172 research outputs found

    Gravitational Faraday rotation in a weak gravitational field

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    We examine the rotation of the plane of polarization for linearly polarized light rays by the weak gravitational field of an isolated physical system. Based on the rotation of inertial frames, we review the general integral expression for the net rotation. We apply this formula, analogue to the usual electromagnetic Faraday effect, to some interesting astrophysical systems: uniformly shifting mass monopoles and a spinning external shell.Comment: 10 pages; accepted for publication in Phys. Rev.

    Polarized inclusive leptoproduction, NhX\ell N \to hX, and the hadron helicity density matrix, ρ(h)\rho(h): possible measurements and predictions

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    We discuss the production of hadrons in polarized lepton nucleon interactions and in the current jet fragmentation region; using the QCD hard scattering formalism we compute the helicity density matrix of the hadron and show how its elements, when measurable, can give information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. The cases of ρ\rho vector mesons and Λ\Lambda baryons are considered in more details and, within simplifying assumptions, some estimates are given.Comment: 17 pages + 4 figures, plain LATeX, figures appended as uuencoded, compressed postscript fil

    ALPGEN, a generator for hard multiparton processes in hadronic collisions

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    This paper presents a new event generator, ALPGEN, dedicated to the study of multiparton hard processes in hadronic collisions. The code performs, at the leading order in QCD and EW interactions, the calculation of the exact matrix elements for a large set of parton-level processes of interest in the study of the Tevatron and LHC data. The current version of the code describes the following final states: (W -> ffbar') QQbar+ N jets (Q being a heavy quark, and f=l,q), with N f fbar)+QQbar+Njets (f=l,nu), with N ffbar') + charm + N jets (f=l,q), N f fbar') + N jets (f=l,q) and (Z/gamma* -> f fbar)+ N jets (f=l,nu), with N<=6; nW+mZ+lH+N jets, with n+m+l+N<=8 and N<=3 including all 2-fermion decay modes of W and Z bosons, with spin correlations; Q Qbar+N jets (N b f fbar' decays and relative spin correlations included if Q=t; Q Qbar Q' Qbar'+N jets, with Q and Q' heavy quarks (possibly equal) and N b f fbar' decays and relative spin correlations included if Q=t; N jets, with N<=6. Parton-level events are generated, providing full information on their colour and flavour structure, enabling the evolution of the partons into fully hadronised final states.Comment: 1+38 pages, uses JHEP.cls. Documents code version 1.2: extended list of processes, updated documentation and bibliograph

    Accelerated Cosmological Models in First-Order Non-Linear Gravity

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    The evidence of the acceleration of universe at present time has lead to investigate modified theories of gravity and alternative theories of gravity, which are able to explain acceleration from a theoretical viewpoint without the need of introducing dark energy. In this paper we study alternative gravitational theories defined by Lagrangians which depend on general functions of the Ricci scalar invariant in minimal interaction with matter, in view of their possible cosmological applications. Structural equations for the spacetimes described by such theories are solved and the corresponding field equations are investigated in the Palatini formalism, which prevents instability problems. Particular examples of these theories are also shown to provide, under suitable hypotheses, a coherent theoretical explanation of earlier results concerning the present acceleration of the universe and cosmological inflation. We suggest moreover a new possible Lagrangian, depending on the inverse of sinh(R), which gives an explanation to the present acceleration of the universe.Comment: 23 pages, Revtex4 fil

    Conformal aspects of Palatini approach in Extended Theories of Gravity

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    The debate on the physical relevance of conformal transformations can be faced by taking the Palatini approach into account to gravitational theories. We show that conformal transformations are not only a mathematical tool to disentangle gravitational and matter degrees of freedom (passing from the Jordan frame to the Einstein frame) but they acquire a physical meaning considering the bi-metric structure of Palatini approach which allows to distinguish between spacetime structure and geodesic structure. Examples of higher-order and non-minimally coupled theories are worked out and relevant cosmological solutions in Einstein frame and Jordan frames are discussed showing that also the interpretation of cosmological observations can drastically change depending on the adopted frame

    Historical separation and present-day structure of common dolphinfish (Coryphaena hippurus) populations in the Atlantic Ocean and Mediterranean Sea

