Modeling and Optimization of Materials and Structures

Preface : The current economic and ecological context requires different industries towards the optimization of structures. One of the most striking examples is the soaring price of oil, which launched the major aircraft manufacturers Airbus and Boeing in a race to relief structures, to reduce their consumption. Therefore, the need of competitive products, both in terms of reliability, performance or operating cost, is pervasive and growing, aviation and elsewhere. Thus, work on the material parts by offering innovative solutions to reduce their weight and improve their performance (new materials, new processes, etc.) is essential and becomes more than ever a major industrial challenge. One way of increasing the selected aircraft is use of composite materials. Indeed, their high ratio mechanical / density properties and excellent resistance to environmental significantly improve the structural performance of the aircraft while generating a significant weight gain (20 to 30% weight of a structure). They were originally implemented in the design of secondary structures of aircraft, but improving their manufacturing processes and a better understanding of their mechanical properties and their degradation mechanisms are they now used for the manufacture of primary structures, such as the fuselage or the central box of an aircraft wing. If applications were rather the military origin, composites now particularly interested in civil aviation, the constraints are much stricter certification, which requires predictability of behavior and life of structures much finer Thus, at present, they account for over 50% of the mass of newer aircraft such as the Airbus A350, the Airbus A380 or the Boeing 787. The potential of composite materials is important, but will speak only on one condition: work not only on the basic constituents of the material (fibers, resin, ...) on the injection preparation conditions (methods, thermal cycle, shaped in the mold, ...) but also and above all on the function of the material in the structure. Indeed, the aterial is a component of a more complex system, consisting of parts, assemblies, subassemblies and the structure itself. This vision system involves understanding the material as parameters, not data, an overall optimization of the structure. This link between material and structure is evident for composites where fiber orientation, or reinforcements in a more general way, in the direction of efforts can greatly increase the performance / weight ratio. We understand that optimizing the structure requires, among other things, a design material to locally respond to the "just need" structural. The main objectives of this special issue (consisting mainly of a selection of papers presented at 5th International Symposium on AirCraft MAterials ACMA 2014) are, by means of modeling strategies and simulation out with conventional strategies, pushing the current limits in modeling and computation in response industrial and societal challenges. It is also to control the calculations and models in a framework that takes into account the major sources of uncertainty to optimize materials and structures. Particular attention is made to the modeling and validation of composite materials and structures

Effects of Rotation on the Minimum Mass of Primordial Progenitors of Pair Instability Supernovae

The issue of which stars may reach the conditions of electron/positron pair formation instability is of importance to understand the final evolution both of the first stars and of contemporary stars. The criterion to enter the pair instability regime in density and temperature is basically controlled by the mass of the oxygen core. The main sequence masses that produce a given oxygen core mass are, in turn, dependent on metallicity, mass loss, and convective and rotationally-induced mixing. We examine the evolution of massive stars to determine the minimum main sequence mass that can encounter pair-instability effects, either a pulsational pair instability (PPISN) or a full-fledged pair-instability supernova (PISN). We concentrate on zero-metallicity stars with no mass loss subject to the Schwarzschild criterion for convective instability, but also explore solar metallicity and mass loss and the Ledoux criterion. As expected, for sufficiently strong rotationally-induced mixing, the minimum main sequence mass is encountered for conditions that induce effectively homogeneous evolution such that the original mass is converted almost entirely to helium and then to oxygen. For this case, we find that the minimum main sequence mass is ~40 Msun to encounter PPISN and ~65 Msun to encounter a PISN. When mass-loss is taken into account those mass limits become ~50 Msun for PPISN and ~80 Msun for PISN progenitors. The implications of these results for the first stars and for contemporary supernovae is discussed.Comment: 23 pages, 8 figure

Variation in reported experience of involvement in cancer treatment decision making: Evidence from the National Cancer Patient Experience Survey

This is the final version. Available on open access from Springer Nature via the DOI in this recordBackground: Exploring variation in patients' experiences of involvement in treatment decision making can identify groups needing extra support, such as additional consultation time, when considering treatment options. Methods: We analysed data from the 2010 English National Cancer Patient Experience Survey, a national survey of all patients attending hospitals in England for cancer treatment over a 3-month period, to examine how experience of involvement in decisions about treatment varied between patients with 38 different primary cancers using logistic regression. We analysed responses from 41 411 patients to a single question examining patient experience of involvement in treatment decision making. We calculated unadjusted odds ratios of reporting the most positive experience between patients of different sociodemographic and tumour characteristics and explored the effects of adjusting for age, gender, ethnicity, deprivation, cancer type and hospital of treatment.Results:Of the 41 441 respondents, 29 776 (72%) reported positive experiences of decision-making involvement. Younger patients reported substantially less positive experiences of involvement in decision making (adjusted OR=0.49 16-24 vs 65-74; P<0.001), as did ethnic minorities (adjusted ORs=0.52, 0.62 and 0.73 for Black, Chinese and Asian vs White patients, respectively; P<0.001). Experience varied considerably between patients with different cancers (e.g., OR=0.52 for anal and 1.37 for melanoma vs colon cancer; P<0.001), with ovarian, myeloma, bladder and rectal cancer patients reporting substantially worse experiences compared with other patients with gynaecological, haematological, urological and colorectal cancers, respectively. Clustering of different patient groups within hospitals with outlying performance report scores could not account for observed differences. Conclusion: Efforts to improve involvement in treatment decision making can focus on those who report the worst experience, in particular younger patients, ethnic minorities and patients with rectal, ovarian, multiple myeloma and bladder cancer. © 2013 Cancer Research UK. All rights reserved.National Institute for Health Research (NIHR

A survey of physicians knowledge regarding awareness of maternal alcohol use and the diagnosis of FAS.

