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

Use of Hydralazine‐Isosorbide Dinitrate Combination in African American and Other Race/Ethnic Group Patients With Heart Failure and Reduced Left Ventricular Ejection Fraction

Background: Hydralazine‐isosorbide dinitrate (H‐ISDN) therapy is recommended for African American patients with moderate to severe heart failure with reduced ejection fraction (<40%) (HFrEF), but use, temporal trends, and clinical characteristics associated with H‐ISDN therapy in clinical practice are unknown. Methods and Results: An observational analysis of 54 622 patients admitted with HFrEF and discharged home from 207 hospitals participating in the Get With The Guidelines–Heart Failure registry from April 2008 to March 2012 was conducted to assess prescription, trends, and predictors of use of H‐ISDN among eligible patients. Among 11 185 African American patients eligible for H‐ISDN therapy, only 2500 (22.4%) received H‐ISDN therapy at discharge. In the overall eligible population, 5115 of 43 498 (12.6%) received H‐ISDN at discharge. Treatment rates increased over the study period from 16% to 24% among African Americans and from 10% to 13% among the entire HFrEF population. In a multivariable model, factors associated with H‐ISDN use among the entire cohort included younger age; male sex; African American/Hispanic ethnicity; and history of diabetes, hypertension, anemia, renal insufficiency, higher systolic blood pressure, and lower heart rate. In African American patients, these factors were similar; in addition, being uninsured was associated with lower use. Conclusions: Overall, few potentially eligible patients with HFrEF are treated with H‐ISDN, and among African‐Americans fewer than one‐fourth of eligible patients received guideline‐recommended H‐ISDN therapy. Improved ways to facilitate use of H‐ISDN therapy in African American patients with HFrEF are needed

Hospital Variation and Characteristics of Implantable Cardioverter-Defibrillator Use in Patients With Heart Failure Data From the GWTG-HF (Get With The Guidelines–Heart Failure) Registry

ObjectivesThe aim of this study was to describe hospital variation and factors associated with adherence to guidelines for implantable cardioverter-defibrillator (ICD) therapy.BackgroundStudies have shown incomplete application of ICD therapy in eligible heart failure (HF) patients.MethodsNew or discharge prescription rates for ICD therapy (ejection fraction ≤30% without documented ICD contraindications) for hospitals were calculated from participants in the GWTG-HF (Get With The Guidelines–Heart Failure) registry during January 2005 to June 2007. With hierarchical modeling, hospitals' patient case-mix adjusted ICD rate and hospital factors associated with ICD use were determined. The association of ICD rate and other quality of care indicators and procedure use was determined.ResultsOverall use of ICD in-hospital or planned implantation rate was 20%. This rate ranged widely among hospitals, from 1% among the lowest tertile to 35% among the top tertile (p < 0.01). After adjusting for patient case mix, independent hospital characteristics associated with higher ICD use were percutaneous coronary intervention, coronary artery bypass grafting, and heart transplant capability as well as larger hospital bed size (p < 0.01). Hospital Centers for Medicare and Medicaid Services/Joint Commission on the Accreditation of Healthcare Organizations performance measures (discharge instructions, angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker use, smoking cessation; p ≥ 0.05) were similar across ICD, whereas higher ICD-rate hospitals had higher adherence to GWTG-HF performance measures (beta-blocker use, evidence-based beta-blocker use, aldosterone-antagonist, hydralazine/nitrate; p < 0.05) except warfarin in patients with atrial fibrillation (p = 0.18).ConclusionsThere is significant unexplained hospital variation in the use of ICD therapy among potentially eligible HF patients. However, hospitals that use ICD therapy more often also have more rapidly adopted other newer evidence-based HF therapies

Incremental Reduction in Risk of Death Associated with Use of Guideline-Recommended Therapies in Patients with Heart Failure: A Nested Case-Control Analysis of IMPROVE HF

Background: Several therapies are guideline-recommended to reduce mortality in patients with heart failure (HF) and reduced left ventricular ejection fraction, but the incremental clinical effectiveness of these therapies has not been well studied. We aimed to evaluate the individual and incremental benefits of guideline-recommended HF therapies associated with 24-month survival. Methods and results: We performed a nested case-control study of HF patients enrolled in IMPROVE HF. Cases were patients who died within 24 months and controls were patients who survived to 24 months, propensity-matched 1:2 for multiple prognostic variables. Logistic regression was performed, and the attributable mortality risk from incomplete application of each evidence-based therapy among eligible patients was calculated. A total of 1376 cases and 2752 matched controls were identified. β-Blocker and cardiac resynchronization therapy were associated with the greatest 24-month survival benefit (adjusted odds ratio for death 0.42, 95% confidence interval (CI), 0.34–0.52; and 0.44, 95% CI, 0.29–0.67, respectively). Angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, implantable cardioverter-defibrillators, anticoagulation for atrial fibrillation, and HF education were also associated with benefit, whereas aldosterone antagonist use was not. Incremental benefits were observed with each successive therapy, plateauing once any 4 to 5 therapies were provided (adjusted odds ratio 0.31, 95% CI, 0.23–0.42 for 5 or more versus 0/1, P<0.0001). Conclusions: Individual, with a single exception, and incremental use of guideline-recommended therapies was associated with survival benefit, with a potential plateau at 4 to 5 therapies. These data provide further rationale to implement guideline-recommended HF therapies in the absence of contraindications to patients with HF and reduced left ventricular ejection fraction

