bluuebunny/crossref_metadata_2025 huggingface dataset:
Moclobemide upregulated Bcl‐2 expression and induced neural stem cell differentiation into serotoninergic neuron via extracellular‐regulated kinase pathway
Authors: Chiou Shih‐Hwa , Ku Hung‐Hai , Tsai Tung‐Hu , Lin Heng‐Liang , Chen Li‐Hsin , Chien Chan‐Shiu , Ho Larry L ‐T , Lee Chen‐Hsen , Chang Yuh‐Lih
Published: May 2006

Moclobemide (MB) is an antidepressant drug that selectively and reversibly inhibits monoamine oxidase‐A. Recent studies have revealed that antidepressant drugs possess the characters of potent growth‐promoting factors for the development of neurogenesis and improve the survival rate of serotonin (5‐hydroxytrytamine; 5‐HT) neurons. However, whether MB comprises neuroprotection effects or modulates the proliferation of neural stem cells (NSCs) needs to be elucidated.

In this study, firstly, we used the MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay to demonstrate that 50 μM MB can increase the cell viability of NSCs. The result of real‐time reverse transcription–polymerase chain reaction (RT–PCR) showed that the induction of MB can upregulate the gene expressions of Bcl‐2 and Bcl‐xL. By using caspases 8 and 3, ELISA and terminal dUTP nick‐end labeling (TUNEL) assay, our data further confirmed that 50 μM MB‐treated NSCs can prevent FasL‐induced apoptosis.

The morphological findings also supported the evidence that MB can facilitate the dendritic development and increase the neurite expansion of NSCs. Moreover, we found that MB treatment increased the expression of Bcl‐2 in NSCs through activating the extracellular‐regulated kinase (ERK) phosphorylation.

By using the triple‐staining immunofluorescent study, the percentages of serotonin‐ and MAP‐2‐positive cells in the day 7 culture of MB‐treated NSCs were significantly increased (P<0.01). Furthermore, our data supported that MB treatment increased functional production of serotonin in NSCs via the modulation of ERK1/2. In sum, the study results support that MB can upregulate Bcl‐2 expression and induce the differentiation of NSCs into serotoninergic neuron via ERK pathway.

British Journal of Pharmacology (2006) 148, 587–598. doi:10.1038/sj.bjp.0706766
Differentiation of hippocampal stem cells into functional neurons: evolving our understanding of monoamine oxidase‐A inhibition
Authors: Egan Colin G
Published: May 2006

Depression affects many millions of people worldwide and much is still unknown with respect to the mode of action of antidepressant drugs. The hippocampus has been associated with many psychiatric disorders, including clinical depression. Recently, stem cells have also been shown to reside within discrete regions of the hippocampus and can differentiate under a variety of conditions into neural cells. In this issue, Chiou et al. have elegantly demonstrated that cells isolated from the rat hippocampus, and treated with the antidepressant moclobemide, may be differentiated in vitro into neural cells exhibiting features to those of serotoninergic neurons. They have also suggested that this process was mediated, in part, through the expression of specific antiapoptotic genes (Bcl‐2 and Bcl‐XL) and via activation of extracellular‐regulated kinase. This work raises the attractive possibility that the use of antidepressants, such as moclobemide, may exert neuroprotective and potentially neurogenerative effects not just in vitro, but also in vivo, through the selected differentiation of stem cells into functional neurons. The exact mechanisms by which such antidepressants differentiate neural stem cells still remains to be fully elucidated.

British Journal of Pharmacology (2006) 148, 563–564. doi:10.1038/sj.bjp.0706768
Cardioprotective effects of atrasentan, an endothelin‐A receptor antagonist, but not of nitric oxide in diabetic mice with myocyte‐specific overexpression of endothelial nitric oxide synthase
Authors: Wölkart Gerald , Stessel Heike , Saad Zora , Kirchengast Michael , Brunner Friedrich
Published: May 2006

We investigated the roles of nitric oxide (NO) and endothelin‐1 (ET‐1) in organ dysfunction in diabetic mice with normal genotype (wild‐type, WT) or myocyte‐specific overexpression of endothelial NO synthase (eNOS) (transgenic, TG) after chronic oral treatment with the endothelin‐A (ETA) receptor antagonist atrasentan.

Mice were rendered diabetic by injection of 200 mg kg−1streptozotocin (STZ). Experimental groups were: untreated WT diabetic (n=9), untreated TG diabetic (n=9), atrasentan‐treated WT diabetic (n=9), atrasentan‐treated TG diabetic (n=8) and the four corresponding nondiabetic groups (n=5). Atrasentan was administered orallyviadrinking water at 3 mg kg−1per day over 28 days. All diabetic mice developed similar hyperglycaemia (27–30 mmol l−1).

Atrasentan treatment significantly improved left ventricular systolic and diastolic function in response to exogenous norepinephrine, but there were no differences between genotypes.

Atrasentan antagonized the diabetic impairments in endothelium‐dependent coronary relaxation and thromboxane‐receptor mediated aortic constriction. Further, it improved cardiac and renal oxidant status as evident from reduced tissue malondialdehyde levels.

Atrasentan reduced diabetic urine flow, proteinuria and plasma creatinine levels, but creatinine clearance was not significantly altered.

These results suggest that in experimental type 1 diabetes, blocking ETAreceptors ameliorates myocardial, coronary and renal function and improves tissue oxidant status, whereas raising myocardial NO levels has neither beneficial nor deleterious effects on diabetic cardiomyopathy in this transgenic model.

