9 research outputs found
QoS Constrained Optimal Sink and Relay Placement in Planned Wireless Sensor Networks
We are given a set of sensors at given locations, a set of potential
locations for placing base stations (BSs, or sinks), and another set of
potential locations for placing wireless relay nodes. There is a cost for
placing a BS and a cost for placing a relay. The problem we consider is to
select a set of BS locations, a set of relay locations, and an association of
sensor nodes with the selected BS locations, so that number of hops in the path
from each sensor to its BS is bounded by hmax, and among all such feasible
networks, the cost of the selected network is the minimum. The hop count bound
suffices to ensure a certain probability of the data being delivered to the BS
within a given maximum delay under a light traffic model. We observe that the
problem is NP-Hard, and is hard to even approximate within a constant factor.
For this problem, we propose a polynomial time approximation algorithm
(SmartSelect) based on a relay placement algorithm proposed in our earlier
work, along with a modification of the greedy algorithm for weighted set cover.
We have analyzed the worst case approximation guarantee for this algorithm. We
have also proposed a polynomial time heuristic to improve upon the solution
provided by SmartSelect. Our numerical results demonstrate that the algorithms
provide good quality solutions using very little computation time in various
randomly generated network scenarios
Impromptu Deployment of Wireless Relay Networks: Experiences Along a Forest Trail
We are motivated by the problem of impromptu or as- you-go deployment of
wireless sensor networks. As an application example, a person, starting from a
sink node, walks along a forest trail, makes link quality measurements (with
the previously placed nodes) at equally spaced locations, and deploys relays at
some of these locations, so as to connect a sensor placed at some a priori
unknown point on the trail with the sink node. In this paper, we report our
experimental experiences with some as-you-go deployment algorithms. Two
algorithms are based on Markov decision process (MDP) formulations; these
require a radio propagation model. We also study purely measurement based
strategies: one heuristic that is motivated by our MDP formulations, one
asymptotically optimal learning algorithm, and one inspired by a popular
heuristic. We extract a statistical model of the propagation along a forest
trail from raw measurement data, implement the algorithms experimentally in the
forest, and compare them. The results provide useful insights regarding the
choice of the deployment algorithm and its parameters, and also demonstrate the
necessity of a proper theoretical formulation.Comment: 7 pages, accepted in IEEE MASS 201
Respostas ecofisiológicas e morfológicas do pau-rosa (Aniba rosaeodora Ducke) aos diferentes níveis de sombreamento, em condição de viveiro.
Publicado também em: Boletim da Faculdade de Ciências Agrárias do Pará, Belém, PA, n. 30, p. 119-132, jul./dez. 1998
Metabolic engineering of biosynthetic pathways leading to isoprenoids: Mono- and sesquiterpenes in plastids and cytosol
Development of pyridine dicoumarols as potent anti HIV-1 leads, targeting HIV-1 associated topoisomeraseIIβ kinase
Persistent pediatric gastro-intestinal myiasis: A case report of fly larval infestation with musca domestica with review of literature
The occurrence of dipterous fly larvae in human is termed as human myiasis. Human myiasis can be classified based on clinical condition it causes like cutaneous myiasis, ocular myiasis, urogenital myiasis and intestinal myiasis. Based on the need for a particular host, myiasis can be divided as specific myiasis, semi-specific myiasis. Accidental myiasis results when the fly larvae are deposited/ingested by human resulting in infestation, which is also called as pseudomyiasis. Fly larvae may be present on the dead and decaying organic matter and domestic animals like dog and cats which are naturally infested with fly larvae and can be source for infection in children. Very few cases have been retrieved from literature on the occurrence of intestinal myiasis in children throughout the world. We report a case of two siblings in the same family infested with dipterous fly larvae
Rv0474 is a copper-responsive transcriptional regulator that negatively regulates expression of RNA polymerase subunit in Mycobacterium tuberculosis
We characterize Rv0474, a putative transcriptional regulatory protein of Mycobacterium tuberculosis, which is found to function as a copper-responsive transcriptional regulator at toxic levels of copper. It is an autorepressor, but at elevated levels (10-250 m) of copper ions the repression is relieved resulting in an increase in Rv0474 expression. Copper-bound Rv0474 is recruited to the rpoB promoter leading to its repression resulting in the growth arrest of the bacterium. Mutational analysis showed that the helix-turn-helix and leucine zipper domains of Rv0474 are essential for its binding to Rv0474 and rpoB promoters, respectively. The mechanism of Rv0474-mediated rpoB regulation seems to be operational only in pathogenic mycobacteria that can persist inside the host