University of Perugia

About: University of Perugia is a education organization based out in Perugia, Umbria, Italy. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 13365 authors who have published 39516 publications receiving 1265601 citations. The organization is also known as: Universitá degli Studi di Perugia & Universita degli Studi di Perugia.

Searches for long-lived charged particles in pp collisions at sqrt(s) = 7 and 8 TeV

Abstract: Results of searches for heavy stable charged particles produced in pp collisions at sqrt(s) = 7 and 8 TeV are presented corresponding to an integrated luminosity of 5.0 inverse femtobarns and 18.8 inverse femtobarns, respectively. Data collected with the CMS detector are used to study the momentum, energy deposition, and time-of-flight of signal candidates. Leptons with an electric charge between e/3 and 8e, as well as bound states that can undergo charge exchange with the detector material, are studied. Analysis results are presented for various combinations of signatures in the inner tracker only, inner tracker and muon detector, and muon detector only. Detector signatures utilized are long time-of-flight to the outer muon system and anomalously high (or low) energy deposition in the inner tracker. The data are consistent with the expected background, and upper limits are set on the production cross section of long-lived gluinos, scalar top quarks, and scalar tau leptons, as well as pair produced long-lived leptons. Corresponding lower mass limits, ranging up to 1322 GeV for gluinos, are the most stringent to date.

Wide-field choroidal thickness profile in healthy eyes.

Abstract: The introduction of wide field optical coherence tomography (WF-OCT) has provided newer insights in the imaging of peripheral choroid. We evaluated choroidal thickness (CT) and large choroidal vessel thickness (LCVT) of 20 eyes in horizontal and vertical meridians using WF-OCT. A high-definition line scan through the fovea in both horizontal and vertical meridian was captured in primary and extremes of gaze to obtain scans up to mid-equator. CT and LCVT measurements were done across predefined points in macular area and all quadrants. LCVT was calculated after identifying a large choroidal vessel near choroidoscleral interface. The main outcome measures were differences in CT and LCVT in macular and four quadrants. Mean CT (331.23 ± 76.34 µ) and LCVT (201.46 ± 54.31 µ) in vertical macular segment were significantly more than CT (245.79 ± 55.38 µ; p = 0.0002) and LCVT (150.48 ± 52.58 µ; p = 0.004) in horizontal macular segment. CT at peripheral points in all quadrants was significantly reduced as compared to subfoveal CT (all p values < 0.05) with maximum reduction in inferior quadrant (64.5%). Using linear regression, only quadrant had a significant effect on CT and LCVT (both p < 0.001). CT and LCVT are highest at the macular area with reduction towards the periphery. The contribution of LCVT to CT is less at the fovea compared to other peripheral points.

New and original pKa prediction method using grid molecular interaction fields.

Abstract: One of the most important physicochemical properties of a molecule is pKa. It is known that two parameters imperative in ADME profiling, solubility, and lipophilicity are governed by pKa, and receptor binding can be influenced by pKa. Because most drugs are ionized in physiological conditions, pKa is particularly relevant to medicinal chemistry. Despite the numerous advances in high-throughput measurements, in silico determination is still the fastest and cheapest way of obtaining pKa. This paper presents a new original computational method for pKa prediction of organic compounds. Descriptors were generated using the program GRID, and these descriptors are based on molecular interaction fields precomputed on a set of molecular fragments. The new method was developed, trained, and cross-validated by using a large and diverse data set of 24 617 pKa values. This paper presents the results for a class of 421 acidic nitrogen compounds (RMSE = 0.41, r2 = 0.97, q2 = 0.87) and for a class of 947 six-membered N-he...

Formation of complex organic molecules in cold objects: the role of gas-phase reactions

Abstract: While astrochemical models are successful in reproducing many of the observed interstellar species, they have been struggling to explain the observed abundances of complex organic molecules. Current models tend to privilege grain surface over gas phase chemistry in their formation. One key assumption of those models is that radicals trapped in the grain mantles gain mobility and react on lukewarm (>30 K) dust grains. Thus, the recent detections of methyl formate (MF) and dimethyl ether (DME) in cold objects represent a challenge and may clarify the respective role of grain surface and gas phase chemistry. We propose here a new model to form DME and MF with gas phase reactions in cold environments, where DME is the precursor of MF via an efficient reaction overlooked by previous models. Furthermore, methoxy, a precursor of DME, is also synthetized in the gas phase from methanol, which is desorbed by a non-thermal process from the ices. Our new model reproduces fairy well the observations towards L1544. It also explains, in a natural way, the observed correlation between DME and MF. We conclude that gas phase reactions are major actors in the formation of MF, DME and methoxy in cold gas. This challenges the exclusive role of grain-surface chemistry and favours a combined grain-gas chemistry.