella

    2004-01-01

    This paper uses survival methods to assess the relationship between perceived peer behavior and the timing of first sex among Rwandan youth. The data derive from a 2001 survey among youth aged 15-24 years in four provinces: Kigali Ville, Butare, Kibuye, and Umutara. A total of 1327 male and female youth were interviewed through a structured…

  16. 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,...

  17. 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....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,...

  18. KMWin – A Convenient Tool for Graphical Presentation of Results from Kaplan-Meier Survival Time Analysis

    PubMed Central

    Gross, Arnd; Ziepert, Marita; Scholz, Markus

    2012-01-01

    Background Analysis of clinical studies often necessitates multiple graphical representations of the results. Many professional software packages are available for this purpose. Most packages are either only commercially available or hard to use especially if one aims to generate or customize a huge number of similar graphical outputs. We developed a new, freely available software tool called KMWin (Kaplan-Meier for Windows) facilitating Kaplan-Meier survival time analysis. KMWin is based on the statistical software environment R and provides an easy to use graphical interface. Survival time data can be supplied as SPSS (sav), SAS export (xpt) or text file (dat), which is also a common export format of other applications such as Excel. Figures can directly be exported in any graphical file format supported by R. Results On the basis of a working example, we demonstrate how to use KMWin and present its main functions. We show how to control the interface, customize the graphical output, and analyse survival time data. A number of comparisons are performed between KMWin and SPSS regarding graphical output, statistical output, data management and development. Although the general functionality of SPSS is larger, KMWin comprises a number of features useful for survival time analysis in clinical trials and other applications. These are for example number of cases and number of cases under risk within the figure or provision of a queue system for repetitive analyses of updated data sets. Moreover, major adjustments of graphical settings can be performed easily on a single window. Conclusions We conclude that our tool is well suited and convenient for repetitive analyses of survival time data. It can be used by non-statisticians and provides often used functions as well as functions which are not supplied by standard software packages. The software is routinely applied in several clinical study groups. PMID:22723912

  19. Tough, but Where's the Love?

    ERIC Educational Resources Information Center

    Coussey, Mary

    2008-01-01

    Every government wants to appear to be tough on asylum seekers. But in failing to offer newcomers immediate access to English language learning one runs the risk of missing out on significant economic and social cohesion benefits. In this article, the author argues that asylum seekers need to get English language support in their first six months…

  20. 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.

  1. Improving the toughness of ultrahigh strength steel

    SciTech Connect

    Soto, Koji

    2002-08-15

    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.

  2. 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.

  3. iTOUGH2 Command Reference

    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 detailed description of all iTOUGH2 commands.

  4. DISCRETE TIME SURVIVAL ANALYSIS OF LAMB MORTALITY IN A TERMINAL SIRE COMPOSITE POPULATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mortality records during the first year of life of 8,642 lambs from a composite population at the U.S. Meat Animal Research Center were studied using discrete survival analyses. Lamb mortality was studied across periods from birth to weaning, birth to 365 d of age and weaning to 365 d of age. Animal...

  5. 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.

  6. Small punch testing for fracture toughness measurement. Final report

    SciTech Connect

    Foulds, J.R.; Woytowitz, P.J.; Parnell, T.K.

    1995-06-01

    The fracture toughness of the material of an operating power plant structural component affects the flaw tolerance of the component. A lower toughness implies a lower flaw tolerance, and generally results in an increased concern for component integrity and higher operation and maintenance costs. Often, the material fracture toughness is unknown because it was never specified or measured, or because service conditions have resulted in its degradation to an unknown extent. Examples of in- service degradation include temper embrittlement of steam turbine rotor low alloy steels exposed to elevated temperatures and neutron irradiation embrittlement of nuclear reactor pressure vessel steels. Conventional test methods for measuring toughness require the removal of large material samples from the in-service component, which is generally impractical. However, the recent development of miniature sample removal systems and the small punch test technique (which utilizes non-standard, miniature specimens of 0.5 mm or 0.020 in. thickness) now provides a convenient, practical, and virtually nondestructive means of evaluating the material of an in-service component for toughness and related mechanical properties. The small punch test method follows an approach that is based on the continuum material toughness concept wherein the criterion for fracture is defined and measured via the continuum stress-strain deformation properties of the material. The procedure specifically involves computing the {open_quotes}local{close_quotes} strain energy density accumulated at the location and time of crack initiation in the small punch test specimen using large-strain finite element analysis. Since the procedure also includes estimation of the material uniaxial tensile stress-strain behavior from the small punch load-displacement curve, both the fracture toughness and the uniaxial tensile behavior are determined from a single small punch test.

  7. High-toughness graphite/epoxy composite material experiment

    NASA Technical Reports Server (NTRS)

    Felbeck, David K.

    1993-01-01

    This experiment was designed to measure the effect of near-earth space exposure on three mechanical properties of specially toughened 5208/T300 graphite/epoxy composite materials. The properties measured are elastic modulus, strength, and fracture toughness. Six toughness specimens and nine tensile specimens were mounted on an external frame during the 5.8-year orbit of the Long Duration Exposure Facility (LDEF). Three identical sets of specimens were manufactured at the outset: the flight set, a zero-time non-flight set, and a total-time non-flight set.

  8. Time-lagged variation in pond density and primary productivity affects duck nest survival in the Prairie Pothole Region.

    PubMed

    Walker, Johann; Rotella, Jay J; Stephens, Scott E; Lindberg, Mark S; Ringelman, James K; Hunter, Christine; Smith, Aaron J

    2013-07-01

    The Prairie Pothole Region (PPR) is the primary breeding region for most species of North American dabbling ducks (Anas spp.). Conservation of these species is guided in part by knowledge of relationships between nest survival probability and habitat features. Positive relationships between duck nest survival and amount and configuration of herbaceous perennial vegetation have been observed in previous studies, but these 2- to 4-year studies might not have adequately characterized the temporal effect of wet-dry episodes on nest survival. Over an eight-year period, we studied nest survival of five species of ducks in the PPR relative to spatial and temporal variation in pond density, primary productivity, and hydrologic status of wetlands, soil, and vegetation on 52 study sites selected to span a gradient of spatial variation in proportion of herbaceous perennial vegetation and in number of wetland basins. We observed the fate of 12 754 nests. Consistent with past studies, 90% of nests that failed to hatch were destroyed by predators. Nest survival probability was positively related to current-year pond density and primary productivity, negatively related to pond density and primary productivity during the previous two years, and positively related to the number of wetland basins on the study site. Predicted relationships between nest survival and proportion or configuration of herbaceous perennial vegetation in the surrounding landscape were not supported. For mallard (Anas platyrhynchos), median estimated nest survival probability ranged from 0.02 (SE = 0.01) to 0.22 (SE = 0.02). Estimated nest survival was greatest on sites with numerous wetland basins that had transitioned from dry, unproductive conditions to wet, productive conditions in the previous 1-2 years. Our results were consistent with time-lagged responses of food webs to resource pulses in a broad array of ecosystems. Our study highlighted the importance of wetland basins and wet-dry episodes to duck

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. Survival Benefit From Kidney Transplantation Using Kidneys From Deceased Donors Aged ≥75 Years: A Time-Dependent Analysis.

    PubMed

    Pérez-Sáez, M J; Arcos, E; Comas, J; Crespo, M; Lloveras, J; Pascual, J

    2016-09-01

    Patients with end-stage renal disease have longer survival after kidney transplantation than they would by remaining on dialysis; however, outcome with kidneys from donors aged ≥75 years and the survival of recipients of these organs compared with their dialysis counterparts with the same probability of obtaining an organ is unknown. In a longitudinal mortality study, 2040 patients on dialysis were placed on a waiting list, and 389 of them received a first transplant from a deceased donor aged ≥75 years. The adjusted risk of death and survival were calculated by non-proportional hazards analysis with being transplanted as a time-dependent effect. Projected years of life since placement on the waiting list was almost twofold higher for transplanted patients. Nonproportional adjusted risk of death after transplantation was 0.44 (95% confidence interval [CI] 0.61-0.32; p < 0.001) in comparison with those that remained on dialysis. Stratifying by age, adjusted hazard ratios for death were 0.17 (95% CI 0.47-0.06; p = 0.001) for those aged <65 years, 0.56 (95% CI 0.92-0.34; p = 0.022) for those aged 65-69 years and 0.82 (95% CI 1.28-0.52; p = 0.389) for those aged ≥70 years. Although kidney transplantation from elderly deceased donors is associated with reduced graft survival, transplanted patients have lower mortality than those remaining on dialysis. PMID:27004984

  16. 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.

  17. 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.

  18. 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.

  19. TOUGH2Viewer: A post-processing tool for interactive 3D visualization of locally refined unstructured grids for TOUGH2

    NASA Astrophysics Data System (ADS)

    Bonduá, S.; Berry, P.; Bortolotti, V.; Cormio, C.

    2012-09-01

    Within the MAC-GEO research project, funded by Regione Toscana and addressed to the exploitation of high enthalpy geothermal systems, the authors worked on the utilization and customization of the open source numerical simulator TOUGH2, as implemented in the code dedicated to model calibration iTOUGH2. TOUGH2 is one of the most used numerical simulation software for non-isothermal flow of multicomponent, multiphase fluids in one, two and three-dimensional porous and fractured media. Lacking an official Graphical User Interface tool for post-processing operations, several commercial and academic software have been developed to manage and display TOUGH2 input and output data files. Almost all of these tools seem to have limits to visualizing parameter values of the numerical model, work only with a predefined binary version of TOUGH2, and only a few of them can manage locally refined unstructured grids (i.e. Voronoi grids). To overcome these limitations, the authors have developed and tested a dedicated software application (called TOUGH2Viewer) for reading and managing TOUGH2 output files, written in Java and able to provide an interactive 3D view of the numerical model. Several functionalities have been implemented for block query and searching, contour mapping and 3D surface mapping of TOUGH2 primary variables (i.e. pressure, temperature, etc.). TOUGH2Viewer is also able to display 2D and 3D views of mass and heat flow between blocks, for each time step in which the simulation proceeds. The application described in this paper is under development to improve its functionalities; nevertheless the current software release is a valid support tool for post-processing that significantly improves the possibility to inspect the simulated data coming from TOUGH2.

  20. 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.

  1. 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.

  2. 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''.

  3. Prevalence of parasitism and adult survival time of Aedes albifasciatus (Diptera: Culicidae) parasitized by Strelkovimermis spiculatus (Nematoda: Mermithidae).

    PubMed

    Di Battista, Cristian M; Fischer, Sylvia; Campos, Raúl E

    2015-12-01

    We described the carryover of Strelkovimermis spiculatus (Poinar and Camino) (Nematoda: Mermithidae) from mosquito larvae, the primary site of maturation, to adults. We analyzed the survival time of male and female Aedes albifasciatus (Macquart) (Diptera: Culicidae) parasitized by S. spiculatus, the time of emergence of nematodes from adult mosquitoes, and the state of parasitism in the same mosquito cohorts during the immature stages. Mosquito larvae with single and multiple parasitism (up to 11 parasites) were observed. The mortality of mosquito larvae and adults was produced in all cases where at least one mermithid emerged. The mortality of S. spiculatus showed an increasing trend in mosquito larvae with larger numbers of nematodes and was higher in larvae parasitized by eight or more nematodes. Maximum survival of parasitized adult females of Ae. albifasciatus was 38 days, while non-parasitized adult males and females survived 39 and 41 days, respectively. Strelkovimermis spiculatus mortality was observed in Ae. albifasciatus larvae with single or multiple parasitisms. The spread of mermithid parasitism in adult mosquito populations is discussed. PMID:26611976

  4. Increased survival time after delayed histamine and prostaglandin blockade in a porcine model of severe sepsis-induced lung injury.

    PubMed

    Byrne, K; Sielaff, T D; Michna, B; Carey, P D; Blocher, C R; Vasquez, A; Sugerman, H J

    1990-03-01

    A combination of cimetidine, diphenhydramine, and ibuprofen has been shown to be an effective treatment in a porcine model of septic acute lung injury. The present study was designed to evaluate this therapy in a delayed treatment survival model. Three groups of animals were studied: a control group (C, n = 6) received a sham infusion of 0.9% saline; a septic group (Ps, n = 5) received a continuous infusion of live Pseudomonas aeruginosa organisms; and a treatment group (CID, n = 6) received P. aeruginosa plus cimetidine 150 mg, ibuprofen 12.5 mg/kg, and diphenhydramine 10 mg/kg given at 90 min after P. aeruginosa infusion, and hourly thereafter. Group Ps developed fulminant acute lung injury and hypodynamic septic shock. CID therapy ameliorated temporarily the progressive course of hypoxemia and increased extravascular lung water (EVLW), delayed the onset of cardiovascular deterioration, and improved significantly survival time. It was concluded that CID therapy given at 90 min after the onset of lethal continuous P. aeruginosa infusion improved significantly animal survival time by improving temporarily hypoxemia and increase in EVLW and delaying cardiovascular collapse. PMID:2302957

  5. 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…

  6. 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…

  7. 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…

  8. 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…

  9. 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…

  10. How to keep cool in tough times.

    PubMed

    Muller-Smith, P

    1999-02-01

    Reengineering is no longer an event that has a beginning and an end. It is an ongoing process of change that continues to occur in all types of businesses. Because there is no longer the sense of security that doing a job well will guarantee continued employment, workers have to approach career planning from a different perspective. Moving up the career ladder in a single organization can no longer serve as the benchmark of success. The contemporary approach to success will be more geared toward the ability to constantly reinvent your unique set of job skills that are transferable from one job setting to another, thus ensuring employability. PMID:10358514

  11. 1970s: Camping in Tough Times.

    ERIC Educational Resources Information Center

    Camping Magazine, 1999

    1999-01-01

    In the 1970s, camps were challenged by economic recession, growing administrative demands, and changing attitudes and interests of campers and staff. An illustrative article from 1972, "Facing the Camping Future with Confidence" (Michael F. Buynak), discusses hidden costs in camp operation and the need for camp administration to shift from…

  12. 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…

  13. Managing board relationships in tough times.

    PubMed

    Commins, Kimberly; Render, John

    2003-01-01

    Scandals have dominated newspaper headlines, bringing corporate directors under increasing scrutiny. These issues continue to elicit public outrage about wrongdoing and ultimately resulted in standards for for-profit corporate board members through the enactment of the Sarbanes Oxley Act in 2002. Although all board members must address corporate responsibility issues, directors of health care organizations also have responsibilities unique to the health care industry that must be met in relation to corporate compliance requirements. PMID:12886663

  14. 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…

  15. 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

  16. A Tough Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA's Mars Exploration Rover Spirit took the four images that make up this mosaic with its microscopic imager on sol 82. The mosaic reveals the drilled surface of the target called 'New York' on the rock dubbed 'Mazatzal.' The rock abrasion tool ground for 3 hours and 45 minutes to create this 3.8 millimeter-deep (0.15 inch) hole. The exposed area is 4.5 centimeters (1.8 inches) in diameter.

    Mazatzal was an interesting rock to grind because it has a lighter tone than the previously ground rocks 'Adirondack' and 'Humphrey,' and because it looks different from its surrounding environment. Scientists hypothesized that Mazatzal's surface might be covered with a rind of weathered material. They drilled through this very top layer to reveal the underlying rock.

    Because Mazatzal's surface was not even, the left half of the rock was penetrated more deeply than the right. As can be seen in this image, the right, darker portion of the rock is still covered by the rind material. Spirit completed a second grind at this location at a different angle to remove the remaining veneer from the right side and create an even deeper hole. Images of this second grind will be sent back to Earth in the next sol or two.

    After the Final Grind The image was acquired on sol 85 after the rover drilled into New York a second time with its rock abrasion tool. Remnants of the dark grey coating that covers Mazatzal's interior can be seen at the right side of the hole. The crack in the rock may have once contained fluids out of which minerals precipitated. Each image making up this mosaic is 3 centimeters (1.2 inches) across.

  17. Fracture Behavior of Silica- and Rubber-Nanoparticle-Toughed Epoxies

    NASA Astrophysics Data System (ADS)

    Labak, Amelia K.

    Particle-toughened crosslinked epoxies are popular materials for a variety of applications, including the microelectronics industry. For this application, the properties of these materials, such as a high fracture toughness and a low coefficient of thermal expansion, are highly appealing. In order to achieve these properties, inorganic particles are often added into the matrix. For this study, both inorganic and organic particles-toughened epoxies are investigated in the hopes of finding an optimized system. In particular, in this study, micron-sized silica and nano-sized rubbery block copolymers are added to an amine-cured epoxy matrix. A series of rubber-only and silica-only systems are investigated for their contribution to the fracture toughness. Then, a series of hybrid systems are investigated. The hypothesis is that the rubber will contribute toughness through rubber particle cavitation and matrix void growth and the silica will contribute toughness through crack pinning and bridging and particle debonding. In the hybrid systems, these mechanisms will take place at a different scale. Therefore, the nanoscale mechanisms of the rubber will be able to function at the same time as the micron sized mechanisms of the silica and the resultant toughness will be synergistically higher. The results from this study show an interesting contribution from the rubber particles both in the rubber-only systems and the hybrid system. Ultimately, there was a marked increase in the fracture toughness of the hybrid systems, although not synergistic. This increase indicates that it would be possible to create an optimized hybrid system from the combined addition of these particles.

  18. 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.

  19. Desiccation survival time for eggs of a widespread and invasive Australian mosquito species, Aedes (Finlaya) notoscriptus (Skuse).

    PubMed

    Faull, K J; Webb, C; Williams, C R

    2016-06-01

    The Australian native mosquito Aedes (Finlaya) notoscriptus (Skuse) is closely associated with natural and artificial water holding receptacles. Eggs are laid in habitats where they are exposed to drying conditions as water levels fluctuate. Withstanding desiccation enables survival in challenging environments and increases the potential for establishment in non-native habitats. Until now, the desiccation resistance of Ae. notoscriptus eggs has been unknown despite the historical invasive success of this important dog heartworm and arbovirus vector. Viability and mean survival times of eggs from two Ae. notoscriptus populations (metropolitan areas of Sydney, NSW and Adelaide, SA) were evaluated, with eggs stored under three dryness conditions for up to 367 days. Our results revealed that Ae. notoscriptus eggs can withstand desiccation for extended periods, under a variety of conditions, with approximately 9-13% egg viability recorded after one year. This prolonged egg survival reflects the widespread distribution of this mosquito in Australia and its history of incursions and subsequent establishment in non-native habitats. Differences in mean egg volume were recorded in addition to significantly different egg length to width ratios for the two populations, which may reflect adaptation to biotope of origin and an associated likelihood of drought and drying conditions. The results of this study suggest that the desiccation resistant eggs of Ae. notoscriptus make this species highly adaptable, increasing the risk of movement to non-endemic regions of the world. PMID:27232125

  20. Dry stress and survival time of Enterobacter sakazakii and other Enterobacteriaceae in dehydrated powdered infant formula.

    PubMed

    Barron, Juncal Caubilla; Forsythe, Stephen J

    2007-09-01

    Powdered infant formula is not a sterile product, and opportunistic pathogens could multiply in the reconstituted product, resulting in neonatal infections. In this study, the generation of sublethally injured Enterobacteriaceae during desiccation and their persistence in dehydrated powdered infant formula was assessed during a 2.5-year period. The study included 27 strains of Enterobacter sakazakii, Enterobacter cloacae, Salmonella Enteritidis, Citrobacter koseri, Citrobacter freundii, Escherichia coli, Escherichia vulneris, Pantoea spp., Klebsiella oxytoca, and Klebsiella pneumoniae. The number of sublethally injured cells generated during desiccation was lower for K. oxytoca, Pantoea spp., Salmonella Enteritidis, and capsulated strains of E. sakazakii than for the other Enterobacteriaceae. The Enterobacteriaceae could be divided into three groups with respect to their long-term survival in the desiccated state. C. freundii, C. koseri, and E. cloacae were no longer recoverable after 6 months, and Salmonella Enteritidis, K. pneumoniae, and E. coli could not be recovered after 15 months. Pantoea spp., K. oxytoca, and E. vulneris persisted over 2 years, and some capsulated strains of E. sakazakii were still recoverable after 2.5 years. PMID:17900090

  1. 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.

  2. 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. PMID:26481486

  3. Effect of Prolonged Radiotherapy Treatment Time on Survival Outcomes after Intensity-Modulated Radiation Therapy in Nasopharyngeal Carcinoma

    PubMed Central

    Luo, Dong-Hua; Shen, Ting; Mai, Dong-Mei; Hu, Wei-Han; Mo, Hao-Yuan

    2015-01-01

    Purpose To estimate the influence of prolonged radiation treatment time (RTT) on survival outcomes in nasopharyngeal carcinoma after continuous intensity-modulated radiation therapy. Methods and Materials Retrospectively review 321 patients with NPC treated between October 2009 and December 2010 and all of them underwent simultaneous accelerated intensity-modulated radiation therapy. The fractionated dose was 2–2.47 Gy/F (median 2.27 Gy), and the total dose for nasopharyngeal region was 64–74 Gy/ 28–33 fractions. The association of prolonged RTT and treatment interruption with PFS, LRFS and DFFS were assessed by univariate analysis and multivariate analysis. Survival analyses were carried out using Kaplan–Meier methodology and the log-rank test was used to assess the difference. The Cox regression proportional hazard model was used for multivariate analyses and evaluating the prognostic parameters for PFS, LRFS and DFFS. Results Univariate analysis revealed no significant associations between prolonged RTT and PFS, LRFS, DFFS when dichotomized using various cut-off values (all P>0.05). In multivariate analysis, RTT (range, 36–63 days) as a continuous variable, had no influence on any survival outcome as well (P>0.05). T and N classification were independent prognostic factors for PFS, LRFS and DFFS (all P<0.05, except T classification for LRFS, P = 0.057). Age was an independent prognostic factor for PFS (hazard ratio [HR], 1.033; P = 0.008) and DFFS (HR, 1.032; P = 0.043). Conclusion We conclude that no such association between survival outcomes and radiation treatment duration (range: 36–63 days) can be found in the present retrospective study, however, we have to remind that prolongation in treatment should be limited in clinical application and interruptions caused by any reason should be minimized as much as possible. PMID:26506559

  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. 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.

