Tracing the Mass during Low-Mass Star Formation. II. Modelling the Submillimeter Emission from Pre-Protostellar Cores

We have modeled the emission from dust in pre-protostellar cores, including a self-consistent calculation of the temperature distribution for each input density distribution. Model density distributions include Bonnor-Ebert spheres and power laws. The Bonnor-Ebert spheres fit the data well for all three cores we have modeled. The dust temperatures decline to very low values (\Td \sim 7 K) in the centers of these cores, strongly affecting the dust emission. Compared to earlier models that assume constant dust temperatures, our models indicate higher central densities and smaller regions of relatively constant density. Indeed, for L1544, a power-law density distribution, similar to that of a singular, isothermal sphere, cannot be ruled out. For the three sources modeled herein, there seems to be a sequence of increasing central condensation, from L1512 to L1689B to L1544. The two denser cores, L1689B and L1544, have spectroscopic evidence for contraction, suggesting an evolutionary sequence for pre-protostellar cores.Comment: 22 pages, 9 figures, Ap. J. accepted, uses emulateapj5.st

The Detection and Characterization of cm Radio Continuum Emission from the Low-mass Protostar L1014-IRS

Observations by the Cores to Disk Legacy Team with the Spitzer Space Telescope have identified a low luminosity, mid-infrared source within the dense core, Lynds 1014, which was previously thought to harbor no internal source. Followup near-infrared and submillimeter interferometric observations have confirmed the protostellar nature of this source by detecting scattered light from an outflow cavity and a weak molecular outflow. In this paper, we report the detection of cm continuum emission with the VLA. The emission is characterized by a quiescent, unresolved 90 uJy 6 cm source within 0.2" of the Spitzer source. The spectral index of the quiescent component is $\alpha = 0.37\pm 0.34$ between 6 cm and 3.6 cm. A factor of two increase in 6 cm emission was detected during one epoch and circular polarization was marginally detected at the $5\sigma$ level with Stokes {V/I} $= 48 \pm 16$% . We have searched for 22 GHz H2O maser emission toward L1014-IRS, but no masers were detected during 7 epochs of observations between June 2004 and December 2006. L1014-IRS appears to be a low-mass, accreting protostar which exhibits cm emission from a thermal jet or a wind, with a variable non-thermal emission component. The quiescent cm radio emission is noticeably above the correlation of 3.6 cm and 6 cm luminosity versus bolometric luminosity, indicating more radio emission than expected. We characterize the cm continuum emission in terms of observations of other low-mass protostars, including updated correlations of centimeter continuum emission with bolometric luminosity and outflow force, and discuss the implications of recent larger distance estimates on the physical attributes of the protostar and dense molecular core.Comment: 14 pages. Accepted for publication in Ap

Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation

Observations have revealed prodigious amounts of star formation in starburst galaxies as traced by dust and molecular emission, even at large redshifts. Recent work shows that for both nearby spiral galaxies and distant starbursts, the global star formation rate, as indicated by the infrared luminosity, has a tight and almost linear correlation with the amount of dense gas as traced by the luminosity of HCN. Our surveys of Galactic dense cores in HCN 1-0 emission show that this correlation continues to a much smaller scale, with nearly the same ratio of infrared luminosity to HCN luminosity found over 7-8 orders of magnitude in L_IR, with a lower cutoff around 10^{4.5} L_sun of infrared luminosity. The linear correlation suggests that we may understand distant star formation in terms of the known properties of local star-forming regions. Both the correlation and the luminosity cutoff can be explained if the basic unit of star formation in galaxies is a dense core, similar to those studied in our Galaxy.Comment: 10 pages, 2 figures. In press for ApJ Letter

A bi-directional relationship between obesity and health-related quality of life : evidence from the longitudinal AusDiab study

Objective: To assess the prospective relationship between obesity and health-related quality of life, including a novel assessment of the impact of health-related quality of life on weight gain.Design and setting: Longitudinal, national, population-based Australian Diabetes, Obesity and Lifestyle (AusDiab) study, with surveys conducted in 1999/2000 and 2004/2005.Participants: A total of 5985 men and women aged 25 years at study entry.Main outcome measure(s): At both time points, height, weight and waist circumference were measured and self-report data on health-related quality of life from the SF-36 questionnaire were obtained. Cross-sectional and bi-directional, prospective associations between obesity categories and health-related quality of life were assessed.Results: Higher body mass index (BMI) at baseline was associated with deterioration in health-related quality of life over 5 years for seven of the eight health-related quality of life domains in women (all P0.01, with the exception of mental health, P&gt;0.05), and six out of eight in men (all P&lt;0.05, with the exception of role-emotional, P=0.055, and mental health, P&gt;0.05). Each of the quality-of-life domains related to mental health as well as the mental component summary were inversely associated with BMI change (all P&lt;0.0001 for women and P0.01 for men), with the exception of vitality, which was significant in women only (P=0.008). For the physical domains, change in BMI was inversely associated with baseline general health in women only (P=0.023).Conclusions: Obesity was associated with a deterioration in health-related quality of life (including both physical and mental health domains) in this cohort of Australian adults followed over 5 years. Health-related quality of life was also a predictor of weight gain over 5 years, indicating a bi-directional association between obesity and health-related quality of life. The identification of those with poor health-related quality of life may be important in assessing the risk of future weight gain, and a focus on health-related quality of life may be beneficial in weight management strategies.<br /

An ammonia spectral map of the L1495-B218 filaments in the Taurus molecular cloud. I. Physical properties of filaments and dense cores

