Star Formation in Galaxies Along the Hubble Sequence

Observations of star formation rates (SFRs) in galaxies provide vital clues to the physical nature of the Hubble sequence, and are key probes of the evolutionary properties of galaxies. The focus of this review is on the broad patterns in the star formation properties of galaxies along the Hubble sequence, and their implications for understanding galaxy evolution and the physical processes that drive the evolution. Star formation in the disks and nuclear regions of galaxies are reviewed separately, then discussed within a common interpretive framework. The diagnostic methods used to measure SFRs are also reviewed, and a self-consistent set of SFR calibrations is presented as an aid to workers in the field.Comment: 41 pages, with 9 figures. To appear in Volume 36 of the Annual Review of Astronomy and Astrophysic

A dominant population of optically invisible massive galaxies in the early Universe

International audienceOur current knowledge of cosmic star-formation history during the first two billion years (corresponding to redshift z > 3) is mainly based on galaxies identified in rest-frame ultraviolet light 1 . However, this population of galaxies is known to under-represent the most massive galaxies, which have rich dust content and/or old stellar populations. This raises the questions of the true abundance of massive galaxies and the star-formation-rate density in the early Universe. Although several massive galaxies that are invisible in the ultraviolet have recently been confirmed at early epochs 2$^{–}$4 , most of them are extreme starburst galaxies with star-formation rates exceeding 1,000 solar masses per year, suggesting that they are unlikely to represent the bulk population of massive galaxies. Here we report submillimetre (wavelength 870 micrometres) detections of 39 massive star-forming galaxies at z > 3, which are unseen in the spectral region from the deepest ultraviolet to the near-infrared. With a space density of about 2 × 10$^{−5}$ per cubic megaparsec (two orders of magnitude higher than extreme starbursts 5 ) and star-formation rates of 200 solar masses per year, these galaxies represent the bulk population of massive galaxies that has been missed from previous surveys. They contribute a total star-formation-rate density ten times larger than that of equivalently massive ultraviolet-bright galaxies at z > 3. Residing in the most massive dark matter haloes at their redshifts, they are probably the progenitors of the largest present-day galaxies in massive groups and clusters. Such a high abundance of massive and dusty galaxies in the early Universe challenges our understanding of massive-galaxy formation

Fundamental cosmological observations and data interpretation

ISBN 978364200791

Analysis of midwall shortening reveals high prevalence of left ventricular myocardial dysfunction in patients with diabetes mellitus: the DYDA study.

Individuals with diabetes mellitus (DM) have a higher risk to develop heart failure. Clinical guidelines emphasize the importance of early diagnosis of left ventricular dysfunction (LVD) and preventive interventions in these patients. In this study we assessed the prevalence of LVD, systolic or diastolic, in DM patients without known cardiac disease recruited in the 'left ventricular DYsfunction in DiAbetes (DYDA)' study. DESIGN AND METHODS: We performed clinical, ECG, laboratory, and echocardiographic exams in 960 patients (61 ± 8 years, 59% hypertensive) recruited in the DYDA study from 37 Italian diabetes referral centres. ECG and echo exams were read in central facilities. Systolic LVD was defined as ejection fraction ≤ 50% or midwall shortening (MFS) ≤ 15%. Diastolic LVD was identified when transmitral E/A was out of the range of 0.75-1.5 or deceleration time of mitral E wave ≤ 140 msec. RESULTS: Echocardiographic data were obtained in 751 patients (78.2%). Isolated systolic LVD was detected in 22.0% of patients, isolated diastolic LVD in 21.5%, and combined systolic and diastolic LVD in 12.7%. All patients with systolic LVD had MFS ≤ 15%, while only 9% had an ejection fraction ≤ 50%. Higher LV mass, relative wall thickness, prevalence of concentric geometry, and LV hypertrophy characterized the patients with LVD. CONCLUSIONS: LVD is present in more than half of DM patients without clinically detectable cardiac disease and is associated with LV hypertrophy and concentric LV geometry. One-third of patients exhibits systolic LVD detectable at the midwall level

Inappropriately high left ventricular mass in patients with type 2 diabetes mellitus and no overt cardiac disease. The DYDA study

An inappropriately high left ventricular mass (iLVM) may be detected in patients with diabetes mellitus. Several hemodynamic and nonhemodynamic factors stimulating LVM growth may actively operate in these patients. In this study, we assessed prevalence and factors associated with iLVM in patients with diabetes mellitus. METHODS: We analyzed baseline data from 708 patients (61 ± 7 years, 57% treated for hypertension) with type 2 diabetes mellitus without evidence of cardiac disease enrolled in the left ventricular dysfunction in diabetes study. iLVM was diagnosed by Doppler echocardiography as LVM more than 28% of the expected LVM predicted from height, sex and stroke work. RESULTS: iLVM was detected in 166 patients (23%), irrespective of concomitant hypertension. Patients with iLVM were more frequently women, had higher BMI and prevalence of metabolic syndrome, higher serum triglyceride levels and were treated more frequently with metformin and diuretics. In a multivariate model, female sex [odds ratio (OR) 1.502 (95% confidence interval (CI) 1.010-2.231), P = 0.04], higher serum triglyceride levels [OR 1.007 (95% CI 1.003-1.012), P < 0.001] and BMI [OR 1.220 (95% CI 1.116-1.335), P < 0.001] emerged independently related to iLVM. CONCLUSION: iLVM is detectable in about a quarter of patients with type 2 diabetes mellitus without evidence of cardiac disease and is unrelated to blood pressure levels. The association between LVM and some components of metabolic syndrome in these patients may have important practical implications. PMID: 21881524 [PubMed - indexed for MEDLINE