bluuebunny/crossref_metadata_2025 huggingface dataset:
5‐Hydroxydecanoate is metabolised in mitochondria and creates a rate‐limiting bottleneck for β‐oxidation of fatty acids
Authors: Hanley Peter J. , Dröse Stefan , Brandt Ulrich , Lareau Rachel A. , Banerjee Abir L. , Srivastava D. K. , Banaszak Leonard J. , Barycki Joseph J. , Van Veldhoven Paul P. , Daut Jürgen
Published: October 2004

5‐Hydroxydecanoate (5‐HD) blocks pharmacological and ischaemic preconditioning, and has been postulated to be a specific inhibitor of mitochondrial ATP‐sensitive K+ (KATP) channels. However, recent work has shown that 5‐HD is activated to 5‐hydroxydecanoyl‐CoA (5‐HD‐CoA), which is a substrate for the first step of β‐oxidation. We have now analysed the complete β‐oxidation of 5‐HD‐CoA using specially synthesised (and purified) substrates and enzymes, as well as isolated rat liver and heart mitochondria, and compared it with the metabolism of the physiological substrate decanoyl‐CoA. At the second step of β‐oxidation, catalysed by enoyl‐CoA hydratase, enzyme kinetics were similar using either decenoyl‐CoA or 5‐hydroxydecenoyl‐CoA as substrate. The last two steps were investigated using l‐3‐hydroxyacyl‐CoA dehydrogenase (HAD) coupled to 3‐ketoacyl‐CoA thiolase. Vmax for the metabolite of 5‐HD (3,5‐dihydroxydecanoyl‐CoA) was fivefold slower than for the corresponding metabolite of decanoate (l‐3‐hydroxydecanoyl‐CoA). The slower kinetics were not due to accumulation of d‐3‐hydroxyoctanoyl‐CoA since this enantiomer did not inhibit HAD. Molecular modelling of HAD complexed with 3,5‐dihydroxydecanoyl‐CoA suggested that the 5‐hydroxyl group could decrease HAD turnover rate by interacting with critical side chains. Consistent with the kinetic data, 5‐hydroxydecanoyl‐CoA alone acted as a weak substrate in isolated mitochondria, whereas addition of 100 μm 5‐HD‐CoA inhibited the metabolism of decanoyl‐CoA or lauryl‐carnitine. In conclusion, 5‐HD is activated, transported into mitochondria and metabolised via β‐oxidation, albeit with rate‐limiting kinetics at the penultimate step. This creates a bottleneck for β‐oxidation of fatty acids. The complex metabolic effects of 5‐HD invalidate the use of 5‐HD as a blocker of mitochondrial KATP channels in studies of preconditioning.
Effects of gestational age and cortisol treatment on ovine fetal heart function in a novel biventricular Langendorff preparation
Authors: Fletcher Andrew J. W. , Forhead Alison J. , Fowden Abigail L. , Ford Will R. , Nathanielsz Peter W. , Giussani Dino A.
Published: October 2004

Structural and functional maturation of a number of fetal organs and physiological systems occurs in the immediate period prior to term, in association with the prepartum increase in fetal plasma cortisol concentration. At present, little is known about how myocardial sensitivity to adrenergic and muscarinic cholinergic stimulation changes as the fetus approaches term, nor the role of the prepartum increase in plasma cortisol concentration in mediating these changes. This study used a novel Langendorff, biventricular, ovine fetal heart preparation to investigate the effects of advancing gestation and cortisol treatment on myocardial sensitivity to adrenergic (isoprenaline) and muscarinic cholinergic (carbachol) stimulation. It was hypothesized that cortisol infusion would fully mimic developmental changes in myocardial responsiveness to adrenergic and cholinergic stimulation. Sixteen Welsh Mountain sheep fetuses were surgically prepared under general anaesthesia with vascular catheters. At 125 ± 1 days gestational age (dGA; term, 145 dGA) fetuses were infused with saline vehicle (n= 7; Premature Control) or with cortisol (n= 4; 2–3 mg kg−1 d−1i.v.; Premature Cortisol) for 5 days. The Term Control group (n= 5) comprised fetuses that were surgically prepared at 130 dGA and infused with vehicle for 5 days prior to delivery (n= 2), or that received no surgery (n= 3). Under terminal anaesthesia, Premature Control and Premature Cortisol fetuses were delivered at 130 dGA and Term Control fetuses between 135 and 143 dGA. Following exsanguination under anaesthesia, fetal hearts were mounted in the Langendorff preparation, allowing measurement of left ventricular (LV) developed pressure and right ventricular (RV) developed pressure, heart rate (HR), coronary perfusion pressure and perfusate distribution to the myocardium. Cortisol infusion elevated fetal plasma cortisol concentrations to values similar to those measured close to term (45.0 ± 7.1 ng ml−1). Advancing gestational age, but not cortisol treatment, enhanced fetal LV developed pressure, RV developed pressure and HR responses to carbachol (P < 0.05). Advancing gestational age, but not cortisol treatment, suppressed fetal LV developed pressure, RV developed pressure and HR responses to isoprenaline (P < 0.05). Maximum doses of either carbachol or isoprenaline had no effect on coronary perfusate distribution. Changes in myocardial responsiveness to adrenergic and muscarinic cholinergic stimulation with advancing gestation provide mechanisms that contribute to the maturation of the cardiovascular system as the ovine fetus approaches term. These changes in myocardial responsiveness are not solely dependent on preparturient elevations in fetal plasma cortisol concentration.
Comparison of forearm blood flow responses to incremental handgrip and cycle ergometer exercise: relative contribution of nitric oxide
Authors: Green Daniel J. , Bilsborough William , Naylor Louise H. , Reed Chris , Wright Jeremy , O'Driscoll Gerry , Walsh Jennifer H.
Published: October 2004