  6. 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…

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

    PubMed

    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

  8. 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

  9. On the development of MP-TOUGH2

    SciTech Connect

    Oldenburg, C.M.; Hinkins, R.L.; Moridis, G.J.; Pruess, K.

    1995-02-01

    The authors are developing MP-TOUGH2 for exploiting massively parallel computers. The goals of this effort are to (1) create a data-parallel subsurface transport code for solving larger problems than currently practical on workstations, (2) write portable code that can take advantage of scalability to run on machines with more processors, and (3) minimize the necessity for additional validation and verification of the resulting code. The initial strategy they have followed is to focus on optimizing the generic and time-consuming task of linear equation solution while leaving the bulk of TOUGH2 unmodified. In so doing, they have implemented a massively parallel direct solver (MPDS) that takes advantage of the banded structure of TOUGH2 Jacobian matrices. The authors have compared timings of the iterative conjugate gradient solvers DSLUBC, DSLUCS, and DSLUGM written in Fortran77 for the front end with the MPDS which uses the data parallel unit. The MPDS shows good performance relative to the iterative conjugate gradient solvers on the free-convection test problem. The robust direct solution provided by MPDS can be used to (1) check on the veracity of a given iterative conjugate gradient solution, or (2) be used on certain problems where iterative solvers fail to converge. The test problem used in this study is the Elder pure thermal convection problem. For generality, the authors use the TOUGH2 equation of state module EOS3 for water, air, and heat, although this particular problem is a single-phase flow problem.

  10. Diabetes Mellitus as a Risk Factor in Glaucoma’s Physiopathology and Surgical Survival Time: A Literature Review

    PubMed Central

    Cunha, João Paulo; Amado, Duarte; Pinto, Luís Abegão; Ferreira, Joana

    2015-01-01

    ABSTRACT Glaucoma is a multifactorial condition under serious influence of many risk factors. The role of diabetes mellitus (DM) in glaucoma etiology or progression remains inconclusive. Although, the diabetic patients have different healing mechanism comparing to the general population and it has a possible-negative role on surgical outcomes. This review article attempts to analyze the association of both diseases, glaucoma and DM, before and after the surgery. The epidemiological studies, based mainly in population prevalence analyzes, have shown opposite outcomes in time and even in the most recent articles also the association remains inconclusive. On the contrary, the experimental models based on animal induced chronic hyperglycemia have shown an important association of both diseases, explained by common neurodegenerative mechanisms. Diabetic patients have a different wound healing process in the eye viz-a-viz other organs. The healing process is more and it results in lower surgical survival time, higher intraocular pressure (IOP) levels and, therefore, these patients usually need more medication to lower the IOP. Both randomized and nonrandomized retrospective and experimental molecular studies have shown the association between DM and glaucoma. Further studies are needed to get better explanations about outcomes on more recent surgical procedures and with the exponential use of antifibrotics. How to cite this article: Costa L, Cunha JP, Amado D, Pinto LA, Ferreira J. Diabetes Mellitus as a Risk Factor in Glaucoma’s Physiopathology and Surgical Survival Time: A Literature Review. J Curr Glaucoma Pract 2015;9(3):81-85. PMID:26997842

  11. A Biomimetic Modular Polymer with Tough and Adaptive Properties

    PubMed Central

    Kushner, Aaron M.; Vossler, John; Williams, Gregory A.; Guan, Zhibin

    2009-01-01

    Natural materials employ many elegant strategies to achieve mechanical properties required for survival under varying environmental conditions. Thus these remarkable biopolymers and nanocomposites often not only have a combination of mechanical properties such as high modulus, toughness, and elasticity, but also exhibit adaptive and stimuli-responsive properties. Inspired by skeletal muscle protein titin, we have synthesized a biomimetic modular polymer that not only closely mimics the modular multi-domain structure of titin, but also manifests an exciting combination of mechanical properties, as well as adaptive properties such as self-healing and temperature-responsive shape-memory properties. PMID:19505144

  12. Formation of tough composite joints

    SciTech Connect

    Brun, M.K.

    1998-12-01

    Joints that exhibited tough fracture behavior were formed in a Si/SiC matrix reinforced with Textron SCS-6 fibers with either boron nitride or silicon nitride fiber coatings. Lapped joints (joints with overlapping fingers) were necessary to obtain tough behavior. Geometrical requirements necessary to avoid brittle joint failure were proposed. Joints with a simple overlap geometry (only a few fingers) had to be very long in order to prevent brittle failure. 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, by changing the fiber coating, significantly increased matrix cracking and ultimate strength of the joints. 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 should permit building of structures containing joints with only a minor reduction of design stresses.

  13. Tough composite materials: Recent developments

    NASA Technical Reports Server (NTRS)

    Vosteen, L. F. (Editor); Johnston, N. J. (Editor); Teichman, L. A. (Editor); Blankenship, C. P. (Editor)

    1985-01-01

    The present volume broadly considers topics in composite fracture toughness and impact behavior characterization, composite system constituent properties and their interrelationships, and matrix systems' synthesis and characterization. Attention is given to the characterization of interlaminar crack growth in composites by means of the double cantilever beam specimen, the characterization of delamination resistance in toughened resin composites, the effect of impact damage and open holes on the compressive strength of tough resin/high strain fiber laminates, the effect of matrix and fiber properties on compression failure mechanisms and impact resistance, the relation of toughened neat resin properties to advanced composite mechanical properties, and constituent and composite properties' relationships in thermosetting matrices. Also treated are the effect of cross-link density on the toughening mechanism of elastomer-modified epoxies, the chemistry of fiber/resin interfaces, novel carbon fibers and their properties, the development of a heterogeneous laminating resin, solvent-resistant thermoplastics, NASA Lewis research in advanced composites, and opportunities for the application of composites in commercial aircraft transport structures.

  14. 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

  15. 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.

  16. 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). PMID:16013393

  17. Human umbilical-cord-blood mononucleated cells enhance the survival of lethally irradiated mice: dosage and the window of time

    PubMed Central

    Kovalenko, Olga A.; Azzam, Edouard I.; Ende, Norman

    2013-01-01

    The purpose of this study was to evaluate the window of time and dose of human umbilical-cord-blood (HUCB) mononucleated cells necessary for successful treatment of radiation injury in mice. Female A/J mice (27–30 weeks old) were exposed to an absorbed dose of 9–10 Gy of 137Cs γ-rays delivered acutely to the whole body. They were treated either with 1 × 108 or 2 × 108 HUCB mononucleated cells at 24–52 h after the irradiation. The antibiotic Levaquin was applied 4 h postirradiation. The increased dose of cord-blood cells resulted in enhanced survival. The enhancement of survival in animals that received 2 × 108 HUCB mononucleated cells relative to irradiated but untreated animals was highly significant (P < 0.01). Compared with earlier studies, the increased dose of HUCB mononucleated cells, coupled with early use of an antibiotic, extended the window of time for effective treatment of severe radiation injury from 4 to 24–52 h after exposure. PMID:23792493

  18. [Effect of waiting time for radiotherapy on five-year overall survival in women with cervical cancer, 1995-2010].

    PubMed

    Nascimento, Maria Isabel do; Silva, Gulnar Azevedo E

    2015-11-01

    Overall 5-year survival and factors associated with death were evaluated in a cohort of 342 women with cervical cancer referred to radiotherapy in the Baixada Fluminense, in Greater Metropolitan Rio de Janeiro State, Brazil. Overall 5-year survival was 25.3%, reaching 60.8% in women with stage IIA or less. The model adjusted by extended Cox proportional regression showed an increase in mortality risk for patients with stages IIB-IIIB (HR = 1.89; 95%CI: 1.214; 2.957) and IVA-IVB (HR = 5.78; 95%CI: 2.973; 11.265). Cytology in asymptomatic women (HR = 0.58; 95%CI: 0.362; 0.961) and referral for first consultation in an oncology service in the Baixada Fluminense (HR = 0.60; 95%CI: 0.418; 0.875) were the main protective factors identified by the study. Waiting time (> 60 versus ≤ 60 days) was not statistically significant, but a delay of 4 days worsened the outcome. The 60-day limit for initiating radiotherapy should be respected, because delay greater than 64 days showed a significant association between all waiting time cut-off points and 5-year mortality risk. PMID:26840822

  19. Time to Insurance Approval in Private and Public Payers Does Not Influence Survival in Patients Who Undergo Hematopoietic Cell Transplantation.

    PubMed

    Bhatt, Vijaya Raj; Loberiza, Fausto R; Schmit-Pokorny, Kim; Lee, Stephanie J

    2016-06-01

    In the United States, insurance status has been implicated as a barrier to obtaining timely treatment. In this retrospective cohort study of 521 patients who underwent first hematopoietic cell transplantation (HCT), we investigated the association between timeliness of HCT and overall survival. Timeliness was operationally defined in the following 3 ways: (1) payer approval, from request for approval to actual payer approval; (2) transplantation speed, from payer approval to time of actual HCT; and (3) total time, from request for approval to HCT. Patients with private insurance had longer time to payer approval (P < .0001) than those with public payers but shorter time from approval to actual HCT (P < .0001) and total time to HCT (P < .0001). Multivariate Cox regression showed no significant differences in risk of death between slow and fast times in the 3 indices of timeliness in the models that used all patients (n = 509), autologous HCT in lymphoma (n = 278), and autologous HCT in multiple myeloma (n = 121). Additional studies to evaluate the effect of insurance timeliness on all patients for whom HCT is recommended, not just those who undergo HCT, should be conducted. PMID:26988742

  20. "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…

  1. 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.

  2. 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.

  3. Fracture toughness of steel-fiber-reinforced bone cement.

    PubMed

    Kotha, S P; Li, C; Schmid, S R; Mason, J J

    2004-09-01

    Fractures in the bone-cement mantle (polymethyl methacrylate) have been linked to the failure of cemented total joint prostheses. The heat generated by the curing bone cement has also been implicated in the necrosis of surrounding bone tissue, leading to loosening of the implants. The addition of reinforcements may improve the fracture properties of bone cement and decrease the peak temperatures during curing. This study investigates the changes in the fracture properties and the temperatures generated in the ASTM F451 tests by the addition of 316L stainless steel fibers to bone cement. The influence of filler volume fraction (5-15% by volume) and aspect ratios (19, 46, 57) on the fracture toughness of the acrylic bone cement was assessed. Increasing the volume fraction of the steel fibers resulted in significant increases in the fracture toughness of the steel-fiber-reinforced composite. Fracture-toughness increases of up to 2.63 times the control values were obtained with the use of steel-fiber reinforcements. No clear trend in the fracture toughness was discerned for increasing aspect ratios of the reinforcements. There is a decrease in the peak temperatures reached during the curing of the steel-fiber-reinforced bone cement, though the decrease is too small to be clinically relevant. Large increases in the fatigue life of acrylic bone cement were also obtained by the addition of steel fibers. These results indicate that the use of steel fibers may enhance the durability of cemented joint prostheses. PMID:15293326

  4. 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.

  5. 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. PMID:18037654

  6. Time trends of smoking cessation analyzed with six mathematical survival models.

    PubMed

    Elketroussi, M; Fan, D P

    1991-01-01

    In this paper, six mathematical models were applied to model time trends of smoking cessation. Both statistical and non-statistical methods were used and included the exponential, ideodynamic, log-logistic, Pareto, sickle and Weibull models. All models included the possibilities of both permanent abstinence and relapse to smoking. Time trends from all models were compared with data from the Multiple Risk Factor Intervention Trial (MRFIT) program. The Pareto, log-logistic, Weibull and ideodynamic models yielded satisfactory fits to the data while the sickle and exponential models did not. Even though the data used in this paper were not sufficient to distinguish among these four models, the methodology will be useful for further narrowing the model choices as additional data for the testing become available. PMID:2050432

  7. Smoking onset and the time-varying effects of self-efficacy, environmental smoking, and smoking-specific parenting by using discrete-time survival analysis.

    PubMed

    Hiemstra, Marieke; Otten, Roy; Engels, Rutger C M E

    2012-04-01

    This study examined the timing of smoking onset during mid- or late adolescence and the time-varying effects of refusal self-efficacy, parental and sibling smoking behavior, smoking behavior of friends and best friend, and parental smoking-specific communication. We used data from five annual waves of the 'Family and Health' project. In total, 428 adolescents and their parents participated at baseline. Only never smokers were included at baseline (n = 272). A life table and Kaplan-Meier survival curve showed that 51% of all adolescents who did not smoke at baseline did not start smoking within 4 years. The risk for smoking onset during mid- or late adolescence is rather stable (hazard ratio between 16 and 19). Discrete-time survival analyses revealed that low refusal self-efficacy, high frequency of communication, and sibling smoking were associated with smoking onset one year later. No interaction effects were found. Conclusively, the findings revealed that refusal self-efficacy is an important predictor of smoking onset during mid- or late adolescence and is independent of smoking-specific communication and smoking behavior of parents, siblings, and (best) friend(s). Findings emphasize the importance of family prevention programs focusing on self-efficacy skills. PMID:21643802

  8. 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.

  9. Consistency and Timing of Marital Transitions and Survival During Midlife: the Role of Personality and Health Risk Behaviors

    PubMed Central

    Brummett, Beverly H.; Martin, Peter; Helms, Michael J.

    2013-01-01

    Background Marital status is associated with survival. Purpose The aims of this study are to evaluate marital history and timing on mortality during midlife, test the role of pre-marital personality, and quantify the role of health risk behaviors. Methods Cox proportional hazard models were run with varying classifications of marital history and sets of covariates. Results In fully adjusted models compared to the currently married, lifetime marital history predicts premature mortality with never married at 2.33 times risk of death and ever married at 1.64 risk of death. Midlife marital history shows that not having a partner during midlife (hazard ratio (HR)= 3.10 formerly married; HR=2.59 remaining single) has the highest risk of death. Controlling for personality and health risk behaviors reduces but does not eliminate the impact of marital status. Conclusion Consistency of marital status during midlife suggests that lack of a partner is associated with midlife mortality. PMID:23299546

  10. Cytomegalovirus infection does not impact on survival or time to first treatment in patients with chronic lymphocytic leukemia.

    PubMed

    Parry, Helen Marie; Damery, Sarah; Hudson, Christopher; Maurer, Matthew J; Cerhan, James R; Pachnio, Annette; Begum, Jusnara; Slager, Susan L; Fegan, Christopher; Man, Stephen; Pepper, Christopher; Shanafelt, Tait D; Pratt, Guy; Moss, Paul A H

    2016-08-01

    Human cytomegalovirus (HCMV) is a widely prevalent herpes virus which establishes a state of chronic infection. The establishment of CMV-specific immunity controls viral reactivation and leads to the accumulation of very large numbers of virus-specific T cells which come to dominate the immune repertoire. There is concern that this may reduce the immune response to heterologous infections and HCMV infection has been associated with reduced survival in elderly people. Patients with chronic lymphocytic leukemia (B-CLL) suffer from a state of immune suppression but have a paradoxical increase in the magnitude of the CMV-specific T cell and humoral immune response. As such, there is now considerable interest in how CMV infection impacts on the clinical outcome of patients with B-CLL. Utilizing a large prospective cohort of patients with B-CLL (n = 347) we evaluated the relationship between HCMV seropositivity and patient outcome. HCMV seropositive patients had significantly worse overall survival than HCMV negative patients in univariate analysis (HR = 2.28, 95% CI: 1.34-3.88; P = 0.002). However, CMV seropositive patients were 4 years older than seronegative donors and this survival difference was lost in multivariate modeling adjusted for age and other validated prognostic markers (P = 0.34). No significant difference was found in multivariate modeling between HCMV positive and negative patients in relation to the time to first treatment (HR = 1.12, 95% CI: 0.68-1.84; P = 0.65). These findings in a second independent cohort of 236 B-CLL patients were validated. In conclusion no evidence that HCMV impacts on the clinical outcome of patients with B-CLL was found. Am. J. Hematol. 91:776-781, 2016. © 2016 Wiley Periodicals, Inc. PMID:27124884

  11. Effect of Li level, artificial aging, and TiB2 reinforcement on the fracture toughness of Weldalite (tm) 049-type alloys

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Plane strain fracture toughness (K sub IC) was evaluated for Weldalite (tm) 049 with and without TiB2 reinforcement. For the nonreinforced variant, changes in toughness were measured for various aging conditions and lithium levels. Toughness testing was carried out on fatigue precracked compact tension (CT) specimens at 24 C, as per ASTM standard E-399. Toughness was measured as a function of aging time at 160 C for the two Weldalite 049(1.3) heats. The composition of these heats differed only in that 0.03 wt pct. Ti was added to one as an additional grain refiner. Both heats showed a decrease in toughness with increasing aging time, although toughness values for one were significantly higher than for the other. This greater toughness may be due to a subtle change in the grain size resulting for the presence of Ti or, alternatively, to differences in texture or substructure formed during extrusion.

  12. 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.

  13. Improved toughness of silicon carbide

    NASA Technical Reports Server (NTRS)

    Palm, J. A.

    1976-01-01

    Impact energy absorbing layers (EALs) comprised of partially densified silicon carbide were formed in situ on fully sinterable silicon carbide substrates. After final sintering, duplex silicon carbide structures resulted which were comprised of a fully sintered, high density silicon carbide substrate or core, overlayed with an EAL of partially sintered silicon carbide integrally bonded to its core member. Thermal cycling tests proved such structures to be moderately resistant to oxidation and highly resistant to thermal shock stresses. The strength of the developed structures in some cases exceeded but essentially it remained the same as the fully sintered silicon carbide without the EAL. Ballistic impact tests indicated that substantial improvements in the toughness of sintered silicon carbide were achieved by the use of the partially densified silicon carbide EALs.

  14. Tough Decisions for Premature Triplets.

    PubMed

    Hurst, Ashley; Vergales, Brooke D; Paget-Brown, Alix; Mercurio, Mark; Lantos, John D

    2016-02-01

    When infants are born at the borderline of viability, doctors and parents have to make tough decisions about whether to institute intensive care or provide only palliative care. Often, these decisions are made in moments of profound emotional turmoil, and parents receive different information from different health professionals. Communication can become garbled. It may be difficult to tell when and whether the patient's clinical condition has changed enough so that certain choices that had once been permissible become impermissible. In this "Ethics Rounds," we present a case of triplets born at the borderline of viability. We sought comments from the triplets' parents, the doctors and ethicist who were caring for the infants, and a bioethicist/neonatologist from another hospital. PMID:26738882

  15. Prediction of time dependent survival in HF patients after VAD implantation using pre- and post-operative data.

    PubMed

    Kourou, Konstantina; Rigas, George; Exarchos, Konstantinos P; Goletsis, Yorgos; Exarchos, Themis P; Jacobs, Steven; Meyns, Bart; Trivella, Maria-Giovanna; Fotiadis, Dimitrios I

    2016-03-01

    Heart failure is one of the most common diseases worldwide. In recent years, Ventricular Assist Devices (VADs) have become a valuable option for patients with advanced HF. Although it has been shown that VADs improve patient survival rates, several complications persist during left VAD (LVAD) support. The stratification scores currently employed are mostly generic, i.e. not specifically built for LVAD patients, and are based on pre-implantation patient data. In this work we apply data mining approaches for the prediction of time dependent survival in patients after LVAD implantation. Moreover, the predictions acquired with the use of pre-implantation data are enriched by employing post-implantation data, i.e. follow-up data. Different clinical scenarios have been depicted and the subsequent conditions are tested in order to identify the optimal set of pre- and post-implant features, as well as the most suitable algorithms for feature selection and prediction. The proposed approach is applied to a real dataset of 71 patients, reporting an accuracy of 84.5%, sensitivity of 87% and specificity of 82%. Based on the reported results, expert cardio-surgeons can be supported in planning the treatment of VAD patients. PMID:26820445

  16. 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.

  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. 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.

  19. Estimation of fracture toughness of cast stainless steels during thermal aging in LWR systems

    SciTech Connect

    Chopra, O.K. )

    1991-06-01

    A procedure and correlations are presented for predicting the change in fracture toughness of cast stainless steel components due to thermal aging during service in light water rectors (LWRs) at 280--330{degrees}C (535--625{degrees}F). The fracture toughness J-R curve and Charpy-impact energy of aged cast stainless steels are estimated from known mineral in formation. Fracture toughness of a specific cast stainless steel is estimated from the extent and kinetics of thermal embrittlement. The extent of thermal embrittlement is characterized by the room-temperature normalized'' Charpy-impact energy. A correlation for the extent of embrittlement at saturation,'' i.e., the minimum impact energy that would be achieved for the material after long-term aging, is given in terms of a material parameter, {Phi}, which is determined from the chemical composition. The fracture toughness J-R curve for the material is then obtained from correlations between room-temperature Charpy-impact energy and fracture toughness parameters. Fracture toughness as a function of time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which is determined from chemical composition. A common lower-bound'' J-R curve for cast stainless steels with unknown chemical composition is also defined for a given material specification, ferrite content, and temperature. Examples for estimating impact strength and fracture toughness of cast stainless steel components during reactor service are describes. 24 refs., 39 figs., 2 tabs.

  20. OP30DIAGNOSTIC DELAY AND SURVIVAL IN HIGH GRADE GLIOMAS - EVIDENCE OF THE “WAITING TIME PARADOX”

    PubMed Central

    Aggarwal, Ajay; Herz, Naomi; Arkush, Leo; Short, Susan; Rees, Jeremy

    2014-01-01

    INTRODUCTION: We present a retrospective single centre study to determine whether delays in diagnosis in high grade glioma (HGG) impact on overall survival (OS). METHOD: Consecutive patients diagnosed with HGG at The National Hospital for Neurology and Neurosurgery, a single neuroscience centre in 2011 were reviewed. Route of referral and time from initial presentation to diagnosis were analysed and correlated with OS. RESULTS: 118 patients were studied, 92 had with glioblastoma (GBM). Diagnosis of GBM in patients presenting to emergency services was quicker than through outpatients (8 days vs 26 days, p < 0.0001), but these patients had significantly worse OS (181 days vs 386 days p = 0.0075 ). CONCLUSION: Earlier diagnosis is paradoxically associated with a worse OS in GBM. An “aggressive” phenotype with rapid symptomatic deterioration and hence emergency presentation is a poor prognostic factor not influenced by more rapid treatment or earlier diagnosis.

