Linking the fate of massive black hole binaries to the active galactic nuclei luminosity function

Massive black hole binaries are naturally predicted in the context of the hierarchical model of structure formation. The binaries that manage to lose most of their angular momentum can coalesce to form a single remnant. In the last stages of this process, the holes undergo an extremely loud phase of gravitational wave emission, possibly detectable by current and future probes. The theoretical effort towards obtaining a coherent physical picture of the binary path down to coalescence is still underway. In this paper, for the first time, we take advantage of observational studies of active galactic nuclei evolution to constrain the efficiency of gas-driven binary decay. Under conservative assumptions we find that gas accretion toward the nuclear black holes can efficiently lead binaries of any mass forming at high redshift (> 2) to coalescence within the current time. The observed "downsizing" trend of the accreting black hole luminosity function further implies that the gas inflow is sufficient to drive light black holes down to coalescence, even if they bind in binaries at lower redshifts, down to z~0.5 for binaries of ~10 million solar masses, and z~0.2 for binaries of ~1 million solar masses. This has strong implications for the detection rates of coalescing black hole binaries of future space-based gravitational wave experiments.Comment: 6 pages, 3 figure, accepted for publication in MNRA

The ATLAS Tile Calorimeter Test Beam Monitoring Program

During 2003 test beam session for ATLAS Tile Calorimeter a monitoring program has been developed to ease the setup of correct running condition and the assessment of data quality. The program has been built using the Online Software services provided by the ATLAS Online Software group. The first part of this note contains a brief overview of these services followed by the full description of Tile Calorimeter monitoring program architecture and features. Performances and future upgrades are discussed in the final part of this note.Comment: 11 pages, 8 figures, ATLAS TILECAL Not

Extending Geant4 Parallelism with External Libraries (MPI, TBB) and Its Use on HPC Resources

With Geant4 Version 10.0, released in December 2013, one of the most widely used Monte-Carlo codes has been ported to take full advantage of multi- and many-core CPUs thanks to the introduction of event-level parallelism via multithreading. In this paper we review recent developments to allow for a better integration of parallel Geant4 jobs with external libraries. We have chosen to develop examples using the popular Intel Threading Building Block (for short TBB) as an alternative parallelization approach to the native Geant4 POSIX. To simplify the scaling of a Geant4 application across nodes on a cluster we are improving the support of MPI in Geant4. In particular it is now possible to run an hybrid MPI/MT application that uses MPI to scale across nodes and MT to scale across cores. %The recent developments allow users to easily implement parallel application resources that scale on a very large number of nodes and cores typical of HPC resources.Comment: conferenc

Top Quark Mass determination at the ATLAS experiment using early data

The ATLAS experiment will start taking data at the end of 2007. During the very first data taking period it will be possible to make a preliminary measurement of the top quark mass in the semileptonic decay channel of ttbar events. A possible strategy to perform this measurement is presented with particular interest in the role of jet energy scale: a jet calibration algorithm is developed and results are discussed. A detailed discussion of test beam data is also presented together with comparisons of Monte Carlo predicions

Primary familial brain calcification: update on molecular genetics

Primary familial brain calcification is a neuropsychiatric disorder with calcium deposits in the brain, especially in basal ganglia, cerebellum and subcortical white matter. The disease is characterized by a clinical heterogeneity, with a various combination of symptoms that include movement disorders and psychiatric disturbances; asymptomatic patients have been also reported. To date, three causative genes have been found: SLC20A2, PDGFRB and PDGFB. SLC20A2 gene codes for the 'sodium-dependent phosphate transporter 2' (PiT-2), a cell membrane transporters of inorganic phosphate, involved in Pi uptake by cells and maintenance of Pi body levels. Over 40 pathogenic variants of SLC20A2 have been reported, affecting the regulation of Pi homeostasis. It was hypothesized that SLC20A2 mutations cause brain calcification most likely through haploinsufficiency. PDGFRB encodes for the platelet-derived growth factor receptor-β (PDGFRβ), a cell-surface tyrosine-kinase (RTK) receptor that regulates cell proliferation, migration, survival and differentiation. PDGFB encodes for the 'platelet-derived growth factor beta' (PDGFβ), the ligand of PDGFRβ. The loss of function of PDGFRβ and PDGFβ could lead to the impairment of the pericytes function and blood brain barrier integrity, causing vascular and perivascular calcium accumulation. SLC20A2 accounts for about 40 % of familial form and 14 % of sporadic cases, while PDGFRB and PDGFB mutations are likely rare. However, approximately 50 % of patients are not genetically defined and there should be at least another causative gene

