Star formation histories of dwarf galaxies from the Colour-Magnitude diagrams of their resolved stellar populations

In this tutorial paper we summarize how the star formation (SF) history of a galactic region can be derived from the colour-magnitude diagram (CMD) of its resolved stars. The procedures to build synthetic CMDs and to exploit them to derive the SF histories (SFHs) are described, as well as the corresponding uncertainties. The SFHs of resolved dwarf galaxies of all morphological types, obtained from the application of the synthetic CMD method, are reviewed and discussed. In short: 1) Only early-type galaxies show evidence of long interruptions in the SF activity; late-type dwarfs present rather continuous, or gasping, SF regimes; 2) A few early-type dwarfs have experienced only one episode of SF activity concentrated at the earliest epochs, whilst many others show extended or recurrent SF activity; 3) No galaxy experiencing now its first SF episode has been found yet; 4) No frequent evidence of strong SF bursts is found; 5) There is no significant difference in the SFH of dwarf irregulars and blue compact dwarfs, except for the current SF rates. Implications of these results on the galaxy formation scenarios are briefly discussed.Comment: 29 pages. Tutorial Review to appear in the special issue "Dwarf-Galaxy Cosmology" in Advances in Astronom

A software architecture for the analysis of large sets of data streams in cloud infrastructures

System management algorithms in private andpublic cloud infrastructures have to work with literally thousands of data streams generated from resource, applicationand event monitors. This cloud context opens two novel issuesthat we address in this paper: how to design a softwarearchitecture that is able to gather and analyze all informationwithin real-time constraints; how it is possible to reduce theanalysis of the huge collected data set to the investigationof a reduced set of relevant information. The application ofthe proposed architecture is based on the most advancedsoftware components, and is oriented to the classification of thestatistical behavior of servers and to the analysis of significantstate changes. These results guide model-driven managementsystems to investigate only relevant servers and to applysuitable decision models considering the deter

Real-time adaptive algorithm for resource monitoring

In large scale systems, real-time monitoring of hardware and software resources is a crucial means for any management purpose. In architectures consisting of thousands of servers and hundreds of thousands of component resources, the amount of data monitored at high sampling frequencies represents an overhead on system performance and communication, while reducing sampling may cause quality degradation. We present a real-time adaptive algorithm for scalable data monitoring that is able to adapt the frequency of sampling and data updating for a twofold goal: to minimize computational and communication costs, to guarantee that reduced samples do not affect the accuracy of information about resources. Experiments carried out on heterogeneous data traces referring to synthetic and real environments confirm that the proposed adaptive approach reduces utilization and communication overhead without penalizing the quality of data with respect to existing monitoring algorithms

Adaptive, scalable and reliable monitoring of big data on clouds

Real-time monitoring of cloud resources is crucial for a variety of tasks such as performance analysis, workload management, capacity planning and fault detection. Applications producing big data make the monitoring task very difficult at high sampling frequencies because of high computational and communication overheads in collecting, storing, and managing information. We present an adaptive algorithm for monitoring big data applications that adapts the intervals of sampling and frequency of updates to data characteristics and administrator needs. Adaptivity allows us to limit computational and communication costs and to guarantee high reliability in capturing relevant load changes. Experimental evaluations performed on a large testbed show the ability of the proposed adaptive algorithm to reduce resource utilization and communication overhead of big data monitoring without penalizing the quality of data, and demonstrate our improvements to the state of the art.Real-time monitoring of cloud resources is crucial for a variety of tasks such as performance analysis, workload management, capacity planning and fault detection. Applications producing big data make the monitoring task very difficult at high sampling frequencies because of high computational and communication overheads in collecting, storing, and managing information. We present an adaptive algorithm for monitoring big data applications that adapts the intervals of sampling and frequency of updates to data characteristics and administrator needs. Adaptivity allows us to limit computational and communication costs and to guarantee high reliability in capturing relevant load changes. Experimental evaluations performed on a large testbed show the ability of the proposed adaptive algorithm to reduce resource utilization and communication overhead of big data monitoring without penalizing the quality of data, and demonstrate our improvements to the state of the art

NGC 1817, NGC 2141 and Berkeley 81: three BOCCE clusters of intermediate age

In this paper we analyse the evolutionary status of three open clusters: NGC 1817, NGC 2141 and Berkeley 81. They are all of intermediate age, two are located in the Galactic anticentre direction while the third one is located in the Galactic Centre direction. All of them were observed with Large Binocular Camera at Large Binocular Telescope using the Bessel B, V and I filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram (CMD) method, i.e. the direct comparison of the observational CMDs with a library of synthetic CMDs generated with different evolutionary sets (Padova, FRANEC and FST). This analysis shows that NGC 1817 has subsolar metallicity, age between 0.8 and 1.2 Gyr, reddening E(B - V) in the range 0.21 and 0.34 and distance modulus (m - M)(0) of about 10.9; NGC 2141 is older, with age in the range 1.25 and 1.9 Gyr, E(B - V) between 0.36 and 0.45, (m - M)(0) between 11.95 and 12.21 and subsolar metallicity; Berkeley 81 has metallicity about solar, with age between 0.75 and 1.0 Gyr, has reddening E(B - V) similar to 0.90 and distance modulus (m - M)(0) similar to 12.4. Exploiting the large field of view of the instrument we derive the structure parameters for NGC 2141 and Berkeley 81 by fitting a King profile to the estimated density profile. Combining this information with the synthetic CMD technique we estimate a lower limit for the cluster total mass for these two systems

