The recurrent nova M31N 2008-12a experiences annual eruptions, contains a near-Chandrasekhar-mass white dwarf, and has the largest mass accretion rate in any nova system. In this paper, we present ...Hubble Space Telescope (HST) WFC3/UVIS photometry of the late decline of the 2015 eruption. We couple these new data with archival HST observations of the quiescent system and Keck spectroscopy of the 2014 eruption. The late-time photometry reveals a rapid decline to a minimum luminosity state, before a possible recovery/rebrightening in the run up to the next eruption. Comparison with accretion disk models supports the survival of the accretion disk during the eruptions, and uncovers a quiescent disk mass accretion rate of the order of 10 − 6 M yr − 1 , which may rise beyond 10 − 5 M yr − 1 during the super-soft source phase-both of which could be problematic for a number of well-established nova eruption models. Such large accretion rates, close to the Eddington limit, might be expected to be accompanied by additional mass loss from the disk through a wind and even through collimated outflows. The archival HST observations, combined with the disk modeling, provide the first constraints on the mass donor: L donor = 103 − 11 + 12 L , R donor = 14.14 − 0.47 + 0.46 R , and T eff , donor = 4890 110 K, which may be consistent with an irradiated M31 red-clump star. Such a donor would require a system orbital period 5 days. Our updated analysis predicts that the M31N 2008-12a WD could reach the Chandrasekhar mass in < 20 kyr.
ABSTRACT BACKGROUND Patients with cleft lip and/or palate can undergo numerous procedures to improve appearance, speech, dentition and hearing. We developed a cleft-specific patient-reported outcome ...instrument to facilitate rigorous international measurement and benchmarking. METHODS Data were collected from patients aged 8–29 years with cleft lip and/or palate at 30 hospitals in 12 countries between October 2014 and November 2016. Rasch measurement theory analysis was used to refine the scales and to examine reliability and validity. Normative CLEFT-Q values were computed for age, sex and cleft type. RESULTS Analysis led to the refinement of an eating and drinking checklist and 12 scales measuring appearance (of the face, nose, nostrils, teeth, lips, jaws and cleft lip scar), health-related quality of life (psychological, social, school, speech distress) and speech function. All scales met the requirements of the Rasch model. Analysis to explore differential item functioning by age, sex and country provided evidence to support the use of a common scoring algorithm for each scale for international use. Lower (worse) scores on CLEFT-Q scales were associated with having a speech problem, being unhappy with facial appearance, and needing future cleft-related treatments, providing evidence of construct validity. Normative values for age, sex and cleft type showed poorer outcomes associated with older age, female sex and having a visible cleft. INTERPRETATION The CLEFT-Q represents a rigorously developed instrument that can be used internationally to collect and compare evidence-based outcomes data from patients aged 8–29 years of age with cleft lip and/or palate.
ABSTRACT We present the results from observing nine Galactic novae in eruption with the Solar Mass Ejection Imager (SMEI) between 2004 and 2009. While many of these novae reached peak magnitudes that ...were either at or approaching the detection limits of SMEI, we were still able to produce light curves that in many cases contained more data at and around the initial rise, peak, and decline than those found in other variable star catalogs. For each nova, we obtained a peak time, maximum magnitude, and for several an estimate of the decline time ( ). Interestingly, although of lower quality than those found in Hounsell et al., two of the light curves may indicate the presence of a pre-maximum halt. In addition, the high cadence of the SMEI instrument has allowed the detection of low-amplitude variations in at least one of the nova light curves.
Marine organisms normally swim at elevated speeds relative to cruising speeds only during strenuous activity, such as predation or escape. We measured swimming speeds of 29 ram ventilating sharks ...from 10 species and of three Atlantic bluefin tunas immediately after exhaustive exercise (fighting a capture by hook-and-line) and unexpectedly found all individuals exhibited a uniform mechanical response, with swimming speed initially two times higher than the cruising speeds reached approximately 6 h later. We hypothesized that elevated swimming behaviour is a means to increase energetic demand and drive the removal of lactate accumulated during capture via oxidation. To explore this hypothesis, we estimated the mechanical work that must have been spent by an animal to elevate its swim speed and then showed that the amount of lactate that could have been oxidized to fuel it comprises a significant portion of the amount of lactate normally observed in fishes after exhaustive exercise. An estimate for the full energetic cost of the catch-and-release event ensued.
