bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonfluoroscopic reduction of intussusception by air enema
Authors: Wang Guiru , Liu Xiao Guang , Zitsman Jeffrey L.
Published: October 2004

Intussusception is a common pediatric condition in China. Hydrostatic reduction with barium sulfate or pneumatic reduction using air and fluoroscopy has become the standard method in most centers throughout the world. To avoid radiation exposure, reduction without fluoroscopic confirmation was studied. Between 1981 and 1985 a total of 224 children were diagnosed and treated for intussusception. The diagnosis was made correctly on clinical grounds in 184 cases; in 40 cases ultrasonography confirmed the clinical diagnosis. Pressurized air reduction was successful in 217 patients (96.9%); seven patients required operative reduction. Ultrasonograms of the abdomen supported the diagnosis in 40 patients and confirmed subsequent reduction. This experience demonstrates that childhood intussusception can be reduced using pneumatic pressure without exposing the patient to ionizing radiation.
Adjuvant postoperative radiation therapy after curative resection of squamous cell carcinoma of the thoracic esophagus: A prospective randomized study
Authors: Zieren Hans U. , Müller Joachim M. , Jacobi Christoph A. , Pichlmaier Heinz , Müller Rolf‐Peter , Staar Sabine
Published: October 2004

Abstracts

Postoperative radiation therapy following curative resection of squamous cell carcinoma of the esophagus was investigated in a prospective randomized study. A group of 33 patients received postoperative radiation therapy and were compared to a control group of 35 patients treated by surgery alone. No statistically significant differences were noted between the two treatment groups concerning overall and disease‐free survival rates. Postoperative irradiation significantly increased the incidence of fibrotic strictures of the esophagogastric or esophagocolonic anastomoses and caused a delayed recovery of patients quality of life. Based on these results, we believe that postoperative radiation therapy alone cannot be advocated as a adjuvant therapy following curative resection of squamous cell carcinoma of the esophagus.
Prophylaxis with intraoperative chemohyperthermia against peritoneal recurrence of serosal invasion‐positive gastric cancer
Authors: Yonemura Y. , Ninomiya I. , Kaji M. , Sugiyama K. , Fujimura K. , Sawa T. , Katayama K. , Tanaka S. , Hirono Yasuo , Miwa K. , Miyazaki I.
Published: October 2004

Continuous hyperthermic peritoneal perfusion (CHPP) with a solution which contains 30 mg mitomycin C and 300 mg cisplatin has been introduced as a prophylactic treatment for peritoneal recurrence after curative resection of 79 advanced gastric cancers. The control group consisted of 81 patients with advanced gastric cancer who underwent curative surgery during the same period. CHPP was performed for 60 minutes by perfusing MMC‐ and CDDP‐containing saline solutions warmed at 43.5°C by a special CHPP device. In patients with pathologically confirmed serosal invasion‐positive tumors, the survival rate of the CHPP group was significantly higher than that of the control group. A survival advantage for stage IV patients was also obtained by CHPP. However, there was no survival advantage between the CHPP group and the control group with serosal invasion‐negative tumors. Adverse effects were observed in four patients who underwent CHPP: One developed severe bone marrow suppression, and transient hyperazotemia was ebserved in the other three. There was no difference in the incidence of mortality and morbidity between the two groups. These results indicate that CHPP is a safe, readily available prophylactic therapy for peritoneal recurrence after gastric cancer surgery.
Early postoperative evaluation of pylorus‐preserving gastrectomy for gastric cancer
Authors: Kodama Masashi , Koyama Kenji , Chida Teisao , Arakawa Akira , Tur Gennady
Published: October 2004

Early postoperative evaluation was prospectively performed in 35 gastric cancer patients after pylorus‐preserving gastrectomy (PPG) between 1989 and 1991, comparing the results with those of 29 patients who underwent conventional distal gastrectomy (CDG). Surgical stress, including the duration of operation (149.0±4.3 minutes) and the total volume of bleeding at operation (97.0±11.2 g), was significantly less in the PPG patients. Early postoperative complications were seen in 31% after PPG and in 35% after CDG. The most frequent complication in PPG patients was remnant gastric stasis (23%). Endoscopy showed redness or erosion (or both) of the gastric remnant in 17% after PPG and in 81% after CDG. Bile regurgitation was demonstrated in 11% after PPG and in 62% after CDG. In PPG patients, the pyloric ring opened and closed during the examination. Gastric pH was 4.2±0.4 in PPG patients but was significantly lower in CDG patients. The resting gallbladder area, examined by ultrasonography, demonstrated no changes after PPG but was significantly enlarged after CDG (from 11.3±1.2 cm2 to 15.8±1.5 cm2 at 2 weeks). The percentage of the original resting gallbladder area at 20 minutes after injection of cerulein increased slightly in PPG patients but recovered thereafter, whereas in CDG patients it increased significantly (from 39.4±8.3% to 66.7±9.1% at 2 weeks). No gallstone formation was detected throughout the observation period after PPG, whereas after CDG it was detected in two patients at 1 year. These results indicated that PPG for gastric cancer has advantages over CDG in terms of surgical stress, the condition of the gastric remnant, and gallbladder function.
The median body of Giardia lamblia: an ultrastructural study
Authors: Piva Bruno , Benchimol Marlene
Published: October 2004

