108 research outputs found
Oxidative damage and changes in Glutathione S-transferase activity in juvenile African catfish, Clarias gariepinus exposed to cypermethrin and chlorpyrifos
Cypermethrin and chlorpyrifos are broad-spectrum insecticides routinely
used as household and agricultural insecticides. Since aquatic
environments serve as sinks for numerous environmental pollutants, the
effects of these substances on the resident aquatic organisms can be
quite serious. In this study, we investigated the effects of exposure
of African catfish to cypermethrin and chlorpyrifos on oxidative damage
and the activity of glutathione S-transferase (GST). Juvenile African
catfish were exposed to 1.25 \ub5g/L cypermethrin, 1.25 \ub5g/L
chlorpyrifos, 2.5 \ub5g/L cypermethrin or 2.5 \ub5g/L chlorpyrifos
for 96 h. Control fish were maintained in borehole water. At the end of
the 96 h exposure, tissue lipid peroxidation (LPO), protein
carbonylation and GST activities were determined. Contaminant exposure
resulted in a significant increase (p < 0.05) in the levels of LPO
and protein carbonylation and the activity of GST in the gills, liver
and muscle of exposed fish compared to the controls. Oxidative damage
was more serious in the groups exposed to chlorpyrifos compared to
those exposed to cypermethrin, thus implying that chlorpyrifos is more
toxic to these fish than cypermethrin. The results of this study
indicate that the pollution of aquatic ecosystems with cypermethrin and
chlorpyrifos may cause oxidation of biomolecules (lipids and proteins)
that are involved in essential physiological and biochemical activities
in animals
Paying to Save: Tax Withholding and Asset Allocation among Low- and Moderate-Income Taxpayers
Medium modification of jet fragmentation in Au+Au collisions at sqrt(s_NN)=200 GeV measured in direct photon-hadron correlations
The jet fragmentation function is measured with direct photon-hadron
correlations in p+p and Au+Au collisions at sqrt(s_NN)=200 GeV. The p_T of the
photon is an excellent approximation to the initial p_T of the jet and the
ratio z_T=p_T^h/p_T^\gamma is used as a proxy for the jet fragmentation
function. A statistical subtraction is used to extract the direct photon-hadron
yields in Au+Au collisions while a photon isolation cut is applied in p+p. I_
AA, the ratio of jet fragment yield in Au+Au to that in p+p, indicates
modification of the jet fragmentation function. Suppression, most likely due to
energy loss in the medium, is seen at high z_T. The fragment yield at low z_T
is enhanced at large angles. Such a trend is expected from redistribution of
the lost energy into increased production of low-momentum particles.Comment: 562 authors, 70 insitutions, 8 pages, and 3 figures. Submitted to
Phys. Rev. Lett. v2 has minor changes to improve clarity. Plain text data
tables for the points plotted in figures for this and previous PHENIX
publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Transverse energy production and charged-particle multiplicity at midrapidity in various systems from to 200 GeV
Measurements of midrapidity charged particle multiplicity distributions,
, and midrapidity transverse-energy distributions,
, are presented for a variety of collision systems and energies.
Included are distributions for AuAu collisions at ,
130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, CuCu collisions at
and 62.4 GeV, CuAu collisions at
GeV, UU collisions at GeV,
Au collisions at GeV, HeAu collisions at
GeV, and collisions at
GeV. Centrality-dependent distributions at midrapidity are presented in terms
of the number of nucleon participants, , and the number of
constituent quark participants, . For all collisions
down to GeV, it is observed that the midrapidity data
are better described by scaling with than scaling with . Also presented are estimates of the Bjorken energy density,
, and the ratio of to ,
the latter of which is seen to be constant as a function of centrality for all
systems.Comment: 706 authors, 32 pages, 20 figures, 34 tables, 2004, 2005, 2008, 2010,
2011, and 2012 data. v2 is version accepted for publication in Phys. Rev.
The long-run behaviour of the terms of trade between primary commodities and manufactures : a panel data approach
This paper examines the Prebisch and Singer hypothesis using a panel of twenty-four commodity prices from 1900 to 2010. The modelling approach stems from the need to meet two key concerns: (i) the presence of cross-sectional dependence among commodity prices; and (ii) the identification of potential structural breaks. To address these concerns, the Hadri and Rao (Oxf Bull Econ Stat 70:245–269, 2008) test is employed. The findings suggest that all commodity prices exhibit a structural break whose location differs across series, and that support for the Prebisch and Singer hypothesis is mixed. Once the breaks are removed from the underlying series, the persistence of commodity price shocks is shorter than that obtained in other studies using alternative methodologies.info:eu-repo/semantics/publishedVersio
Rational Asymmetric Development: Transfer Pricing and Sub-Saharan Africa's Extreme Poverty Tragedy
Physical and cultural inheritance enhance agency, but what are the origins of this concern to establish a legacy? A nationally-representative twin study of Erikson’s concept of generativity.
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