From Classical Trajectories to Quantum Commutation Relations

In describing a dynamical system, the greatest part of the work for a theoretician is to translate experimental data into differential equations. It is desirable for such differential equations to admit a Lagrangian and/or an Hamiltonian description because of the Noether theorem and because they are the starting point for the quantization. As a matter of fact many ambiguities arise in each step of such a reconstruction which must be solved by the ingenuity of the theoretician. In the present work we describe geometric structures emerging in Lagrangian, Hamiltonian and Quantum description of a dynamical system underlining how many of them are not really fixed only by the trajectories observed by the experimentalist.Comment: 25 pages. Comments are welcome

Stopping of Charged Particles in a Magnetized Classical Plasma

The analytical and numerical investigations of the energy loss rate of the test particle in a magnetized electron plasma are developed on the basis of the Vlasov-Poisson equations, and the main results are presented. The Larmor rotation of a test particle in a magnetic field is taken into account. The analysis is based on the assumption that the energy variation of the test particle is much less than its kinetic energy. The obtained general expression for stopping power is analyzed for three cases: (i) the particle moves through a collisionless plasma in a strong homogeneous magnetic field; (ii) the fast particle moves through a magnetized collisionless plasma along the magnetic field; and (iii) the particle moves through a magnetized collisional plasma across a magnetic field. Calculations are carried out for the arbitrary test particle velocities in the first case, and for fast particles in the second and third cases. It is shown that the rate at which a fast test particle loses energy while moving across a magnetic field may be much higher than the loss in the case of motion through plasma without magnetic field.Comment: 14 pages, 3 figures, LaTe

The afterglow and host galaxy of GRB 090205: evidence for a Ly-alpha emitter at z=4.65

Gamma-ray bursts have been proved to be detectable up to distances much larger than any other astrophysical object, providing the most effective way, complementary to ordinary surveys, to study the high redshift universe. To this end, we present here the results of an observational campaign devoted to the study of the high-z GRB 090205. We carried out optical/NIR spectroscopy and imaging of GRB 090205 with the ESO-VLT starting from hours after the event up to several days later to detect the host galaxy. We compared the results obtained from our optical/NIR observations with the available Swift high-energy data of this burst. Our observational campaign led to the detection of the optical afterglow and host galaxy of GRB 090205 and to the first measure of its redshift, z=4.65. Similar to other, recent high-z GRBs, GRB 090205 has a short duration in the rest-frame with T_{90,rf}=1.6 s, which suggests the possibility that it might belong to the short GRBs class. The X-ray afterglow of GRB 090205 shows a complex and interesting behaviour with a possible rebrightening at 500-1000s from the trigger time and late flaring activity. Photometric observations of the GRB 090205 host galaxy argue in favor of a starburst galaxy with a stellar population younger than ~ 150 Myr. Moreover, the metallicity of Z > 0.27 Z_Sun derived from the GRB afterglow spectrum is among the highest derived from GRB afterglow measurement at high-z, suggesting that the burst occurred in a rather enriched envirorment. Finally, a detailed analysis of the afterglow spectrum shows the existence of a line corresponding to Lyman-alpha emission at the redshift of the burst. GRB 090205 is thus hosted in a typical Lyman-alpha emitter (LAE) at z=4.65. This makes the GRB 090205 host the farthest GRB host galaxy, spectroscopically confirmed, detected to date.Comment: Accepted for publication in Astronomy and Astrophysics; 8 pages, 7 figure

Simultaneous multiwavelength observations of the Low/Hard State of the X-ray transient source SWIFT J1753.5-0127

We report the results of simultaneous multiwavelength observations of the X-ray transient source SWIFT J1753.5-0127 performed with INTEGRAL, RXTE, NTT, REM and VLA on 2005 August 10-12. The source, which underwent an X-ray outburst since 2005 May 30, was observed during the INTEGRAL Target of Opportunity program dedicated to new X-ray novae located in the Galactic Halo. Broad-band spectra and fast timing variability properties of SWIFT J1753.5-0127 are analyzed together with the optical, near infra-red and radio data. We show that the source was significantly detected up to 600 keV with Comptonization parameters and timing properties typical of the so-called Low/Hard State of black hole candidates. We build a spectral energy distribution and we show that SWIFT J1753.5-0127 does not follow the usual radio/X-ray correlation of X-ray binaries in the Low/Hard State. We give estimates of distance and mass. We conclude that SWIFT J1753.5-0127 belongs to the X-ray nova class and that it is likely a black hole candidate transient source of the Galactic Halo which remained in the Low/Hard State during its main outburst. We discuss our results within the context of Comptonization and jet models.Comment: Accepted for publication in ApJ, 25 pages, 4 tables, 11 figures (3 in color