  1. Survival Impact of Increasing Time to Treatment Initiation for Patients With Head and Neck Cancer in the United States

    PubMed Central

    Murphy, Colin T.; Handorf, Elizabeth A.; Egleston, Brian L.; Wang, Lora S.; Mehra, Ranee; Flieder, Douglas B.; Ridge, John A.

    2016-01-01

    Purpose To estimate the overall survival (OS) impact from increasing time to treatment initiation (TTI) for patients with head and neck squamous cell carcinoma (HNSCC). Methods Using the National Cancer Data Base (NCDB), we examined patients who received curative therapy for the following sites: oral tongue, oropharynx, larynx, and hypopharynx. TTI was the number of days from diagnosis to initiation of curative treatment. The effect of TTI on OS was determined by using Cox regression models (MVA). Recursive partitioning analysis (RPA) identified TTI thresholds via conditional inference trees to estimate the greatest differences in OS on the basis of randomly selected training and validation sets, and repeated this 1,000 times to ensure robustness of TTI thresholds. Results A total of 51,655 patients were included. On MVA, TTI of 61 to 90 days versus less than 30 days (hazard ratio [HR], 1.13; 95% CI, 1.08 to 1.19) independently increased mortality risk. TTI of 67 days appeared as the optimal threshold on the training RPA, statistical significance was confirmed in the validation set (P < .001), and the 67-day TTI was the optimal threshold in 54% of repeated simulations. Overall, 96% of simulations validated two optimal TTI thresholds, with ranges of 46 to 52 days and 62 to 67 days. The median OS for TTI of 46 to 52 days or fewer versus 53 to 67 days versus greater than 67 days was 71.9 months (95% CI, 70.3 to 73.5 months) versus 61 months (95% CI, 57 to 66.1 months) versus 46.6 months (95% CI, 42.8 to 50.7 months), respectively (P < .001). In the most recent year with available data (2011), 25% of patients had TTI of greater than 46 days. Conclusion TTI independently affects survival. One in four patients experienced treatment delay. TTI of greater than 46 to 52 days introduced an increased risk of death that was most consistently detrimental beyond 60 days. Prolonged TTI is currently affecting survival. PMID:26628469

  2. Survival analysis of time to uptake of modern contraceptives among sexually active women of reproductive age in Nigeria

    PubMed Central

    Adebowale, Ayo Stephen; Morhason-Bello, ImranOludare

    2015-01-01

    Objective To assess the timing of modern contraceptive uptake among married and never-married women in Nigeria. Design A retrospective cross-sectional study. Data and method We used nationally representative 2013 Demographic and Health Survey data in Nigeria. Modern contraceptive uptake time was measured as the period between first sexual intercourse and first use of a modern contraceptive. Non-users of modern contraceptives were censored on the date of the survey. Kaplan–Meier survival curves were used to determine the rate of uptake. A Cox proportional-hazards model was used to determine variables influencing the uptake at 5% significance level. Participants A total of 33 223 sexually active women of reproductive age. Outcome measure Time of uptake of a modern contraceptive after first sexual intercourse. Results The median modern contraceptive uptake time was 4 years in never-married and 14 years among ever-married women. Significant differences in modern contraceptive uptake existed in respondents’ age, location, education and wealth status. Never-married women were about three times more likely to use a modern contraceptive than ever-married women (aHR=3.24 (95% CI 2.82 to 3.65)). Women with higher education were six times more likely to use a modern contraceptive than those without education (aHR=6.18 (95% CI 5.15 to 7.42)). Conclusions The rate of modern contraceptive uptake is low, and timing of contraceptive uptake during or after first sexual intercourse differed according to marital status. Age and number of children ever born influenced modern contraceptive uptake among the never-married women, but religion and place of residence were associated with the probability of modern contraceptive uptake among ever-married women. PMID:26671948

  3. Managing tough and easy organizational cultures.

    PubMed

    Bruhn, J G

    2001-12-01

    Some organizations have cultures which are tough on members while others are easy. A tough culture would be expected to be out of touch with the values of its members and suppress value conflicts. An easy culture would be expected to be sensitive to the values of its members and deal with value conflict openly. The importance of value dynamics and transactions is discussed as the basic condition for toughness and easiness. The management of members who feel victimized by organizational values and perceptions is also discussed. Strategies for sustaining value relationships and value fulfillment in organizations undergoing change are presented. PMID:11809032

  4. Large fracture toughness boron-epoxy composites

    NASA Technical Reports Server (NTRS)

    Atkins, A. G.

    1975-01-01

    The high tensile strengths of strong interfacial bonding may be combined with the large fracture toughness of weak interfacial bonding in brittle fiber/brittle matrix composites by intermittently coating the filaments before layup so as to have random alternate weak and strong regions. Appropriate coating materials enable Cook-Gordon Mode I interfacial debonding to take place, which produces very long pull-out lengths with an associated large contribution to toughness. Unidirectional boron-epoxy composites have been so made which have toughnesses greater than 200 kJ/sq m while retaining rule of mixtures tensile strengths. Similar trends have been observed for crossply layups.

  5. Fracture Toughness of Functionally Graded Steels

    NASA Astrophysics Data System (ADS)

    Nazari, Ali; Mohandesi, Jamshid Aghazadeh; Riahi, Shadi

    2012-04-01

    In this study, fracture toughness of functionally graded steels in both crack divider and crack arrester configurations has been studied. Spot-welded plain carbon steel and austenitic stainless steel with different thicknesses and arrangements were used as electrodes of electroslag remelting to produce functionally graded steels. Fracture toughness of the specimens in crack divider configuration was found to depend on the arrangements of the primary electrodes' pieces together with the type of the containing phases. In crack arrester configuration, the fracture toughness was found to depend on the crack tip position and the distance of the crack tip with respect to the bainitic or martensitic intermediate layers.

  6. 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. PMID:10247957

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

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

    PubMed Central

    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.

    2016-01-01

    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. PMID:26887055

  13. 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. PMID:26888018

  14. Toughness and strength of nanocrystalline graphene.

    PubMed

    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

  15. Toughness and strength of nanocrystalline graphene

    DOE PAGESBeta

    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

  16. 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

  17. 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.

  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

    NASA Astrophysics Data System (ADS)

    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.

  20. 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.

  1. Length of time on dialysis prior to renal transplantation is a critical factor affecting patient survival after allografting.

    PubMed

    West, J C; Bisordi, J E; Squiers, E C; Latsha, R; Miller, J; Kelley, S E

    1992-01-01

    Within the past year at our transplant center we have had the experience of performing renal allografts in two patients older than 65 years, each of whom had been on hemodialysis more than 10 years. Both resulted in patient mortality within 90 days of transplant (one due to myocardial infarction, the other due to visceral ischemia with infarction). This prompted us to review retrospectively our own data (n = 204) and the national (UNOS) data (n = 10,971) regarding transplant outcome, patient age, and length of time on dialysis prior to renal transplantation. This review revealed that patient mortality after transplant increased with the length of end-stage renal disease (dialysis, regardless of type) independent of age, the greatest mortality occurring within the first 6 months of transplant (and not thereafter); graft survival was similar for all age cohorts analyzed. Our review of the literature reveals a paucity of articles pertaining to post-transplant mortality and length of time on dialysis prior to transplant. Our results indicate the following possible conclusions. (1) The length of time of end-stage renal disease therapy prior to renal transplantation is a significant and independent risk factor for post-transplant mortality. (2) Higher priority should be given to this factor when formulating strategies for allocation of scarce resources. (3) Patients on dialysis for extended periods of time who are elderly may be at particularly high risk. (4) Patients being considered for renal transplant should be informed of their individual risk factors for mortality post-transplant based on length of ESRD therapy. (5) Renal transplantation should be considered as early as possible in patients with ESRD (or imminent ESRD). PMID:14621760

  2. Depression After First Hospital Admission for Acute Coronary Syndrome: A Study of Time of Onset and Impact on Survival.

    PubMed

    Osler, Merete; Mårtensson, Solvej; Wium-Andersen, Ida Kim; Prescott, Eva; Andersen, Per Kragh; Jørgensen, Terese Sara Høj; Carlsen, Kathrine; Wium-Andersen, Marie Kim; Jørgensen, Martin Balslev

    2016-02-01

    We examined incidence of depression after acute coronary syndrome (ACS) and whether the timing of depression onset influenced survival. All first-time hospitalizations for ACS (n = 97,793) identified in the Danish Patient Registry during 2001-2009 and a reference population were followed for depression and mortality via linkage to patient, prescription, and cause-of-death registries until the end of 2012. Incidence of depression (as defined by hospital discharge or antidepressant medication use) and the relationship between depression and mortality were examined using time-to-event models. In total, 19,520 (20.0%) ACS patients experienced depression within 2 years after the event. The adjusted rate ratio for depression in ACS patients compared with the reference population was 1.28 (95% confidence interval (CI): 1.25, 1.30). During 12 years of follow-up, 39,523 (40.4%) ACS patients and 27,931 (28.6%) of the reference population died. ACS patients with recurrent (hazard ratio (HR) = 1.62, 95% CI: 1.57, 1.67) or new-onset (HR = 1.66, 95% CI: 1.60, 1.72) depression had higher mortality rates than patients with no depression. In the reference population, the corresponding relative estimates for recurrent (HR =1.98, 95% CI: 1.92, 2.05) and new-onset (HR = 2.42, 95% CI: 2.31, 2.54) depression were stronger. Depression is common in ACS patients and is associated with increased mortality independently of time of onset, but here the excess mortality associated with depression seemed to be lower in ACS patients than in the reference population. PMID:26740025

  3. 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.

  4. 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

  5. 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...

  6. Strength-toughness requirements for thick-walled high pressure vessels

    NASA Astrophysics Data System (ADS)

    Kapp, Joseph A.

    1992-05-01

    The strength and toughness requirements of materials used in high pressure vessels has been the subject of some discussion in the meetings of the Materials Task Group of the Special Working Group - High Pressure Vessels. A fracture mechanics analysis has been performed to theoretically establish the required toughness for a high pressure vessel. The analysis is based on the validity requirement for plane-strain fracture of fracture toughness test specimens. This means that at fracture, the crack length, uncracked ligament, and vessel length must each be greater than fifty times the crack tip plastic zone since for brittle fracture to occur. For high pressure piping applications, the limiting physical dimension is the uncracked ligament, since it can be assumed that the other dimensions are always greater than fifty times the crack tip plastic zone. To perform the fracture mechanics analysis, several parameters must be known, including vessel dimensions, material strength, degree of autofrettage, and design pressure. Remarkably, the results of the analysis show that the effects of radius ratio, pressure, and degree of autofrettage can be ignored when establishing strength and toughness requirements for design code purposes. The only parameters that enter into the calculation are yield strength, toughness and vessel thickness. The final results can easily be represented as a graph of yield strength against toughness on which several curves, one for each vessel thickness, are plotted.

  7. 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…

  8. Who Is Most at Risk for School Removal? A Multilevel Discrete-Time Survival Analysis of Individual- and Context-Level Influences

    ERIC Educational Resources Information Center

    Petras, Hanno; Masyn, Katherine E.; Buckley, Jacquelyn A.; Ialongo, Nicholas S.; Kellam, Sheppard

    2011-01-01

    The focus of this study was to prospectively investigate the effect of aggressive behavior and of classroom behavioral context, as measured in the fall of 1st grade, on the timing of 1st school removal across Grades 1-7 in a sample of predominately urban minority youths from Baltimore, Maryland. Using a multilevel discrete-time survival framework,…

  9. 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

  10. Increased survival time of a patient with metastatic malignant melanoma following immunotherapy: A case report and literature review

    PubMed Central

    ZHANG, YONG; SONG, YONGPING; GAO, QUANLI

    2015-01-01

    Metastatic malignant melanoma is treated with chemotherapy and radiotherapy. A number of previous studies have indicated that cytokine-induced killer cells (CIK cells) are a heterogeneous cell population that express cluster of differentiation (CD)3 and CD56, in addition to the natural killer cell NKG2D activating receptor. CIK cells possess major histocompatibility complex-unrestricted cytotoxicity towards cancer, but not towards normal targets. The present study investigated whether the addition of CIK cells resulted in an improved therapeutic response in a patient with metastatic malignant melanoma. In the current case, a patient with metastatic malignant melanoma received CIK therapy, which resulted in a relatively long survival time of 28 months. To the best of our knowledge, there have been no previous studies reporting such positive effects in a patient who received CIK cell immunotherapy. Based on the findings of the present study, CIK cell therapy may be an option that results in a good prognosis in certain patients with metastatic malignant melanoma. PMID:26622588

  11. 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

  12. Precise survival time and physical activity after fatal left ventricle injury from sharp pointed weapon: a case report and a review of the literature.

    PubMed

    Franchi, Angélique; Kolopp, Martin; Coudane, Henry; Martrille, Laurent

    2016-09-01

    Survival time and physical activity following fatal injury are especially important during investigation of homicide cases and the estimation of a victim's survival time and physical activity following a fatal injury from a sharp weapon is a commonly raised issue, particularly at trial. According to the literature, survival time and physical activity after cardiac damage are short-term estimates without high accuracy. We report the homicide case of a young man who died as a result of a left ventricle injury caused by a sharp pointed weapon. This case is based on evidence from a video surveillance camera that recorded the whole scene after the fatal injury: The victim showed an adapted physical activity for 38 s, although the left ventricle incision measured 2 cm. Despite several cases in the literature, it is not possible to correlate precisely the size of the wounds and the acting capability. PMID:26914799

  13. 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

  14. TOUGH+ v1.5 Core Code

    Energy Science and Technology Software Center (ESTSC)

    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 FORTRANmore » 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.« less

  15. 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.

  16. 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

  17. 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

  18. Combining strength and toughness in ultrahigh strength steel

    NASA Astrophysics Data System (ADS)

    Wang, L. D.; Jiang, L. Z.; Zhu, M.; Liu, X.; Zhou, W. M.; Li, Y.

    2004-08-01

    The main objective of this investigation is to examine the effects of a new technique, double-ageing, on the microstructure and mechanical properties of the ultrahigh strength steel Aermet 100. Under the condition of double-ageing, there is no apparent decrease in the steel strength. However, the impact fatigue life can be prolonged by 35.5% and the dynamic fracture toughness raised by 22.6% by this technique compared with normal ageing. Based on the observation of the microscopic structure, the physical mechanism of prolongation of fatigue life and enhancement of the stability of the reverted austenite is analysed further. The results show that this new technique is a breakthrough in optimally combining the strength and toughness of Aermet 100 steel. In light of the current understanding of this subject, the toughness of the reverted austenite formed at the time of heat preservation at the higher temperature of the double-ageing process increases drastically. Moreover, during the treatment at the lower temperature of the double-ageing process, the carbon separating from the martensitic ferrite of Aermet 100 steel will diffuse into the reverted austenite, resulting in a decrease of the brittleness of the martensite and an increase of the stability of the reverted austenite.

  19. TRITIUM AND DECAY HELIUM EFFECTS ON THE FRACTURE TOUGHNESS PROPERTIES OF STAINLESS STEEL WELDMENTS

    SciTech Connect

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

    2007-08-31

    J-Integral fracture toughness tests were conducted on tritium-exposed-and-aged Types 304L and 21-6-9 stainless steel weldments in order to measure the combined effects of tritium and its decay product, helium-3 on the fracture toughness properties. Initially, weldments have fracture toughness values about three times higher than base-metal values. Delta-ferrite phase in the weld microstructure improved toughness provided no tritium was present in the microstructure. After a tritium-exposure-and-aging treatment that resulted in {approx}1400 atomic parts per million (appm) dissolved tritium, both weldments and base metals had their fracture toughness values reduced to about the same level. The tritium effect was greater in weldments (67 % reduction vs. 37% reduction) largely because the ductile discontinuous delta-ferrite interfaces were embrittled by tritium and decay helium. Fracture toughness values decreased for both base metals and weldments with increasing decay helium content in the range tested (50-200 appm).

  20. Effect of tritium and decay helium on the fracture toughness properties of stainless steel weldments

    SciTech Connect

    Morgan, M. J.; West, S.; Tosten, M. H.

    2008-07-15

    J-Integral fracture toughness tests were conducted on tritium-exposed-and- aged Types 304L and 21-6-9 stainless steel weldments in order to measure the combined effects of tritium and its decay product, helium-3 on the fracture toughness properties. Initially, weldments have fracture toughness values about three times higher than base-metal values. Delta-ferrite phase in the weld microstructure improved toughness provided no tritium was present in the microstructure. After a tritium-exposure-and-aging treatment that resulted in {approx}1400 atomic parts per million (appm) dissolved tritium, both weldments and base metals had their fracture toughness values reduced to about the same level. The tritium effect was greater in weldments (67 % reduction vs. 37% reduction) largely because the ductile discontinuous delta-ferrite phase was embrittled by tritium and decay helium. For both base metals and weldments, fracture toughness values decreased with increasing decay helium content in the range tested (50-800 appm). (authors)

  1. The conflicts between strength and toughness

    NASA Astrophysics Data System (ADS)

    Ritchie, Robert O.

    2011-11-01

    The attainment of both strength and toughness is a vital requirement for most structural materials; unfortunately these properties are generally mutually exclusive. Although the quest continues for stronger and harder materials, these have little to no use as bulk structural materials without appropriate fracture resistance. It is the lower-strength, and hence higher-toughness, materials that find use for most safety-critical applications where premature or, worse still, catastrophic fracture is unacceptable. For these reasons, the development of strong and tough (damage-tolerant) materials has traditionally been an exercise in compromise between hardness versus ductility. Drawing examples from metallic glasses, natural and biological materials, and structural and biomimetic ceramics, we examine some of the newer strategies in dealing with this conflict. Specifically, we focus on the interplay between the mechanisms that individually contribute to strength and toughness, noting that these phenomena can originate from very different lengthscales in a material's structural architecture. We show how these new and natural materials can defeat the conflict of strength versus toughness and achieve unprecedented levels of damage tolerance within their respective material classes.

  2. 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.

  3. Joint modelling of repeated measurements and event time: application to performance traits and survival of lambs bred in sub-humid tropics.

    PubMed

    Nguti, Rosemary; Burzykowski, Tomasz; Rowlands, John; Renard, Didier; Janssen, Paul

    2005-01-01

    We considered the analysis of a study for Dorper, Red Maasai and crossbred lambs born over a period of 6 years at the Diani Estate, Kenya. The study was designed to compare survival and performance traits of genotypes with differing susceptibilities to helminthiasis. The available data include information on time to death and repeated measurements of body weight, packed cell volume (PCV) and faecal egg count (FEC) of the animals. In the paper, we consider joint modelling of the survival time and the repeated measurements. Such an approach allows to account for the possible association between the survival and repeated measurement processes. The advantages and limitations of the joint modelling are discussed and illustrated using the Diani Estate study data. PMID:16194523

  4. Deoxyelephantopin, a novel multifunctional agent, suppresses mammary tumour growth and lung metastasis and doubles survival time in mice

    PubMed Central

    Huang, Chi-Chang; Lo, Chiu-Ping; Chiu, Chih-Yang; Shyur, Lie-Fen

    2010-01-01

    Background and purpose: Elephantopus scaber L. (Asteraceae) is a traditional herbal medicine with anti-cancer effects. We evaluated the in vitro and in vivo efficacy of a major sesquiterpene lactone constituent of E. scaber, deoxyelephantopin (DET), against mammary adenocarcinoma and the underlying molecular mechanism. Experimental approach: A variety of cellular assays, immunoblotting and immunohistochemistry, as well as both orthotopic and metastatic TS/A tumour models in BALB/c mice, were used. Test mice were pretreated and post-treated with DET or paclitaxel and mammary tumour growth evaluated. Key results: DET (≤2 µg·mL−1) significantly inhibited colony formation, cell proliferation, migration and invasion of TS/A cells and induced G2/M arrest and apoptosis in TS/A cells. c-Jun N-terminal kinase-mediated p21Waf1/Cip1 expression and caspase activation cascades were up-regulated by DET, effects suppressed by N-acetyl-L-cysteine. Moreover, tumour necrosis factor α-induced matrix metalloproteinase-9 enzyme activity and expression and nuclear factor-kappa B activation were abolished by DET. Pretreatment with DET was more effective than paclitaxel, for profound suppression of orthotopic tumour growth (99% vs. 68% reduction in tumour size) and lung metastasis of TS/A cells (82% vs. 63% reduction in metastatic pulmonary foci) and prolonged median survival time (56 vs. 37 days, P < 0.01) in mice. The levels of cyclooxygenase-2 and vascular endothelial growth factor in metastatic lung tissues of TS/A-bearing mice were attenuated by DET. Conclusions and implications: Our data provide evidence for the suppression of mammary adenocarcinoma by DET with several mechanisms and suggest that DET has potential as a chemopreventive agent for breast cancer. PMID:20105176

  5. 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-history strategy, population dynamics, and conservation of this long-lived snake.

  6. 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 labborn 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-history strategy, population dynamics, and conservation of this long-lived snake

  7. 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

  8. Toughness variation with test temperature and

    NASA Astrophysics Data System (ADS)

    German, R. M.; Hanafee, J. E.; Digiallonardo, S. L.

    1984-01-01

    A two phase heavy alloy composite based on 95 W-3.5 Ni-1.5 Fe (wt pct) was fabricated from elemental powders by liquid phase sintering. Past reports on the heavy alloys indicate considerable disagreement concerning cooling rate effects on toughness. The present experiments determined the effect of both cooling rate and test temperature on the properties of the 95 W heavy alloy. This alloy undergoes a ductile to brittle transition with decreasing test temperature; the transition temperature is close to room temperature. The cooling rate from post-sintering anneals carried out at temperatures greater than 1000 °C has a large influence on toughness; rapid quenching gives superior toughness. These findings support an impurity segregation explanation for embrittlement in the heavy alloys.

  9. Fracture toughness and strength of 96% alumina

    SciTech Connect

    Price, D.B.; Chinn, R.E.; McNerney, K.R.; Brog, T.K.; Kim, C.Y.; Krutyholowa, M.W.; Chen, N.W.; Haun, M.J.

    1997-05-01

    There exists a need to understand the controlling factors that simultaneously impact strength and toughness in 96% alumina. The enhancement of both strength and toughness enables designers to extend the use limits and reliability for structural ceramics. This article presents mechanical property results from a group study examining the use of different alkaline-earth aluminosilicate intergranular compositions containing magnesium, calcium and strontium oxides (RO) in 96% alumina. Principal results address trends in indentation strength toughness and modulus of rupture. Trends in the data are presented relative to existing theories of thermal expansion mismatch toughening, grain-bridging crack-wake effect and crack deflection mechanisms. Strength is addressed in terms of strength after indentation, crack growth of indentation flaws and Weibull characterization for the strength distribution.