The accretion of hydrogen onto a white dwarf star ignites a classical nova eruption
-a thermonuclear runaway in the accumulated envelope of gas, leading to luminosities up to a million times that of ...the Sun and a high-velocity mass ejection that produces a remnant shell (mainly consisting of insterstellar medium). Close to the upper mass limit of a white dwarf
(1.4 solar masses), rapid accretion of hydrogen (about 10
solar masses per year) from a stellar companion leads to frequent eruptions on timescales of years
to decades
. Such binary systems are known as recurrent novae. The ejecta of recurrent novae, initially moving at velocities of up to 10,000 kilometres per second
, must 'sweep up' the surrounding interstellar medium, creating cavities in space around the nova binary. No remnant larger than one parsec across from any single classical or recurrent nova eruption is known
, but thousands of successive recurrent nova eruptions should be capable of generating shells hundreds of parsecs across. Here we report that the most frequently recurring nova, M31N 2008-12a in the Andromeda galaxy (Messier 31 or NGC 224), which erupts annually
, is indeed surrounded by such a super-remnant with a projected size of at least 134 by 90 parsecs. Larger than almost all known remnants of even supernova explosions
, the existence of this shell demonstrates that the nova M31N 2008-12a has erupted with high frequency for millions of years.
Determining the evolution of the ejecta morphology of novae provides valuable information on the shaping mechanisms in operation at early stages of the nova outburst. Understanding such mechanisms ...has implications for studies of shaping for example in proto-Planetary Nebulae. Here we perform morpho-kinematical studies of V2491 Cyg using spectral data to determine the likely structure of the ejecta and its relationship to the central system and shaping mechanisms. We use shape to model different morphologies and retrieve their spectra. These synthetic spectra are compared with observed spectra to determine the most likely morphology giving rise to them, including system inclination and expansion velocity of the nova ejecta. We find the best-fitting remnant morphology to be that of polar blobs and an equatorial ring with an implied inclination of 80+3
−12 degrees and an maximum expansion velocity of the polar blobs of 3100+200
−100 km s−1 and for the equatorial ring 2700+200
−100 km s−1. This inclination would suggest that we should observe eclipses which will enable us to determine more precisely important parameters of the central binary. We also note that the amplitude of the outburst is more akin to the found in recurrent nova systems.
Research suggests that end‐stage renal disease patients with elevated body mass index (BMI) have superior outcomes on dialysis. In contrast, low and high BMI patients represent the highest risk ...cohorts for kidney transplant recipients. The important question remains concerning how to manage transplant candidates given the potentially incommensurate impact of BMI by treatment modality. We conducted a retrospective analysis of waitlisted and transplanted patients in the United States from 1990 to 2003. We constructed Cox models to evaluate the effect of BMI on mortality of waitlisted candidates and identified risk factors for rapid weight change. We then assessed the impact of weight change during waitlisting on transplant outcomes. Decline in BMI on the waiting list was not protective for posttransplant mortality or graft loss across BMI strata. Substantial weight loss pretransplantation was associated with rapid gain posttransplantation. The highest risk for death was among listed patients with low BMI (13–20 kg/m2, adjusted hazard ratio = 1.47, p < 0.01). Approximately one‐third of candidates had a change in BMI category prior to transplantation. While observed declines in BMI may be volitional or markers of disease processes, there is no evidence that candidates have improved transplant outcomes attributable to weight loss. Prospective trials are needed to evaluate the efficacy of weight loss protocols for candidates of kidney transplantation.
Although high BMI on the wait list is a risk factor for kidney transplant recipients, this retrospective analysis of USRDS data found no evidence that weight loss before transplantation is associated with improved transplant outcomes. See also editorial by Schnitzler et al in this issue on page 493.
Summary
Background
Rising cirrhosis incidence and mortality in the United Kingdom has been attributed predominantly to excess alcohol consumption. However, metabolic risk factors such as Type 2 ...diabetes and obesity may also be important.
Aim
To screen at‐risk individuals in general practice for undetected cirrhosis using transient elastography and study the risk factors underlying these cases.
