bluuebunny/crossref_metadata_2025 huggingface dataset:
Weight loss with sibutramine improves glycaemic control and other metabolic parameters in obese patients with type 2 diabetes mellitus
Authors: Fujioka K. , Seaton T. B. , Rowe E. , Jelinek C. A. , Raskin P. , Lebovitz H. E. , Weinstein S. P. , Group The Sibutramine/Diabetes Clinical Study
Published: July 2002

Aim: To determine the efficacy and tolerability of sibutramine hydrochloride in obese patients whose type 2 diabetes was poorly controlled on diet alone or with an oral antidiabetic agent

Methods: This study was a 24‐week, double‐blind, multicentre trial following a 5‐week placebo run‐in period. One hundred and seventy‐five obese (body mass index (b.m.i.) ≥27 kg/m2) patients with poorly controlled type 2 diabetes mellitus were randomized either to sibutramine (n = 89; mean age 53.5 years; mean weight 99.3 kg) or placebo (n = 86; mean age 55 years; mean weight 98.2 kg) at 16 participating centres. To achieve moderate calorie restriction (deficit ≥ 250–500 kcal/day), individual dietary counselling was accompanied by either placebo or sibutramine (initial dosage of 5 mg/day titrated up by 5 mg biweekly through week 6, and maintained at 20 mg through week 24). The main outcome measures included changes in weight, b.m.i., waist and hip circumference, glycaemic control, lipid profile, and quality of life, and evaluation of reported adverse events.

Results: Sixty‐seven per cent of sibutramine patients and 71% of placebo patients completed the study. At week 24 when comparing those who completed the course, sibutramine compared with placebo patients showed significantly greater (p < 0.001) absolute (−4.3 vs. −0.4 kg) and percentage (−4.5% vs. −0.5%) weight loss. Weight loss ≥5% or 10% was achieved by 33% and 8% of sibutramine patients, respectively, but no placebo patients (p < 0.03 or better). Improvement in glycaemic control was correlated with weight loss (p < 0.001). In 5% and 10% weight‐loss responders, mean treatment differences were −0.53% and −1.65% (p ≤ 0.05), respectively, for HbA1c, and −1.4 mmol/l (p ≤0.05) and −3.8 (p ≤0.05) mmol/l for fasting plasma glucose. Sibutramine patients also showed improvements in fasting insulin, triglycerides, HDL cholesterol, and quality‐of‐life assessments. Overall, sibutramine was well tolerated compared with the placebo. Sibutramine treatment was associated with small mean increases in blood pressure (BP) and pulse, although an increase in BP was not seen in sibutramine‐treated patients who lost ≥ 5% of their weight.

Conclusions: Sibutramine produced statistically and clinically significant weight loss when used in combination with recommendations for moderate caloric restriction. This weight loss was associated with improvements in metabolic control and quality of life, and sibutramine was generally well tolerated in obese patients with type 2 diabetes.
Tinea capitis in Europe: new perspective on an old problem
Authors: Hay RJ , Robles W , Midgley G , Moore MK
Published: July 2002

A survey of tinea capitis conducted under the auspices of the European Confederation of Medical Mycology showed that laboratories contributing to a voluntary scheme for reporting have recently been seeing a different pattern of scalp ringworm. The survey was conducted among 92 medical mycology laboratories across 19 European countries by postal questionnaire comparing the years 1987 with 1997. The survey shows an overall increase in the numbers of cases caused by anthropophilic infections, which, in 1997, were the dominant causes of scalp infection; the greatest increase was seen in laboratories covering urban populations and in African Caribbean children living in Europe. While the commonest infection remains Microsporum canis, the largest overall increase has been in Trichophyton tonsurans, which in 1997 was the second commonest cause of infection overall and the commonest in urban populations. The pattern of change is not uniform in Europe and while some cities have reported large increases in T. tonsurans others, e.g. in France, have seen more cases of infection due to T. soudanense and M. audouinii. While these figures do not necessarily reflect changes in the underlying prevalence of infection, the trends are important to recognize as the control measures for anthropophilic tinea capitis differ from those used in zoophilic infections. In particular there is a need for an increased level of surveillance and more advice on control given to primary care physicians, dermatologists and school health authorities.
Alterations in fibrillin as well as collagens I and III and elastin occur in vulval lichen sclerosus
Authors: Farrell AM , Dean D , Millard PR , Charnock FM , Wojnarowska F
Published: July 2002

Background

The clinical features of lichen sclerosus, which include atrophy, scarring, fragility and tendency to form ecchymoses with only slight trauma, suggest that there is an alteration in the extracellular matrix fibres that are responsible for the tensile strength of the dermis. However, the precise nature of these changes is poorly understood.

Methods

Biopsies from 16 patients with untreated, histologically confirmed, vulval lichen sclerosus were examined immunohistochemically using polyclonal antibodies to collagens I and III and a monoclonal antibody to elastin. Twelve of the lichen sclerosus specimens were also stained with a monoclonal antibody to fibrillin. Normal vulva tissue and patients’ uninvolved thigh were used as controls.

Results

In the lichen sclerosus specimens, collagens I and III stained with a more homogeneous pattern than in the control tissues. Reduced numbers of elastin fibres were seen in the zone of sclerosus in 15 of the 16 lichen sclerosus specimens. In the control tissue fibrillin fibres were seen as a fine network of fibres in the upper dermis arranged at right angles to and inserting into the basement membrane and forming a fine network throughout the dermis. In the lichen sclerosus specimens, although fibrillin microfibrils were still seen inserting at right angles into the basement membrane, below this the fibrillin staining was reduced in the upper dermis in 11 of the 12 lichen sclerosus specimens. The zone of reduced fibrillin staining was greatest in those specimens where the band of inflammation was deep in the dermis.