  10. 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.

  11. 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…

  12. 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.

  13. 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.

  14. 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. PMID:23057247

  15. CDC Issues Tough New Guidelines on Use of Prescription Painkillers

    MedlinePlus

    ... medlineplus/news/fullstory_157775.html CDC Issues Tough New Guidelines on Use of Prescription Painkillers To curb ... and Vicodin, federal officials on Tuesday issued tough new prescribing guidelines to the nation's doctors. The new ...

  16. Fluid-driven cracks in an elastic matrix in the toughness-dominated limit.

    PubMed

    Lai, Ching-Yao; Zheng, Zhong; Dressaire, Emilie; Stone, Howard A

    2016-10-13

    The dynamics of fluid-driven cracks in an elastic matrix is studied experimentally. We report the crack radius R(t) as a function of time, as well as the crack shapes w(r,t) as a function of space and time. A dimensionless parameter, the pressure ratio Δpf/Δpv, is identified to gauge the relative importance between the toughness (Δpf) and viscous (Δpv) effects. In our previous paper (Lai et al. 2015 Proc. R. Soc. A 471, 20150255. (doi:10.1098/rspa.2015.0255)), we investigated the viscous limit experimentally when the toughness-related stresses are negligible for the crack propagation. In this paper, the experimental parameters, i.e. Young's modulus E of the gelatin, viscosity μ of the fracturing liquid and the injection flow rate Q, were chosen so that the viscous effects in the flow are negligible compared with the toughness effects, i.e. Δpf/Δpv≫1. In this limit, the crack dynamics can be described by the toughness-dominated scaling laws, which give the crack radius R(t)∝t(2/5) and the half maximum crack thickness W(t)∝t(1/5) The experimental results are in good agreement with the predictions of the toughness scaling laws: the experimental data for crack radius R(t) for a wide range of parameters (E,μ,Q) collapse after being rescaled by the toughness scaling laws, and the rescaled crack shapes w(r,t) also collapse to a dimensionless shape, which demonstrates the self-similarity of the crack shape. The appropriate choice of the viscous or toughness scaling laws is important to accurately describe the crack dynamics.This article is part of the themed issue 'Energy and the subsurface'. PMID:27597782

  17. 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.

  18. THE INFLUENCE OF MODEL TIME STEP ON THE RELATIVE SENSITIVITY OF POPULATION GROWTH TO SURVIVAL, GROWTH AND REPRODUCTION

    EPA Science Inventory

    Matrix population models are often used to extrapolate from life stage-specific stressor effects on survival and reproduction to population-level effects. Demographic elasticity analysis of a matrix model allows an evaluation of the relative sensitivity of population growth rate ...

  19. 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

  20. Joint modeling of longitudinal ordinal data and competing risks survival times and analysis of the NINDS rt-PA stroke trial

    PubMed Central

    Li, Ning; Elashoff, Robert M.; Li, Gang; Saver, Jeffrey

    2009-01-01

    SUMMARY Existing joint models for longitudinal and survival data are not applicable for longitudinal ordinal outcomes with possible non-ignorable missing values caused by multiple reasons. We propose a joint model for longitudinal ordinal measurements and competing risks failure time data, in which a partial proportional odds model for the longitudinal ordinal outcome is linked to the event times by latent random variables. At the survival endpoint, our model adopts the competing risks framework to model multiple failure types at the same time. The partial proportional odds model, as an extension of the popular proportional odds model for ordinal outcomes, is more flexible and at the same time provides a tool to test the proportional odds assumption. We use a likelihood approach and derive an EM algorithm to obtain the maximum likelihood estimates of the parameters. We further show that all the parameters at the survival endpoint are identifiable from the data. Our joint model enables one to make inference for both the longitudinal ordinal outcome and the failure times simultaneously. In addition, the inference at the longitudinal endpoint is adjusted for possible non-ignorable missing data caused by the failure times. We apply the method to the NINDS rt-PA stroke trial. Our study considers the modified Rankin Scale only. Other ordinal outcomes in the trial, such as the Barthel and Glasgow scales can be treated in the same way. PMID:19943331

  1. Therapeutic Cancer Vaccines in Prostate Cancer: The Paradox of Improved Survival Without Changes in Time to Progression

    PubMed Central

    Madan, Ravi A.; Fojo, Tito; Dahut, William L.

    2010-01-01

    Therapeutic cancer vaccines represent a new class of agents in the treatment of cancer. Sipuleucel-T is an antigen-presenting cell–based vaccine that recently demonstrated a significant 4.8-month improvement in overall survival in advanced prostate cancer patients and was well tolerated. The findings of that study have been met with skepticism, primarily because the agent did not change initial disease progression and yet led to longer survival. Although the commonly accepted treatment paradigm suggests that treatments should initially decrease tumor volume, perhaps vaccines work differently. Vaccines may induce delayed responses not seen in the first few months of therapy or they may initiate a dynamic immune response that ultimately slows the tumor growth rate, resulting in longer survival. Subsequent therapies may also combine with the induced immune response, resulting in a combination that is more effective than conventional treatments alone. Also, other treatments may alter tumor-associated antigen expression, enhancing the immune response. Future trials are currently planned to investigate these hypotheses; however, the results of the sipuleucel-T vaccine in prostate cancer should not be dismissed. Results with another vaccine in prostate cancer are similar, perhaps suggesting a class effect. In a broader context, clinicians may need to reconsider how they measure success. Several agents have been approved that produce superior disease progression results, but do not affect overall survival. Given the toxicity and costs of cancer therapies, perhaps studies should put more weight on long-term survival endpoints than on short-term endpoints that may be less consequential. PMID:20798195

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

    PubMed

    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

    1994-02-01

    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

  3. 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

  4. 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.

  5. Lupus a Tough Disease to Spot, Treat

    MedlinePlus

    ... Español You Are Here: Home → Latest Health News → Article URL of this page: https://medlineplus.gov/news/fullstory_159098.html Lupus a Tough Disease to Spot, Treat But experts say scientists are working to unearth genetic causes of autoimmune ...

  6. 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…

  7. Tough Ceramic Mimics Mother of Pearl

    ScienceCinema

    Ritchie, Robert

    2013-05-29

    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/

  8. Survey of fracture toughness test methods

    NASA Technical Reports Server (NTRS)

    Brown, W. F., Jr.; Jones, M. H.; Srawley, J. E.

    1968-01-01

    Comprehensive survey presents current methods of fracture toughness testing that are based on linear elastic fracture mechanics. General principles of the basic two dimensional crack stress field model are discussed in relation to real three dimensional specimens. Methods of test instrumentation and procedure are described.

  9. 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.

  10. 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/

  11. 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. PMID:22927966

  12. 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.

  13. The fracture toughness of soft tissues.

    PubMed

    Taylor, David; O'Mara, Niamh; Ryan, Eoin; Takaza, Michael; Simms, Ciaran

    2012-02-01

    Fracture toughness is important for any material, but to date there have been few investigations of this mechanical property in soft mammalian tissues. This paper presents new data on porcine muscle tissue and a detailed analysis of all previous work. The conclusion is that, in most cases, fracture toughness has not in fact been measured for these tissues. Reanalysis of the previous work shows that failure of the test specimens generally occurred at the material's ultimate strength, implying that no information about toughness can be obtained from the results. This finding applied to work on cartilage, artificial neocartilage, muscle and the TMJ disc. Our own data, which was also found to be invalid, gave measured fracture toughness values which were highly variable and showed a strong dependence on the crack growth increment. The net-section failure stress and failure energy were relatively constant in large specimens, independent of crack length, whilst for smaller specimens they showed a strong size effect. These findings are explained by the fact that the process zone size, estimated here using the critical distance parameter L, was similar to, or larger than, critical specimen dimensions (crack length and specimen width). Whilst this analysis casts doubt on much of the published literature, a useful finding is that soft tissues are highly tolerant of defects, able to withstand the presence of cracks several millimetres in length without significant loss of strength. PMID:22301183

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

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Fracture Toughness Requirements G Appendix G to Part 50 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION FACILITIES Pt. 50, App. G Appendix G to Part 50—Fracture Toughness Requirements I. Introduction and scope. II. Definitions. III. Fracture toughness tests....

  15. 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 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION FACILITIES Pt. 50, App. G Appendix G to Part 50—Fracture Toughness Requirements I. Introduction and scope. II. Definitions. III. Fracture toughness tests....

  16. 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 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION FACILITIES Pt. 50, App. G Appendix G to Part 50—Fracture Toughness Requirements I. Introduction and scope. II. Definitions. III. Fracture toughness tests....

  17. 10 CFR Appendix G to Part 50 - Fracture Toughness Requirements

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Fracture Toughness Requirements G Appendix G to Part 50 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION FACILITIES Pt. 50, App. G Appendix G to Part 50—Fracture Toughness Requirements I. Introduction and scope. II. Definitions. III. Fracture toughness tests....

  18. 10 CFR Appendix G to Part 50 - Fracture Toughness Requirements

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Fracture Toughness Requirements G Appendix G to Part 50 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION FACILITIES Pt. 50, App. G Appendix G to Part 50—Fracture Toughness Requirements I. Introduction and scope. II. Definitions. III. Fracture toughness tests....

  19. 46 CFR 54.05-5 - Toughness test specimens.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Toughness test specimens. 54.05-5 Section 54.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Toughness Tests § 54.05-5 Toughness test specimens. (a) Charpy V-notch impact tests. Where required,...

  20. 46 CFR 54.05-5 - Toughness test specimens.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Toughness test specimens. 54.05-5 Section 54.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Toughness Tests § 54.05-5 Toughness test specimens. (a) Charpy V-notch impact tests. Where required,...

  1. The limit of strength and toughness of steel

    SciTech Connect

    Guo, Zhen

    2001-12-17

    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.

  2. 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).

  3. Linking Reproduction and Survival Can Improve Model Estimates of Vital Rates Derived from Limited Time-Series Counts of Pinnipeds and Other Species

    PubMed Central

    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. PMID:24324541

  4. 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…

  5. Complex karyotype in mantle cell lymphoma is a strong prognostic factor for the time to treatment and overall survival, independent of the MCL international prognostic index.

    PubMed

    Sarkozy, Clémentine; Terré, Christine; Jardin, Fabrice; Radford, Isabelle; Roche-Lestienne, Catherine; Penther, Dominique; Bastard, Christian; Rigaudeau, Sophie; Pilorge, Sylvain; Morschhauser, Franck; Bouscary, Didier; Delarue, Richard; Farhat, Hassan; Rousselot, Philippe; Hermine, Olivier; Tilly, Hervé; Chevret, Sylvie; Castaigne, Sylvie

    2014-01-01

    Mantle cell lymphoma (MCL) is usually an aggressive disease. However, a few patients do have an "indolent" evolution (iMCL) defined by a long survival time without intensive therapy. Many studies highlight the prognostic role of additional genetic abnormalities, but these abnormalities are not routinely tested for and do not yet influence the treatment decision. We aimed to evaluate the prognostic impact of these additional abnormalities detected by conventional cytogenetic testing, as well as their relationships with the clinical characteristics and their value in identifying iMCL. All consecutive MCL cases diagnosed between 1995 and 2011 at four institutions were retrospectively selected on the basis of an informative karyotype with a t(11;14) translocation at the time of diagnosis. A total of 125 patients were included and followed for an actual median time of 35 months. The median overall survival (OS) and survival without treatment (TFS) were 73.7 and 1.3 months, respectively. In multivariable Cox models, a high mantle cell lymphoma international prognostic index score, a complex karyotype, and blastoid morphology were independently associated with a shortened OS. Spleen enlargement, nodal presentation, extra-hematological involvement, and complex karyotypes were associated with shorter TFS. A score based on these factors allowed for the identification of "indolent" patients (median TFS 107 months) from other patients (median TFS: 1 month). In conclusion, in this multicentric cohort of MCL patients, a complex karyotype was associated with a shorter survival time and allowed for the identification of iMCL at the time of diagnosis. PMID:24249260

  6. Longer waiting times for early stage cervical cancer patients undergoing radical hysterectomy are associated with diminished long-term overall survival

    PubMed Central

    Nanthamongkolkul, Kulisara

    2015-01-01

    Objective The aim of this study was to evaluate the impact of surgical waiting time on clinical outcome in early stage cervical cancer. Methods The cohort consisted of 441 patients diagnosed with stages IA2-IB1cervical cancer who underwent radical hysterectomy and pelvic node dissection. The patients were divided into two groups based on surgical waiting time. The associations between waiting time and other potential prognostic factors with clinical outcome were evaluated. Results The median surgical waiting time was 43 days. Deep stromal invasion (hazard ratio [HR], 2.5; 95% confidence interval [CI], 1.4 to 4.6; p=0.003) and lymph node metastasis (HR, 2.9; 95% CI, 1.3 to 6.7; p=0.026) were identified as independent prognostic factors for recurrence-free survival while no prognostic significance of surgical waiting time was found (p=0.677). On multivariate analysis of overall survival (OS), only deep stromal invasion (HR, 2.6; 95% CI, 1.3 to 5.0; p=0.009) and lymph node metastasis (HR, 3.6; 95% CI, 1.5 to 8.6; p=0.009) were identified as independent prognostic factors for OS. Although OS showed no significant difference between short (≤8 weeks) and long (>8 weeks) waiting times, multivariate analysis of OS with time-varying effects revealed that a waiting time longer than 8 weeks was associated with poorer long-term survival (after 5 years; HR, 3.4; 95% CI, 1.3 to 9.2; p=0.021). Conclusion A longer surgical waiting time was associated with diminished long-term OS of early stage cervical cancer patients. PMID:26404122

  7. 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.

  8. 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.; U.S. Geological Survey; Gillikin, Daniel; U.S. Fish and Wildlife Service

    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.

  9. A race against time: can CO-OPs and provider start-ups survive in the health insurance marketplaces?

    PubMed

    Eggbeer, Bill

    2015-12-01

    > The Affordable Care Act's state and federal health insurance marketplaces, designed to provide affordable insurance coverage to individuals and small groups, are proving hostile territory to new market entrants. Efforts to inject competition into the marketplaces are being challenged by the wide-scale withdrawal o consumer-operated and oriented plans (CO-OPs). Meanwhile, premiums appear likely to increase for consumers as plans seek to balance medical losses. Flaws in the "Three R's" (reinsurance, risk corridors, and risk-adjustment) program are viewed as a threat to the survival of CO-OPs and start-ups. PMID:26793946

  10. Human umbilical cord mesenchymal stromal cells suppress MHC class II expression on rat vascular endothelium and prolong survival time of cardiac allograft

    PubMed Central

    Qiu, Ying; Yun, Mark M; Han, Xia; Zhao, Ruidong; Zhou, Erxia; Yun, Sheng

    2014-01-01

    Background: Human umbilical cord mesenchymal stromal cells (UC-MSCs) have low immunogenicity and immune regulation. To investigate immunomodulatory effects of human UC-MSCs on MHC class II expression and allograft, we transplanted heart of transgenic rats with MHC class II expression on vascular endothelium. Methods: UC-MSCs were obtained from human umbilical cords and confirmed with flow cytometry analysis. Transgenic rat line was established using the construct of human MHC class II transactivator gene (CIITA) under mouse ICAM-2 promoter control. The induced MHC class II expression on transgenic rat vascular endothelial cells (VECs) was assessed with immunohistological staining. And the survival time of cardiac allograft was compared between the recipients with and without UC-MSC transfusion. Results: Flow cytometry confirmed that the human UC-MSCs were positive for CD29, CD44, CD73, CD90, CD105, CD271, and negative for CD34 and HLA-DR. Repeated infusion of human UC-MSCs reduced MHC class II expression on vascular endothelia of transplanted hearts, and increased survival time of allograft. The UC-MSCs increased regulatory cytokines IL10, transforming growth factor (TGF)-β1 and suppressed proinflammatory cytokines IL2 and IFN-γ in vivo. The UC-MSC culture supernatant had similar effects on cytokine expression, and decreased lymphocyte proliferation in vitro. Conclusions: Repeated transfusion of the human UC-MSCs reduced MHC class II expression on vascular endothelia and prolonged the survival time of rat cardiac allograft. PMID:25126177

  11. Haloarchaeal survival over geological times and the detection of extraterrestrial halite - implications for the search for life on Mars

    NASA Astrophysics Data System (ADS)

    Stan-Lotter, Helga; Legat, Andrea; Fendrihan, Sergiu; Leuko, Stefan; Gruber, Claudia; Radax, Christian; Pfaffenhuemer, Marion; Weidler, Gerhard; Rittmann, Simon

    2004-03-01

    Several viable extremely halophilic archaebacteria (haloarchaea) were isolated previously from Permo-Triassic salt sediments. We described two halococcal strains from rock salt of the salt mine in Bad Ischl, Austria. Recently, we isolated a rod-shaped haloarchaeal species from a salt bore core. In addition, sequencing of 16S rRNA genes from dissolved rock salt indicated the presence of a vast diversity of as yet uncultured haloarchaea. The results are compatible with the notion that these haloarchaea might be the remnants of microbial communities which populated the ancient hypersaline seas. How they survived in the dry salt evaporites is not known. Extremely dry conditions are characteristic for the Martian surface and perhaps also subsurface; since extraterrestrial halite has been discovered in meteorites from Mars and other celestial bodies, it appears feasible to explore the response of haloarchaea to simulated Martian environments. Preliminary results suggested survival rates of haloarchaea, following freezing, freeze-drying or embedding in salt crystals, respectively, in the range of 0.1 to 10%. Thus, low water activities and low temperatures appear to be tolerated well by haloarchaea.

  12. Fracture toughness and crack growth of Zerodur

    NASA Technical Reports Server (NTRS)

    Viens, Michael J.

    1990-01-01

    The fracture toughness and crack growth parameters of Zerodur, a low expansion glass ceramic material, were determined. The fracture toughness was determined using indentation techniques and was found to be 0.9 MPa x m(sup 1/2). The crack growth parameters were determined using indented biaxial specimens subjected to static and dynamic loading in an aqueous environment. The crack growth parameters n and 1n(B) were found to be 30.7 and -6.837, respectively. The crack growth parameters were also determined using indented biaxial specimens subjected to dynamic loading in an ambient 50 percent relative humidity environment. The crack growth parameters n and 1n(B) at 50 percent relative humidity were found to be 59.3 and -17.51, respectively.

  13. Interlaminar fracture toughness of thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.; Johnston, Norman J.; O'Brien, T. Kevin

    1989-01-01

    Edge delamination tension and double cantilever beam tests were used to characterize the interlaminar fracture toughness of continuous graphite-fiber composites made from experimental thermoplastic polyimides and a model thermoplastic. Residual thermal stresses, known to be significant in materials processed at high temperatures, were included in the edge delamination calculations. In the model thermoplastic system (polycarbonate matrix), surface properties of the graphite fiber were shown to be significant. Cricital strain energy release rates for two different fibers having similar nominal tensile properties differed by 30 to 60 percent. The reason for the difference is not clear. Interlaminar toughness values for the thermoplastic polyimide composites (LARC-TPI and polyimidesulfone) were 3 to 4 in-lb/sq in. Scanning electron micrographs of the EDT fracture surfaces suggest poor fiber/matrix bonding. Residual thermal stresses account for up to 32 percent of the strain energy release in composites made from these high-temperature resins.

  14. Resin blending for toughness in balloon films

    NASA Technical Reports Server (NTRS)

    Farr, M. P.; Harrison, I. R.

    1993-01-01

    The influence of chain architecture on toughness is examined by testing blends of HDPE with different types of low density PEs. The LDPE and LLDPE used have reported similar molecular weights, and densities. Two structural factors differentiate these polymers, long chain branching is peculiar to LDPE, and the short chain branching distribution of the two polymers are different. LDPE has branches which are evenly distributed among all chains. In contrast, the short chain branches in LLDPE are distributed heterogeneously. LLDPE and ULDPE have similar branch distributions but, ULDPE has a higher average number of branches per 1000 carbons and consequently a lower density. The effect which these structural differences have on mechanical properties can be used to investigate which parameters control toughness in PE materials.

  15. Interlaminar fracture toughness of thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Hinkley, J. A.; Johnston, N. J.; Obrien, T. K.

    1988-01-01

    Edge delamination tension and double cantilever beam tests were used to characterize the interlaminar fracture toughness of continuous graphite-fiber composites made from experimental thermoplastic polyimides and a model thermoplastic. Residual thermal stresses, known to be significant in materials processed at high temperatures, were included in the edge delamination calculations. In the model thermoplastic system (polycarbonate matrix), surface properties of the graphite fiber were shown to be significant. Critical strain energy release rates for two different fibers having similar nominal tensile properties differed by 30 to 60 percent. The reason for the difference is not clear. Interlaminar toughness values for the thermoplastic polyimide composites (LARC-TPI and polyimidesulfone) were 3 to 4 in-lb/sq in. Scanning electron micrographs of the EDT fracture surfaces suggest poor fiber/matrix bonding. Residual thermal stresses account for up to 32 percent of the strain energy release in composites made from these high-temperature resins.

  16. 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.

  17. Modeling the concentration-response function of the herbicide dinoseb on Daphnia magna (survival time, reproduction) and Pseudokirchneriella subcapitata (growth rate).

    PubMed

    Chèvre, Nathalie; Brazzale, Alessandra R; Becker-van Slooten, Kristin; Behra, Renata; Tarradellas, Joseph; Guettinger, Herbert

    2005-09-01

    Models describing dose-response relationships are becoming increasingly popular in ecotoxicology. They allow simple and thorough evaluations of toxicity test results, including inter- and extrapolations to concentrations or exposure times other than those tested. Simple parametric regression models are of particular interest because their parameters may be attributed mechanistic meanings and they can be applied without sophisticated mathematical and computational support. We recently proposed a four-parameter logistic regression model to fit the survival data of Daphnia magna under dinoseb stress. The model parameters are the maximum survival time, the minimum time required for an individual to die, effect concentration, EC(50), and a curve shape parameter. This model has now been applied to compare the lethality and reproduction toxicity of D. magna and the growth inhibition of Pseudokirchneriella subcapitata under dinoseb stress. It can be fitted adequately to all the measured data and the parameters can be attributed biological meanings in any of the three endpoints. A comparison of the modeled concentration-response functions of all three endpoints for dinoseb toxicity shows that the range of ECs with respect to both D. magna and algae is steep (a decrease of between 0.1 and 0.6 mg/L). The survival and reproduction of D. magna exhibit similar characteristic concentration-response functions and toxicities. The statistical no-effect concentration (SNEC) is 0.14 (survival) and 0.11 (reproduction)mg/L, respectively. On the other hand, algae seem to be less sensitive to dinoseb than D. magna (SNEC: 0.48 mg/L). However, further investigations of individual algae may lead to a more suitable comparison. We speculate that the four parameters of the model function can be related to specific properties of chemicals and organisms. Characterization of these properties would allow simple and appropriate estimation of the toxic effects of these chemicals. PMID:15978287

  18. 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.

