bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular and subcellular localization of annexin IV in rabbit intestinal epithelium, pancreas and liver
Authors: Massey Dominique , Traverso Valérie , Rigal Alain , Maroux Suzanne
Published: February 2003

Summry— The results of immunoblot analysis performed with a specific monoclonal antibody showed that the intestinal mucosa, pancreas and liver are privileged tissues for the expression of annexin IV. Immunofluorescence labelling of thin frozen sections of these tissues showed a strong concentration of annexin IV along the basolateral domain of the plasma membrane of intestinal absorbing cells, hepatocytes and pancreatic acinar cells, whereas in intestinal mucous secreting cells and centro acinar pancreatic cells, annexin IV was found to be present throughout the cytoplasm.
Identification of the eleocytes as the vitellogenin producing cells in nereids
Authors: Bonnier Patrick , Porchet‐Hennere Eliane , Baert Jean‐Luc
Published: February 2003

Summry— Coelomocytes of Nereis diversicolor synthesize and secrete vitellogenin in vitro. Using a monoclonal antibody which specifically recognized vitellogenin, we showed by immunocytochemistry that among the coelomocytes only a subpopulation, called eleocytes, countained vitellogenin. These results assert that eleocytes are the vitellogenin producing cells in nereids.
Three‐dimensional analysis demonstrates the presence of exocrine cytoplasmic vela between endocrine cells and basal lamina in the stomach of mammals
Authors: Pradal Gilbert , Piloquet Philippe , Vo Ngoc Huong , Lefranc Gérard
Published: February 2003

Summary— Three‐dimensional analysis demonstrated the presence of cytoplasmic vela extending from exocrine cells into the space between endocrine cells and basal lamina in the gastrointestinal epithelium of the rabbit; these structures were also observed in various other mammals. The following techniques were used to determine the morphologic characteristics of these vela and to study their significance: preparation of semiserial thin sections, three‐dimensional reconstruction in plexiglass and lanthanum staining of pericellular spaces. It was found that these fine vela, devoid of major differentiated cell‐constituents, sometimes form a pseudocircular crown at the base of endocrine cells. If the zone of basal apposition of the plasma membrane is referred to as ZBA and the zones of lateral apposition as ZLA, the presence of this velum makes it possible to distinguish a zone of immediate apposition without interposition (ZIA) and a mediate zone of apposition with interposition (ZMA) within the ZBA. Exocrine cell processes can also penetrate within endocrine cells in invaginations, and the depth of these invaginations can be demonstrated by lanthanum staining. Adjacent to the membrane zones defined above, other cytoplasmic microdomains‐M(ZLA) and M(ZBA), as well as M(ZIA) and M(ZMA) of different morphofunctional significance may also be envisaged.
A baseline study of the diversity and community ecology of crab and molluscan macrofauna in the Sematan mangrove forest, Sarawak, Malaysia
Authors: Ashton Elizabeth C. , Macintosh Donald J. , Hogarth Peter J.
Published: February 2003

Baseline ecological studies of pristine mangroves are important for monitoring, management and conservation of mangrove ecosystems. Diversity, density, biomass and community structure of crab and molluscan macrofauna were studied in a near-pristine mangrove forest in Sematan, Sarawak. In each of the nine 100-m2 plots, six 15-min catching periods were used to collect crabs and three 1-m2 quadrats were sampled for molluscan epifauna. Environmental variables and vegetation were also recorded in each 100-m2 plot. Thirty-one crab species and 44 molluscan species were recorded, including a few species not previously reported from Sarawak. Crab community structure was correlated with topographical height and surface water pH and salinity. Gastropod community structure was correlated with redox potential of water at depth, topographical height, surface water pH and leaf litter. Crab community structure and species number were positively correlated with tree and seedling community structure and diversity, suggesting that the mangrove vegetation is important to the crab fauna as a habitat and food supply. Molluscan abundance was positively correlated with sapling diversity and negatively correlated with the numbers of mangrove associates and tree species. The young leaves on mangrove saplings may provide a better food source than those on mature trees or mangrove associates. The data from this study provide a valuable baseline for future use at this site and for comparison with more degraded mangrove habitats elsewhere in South-East Asia.
The importance of occasional droughts for afroalpine landscape ecology
Authors: Wesche Karsten
Published: February 2003

The paper presents climatic and plant ecological data for unusually severe dry-season conditions on Mt. Elgon (Uganda/Kenya) and the Bale Mountains (Ethiopia). There is clear evidence that plants are exposed to desiccation stress during high-altitude droughts, which occur on average every 7-10 y in the study sites. Although high vapour-pressure deficits and consequently high potential evapotranspiration led to conspicuous wilting of several plant species, no lethal damage was observed and plant communities maintained increased flowering activity under drought conditions. Moreover, highest outposts of ericaceous vegetation were regularly found on thin soil covering rocky outcrops, where water stress apparently is high. Probably more important than direct water stress are the extensive fires occurring under drought conditions, which cause large-scale replacement of woody vegetation by grasslands. Additional consequences of drought include adverse conditions for seedling stablishment.
Risks in space
Authors: WOLFENDALE ARNOLD
Published: February 2003

The human species is beset by ‘risks’; one of which is related to its exposed position on the Earth as it travels through cosmic space. An examination is made of the major risks – those associated with cometary impact, with solar emissions and with the explosions of nearby stars. Estimates are given of the risks associated with trying to avoid the effect of these phenomena. Not surprisingly it is concluded that more work is necessary.
Transparency, accountability and inclusivity are not going to solve all our problems in handling risk
Authors: BURKE DEREK
Published: February 2003