Conclusions

The distribution of collagens I and III, elastin and fibrillin are altered in lichen sclerosus and this is likely to contribute to the fragility, scarring and atrophy seen clinically in lichen sclerosus.
Rheopheresis: Rheologic, Functional, and Structural Aspects
Authors: Klingel Reinhard , Fassbender Cordula , Fassbender Thurid , Erdtracht Bernard , Berrouschot Jörg
Published: July 2002

Abstract: Rheopheresis is a specific application of membrane differential filtration, synonymous with double filtration plasmapheresis for extracorporeal hemorheotherapy, eliminating an exactly defined spectrum of high molecular weight proteins from human plasma (e.g.: fibrinogen, α‐2‐macroglobulin, low‐density lipoprotein cholesterol, IgM). This results in the improvement of blood flow and microcirculation initiated by lowering blood and plasma viscosity, and erythrocyte aggregation. In this context, microcirculation stands not only for the patency of small blood vessels, but for the complete interactive network between plasma, blood cells, the vessel wall, and cellular and extracellular compartments of the surrounding tissue. Insufficient tissue oxygenation leads to tissue damage, e.g., a microcirculatory disorder develops, creating acute as well as chronic symptoms. Therefore, impaired microcirculation has a rheologic, functional, and structural dimension with respect to involved organs or tissues. Rheopheresis represents a specific therapeutic approach with an acute rheologic as well as chronic functional and structural effects, which was confirmed in pilot and controlled clinical studies for several organ systems. Data from 2 controlled clinical trials are available for the safe and effective treatment in patients with age‐related macular degeneration.
Exercise Rehabilitation Improves Functional Outcomes and Peripheral Circulation in Patients with Intermittent Claudication: A Randomized Controlled Trial
Authors: Gardner Andrew W. , Katzel Leslie I. , Sorkin John D. , Bradham Douglas D. , Hochberg Marc C. , Flinn William R. , Goldberg Andrew P.
Published: July 2002

OBJECTIVE: To determine the effects of a 6‐month exercise program on ambulatory function, free‐living daily physical activity, peripheral circulation, and health‐related quality of life (QOL) in disabled older patients with intermittent claudication.

DESIGN: Prospective, randomized controlled trial.

SETTING: University Medical Center and Veterans Affairs Medical Center, Baltimore, Maryland.

PARTICIPANTS: Thirty‐one of 61 patients with Fontaine stage II peripheral arterial occlusive disease (PAOD) were randomized to exercise rehabilitation and 30 to usual‐care control. Three patients from the exercise group and six patients from the control group dropped out, leaving 28 and 24 patients, respectively, completing the study in each group.

INTERVENTION: Six months of exercise rehabilitation.

MEASUREMENTS: Treadmill distance walked to onset of claudication and to maximal claudication, ambulatory function, peripheral circulation, perceived QOL, and daily physical activity.

RESULTS: Compliance with the exercise program was 73% of the possible sessions. Exercise rehabilitation increased treadmill distance walked to onset of claudication by 134% (P < .001) and to maximal claudication by 77% (P < .001), walking economy by 12% (P = .003), 6‐minute walk distance by 12% (P < .001), and maximal calf blood flow by 30% (P < .001). Changes in distance walked to maximal pain correlated with changes in walking economy (r = −.50, P = .013) and changes in maximal calf blood flow (r = .38, P = .047). Exercise rehabilitation increased accelerometer‐derived daily physical activity by 38% (P < .001); this change correlated with the change in distance walked to maximal pain (r = .45, P = .020). These improvements were significantly better than the changes in the control group (P < .05).

CONCLUSION: Improvements in claudication following exercise rehabilitation in older PAOD patients are dependent on improvements in peripheral circulation and walking economy. Improvement in treadmill claudication distances in these patients translated into increased accelerometer‐derived physical activity in the community, which enabled the patients to become more functionally independent. J Am Geriatr Soc 49:755–762, 2001.
Phenolic and Oxidative Metabolism as Bioindicators of Nitrogen Deficiency in French Bean Plants (Phaseolus vulgaris L. cv. Strike)
Authors: Sánchez E. , Soto J. M. , García P. C. , López‐Lefebre L. R. , Rivero R. M. , Ruiz J. M. , Romero L.
Published: July 2002

Abstract: The aim of the present work was to determine the effect of abiotic stress, such as nitrogen (N) deficiency, on phenol and oxidative metabolism. In addition, we analyzed whether the response of the two metabolic processes is a good bioindicator of N deficiency in French bean plants. The N was applied to the nutrient solution in the form of NH4NO3 at 1.35 mM (N1), 2.7 mM (N2) and 5.4 mM (N3), this latter dosage being considered optimal. The results indicated that application of 1.35 and 2.70 mM of N can be defined as suboptimal or deficient, as it depressed foliar biomass of the French bean plants in our experiment. In addition, abiotic stress from the application of these N dosages stimulated the enzymes PPO, POD and CAT, and inhibited PAL and SOD activities, resulting in the lowest foliar accumulation of phenolic compounds and H2O2.
Pattern and Amount of Aerenchyma Relate to Variable Methane Transport Capacity of Different Rice Cultivars
Authors: Aulakh M. S. , Wassmann R. , Rennenberg H. , Fink S.
Published: July 2002

