1,319 research outputs found
A Simple But Effective Evolutionary Algorithm for Complicated Optimization Problems
A simple but effective evolutionary algorithm is proposed in this paper for solving complicated optimization problems. The new algorithm presents two hybridization operations incorporated with the conventional genetic algorithm. It takes only 4.1% ~ 4.7% number of function evaluations required by the conventional genetic algorithm to obtain global optima for the benchmark functions tested. Application example is also provided to demonstrate its effectiveness.Singapore-MIT Alliance (SMA
Calcium-sensing receptor activation increases cell-cell adhesion and ß-cell function
Background/Aims: The extracellular calcium-sensing receptor (CaR) is expressed in pancreatic β-cells where it is thought to facilitate cell-to-cell communication and augment insulin secretion. However, it is unknown how CaR activation improves β-cell function. Methods: Immunocytochemistry and western blotting confirmed the expression of CaR in MIN6 β-cell line. The calcimimetic R568 (1µM) was used to increase the affinity of the CaR and specifically activate the receptor at a physiologically appropriate extracellular calcium concentration. Incorporation of 5-bromo-2’-deoxyuridine (BrdU) was used to measure cell proliferation, whilst changes in non-nutrient-evoked cytosolic calcium were assessed using fura-2-microfluorimetry. AFM-single-cell-force spectroscopy related CaR-evoked changes in epithelial (E)-cadherin expression to improved functional tethering between coupled cells. Results: Activation of the CaR over 48hr doubled the expression of E-cadherin (206±41%) and increased L-type voltage-dependent calcium channel expression by 70% compared to control. These changes produced a 30% increase in cell-cell tethering and elevated the basal-to-peak amplitude of ATP (50µM) and tolbutamide (100µM)-evoked changes in cytosolic calcium. Activation of the receptor also increased PD98059 (1-100µM) and SU1498 (1-100µM)-dependent β-cell proliferation. Conclusion: Our data suggest that activation of the CaR increases E-cadherin mediated functional tethering between β-cells and increases expression of L-type VDCC and secretagogue-evoked changes in [Ca2+]i. These findings could explain how local changes in calcium, co-released with insulin, activate the CaR on neighbouring cells to help ensure efficient and appropriate secretory function
Botanical composition, production and nutrient status of an originally Lolium perenne-dominant cut grass sward receiving long-term manure applications
Effects of long-term applications (50, 100 and 200 m(3) ha(-1)y(-1)) of pig and cow slurries on yield, botanical composition and nutrient content of herbage of an original perennial ryegrass sward were assessed in a three-cut silage system and compared with unamended and fertilized controls in the 36th year of the experiment. Cow slurry at 50 m(3) ha(-1) produced similar annual herbage DM yield to 200 kg ha(-1) fertilizer N in 2006, whereas about 100 m(3) ha(-1) pig slurry were required to produce a similar amount of DM. The highest slurry application rate significantly influenced sward botanical composition without depressing DM yield. The principal invading species were creeping bent and meadow grasses (similar to findings at a previous assessment in 1981) except in the unamended control (which were common bent and Yorkshire fog). Perennial ryegrass remained a main species in plots receiving fertilizer (31 % annual DM yield) and low slurry rates (38 %) but declined to 3 % annual DM yield at the highest slurry rate where the ability of ryegrass to utilize slurry N and P may have been affected by chemically or physically induced deficiencies of other nutrients (e.g. Ca) or direct physical effects such as smothering
A fabrication history based strain-fatigue model for prediction of crack initiation in a radial loading wheel
A strain-based fatigue model concerning fabrication history is applied to predict the fatigue life of a commercial car wheel under radial loads. As the prior conditions, the strain fatigue testing is performed on standard specimen of DP590 and FB540 steels at various fabrication states, including raw materials, pre-strain and pre-strain + bake. Furthermore, the strain distribution of car wheel during its rotation under radial loads is simulated via ANSYS. The fatigue properties mainly determined by crack initiation of car wheels at various fabrication states are predicted via local stress–strain method, in which the scale and surface factors are also taken into account. The radial fatigue testing is carried out, and the results are used to validate the present model. The fracture mechanism is analysed using FEI Nova 400 field emission gun scanning electron microscope
Crambe meal : evaluation, improvement and comparison with rapeseed meal
Crambe abyssinica has gradually been introduced in agriculture as a new oil-bearing crop. Its oil contains 55 to 60% erucic acid (C22:1, Δ13), desirable as lubricants, plastic additives or as a raw material for chemical synthesis. The defatted meal has high protein content which provides potential as an animal feed. However, crambe seeds contain glucosinolates as a negative factor in nutrition. The aim of this study was to obtain a clear view of the possibilities and constraints of crambe by-products as feedstuff. The investigation showed the decorticated and defatted crmabe meal contains nearly 50 % protein with an amino acid profile similar to rape. Crambe meal has low contents of cell wall constituents and high energy digestibility in both rats and pigs. The seed pericarp is fibrous and therefore poorly digested in cows. The level of glucosinolates in crambe seed is higher than in traditional rapeseeds, with an epi- progoitrin domination. Several approaches were investigated to remove crambe glucosinolates, which revealed possibilities and inclusion levels in animal feeding. Furthermore, two studies were carried out on rapeseed meal concerning detoxification treatments and their effect on the nutritive value. The final chapter discussed crambe meal's perspectives and future research areas
The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry
