Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

An ultra stable glass system for optical fiber devices

In this paper a modified chalcogenide glass was studied by X-ray powder diffraction, differential thermal analysis, infrared and Raman scattering spectroscopies. The study of this new matrix opens new perspectives to fabricate Pr3+-doped fibers to operate as an optical amplifier in the 1.3 mum telecommunications window. The Pr3+-doped 70Ga(2)S(3)-30La(2)S(3) glass was modified through the substitution of La2S3 by La2O3, which improves the thermal stability of these glasses without any modification of phonon energy. The possibility to pull a fiber from this glass system without any devitrification is easily achieved

Efficient second-harmonic generation in praseodymium-doped Ga:La:S glass for 1.3-mu m optical fiber amplifiers

Efficient second-harmonic generation in praseodymium-doped gallium-lanthanum-sulphide glasses for optical fiber amplifiers around 1.3 mu m is experimentally investigated. The Pr3+-doped Ga:La:S glass samples were pumped by Nd:YAG laser pulses at 1.319 mu m and 1.064 mu m and generated frequency doubled light at 660 nm and 532 nm, respectively, with conversion efficiencies as high as 0.02%, Frequency doubling in praseodymium-free Ga:La:S glass samples was also observed.8682182

Multiwavelength frequency-doubling in bulk gallium-lanthanum-sulphide glasses for optical fiber amplifiers at 1.3 mu m

We report on the experimental investigation of efficient multiwavelength frequency-doubling in bulk undoped and Pr3+-doped Ga:La:S glasses for optical fiber amplifiers in the 1.3 mu m telecommunications window. The amorphous sulphide-based glass samples were pumped by several wavelengths (1.06, 1.12, 1.16 and 1.32 mu m) and unseeded frequency doubled signals at 532, 560, 580 and 660 nm, respectively, were generated instantaneously for all these pump wavelengths separately. Second-harmonic conversion efficiencies as high as 0.02% were obtained at 1.32 mu m. The results also revealed that in Pr3+-doped sulphide-based glasses the frequency-doubling mechanism is enhanced owing to the presence of the praseodymium dopant in the glass matrix.7416711

Upconversion fluorescence spectroscopy of Er3+/Yb3+-doped heavy metal Bi2O3-Na2O-Nb2O5-GeO2 glass

Upconversion fluorescence emission of Er3+/Yb3+-doped Bi2O3-Na2O-Nb2O5-GeO2 heavy metal glass samples excited at 1.06 mu m is experimentally investigated. The results reveal the existence of intense emission bands centered around 520, 545, and 655 nm. The germano-niobate based host glass presents high transparency in the region of 400-2700 nm, the capability of incorporating high dopant concentrations, high melting temperature, and large resistance to atmospheric moisture. The observed intensity of the green fluorescence emission, suggested that the niobium based host glass material plays an important role in the efficiency of the upconversion process. Emission lines centered at 425, 483, 503, 608, and 628 nm were also observed. (C) 1997 American Institute of Physics

Analysis of the four wave mixing effect (FWM) in a dispersion decreasing fiber (DDF) for a WDM system

We did a numerical investigation of the propagation of short light pulses in the region of 1.55 mu m and the conversion efficiency (CE) for the four wave mixing generation (FWM) of ordinary and dispersion decreasing fibers for use in wavelength division multiplexing (WDM) systems, Our simulations studies three different profiles, linear, hyperbolic. and constant, One conclude that for all the profiles there is decrease of the conversion efficiency with the increase in the channel separation. The hyperbolic profile present a higher efficiency of around 1000 above in magnitude compared with the others profiles at 0.2 nm of channel separation. We calculate the conversion efficiency versus the fiber length for the three profiles. The conversion efficiency for the hyperbolic profile is higher when compared to the constant and linear profiles. The other interesting point of the hyperbolic profile is that the increase of the CE in the beginning of the fiber does not show my oscillation in the CE value (log eta), which was observed for the constant and linear profiles. For all the profiles there is an increase of the conversion efficiency with the increase of the pump power. The compression factor C-i for the generated FWM signal at omega(3) was measured along the DDF's and the constant profile fibers. One can conclude that with the use of decreasing dispersion profile (DDF) fibers one can have a control of the (CE) conversion efficiency and the compression factor of the four wave mixing (FWM) generation in WDM systems. (c) 2005 Elsevier B.V. All rights reserved

Distrofia muscular congênita estudo clinico de 17 pacientes

Descrevemos 17 pacientes (12m, 5f) com idades que variaram de 1 a 24 anos (mediana 6 anos) com distrofia muscular congênita (DMC), que foram estudados do ponto de vista genético, clínico, laboratorial, eletrofisiológico e anátomo-patológico. A apresentação segundo a herança foi da forma esporádica (76,5%) ou possivelmente autossômica recessiva (23,5%). A diminuição da movimentação fetal intra-uterina foi referida em 57% dos casos, hipotonia neonatal em 82% e retardo no desenvolvimento motor em 88,2%. Fraqueza muscular, diminuição dos reflexos profundos e contraturas articulares estavam presentes em todos os casos. A piora na função motora estava muito relacionada ao aumento ou aparecimento de novas retrações articulares. A CK nunca ultrapassou valores acima de 8 vezes o normal. O ENMG foi de padrão miopático em 73,3%, neuropático em 13,3% e normal em 13,3% dos casos. Aspectos tomográficos com hipodensidade da substância branca subcortical foram vistos em 8 casos. Ao tratamento impôs-se fisioterapia adequada e cirurgia corretiva das deformidades articulares. Novas contraturas desenvolveram-se mais tarde e estavam relacionadas freqüentemente a fisioterapia insuficiente