British Journal of Pharmacology(2006)148, 671–681. doi:10.1038/sj.bjp.0706772
Effect of magnetic field profile on the anode fall in a Hall-effect thruster discharge
Authors: Dorf L. , Raitses Y. , Fisch N. J.
Published: May 2006

The effect of the magnetic field configuration on the anode fall in an E⃗×B⃗ discharge of a Hall thruster is studied both experimentally and theoretically. Plasma potential, electron temperature, and plasma density in the near-anode region are measured with a biased probe in three configurations of the magnetic field. It is observed that the anode fall in a Hall thruster can be changed from negative to positive by creating a magnetic field configuration with a zero magnetic field region. Similar configurations are utilized in some advanced Hall thrusters, like an ATON thruster. Results of the measurements are employed to model a Hall thruster with different magnetic field configurations, including the one with a zero-field region. Different anode sheath regimes observed experimentally are used to set the boundary conditions for the quasineutral plasma. Numerical solutions obtained with a hydrodynamic quasi-one-dimensional model suggest that varying the magnetic field configuration affects the electron mobility both inside and outside the channel, as well as the plasma density distribution along the axis.
Rayleigh-Taylor growth measurements of three-dimensional modulations in a nonlinear regime
Authors: Smalyuk V. A. , Sadot O. , Betti R. , Goncharov V. N. , Delettrez J. A. , Meyerhofer D. D. , Regan S. P. , Sangster T. C. , Shvarts D.
Published: May 2006

An understanding of the nonlinear evolution of Rayleigh-Taylor (RT) instability is essential in inertial confinement fusion and astrophysics. The nonlinear RT growth of three–dimensional (3-D) broadband nonuniformities was measured near saturation levels using x-ray radiography in planar foils accelerated by laser light. The initial 3-D target modulations were seeded by laser nonuniformities and subsequently amplified by the RT instability. The measured modulation Fourier spectra and nonlinear growth velocities are in excellent agreement with those predicted by Haan's model [S. Haan, Phys. Rev. A 39, 5812 (1989)]. These spectra and growth velocities are insensitive to initial conditions. In a real-space analysis, the bubble merger was quantified by a self-similar evolution of bubble size distributions, in agreement with the Alon–Oron–Shvarts theoretical predictions [D. Oron et al. Phys. Plasmas 8, 2883 (2001)].
Measurement and modeling of the implosion of wire arrays with seeded instabilities
Authors: Jones Brent , Garasi Christopher J. , Ampleford David J. , Deeney Christopher , Mehlhorn Thomas A. , Bland Simon N. , Lebedev Sergey V. , Chittenden Jeremy P. , Bott Simon C. , Palmer James B. A. , Hall Gareth N. , Rapley Jack
Published: May 2006

In order to study wire array Z-pinch instabilities, perturbations have been seeded by etching 15μm diameter aluminum wires to introduce 20% modulations in radius with a controlled axial wavelength. These perturbations seed additional imploding structures that are studied experimentally on the 1MA, 250ns MAGPIE generator [S. V. Lebedev et al., Plasma Phys. Control. Fusion 47, A91 (2005)] and with three-dimensional magnetohydrodynamic calculations using the ALEGRA-HEDP [A. C. Robinson and C. J. Garasi, Comput. Phys. Commun. 164, 408 (2004)] and GORGON [J. P. Chittenden et al., Plasma Phys. Control. Fusion 46, B457 (2004)] codes. Simulations indicate that current path nonuniformity at discontinuities in the wire radius result in perturbation-induced magnetic bubble formation. Imploding bubbles originating from discontinuities are observed experimentally, and their collision on axis determines the start of the main x-ray pulse rise. These mechanisms likely govern dynamics of standard wire array Z pinches, and tailoring the profile of imploding mass may allow x-ray pulse shaping for inertial confinement fusion applications.
Thirty-minute plasma sustainment by real-time magnetic-axis swing for effective divertor-load-dispersion in the Large Helical Device
Authors: Mutoh T. , Masuzaki S. , Kumazawa R. , Seki T. , Saito K. , Nakamura Y. , Kubo S. , Takeiri Y. , Shimozuma T. , Yoshimura Y. , Igami H. , Ohkubo K. , Watanabe T. , Ogawa H. , Miyazawa J. , Shoji M. , Ashikawa N. , Nishimura K. , Sakamoto M. , Osakabe M. , Tsumori K. , Ikeda K. , Chikaraishi H. , Funaba H. , Morita S. , Goto M. , Tokuzawa T. , Takeuchi N. , Shimpo F. , Nomura G. , Takahashi C. , Yokota M. , Zhao Y. P. , Kwak J. G. , Yamada H. , Kawahata K. , Ohyabu N. , Kaneko O. , Ida K. , Nagayama Y. , Noda N. , Komori A. , Sudo S. , Motojima O. , Group LHD Experiment
Published: May 2006

Achieving steady-state plasma operation at high plasma temperatures is one of the important goals of worldwide magnetic fusion research. A high temperature of approximately 2keV, and steady-state plasma-sustainment operation of the Large Helical Device (LHD) [O. Motojima, K. Akaishi, H. Chikaraishi et al., Nucl. Fusion 40, 599 (2000)] is reported. High-temperature plasmas were created and maintained for more than 30min with a world record injected heating power of 1.3GJ. The three-dimensional heat-deposition profile of the LHD helical divertor was modified and during long-pulse discharges it effectively dispersed the heat load using a magnetic-axis swing technique developed at the LHD. A sweep of only 3cm of the major radius of the magnetic axis position (less than 1% of the major radius of the LHD) was enough to disperse the divertor heat load. The modification of the heat-load profile was explained well by field-line tracing. The steady-state plasma was heated and sustained mainly by hydrogen minority ion heating using ion cyclotron range of frequencies. The operation lasted until a sudden increase of radiation loss occurred, presumably because of wall metal flakes dropping into the plasma. The sustained line-averaged electron density was approximately 0.7–0.8×1019m−3. The average input power was 680kW, and the plasma duration was 31min 45s. This successful long operation shows that the heliotron configuration has a high potential as a steady-state fusion reactor.
Compression of laser radiation in plasmas via electromagnetic cascading
Authors: Kalmykov Serguei , Shvets Gennady
Published: May 2006

