The changing constants of creep: A letter on region splitting in creep lifing

This letter explores issues surrounding region splitting, a current technique used to improve creep life predictions. The history of the technique is discussed briefly and its current implementation by major research groups described in more detail. An example of novel or non-traditional region splitting is also explored with its first known application to nano-creep. The issues surrounding region splitting when considered as an industry practice are also briefly discussed. The purpose of this letter is to explicitly discuss region splitting as a creep lifing technique and identify the current and future issues researchers and industry may face when implementing this powerful technique

A Modern Philosophy for Creep Lifing in Engineering Alloys

Lifing of components which are likely to be subject to high temperature creep deformation is a critical area to a range of industries, particularly power generation and aerospace. In particular, extrapolation of short term data to predict long-term allowable creep stresses is an area of significant importance, since no appropriate method of accelerating tests has been discovered. Traditional methods for extrapolation are mainly based around power law type equations that have historically formed the basis of creep mechanism understanding. The current chapter however, seeks to offer alternative approaches in the field, particularly emphasising the need to link lifing approaches to observable micro-mechanical behaviour

Advanced Methods for Creep in Engineering Design

There are many applications where the combination of stress and elevated temperature require creep to be considered during the design process. For some applications, an evaluation of rupture life for given conditions is sufficient, however, for components such as those in gas turbine aeroengines, the accumulation of creep strain over time and the effect this has on other phenomena, such as high-temperature fatigue must be considered. In this chapter, modern creep curve modelling methods are applied to alloys used in gas turbine applications over a wide range of test conditions. Also, different creep hardening modelling methods are discussed along with their application to transient creep showing the deficiencies of simplistic models. Models are related to micromechanical properties where possible, and creep damage models are evaluated and applied to different applications using finite element analysis (FEA)

Development and Assessment of a New Empirical Model for Predicting Full Creep Curves

This paper details the development and assessment of a new empirical creep model that belongs to the limited ranks of models reproducing full creep curves. The important features of the model are that it is fully standardised and is universally applicable. By standardising, the user no longer chooses functions but rather fits one set of constants only. Testing it on 7 contrasting materials, reproducing 181 creep curves wedemonstrate its universality. New model and Theta Projection curves are compared to one another using an assessment tool developed within this paper

Household Food Insecurity and U.S. Department of Housing and Urban Development Federal Housing Assistance

The U.S. Department of Housing and Urban Development (HUD) provides housing rental assistance to more than 4.5 million low-income households. Using health survey data from the National Health Interview Survey (NHIS) linked to Federal housing administrative data, household food insecurity was assessed among adults receiving housing assistance at the time of their NHIS interview during 2011 and 2012 (n=2,089). Food-insecure households had difficulty at times providing adequate food for all their members due to limited resources. Among NHIS adult respondents receiving HUD assistance, 37.2 percent reported household food insecurity (including low and very low food security), while 19.1 percent experienced very low food security, the more severe range of food insecurity characterized by disrupted eating patterns and reduced food intake. Analyses revealed that adults in the Housing Choice Voucher program were significantly more likely to report household food insecurity than adults in other HUD programs (Public Housing and Multifamily Housing), net of other characteristics. Although housing assistance programs are designed to free financial resources associated with housing cost burden, household food insecurity is still prominent among low-income, HUD-assisted adults

Household Food Insecurity and U.S. Department of Housing and Urban Development Federal Housing Assistance

The U.S. Department of Housing and Urban Development (HUD) provides housing rental assistance to more than 4.5 million low-income households. Using health survey data from the National Health Interview Survey (NHIS) linked to Federal housing administrative data, household food insecurity was assessed among adults receiving housing assistance at the time of their NHIS interview during 2011 and 2012 (n=2,089). Food-insecure households had difficulty at times providing adequate food for all their members due to limited resources. Among NHIS adult respondents receiving HUD assistance, 37.2 percent reported household food insecurity (including low and very low food security), while 19.1 percent experienced very low food security, the more severe range of food insecurity characterized by disrupted eating patterns and reduced food intake. Analyses revealed that adults in the Housing Choice Voucher program were significantly more likely to report household food insecurity than adults in other HUD programs (Public Housing and Multifamily Housing), net of other characteristics. Although housing assistance programs are designed to free financial resources associated with housing cost burden, household food insecurity is still prominent among low-income, HUD-assisted adults

Fiscal Policy and Income Redistribution in Latin America: Challenging the Conventional Wisdom