Abstract Giardia lamblia is an intestinal parasite of several mammals. The most striking feature of Giardia is the presence of a complex and unique cytoskeleton, and among its components the median body (MB) is the least defined microtubular structure. In the present study, we used a technique that allowed the removal of the plasma membrane and observation of cytoskeletal structures by both routine scanning electron microscopy (SEM) and field emission high resolution SEM. This technique permitted new observations such as details and insights of the median bodies, not previously described or controversial in the literature. Light microscopy after Panotic staining, immunofluorescence microscopy using several antibodies, and thin sections were also used to better characterized the Giardia MB. The new observations concerning the median bodies were : (1) they are not one or two structures, but varied in number, shape and position ; (2) they were found in mitotic and interphasic trophozoites, in disagreement with previous works ; (3) they were present in about 80 % of the cells, and not in 50 % of the cells, as previously described ; (4) they could be connected either to the plasma membrane, to the adhesive disc, and caudal flagella, and thus they are not completely free in the cells, as published before ; (5) they can protrude the cell surface ; (6) their microtubules react with several anti‐tubulin and ‐beta giardin antibodies. These observations add new data on the scarce literature and to this largely understudied cell structure.
Evidence for copper homeostasis function of metallothionein (MT3) in the hyperaccumulator Thlaspi caerulescens
Authors: Roosens Nancy H. , Bernard Catherine , Leplae Raphael , Verbruggen Nathalie
Published: October 2004

Metallothioneins chelate metals and consequently may be a control point of metal homeostasis. Homologous to type 3 metallothioneins, TcMT3 cDNA was identified in the Cd/Zn hyperaccumulator, Thlaspi caerulescens. TcMT3 amino acid sequence showed modifications in the Cys positions when compared with its Arabidopsis orthologue. A structural model established that the MT3 carboxyterminal domain is similar to the β domain of animal metallothioneins and predicts a smaller cavity to chelate metals for A. thaliana than for T. caerulescens. Functional testing in yeast and Northern blot analysis added further evidence for adaptative variations of MT3 for the maintenance of Cu homeostasis in a metal hyperaccumulator.
Protein–protein interaction between monomers of coliphage HK022 excisionase
Authors: Gottfried Pnina , Kolot Mikhail , Silberstein Nava , Yagil Ezra
Published: October 2004

Excisionase (Xis) is an accessory protein that is required for the site‐specific excision reaction of the coliphages HK022 and λ. Xis binds in a strong cooperative manner to two tandem binding sites (X1 and X2) located on the P arm of the attachment (att) sites on the phage genome. As a result of crosslinking experiments in vivo and in vitro of Xis‐overexpressing cells, by gel filtration of purified Xis and by FRET analyses we show that Xis monomers of HK022 interact and form dimers that are not dependent on the single Cys residue of the protein and on the presence of DNA. The formation of the dimers may explain the strong binding cooperativity of Xis to its sites on DNA.
Expression of a cascading genetic network within liposomes
Authors: Ishikawa Keitaro , Sato Kanetomo , Shima Yasufumi , Urabe Itaru , Yomo Tetsuya
Published: October 2004

Liposomes have long been used as possible compartments for artificial cells, and it has been shown that liposomes can sustain various types of biochemical reactions. To elevate the degree of molecular complexity of the system in liposomes, we have constructed a two‐stage genetic network encapsulated in liposomes. This two‐stage genetic network was constructed with the plasmid pTH, in which the protein product of the first stage (T7 RNA polymerase) is required to drive the protein synthesis of the second stage (GFP). We show that the two‐stage genetic network constructed in a cell‐free expression system is functional within liposomes.
Proteoglycan isolated from Phellinus linteus inhibits tumor growth through mechanisms leading to an activation of CD11c+CD8+ DC and type I helper T cell‐dominant immune state
Authors: Kim Gi-Young , Oh Won-Kyo , Shin Byung-Cheul , Shin Yong-Il , Park Young-Chul , Ahn Soon-Cheol , Lee Jae-Dong , Bae Yoe-Sik , Kwak Jong-Young , Park Yeong-Min
Published: October 2004

Dendritic cells (DC) are known to not only induce the activation of T cells, but are also associated with the polarization of T cells. This study investigated whether or not proteoglycan (PG) isolated from Phellinus linteus induces the phenotypic and functional maturation of CD11c+ DC in vitro and in vivo. PG was found to induce the phenotypic and functional maturation of bone marrow‐derived DC via Toll‐like receptors (TLR) 2 and 4 in vitro. Administration of PG in vivo strongly inhibited the MCA‐102 tumor growth and increase in vivo. The ratio of CD8+ DC to CD8− DC increased, and PG enhanced IL‐12 and IFN‐γ production, and expression of surface molecules including major histocompatibility complexes (MHC) classes I, MHC II, CD80, and CD86 in MCA‐102‐challenged mice. PG also caused a marked increase in the production of Th (helper T cells)‐1 cytokine (IFN‐γ) and a decrease in the production of Th‐2 cytokine (IL‐4) by splenic cells and inguinal lymph node cells in MCA‐102 tumor‐bearing mice. Furthermore, PG stimulated the proliferation of CD4+ and CD8+ T cells. In addition, a combination of PG and tumor lysate‐pulsed DC inhibited completely the growth of MCA‐102 cells in tumor‐bearing mice. These results indicate that the administration of PG inhibited the tumor growth through a mechanism leading to a Th‐1 dominant immune state and the activation of CD11c+CD8+ DC.
A kunitz‐type protease inhibitor bikunin disrupts ligand‐induced oligomerization of receptors for transforming growth factor (TGF)‐β and subsequently suppresses TGF‐β signalings
Authors: Yagyu Tatsuo , Kobayashi Hiroshi , Wakahara Kiyoshi , Matsuzaki Hidenori , Kondo Toshiharu , Kurita Noriyuki , Sekino Hideo , Inagaki Kiyokazu , Suzuki Mika , Kanayama Naohiro , Terao Toshihiko
Published: October 2004

