Tibetan sheep are better able to cope with low energy intake than Small-tailed Han sheep due to lower maintenance energy requirements and higher nutrient digestibilities

Tibetan sheep are indigenous to the Qinghai-Tibetan Plateau (QTP) and are well-adapted to and even thrive under the harsh alpine conditions. Small-tailed Han sheep were introduced to the plateau because of their high prolificacy and are maintained mainly in feedlots. Because of their different backgrounds, we hypothesised that Tibetan and Small-tailed Han sheep would differ in their utilization of energy intake and predicted that Tibetan sheep would cope better with low energy intake than Small-tailed Han sheep. To test this prediction, we determined nutrient digestibilities, energy requirements for maintenance and blood metabolite and hormone concentrations involved in energy metabolism in these breeds. Sheep of each breed (n = 24 of each, all wethers and 1.5 years of age) were distributed randomly into one of four groups and offered ad libitum diets of different digestible energy (DE) densities: 8.21, 9.33, 10.45 and 11.57 MJ DE/kg Dry matter (DM). Following 42 d of measuring feed intake, a 1-week digestion and metabolism experiment was done. DM intakes did not differ between breeds nor among treatments but, by design, DE intake increased linearly in both breeds as dietary energy level increased (P < 0.001). The average daily gain (ADG) was significantly greater in the Tibetan than Small-tailed Han sheep (P = 0.003) and increased linearly in both breeds (P < 0.001). In addition, from the regression analysis of ADG on DE intake, daily DE maintenance requirements were lower for Tibetan than for Small-tailed Han sheep (0.41 vs 0.50 MJ/BW0.75, P < 0.05). The DE and metabolizable energy (ME) digestibilities were higher in the Tibetan than Small-tailed Han sheep (P < 0.001) and increased linearly as the energy level increased in the diet (P < 0.001). At the lowest energy treatment, Tibetan sheep when compared with Small-tailed Han sheep, had: 1) higher serum glucose and glucagon, but lower insulin concentrations (P < 0.05), which indicated a higher capacity for gluconeogenesis and ability to regulate glucose metabolism; and 2) higher non-esterified fatty acids (NEFA) and lower very low density lipoprotein (VLDL) and triglyceride (TG) concentrations (P < 0.05), which indicated a higher capacity for NEFA oxidation but lower ability for triglyceride (TG) synthesis. We concluded that our prediction was supported as these differences between breeds conferred an advantage for Tibetan over Small-tailed Han sheep to cope better with low energy diets

Plasma-enhanced chemical vapor deposition of thick silicon nitride films with low stress on InP

We have developed a low-temperature plasma-enhanced chemical vapor deposition process that facilitates the deposition of silicon nitride films with controlled stress by using periodically alternating high- and low-frequency power sources. Very thick films of 3 mu m with low stress were deposited on InP substrates. Suitable sidewall profiles for metallization are obtained at 250 degrees C deposition temperature. A 3- mu m-thick low-stress nitride film was successfully applied to reduce the capacitance of bond pad for an array of four InP based photodetectors, that were integrated with a four channel phased-array wavelength demultiplexer. The capacitance of the detectors was below 0.5 pF at -5 V bia

Plasma-enhanced chemical vapor deposition of thick silicon nitride films with low stress on InP

We have developed a low-temperature plasma-enhanced chemical vapor deposition process that facilitates the deposition of silicon nitride films with controlled stress by using periodically alternating high- and low-frequency power sources. Very thick films of 3 mu m with low stress were deposited on InP substrates. Suitable sidewall profiles for metallization are obtained at 250 degrees C deposition temperature. A 3- mu m-thick low-stress nitride film was successfully applied to reduce the capacitance of bond pad for an array of four InP based photodetectors, that were integrated with a four channel phased-array wavelength demultiplexer. The capacitance of the detectors was below 0.5 pF at -5 V bia