  19. Resin selection criteria for tough composite structures

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Smith, G. T.

    1983-01-01

    Resin selection criteria are derived using a structured methodology consisting of an upward integrated mechanistic theory and its inverse (top-down structured theory). These criteria are expressed in a "criteria selection space" which are used to identify resin bulk properties for improved composite "toughness". The resin selection criteria correlate with a variety of experimental data including laminate strength, elevated temperature effects and impact resistance.

  20. 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.

  1. 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.

  2. Greatly increased toughness of infiltrated spider silk.

    PubMed

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

    2009-04-24

    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. PMID:19390040

  3. 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. PMID:26352293

  4. Effect of noise and detector sensitivity on a dynamical process: inverse power law and Mittag-Leffler interevent time survival probabilities.

    PubMed

    Pramukkul, Pensri; Svenkeson, Adam; Grigolini, Paolo

    2014-02-01

    We study the combined effects of noise and detector sensitivity on a dynamical process that generates intermittent events mimicking the behavior of complex systems. By varying the sensitivity level of the detector we move between two forms of complexity, from inverse power law to Mittag-Leffler interevent time survival probabilities. Here fluctuations fight against complexity, causing an exponential truncation to the survival probability. We show that fluctuations of relatively weak intensity have a strong effect on the generation of Mittag-Leffler complexity, providing a reason why stretched exponentials are frequently found in nature. Our results afford a more unified picture of complexity resting on the Mittag-Leffler function and encompassing the standard inverse power law definition. PMID:25353422

  5. Effect of noise and detector sensitivity on a dynamical process: Inverse power law and Mittag-Leffler interevent time survival probabilities

    NASA Astrophysics Data System (ADS)

    Pramukkul, Pensri; Svenkeson, Adam; Grigolini, Paolo

    2014-02-01

    We study the combined effects of noise and detector sensitivity on a dynamical process that generates intermittent events mimicking the behavior of complex systems. By varying the sensitivity level of the detector we move between two forms of complexity, from inverse power law to Mittag-Leffler interevent time survival probabilities. Here fluctuations fight against complexity, causing an exponential truncation to the survival probability. We show that fluctuations of relatively weak intensity have a strong effect on the generation of Mittag-Leffler complexity, providing a reason why stretched exponentials are frequently found in nature. Our results afford a more unified picture of complexity resting on the Mittag-Leffler function and encompassing the standard inverse power law definition.

  6. Determination of dynamic fracture toughness using a new experimental technique

    NASA Astrophysics Data System (ADS)

    Cady, Carl M.; Liu, Cheng; Lovato, Manuel L.

    2015-09-01

    In other studies dynamic fracture toughness has been measured using Charpy impact and modified Hopkinson Bar techniques. In this paper results will be shown for the measurement of fracture toughness using a new test geometry. The crack propagation velocities range from ˜0.15 mm/s to 2.5 m/s. Digital image correlation (DIC) will be the technique used to measure both the strain and the crack growth rates. The boundary of the crack is determined using the correlation coefficient generated during image analysis and with interframe timing the crack growth rate and crack opening can be determined. A comparison of static and dynamic loading experiments will be made for brittle polymeric materials. The analysis technique presented by Sammis et al. [1] is a semi-empirical solution, however, additional Linear Elastic Fracture Mechanics analysis of the strain fields generated as part of the DIC analysis allow for the more commonly used method resembling the crack tip opening displacement (CTOD) experiment. It should be noted that this technique was developed because limited amounts of material were available and crack growth rates were to fast for a standard CTOD method.

  7. EOSN: A TOUGH2 module for noble gases

    SciTech Connect

    Shan, Chao; Pruess, Karsten

    2003-03-07

    We developed a new fluid property module for TOUGH2, called EOSN, to simulate transport of noble gases in the subsurface. Currently, users may select any of five different noble gases as well as CO2, two at a time. For the three gas components (air and two user-specified noble gases) in EOSN, the Henry's coefficients and the diffusivities in the gas phase are no longer assumed constants, but are temperature dependent. We used the Crovetto et al. (1982) model to estimate Henry's coefficients, and the Reid et al. (1987) correlations to calculate gas phase diffusivities. The new module requires users to provide names of the selected noble gases, which properties are provided internally. There are options for users to specify any (non-zero) molecular weights and half-lives for the gas components. We provide two examples to show applications of TOUGH2IEOSN. While temperature effects are relatively insignificant for one example problem where advection is dominant, they cause almost an order of magnitude difference for the other case where diffusion becomes a dominant process and temperature variations are relatively large. It appears that thermodynamic effects on gas diffusivities and Henry's coefficients can be important for low-permeability porous media and zones with large temperature variations.

  8. 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

  9. '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.

  10. Piscivory in juvenile walleyes: Relative importance of prey species, timing of spawning of prey fish, and density on growth and survival

    USGS Publications Warehouse

    Kolar, C.S.; Wahl, David H.; Hooe, M.L.

    2003-01-01

    We examined the effect of the timing of spawning by prey fish and the species of prey fish on the growth and survival of juvenile walleye Stizostedion vitreum. We expected that age-0 walleyes would grow more in ponds when stocked about the same time as the spawning of gizzard shad Dorosoma cepedianum than when stocked about 6 weeks after spawning. We found, however, that the timing of larval gizzard shad presence did not affect walleye growth or survival. Also contrary to our expectations, walleyes from ponds with bluegill Lepomis macrochirus grew more (by 9% in total length and 38% in mass) than those from ponds with gizzard shad. However, the density of gizzard shad was lower than that of bluegills, particularly after the first few weeks of the experiment. Bluegills remained within the gape limits of walleyes throughout the experiment, whereas gizzard shad outgrew their vulnerability to predation. Late-spawned gizzard shad remained vulnerable to walleye predation only slightly longer than did those from early spawned ponds. The survival of age-0 walleyes was unaffected by water temperature, the timing of spawning by prey fish, prey species, or density. Our results suggest that even though walleyes typically grow faster in systems with gizzard shad as prey than in those with bluegills, juvenile walleyes can still grow well in bluegill-dominated systems. In some systems, high densities of a less beneficial prey (e.g., abundant bluegills rather than less abundant gizzard shad) may overcome the growth differences of juvenile walleyes that would be expected based on the differences in prey species alone. A wide variation in individual walleye growth in our ponds, even within prey treatments, indicated the complexity of interactions among the factors affecting juvenile walleye growth.

  11. Influence of microstructure on fracture toughness of austempered ductile iron

    SciTech Connect

    Rao, P.P.; Putatunda, S.K.

    1997-07-01

    An investigation was carried out to examine the influence of microstructure on the plane strain fracture toughness of austempered ductile iron. Austempered ductile iron (ADI) alloyed with nickel, copper, and molybdenum was austenitized and subsequently austempered over a range of temperatures to produce different microstructures. The microstructures were characterized through optical microscopy and X-ray diffraction. Plane strain fracture toughness of all these materials was determined and was correlated with the microstructure. The results of the present investigation indicate that the lower bainitic microstructure results in higher fracture toughness than upper bainitic microstructure. Both volume fraction of retained austenite and its carbon content influence the fracture toughness. The retained austenite content of 25 vol pct was found to provide the optimum fracture toughness. It was further concluded that the carbon content of the retained austenite should be as high as possible to improve fracture toughness.

  12. 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).

  13. 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.

  14. Survival Benefits With Artificial Liver Support System for Acute-on-Chronic Liver Failure: A Time Series-Based Meta-Analysis.

    PubMed

    Shen, Yi; Wang, Xu-Lin; Wang, Bin; Shao, Jian-Guo; Liu, Yan-Mei; Qin, Yan; Wang, Lu-Jun; Qin, Gang

    2016-01-01

    The artificial liver support system (ALSS) offers the potential to improve the prognosis of patients with acute-on-chronic liver failure (ACLF). However, the literature has been inconsistent on its survival benefits. We aimed to conduct a time series-based meta-analysis of randomized clinical trials (RCTs) and observational studies which examined differences in mortality in ACLF patients treated with ALSS or not.MEDLINE, EMBASE, OVID, and COCHRANE library database were systemically searched up to December 2014. Quality of included studies was evaluated using the Jadad score. The outcome measure was mortality at different follow-up endpoints. Odds ratios (ORs) and survival curve data were pooled for analysis.Ten studies, 7 RCTs, and 3 controlled cohorts were enrolled, involving a total of 1682 ACLF patients, among whom 842 were treated with ALSS. ALSS was found to reduce the risk of short-term (1-month and 3-month) mortality for patients with ACLF by nearly 30%. Randomized trials and observational studies provided good internal and external validity respectively. The combined Kaplan-Meier curves showed a consistent pattern of findings. Meta-analysis also suggested that ALSS might reduce medium-term (6-month and 1-year) mortality risk by 30% and long-term (3-year) mortality risk by 50% in ACLF patients.ALSS therapy could reduce short-term mortality in patients with ACLF. Meanwhile, its impacts on medium- and long-term survival seem to be promising but remained inconclusive. Clinical utility of this system for survival benefit may be implied. PMID:26817889

  15. The hardness and toughness of HIPed silicon nitride

    SciTech Connect

    Berriche, R.; Holt, R.T.; Kumar, S.N.; Maccagno, T.M.

    1992-10-01

    Silicon nitride with and without additives has been produced by hot isostatic pressing under different conditions. The HIP cycle parameters and grade of powder used have been found to affect the density, the hardness and the fracture toughness of the material produced. Sintering aids, on the other hand, have been found to affect the fracture toughness only. Materials HIPed with additives displayed a higher fracture toughness than materials HIPed without additives. 12 refs.

  16. Low-Temperature Toughness of the Austempered Offshore Steel

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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.

  17. Leaf cellulose density as the key determinant of inter- and intra-specific variation in leaf fracture toughness in a species-rich tropical forest.

    PubMed

    Kitajima, Kaoru; Wright, S Joseph; Westbrook, Jared W

    2016-06-01

    Leaves as the main photosynthetic organ of plants must be well protected against various hazards to achieve their optimal lifespans. Yet, within-species variation and the material basis of leaf strength have been explored for very few species. Here, we present a large dataset of leaf fracture toughness from a species-rich humid tropical forest on Barro Colorado Island, Panama, reporting both among- and within-species variation in relation to light environment (sun-lit canopy versus shaded understorey) and ontogeny (seedlings versus adults). In this dataset encompassing 281 free-standing woody species and 428 species-light combinations, lamina fracture toughness varied ca 10 times. A central objective of our study was to identify generalizable patterns in the structural and material basis for interspecific variation in leaf lamina fracture toughness. The leaf lamina is a heterogeneous structure in which strong materials in cell walls, such as cellulose and lignin, contribute disproportionately to fracture toughness. We found significant increases in leaf fracture toughness from shade to sun and from seedling leaves to adult leaves. Both within and across species, leaf fracture toughness increased with total bulk density (dry biomass per unit volume) and cellulose mass concentration, but decreased with mass concentrations of lignin and hemicelluose. These bivariate relationships shift between light environments, but leaf cellulose density (cellulose mass per unit leaf volume) exhibits a common relationship with lamina fracture toughness between light environments and through ontogeny. Hence, leaf cellulose density is probably a universal predictor of leaf fracture toughness. PMID:27274796

  18. iTOUGH2 V7.0

    SciTech Connect

    2013-07-01

    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, 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. 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 (derivativefree, 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) joint hydrogeophysical inversion methods, (c) additional input features and output analyses, (d) increased forward simulation capabilities, (e) reducedorder modeling capabilities, (f) parallel execution of multicore PCs and Linux clusters, and (g) bug fixes. More details can be found at http://esd.lbl.gov/iTOUGH2 and the publications cited in Part II, H.

  19. iTOUGH2 V7.0

    Energy Science and Technology Software Center (ESTSC)

    2013-07-01

    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, 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, andmore » uncertainty quantification of any external code that uses text-based input and output files. 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 (derivativefree, 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) joint hydrogeophysical inversion methods, (c) additional input features and output analyses, (d) increased forward simulation capabilities, (e) reducedorder modeling capabilities, (f) parallel execution of multicore PCs and Linux clusters, and (g) bug fixes. More details can be found at http://esd.lbl.gov/iTOUGH2 and the publications cited in Part II, H.« less

  20. 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

  1. 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

  2. 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.

  3. 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

  4. Study on the Hot Processing Parameters-Impact Toughness Correlation of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing

    2016-05-01

    In this research, the hot processing parameters-impact toughness correlation of Ti-6Al-4V titanium alloy is studied. Fifty-four groups of hot processing treatments with different forging temperatures (930, 950, 970 °C), deformation degrees (20, 50, 80%), annealing temperatures (600, 700, 800 °C), and annealing time (1 and 5 h) were conducted. The orthogonal design was used to find the primary hot processing parameters influencing the impact toughness of Ti-6Al-4V alloy. The results show that the annealing temperature can exert the biggest influence on impact toughness. Low annealing temperature is essential to achieve high impact toughness value. In addition, the BP neural network was used to describe the quantitative correlation between hot processing parameters and impact toughness. The results show that the BP neural network exhibits good performance in predicting the impact toughness of Ti-6Al-4V alloy. The prediction error is within 5%. The BP neural network and the orthogonal design method are mutually confirmed in the present work. Finally, based on the microstructure analysis, the reasons responsible for above experimental results are explained.

  5. Study on the Hot Processing Parameters-Impact Toughness Correlation of Ti-6Al-4V Alloy

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing

    2016-04-01

    In this research, the hot processing parameters-impact toughness correlation of Ti-6Al-4V titanium alloy is studied. Fifty-four groups of hot processing treatments with different forging temperatures (930, 950, 970 °C), deformation degrees (20, 50, 80%), annealing temperatures (600, 700, 800 °C), and annealing time (1 and 5 h) were conducted. The orthogonal design was used to find the primary hot processing parameters influencing the impact toughness of Ti-6Al-4V alloy. The results show that the annealing temperature can exert the biggest influence on impact toughness. Low annealing temperature is essential to achieve high impact toughness value. In addition, the BP neural network was used to describe the quantitative correlation between hot processing parameters and impact toughness. The results show that the BP neural network exhibits good performance in predicting the impact toughness of Ti-6Al-4V alloy. The prediction error is within 5%. The BP neural network and the orthogonal design method are mutually confirmed in the present work. Finally, based on the microstructure analysis, the reasons responsible for above experimental results are explained.

  6. 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.

  7. 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.

  8. 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

  9. Activation and survival of immature neurons in the dentate gyrus with spatial memory is dependent on time of exposure to spatial learning and age of cells at examination.

    PubMed

    Epp, Jonathan R; Haack, Andrew K; Galea, Liisa A M

    2011-03-01

    Neurogenesis continues to occur throughout life in the dentate gyrus of the hippocampus and may be related to hippocampus-dependent learning. We have recently reported that there is an enhancement of neurogenesis in the hippocampus only when BrdU is administered 6 days prior to starting spatial training but not when training started either 1 day or 11 days following BrdU administration. In that study, all rats were perfused on day 16 after BrdU injection in order to compare cells of the same age (i.e. 16 day old cells) and thus the survival time after learning was different between groups. This study was designed to address whether the amount of time that passed following training could also contribute to the effects of spatial learning on hippocampal neurogenesis and whether there was differential new neuron activation in response to spatial learning that depended on the age of new cells at the time of spatial learning. Here we tested whether a survival period of 5 days following spatial learning at either 1-5, 6-10 or 11-15 days following BrdU administration would alter cell survival and/or activation of new neurons. Our results indicate that 5 days after training in the Morris water task cell survival is unaltered by training on days 1-5, increased by training at days 6-10 and decreased when training occurs on days 11-15. Furthermore spatial learners trained on days 6-10 or 11-15 show greater activation of new neurons compared to cue-trained rats during a probe trial 5 days after training. In addition, rats trained on the spatial task on days 11-15 had a greater number of activated new neurons compared to rats trained on the spatial task on days 6-10. These results suggest there is a gradual removal of older BrdU-labeled new neurons following spatial learning perhaps due to a competitive interaction with a population of younger BrdU-labeled new neurons. PMID:21216298

  10. Gender and Timing during Ontogeny Matter: Effects of a Temporary High Temperature on Survival, Body Size and Colouration in Harmonia axyridis

    PubMed Central

    Knapp, Michal; Nedvěd, Oldřich

    2013-01-01

    The ambient temperature experienced during development is a crucial factor affecting survival and adult phenotype in ectotherms. Moreover, the exact response of individuals to different temperature regimes is frequently sex-specific. This sex-specific response can result in varying levels of sexual dimorphism according to the experienced conditions. The majority of studies have investigated the effects of temperature on individuals reared under a constant temperature regime throughout their whole preimaginal development, whereas information on stage-dependent variation in temperature effects is scarce. Here we investigate how the stage at which elevated temperature is experienced influences survival, adult body size and colouration in the harlequin ladybird Harmonia axyridis form succinea. The effects of timing of exposure to elevated temperature on the adult phenotype are assessed separately for males and females. Control individuals were reared at a constant temperature of 20°C. Beetles in other treatments were additionally exposed to 33°C for 48 hours during the following developmental stages: egg, 1st to 2nd larval instar, 3rd larval instar, 4th larval instar and pupa. Exposure to an elevated temperature during the early developmental stages resulted in lower survival, but the adult phenotype of survivors was almost unaffected. Exposure to an elevated temperature during the later developmental stages (4th larval instar or pupa) resulted in the decreased melanisation of elytra, decreased structural body size and increased dry mass. Furthermore, the timing of high temperature exposure affected the degree of sexual dimorphism in elytral melanisation and dry mass. We demonstrate that the effects of elevated temperature can vary according to the developmental stage at exposure. Detailed information on how ambient temperature affects the developmental biology of ectotherms is crucial for modeling population growth and predicting the spread of invasive species such

  11. Expression of the macrophage antigen CD163 in rectal cancer cells is associated with early local recurrence and reduced survival time.

    PubMed

    Shabo, Ivan; Olsson, Hans; Sun, Xiao-Feng; Svanvik, Joar

    2009-10-15

    Expression of the macrophage antigen CD163 in breast cancer cells is recently shown to be related to early distant recurrence and shortened survival. In this study, 163 patients with rectal cancer, included in the Swedish rectal cancer trial and followed up for a median of 71 months, were examined for the expression of CD163 in the primary tumors. The cancer cells expressed CD163 in the primary tumors in 23% (n = 32) of the patients. In pretreatment biopsies from 101 patients, 10 had CD163-positive cancers and these patients had earlier local recurrence (p < 0.044) and reduced survival time (p < 0.045) compared with those with CD163-negative tumors. When studying surgical specimens from 61 patients randomized to preoperative irradiation (5 x 5 Gy delivered in 1 week), it was found that 31% were CD163 positive whereas the corresponding figure was only 17% for 78 patients who were nonirradiated (p < 0.044), which tentatively may be consistent with X-rays inducing fusion. In CD163-positive tumors there was a reduced apoptotic activity as measured with the Termina deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) technique (p = 0.018). There tended also to be an increased proliferation activity measured as an expression of Ki-67 non significant (NS). It is concluded that primary rectal cancers may express CD-163, and this phenotypic macrophage trait is related to early local recurrence, shorter survival time and reduced apoptosis. Furthermore, the expression of CD163 is more common after irradiation. PMID:19582880

  12. Gender and timing during ontogeny matter: effects of a temporary high temperature on survival, body size and colouration in Harmonia axyridis.

    PubMed

    Knapp, Michal; Nedvěd, Oldřich

    2013-01-01

    The ambient temperature experienced during development is a crucial factor affecting survival and adult phenotype in ectotherms. Moreover, the exact response of individuals to different temperature regimes is frequently sex-specific. This sex-specific response can result in varying levels of sexual dimorphism according to the experienced conditions. The majority of studies have investigated the effects of temperature on individuals reared under a constant temperature regime throughout their whole preimaginal development, whereas information on stage-dependent variation in temperature effects is scarce. Here we investigate how the stage at which elevated temperature is experienced influences survival, adult body size and colouration in the harlequin ladybird Harmonia axyridis form succinea. The effects of timing of exposure to elevated temperature on the adult phenotype are assessed separately for males and females. Control individuals were reared at a constant temperature of 20 °C. Beetles in other treatments were additionally exposed to 33 °C for 48 hours during the following developmental stages: egg, 1(st) to 2(nd) larval instar, 3(rd) larval instar, 4(th) larval instar and pupa. Exposure to an elevated temperature during the early developmental stages resulted in lower survival, but the adult phenotype of survivors was almost unaffected. Exposure to an elevated temperature during the later developmental stages (4(th) larval instar or pupa) resulted in the decreased melanisation of elytra, decreased structural body size and increased dry mass. Furthermore, the timing of high temperature exposure affected the degree of sexual dimorphism in elytral melanisation and dry mass. We demonstrate that the effects of elevated temperature can vary according to the developmental stage at exposure. Detailed information on how ambient temperature affects the developmental biology of ectotherms is crucial for modeling population growth and predicting the spread of invasive

  13. Music Travel in Tough Times: Yes, It Broadens the Mind--But It also Empties the Wallet. Nevertheless, Many Music Teachers Are Still Finding Ways to Keep Their Students on the Move, Even during a Recession

    ERIC Educational Resources Information Center

    Poliniak, Susan

    2009-01-01

    It is certainly no secret that people are living in a difficult economic climate. In these times of belt-tightening, both institutional and personal, budgets for arts education are being slashed and individual donations are plummeting. Music teachers in particular know well the impact of these developments on their programs, and they know that…

  14. Gene Expression Mapping of Histone Deacetylases and Co-factors, and Correlation with Survival Time and 1H-HRMAS Metabolomic Profile in Human Gliomas

    PubMed Central

    Dali-Youcef, Nassim; Froelich, Sébastien; Moussallieh, François-Marie; Chibbaro, Salvatore; Noël, Georges; Namer, Izzie J.; Heikkinen, Sami; Auwerx, Johan

    2015-01-01

    Primary brain tumors are presently classified based on imaging and histopathological techniques, which remains unsatisfaying. We profiled here by quantitative real time PCR (qRT-PCR) the transcripts of eighteen histone deacetylases (HDACs) and a subset of transcriptional co-factors in non-tumoral brain samples from 15 patients operated for epilepsia and in brain tumor samples from 50 patients diagnosed with grade II oligodendrogliomas (ODII, n = 9), grade III oligodendrogliomas (ODIII, n = 22) and glioblastomas (GL, n = 19). Co-factor transcripts were significantly different in tumors as compared to non-tumoral samples and distinguished different molecular subgroups of brain tumors, regardless of tumor grade. Among all patients studied, the expression of HDAC1 and HDAC3 was inversely correlated with survival, whereas the expression of HDAC4, HDAC5, HDAC6, HDAC11 and SIRT1 was significantly and positively correlated with survival time of patients with gliomas. 1H-HRMAS technology revealed metabolomically distinct groups according to the expression of HDAC1, HDAC4 and SIRT1, suggesting that these genes may play an important role in regulating brain tumorigenesis and cancer progression. Our study hence identified different molecular fingerprints for subgroups of histopathologically similar brain tumors that may enable the prediction of outcome based on the expression level of co-factor genes and could allow customization of treatment. PMID:25791281

  15. 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.

