2,806 research outputs found

    Low-energy diffraction; a direct-channel point of view: the background

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    We argue that at low-energies, typical of the resonance region, the contribution from direct-channel exotic trajectories replaces the Pomeron exchange, typical of high energies. A dual model realizing this idea is suggested. While at high energies it matches the Regge pole behavior, dominated by a Pomeron exchange, at low energies it produces a smooth, structureless behavior of the total cross section determined by a direct-channel nonlinear exotic trajectory, dual to the Pomeron exchange.Comment: 6 pages, 1 figure. Talk presented at the Second International "Cetraro" Workshop & NATO Advanced Research Workshop "Diffraction 2002", Alushta, Crimea, Ukraine, August 31 - September 6, 200

    Search for single sources of ultra high energy cosmic rays on the sky

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    In this paper, we suggest a new way to identify single bright sources of Ultra High Energy Cosmic Rays (UHECR) on the sky, on top of background. We look for doublets of events at the highest energies, E > 6 x 10^19 eV, and identify low energy tails, which are deflected by the Galactic Magnetic Field (GMF). For the sources which are detected, we can recover their angular positions on the sky within one degree from the real ones in 68% of cases. The reconstruction of the deflection power of the regular GMF is strongly affected by the value of the turbulent GMF. For typical values of 4 microG near the Earth, one can reconstruct the deflection power with 25% precision in 68% of cases.Comment: 20 pages, 10 figures. Corresponds to the version published in JCA

    Lensing of ultra-high energy cosmic rays in turbulent magnetic fields

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    We consider the propagation of ultra high energy cosmic rays through turbulent magnetic fields and study the transition between the regimes of single and multiple images of point-like sources. The transition occurs at energies around EcZ 41EeV(Brms/5μG)(L/2kpc)3/250pc/LcE_c\simeq Z~41 {\rm EeV}(B_{rms}/5 \mu{\rm G}) (L/ 2 {\rm kpc})^{3/2}\sqrt{50 {\rm pc}/L_c}, where LL is the distance traversed by the CR's with electric charge ZeZe in the turbulent magnetic field of root mean square strength BrmsB_{rms} and coherence length LcL_c. We find that above 2Ec2 E_c only sources located in a fraction of a few % of the sky can reach large amplifications of its principal image or start developing multiple images. New images appear in pairs with huge magnifications, and they remain amplified over a significant range of energies. At decreasing energies the fraction of the sky in which sources can develop multiple images increases, reaching about 50% for E>Ec/2E>E_c/2. The magnification peaks become however increasingly narrower and for E<Ec/3E<E_c/3 their integrated effect becomes less noticeable. If a uniform magnetic field component is also present it would further narrow down the peaks, shrinking the energy range in which they can be relevant. Below EEc/10E\simeq E_c/10 some kind of scintillation regime is reached, where many demagnified images of a source are present but with overall total magnification of order unity. We also search for lensing signatures in the AGASA data studying two-dimensional correlations in angle and energy and find some interesting hints.Comment: 30 pages, 16 figures, final version with minor change

    Ultrahigh Energy Nuclei in the Galactic Magnetic Field

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    Observations are consistent with a significant fraction of heavy nuclei in the cosmic ray flux above a few times 10^19 eV. Such nuclei can be deflected considerably in the Galactic magnetic field, with important implications for the search of their sources. We perform detailed simulations of heavy nuclei propagation within recent Galactic magnetic field models. While such models are not yet sufficiently constrained to predict deflection maps in detail, we find general features of the distribution of (de-) magnified flux from sources. Since in most theoretical models sources of heavy nuclei are located in the local large scale structure of galaxies, we show examples of images of several nearby galaxy clusters and of the supergalactic plane. Such general features may be useful to develop efficient methods for source reconstruction from observed ultrahigh energy cosmic ray arrival directions.Comment: 17 pages, 11 figures. Published in JCA