Coupled Hartree-Fock-Bogoliubov kinetic equations for a trapped Bose gas

Using the Kadanoff-Baym non-equilibrium Green's function formalism, we derive the self-consistent Hartree-Fock-Bogoliubov (HFB) collisionless kinetic equations and the associated equation of motion for the condensate wavefunction for a trapped Bose-condensed gas. Our work generalizes earlier work by Kane and Kadanoff (KK) for a uniform Bose gas. We include the off-diagonal (anomalous) pair correlations, and thus we have to introduce an off-diagonal distribution function in addition to the normal (diagonal) distribution function. This results in two coupled kinetic equations. If the off-diagonal distribution function can be neglected as a higher-order contribution, we obtain the semi-classical kinetic equation recently used by Zaremba, Griffin and Nikuni (based on the simpler Popov approximation). We discuss the static local equilibrium solution of our coupled HFB kinetic equations within the semi-classical approximation. We also verify that a solution is the rigid in-phase oscillation of the equilibrium condensate and non-condensate density profiles, oscillating with the trap frequency.Comment: 25 page

A Two-Step Quantum Direct Communication Protocol Using Einstein-Podolsky-Rosen Pair Block

A protocol for quantum secure direct communication using blocks of EPR pairs is proposed. A set of ordered $N$ EPR pairs is used as a data block for sending secret message directly. The ordered $N$ EPR set is divided into two particle sequences, a checking sequence and a message-coding sequence. After transmitting the checking sequence, the two parties of communication check eavesdropping by measuring a fraction of particles randomly chosen, with random choice of two sets of measuring bases. After insuring the security of the quantum channel, the sender, Alice encodes the secret message directly on the message-coding sequence and send them to Bob. By combining the checking and message-coding sequences together, Bob is able to read out the encoded messages directly. The scheme is secure because an eavesdropper cannot get both sequences simultaneously. We also discuss issues in a noisy channel.Comment: 8 pages and 2 figures. To appear in Phys Rev

Spinodal Decomposition in a Binary Polymer Mixture: Dynamic Self Consistent Field Theory and Monte Carlo Simulations

We investigate how the dynamics of a single chain influences the kinetics of early stage phase separation in a symmetric binary polymer mixture. We consider quenches from the disordered phase into the region of spinodal instability. On a mean field level we approach this problem with two methods: a dynamical extension of the self consistent field theory for Gaussian chains, with the density variables evolving in time, and the method of the external potential dynamics where the effective external fields are propagated in time. Different wave vector dependencies of the kinetic coefficient are taken into account. These early stages of spinodal decomposition are also studied through Monte Carlo simulations employing the bond fluctuation model that maps the chains -- in our case with 64 effective segments -- on a coarse grained lattice. The results obtained through self consistent field calculations and Monte Carlo simulations can be compared because the time, length, and temperature scales are mapped onto each other through the diffusion constant, the chain extension, and the energy of mixing. The quantitative comparison of the relaxation rate of the global structure factor shows that a kinetic coefficient according to the Rouse model gives a much better agreement than a local, i.e. wave vector independent, kinetic factor. Including fluctuations in the self consistent field calculations leads to a shorter time span of spinodal behaviour and a reduction of the relaxation rate for smaller wave vectors and prevents the relaxation rate from becoming negative for larger values of the wave vector. This is also in agreement with the simulation results.Comment: Phys.Rev.E in prin

Exact eigenstate analysis of finite-frequency conductivity in graphene

We employ the exact eigenstate basis formalism to study electrical conductivity in graphene, in the presence of short-range diagonal disorder and inter-valley scattering. We find that for disorder strength, $W \ge$ 5, the density of states is flat. We, then, make connection, using the MRG approach, with the work of Abrahams \textit{et al.} and find a very good agreement for disorder strength, $W$ = 5. For low disorder strength, $W$ = 2, we plot the energy-resolved current matrix elements squared for different locations of the Fermi energy from the band centre. We find that the states close to the band centre are more extended and falls of nearly as $1/E_l^{2}$ as we move away from the band centre. Further studies of current matrix elements versus disorder strength suggests a cross-over from weakly localized to a very weakly localized system. We calculate conductivity using Kubo Greenwood formula and show that, for low disorder strength, conductivity is in a good qualitative agreement with the experiments, even for the on-site disorder. The intensity plots of the eigenstates also reveal clear signatures of puddle formation for very small carrier concentration. We also make comparison with square lattice and find that graphene is more easily localized when subject to disorder.Comment: 11 pages,15 figure