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. 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…

  8. 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…

  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. 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.

  2. 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.

  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. 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)

  10. 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…

  11. 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…

  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. 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.

  12. 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.

  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. 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

  15. 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.

  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. 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.

  19. 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.

  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. 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.

  10. 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

  11. 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)

  12. 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…

  13. 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…

  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. 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

  17. 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

  18. Fracture toughness of fibrous composite materials

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1984-01-01

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

  19. 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. 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

  12. 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

  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. 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

  5. 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.

  6. 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…

  7. 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.

  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. 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.

  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. 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

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

    SciTech Connect

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

    1985-05-01

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

  2. 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

  3. 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

  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. 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

  15. 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.

  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. 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

  18. 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

  19. 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

  20. 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.

  1. 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.

  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. 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

  14. 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…

  15. 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

  16. 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

  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. 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,...

  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. 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...

  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. 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.

  4. 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.

  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. 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

  12. 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.

  13. 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.

  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. 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…

  6. 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…

  7. 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…

  8. 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…

  9. 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

  10. 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…

  11. 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…

  12. 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…

  13. 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

  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. 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

  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. 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.

  4. 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…

  5. 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.

  6. 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.

  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. 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.

  4. 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

  5. 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

  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 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

  13. 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.

  14. 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.

  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. 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.

  20. 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.

  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. 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

  4. 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

  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. 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.

  7. 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...

  8. 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...

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

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

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

    Code of Federal Regulations, 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...