16,614 research outputs found
The Vietnamese shrimp trade: livelihoods analysis of stakeholders and market chain analysis
Aquaculture and capture fisheries in Vietnam have been increasing fast in the last decade, especially aquaculture growth rate is 12% for the 1999 – 2003 period, contributing a significant part into the hunger eradication and poverty reduction1. Vietnam is to be ranked into one of the countries potential to produce the aquatic economic in the world, and the fact is that, after 40 years of establishing, the fisheries sector has made remarkable contributions to the country. By the list, at the moment the aquatic products make up about 4 - 5% of GDP and create job opportunities for over 3 three million
employees (VASEP, 2004), in which the largest contribution is from shrimp farming. [PDF contains 124 pages.
The contingent roles of perceived budget fairness, budget goal commitment and vertical information sharing in driving work performance
Drawing on equity theory, social exchange theory and goal setting theory, the purpose of this paper is to investigate the contingencies on the link between employees’ budgetary participation and their work performance. Specifically, this study addresses the research questions: whether vertical information sharing and budget goal commitment mediate the relationship between employees’ budgetary participation and their work performance; and whether employees’ perceived budget fairness can strengthen the positive effects of budgetary participation on vertical information sharing and budget goal commitment
Approximating the minimum directed tree cover
Given a directed graph with non negative cost on the arcs, a directed
tree cover of is a rooted directed tree such that either head or tail (or
both of them) of every arc in is touched by . The minimum directed tree
cover problem (DTCP) is to find a directed tree cover of minimum cost. The
problem is known to be -hard. In this paper, we show that the weighted Set
Cover Problem (SCP) is a special case of DTCP. Hence, one can expect at best to
approximate DTCP with the same ratio as for SCP. We show that this expectation
can be satisfied in some way by designing a purely combinatorial approximation
algorithm for the DTCP and proving that the approximation ratio of the
algorithm is with is the maximum outgoing degree of
the nodes in .Comment: 13 page
Behavior and the Response of Cancer Cells on Anticancer Drug Treatment Monitored with Microelectrode Array
AbstractA cell-based impedance biosensor using microelectrode array has been developed for monitoring cellular activities of MCF-7 breast cancer cells and evaluating drug-induced apoptosis. Using this device, different activities of cells such as cell attachment, adhesion, and spreading are monitored by measuring impedance spectra and interpreting the data using an electrical equivalent circuit. In order to demonstrate pharmaceutical relevance, the cells were treated with 25μM of anti-cancer drug Cisplatin. It was found that cell spreading caused a significant increase of impedance magnitude in the frequency range between 10kHz and 100kHz during 23h of incubation, which is reversed after 24h treatment with Cisplatin. This reversal is attributed to cell apoptosis, which is confirmed by microscopic observation of the cells
Device-spectroscopy of magnetic field effects in a polyfluorene organic light-emitting diode
We perform charge-induced absorption and electroluminescence spectroscopy in
a polyfluorene organic magnetoresistive device. Our experiments allow us to
measure the singlet exciton, triplet exciton and polaron densities in a live
device under an applied magnetic field, and to distinguish between three
different models that were proposed to explain organic magnetoresistance. These
models are based on different spin-dependent interactions, namely exciton
formation, triplet exciton-polaron quenching and bipolaron formation. We show
that the singlet exciton, triplet exciton and polaron densities and
conductivity all increase with increasing magnetic field. Our data are
inconsistent with the exciton formation and triplet-exciton polaron quenching
models.Comment: 4 pages, two figure
Polyelectrolyte Persistence Length: Attractive Effect of Counterion Correlations and Fluctuations
The persistence length of a single, strongly charged, stiff polyelectrolyte
chain is investigated theoretically. Path integral formulation is used to
obtain the effective electrostatic interaction between the monomers. We find
significant deviations from the classical Odijk, Skolnick and Fixman (OSF)
result. An induced attraction between monomers is due to thermal fluctuations
and correlations between bound counterions. The electrostatic persistence
length is found to be smaller than the OSF value and indicates a possible
mechanical instability (collapse) for highly charged polyelectrolytes with
multivalent counterions. In addition, we calculate the amount of condensed
counterions on a slightly bent polyelectrolyte. More counterions are found to
be adsorbed as compared to the Manning condensation on a cylinder.Comment: 5 pages, 1 ps figur
Parallel Imaging with RASER using Multiband Frequency-modulated Excitation Pulses
The many advantages of the recently proposed RASER sequence have been demonstrated. Hence, RASER holds great promises for functional MRI (fMRI), particularly for studies of the orbital-frontal cortex and other brain regions near air cavities, which cause distortion and signal loss in conventional EPI methods. However, the single-shot RASER sequence implemented so far inherently presents a set of temporal and spatial limitations that hinders it feasibility and full potential for fMRI applications. It is believed that parallel imaging will help overcome such restrictions. In this work, the RASER acquisition and reconstruction scheme is extended for parallel imaging using tailored pulses for simultaneous multi-band excitation
Kohn-Sham scheme for frequency dependent linear response
We study the Kohn-Sham scheme for the calculation of the steady state linear
response to a harmonic perturbation that is turned on adiabatically. Although
in general the exact time dependent exchange-correlation potential cannot be
expressed as the functional derivative of a universal functional due to the
so-called causality paradox, we show that for a harmonic perturbation the
exchange-correlation part of the first-order Kohn-Sham potential is given by . is the exchange-correlation part of the
second-order quasienergy . The Frenkel variation principle implies a
stationary principle for the second-order quasienergy. We also find an
analogous stationary principle and KS scheme in the time dependent extension of
one-matrix functional theory, in which the basic variable is the one-matrix
(one-body reduced density matrix).Comment: 11 pages; minor corrections; details adde
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