The contribution of endothelium‐derived nitric oxide (NO) to exercise hyperaemia remains controversial. Disparate findings may, in part, be explained by different shear stress stimuli as a result of different types of exercise. We have directly compared forearm blood flow (FBF) responses to incremental handgrip and cycle ergometer exercise in 14 subjects (age ±s.e.m.) using a novel software system which calculates conduit artery blood flow continuously across the cardiac cycle by synchronising automated edge‐detection and wall tracking of high resolution B‐mode arterial ultrasound images and Doppler waveform envelope analysis. Monomethyl arginine (l‐NMMA) was infused during repeat bouts of each incremental exercise test to assess the contribution of NO to hyperaemic responses. During handgrip, mean FBF increased with workload (P < 0.01) whereas FBF decreased at lower cycle workloads (P < 0.05), before increasing at 120 W (P < 0.001). Differences in these patterns of mean FBF response to different exercise modalities were due to the influence of retrograde diastolic flow during cycling, which had a relatively larger impact on mean flows at lower workloads. Retrograde diastolic flow was negligible during handgrip. Although mean FBF was lower in response to cycling than handgrip exercise, the impact of l–NMMA was significant during the cycle modality only (P < 0.05), possibly reflecting the importance of an oscillatory antegrade/retrograde flow pattern on shear stress‐mediated release of NO from the endothelium. In conclusion, different types of exercise present different haemodynamic stimuli to the endothelium, which may result in differential effects of shear stress on the vasculature.
Gender‐modulated endogenous baseline neuropeptide Y Y1‐receptor activation in the hindlimb of Sprague‐Dawley rats
Authors: Jackson Dwayne N. , Milne Kevin J. , Noble Earl G. , Shoemaker J. Kevin
Published: October 2004

This study examined the effect of neuropeptide Y Y1‐receptor blockade both alone, and in interaction with α1‐adrenoceptor antagonism, on basal hindlimb vascular conductance in male and female Sprague‐Dawley rats. Hindlimb vascular conductance was measured during infusion of BIBP3226 (Y1‐receptor antagonist; 100 μg kg−1), prazosin (α1‐receptor antagonist; 20 μg kg−1), and combined blockade. In males, vascular conductance increased 1.1 ± 0.3 μl min−1 mmHg−1 above baseline with BIBP3226, and 2.4 ± 0.4 μl min−1 mmHg−1 above baseline with prazosin (both P < 0.05). The increase in vascular conductance during combined blockade (5.1 ± 0.7 μl min−1 mmHg−1) was greater than the sum of the independent BIBP3226 and prazosin responses (P < 0.05). In females, basal hindlimb vascular conductance was unaffected by Y1‐receptor blockade. However, α1‐receptor blockade resulted in a 3.5 ± 0.6 μl min−1 mmHg−1 increase in vascular conductance above baseline, which was not different than the combined blockade condition. Males had greater skeletal muscle neuropeptide Y concentration (P < 0.05; ELISA) than females. Furthermore, compared with females, male skeletal muscle contained greater Y1‐receptor expression (P < 0.05; Western blot). It was concluded that, under baseline conditions, agonist and receptor‐based mechanisms for Y1‐receptor dependent control of vascular conductance in skeletal muscle was greater in male versus female rats.
NR2 subunit‐dependence of NMDA receptor channel block by external Mg2+
Authors: Qian Anqi , Buller Amy L. , Johnson Jon W.
Published: October 2004

The vital roles played by NMDA receptors in CNS physiology depend critically on powerful voltage‐dependent channel block by external Mg2+ (Mg2+o). NMDA receptor channel block by Mg2+o depends on receptor subunit composition: NR1/2A receptors (receptors composed of NR1 and NR2A subunits) and NR1/2B receptors are more strongly inhibited by Mg2+o than are NR1/2C or NR1/2D receptors. We investigated the effects of Mg2+o on single‐channel and whole‐cell currents recorded from recombinant NR1/2D and NR1/2A receptors expressed in HEK293 and 293T cells. The main conclusions are as follows: (1) Voltage‐dependent inhibition by Mg2+o of whole‐cell NR1/2D receptor responses was at least 4‐fold weaker than inhibition of NR1/2A receptor responses at all voltages tested. (2) Channel block by Mg2+o reduced the duration of NR1/2D receptor single‐channel openings; this reduction was used to estimate the apparent blocking rate of Mg2+o (k+,app). The k+,app for NR1/2D receptors was similar to but moderately slower than the k+,app obtained from cortical NMDA receptors composed of NR1, NR2A and NR2B subunits at all voltages tested. (3) Mg2+o blocking events induced an additional component in the closed‐duration distribution; this component was used to estimate the apparent unblocking rate of Mg2+o (k−,app). The k−,app for NR1/2D receptors was much faster than the k−,app for cortical receptors at all voltages tested. The voltage‐dependence of the k−,app of NR1/2D and cortical receptors differed in a manner that suggested that Mg2+o may permeate NR1/2D receptors more easily than cortical receptors. (4) Mg2+o inhibits NR1/2D receptors less effectively than cortical receptors chiefly because Mg2+o unbinds much more rapidly from NR1/2D receptors.
Capacitative calcium entry supports calcium oscillations in human embryonic kidney cells
Authors: Bird Gary St. J. , Putney James W.
Published: October 2004