Abstract: Aerenchyma, developed in both root and aboveground parts of rice plants, is predominantly responsible for plant‐mediated transfer of methane (CH4) from the soil to the atmosphere. To clarify the pathways of CH4 transport through the rice plant and find differences that may determine the large¡variation in the patterns of methane transport capacity (MTC) of rice cultivars, we examined the appearance, the distribution pattern, and the density of aerenchyma in different parts of rice¡plants of three widely varying rice cultivars during panicle initiation, flowering, and maturity stages. The data on the amount and density of small (> 1 ¡Á 103− 5 ¡Á 103Ìm2), medium (> 5 ¡Á 103− 20 ¡Á 103Ìm2) and large aerenchyma lacunae (> 20 ¡Á 103Ìm2) were collected using a computer assisted image‐analyzing system. The brightfield optical microscopy of roots of all tested rice plants demonstrated the continuity of aerenchyma channels in the roots that function as conduits for bi‐directional transport of gases. The aerenchyma channels of primary roots showed direct connection with those of culms. Intercalary meristems were found at the transition zone of rootaCculm aerenchyma connections. Well‐developed aerenchyma lacunae present in the internodal region of the culm base were uniformly distributed in the peripheral cortical zone. The nodal region had relatively fewer and smaller aerenchyma lacunae that showed a non‐uniform distribution pattern. As a result, few aerenchyma channels continued from the internodal region through to the nodal region. The aerenchyma in the cortex zone of the culm expanded along with the growing secondary tiller, developing continuity between the culm and the secondary tiller. The micrographs of longitudinal sections of different specimens of culmaCleaf sheath intersection showed the continuity of aerenchyma channels from the culm to the leaf. The amount of medium and large aerenchyma lacunae in the leaf sheath was respectively 2 and 33 times greater as compared to those of the tiller. The proportion of the large lacunae in the total amount of aerenchyma in leaf sheath was 75 % as compared to only 8 % in the tiller, revealing higher number and larger size of aerenchyma in the former. There were significant differences in amount and density of aerenchyma between individual cultivars at a given growth stage, as well as in the development patterns. While the amount and density of medium and small aerenchyma lacunae in the internodal region of the culm base did not show any relationship with MTC of rice cultivars, large aerenchyma lacunae exhibited highly significant correlations with MTC of different cultivars, suggesting that the wide variation in MTC of rice plants during different growth stages are related to these structural features.
Measurements of 3d state occupancy in transition metals using electron energy loss spectrometry
Authors: Pearson D. H. , Fultz B. , Ahn C. C.
Published: July 2002

We report a linear correlation between the total intensities of the L2,3 white lines in electron energy loss spectra and the number of unoccupied 3d states in 3d transition metals. We show that this correlation can be used to obtain quantitative information about electronic changes during alloying and during solid-state phase transformations.
Sequential surface chemical reaction limited growth of high quality Al2O3 dielectrics
Authors: Higashi G. S. , Fleming C. G.
Published: July 2002

Sequential surface reactions of trimethylaluminum and water vapor have been used to deposit Al2O3 on Si(100) surfaces. The self-limiting nature of the surface reactions allows precise control of the thickness of the deposited layers and gives rise to films with highly conformal step coverage. High quality dielectrics have been deposited at temperatures as low as 100 °C. Resistivities of 1017 Ω cm, breakdown strengths of 8×106 V/cm, and interface-state densities of 1011 states/eV cm2 have already been achieved and they suggest possible applications as a gate insulator or a dielectric passivation layer.
Recombination properties of structurally well defined NiSi2 precipitates in silicon
Authors: Kittler M. , Lärz J. , Seifert W. , Seibt M. , Schröter W.
Published: July 2002

We report first results on the recombination properties of structurally well defined NiSi2 precipitates in n-type silicon. Under the conditions applied, precipitates form without the occurrence of punched out dislocations or any other secondary defects. We find that the minority-carrier diffusion length (LD) measured by electron beam induced current (EBIC) is related to the precipitate density NV and LD ≂ 0.7 × NV−1/3. EBIC investigations of individual precipitates reveal contrasts up to 40% demonstrating NiSi2 particles to be efficient recombination centers.
Surface-micromachined PbTiO3 pyroelectric detectors
Authors: Polla D. L. , Ye Chian-ping , Tamagawa Takashi
Published: July 2002

Lead titanate (PbTiO3) thin-film pyroelectric infrared detectors have been fabricated on polycrystalline silicon micromechanical membranes. Pyroelectric PbTiO3 thin films of thickness ranging from 0.2 to 0.6 μm were prepared by sol-gel spin casting techniques and deposited on 1.0-μm-thick polycrystalline silicon membranes suspended 1.0 μm above the surface of a silicon wafer. This composite structure offers high sensitivity and low thermal mass. The measured pyroelectric coefficient for 0.36-μm-thick PbTiO3 films is 90 nC/cm2 K. The measured blackbody voltage responsivity for a pyroelectric element with an active area of 7×10−4 cm2 at 297 K and a chopping frequency of 50 Hz is 4.2×104 V/W. The measured normalized detectivity D* at 297 K and 50 Hz is 1.0×109 cm Hz1/2/W.
On the ‘‘band-A’’ emission and boron related luminescence in diamond
Authors: Ruan J. , Kobashi Koji , Choyke W. J.
Published: July 2002

