47,548 research outputs found
Trade Liberalisation Policies, Intra-regional Trade and Opportunities for Sustainable Agricultural Development
Many of the Near East (NE) countries are currently opening their agricultural markets at three distinct but interacting levels: unilateral liberalisation, regional integration schemes and multilateral trade liberalisation. These changes hold important implications for intra- and extra-regional trade, use of agricultural resources and sustainability of agricultural development in the NE countries. Unilaterally, and since the late 1980s, most countries of the region have liberalised their agriculture sectors by eliminating or reducing input subsidies, removing or reducing guaranteed producer prices, reducing the number of subsidised commodities and liberalising the exchange rate and the trade regime. Most of the implicit and explicit subsidies for agricultural inputs and outputs were withdrawn. However, some of the NE countries were able to continue supporting agriculture mainly for food security reasons. Experiences showed that domestic reform is necessary but not sufficient condition for economic growth.
Frustrated Metastable Behavior of Magnetic and Transport Properties in Charge Ordered La1-xCaxMnO3+d Manganites
We have studied the effect of metastable, irreversibility induced by repeated
thermal cycles on the electric transport and magnetization of polycrystalline
samples of La1-xCaxMnO3 (0.48\leq x \leq 0.55) close to charge ordering. With
time and thermal cycling (T<300 K) there is an irreversible transformation of
the low-temperature phase from a partially ferromagnetic and metallic to one
that is less ferromagnetic and highly resistive for the composition close to
charge ordering (x=050 and 0.52). Irrespective of the actual ground state of
the compound, the effect of thermal cycling is towards an increase of the
amount of the insulating phase. We have observed the magnetic relaxation in the
metastable state and also the revival of the metastable state (in a relaxed
sample) due to high temperature thermal treatment. We observed changes in the
resistivity and magnetization as the revived metastable state is cycled. The
time changes in the magnetization are logarithmic in general and activation
energies are consistent with those expected for electron transfer between Mn
ions. Changes induced by thermal cycling can be inhibited by applying magnetic
field. These results suggest that oxygen non-stoichiometry results in
mechanical strains in this two-phase system, leading to the development of
frustrated metastable states which relax towards the more stable charge-ordered
and antiferromagnetic microdomains. Our results also suggest that the growth
and coexistence of phases gives rise to microstructural tracks and strain
accommodation, producing the observed irreversibility.Comment: 13 Pages, 10 Figure
Molecular dynamics simulations and in silico peptide ligand screening of the Elk-1 ETS domain
Background: The Elk-1 transcription factor is a member of a group of proteins called ternary complex factors, which serve as a paradigm for gene regulation in response to extracellular signals. Its deregulation has been linked
to multiple human diseases including the development of tumours. The work herein aims to inform the design of
potential peptidomimetic compounds that can inhibit the formation of the Elk-1 dimer, which is key to Elk-1
stability. We have conducted molecular dynamics simulations of the Elk-1 ETS domain followed by virtual screening.
Results: We show the ETS dimerisation site undergoes conformational reorganisation at the a1b1 loop. Through
exhaustive screening of di- and tri-peptide libraries against a collection of ETS domain conformations representing the dynamics of the loop, we identified a series of potential binders for the Elk-1 dimer interface. The di-peptides showed no particular preference toward the binding site; however, the tri-peptides made specific interactions with residues: Glu17, Gln18 and Arg49 that are pivotal to the dimer interface.
Conclusions: We have shown molecular dynamics simulations can be combined with virtual peptide screening to obtain an exhaustive docking protocol that incorporates dynamic fluctuations in a receptor. Based on our findings, we suggest experimental binding studies to be performed on the 12 SILE ranked tri-peptides as possible compounds for the design of inhibitors of Elk-1 dimerisation. It would also be reasonable to consider the score ranked tri-peptides as a comparative test to establish whether peptide size is a determinant factor of binding to the ETS domain
Length-scale cascade and spread rate of atomizing planar liquid jets
The primary breakup of a planar liquid jet is explored via direct numerical
simulation (DNS) of the incompressible Navier-Stokes equation with level-set
and volume-of-fluid interface capturing methods. PDFs of the local radius of
curvature and the local cross-flow displacement of the liquid-gas interface are
evaluated over wide ranges of the Reynolds number (), Weber number (),
density ratio and viscosity ratio. The temporal cascade of liquid-structure
length scales and the spread rate of the liquid jet during primary atomization
are analyzed. The formation rate of different surface structures, e.g. lobes,
ligaments and droplets, are compared for different flow conditions and are
explained in terms of the vortex dynamics in each atomization domain that we
identified recently. With increasing , the average radius of curvature of
the surface decreases, the number of small droplets increases, and the cascade
and the surface area growth occur at faster rates. The spray angle is mainly
affected by and density ratio, and is larger at higher , at higher
density ratios, and also at lower . The change in the spray spread rate
versus is attributed to the angle of ligaments stretching from the jet
core, which increases as decreases. Gas viscosity has negligible effect on
both the droplet-size distribution and the spray angle. Increasing the
wavelength-to-sheet-thickness ratio, however, increases the spray angle and the
structure cascade rate, while decreasing the droplet size. The smallest length
scale is determined more by surface tension and liquid inertia than by the
liquid viscosity, while gas inertia and liquid surface tension are the key
parameters in determining the spray angle.Comment: Submitted for publication to International Journal of Multiphase
Flow. 37 pages; 33 figure
Liquid jet pumped by rising gas bubbles
A two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. Bubbles provide a large buoyancy force and the associated drag on the liquid moves the liquid upward. The liquid pumped upward consists of the bubble wakes and the liquid brought into the jet region by turbulent entrainment. The expansion of the gas bubbles as they rise through the liquid is taken into account. The continuity and momentum equations are solved numerically for an axisymmetric air jet submerged in water. Water pumping rates are obtained as a function of air flow rate and depth of submergence. Comparisons are made with limited experimental information in the literature
Soil salinity-sodicity and land use suitability in the Fordwah Eastern Sadiqia (South) irrigated area
Soil salinity / Sodic soils / Soil classification / Soil surveys / Soil analysis / Groundwater development / Water table / Water quality / Land use / Irrigation canals / Farmer participation / Surface drainage / Subsurface drainage / Soil reclamation / Waterlogging / Pakistan / Fordwah Eastern Sadiqia / Bahawalnagar District
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