A radio frequency identification (RFID) system is a special kind of sensor network to identify an object or a person using radio frequency transmission. A typical RFID system includes transponders (tags) and interrogators (readers): tags are attached to objects/persons, and readers communicate with the tags in their transmission ranges via radio signals. RFID systems have been gaining more and ...

The unusual supernova SN1998bw, which is thought to be related to the γray burster GRB980425, is a possible link between the two classes of objects. Analyzing the extensive radio emission data avaliable for SN1998bw, we are able to describe its time evolution within the well established framework available for the analysis of radio emission from supernovae. This then allows description of a num...

We review the design, selected applications and parallel performance of WiPPET, a general parallel simulation testbed for various types of wireless networks. WiPPET has been written in TeD/C++, a new object-oriented modeling framework that isolates network modeling from the underlying parallel discrete event simulator. We describe the techniques for modeling radio propagation (long and short-sc...

Aims. We analyze the LBN 978 HII region in order to study the HII/molecular cloud interaction. Methods. We used the IAC-80 telescope to image the region with narrow-band filters and the Very Large Array to obtain a radio continuum map at 3.6 cm. We also used the DSS2 red images and the NRAO VLA Sky Survey at 20 cm. Results. We have discovered a new radial system of dark globules associated with...

We report on ESO–VLT near-IR adaptive optics imaging of one radio-loud (PKS 0113-283) and two radio quiet (Q 0045-3337 and Q0101-337) quasars at z > 2. In the first case we are able to resolve the QSO and find that it is hosted by an elliptical of absolute magnitude MK = −27.6. For the other two objects no extended emission has been unambiguously detected. This result, though restricted to a si...

Aims. We aim to investigate the nature of the high energy source KS 1741−293 by revisiting the radio and infrared associations proposed in the early 1990s. Methods. Our work is mostly based on the analysis of modern survey and archive data, including the NRAO, MSX, 2MASS and Chandra archives, and catalogues. We also have obtained deep CCD optical observations by ourselves. Results. The coincide...

We present a near-IR spectrum of the nearby radio galaxy PKS1549-79 (z = 0.153). These data were taken with the aim of testing the idea that this object contains a quasar nucleus that is moderately extinguished, despite evidence that its radio jet points close to our line-of-sight. We detect broad Paα emission (FWHM 1745 ± 40 km s), relatively bright continuum emission, and a continuum slope co...

We present the discovery of a radio galaxy at a likely redshift of z=4.424 in one of the flanking fields of the Hubble Deep Field (HDF). Radio observations with the Very Large Array and MERLIN centered on the HDF yielded a complete sample of microjansky radio sources, of which about 20% have no optical counterpart to I</=25 mag. In this Letter, we address the possible nature of one of these sou...

We report the discovery of a radio transient VLA 232937.2-235553, coincident with the proposed X-ray afterglow for the gamma-ray burst GRB 981226. This gamma-ray burst (GRB) has the highest ratio of X-ray to gamma-ray fluence of all the GRBs detected by BeppoSAX so far, and yet no corresponding optical transient was detected. The radio light curve of VLA 232937.2-235553 is qualitatively similar...

We discuss the nature of the unidentified EGRET source 3EG J1621+8203. In an effort to identify the gammaray source, we have examined X-ray images of the field from ROSAT PSPC, ROSAT HRI, and ASCA GIS. Of the several faint X-ray point sources in the error circle of 3EG J1621+8203, most are stars or faint radio sources, unlikely to be counterparts to the EGRET source. The most notable object in ...