This traffic-shaping effect of network coding can be readily applied to cognitive radio networks. In particular, we develop adaptive spectrum sensing for secondary users (SUs) to exploit the induced predictability in primary user channels with network-coded transmissions and show that the throughput of SUs is significantly improved. On the other hand, we caution

that the predictable structure of network-coded transmissions also makes wireless channels more susceptible to jamming attacks. Our results lead to a new understanding of network coding as a spectrum shaper and reveal the inherent tradeoffs between the throughput and security objectives resulting from the spectrum predictability induced by network coding.”
“Foraging distance is a key determinant of colony survival and pollination potential BEZ235 molecular weight in bumblebees Bombus spp. However this aspect of bumblebee ecology is poorly Fer-1 molecular weight understood because of the difficulty

in locating colonies of these central place foragers. Here, we used a combination of molecular microsatellite analyses, remote sensing and spatial analyses using kernel density estimates to estimate nest location and foraging distances for a large number of wild colonies of two species, and related these to the distribution of foraging habitats across an experimentally manipulated landscape. Mean foraging distances were 755 m for Bombus lapidarius and 775 m for B. pascuorum (using our most conservative estimation method). Colony-specific foraging distances of both species varied with landscape structure, decreasing as the proportion of foraging habitats increased. This is the first time that foraging distance

in wild bumblebees has been shown to vary with resource availability. Our method offers a means of estimating foraging distances selleck in social insects, and informs the scale of management required to conserve bumblebee populations and enhance their pollination services across different landscapes.”
“Introduction Up to half of all children presenung to Nutrition Rehabilitation Units (NRUs) in Malawi with severe acute malnutrition (SAM) are infected with HIV There are many similarities in the clinical presentation of SAM and HIV. to improve case management. This study aims to identify features suggestive of HIV in children with SAM\n\nMethods All 1024 children admitted to the Blantyre NRU between July 2006 and March 2007 had demographic, anthropometric and clinical characteristics documented on admission. HIV status was known for 904 children, with 445 (43%) seropositive and 459 (45%) seronegative Features associated with HIV were determined\n\nResults Associations were found for the following signs: chronic ear discharge (OR 14.6, 95% 5 8-36 7), lymphadenopathy (6.4, 3.5-11 7), Clubbing (4.9, 2.6-9.4), maraSMILIS (4 9, 3.56.8), hepato-splenomegally (3.2, 1.8-5.6), and oral candida (2.4, 1 8-3 27). Any one of these signs was present in 74% of the HIV seropositive, and 38% of HIV uninfected children.