Interstellar (Na-22) as a possible source of the excess (Ne-22) in the galactic cosmic ray

A selective injection mechanism of cosmic ray seed nuclei due to nuclear decay effects is proposed. It is shown that 22NA ejected by novae explosion can explain the excess 22Ne in the galactic cosmic ray source by invoking energization and ionization during its beta-decay process in interstellar space

A stochastic simulation of the propagation of Galactic cosmic rays reflecting the discreteness of cosmic ray sources. Age and path length distribution

The path length distribution of Galactic cosmic rays (GCRs) is the fundamental ingredient for modeling the propagation process of GCRs based on the so-called weighted slab method. We try to derive this distribution numerically by taking into account the discreteness in both space and time of occurrences of supernova explosions where GCRs are suspected to be born. We solve numerically the stochastic differential equations equivalent to the Parker diffusion-convection equation which describes the propagation process of GCR in the Galaxy. We assume the three-dimensional diffusion is an isotropic one without any free escape boundaries. We ignore any energy change of GCRs and the existence of the Galactic wind for simplicity. We also assume axisymmetric configurations for the density distributions of the interstellar matter and for the surface density of supernovae. We have calculated age and path length of GCR protons arriving at the solar system with this stochastic method. The obtained age is not the escape time of GCRs from the Galaxy as usually assumed, but the time spent by GCRs during their journey to the solar system from the supernova remnants where they were born. The derived age and path length show a distribution spread in a wide range even for GCR protons arriving at the solar system with the same energy. The distributions show a cut-off at a lower range in age or path length depending on the energy of GCRs. These cut-offs clearly come from the discreteness of occurrence of supernovae. The mean age of GeV particles obtained from the distributions is consistent with the age obtained by direct observation of radioactive secondary nuclei. The energy dependence of the B/C ratio estimated with the path length distribution reproduces reliably the energy dependence of B/C obtained by recent observations in space.Comment: 5 pages, 5 figures. Accepted for publication in A&

Constraints on Cold Dark Matter in the Gamma-ray Halo of NGC 253

A gamma-ray halo in a nearby starburst galaxy NGC 253 was found by the CANGAROO-II Imaging Atmospheric Cherenkov Telescope (IACT). By fitting the energy spectrum with expected curves from Cold Dark Matter (CDM) annihilations, we constrain the CDM-annihilation rate in the halo of NGC 253. Upper limits for the CDM density were obtained in the wide mass range between 0.5 and 50 TeV. Although these limits are higher than the expected values, it is complementary important to the other experimental techniques, especially considering the energy coverage. We also investigate the next astronomical targets to improve these limits.Comment: 13 pages, 5 figures, aastex.cls, natbib.sty, To appear in ApJ v596n1, Oct. 10, 200

Design of Easily Synchronizable Oscillator Networks Using the Monte Carlo Optimization Method

Starting with an initial random network of oscillators with a heterogeneous frequency distribution, its autonomous synchronization ability can be largely improved by appropriately rewiring the links between the elements. Ensembles of synchronization-optimized networks with different connectivities are generated and their statistical properties are studied

