Magnetoresistance of a 2-dimensional electron gas in a random magnetic field

We report magnetoresistance measurements on a two-dimensional electron gas (2DEG) made from a high mobility GaAs/AlGaAs heterostructure, where the externally applied magnetic field was expelled from regions of the semiconductor by means of superconducting lead grains randomly distributed on the surface of the sample. A theoretical explanation in excellent agreement with the experiment is given within the framework of the semiclassical Boltzmann equation.Comment: REVTEX 3.0, 11 pages, 3 Postscript figures appended. The manuscript can also be obtained from our World Wide Web server: http://roemer.fys.ku.dk/randmag.ht

On the Coexistence of Diagonal and off-Diagonal Long-Range Order, a Monte Carlo Study

The zero temperature properties of interacting 2 dimensional lattice bosons are investigated. We present Monte Carlo data for soft-core bosons that demonstrate the existence of a phase in which crystalline long-range order and off-diagonal long-range order (superfluidity) coexist. We comment on the difference between hard and soft-core bosons and compare our data to mean-field results that predict a larger coexistence region. Furthermore, we determine the critical exponents for the various phase transitions.Comment: 7 pages and 8 figures appended in postscript, KA-TFP-93-0

Adaptation of photosystem II to high and low light in wild-type and triazine-resistant Canola plants: analysis by a fluorescence induction algorithm

Plants of wild-type and triazine-resistant Canola (Brassica napus L.) were exposed to very high light intensities and after 1 day placed on a laboratory table at low light to recover, to study the kinetics of variable fluorescence after light, and after dark-adaptation. This cycle was repeated several times. The fast OJIP fluorescence rise curve was measured immediately after light exposure and after recovery during 1 day in laboratory room light. A fluorescence induction algorithm has been used for resolution and analysis of these curves. This algorithm includes photochemical and photo-electrochemical quenching release components and a photo-electrical dependent IP-component. The analysis revealed a substantial suppression of the photo-electrochemical component (even complete in the resistant biotype), a partial suppression of the photochemical component and a decrease in the fluorescence parameter Fo after high light. These effects were recovered after 1 day in the indoor light

Impact of Duodenal-Jejunal Exclusion on Satiety Hormones

OBJECTIVE: Bariatric procedures that exclude the proximal small intestine lead to significant weight loss which is probably mediated by changes in hormones that alter appetite, such as peptide YY (PYY), ghrelin, cholecystokinin (CCK), and leptin. Here, the effect of the non-surgical duodenal-jejunal bypass liner (DJBL) on concentrations of hormones implicated in appetite control was investigated. SUBJECTS: A two-center prospective study was conducted between January and December 2010. Seventeen obese subjects with type 2 diabetes were treated with the DJBL for 24 weeks. Fasting concentrations of leptin and meal responses of plasma PYY, CCK, and ghrelin were determined prior to and after implantation of the DJBL. RESULTS: At baseline, subjects had an average body weight of 116.0 +/- 5.8 kg. One week after implantation, subjects had lost 4.3 +/- 0.6 kg (p < 0.01), which progressed to 12.7 +/- 1.3 kg at week 24 (p < 0.01). Postprandial concentrations of PYY and ghrelin increased (baseline vs. week 1 vs. week 24 PYY: 2.6 +/- 0.2 vs. 4.1 +/- 0.4 vs. 4.1 +/- 0.7 nmol/L/min and ghrelin: 7.8 +/- 1.8 vs. 11.0 +/- 1.8 vs. 10.6 +/- 1.8 ng/mL/min, all p < 0.05). In parallel, the CCK response decreased (baseline vs. week 1 vs. week 24: 434 +/- 51 vs. 229 +/- 52 vs. 256 +/- 51pmol/L/min, p < 0.01). Fasting leptin concentrations also decreased (baseline vs. week 24: 98 +/- 17 vs. 53 +/- 10 ng/mL, p < 0.01). CONCLUSIONS: DJBL treatment induces weight loss paralleled by changes in concentrations of hormones involved in appetite control

Trans-eQTLs Reveal That Independent Genetic Variants Associated with a Complex Phenotype Converge on Intermediate Genes, with a Major Role for the HLA

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

The Research on Sino-US Green Building Rating System

AbstractThis paper describes the more commonly used domestic and international green building rating systems and details of the evaluation of U.S. LEED, its old and new versions, the trend of improvement in LEED; Compared Chinese “Evaluation Standard for Green Building” (GB/T 50378-2006)with the LEED2009, the paper points out their shortcomings, and identify the existing differences between them. Then comes out the conclusion that LEED2009 is still target to the U.S. buildings, Chinese engineers should learn from its advantage, make use in our evaluation of green building, which is suitable for China's actual conditions. But we make full use of Chinese buildings of the LEED rating system is not appropriate. Finally, we make a suggestion for “Evaluation Standard for Green Building” that we should add incentives for new energy sources can effectively develop our new energy, give a positive role in environment protection

The superconductor-insulator transition in 2D dirty boson systems

Universal properties of the zero temperature superconductor-insulator transition in two-dimensional amorphous films are studied by extensive Monte Carlo simulations of bosons in a disordered medium. We report results for both short-range and long-range Coulomb interactions for several different points in parameter space. In all cases we observe a transition from a superconducting phase to an insulating Bose glass phase. {}From finite-size scaling of our Monte Carlo data we determine the universal conductivity $\sigma^*$ and the critical exponents at the transition. The result $\sigma^* = (0.55 \pm 0.06) (2e)^2/h$ for bosons with long-range Coulomb interaction is roughly consistent with experiments reported so far. We also find $\sigma^* = (0.14 \pm 0.03) (2e)^2/h$ for bosons with short-range interactions.Comment: Revtex 3.0, 54 pages, 17 figures included, UBCTP-93-01

Integer Quantum Hall Effect in Double-Layer Systems

We consider the localization of independent electron orbitals in double-layer two-dimensional electron systems in the strong magnetic field limit. Our study is based on numerical Thouless number calculations for realistic microscopic models and on transfer matrix calculations for phenomenological network models. The microscopic calculations indicate a crossover regime for weak interlayer tunneling in which the correlation length exponent appears to increase. Comparison of network model calculations with microscopic calculations casts doubt on their generic applicability.Comment: 14 pages, 12 figures included, RevTeX 3.0 and epsf. Additional reference