Explorations of the viability of ARM and Xeon Phi for physics processing

We report on our investigations into the viability of the ARM processor and the Intel Xeon Phi co-processor for scientific computing. We describe our experience porting software to these processors and running benchmarks using real physics applications to explore the potential of these processors for production physics processing.Comment: Submitted to proceedings of the 20th International Conference on Computing in High Energy and Nuclear Physics (CHEP13), Amsterda

Reduced Graphene Oxide/Waste-Derived TiO2 Composite Membranes: Preliminary Study of a New Material for Hybrid Wastewater Treatment

This work reports the preliminary results of the development of composite self-assembling membranes obtained by the combination of reduced graphene oxide (rGO) with commercial Degussa P25 titanium dioxide (TiO2). The purpose is to demonstrate the possibility of combining, in the same self-standing material, the capability to treat wastewater containing both inorganic and organic pollutants by exploiting the established ability of rGO to capture metal ions together with that of TiO2 to degrade organic substances. Moreover, this study also investigates the potential photocatalytic properties of tionite (TIO), to demonstrate the feasibility of replacing commercial TiO2 with such waste-derived TiO2-containing material, fulfilling a circular economy approach. Thus, rGO–TiO2 and rGO–TIO composite membranes, 1:1 by weight, were prepared and characterized by SEM-EDX, XRD, thermogravimetry, as well as by Raman and UV-Vis spectroscopies to verify the effective and homogeneous integration of the two components. Then, they were tested towards 3-mg L−1 aqueous synthetic solutions of Fe3+ and Cu2+ ions to evaluate their metal adsorption ability, with values of the order of 0.1–0.2 mmol gmembrane−1, comparable or even slightly higher than those of pristine rGO. Finally, the ability of the composites to degrade a common organic pesticide, i.e., Imidacloprid®, was assessed in preliminary photocatalysis experiments, in which maximum degradation efficiencies of 25% (after 3 h) for rGO–TiO2 and of 21% (after 1 h) for rGO–TIO were found. The result of tionite-containing membranes is particularly promising and worthy of further investigation, given that the anatase content of tionite is roughly 1/6 of the one in commercial TiO2

Progression of brain atrophy in spinocerebellar ataxia type 2: A longitudinal tensor-based morphometry study

Spinocerebellar ataxia type 2 (SCA2) is the second most frequent autosomal dominant inherited ataxia worldwide. We investigated the capability of magnetic resonance imaging (MRI) to track in vivo progression of brain atrophy in SCA2 by examining twice 10 SCA2 patients (mean interval 3.6 years) and 16 age- and gender-matched healthy controls (mean interval 3.3 years) on the same 1.5 T MRI scanner. We used T1-weighted images and tensor-based morphometry (TBM) to investigate volume changes and the Inherited Ataxia Clinical Rating Scale to assess the clinical deficit. With respect to controls, SCA2 patients showed significant higher atrophy rates in the midbrain, including substantia nigra, basis pontis, middle cerebellar peduncles and posterior medulla corresponding to the gracilis and cuneatus tracts and nuclei, cerebellar white matter (WM) and cortical gray matter (GM) in the inferior portions of the cerebellar hemisphers. No differences in WM or GM volume loss were observed in the supratentorial compartment. TBM findings did not correlate with modifications of the neurological deficit. In conclusion, MRI volumetry using TBM is capable of demonstrating the progression of pontocerebellar atrophy in SCA2, supporting a possible role of MRI as biomarker in future trials