We previously found that bikunin (bik), a Kunitz‐type protease inhibitor, suppresses transforming growth factor‐β1 (TGF‐β1)–stimulated expression of urokinase‐type plasminogen activator (uPA) in human ovarian cancer cells that lack endogenous bik. In the present study, we tried to elucidate the mechanism by which bik also inhibits plasminogen activator inhibitor type‐1 (PAI‐1) and collagen synthesis using human ovarian cancer cells. Here, we show that (a) there was an enhanced production of both uPA and PAI‐1 in HRA cells in response to TGF‐β1; (b) the overexpression of bik in the cells or exogenous bik results in the inhibition of TGF‐β1 signaling as measured by phosphorylation of the downstream signaling effector Smad2, nuclear translocation of Smad3, and production of PAI‐1 and collagen; (c) bik neither decreased expression of TGF‐β receptors (TβRI and TβRII) in either cell types nor altered the specific binding of 125I TGF‐β1 to the cells, indicating that the effects of bik in these cells are not mediated by ligand sequestration; (d) TβRI and TβRII present on the same cells exclusively form aggregates in TGF‐β1‐stimulated cells; (e) co‐treatment of TGF‐β1–stimulated cells with bik suppresses TGF‐β1–induced complex formation of TβRI and TβRII; and (f) a chondroitin‐4‐sulfate side chain‐deleted bik (deglycosylated bik) does not inhibit TGF‐β1 signaling or association of type I/type II receptor. We conclude that glycosylated bik attenuates TGF‐β1–elicited signaling cascades in cells possibly by abrogating the coupling between TβRI and TβRII and that this probably provides the mechanism for the suppression of uPA and PAI‐1 expression.
Effect of water table drawdown on northern peatland methane dynamics: Implications for climate change
Authors: Strack M. , Waddington J. M. , Tuittila E.‐S.
Published: October 2004

As natural sources of methane (CH4), peatlands play an important role in the global carbon cycle. Climate models predict that evapotranspiration will increase under a 2 × CO2 scenario due to increased temperatures leading to lowered water tables at many northern latitudes. Given that the position of the water table within a peatland can have a large effect on CH4 emissions, climate change may alter the CH4 emissions from peatlands in this area. Research was conducted during 2001–2003 on natural and drained (8 years prior) sites within a poor fen in central Quebec. Flux measurements were made for each site at different microtopographical features that varied in depth to water table and vegetation cover. The quantity of CH4 dissolved in the pore water was measured in the field and the potential of the peat for CH4 production and consumption was determined in the laboratory. Methane emissions and storage were lower in the drained fen. Growing season CH4 emissions at the drained site were 55% lower than the control site, primarily due to significantly reduced fluxes from topographic highs (up to 97% reduction), while the flux from topographically low areas remained high. The maintenance of high fluxes at these hollow sites was related to hydrological and ecological effects of the water table drawdown. The removal of standing water removed a potential zone of CH4 oxidation. It also enabled plant colonization at these locations, leading to an increase in gross ecosystem photosynthesis (GEP). At the hollow sites, seasonal CH4 emissions were significantly correlated to seasonal GEP (R2 = 0.85). These results suggest that the response of northern peatland CH4 dynamics to climate change depends on the antecedent moisture conditions of the site. Moreover, ecological succession can play an important role for determining future CH4 emissions, particularly from wetter sites.
Calculation of river discharge and prediction of lake height from satellite radar altimetry: Example for the Lake Chad basin
Authors: Coe Michael T. , Birkett Charon M.
Published: October 2004

The application of satellite radar altimetry to the determination of lake and river elevations has been used in numerous projects, and is well validated. Here we show that with the aid of ground‐based information, this technique can be extended to determine river discharge and predict downstream lake and marsh height. The Lake Chad basin provides an ideal case study due to its well‐known hydrology and complex lake and marsh morphology and because prediction of lake and marsh height has been identified as potentially useful to people living in the region. Altimetric stage measurements from the TOPEX/Poseidon satellite, at the Chari/Ouham confluence, estimate river discharge about 500 km downstream at N'Djamena 10 days in advance (r2 = 0.9562). Via simple linear correlation methods, the stage measurements successfully estimate the height of the permanent waters of the lake (600 km downstream) 39 days in advance (r2 = 0.9297). Predicting the water height on the western marshes of the lake bed is poorer (r2 = 0.7958) due to a change in response time of the local stage to the seasonal floods coincident with an observed increase in mean water level in the latter half of the 1990s. Before 1997 a 96‐day phase lag results in the best fit (r2 = 0.6463). After 1997 the best fit is obtained with a 66‐day phase lag (r2 = 0.8139). The excellent river discharge and lake height predictions show that altimetry is a useful tool where ground‐based data are difficult to obtain and where rapid water resource assessment is desirable.
A new look at homogeneous freezing of water
Authors: Baker M. B. , Baker M.
Published: October 2004

