The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gammaray bursts (GRBs) observed by the Fermi GBM telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S, 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. The main trend of spectral evolution (lag behavior) is estimated with log, where E p is the peak photon energy in the radiation spectrum, t + t 0 is the observer time relative to the beginning of pulse −t 0 , andτ is the spectral lag of photons with energy E with respect to the energy band 8-25 keV. For H2S and H2S-dominatedtracking pulses, a weak correlation between kτ /W and k E is found, where W is the pulse width. We also study the spectral lag behavior with peak time t p E of pulses for 30 well-shaped pulses and estimate the main trend of the spectral lag behavior with log t p E ∝ k tp log E. It is found that k tp is correlated with k E . We perform simulations under a phenomenological model of spectral evolution, and find that these correlations are reproduced. We then conclude that spectral lags are closely related to spectral evolution within the pulse. The most natural explanation of these observations is that the emission is from the electrons in the same fluid unit at an emission site moving away from the central engine, as expected in the models invoking magnetic dissipation in a moderately-high-σ outflow.

XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to X-ray Astronomy. At the time of writing XIPE is in a competitive phase A as fourth medium size mission of ESA (M4). It promises to reopen the polarimetry window in high energy Astrophysics after more than 4 decades thanks to a detector that efficiently exploits the photoelectric effect and to X-ray optics with large effective area. XIPE uniqueness is time-spectrallyspatially-resolved X-ray polarimetry as a breakthrough in high energy astrophysics and fundamental physics. Indeed the payload consists of three Gas Pixel Detectors at the focus of three X-ray optics with a total effective area larger than one XMM mirror but with a low weight. The payload is compatible with the fairing of the Vega launcher. XIPE is designed as an observatory for X-ray astronomers with 75 % of the time dedicated to a Guest Observer competitive program and it is organized as a consortium across Europe with main contributions from

The association between health-related quality of life (HRQOL)

This paper presents a new method for an inexpensive fabrication of large sized aluminium matrix nanocomposite, namely, the solid–liquid mixed (SLiM) casting technique accompanied with the idea of carrier ‘protein’ in the biochemistry. The results reveal that the poor dispersibility and low wettability of nanosized Al2O3 particles are obviously improved via the carrier agent of Al powder, and the large sized 0·6 wt-Al2O3–Al-2024 metal matrix nanocomposite (MMNC) with an uniformly nanosized particle distribution is successfully prepared by the SLiM casting process. Compared with the conventional stir casting, the tensile strength, yield strength and the hardness of the SLiM 0·6 wt-Al2O3–Al-2024 nanocomposite are enhanced by 59, 58 and 16 respectively. The present fabrication method is suitable for the production of other MMNCs. This work is expected to provide a guidance for the commercial preparation of the MMNC.

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