Over the last few years, the regulatory system for GM foods and crops in Europe has ground to a halt because of the difficulty in reaching agreement. Regulators, in struggling to overcome the distrust and suspicion that has greeted GM soya in particular, have introduced a new mantra: transparency, accountability and inclusivity. I argue in this paper that this mantra, although a considerable advance on what has gone before, will not solve all our problems; basically, because such procedures can only partially deal with the loss of trust and the climate of suspicion in which we now working. Some suggestions are made as to what we should do next.
Demonstrating the destruction of the habitat of the Cape Sable seaside sparrow (Ammodramus maritimus mirabilis)
Authors: Jenkins Clinton N. , Powell Robert D. , Bass Oron L. , Pimm Stuart L.
Published: February 2003

The Cape Sable seaside sparrow (Ammodramus maritimus mirabilis) is Federally protected under the Endangered Species Act of the United States of America. This legislation prohibits direct or indirect take ‐ the killing or harming ‐ of the protected species. In 1993 and 1995, the opening of floodgates into Everglades National Park during the normal dry season resulted in a direct take of the sparrow. The argument was also made that there was indirect take through destruction of the habitat upon which the sparrow depends. Using a combination of fieldwork and satellite image analysis, we show that the floods did damage to the habitat of the sparrow. Moreover, they did so for a period longer than the actual flooding, further increasing the sparrow's extinction risk. Recovery of the sparrow population to pre‐flood levels will require an adequate and stable amount of habitat. We now have a technique for monitoring that habitat and ensuring that poor water management does not threaten it. More broadly, this technique has the potential for monitoring the habitat of many other species and avoiding another situation such as the sparrow faces.
Microhabitat‐specific early‐larval survival of the maritime ringlet (Coenonympha tullia nipisiquit)
Authors: Sei Makiri , Porter Adam H.
Published: February 2003

Maritime ringlet butterflies (Coenonympha tullia nipisiquit McDunnough) are rare, endangered salt marsh butterflies with larvae that survive periodic tidal submergence. Only six disjunct populations are known to exist. First‐instar larvae were released and monitored in seven microhabitats within a salt marsh in Bathurst, New Brunswick, Canada. From resighting data, microhabitat‐specific daily death rates were estimated with maximum likelihood. The survival of the larvae released in groups was compared by calculating minimum number of larvae known to be alive (MNKA). Death rates were low in microhabitats with the larval host plant, salt meadow cordgrass (Spartina patens (Aiton) Muhl.) and the major nectar source, sea lavender (Limonium carolinianum (Walter) Britton), a habitat with a moderate frequency of flooding. Because microhabitats have a large effect on the survival rate of young larvae, use of microhabitat profiles in salt marshes as habitat‐quality indices is recommended in critical‐habitat assessment and reintroduction efforts.
Pressure coefficient of thermoelectric power of platinum/platinum−10% rhodium and Chromel/Alumel thermocouples
Authors: Cheng V. M. , Allen P. C. , Lazarus D.
Published: February 2003

A differential measurement between two thermocouples of the same type, one under hydrostatic pressure and the other at zero pressure, was undertaken at temperatures up to 950 °C and pressures to 2 kbar, for platinum/platinum−10% rhodium (P/P10R) and Chromel/Alumel (C/A) couples, using an externally heated pressure cell. The correction term for P/P10R rises monotonically and levels off to a value of −0.44±0.02 °C/kbar at 800 °C. The correction term for C/A is in the opposite sense: it remains less than 0.1°C/kbar up to 450 °C where it begins to rise, eventually reaching 0.42±0.02 °C/kbar at 950 °C.
Optical pumping and tunable laser spectroscopy of the ν2 band of D2O
Authors: Keilmann F. , Sheffield R. L. , Leite J. R. R. , Feld M. S. , Javan A.
Published: February 2003

Absorption resonances in the ν2 band of D2O in near coincidence with CO2 laser lines are reported and assigned. Optical pumping induces strong laser emission at new submillimeter wavelengths, confirming the assignments. Acousto−optic modulation is used to tune the R (22) line of the CO2 laser into coincidence with the 000,533−010,422 D2O transition. Its center frequency is 1079.8628 cm−1; the linewidth (HWHM) due to collisional broadening is 13 MHz/Torr. D2S and HDS transitions in near coincidence with CO2 laser lines are also reported.
Hollow hydrogen spheres for laser-fusion targets
Authors: Foster C. A. , Hendricks C. D. , Turnbull R. J.
Published: February 2003

Many laser fusion experiments require the use of hollow spherical shells of hydrogen (deuterium-tritium mixture) as targets. We have produced hollow particles of normal hydrogen in preparation for producing shells of the various hydrogen isotopes and controlled mixtures of these isotopes. The hollow spheres were produced by ultrasonically nucleating bubbles in superheated liquid drops of hydrogen. Evaporation into the bubble increased its size and produced the shells.
High-pressure chemical waveguide laser
Authors: Poehler T. O. , Walker R. E. , Leight J. W.
Published: February 2003

The exothermic chain reactions between deuterium and fluorine have been used to produce laser emission from carbon dioxide in a high-pressure chemical waveguide laser. Chemical chain reactions initiated by flash photolysis of this system produced 10.6-μm radiation from a 3-mm-diam laser tube having an effective length of 50 cm. Lasing occurs in stable D2-F2-CO2-He mixtures at pressures as high as 1 atm with peak power of 2.5 kW for pulses of 20-μsec duration.
New anodic native oxide of GaAs with improved dielectric and interface properties
Authors: Hasegawa Hideki , Forward Kevin E. , Hartnagel Hans L.
Published: February 2003