Despite its atmospheric importance, homogeneous freezing of aqueous drops is poorly understood. Here we provide evidence that at atmospheric pressures the conditions leading to the initiation of freezing in pure water are those for which the liquid compressibility and the corresponding density fluctuations reach maxima. This liquid‐only criterion for the onset of freezing contrasts with the traditional view that freezing temperatures depend sensitively on the parameters of ice and the ice‐water interface. We generalize the connection between compressibility maxima and freezing to aqueous solutions. Utilizing compressibility data, we predict solution freezing temperatures from those of pure water under pressure. These predictions are almost coincident with the parameterizations of droplet freezing temperatures in terms of water activity [Koop et al., 2000] used to predict ice formation in cirrus clouds. Our work then provides a physical basis for this link between water activity in solution and homogeneous freezing temperatures.
Recent eruptive history of Stromboli (Aeolian Islands, Italy) determined from high‐accuracy archeomagnetic dating
Authors: Arrighi Simone , Rosi Mauro , Tanguy Jean‐Claude , Courtillot Vincent
Published: October 2004

The “large sample method” of archeomagnetic dating was applied to Stromboli. 127 samples (10 sites) yielded paleofield directions with 95% confidence intervals less than 2°. Coupled with a reference curve for secular variation in western Europe, these allow accurate dating of volcanic events. A lava flow underlying San Bartolo village gave a minimum age of AD 100 (±100); a lava overflow predating the last sector collapse was dated from 1350 (±60), suggesting the recent occurrence of highly hazardous events. Lava spatters and a hot avalanche high on the northern flank were emplaced during the XXth century; lava spatters on the lower flanks could date the onset of the still‐ongoing phase from AD 550 (±50). These results are different from those obtained in a recent study, probably because traditional paleomagnetic sampling cannot yield sufficient precision, considering the characteristics of the archeomagnetic secular variation curve.
An estimate of the global distribution of radon emissions from the ocean
Authors: Schery S. D. , Huang S.
Published: October 2004

There is a need for improved estimates of the radon (222Rn) flux density from the ocean for use in the modeling and interpretation of atmospheric radon in global climate and air pollution studies. We use a modification of a frequently used model of gas transfer to generate global predictions of ocean radon flux density for each month of the year (climate averaged) on a 192 by 94 global grid. Compared with the often‐used approximation of a constant radon flux from the ocean, the model's predictions indicate large variations over regions of the ocean (a factor of ten is not uncommon). For example, latitude bands near the equator and Southern Ocean are predicted to emit relatively high average radon flux compared with other latitude bands. The predicted annually‐averaged flux density from the ocean is 0.0382 mBq m−2 s−1 (0.00182 atoms cm−2 s−1), smaller than some commonly‐used estimates.
Generation region of pulsating aurora obtained simultaneously by the FAST satellite and a Syowa‐Iceland conjugate pair of observatories
Authors: Sato N. , Wright D. M. , Carlson C. W. , Ebihara Y. , Sato M. , Saemundsson T. , Milan S. E. , Lester M.
Published: October 2004

We have carried out a direct comparison of pulsating auroras observed from the ground at Syowa Station in Antarctica and on board the FAST satellite (∼3100 km altitude), with reference to simultaneous data obtained by a Syowa‐Iceland conjugate pair of observatories. The aurora at Syowa appeared as east‐west aligned bands consisting of two different types: a poleward moving oscillation and a standing oscillation, each with a period of ∼6 s. Spatial and temporal variations of the downgoing high‐energy (>5 keV) electron flux obtained by FAST showed a one‐to‐one correspondence with the optical pulsating aurora. The occurrence regions of the two different types of pulsating aurora were separated by a narrow gap (∼7–10 km in width at 100 km altitude) in the inverted‐V structure, and the gaps were colocated with the small‐scale upward field‐aligned currents. The time‐varying magnetic fields (upward field‐aligned current) observed by FAST were almost correlated (in‐phase) with the downgoing electron flux (>5 keV) modulations. Both the optical emission intensity at Syowa and the downgoing high‐energy electron flux (>7 keV) on board FAST showed ∼3 Hz modulation. The ∼3 Hz fine structure constituted the main body of the ∼6 s pulsating aurora. VLF wave activities were not observed by FAST in the region of pulsating aurora. The source regions of the generation or modulation of the energetic particles are estimated to be at a higher altitude than FAST, in the region of ∼2 Re to 6 Re from the satellite. This suggests that the source region is not located in the equatorial plane of the magnetosphere but is located earthward, far from the equatorial plane. The conjugate pair observations on the ground revealed that the aurora, though pulsating in both hemispheres, was not conjugate in shape, appearing as an east‐west aligned band in the Southern Hemisphere but as a torch structure (omega band) in the Northern Hemisphere. The evidence presented in this study suggests that ionosphere‐magnetosphere coupling processes are important in producing the pulsating aurora.
Self‐potential signals associated with pumping tests experiments
Authors: Rizzo E. , Suski B. , Revil A. , Straface S. , Troisi S.
Published: October 2004

