196,177 research outputs found
Nitrogen fractionation across the Galaxy: Observations of the 14N/15N ratio in a large sample of high-mass star-forming cores
No full textWe have measured the 14N/15N ratio in a sample of 27 high-mass star
forming cores, from observations of HCN(1-0) and HNC(1-0) (Colzi et al.
2017a, in press.). The observations were done with the IRAM-30m
Telescope that is a single-dish Radiotelescope and one of the best
existing radio-millimeter telescopes. Surprisingly, we have found values
that are distributed remarkably well around that of the PSN (about 441).
Moreover, these sources were divided into the three main evolutionary
categories of the high-mass star formation process: 11 high-mass
starless cores, 9 high-mass protostellar objects and 7 ultracompact HII
regions. This study shows that the chemical evolution does not seem to
play a role in the fractionation of nitrogen.
Afterwards we have decided to implement the sample by an even larger
sample of this kind of sources (about 90 in total) observed also with
IRAM 30-m. We have computed the 14N/15N ratios from the same molecules
and we have confirmed that these ratios in these high-mass sources, for
these two molecules, are concentrated from about 270 (value measured for
the terrestrial atmosphere) and about 441 (Colzi et al., in prep).
Thanks to the very large sample and the fact that these sources span a
wide range of distances from the Galactic center, we have decided also
to search for a Galactocentric gradient, and this will be the first for
14N/15N with such a robust statistics
TERAPIA DELL’EMBOLIA POLMONARE IN PAZIENTE CON ANEURISMA DISSECANTE DELL’AORTA ADDOMINALE
No full textNitrogen fractionation in high-mass star-forming cores across the Galaxy
No full textThe fractionation of nitrogen (N) in star-forming regions is a poorly understood process. To put more stringent observational constraints on the N-fractionation, we have observed with the IRAM-30-m telescope a large sample of 66 cores in massive star-forming regions. We targeted the (1-0) rotational transition of HN13C, HC15N, H13CN and HC15N, and derived the 14N/15N ratio for both HCN and HNC. We have completed this sample with that already observed by Colzi et al., and thus analysed a total sample of 87 sources. The 14N/15N ratios are distributed around the Proto-Solar Nebula value with a lower limit near the TA value (∼272). We have also derived the 14N/15N ratio as a function of the Galactocentric distance and deduced a linear trend based on unprecedented statistics. The Galactocentric dependences that we have found are consistent, in the slope, with past works but we have found a new local 14N/15N value of ∼400, i.e. closer to the Prosolar Nebula value. A second analysis was done, and a parabolic Galactocentric trend was found. Comparison with Galactic chemical evolution models shows that the slope until 8 kpc is consistent with the linear analysis, while the flattening trend above 8 kpc is well reproduced by the parabolic analysis
A vehicle-user matching tool to encourage electric mobility
No full textElectric vehicles (EVs) are recognized to be an effective way to reduce global warming pollution. Therefore, there is an increasing interest and effort in developing new ideas and technology to spread the use of EVs as an alternative to conventional cars. However, the consumers' perception of EVs, especially concerning their limited and not-fully predictable range, is still of low reliability, thus the number of sales is increasing slower than expected. In this paper, a software tool for non-EVs owners is presented, with the aim of profiling the drivers and show which EV alternative, if any, would be suitable for each case. The final goal is to encourage electric mobility against range anxiety. The whole analysis is carried out by using experimental data collected from some users in Milan, Italy
Technical and economic analysis of EV high-power recharging pools equipped with storage
No full textA comprehensive network of high-power recharging points will be fundamental to enable long-distance travel for electric vehicles. However, the distribution grid may not be always capable to provide such high levels of power in every area. From this prospect, recharging pools equipped with battery storage system provide the opportunity to limit the maximum power request to the grid, avoiding the need for an upgrade to the grid connection. This solution can be implemented by means of various configuration depending on the storage system size and the relative energy management, leading to different costs. This paper carries out a technical and economic analysis of a high-power recharging pool connected to the low voltage distribution network and equipped with a stationary storage system. A simulation model developed in Modelica language is used to compare three different storage configurations. Results indicate that a peak shaving BESS is the most feasible solution. It is also observed that a reduced size would improve the profitability of the investment, supporting the EV recharge with a reasonable additional waiting time
Dolore Toracico non traumatico. Attività del 2010 dell’Unità Operativa Semplice Chest Pain Unit dell’Azienda Policlinico Umberto I di Roma
No full textDr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Production of large Bose-Einstein condensates in a magnetic-shield-compatible hybrid trap
No full textWe describe the production of large Na-23 Bose-Einstein condensates in a hybrid trap characterized by a weak magnetic field quadrupole and a tightly focused infrared beam. The use of small magnetic field gradients makes the trap compatible with the state-of-the-art magnetic shields. By taking advantage of the deep cooling and high efficiency of gray molasses to improve the initial trap loading conditions, we produce condensates composed of as many as 7 million atoms in less than 30 s
EFFECT OF TAURO-URSODEOXYCHOLIC ACID ON SERUM ENZYME LEVELS IN PATIENTS WITH CHRONIC ACTIVE HEPATITIS
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