Showing papers by "David W. Johnson published in 1999"

The DNA sequence of human chromosome 22

Abstract: Knowledge of the complete genomic DNA sequence of an organism allows a systematic approach to defining its genetic components. The genomic sequence provides access to the complete structures of all genes, including those without known function, their control elements, and, by inference, the proteins they encode, as well as all other biologically important sequences. Furthermore, the sequence is a rich and permanent source of information for the design of further biological studies of the organism and for the study of evolution through cross-species sequence comparison. The power of this approach has been amply demonstrated by the determination of the sequences of a number of microbial and model organisms. The next step is to obtain the complete sequence of the entire human genome. Here we report the sequence of the euchromatic part of human chromosome 22. The sequence obtained consists of 12 contiguous segments spanning 33.4 megabases, contains at least 545 genes and 134 pseudogenes, and provides the first view of the complex chromosomal landscapes that will be found in the rest of the genome.

Making cooperative learning work

Abstract: (1999). Making cooperative learning work. Theory Into Practice: Vol. 38, Building Community Through Cooperative Learning, pp. 67-73.

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana

Abstract: The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

Does competition enhance or inhibit motor performance: a meta-analysis.

Abstract: A meta-analysis was conducted on the relative impact of cooperative, competitive, and individualistic efforts on motor skills performance. Competition was divided into 3 groups: zero sum, appropriate, and unclear. The motor skills tasks were divided into means-interdependent and means-independent tasks. The dependent variables were achievement-performance, interpersonal attraction, social support, and self-esteem. A total of 64 studies met the criteria for inclusion. Effects sizes were computed, and confidence intervals were used to determine their significance. A fail-safe sample size was computed to determine how many additional studies were needed to change the significance of the results. Cooperation resulted in higher achievement for means-interdependent tasks in zero-sum competition, unclear competition, and individualistic efforts, and it promoted higher achievement for means-independent tasks for unclear competition and individualistic efforts. For all comparisons, cooperation resulted in greater interpersonal attraction, social support, and self-esteem.

The effectiveness of glucocorticoids in treating croup: meta-analysis.

Abstract: Objective: To determine the effectiveness of glucocorticoid treatment in children with croup. Design: Meta-analysis of randomised controlled trials that examine the effectiveness of glucocorticoid treatment in children with croup. Main outcome measures: Score on scale measuring severity of croup, use of cointerventions (adrenaline (epinephrine), antibiotics, or supplemental glucocorticoids), length of stay in accident and emergency or in hospital, and rate of hospitalisation. Results: Twenty four studies met the inclusion criteria. Glucocorticoid treatment was associated with an improvement in the croup severity score at 6 hours with an effect size of −1.0 (95% confidence interval −1.5 to −0.6) and at 12 hours −1.0 (−1.6 to −0.4); at 24 hours this improvement was no longer significant (−1.0, −2.0 to 0.1). There was a decrease in the number of adrenaline treatments needed in children treated with glucocorticoids: a decrease of 9% (95% confidence interval 2% to 16%) among those treated with budesonide and of 12% (4% to 20%) among those treated with dexamethasone. There was also a decrease in the length of time spent in accident and emergency (−11 hours, 95% confidence interval −18 to 4 hours), and for inpatients hospital stay was reduced by 16 hours (−31 to 1 hour). Publication bias seems to play a part in these results. Conclusions: Dexamethasone and budesonide are effective in relieving the symptoms of croup as early as 6 hours after treatment. Fewer cointerventions are used and the length of time spent in hospital is decreased in patients treated with glucocorticoids. Key messages Most trials evaluating the treatment of croup are of high methodological quality and hence have a low risk of bias Publication bias, however, seems to be a problem, making the results of this meta-analysis somewhat less certain Glucocorticoids seem to bring about clinical improvement in children with croup within 6 hours Nebulised budesonide or dexamethasone, given either orally or intramuscularly, is effective in treating croup The use of glucocorticoids is associated with a lower rate of use of cointerventions and shortens the time spent in hospital