The flow of groundwater during a pumping test experiment is responsible for a measurable electrical field at the ground surface owing to the electrokinetic coupling between the Darcy velocity and the electrical current density. This electrical field can be measured passively with a network of nonpolarizable electrodes connected to a digital multichannel multimeter with a high internal impedance (>10 Mohm). These so‐called self‐potential signals can be used to track the pattern of groundwater flow in the subsurface. A field test was performed using a set of 53 Pb/PbCl2 electrodes plus an additional electrode used as a unique reference in the field and a set of five piezometers to monitor the position of the piezometric surface. Using appropriate Green's functions, the electrical response is analyzed in terms of piezometric head distribution. This new methodology, which we call “electrography,” allows visualization of preferential fluid flow pathways and the distribution of heads during pumping test experiments. Using a conditioning technique, this method could allow inversion of the hydraulic conductivity distribution around a pumping well.
Application of pollen analysis to dating of ice cores from lower‐latitude glaciers
Authors: Nakazawa Fumio , Fujita Koji , Uetake Jun , Kohno Mika , Fujiki Toshiyuki , Arkhipov Serguei M. , Kameda Takao , Suzuki Keisuke , Fujii Yoshiyuki
Published: October 2004

Ice cores from temperate regions have long been expected to be useful for understanding local climate trends, but a reliable dating method has proved difficult. Here we show that measurements of pollen using samples with only 10 mL of water can give an accurate measure of the annual ice accumulation. In addition, two major types of pollen allow us to estimate the summer ice accumulation as well as the annual accumulation.
Conservative and sorptive forced‐gradient and uniform flow tracer tests in a three‐dimensional laboratory test aquifer
Authors: Fernàndez‐Garcia Daniel , Illangasekare Tissa H. , Rajaram Harihar
Published: October 2004

Forced‐gradient tracer tests (FGTTs) and uniform flow tracer tests (UFTTs) were conducted in a unique physically and chemically highly heterogeneous three‐dimensional test aquifer to study the differences in the scale dependence and spatial variability of dispersivity and retardation factors estimated from temporal moments of breakthrough curves due to changes in the flow configuration and source sizes. It is experimentally shown that the distance scales at which dispersivities from FGTTs approach a constant value are larger than those from UFTTs. These discrepancies are largely emphasized when dispersivities from small‐source FGTTs are compared with those from large‐source UFTTs. Remarkably, point source FGTTs showed a late but substantial scale dependence of dispersivity. In practice, at usual field test scales (few spatial correlation scales), dispersivities estimated from small source FGTTs will significantly underestimate those needed to make predictions on the fate and transport of tracer plumes under natural gradients. Nonetheless, at large distances, asymptotic dispersivities from large source FGTTs were similar to those from large source UFTTs. A negative correlation between R and lnK developed an increase in dispersivities for reactive tracers in both uniform and forced‐gradient flow systems. Whereas in uniform flows retardation factors showed a decreasing scale dependence with distance approaching the arithmetic average of the retardation factor field at large distances, retardation factors from FGTTs exhibited a strong increasing scale dependence. Spatial variability of dispersivities and retardation factors estimated from FGTTs were larger than those from UFTTs.
Electron cyclotron emission radiometer upgrade on the Joint European Torus (JET) tokamak
Authors: Luna E. de la , Sánchez J. , Tribaldos V. , contributors JET-EFDA , Conway G. , Suttrop W. , Fessey J. , Prentice R. , Gowers C. , Chareau J. M.
Published: October 2004

The capabilities of the Joint European Torus (JET) electron cyclotron emission (ECE) diagnostics have recently been extended with an upgrading of the heterodyne radiometer. The number of channels has been doubled to 96 channels, with a frequency separation corresponding to <1 cm for JET magnetic field gradient, and with a frequency response of 1 MHz. This enhancement has increased the radial coverage of the ECE electron temperature measurements in JET to approximately the full plasma column (limited at R>2.6 m for the X-mode due to harmonic overlap) at almost all magnetic field values used at JET (1.7 T<BT<4 T), while maintaining the high sensitivity and spectral resolution of the previous system. In this paper an overview of the upgraded radiometer is presented along with some results showing its performance.
Development of M-shell x-ray spectroscopy and spectropolarimetry of z-pinch tungsten plasmas
Authors: Shlyaptseva A. , Fedin D. , Hamasha S. , Harris C. , Kantsyrev V. , Neill P. , Ouart N. , Safronova U. I. , Beiersdorfer P. , Boyce K. , Brown G. V. , Kelley R. , Kilbourne C. A. , Porter F. S.
Published: October 2004

The development of spectroscopic modeling of M-shell tungsten z-pinch plasma is presented. The spectral region from 3.5 to 6.5 Å includes three distinct groups of transitions, and the best candidates for M-shell diagnostics are identified. Theoretical modeling is benchmarked with LLNL electron beam ion trap data produced at different energies of the electron beam and recorded by crystal spectrometers and a broadband microcalorimeter. A new high temperature plasma diagnostic tool, x-ray spectropolarimetry, is proposed to study polarization of W line emission and is illustrated using the results of x-pinch polarization-sensitive experiments. The x-ray line polarization of the prominent M-shell tungsten lines is calculated, and polarization markers are identified. The advantage of using x-pinch W wire experiments for the development of M-shell diagnostics is shown.
Velocity and metastable state population distributions of laser-ablated neodymium
Authors: Wang Haiming , Miyatake Hiroari , Ohba Hironori , Saeki Morihisa , Miyabe Masabumi , Shibata Takemasa , Iimura Hideki
Published: October 2004

