bluuebunny/crossref_metadata_2025 huggingface dataset:
High throughput approaches in neuroscience
Authors: Morris C.M. , Wilson K.E.
Published: October 2004

Traditional approaches to understanding biological problems are now being advanced with the use of high throughput technologies, which analyse multiple samples simultaneously, or thousands of analytes in a single sample. The application of these technologies in neurochemistry and neuroscience is beginning to be explored and is assisting in the development of new models of drug action, neuroanatomical investigations, and in identifying molecular pathways involved in neurological and psychiatric disease. Tools such as microarray‐based gene expression profiling and 2D and multidimensional proteomic methods are uncovering functional components to a wide variety of neuroscience paradigms and the application of these technologies is set to become standard in analysis.
Strategies to prevent eclampsia in a developing country: II. Use of a maternal pictorial card
Authors: MacGillivray I. , McCaw‐Binns A.M. , Ashley D.E. , Fedrick A. , Golding J.
Published: October 2004

Objective: To assess the efficacy and acceptability of a patient‐held pictorial card aimed at raising awareness and appropriate health seeking behavior in response to prodromal symptoms of imminent eclampsia. Method: Pictorial cards (and posters) were issued to antenatal clinics and used to focus instruction and advice to pregnant women. Mothers were surveyed before and after the cards were introduced to assess maternal likelihood of seeking care if edema was seen, and of attending hospital if so advised. We monitored the eclampsia rate. Health workers were interviewed 6 months after cards and posters were issued to determine the acceptability of using the cards as part of routine antenatal care. Results: The card was seen as widely acceptable by health professionals, and increased their own awareness of the prodromal symptoms of eclampsia and their discussion of these symptoms with antenatal mothers. Mothers' awareness and response to symptoms improved significantly and there was a marked drop in eclampsia incidence. Suggested improvements to the card were made by mothers and health workers. Conclusion: The cost of providing a card for every pregnant mother is likely to be offset by health service delivery savings.
Ultrasonographic evaluation of lower uterine segment thickness in patients of previous cesarean section
Authors: Sen S. , Malik S. , Salhan S.
Published: October 2004

Objective

To evaluate by ultrasonography, the lower uterine segment thickness of women with a previous cesarean delivery and determine a critical thickness above which safe vaginal delivery is predictable.

Methods

A prospective observational study of 71 antenatal women with previous cesarean delivery and 50 controls was carried out. Transabdominal and transvaginal ultrasonography were used in both groups to evaluate lower uterine segment thickness. The obstetric outcome in patients with successful vaginal birth and intraoperative findings in women undergoing cesarean delivery were correlated with lower segment thickness.

Results

The overall vaginal birth after cesarean section (VBAC) was 46.5% and VBAC success rate was 63.5%, the incidence of dehiscence was 2.82%, and there were no uterine ruptures. There was a 96% correlation between transabdominal ultrasonography with magnification and transvaginal ultrasonography. The critical cutoff value for safe lower segment thickness, derived from the receiver operator characteristic curve, was 2.5 mm.

Conclusion

Ultrasonographic evaluation permits better assessment of the risk of scar complication intrapartum, and could allow for safer management of delivery.
Prostatic carcinoma causing urethral obstruction and obstipation in a cat
Authors: LeRoy Bruce E. , Lech Margaret E.
Published: October 2004

A 9-year-old intact male cat was presented for vomiting and straining to defecate. A large abdominal mass was palpated. The urinary bladder was full and non-expressible. Exploratory laparotomy revealed that the mass was compressing the colon and encircling the urethra caudal to the bladder. The mass was removed, the urethra transected, and the urinary bladder marsupialized to the ventral abdominal wall to allow urine drainage. Histopathologic examination of the mass revealed a prostatic carcinoma. The cat died approximately 6 weeks after removal of the mass. This is the first reported case of a prostatic carcinoma causing urethral obstruction and obstipation in a cat.
Tropopause folding at satellite‐observed spatial gradients: 1. Verification of an empirical relationship
Authors: Wimmers A. J. , Moody J. L.
Published: October 2004

Tropopause folding, a mechanism for stratosphere/troposphere exchange (STE), can be detected indirectly from strong spatial gradients in two satellite‐derived products that are primarily sensitive to tropopause height: the altered water vapor product, developed from the GOES water vapor channel; and the Total Ozone Mapping Spectrometer level 2 total ozone product. The images were preprocessed with an optimized smoothing algorithm that filtered out gradients at spatial scales of less than ∼30 km. This removed jagged, fine‐scale edges in the moisture fields and helped emphasize upper tropospheric air mass boundaries and dry air “streamers,” which are both associated with STE. In the verification data set, 13 out of 14 tropopause folds identified by an airborne lidar were correctly distinguished by the technique with no false positives. These results have been applied in an empirical model over the midlatitudes to predict spatial and temporal patterns in tropopause folding.
Effects of Miyake volcanic effluents on airborne particles and precipitation in central Japan
Authors: Satsumabayashi Hikaru , Kawamura Minoru , Katsuno Takao , Futaki Katsumi , Murano Kentaro , Carmichael Gregory R. , Kajino Mizuo , Horiguchi Mitsuaki , Ueda Hiromasa
Published: October 2004