A train of few-laser-cycle relativistically intense radiation spikes with a terahertz repetition rate can be organized self-consistently in plasma from two frequency detuned co-propagating laser beams of low intensity. Large frequency bandwidth for the compression of spikes is produced via laser-induced periodic modulation of the plasma refractive index. The beat-wave-driven electron plasma wave downshifted from the plasma frequency creates a moving index grating thus inducing a periodic phase modulation of the driving laser (in spectral terms, electromagnetic cascading). The group velocity dispersion compresses the chirped laser beat notes to a few-cycle duration and relativistic intensity either concurrently in the same, or sequentially in different plasmas. Particle-in-cell simulations indicate that the effect persists in a realistic three-dimensional axisymmetric geometry.
Different kλD regimes for nonlinear effects on Langmuir waves
Authors: Kline J. L. , Montgomery D. S. , Yin L. , DuBois D. F. , Albright B. J. , Bezzerides B. , Cobble J. A. , Dodd E. S. , DuBois D. F. , Fernández J. C. , Johnson R. P. , Kindel J. M. , Rose H. A. , Vu H. X. , Daughton W.
Published: May 2006

As Langmuir waves (LWs) are driven to large amplitude in plasma, they are affected by nonlinear mechanisms. A global understanding, based on simulations and experiments, has emerged that identifies various nonlinear regimes depending on the dimensionless parameter kλD, where k is the Langmuir wave number and λD is the electron Debye length. The nonlinear phenomena arise due to wave-wave and wave-particle coupling mechanisms, and this basic separation between fluid-like nonlinearities and kinetic nonlinearities depends on the degree to which electron and ion Landau damping, as well as electron trapping, play a role. Previous ionospheric heating experiments [Cheung et al. Phys. Plasmas 8, 802 (2001)] identified cavitation/collapse and Langmuir decay instability (LDI), predominantly wave-wave mechanisms, to be the principal nonlinear effects for driven LWs with kλD<0.1, in agreement with fluid simulations [DuBois et al. Phys. Plasmas 8, 791 (2001)]. In the present research, collective Thomson scattering measurements of LWs driven by stimulated Raman scattering in laser-plasma experiments are used to study both wave-wave and wave-particle nonlinearities [Kline et al. Phys. Rev. Lett. 94, 175003 (2005)]. For kλD<0.29, multiple LWs are detected and are attributed to LDI, a wave-wave nonlinear regime. For kλD>0.29, a single-wave, frequency-broadened spectrum is observed associated with electron trapping, a wave-particle nonlinear regime. The transition from wave-wave to wave-particle nonlinear behavior is qualitatively consistent with particle-in-cell simulations and with the crossing of the LDI threshold above that for LW self-focusing. The fact that LDI is observed in both ionospheric and laser-plasma experiments for similar values of kλD, though vastly differing in plasma conditions and scales, and that simulations predict the various observed nonlinear regimes over a large range of kλD, supports our global view of LW nonlinear behavior.
First hohlraum drive studies on the National Ignition Facility
Authors: Dewald E. L. , Landen O. L. , Suter L. J. , Schein J. , Holder J. , Campbell K. , Glenzer S. H. , McDonald J. W. , Niemann C. , Mackinnon A. J. , Schneider M. S. , Haynam C. , Hinkel D. , Hammel B. A.
Published: May 2006

The first hohlraum experiments on the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, 228 (2004)] using the first four laser beams have activated the indirect-drive experimental capabilities and tested radiation temperature limits imposed by hohlraum plasma filling. Vacuum hohlraums have been irradiated with laser powers up to 9 TW, 1 to 9ns long square pulses and energies of up to 17kJ to study the hohlraum radiation temperature scaling with the laser power and hohlraum size, and to make contact with hohlraum experiments performed previously at other laser facilities. Furthermore, for a variety of hohlraum sizes and pulse lengths, the measured x-ray flux shows signatures of plasma filling that coincide with hard x-ray emission from plasma streaming out of the hohlraum. These observations agree with hydrodynamic simulations and with analytical modeling that includes hydrodynamic and coronal radiative losses. The modeling predicts radiation temperature limits on full NIF (1.8MJ) that are significantly greater than required for ignition hohlraums.
Multidimensional spatial-spectral holographic interpretation of NMR photography
Authors: Kiruluta Andrew J. M.
Published: May 2006

A spectral holographic interpretation arises naturally in nuclear magnetic resonance (NMR) photography from either the intrinsic chemical shift anisotropy of the spin system or the field inhomogeneity due to the applied spatial encoding gradients. We can thus think of NMR photography as arising from a “diffraction” off a spatial-spectral holographic grating. The spatial holographic component arises from a high dielectric constant (>50) of the NMR medium at high field strength (>4T) when the excitation wavelength is commensurate with the size of the NMR sample; otherwise, it is a volume spectral holographic grating. In this paper, the NMR localized spectroscopy (imaging) equation is derived from the principles of spatial-spectral holography. Holographic properties of storage and programmable time delay and time reversal are shown to follow naturally from this viewpoint and are experimentally demonstrated in an inhomogeneously broadened NMR sample. These ideas are shown to be extendable to complex signal processing functions such as recognition, correlations, and triple products.