We present deep NH3 observations of the L1495-B218 filaments in the Taurus molecular cloud covering over a 3° angular range using the K-band focal plane array on the 100 m Green Bank Telescope. The L1495-B218 filaments form an interconnected, nearby, large complex extending over 8 pc. We observed NH3 (1, 1) and (2, 2) with a spectral resolution of 0.038 km s−1 and a spatial resolution of 31''. Most of the ammonia peaks coincide with intensity peaks in dust continuum maps at 350 and 500 μm. We deduced physical properties by fitting a model to the observed spectra. We find gas kinetic temperatures of 8–15 K, velocity dispersions of 0.05–0.25 km s−1, and NH3 column densities of 5 × 1012 to 1 × 1014 cm−2. The CSAR algorithm, which is a hybrid of seeded-watershed and binary dendrogram algorithms, identifies a total of 55 NH3 structures, including 39 leaves and 16 branches. The masses of the NH3 sources range from 0.05 to 9.5 ${{M}_{\odot }}$. The masses of NH3 leaves are mostly smaller than their corresponding virial mass estimated from their internal and gravitational energies, which suggests that these leaves are gravitationally unbound structures. Nine out of 39 NH3 leaves are gravitationally bound, and seven out of nine gravitationally bound NH3 leaves are associated with star formation. We also found that 12 out of 30 gravitationally unbound leaves are pressure confined. Our data suggest that a dense core may form as a pressure-confined structure, evolve to a gravitationally bound core, and undergo collapse to form a protostar

Knowledge, the curriculum, and democratic education: the curious case of school English

Debate over subject curricula is apt to descend into internecine squabbles over which (whose?) curriculum is best. Especially so with school English, because its domain(s) of knowledge have commonly been misunderstood, or, perhaps, misrepresented in the government’s programmes of study. After brief consideration of democratic education (problems of its form and meaning), I turn to issues of knowledge and disciplinarity, outlining two conceptions of knowledge – the one constitutive and phenomenological, the other stipulative and social-realist. Drawing on Michael Young and Johan Muller, I argue that, by social-realist standards of objectivity, school English in England -- as currently framed in national curriculum documents -- falls short of the standards of ‘powerful knowledge’ and of a democratic education conceived as social justice. Having considered knowledge and disciplinarity in broad terms, I consider the curricular case of school English, for it seems to me that the curious position of English in our national curriculum has resulted in a model that is either weakly, perhaps even un-, rooted in the network of academic disciplines that make up English studies

Macronutrients, Food Groups, and Eating Patterns in the Management of Diabetes: A systematic review of the literature, 2010

The effectiveness of medical nutrition therapy (MNT) in the management of diabetes has been well established (1). Previous reviews have provided comprehensive recommendations for MNT in the management of diabetes (2,3). The goals of MNT are to 1 ) attain and maintain optimal blood glucose levels, a lipid and lipoprotein profile that reduces the risk of macrovascular disease, and blood pressure levels that reduce the risk for vascular disease; 2 ) prevent and treat the chronic complications of diabetes by modifying nutrient intake and lifestyle; 3 ) address individual nutrition needs, taking into account personal and cultural preferences and willingness to change; and 4 ) maintain the pleasure of eating by only limiting food choices when indicated by scientific evidence (4). The literature on nutrition as it relates to diabetes management is vast. We undertook the specific topic of the role of macronutrients, eating patterns, and individual foods in response to continued controversy over independent contributions of specific foods and macronutrients, independent of weight loss, in the management of diabetes. The position of the American Diabetes Association (ADA) on MNT is that each person with diabetes should receive an individualized eating plan (4). ADA has received numerous criticisms because it does not recommend one specific mix of macronutrients for everyone with diabetes. The previous literature review conducted by ADA in 2001 supported the idea that there was not one ideal macronutrient distribution for all people with diabetes. This review focuses on literature that has been published since that 2001 date (5). This systematic review will be one source of information considered when updating the current ADA Nutrition Position Statement (4). Other systematic reviews and key research studies that may not be included in this review will also be considered. When attempting to tease out the role of macronutrients from other dietary

Nutrition therapy recommendations for the management of adults with diabetes. Diabetes Care 2013;36:3821-3842

A healthful eating pattern, regular physical activity, and often pharmacotherapy are key components of diabetes management. For many individuals with diabetes, the most challenging part of the treatment plan is determining what to eat. It is the position of the American Diabetes Association (ADA) that there is not a “one-size-fits-all” eating pattern for individuals with diabetes. The ADA also recognizes the integral role of nutrition therapy in overall diabetes management and has historically recommended that each person with diabetes be actively engaged in self-management, education, and treatment planning with his or her health care provider, which includes the collaborative development of an individualized eating plan (1,2). Therefore, it is important that all members of the health care team be knowledgeable about diabetes nutrition therapy and support its implementation. This position statement on nutrition therapy for individuals living with diabetes replaces previous position statements, the last of which was published in 2008 (3). Unless otherwise noted, research reviewed was limited to those studies conducted in adults diagnosed with type 1 or type 2 diabetes. Nutrition therapy for the prevention of type 2 diabetes and for the management of diabetes complications and gestational diabetes mellitus is not addressed in this review. A grading system, developed by the ADA and modeled after existing methods, was utilized to clarify and codify the evidence that forms the basis for the recommendations (1) (Table 1). The level of evidence that supports each recommendation is listed after the recommendation using the letters A, B, C, or E. A table linking recommendations to evidence can be reviewed at http://professional.diabetes.org/nutrition. Members of the Nutrition Recommendations Writing Group Committee disclosed all potential financial conflicts of interest with industry. These disclosures were discussed at the onset of the position statement development process. Members of this committee, their employers,