A new method of forming an anodic native oxide of GaAs with excellent dielectric and interface properties is described. The oxide is grown in a very stable and reproducible manner in an electrolyte which is a suitable mixture of (i) water, (ii) weak carboxylic acid (tartaric or citric acid), and (iii) polyhydric alcohol. The breakdown field strength of the as-grown oxide is 5×106 V/cm and the specific resistivity is 1014–1016 Ω cm. Relatively low temperature annealing in hydrogen results in greatly improved interface properties with a density of fast interface states near midgap of 1–2×1011 cm−2 eV−1, with only a small capacitance/voltage hysteresis, and only small frequency dispersion of capacitance in the accumulation region.
Recrystallization processes in polycrystalline silicon
Authors: Ouwens C. Daey , Heijligers H.
Published: February 2003

Recrystallization processes in polycrystalline silicon made by a chemical vapor deposition technique have been investigated. Primary recrystallization has been observed between 1150 and 1250 °C, secondary recrystallization occurred above 1350 °C. By this procedure, grains of about 100 μm have been obtained. Recrystallized silicon can in principle be used as a substrate for making relatively inexpensive solar cells.
Epitaxial crystalline films of the metallic polymer (SN)x
Authors: Bright A. A. , Cohen Marshall J. , Garito A. F. , Heeger A. J. , Mikulski C. M. , MacDiarmid A. G.
Published: February 2003

The achievement of fully oriented epitaxial films of polymeric sulfur nitride is reported together with initial results on their optical and transport properties. Oriented epitaxial thin films of (SN)x have been grown on various substrates including Mylar, Teflon, and polyethylene.
New Bi phase transition near 300 kbar and 298 °K
Authors: Homan C. G. , Davidson T. E. , Kendall D. P.
Published: February 2003

Resistometric measurements were made on Bi to pressures in excess of 300 kbar. Reproducible resistance drops were observed at a pressure near 300 kbar. The related transition has been identified as the Bi VI-IX transition.
Determination of saturated electron velocity in GaAs
Authors: Kramer B. , Mircea A.
Published: February 2003

The saturated electron velocity in GaAs is determined at 100 and 150 °C from a comparison of measured and calculated small-signal impedance of IMPATT devices. The results are in good agreement with the values obtained by extrapolating Gunn effect theoretical calculations at higher fields, while the values used in previously published IMPATT design work were too high.
Effective absorption for thermal blooming due to aerosols
Authors: Chan C. H.
Published: February 2003

Thermal blooming on laser propagation due to the presence of aerosol particles is considered. Emphasis is placed on the derivation of an effective absorption coefficient αeff(t), where αeff(t) corresponds to that part of aerosol absorption which heats up the air only. Becuase of the small but nonvanishing heat capacity of the aerosol particles, air is not instantly heated resulting in a small time delay in thermal blooming.
Integrated grating-type Schottky-barrier photodetector with optical channel waveguide
Authors: Tseng Cheng-Chung , Wang Shyh
Published: February 2003

A grating-type Schottky-barrier photodetector has been incorporated within an optical channel waveguide. Silicon is used as the base material for future integration of optical and electronic components. The fabrication processes are simple and completely compatible with the standard silicon planar technology. Estimated responsivity of the detector is 0.33 μA/μW at a wavelength of 0.6328 μm with nanosecond response time.
Spectroscopic investigation of the photorefractive recording and erasure process in LiNbO3 : Fe
Authors: Kurz H. , Krätzig E.
Published: February 2003

Photoinduced currents responsible for the photorefractive process in reduced and oxidized LiNbO3 : Fe crystals have been investigated in the spectral range between 1.5 and 4.0 eV. Optical erasure has also been studied by measuring the decay of a photoinduced phase grating during illumination with incoherent light. In comparison to optical absorption these spectra yield information on energy levels of photorefractive centers.
Diffusion kinetics and optical quality in LiNbO3-LiTaO3 optical waveguides
Authors: Chin G. Y. , Ballman A. A. , Tien P. K. , Riva-Sanseverino S.
Published: February 2003

Diffusivity measurements have been made at 1000, 1100, and 1200 °C on LiNbO3-LiTaO3 single-crystal thin films prepared by melt-phase and liquid-phase epitaxy. The interdiffusion coefficient is determined to be D∼5×10−7 exp[−40(kcal/mol)/RT] cm2 sec−1. In addition, we found substantial reduction in opitcal scattering after a diffusion anneal.
GaAs electro-optic channel-waveguide modulator
Authors: Campbell J. C. , Blum F. A. , Shaw D. W.
Published: February 2003

We describe a GaAs electro-optic channel waveguide which can be used as a high-speed modulator with a potential bandwidth of 1 GHz. A narrow Schottky-barrier strip permits beam trapping to be controlled by an applied voltage. Ninety-five percent amplitude modulation has been obtained with a minimum bandwidth of 150 MHz and a power requirement of <300 μW/MHz.
Birefringence in silicon monoxide films used for aligning liquid crystal layers
Authors: Crossland W. A.
Published: February 2003

Obliquely evaporated thin films of silicon monoxide are widely used to align nematic liquid crystal layers in electro-optic devices, but the mechanism of this alignment is incompletely understood. This letter reports that such films exhibit birefringence, despite the basically amorphous structure of SiO. The nature of the birefringence appears to be related to the manner in which the films align the nematic director. It is suggested that the phenomenon may be due to form birefringence caused by anisotropic morphology in the films.
AES analysis of sodium in a corroded bioglass using a low-temperature technique
Authors: Pantano Jr. C. G. , Dove D. B. , Onoda Jr. G. Y.
Published: February 2003