This article is being retracted effective 8 November 2011.
The electronic mean-field configuration interaction method. I. Theory and integral formulas
Authors: Cassam-Chenaï Patrick
Published: May 2006

In this article, we introduce a new method for solving the electronic Schrödinger equation. This new method follows the same idea followed by the mean-field configuration interaction method already developed for molecular vibrations; i.e., groups of electronic degrees of freedom are contracted together in the mean field of the other degrees. If the same partition of electronic degrees of freedom is iterated, a self-consistent field method is obtained. Making coarser partitions (i.e., including more degrees in the same groups) and discarding the high energy states, the full configuration interaction limit can be approached. In contrast with the usual group function theory, no strong orthogonality condition is enforced. We have made use of a generalized version of the fundamental formula defining a Hopf algebra structure to derive Hamiltonian and overlap matrix element expressions which respect the group structure of the wave function as well as its fermionic symmetry. These expressions are amenable to a recursive computation.
The experimental determination of the torsional barrier and shape for disilane
Authors: Moazzen-Ahmadi N. , Horneman V.-M.
Published: May 2006

The torsional spectrum of disilane was recorded for the first time under high-pressure-pathlength conditions and at a spectral resolution of 0.007cm−1 using a Bruker IFS-120 HR Fourier transform spectrometer. The spectrum shows six distinct Q branches. The most prominent Q branch is near 130cm−1 which is a blend of four components of the torsional fundamental. Of the remaining five, four were assigned to the first torsional hot band (v4=2←1) and one to the second torsional hot band (v4=3←2). Over 350 transitions were identified. An analysis of the torsional fundamental, the first torsional hot band, and the lower state combination differences from frequencies of the vibrational bands ν9 and ν9+ν4−ν4 was made to characterize the torsion-rotation Hamiltonian in the ground vibrational state. The barrier height, barrier shape, and the rotational constant about the Si–Si bond were determined to be 404.344(83)cm−1, 2.255(65)cm−1, and 43208(28)MHz, respectively. Comparison of simulated and the experimental spectra yielded (μ‖−μ⊥)∕μ⊥=−4(1) for the torsional dipole moments. This ratio compares well with −3.39(6) for ethane. A comparison of molecular parameters obtained here is made with those for methyl silane and ethane.
The local structure of protonated water from x-ray absorption and density functional theory
Authors: Cavalleri Matteo , Näslund Lars-Åke , Edwards David C. , Wernet Philippe , Ogasawara Hirohito , Myneni Satish , Ojamäe Lars , Odelius Michael , Nilsson Anders , Pettersson Lars G. M.
Published: May 2006

We present a combined x-ray absorption spectroscopy/computational study of water in hydrochloric acid (HCl) solutions of varying concentration to address the structure and bonding of excess protons and their effect on the hydrogen bonding network in liquid water. Intensity variations and energy shifts indicate changes in the hydrogen bonding structure in water as well as the local structure of the protonated complex as a function of the concentration of protons. In particular, in highly acidic solutions we find a dominance of the Eigen form, H3O+, while the proton is less localized to a specific water under less acidic conditions.
Eddy viscosity and flow properties of the solar wind: Co-rotating interaction regions, coronal-mass-ejection sheaths, and solar-wind/magnetosphere coupling
Authors: Borovsky Joseph E.
Published: May 2006

The coefficient of magnetohydrodynamic (MHD) eddy viscosity of the turbulent solar wind is calculated to be νeddy≈1.3×1017cm2∕s: this coefficient is appropriate for velocity shears with scale thicknesses larger than the ∼106 km correlation length of the solar-wind turbulence. The coefficient of MHD eddy viscosity is calculated again accounting for the action of smaller-scale turbulent eddies on smaller scale velocity shears in the solar wind. This eddy viscosity is quantitatively tested with spacecraft observations of shear flows in co-rotating interaction regions (CIRs) and in coronal-mass-ejection (CME) sheaths and ejecta. It is found that the large-scale (∼107km) shear of the CIR fractures into intense narrow (∼105km) slip zones between slabs of differently magnetized plasma. Similarly, it is found that the large-scale shear of CME sheaths also fracture into intense narrow slip zones between parcels of differently magnetized plasma. Using the solar-wind eddy-viscosity coefficient to calculate vorticity-diffusion time scales and comparing those time scales with the ∼100-h age of the solar-wind plasma at 1AU, it is found that the slip zones are much narrower than eddy-viscosity theory says they should be. Thus, our concept of MHD eddy viscosity fails testing. For the freestream turbulence effect in solar-wind magnetosphere coupling, the eddy-viscous force of the solar wind on the Earth's magnetosphere is rederived accounting for the action of turbulent eddies smaller than the correlation length, along with other corrections. The improved derivation of the solar-wind driver function for the turbulence effect fails to yield higher correlation coefficients between measurements of the solar-wind driver and measurements of the response of the Earth's magnetosphere.
High-power quantum cascade lasers grown by low-pressure metal organic vapor-phase epitaxy operating in continuous wave above 400K
Authors: Diehl L. , Bour D. , Corzine S. , Zhu J. , Höfler G. , Lončar M. , Troccoli M. , Capasso Federico
Published: May 2006

