R Coronae Borealis Stars are Viable Factories of Pre-solar Grains

We present a new theoretical estimate for the birthrate of R Coronae Borealis (RCB) stars that is in agreement with recent observational data. We find the current Galactic birthrate of RCB stars to be $\approx$ 25% of the Galactic rate of Type Ia supernovae, assuming that RCB stars are formed through the merger of carbon-oxygen and helium-rich white dwarfs. Our new RCB birthrate ($1.8 \times 10^{-3}$ yr$^{-1}$) is a factor of 10 lower than previous theoretical estimates. This results in roughly 180--540 RCB stars in the Galaxy, depending on the RCB lifetime. From the theoretical and observational estimates, we calculate the total dust production from RCB stars and compare this rate to dust production from novae and born-again asymptotic giant branch (AGB) stars. We find that the amount of dust produced by RCB stars is comparable to the amounts produced by novae or born-again post-AGB stars, indicating that these merger objects are a viable source of carbonaceous pre-solar grains in the Galaxy. There are graphite grains with carbon and oxygen isotopic ratios consistent with the observed composition of RCB stars, adding weight to the suggestion that these rare objects are a source of stardust grains.Comment: Accepted for publication in The Astrophysical Journal, 7 page

Optimization of the magnetic dynamo

In stars and planets, magnetic fields are believed to originate from the motion of electrically conducting fluids in their interior, through a process known as the dynamo mechanism. In this Letter, an optimization procedure is used to simultaneously address two fundamental questions of dynamo theory: "Which velocity field leads to the most magnetic energy growth?" and "How large does the velocity need to be relative to magnetic diffusion?" In general, this requires optimization over the full space of continuous solenoidal velocity fields possible within the geometry. Here the case of a periodic box is considered. Measuring the strength of the flow with the root-mean-square amplitude, an optimal velocity field is shown to exist, but without limitation on the strain rate, optimization is prone to divergence. Measuring the flow in terms of its associated dissipation leads to the identification of a single optimal at the critical magnetic Reynolds number necessary for a dynamo. This magnetic Reynolds number is found to be only 15% higher than that necessary for transient growth of the magnetic field.Comment: Optimal velocity field given approximate analytic form. 4 pages, 4 figure

Novel Rubidium Poly-Nitrogen Materials at High Pressure

First-principles crystal structure search is performed to predict novel rubidium poly-nitrogen materials at high pressure by varying the stoichiometry, i. e. relative quantities of the constituent rubidium and nitrogen atoms. Three compounds of high nitrogen content, RbN_{5}, RbN_{2}, and Rb_{4}N_{6}, are discovered. Rubidium pentazolate (RbN5) becomes thermodynamically stable at pressures above \unit[30]{GPa}. The charge transfer from Rb to N atoms enables aromaticity in cyclo-N_{^{_{5}}}^{-} while increasing the ionic bonding in the crystal. Rubidium pentazolate can be synthesized by compressing rubidium azide (RbN3) and nitrogen (N2) precursors above \unit[9.42]{GPa}, and its experimental discovery is aided by calculating the Raman spectrum and identifying the features attributed to N_{^{_{5}}}^{-} modes. The two other interesting compounds, RbN2 containing infinitely-long single-bonded nitrogen chains, and Rb_{4}N_{6} consisting of single-bonded N_{6} hexazine rings, become thermodynamically stable at pressures exceeding \unit[60]{GPa}. In addition to the compounds with high nitrogen content, Rb_{3}N_{3}, a new compound with 1:1 RbN stoichiometry containing bent N_{3} azides is found to exist at high pressures