    Pulmonary hypertension in chronic interstitial lung diseases

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    Pulmonary hypertension (PH) is a common complication of interstitial lung diseases (ILDs), particularly in idiopathic pulmonary fibrosis and ILD associated with connective tissue disease. However, other lung diseases, such as combined pulmonary fibrosis and emphysema syndrome, pulmonary Langerhans cell histiocytosis, and lymphangioleiomyomatosis, may also include PH in their clinical manifestations. In all of these diseases, PH is associated with reduced exercise capacity and poor prognosis. The degree of PH in ILDs is typically mild-to-moderate. However, some of these patients may develop a disproportionate increase in PH that cannot be justified solely by hypoxia and parenchymal injury: this condition has been termed "out-of-proportion" PH. The pathogenesis of PH in these diseases is various, incompletely understood and may be multifactorial. The clinical suspicion (i.e. increased dyspnoea, low diffusion capacity) and echocardiographic assessment are the first steps towards proper diagnosis of PH; however, right heart catheterisation remains the current gold standard for diagnosis of PH. At present, no specific therapies have been approved for the treatment of PH in patients with ILDs. \ua9 ERS 2013

    Exercise-induced cardiac costraint by the lungs

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    A patient of fourty-five years old male, with severe emphysema, underwent bullectomy. He was studied, before and one year after surgery, by standard pulmonary function test and cardiopulmonary exercise test. We found that before bullectomy, tidal volume increases up to 45 W and flattens thereafter. After bullectomy tidal volume increases trough the entire exercise

    Severe idiopathic pulmonary fibrosis: What can be done?

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    Idiopathic pulmonary fibrosis (IPF) remains a challenging disease to manage. Two drugs are now available that can slow disease progression in patients with mild-to-moderate IPF. This means that early diagnosis is mandatory, because there are no proven effective therapies for severe IPF. This lack of proven therapies may be at least partially due to the fact that severe IPF patients are usually not enrolled in randomised, prospective, multicentre, international trials. Clinical observation experiences and preliminary results of long-term, open-label extensions of clinical trials suggest that both pirfenidone and nintedanib may also slow or decrease progression in patients with severe IPF. However, data are sparse and obtained from a relatively small number of patients. Lung transplantation should be taken into account early and discussed with patients, when indicated. Rehabilitative strategies are important and effective supportive therapies. The needs of patients with severe IPF are similar to those of patients with an advanced neoplastic disease. Palliative care and psychological support play an important role in the relief of symptoms of anxiety and depression. Accordingly, these therapeutic approaches should start early in IPF patients

    The Galactic magnetic field and propagation of ultra-high energy cosmic rays

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    The puzzle of ultra-high energy cosmic rays (UHECRs) still remains unresolved. With the progress in preparation of next generation experiments (AUGER, EUSO, OWL) grows also the importance of directional analysis of existing and future events. The Galactic magnetic field (GMF) plays the key role in source identification even in this energy range. We first analyze current status of our experimental and theoretical knowledge about GMF and introduce complex up-to-date model of GMF. Then we present two examples of simple applications of influence of GMF on UHECR propagation. Both examples are based on Lorentz equation solution. The first one is basic directional analysis of the incident directions of UHECRs and the second one is a simulation of a change of chemical composition of CRs in the energy range 10^13 - 10^19 eV. The results of these simple analyses are surprisingly rich - e.g. the rates of particle escape from the Galaxy or the amplifications of particle flux in specific directions.Comment: 10 pages, 7 figures, accepted for publication in A&

    Percolation on the average and spontaneous magnetization for q-states Potts model on graph

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    We prove that the q-states Potts model on graph is spontaneously magnetized at finite temperature if and only if the graph presents percolation on the average. Percolation on the average is a combinatorial problem defined by averaging over all the sites of the graph the probability of belonging to a cluster of a given size. In the paper we obtain an inequality between this average probability and the average magnetization, which is a typical extensive function describing the thermodynamic behaviour of the model
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