High-power quantum cascade lasers (QCLs) working in continuous wave (cw) above 400K are presented. The material was grown by low-pressure metal organic vapor-phase epitaxy and processed into narrow buried heterostructure lasers. A cw output power of 204mW was obtained at 300K with an 8.38μm wavelength, 3mm long and 7.5μm wide coated laser. The device operates in cw mode above 400K, which exceeds the previous maximum cw temperature operation of QCLs by approximately 60K. Preliminary reliability data obtained by accelerated aging tests indicate a remarkable robustness of the lasers.
Blue luminescent isolated Alq3 molecules in a solid-state matrix
Authors: Levichkova M. M. , Assa J. J. , Fröb H. , Leo K.
Published: May 2006

Thin vacuum deposited films of aluminum tris(8-hydroxyquinolinate) (Alq3) embedded in SiO2 matrix at concentrations corresponding to a single-molecule distribution are investigated. The spectral properties of the films are studied by luminescence spectroscopy. It is established that the dilution of Alq3 in the matrix leads to blueshift of the luminescence maximum up to 0.28eV compared to pure Alq3 layers. In contrast to the recently reported facial isomer of Alq3 in the crystalline δ phase, we conclude from our spectral data the observation of facial isomer molecules.
Synchronization in neuronal population with the variable coupling strength in the presence of external stimulus
Authors: Jiao Xianfa , Wang Rubin
Published: May 2006

In this letter, taking into account the variation of coupling strength, we present a dynamical model of neuronal oscillator population subject to external stimulus and noise, and introduce an average number density of coupling pairs to describe the synchronization behavior of the neuronal oscillator population. The numerical simulations indicate that external stimulus enhances the synchronized activity in neuronal population and the coupling between the neuronal oscillators. With a stronger stimulus, the synchronization in neuronal population emerges rapidly, and the duration of the synchronization is longer. The numerical simulations also show that when the combined stimuli of different modalities are performed simultaneously, there is a reciprocal or competitive interaction between the different stimulus modalities.
Novel deformation mechanism of twinned nanowires
Authors: Wang Jian , Huang Hanchen
Published: May 2006

This letter reports a novel deformation mechanism of twinned Cu nanowires, based on molecular statics and dynamics simulations. Under mechanical loading, Shockley partial dislocations nucleate and glide on a {111} plane toward a twin boundary. Upon penetration of the twin boundary, a dislocation with Burgers vector of 12⟨110⟩ nucleates and glides on a {100} plane, instead of conventional {111} planes. The dislocation nucleation on {100} planes is facilitated by the intersection of surface and twin boundary, and the dislocation glide is primarily facilitated by the matching of Burgers vector along the normal direction of the twin boundary.
Highly efficient organic electroluminescent device with modified cathode
Authors: Choulis Stelios A. , Mathai Mathew K. , Choong Vi-En , So Franky
Published: May 2006

One of the key parameters for high efficiency organic electrophosphorescent light emitting diodes is charge injection into the phosphorescence compound. By introducing a hybrid device architecture, and incorporating electron and hole interfacial layers with lowest unoccupied molecular orbital and highest occupied molecular orbital levels similar to that of the phosphorescence compound, on the cathode and the anode side of the device, respectively, charge injection properties were improved. A green electrophosphorescence device with luminous efficacy of 50lm∕W at luminance efficiency reaching 55cd∕A was demonstrated.
Effect of uniaxial stress on excitons in a self-assembled quantum dot
Authors: Seidl Stefan , Kroner Martin , Högele Alexander , Karrai Khaled , Warburton Richard J. , Badolato Antonio , Petroff Pierre M.
Published: May 2006

The fine structure of the neutral exciton in a single self-assembled InGaAs quantum dot is investigated under the effect of an applied uniaxial stress. The spectrum of the excitonic Rayleigh scattering was measured in reflectivity using high-resolution laser spectroscopy while the sample was submitted to a tunable uniaxial stress along its [110] crystal axis. We show that using this stretching technique, the quantum dot potential is elastically deformable such that the exciton fine structure splitting can be substantially reduced.
Polarization-insensitive liquid crystal Fresnel lens of dynamic focusing in an orthogonal binary configuration
Authors: Kim Dong-Woo , Yu Chang-Jae , Kim Hak-Rin , Kim Sung-Jin , Lee Sin-Doo
Published: May 2006

We report on a polarization-insensitive liquid crystal (LC) Fresnel lens with the centrosymmetry of dynamic focusing in an orthogonally alternating hybrid configuration. The polarization-insensitive Fresnel lens having such successive orthogonal hybrid alignment in two adjacent zones was fabricated using a single-masking process through two-step exposure of a linearly polarized ultraviolet light. It was found that the dynamic focusing property of the LC Fresnel lens is electrically controllable and entirely centrosymmetrical irrespective of the polarization state of an incident light.
Brillouin scattering spectroscopy for a laser heated diamond anvil cell
Authors: Li Fangfei , Cui Qiliang , He Zhi , Cui Tian , Gao Chunxiao , Zhou Qiang , Zou Guangtian
Published: May 2006

An in situ Brillouin scattering system is developed to study the elastic properties of materials under high pressure-temperature conditions in deep interior of the Earth and planets. This system integrates confocal Brillouin scattering system with a double-sided laser heated system. Furthermore, the magnetic sputter film deposition technique and photolithographic shaping method are used to grow heat insulated layer and internal heat absorber on the surface of diamond anvil for heating sample easily and uniformly. To study the elastic properties of “hot ice,” the Brillouin scattering of liquid water was performed up to 21.8GPa and 1170K in this paper.
Red phosphorescence in Sr4Al14O25: Cr3+,Eu2+,Dy3+ through persistent energy transfer
Authors: Zhong Ruixia , Zhang Jiahua , Zhang Xia , Lu Shaozhe , Wang Xiao-jun
Published: May 2006