BACKGROUND: Alcohol is the most widely used drug in the world that is a human teratogen whose use among women of childbearing age has been steadily increasing. It is also probable that Fetal Alcohol Syndrome is under diagnosed by physicians. The objectives of this study were twofold: 1) to evaluate the experience, knowledge and confidence of family physicians with respect to the diagnosis of FAS and 2) to evaluate physicians awareness of maternal drinking patterns. METHODS AND PARTICIPANTS: A multiple choice anonymous questionnaire was sent to a randomly selected group of family physicians in the Metropolitan Toronto area. RESULTS: There was a 73% (75/103) total response rate; Overall, 6/75 (8%) of family physicians reported that they had actually diagnosed a child with FAS. 17.9% had suspicions but did not make a diagnosis and 12.7% reported making a referral to confirm the diagnosis. Physician rated confidence in the ability to diagnosis FAS was low, with 49% feeling they had very little confidence. 75% reported counselling pregnant women and 60.8% reported counselling childbearing women in general on the use of alcohol. When asked what screening test they used to detect the use of alcohol, 75% described frequency/quantity. Not a single respondent identified using the current accepted screening method for alcohol use (TWEAK) which is recommended by The Centre for Addiction and Mental Health. CONCLUSIONS: Family physicians do not feel confident about diagnosing FAS. None of the physicians were aware of the current screening methods to accurately gage alcohol use in pregnant and childbearing wome

Hormesis and Its Place in Nonmonotonic Dose–Response Relationships: Some Scientific Reality Checks

OBJECTIVE: This analysis is a critical assessment of current hormesis literature. I discuss definitions, characterization, generalizability, mechanisms, absence of empirical data specific for hormesis hypothesis testing, and arguments that hormesis be the “default assumption” in risk assessment. DATA SOURCES: Hormesis, a biological phenomenon typically described as low-dose stimulation from substances producing higher-dose inhibition, has recently garnered interest in several quarters. The principal sources of published materials for this analysis are the writings of certain proponents of hormesis. Surprisingly few systematic critiques of current hormesis literature exist. Limits to the phenomenon’s appropriate role in risk assessment and health policy have been published. DATA SYNTHESIS: Serious gaps in scientific understanding remain: a stable definition; generalizability, especially for humans; a clear mechanistic basis; limitations in the presence of multiple toxic end points, target organs, and mechanisms. Absence of both arms-length, consensus-driven, scientific evaluations and empirical data from studies specifically designed for hormesis testing have limited its acceptance. CONCLUSIONS: Definition, characterization, occurrence, and mechanistic rationale for hormesis will remain speculative, absent rigorous studies done specifically for hormesis testing. Any role for hormesis in current risk assessment and regulatory policies for toxics remains to be determined

Accuracy of routinely recorded ethnic group information compared with self-reported ethnicity: evidence from the English Cancer Patient Experience survey.

OBJECTIVE: To describe the accuracy of ethnicity coding in contemporary National Health Service (NHS) hospital records compared with the 'gold standard' of self-reported ethnicity. DESIGN: Secondary analysis of data from a cross-sectional survey (2011). SETTING: All NHS hospitals in England providing cancer treatment. PARTICIPANTS: 58 721 patients with cancer for whom ethnicity information (Office for National Statistics 2001 16-group classification) was available from self-reports (considered to represent the 'gold standard') and their hospital record. METHODS: We calculated the sensitivity and positive predictive value (PPV) of hospital record ethnicity. Further, we used a logistic regression model to explore independent predictors of discordance between recorded and self-reported ethnicity. RESULTS: Overall, 4.9% (4.7-5.1%) of people had their self-reported ethnic group incorrectly recorded in their hospital records. Recorded White British ethnicity had high sensitivity (97.8% (97.7-98.0%)) and PPV (98.1% (98.0-98.2%)) for self-reported White British ethnicity. Recorded ethnicity information for the 15 other ethnic groups was substantially less accurate with 41.2% (39.7-42.7%) incorrect. Recorded 'Mixed' ethnicity had low sensitivity (12-31%) and PPVs (12-42%). Recorded 'Indian', 'Chinese', 'Black-Caribbean' and 'Black African' ethnic groups had intermediate levels of sensitivity (65-80%) and PPV (80-89%, respectively). In multivariable analysis, belonging to an ethnic minority group was the only independent predictor of discordant ethnicity information. There was strong evidence that the degree of discordance of ethnicity information varied substantially between different hospitals (p<0.0001). DISCUSSION: Current levels of accuracy of ethnicity information in NHS hospital records support valid profiling of White/non-White ethnic differences. However, profiling of ethnic differences in process or outcome measures for specific minority groups may contain a substantial and variable degree of misclassification error. These considerations should be taken into account when interpreting ethnic variation audits based on routine data and inform initiatives aimed at improving the accuracy of ethnicity information in hospital records