Conventional wisdom states that fiscal policy redistributes little in Latin America. Lower tax revenues and, above all, lower and less progressive transfers have been identified as the main cause. Existing studies show that, while in Europe the distribution of all transfers combined (cash and in-kind) is egalitarian, the bulk of transfers in Latin America accrue to the upper quintile. Through an in-depth fiscal incidence analysis applied to Argentina, Bolivia, Brazil, Mexico and Peru we argue that conventional wisdom may be wrong. First, the extent and effectiveness of income redistribution and poverty reduction, revenue-collection, and spending patterns vary so significantly across countries that speaking of "Latin America" as a unity is misleading. The (after direct taxes and transfers) Gini, for example, declines by over 10 percent in Argentina but by only 2.4 percent in Bolivia. In Argentina, Brazil and Bolivia government revenues are close to 40 percent of GDP, whereas in Mexico and Peru they are around 20 percent. Social spending (excluding contributory pensions) as a share of GDP ranges from 17 percent in Brazil to 5.2 percent in Peru. Second, social spending does not accrue to the richest quintile. On the contrary, concentration coefficients for social spending are highly negative (progressive in absolute terms) for Argentina and slightly so for Bolivia and Mexico. In Brazil and Peru social spending is progressive in relative terms only. Third, there is no obvious correlation between the size of government and the size of social spending, on the one hand, and the extent and effectiveness of redistribution, on the other: government size is similar for Argentina and Bolivia but they are on opposite sides in terms of the extent of redistribution.Fourth, due to indirect taxes households are net payers to the "fisc" beginning in the third decile in Bolivia and Brazil; for Argentina, Mexico and Peru this happens in the fifth decile. Fifth, corrective measures differ too: in Argentina, Bolivia and Brazil they may involve the reduction in revenues and total spending, while revenues and social spending (especially direct transfers to the poor) should be increased in Mexico and Peru. Bolivia and Brazil need to introduce changes to their tax and transfer system so that net payers to the "fisc" start at higher incomes. All five countries need to improve the of progressivity of their spending, including non-social spending components.fiscal incidence, fiscal policy, inequality, poverty, redistribution, social policy, taxes, transfers, Latin America, Argentina, Bolivia, Brazil, Mexico and Peru

Systematic Review of the Relationships Between Objectively Measured Physical Activity and Health Indicators in School-Aged Children and Youth

Moderate-to-vigorous physical activity (MVPA) is essential for disease prevention and health promotion. Emerging evidence suggests other intensities of physical activity (PA), including light-intensity activity (LPA), may also be important, but there has been no rigorous evaluation of the evidence. The purpose of this systematic review was to examine the relationships between objectively measured PA (total and all intensities) and health indicators in school-aged children and youth. Online databases were searched for peer-reviewed studies that met the a priori inclusion criteria: population (apparently healthy, aged 5–17 years), intervention/exposure/comparator (volumes, durations, frequencies, intensities, and patterns of objectively measured PA), and outcome (body composition, cardiometabolic biomarkers, physical fitness, behavioural conduct/pro-social behaviour, cognition/academic achievement, quality of life/well-being, harms, bone health, motor skill development, psychological distress, self-esteem). Heterogeneity among studies precluded meta-analyses; narrative synthesis was conducted. A total of 162 studies were included (204 171 participants from 31 countries). Overall, total PA was favourably associated with physical, psychological/social, and cognitive health indicators. Relationships were more consistent and robust for higher (e.g., MVPA) versus lower (e.g., LPA) intensity PA. All patterns of activity (sporadic, bouts, continuous) provided benefit. LPA was favourably associated with cardiometabolic biomarkers; data were scarce for other outcomes. These findings continue to support the importance of at least 60 min/day of MVPA for disease prevention and health promotion in children and youth, but also highlight the potential benefits of LPA and total PA. All intensities of PA should be considered in future work aimed at better elucidating the health benefits of PA in children and youth

Association between active genes occurs at nuclear speckles and is modulated by chromatin environment

Genes on different chromosomes can be spatially associated in the nucleus in several transcriptional and regulatory situations; however, the functional significance of such associations remains unclear. Using human erythropoiesis as a model, we show that five cotranscribed genes, which are found on four different chromosomes, associate with each other at significant but variable frequencies. Those genes most frequently in association lie in decondensed stretches of chromatin. By replacing the mouse α-globin gene cluster in situ with its human counterpart, we demonstrate a direct effect of the regional chromatin environment on the frequency of association, whereas nascent transcription from the human α-globin gene appears unaffected. We see no evidence that cotranscribed erythroid genes associate at shared transcription foci, but we do see stochastic clustering of active genes around common nuclear SC35-enriched speckles (hence the apparent nonrandom association between genes). Thus, association between active genes may result from their location on decondensed chromatin that enables clustering around common nuclear speckles