Cr 3 + , Eu2+, and Dy3+ codoped Sr4Al14O25 has been synthesized by solid-state reaction. Long persistent phosphorescence in red of Cr3+ and in blue of Eu2+ has been observed in this system with persistence times of over 2h for the red and 10h for the blue. Red phosphorescence is performed through persistent energy transfer from Eu2+ to Cr3+, converting the blue to the red. Concentration effect is analyzed based on energy transfer. The calculated results are in good agreement with the experimental data. The different decay patterns of the red and blue phosphorescence are measured and discussed.
Omnidirectional terahertz mirrors: A key element for future terahertz communication systems
Authors: Krumbholz N. , Gerlach K. , Rutz F. , Koch M. , Piesiewicz R. , Kürner T. , Mittleman D.
Published: May 2006

We present an omnidirectional mirror for the terahertz range made from polypropylene and high-resistivity silicon. The structure is characterized by time-domain terahertz spectroscopy. The experimental data are in good agreement with transfer matrix calculations. In the frequency band between 319 and 375GHz the mirror is highly reflecting for all incidence angles and s as well as p polarization.
Binding crossmodal object features in perirhinal cortex
Authors: Taylor Kirsten I. , Moss Helen E. , Stamatakis Emmanuel A. , Tyler Lorraine K.
Published: May 2006

Knowledge of objects in the world is stored in our brains as rich, multimodal representations. Because the neural pathways that process this diverse sensory information are largely anatomically distinct, a fundamental challenge to cognitive neuroscience is to explain how the brain binds the different sensory features that comprise an object to form meaningful, multimodal object representations. Studies with nonhuman primates suggest that a structure at the culmination of the object recognition system (the perirhinal cortex) performs this critical function. In contrast, human neuroimaging studies implicate the posterior superior temporal sulcus (pSTS). The results of the functional MRI study reported here resolve this apparent discrepancy by demonstrating that both pSTS and the perirhinal cortex contribute to crossmodal binding in humans, but in different ways. Significantly, only perirhinal cortex activity is modulated by meaning variables (e.g., semantic congruency and semantic category), suggesting that these two regions play complementary functional roles, with pSTS acting as a presemantic, heteromodal region for crossmodal perceptual features, and perirhinal cortex integrating these features into higher-level conceptual representations. This interpretation is supported by the results of our behavioral study: Patients with lesions, including the perirhinal cortex, but not patients with damage restricted to frontal cortex, were impaired on the same crossmodal integration task, and their performance was significantly influenced by the same semantic factors, mirroring the functional MRI findings. These results integrate nonhuman and human primate research by providing converging evidence that human perirhinal cortex is also critically involved in processing meaningful aspects of multimodal object representations.
Salt screening and specific ion adsorption determine neutral-lipid membrane interactions
Authors: Petrache Horia I. , Zemb Thomas , Belloni Luc , Parsegian V. Adrian
Published: May 2006

The simplest, single-component biological membrane challenges accepted models of macromolecular interactions: lipid lamellar phases swell when immersed in monovalent salt solutions. Moreover, typical of a Hofmeister series, Br salts swell multilayers more than Cl salts, offering an excellent opportunity to investigate long-standing questions of ionic specificity. In accord with earlier measurements of liposome mobilities in electric fields, we find an added electrostatic repulsion of membranes due to anion binding, with a much stronger Br binding compared with Cl. However, contrary to the expectation that electrostatic repulsion should vanish in high salinity, swelling of lipid multilayers is monotonic with increasing salt concentration for both Br and Cl salts. The apparent contradiction is resolved by recognizing that although the electrostatic repulsion is progressively screened by increasing salt concentration, so is the van der Waals (vdW) attraction. Negligible in low salt, weakening of vdW forces becomes significant by the time electrostatic forces vanish. The result is a smooth monotonic swelling curve with no apparent distinction between low and high salt concentration regimes. Furthermore, when compared with theoretical predictions, measured vdW forces decay much too slowly with added salt. However, by accounting for the recently measured salt deficit near lipid bilayers, the expected scaling with Debye screening length is recovered. The combination of ion-specific binding and nonspecific ionic screening of low-frequency fluctuations explains salt effects on lipid membrane interactions and, by extension, explains specific (Hofmeister) effects at macromolecular interfaces between low and high dielectric.
Bayesian error analysis model for reconstructing transcriptional regulatory networks
Authors: Sun Ning , Carroll Raymond J. , Zhao Hongyu
Published: May 2006

Transcription regulation is a fundamental biological process, and extensive efforts have been made to dissect its mechanisms through direct biological experiments and regulation modeling based on physical–chemical principles and mathematical formulations. Despite these efforts, transcription regulation is yet not well understood because of its complexity and limitations in biological experiments. Recent advances in high throughput technologies have provided substantial amounts and diverse types of genomic data that reveal valuable information on transcription regulation, including DNA sequence data, protein–DNA binding data, microarray gene expression data, and others. In this article, we propose a Bayesian error analysis model to integrate protein–DNA binding data and gene expression data to reconstruct transcriptional regulatory networks. There are two unique aspects to this proposed model. First, transcription is modeled as a set of biochemical reactions, and a linear system model with clear biological interpretation is developed. Second, measurement errors in both protein–DNA binding data and gene expression data are explicitly considered in a Bayesian hierarchical model framework. Model parameters are inferred through Markov chain Monte Carlo. The usefulness of this approach is demonstrated through its application to infer transcriptional regulatory networks in the yeast cell cycle.
X-ray structure of a native calicivirus: Structural insights into antigenic diversity and host specificity
Authors: Chen Rong , Neill John D. , Estes Mary K. , Prasad B. V. Venkataram
Published: May 2006

