620 research outputs found

    Phase distortions of attosecond pulses produced by resonance-enhanced high harmonic generation

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    Resonant enhancement of high harmonic generation can be obtained in plasmas containing ions with strong radiative transitions resonant with harmonic orders. The mechanism for this enhancement is still debated. We perform the first temporal characterization of the attosecond emission from a tin plasma under near-resonant conditions for two different resonance detunings. We show that the resonance considerably changes the relative phase of neighbouring harmonics. For very small detunings, their phase locking may even be lost, evidencing strong phase distortions in the emission process and a modified attosecond structure. These features are well reproduced by our simulations, allowing their interpretation in terms of the phase of the recombination dipole moment

    Penning trap mass measurements on (99-109)$Cd with ISOLTRAP and implications on the rp process

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    Penning trap mass measurements on neutron-deficient Cd isotopes (99-109)Cd have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all with relative mass uncertainties below 3*10^8. A new mass evaluation has been performed. The mass of 99Cd has been determined for the first time which extends the region of accurately known mass values towards the doubly magic nucleus 100Sn. The implication of the results on the reaction path of the rp process in stellar X-ray bursts is discussed. In particular, the uncertainty of the abundance and the overproduction created by the rp-process for the mass A = 99 is demonstrated by reducing the uncertainty of the proton-separation energy of 100In Sp(100In) by a factor of 2.5.Comment: 14 pages, 9 figure

    Search for the Radiative Capture d+d->^4He+\gamma Reaction from the dd\mu Muonic Molecule State

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    A search for the muon catalyzed fusion reaction dd --> ^4He +\gamma in the dd\mu muonic molecule was performed using the experimental \mu CF installation TRITON and NaI(Tl) detectors for \gamma-quanta. The high pressure target filled with deuterium at temperatures from 85 K to 800 K was exposed to the negative muon beam of the JINR phasotron to detect \gamma-quanta with energy 23.8 MeV. The first experimental estimation for the yield of the radiative deuteron capture from the dd\mu state J=1 was obtained at the level n_{\gamma}\leq 2\times 10^{-5} per one fusion.Comment: 9 pages, 3 Postscript figures, submitted to Phys. At. Nuc

    On application of Liouville type equations to constructing B\"acklund transformations

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    It is shown how pseudoconstants of the Liouville-type equations can be exploited as a tool for construction of the B\"acklund transformations. Several new examples of such transformations are found. In particular we obtained the B\"acklund transformations for a pair of three-component analogs of the dispersive water wave system, and auto-B\"acklund transformations for coupled three-component KdV-type systems.Comment: 11 pages, no figure

    Elevated neopterin levels in non-allergic asthma

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    Neopterin is synthesized by human monocyte-derived macrophages upon stimulation with interferon-gamma (IFN-gamma). Measurement of neopterin concentration is useful to monitor cell-mediated (Th1-type) immune activation. In this study, we aimed to analyze the behaviour of neopterin in long lasting asthma considering its role as a marker of the Th1 environment and to establish the distinction between patients belonging either to the allergic or the non-allergic population, particularly in the elderly where asthma is often under diagnosed. Therefore we evaluated allergic parameters such as skin prick tests, IgE and hemogram (eosinophils count), and we compared our findings with neopterin values found in an age-matched control population. A group of individuals older than 65 was selected. It included 64 asthmatic patients (mean age 72+/-5 years) and 41 healthy individuals (mean age 79+/-7 years). In our study population, 42 patients presented positive skin tests, mainly to house dust mites. All patients were clinically stable and presented an average percentage of predicted forced expiratory volume in the first second (FEV1) of 73.6+/-25.3 and predicted median expiratory flow percentage (MEF50) of 38.8+/-26.7. Blood cell counts showed statistically different mean values of eosinophils between allergic and non-allergic controls (5.42+/-4.7% versus 2.8+/-2.8%; p2.1ng/ml) presented lower mean IgE values (IgE</=336.58IU) than those with lower neopterin values (</=2.1ng/ml) who presented mean IgE values of 402.70IU. Our initial findings may lead to a better understanding of the immunoinflammatory pathways in asthma. Further studies will probably show that serum neopterin could became a useful marker for asthma classification including in elderly patients with long lasting disease