Measurements have been made of sodium compositional profiles at a glass surface using Auger electron spectroscopy. It has been found that stable sodium signals may be obtained by lowering the temperature of the glass to 80 °K and by keeping the exciting electron beam current to less than 1 μA. Use of a low-energy electron flood gun had little effect on the AES measurement but was found to be valuable in reducing charging during ion bombardment of the low-temperature substrate. Observations on a glass designed for biological implant applications subjected to a simulated biological environment exposure showed that a region leached of alkali ions formed, and a Na-, Ca-, P-rich film built up on the surface.
Positioning of relativistic superpinched beams by control of the anode return currents
Authors: Kelly J. G.
Published: February 2003

The centering of relativistic superpinched beams from large aspect ratio diodes (r/d≫1) onto small targets for studies of superpinches relies on a centering force, which is normally so weak that small diode asymmetries will cause the beam to pinch off axis. A new technique is described herein that increases the magnetic centering force by approximately a factor of 103 through control of the return current flow pattern on the anode surface. Preliminary experiments conducted on the Nereus accelerator (Vg=100 kV, Ip=50 kA, and τ=50 ns) have demonstrated that the superpinch can be reproducibly centered within 0.025 cm of the axis of a 2.54-cm-diam flat cathode.
Production of intense megavolt ion beams with a vacuum reflex discharge
Authors: Humphries S. , Sudan R. N. , Condit W. C.
Published: February 2003

Experiments have been carried out using a reflex triode-type pulsed ion accelerator at voltages up to 1.8 MeV. Large reductions in the breakdown electron current drawn by the system resulted from the electron reflexing. Diode closure was the major problem and was strongly affected by the choice of anode materials. The best results were obtained with thin aluminum foil anodes. Over a total accelerating pulse of 130 nsec peak aluminum currents in excess of 5 kA were extracted with a peak energy of Al++ of 3 MeV.
Negative electron affinity GaAs: A new source of spin-polarized electrons
Authors: Pierce D. T. , Meier F. , Zürcher P.
Published: February 2003

The spectrum of spin polarization and yield of photoelectrons from negative electron affinity GaAs were measured. The results show that GaAs is an excellent source of polarized electrons with P∼50%, high current, small energy spread, and high brightness.
Distribution of charge in electrets
Authors: Collins R. E.
Published: February 2003

Measurements are reported of the total charge and its mean position in liquid-charged FEP electrets. A new nondestructive technique has been used. The large difference in decay rates of positive and negative liquid-charged electrets is accompanied by quite different behavior of the deposited charge as it migrates through the electret. The total volume charge density present in untreated FEP has been measured: it typically amounts to 0.1–0.6 C m−3 for 25-μ-thick material.
Metallic state of Si in Si−noble−metal vapor−quenched alloys studied by Auger electron spectroscopy
Authors: Hiraki A. , Shimizu A. , Iwami M. , Narusawa T. , Komiya S.
Published: February 2003

Thin vapor−quenched films of Si−Au (Ag, Cu) alloys were studied by using Auger electron spectroscopy (AES). In these films, when the concentration of the noble metal was more than a critical value (∼70 at.%), the Si (LVV) Auger spectrum had double peaks at 90 and 95 eV; these peak energies were all the same for Si−Au, Si−Ag, and Si−Cu. However, with smaller noble−metal concentrations, the Si (LVV) spectrum was nothing but that of pure Si having a single peak at 92 eV. These results are explained by the statement that the double−peaked spectrum reflects the metallic state of Si quenched from the liquid state and some amount of metal is necessary to stabilize the metallic Si.
Surface acoustic wave planar resonator using grating reflectors
Authors: Joseph T. R. , Lakin K. M. , Penunuri D.
Published: February 2003

A surface acoustic wave resonator is described which utilizes electrically shorted gratings to form a resonant acoustic cavity where energy is introduced and removed by means of a short interdigital transducer placed in the center. Experimental results are presented for a device with two 100−finger pair gratings and a 9.5−finger pair central interdigital transducer (IDT) and compared with theoretical calculations. The device exhibits a resonant Q of 2300 at 47.55 MHz.
Frequency dependence of multiphonon infrared absorption in the transparent regime of fluorite crystals
Authors: Namjoshi Kashinath V. , Mitra Shashanka S. , Bendow Bernard , Harrington James A. , Stierwalt Don L.
Published: February 2003

The first measurements of multiphonon absorption in fluorites carried out by the technique of spectral emittance are reported. Also, the first detailed comparison of theory and experiment for multiphonon absorption in fluorites is carried out, utilizing the present as well as previous data. The results provide strong evidence of intrinsic behavior over a wide range of frequencies above the Rehstrahl in these crystals.
Highly collimated laser beams from electrically pumped SH GaAs/GaAlAs distributed−feedback lasers
Authors: Scifres D. R. , Burnham R. D. , Streifer W.
Published: February 2003

Utilizing an electrically pumped single−heterostructure GaAs/GaAlAs distributed−feedback laser diode operating in fourth order we have obtained a highly collimated laser beam which is coupled out normal to the plane of the p−n junction rather than through the cleaved end mirrors. This beam is found to have an angular divergence of 0.35° in the dimension determined by the grating and is virtually 100% polarized with the E vector parallel to the grooves of the corrugated feedback structure.
Different bonding states of Cs and O on highly photoemissive GaAs by flash−desorption experiments
Authors: Goldstein Bernard , Szostak Daniel
Published: February 2003