Treatment of human epithelial kidney (HEK293) cells with low concentrations of the muscarinic agonist methacholine results in the activation of complex and repetitive cycling of intracellular calcium ([Ca2+]i), known as [Ca2+]i oscillations. These oscillations occur with a frequency that depends on the concentration of methacholine, whereas the magnitude of the [Ca2+]i spikes does not. The oscillations do not persist in the absence of extracellular Ca2+, leading to the conclusion that entry of Ca2+ across the plasma membrane plays a significant role in either their initiation or maintenance. However, treatment of cells with high concentrations of GdCl3, a condition which limits the flux of calcium ions across the plasma membrane in both directions, allows sustained [Ca2+]i oscillations to occur. This suggests that the mechanisms that both initiate and regenerate [Ca2+]i oscillations are intrinsic to the intracellular milieu and do not require entry of extracellular Ca2+. This would additionally suggest that, under normal conditions, the role of calcium entry is to sustain [Ca2+]i oscillations. By utilizing relatively specific pharmacological manoeuvres we provide evidence that the Ca2+ entry that supports Ca2+ oscillations occurs through the store‐operated or capacitative calcium entry pathway. However, by artificial introduction of a non‐store‐operated pathway into the cells (TRPC3 channels), we find that other Ca2+ entry mechanisms can influence oscillation frequency in addition to the store‐operated channels.
Vasopressin‐stimulated CFTR Cl− currents are increased in the renal collecting duct cells of a mouse model of Liddle's syndrome
Authors: Chang Chiz‐Tzung , Bens Marcelle , Hummler Edith , Boulkroun Sheerazed , Schild Laurent , Teulon Jacques , Rossier Bernard C. , Vandewalle Alain
Published: October 2004

Liddle's syndrome is a genetic form of hypertension linked to Na+ retention caused by activating mutations in the COOH terminus of the β or γ subunit of the epithelial sodium channel (ENaC). In this study, we used the short‐circuit current (Isc) method to investigate the effects of deamino‐8‐d‐arginine vasopressin (dDAVP) on Na+ and Cl− fluxes in primary cultures of cortical collecting ducts (CCDs) microdissected from the kidneys of mice with Liddle's syndrome carrying a stop codon mutation, corresponding to the β‐ENaC R566 stop mutation (L) found in the original pedigree. Compared to wild‐type (+/+) CCD cells, untreated L/+ and L/L CCD cells exhibited 2.7‐ and 4.2‐fold increases, respectively, in amiloride‐sensitive (Ams) Isc, reflecting ENaC‐dependent Na+ absorption. Short‐term incubation with dDAVP caused a rapid and significant increase (∼2‐fold) in Ams Isc in +/+, but not in L/+ or L/L CCD cells. In sharp contrast, dDAVP induced a greater increase in 5‐nitro‐2‐(3‐phenylpropamino)benzoate (NPPB)‐inhibited apical Cl− currents in amiloride‐treated L/L and L/+ cells than in their +/+ counterparts. Isc recordings performed under apical ion substituted conditions revealed that the dDAVP‐stimulated apical secretion of Cl−, which was absent in cultured CCDs lacking CFTR, was 1.8‐fold greater in L/+ and 3.7‐fold greater in L/L CCD cells than in their +/+ CCD counterparts. After the basal membrane had been permeabilized with nystatin and a basal‐to‐apical Cl− gradient had been imposed, dDAVP also stimulated larger Cl− currents across L/L and L/+ CCD layers than +/+ CCD layers. These findings demonstrate that vasopressin stimulates greater apical CFTR Cl− conductance in the renal CCD cells of mice with Liddle's syndrome than in wild‐type mice. This effect could contribute to the enhanced NaCl reabsorption observed in the distal nephron of patients with Liddle's syndrome.
Probing Electronic Transitions in Individual Carbon Nanotubes by Rayleigh Scattering
Authors: Sfeir Matthew Y. , Wang Feng , Huang Limin , Chuang Chia-Chin , Hone J. , O'Brien Stephen P. , Heinz Tony F. , Brus Louis E.
Published: October 2004

Rayleigh scattering spectra were obtained from individual single-walled carbon nanotubes with the use of a laser-generated visible and near-infrared supercontinuum. This diagnostic method is noninvasive and general for nanoscale objects. The approach permits clear identification of excited states in arbitrary metallic and semiconducting nanotubes. We analyzed spectral lineshapes in relation to the role of excitonic effects and correlated the results with Raman scattering data on individual tubes. The nanotube structure remained the same over distances of tens of micrometers. Small nanotube bundles retained distinct Rayleigh spectroscopic signatures of their component nanotubes, thus allowing the probing of nanotube-nanotube interactions.
FOUR-WAVE MIXING IN SEMICONDUCTOR TRAVELING-WAVE AMPLIFIERS FOR WAVELENGTH CONVERSION IN ALL-OPTICAL NETWORKS
Authors: VAHALA KERRY J. , ZHOU JIANHUI , GERAGHTY DAVID , LEE ROBERT , NEWKIRK MIKE , MILLER BARRY
Published: October 2004

Intraband modulation in semiconductor gain media has recently been shown to provide a wideband nonlinearity which is five orders of magnitude larger than the Kerr non-linearity in silica fiber. We discuss recent work on the application of this nonlinearity to the wavelength conversion function in all optical networks; specifically, carrier wavelength spectral translation by four-wave mixing. In addition to reviewing the current performance of these devices including conversion efficiency, signal-to-noise and a simple system demonstration, we will describe the underlying physics of the ultra-fast four-wave mixing mechanism and its application to TeraHertz spectroscopy of intraband scattering. An overview of wavelength conversion in the context of all-optical networks is provided and competing techniques to four-wave mixing wavelength conversion are also discussed.
AN INTRODUCTION TO HIGH SPEED TRANSMISSION SYSTEMS AND RELATED DEVICES IN CHINA
Authors: ZHAO ZI-SEN
Published: October 2004

This paper is an introduction of high speed optical communication systems used in China, especially those deployed by the Ministry of Post and Telecommunication.

Practical high speed systems, such as 565 Mb/s system and the optical devices used in these systems manufactured in China are described.

Further development of high speed systems and devices such as SDH systems at 622 Mb/s and 2.5 Gb/s, EDFA, MQW laser diodes and a comprehensive test bed are discussed.
QUANTUM WELL LASERS AND THEIR APPLICATIONS
Authors: CHEN LIANGHUI
Published: October 2004

Quantum well lasers have attracted a great deal of attention by their many advantages such as low threshold current density, excellent temperature feature, high modulation rate and wavelength adjustability etc. The investigation on quantum well laser in mainland China started in the early 80s. AlGaAs/GaAs QW laser diode and InGaAs/GaAs strained layer QW laser diode have been developed using MBE technology with extremely low threshold current and high T0. Now the growth technologies for QW structure have been expanded to MOCVD technology. Emission wavelengths, on longer wavelength sides have been expanded up to 1.3 µm and 1.55 µm with InGaAsP/InP material system for application in optical fiber communication. On shorter wavelength sides, the emission wavelength has been expanded to lower than 670 nm, for applications in optical information processing. The characteristics of these devices will be demonstrated in this paper.