Laser-induced fluorescence spectroscopy has been employed to characterize a plume produced in nanosecond laser ablation of metallic neodymium. Kinetic energy distributions of ions and neutrals in the plume were investigated as functions of processing parameters such as laser fluence and ambient gas pressure. Population distributions of metastable levels in the ablated atoms were also measured. These investigations provide preliminary data for the design of a new type of resonance photo-ionization laser ion source.
Influence of antenna aiming on ECE in MAST
Authors: Preinhaelter Josef , Urban Jakub , Pavlo Pavol , Shevchenko Vladimir , Valovič Martin , Vahala Linda , Vahala George
Published: October 2004

The effect of the direction of the detected beam on the intensity of ECE is studied. It is found that the combined effects of the strong dependence of the conversion efficiencey of O mode at the plasma resonance on the direction of the incident wave and the partial screening of the beam waist by the MAST vessel wall, can be responsible for the weakening of ECE emission for some frequencies. The theoretical model for ECE data interpretation on MAST has been significantly improved. New features of the model are as follows: the quasioptical treatment of the receiving antenna, interference, polarization and screening effects of the vacuum window and collisional damping of EBWs in the peripheral plasma.
Plasma resistivity profile measurement from an external radio-frequency magnetic coil
Authors: Slough John T. , Andreason Samuel P. , Milroy Richard D.
Published: October 2004

Plasma resistivity is obtained by measuring the change in circuit behavior from a simple loop placed externally to the plasma. The loop is part of a series-driven oscillator that can be tuned over a wide range of frequencies with a very low internal impedance. By varying the frequency, and observing both the detuning and loading of this circuit, the location and resistance of the screening currents can be determined. A two-dimensional resistive magnetohydrodynamic code calculation is performed to obtain both the plasma interaction with the oscillating field as well as the effects of nearby conductors. The plasma resistance in the numerical calculations is adjusted to match the data from the experiment and, in this way, obtain a measure of the plasma resistivity profile.
X-mode reflectometry for magnetohydrodynamic activity associated with q=1 surface measurements on Tore Supra
Authors: Vermare L. , Clairet F. , Gabillet F. , Sabot R. , Sirinelli A. , Heuraux S. , Leclert G.
Published: October 2004

Tore Supra is equipped with two 20 μs fast sweep X-mode reflectometers operating between 50–110 GHz dedicated to density profile determination and an X-mode fixed frequency reflectometer operating between 105–155 GHz for density fluctuation measurements. Heterodyne and sine–cosine detection provide measurements of the reflected signal with high sensitivity. Operating profile reflectometer in burst mode (5 μs dead time between two consecutive sweeps) allows quasi-simultaneous measurements at fixed frequency over a broad frequency band. Thus, information on plasma fluctuations, such as magnetohydrodynamic (MHD) activity, up to 20 kHz as well as a radial localization of the modes is accessible. The temporal evolution of the q=1 rational surface during sawtooth crash activity has been recorded in the plasma center with high spatial resolution. In addition, a direct comparison between signals associated with a central MHD mode from both profile and fluctuation reflectometers, positioned at different toroidal angles, allows one to determine the plasma toroidal velocity.
Upgrade of the X-mode reflectometry diagnostic for radial correlation measurements in the Joint European Torus
Authors: Hacquin S. , Meneses L. , Cupido L. , Cruz N. , Kokonchev L. , Prentice R. , Gowers C.
Published: October 2004

The recent upgrades and the potential of the X-mode reflectometry diagnostic on the Joint European Torus (JET), dedicated to measurement of the turbulence radial correlation length, are presented in this article. The reflectometer system now consists of four independent heterodyne instruments working at different probing frequencies, which in principle enables analysis of the density fluctuations at four distinct radial regions in the plasma. A VERSA Module Eurocard-based computer connected to the JET database computer system is used to control all of the diagnostic in particular the frequency of the tunable sources and frequency of the fast acquisition boards. The diagnostic is fully operated by remote control. A study of the effects of type-I edge localized modes observed at JET illustrates its potential. The main limitation comes from the low quality of the transmission lines, which leads to a strong attenuation of the signal and makes the measurements difficult especially in the plasma core. To reach higher performances, new low attenuation corrugated circular waveguides (with an expected gain of 20 dB) will be installed in the summer of 2004 during the JET shutdown.
Design of an X-mode swept frequency modulation reflectometer for the measurement of KSTAR plasma density profiles (invited)
Authors: Roh Y. , Domier C. W. , Luhmann N. C.
Published: October 2004

An X-mode swept frequency modulation (FM) reflectometry system has been designed to measure the electron density profiles of the “initial” KSTAR plasma. Fast swept HTO oscillators are employed to avoid density fluctuation effects, and frequency quadruplers are utilized to expand the HTO frequency range of 8–18 GHz to completely cover the X-mode cutoff frequency range of 33–66 GHz. The system can also be utilized to measure the edge profiles of the “Day One” KSTAR plasma by either switching from X- to O-mode reflectometry or by employing higher frequency millimeter-wave components and retaining the X-mode reflectometry configuration. To facilitate engineering design and optimization, a 3D drawing tool is utilized to effectively deal with any technical problems that may happen under actual KSTAR conditions. Details of the KSTAR FM reflectometry system are described together with important design issues.
10
kHz
repetitive high-resolution TV Thomson scattering on TEXTOR
Authors: van der Meiden H. J. , Barth C. J. , Oyevaar T. , Varshney S. K. , Donné A. J. H. , Kantor M. Yu. , Kouprienko D. V. , Alexeev A. , Biel W. , Pospieszczyk A.
Published: October 2004