Electrospun Nanostructured Fibers of Collagen-Biomimetic Apatite on Titanium Alloy

Titanium and its alloys are currently the mainly used materials to manufacture orthopaedic implants due to their excellent mechanical properties and corrosion resistance. Although these materials are bioinert, the improvement of biological properties (e.g., bone implant contact) can be obtained by the application of a material that mimics the bone extracellular matrix. To this aim, this work describes a new method to produce nanostructured collagen-apatite composites on titanium alloy substrate, by combining electrospinning and biomimetic mineralization. The characterization results showed that the obtained mineralized scaffolds have morphological, structural, and chemical compositional features similar to natural bone extracellular matrix. Finally, the topographic distribution of the chemical composition in the mineralized matrix evaluated by Fourier Transform Infrared microspectroscopy demonstrated that the apatite nanocrystals cover the collagen fibers assembled by the electrospinning

Resolved photometry of young massive clusters in the starburst galaxy NGC 4214

We present the results of deep high-resolution imaging performed with Advanced Camera for Surveys (ACS)/HRC@HST in the most active region of the nearby starburst galaxy NGC 4214. We resolved the stellar populations of five young massive clusters and their surrounding galactic field. The star formation history of this region is characterized by two main bursts occurred within the last 500 Myr, with the oldest episode spread out across an area larger than that covered by the most recent one. The ages derived for the analysed clusters cover a wide range within 6.4 < log t/yr < 8.1 in agreement with those predicted by recent analyses based on integrated photometry. The comparison between the mass of the young associations and that of the surrounding field population with similar ages indicates a high cluster formation efficiency (Gamma similar to 33 per cent) which decreases when old populations are considered. The mass function of the major assembly has been found to be slightly flatter than the Salpeter law with a hint of mass segregation. We found no clear signatures of multiple stellar populations in the two young (log t/yr < 6.8) associations where we were able to resolve their innermost region. The masses and sizes of three clusters indicate that at least one of them could evolve towards a globular cluster-like structure

Increased Carotid Thickness in Subjects with Recently-Diagnosed Diabetes from Rural Cameroon

PMCID: PMC3423396This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Thalidomide-dexamethasone as induction therapy before autologous stem cell transplantation in patients with newly diagnosed multiple myeloma and renal insufficiency.

The aim of this study was to evaluate the efficacy and the toxicity of thalidomide-dexamethasone (Thal-Dex) as induction therapy before autologous peripheral blood stem cell (PBSC) transplantation in patients with newly diagnosed multiple myeloma (MM) with renal insufficiency. The study included 31 patients with a baseline creatinine clearance value ≤50 mL/min, 7 of whom required chronic hemodialysis. Patients received 4 months of Thal-Dex, followed by PBSC collection and subsequent transplantation. After induction, a partial response (PR) or greater was obtained in 23 patients (74%), including 8 (26%) who achieved a very good PR. Renal function improved more frequently in patients achieving a PR or greater (82%, vs 37% in patients achieving less than a PR; P = .04). Twenty-six patients underwent PBSC mobilization; in 17 of these patients (65%), >4 × 10 6 CD34 + cells/kg were collected. Double autologous transplantation was performed in 15 patients, and a single autologous transplantation was performed in 7 patients. After a median of 32 months of follow-up, median event-free survival was 30 months, and median survival was not determined. According to our data, Thal-Dex is effective and safe in patients with newly diagnosed MM and renal insufficiency. Given the relationship between recovery of renal function and response to induction treatment, more intensive Thal + bortezomib regimens could be explored to rescue higher numbers of patients

Three new bricks in the wall: Berkeley 23, Berkeley 31, and King 8

A comprehensive census of Galactic open cluster properties places unique constraints on the Galactic disc structure and evolution. In this framework we investigate the evolutionary status of three poorly-studied open clusters, Berkeley 31, Berkeley 23 and King 8, all located in the Galactic anti-centre direction. To this aim, we make use of deep LBT observations, reaching more than 6 mag below the main sequence Turn- Off. To determine the cluster parameters, namely age, metallicity, distance, reddening and binary fraction, we compare the observational colour-magnitude diagrams (CMDs) with a library of synthetic CMDs generated with different evolutionary sets (Padova, FRANEC and FST) and metallicities. We find that Berkeley 31 is relatively old, with an age between 2.3 and 2.9 Gyr, and rather high above the Galactic plane, at about 700 pc. Berkeley 23 and King 8 are younger, with best fitting ages in the range 1.1-1.3 Gyr and 0.8-1.3 Gyr, respectively. The position above the Galactic plane is about 500- 600 pc for the former, and 200 pc for the latter. Although a spectroscopic confirmation is needed, our analysis suggests a sub-solar metallicity for all three clusters.Comment: 17 Pages, Accepted for publication in MNRA