  16. A cleavage toughness master curve model

    NASA Astrophysics Data System (ADS)

    Odette, G. R.; He, M. Y.

    2000-12-01

    Development of fusion power will require a fracture toughness database, derived largely from small specimen tests, closely integrated with methods to assess first wall and blanket structural integrities. A master curve-shift (MC-ΔT) method has been proposed as an engineering expedient to treat the effects of structural geometry, irradiation, loading rates and safety margins. However, a number of issues related to the MC-ΔT method remain to be resolved, including the universality of MC shapes. A new micromechanical model of fracture toughness in the cleavage transition regime is proposed that combines analytical representations of finite element analysis simulations of crack-tip stress fields with a local critical stress-critical stressed area (σ∗-A∗) fracture criterion. This model, has been successful in predicting geometry effects, as well as high loading rate and irradiation hardening-induced Charpy shifts. By incorporating a modest temperature dependence in σ∗(T), an inconsistency between model predictions and an observed universal-type MC shape is resolved.

  17. Phase Behavior and Significantly Enhanced Toughness in Polylactide Graft Copolymers

    NASA Astrophysics Data System (ADS)

    Robertson, Megan; Theryo, Grayce; Jing, Feng; Hillmyer, Marc

    2011-03-01

    Polylactide (PLA), a biodegradable polyester derived from plant sugars, is commercially available and used in a variety of applications ranging from serviceware to resorbable sutures. One limitation to diversifying the applications of the material is its inherent brittleness. Graft copolymers containing PLA arms and a rubbery aliphatic polymer backbone were synthesized by a combination of ring-opening metathesis and ring-opening transesterification polymerizations. The high degree of incompatibility between the arms and backbone resulted in microphase separation of the graft copolymer at increasingly low fractions of the backbone polymer, as evidenced by small-angle x-ray scattering. In graft copolymers with a rubbery content of only 5 wt percent, the tensile strain at break was observed to be as high as twenty times that of neat PLA. Studies are underway to provide insight into the critical polymer molecular parameters for enhanced toughness and the deformation mechanisms.

  18. 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.

  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. 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...

  1. 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...

  2. 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...

  3. 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...

  4. Proteoglycans and glycosaminoglycans improve toughness of biocompatible double network hydrogels.

    PubMed

    Zhao, Yu; Nakajima, Tasuku; Yang, Jing Jing; Kurokawa, Takayuki; Liu, Jian; Lu, Jishun; Mizumoto, Shuji; Sugahara, Kazuyuki; Kitamura, Nobuto; Yasuda, Kazunori; Daniels, A U D; Gong, Jian Ping

    2014-01-22

    Based on the molecular stent concept, a series of tough double-network hydrogels (St-DN gels) made from the components of proteoglycan aggregates - chondroitin sulfate proteoglycans (1), chondroitin sulfate (2), and sodium hyaluronate (3) - are successfully developed in combination with a neutral biocompatible polymer. This work demonstrates a promising method to create biopolymer-based tough hydrogels for biomedical applications. PMID:24431128

  5. Reactor Material Program Fracture Toughness of Type 304 Stainless Steel

    SciTech Connect

    Awadalla, N.G.

    2001-03-28

    This report describes the experimental procedure for Type 304 Stainless Steel fracture toughness measurements and the application of results. Typical toughness values are given based on the completed test program for the Reactor Materials Program (RMP). Test specimen size effects and limitations of the applicability in the fracture mechanics methodology are outlined as well as a brief discussion on irradiation effects.

  6. 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.

  7. Enhancing Scalability and Efficiency of the TOUGH2_MP for LinuxClusters

    SciTech Connect

    Zhang, Keni; Wu, Yu-Shu

    2006-04-17

    TOUGH2{_}MP, the parallel version TOUGH2 code, has been enhanced by implementing more efficient communication schemes. This enhancement is achieved through reducing the amount of small-size messages and the volume of large messages. The message exchange speed is further improved by using non-blocking communications for both linear and nonlinear iterations. In addition, we have modified the AZTEC parallel linear-equation solver to nonblocking communication. Through the improvement of code structuring and bug fixing, the new version code is now more stable, while demonstrating similar or even better nonlinear iteration converging speed than the original TOUGH2 code. As a result, the new version of TOUGH2{_}MP is improved significantly in its efficiency. In this paper, the scalability and efficiency of the parallel code are demonstrated by solving two large-scale problems. The testing results indicate that speedup of the code may depend on both problem size and complexity. In general, the code has excellent scalability in memory requirement as well as computing time.

  8. 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

  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. Fracture Toughness in Advanced Monolithic Ceramics - SEPB Versus SEVENB Methods

    NASA Technical Reports Server (NTRS)

    Choi, S. R.; Gyekenyesi, J. P.

    2005-01-01

    Fracture toughness of a total of 13 advanced monolithic ceramics including silicon nitrides, silicon carbide, aluminas, and glass ceramic was determined at ambient temperature by using both single edge precracked beam (SEPB) and single edge v-notched beam (SEVNB) methods. Relatively good agreement in fracture toughness between the two methods was observed for advanced ceramics with flat R-curves; whereas, poor agreement in fracture toughness was seen for materials with rising R-curves. The discrepancy in fracture toughness between the two methods was due to stable crack growth with crack closure forces acting in the wake region of cracks even in SEVNB test specimens. The effect of discrepancy in fracture toughness was analyzed in terms of microstructural feature (grain size and shape), toughening exponent, and stable crack growth determined using back-face strain gaging.

  11. 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.

  12. Laser notching ceramics for reliable fracture toughness testing

    DOE PAGESBeta

    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, 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

  13. Tough poly(arylene ether) thermoplastics as modifiers for bismaleimides

    NASA Technical Reports Server (NTRS)

    Stenzenberger, H. D.; Roemer, W.; Hergenrother, P. M.; Jensen, B. J.

    1989-01-01

    Several aspects of research on thermoplastics as toughness modifiers are discussed, including the contribution of the backbone chemistry and the concentration of the poly(arylene ether) thermoplastic to fracture toughness, influence of the molecular weight of the poly(arylene ether) thermoplastic on neat resin fracture toughness, and the morphology of the thermoplastic modified networks. The results show that fracture toughness of brittle bismaleimide resins can be improved significantly with poly(arylene ether) thermoplastic levels of 20 percent by weight, and that high molecular weight poly(arylene ether) based on bisphenol A provides the highest degree of toughening. Preliminary composite evaluation shows that improvements in neat resin toughness translate into carbon fabric composite.

  14. 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.

  15. High expression of peroxiredoxin 4 affects the survival time of colorectal cancer patients, but is not an independent unfavorable prognostic factor

    PubMed Central

    YI, NAN; XIAO, MING BING; NI, WEN KAI; JIANG, FENG; LU, CUI HUA; NI, RUN-ZHOU

    2014-01-01

    Peroxiredoxin 4 (Prx4) has a number of important biological functions, such as efficient antioxidant capacity and promotion of cell proliferation and differentiation. The purpose of this study was to investigate the expression and significance of Prx4 in human colorectal cancer (CRC). Quantitative polymerase chain reaction (qPCR) was performed to detect Prx4 in 8 freshly frozen specimens of CRC and their adjacent normal tissues. In addition, immunohistochemical analysis was performed to detect Prx4 in 59 specimens of CRC and 26 of adjacent normal tissues. The immunohistochemical and qPCR results demonstrated that the expressions of the Prx4 gene and protein were higher in CRC compared to those in the adjacent normal tissues. The expression intensity of the Prx4 protein was correlated with depth of invasion (P=0.001), lymph node metastasis (P=0.006) and Dukes’ classification (P=0.004) in CRC. The Kaplan-Meier survival curves revealed that high Prx4 expression was correlated with short survival time. However, the Cox proportional hazards regression analysis did not identify Prx4 as an independent prognostic marker for CRC (P>0.05). These results suggested that Prx4 may be associated with carcinogenesis and the development of CRC and it may be a prognostic marker for postoperative CRC patients. PMID:25054044

  16. 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

  17. Eriobotrya japonica hydrophilic extract modulates cytokines in normal tissues, in the tumor of Meth-A-fibrosarcoma bearing mice, and enhances their survival time

    PubMed Central

    2011-01-01

    Background Cytokines play a key role in the immune response to developing tumors, and therefore modulating their levels and actions provides innovative strategies for enhancing the activity of antigen presenting cells and polarizing towards T helper 1 type response within tumor microenvironment. One of these approaches could be the employment of plant extracts that have cytokine immunomodulation capabilities. Previously, we have shown that the Eriobotrya japonica hydrophilic extract (EJHE) induces proinflammatory cytokines in vitro and in vivo. Methods The present study explored the in vivo immunomodulatory effect on interferon-gamma (IFN-γ), interleukin-17 (IL-17), and transforming growth factor-beta 1 (TGF-β1) evoked by two water-extracts prepared from EJ leaves in the tissues of normal and Meth-A-fibrosarcoma bearing mice. Results Intraperitoneal (i.p.) administration of 10 μg of EJHE and EJHE-water residue (WR), prepared from butanol extraction, increased significantly IFN-γ production in the spleen (p < 0.01) and lung (p < 0.03) tissues at 6-48 hours and suppressed significantly TGF-β1 production levels (p < 0.001) in the spleen for as long as 48 hours. The latter responses, however, were not seen in Meth-A fibrosarcoma-bearing mice. On the contrary, triple i.p. injections, 24 hours apart; of 10 μg EJHE increased significantly IFN-γ production in the spleen (p < 0.02) while only EJHE-WR increased significantly IFN-γ, TGF-β1 and IL-17 (p < 0.03 - 0.005) production within the tumor microenvironment of Meth-A fibrosarcoma. In addition, the present work revealed a significant prolongation of survival time (median survival time 72 days vs. 27 days of control, p < 0.007) of mice inoculated i.p. with Meth-A cells followed by three times/week for eight weeks of i.p. administration of EJHE-WR. The latter prolonged survival effect was not seen with EJHE. Conclusions The therapeutic value of EJHE-WR as an anticancer agent merits further investigation of

  18. 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

  19. 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

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

    PubMed Central

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

    2014-01-01

    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 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 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 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, 1 ml/kg/day) or alendronate (ALN) at a clinical dose (0.2 mg/kg/day). Treatment duration ranged from 3 months to 3 years. 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 femoral

  1. Joint Analyses of Longitudinal and Time-to-Event Data in Research on Aging: Implications for Predicting Health and Survival

    PubMed Central

    Arbeev, Konstantin G.; Akushevich, Igor; Kulminski, Alexander M.; Ukraintseva, Svetlana V.; Yashin, Anatoliy I.

    2014-01-01

    Longitudinal data on aging, health, and longevity provide a wealth of information to investigate different aspects of the processes of aging and development of diseases leading to death. Statistical methods aimed at analyses of time-to-event data jointly with longitudinal measurements became known as the “joint models” (JM). An important point to consider in analyses of such data in the context of studies on aging, health, and longevity is how to incorporate knowledge and theories about mechanisms and regularities of aging-related changes that accumulate in the research field into respective analytic approaches. In the absence of specific observations of longitudinal dynamics of relevant biomarkers manifesting such mechanisms and regularities, traditional approaches have a rather limited utility to estimate respective parameters that can be meaningfully interpreted from the biological point of view. A conceptual analytic framework for these purposes, the stochastic process model of aging (SPM), has been recently developed in the biodemographic literature. It incorporates available knowledge about mechanisms of aging-related changes, which may be hidden in the individual longitudinal trajectories of physiological variables and this allows for analyzing their indirect impact on risks of diseases and death. Despite, essentially, serving similar purposes, JM and SPM developed in parallel in different disciplines with very limited cross-referencing. Although there were several publications separately reviewing these two approaches, there were no publications presenting both these approaches in some detail. Here, we overview both approaches jointly and provide some new modifications of SPM. We discuss the use of stochastic processes to capture biological variation and heterogeneity in longitudinal patterns and important and promising (but still largely underused) applications of JM and SPM to predictions of individual and population mortality and health

  2. 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.

  3. 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].

  4. 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.

  5. Using TOUGH2 to model capillary barriers

    SciTech Connect

    Webb, S.W.

    1998-09-01

    Ross (1990) developed an analytical relationship to calculate the diversion length of a tilted fine-over-coarse capillary barrier. Oldenburg and Pruess compared TOUGH2 simulation results to the diversion length predicted by Ross` formula using upstream and harmonic weighting. The results were mixed. The qualitative agreement is reasonable but the quantitative comparison is poor, especially for upstream weighting. The proximity of the water table to the fine-coarse interface at breakthrough has been proposed as a possible reason for the poor agreement. In the present study, the Oldenburg and Pruess problem is extended to address the water table issue. When the water table is sufficiently far away from the interface at breakthrough, good qualitative and quantitative agreement is obtained using upstream weighting.

  6. 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.

  7. Tough, processable simultaneous semi-interpenetrating polyimides

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1994-01-01

    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 materials. This simultaneous semi-IPN was prepared by mixing a thermosetting polyimide with a thermoplastic monomer precursor solution (NR150B2) 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.

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Sebastiani, M.; Johanns, K. E.; Herbert, E. G.; Carassiti, F.; Pharr, G. M.

    2015-06-01

    The fracture toughness of thin ceramic films is an important material property that plays a role in determining the in-service mechanical performance and adhesion of this important class of engineering materials. Unfortunately, measurement of 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 issues 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 upper portion of the pillar 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 behaviour. Cohesive finite element simulations are used for analysis and development of a simple relationship between the critical load at failure, pillar radius and fracture toughness for a given material. The main novel aspect of this work is that neither crack geometries nor crack sizes need to be measured post test. In addition, the residual stress can be measured at the same time with toughness, by comparison of the indentation results obtained on the stress-free pillars and the as-deposited film. The method is tested on three different hard coatings created by physical vapour deposition, namely 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.

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

    DOE PAGESBeta

    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 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Dynamic fracture toughness evaluation by measurement of CTOD

    SciTech Connect

    Sharpe, W.N. Jr.; Douglas, A.S.; Shapiro, J.M.

    1988-02-01

    Quantification of the dynamic fracture toughness of structural materials is essential to a wide range of problems-from nuclear accidents to ordnance applications. However, the difficulties associated with accurate measurements of crack under dynamic loading are considerable. Thus there are no standardized procedures and few reliable results. A systematic study of the dynamic fracture toughness of SAE-01 tool steel, 4340 and HY100 steels, and a tungsten are described using the Interferometric Strain/Displacement Gage (ISDG) system which has very high frequency resolution. The ISDG system is used to measure the crack tip opening displacement (CTOD) 100 microns behind a fatigue crack tip in a three-point bend specimen. Static measurements on similar specimens serve to calibrate the method and ensure consistency with the accepted procedures for static fracture toughness testing. Finite element analyses are used to obtain full field information at the point of initiation and to assess the material characteristics which lead to changes in toughness with loading rate. The major advantage of the method is that information is obtained very close to the crack tip, so that stress wave loading effects are accounted for. Results show that 4340 steel, which is strain-rate insensitive, has no significant change in toughness with loading rate. Measurable toughness dependence on loading rate is found for HY-100 and tungsten, which are approximately 15 percent tougher under dynamic conditions. The SAE-01 tool steel shows a significant increase (50 percent) in fracture toughness for dynamic over static loading.

  17. A workflow for handling heterogeneous 3D models with the TOUGH2 family of codes: Applications to numerical modeling of CO 2 geological storage

    NASA Astrophysics Data System (ADS)

    Audigane, Pascal; Chiaberge, Christophe; Mathurin, Frédéric; Lions, Julie; Picot-Colbeaux, Géraldine

    2011-04-01

    This paper is addressed to the TOUGH2 user community. It presents a new tool for handling simulations run with the TOUGH2 code with specific application to CO 2 geological storage. This tool is composed of separate FORTRAN subroutines (or modules) that can be run independently, using input and output files in ASCII format for TOUGH2. These modules have been developed specifically for modeling of carbon dioxide geological storage and their use with TOUGH2 and the Equation of State module ECO2N, dedicated to CO 2-water-salt mixture systems, with TOUGHREACT, which is an adaptation of TOUGH2 with ECO2N and geochemical fluid-rock interactions, and with TOUGH2 and the EOS7C module dedicated to CO 2-CH 4 gas mixture is described. The objective is to save time for the pre-processing, execution and visualization of complex geometry for geological system representation. The workflow is rapid and user-friendly and future implementation to other TOUGH2 EOS modules for other contexts (e.g. nuclear waste disposal, geothermal production) is straightforward. Three examples are shown for validation: (i) leakage of CO 2 up through an abandoned well; (ii) 3D reactive transport modeling of CO 2 in a sandy aquifer formation in the Sleipner gas Field, (North Sea, Norway); and (iii) an estimation of enhanced gas recovery technology using CO 2 as the injected and stored gas to produce methane in the K12B Gas Field (North Sea, Denmark).

  18. The Use of Doublers in Delamination Toughness Testing

    NASA Technical Reports Server (NTRS)

    Reeder, James R.; Demarco, Kevin; Whitley, Karen S.

    2002-01-01

    In this paper, the data reduction equations for common delamination toughness tests are rederived for use with specimens which have bonded doublers. The common toughness tests considered here are the double cantilever beam (DCB) for mode I toughness; the end notch flexure (3ENF) and 4 point ENF (4ENF) for mode II toughness; and the mixed mode bending (MMB) test for testing under combined mode I and mode II loading. Because the addition of the doublers changes the bending stiffness of the specimens, these data reduction equations may need to be corrected. Doublers were added to the delamination test specimens to solve a premature failure problem. Delamination toughness is normally tested using a beam with an imbedded insert so that one end of the specimen is split into two arms. If the specimen is too thin, or if the toughness of the material is too high, an arm of the specimen may fail in bending before the delamination grows. When this occurs, the toughness of the material cannot be determined. To delay the bending failure so that delamination growth occurs, doubler plates were bonded to both top and bottom surfaces of the specimen. A doubler parameter, beta, which describes how much the use of doubler plates changed the ratio of full thickness to delaminated bending stiffnesses, was defined. When changes to the data reduction equations were required, the changes were minor when written in terms of the beta parameter. The doubler plate technique was demonstrated by measuring the mixed-mode fracture toughness of a carbon-carbon composite using test specimens which would otherwise have failed before delamination growth occurred. The doubler plate technique may solve several problems that can be encountered when testing delamination fracture toughness.

  19. Tough Times for Medicinal Chemists: Are We to Blame?

    PubMed Central

    2013-01-01

    In the United States, medicinal chemists continue to face job insecurity and high rates of unemployment. The situation is unlikely to improve in the near future. Is there a light at the end of the tunnel? Is there anything we can do to revitalize our community? The answer may be right in front of us. PMID:24900676

  20. 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…

  1. Being Relevant in Tough Times: TRIUMF's Five-Year Plan

    ScienceCinema

    Tim, Mayer [TRIUMF

    2010-01-08

    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.

  2. In Tough Times, Some Colleges Find Conservative Management Pays Off.

    ERIC Educational Resources Information Center

    McMillen, Liz; Nicklin, Julie L.

    1992-01-01

    The successful conservative administrative strategies of four private colleges (Claremont McKenna College, California; Connecticut College; Livingstone College, North Carolina; Northwestern University, Illinois) in a climate of widespread institutional cutbacks are described. They include investment, avoidance of administrative "bloat," tough…

  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. Breast cancer in tough economic times: disruptive technology emerging

    NASA Astrophysics Data System (ADS)

    Bretz, Phillip; Lynch, Richard

    2012-06-01

    The objective of this study was to investigate the efficacy of melding three emerging technologies: Pharmacogenomics, Modified Military Digital Infrared and Halo to establish their capability in diagnosing ultra-small breast cancers as well as other cancers. Mammography, ultrasound and MRI technologies have been available for over forty years, however, there is still no uniform utilization by women, costs continue to escalate and problems persist like high false positive rates for MRI and high false negative rates for mammography. Of the first 500 IR patients, 499 were female and 1 male. Of 550 OncoVue patients, 129 opted to undergo IR. A total of 19 were lost to follow-up. Patients who were negative on IR: 419/500 (84%). Of these, 63/419 went to biopsy because of findings of other diagnostic modalities. Of these 61/63 with negative IR had a negative biopsy. Of two missed, one was the fault of the investigator but was included. In this series 2/500 were false negative (0.4%). The sensitivity was 96% and the specificity was 79%. In total, 46 cancers were identified including five outside the breast (e.g. 2 lung cancers). A total of 92 MRIs were done and in 71/92 patients IR and MRI agreed. Using these three modalities the smallest cancer found was a 4 mm invasive cancer. The study demonstrated that these diagnostic techniques can dramatically lower cost and provide results at least as good as the older paradigms. Further research and a multicenter clinical trial are necessary to shift the paradigm of breast cancer diagnosis and treatment.