Miyake volcano, which is located in the northwest Pacific Ocean 200 km south of the Tokyo metropolitan area, began to erupt on 8 July 2000. Its SO2 emission amounted to a maximum of 6 × 104 t d−1, which was about the same level as the anthropogenic emission of northeast Asia and 20 times larger than that of Japan, and is decreasing to 104 t d−1. Aerosol and precipitation, together with gaseous pollutants, have been observed from 2 years before the eruption to present on a prominent mountain ridge, Happo ridge (330 km north of the volcano). Short time samplings of aerosols and gaseous acids, such as HCl and HNO3, were made for 3–6 hours every day. Annual mean concentration of SO2 was increased 3.8 times, and concentrations of SO42− were increased 1.5 and 1.7 times in aerosol and precipitation, respectively. In contrast, aerosol concentrations of NO3− and Cl− decreased under the influence of volcanic effluents. This was caused by the excess amount of SO42− formation. The produced SO42− at first exhausted gaseous ammonia to form (NH4)2SO4 aerosol and then, driving out NO3− and Cl−, it took their place in the aerosol and sometimes existed as sulfuric acid mist after exhausting ammonia. These facts were explained successfully by a multicomponent gas‐aerosol equilibrium. The expelled HNO3 and HCl might be deposited more intensively both by wet and dry deposition processes and might accelerate the environmental acidification.
Active tectonics and late Cenozoic strain distribution in central and eastern Iran
Authors: Walker Richard , Jackson James
Published: October 2004

Right‐lateral shear between central Iran and Afghanistan is accommodated on N–S right‐lateral strike‐slip faults surrounding the aseismic Dasht‐e‐Lut. North of ∼34°N, the right‐lateral shear is accommodated on left‐lateral faults that rotate clockwise about vertical axes. Little is known of the late Tertiary and younger offsets and slip rates on the active fault systems, results that are important for understanding the regional tectonics. We use observations from satellite imagery to identify displaced geological and geomorphological markers, which we use in conjunction with the overall morphology and orientation of the active fault systems to estimate the total cumulative right‐lateral shear. Estimates of cumulative fault movements from offset features and inferred vertical axis rotation of fault‐bounded blocks suggest that the late Cenozoic strain is concentrated toward the eastern margin of Iran, along the Sistan shear zone, where bedrock offsets of at least 70 km are observed across the active faults. The geomorphology of the Deh Shir, Anar, and Great Kavir strike‐slip faults in central Iran suggest that although little shortening is accommodated across this region, they might still be active, and hence capable of producing earthquakes. Present‐day activity on these faults in central Iran would not be expected from distributions of instrumental and historical earthquakes. Although speculative, the late Tertiary strain distribution described in this paper is consistent with what we know of the present‐day rates of shear in eastern Iran and provides a framework to which later, more detailed, work can be added.
Impact of nesting strategies in dynamical downscaling of reanalysis data
Authors: Beck A. , Ahrens B. , Stadlbacher K.
Published: October 2004

Coarse–grid global numerical weather simulations or analysis data have to be downscaled, e.g., with nested limited–area models (LAMs), for regional interpretation. Here, the impact of different one–way nesting strategies on precipitation simulations over the European Alps with the LAM ALADIN is studied. The LAM is forced by initial and lateral boundary data derived from ERA40 reanalyses with 120 km horizontal gridspacing and 6 h update interval. The nesting strategies considered include relaxation–based techniques with direct nesting of the high–resolution LAM (horizontal gridspacing Δx = 12 km; domain size 2800 × 2500 km2) or double nesting with an intermediate–resolution nest (Δx = 50 km). Additionally, the impact of a spectral initialization technique is investigated. Results indicate that the considered nesting strategies are comparably successful in terms of precipitation simulation, despite the large resolution jump (120 to 12 km) involved. Thus, the cheapest method in terms of computational resources, i.e., direct nesting, seems to be the most adequate for dynamical downscaling of reanalysis data over complex terrain.
Infrasound from ocean waves observed in Tahiti
Authors: Le Pichon A. , Maurer V. , Raymond D. , Hyvernaud O.
Published: October 2004

The dominant source of infrasonic waves detected in Tahiti is associated with ocean swells generating permanent signals from 0.1 to several hertz. At thousands of kilometers from Tahiti, microbaroms are mainly produced by standing ocean waves near low‐pressure systems in the south Pacific. Their monitoring over one year exhibits clear seasonal trends correlated with changes in the prevailing stratospheric wind direction. More locally, ocean waves propagating towards Tahiti also generate surf noise when impacting against the reefs. Analyzing the infrasonic recordings, the main source regions of surf signals are identified and their locations and seasonal variations are discussed.
On using ocean swells for continuous infrasonic measurements of winds and temperature in the lower, middle, and upper atmosphere
Authors: Garcés M. , Willis M. , Hetzer C. , Le Pichon A. , Drob D.
Published: October 2004

The arrival azimuths of coherent microbarom signals observed in Hawaii during 2003 are associated with high ocean wave activity in the Pacific Basin, the dominant wind directions in the troposphere, stratosphere, and mesosphere, and the thermal structure of the atmosphere. Some of the seasonal trends in the microbarom observations can be explained by the winds in the stratosphere and lower mesosphere, while some of the daily variability can be explained by the winds in the troposphere and lower stratosphere. However, coherent energy from powerful swells may overcome the wind‐carried microbarom signals and arrive to the station through thermospheric ducting. Our observations suggest that either (1) the wind speeds in the troposphere, stratosphere and mesosphere may be underestimated in atmospheric models or (2) elevated leaky infrasonic waveguides are persistent propagation paths that should be investigated in more detail.
The correspondence between thermospheric neutral densities and broadband measurements of the total solar soft X‐ray flux
Authors: Eastes R. , Bailey S. , Bowman B. , Marcos F. , Wise J. , Woods T.
Published: October 2004

