n-Type GaAs/AlGaAs heterostructure detector with a 3.2 THz threshold frequency

Terahertz detection using the free-carrier absorption requires a small internal work function of the order of a few millielectron volts. A threshold frequency of 3.2 THz (93 microm or approximately 13 meV work function) is demonstrated by using a 1 x 10(18) cm(-3) Si-doped GaAs emitter and an undoped Al(0.04)Ga(0.96)As barrier structure. The peak responsivity of 6.5 A/W, detectivity of 5.5 x 10(8) Jones, and quantum efficiency of 19% were obtained at 7.1 THz under a bias field of 0.7 kV/cm at 6 K, while the detector spectral response range spans from 3.2 to 30 THz.     

Fourier transform spectral interferometric coherent anti-Stokes Raman scattering (FTSI-CARS) spectroscopy

A novel Fourier transform spectral interferometric (FTSI) multiplex coherent anti-Stokes Raman scattering (CARS) technique is developed to extract the vibrational spectrum equivalent to the spontaneous Raman scattering. The conventional FTSI method is modified to use the internal nonresonant CARS signal as a local oscillator to perform spectral interferometry. Utilizing the causality of the coherent vibration (i.e., there should be no signal before the laser excitation), this new FTSI method recovers the entire complex vibrational spectral parameters. We demonstrate this technique with a previously reported single-pulse multiplex CARS method that uses a single phase-controlled broadband ultrafast laser pulse.     

New insight into the role of the β3 subunit of the GABA<Subscript>A</Subscript>-R in development,behavior, body weight regulation,and anesthesia revealed by conditional gene knockout

Background  

The β3 subunit of the γ-aminobutyric acid type A receptor (GABA_A-R) has been reported to be important for palate formation, anesthetic action, and normal nervous system function. This subunit has also been implicated in the pathogenesis of Angelman syndrome and autism spectrum disorder. To further investigate involvement of this subunit, we previously produced mice with a global knockout of β3. However, developmental abnormalities, compensation, reduced viability, and numerous behavioral abnormalities limited the usefulness of that murine model. To overcome many of these limitations, a mouse line with a conditionally inactivated β3 gene was engineered.     

The millimeter wave rotational spectrum of pyruvic acid

The rotational spectrum of pyruvic acid has been investigated for the first time in the millimeter-wave region, at 160-314 GHz, and also in supersonic expansion, at 10-17.4 GHz. The analysis of the broadband spectra recorded in this work was carried out with the newly developed AABS software package for Assignment and Analysis of Broadband Spectra, and precise spectroscopic constants are reported for the ground state, the first excited state of the low-frequency skeletal torsional mode ν₂₄, and the first excited state of the methyl torsional mode ν₂₃. Limited results have also been obtained for several higher excited states. The dataset for the ground state currently exceeds 1500 lines and for both the A and E internal rotor sublevels spans the complete range of values of K_a at the mid values of J for the measured transitions. The results were analysed with three freely available computer programs employing different strategies for dealing with internal rotation and a comparative discussion of their merits is made.     

Variations on the warped deformed conifold

The warped deformed conifold background of type IIB theory is dual to the cascading SU(M(p+1))×SU(Mp) gauge theory. We show that this background realizes the (super-)Goldstone mechanism where the U(1) baryon number symmetry is broken by expectation values of baryonic operators. The resulting massless pseudo-scalar and scalar glueballs are identified in the supergravity spectrum. A D-string is then dual to a global string in the gauge theory. Upon compactification, the Goldstone mechanism turns into the Higgs mechanism, and the global strings turn into ANO strings. To cite this article: S.S. Gubser et al., C. R. Physique 5 (2004).

Résumé

La configuration de fond pour la théorie de type IIB donnée par le conifold voilé déformé est duale à la cascade de théorie de jauge SU(M(p+1))×SU(Mp). Nous montrons que cette configuration donne une réalisation du mécanisme de (super-)Goldstone où la symètrie baryonique U(1) est brisée par la valeur moyenne dans le vide des opérateurs baryoniques. Les boules de glue pseudo-scalaires et scalaires de masse nulle résultantes sont identifiées dans le spectre de supegravité. Une D-corde est alors duale à une corde globale dans la théorie de jauge. Après compactification, le mécanisme de Goldstone devient un mécanisme de Higgs, et une corde globale devient une corde ANO. Pour citer cet article : S.S. Gubser et al., C. R. Physique 5 (2004).     

Multiple synaptic and membrane sites of anesthetic action in the CA1 region of rat hippocampal slices

Background  

Anesthesia is produced by a depression of central nervous system function, however, the sites and mechanisms of action underlying this depression remain poorly defined. The present study compared and contrasted effects produced by five general anesthetics on synaptic circuitry in the CA1 region of hippocampal slices.     

Transient Response of Particle Distribution in a Chamber to Transient Particle Injection

We inject a large number of newly created nano‐particle aggregates into a chamber for the purpose of removing harmful contents in an indoor environment. This study is to experimentally and numerically investigate transient response of particle distributions to particle injections. A room‐sized chamber of 4 m × 2.1 m × 2.4 m is connected to a specially designed particle‐injection system, with two Optical Particle Counters used to simultaneously measure particle‐number densities with the size range from 0.3 μm to 10 μm at the inlet and in the chamber. A velocity probe measures the flow that is up to 1 m/s. An Euler‐type particulate‐phase‐transport model is developed and validated by comparing with experimental data. The study shows that the transient behavior of particle distributions is determined by many factors, including particle size, particle settling speed, sampling location, and velocity distribution. Particle number densities decrease in time more quickly for large particles than for small particles, and locations farther downstream in the chamber correlate more weakly with the inlet injection.     

MRI findings in nonalcoholic steatohepatitis: correlation with histopathology and clinical staging

Purpose

To evaluate magnetic resonance imaging (MRI) findings of nonalcoholic steatohepatitis (NASH) and to determine the correlation of MRI findings with histopathology and Mayo End-Stage Liver Disease (MELD) score.

Materials and Methods

Thirty patients (18 males, 12 females; mean age: 57±8.9 years; age range: 35–71 years) with histopathologically proven NASH who underwent MRI examinations between January 2001 and October 2005 were included in the study. Two radiologists retrospectively reviewed all magnetic resonance (MR) examinations in consensus to evaluate the presence and extent of predetermined findings of NASH including liver steatosis, early patchy liver enhancement indicating inflammation and liver fibrosis. The findings detected on MRI were correlated and compared to histopathological findings and MELD score by using nonparametric Spearman correlation coefficient and Kruskal–Wallis analysis of variance.

Results

Liver steatosis was observed in 10 of 30 patients; early patchy liver enhancement, in 8 of 30 patients and liver fibrosis in 19 of 30 patients on MR images. Liver fibrosis was reticular in all these patients. There were statistically significant moderate correlations between MRI findings of liver steatosis and histopathologic grades of steatosis (r=0.43; P<.05), and between MRI findings of fibrosis and histopathologic stages of fibrosis (r=0.61; P<.001). Early patchy enhancement did not demonstrate statistically significant correlation with inflammation (P=.28). There was no statistically significant overall correlation between MRI findings of NASH and MELD score.

Conclusion

MRI findings of liver steatosis and fibrosis in NASH showed moderate correlations with histopathologic grades of steatosis and stages of fibrosis, but MRI findings of NASH did not demonstrate any significant correlations with MELD score.