Heat flow parameters affecting dendrite spacings during unsteady-state solidification of Sn-Pb and Al-Cu alloys

Solidification thermal parameters and dendrite arm spacings have been measured in hypoeutectic Sn-Pb and Al-Cu alloys solidified under unsteady-state heat flow conditions. It was observed that both primary and secondary spacings decreased with increased solute content for Sn-Pb alloys. For Al-Cu alloys, the primary spacing was found to be independent of composition, and secondary spacings decrease as the solute content is increased. The predictive theoretical models for primary spacings existing in the literature did not generate the experimental observations concerning the Sn-Pb and Al-Cu alloys examined in the present study. The theoretical Bouchard-Kirkaldy's (BK's) equation relating secondary spacings with tip growth rate has generated adequately the experimental results for both metallic systems. The insertion of analytical expressions for tip growth rate and cooling rate into the predictive model, or into the resulting experimental equations in order to establish empirical formulas permitting primary and secondary dendritic spacings to be determined as functions of unsteady-state solidification parameters such as melt superheat, type of mold, and transient metal/mold heat-transfer coefficient is proposed.34A4995100

Inequalities in access to cardiac rehabilitation after an acute coronary syndrome: the EPiHeart cohort

Objectives To estimate cardiac rehabilitation (CR) referral and participation rates among patients with acute coronary syndrome (ACS) and to identify their determinants, in two Portuguese regions. Design Prospective cohort study. Setting Patients consecutively admitted to the cardiology department of two hospitals, one in the district of Porto and one in the north-east region (NER) of Portugal, were enrolled in the EPIHeart cohort and then followed up for 6 months. Participants Between August 2013 and December 2014, 939 patients were included in the cohort, and 853 were re-evaluated at 6-month follow-up. Outcome measures Referral rate was defined as the proportion of eligible patients who were referred to a CR programme, whereas participation rate was defined as the proportion of eligible patients who completed a CR programme, as was recommended by their physicians. Results Patients referred were 32.3% and 10.7% of those eligible in Porto and NER, respectively. In both regions, referral to CR decreased with age and with longer travel times to CR centres and increased with education or social class. At follow-up, 128 patients from Porto (26.2% of those eligible and 81.0% of those referred) and 26 from NER (7.1% of those eligible and 66.7% of those referred) reported actually participating in a CR programme. In Porto, the main barriers to participation were the long time until a programme was available and lack of perceived benefit. Patients in NER identified distance to CR and costs as the main barriers. Conclusions CR remains clearly underused in Portugal, with major inequalities in access between regions. Achieving equitable and greater use of CR requires a multilevel approach addressing barriers related to healthcare system, providers and patients in order to improve provision, referral and participation.This study was supported by FEDER through the Operational Programme Competitiveness and Internationalisation and national funding from the Foundation for Science and Technology—FCT (Portuguese Ministry of Science, Technology and Higher Education) (FCOMP-01-0124-FEDER-028709), under the project ‘Inequalities in coronary heart disease management and outcomes in Portugal’ (FCT PTDC/DTP-EPI/0434/2012) and the Unidade de Investigação em Epidemiologia—Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; ref UID/DTP/04750/2013)

Sex differences in presenting symptoms of acute coronary syndrome: the EPIHeart cohort study