While it is accepted that neutral densities in the thermosphere have a significant dependence on the solar soft X‐ray fluxes, until recently the only coincident measurements available for an extended time period were from the AE‐E satellite in the late 1970's. However, the Student Nitric Oxide Explorer (SNOE) satellite began measuring the solar soft X‐ray flux (full disk) in March of 1998. Photometers on SNOE measured the solar flux in broad bands from 2 to 20 nm, rather than having high spectral resolution like the AE‐E measurements. The SNOE measurements are coincident with high precision satellite orbit measurements, from which total neutral densities near 350 km can be derived, for the GeoForschungsZentrum (GFZ) satellite. The GFZ data ended on 1 June, 1999. A quantitative assessment of the relationship between densities and broad band measurements of solar soft X‐rays, such as those from SNOE, is needed to determine the usefulness of broad band solar measurements for space weather applications. We have conducted such an assessment for geomagnetically undisturbed times and find correlations of ∼0.74 between the daily variations in total neutral density and the soft X‐rays measured by SNOE. The correlation seen between F10.7 and the neutral densities is significantly lower, ∼0.60. These results indicate that broadband solar soft X‐ray measurements could significantly improve the specification and prediction of neutral densities in the Earth's space environment.
Geometry of an interplanetary CME on October 29, 2003 deduced from cosmic rays
Authors: Kuwabara T. , Munakata K. , Yasue S. , Kato C. , Akahane S. , Koyama M. , Bieber J. W. , Evenson P. , Pyle R. , Fujii Z. , Tokumaru M. , Kojima M. , Marubashi K. , Duldig M. L. , Humble J. E. , Silva M. R. , Trivedi N. B. , Gonzalez W. D. , Schuch N. J.
Published: October 2004

A coronal mass ejection (CME) associated with an X17 solar flare reached Earth on October 29, 2003, causing an ∼11% decrease in the intensity of high‐energy Galactic cosmic rays recorded by muon detectors. The CME also produced a strong enhancement of the cosmic ray directional anisotropy. Based upon a simple inclined cylinder model, we use the anisotropy data to derive for the first time the three‐dimensional geometry of the cosmic ray depleted region formed behind the shock in this event. We also compare the geometry derived from cosmic rays with that derived from in situ interplanetary magnetic field (IMF) observations using a Magnetic Flux Rope model.
Bias reduction in short records of satellite soil moisture
Authors: Reichle R. H. , Koster R. D.
Published: October 2004

Although surface soil moisture data from different sources (satellite retrievals, ground measurements, and land model integrations of observed meteorological forcing data) have been shown to contain consistent and useful information in their seasonal cycle and anomaly signals, they typically exhibit very different mean values and variability. These biases pose a severe obstacle to exploiting the useful information contained in satellite retrievals through data assimilation. A simple method of bias removal is to match the cumulative distribution functions (cdf) of the satellite and model data. However, accurate cdf estimation typically requires a long record of satellite data. We demonstrate here that by using spatial sampling with a 2 degree moving window we can obtain local statistics based on a one‐year satellite record that are a good approximation to those that would be derived from a much longer time series. This result should increase the usefulness of relatively short satellite data records.
Coseismic and postseismic velocity changes measured by repeating earthquakes
Authors: Schaff David P. , Beroza Gregory C.
Published: October 2004

Repeating earthquakes that rupture approximately the same fault patch and have nearly identical waveforms are a useful tool for measuring temporal changes in wave propagation in the Earth's crust. Since source and path effects are common to all earthquakes in a repeating earthquake sequence (multiplet), differences in their waveforms can be attributed to changes in the characteristics of the medium. We have identified over 20 multiplets containing between 5 and 40 repeating events in the aftershock zones of the 1989 Loma Prieta and 1984 Morgan Hill, California, earthquakes. Postmain shock events reveal delays of phases in the early S wave coda of as much as 0.2 s relative to premain shock events. The delay amounts to a path‐averaged coseismic velocity decrease of about 1.5% for P waves and 3.5% for S waves. Since most of the multiplets are aftershocks and follow Omori's law, we have excellent temporal sampling in the immediate postmain shock period. We find that the amplitude of the velocity decrease decays logarithmically in time following the main shock. In some cases it returns to the premain shock values, while in others it does not. Similar results are obtained for the Morgan Hill main shock. Because the fractional change in S wave velocity is greater than the fractional change in P wave velocity, it suggests that the opening or connection of fluid‐filled fractures is the underlying cause. The magnitude of the velocity change implies that low effective pressures are present in the source region of the velocity change. Our results suggest that the changes are predominantly near the stations and shallow, but we cannot exclude the possibility that changes occur at greater depth as well. If the variations are shallow, we may be detecting the lingering effects of nonlinearity during main shock strong ground motion. If the variations are deep, it suggests that pore pressures at seismogenic depths are high, which would likely play a key role in the earthquake process.
Estimating atmospheric CO2 from advanced infrared satellite radiances within an operational 4D‐Var data assimilation system: Methodology and first results
Authors: Engelen Richard J. , Andersson Erik , Chevallier Frédéric , Hollingsworth Anthony , Matricardi Marco , McNally Anthony P. , Thépaut Jean‐Noël , Watts Philip D.
Published: October 2004