The thermal desorption of Cs and O from GaAs/Cs/O activated to negative electron affinity occurs as atomic Cs133 and (mostly) Ga2O. Flash−desorption experiments show that several bonding states exist for the adsorbed Cs which correlate with changes in work function. For example, (i) the Cs bonding state for GaAs/Cs changes when the Cs coverage exceeds that required for maximum photoemission, and (ii) the distribution of bonding states for Cs shifts markedly to higher energies as the GaAs surface passes from unactivated (GaAs/Cs) to activated (GaAs/Cs/O).
Measurement of the diffusion coefficient of electrons in WO3 films
Authors: Crandall Richard S. , Faughnan Brian W.
Published: February 2003

Measurements of the electron diffusion coefficient in amorphous films of tungsten oxide give a value of D=0.0025±0.0006 cm2 sec−1. D decreases by less than a factor of 2 between +40 and −20 °C.
Resonance self−absorption in CO lasers
Authors: Lacina W. B. , McAllister G. L.
Published: February 2003

Resonance self−absorption from overlapping lines in a CO laser medium may be an important pressure−dependent mechanism for theoretical analysis, with possible impact on line selection and atmospheric propagation. Certain presently unexplained discrepancies relating to transient time scale, spectral anomalies, efficiency degradation, and sensitivity to temperature might all be consistently resolved by this hypothesis.
Silicon nitride trap properties as revealed by charge−centroid measurements on MNOS devices
Authors: Arnett P. C. , Yun B. H.
Published: February 2003

Previous charge−centroid studies of MNOS devices have shown that electrons injected into the insulator structure from the silicon are trapped not solely at the dielectric interface, but can be distributed over nearly the entire nitride thickness. In this paper, results of charge−centroid measurements on thin−oxide MNOS devices are interpreted with a charge trapping model, leading to values for the nitride trap density, capture cross section, and average trapping distance of 6×1018/cm3, 5×10−13 cm2, and 35 Å, respectively.
A dispersive modulator
Authors: Loy Michael M. T.
Published: February 2003

Amplitude modulation and temporal compression of 10−μ light at a frequency up to 80 MHz were demonstrated using a dispersive molulator—a NH3 vapor cell with a near−resonant time−dependent transition frequency controlled externally via the Stark effect. The peak output intensity was observed to be higher than the input intensity, showing that compression effects due to the time−dependent dispersion are essential in determining the output waveform.
Structural defect thermoelectric power in thin copper films
Authors: Thakoor A. P. , Suri Ritu , Suri S. K. , Chopra K. L.
Published: February 2003

Thermoelectric power and electrical resistivity of thin (<1000 Å) copper films annealed at different temperatures have been studied. The data have been utilized to obtain the contribution to thermoelectric power by the structural defects in the films. This contribution is comparable in magnitude to the bulk value. It increases with film thickness giving rise to a strong thickness dependence of thermoelectric power at thicknesses considerably larger than the mean free path of the conduction electrons.
cw Raman fiber amplifier
Authors: Stone J.
Published: February 2003

cw Raman amplification has been observed in a hollow fused silica fiber, inside diameter 5 μm, 5 m long, filled with benzene. Using a krypton laser pump, amplification of the 992−cm−1 Stokes Raman line has been obtained at pump wavelengths 5682, 6471, and 7525 Å. The pump powers determined by measuring the slightly attenuated output from the fiber were 17, 25, and 17 mW, respectively. The corresponding amounts of power in the input laser pump before the launching optics were 70, 85, and 75 mW.
Metallization scheme for n−GaAs Schottky diodes incorporating sintered contacts and a W diffusion barrier
Authors: Sinha A. K.
Published: February 2003

Using Schottky barrier measurements on n−GaAs diodes metallized with Au/W and Pt/W films, we have shown that thin films of W (∼3000 Å) offer an excellent barrier to diffusion of both Au and Pt atoms at temperatures up to 500 °C. These properties of W are utilized in a Schottky barrier metallization scheme consisting of Au/W/(PtGa/PtAs2)/n−GaAs, where (a) the thin sintered Pt layer provides a large φB (due to PtAs2 at the GaAs interface) and a metallurgically stable conductor−semiconductor interface, (b) the W layer acts as a diffusion barrier, and (c) the outer Au layer provides thermocompression bondability.
Multiple storage and erasure of fixed holograms in Fe−doped LiNbO3
Authors: Staebler D. L. , Burke W. J. , Phillips W. , Amodei J. J.
Published: February 2003

Holograms were recorded and fixed simultaneously in heated (∼160°C) crystals of Fe−doped LiNbO3. With this procedure the crystals have the erase/write asymmetry required for multiple storage of high−diffraction−efficiency holograms. Five hundred fixed holograms, each with more than 2.5% diffraction efficiency, were recorded.
Optical aging characteristics of borosilicate clad fused silica core fiber optical waveguides
Authors: Camlibel I. , Pinnow D. A. , Dabby F. W.
Published: February 2003

Very low transmission loss fiber optical waveguides have been developed during the past two years which have pure fused silica cores surrounded by borosilicate glass claddings. A recent study of the binary borosilicate glass system revealed that the low refractive index values which can be achieved with this glass and which are essential for the fiber cladding application occur only when the glass is quenched. Annealing causes the refractive index to increase to a less acceptable value. Although fibers are naturally quenched during drawing, there is a legitimate concern that the cladding might spontaneously anneal at its operating temperature in an unacceptably short time. The details of the annealing time−temperature relationship are determined in the present work and effective lifetimes for borosilicate clad fibers are predicted. It is concluded that lifetimes in excess of 100 years should be expected if the fiber operating temperature does not exceed 60 °C.
Observation of laser action in CO gas excited only by fission fragments
Authors: McArthur D. A. , Tollefsrud P. B.
Published: February 2003