The QW-DFB LD and low-dimension quantum wire and quantum dot lasers are under investigation.
GaAs/GaAlAs MULTIQUANTUM WELL ELECTROABSORPTION REFLECTION MODULATOR AND SELF ELECTRO-OPTIC EFFECT DEVICE (SEED)
Authors: WU RONGHAN , GAO WENZHI , ZHAO JUN , CHEN ZHIBIAO , LIN SHIMING , HUANG YONGZHEN , ZHONG ZHANTIAN , WANG QIMING , CAO MINGCUI , LI HONGPU
Published: October 2004

GaAs/GaAlAs MQW reflection modulators and SEED have been investigated. The analysis is emphasized on the combined behaviors of quantum confined Stark effect (QCSE), distributed Bragg reflector (DBR), and different asymmetric Fabry–Perot cavities (ASFP). Experimental results include the fabrication and characterization of a modulator array with a contrast ratio of about 10 dB and S-SEED array with optical switch energy less than 10 fJ /(µ m )2. An application of a modulator array in microoptical interconnection module is also demonstrated.
DISTRIBUTED FEEDBACK SEMICONDUCTOR LASERS AND THEIR APPLICATION IN PHOTONIC INTEGRATED DEVICES
Authors: LUO YI , WANG WEI
Published: October 2004

Distributed feedback (DFB) semiconductor lasers, especially those with gain-coupled (GC) mechanisms, are studied. A GaAlAs/GaAs multi-quantum well GC-DFB laser with a loss grating is fabricated using MBE for the first time. A 1.3 µm InGaAsP/InP DFB laser with a loss grating and one with a gain grating formed by injected carriers are developed by LPE and MOVPE, respectively.

GC-DFB lasers monolithically integrated with electroabsorption modulator is studied systematically for the first time. A novel integrated device structure is proposed and fabricated successfully.
HIGH PERFORMANCE TANDEM TWO-STAGE EDFA, BI-DIRECTIONAL FIBER RING LASER AND CORRELATED Q-SWITCHED/MODE-LOCKED FIBER FIGURE-8 LASER
Authors: PENG JIANGDE , LIU XIAOMING , TANG PINGSHENG , FAN CHONGCHENG , ZHOU BINGKUN
Published: October 2004

The recent progress on the research of Er 3+-doped fiber amplifier (EDFA) and laser (EDFL) in our laboratory is reported in this paper. A novel tandem two-stage EDFA configuration was achieved with a small signal gain of 41 dB, output power of 14.5 dBm (both at 1550 nm) and a bandwidth of more than 40 nm. In a novel coupled-ring EDFL, bi-directional simultaneous single longitudinal mode oscillation was accomplished with a laser linewidth of less than 1.0 GHz. By introducing polarization-evolution self-loss modulation in a LD pumped figure-8 all-fiber EDFL, correlated self Q-switching with variable period and mode-locking with low threshold were observed, respectively.
IMPACT OF ASE NOISE OF OPTICAL AMPLIFIER ON PIN-RECEIVER AND CALCULATION OF BIT-ERROR RATE
Authors: XIANG QIANGSHENG , XU ANSHI , WU DEMING , XIE LINZHEN
Published: October 2004

A simple analytical expression is derived to calculate the Bit-Error Rate in lightwave systems with optical amplifiers. According to this expression the Bit-Error Rate can be estimated by the signal power and the ASE spectrum density before the receiver. The theoretical calculation agrees with the experiment very well, so it can provide a method to judge the quality of the optical channel in the optical communication system with optical amplifiers. Futhermore, the impact of the ASE noise on the receiver sensitivity is discussed. It is important to select proper receivers in practical systems.
GaAs HIGH SPEED DEVICES AND CIRCUITS
Authors: LIANG CHUNGUANG , ZENG QINGMING , MA ZHENCHANG , YUAN MINGWEN , AO JINPING
Published: October 2004

This paper presents the R&D of GaAs-based high speed devices and circuits at the Hebei Semiconductor Research Institute (HSRI) in China. It is concerned with low noise and medium power GaAs-MESFET MMIC and monolithic laser diode driver and preamplifier for 2.4 Gb/s fiber communication application, GaAs-based high speed digital circuits like single and dual modulus frequency divider, digital/analog convertor, shift register, HEMT and HBT integrated circuits.
SMALL-SIGNAL ANALYSIS BY MEANS OF TRANSIENT EXCITATIONS AND ITS APPLICATIONS IN BIPOLAR TRANSISTOR MODELING
Authors: HERZEL FRANK , HEINEMANN BERND , GAJEWSKI HERBERT
Published: October 2004

We investigate the linear response of the terminal currents of a semiconductor device to external voltage perturbations by means of a two-dimensional device-simulation code. The calculation is based on the solution of the time-dependent drift-diffusion equations followed by Fourier decomposition of the voltages and currents. Our approach is especially suited for small-signal analysis at high frequencies since, in contrast to iterative methods, convergence problems do not appear. The memory capacity of the transient excitation method hardly exceeds that of the static problem. We apply our method to Si homojunction bipolar transistors and Si/Si 1–x Ge x/Si heterojunction bipolar transistors.
TEMPORAL PROPERTIES OF PHOTOREFRACTIVE MATERIALS
Authors: STATMAN D. , GILBREATH G.C.
Published: October 2004