Atmospheric CO2 concentrations have been obtained from the Atmospheric Infrared Sounder (AIRS) radiance data within the European Centre for Medium‐Range Weather Forecasts data assimilation system. A subset of channels from the AIRS instrument on board the NASA Aqua platform has been assimilated providing estimates of tropospheric and stratospheric column‐average CO2 mixing ratios. Although global estimates are obtained, the information content of the tropospheric estimates at middle and high latitudes is limited, and results are therefore only presented for the tropical region. First results for February and August 2003 show considerable geographical variability compared to the background with values ranging between 371 and 380 ppmv. These CO2 values are representative for a layer between the tropopause and about 600 hPa. The monthly mean random error is about 1%. Careful error analysis has been carried out to minimize any systematic errors. This study has demonstrated the feasibility of global CO2 estimation using AIRS data in a numerical weather prediction data assimilation system. In the future the system will be improved to treat CO2 as a full three‐dimensional atmospheric variable, including transport.
A major regional air pollution event in the northeastern United States caused by extensive forest fires in Quebec, Canada
Authors: DeBell Linsey J. , Talbot Robert W. , Dibb Jack E. , Munger J. William , Fischer Emily V. , Frolking Steve E.
Published: October 2004

During early July 2002, wildfires burned ∼1 × 106 ha of forest in Quebec, Canada. The resultant smoke plume was seen in satellite images blanketing the U.S. east coast. Concurrently, extremely high CO mixing ratios were observed at the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) network sites in New Hampshire and at the Harvard Forest Environmental Measurement Site (HFEMS) in Massachusetts. The CO enhancements were on the order of 525–1025 ppbv above low mixing ratio conditions on surrounding days. A biomass burning source for the event was confirmed by concomitant enhancements in aerosol K+, NH4+, NO3−, and C2O42− mixing ratios at the AIRMAP sites. Additional data for aerosol K, organic carbon, and elemental carbon from the Interagency Monitoring of Protected Visual Environments network and CO data from Environmental Protection Agency sites indicated that the smoke plume impacted much of the U.S. east coast, from Maine to Virginia. CO mixing ratios and K concentrations at stations with 10‐year or longer records suggested that this was the largest biomass burning plume to impact the U.S. east coast in over a decade. Furthermore, CO mixing ratios and aerosol particles with diameters <2.5 μm (PM2.5) mass and scattering coefficients from the AIRMAP network and HFEMS indicated that this event was comparable to the large anthropogenic combustion and haze events which intermittently impact rural New England. The degree of enhancement of O3, NOy, NO3−, NH4+, and SO42− in the biomass plume showed significant variation with elevation and latitude that is attributed to variations in transport and surface depositional processes.
Latitude‐dependent nature and physical characteristics of transverse aeolian ridges on Mars
Authors: Wilson Sharon A. , Zimbelman James R.
Published: October 2004

Narrow‐angle images from the Mars Orbiter Camera (MOC) have revealed the common occurrence of small‐scale (<100 m wavelength) bright transverse aeolian ridges (TARs) on the surface of Mars. MOC images were used to assess the broad distribution of TARs from 90°N to 90°S between 180°E and ∼240°E to investigate their relationship to latitude, elevation, thermal inertia, geologic units, local slopes, and surface roughness. Out of 5112 examined images from the primary mission, 520 (10%) contain evidence of TARs, 92% of the images with TARs are located between ±50° latitude, and very few occur in the middle to upper latitudes or polar regions of either hemisphere. TARs are observed at elevations from −5 km to 3 km, with the highest frequency (26%) between −1 and 0 km. There is no systematic relationship between the distribution of TARs and global thermal inertia measurements. Most TARs occur in geologic units associated with the Channel System Materials (39%) and the Olympus Mons Aureole (33%). At a length scale of 1.85 km/pixel, the average local slopes for images with and without TARs are 1.92° and 1.36°, respectively. Of the parameters investigated, the latitudinal trend of TARs in both hemispheres appears to be predominantly related to surface roughness, with a positive linear correlation between the surface roughness of geologic units and frequency of TARs (R2 = 0.87). Factors affecting the semiglobal distribution of TARs are likely related to the climate and wind regimes in which they formed but do not provide definitive evidence for either saltation or reptation formation mechanisms.
Multi‐tasking by the p75 neurotrophin receptor: sortilin things out?
Authors: Bronfman Francisca C , Fainzilber Mike
Published: October 2004