We report the first clear observation of laser action in a medium excited only by fission fragments. CO gas at 77 °K and pressure ≈100 Torr was excited by fission fragments from enriched 235U3O8 foils, which were irradiated with neutrons from a fast−burst reactor. The laser signal was ≳103 times the fluorescence signal, disappeared if the laser output mirror was misaligned, and had a very sharp onset and fall. The measured laser pulse energy was 10 times the maximum possible fluorescence energy.
Nonchemical HF pulse laser pumped by e−beam−sustained discharge
Authors: Osgood Jr. R. M. , Mooney D. L.
Published: February 2003

Experiments with a pulsed discharge−pumped (nonchemical) HF laser are described. The laser discharge is sustained with a cold cathode electron beam gun. An output power of 8 kW/cm2 in a 2.5−μsec pulse length is obtained. Several observations regarding the laser mechanism are made.
Theory of the dispersive modulator
Authors: Grischkowsky D. , Loy M. M. T.
Published: February 2003

The recent observations by Loy of amplitude modulation and compression of infrared laser pulses caused by passage through the dispersive modulator (a cell containing dilute NH3 vapor with a Stark−modulated resonant frequency) are explained. It is shown that there is a formal equivalence between (i) the passage of a near−resonant light beam through a vapor with a time−dependent resonant frequency, and (ii) the passage of a frequency−modulated light beam through a vapor with a constant resonant frequency. For low−intensity light this equivalence reduces the problem to the optical analog of chirp radar.
Effects of flow in aerosol measurements by laser Doppler spectroscopy and its nullification
Authors: Ben−Yosef N. , Weitz A. , Yinnon H.
Published: February 2003

It is shown that the current autocorrelation function of scattered light from aerosols situated in gas that has macroscopic motion will be strongly affected. The exact autocorrelation function for steady flow is calculated. Experimental results verify the calculated results. Using the measured results and the calculated function one can find the single−particle correlation function and the diffusion coefficient.
Amorphous semiconductor threshold on−state properties as functions of decay time, ambient temperature, and polarity
Authors: Vezzoli Gary C. , Doremus L. William , Tirellis G. G. , Walsh Peter J.
Published: February 2003

The on−state conductance and radiative emission properties of an amorphous semiconductor threshold switch have been investigated. The transient on−state conductance GT and differential conductance G̃T are found to be constant for time intervals τ of up to 120 nsec during which the voltage is below the low−frequency holding voltage but above the knee voltage. The knee voltage is the voltage at which the transient on−state current−voltage curve coalesces into the transient off−state curve in the down−voltage direction. For τ≳120 nsec, GT and G̃T vary asymptotically with time. As ambient temperature is increased from 300 to 400 °K, G̃T is observed to remain constant or increase slightly as would be expected in dGT/dT for a metal. If the on−state is assumed to have a band gap, conductance vs temperature measurements indicate that the gap would have a value less than 1.2×10−4 eV, and thus for practical purposes the gap could be considered to be essentially zero. The intensity of the nonthermal radiative emission which is observed during the on−state of a threshold event is found to be polarity dependent such that when the Nesa electrode adjacent to the detector is of positive polarity, the intensity of the emission is 25% greater than when the polarity is reversed. These observations are interpreted as indications that the on state is maintained electronically rather than thermally, in a state analogous to a metal or semimetal with a zero indirect electrical band gap but a finite direct optical gap.
Coherent selective erasure of superimposed volume holograms in LiNbO3
Authors: Huignard J. P. , Herriau J. P. , Micheron F.
Published: February 2003

Selective erasure of superimposed holograms recorded in Fe−doped LiNbO3 is reported. This process consists of photoinducing complementary refractive index changes which cancel the previously recorded changes. It can be applied to any stacked hologram in the crystal volume as well as to any part of one selected hologram; in this last case it performs the Boolean operation exclusive or.
Ferromagnetic domain structure of metallic glasses
Authors: Leamy H. J. , Ferris S. D. , Norman G. , Joy D. C. , Sherwood R. C. , Gyorgy E. M. , Chen H. S.
Published: February 2003

We have applied the scanning electron microscopy (SEM) technique of Fathers et al. to a study of domain structure in metallic glasses of the form TM0.75P0.16X0.06Al0.03, where TM denotes Fe, Co, Ni, or an alloy of these and X denotes either B, C, or Si. The domain structure is dominated by the presence of a spatially nonuniform uniaxial anisotropy which is related to the flow processes induced by quenching the molten alloy. The existence of both a magnetostrictive and a directional ordering source of anisotropy is indicated.
Depletion effects in semi−insulating GaAs
Authors: Waldrop J. R. , Zucca R. , Wen C. P.
Published: February 2003

Auger electron spectroscopy in an ultrahigh−vacuum scanning electron microscope is used to determine the potential distribution across p−i−p and n−i−n GaAs structures under dc bias conditions. The two types of specimen structures give rise to very different potential profiles. Depletion regions in the semi−insulating (SI) material at the p−i junctions are identified, an effect that disallows the application of the widely used current injection theory. The depletion effect indicates that the examined SI GaAs material has n−type behavior even though the material is purposely doped with Cr, a known acceptor.
High−power mode−locked TEA CO2 laser using an unstable resonator
Authors: Dyer P. E. , James D. J.
Published: February 2003