Lidocaine for systemic sclerosis: a double-blind randomized clinical trial

Background: Systemic sclerosis (scleroderma; SSc) is an orphan disease with the highest case-specific mortality of any connective-tissue disease. Excessive collagen deposit in affected tissues is a key for the disease's pathogenesis and comprises most of the clinical manifestations. Lidocaine seems to be an alternative treatment for scleroderma considering that: a) the patient's having excessive collagen deposits in tissues affected by scleroderma; b) the patient's demonstrating increased activity of the enzyme prolyl hydroxylase, an essential enzyme for the biosynthesis of collagen; and c) lidocaine's reducing the activity of prolyl hydroxylase. the aim of this study was to evaluate the efficacy and safety of lidocaine in treating scleroderma.Methods: A randomized double-blind clinical trial included 24 patients with scleroderma randomized to receive lidocaine or placebo intravenously in three cycles of ten days each, with a one-month interval between them. Outcomes: cutaneous (modified Rodnan skin score), oesophageal (manometry) and microvascular improvement (nailfold capillaroscopy); improvement in subjective self-assessment and in quality of life (HAQ).Results: There was no statistically significant difference between the groups for any outcome after the treatment and after 6-months follow-up. Improvement in modified Rodnan skin score occurred in 66.7% and 50% of placebo and lidocaine group, respectively (p = 0.408). Both groups showed an improvement in subjective self-assessment, with no difference between them.Conclusions: Despite the findings of a previous cohort study favouring the use of lidocaine, this study demonstrated that lidocaine at this dosage and means of administration showed a lack of efficacy for treating scleroderma despite the absence of significant adverse effects. However, further similar clinical trials are needed to evaluate the efficacy of lidocaine when administered in different dosages and by other means.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Brazilian Cochrane Ctr, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Emergency Med & Evidence Based Med, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Rheumatol, São Paulo, BrazilUniv Santo Amaro, Discipline Rheumatol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Brazilian Cochrane Ctr, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Emergency Med & Evidence Based Med, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Rheumatol, São Paulo, BrazilFAPESP: 01-13895-9Web of Scienc

Observations of the supernova remnant W28 at TeV energies

The atmospheric Cerenkov imaging technique has been used to search for point-like and diffuse TeV gamma-ray emission from the southern supernova remnant, W28, and surrounding region. The search, made with the CANGAROO 3.8m telescope, encompasses a number of interesting features, the supernova remnant itself, the EGRET source 3EG J1800-2338, the pulsar PSR J1801-23, strong 1720 MHz OH masers and molecular clouds on the north and east boundaries of the remnant. An analysis tailored to extended and off-axis point sources was used, and no evidence for TeV gamma-ray emission from any of the features described above was found in data taken over the 1994 and 1995 seasons. Our upper limit (E>1.5 TeV) for a diffuse source of radius 0.25deg encompassing both molecular clouds was calculated at 6.64e-12 photons cm^-2 s^-1 (from 1994 data), and interpreted within the framework of a model predicting TeV gamma-rays from shocked-accelerated hadrons. Our upper limit suggests the need for some cutoff in the parent spectrum of accelerated hadrons and/or slightly steeper parent spectra than that used here (-2.1). As to the nature of 3EG J1800-2338, it possibly does not result entirely from pi-zero decay, a conclusion also consistent with its location in relation to W28.Comment: 11 pages, 5 figures. Accepted for publication in Astronomy and Astrophysic

Evidence for TeV gamma-ray emission from the shell type SNR RXJ1713.7-3946

We report the results of TeV gamma-ray observations of the shell type SNR RXJ1713.7-3946 (G347.3-0.5). The discovery of strong non-thermal X-ray emission from the northwest part of the remnant strongly suggests the existence of electrons with energies up to 100 TeV in the remnant, making the SNR a good candidate TeV gamma-ray source. We observed RXJ1713.7-3946 from May to August 1998 with the CANGAROO 3.8m atmospheric imaging Cerenkov telescope and obtained evidence for TeV gamma-ray emission from the NW rim of the remnant with the significance of 5.6 sigma. The observed TeV gamma-ray flux from the NW rim region was estimated to be (5.3 +/- 0.9[statistical] +/- 1.6[systematic]) * 10^{-12} photons cm^{-2} s^{-1} at energies >= 1.8 +/- 0.9 TeV. The data indicate that the emitting region is much broader than the point spread function of our telescope. The extent of the emission is consistent with that of hard X-rays observed by ASCA. This TeV gamma-ray emission can be attributed to the Inverse Compton scattering of the Cosmic Microwave Background Radiation by shock accelerated ultra-relativistic electrons. Under this assumption, a rather low magnetic field of 11 micro gauss is deduced for the remnant from our observation.Comment: Accepted for publication by Astronomy and Astrophysics (5 pages, 2 figures