Cathodoluminescence spectra of undoped and boron-doped diamond films are reported and are compared with each other. The dominant spectra feature of these samples is the broad luminescence bands centered around 2.83 and 2.32 eV in undoped and relatively heavily doped samples, respectively. Our result indicates that the commonly observed 2.83 eV band (often called by the name ‘‘band-A’’) is neither related to boron nor to donor-acceptor pairs in diamond. From all of the available data, we conclude that the 2.32 eV band is due to boron related centers and the 2.83 eV band is due to dislocations in diamond.
Oxygen diffusion into diamond induced by hydrogen microwave plasma
Authors: Mori Y. , Eimori N. , Kozuka H. , Yokota Y. , Moon J. , Ma J. S. , Ito T. , Hiraki A.
Published: July 2002

Diffusion of oxygen atoms into diamond can be introduced by CrO3 treatment followed by an exposure to a hydrogen plasma. From characterization using Rutherford backscattering spectrometry, it is found that the depth distribution of the doped oxygen in the diamond is homogeneous from the surface where its concentration is about 1020 atoms/cm3. The doped oxygen can form cathodoluminescence centers yielding luminescence peaks at 3.75 and 4.64 eV at room temperature. After the diffusion of oxygen atoms, damages in the diamond cannot be detected by Raman scattering spectroscopy.
On the effects of carrier diffusion and quantum capture in high speed modulation of quantum well lasers
Authors: Kan Sidney C. , Vassilovski Dan , Wu Ta C. , Lau Kam Y.
Published: July 2002

It is shown that, the combined effects of carrier diffusion in the separate confinement heterostructure region and quantum capture into the quantum well must be considered together when evaluating the limits on the modulation bandwidth of quantum well lasers, despite the fact that quantum capture is considerably faster than carrier diffusion. The importance of quantum capture may be observed by noting that the modulation bandwidth is adversely affected even for quantum capture times as short as 0.2 ps, or if the ratio of the quantum capture time to quantum escape time is large (≳0.01). Therefore, the bandwidth limitation may be caused by electron transport rather than hole transport since quantum capture of holes is faster than that of electrons.
Persistent hole burning of the nitrogen vacancy center and the 2.16 eV center of chemical-vapor deposited diamond
Authors: Yokota Yoshihiro , Ma Jing Sheng , Ito Toshimichi , Hiraki Akio , Kurita Atusi , Kushida Takashi , Kawarada Hiroshi
Published: July 2002

The persistent spectral hole burning effect has been observed for the nitrogen vacancy (NV) center and the 2.16 eV center in chemical-vapor deposited (CVD) diamond. This sideband is the first observation of spectral hole burning in CVD diamond. Holes are burned in the inhomogeneously broadened zero-phonon lines of both the centers by dye lasers. The holes were observed by photoluminescence excitation spectroscopy, with monitoring of the phonon-sideband emission, at temperatures up to 130 K for the NV center and up to 100 K for the 2.16 eV center.
Raman spectroscopy and the effects of ultraviolet irradiation on polyimide film
Authors: Gu X. J.
Published: July 2002

Raman spectra of polyimide films were studied before and after being irradiated with 308 nm excimer laser pulses in order to understand the conductivity increase induced by ultraviolet irradiation. Changes in the chemical structure of polyimide were observed. A possible mechanism responsible for the ultraviolet induced conductivity increase is proposed. This letter also shows that the Raman microprobe can be very useful in the analysis of the molecular structure of polymers.
Quantum efficiencies exceeding unity due to impact ionization in silicon solar cells
Authors: Kolodinski Sabine , Werner Jürgen H. , Wittchen Thomas , Queisser Hans J.
Published: July 2002

Absolute measurements demonstrate internal quantum efficiencies in silicon solar cells to exceed unity for photon energies above the first direct band gap and to show distinct spectral features that correspond to specific points in the Brillouin zone. Ultraviolet radiation can generate hot carriers with sufficient energy to cause impact ionization which results in two electron hole pairs per incident photon.
Low resistivity cubic phase CdS films by chemical bath deposition technique
Authors: de Melo O. , Hernández L. , Zelaya-Angel O. , Lozada-Morales R. , Becerril M. , Vasco E.
Published: July 2002

In this letter we report on cubic CdS thin films with low resistivity by chemical bath deposition (CBD) technique and subsequent annealings in S2 and H2+In. Low temperature photoluminescence, x rays, and transmission spectra support the assumption that S2 annealings contribute to fill the vacancies in the as-deposited films leading to an enlargement of the CdS cubic cell. This fact is revealed by an increase in interplanar distances, evanescence of the PL red broad band, and decrease in band-gap energies. Cubic phase remains after H2+In annealing at higher temperatures. A resistivity as low as 11 Ω cm was obtained at an optimum annealing temperature of 350 °C.
Ge surface segregation at low temperature during SiGe growth by molecular beam epitaxy
Authors: Godbey D. J. , Lill J. V. , Deppe J. , Hobart K. D.
Published: July 2002

The temperature dependence of germanium surface segregation during growth by solid source SiGe molecular beam epitaxy (MBE) was studied by x-ray photoelectron spectroscopy and kinetic Monte Carlo (KMC) modeling. Germanium segregation persisted at temperatures 60 °C below that predicted by a two-state exchange model. KMC simulations, where film growth, surface diffusion, and surface segregation are modeled consistently, successfully describe the low temperature segregation of germanium. Realistic descriptions of MBE must follow the physical rates of the growth, surface diffusion, and surface segregation processes.
Densification, anisotropic deformation, and plastic flow of SiO2 during MeV heavy ion irradiation
Authors: Snoeks E. , Polman A. , Volkert C. A.
Published: July 2002