Signalling by the p75 neurotrophin receptor has been implicated in diverse neuronal responses, including increased differentiation or survival, inhibition of regeneration, and initiation of apoptotic cell death. These numerous roles are matched by, but are not yet correlated with, a multiplicity of extracellular ligands and intracellular interactors. Membrane proteins such as sortilin, a member of the Vps10p family of sorting receptors, and the glycosylphosphatidylinositol‐linked Nogo receptor (NgR) and the associated adaptor lingo 1 have recently been added to the list of p75‐interacting modulators. Other studies have described intramembranal cleavage of p75 and the potential nuclear targeting of cleavage fragments or of the complete receptor after it has been internalized into a putative signalling endosome. These findings suggest that some of the diversity in p75 activities might be due to differential subcellular localization and transport of p75 receptor complexes. We therefore argue that cell‐biology‐driven approaches are now required to make sense of p75 signalling.
Duchenne muscular dystrophy and dystrophin: pathogenesis and opportunities for treatment
Authors: Nowak Kristen J , Davies Kay E
Published: October 2004

Duchenne muscular dystrophy (DMD) is caused by mutations in the gene that encodes the 427‐kDa cytoskeletal protein dystrophin. Increased knowledge of the function of dystrophin and its role in muscle has led to a greater understanding of the pathogenesis of DMD. This, together with advances in the genetic toolkit of the molecular biologist, are leading to many different approaches to treatment. Gene therapy can be achieved using plasmids or viruses, mutations can be corrected using chimaeraplasts and short DNA fragments, exon skipping of mutations can be induced using oligonucleotides and readthrough of nonsense mutations can be achieved using aminoglycoside antibiotics. Blocking the proteasome degradation pathway can stabilize any truncated dystrophin protein, and upregulation of other proteins can also prevent the dystrophic process. Muscle can be repopulated with myoblasts or stem cells. All, or a combination, of these approaches hold great promise for the treatment of this devastating disease.
Motional narrowing of the rotational spectrum of trifluoropropyne at 6550 cm−1 by intramolecular vibrational energy redistribution
Authors: Douglass Kevin O. , Dian Brian C. , Brown Gordon G. , Johns James E. , Nair Pradeep M. , Pate Brooks H.
Published: October 2004

We present the basic principles of dynamic rotational spectroscopy for the highly vibrationally excited symmetric top molecule trifluoropropyne (TFP,CF3CCH). Single molecular eigenstate rotational spectra of TFP were recorded in the region of the first overtone of the ν1 acetylenic stretching mode at 6550 cm−1 by infrared-pulsed microwave–Fourier transform microwave triple resonance spectroscopy. The average rotational constant (B) of the highly vibrationally mixed quantum states at 6550 cm−1 is 2909.33 MHz, a value that is 40 MHz larger than the rotational constant expected for the unperturbed C-H stretch overtone (2869.39 MHz). The average rotational constant and rotational line shape of the molecular eigenstate rotational spectra are compared to the distribution of rotational constants expected for the ensemble of normal-mode vibrational states at 6550 cm−1 that can interact by intramolecular vibrational energy redistribution (IVR). The normal-mode population distribution at 6550 cm−1 can be described using a Boltzmann distribution with a microcanonical temperature of 1200 K. At this energy the rotational constant distribution in the normal-mode basis set is peaked at about 2910 MHz with a width of about 230 MHz. The distribution is slightly asymmetric with a tail to the high end. The experimentally measured dynamic rotational spectra are centered at the normal-mode distribution peak; however, the spectral width is significantly narrower (40 MHz) than normal-mode ensemble width (230 MHz). This reduction of the width, along with the Lorentzian shape of the eigenstate rotational spectra when compared to the Gaussian shape of the calculated ensemble distribution, illustrates the narrowing of the spectrum due to IVR exchange. The IVR exchange rate was determined to be 120 ps, about ten times faster than the rate at which energy is redistributed from the v=2 level of the acetylenic stretch.
Application of the focusing x-ray spectrograph with crossed dispersion to investigations of X pinch plasmas
Authors: Pikuz S. A. , Song B. M. , Shelkovenko T. A. , Chandler K. M. , Mitchell M. D. , Hammer D. A.
Published: October 2004

A new focusing spectrograph configuration with crossed dispersion (FSCD) has been developed for use in X pinch experiments. This device solves the problem in a crystal spectrograph of the overlapping of reflected radiation in many orders. The x-ray radiation from a small source is dispersed by a transmission grating before it reaches the Bragg reflector (mica crystal). A large aperture (10 mm×10 mm), 0.5 μm period gold transmission grating was made on a 0.5 μm thick Si3N4 substrate and combined with spherically bent mica crystals with radii of curvature of 100 mm or 186 mm. Results of FSCD application to plasma experiments with X pinch x-ray sources is presented.
The Astro-E2 X-ray spectrometer/EBIT microcalorimeter x-ray spectrometer
Authors: Porter Frederick Scott , Brown Greg V. , Boyce Kevin R. , Kelley Richard L. , Kilbourne Caroline A. , Beiersdorfer Peter , Chen Hui , Terracol Stephane , Kahn Steven M. , Szymkowiak Andrew E.
Published: October 2004

The x-ray spectrometer (XRS) instrument is a revolutionary nondispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare XRS microcalorimeter spectrometer at the EBIT-I and SuperEBIT facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolving power. The XRS microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high energy resolution by operating at 0.06   K and by carefully engineering the heat capacity and thermal conductance. The XRS/EBIT instrument has 32 pixels in a square geometry and achieves an energy resolution of 6 eV at 6 keV, with a bandpass from 0.1 to 12 keV (or more at higher operating temperature). The instrument allows detailed studies of the x-ray line emission of laboratory plasmas. The XRS/EBIT also provides an extensive calibration “library” for the Astro-E2 observatory.
Reactivity of C10H7+ and C10D7+ with H2 and D2
Authors: Ascenzi D. , Bassi D. , Franceschi P. , Hadjar O. , Tosi P. , Di Stefano M. , Rosi M. , Sgamellotti A.
Published: October 2004