3-O-desacyl monophosphoryl lipid A derivatives : Synthesis and immunostimulant activities

Abstract: The synthesis of a series of novel analogues of lipid A, the active principle of lipopolysaccharide, is reported. In these compounds, the 1-O-phosphono and (R)-3-hydroxytetradecanoyl moieties of native Salmonella minnesota R595 lipid A have been replaced with hydrogen and the length of the normal fatty acyl residues has been systematically varied. Normal fatty acid chain length in the 3-O-desacyl monophosphoryl lipid A (MLA) series is shown to be a critical determinant of iNOS gene expression in activated mouse macrophages and the induction of proinflammatory cytokines in human peripheral monocytes. Examination of pyrogenicity in rabbits and lethal toxicity in D-galactosamine-treated mice shows that toxic effects in the MLA series can be ameliorated by modifying fatty acid chain length. When used as an adjuvant for tetanus toxoid vaccines, certain MLA derivatives enhance the production of tetanus toxoid-specific antibodies in mice.

The effects of quantity and duration of simulated pollutant nitrogen deposition on root-surface phosphatase activities in calcareous and acid grasslands: a bioassay approach

Abstract: A field and laboratory based bioassay has been developed to investigate the effects of the quantity and duration of simulated pollutant nitrogen (N) deposition on root-surface phosphomonoesterase (PME) activities in calcareous and acid grasslands. Seedlings of Plantago lanceolata were transplanted to a calcareous grassland and Agrostis capillaris seedlings were grown in microcosms containing soil from an acid grassland that had received either 7 yr (long-term) N additions or 18 months (short-term) N and phosphorus (P) additions. The bioassay revealed that short-term N treatments had little effect on the enzyme activity, whereas long-term N additions significantly increased PME activity within 7 d of transplanting into the field plots. Root-surface PME activity of A. capillaris was significantly reduced in soil that received additions of P. In the plots receiving long-term additions of N, a strong relationship was observed between extractable soil ammonium and root-surface PME activity. Soil ammonium concentrations accounted for 67% of the variation in PME activity of P. lanceolata in the calcareous grassland, and 86% of the variation in PME activity of A. capillaris in the acid grassland. These results provide evidence that N deposition may have considerable effects on the demand and turnover of P in ecosystems that are approaching or have reached N saturation.

Cyclosporin exerts a direct fibrogenic effect on human tubulointerstitial cells: roles of insulin-like growth factor I, transforming growth factor beta1, and platelet-derived growth factor.

Abstract: To assess the direct fibrogenic effects of cyclosporin A (CyA) on the human tubulointerstitium, primary cultures of human renal proximal tubule cells (PTC) and renal cortical fibroblasts (CF) were incubated for 24 h with various concentrations of CyA. Cytotoxicity was confirmed in both cell populations by dose-dependent inhibition of thymidine incorporation, viability, and PTC apical sodium-hydrogen exchange activity (ethylisopropylamiloride-sensitive apical22Na+ uptake). Compared with controls, both 500 and 1000 ng/ml CyA significantly stimulated CF collagen synthesis (proline incorporation 4.6 ± 0.4, 6.5 ± 0.8, and 7.1 ± 1.0%, respectively; p < .05) and inhibited matrix metalloproteinase-2 (100%, 85.7 ± 10.0%, and 38.8 ± 9.2%) and matrix metalloproteinase-9 activity (100%, 110.6 ± 19.0%, and 49.9 ± 12.8%). CyA did not affect CF secretion of transforming growth factor β1, but markedly stimulated insulin-like growth factor-I (IGF-I) secretion and inhibited secretion of both IGF-I binding protein-(IGFBP)-3 and IGFBP-2. CyA-induced CF collagen synthesis was abrogated by 5 μg/ml anti-IGF-I receptor antibody, but not by 5 μg/ml murine nonimmune globulin. Increasing concentrations of CyA progressively augmented PTC secretion of the fibrogenic cytokines transforming growth factor-β1and platelet-derived growth factor. These results indicate that clinically relevant concentrations of CyA are directly toxic to PTC and CF, irrespective of hemodynamic effects, and promote interstitial fibrosis by inhibiting matrix degradation and stimulating cortical fibroblast collagen synthesis via induction of autocrine IGF-I action. The latter effect may be further accentuated by the ability of CyA to augment secretion of transforming growth factor β1 and platelet-derived growth factor by PTCs.