The response of SiO2 thin films and implantation masks to 4.0 MeV Xe irradiation is studied. Trenches in silica deform dramatically after irradiation with 3×1015 ions/cm2. In situ wafer curvature measurements show that thin planar silica films first densify by 3.6% during irradiation. The resulting stress then relaxes viscously by radiation-enhanced Newtonian flow. At a flux of 3×1010 Xe ions/cm2s the measured shear viscosity was 6×1013Pa s. We find evidence that an irradiation induced anisotropic deformation mechanism is present in the silica films. In equilibrium, this deformation leads to an average compressive saturation stress as large as 4.5×107 Pa.
Imaging radio-frequency fields using a scanning SQUID microscope
Authors: Black R. C. , Wellstood F. C. , Dantsker E. , Miklich A. H. , Koelle D. , Ludwig F. , Clarke J.
Published: July 2002

Using a liquid-nitrogen-cooled scanning SQUID magnetic microscope, we have developed a technique for broadband imaging of radio-frequency (rf) and microwave fields with a spatial resolution of about 15 μm. We have produced images of the amplitude of 50 MHz fields with an rms noise of 2.6 nT and a 300 μm/s scan rate. Detection is accomplished by using the nonlinearity of the voltage-flux characteristic of the SQUID to rectify the rf fields. Our present technique is limited by cavity mode resonances in the SrTiO3 substrate of our SQUID sensor. Using a small excitation probe, we have directly imaged these resonances at frequencies up to about 12.5 GHz.
Magnetic diagnostics and feedback control on TFTR (invited)
Authors: Coonrod J. , Bell M. G. , Hawryluk R. J. , Mueller D. , Tait G. D.
Published: July 2002

The various operating modes of TFTR require the use of a sophisticated system of magnetic diagnostics integrated with a feedback control system. This system has successfully controlled the plasma current and position over a range of major and minor radii, during strong compression, and will soon be used during intense neutral beam heating. Current and position values are held constant to within 2 kA and 1 cm. A wide variety of preoperational field measurements were required to determine proper compensation for dynamic stray fields due to eddy currents. Data from plasma profile diagnostics, such as bolometer arrays, Thomson scattering, soft x-ray diode array, and the scanning radiometer, have been compared to the absolute position deduced from magnetics. In addition to control functions, magnetic diagnostics on TFTR provide data on plasma current asymmetry, βθ, MHD fluctuations, loop voltage, and flux consumption. This paper will discuss the mechanical and electronic design constraints, as well as the analytic and calibration techniques required.
High-resolution scanning SQUID microscope
Authors: Kirtley J. R. , Ketchen M. B. , Stawiasz K. G. , Sun J. Z. , Gallagher W. J. , Blanton S. H. , Wind S. J.
Published: July 2002

We have combined a novel low temperature positioning mechanism with a single-chip miniature superconducting quantum interference device (SQUID) magnetometer to form an extremely sensitive new magnetic microscope, with a demonstrated spatial resolution of ∼10 μm. The design and operation of this scanning SQUID microscope will be described. The absolute calibration of this instrument with an ideal point source, a single vortex trapped in a superconducting film, will be presented, and a representative application will be discussed.
Flexible tube countercurrent heat exchanger
Authors: Coffelt R. J. , Wikman-Coffelt J.
Published: July 2002

The countercurrent heat exchanger described here functions as a fluid heater or cooler for maintaining or modulating temperature in a liquid flowing through a glassware and plastic tube system.
Measurement of 0.1–3-keV x rays from laser plasmas
Authors: Kornblum H. N. , Kauffman R. L. , Smith J. A.
Published: July 2002

We have made absolute measurements of x-ray spectra from 0.1–1.5 keV produced by plasmas from targets irradiated by the Lawrence Livermore National Laboratory Nova laser. These measurements were made using a 15-channel K- and L-edge filtered x-ray diode system. Valid interpretation of the results from this type of diagnostic requires some care in eliminating the effect of channel response at photon energies higher than the absorption edge. Significant errors can occur if this is disregarded. We will discuss the techniques used and the magnitude of the effects observed. Integrated x-ray energy in the 1.5–3-keV region is inferred from the results.
HAIFA: A modular, fiber-optic coupled, spectroscopic diagnostic for plasmas
Authors: Ramsey Alan T. , Turner Stephen L.
Published: July 2002

HAIFA is a modular, multichannel, fiber-optically coupled spectroscopy diagnostic for tokamak plasmas. It operates in the visible, measuring Hα radiation, the visible continuum from thermal bremsstrahlung, and selected impurity lines. HAIFA is characterized by high modularity and flexibility, good radiation resistance, high noise immunity, and low cost. Details of design, construction, and calibration are given. The analysis of visible bremsstrahlung radiation measurements to deduce the effective ionic charge in a plasma is discussed.
Tomographic imaging of three-phase flow experiments
Authors: Vinegar Harold J. , Wellington Scott L.
Published: July 2002