A passively mode−locked TEA CO2 laser has been operated with an unstable resonator, and mode−locked trains with peak powers ≳150 MW, together with near diffraction−limited beams, have been obtained. Single axial mode operation at a power level of 14 MW has also been achieved. These results represent a significant improvement over similarly dimensioned systems using stable resonators.
Multidirectional Doppler pumping: A new method to prepare an atomic beam having a large fraction of excited atoms
Authors: Gerritsen H. J. , Nienhuis G.
Published: February 2003

We discuss some problems associated with obtaining an atomic beam with a large fraction of excited−state atoms. We show, e.g., that for sodium atoms to be pumped up into the 32P1/2 state, they must experience a minimum of three optical frequencies near the D1 line. In order to achieve this with only one optical frequency, the following method is proposed: A strong laser beam impinges three times on an atomic beam, each time under a different angle, in such a way that for one velocity class the Doppler shift generates the three frequencies needed. The effects of the polarization of the laser beams are discussed.
Optical intensity modulator with three−dimensional waveguide
Authors: Uehara Shingo , Takamoto Kiichi , Matsuo Seitaro , Yamauchi Yoshiharu
Published: February 2003

A LiTaO3 optical waveguide modulator, in which a laser beam is confined in both transverse dimensions, has been fabricated. The three−dimensional waveguiding operation was achieved by using an ion−etched thin core slab and a slit metal cladding. Waveguide porperties for 0.633− and 1.15−μm laser beams and dc and rf modulation performance for a 1.15−μm beam are described.
Absorption coefficient measurements of nitrous oxide and methane at DF laser wavelengths
Authors: Deaton Terrence F. , Depatie David A. , Walker Thomas W.
Published: February 2003

The absorption coefficients for methane and nitrous oxide have been measured at 17 DF laser wavelengths in the region of 3.8 μm using a spectrophone. Concentrations of the absorbing gases very near their atmospheric concentrations were used. The absorption coefficients for the two gases at standard sea level atmospheric conditions are presented. The spectrophone device developed for this work is a differential cell which produces an equivalent absorption background signal of only 3.3×10−7 m−1/W.
Population inversion by nonadiabatic frequency chirping
Authors: Horwitz Paul
Published: February 2003

A calculation is presented of the asymptotic final state of a two−level system, initially in the ground state, in the presence of coherent constant−intensity radiation, the frequency of which is linearly swept through the resonance line. The resulting very simple formula approaches the appropriate limits in the sudden and adiabatic approximations.
Transversely pumped LNP laser performance
Authors: Otsuka Kenju , Yamada Tomoaki
Published: February 2003

We report on quaiscontinuous laser oscillation of lithium neodymium tetraphosphate of 2−mm length pumped transversely with a chopped argon laser. The room−temperature threshold was 95 mW and the slope efficiency was 3.7%. The threshold of transverse pumping was 2.5 times that of longitudinal pumping; therefore, the relative pumping efficiency was 40%.
Optically pumped vibrational transition laser in OCS
Authors: Schlossberg H. R. , Fetterman H. R.
Published: February 2003

Laser oscillation between vibrational states has been demonstrated at 19 μm in OCS by optical pumping on the ν2 overtone with a CO2 TEA laser. Analysis of the molecular kinetics indicates this technique to be general and capable of yielding many high−power (≳1000 W) laser lines below 50 μm.
Phase−matched second harmonic generation in a liquid−filled waveguide
Authors: Levine B. F. , Bethea C. G. , Logan R. A.
Published: February 2003

Phase−matched second harmonic generation in a nitrobenzene−filled waveguide has been accomplished by using a periodic electrode to modulate the nonlinear susceptibility.
Two−port cavity resonator low−insertion−loss delay line
Authors: Joseph T. R. , Lakin K. M.
Published: February 2003

A delay line is described which uses unidirectional transducers, formed by placing a short interdigital transducer (IDT) adjacent to a grating reflector, to realize low insertion losses. Theoretical and experimental results are compared for a device with 10.5 finger pair transducers and 100 finger pair gratings. The measured insertion loss was 2.5 dB at 38.14 MHz.
Transformation of the magnetic energy of a rotating relativistic beam into plasma energy
Authors: Kapetanakos C. A. , Black W. M. , Striffler C. D.
Published: February 2003

An intense rotating relativistic electron beam of energy 500 kV and current 40−50 kA is injected into neutral gas of pressure 200−700 mTorr, in the presence of an external magnetic field B0≃800 G. It is observed that the ratio of the magnetic field on axis ΔBz(r=0) to B0 is ΔBz(r=0)/B0≃2.2. The average magnetic energy density is about 2.5×1016 eV cm−3. Spectroscopic results show that most of this energy is transferred to the plasma through Joule heating.
Cadmium−diffused CuInSe2 junction diode and photovoltaic detection
Authors: Yu Phil Won , Faile S. P. , Park Y. S.
Published: February 2003

Homojunction diodes have been prepared by diffusing cadmium into p−type CuInSe2. Forward−bias electrical characteristics exhibit a I∝V3 law, indicating double carrier flow. The photovoltaic response of typical diodes has a quantum efficiency of 35−40% in the wavelength region 0.9−1.2 μ.
Fabrication of submicron polysilicon lines by conventional techniques
Authors: Nicholas K. H. , Brockman H. E. , Stemp I. J.
Published: February 2003

A new method of making fine geometry polysilicon lines has been developed. It requires no special apparatus or critical processing. Silicon gate MOST’s with dimensions of about 1 μm have been fabricated. Applications of the fine geometry MOST’s to the fabrication of high−packing−density MOSIC’s and high−frequency transistors are outlined.
New high−speed bubble garnets based on large gyromagnetic ratios (high g)
Authors: LeCraw R. C. , Blank S. L. , Vella−Coleiro G. P.
Published: February 2003