What is the Value of Home? NOT FOR SALE - West End Interventions

Many Australians today are image consumers. We fail to question the importance of lifestyle imagery created and promoted by Real Estate Agencies whom have no actual part in the physical creation of house, or indeed the intimate making of "home" through our experiences of place. Real Estate Markets dictate how, where, when and what we buy. Re-sale values, profit-making, and value-adding interfere with the crafting of a home over time as a tangible, individual, collaborative, and rich lived experience of dwelling. The "NOT FOR SALE" project is a response and critique of the dominance of real estate forces in West End within the context and unshakable presence of a booming inner-city property market. This proposal originated from an experimental dwelling in Avebury St., West End. This project has been fashioned over a period of several years primarily from recycled local materials, interconnected with the changing needs and spatial requirements of the occupants and project participants. The influence of property markets is of little concern in this home "making". The "NOT FOR SALE" project attempts to question and critique the purely financial value that we as a society place upon our homes. By appropriating and re-coding the Real Estate Signage typologies, we aim to provoke social commentary on the dominance of real estate forces in the West End suburb. There is a strong and rich tradition of anti-consumerist activist graffiti in West End. Activists re-code signs and property with political commentary and critique. The "NOT FOR SALE" project draws upon this tradition through our RRESign (Recodified Real Estate Signs): we aim to redress the dominant commercial forces associated with the single house/property. Collectively, at the scale of the street, these RRESigns will reflect a critique of street scale, amenity, and character. Finally, at the scale of the suburb, the network of RRESigns will reflect a critique of the idea of place making. Collectively, the aim of the "NOT FOR SALE" RRESign interventions is to highlight the idea of making and the material characteristics of dwelling that challenges the cultural value of commodified property, re-defining and prioritising the idea of "home". Conventional Real Estate signs use images and text to sell an idea of home: our proposed interventions sell nothing, and are rather celebrations of the joy of making tactile, handcrafted objects, and by extension, the making and crafting of home. The intimate and experiential understanding of home will be harnessed through the engagement of local residents. Community groups within West End such as Local Push can further disseminate the RRESign interventions. The signs will be constructed West End-specific materials (old signs purchased from inexpensive second-hand material merchant Reverse Garbage in Montague Rd.): turning post-consumer waste into objects of material beauty and social critique. Residents and community groups will be encouraged to place their RRESigns outside their properties and adjacent real estate signs, frustrating and recoding the existing For-Sale signs that currently dominate the West End street scape. The project is dependent on the support of the local residents, extending from a few signs in Avebury St. to a network of RRESigns throughout West End. A commentary on people's responses to the project will be linked to the www.apbv.com.au website. What is the value of home

Associations between area-level unemployment, body mass index, and risk factors for cardiovascular disease in an urban area

