3,704 research outputs found
Molecular beam epitaxial growth of high-quality InSb on InP and GaAs substrates
Epitaxial layers of InSb were grown on InP and GaAs substrates by molecular beam epitaxy. The dependence of the epilayer quality on flux ratio, J sub Sb4/J sub In, was studied. Deviation from an optimum value of J sub Sb4/J sub In (approx. 2) during growth led to deterioration in the surface morphology and the electrical and crystalline qualities of the films. Room temperature electron mobilities as high as 70,000 and 53,000 sq cm /V-s were measured in InSb layers grown on InP and GaAs substrates, respectively. Unlike the previous results, the conductivity in these films is n-type even at T = 13 K, and no degradation of the electron mobility due to the high density of dislocations was observed. The measured electron mobilities (and carrier concentrations) at 77 K in InSb layers grown on InP and GaAs substrates are 110,000 sq cm/V-s (3 x 10(15) cm(-3)) and 55,000 sq cm/V-s (4.95 x 10(15) cm(-3)), respectively, suggesting their application to electronic devices at cryogenic temperatures
Spin and spin-spin correlations in chargino pair production at future linear e+e- colliders
A possibility to measure the spin and spin-spin correlations of a chargino
pair is investigated in the process electron positron -> chargino_1
anti-chargino_1 -> (neutralino_1 quark anti-quark) (neutralino_1 quark
anti-quark) at future linear-collider energies. The total and the differential
cross sections are calculated by the GRACE system which allows for the full
spin correlation. Experimental sensitivity of the measurements are examined by
assuming the limited detector resolution, the initial state radiation and the
beam-beam effect (beamstrahlung). It is found that generally the spin-spin
correlation can only be measured with a lower sensitivity than the chargino
spin itself. The dependence of the correlation measurements on the relevant
SUSY parameters can be seen for a light sneutrino case, but the situation
becomes worse for a heavier sneutrino.Comment: 23 pages, 7 figures, 6 tables; added reference for section
Comparison of Lidocaine-Xylazine and Procaine-Xylazine for Lumbar Epidural Anesthesia in Cattle
NO ABSTRACT AVAILABLELumbar epidural anesthesia is commonly utilized in veterinary medicine for diagnostic, obstetrical, and surgical intervention in the abdominal and perineal regions of large animals. The aim of this study was to directly compare the time to onset and duration of epidural anesthesia produced by lidocaine-xylazine and procaine-xylazine combinations to that produced by xylazine alone in cattle. A total of 24 healthy adult Holstein dairy cows were included in this study. The time to onset and duration of anesthesia were recorded. The heart rate, respiratory rate, and rectal temperature were recorded at 0 minute and at 10, 20, 30, 60, and 90 minutes after the epidural administration of each treatment. The time to onset of anesthesia did not significantly differ between the xylazine only group and the lidocaine-xylazine and procaine-xylazine combination groups. The duration of anesthesia in the xylazine only group was significantly shorter than that in the lidocaine-xylazine and procaine-xylazine combination groups (p < 0.05). Ataxia was not observed in any group. The heart rate, respiratory rate, and rectal temperature values in all the treatment groups throughout the study did not significantly differ from those at baseline. We found that administration of procaine hydrochloride in combination with xylazine hydrochloride, an α2-adrenergic receptor agonist, offers the same time to onset and duration of anesthesia as does epidural anesthesia using a combination of lidocaine hydrochloride and xylazine hydrochloride. Furthermore, this combination of treatments did not cause adverse effects in the cardiovascular and respiratory systems. These findings indicate that combined administration of procaine and xylazine is an economic and useful approach for epidural anesthesia
Temperature-Dependent Site Control of InAs/GaAs (001) Quantum Dots Using a Scanning Tunneling Microscopy Tip During Growth
Site-controlled InAs nano dots were successfully fabricated by a STMBE system (in situ scanning tunneling microscopy during molecular beam epitaxy growth) at substrate temperatures from 50 to 430°C. After 1.5 ML of the InAs wetting layer (WL) growth by ordinal Stranski–Krastanov dot fabrication procedures, we applied voltage at particular sites on the InAs WL, creating the site where In atoms, which were migrating on the WL, favored to congregate. At 240°C, InAs nano dots (width: 20–40 nm, height: 1.5–2.0 nm) were fabricated. At 430°C, InAs nano dots (width: 16–20 nm, height: 0.75–1.5 nm) were also fabricated. However, these dots were remained at least 40 s and collapsed less than 1000 s. Then, we fabricated InAs nano dots (width: 24–150 nm, height: 2.8–28 nm) at 300°C under In and As4 irradiations. These were not collapsed and considered to high crystalline dots