A new approach to overcoming the problem of dynamic conversion in high−mobility bubble garnets is described based on large gyromagnetic ratios (high g factors). In a film of Eu1.45Y0.45Ca1.1Fe3.9Si0.6Ge0.5O1 2, a g factor greater than 30 has been obtained, which increases the usable domain wall velocity before onset of dynamic conversion by more than an order of magnitude over comparable bubble garnet films with g approximately 2. Using a circuit period of 28.8 μm, propagation data showing no deterioration in bias margins out to 107 steps were obtained on this film at 1 and 2 MHz.
A 3400−Å p−terphenyl dye laser pumped by a CO2−laser−produced plasma
Authors: Silfvast W. T. , Wood II O. R.
Published: February 2003

Ultraviolet radiation from a xenon plasma produced with a high−pressure pulsed CO2 laser has been used to pump a 3400−Å p−terphenyl dye laser. Potential advantages of laser−porduced plasmas over electrical flashlamps as pumping sources for uv dye lasers are discussed.
Junction electroluminescence in CuInS2
Authors: Bridenbaugh P. M. , Migliorato P.
Published: February 2003

We report the first observation of homojunction electroluminescence in CuInS2. These homojunctions are made by two different annealing procedures which convert a surface layer of p−type crystals. Diodes made by low−temperature (200 °C) In−Ga diffusion show a rectification ratio of 17000:1 at 2 V and a zero bias resistance of 1×107 Ω. For diodes made by high−temperature (600 °C) annealing in InCl3 the values are 15000:1 and 3×107 Ω, respectively. Electroluminescence has been observed in diodes made by In−Ga diffusion. The spectrum peaks at 1.48 eV at 300 °K and at 1.42 eV at 77 °K. The internal quantum efficiency is 10−5 at 300 °K and 10−3 at 77 °K.
Epitaxial growth of aluminum nitride films on sapphire by reactive evaporation
Authors: Yoshida S. , Misawa S. , Itoh A.
Published: February 2003

Single−crystal films of AlN were fabricated on sapphire substrates by reactive evaporation of aluminum in ammonia gas. Films obtained have smooth and flat surfaces and there is no observed cracking. On the (0001) plane of sapphire, the c axis of AlN is aligned normal to the substrate surface, while on sapphire (011̄2), the c axis of AlN is inclined at about 28° to the film normal.
Channeling−effect study of deuteron−induced damage in Si and Ge crystals
Authors: Baeri P. , Campisano S. U. , Foti G. , Rimini E. , Davies J. A.
Published: February 2003

The disorder produced by 0.3−MeV D+ in Si and Ge at 80 °K has been analyzed in situ by 1.5−MeV D+ channeling measurements. Differences of about 10% have been found in the ψ1/2 values between the undamaged and damaged crystal. On the basis of the Lindhard continuum potential approximation, an average displacement of 0.15 Å from the row is required to explain the observed ψ1/2 decrease.
Liquid-phase-epitaxial growth of single-crystal LiNbO3 thin film
Authors: Kondo Susumu , Miyazawa Shintaro , Fushimi Shoichi , Sugii Kiyomasa
Published: February 2003

The phase equilibrium of the LiVO3-LiNbO3 pseudobinary system has been investigated, and a LiNbO3 single-crystal thin film has been grown epitaxially onto the substrate by dipping a c-plate LiTaO3 substrate into a LiVO3 flux solution. An x-ray rocking curve indicated that the film had a high single crystallinity with good epitaxy. The composition ratio Li/Nb of the film was estimated to be close to the stoichiometric value Li/Nb≈1.0.
Surface stress and the normal mode of vibration of thin crystals :GaAs
Authors: Lagowski J. , Gatos H. C. , Sproles E. S.
Published: February 2003

The normal mode of vibration of (111) GaAs wafers with a thickness below about 15 μm was found to depend strongly on the surface preparation and on the ambient atmosphere. This dependence was attributed to effects directly related to the surface stress σs. It was shown that σs can be evaluated from the natural frequency of vibration. The values of σs, in the 〈110〉 direction, for etched and unetched (111) GaAs wafers in room atmosphere were found to be 325 and 570 dyn/cm, respectively. It was further demonstrated that surface stress transients due to the adsorption processes (adsorption transients) can be determined by corresponding changes in the natural frequency of vibration.
Extension of absolute frequency measurements to 148 THz: Frequencies of the 2.0- and 3.5-μm Xe laser
Authors: Jennings D. A. , Petersen F. R. , Evenson K. M.
Published: February 2003

Absolute infrared frequency measurement has been extended to 148 THz (the highest frequency ever directly measured) with measurement of the two strong cw laser lines of Xe. The frequencies were synthesized with stabilized CO2 and 3.39-μm He-Ne lasers and mixed on a W-Ni point-contact diode. The measured frequencies are νXe(2.0μm)=147.915 850(15) THz and νXe(3.5μm)=85.459 997(3) THz.
GaAs-AlGaAs double heterostructure lasers with taper-coupled passive waveguides
Authors: Reinhart F. K. , Logan R. A.
Published: February 2003

Taper-coupled laser structures suitable for integrated optics applications were grown by a liquid phase epitaxy process. Reduced threshold current densities, j0=6.3 kA/cm2 μm, and external differential quantum efficiencies ηd as high as 28% were measured with nominally undoped n-type active layers. Control units yielded j0=5.3 kA/cm2 μm with ηd as high as 37%. An internal quantum efficiency of 78% and a taper coupling efficiency ≳50% are deduced from the data.