High quality GaMnAs films grown with As dimers

We demonstrate that GaMnAs films grown with As2 have excellent structural, electrical and magnetic properties, comparable or better than similar films grown with As4. Using As2, a Curie temperature of 112K has been achieved, which is slightly higher than the best reported to date. More significantly, films showing metallic conduction have been obtained over a much wider range of Mn concentrations (from 1.5% to 8%) than has been reported for films grown with As4. The improved properties of the films grown with As2 are related to the lower concentration of antisite defects at the low growth temperatures employed.Comment: 8 pages, accepted for publication in J. Crystal Growt

BESII Detector Simulation

A Monte Carlo program based on Geant3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM

Development of ultra-low noise HEMTs for cryoelectronics at <= 4.2 k

We report on DC and noise characteristics at 4.2 K of High Electron Mobility Transistors (HEMTs) which have been realized at LPN/CNRS. This work is aimed to develop high performance, low-power, low-frequency noise and low-temperature field-effect transistors for the future cryoelectronics. A high quality two-dimensional electron gas (2DEG) based on AlGaAs/GaAs heterostructure has been used to realize appropriately designed HEMTs with different gate configurations. With these transistors, we have obtained, for example, a transconductance of about 100 mS and a voltage gain of 26 with a power dissipation of less than 100 mu W at 4.2 K; and a corresponded equivalent input voltage noise of 1.2 nV/Hz(1/2) at 1 kHz and as low as 0.12 nV/Hz(1/2)s at 100 kHz

Scaling behavior of nucleotide cluster in DNA sequences

In this paper we study the scaling behavior of nucleotide cluster in 11 chromosomes of Encephalitozoon cuniculi Genome. The statistical distribution of nucleotide clusters for 11 chromosomes is characterized by the scaling behavior of P(S)∝e(−αS), where S represents nucleotide cluster size. The cluster-size distribution P(S (1)+S (2)) with the total size of sequential C-G cluster and A-T cluster S (1)+S (2) were also studied. P(S (1)+S (2)) follows exponential decay. There does not exist the case of large C-G cluster following large A-T cluster or large A-T cluster following large C-G cluster. We also discuss the relatively random walk length function L(n) and the local compositional complexity of nucleotide sequences based on a new model. These investigations may provide some insight into nucleotide cluster of DNA sequence

The effects of acupuncture on rates of clinical pregnancy among women undergoing in vitro fertilization: a systematic review and meta-analysis

Background: Recent systematic reviews of adjuvant acupuncture for IVF have pooled heterogeneous trials, without examining variables that might explain the heterogeneity. The aims of our meta-analysis were to quantify the overall pooled effects of adjuvant acupuncture on IVF clinical pregnancy success rates, and evaluate whether study design-, treatment- and population-related factors influence effect estimates. Methods:We included randomized controlled trials that compared needle acupuncture administered within 1 day of embryo transfer, versus sham acupuncture or no adjuvant treatment. Our primary outcome was clinical pregnancy rates.We obtained from all investigators additional methodological details and outcome data not included in their original publications.We analysed sham-controlled and no adjuvant treatmentcontrolled trials separately, but since there were no large or significant differences between these two subsets, we pooled all trials for subgroup analyses.We prespecified 11 subgroup variables (5 clinical and 6 methodological) to investigate sources of heterogeneity, using single covariate meta-regressions. Results: Sixteen trials (4021 participants) were included in the meta-analyses. There was no statistically significant difference between acupuncture and controls when combining all trials [risk ratio (RR) 1.12, 95% confidence interval (CI), 0.96-1.31;