The \u3cem\u3edapE\u3c/em\u3e-encoded \u3cem\u3eN\u3c/em\u3e-Succinyl-l,l-Diaminopimelic Acid Desuccinylase from \u3cem\u3eHaemophilus influenzae\u3c/em\u3e Is a Dinuclear Metallohydrolase
The Zn K-edge extended X-ray absorption fine structure (EXAFS) spectra, of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) from Haemophilus influenzae have been recorded in the presence of one or two equivalents of Zn(II) (i.e. [Zn_(DapE)] and [ZnZn(DapE)]). The Fourier transforms of the Zn EXAFS are dominated by a peak at ca. 2.0 Å, which can be fit for both [Zn_(DapE)] and [ZnZn(DapE)], assuming ca. 5 (N,O) scatterers at 1.96 and 1.98 Å, respectively. A second-shell feature at ca. 3.34 Å appears in the [ZnZn(DapE)] EXAFS spectrum but is significantly diminished in [Zn_(DapE)]. These data show that DapE contains a dinuclear Zn(II) active site. Since no X-ray crystallographic data are available for any DapE enzyme, these data provide the first glimpse at the active site of DapE enzymes. In addition, the EXAFS data for DapE incubated with two competitive inhibitors, 2-carboxyethylphosphonic acid and 5-mercaptopentanoic acid, are also presented
Fighting Antibiotic Resistance: The \u3cem\u3edapE\u3c/em\u3e-encoded N-succinyl-L, L-Diaminopimelic Acid Desuccinylase from \u3cem\u3eHaemophilus influenzae\u3c/em\u3e in a Dinuclear Metallohydrolase
Evidence of Luttinger liquid behavior in one-dimensional dipolar quantum gases
The ground state and structure of a one-dimensional Bose gas with dipolar
repulsions is investigated at zero temperature by a combined Reptation Quantum
Monte Carlo (RQMC) and bosonization approach. A non trivial Luttinger-liquid
behavior emerges in a wide range of intermediate densities, evolving into a
Tonks-Girardeau gas at low density and into a classical quasi-ordered state at
high density. The density dependence of the Luttinger exponent is extracted
from the numerical data, providing analytical predictions for observable
quantities, such as the structure factor and the momentum distribution. We
discuss the accessibility of such predictions in current experiments with
ultracold atomic and molecular gases.Comment: 4 pages, 3 EPS figures, Revtex
Neural Stochastic Contraction Metrics for Learning-based Control and Estimation
We present Neural Stochastic Contraction Metrics (NSCM), a new design framework for provably-stable learning-based control and estimation for a class of stochastic nonlinear systems. It uses a spectrally-normalized deep neural network to construct a contraction metric and its differential Lyapunov function, sampled via simplified convex optimization in the stochastic setting. Spectral normalization constrains the state-derivatives of the metric to be Lipschitz continuous, thereby ensuring exponential boundedness of the mean squared distance of system trajectories under stochastic disturbances. The trained NSCM model allows autonomous systems to approximate optimal stable control and estimation policies in real-time, and outperforms existing nonlinear control and estimation techniques including the state-dependent Riccati equation, iterative LQR, EKF, and the deterministic NCM, as shown in simulation results
Rescue with an anti-inflammatory peptide of chickens infected H5N1 avian flu
Chickens suffering from avian flu caused by H5N1 influenza virus are destined to die within 2 days due to a systemic inflammatory response. Since HVJ infection (1,2) and influenza virus infection (3,4) cause infected cells to activate homologous serum complement, the systemic inflammatory response elicited could be attributed to the unlimited generation of C5a anaphylatoxin of the complement system, which is a causative peptide of serious inflammation. In monkeys inoculated with a lethal dose of LPS (4 mg/kg body weight), inhibition of C5a by an inhibitory peptide termed AcPepA (5) rescued these animals from serious septic shock which would have resulted in death within a day (6). Therefore, we tested whether AcPepA could also have a beneficial effect on chickens with bird flu. On another front, enhanced production of endothelin-1 (ET-1) and the activation of mast cells (MCs) have been implicated in granulocyte sequestration (7). An endothelin receptor derived antisense homology box peptide (8) designated ETR-P1/fl was shown to antagonize endothelin A receptor (ET-A receptor) (9) and reduce such inflammatory responses as endotoxin-shock (10) and hemorrhagic shock (11), thereby suppressing histamine release in the circulation (12). Thus, we also administered ETR-P1/fl to bird flu chickens expecting suppression of a systemic inflammatory response
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