We have investigated, both theoretically and experimentally, the reactions of naphthylium C10H7+ and d-naphthylium C10D7+ ions with H2 and D2. Cross sections as functions of the collision energy have been measured for a variety of reaction channels. Theoretical calculations have been carried out at the density functional theory level which utilizes the hybrid functional B3LYP and the split-valence 6-31G* basis set. The key features of the potential energy surfaces and the relevant thermochemical parameters have been calculated and they provide insights on the reaction mechanisms. The bimolecular reactivity of C10H7+ with H2 is dominated by the production of naphthalene cation C10H8+. The reaction is not a direct atom-abstraction process, but instead it proceeds via the formation of a stable intermediate complex C10H9+ of σ type geometry, with a significant mobility of hydrogen along the ring. This mobility allows the scrambling of the hydrogen atoms and causes the successive statistical fragmentation of the complex into a variety of product channels. Elimination of one H(D) atom appears to be favored over elimination of one H2 or HD molecule. Alternatively, the intermediate complex can be stabilized either by collision with a third body or by emission of a photon.
Improvement of the Te profile on Joint European Torus measured by electron cyclotron emission
Authors: Blanchard Patrick , Luna Elena de la , Gowers Chris ,   JET-EFDA contributors
Published: October 2004

On the Joint European Torus (JET), a key source of calibrated electron temperature Te profiles is from the measurements of the full electron cyclotron emission (ECE) spectrum made by a Fourier transform spectrometer (FTS). It is absolutely calibrated by using a calibration source inside the vacuum vessel. High spatial and temporal resolution ECE Te profiles are obtained using a 96-channel heterodyne instrument which is cross-calibrated on each JET pulse against the data from the FTS system. Residual systematic frequency dependent errors at the 5%–10% level can then be evaluated and corrected for, using specific discharges in which the toroidal field is varied while keeping the shape of the Te profile constant. This improvement in the calibration method has been systematically applied at JET for the first time improving both the smoothness and the symmetry of the Te profiles. The consequences of this improvement are discussed. In addition, it is shown that no deviation occurs in the FTS calibration for more than eight years, which is relevant for the International Thermonuclear Experimental Reactor.
Orbital alignment in N2O photodissociation. I. Determination of all even rank anisotropy parameters
Authors: Smolin Andrey G. , Vasyutinskii Oleg S. , Wouters Eloy R. , Suits Arthur G.
Published: October 2004

We present a general method for determination of the photofragment K=4 state multipoles in an ion imaging experiment. These multipoles are important for determining the full density matrix for any photofragment with ja⩾2. They are expressed in terms of laboratory frame anisotropy parameters that have distinct physical origins and possess characteristic angular distributions. The explicit expression for the (2+1) resonant multiphoton ionization absorption signal for the case of arbitrarily polarized probe light is derived and a procedure for isolation of the rank-4 state multipoles from all others is shown. This treatment is applied to the case of O(1D) produced in the 193 nm photodissociation of N2O. The results show nonzero values for all K=4 anisotropy parameters, indicating the complexity of the photodissociation dynamics in this system.
Ultrashort-pulse reflectometer on LHD
Authors: Kogi Yuichiro , Uchida Kazuyuki , Mase Atsushi , Bruskin Leonid , Ignatenko Maxim , Tokuzawa Tokihiko , Nagayama Yoshio , Kawahata Kazuo
Published: October 2004

We have applied an ultrashort-pulse reflectometer to large helical device plasmas for density profile measurement. The frequency range of the impulse is up-converted into the R band, which corresponds to the cutoff frequency of edge plasma region in the ordinary mode. The reflected wave from plasma is received and directly recorded by a sampling scope. This system can be controlled and monitored from remote site (Kyushu University) by using ultrawideband science information network (super-SINET) that ideal bandwidth reaches up to 1 Gbps. As a result of the measurement, we have confirmed reflection wave from the plasma when the plasma density reaches steady state during the measurement.
Upgrade to the control system of the reflectometry diagnostic of ASDEX upgrade
Authors: Graça S. , Santos J. , Manso M. E. ,   CFN Reflectometry Team
Published: October 2004

The broadband frequency modulation-continuous wave microwave/millimeter wave reflectometer of ASDEX upgrade tokamak (Institut für Plasma Physik (IPP), Garching, Germany) developed by Centro de Fusão Nuclear (Lisboa, Portugal) with the collaboration of IPP, is a complex system with 13 channels (O and X modes) and two types of operation modes (swept and fixed frequency). The control system that ensures remote operation of the diagnostic incorporates VME and CAMAC bus based acquisition/timing systems. Microprocessor input/output boards are used to control and monitor the microwave circuitry and associated electronic devices. The implementation of the control system is based on an object-oriented client/server model: a centralized server manages the hardware and receives input from remote clients. Communication is handled through transmission control protocol/internet protocol sockets. Here we describe recent upgrades of the control system aiming to: (i) accommodate new channels; (ii) adapt to the heterogeneity of computing platforms and operating systems; and (iii) overcome remote access restrictions. Platform and operating system independence was achieved by redesigning the graphical user interface in JAVA. As secure shell is the standard remote access protocol adopted in major fusion laboratories, secure shell tunneling was implemented to allow remote operation of the diagnostic through the existing firewalls.
Parallel, linear-scaling building-block and embedding method based on localized orbitals and orbital-specific basis sets
Authors: Seijo Luis , Barandiarán Zoila
Published: October 2004

