We investigate the effect of a directional antenna in wireless sensor networks from the perspective of network lifetime extension. Previous studies on wireless sensor networks have assumed only an omni-directional antenna model, since a directional antenna has been considered inappropriate for sensors due to size and cost constraints. In this sense, we propose to mount the directional antenna o...

We present a theory extending the source-sink concept with an ecosystem perspective. We analyze a model for meta-ecosystem dynamics in a heterogeneous environment to study how the spatial flows of materials such as inorganic nutrients and nutrients sequestered into producers, herbivores, and detritus affect the community dynamics. We show that spatial flows of an inorganic nutrient (direct nutr...

Gas exchange, chlorophyll fluorescence, photosynthetic end products and related enzymes in source leaves in response to low sink demand after girdling to remove the root sink were assessed in young apple trees (Malus pumila) grown in two greenhouses with different air temperatures for 5 days. Compared with the non-girdled control in the low-temperature greenhouse (diurnal maximum air temperatur...

a sensor network is made up of a large number of sensors with limited energy. sensors collect environmental data then send them to the sink. energy efficiency and thereby increasing the lifetime of sensor networks is important. direct transfer of the data from each node to the central station will increase energy consumption. previous research has shown that the organization of nodes in cluster...

Salinization of water and soil has a negative impact on tomato (Solanum lycopersicum L.) productivity by reducing growth of sink organs and by inducing senescence in source leaves. It has been hypothesized that yield stability implies the maintenance or increase of sink activity in the reproductive structures, thus contributing to the transport of assimilates from the source leaves through chan...

Due to the limited transmission range, data sensed by each sensor has to be forwarded in a multi-hop fashion before being delivered to the sink. The sensors closer to the sink have to forward comparatively more messages than sensors at the periphery of the network,and will deplete their batteries earlier. Besides the loss of the sensing capabilities of the nodes close to the sink, a more seriou...

PURPOSE To assess by means of computer simulations whether the heat sink effect inside a large vessel (portal vein) could protect the vessel wall from thermal damage close to an internally cooled electrode during radiofrequency (RF)-assisted resection. METHODS First,in vivo experiments were conducted to validate the computational model by comparing the experimental and computational thermal l...