3,734 research outputs found
Some remarks on PM2.5
Since 1970, the General Physics Department of «Università degli Studi di Torino» has carried out a project research, on inorganic solid particulate matter. The special issue of Annals of Geophysics, published for Professor Giorgio Fioccos 70th birthday, gives us the possibility to make some important remarks on this topic, focusing on PM2.5. This has been possible using all the old and new experimental data of the measures made by the authors of this paper since 1970
Intense events of rainfalls in Piemonte
The possibility of studying the precipitations recorded in a large number of meteorological stations in Piemonte
led us to analyse what has happened in the last century. A comparison between periods of 10-20 years, using an arbitrary index of rainfall, shows an increase in intense events in the last 20 years though we can observe a general reduction, in absolute value, of the quantity of rain. It is shown that, in the last 30 years, there has been a change in the granulometric distribution of Suspended Particulate Matter (SPM) which, in standard conditions, might
become Condensation Nuclei (CN). This might have infl uenced condensation phenomenon, causing a greater frequency of intense events
Response of Contrasting Cocksfoot Varieties to Summer Moisture Availability in a Mediterranean Environment
The responsiveness to water availability in summer and the effect of summer drought were assessed in a Mediterranean environment on both temperate and Mediterranean cocksfoot (Dactylis glomerata L.) materials. Three consecutive evaluation phases were contemplated: i) under rainfed conditions from autumn to spring; ii) under contrasting moisture conditions in the following summer; and iii) under rainfed conditions in the subsequent autumn-spring season to assess the effect of the previous summer treatments. The ability to become summer dormant under conducive conditions, such as in Mediterranean germplasm, proved a plant pre-requisite for survival under drought. All the “summer-active”, temperate varieties did not survive drought stress. Mediterranean materials showed a facultative dormancy behaviour in that they responded to moisture availability in summer. There was evidence that selection for such responsiveness was effective, as shown by a variety selected from Mediterranean germplasm also considering this criterion. Forcing summer growth by preventing dormancy had little detrimental effect on subsequent autumn recovery of Mediterranean improved varieties but more evidence is required on this aspect
Critical Current Oscillations in Strong Ferromagnetic Pi-Junctions
We report magnetic and electrical measurements of Nb Josephson junctions with
strongly ferromagnetic barriers of Co, Ni and Ni80Fe20 (Py). All these
materials show multiple oscillations of critical current with barrier thickness
implying repeated 0-pi phase-transitions in the superconducting order
parameter. We show in particular that the Co barrier devices can be accurately
modelled using existing clean limit theories and so that, despite the high
exchange energy (309 meV), the large IcRN value in the pi-state means Co
barriers are ideally suited to the practical development of superconducting
pi-shift devices.Comment: 4 pages 3 figures 1 table. Revised version as accepted for
publication. To appear in Physical Review Letter
X-ray follow-ups of XSSJ12270-4859: a low-mass X-ray binary with gamma ray FERMI-LAT association
XSSJ1227.0-4859 is a peculiar, hard X-ray source recently positionally
associated to the Fermi-LAT source 1FGLJ1227.9-4852/2FGLJ1227.7-4853.
Multi-wavelength observations have added information on this source, indicating
a low-luminosity low-mass X-ray binary (LMXB), but its nature is still unclear.
To progress in our understanding, we present new X-ray data from a monitoring
campaign performed in 2011 with the XMM-Newton, RXTE, and Swift satellites and
combine them with new gamma-ray data from the Fermi and AGILE satellites. We
complement the study with simultaneous near-UV photometry from XMM-Newton and
with previous UV/optical and near-IR data. The X-ray history of XSSJ1227.0-4859
over 7yr shows a persistent and rather stable low-luminosity (~6x10^33
d_{1\,kpc}^2 erg/s) source, with flares and dips being peculiar and permanent
characteristics. The associated Fermi-LAT source 2FGLJ1227.7-4853 is also
stable over an overlapping period of 4.7\,yr. Searches for X-ray fast
pulsations down to msec give upper limits to pulse fractional amplitudes of
15-25% that do not rule out a fast spinning pulsar. The combined
UV/optical/near-IR spectrum reveals a hot component at ~13\,kK and a cool one
at ~4.6\,kK. The latter would suggest a late-type K2-K5 companion star, a
distance range of1.4--3.6kpc and an orbital period of 7--9 h. A near-UV
variability (>6\,h) also suggests a longer orbital period than previously
estimated. The analysis shows that the X-ray and UV/optical/near-IR emissions
are more compatible with an accretion-powered compact object than with a
rotational powered pulsar. The X-ray to UV bolometric luminosity ratio could be
consistent with a binary hosting a neutron star, but the uncertainties in the
radio data may also allow an LMXB black hole with a compact jet. In this case
it would be the first associated with a high-energy gamma-ray source.Comment: 17 pages, 14 figures, 1 table; Accepted for publication in Astronomy
& Astrophysics Main Journa
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