Caliciviruses, grouped into four genera, are important human and veterinary pathogens with a potential for zoonosis. In these viruses, capsid-related functions such as assembly, antigenicity, and receptor interactions are predominantly encoded in a single protein that forms an icosahedral capsid. Understanding of the immunologic functions and pathogenesis of human caliciviruses in the
Norovirus
and
Sapovirus
genera is hampered by the lack of a cell culture system or animal models. Much of our understanding of these viruses, including the structure, has depended on recombinant capsids. Here we report the atomic structure of a native calicivirus from the
Vesivirus
genus that exhibits a broad host range possibly including humans and map immunological function onto a calicivirus structure. The vesivirus structure, despite a similar architectural design as seen in the recombinant norovirus capsid, exhibits novel features and indicates how the unique modular organization of the capsid protein with interdomain flexibility, similar to an antibody structure with a hinge and an elbow, integrates capsid-related functions and facilitates strain diversity in caliciviruses. The internally located N-terminal arm participates in a novel network of interactions through domain swapping to assist the assembly of the shell domain into an icosahedral scaffold, from which the protruding domain emanates. Neutralization epitopes localize to three hypervariable loops in the distal portion of the protruding domain surrounding a region that exhibits host-specific conservation. These observations suggest a mechanism for antigenic diversity and host specificity in caliciviruses and provide a structural framework for vaccine development.
Evidence that the Y chromosome influences autoimmune disease in male and female mice
Authors: Teuscher Cory , Noubade Rajkumar , Spach Karen , McElvany Benjamin , Bunn Janice Y. , Fillmore Parley D. , Zachary James F. , Blankenhorn Elizabeth P.
Published: May 2006

Experimental allergic encephalomyelitis (EAE), an autoimmune model of multiple sclerosis, is a complex disease influenced by genetic, intrinsic, and environmental factors. In this study, we questioned whether parent-of-origin effects influence EAE, using reciprocal F2intercross progeny generated between EAE-susceptible SJL/J (S) and EAE-resistant B10.S/SgMcdJ (B) mice. EAE susceptibility and severity were found to be different in female BS × BS intercross mice as compared with females from the three other birth crosses (BS × SB, SB × SB, and SB × BS), and in fact, both traits in female mice resembled those of their male siblings. This masculinization is associated with transmission of the SJL/J Y chromosome and an increased male-to-female sex ratio. Related studies using progeny of C57BL/6J Y-chromosome substitution strains demonstrate that the Y chromosome again influences EAE in both male and female mice, and that the disease course in females resembles that of their male littermates. Importantly, these data provide experimental evidence supporting the existence of a Y-chromosome polymorphism capable of modifying autoimmune disease susceptibility in both males and females.
Direct and fast detection of neuronal activation in the human brain with diffusion MRI
Authors: Le Bihan Denis , Urayama Shin-ichi , Aso Toshihiko , Hanakawa Takashi , Fukuyama Hidenao
Published: May 2006

Using MRI, we found that a slowly diffusing water pool was expanding (1.7 ± 0.3%) upon activation on the human visual cortex at the detriment of a faster diffusing pool. The time course of this water phase transition preceded the activation-triggered vascular response detected by usual functional MRI by several seconds. The observed changes in water diffusion likely reflect early biophysical events that take place in the activated cells, such as cell swelling and membrane expansion. Although the exact mechanisms remain to clarify, access to such an early and direct physiological marker of cortical activation with MRI will provide opportunities for functional neuroimaging of the human brain.
Fluoxetine targets early progenitor cells in the adult brain
Authors: Encinas Juan M. , Vaahtokari Anne , Enikolopov Grigori
Published: May 2006

Chronic treatment with antidepressants increases neurogenesis in the adult hippocampus. This increase in the production of new neurons may be required for the behavioral effects of antidepressants. However, it is not known which class of cells within the neuronal differentiation cascade is targeted by the drugs. We have generated a reporter mouse line, which allows identification and classification of early neuronal progenitors. It also allows accurate quantitation of changes induced by neurogenic agents in these distinct subclasses of neuronal precursors. We use this line to demonstrate that the selective serotonin reuptake inhibitor antidepressant fluoxetine does not affect division of stem-like cells in the dentate gyrus but increases symmetric divisions of an early progenitor cell class. We further demonstrate that these cells are the sole class of neuronal progenitors targeted by fluoxetine in the adult brain and suggest that the fluoxetine-induced increase in new neurons arises as a result of the expansion of this cell class. This finding defines a cellular target for antidepressant drug therapies.
Hotspots for copy number variation in chimpanzees and humans
Authors: Perry George H. , Tchinda Joelle , McGrath Sean D. , Zhang Junjun , Picker Simon R. , Cáceres Angela M. , Iafrate A. John , Tyler-Smith Chris , Scherer Stephen W. , Eichler Evan E. , Stone Anne C. , Lee Charles
Published: May 2006

