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  • 1
    Electronic Resource
    Electronic Resource
    Ions in holes: An experimental study of ion distributions inside surface features on radio-frequency-biased wafers in plasma etching discharges (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 92 (2002), S. 716-723 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present an experimental study of ion fluxes, energy distributions, and angular distributions inside surface features on radio frequency-biased wafers in high-density, inductively driven discharges in argon. Specifically, we present data on ion distributions at the bottom of 100-μm-square, 400-μm-deep "holes" in the wafer. Transmission of ions to the bottom of the holes increases with increasing ion energy and decreases as the sheath size becomes comparable to the hole size. Ion energy distributions at the bottom of the holes are narrower than distributions on the flat wafer surface. The flux of ions remains normal to the wafer surface over most of the hole area but the flux of ions within 6 μm of the wall is angled towards the wall. The observed trends are consistent with effects expected due to bowing of the plasma sheath around the surface features on the wafer. Scattering of ions off sidewalls contributes at most, only a small part of the ion flux reaching the bottom of the hole. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1486054
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  • 2
    Electronic Resource
    Electronic Resource
    The Predictability of Large Earthquakes: Evidence from an Analogue Model of Earthquake Rupture (1998)
    Springer
    Pure and applied geophysics 152 (1998), S. 23-35 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Analogue model, large earthquakes, recurrence behaviour, lognormal distribution.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —The recurrence behaviour of large earthquakes, in several tectonic settings, has been explained by simple models of stress accumulation and release which assume that the fault stress state is solely a function of the far-field tectonic strain rate. However, the limited dataset of large event recurrence intervals has been a major obstacle to the verification of these and other models. We present the results from a simple analogue model of earthquake rupture and stick-slip which displays power-law frequency-size statistics and involves many cycles of large events. We show that, despite the macroscopic homogeneity of the model, large events do not conform to simple deterministic time- or slip-predictable patterns. However, when the recurrence intervals for large events are divided by the median recurrence interval, the normalized data are composed of two distinct lognormally distributed populations. One population is characterized by events which are strongly clustered in time with relatively short recurrence intervals and low moment release, the other by events which are weakly clustered in time with median-sized recurrence intervals. It is suggested that the long-term recurrence behaviour of large earthquakes, whilst being non-deterministic, may be modelled by a well-defined statistical distribution of recurrence intervals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050139
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  • 3
    Electronic Resource
    Electronic Resource
    New Non-cytotoxic Approaches to Ovarian Cancer (1999)
    Springer
    Annals of oncology 10 (1999), S. 65-68 
    Details
    ISSN: 1569-8041
    Keywords: drug resistance ; genetic therapy ; immunotherapy ; metalloproteinase inhibitors ; radioconjugates ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two recent examples of conventional cytotoxic drugs, taxoids and topo I inhibitors, are set to make a real impact in the treatment of ovarian cancer. However, further progress may depend on novel approaches, focusing on other targets. This review will concentrate on those approaches which have already led to the initiation of clinical trials: agents designed to circumvent cellular drug resistance, signal transduction inhibitors, new hormonal agents, matrix metalloproteinase inhibitors, immunotherapy, immunotoxins and radioconjugates, and intraperitoneal genetic therapy, including the use of replicating viruses. In some cases, early clinical data are encouraging, but ultimately combined treatment with conventional agents may make most impact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008315603401
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  • 4
    Electronic Resource
    Electronic Resource
    A stringent new limit on bursts from nearby galaxies (1995)
    Springer