The Pobei mafic-ultramafic complex in northwestern China comprises magmatic Cu-Ni sulfide ore deposits coexisting with Fe-Ti oxide deposits. The Poshi, Poyi, and Podong ultramafic intrusions host the Cu-Ni ore. The ultramafic intrusions experienced four stages during its formation. The intrusion sequence was as follows: dunite, hornblende-peridotite, wehrlite and pyroxenite. The wall rock of the ultramafic intrusions is the gabbro intrusion in the southwestern of the Pobei complex. The Xiaochangshan magmatic deposit outcrops in the magnetitemineralized gabbro in the northeastern part of the Pobei complex. The main emplacement events related to the mineralization in the Pobei complex, are the magnetite-mineralized gabbro related to the Xiaochangshan Fe deposit, the gabbro intrusion associated to the Poyi, Poshi and Podong Cu-Ni deposits, and the ultramafic intrusions that host Cu-Ni deposits (Poyi and Poshi). The U-Pb age of the magnetite-mineralized gabbro is 276±1.7Ma, which is similar to that of the Pobei mafic intrusions. The εHf(t) value of zircon in the magnetite-mineralized gabbro is almost the same as that of the gabbro around the Poyi and Poshi Cu-Ni deposits, indicating that the rocks related to Cu-Ni and magnetite deposits probably originated from the same parental magma. There is a trend of crystallization differentiation evolution in the Harker diagram from the dunite in the Cu-Ni deposit to the magnetite-mineralized gabbro. The monosulfide solid solution fractional crystallization was weak in Pobei; thus, the Pd/Ir values were only influenced by the crystallization of silicate minerals. The more complete the magma evolution is, the greater is the Pd/Ir ratio. The Pd/Ir values of dunite, the lithofacies containing sulfide (including hornblende peridotite, wehrlite, and pyroxenite) in the Poyi Cu-Ni deposit, magnetite-mineralized gabbro, and massive magnetite, are 8.55, 12.18, 12.26, and 18.14, respectively. Thus, the massive magnetite was probably the latest product in the evolution of the Pobei mafic-ultramafic intrusions. We infer that the Cu-Ni sulfide and Fe-Ti oxide ores in the Pobei area were products of a cogenetic magma at different evolutionary stages; at the late stage, the magma became iron enriched through crystallization differentiation. The magma differentiation occurred in a deep staging magma chamber emplaced in the upper magma chamber. Earlier crystallized olivine with some interstitial sulfides gathered at the bottom of the staging magma chamber because of its greater density. That is to say, the ultramafic magma hosting the Cu-Ni sulfide formed at the bottom of the staging magma chamber, while the magnetite-mineralized gabbro was in the upper part. However, the magnetite-mineralized gabbro injected into the upper magma chamber first and the ultramafic lithofacies containing the olivine and the interstitial Cu-Ni sulfides were subsequently emplaced in the upper magma chamber as crystal mush
Influence of Fermi surface topology on the quasiparticle spectrum in the vortex state
We study the influence of Fermi surface topology on the quasiparticle density
of states in the vortex state of type II superconductors. We observe that the
field dependence and the shape of the momentum and spatially averaged density
of states is affected significantly by the topology of the Fermi surface. We
show that this behavior can be understood in terms of characteristic Fermi
surface functions and that an important role is played by the number of points
on the Fermi surface at which the Fermi velocity is directed parallel to the
magnetic field. A critical comparison is made with a broadened BCS type density
of states, that has been used frequently in analysis of tunneling data. We
suggest a new formula as a replacement for the broadened BCS model for the
special case of a cylindrical Fermi surface. We apply our results to the two
gap superconductor MgB and show that in this particular case the field
dependence of the partial densities of states of the two gaps behaves very
differently due to the different topologies of the corresponding Fermi
surfaces, in qualitative agreement with recent tunneling experiments.Comment: 12 pages 12 figure
Nucleon-nucleon momentum correlation function for light nuclei
Nucleon-nucleon momentum correlation function have been presented for nuclear
reactions with neutron-rich or proton-rich projectiles using a nuclear
transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model.
The relationship between the binding energy of projectiles and the strength of
proton-neutron correlation function at small relative momentum has been
explored, while proton-proton correlation function shows its sensitivity to the
proton density distribution. Those results show that nucleon-nucleon
correlation function is useful to reflect some features of the neutron- or
proton-halo nuclei and therefore provide a potential tool for the studies of
radioactive beam physics.Comment: Talk given at the 18th International IUPAP Conference on Few-Body
Problems in Physics (FB18), Santos, Brasil, August 21-26, 2006. To appear in
Nucl. Phys.
Grooming of Dynamic Traffic in WDM Star and Tree Networks Using Genetic Algorithm
The advances in WDM technology lead to the great interest in traffic grooming
problems. As traffic often changes from time to time, the problem of grooming
dynamic traffic is of great practical value. In this paper, we discuss dynamic
grooming of traffic in star and tree networks. A genetic algorithm (GA) based
approach is proposed to support arbitrary dynamic traffic patterns, which
minimizes the number of ADM's and wavelengths. To evaluate the algorithm,
tighter bounds are derived. Computer simulation results show that our algorithm
is efficient in reducing both the numbers of ADM's and wavelengths in tree and
star networks.Comment: 15 page
Lattice dynamics and electron-phonon coupling in transition metal diborides
The phonon density-of-states of transition metal diborides TMB2 with TM = Ti,
V, Ta, Nb and Y has been measured using the technique of inelastic neutron
scattering. The experimental data are compared with ab initio density
functional calculations whereby an excellent agreement is registered. The
calculations thus can be used to obtain electron-phonon spectral functions
within the isotropic limit. A comparison to similar data for MgB2 and AlB2
which were subject of prior publications as well as parameters important for
the superconducting properties are part of the discussion.Comment: 4 pages, 3 figure
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