Photorefractive two-beam coupling is examined experimentally for the case of high modulation depth. It is seen that the dynamics of signal growth and decay are best described by a double exponential function. The properties of this function with respect to interaction angle and modulation depth are studied. It is suggested that the equations governing photorefractive dynamics may be reduced to a pair of coupled bilinear rate equations which adequately describe photorefractive dynamics for high modulation depth.
ELECTRO-OPTICAL SWITCHING CHARACTERISTICS OF VOLUME HOLOGRAMS IN POLYMER DISPERSED LIQUID CRYSTALS
Authors: NATARAJAN L.V. , SUTHERLAND R.L. , TONDIGLIA V.P. , BUNNING T.J. , ADAMS W.W.
Published: October 2004

Electrically switchable volume holograms lead to the possiblity of real-time electro-optical control of diffractive optic components. We report here on the development of a novel photopolymer-liquid crystal composite material system for writing in a fast single step, high diffraction efficiency volume holograms, capable of switching in applied electric fields of low voltage. Switching of a first-order Bragg diffracted beam into the zero-order with an applied field of ~10 V/µm was observed. With the addition of a surfactant to our pre-polymer syrup, we observed lowering of the switching fields to ~5 V/µm. We report response times for switching and relaxation in the order of microseconds. Low voltage, high resolution scanning electron microscopy studies show that the Bragg gratings formed consist of periodic polymer dispersed liquid crystal planes. The addition of surfactant leads to formation of very uniform small (20–40 nm) nematic droplets. A simple model based on the shape of the liquid crystal droplets was applied to explain the switching fields and response times.
ELECTRON IMPACT PROCESSES IN SUPER-INTENSE LASER FIELDS
Authors: GOLOVINSKI P.A. , DOLGOPOLOV M.A. , KHLEBOSTROEV V.G.
Published: October 2004

We discuss the motion of an electron in a classical electromagnetic wave, including ponderomotive force effects. To describe electron impact stimulated reactions under the action of superstrong laser field we formulate instant-impact approximation. We demonstrate how it can be applied to calculate hard electron-nuclear processes for obtaining the reaction rates for such effects as trident pair production, hard X-ray generation, electrostimulated nuclear fission, and both ions and nuclei excitation by electron impact in the laser field.
PHOTOINDUCED MOLECULAR REORIENTATION IN POLYMERS, LANGMUIR-BLODGETT FILMSAND LIQUID CRYSTALS
Authors: BLINOV L.M.
Published: October 2004

A review of the experimental data on a photoinduced molecular reorientation in various molecular guest-host systems (dyes in liquid solutions, liquid crystals and polymer matrices), side-chain polymers and Langmuir-Blodgett films (LBFs) containing light absorbing chromophores is presented. The photoorientation may be reversible or irreversible. It is accompanied by the photoinduced dichroism and optical anisotropy which is widely used for optical recording information. Special attention is paid to the photoassisted poling of polymers and LBFs, a novel technique that allows for the preparation of the stable photoelectrets at room temperature possessing very promising nonlinear optical properties. The physical mechanisms of the photoinduced molecular reorientation are discussed.
SECOND ORDER NONLINEAR OPTICAL PROPERTIES IN SILICA-BASED GLASS FILM WAVEGUIDES
Authors: HORINOUCHI S. , IMAI H. , YAMASAKI H. , FUKAO K. , ZHANG G.J. , KINOSHITA T. , MITO K. , HIRASHIMA H. , SASAKI K.
Published: October 2004

Phase-matched blue second harmonic generation was observed in a corona-poled Corning 7059 glass film waveguide. The induced quadratic optical nonlinearity was examined by second harmonic generation with a time dependent decay for multi-complex of SiO 2, BaO,B 2 O 3 and/or Al 2 O 3. Glass films with every possible combination of composition were fabricated and examined, The glass composition of SiO 2- BaO-B 2 O 3 and/or SiO 2- BaO-Al 2 O 3 was found to play effective roles in maintaining the induced second order nonlinearity for a longer period of time. This is supposed to be related to distributed traps which come from complex of the glass components.
BELOW BAND-GAP NONLINEAR OPTICAL PROPERTIES OF SEMICONDUCTOR-DOPED GLASSES
Authors: BANFI G.P. , DEGIORGIO V. , FORTUSINI D. , TAN H.M.
Published: October 2004

Through nonlinear transmission and wave-mixing measurements. combined with structural data from neutron scattering, we obtain the below band-gap third-order susceptibility χ(3) (both imaginary and real part) and the refractive-index-change per carrier of semiconductor nanocrystals embedded in a glass matrix. Our data covers a range of crystal radii between 2 and 14 nm, and a range of ratios y=Eg /(ħω), where Eg is the energy gap of the semiconductor and ħω is the energy of the incident photon, between 1.1 and 1.9. The magnitude of χ(3) and its dependence on y are comparable to those of related bulk semiconductors.
METAL NANOCLUSTER FORMATION BY ION IMPLANTATION IN SILICATE GLASSES: NONLINEAR OPTICAL APPLICATIONS
Authors: MAZZOLDI P. , ARNOLD G.W. , BATTAGLIN G. , GONELLA F. , HAGLUND R.F.
Published: October 2004

Implantation of metal ions (e.g., silver, copper, gold, lead) in glass substrates leads under certain circumstances to the formation of nanometer-radius colloidal particles in a thin surface layer. These particles exhibit an electron plasmon resonance which depends on the optical constants of the implanted metal and on the refractive index of the glass host. The nonlinear optical properties of such colloids, in particular the enhancement of optical Kerr susceptibility by both dielectric and quantum-confinement effects, suggest that the ion implantation technique may play an important role for the production of all-optical switching devices. A review of the state-of-the-art of the research in this field will be presented from the perspective of the nonlinear optical properties of ion-implanted glasses.
NONLINEAR OPTICAL STUDIES OF BACTERIORHODOPSIN
Authors: RAO D.V.G.L.N. , ARANDA F.J. , CHEN Z. , AKKARA J.A. , KAPLAN D.L. , NAKASHIMA M.
Published: October 2004