    Astrophysics and space science 231 (1995), S. 453-456 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract If typical gamma-ray bursts [GRBs] have X-ray counterparts similar to those detected byGinga, then sensitive focusing X-ray telescopes will be able to detect GRBs three orders of magnitude fainter than the detection limit of the Burst and Transient Spectroscopy Experiment [BATSE]. If a substantial portion of the burst population detected byBATSE originates in a Galactic halo at distances greater than or equal to 150 kpc, existing X-ray telescopes will be able to detect GRBs in external galaxies out to a distance of at least 4.5 Mpc. As reported in Hamilton, Gotthelf and Helfand (1995) the Imaging Proportional counter [IPC] on board theEINSTEIN Observatory detected 42 transient events with pointlike spatial characteristics and timescales of less than 10 seconds. These events are distributed isotropically on the sky; in particular, they are not concentrated in the directions of nearby external galaxies. For halo models of theBATSE bursts with radii of 150 kpc or greater, we would expect to see several burst events in observations pointed towards nearby galaxies. We see none. We therefore conclude that if theGinga detections are representative of the population of GRBs sampled byBATSE, GRBs cannot originate in a Galactic halo population with limiting radii between 150 kpc and 400 kpc. Inasmuch as halos with limiting radii outside of this range have been excluded by theBATSE isotropy measurements, our result indicates that all halo models are excluded. This result is independent of whether the flashes we do detect have an astronomical origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00658669
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  • 5
    Electronic Resource
    Electronic Resource
    Basic Research: How Much do we Know, and What are we Likely to Learn About Ovarian Cancer in the Near Future? (1999)
    Springer
    Annals of oncology 10 (1999), S. 69-73 
    Details
    ISSN: 1569-8041
    Keywords: BRCA1 ; experimental mod ; ovarian tumours ; ROSE ; suppressor genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The scientific community, which studies ovarian cancer in the laboratory, is making progress in understanding many aspects of the disease. At present there is evidence that the cancer prone ovary has a preneoplastic phenotype. These genetic changes may constitute a surrogate intermediate end-point biomarker of cancer risk, which might be altered by preventive measures. Studies that aim at understanding the genetic basis of the disease are reviewed. Many of these studies use clinical ovarian cancer samples. To augment study of clinical specimens, an experimental system has been developed where malignancy is induced in the rat ovarian surface epithelium (ROSE). This system markedly facilitates examination of how genes fit into the ovarian cancer puzzle. The problem of drug resistance in ovarian cancer has received considerable attention. Although the functional changes responsible for resistance have been identified there has been little progress in identifying the actual g enes capable of conferring the substantial resistance seen in cell lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008367620240
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  • 6
    Electronic Resource
    Electronic Resource
    Advanced Epithelial Ovarian Cancer: 1998 Consensus Statements (1999)
    Springer
    Annals of oncology 10 (1999), S. 87-92 
    Details
    ISSN: 1569-8041
    Keywords: CA 125 ; consensus ; management ; ovarian cancer ; prognostic factors ; second-line treatment ; surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: During an international workshop held in September 1998, a group of specialists in the field of ovarian cancer reached consensus on a number of issues with implications for standard practice and for research of advanced epithelial ovarian cancer. Methods: Five groups of experts considered several issues which included: biologic factors, prognostic factors, surgery, initial chemotherapy, second-line treatment, the use of CA 125, investigational drugs, intra-peritoneal treatment and high-dose chemotherapy. The group attempted to arrive at answers to questions such as: Are there prognostic factors, which help to identify patients who will not do well with current therapy? What is the current best therapy for advanced ovarian carcinoma? What directions should research take in advanced ovarian cancer? These issues were discussed in a plenary meeting. Results: One of the major conclusions drawn by the consensus committee was that in previously untreated advanc ed ovarian cancer, cisplatin plus paclitaxel has been shown to be superior to previous standard therapy with cisplatin plus cyclophosphamide (level I evidence). However, for many patients, carboplatin plus paclitaxel is a reasonable alternative because of toxicity and convenience considerations. Most participants felt that the benefits in terms of toxicity for the paclitaxel-carboplatin are such that its widespread adoption at this stage is justified. Until mature survival data are available a minority of investigators would recommend continued use of cisplatin plus paclitaxel, specifically for those patients with advanced disease with the best prognostic characteristics. For future clinical research in this area, new end points for randomised clinical trials, together with a new Trials Network, are proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008323922057
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  • 7
    Electronic Resource
    Electronic Resource