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    The common dolphinfish (Coryphaena hippurus) is an epipelagic, mid-trophic level, highly migratory species distributed throughout the world’s tropical and subtropical oceans in waters greater than 20C. Life-history variables, migratory behaviour, and genetic markers have been used to define major stocks in the central Atlantic Ocean and Mediterranean Sea. Here, we used the mitochondrial DNA gene NADH subunit 1 (688 bp) to test for differences between population groups. A total of 103 haplotypes were detected among 203 fish. Gene diversities in samples were large and similar among populations (mean h ¼ 0.932; range 0.894–0.987), but nucleotide diversities varied widely among samples (range p ¼ 0.004–0.034) and appear to reflect population histories. Principal component analysis revealed two large populations groups, and the analysis of molecular variation and pairwise values of UST resolved population structure within these groups. Populations in the eastern Atlantic and Mediterranean showed the largest amounts of divergence from one another (UCT ¼ 0.331). Adult movement and biophysical barriers to larval dispersal may explain contemporary differences between stocks, but the divergent populations in the Mediterranean Sea are likely due to isolations by cold temperature barriers during Pleistocene glaciations. The geographically large stock groupings require international cooperation in the harvest management and conservation of local dolphinfish populations

    Optimization of conventional and ultrasound assisted extraction of flavonoids from grapefruit (Citrus paradisi L.) solid wastes

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    Flavonoid compounds from grapefruit wastes were obtained by conventional solid liquid extraction (CE) and ultrasound assisted extraction (USE). Naringin was by far the most abundant flavonoid in the extracts ranging from 18 to 28 mg/g dw for CE and 24-36 mg/g dw for USE. Response surface methodology allowed obtaining predictive models for total phenolic content (TPC) and total antioxidant activity (TAA) as a function of the process variables ethanol concentration (Etc) (defined as weight of ethanol/weight of solution), temperature (T) and time (t) with reasonable success (CE-TPC, R-2 = 0.86, CE-TAA, R-2 = 0.85; USE-TPC, R-2 = 0.82; USE, TAA, R-2 = 0.86). USE was very effective when compared with conventional solvent extraction, allowing higher extraction yields (on average TPC 50% and TAA 66% higher) with lower temperatures and extraction times. Although the optimum process conditions indicate the use of a low ethanol concentration and ultrasounds (T = 25 degrees C, EtC = 0.4 (g/g) (40 g/100 g) and t = 55 min leading to TPC = 80.0 mg GAE/g dw and TAA = 38.3 mmol trolox/g dw), it has been proved that an USE treatment free of organic solvent (EtC = 0 g/g), at moderate temperature (25 degrees C) and short time (t = 3 min) leads to similar results (TPC = 753 mg GAE/g dw and TAA = 31.9 mmol trolox/g dw), suggesting its use for economic and environmental purposes.The authors acknowledge the Universitat Politecnica de Valencia (Spain) for its financial support through the project 1965 (PAID05-11).Garcia-Castello, EM.; Rodríguez López, AD.; Mayor López, L.; Ballesteros, R.; Conidi, C.; Cassano, A. (2015). Optimization of conventional and ultrasound assisted extraction of flavonoids from grapefruit (Citrus paradisi L.) solid wastes. Food Science and Technology. 64(2):1114-1122. https://doi.org/10.1016/j.lwt.2015.07.024S1114112264

    Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

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    We report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at lg(E/eV)=18.519.0\lg(E/{\rm eV})=18.5-19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A>4A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe

    ACTA OTORHINOLARYNGOLOGICA ITALICA

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    La neurofibromatosi tipo 2 [NF2] è una malattia genetica a trasmissione autosomica dominante [MIM # 101000]. Clinicamente è caratterizzata da: (1) schwannomi bilaterali del (VIII) nervo acustico/vestibolare; (2) cataratta giovanile o amartomi retinici; (3) schwannomi a carico dei nervi periferici e dei nervi cranici; (4) tumori multipli del sistema nervoso centrale (es., meningiomi, astrocitomi, ependimomi); (5) lesioni cutanee: (a) placche NF2 (schwannomi cutanei); (b) (poche) macchie caffellatte; (6) malformazioni dello sviluppo corticale cerebrale. La prevalenza della (forma sintomatica di) NF2 nella popolazione generale è di 1 su 100.000-200.000 individui con unincidenza di 1 su 33.000 nati. La forma classica a esordio nel giovane adulto è conosciuta come forma di Gardner, (esordio intorno ai 20-30 anni detà) con manifestazioni legate agli schwannomi bilaterali del nervo acustico/vestibolare (diminuzione/perdita progressiva delludito, tinnito, vertigini) e/o più raramente con manifestazioni da (altri) tumori del sistema nervoso centrale e/o periferico. In età pediatrica il fenotipo è diverso (forma di Wishart): per primi compaiono abitualmente i tumori del sistema nervoso centrale in assenza di schwannomi vestibolari; si possono avere macchie caffellatte e placche NF2 e solo dopo anni i tumori del nervo cranico VIII e di altri nervi cranici. Il quadro è più grave. Esiste anche una forma congenita ad esordio nei primi giorni/mesi di vita, con schwannomi vestibolari di piccole dimensioni (stabili nel tempo: anche per anni/decenni ma con improvvisa e rapida progressione) e numerose placche NF2; in questa forma le altre manifestazioni (es. meningiomi, altri tumori, altri schwannomi) sono spesso più gravi e progressive delle altre forme. Il gene responsabile della NF2 è localizzato sul cromosoma 22q12.1. Il prodotto genico della NF2 è conosciuto con il nome di schwannomina o merlina [dalla famiglia di proteine 4.1 del tipo moesina-ezrina-radixina/ERM alla quale appartiene il gene della NF2) e ha funzioni di regolazione della crescita e del rimodellamento cellulare (soppressione della crescita cellulare e della tumorigenesi)]. Alcune persone possono presentare tutte le (o parte delle) manifestazioni della NF2 in un emilato o in segmenti corporei circoscritti [NF2 a mosaico]. Altre persone presentano schwannomi (confermati istologicamente) dei nervi periferici (non intradermici) e/o delle radici gangliari in assenza di tumori del nervo vestibolare (o di altri nervi cranici: anche se in alcuni casi vi possono essere anche tumori unilaterali o bilaterali del nervo acustico/vestibolare e/o dei nervi cranici misti) o di altri segni diagnostici per la NF2 [Schwannomatosi, SWNTS]. Lesordio in questa forma è intorno ai 30 anni detà (sono conosciuti casi in età pediatrica) con tumori in svariate sedi (abitualmente tronco e arti). Si conoscono due forme principali: (1) SWNTS1 [MIM # 162091] causata da alterazioni del gene SMARCB1 [regolatore della cromatina actina-dipendente associato alla matrice e correlato alle proteina SWI/SBF, sub-famiglia B, membro di tipo 1; MIM # 601607], sul cromosoma 22q11.23 (posizione centromerica rispetto al gene della NF2); (2) SWNTS2 [MIM # 615670] causata da alterazioni del gene LZTR1 [regolatore della trascrizione di tipo 1 legato alla Leucina; MIM # 600574], cromosoma 22q11.21 (posizione centromerica rispetto al gene SMARCB1) che codifica per una proteina, membro della super-famiglia BTB-kelch. Il meccanismo molecolare della Schwannomatosi comprende: (1) mutazione germinale del gene SMARCB1 o del gene LZTR1; (2) ampia delezione allinterno del cromosoma 22 (con perdita del gene NF2 e dellallele intatto SMARCB1 o LZTR1); e (3) mutazione somatica dellallele intatto del gene NF2 [meccanismo conosciuto come four hits: Quadrupla alterazione (su entrambi gli alleli dei due geni SWNTS/NF2), con tre passaggi consecutivi]. Negli ultimi anni, accanto alle tradizionali terapie chirurgiche e/o radioterapiche sono stati anche impiegati diversi farmaci biologici (es., Lapatinib e Bevacizumab) con effetti di riduzione/arresto della crescita dei tipici tumori NF2

    Design and implementation of the AMIGA embedded system for data acquisition

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