The medical x-ray computerized tomography (CT) scanner has proved to be a useful tool for studies of fluid flow in porous media, with particular applications in reservoir engineering and enhanced oil recovery. This paper explains how CT is used to measure the volume fraction of pore space occupied by up to three discrete phases, such as oil, water, and gas. The image processing system, x-ray transparent high-pressure flow equipment, choice of fluid dopants, and x-ray energies are described for scanning of core flood experiments. Examples are given of tertiary miscible carbon dioxide displacements in Berea sandstone.
Electrical resistance of screw-fastened thermal joints for ultra-low temperatures
Authors: Okamoto Tohru , Fukuyama Hiroshi , Ishimoto Hidehiko , Ogawa Shinji
Published: July 2002

Electrical resistance measurements at 4.2 K have been made for various screw-fastened thermal joints used at ultra-low temperatures below 100 μK. The measured contact resistance for a gold-plated joint varied in inverse proportion to a tightening torque of the screw. With a maximum tightening torque for a 4-mm stainless-steel screw, several types of the joints revealed to have contact resistances below 10 nΩ. A current-decay method used to measure a small variation of contact resistance of less than 0.1 nΩ is also described.
Photon scanning tunneling microscopy
Authors: Reddick R. C. , Warmack R. J. , Chilcott D. W. , Sharp S. L. , Ferrell T. L.
Published: July 2002

An optical tunneling microscope is presented that operates in exactly the same way as the electron scanning tunneling microscope (ESTM). It takes advantage of evanescent fields generated by the total internal reflection (TIR) of light at the interface between materials of different optical densities. The photon scanning tunneling microscope (PSTM) employs an optically conducting probe tip to map spatial variations in the evanescent and scattered field intensity distributions adjacent to a sample surface, which forms or is placed on the TIR surface. These variations are due to the local topography, morphology, and optical activity of the surface and form the basis of imaging. Evanescent field theory is discussed and the evanescent field intensity as a function of surface-probe separation is calculated using several probe tip models. After a description of PSTM construction and operation, evanescent field intensity measurements are shown to agree with the model calculations. PSTM images of various sample surfaces demonstrate subwavelength resolution exceeding that of conventional optical microscopy, especially in the vertical dimension. Limitations and interpretation of PSTM images are discussed as well as the PSTMs applicability to other forms of surface analysis.
Design of a multistage 250 kJ capacitor bank for ohmic transformer of tokamak ‘‘ADITYA’’
Authors: Sathyanarayana K. , Saxena Y. C. , John P. I. , Pujara H. D. , Jain K. K.
Published: July 2002

Tokamaks require toroidal loop voltage for breakdown of the neutral gas, current rise, and the flat top phase. The temporal profile of the loop voltage established by the change of flux linked by the ohmic transformer has to be a noncosine waveform. In this paper a multistage capacitor bank is described which was used to energize the ohmic transformer in tokamak ADITYA with a major radius of 0.75 m, minor radius of 0.25 m, and a toroidal field of 1.5 T at the plasma center. A combination of capacitors charged to different voltages are switched in at appropriate times, to realize an experimental demand for initial high loop voltage followed by a lower sustaining loop voltage. Theoretical prediction for the duration of the secondary loop voltage as a function of circuit parameters, for a fast bank operation of 6 kV, slow bank, 4–4.5 kV, and slow bank, 2–2.5 kV yield t0=1.25 mS, t1=4.95 mS, and t2=24.1 mS. These values are in close agreement to the measured values of t0=1.39 mS, t1=5.7 mS, and t2=23.7 mS. The trigger delays to the various capacitor bank sections are parameter dependent. To avoid repetitive adjustments in the delays, a novel scheme for consistent triggering is also highlighted.
Near-infrared topographic measurement system: Imaging of absorbers localized in a scattering medium
Authors: Yamashita Yuichi , Maki Atsushi , Koizumi Hideaki
Published: July 2002

We developed a multichannel reflectance measurement system that uses near-infrared measurements for topographic imaging inside biological tissue. In this system, nine incident and four detecting optical fibers are arranged alternately at square lattice points on the sample. Source light is optically demultiplexed with an optical fiber switch, and connected to one of the incident fibers. Reflected light from the sample is received by the detecting fibers each of which is connected to a photodiode. The photodiode outputs are multiplexed. Sixteen combinations of neighboring incident and detecting fibers correspond to 16 measurement channels. These channels are selected sequentially with the optical fiber switch and the multiplexer. The system was used to obtain topographic images of absorbers in the scattering medium that simulated biological tissue.
Multilayer roughness and image formation in the Schwarzschild objective
Authors: Singh S. , Solak H. , Cerrina F.
Published: July 2002

We present a study of the effect of multilayer-surface-roughness-induced scattering in the image formation of the Schwarzschild objective (SO) used in the spectromicroscope MAXIMUM. The two mirrors comprising the SO are coated with Ru/B4C multilayers that have a peak reflectivity at 130 eV. We had long observed that a diffuse x-ray background surrounds the focused x-ray spot. The spatial resolution remains at 0.1 μm in spite of this. However, since a significant fraction of the flux is lost to the background, since too large an area of the sample is illuminated, and since the S/N ratio is degraded, the origins of this effect merit investigation. This diffuse background resulting from x-ray scattering at the surface of the mirrors was mapped out using bidirectional knife edge scans. Complementary surface roughness simulations were carried out with the ray-tracing program SHADOW. AFM experiments were also done to directly measure the surface roughness and power spectrum of representative multilayers. Following curve fitting, it was possible to classify Gaussian components in both the measured and simulated profiles as arising from scattering occurring at either the convex primary mirror or the concave secondary mirror. Together with geometrical analysis, these techniques permitted us to track the image formation process of an actual optical system in the presence of surface roughness.
Reentrant radio-frequency resonator for automated phase-equilibria and dielectric measurements in fluids
Authors: Goodwin Anthony R. H. , Mehl James B. , Moldover Michael R.
Published: July 2002