INTRODUCTION: Il existe peu d’évidences sur l’association entre le taux de chômage dans le milieu résidentiel (CR) et le risque de maladies cardiovasculaires parmi les résidents de milieux urbains. De plus, on ne sait pas si ce lien diffère entre les deux sexes. Cette thèse a pour objectif de déterminer la direction et la taille de l’association entre le CR et le risque de maladies cardiovasculaires, et d’examiner si cette association varie en fonction du sexe. MÉTHODES: Un sous-échantillon de 342 participants de l’Étude sur les habitudes de vie et la santé dans les quartiers montréalais a rapporté ses habitudes de vie et sa situation socio-économique. Des mesures biologiques et anthropométriques ont été recueillies par une infirmière. Le CR a été opérationnalisé en fonction d’une zone-tampon d’un rayon de 250 m centrée sur la résidence de chacun des participants à l’aide d’un Système d’Information Géographique (SIG). Des équations d’estimation généralisées ont été utilisées afin d’estimer l’association entre le CR et l’Indice de Masse Corporelle (IMC) et un score cumulatif de Risque Cardio-métabolique (RC) représentant la présence de valeurs élevées de cholestérol total, de triglycérides, de lipoprotéines de haute densité et d’hémoglobine glyquée. RÉSULTATS: Après ajustement pour l’âge, le sexe, le tabagisme, les comportements de santé et le statut socio-économique, le fait de vivre dans un endroit classé dans le 3e ou 4e quartile de CR était associé avec un IMC plus élevé (beta pour Q4 = 2.1 kg/m2, IC 95%: 1.02-3.20; beta pour Q3 = 1.5 kg/m2, IC 95%: 0.55-2.47) et un taux plus élevé de risque cardiovasculaires Risque Relatif [RR pour Q4 = 1.82 (IC 95 %: 1.35-2.44); RR pour Q3 = 1.66 (IC 95%: 1.33-2.06)] par rapport au 1er quartile. L'interaction entre le sexe et le CR révèle une différence absolue d’IMC de 1.99 kg/m2 (IC 95%: 0.00-4.01) et un risque supérieur (RR=1.39; IC 95%: 1.06-1.81) chez les femmes par rapport aux hommes. CONCLUSIONS: Le taux de chômage dans le milieux résidentiel est associé à un plus grand risque de maladies cardiovasculaires, mais cette association est plus prononcée chez les femmes.INTRODUCTION: Little is known about whether area-level unemployment is independently associated with individual-level Cardiovascular Disease (CVD) in an urban setting. Furthermore, it is unclear whether this relationship differs by sex. This thesis examined the direction and magnitude of the association between area-level unemployment (ALU) and Body Mass Index (BMI) and a marker for CVD risk, and whether this association differs by sex. METHODS: A sample of 342 individuals from the Montreal Neighbourhood Survey of Lifestyle and Health (MNSLH) self-reported behavioural and socioeconomic information. A registered nurse collected biochemical and anthropometric data. ALU was operationalised within a 250 m radius buffer centered on individual residence using a Geographic Information System (GIS). Generalized Estimating Equations were used to determine if body mass index (BMI), and a cumulative score for total cardiometabolic risk (TCR) representing elevated values for total cholesterol, triglycerides, high-density lipoprotein cholesterol, and glycosylated hemoglobin, were associated with ALU. RESULTS: After adjustment for age, gender, smoking status, behavioural, and socioeconomic covariates, living in an area in the upper ALU quartiles was associated with an elevated BMI [Q4 beta = 2.1 kg/m2 (95% CI: 1.02-3.20)] and greater TCR [Q4 RR = 1.82 (95 % CI: 1.35-2.44); Q3 RR = 1.66 (95% CI: 1.33-2.06)] relative to the 1st quartile. Sex-by-ALU interaction revealed a 1.99 kg/m2 (95% CI: 0.00-4.01) difference in BMI and 1.39-fold (95% CI: 1.06-1.81) greater TCR Score for women compared to men. CONCLUSIONS: Area-level unemployment is associated with greater CVD risk in men and women but associations are stronger among women

Gastrointestinal Bleeding Events and Statin Use: A Large Propensity Score-Matched Retrospective Cohort Study

Literature is conflicting regarding the association between statin use and gastrointestinal (GI) bleeding. This study sought to determine whether there is an association between statin use and GI bleeding by comparing incidence of gastrointestinal events between statin users and an active comparator group. Data was obtained from a large administrative claims database composed of subjects enrolled in a selection of insurance plans throughout the United States from 2009-2014. New statin users (exposed) and thyroid medication users (active comparator, unexposed) were followed from the baseline period (one year prior to medication initiation) until first event, discontinuation, or disenrollment. Subjects were matched using a propensity score based on demographics, comorbidities, healthcare utilization, and medication use. Odds of gastrointestinal events, including GIH, gastroduodenal (GD) ulcer, and gastritis/duodenitis were compared between groups. The final analysis included 1,442,954 statin users matched using a 1:1 algorithm with replacement to thyroid medication users. Frequency of GIH in the unexposed group was 0.56±0.01% and frequency in the low, moderate, and high-intensity statin users group was 0.81±0.03%, 0.91±0.02%, and 0.90±0.05% respectively (p\u3c0.002). Statin users had 1.81 times the rate of GIH compared to the active comparator group (HR 1.81; 95% confidence interval (CI) 1.76-1.86). Hazard ratios for GD ulcer and gastritis/duodenitis events were 1.13 (CI 0.618-2.05) and 1.19 (CI 0.796-1.80) respectively. Practitioners should consider these trends when prescribing statins in patients at high- risk of bleeding. Additional research is needed to verify the association between statins and GIH