We present a linear scaling method for the energy minimization step of semiempirical and first-principles Hartree–Fock and Kohn–Sham calculations. It is based on the self-consistent calculation of the optimum localized orbitals of any localization method of choice and on the use of orbital-specific basis sets. The full set of localized orbitals of a large molecule is seen as an orbital mosaic where each tessera is made of only a few of them. The orbital tesserae are computed out of a set of embedded cluster pseudoeigenvalue coupled equations which are solved in a building-block self-consistent fashion. In each iteration, the embedded cluster equations are solved independently of each other and, as a result, the method is parallel at a high level of the calculation. In addition to full system calculations, the method enables to perform simpler, much less demanding embedded cluster calculations, where only a fraction of the localized molecular orbitals are variational while the rest is frozen, taking advantage of the transferability of the localized orbitals of a given localization method between similar molecules. Monitoring single point energy calculations of large poly(ethylene oxide) molecules and three dimensional carbon monoxide clusters using an extended Hückel Hamiltonian are presented.
Multipoint Thomson scattering diagnostic for the ETE tokamak
Authors: Berni L. A. , Alonso M. P. , Oliveira R. M.
Published: October 2004

To measure the electron temperature and plasma density profiles on the Experimento Tokamak Esférico tokamak a multiplexed Thomson scattering diagnostic was implemented. The diagnostic is based on a 10 J ruby laser and a single five spectral channel filter polychromator. A collection lens with f/6.3 relay the scattered light from 23 spatial points to optical fibers. The fibers have a monotonous increasing length and are inserted into the polychromator. Between the collection lens and each fiber optic we have a microlens to match the numerical aperture and to enlarge the plasma observation volume. This work describes the project, the simulations, and the preliminary results obtained with the first four optical fibers.
Study of the stabilization energies of halide-water clusters: An application of first-principles interaction potentials based on a polarizable and flexible model
Authors: Ayala Regla , Martı́nez José M. , Pappalardo Rafael R. , Sánchez Marcos Enrique
Published: October 2004

The aim of this work is to compute the stabilization energy Estab(n) of [X(H2O)n]− (X≡F, Br, and I for n=1–60) clusters from Monte Carlo simulations using first-principles ab initio potentials. Stabilization energy of [X(H2O)n]− clusters is defined as the difference between the vertical photodeachment energy of the cluster and the electron affinity of the isolated halide. On one hand, a study about the relation between cluster structure and the Estab(n) value, as well as the dependence of the latter with temperature is performed, on the other hand, a test on the reliability of our recently developed first-principles halide ion-water interaction potentials is carried out. Two different approximations were applied: (1) the Koopmans’ theorem and (2) calculation of the difference between the interaction energy of [X(H2O)n]− and [X(H2O)n] clusters using the same ab initio interaction potentials. The developed methodology allows for using the same interaction potentials in the case of the ionic and neutral clusters with the proviso that the charge of the halide anion was switched off in the latter. That is, no specific parametrization of the interaction potentials to fit the magnitude under study was done. The good agreement between our predicted Estab(n) and experimental data allows us to validate the first-principles interaction potentials developed elsewhere and used in this study, and supports the fact that this magnitude is mainly determined by electrostatic factors, which can be described by our interaction potentials. No relation between the value of Estab(n) and the structure of clusters has been found. The diversity of Estab(n) values found for different clusters with similar interaction energy indicates the need for statistical information to properly estimate the stabilization energy of the halide anions. The effect of temperature in the prediction of the Estab(n) is not significant as long as it was high enough to avoid cluster trapping into local equilibrium configurations which guarantees an appropriate sampling of the configurational space. Parallel tempering method was applied in particular cases to guarantee satisfactory sampling of clusters at low temperature.
Evaluation of tapered slot antennas for use in multichannel reflectometers
Authors: Hattori K. , Tsugueda H. , Takabatake O. , Tobari H. , Ando A. , Inutake M.
Published: October 2004

We have evaluated a Fermi antenna newly designed in X band for use in a multichannel reflectometer. The Fermi antenna is a tapered slot antenna provided with both a Fermi–Dirac-function-type tapered slot structure and a corrugated structure along the antenna edge in order to improve radiation patterns of the linearly tapered slot antenna. We attained a 3 dB beam width of 32° in the E plane and 37° in the H plane at 12 GHz. By optimizing the stripline dimensions according to an equivalent circuit model, a bandwidth of 8–18 GHz with a voltage standing-wave ratio less than 2 is obtained. In the mockup experiments using a rotating metal cylinder, the experimental results are in good agreement with the predicted ones.
Ion species mix measurements in DIII-D and International Thermonuclear Experimental Reactor using ion–ion hybrid layer reflectometry
Authors: Heidbrink W. W. , Watson G. W. , Burrell K. H.
Published: October 2004