A reentrant rf cavity resonator has been developed for automated detection of phase separation of fluid mixtures contained within the cavity. Successful operation was demonstrated by redetermining the phase boundaries of a CO2+C2H6 mixture in the vicinity of its critical point. We developed an accurate electrical model for the resonator and used helium to determine the deformation of the resonator under pressure. With the model and pressure compensation, the resonator was capable of very accurate dielectric measurements. We confirmed this by remeasuring the molar dielectric polarizability Aε of argon and obtained the result Aε=(4.140±0.006) cm3/mol (standard uncertainty) in excellent agreement with published values. We exploited the capability for accurate dielectric measurements to determine the densities of the CO2+C2H6 mixture at the phase boundaries and to determine the dipole moment of 1,1,1,2,3,3-hexafluoropropane, a candidate replacement refrigerant. Near the operating frequency of 375 MHz the capacitor in the resonator has an impedance near 14 Ω. This low impedance is more tolerant of electrical conductivity within the test fluid and in parallel paths in the support structures than comparable capacitors operating at audio frequencies. This will be an advantage for operation at high temperatures where some conductivity must be expected in all fluids. Of further value for high-temperature applications, the present rf resonator has only two metal–insulator joints. These joints seal coaxial cables; neither joint is subjected to large mechanical stresses and neither joint is required to maintain precise dimensional tolerances. The resonator is rugged and may be operated with inexpensive electronics.
Ultrasonic shear wave reflection method for measurements of the viscoelastic properties of polymer films
Authors: Alig I. , Lellinger D. , Sulimma J. , Tadjbakhsch S.
Published: July 2002

We report a shear wave reflection technique which allows time- and temperature-dependent measurements of the complex dynamic shear modulus (G*=G′+iG′′) or the dynamic shear viscosity (ηs′) in the ultrasonic frequency range (3–40 MHz). The shear wave reflection method developed by Mason et al. [Phys. Rev. 75, 936 (1949)] was adapted to the possibilities of the high-frequency digital technique. A conventional single-frequency pulse-burst system and a broadband pulsed ultrasonic spectroscopic system using Fourier analysis for detection of phase and amplitude changes of the reflected signals are described alternatively. Due to digital analysis of the received signal it was possible to achieve a simplification of the experimental setup and to extend the limits of the shear wave reflection technique to about one Gigapascal (100 μm film thickness) or to minimum film thickness of about 10 μm (G′<10 MPa). Furthermore, it is possible to monitor time-dependent isothermal processes or reactions with the setup. The basic features of the two different techniques are presented together with brief experimental results on film formation from aqueous polychloroprene dispersions and of the crystallization kinetics in the films. Furthermore, temperature-dependent studies of melting and crystallization on semicrystalline polychloroprene and of the glass transition behavior of amorphous butyl acrylate/styrene copolymer films are reported. The importance of the method is discussed for both investigations of fundamental questions (e.g., film formation, reaction kinetics, or phase transitions) and technological assessment (glues, paints, etc.).
A Langmuir/Mach probe array for edge plasma turbulence and flow
Authors: Back Rüdiger , Bengtson Roger D.
Published: July 2002

We have installed and operated a reciprocating Langmuir/Mach probe to simultaneously measure parallel and perpendicular plasma flow profiles along with density, temperature, floating potential profiles, and fluctuating parameters such as fluctuation driven particle flux and wave number on a single shot. Plasma facing components are made from boron nitride and the probe tips are 1-mm-diam carbon cylinders. The Mach probe, designed following the Gundestrup model, has 12 probes arranged in a circular array. Four Langmuir probes mounted at the front of the Mach probe array measure floating potential, ion saturation current, and temperature. The perpendicular flow velocity measurements reduced from the Mach probe array compare well with the phase velocity measured from the proud Langmuir probes and the Er×B poloidal rotation.
Fiber Bragg gratings
Authors: Othonos Andreas
Published: July 2002

Since the discovery of photosensitivity in optical fibers there has been great interest in the fabrication of Bragg gratings within the core of a fiber. The ability to inscribe intracore Bragg gratings in these photosensitive fibers has revolutionized the field of telecommunications and optical fiber based sensor technology. Over the last few years, the number of researchers investigating fundamental, as well as application aspects of these gratings has increased dramatically. This article reviews the technology of Bragg gratings in optical fibers. It introduces the phenomenon of photosensitivity in optical fibers, examines the properties of Bragg gratings, and presents some of the important developments in devices and applications. The most common fabrication techniques (interferometric, phase mask, and point by point) are examined in detail with reference to the advantages and the disadvantages in utilizing them for inscribing Bragg gratings. Reflectivity, bandwidth, temperature, and strain sensitivity of the Bragg reflectors are examined and novel and special Bragg grating structures such as chirped gratings, blazed gratings, phase-shifted gratings, and superimposed multiple gratings are discussed. A formalism for calculating the spectral response of Bragg grating structures is described. Finally, devices and applications for telecommunication and fiber-optic sensors are described, and the impact of this technology on the future of the above areas is discussed.
High power ultrafast lasers
Authors: Backus Sterling , Durfee Charles G. , Murnane Margaret M. , Kapteyn Henry C.
Published: July 2002