    The Marshall Islands Radioassay Quality Assurance Program: An Overview (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 243 (2000), S. 415-422 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The Lawrence Livermore National Laboratory has developed an extensive quality assurance program to provide high quality data and assessments in support of the Marshall Islands Dose Assessment and Radioecology Program. Our quality assurance objectives begin with the premise of providing integrated and cost-effective program support (to meet wide-ranging programmatic needs, scientific peer review, and build public confidence) and continue through from design and implementation of large-scale field programs, sampling and sample preparation, radiometric and chemical analyses, documentation of quality assurance/quality control practices, exposure assessments, and dose/risk assessments until publication. The basic structure of our radioassay quality assurance/quality control program can be divided into four essential elements: (1) sample and data integrity control, (2) instrument validation and calibration, (3) method performance testing, validation, development and documentation, and (4) periodic peer review and on-site assessments. While our quality assurance objectives are tailored towards a single research program and the evaluation of major exposure pathways/critical radionuclides pertinent to the Marshall Islands, we have attempted to develop quality assurance practices that are consistent with proposed criteria designed for laboratory accreditation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016022029721
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  • 8
    Electronic Resource
    Electronic Resource
    The Effect of Carbonate Soil on Transport and Dose Estimates for Long-Lived Radionuclides at a U.S. Pacific Test Site (2000)
    Springer
    Journal of radioanalytical and nuclear chemistry 243 (2000), S. 459-465 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The United States conducted a series of nuclear tests from 1946 to 1958 at Bikini, a coral atoll, in the Marshall Islands (MI). The aquatic and terrestrial environments of the atoll are still contaminated with several long-lived radionuclides that were generated during testing. The four major radionuclides found in terrestrial plants and soils are cesium-137, strontium-90, plutonium-239+240 and americium-241. Cesium-137 in the coral soils is more available for uptake by plants than 137Cs associated with continental soils of North America or Europe. Soil-to-plant 137Cs median concentration ratios (CR) (kBq·kg-1 dry weight plant/kBq·kg-1 dry weight soil) for tropical fruits and vegetables range between 0.8 and 36, much larger than the range of 0.005 to 0.5 reported for vegetation in temperate zones. Conversely, 90Sr median CRs range from 0.006 to 1.0 at the atoll versus a range from 0.02 to 3.0 for continental silica-based soils. Thus, the relative uptake of 137Cs and 90Sr by plants in carbonate soils is reversed from that observed in silica-based soils. The CRs for 239+240Pu and 241Am are very similar to those observed in continental soils. Values range from 10-6 to 10-4 for both 239+240Pu and 241Am. No significant difference is observed between the two in coral soil. The uptake of 137Cs by plants is enhanced because of the absence of mineral binding sites and the low concentration of potassium in the coral soil. Cesium-137 is bound to the organic fraction of the soil, whereas 90Sr, 239+240Pu and 241Am are primarily bound to soil particles. Assessment of plant uptake for 137Cs and 90Sr into locally grown food crops was a major contributing factor in: (1) reliably predicting the radiological dose for returning residents and (2) developing a strategy to limit the availability and uptake of 137Cs into locally grown food crops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016090517426
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  • 9
    Electronic Resource
    Electronic Resource
    Characterisation of marine and lacustrine sediments in a drowned thermokarst embayment, Richards Island, Beaufort Sea, Canada (2000)
    Springer
    International journal of earth sciences 89 (2000), S. 503-521 
    Details
    ISSN: 1437-3262
    Keywords: Beaufort Sea Mackenzie Delta Thermokarst lake Embayment Arctic Cesium radiocarbon Geochemistry Permafrost Acoustic stratigraphy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract. A multidisciplinary study was made of lakes and lagoons in a thermokarst embayment on Richards Island, Canadian Beaufort Sea, in order to investigate the response of the Mackenzie Delta shoreline to changing hydrological influences. Seismo-acoustic profiles made from an amphibious vehicle, combined with sediment core data, show that the deepest lakes contain up to 10 m of transparent or stratified silty mud overlying the Kittigazuit sand basement. Palynological and microfossil data from 21 surface samples allow delineation of freshwater, saltmarsh, tidal flat and subtidal assemblages. These modern reference data allow distinction of freshwater and marine facies in the cores and subsequent interpretation of geochemical content (carbon, ammonia, sulphate). Radiocarbon dates and 137 Cs show that sedimentation rates have increased by an order of magnitude since drowning of the embayment during the past millennium, and that most of this sediment is from the Mackenzie River plume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310000126
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