In December 2003 a new 10 kHz multiposition Thomson scattering diagnostic with high spatial resolution has become operational on the TEXTOR tokamak. The system is the follow up of the high-resolution double-pulse Thomson scattering diagnostic. The conventional ruby laser has been replaced by a 10 kHz intracavity laser system and the spectrometer detector has been upgraded with two ultrafast complementary metal–oxide–semiconductor cameras combined with a special image intensifier stage. In the initial phase of operation, a burst of 18 pulses decaying from 17 to 8 J, with a repetition rate of 5 kHz, could be extracted from the laser. At a laser energy up to 12 J per pulse, ten electron temperature and density profiles were measured with an observational error of 10% on the electron temperature (Te) and 5% on the electron density (ne) at ne=2.5×1019 m−3 per spatial element of 12 mm. The resolution of the detection optics enables to sample either the full plasma diameter of 900 mm with 120 spatial channels of 7.5 mm each, or a 160 mm long edge chord with 98 spatial channels of 1.7 mm each.
Electron cyclotron emission as a density fluctuation diagnostic
Authors: Lynn A. G. , Phillips P. E. , Hubbard A.
Published: October 2004

A new technique for measuring density fluctuations using a high-resolution heterodyne electron cyclotron emission (ECE) radiometer has been developed. Although ECE radiometry is typically used for electron temperature measurements, the unique viewing geometry of this system’s quasioptical antenna has been found to make the detected emission extremely sensitive to refractive effects under certain conditions. This sensitivity gives the diagnostic the ability to measure very low levels of density fluctuations in the core of Alcator C-Mod tokamak. The refractive effects have been modeled using ray-tracing methods, allowing estimates of the density fluctuation magnitude and spatial localization.
Design, construction, and performance of a composite mirror for collecting Thomson scattered light from the large helical device plasma
Authors: Narihara K. , Yamada I. , Hayashi H. , Yamauchi K.
Published: October 2004

A 1.5 m×1.8 m rectangular composite mirror composed of 138 segment hexagonal spherical mirrors was constructed for collecting Thomson scattered light from the Large Helical Device plasma. The hexagonal mirrors with side length of 87 mm were patched on the surface of a framework made of glass fiber reinforced plastic. The position and angular orientation of each mirror are adjusted with three pairs of push-and-pull screws attached to the back plane of the mirrors so that the image of a tiny light source (0.1 mm in diameter) formed by each segment mirror be minimized and coincide with each other on a charge coupled device plate. The optical quality and its long-term stability of the assembled mirror have been monitored and sufficient for the present purpose.
Doppler backscattering system for measuring fluctuations and their perpendicular velocity on Tore Supra
Authors: Hennequin P. , Honoré C. , Truc A. , Quéméneur A. , Lemoine N. , Chareau J.-M. , Sabot R.
Published: October 2004

Backscattering of a microwave beam launched in oblique incidence makes possible measurement of density fluctuations close to the cut-off with a selected wave number k⃗⊥=−2k⃗i, where k⃗i is the beam wave vector at the reflection layer. On the system installed on Tore Supra, the incidence of the Gaussian beam is controlled thanks to a tiltable monostatic antenna. The microwave part of the system is based on a fluctuation reflectometer scheme with heterodyne detection, and the choice of a V band (50–75 GHz) microwave source and O mode polarization is appropriate for typical enhanced plasma regimes (n0=3–7×1019 m−3). Both the scattering wave number k⊥ and the scattering localization r/a can be changed during a shot, owing to the steppable probing frequency and the motorized antenna (tilt angle 0–10°). The wave-number range k⊥ is 4–15 cm−1, with a wave-number resolution around 2 cm−1, and the localization r/a∼0.3–0.85. The Doppler effect also provides the perpendicular velocity profile for the same position range. Experiments confirm the diagnostic capabilities.
Frequency modulation continuous wave reflectometry measurements of plasma position in ASDEX Upgrade ELMy H-mode regimes
Authors: Santos J. , Hacquin S. , Manso M. ,   ASDEX Upgrade Team
Published: October 2004

Plasma position measurements of frequency modulation continuous wave reflectometry are analyzed in ASDEX Upgrade ELMy H-mode regimes [International Thermonuclear Energy Reactor (ITER) reference scenario], to assess the viability of using reflectometry for position and shape control purposes in ITER. Plasma separatrix position is estimated both at the low and high field sides of the tokamak. A scaling factor applied to the linear average density (an ITER online measurement) is used to estimate the separatrix density, whose position is then tracked using reflectometry profile measurements. Edge localized mode (ELM) activity effects are overcome by disregarding measurements performed during the onset and magnetohydrodynamic phases of the ELMs. Position data is compared, with data derived from the magnetics and its quality is assessed using one dimensional full-wave numerical simulations, taking into account the influence of the nonprobed edge plasma region (O-mode operation) and of the plasma turbulence. Results indicate that selecting an adequate scaling to the linear average density leads to a good estimate of the separatrix position, even when the pedestal is out of the measuring range, which will be the case of ITER position reflectometer.
Effects of asymmetry and target location on microwave imaging reflectometry
Authors: Ignatenko M. , Mase A. , Bruskin L. G. , Kogi Y. , Hojo H.
Published: October 2004