  5. 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…

  6. Being Relevant in Tough Times: TRIUMF's Five-Year Plan

    SciTech Connect

    Mayer, Tim

    2009-05-27

    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.

  7. Being Relevant in Tough Times: TRIUMF's Five-Year Plan

    SciTech Connect

    Tim, Mayer

    2009-05-27

    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. Staying Focused during Tough Economic Times: Consolidating Our Research Base

    ERIC Educational Resources Information Center

    Allen, Melissa

    2010-01-01

    Today school library media specialists operate in an environment of daily challenges and controversies. "No Child Left Behind" established mandates that all educators are scrambling to meet. No matter how people feel about the way the legislation is being carried out, it is difficult to argue against its purpose--that all educators must find ways…

  9. 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…

  10. 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…

  11. 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.

  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. Surviving Cancer

    MedlinePlus

    ... Watch the video to learn more about these breast cancer survivors. To enlarge the video, click the brackets in the lower right-hand corner. To reduce the video, press the Escape (Esc) button on your keyboard.) Age and Health May Affect Survival A person's age, and more importantly his or ...

  14. Beyond Survival

    ERIC Educational Resources Information Center

    Steffenson, Dave

    1975-01-01

    The author argues that environmentalists need to realize that the present ecological crisis is essentially a value crisis, not merely a fight for survival alone. He envisions a complete value change for the human population and advocates the incorporation of value strategies into all environmental education programs immediately. (MA)

  15. Survival Outcomes for Patients with Stage IVB Vulvar Cancer with Grossly Positive Pelvic Lymph Nodes: Time to Reconsider the FIGO Staging System?

    PubMed Central

    Thaker, Nikhil G.; Klopp, Ann H.; Jhingran, Anuja; Frumovitz, Michael; Iyer, Revathy B.; Eifel, Patricia J.

    2015-01-01

    Objective To evaluate treatment outcomes for patients with vulvar cancer with grossly positive pelvic lymph nodes (PLNs). Methods From a database of 516 patients with vulvar cancer, we identified patients with grossly positive PLNs without distant metastasis at initial diagnosis. We identified 20 patients with grossly positive PLNs; inclusion criteria included PLN 1.5 cm or larger in short axis dimension on CT/MRI (n=11), FDG-avid PLN on PET/CT (n=3), or biopsy-proven PLN disease (n=6). Ten patients were treated with chemoradiation (CRT) therapy, 4 with RT alone, and 6 with various combinations of surgery, RT or CRT. Median follow-up time for patients who had not died of cancer was 47 months (range, 4-228 months). Results Mean primary vulvar tumor size was 6.4 cm; 12 patients presented with 2009 AJCC T2 and 8 with T3 disease. All patients had grossly positive inguinal nodes, and the mean inguinal nodal diameter was 2.8 cm. The 5-year overall survival and disease specific survival rates were 43% and 48%, respectively. Eleven patients had recurrences, some at multiple sites. There were 9 recurrences in the vulva, but no isolated nodal recurrences. Four patients developed distant metastasis within 6 months of starting radiation therapy. Conclusions Aggressive locoregional treatment can lead to favorable outcomes for many patients with grossly involved PLNs that is comparable to that of grossly involved inguinal nodes only. We recommend modification of the FIGO stage IVB classification to more accurately reflect the relatively favorable prognosis of patients with PLN involvement. PMID:25524458

  16. Molecularly engineered dual-crosslinked hydrogel with ultrahigh mechanical strength, toughness, and good self-recovery.

    PubMed

    Lin, Peng; Ma, Shuanhong; Wang, Xiaolong; Zhou, Feng

    2015-03-25

    A molecularly engineered dual-crosslinked hydrogel with extraordinary mechanical properties is reported. The hydrogel network is formed with both chemical crosslinking and acrylic-Fe(III) coordination; these, respectively, impart the elasticity and enhance the mechanical properties by effectively dissipating energy. The optimal hydrogel achieves a tensile stress of ca. 6 MPa at a large elongation ratio (>7 times), a toughness of 27 MJ m(-3) , and a stiffness of ca. 2 MPa, and has good self-recovery properties. PMID:25677412

  17. Effect of Aging Treatment on Impact Toughness and Corrosion Resistance of Super Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Hwan; Oh, Eun-Ji; Lee, Byung-Chan; Kang, Chang-Yong

    2016-01-01

    The effect of aging time on impact toughness and corrosion resistance of 25%Cr-7%Ni-2%Mo-4%W-0.2%N super duplex stainless steel from the viewpoint of intermetallic secondary phase variation was investigated with scanning electron microscopic observation with energy-dispersive x-ray spectroscopic analysis and transmission electron microscopy. The results clarified that R-phase is precipitated not only at the interface of ferrite and austenite but inside the ferrite at an initial stage of aging and then transformed into σ-phase from an aging time of 1 h, while the ferrite phase decomposed into γ2 and σ-phase with increase of aging time. This variation of the phases led to decrease of its impact toughness, and specifically, the R-phase was proved to be predominant in the degradation of the impact toughness at the initial stage of the aging. Additionally, these secondary phases led to deterioration of corrosion resistance because of Cr depletion.

  18. 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

  19. Southern States Lagging in Tough Smoking Bans, CDC Says

    MedlinePlus

    ... 159529.html Southern States Lagging in Tough Smoking Bans, CDC Says Only 6 in 10 Americans covered ... federal government report says. This type of law bans smoking in all indoor areas of workplaces, restaurants ...

  20. Southern States Lagging in Tough Smoking Bans, CDC Says

    MedlinePlus

    ... fullstory_159529.html Southern States Lagging in Tough Smoking Bans, CDC Says Only 6 in 10 Americans covered by state or local laws banning smoking in public places To use the sharing features ...

  1. Tough Economy, Alcohol Fuels Suicide Risk in Men

    MedlinePlus

    ... html Tough Economy, Alcohol Fuels Suicide Risk in Men: Study But similar link not seen for women ... drinking may fuel the risk of suicide among men when the economy is sinking, new research suggests. ...

  2. Night Shift Work May Be Tough on A Woman's Heart

    MedlinePlus

    ... medlineplus.gov/news/fullstory_158508.html Night Shift Work May Be Tough on a Woman's Heart But ... TUESDAY, April 26, 2016 (HealthDay News) -- Women who work rotating night shifts may face a slightly increased ...

  3. Physical hydrogels composed of polyampholytes demonstrate high toughness and viscoelasticity

    NASA Astrophysics Data System (ADS)

    Sun, Tao Lin; Kurokawa, Takayuki; Kuroda, Shinya; Ihsan, Abu Bin; Akasaki, Taigo; Sato, Koshiro; Haque, Md. Anamul; Nakajima, Tasuku; Gong, Jian Ping

    2013-10-01

    Hydrogels attract great attention as biomaterials as a result of their soft and wet nature, similar to that of biological tissues. Recent inventions of several tough hydrogels show their potential as structural biomaterials, such as cartilage. Any given application, however, requires a combination of mechanical properties including stiffness, strength, toughness, damping, fatigue resistance and self-healing, along with biocompatibility. This combination is rarely realized. Here, we report that polyampholytes, polymers bearing randomly dispersed cationic and anionic repeat groups, form tough and viscoelastic hydrogels with multiple mechanical properties. The randomness makes ionic bonds of a wide distribution of strength. The strong bonds serve as permanent crosslinks, imparting elasticity, whereas the weak bonds reversibly break and re-form, dissipating energy. These physical hydrogels of supramolecular structure can be tuned to change multiple mechanical properties over wide ranges by using diverse ionic combinations. This polyampholyte approach is synthetically simple and dramatically increases the choice of tough hydrogels for applications.

  4. Link Between Money Woes, Domestic Abuse Tough to Untangle

    MedlinePlus

    ... fullstory_158582.html Link Between Money Woes, Domestic Abuse Tough to Untangle Researchers trying to determine if ... April 29, 2016 (HealthDay News) -- Money problems and domestic violence appear to be linked, but it's not clear ...

  5. Posttreatment prostatic-specific antigen doubling time as a surrogate endpoint for prostate cancer-specific survival: An analysis of Radiation Therapy Oncology Group Protocol 92-02

    SciTech Connect

    Valicenti, Richard K. . E-mail: Richard.Valicenti@mail.tju.edu; DeSilvio, Michelle; Hanks, Gerald E.; Porter, Arthur; Brereton, Harmar; Rosenthal, Seth A.; Shipley, William U.; Sandler, Howard M.

    2006-11-15

    Purpose: We evaluated whether posttreatment prostatic-specific antigen doubling time (PSADT) was predictive of prostate cancer mortality by testing the Prentice requirements for a surrogate endpoint. Methods and Materials: We analyzed posttreatment PSA measurements in a cohort of 1,514 men with localized prostate cancer (T2c-4 and PSA level <150 ng/mL), treated and monitored prospectively on Radiation Therapy Oncology Group Protocol 92-02. From June 1992 to April 1995, men were randomized to neoadjuvant androgen deprivation and 65-70 Gy of radiation therapy (n = 761), or in combination with 24 months of adjuvant androgen deprivation (n = 753). Using an adjusted Cox proportional hazards model, we tested if PSADT was prognostic and independent of randomized treatment in this cohort. The endpoints were time to PSADT (assuming first-order kinetics for a minimum of 3 rising PSA measurements) and cancer-specific survival (CSS). Results: After a median follow-up time of 5.9 years, randomized treatment was a significant predictor for CSS (p{sub Cox} = 0.002), PSADT <6 months (p{sub Cox} < 0.001), PSADT <9 months (p{sub Cox} < 0.001), and PSADT <12 months (p{sub Cox} < 0.001) but not for PSADT <3 (p{sub Cox} = 0.4). The significant posttreatment PSADTs were also significant predictors of CSS (p{sub Cox}< 0.001). After adjusting for T stage, Gleason score and PSA, all of Prentice's requirements were not met, indicating that the effect of PSADT on CSS was not independent of the randomized treatment. Conclusions: Prostatic specific antigen doubling time is significantly associated with CSS, but did not meet all of Prentice's requirements for a surrogate endpoint of CSS. Thus, the risk of dying of prostate cancer is not fully explained by PSADT.

  6. 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. Am. J. Hematol. 91:426-429, 2016. © 2016 Wiley Periodicals, Inc. PMID:26820493

  7. Correlations between ultrasonic and fracture toughness factors in metallic materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

    A heuristic mathematical basis was proposed for the experimental correlations found between ultrasonic propagation factors and fracture toughness factors in metallic materials. A crack extension model was developed wherein spontaneous stress (elastic) waves produced during microcracking are instrumental in promoting the onset of unstable crack extension. Material microstructural factors involved in the process are measurable by ultrasonic probing. Experimental results indicate that ultrasonic attenuation and velocity measurements will produce significant correlations with fracture toughness properties and also yield strength.

  8. Correlations between ultrasonic and fracture toughness factors in metallic materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

    A heuristic mathematical basis is proposed for the experimental correlations found between ultrasonic propagation factors and fracture toughness factors in metallic materials. A crack extension model is proposed wherein spontaneous stress (elastic) waves produced during microcracking are instrumental in promoting the onset of unstable crack extension. Material microstructural factors involved in this process are measurable by ultrasonic probing. Experimental results indicate that ultrasonic attenuation and velocity measurements will produce significant correlations with fracture toughness properties and also yield strength.

  9. Interfacial fracture toughness of alumina/niobium systems

    SciTech Connect

    Stout, M.G. ); O'Dowd, N.P.; Shih, C.F. . Div. of Engineering)

    1991-01-01

    The interfacial fracture toughness of an alumina/niobium composite has been measured as a function of phase angle. The interface was formed by solid-state bonding bulk Coor's AD-999 fine-grain alumina with a commercial purity niobium at 1600{degrees}C for 0.5 hr under a pressure of 10.5 MPa. The alumina/niobium system has a number of features which makes it ideal for an investigation of interfacial fracture toughness. From HREM data we estimate that the width of the interface is no more than 10 atomic planes. Furthermore the thermal expansion coefficients of the two materials differ by less than 5% so residual stresses due to the bonding process are small. Using symmetric and asymmetric four point bend specimens we have measured the fracture toughness of homogenous alumina and that of the alumina/niobium bimaterial in combinations of in-plane shear and tension. The fracture toughness of the homogenous alumina is relatively insensitive to the loading phase. The measured fracture toughness K{sub c} of the interface, however, depended strongly on phase angle. We were unable to obtain valid alumina/niobium interfacial toughness data at negative phase angles as the fracture initiates in the alumina and not at the interface. In symmetric bending at a phase angle {approx}5{degrees}, we measured a nominal interface toughness of 4.0 MPa{radical}m, comparable to the homogeneous alumina. We found that the toughness increased with loading phase angle to a value of K{sub c} {approx} 9 MPa{radical}m at a phase between 25{degrees} and 40{degrees}. Preliminary calculations and experiments suggest that this effect is due to an asymmetric stress distribution, with respect to the interface, and plastic deformation in the niobium. 12 refs., 9 figs., 1 tab.

  10. Fracture toughness of polybutadiene at cryogenic temperatures. Technical report

    SciTech Connect

    Burford, R.P.

    1983-04-01

    An estimate of fracture toughness of crosslined polybutadiene rubber at -180 degrees C has been made using the double torsin method. By using suitable specimen dimensions and strain rates, controlled crack propagatin can be achieved, together with a constant compliance to crack length ratio. Strain energy release rated for this polymer, crosslinked with either dicumyl peroxide or sulphur, were found to be an order of magnitude higher than for linear, glassy thermoplastics. Crazing is considered to contribute to the high toughness observed.

  11. 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.

  12. 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.

  13. The shear fracture toughness, KIIc, of graphite

    DOE PAGESBeta

    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

  14. 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…

  15. 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

  16. Fracture Toughness Properties of Gd123 Superconducting Bulks

    NASA Astrophysics Data System (ADS)

    Fujimoto, H.; Murakami, A.

    Fracture toughness properties of melt growth GdBa2Cu3Ox (Gd123) large single domain superconducting bulks with Ag2O of 10 wt% and Pt of 0.5 wt%; 45 mm in diameter and 25 mm in thickness with low void density were evaluated at 77 K through flexural tests of specimens cut from the bulks, and compared to those of a conventional Gd123 with voids. The densified Gd123 bulks were prepared with a seeding and temperature gradient method; first melt processed in oxygen, then crystal growth in air; two-step regulated atmosphere heat treatment. The plane strain fracture toughness, KIC was obtained by the three point flexure test of the specimens with through precrack, referring to the single edge pre-cracked beam (SEPB) method, according to the JIS-R-1607, Testing Methods for Fracture Toughness of High Performance Ceramics. The results show that the fracture toughness of the densified Gd123 bulk with low void density was higher than that of the standard Gd123 bulk with voids, as well as the flexural strength previously reported. We also compared the fracture toughness of as-grown bulks with that of annealed bulks. The relation between the microstructure and the fracture toughness of the Gd123 bulk was clearly shown.

  17. A parametric study of fracture toughness of fibrous composite materials

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1987-01-01

    Impacts to fibrous composite laminates by objects with low velocities can break fibers giving crack-like damage. The damage may not extend completely through a thick laminate. The tension strength of these damage laminates is reduced much like that of cracked metals. The fracture toughness depends on fiber and matrix properties, fiber orientations, and stacking sequence. Accordingly, a parametric study was made to determine how fiber and matrix properties and fiber orientations affect fracture toughness and notch sensitivity. The values of fracture toughness were predicted from the elastic constants of the laminate and the failing strain of the fibers using a general fracture toughness parameter developed previously. For a variety of laminates, values of fracture toughness from tests of center-cracked specimens and values of residual strength from tests of thick laminates with surface cracks were compared to the predictions to give credibility to the study. In contrast to the usual behavior of metals, it is shown that both ultimate tensile strength and fracture toughness of composites can be increased without increasing notch sensitivity.

  18. Self-concept organisation and mental toughness in sport.

    PubMed

    Meggs, Jennifer; Ditzfeld, Christopher; Golby, Jim

    2014-01-01

    The present study examines the relationship between individual differences in evaluative self-organisation and mental toughness in sport, proposing that motivation and emotional resiliency (facets of mental toughness) stem from differences in core self. A cross-sectional assessment of 105 athletes competing at a range of performance levels took part in an online study including measures of self-reported mental toughness (Sport Mental Toughness Questionnaire; Sheard, M., Golby, J., & van Wersch, A. (2009). Progress towards construct validation of the Sports Mental Toughness Questionnaire (SMTQ). European Journal of Psychological Assessment, 25(3), 186-193. doi:10.1027/1015-5759.25.3.186) and self-organisation (self-descriptive attribute task; Showers, C. J. (2002). Integration and compartmentalisation: A model of self-structure and self-change. In D. Cervone & W. Mischel (Eds.), Advances in personality science (pp. 271-291). New York, NY: Guilford Press). As predicted, global mental toughness was associated with self-concept positivity, which was particularly high in individuals with positive-integrative self-organisation (individuals who distribute positive and negative self-attributes evenly across multiple selves). Specifically, positive integration was associated with constancy (commitment to goal achievement despite obstacles and the potential for failure), which extends presumably from positive integratives' emotional stability and drive to resolve negative self-beliefs. PMID:23968218

  19. 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.

  20. The stability of precipitated austenite and the toughness of 9Ni steel

    NASA Astrophysics Data System (ADS)

    Fultz, B.; Kim, J. I.; Kim, Y. H.; Kim, H. J.; Fior, G. O.; Morris, J. W.

    1985-12-01

    A correlation was confirmed between the good low temperature Charpy toughness of 9Ni steel and the stability of its precipitated austenite against the martensitic transformation. Changes in the microstructure during isothermal tempering were studied in detail. The austenite/martensite interface is originally quite coherent over ˜100 A distances. With further tempering, however, the dislocation structure at the austenite/martensite interface changes, and this change may be related to the increased instability of the austenite particles. The reduction in austenite carbon concentration does not seem large enough to account for the large reduction in austenite stability with tempering time. The strains inherent to the transformation of austenite particles create dislocation structures in the tempered martensite. The large deterioration of the Charpy toughness of overtempered material is attributed, in part, to these dislocation structures.

  1. Fracture toughness of hydroxyapatite/mica composite, packed hydroxyapatite, alumina ceramics, silicon nitride and -carbide.

    PubMed

    Nordström, E G; Yokobori, A T; Yokobori, T; Aizawa, Y

    1998-01-01

    By using the fracture toughness estimation method based on two-dimensional map, it was found that the ductility of the high porosity hydroxyapatite/mice composite was comparable with silicon carbide. It was measured to be higher than that of packed hydroxyapatite. Alumina ceramics with more than 96% aluminium oxide showed a higher fracture toughness than the composite material. When bending strength was compared, the strength of the composite was two or three times lower than that of packed hydroxyapatite and much lower than the other studied materials. The composite material showed high porosity, which in turn gives it a lower bending strength. However, the high porosity is more favourable for biocompatibility. PMID:9713684

  2. 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

  3. 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.

  4. Sleep restriction reduces the survival time and aggravates the neurological dysfunction and memory impairments in an animal model of cerebral hypoperfusion.