Preliminary results of a systematic review focusing on the effectiveness of the interventions in preventing the progression of frailty in older adults

uropean Union’s Health Programme - Project FOCUSpublishe

A Photometric Redshift of z ~ 9.4 for GRB 090429B

Gamma-ray bursts (GRBs) serve as powerful probes of the early universe, with their luminous afterglows revealing the locations and physical properties of star-forming galaxies at the highest redshifts, and potentially locating first-generation (Population III) stars. Since GRB afterglows have intrinsically very simple spectra, they allow robust redshifts from low signal-to-noise spectroscopy, or photometry. Here we present a photometric redshift of z ~ 9.4 for the Swift detected GRB 090429B based on deep observations with Gemini-North, the Very Large Telescope, and the GRB Optical and Near-infrared Detector. Assuming a Small Magellanic Cloud dust law (which has been found in a majority of GRB sight lines), the 90% likelihood range for the redshift is 9.06 7. The non-detection of the host galaxy to deep limits (Y(AB) ~ 28, which would correspond roughly to 0.001L* at z = 1) in our late-time optical and infrared observations with the Hubble Space Telescope strongly supports the extreme-redshift origin of GRB 090429B, since we would expect to have detected any low-z galaxy, even if it were highly dusty. Finally, the energetics of GRB 090429B are comparable to those of other GRBs and suggest that its progenitor is not greatly different from those of lower redshift bursts

"Frailty management optimisation through EIP AHA commitments and utilisation of stakeholders - FOCUS" - how can family doctors support our dementia carers?

publishe

The Optical SN 2012bz Associated with the Long GRB 120422A

The association of Type Ic SNe with long-duration GRBs is well established. We endeavor, through accurate ground-based observational campaigns, to characterize these SNe at increasingly high redshifts. We obtained a series of optical photometric and spectroscopic observations of the Type Ic SN2012bz associated with the Swift long-duration GRB120422A (z=0.283) using the 3.6-m TNG and the 8.2-m VLT telescopes. The peak times of the light curves of SN2012bz in various optical filters differ, with the B-band and i'-band light curves reaching maximum at ~9 and ~23 rest-frame days, respectively. The bolometric light curve has been derived from individual bands photometric measurements, but no correction for the unknown contribution in the near-infrared (probably around 10-15%) has been applied. Therefore, the present light curve should be considered as a lower limit to the actual UV-optical-IR bolometric light curve. This pseudo-bolometric curve reaches its maximum (Mbol = -18.56 +/- 0.06) at 13 +/- 1 rest-frame days; it is similar in shape and luminosity to the bolometric light curves of the SNe associated with z<0.2 GRBs and more luminous than those of SNe associated with XRFs. A comparison with the model generated for the bolometric light curve of SN2003dh suggests that SN2012bz produced only about 15% less 56Ni than SN2003dh, about 0.35 Msol. Similarly the VLT spectra of SN2012bz, after correction for Galactic extinction and for the contribution of the host galaxy, suggest comparable explosion parameters with those observed in SN2003dh (EK~3.5 x 10^52 erg, Mej~7 Msol) and a similar progenitor mass (~25-40 Msol). GRB120422A is consistent with the Epeak-Eiso and the EX,iso-Egamma,iso-E_peak relations. GRB120422A/SN2012bz shows the GRB-SN connection at the highest redshift so far accurately monitored both photometrically and spectroscopically.Comment: 7 pages, 6 figures, 2 tables, accepted for publication in Astronomy & Astrophysic

Characterization of the Prokaryotic Sodium Channel NavSp Pore with a Microfluidic Bilayer Platform

This paper describes the use of a newly-developed micro-chip bilayer platform to examine the electrophysiological properties of the prokaryotic voltage-gated sodium channel pore (NavSp) from Silicibacter pomeroyi. The platform allows up to 6 bilayers to be analysed simultaneously. Proteoliposomes were incorporated into suspended lipid bilayers formed within the microfluidic bilayer chips. The chips provide access to bilayers from either side, enabling the fast and controlled titration of compounds. Dose-dependent modulation of the opening probability by the channel blocking drug nifedipine was measured and its IC50 determined