We report interesting results on nonlinear optics at low powers in bacteriorhodopsin films with applications in all-optical switching and modulation. Chemically stabilized films of bacteriorhodopsin in a polymer matrix for which the lifetime of the excited M state is 3 to 4 orders of magnitude longer than that of water solutions of wild-type bR were used in these experiments. Due to the sensitivity of the films, very small powers of order microwatts are required for optical phase conjugation. The influence of the fast photochemical M to B transition induced by blue light on the saturation intensity, phase conjugate intensity and switching time was established. We also report our measurements of the intensity dependence of the self-focusing and self-defocusing properties of wild-type bR in water solution using the Z-scan technique with low power cw lasers at two wavelengths on either side of the absorption band. Our measurements indicate that the sign of the nonlinearity depends on the wavelength and the magnitude depends on the fluence of the incident laser beam. The observed self-focusing and defocusing is not due to the intrinsic electronic nonlinearity. The observations can be explained in terms of the Kramers-Kronig dispersion relation that relates the real and imaginary parts of the complex index of refraction.
THREE-DIMENSIONAL SIMULATIONS OF STIMULATED BRILLOUIN SCATTERING WITH FOCUSED GAUSSIAN BEAMS
Authors: MOORE T.R. , BOYD R.W.
Published: October 2004

We report on a detailed investigation of the process of SBS with focused Gaussian beams via a three-dimensional simulation of the SBS process that includes spontaneous noise. We show that spontaneous noise present at points other than where the initiation of SBS occurs does not significantly affect the Stokes wave. The effects on the Stokes beam of modes not present in the pump wave (nonconjugate modes) are investigated and it is found that the phase of a given Stokes mode is affected by the presence of other modes, a process termed phase pulling. We also show that for a focused Gaussian beam the Brillouin gain parameter does not increase linearly with increased pump power once SBS threshold is reached; rather, above threshold the SBS process resembles a reverse saturable absorber for the pump wave at any point. between the entrance to the medium and the focal point of the pump beam.
POLING PROPERTIES OF DOPED FILMS OF TRANSPARENT NITROPHENYLTRIAZOLE IN GLASSY POLYMER
Authors: CHENG YE , ZHIMING FENG , YINGXU XIANG , RUBIN XIN , FENG JIN
Published: October 2004

DMNPTAz is a newly developed blue-light transparent nonlinear optical material. Poling properties of doped films of DMNPTAz in PSt and PMMA were investigated with electrochromism and waveguiding refractive index measurements, respectively.
ULTRA-SHORT PULSE NONLINEAR OPTICS: SECOND HARMONIC GENERATION AND SUM FREQUENCY GENERATION WITHOUT GROUP VELOCITY MISMATCH BROADENING
Authors: BAND Y.B. , TRIPPENBACH M. , RADZEWICZ C. , KRASINSKI J.S.
Published: October 2004

The propagation of short pulses in nonisotropic nonlinear optical media involves new phenomena not encountered in the propagation of longer pulses. We describe two such phenomena here. Specifically, (a) we demonstrate a new method of nonlinear frequency generation for femtosecond light pulses that alleviates group velocity mismatch broad-ening in the generation of second harmonic pulses that are shorter than the input fundamental pulses. The method relies on non-collinear phase-matching and group-velocity-matching. Using our method, we generated 28 fs second harmonic pulses from 33 fs 800 nm fundamental pulses. (b) We show that an optical wavepacket propagating as an extraordinary wave in a non-isotropic dispersive medium experiences a rotation (or tilt) about an axis perpendicular to the propagation vector. We measured the tilting of a femtosecond laser wavepacket in a birefringent rutile crystal. The measurements were carried out using a linear interferometric technique which, in contrast to nonlinear correlation techniques, allows measurement at very low power. A 23 fs delay between the left and right parts of a 30 fs, 800 nm wavepacket was measured for a 1 mm thick rutile crystal.
FOUR WAVE MIXING OBSERVATION OF A SATELLITE IN THE Na-Xe NON-IMPACT COLLISIONAL LINESHAPE
Authors: VAYNBERG B. , MATUSOVSKY M. , ROSENBLUH M.
Published: October 2004

Degenerate four-wave mixing in sodium vapor in the presence of a noble gas is measured and calculated for large detunings from resonance, where the collisional impact approximation is no longer applicable. The measurement thus probes the non-impact collisional potential of the Na-noble gas system. When the noble gas is Xe, and the detuning is to the red of the Na D 1 resonance, an avoided crossing between the quasi-molecular potentials results in a satellite in the absorption lineshape, which can be detected in the four wave mixing signal. We calculate collisional lineshapes with several available sets of Na-Xe interaction potentials using the quasi-static and semi-classic line broadening theories, and find that the available potentials do not yield line shapes which agree with the measurements. The lineshape derived from the measured degenerate four wave mixing signal shows good agreement with theoretical calculations, only if the non-adiabatic nature of the level crossing is considered. Based on our experimental lineshape and a non-adiabatic level crossing theory, we derive corrections to the Na-Xe potentials, near the level crossing, that is for interatomic separations in the range of 0.55–0.75 nm.
DISTANCE MEASUREMENTS USING FREQUENCY STABILIZED Nd:YAG LASERS
Authors: MAHAL VERED , ARIE ADY
Published: October 2004

Two diode-pumped tunable Nd:YAG lasers locked to sub-Doppler transitions of 127I2 and 133 Cs 2 are used as a source for two-wavelength interferometry. The synthetic wavelength, Λ=c/∆ν, is highly stable and accurate, owing to the frequency stability of the locked lasers and the precise determination of the frequency difference Δν between Cs 2 and I 2 transitions. The dense spectra of these molecules allows selection of Λ over a wide range, between 8.5 mm and several meters, thus enabling distance measurements with a large non-ambiguity range. Fringe contrast and phase-shifting methods are used to measure the phase difference. An accuracy of 70 μm is achieved for Λ~19 mm, i.e. Λ/260.
AN AIRY FUNCTION FOR THE LASER
Authors: STÉPHAN GUY
Published: October 2004