Objectives Prompt diagnosis of acute coronary syndrome (ACS) remains a challenge, with presenting symptoms affecting the diagnosis algorithm and, consequently, management and outcomes. This study aimed to identify sex differences in presenting symptoms of ACS. Design Data were collected within a prospective cohort study (EPIHeart). Setting Patients with confirmed diagnosis of type 1 (primary spontaneous) ACS who were consecutively admitted to the Cardiology Department of two tertiary hospitals in Portugal between August 2013 and December 2014. Participants Presenting symptoms of 873 patients (227 women) were obtained through a face-to-face interview. Outcome measures: Typical pain was defined according to the definition of cardiology societies. Clusters of symptoms other than pain were identified by latent class analysis. Logistic regression was used to quantify differences in presentation of ACS symptoms by sex. Results Chest pain was reported by 82% of patients, with no differences in frequency or location between sexes. Women were more likely to feel pain with an intensity higher than 8/10 and this association was stronger for patients aged under 65 years (interaction P=0.028). Referred pain was also more likely in women, particularly pain referred to typical and atypical locations simultaneously. The multiple symptoms cluster, which was characterised by a high probability of presenting with all symptoms, was almost fourfold more prevalent in women (3.92, 95% CI 2.21 to 6.98). Presentation with this cluster was associated with a higher 30-day mortality rate adjusted for the GRACE V.2.0 risk score (4.9% vs 0.9% for the two other clusters, P<0.001). Conclusions While there are no significant differences in the frequency or location of pain between sexes, women are more likely to feel pain of higher intensity and to present with referred pain and symptoms other than pain. Knowledge of these ACS presentation profiles is important for health policy decisions and clinical practice.This study was funded by FEDER through the Operational Programme Competitiveness and Internationalization and national funding from the Foundation for Science and Technology (FCT; Portuguese Ministry of Science, Technology and Higher Education) (FCOMP-01-0124-FEDER-028709), under the project ’Inequalities in coronary heart disease management and outcomes in Portugal' (Ref. FCT PTDC/DTP-EPI/0434/2012) and Unidade de Investigação em Epidemiologia—Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref. UID/DTP/04750/2013)

Regional variation in coronary heart disease mortality trends in Portugal, 1981-2012

BACKGROUND: Information is scarce about the geographic variation in time trends of mortality from coronary heart disease (CHD). We aimed to describe trends in death rates, absolute number of deaths and years of life lost (YLL) due to CHD among men and women in Portugal, by region, from 1981 to 2012. METHODS: The age-standardized mortality rates from CHD were estimated by sex and region. We used joinpoint regression analysis to calculate the annual percent change (APC) in mortality and to identify points of significant change in the trend. The YLL due to premature mortality for CHD were computed using the Global Burden of Disease method. RESULTS: The age-adjusted mortality from CHD decreased between 1981 and 2012, both in men and women, but with significantly different APC by region. Smaller declines in rates were observed in Alentejo (men: APC 1993-2012: -2.4%; women: APC 1991-2012: -2.4%). The greatest decline was observed in Madeira between 2003 and 2012, in men (APC: -7.6%) and women (APC: -9.7%). The decline in rates in Algarve started only after 2003, whereas it was consistent from 1981 in the North and started in the 1990s in most other regions. A decrease in the number of deaths was only observed after 2000. The YLL from CHD decreased from 1981 to 2012, mainly after 2000. CONCLUSIONS: In Portugal, between 1981 and 2012, relative declines of CHD mortality indicators were different by geographic region. Consistent decreases in mortality rates were only observed in the Centre, Lisbon and North, the most populated and urbanized regions

Drought impact on forest carbon dynamics and fluxes in Amazonia

In 2005 and 2010 the Amazon basin experienced two strong droughts, driven by shifts in the tropical hydrological regime possibly associated with global climate change, as predicted by some global models. Tree mortality increased after the 2005 drought, and regional atmospheric inversion modelling showed basin-wide decreases in CO2 uptake in 2010 compared with 2011 (ref. 5). But the response of tropical forest carbon cycling to these droughts is not fully understood and there has been no detailed multi-site investigation in situ. Here we use several years of data from a network of thirteen 1-ha forest plots spread throughout South America, where each component of net primary production (NPP), autotrophic respiration and heterotrophic respiration is measured separately, to develop a better mechanistic understanding of the impact of the 2010 drought on the Amazon forest. We find that total NPP remained constant throughout the drought. However, towards the end of the drought, autotrophic respiration, especially in roots and stems, declined significantly compared with measurements in 2009 made in the absence of drought, with extended decreases in autotrophic respiration in the three driest plots. In the year after the drought, total NPP remained constant but the allocation of carbon shifted towards canopy NPP and away from fine-root NPP. Both leaf-level and plot-level measurements indicate that severe drought suppresses photosynthesis. Scaling these measurements to the entire Amazon basin with rainfall data, we estimate that drought suppressed Amazon-wide photosynthesis in 2010 by 0.38 petagrams of carbon (0.23-0.53 petagrams of carbon). Overall, we find that during this drought, instead of reducing total NPP, trees prioritized growth by reducing autotrophic respiration that was unrelated to growth. This suggests that trees decrease investment in tissue maintenance and defence, in line with eco-evolutionary theories that trees are competitively disadvantaged in the absence of growth. We propose that weakened maintenance and defence investment may, in turn, cause the increase in post-drought tree mortality observed at our plots.Gordon and Betty Moore FoundationNatural Environment Research Council (NERC)EU FP7 Amazalert (282664) projectEU FP7GEOCARBON (283080) projectNational Council for Scientific and Technological Development (CNPq, Brazil)ARC - fellowship awardERC - Advanced Investigator AwardRoyal Society - Wolfson Research Merit AwardJackson FoundationJohn Fell Fun