Accuracy of routinely recorded ethnic group information compared with self-reported ethnicity: Evidence from the English Cancer Patient Experience survey

This is the final version. Available on open access from BMJ Publishing Group via the DOI in this recordData sharing statement No additional data are available.Objective: To describe the accuracy of ethnicity coding in contemporary National Health Service (NHS) hospital records compared with the 'gold standard' of self-reported ethnicity. Design: Secondary analysis of data from a crosssectional survey (2011). Setting: All NHS hospitals in England providing cancer treatment. Participants: 58 721 patients with cancer for whom ethnicity information (Office for National Statistics 2001 16-group classification) was available from self-reports (considered to represent the 'gold standard') and their hospital record. Methods: We calculated the sensitivity and positive predictive value (PPV) of hospital record ethnicity. Further, we used a logistic regression model to explore independent predictors of discordance between recorded and self-reported ethnicity. Results: Overall, 4.9% (4.7-5.1%) of people had their self-reported ethnic group incorrectly recorded in their hospital records. Recorded White British ethnicity had high sensitivity (97.8% (97.7-98.0%)) and PPV (98.1% (98.0-98.2%)) for self-reported White British ethnicity. Recorded ethnicity information for the 15 other ethnic groups was substantially less accurate with 41.2% (39.7-42.7%) incorrect. Recorded 'Mixed' ethnicity had low sensitivity (12-31%) and PPVs (12- 42%). Recorded 'Indian', 'Chinese', 'Black-Caribbean' and 'Black African' ethnic groups had intermediate levels of sensitivity (65-80%) and PPV (80-89%, respectively). In multivariable analysis, belonging to an ethnic minority group was the only independent predictor of discordant ethnicity information. There was strong evidence that the degree of discordance of ethnicity information varied substantially between different hospitals (p<0.0001). Discussion: Current levels of accuracy of ethnicity information in NHS hospital records support valid profiling of White/non-White ethnic differences. However, profiling of ethnic differences in process or outcome measures for specific minority groups may contain a substantial and variable degree of misclassification error. These considerations should be taken into account when interpreting ethnic variation audits based on routine data and inform initiatives aimed at improving the accuracy of ethnicity information in hospital records. Copyright © 2013 BMJ Publishing Group. All rights reserved.National Institute for Health Research (NIHR

Microstructure of single-phase cobalt and manganese oxide spinel Mn3−xCoxO4 ceramics

This paper reports microstructural studies of single-phase Mn3−xCoxO4(0.98 ≤ x ≤ 2.93) spinel ceramics using transmission electron microscopy(TEM) and energy dispersive X-ray spectroscopy (EDX). These ceramics were obtained by conventional sintering or by spark plasma sintering(SPS) of powders prepared by thermal decomposition of coprecipitated oxalate precursors. For x < 1.78 or x ≥ 1.78, the monophasic ceramicscorrespond respectively to quadratic (Q) or cubic (C) spinel structure. The ferroelastic character of the structural phase transition from C to Qis highlighted by specific microstructural features. The effect of chemical composition and heat treatment conditions on the microstructure andessentially on the presence and the characteristics of twins were investigated. The coherent twin interfaces are parallel to (1 1 2) planes in the Qcell. Twins can correspond to: tweeds, single lamellae (widths: 5–306 nm) arranged parallel to each other, large lamellae (widths: 69–928 nm)internally twinned and sometimes arranged in cyclic forms (triangular shapes)

The effects of population III stars on the chemical and photometrical evolution of ellipticals

We have studied the effects of an hypothetical initial generation containing very massive stars (M > 100 Msun, pair-creation SNe) on the chemical and photometric evolution of elliptical galaxies. To this purpose, we have computed the evolution of a typical elliptical galaxy with luminous mass of the order of 10^11 Msun and adopted chemical evolution models already tested to reproduce the main features of ellipticals. We have tested several sets of yields for very massive zero-metallicity stars: these stars should produce quite different amounts of heavy elements than lower mass stars. We found that the effects of population III stars on the chemical enrichment is negligible if only one or two generations of such stars occurred, whereas they produce quite different results from the standard models if they continuously formed for a period not shorter than 0.1 Gyr. In this case, the results are at variance with the main observational constraints of ellipticals such as the average [] ratio in stars and the integrated colors. Therefore, we conclude that if population III stars ever existed they must have been present for a very short period of time and their effects on the following evolution of the parent galaxy must have been negligible. This effect is minimum if a more realistic model with initial infall of gas rather than the classic monolithic model is adopted. Ultimately, we conclude that there is no need to invoke a generation of very massive stars in ellipticals to explain their chemical and photometric properties.Comment: 9 pages, 6 figures, MNRAS accepte