A superheterodyne reflectometer can provide a direct and inexpensive measurement of the concentrations of ion species with different charge to mass ratios. The ion–ion hybrid cutoff frequency is uniquely determined by the cyclotron frequencies and concentrations of the different species. The phase of a ∼20 MHz wave that travels from a launching antenna on the low-field side of a tokamak, reflects off the cutoff layer, then travels to a receiving antenna provides a direct measure of the species mix. Hydrogen concentrations between 3% and 67% are measured in DIII-D using this technique. In theory, the technique can measure the spatial profile of the tritium concentration in the International Thermonuclear Experimental Reactor. Possible practical difficulties include attenuation of the wave in the evanescent layer near the antenna.
Frequency hopping millimeter wave reflectometer
Authors: Cupido L. , Sánchez J. , Estrada T.
Published: October 2004

Reflectometry techniques are employed to study density fluctuations in fusion plasmas either using one channel or two channels with slightly different frequencies, to probe simultaneously closely spaced plasma layers (for radial correlation studies). The present article describes a novel system with increasing measuring capability utilizing only one single frequency that can be hopped during the discharge. This broadband fast hopping mm-wave reflectometer (BFHR) has been developed for both ASDEX upgrade (Max Plank Institute-Garching-Germany) and TJ-II stellarator (CIEMAT-Spain). The BFHR incorporates frequency synthesizers at microwave frequencies multiplied into the millimeter-wave range and uses heterodyne detection for sensitive phase and amplitude measurements.
High-resolution dual-polarization frequency modulated reflectometer density profile measurements on DIII-D
Authors: Wang G. , Doyle E. J. , Peebles W. A. , Zeng L. , Rhodes T. L. , Kubota S. , Nguyen X. , Crocker N. A.
Published: October 2004

A novel dual-polarization technique has been applied to the frequency-modulated electron density profile reflectometer on DIII-D. In this application, both O- and X-mode waves are simultaneously launched from a common high-performance solid-state source, and simultaneous measurements of both O- and X-mode reflections from corresponding cutoffs serve to expand the density coverage. The system consists of both Q-band (33–50 GHz) and V-band (50–72 GHz) subsystems, their combination covers a density range from 0 to 6.4×1019 m−3, with a time resolution of ⩾10 μs and spatial resolution of ⩾4 mm. The dual-polarization technique was implemented successfully in the Q-band subsystem during 2003 and detailed information for H-mode pedestal physics studies was provided. It has also recently been applied to the V-band subsystem, and extended contributions to H-mode pedestal physics and particle transport studies are expected during the 2004 DIII-D campaign.
Omega Dante soft x-ray power diagnostic component calibration at the National Synchrotron Light Source
Authors: Campbell K. M. , Weber F. A. , Dewald E. L. , Glenzer S. H. , Landen O. L. , Turner R. E. , Waide P. A.
Published: October 2004

The Dante soft x-ray spectrometer, installed on the Omega laser facility at the Laboratory for Laser Energetics, University of Rochester, is a 12-channel filter-edge defined soft x-ray power diagnostic. It is used to measure the spectrally resolved, absolute flux from direct drive, indirect drive (hohlraums) and other plasma sources. Dante component calibration efforts using two beam lines, U3C (50 eV–1 keV) and X8A (1–6 keV) at the National Synchrotron Light Source have been implemented to improve the accuracy of these measurements. We have calibrated metallic vacuum x-ray diodes, mirrors and filters.
Ultrashort-pulse reflectometer performance on Sustained Spheromak Physics Experiment
Authors: Domier C. W. , Luhmann N. C. , Roh Y. , McLean H. S. , Hooper E. B. , Hill D. N.
Published: October 2004

Time-resolved density profiles on the Sustained Spheromak Physics Experiment device are now generated automatically from data collected by an ultrashort-pulse reflectometry (USPR) diagnostic comprised of 24 frequency channels spanning 34–75 GHz. Upgrades in USPR timing electronics and reconstruction software, coupled with new low noise amplifiers and reduced bandwidth filters, have significantly decreased amplitude and timing jitter enabling simultaneous density profile and multilayer density fluctuation operation. Hardware and software components of the upgraded USPR system are described, and sample profile and fluctuation data are presented. A new system layout is proposed to increase the USPR dynamic range by 8–10 dB.
Design study for International Thermonuclear Experimental Reactor high resolution x-ray spectroscopy array
Authors: Barnsley R. , O’Mullane M. , Ingesson L. C. , Malaquias A.
Published: October 2004

The impurity line and continuum emission for International Thermonuclear Experimental Reactor (ITER) reference H-mode and Internal Transport Barrier (ITB) plasmas were modeled using the SANCO impurity transport code. Using the instrument sensitivity for a spatially resolving crystal spectrometer array with doubly-curved crystals and two-dimensional detectors, signals, and signal-to-noise ratios were calculated for impurities including argon, iron, and krypton. These were shown to have lines suitable for the measurement of the ion temperature (0.5–30 keV) and the rotation over almost the entire plasma minor radius. The main contribution to the signal-to-noise is the plasma continuum radiation on which the lines are superimposed. The tolerable impurity concentration is limited by the incremental radiated power ΔPrad, there being a broad operating range between about 100 kW and 10 MW. The spectrometer array has now been integrated into the ITER design. A quasitomographic technique to reconstruct the Ti and rotation profiles, is reported by Ingesson et al. [C. Ingesson, these proceedings].