A novel in situ passive heating method for evaluating whole-tree responses to daytime warming in remote environments

Background Many significant ecosystems, including important non-forest woody ecosystems such as the Cerrado (Brazilian savannah), are under threat from climate change, yet our understanding of how increasing temperatures will impact native vegetation remains limited. Temperature manipulation experiments are important tools for investigating such impacts, but are often constrained by access to power supply and limited to low-stature species, juvenile individuals, or heating of target organs, perhaps not fully revealing how entire or mature individuals and ecosystems will react to higher temperatures. Results We present a novel, modified open top chamber design for in situ passive heating of whole individuals up to 2.5 m tall (but easily expandable) in remote field environments with strong solar irradiance. We built multiple whole-tree heating structures (WTHSs) in an area of Cerrado around native woody species Davilla elliptica and Erythroxylum suberosum to test the design and its effects on air temperature and humidity, while also studying the physiological responses of E. suberosum to short-term heating. The WTHSs raised internal air temperature by approximately 2.5 °C above ambient during the daytime. This increased to 3.4 °C between 09:00 and 17:00 local time when thermal impact was greatest, and during which time mean internal temperatures corresponded closely with maximum ambient temperatures. Heating was consistent over time and across WTHSs of variable size and shape, and they had minimal effect on humidity. E. suberosum showed no detectable response of photosynthesis or respiration to short-term experimental heating, but some indication of acclimation to natural temperature changes. Conclusions Our WTHSs produced a consistent and reproducible level of daytime heating in line with mid-range climate predictions for the Cerrado biome by the end of the century. The whole-tree in situ passive heating design is flexible, low-cost, simple to build using commonly available materials, and minimises negative impacts associated with passive chambers. It could be employed to investigate the high temperature responses of many understudied species in a range of complex non-forest environments with sufficient solar irradiance, providing new and important insights into the possible impacts of our changing climate

The carbon balance of South America: A review of the status, decadal trends and main determinants

Copyright © 2012 European Geosciences Union. This is the published version available at http://www.biogeosciences-discuss.net/9/627/2012/bgd-9-627-2012.htmlWe attempt to summarize the carbon budget of South America and relate it to its dominant controls: population and economic growth, changes in land use practices and a changing atmospheric environment and climate. Flux estimation methods which we consider sufficiently reliable are fossil fuel emission inventories, biometric analysis of old-growth rainforests, estimation of carbon release associated with deforestation based on remote sensing and inventories, and finally inventories of agricultural exports. Other routes to estimating land-atmosphere CO2 fluxes include atmospheric transport inverse modelling and vegetation model predictions but are hampered by the data paucity and the need for improved parameterisation. The available data we analyze suggest that South America was a net source to the atmosphere during the 1980s (∼0.3–0.4 Pg C yr−1) and close to neutral (∼0.1 Pg C yr−1) in the 1990s with carbon uptake in old-growth forests nearly compensating carbon losses due to fossil fuel burning and deforestation. Annual mean precipitation over tropical South America measured by Amazon River discharge has a long-term upward trend, although over the last decade, dry seasons have tended to be drier and longer (and thus wet seasons wetter), with the years 2005 and 2010 experiencing strong droughts. It is currently unclear what the effect of these climate changes on the old-growth forest carbon sink will be but first measurements suggest it may be weakened. Based on scaling of forest census data the net carbon balance of South America seems to have been an increased source roughly over the 2005–2010 period (a total of ∼1 Pg C of dead tree biomass released over several years) due to forest drought response. Finally, economic development of the tropical forest regions of the continent is advancing steadily with exports of agricultural products being an important driver and witnessing a strong upturn over the last decade