dutch elm disease is one of the most destructive and common plant vascular diseases now which isknown as a global problem. the aim of this study was comparison of early- and late-wood vesselsdiameter and ray dimensions. in 4 species: ulmus carpinifolia, zelkova carpinifolia, ulmus glabra andceltis australis from ulmaceae. then, very thin transversal sections were prepared and after differentsta...

This paper presents the theoretical basis of the fireball/blast wave model, and some implications of recent results on GRB source models and cosmic-ray production from GRBs. BATSE observations of the prompt γ-ray luminous phase, and Beppo-SAX and long wavelength afterglow observations of GRBs are briefly summarized. Derivation of spectral and temporal indices of an adiabatic blast wave decelera...

X-ray emission can provide a crucial diagnostic of gamma-ray bursts (GRBs). We calculate the X-ray and gamma-ray spectra of impulsive acceleration episodes related to GRB pulses. We use the synchrotron shock model (SSM) as a basis of our calculations. We show that the current data on soft-to-hard emission ratios of GRB pulse emission are in agreement with the SSM. In particular, GRB pulse emiss...

he X-Ray/Gamma-Ray Spectrometer on the Near Earth Asteroid Rendezvous (NEAR) spacecraft will remotely sense X-ray and gamma-ray emissions from the surface of near-Earth asteroid 433 Eros and look for characteristic “signatures” in those emissions to determine its elemental composition. During the planned 10 months of orbits about Eros beginning in early 1999, data returned from the instrument w...

The afterglow emission has become the main stream of Gamma-Ray burst research since its discovery three years ago. With the distance-scale enigma solved, the study of the late-time GRB emission is now the most promising approach to disclose the origin of these explosions and their relationship with the environment of the host galaxy in the early phase of the Universe. In this contribution I wil...