    PubMed

    Kim, Lenise Jihe; Coelho, Fernando Morgadinho; Araujo, Paula; Tedesco, Roberto Carlos; Souza, Rodrigo Barbosa; Tufik, Sergio; Andersen, Monica Levy

    2016-08-01

    Cerebral blood flow is associated with the cerebrovascular prognosis. Sleep restriction (SR) may be a limiting factor of the prognosis after a cerebrovascular event, impairing the neurological recovery. We aimed to investigate the effects of SR on mortality rate and on behavioral and histological parameters of animals submitted to permanent cerebral hypoperfusion. Sixty male Wistar rats were distributed in 4 groups, according to the protocol of common carotid artery occlusion (CCAO) and SR: nSR+nCCAO, SR+nCCAO, nSR+CCAO, and SR+CCAO. The groups SR+nCCAO and SR+CCAO were submitted to SR during 10 days. The cerebral hypoperfusion was induced by the permanent CCAO. Neurological function and memory were assessed over 14 days of cerebral hypoperfusion. Analysis of neuropathological alterations were performed in the CA1 region of hippocampus. The mortality rate was 40% in the nSR+CCAO and SR+CCAO groups. SR significantly reduced the survival time of animals submitted to CCAO. After 7 and 14 days of cerebral hypoperfusion, 11% and 33% of the nSR+CCAO and SR+CCAO animals showed severe neurological dysfunction, respectively. A significant association between a high frequency of memory impairments with the group SR+CCAO was observed. The neuropathological alterations in CA1 region of hippocampus were similar among the groups. SR potentiates the negative effects of cerebral hypoperfusion conditions, suggesting that SR could be a factor associated with a worse prognosis after a cerebrovascular event. PMID:27174002

  5. 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

  6. 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

  7. Density of tumor-infiltrating lymphocytes correlates with extent of brain edema and overall survival time in patients with brain metastases

    PubMed Central

    Berghoff, Anna S; Fuchs, Elisabeth; Ricken, Gerda; Mlecnik, Bernhard; Bindea, Gabriela; Spanberger, Thomas; Hackl, Monika; Widhalm, Georg; Dieckmann, Karin; Prayer, Daniela; Bilocq, Amelie; Heinzl, Harald; Zielinski, Christoph; Bartsch, Rupert; Birner, Peter; Galon, Jerome; Preusser, Matthias

    2016-01-01

    The immune microenvironment of the brain differs from that of other organs and the role of tumor-infiltrating lymphocytes (TILs) in brain metastases (BM), one of the most common and devastating complication of cancer, is unclear. We investigated TIL subsets and their prognostic impact in 116 BM specimens using immunohistochemistry for CD3, CD8, CD45RO, FOXP3, PD1 and PD-L1. The Immunoscore was calculated as published previously. Overall, we found TIL infiltration in 115/116 (99.1%) BM specimens. PD-L1 expression was evident in 19/67 (28.4%) BM specimens and showed no correlation with TIL density (p > 0.05). TIL density was not associated with corticosteroid administration (p > 0.05). A significant difference in infiltration density according to TIL subtype was present (p < 0.001; Chi Square); high infiltration was most frequently observed for CD3+ TILs (95/116; 81.9%) and least frequently for PD1+ TILs (18/116; 15.5%; p < 0.001). Highest TIL density was observed in melanoma, followed by renal cell cancer and lung cancer BM (p < 0.001). The density of CD8+ TILs correlated positively with the extent of peritumoral edema seen on pre-operative magnetic resonance imaging (p = 0.031). The density of CD3+ (15 vs. 6 mo; p = 0.015), CD8+ (15 vs. 11 mo; p = 0.030) and CD45RO+ TILs (18 vs. 8 mo; p = 0.006) showed a positive correlation with favorable median OS times. Immunoscore showed significant correlation with survival prognosis (27 vs. 10 mo; p < 0.001). The prognostic impact of Immunoscore was independent from established prognostic parameters at multivariable analysis (HR 0.612, p < 0.001). In conclusion, our data indicate that dense TILs infiltrates are common in BM and correlate with the amount of peritumoral brain edema and survival prognosis, thus identifying the immune system as potential biomarker for cancer patients with CNS affection. Further studies are needed to substantiate our findings. PMID:26942067

  8. 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

  9. SURVIV for survival analysis of mRNA isoform variation.

    PubMed

    Shen, Shihao; Wang, Yuanyuan; Wang, Chengyang; Wu, Ying Nian; Xing, Yi

    2016-01-01

    The rapid accumulation of clinical RNA-seq data sets has provided the opportunity to associate mRNA isoform variations to clinical outcomes. Here we report a statistical method SURVIV (Survival analysis of mRNA Isoform Variation), designed for identifying mRNA isoform variation associated with patient survival time. A unique feature and major strength of SURVIV is that it models the measurement uncertainty of mRNA isoform ratio in RNA-seq data. Simulation studies suggest that SURVIV outperforms the conventional Cox regression survival analysis, especially for data sets with modest sequencing depth. We applied SURVIV to TCGA RNA-seq data of invasive ductal carcinoma as well as five additional cancer types. Alternative splicing-based survival predictors consistently outperform gene expression-based survival predictors, and the integration of clinical, gene expression and alternative splicing profiles leads to the best survival prediction. We anticipate that SURVIV will have broad utilities for analysing diverse types of mRNA isoform variation in large-scale clinical RNA-seq projects. PMID:27279334

  10. SURVIV for survival analysis of mRNA isoform variation

    PubMed Central

    Shen, Shihao; Wang, Yuanyuan; Wang, Chengyang; Wu, Ying Nian; Xing, Yi

    2016-01-01

    The rapid accumulation of clinical RNA-seq data sets has provided the opportunity to associate mRNA isoform variations to clinical outcomes. Here we report a statistical method SURVIV (Survival analysis of mRNA Isoform Variation), designed for identifying mRNA isoform variation associated with patient survival time. A unique feature and major strength of SURVIV is that it models the measurement uncertainty of mRNA isoform ratio in RNA-seq data. Simulation studies suggest that SURVIV outperforms the conventional Cox regression survival analysis, especially for data sets with modest sequencing depth. We applied SURVIV to TCGA RNA-seq data of invasive ductal carcinoma as well as five additional cancer types. Alternative splicing-based survival predictors consistently outperform gene expression-based survival predictors, and the integration of clinical, gene expression and alternative splicing profiles leads to the best survival prediction. We anticipate that SURVIV will have broad utilities for analysing diverse types of mRNA isoform variation in large-scale clinical RNA-seq projects. PMID:27279334

  11. 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.

  12. Liquid crystal self-templating approach to ultrastrong and tough biomimic composites

    PubMed Central

    Hu, Xiaozhen; Xu, Zhen; Liu, Zheng; Gao, Chao

    2013-01-01

    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). PMID:23918042

  13. 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.

  14. The Effect of Curing Temperature on the Fracture Toughness of Fiberglass Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Ryan, Thomas J.

    The curing reaction in a thermoset polymer matrix composite is often accelerated by the addition of heat in an oven or autoclave. The heat added increases the rate of the polymerization reaction and cross-linking in the material. The cure cycle used (temperature, pressure and time) can therefore alter the final material properties. This research focuses on how the curing temperature (250, 275, 300 °F) affects the yield strength and the mode I interlaminar fracture toughness, GI, of a unidirectional S-2 glass epoxy composite. The test method that was used for the tension test was ASTM D3039 and the test method for the mode I interlaminar fracture toughness, the double cantilever beam (DCB) test, was ASTM D5528. The DCB specimens were fabricated with a non-adhesive insert at the midplane of the composite that serves as the initiatior of the delamination. Opening forces were then applied to the specimen, causing the crack propagation. The results show that increasing the cure temperature by 50 °F increased the tensile strength by 10% (86.54 - 94.73 ksi) and decreased the fracture toughness 20% (506.23 - 381.31 J/m 2). Thus, the curing temperature can cause a trade-off between these two properties, which means that the curing cycle will need to be altered based on the intended use and the required material properties.

  15. Grain growth and fracture toughness of fine-grained silicon carbide ceramics

    SciTech Connect

    Kim, Y.W.; Mitomo, Mamoru; Hirotsuru, Hideki

    1995-11-01

    Fine-grained silicon carbide ceramics with an average grain size of 0.11 {micro}m were liquid-phase sintered from fine {beta}-SiC powder by hot pressing. The hot-pressed materials were subsequently annealed to enhance grain growth. The diameters and aspect ratios of grains in the hot-pressed and annealed materials were measured on polished and etched surfaces. The bimodal grain size distribution in annealed materials was obtained at 1,850 C without appreciable phase transformation. The average diameter and average aspect ratio increased with annealing time. The fracture toughness of a fine-grained silicon carbide ceramic determined by the Vickers indentation method was 1.9 MPa {center_dot} m{sup 1/2}. The fracture toughness increased to 6.1 MPa {center_dot} m{sup 1/2} after grain growth by annealing at 1,850 C for 12 h. Higher fracture toughness of annealed materials is due to bridging by elongated grains as evidenced by R-curve-like behavior.

  16. 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.

  17. Design and Analysis of Salmonid Tagging Studies in the Columbia Basin : Evaluating Wetland Restoration Projects in the Columbia River Estuary using Hydroacoustic Telemetry Arrays to Estimate Movement, Survival, and Residence Times of Juvenile Salmonids, Volume XXII (22).

    SciTech Connect

    Perry, Russell W.; Skalski, John R.

    2008-08-01

    Wetlands in the Columbia River estuary are actively being restored by reconnecting these habitats to the estuary, making more wetland habitats available to rearing and migrating juvenile salmon. Concurrently, thousands of acoustically tagged juvenile salmonids are released into the Columbia River to estimate their survival as they migrate through the estuary. Here, we develop a release-recapture model that makes use of these tagged fish to measure the success of wetland restoration projects in terms of their contribution to populations of juvenile salmon. Specifically, our model estimates the fraction of the population that enter the wetland, survival within the wetland, and the mean residence time of fish within the wetland. Furthermore, survival in mainstem Columbia River downstream of the wetland can be compared between fish that remained the mainstem and entered the wetland. These conditional survival estimates provide a means of testing whether the wetland improves the subsequent survival of juvenile salmon by fostering growth or improving their condition. Implementing such a study requires little additional cost because it takes advantage of fish already released to estimate survival through the estuary. Thus, such a study extracts the maximum information at minimum cost from research projects that typically cost millions of dollars annually.

  18. The Option for Survival

    ERIC Educational Resources Information Center

    Berry, R. Stephen

    1971-01-01

    Suggests formula for survival that takes a thermodynamic view which holds that we must recycle waste while the thermodynamic potential still is moderately high. Otherwise they are lost, as helium is lost when it leaves Earth's atmosphere and goes into space. The idea that the Earth is a closed system is a myth; it collapses each time we put our…

  19. 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.

  20. The fracture toughness of cancellous bone.

    PubMed

    Cook, R B; Zioupos, P

    2009-09-18

    The mechanical capacity and integrity of cancellous bone is crucial in osteoporosis, a condition which is set to become more prevalent with increasing lifespan and population sizes. The fracture toughness (FT) of cancellous bone has never been examined before and the conditions associated with the growth of a major crack through the lattice of cancellous bone, a cellular solid, may improve our understanding for structural integrity of this material. The aim of this study is to provide (i) basic data on cancellous bone FT and (ii) the experimental support for the hypothesis of Gibson, L.J., Ashby, M.F. [1997a. Chapter 10: Wood. In: Cellular Solids: Structure and Properties, second ed. Cambridge University Press, pp. 387-428; Gibson, L.J., Ashby, M.F., 1997b. Chapter 11: Cancellous Bone. In: Cellular Solids: Structure and Properties, second ed. Cambridge University Press, pp. 429-52] that the FT of cancellous bone tissue is governed by the density of the tissue to a power function of between one and two. 294 SENB and 121 DC(T) specimen were manufactured from 45 human femoral heads, 37 osteoporotic and 8 osteoarthritic, as well as 19 equine thoracic vertebrae. The samples were manufactured in two groups: the first aligned with the trabecular structure (A( parallel)), the second orientated at 90 degrees to the main trabecular orientation (A( perpendicular)). The samples were tested in either tensile or bending mode to provide values of the stress intensity factor (K). The results which were obtained show a strong and significant link between the density of the cancellous bone tissue and that the critical stress intensity values are governed by the density of the tissue to a power function of between 1 and 2 (K(Q) vs. apparent density: A( perpendicular)=1.58, A( parallel)=1.6). Our results provide some fundamental values for the critical stress intensity factor for cancellous bone and also support the previous hypothesis as set by Gibson, L.J., Ashby, M.F., 1997a

  1. Matching methods to create paired survival data based on an exposure occurring over time: a simulation study with application to breast cancer

    PubMed Central

    2014-01-01

    Background Paired survival data are often used in clinical research to assess the prognostic effect of an exposure. Matching generates correlated censored data expecting that the paired subjects just differ from the exposure. Creating pairs when the exposure is an event occurring over time could be tricky. We applied a commonly used method, Method 1, which creates pairs a posteriori and propose an alternative method, Method 2, which creates pairs in “real-time”. We used two semi-parametric models devoted to correlated censored data to estimate the average effect of the exposure HR¯(t): the Holt and Prentice (HP), and the Lee Wei and Amato (LWA) models. Contrary to the HP, the LWA allowed adjustment for the matching covariates (LWA a ) and for an interaction (LWA i ) between exposure and covariates (assimilated to prognostic profiles). The aim of our study was to compare the performances of each model according to the two matching methods. Methods Extensive simulations were conducted. We simulated cohort data sets on which we applied the two matching methods, the HP and the LWA. We used our conclusions to assess the prognostic effect of subsequent pregnancy after treatment for breast cancer in a female cohort treated and followed up in eight french hospitals. Results In terms of bias and RMSE, Method 2 performed better than Method 1 in designing the pairs, and LWA a was the best model for all the situations except when there was an interaction between exposure and covariates, for which LWA i was more appropriate. On our real data set, we found opposite effects of pregnancy according to the six prognostic profiles, but none were statistically significant. We probably lacked statistical power or reached the limits of our approach. The pairs’ censoring options chosen for combination Method 2 - LWA had to be compared with others. Conclusions Correlated censored data designing by Method 2 seemed to be the most pertinent method to create pairs, when the criterion

  2. General regression neural network and Monte Carlo simulation model for survival and growth of Salmonella on raw chicken skin as a function of serotype, temperature and time for use in risk assessment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A general regression neural network and Monte Carlo simulation model for predicting survival and growth of Salmonella on raw chicken skin as a function of serotype (Typhimurium, Kentucky, Hadar), temperature (5 to 50C) and time (0 to 8 h) was developed. Poultry isolates of Salmonella with natural r...

  3. 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.

  4. Design of tough ferritic steels for cryogenic use

    SciTech Connect

    Morris, J.W. Jr.

    1985-10-01

    This paper describes the design of ferritic steels and weldments that combine strength and toughness at cryogenic temperatures. The alloy must have a ductile-brittle transition temperature below the intended service temperature and a high fracture toughness in the ductile mode. Its systematic design uses the microstructure-property relations that govern the transition temperature and fracture toughness to identify a suitable microstructure, and then employs the microstructure-processing relations that govern its thermal response to manipulate the microstructure into the appropriate form. The procedure is illustrated by describing the heat treatments, microstructures and properties of a variety of laboratory and commercial alloys, including conventional ''9Ni'' steel, the low-Ni and Fe-Mn ferritic steels that have been developed as an alternative to 9Ni, the 12Ni steels that are promising for use at 4K, and the welding procedures and ferritic filler metals that are useful for ferritic cryogenic steels.

  5. Fracture toughness of an Al-Li-Cu-In alloy

    SciTech Connect

    Wagner, J.A.; Gangloff, R.P. Virginia, University, Charlottesville )

    1992-06-01

    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. 21 refs.

  6. 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.

  7. 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. PMID:26350404

  8. Evaluation and significance of fracture toughness in ceramic materials

    SciTech Connect

    Mutoh, Y.

    1995-12-31

    Fracture toughness tests of several ceramic materials were carried out according to the various test methods, that is the Bridge indentation (BI, SEPB), Fatigue precrack (FP), Controlled surface flaw (CSF), Chevron notch (CN) and Indentation fracture (IF) methods. Mutual comparison of the test results was made to discuss the validity and applicability of each test method. Significance of the apparent fracture toughness with stable crack growth was discussed. The intrinsic fracture toughness can be obtained by the CSF method, in which a small surface crack is used. At high temperatures, since nonlinear deformation due to softening of glass phase and stable crack growth occur, nonlinear fracture mechanics approach should be applied. J{sub IC}-value is successfully evaluated according to the R-curve method.

  9. New routes to improve toughness of rubber-modified epoxies

    SciTech Connect

    Pearson, R.A.

    1995-12-31

    Significant progress has been made in modeling the toughening mechanisms in rubber-modified epoxies due to the efforts of many researchers. The result of these efforts has led to an increased awareness of the roles of rubber particle bridging, rubber particle cavitation, matrix dilation, and matrix shear banding on the enhancement of fracture toughness. However, there are still many questions regarding rubber-toughening which remain unanswered. This talk will focus on the importance and the roles of the interphase region between the epoxy matrix and the rubber particle and of the overall particle morphology on the toughness enhancement in rubber-modified epoxies. It will be demonstrated that additional toughness enhancement may be achieved by means not included in any of the toughening models proposed to date. Methods to incorporate these effects into existing toughening models will be discussed.

  10. 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.

  11. Fracture toughness of ultrashort pulse-bonded fused silica

    NASA Astrophysics Data System (ADS)

    Richter, S.; Naumann, F.; Zimmermann, F.; Tünnermann, A.; Nolte, S.

    2016-02-01

    We determined the bond interface strength of ultrashort pulse laser-welded fused silica for different processing parameters. To this end, we used a high repetition rate ultrashort pulse laser system to inscribe parallel welding lines with a specific V-shaped design into optically contacted fused silica samples. Afterward, we applied a micro-chevron test to measure the fracture toughness and surface energy of the laser-inscribed welding seams. We analyzed the influence of different processing parameters such as laser repetition rate and line separation on the fracture toughness and fracture surface energy. Welding the entire surface a fracture toughness of 0.71 {MPa} {m}^{1/2}, about 90 % of the pristine bulk material ({≈ } 0.8 {MPa} {m}^{1/2}), is obtained.

  12. Potential factors affecting survival differ by run-timing and location: linear mixed-effects models of Pacific salmonids (Oncorhynchus spp.) in the Klamath River, California.

    PubMed

    Quiñones, Rebecca M; Holyoak, Marcel; Johnson, Michael L; Moyle, Peter B

    2014-01-01

    Understanding factors influencing survival of Pacific salmonids (Oncorhynchus spp.) is essential to species conservation, because drivers of mortality can vary over multiple spatial and temporal scales. Although recent studies have evaluated the effects of climate, habitat quality, or resource management (e.g., hatchery operations) on salmonid recruitment and survival, a failure to look at multiple factors simultaneously leaves open questions about the relative importance of different factors. We analyzed the relationship between ten factors and survival (1980-2007) of four populations of salmonids with distinct life histories from two adjacent watersheds (Salmon and Scott rivers) in the Klamath River basin, California. The factors were ocean abundance, ocean harvest, hatchery releases, hatchery returns, Pacific Decadal Oscillation, North Pacific Gyre Oscillation, El Niño Southern Oscillation, snow depth, flow, and watershed disturbance. Permutation tests and linear mixed-effects models tested effects of factors on survival of each taxon. Potential factors affecting survival differed among taxa and between locations. Fall Chinook salmon O. tshawytscha survival trends appeared to be driven partially or entirely by hatchery practices. Trends in three taxa (Salmon River spring Chinook salmon, Scott River fall Chinook salmon; Salmon River summer steelhead trout O. mykiss) were also likely driven by factors subject to climatic forcing (ocean abundance, summer flow). Our findings underscore the importance of multiple factors in simultaneously driving population trends in widespread species such as anadromous salmonids. They also show that the suite of factors may differ among different taxa in the same location as well as among populations of the same taxa in different watersheds. In the Klamath basin, hatchery practices need to be reevaluated to protect wild salmonids. PMID:24866173

  13. Potential Factors Affecting Survival Differ by Run-Timing and Location: Linear Mixed-Effects Models of Pacific Salmonids (Oncorhynchus spp.) in the Klamath River, California

    PubMed Central

    Quiñones, Rebecca M.; Holyoak, Marcel; Johnson, Michael L.; Moyle, Peter B.

    2014-01-01

    Understanding factors influencing survival of Pacific salmonids (Oncorhynchus spp.) is essential to species conservation, because drivers of mortality can vary over multiple spatial and temporal scales. Although recent studies have evaluated the effects of climate, habitat quality, or resource management (e.g., hatchery operations) on salmonid recruitment and survival, a failure to look at multiple factors simultaneously leaves open questions about the relative importance of different factors. We analyzed the relationship between ten factors and survival (1980–2007) of four populations of salmonids with distinct life histories from two adjacent watersheds (Salmon and Scott rivers) in the Klamath River basin, California. The factors were ocean abundance, ocean harvest, hatchery releases, hatchery returns, Pacific Decadal Oscillation, North Pacific Gyre Oscillation, El Niño Southern Oscillation, snow depth, flow, and watershed disturbance. Permutation tests and linear mixed-effects models tested effects of factors on survival of each taxon. Potential factors affecting survival differed among taxa and between locations. Fall Chinook salmon O. tshawytscha survival trends appeared to be driven partially or entirely by hatchery practices. Trends in three taxa (Salmon River spring Chinook salmon, Scott River fall Chinook salmon; Salmon River summer steelhead trout O. mykiss) were also likely driven by factors subject to climatic forcing (ocean abundance, summer flow). Our findings underscore the importance of multiple factors in simultaneously driving population trends in widespread species such as anadromous salmonids. They also show that the suite of factors may differ among different taxa in the same location as well as among populations of the same taxa in different watersheds. In the Klamath basin, hatchery practices need to be reevaluated to protect wild salmonids. PMID:24866173

  14. 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.

  15. 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.

  16. Thermal characterization and toughness of ethynyl containing blends

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.

    1991-01-01

    As part of an effort to develop high performance structural resins with an attractive combination of properties for aerospace applications, a series of ethynyl-terminated polysulfones of different molecular weights were prepared and blended with a low molecular weight ethynyl-terminated coreactant. Upon heating above 200 C, these ethynyl containing materials react to form a chain extended and crosslinked network structure. This reaction renders the materials insoluble in common solvents, but also reduces the toughness as compared to high molecular weight linear polysulfones. The thermal characterization of these blends and the toughness of the resulting cured materials are discussed.

  17. Functionalized poly(arylene ethers) as toughness modifiers for bismaleimides

    NASA Technical Reports Server (NTRS)

    Stenzenberger, H. D.; Roemer, W.; Hergenrother, P. M.; Jensen, B.; Breitigam, W.

    1990-01-01

    A family of novel, low molecular weight functionalized poly(arylene ether) resins has been investigated to ascertain its members' toughness-imparting contribution to neat bismaleimide (BMI) resin and BMI-matrix laminate composite properties. Attention is given to the contribution of the reactive poly(arylene ether)'s backbone chemistry to fracture toughness, as well as to the comparative influence of high and low molecular weight reactive poly(arylene ether) types on the modified BMI resin systems. The modified BMIs possess a polyphase morphology, with good adhesion between the thermoplastic nodules and the host thermoset systems.

  18. An innovative technique for evaluating fracture toughness of graphite materials

    NASA Astrophysics Data System (ADS)

    Wang, Jy-An John; Liu, Ken C.

    2008-10-01

    Spiral notch torsion fracture toughness test (SNTT) was developed recently to measure the intrinsic fracture toughness ( KIC) of structural materials. The SNTT system operates by applying pure torsion to uniform cylindrical specimens with a notch line that spirals around the specimen at a 45° pitch. The KIC values are obtained with the aid of a three-dimensional finite-element computer code, TOR3D-KIC. The SNTT method is uniquely suitable for testing a wide variety of materials used extensively in pressure vessel and piping structural components and weldments, including others such as ceramics, their composites, and concrete.

  19. Semi-interpenetrating polymer network's of polyimides: Fracture toughness

    NASA Technical Reports Server (NTRS)

    Hansen, Marion Glenn

    1988-01-01

    The objective was to improve the fracture toughness of the PMR-15 thermosetting polyimide by co-disolving LaRC-TPI, a thermoplastic polyimide. The co-solvation of a thermoplastic into a thermoset produces an interpenetration of the thermoplastic polymer into the thermoset polyimide network. A second research program was planned around the concept that to improve the fracture toughness of a thermoset polyimide polymer, the molecular weight between crosslink points would be an important macromolecular topological parameter in producing a fracture toughened semi-IPN polyimide.

  20. Toughness of composite steel-concrete structure of sandwich system

    SciTech Connect

    Iwata, Setsuo; Hattori, Yoichi

    1994-12-31

    Offshore structure should have a high degree of structural safety not only under normal conditions but also extreme conditions even under collision loadings. The authors carried out both experimental and theoretical investigations on the toughness of the sandwich composite structures. Experiments were carried out for the two-dimensional models of composite structures under pure bending and combined shear and bending as well. A nonlinear analysis was developed to predict the toughness of sandwich beam under pure bending. In the analysis the material nonlinearity of both concrete and steel plate were taken into consideration. The analysis were found to be very close to the experimental results.