Methods
The study was undertaken in 4 general practices (adult patient population 20 868) between February 2012 and September 2014. Patients with defined risk factors for chronic liver disease (hazardous alcohol use and/or Type 2 diabetes) were identified from the General Practice electronic records and invited for transient elastography. Elevated liver stiffness was defined as ≥8 kPa. Cirrhosis was confirmed by established histological, radiological and biochemical methods.
Results
Two thousand three hundred and sixty eight patients were invited for transient elastography and 899/919 who attended (97.8%) had valid measurements. Of these 230 patients had elevated liver stiffness (25.6%) and 27 had cirrhosis (2.9%). Risk factors for new cirrhosis diagnoses were obesity and/or Type 2 diabetes in 16 patients (59.3%), alcohol alone in 3 (11.1%) and both alcohol and obesity and/or diabetes in eight (29.6%). Presence of cirrhosis was significantly increased in obese patients with Type 2 diabetes or hazardous alcohol use compared to non‐obese (odds ratio 9.4 95% CI 2.2‐40.9 and 5.6 95% CI 1.6‐19.7 respectively).
Conclusions
The number of new cases of cirrhosis diagnosed clearly demonstrates that existing estimates of prevalence are likely to be gross underestimates. Obesity was an important risk factor for cirrhosis within both alcohol users and diabetics.
Linked ContentThis article is linked to Ampuero and Romero‐Gómez paper. To view
this article visit https://doi.org/10.1111/apt.14517.
Modelling the morphology of a nova outburst provides valuable information on the shaping mechanism in operation at early stages following the outburst. We performed morpho-kinematical studies, using ...shape, of the evolution of the Hα line profile following the outburst of the nova KT Eridani. We applied a series of geometries in order to determine the morphology of the system. The best-fitting morphology was that of a dumbbell structure with a ratio between the major to minor axis of 4:1, with an inclination angle of 58
deg and a maximum expansion velocity of 2800 ± 200 km s−1. Although, we found that it is possible to define the overall structure of the system, the radial density profile of the ejecta is much more difficult to disentangle. Furthermore, morphology implied here may also be consistent with the presence of an evolved secondary as suggested by various authors.
•A carbon price may generate substantial sequestration but not much biodiversity.•A complementary biodiversity payment may generate biodiversity services.•Supply of both services is highly variable ...under plausible global outlooks for 2050.•Domestic variables of adoption rate and agricultural productivity are influential.
Global agroecosystems can contribute to both climate change mitigation and biodiversity conservation, and market mechanisms provide a highly prospective means of achieving these outcomes. However, the ability of markets to motivate the supply of carbon sequestration and biodiversity services from agricultural land is uncertain, especially given the future changes in environmental, economic, and social drivers. We quantified the potential supply of these services from the intensive agricultural land of Australia from 2013 to 2050 under four global outlooks in response to a carbon price and biodiversity payment scheme. Each global outlook specified emissions pathways, climate, food demand, energy price, and carbon price modeled using the Global Integrated Assessment Model (GIAM). Using a simplified version of the Land Use Trade-Offs (LUTO) model, economic returns to agriculture, carbon plantings, and environmental plantings were calculated each year. The supply of carbon sequestration and biodiversity services was then quantified given potential land use change under each global outlook, and the sensitivity of the results to key parameters was assessed. We found that carbon supply curves were similar across global outlooks. Sharp increases in carbon sequestration supply occurred at carbon prices exceeding 50$tCO2−1 in 2015 and exceeding 65$tCO2−1 in 2050. Based on GIAM-modeled carbon prices, little carbon sequestration was expected at 2015 under any global outlook. However, at 2050 expected carbon supply under each outlook differed markedly, ranging from 0 to 189MtCO2yr−1. Biodiversity services of 3.32% of the maximum may be achieved in 2050 for a 1$B investment under median scenario settings. We conclude that a carbon market can motivate supply of substantial carbon sequestration but only modest amounts of biodiversity services from agricultural land. A complementary biodiversity payment can synergistically increase the supply of biodiversity services but will not provide much additional carbon sequestration. The results were sensitive to global drivers, especially the carbon price, and the domestic drivers of adoption hurdle rate and agricultural productivity. The results can inform the design of an effective national policy and institutional portfolio addressing the dual objectives of climate change and biodiversity conservation that is robust to future uncertainty in both national and global drivers.
PDF