Meaningful Measurement Matters: Defining Potentially Inappropriate Medication Use to Target Cognitive Outcomes

Preventable and unintended consequences of medication use occur in more than 25% of ambulatory and hospitalized patients, and nearly half of long-term care patients. Unfortunately, many medications used to treat common health conditions in older adults (such as anxiety, behavioral disturbances, incontinence, insomnia, depression, and pain) have also been linked to cognitive impairment and decline. Recently, substantial efforts to investigate medications and medication classes that may be associated with cognitive impairment and decline in older adults have been undertaken. Unfortunately, studies have used a wide variety of different tools to define “potentially inappropriate medication” (PIM) use, and no published literature has consistently associated a particular medication appropriateness tool with cognitive outcomes, leaving clinicians and patients without a much-needed approach to deprescribing for preservation of cognitive function. Given the national focus on prevention of cognitive decline, the vast pool of available PIM measurement tools, and the variety of ways in which to consider exposure to PIMs, there is a need to determine which tool (if any) identifies PIMs most strongly associated with cognitive decline. Without widespread consensus as to what measure of PIM use is the best to use when studying the aptitude of medications to cause cognitive decline, clinicians will not have the tools they need to improve outcomes for their patients. As the world awaits further developments that may one day produce an effective treatment (or even cure) for the terrible brain-destroying disease of dementia, we can take steps today to improve medication therapy that may dampen its horrific impact on the lives of older adults and their loved ones. In this work, we set out to examine the issue of measuring medication appropriateness to target cognitive outcomes with the intent of informing future research and clinical practice. While the gold-standard in evidence generation remains randomized placebo-controlled clinical trials, we have seen that even the most rigorously performed trials are not useful to generate evidence if there is not a consistent meaning to inappropriate medication. Groundwork must laid to provide crucial validation and consensus to the measurement of medication appropriateness in light of cognition, and then it must be applied to numerous prospective research endeavors in order to provide a synthesized evidence-base for how medications should be managed to ensure appropriate use in older adults wishing to preserve cognition. In the first section, we have provided a historical context for the importance of medication management, described the current state of affairs in the US and around the world, and provided an overview of the available tools that have been used to measure medication appropriateness with a perspective toward cognition. Section two will utilize a number of these tools to estimate prevalence of potentially inappropriate medication use in various populations of American older adults. The next section will use various methodological techniques and data sources to explore how some of these tools may or may not be associated with cognitive decline in older adults. We will define both PIM use and cognitive decline in a variety of ways to determine the effect varying definitions may have on new evidence generation. Finally, we will explore how the findings provided in this work may be applied to clinical practice, future research endeavors, and governmental policies

When the Penny Drops: Understanding how social class influences speciality careers in the UK medical profession

In the UK, the medical profession is socially exclusive and socially stratified as doctors from more advantaged backgrounds are more likely to train for specialities with more competitive entry. However, in research to date the causes and consequences of social stratification have been overlooked. We explore this subject here, drawing on a qualitative study comprising in-depth interviews with 30 medical students and doctors from less advantaged socio-economic backgrounds negotiating medical school and early careers. Using Bourdieu's ‘theory of practice’ we show how socialisation in the family and at school influences how aspirant medics from less advantaged backgrounds view the world, suggesting some inclination towards more community orientated careers, which may be less competitive. However, these tendencies are encouraged as they lack stocks of social, economic and cultural capital, which are convertible to power and position in the field. While allowing for both choice and constraint our core argument is that speciality outcomes are sometimes inequitable and potentially inefficient, as doctors from more advantaged backgrounds have privileged access to more competitive careers for reasons not solely related to ability or skill. Our main theoretical contribution is to literature in the sociology of medical education where ours is the first study to open-up the ‘black box’ of causal factors connecting medical students' resources on entering the field of education and training with speciality outcomes, though our findings also have important implications for practitioners, the profession and for patients. We discuss the implications for safe and effective healthcare and how this informs directions for future research