We give a general equation which allows the description of the evolution of the laser properties when the gain is varied from below to above threshold. The method is general in the context of the semi-classical theory of lasers. It is numerically illustrated in the simplest case of a single mode laser with a source term characterized by a very narrow spectrum. The transformation of the Airy line shape of the passive Fabry-Perot cavity into the laser line shape is described. A classical linewidth which complements the usual quantum limit can thus be introduced, together with its control parameters.
DOUBLE PHASE CONJUGATE MIRROR AT 1.55 μm BETWEEN SINGLE MODE FIBERS WITH CdZnTe: V
Authors: MARTEL G. , WOLFFER N. , MOISAN J.Y. , GRAVEY P.
Published: October 2004

We present experimental results of a double phase conjugate mirror (DPCM) in a crystal of Cd 0.96 Zn 0.04 Te:V operating at 1.55 μm. Elimination of conical diffraction has been obtained by cylindrical lenses and has allowed to measure a coupling efficiency between monomode fibers versus different experimental parameters. An oscillation of the diffracted beam direction at the frequency of the applied ac field has been observed. Perturbation of the grating period that satisfy the Bragg matching can be due to mechanical vibrations resulting from the piezoelectric effect. In a ring phase conjugate mirror (PCM) configuration, experimental results of the conversion efficiency and of the phase of the diffracted beam are also presented.
SUBNANOSECOND REFLECTIVITY MODULATION KINETICS IN GaAs/GaAlAs MICROCAVITIES
Authors: IEHL J.L. , GRAC R. , COLLET J.H. , PUGNET M. , BARDINAL V. , FONTAINE C. , LEGROS R.
Published: October 2004

We study the subnanosecond reflectivity kinetics of distributed Fabry-Pérot cavities composed of two GaAs/AlAs Bragg reflectors enclosing a central GaAs layer. The structure reflectivity exhibits a sharp minimum in the absorption edge of GaAs at the temperature of 300 K, around the wavelength of 885 nm. The photogeneration of an electron-hole plasma causes a shift of the cavity resonance. The switch energy and the recovery time are investigated. Switching capabilities are observed with excitation energies of few tens of μJ/cm2. We correlate the reflectivity kinetics to the plasma dynamics in the central GaAs zone of the structure, especially to the density and temperature relaxation.
BIREFRINGENCE PHASE MATCHING IN SELECTIVELY OXIDIZED GaAs/AlAs OPTICAL WAVEGUIDES FOR NONLINEAR FREQUENCY CONVERSION
Authors: FIORE A. , BERGER V. , ROSENCHER E. , LAURENT N. , VODJDANI N. , NAGLE J.
Published: October 2004

We propose using the huge birefringence available in GaAs/AlAs oxidized waveguides to phase-match nonlinear optical conversions in the near- and mid-infrared. Tunable midinfrared radiation can be obtained by difference frequency generation from two tunable near-infrared semiconductor lasers. We measured the transmission spectrum of the AlAs oxide, and demonstrated the birefringence enhancement due to oxidation in a single polarization waveguide.
A TWO-FORM DESCRIPTION OF PUSH-PULL MOLECULES: CORRELATIONS BETWEEN STRUCTURE, INTRAMOLECULAR CHARGE TRANSFER AND (HYPER) POLARIZABILITIES
Authors: BARZOUKAS M. , FORT A. , BLANCHARD-DESCE M.
Published: October 2004

We present a quantum two-form two-state description of donor-acceptor molecules. We single out relevant factors that are characteristic of the molecule and its environment. In addition, we define a parameter which rules the geometry of both ground and excited states. Also, this parameter is proportional to the change in dipole between excited and ground states. We show that correlations between (hyper)polarizabilities and this parameter reproduce remarkably well semi-empirical predictions. We extend this model in order to account for the solvent reaction field. This model helps in the understanding of the dependencies of (hyper)polarizabilities on solvent polarity.
TWO-PHOTON ABSORPTION AND OPTICAL-LIMITING PROPERTIES IN DIMETHYLAMINOCYANOBIPHENYL CRYSTAL
Authors: FENEYROU P. , DOCLOT O. , BLOCK D. , BALDECK P.L. , ZYSS J.
Published: October 2004

Dimethylaminocyanobiphenyl (DMACB) has been synthesized in view of nonlinear optical applications in the visible. In this communication, we report the strong nonlinear absorption of DMACB crystal in its noncentrosymmetric form which could be useful for optical-limiting applications in the visible. The transmitted intensity of a 230 μm thick crystal was measured at λ=532 nm as a function of beam intensity and polarization. For light polarized parallel to the long molecular axis, the nonlinear absorption coefficient is 130±40 cm GW −1. Various hypothesis to explain this value are discussed.
NONLINEAR LASER SPECTROSCOPY OF NONLINEAR SOLVATION
Authors: FAINBERG B.D. , ZOLOTOV B. , HUPPERT D.
Published: October 2004

In this study we show that the transient four-photon spectroscopy with pulses longer than the electronic transition dephasing can be used for nonlinear solvation study, i.e., when the linear response for the solvation dynamics breaks down. We have obtained new formulae describing the time evolution of the moments of the nonlinear optical spectra and, in particular, the time resolved fluorescence in the case of nonlinear solvation.
SHORT DISTANCE APPLICATIONS OF QUANTUM CRYPTOGRAPHY
Authors: HUTTNER BRUNO , IMOTO NOBUYUKI , BARNETT STEVE M.
Published: October 2004

We present an identification protocol based on quantum mechanics. The first user, Alice, needs to identify herself in front of a second user, Bob, by means of a password, known only to both. The safety requirement for Alice is that somebody impersonating Bob, who only pretended to know Alice’s password, shall not be able to obtain information on the password from the exchange. This is an example of a potentially practical new application of quantum mechanics to cryptography.
FREE ATOM IN STRONG AMPLITUDE-MODULATED LIGHT
Authors: BURSHTEIN A.I. , SIVACHENKO A.YU.
Published: October 2004