Assembly of a Novel Cartilage Matrix Protein Filamentous Network: Molecular Basis of Differential Requirement of von Willebrand Factor A Domains

Abstract: Cartilage matrix protein (CMP) is the prototype of the newly discovered matrilin family, all of which contain von Willebrand factor A domains. Although the function of matrilins remain unclear, we have shown that, in primary chondrocyte cultures, CMP (matrilin-1) forms a filamentous network, which is made up of two types of filaments, a collagen-dependent one and a collagen-independent one. In this study, we demonstrate that the collagen-independent CMP filaments are enriched in pericellular compartments, extending directly from chondrocyte membranes. Their morphology can be distinguished from that of collagen filaments by immunogold electron microscopy, and mimicked by that of self-assembled purified CMP. The assembly of CMP filaments can occur from transfection of a wild-type CMP transgene alone in skin fibroblasts, which do not produce endogenous CMP. Conversely, assembly of endogenous CMP filaments by chondrocytes can be inhibited specifically by dominant negative CMP transgenes. The two A domains within CMP serve essential but different functions during network formation. Deletion of the A2 domain converts the trimeric CMP into a mixture of monomers, dimers, and trimers, whereas deletion of the A1 domain does not affect the trimeric configuration. This suggests that the A2 domain modulates multimerization of CMP. Absence of either A domain from CMP abolishes its ability to form collagen-independent filaments. In particular, Asp22 in A1 and Asp255 in A2 are essential; double point mutation of these residues disrupts CMP network formation. These residues are part of the metal ion-dependent adhesion sites, thus a metal ion-dependent adhesion site-mediated adhesion mechanism may be applicable to matrilin assembly. Taken together, our data suggest that CMP is a bridging molecule that connects matrix components in cartilage to form an integrated matrix network.

Paclitaxel Steady-State Plasma Concentration as a Determinant of Disease Outcome and Toxicity in Lung Cancer Patients Treated with Paclitaxel and Cisplatin