    Substance P in Long-Lasting Asthma: Immunoinflammatory pathways

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    Background: Substance P (SP) was described at the beginning of the 20th Century, and its biological action was recognized to have implications in neurogenic inflammation and constriction of smooth muscles. The changes associated with inflammatory chronicity can compromise organ function reversibility. The role of neuromechanisms in the pathology of the disease has been investigated in order to achieve better diagnosis and therapeutic approaches. The stimulation of human cells, such as macrophages and polymorphonuclear cells by SP leads to their activation and to the release of reactive oxygen species (ROS) by these cells. Consequently, a continuous inflammatory disability is observed, mainly if a decrease in antioxidant defence occurs. SP is a substrate for dipeptidyl peptidase IV (DPPIV), which is a multifunctional molecule with enzymatic and proinflammatory activities. CD26 is considered an activation T cell marker. The aim of the present study was to analyse if serum SP values in long-lasting asthma patients were related to lung function parameters. It was also decided to analyze the relationship of SP with superoxide dismutase (SOD) and total antioxidant activity in serum (TAS), as well as its association to CD26/DPPIV values considering their immunological and inflammatory properties. Methods/Data base: A group of individuals older than 65 years, including 64 asthmatic patients (mean age 72±5 years) and 41 healthy individuals (mean age 79±7years) was selected. Both subgroups were submitted to clinical observation, to skin prick tests (SPT) and to SP, TAS, SOD, and DPPIV determinations. T cell CD26 typing was also performed. Lung function tests were done on all patients. Results: Among the patients studied, 42 had positive skin tests, mainly to house dust mites. Asthmatic patients showed a significant increase in SP values (116.2±138.9 vs 39.5±17.9 pg/ml) when compared to controls and a significant decrease in TAS levels (.85±.13 vs .91±.10 mM) and in SOD levels (588.1±156.l vs 822.9±179.5 U/gHb). All patients were clinically stable and presented an average percentage of predict forced expiratory volume in the first second (FEV1) of 73.6±25.3 and median expiratory flow percentage of predict (MEF50) of 38.8±26.7. DPPIV values were significantly increased in asthmatics compared to controls (69.7±15.2 vs 58.6±14.3 U/L). The CD26 expression was only slightly increased in asthmatic patients (41.9±10.2 vs 39.4±11.4). Conclusion: These results confirm the role of SP in asthma and give a contribution for a better knowledge of the immunoinflammatory pathway associated with this chronic disorder. A final goal for these studies would be to achieve a better therapeutic approach in order to improve the outcome of asthmatic patients

    Substance P in Bronchial Asthma: Role in oxidant stress and in cell activation

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    The substance P (SP) was described in the beginning of the XXth Century, and its biological actions was recognized to have implications in neurogenic inflammation and constriction of smooth muscles. The bronchial asthma prevalence has been increasing in all developed countries. The changes associated to inflammatory chronicity can compromise the organ function reversibility. The role of neuromechanisms in the pathology of the disease has been investigated considering the hypotheses that better therapeutic approaches can be achieved. The stimulation of human cells by SP leads to their activation and to reactive oxygen species (ROS) release. Consequently a persisting inflammatory disability is observed, mainly if a decrease in the anti-oxidant defence occurs. SP is a substrate for dipeptidyl peptidase IV (DPPIV), which is a multifunctional molecule with enzymatic and proinflammatory activities. CD26 was identified as the membrane DPPIV and is considered as an activation T cell marker, as well as CD25. The aim of the present study was therefore to analyse if serum SP values in long-term asthma patients, were associated to lung function parameters, considering the role of SP in neurogenic inflammation and in bronchoconstriction. It was also proposed to analyse the relationship of SP with superoxide dismutase (SOD) and total anti-oxidation activity in serum (TAS), considering the ROS production during the inflammatory process, as well as its association to CD26 and CD25 values and their immunologic and inflammatory properties. A group of individuals older than 65 years including 64 asthmatic patients (mean age 72.4±5.1 years) and 41 healthy individuals (mean age 79.2±7.0 years) was selected. Both subgroups were submitted to clinical observation, to skin prick tests and to SP, TAS and SOD. T cell CD26 and CD25 typing was also performed. Lung function tests were done to all patients. Among patients studied, 42 presented positive skin tests, mainly to house dust mites. Asthmatic patients presented significant increased values of SP (116.2±138.9 vs 39.5±17.9 pg/ml) when compared to controls and a significant decrease of TAS (.85±.13 vs .91±.10 mM) and SOD (588.1±156.l vs 822.9±179.5 U/gHb). All patients have clinical stability and presented forced expiratory volume in one second (FEV1) values of 73.6±25.3 l/s and peak expiratory flow (PEF50) of 38.8±26.7l. The CD25 expression was significantly increased in disease (14.3±5.9 vs 22.4±7.8) while CD26 was only slightly increased (41.9±10.2 vs 39.4±11.4). These results confirm the role of SP in the respiratory pathology studied and give a contribution for a better knowledge of the network of immunoinflammatory pathway, associated to this chronic disorder. A final goal for these studies would be a better diagnostic and therapeutic approach in this pathology

    Finite Temperature Aging Holography

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    We construct the gravity background which describes the dual field theory with aging invariance. We choose the decay modes of the bulk scalar field in the internal spectator direction to obtain the dissipative behavior of the boundary correlation functions of the dual scalar fields. In particular, the two-time correlation function at zero temperature has the characteristic features of the aging system: power law decay, broken time translation and dynamical scaling. We also construct the black hole backgrounds with asymptotic aging invariance. We extensively study characteristic behavior of the finite temperature two-point correlation function via analytic and numerical methods.Comment: 38 pages and 5 figures, expanded discussions on correlator, one mistake is fixed, modified discussion on shear viscosity, to appear in JHE
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