Data networks, such as wireless networks and the Internet, in addition to offering reliable point-to-point unicast communication, also support a multicast facility by which a sender can disseminate data to multiple receivers (clients) without incurring a per-receiver cost. One of the shortcomings of traditional multicast protocols is their inability to deliver data reliably to all receivers in ...

Wireless sensor network technologies enable a wide variety of applications (e.g., environmental monitoring). Such sensor networks are often deployed in regions that make it difficult to collect and redistribute the nodes for maintenance. However, there is often a need to reprogram all of the nodes in the network, either during application test phases on deployed networks, or to support software...

The evidence for locating the High Velocity Clouds in the Local Group is summarized and evaluated. Recent measurements of the Hα surface brightness and metallicity of a number of HVCs appear to be fatal to the Galactic fountain as a significant contributor to the HVC phenomenon, but not to the existence of the fountain itself. Observations of extragalactic analogues to HVCs remain the sine qua ...

Studies of the halo gas in the Milky Way and in nearby spiral galaxies show the presence of gas complexes that cannot be reconciled with an internal (galactic fountain) origin and are direct evidence of gas accretion. Estimating gas accretion rates from these features consistently gives values, which are one order of magnitude lower than what is needed to feed the star formation. I show that th...

A school of fish exhibit a variety of distinctive maneuvers to escape from predators. For example, they adopt avoid, compact, and inspection maneuvers when predators are nearby, use skitter or fast avoid maneuvers when predators chase them, or exhibit fountain, split, and flash maneuvers when predators attack them. Although these escape maneuvers have long been studied in biology and ecology, t...

1047-3203/$ see front matter 2011 Elsevier Inc. A doi:10.1016/j.jvcir.2011.09.003 ⇑ Corresponding author. Fax: +82 54 279 2299. E-mail address: [email protected] (H. Song In this paper, we present a novel fountain code-based mobile IPTV multicast system architecture over WiMAX network. In the proposed system, the transmission algorithm at a base station determines the control parameters of...

Reducing energy and power consumption is important for many reasons, including extending the lifetime of battery operated devices and reducing energy bills. An important source of energy loss in wireless networks comes from retransmissions of lost packets. Many of the transmission protocols in use today were designed mainly to be used in wired IP networks, and therefore performs bad in wireless...

We have performed high resolution 3D simulations with adaptive mesh refinement, following the ISM evolution in a star forming galaxy both on small (<1 pc) and large (>10 kpc) scales, enabling us to track structures in cooling shock compressed regions as well as the entire Galactic fountain flow. It is shown in an MHD run that the latter one is not inhibited by a large scale disk parallel magnet...

help parents who decide?or are compelled by lack of other provision?to look after their children at home. Dr. Jack Tizard and Dr. Jacqueline Grad have set out some of the problems faced by parents of retarded children, saying that 'for substantial numbers effective social intervention might have made hospital care unnecessary'. is perhaps some measure of the severe physical and emotional proble...

We describe the operation of a laser cooled cesium fountain clock in the quantum limited regime. An ultrastable cryogenic sapphire oscillator is used to measure the short-term frequency stability of the fountain as a function of the number of detected atoms Nat. For Nat varying from 4 3 104 to 6 3 105 the Allan standard deviation of the frequency fluctuations is in excellent agreement with the ...