Copy number variation is surprisingly common among humans and can be involved in phenotypic diversity and variable susceptibility to complex diseases, but little is known of the extent of copy number variation in nonhuman primates. We have used two array-based comparative genomic hybridization platforms to identify a total of 355 copy number variants (CNVs) in the genomes of 20 wild-born chimpanzees (
Pan troglodytes
) and have compared the identified chimpanzee CNVs to known human CNVs from previous studies. Many CNVs were observed in the corresponding regions in both chimpanzees and humans; especially those CNVs of higher frequency. Strikingly, these loci are enriched 20-fold for ancestral segmental duplications, which may facilitate CNV formation through nonallelic homologous recombination mechanisms. Therefore, some of these regions may be unstable “hotspots” for the genesis of copy number variation, with recurrent duplications and deletions occurring across and within species.
Complex genomic alterations and gene expression in acute lymphoblastic leukemia with intrachromosomal amplification of chromosome 21
Authors: Strefford Jon C. , van Delft Frederik W. , Robinson Hazel M. , Worley Helen , Yiannikouris Olga , Selzer Rebecca , Richmond Todd , Hann Ian , Bellotti Tony , Raghavan Manoj , Young Bryan D. , Saha Vaskar , Harrison Christine J.
Published: May 2006

We have previously identified a unique subtype of acute lymphoblastic leukemia (ALL) associated with a poor outcome and characterized by intrachromosomal amplification of chromosome 21 including theRUNX1gene (iAMP21). In this study, array-based comparative genomic hybridization (aCGH) (n= 10) detected a common region of amplification (CRA) between 33.192 and 39.796 Mb and a common region of deletion (CRD) between 43.7 and 47 Mb in 100% and 70% of iAMP21 patients, respectively. High-resolution genotypic analysis (n= 3) identified allelic imbalances in the CRA. Supervised gene expression analysis showed a distinct signature for eight patients with iAMP21, with 10% of overexpressed genes located within the CRA. The mean expression of these genes was significantly higher in iAMP21 when compared to other ALL samples (n= 45). Although genomic copy number correlated with overall gene expression levels within areas of loss or gain, there was considerable individual variation. A unique subset of differentially expressed genes, outside the CRA and CRD, were identified when gene expression signatures of iAMP21 were compared to ALL samples withETV6-RUNX1fusion (n= 21) or high hyperdiploidy with additional chromosomes 21 (n= 23). From this analysis,LGMNwas shown to be overexpressed in patients with iAMP21 (P= 0.0012). Genomic and expression data has further characterized this ALL subtype, demonstrating high levels of 21q instability in these patients leading to proposals for mechanisms underlying this clinical phenotype and plausible alternative treatments.
The chemokine SDF-1/CXCL12 modulates the firing pattern of vasopressin neurons and counteracts induced vasopressin release through CXCR4
Authors: Callewaere Céline , Banisadr Ghazal , Desarménien Michel G. , Mechighel Patricia , Kitabgi Patrick , Rostène William H. , Mélik Parsadaniantz Stéphane
Published: May 2006

Chemokines play a key role in inflammation. They are expressed not only in neuroinflammatory conditions, but also constitutively by different cell types, including neurons in the normal brain, suggesting that they may act as modulators of neuronal functions. Here, we investigated a possible neuroendocrine role of the chemokine stromal cell-derived factor 1 (SDF-1)/CXCL12. We demonstrated the colocalization of SDF-1 and its receptor CXCR4 with arginine vasopressin (AVP) in the magnocellular neurons of the supraoptic nucleus (SON) and the paraventricular hypothalamic nucleus and on AVP projections to the neurohypophysis. Electrophysiological recordings of SON neurons demonstrated that SDF-1 affects the electrical activity of AVP neurons through CXCR4, resulting in changes in AVP release. We observed that SDF-1 can blunt the autoregulation of AVP release
in vitro
and counteract angiotensin II-induced plasma AVP release
in vivo
. Furthermore, a short-term physiological increase in AVP release induced by enhanced plasma osmolarity, which was produced by the administration of 1 M NaCl i.p., was similarly blocked by central injection of SDF-1 through CXCR4. A change in water balance by long-term salt loading induced a decrease in both SDF-1 and CXCR4 parallel to that of AVP immunostaining in SON. From these data, we demonstrate that chemokine actions in the brain are not restricted to inflammatory processes. We propose to add to the known autoregulation of AVP on its own neurons, a second autocrine system induced by SDF-1 able to modulate central AVP neuronal activity and release.
The negative regulator of plant cold responses, HOS1, is a RING E3 ligase that mediates the ubiquitination and degradation of ICE1
Authors: Dong Chun-Hai , Agarwal Manu , Zhang Yiyue , Xie Qi , Zhu Jian-Kang
Published: May 2006

Plant responses to cold stress are mediated by a transcriptional cascade, in which the transcription factor ICE1 and possibly related proteins activate the expression of C-repeat (CRT)-binding factors (
CBF
s), leading to the transcription of downstream effector genes. The variant RING finger protein
h
igh expression of
os
motically responsive gene (HOS)1 was identified genetically as a negative regulator of cold responses. We present evidence here that HOS1 is an E3 ligase required for the ubiquitination of ICE1. HOS1 physically interacts with ICE1 and mediates the ubiquitination of ICE1 both
in vitro
and
in vivo
. We found that cold induces the degradation of ICE1 in plants, and this degradation requires HOS1. Consistent with enhanced cold-responsive gene expression in loss-of-function
hos1
mutant plants, overexpression of HOS1 represses the expression of
CBF
s and their downstream genes and confers increased sensitivity to freezing stress. Our results indicate that cold stress responses in
Arabidopsis
are attenuated by a ubiquitination/proteasome pathway in which HOS1 mediates the degradation of the ICE1 protein.