The population and phase relaxation in TLS induced by resonant radiation with stochastic amplitude was studied within the framework of sudden modulation theory. Kinetics and stationary light absorption as well as resonance fluorescence were calculated for light with complex and real amplitude. Although the latter is a very popular model of the former, it was shown to be inappropriate at strong interaction. The real (Rayleigh) light has complex amplitude random in magnitude and phase and changing in time as a Markovian chain, correlated or non-correlated. With respect to atom response to light of medium power, the analytically studied non-correlated field was shown to be similar to strongly correlated, “stochastic” field opened to only numerical inspection.
QUANTUM NOISE REDUCTION IN LASERS
Authors: GIACOBINO E. , MARIN F. , BRAMATI A. , JOST V.
Published: October 2004

The intensity noise of semiconductor lasers was brought below shot noise by about 30% using constant current supply together with line narrowing techniques. This result is shown to be in good agreement with theoretical predictions of a laser theory including regulated pumping. The latter theory is applied to the case of Nd:YVO 4 microlasers pumped by the sub-shot noise semiconductor lasers.
ON THE PUMP INTENSITY DEPENDENCE OF PROBE NOISE, ABSORPTION AND DISPERSION IN A DRIVEN TWO-LEVEL SYSTEM AT POINTS OF ZERO ABSORPTION AND IN THE DEAD-ZONE
Authors: ROSENHOUSE-DANTSKER A. , WILSON-GORDON A.D. , FRIEDMANN H.
Published: October 2004

We investigate the quantum noise gained by a weak probe laser interacting with a driven two-level system at points of zero absorption and in the dead-zone. We find that in the Doppler-limit, maximum noise is obtained at the extremum point of the probe dispersion curve as a function of the pump intensity. This implies that in this limit, the noise is maximal at the transition point between focusing and defocusing. On the other hand, in the absence of Doppler broadening, this is true only for the case of a resonant pump.
ATOMIC VELOCITY SELECTION BY INTERFERENCE IN TWO-PHOTON IONIZATION
Authors: GARREAU J.C. , WILKOWSKI D. , HENNEQUIN D. , ZEHNLÉ V.
Published: October 2004

This paper discusses a new scheme for generating quantum coherence between different degrees of freedom of an atom interacting with two modes of the electromagnetic field. The presence of quantum interference in a two-photon coupling between the ground state of the atom and the continuum through two quasi-resonant intermediate states induces selective ionization of the atoms for particular combinations of the different parameters characterizing the degrees of freedom of the system, leading to quantum coherence between the internal state, the center-of-mass motion of the atom, and the electromagnetic field. The application of this method to the selection of an atomic velocity class is discussed.
Effects of yo-yo diet, caloric restriction, and olestra on tissue distribution of hexachlorobenzene
Authors: Jandacek Ronald J. , Anderson Nicole , Liu Min , Zheng Shuqin , Yang Qing , Tso Patrick
Published: October 2004

Chlorinated hydrocarbons are lipophilic, toxic, and persistent in the environment and animal tissues. They enter the body in food and are stored in adipose tissue. Loss of body fat through caloric restriction mobilizes stored lipophilic xenobiotics and results in distribution to other tissues. We have studied the reversibility of this process in mice that followed a regimen of body weight cycling. Weight gain was followed by weight loss, a second gain, and a second loss (“yo-yo diet regimen”). We measured the distribution of orally gavaged [14C]hexachlorobenzene, which is sparingly metabolized. We found that weight cycling has different effects in different organs. Continued weight loss resulted in a threefold increase of14C amount and concentration in the brain. After weight regain,14C in the brain decreased but then increased again after a second weight loss. Weight loss resulted in an increase in the concentration of14C in adipose tissue without changing the total amount in that tissue. Weight loss and regain resulted in an increase of14C in the liver, which reflected an increase of fat in the liver. The regimen of weight gain and loss was repeated in mice gavaged with [14C]hexachlorobenzene, with one group receiving the nonabsorbable fat olestra in the diet. Combined dietary olestra and caloric restriction caused a 30-fold increase in the rate of excretion of14C relative to an ad libitum diet or a reduced caloric diet alone. Distribution of14C into the brain resulting from the restricted diet was reduced by 50% by dietary olestra.
cTnT1, a cardiac troponin T isoform, decreases myofilament tension and affects the left ventricular pressure waveform
Authors: Nassar Rashid , Malouf Nadia N. , Mao Lan , Rockman Howard A. , Oakeley Annette E. , Frye James R. , Herlong J. René , Sanders Stephen P. , Anderson Page A. W.
Published: October 2004

Four isoforms of cardiac troponin T (cTnT), a protein essential for calcium-dependent myocardial force development, are expressed in the human; they differ in charge and length. Their expression is regulated developmentally and is affected by disease states. Human cTnT (hcTnT) isoform effects have been examined in reconstituted myofilaments. In this study, we evaluated the modulatory effects of overexpressing one cTnT isoform on in vitro and in vivo myocardial function. A hcTnT isoform, hcTnT1, expressed during development and in heart disease but not in the normal adult heart, was expressed in transgenic (TG) mice (1–30% of total cTnT). Maximal active tension measured in skinned myocardium decreased as a function of relative hcTnT1expression. The pCa at half-maximal force development, Hill coefficient, and rate of redevelopment of force did not change significantly with hcTnT1expression. In vivo maximum rates of rise and fall of left ventricular pressure decreased, and the half-time of isovolumic relaxation increased, with hcTnT1expression. Substituting total cTnT charge for hcTnT1expression resulted in similar conclusions. Morphometric analysis and electron microscopy revealed no differences between wild-type (non-TG) and TG myocardium. No differences in isoform expression of tropomyosin, myosin heavy chain, essential and regulatory myosin light chains (MLC), TnI, or in posttranslational modifications of mouse cTnT, cTnI, or regulatory MLC were observed. These results support the hypothesis that cTnT isoform amino-terminal differences affect myofilament function and suggest that hcTnT1expression levels present during human development and in human heart disease can affect in vivo ventricular function.