In this article, we review progress in the development of high peak-power ultrafast lasers, and discuss in detail the design issues which determine the performance of these systems. Presently, lasers capable of generating terawatt peak powers with unprecedented short pulse duration can now be built on a single optical table in a small-scale laboratory, while large-scale lasers can generate peak power of over a petawatt. This progress is made possible by the use of the chirped-pulse amplification technique, combined with the use of broad-bandwidth laser materials such as Ti:sapphire, and the development of techniques for generating and propagating very short (10–30 fs) duration light pulses. We also briefly summarize some of the new scientific advances made possible by this technology, such as the generation of coherent femtosecond x-ray pulses, and the generation of MeV-energy electron beams and high-energy ions.
Improved two-dimensional product imaging: The real-time ion-counting method
Authors: Chang Bor-Yu , Hoetzlein Rama C. , Mueller Julie A. , Geiser Joseph D. , Houston Paul L.
Published: July 2002

A novel ion-counting method for significantly improving the spatial resolution and detection sensitivity of two-dimensional product imaging in molecular beam experiments is presented. The method makes use of real-time digital image processing to retrieve, threshold, and determine the local maximum of each ion hitting a microchannel plate assembly. The current version can process data at rates up to 3.07 Mbyte/s, and methods for accelerating this rate are proposed.
Cavity enhanced absorption and cavity enhanced magnetic rotation spectroscopy
Authors: Engeln Richard , Berden Giel , Peeters Rudy , Meijer Gerard
Published: July 2002

It is experimentally demonstrated that a narrow band continuous wave (cw) light source can be used in combination with a high-finesse optically stable cavity to perform sensitive, high-resolution direct absorption and optical rotation spectroscopy in an amazingly simple experimental setup, using ideas from the field of cavity ring down spectroscopy. Light from a scanning narrow band cw laser is coupled into the cavity via accidental coincidences of the laser frequency with the frequency of one of the multitude of modes of the cavity. The absorption and polarization rotation information is extracted from a measurement of the time-integrated light intensity leaking out of the cavity as a function of laser wavelength.
Quantitative microwave near-field microscopy of dielectric properties
Authors: Gao C. , Xiang X.-D.
Published: July 2002

A theoretical model analysis for a recently developed scanning evanescent microwave microscope has been performed. The result enables a quantitative microscopy of local complex dielectric constant profiles for dielectric materials. Various experiments were performed and found to be in good agreement with the theoretical results. The estimation of intrinsic resolution of the microscope suggests that nanometer spatial resolution is achievable. System analysis gives a limiting sensitivity of about δε/ε∼1×10−5.
Low aberration focusing system for a proton nanoprobe
Authors: Wollnik H. , Yavor M. I. , Kalimov A. G.
Published: July 2002

Based on detailed numerical calculations, an ion-optical scheme is proposed for a low aberration proton nanoprobe system that includes four electrostatic quadrupoles arranged like a “Russian Quadruplet” and a magnetic solenoid lens with a flux density of 2 T. The sensitivity of the system to misalignments of the lenses is investigated.
Development of a high performance core snubber for high power neutral beam injectors
Authors: Watanabe Kazuhiro , Mizuno Makoto , Nakajima Shin , Iimura Tsutomu , Miyai Yuzo
Published: July 2002

A high performance core snubber using Fe-based soft magnetic alloys composed of ultrafine grain structure cores has been developed to protect an ion source accelerator from electrical breakdowns. Dimension of each core is 900 mm in outer diameter, 400 mm in inner diameter, and 25.4 mm in thickness. Basic characteristics of the core has been investigated and confirmed that the core has a saturation magnetic flux density of 1.35 T with a high relative permeability of about 3500 for a high frequency pulse of 1 MHz. A total magnetic flux of the core snubber is 0.15 Wb with 13 cores and a biasing current. The size of the core snubber could be reduced to about 1/3 from the conventional one composed of Ni–Zn ferrite cores.
Further development of a gaseous ion source based on low-pressure hollow cathode glow
Authors: Vizir A. V. , Yushkov G. Yu. , Oks E. M.
Published: July 2002

The gaseous ion source based on a hollow cathode glow discharge with additional external injection of electron beam described in a previous publication has undergone further development. The direction of the source upgrade was to increase the total beam current and its density keeping the same broad beam cross section (about 100 cm2). With an operating gas pressure of 10−4 Torr, the maximum stable discharge current was as high as 40 A in 300 μs (pulsed mode) and about 10 A (dc mode) without discharge gap arc breakdown. The total ion emission current exceeded 1 A in both cases. The geometry of the discharge gap was optimized, allowing improvement of the parameters of the device. The composition of the ion beam under various operating conditions of the discharge has been measured using the time-of-flight method. The electron beam injection into the hollow cathode of the ion source resulted in a reduction of the discharge voltage from the usual 500–600 V to 100 V or less. This lead to lower sputtering and as a result low contamination of the gaseous ion beam by metal fractions. Measurements showed 0.15% metal content instead of the typical several percent. The influence of the ion beam extraction on the discharge parameters was also examined.
Carbon nanotubes are coherent electron sources
Authors: Schmid Heinz , Fink Hans-Werner
Published: July 2002

The observation of electron interference effects provides direct evidence of the coherence of the electrons emitted from a carbon nanotube. To demonstrate this, the low-energy electron point source microscope has been used to mount an individual carbon nanotube onto a tungsten tip. In subsequent experiments, the electrons emitted from the nanotube were used to generate holograms. Comparison with a standard tungsten atomic point source emitter establishes a high degree of coherence for a nanotube emitter.