Thermal capacitator design rationale. Part 1: Thermal and mechanical property data for selected materials potentially useful in thermal capacitor design and construction

The thermal properties of paraffin hydrocarbons and hydrocarbon mixtures which may be used as the phase change material (PCM) in thermal capacitors are discussed. The paraffin hydrocarbons selected for consideration are those in the range from C11H24 (n-Undecane) to C20H42 (n-Eicosane). A limited amount of data is included concerning other properties of paraffin hydrocarbons and the thermal and mechanical properties of several aluminum alloys which may find application as constructional materials. Data concerning the melting temperature, transition temperature, latent heat of fusion, heat of transition, specific heat, and thermal conductivity of pure and commercial grades of paraffin hydrocarbons are given. An index of companies capable of producing paraffin hydrocarbons and information concerning the availability of various grades (purity levels) is provided

Metal-Insulator Transition of the LaAlO3-SrTiO3 Interface Electron System

We report on a metal-insulator transition in the LaAlO3-SrTiO3 interface electron system, of which the carrier density is tuned by an electric gate field. Below a critical carrier density n_c ranging from 0.5-1.5 * 10^13/cm^2, LaAlO3-SrTiO3 interfaces, forming drain-source channels in field-effect devices are non-ohmic. The differential resistance at zero channel bias diverges within a 2% variation of the carrier density. Above n_c, the conductivity of the ohmic channels has a metal-like temperature dependence, while below n_c conductivity sets in only above a threshold electric field. For a given thickness of the LaAlO3 layer, the conductivity follows a sigma_0 ~(n - n_c)/n_c characteristic. The metal-insulator transition is found to be distinct from that of the semiconductor 2D systems.Comment: 4 figure

InGaAs implant-free quantum-well MOSFETs: performance evaluation using 3D Monte Carlo simulation

In this paper we use numerical simulations to evaluate the performance of III-V Implant-Free Quantum-Well (IFQW) MOSFET devices that offer simultaneously high channel mobility, high drive current and excellent electrostatic integrity. Using 3D Monte Carlo simulations we show that to fully understand the performance of this device architecture, Fermi-Dirac statistics and quantum-corrections must be considered to account for the impact of low density-of-states and quantum confinement in the channel layer respectively

Representation of SO(3) Group by a Maximally Entangled State

A representation of the SO(3) group is mapped into a maximally entangled two qubit state according to literatures. To show the evolution of the entangled state, a model is set up on an maximally entangled electron pair, two electrons of which pass independently through a rotating magnetic field. It is found that the evolution path of the entangled state in the SO(3) sphere breaks an odd or even number of times, corresponding to the double connectedness of the SO(3) group. An odd number of breaks leads to an additional $\pi$ phase to the entangled state, but an even number of breaks does not. A scheme to trace the evolution of the entangled state is proposed by means of entangled photon pairs and Kerr medium, allowing observation of the additional $\pi$ phase.Comment: 4 pages, 3 figure

Transposon and deletion mutagenesis of genes involved in perchlorate reduction in Azospira suillum PS.

UnlabelledAlthough much work on the biochemistry of the key enzymes of bacterial perchlorate reduction, chlorite dismutase, and perchlorate reductase has been published, understanding of the molecular mechanisms of this metabolism has been somewhat hampered by the lack of a clear model system amenable to genetic manipulation. Using transposon mutagenesis and clean deletions, genes important for perchlorate reduction in Azospira suillum PS have been identified both inside and outside the previously described perchlorate reduction genomic island (PRI). Transposon mutagenesis identified 18 insertions in 11 genes that completely abrogate growth via reduction of perchlorate but have no phenotype during denitrification. Of the mutants deficient in perchlorate reduction, 14 had insertions that were mapped to eight different genes within the PRI, highlighting its importance in this metabolism. To further explore the role of these genes, we also developed systems for constructing unmarked deletions and for complementing these deletions. Using these tools, every core gene in the PRI was systematically deleted; 8 of the 17 genes conserved in the PRI are essential for perchlorate respiration, including 3 genes that comprise a unique histidine kinase system. Interestingly, the other 9 genes in the PRI are not essential for perchlorate reduction and may thus have unknown functions during this metabolism. We present a model detailing our current understanding of perchlorate reduction that incorporates new concepts about this metabolism.ImportanceAlthough perchlorate is generated naturally in the environment, groundwater contamination is largely a result of industrial activity. Bacteria capable of respiring perchlorate and remediating contaminated water have been isolated, but relatively little is known about the biochemistry and genetics of this process. Here we used two complementary approaches to identify genes involved in perchlorate reduction. Most of these genes are located on a genomic island, which is potentially capable of moving between organisms. Some of the genes identified are known to be directly involved in the metabolism of perchlorate, but other new genes likely regulate the metabolism in response to environmental signals. This work has uncovered new questions about the regulation, energetics, and evolution of perchlorate reduction but also presents the tools to address them

Tree Unitarity and Partial Wave Expansion in Noncommutative Quantum Field Theory

The validity of the tree-unitarity criterion for scattering amplitudes on the noncommutative space-time is considered, as a condition that can be used to shed light on the problem of unitarity violation in noncommutative quantum field theories when time is noncommutative. The unitarity constraints on the partial wave amplitudes in the noncommutative space-time are also derived.Comment: 15 pages, 1 figur

Avalanche-Induced Current Enhancement in Semiconducting Carbon Nanotubes

Semiconducting carbon nanotubes under high electric field stress (~10 V/um) display a striking, exponential current increase due to avalanche generation of free electrons and holes. Unlike in other materials, the avalanche process in such 1D quantum wires involves access to the third sub-band, is insensitive to temperature, but strongly dependent on diameter ~exp(-1/d^2). Comparison with a theoretical model yields a novel approach to obtain the inelastic optical phonon emission length, L_OP,ems ~ 15d nm. The combined results underscore the importance of multi-band transport in 1D molecular wires

Flow Equations for U_k and Z_k

By considering the gradient expansion for the wilsonian effective action S_k of a single component scalar field theory truncated to the first two terms, the potential U_k and the kinetic term Z_k, I show that the recent claim that different expansion of the fluctuation determinant give rise to different renormalization group equations for Z_k is incorrect. The correct procedure to derive this equation is presented and the set of coupled differential equations for U_k and Z_k is definitely established.Comment: 5 page

On the Connection Between Momentum Cutoff and Operator Cutoff Regularizations

Operator cutoff regularization based on the original Schwinger's proper-time formalism is examined. By constructing a regulating smearing function for the proper-time integration, we show how this regularization scheme simulates the usual momentum cutoff prescription yet preserves gauge symmetry even in the presence of the cutoff scales. Similarity between the operator cutoff regularization and the method of higher (covariant) derivatives is also observed. The invariant nature of the operator cutoff regularization makes it a promising tool for exploring the renormalization group flow of gauge theories in the spirit of Wilson-Kadanoff blocking transformation.Comment: 28 pages in plain TeX, no figures. revised and expande

Renormalization Group and Universality

It is argued that universality is severely limited for models with multiple fixed points. As a demonstration the renormalization group equations are presented for the potential and the wave function renormalization constants in the $O(N)$ scalar field theory. Our equations are superior compared with the usual approach which retains only the contributions that are non-vanishing in the ultraviolet regime. We find an indication for the existence of relevant operators at the infrared fixed point, contrary to common expectations. This result makes the sufficiency of using only renormalizable coupling constants in parametrizing the long distance phenomena questionable.Comment: 32pp in plain tex; revised version to appear in PR