Spitzer observations of a 24 micron shadow: Bok Globule CB190

We present Spitzer observations of the dark globule CB190 (L771). We observe a roughly circular 24 micron shadow with a 70 arcsec radius. The extinction profile of this shadow matches the profile derived from 2MASS photometry at the outer edges of the globule and reaches a maximum of ~32 visual magnitudes at the center. The corresponding mass of CB190 is ~10 Msun. Our 12CO and 13CO J = 2-1 data over a 10 arcmin X 10 arcmin region centered on the shadow show a temperature ~10 K. The thermal continuum indicates a similar temperature for the dust. The molecular data also show evidence of freezeout onto dust grains. We estimate a distance to CB190 of 400 pc using the spectroscopic parallax of a star associated with the globule. Bonnor-Ebert fits to the density profile, in conjunction with this distance, yield xi_max = 7.2, indicating that CB190 may be unstable. The high temperature (56 K) of the best fit Bonnor-Ebert model is in contradiction with the CO and thermal continuum data, leading to the conclusion that the thermal pressure is not enough to prevent free-fall collapse. We also find that the turbulence in the cloud is inadequate to support it. However, the cloud may be supported by the magnetic field, if this field is at the average level for dark globules. Since the magnetic field will eventually leak out through ambipolar diffusion, it is likely that CB190 is collapsing or in a late pre-collapse stage.Comment: 16 pages, 13 figures, accepted for publication in Ap

Influence of Beta-Blocker Continuation or Withdrawal on Outcomes in Patients Hospitalized With Heart Failure Findings From the OPTIMIZE-HF Program

ObjectivesThis study ascertains the relationship between continuation or withdrawal of beta-blocker therapy and clinical outcomes in patients hospitalized with systolic heart failure (HF).BackgroundWhether beta-blocker therapy should be continued or withdrawn during hospitalization for decompensated HF has not been well studied in a broad cohort of patients.MethodsThe OPTIMIZE-HF (Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure) program enrolled 5,791 patients admitted with HF in a registry with pre-specified 60- to 90-day follow-up at 91 academic and community hospitals throughout the U.S. Outcomes data were prospectively collected and analyzed according to whether beta-blocker therapy was continued, withdrawn, or not started.ResultsAmong 2,373 patients eligible for beta-blockers at discharge, there were 1,350 (56.9%) who were receiving beta-blockers before admission and continued on therapy, 632 (26.6%) newly started, 79 (3.3%) in which therapy was withdrawn, and 303 (12.8%) eligible but not treated. Continuation of beta-blockers was associated with a significantly lower risk and propensity adjusted post-discharge death (hazard ratio [HR]: 0.60; 95% confidence interval [CI]: 0.37 to 0.99, p = 0.044) and death/rehospitalization (odds ratio: 0.69; 95% CI: 0.52 to 0.92, p = 0.012) compared with no beta-blocker. In contrast, withdrawal of beta-blocker was associated with a substantially higher adjusted risk for mortality compared with those continued on beta-blockers (HR: 2.3; 95% CI: 1.2 to 4.6, p = 0.013), but with similar risk as HF patients eligible but not treated with beta-blockers.ConclusionsThe continuation of beta-blocker therapy in patients hospitalized with decompensated HF is associated with lower post-discharge mortality risk and improved treatment rates. In contrast, withdrawal of beta-blocker therapy is associated with worse risk and propensity-adjusted mortality. (Organized Program To Initiate Lifesaving Treatment In Hospitalized Patients With Heart Failure [OPTIMIZE-HF]; NCT00344513

Has carbohydrate-restriction been forgotten as a treatment for diabetes mellitus? A perspective on the ACCORD study design

Prior to the discovery of medical treatment for diabetes, carbohydrate-restriction was the predominant treatment recommendation to treat diabetes mellitus. In this commentary we argue that carbohydrate-restriction should be reincorporated into contemporary treatment studies for diabetes mellitus

Chemistry and Dynamics in Pre-Protostellar Cores

We have compared molecular line emission to dust continuum emission and modeled molecular lines using Monte Carlo simulations in order to study the depletion of molecules and the ionization fraction in three preprotostellar cores, L1512, L1544, and L1689B. L1512 is much less dense than L1544 and L1689B, which have similar density structures. L1689B has a different environment from those of L1512 and L1544. We used density and temperature profiles, calculated by modeling dust continuum emission in the submillimeter, for modeling molecular line profiles. In addition, we have used molecular line profiles and maps observed in several different molecules toward the three cores. We find a considerable diversity in chemical state among the three cores. The molecules include those sensitive to different timescales of chemical evolution such as CCS, the isotopes of CO and HCO+, DCO+, and N2H+. The CO molecule is significantly depleted in L1512 and L1544, but not in L1689B. CCS may be in the second enhancement of its abundance in L1512 and L1544 because of the significant depletion of CO molecules. N2H+ might already start to be depleted in L1512, but it traces very well the distribution of dust emission in L1544. On the other hand, L1689B may be so young that N2H+ has not reached its maximum yet. The ionization fraction has been calculated using H13CO+ and DCO+. This study suggests that chemical evolution depends on the absolute timescale during which a core stays in a given environment as well as its density structure.Comment: 33 pages, 12 figures, accepted to Ap

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