University of Udine

About: University of Udine is a education organization based out in Udine, Italy. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 6745 authors who have published 20530 publications receiving 669088 citations. The organization is also known as: Università degli Studi di Udine & Universita degli Studi di Udine.

Density-Functional Perturbation Theory for Quasi-Harmonic Calculations

Abstract: Computer simulations allow for the investigation of many materials properties and processes that are not easily accessible in the laboratory. This is particularly true in the Earth sciences, where the relevant pressures and temperatures may be so extreme that no experimental techniques can operate at those conditions. Computer modeling is often the only source of information on the properties of materials that, combined with indirect evidence (such as seismic data), allows one to discriminate among competing planetary models. Many computer simulations are performed using effective interatomic potentials tailored to reproduce some experimentally observed properties of the materials being investigated. The remoteness of the physically interesting conditions from those achievable in the laboratory, as well as the huge variety of different atomic coordination and local chemical state occurring in the Earth interior, make the dependability of semi-empirical potentials questionable. First-principles techniques based on density-functional theory (DFT) (Hohenberg and Kohn 1964; Kohn and Sham 1965) are much more predictive, not being biased by any prior experimental input, and have demonstrated a considerable accuracy in a wide class of materials and variety of external conditions. The importance of thermal effects in the range of phenomena interesting to the Earth sciences makes a proper account of atomic motion essential. Traditionally, this is achieved using molecular dynamics techniques which have been successfully combined with DFT in the first-principles molecular dynamics technique of Car and Parrinello (1985). Well below the melting temperature, the numerical efficiency of molecular dynamics is limited by the lack of ergodicity, which would require long simulation times, and by the importance of long-wavelength collective motions (phonons), which would require large simulation cells. Both difficulties are successfully dealt with in the quasi-harmonic approximation (QHA) where the thermal properties of solid materials are traced back to those of a system of non-interacting …

Measurement of the muon reconstruction performance of the ATLAS detector using 2011 and 2012 LHC proton–proton collision data

Abstract: This paper presents the performance of the ATLAS muon reconstruction during the LHC run with pp collisions at root s = 7-8 TeV in 2011-2012, focusing mainly on data collected in 2012. Measurements ...

Search for dark matter candidates and large extra dimensions in events with a jet and missing transverse momentum with the ATLAS detector

Abstract: A search for new phenomena in events with a high-energy jet and large missing transverse momentum is performed using data from proton-proton collisions at root s = 7 TeV with the ATLAS experiment at the Large flatiron Collider. Four kinematic regions are explored using a dataset corresponding to an integrated luminosity of 4.7 fb(-1). No excess of events beyond expectations from Standard Model processes is observed, and limits are set on large extra dimensions and the pair production of dark matter particles.

Factors limiting maximal performance in humans.

Abstract: Theoretical best performance times (t theor) in track running are calculated as follows. Maximal metabolic power (Ė max) is a known function of maximal oxygen uptake (VO2max), of maximal anaerobic capacity (AnS) and of effort duration to exhaustion (t e): Ė max=f (t e). Metabolic power requirement (Ė r) to cover the distance (d) in the performance time t p is the product of the energy cost of locomotion per unit distance (C) and the speed: Ė r=C×d/t p. The time values for which Ė max (t e)=Ė r (t p), assumed to yield t theor, can be obtained for any given subject and distance provided that VO2max, AnS and C are known, and compared with actual best performances (t act). For 15 min≥t e≥100 s, the overall ratio t act/t theor was rather close to 1.0. To estimate the relative role of the different factors limiting VO2max, several resistances to O2 transport are identified, inversely proportional to: alveolar ventilation (R V*), O2 transport by the circulation (R Q), O2 diffusion from capillary blood to mitochondria (R t), mitochondrial capacity (R m). Observed changes of VO2max are accompanied by measured changes of several resistances. The ratio of each resistance to the overall resistance can therefore be calculated by means of the O2 conductance equation. In exercise with large muscle groups (two legs), R Q is the major (75%) limiting factor downstream of the lung, its role being reduced to 50% during exercise with small muscle groups (one leg). R t and R m account for the remaining fractions. In normoxia R V* is negligible; at high altitude it increases progressively, together with R t and R m, at the expense of R Q.

Ecology of Varroa destructor, the Major Ectoparasite of the Western Honey Bee, Apis mellifera

Abstract: Varroa destructor is the most important ectoparasite of Apis mellifera. This review addresses the interactions between the varroa mite, its environment, and the honey bee host, mediated by an impressive number of cues and signals, including semiochemicals regulating crucial steps of the mite's life cycle. Although mechanical stimuli, temperature, and humidity play an important role, chemical communication is the most important channel. Kairomones are used at all stages of the mite's life cycle, and the exploitation of bees' brood pheromones is particularly significant given these compounds function as primer and releaser signals that regulate the social organization of the honey bee colony. V. destructor is a major problem for apiculture, and the search for novel control methods is an essential task for researchers. A detailed study of the ecological interactions of V. destructor is a prerequisite for creating strategies to sustainably manage the parasite.