In this article we perform a numerical study of microwave imaging reflectometry (MIR) and compare it with conventional reflectometry system. As an approximation to the reflections by real plasma fluctuations, a corrugated wheel is used. As far as general performance is concerned, our simulations confirm the results by Munsat et al. [Plasma Phys. Controlled Fusion 45, 469 (2003)] that the MIR system reproduces shape of corrugation far from the wheel while conventional systems fail to do so. We addressed the effects of asymmetry and defocusing of the wheel-reflectometer system as well as spectral sensitivity of the imaging reflectometer. For a particular geometry we estimated the deterioration of the MIR performance due to misalignments and existence of broadband fluctuations.
Microwave scattering system design for ρe scale turbulence measurements on NSTX
Authors: Smith D. R. , Mazzucato E. , Munsat T. , Park H. , Johnson D. , Lin L. , Domier C. W. , Johnson M. , Luhmann N. C.
Published: October 2004

Despite suppression of ρi scale turbulent fluctuations, electron thermal transport remains anomalous in NSTX. For this reason, a microwave scattering system will be deployed to directly observe the ω and k spectra of ρe scale turbulent fluctuations and characterize the effect on electron thermal transport. The scattering system will employ a Gaussian probe beam produced by a high power 280 GHz microwave source. A five-channel heterodyne detection system will measure radial turbulent spectra in the range |kr|=0–20 cm−1. Inboard and outboard launch configurations cover most of the normalized minor radius. Improved spatial localization of measurements is achieved with low aspect ratio and high magnetic shear configurations. This article will address the global design of the scattering system, such as choice of frequency, size, launching system, and detection system.
Filter-fluorescer diagnostic system for the National Ignition Facility
Authors: McDonald J. W. , Kauffman R. L. , Celeste J. R. , Rhodes M. A. , Lee F. D. , Suter L. J. , Lee A. P. , Foster J. M. , Slark G.
Published: October 2004

An early filter-fluorescer diagnostic system is being fielded at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) to measure the amount of hard x rays (20<hν<150 keV) generated in laser fusion experiments. From these measurements we hope to quantify the number of hot electrons produced in laser fusion experiments. The measurement of hot electron production is important for ignition experiments because these electrons can preheat the fuel capsule. Hot electrons can also be employed in experimentation by preheating hydrodynamic packages or by driving plasmas out of equilibrium. The experimental apparatus, data collection, analysis and calibration issues are discussed. Expected data signal levels are predicted and discussed.
Dante soft x-ray power diagnostic for National Ignition Facility
Authors: Dewald E. L. , Campbell K. M. , Turner R. E. , Holder J. P. , Landen O. L. , Glenzer S. H. , Kauffman R. L. , Suter L. J. , Landon M. , Rhodes M. , Lee D.
Published: October 2004

Soft x-ray power diagnostics are essential for measuring the total x-ray flux, radiation temperature, conversion efficiency, and albedo that define the energetics in indirect and direct drive, as well as other types of high temperature laser plasma experiments. A key diagnostic for absolute radiation flux and radiation temperature in hohlraum experiments is the Dante broadband soft x-ray spectrometer. For the extended range of x-ray fluxes predicted for National Ignition Facility (NIF) compared to Omega or Nova hohlraums, the Dante spectrometer for NIF will include more high energy (<2 keV) edge filter band-pass channels and access to an increased dynamic range using grids and signal division. This will allow measurements of radiation fluxes of between 0.01 to 100 TW/sr, for hohlraum radiation temperatures between 50 eV and 1 keV. The NIF Dante will include a central four-channel imaging line-of-sight to verify the source size, alignment as well as checking for any radiation contributions from unconverted laser light plasmas.
X-ray spectroscopy with elliptical crystals and face-on framing cameras
Authors: Heeter R. F. , Emig J. A. , Fournier K. B. , Hansen S. B. , May M. J. , Young B. K. F.
Published: October 2004

X-ray spectrometers using elliptically bent crystals have desirable properties for applications requiring broad spectral coverage, good spectral resolution, and minimized source broadening. Previous work used custom-positioned film or microchannel plate detectors. We find it is also useful and cost-effective to field elliptical crystals in existing snouts on the face-on gated microchannel plate framing cameras commonly used at many facilities. We numerically explored the full design space (spectral range and resolution) of elliptical crystals compatible with the new multipurpose spectrometer snout. We have tested at the Omega laser an elliptical rubidium acid phthalate crystal with 174 mm focal length, 0.9885 eccentricity, and 4.6° inclination, viewing from 1.0 to at least 1.7 keV with spectral resolution E/dE of 300–500. A slit (2×magnification) images 3 mm sources with 70 μm spatial resolution.
Diagnostics for edge pedestal research (invited)
Authors: Leonard A. W.
Published: October 2004

Edge pedestal research in magnetic plasma confinement devices requires measurements which span multiple spatial and temporal scales and include a number of physical processes. Research seeks to optimize the height of the pedestal for maximum confinement, but to avoid large repetitive particle and heat loads in the divertor as a consequence of edge localized modes (ELMs). In this complex region, transport physics, fueling by neutrals, stability physics, and the physics of the self-driven bootstrap current all play key roles. To develop an understanding of the pedestal region, detailed physics measurements of the local gradients, neutral fueling, the turbulence spectra, and the magnetohydrodynamic characteristics are needed with both fine spatial and temporal resolution. Finally, development of two-dimensional and three-dimensional imaging of the ELM evolution would greatly aid in understanding ELM transport.