Abstract: The principal purpose of this study was to evaluate relationships between paclitaxel plasma steady-state concentration ( C ss ) and both disease outcome and toxicity in patients with non-small cell lung cancer (NSCLC) treated with paclitaxel and cisplatin in an Eastern Cooperative Oncology Group (ECOG) Phase III study E5592. Chemotherapy-naive patients with stage IIIb and IV NSCLC were randomized to treatment with either 75 mg/m 2 cisplatin i.v. on day 1 and 100 mg/m 2 etopside i.v. on days 1–3 (EC arm) or 75 mg/m 2 cisplatin i.v. combined with either a low dose of paclitaxel (135 mg/m 2 , 24-h i.v. infusion; PC arm) or a higher dose of paclitaxel (250 mg/m 2 i.v., 24-h i.v. infusion) with granulocyte colony-stimulating factor (PCG arm). End-of-24-h-infusion paclitaxel concentrations, which have been demonstrated to be nearly equal to C ss s on this schedule, were obtained during the first and second courses in patients on the PC and PCG arms. Relationships between the average paclitaxel C ss ( C ss,avg ) and the best response to treatment, time to treatment failure (TTF), survival, and worst grade of leukopenia and neurotoxicity were evaluated by univariate analysis. A multivariate model was used to assess the influence of paclitaxel C ss in conjunction with other potentially relevant patient variables that may affect disease outcome, including the paclitaxel treatment arm, age, sex, performance status, weight loss during the previous 6 months, and disease stage. Paclitaxel C ss in both courses 1 and 2 were obtained in 71 patients treated with PC and 75 patients treated with PCG. Although C ss,avg s in patients treated with PC and PCG were significantly different (median, 0.32 versus 0.81 μmol/liter; P versus 26.7%; P = 0.3719). In addition, there were no differences between the PC and PCG arms in TTF (median, 5.1 versus 5.5 months, P = 0.6201) or survival (median, 11.6 versus 11.3 months, P = 0.7173). Combined analysis of paclitaxel concentrations from both treatment arms revealed no significant difference in paclitaxel C ss,avg between responders and nonresponders [median, 0.40 (range, 0.16–1.6) μmol/liter versus 0.55 (range, 0.11–3.6)], and C ss,avg s were similar in patients segregated according to whether they had a complete response, partial response, stable disease, or progressive disease as their best response to treatment ( P = 0.7612). In addition, the relationship between C ss,avg and TTF was weak ( r 2 = 0.00003, P = 0.94), as was the relationship between C ss,avg and survival ( P = 0.1267). With regard to the principal toxicities, neither the propensity to develop neuromuscular and neurosensory toxicity nor the worst grade of these adverse effects were related to C ss,avg ( P = 0.5000 and 0.2033, respectively); however, the relationship between C ss,avg and the worst grade of leukopenia experienced was marginally significant ( P = 0.0796). In a multivariate model, neither the combined effect of relevant demographic and stratification variables nor paclitaxel C ss,avg predicted for either response ( P = 0.1544) or TTF ( P = 0.2574), whereas the combined effect of all covariates predicted for survival ( P = 0.0249). With regard to individual covariates, a lower disease stage (stage IIIb) was the only significant positive determinant of response ( P = 0.0173), female sex was the only significant favorable predictor for TTF ( P = 0.0195), and a lower ECOG performance status (= 0) was the only significant positive determinant of survival ( P = 0.0121) in the multivariate model. In summary, paclitaxel C ss,avg was not a determinant of response, TTF, or survival in patients with advanced NSCLC treated with paclitaxel as a 24-h i.v. infusion combined with cisplatin. On the basis of both the clinical and pharmacodynamic results of E5592, there is no compelling reason to treat patients with advanced NSCLC with paclitaxel on a 24-h i.v. schedule at doses of >135 mg/m 2 in combination with cisplatin, although higher doses are associated with higher paclitaxel C ss s.

Dimethylaminoethyl esters for trace, rapid analysis of fatty acids by electrospray tandem mass spectrometry.

Abstract: The development of a new derivative, the dimethylaminoethyl ester, for the analysis of fatty acids by electrospray tandem mass spectrometry is described. Qualitative and quantitative analyses of long to very long chain fatty acids in plasma, blood, urine and wax were performed. Branched chain, unsaturated, dicarboxylic, hydroxy, amino and keto acids were studied. The quantitative analysis method using the new derivative is simple, rapid and precise with small sample size. It has good potential as a screening method for biologically important fatty acids. Copyright 1999 John Wiley & Sons, Ltd.

Inaccurate measurement of free carnitine by the electrospray tandem mass spectrometry screening method for blood spots.

Abstract: An increasing number of laboratories screen for inherited metabolic diseases by electrospray tandem mass spectrometric analysis of extracts of blood spots from newborns (Chace et al 1995 ; Rashed et al 1995). The dried methanol extract of the blood spot, to which deuterium-labelled internal standards have been added, is butylated and infused into an electrospray tandem mass spectrometer. The concentrations of carnitine, acylcarnitines and amino acids are measured and compared with a normal reference range, and abnormal values are Ñagged. The standard butylation procedure involves heating the dried extract in 60 kl of anhydrous nbutanolÈ3 mol/L HCl at 65¡C for 15 min. Milder conditions a†ord incomplete butylation and the problems of interfering peaks and reduced sensitivity. Experiments in our laboratory have shown that (butylated) acylcarnitines are also converted to (butylated) carnitine in n-butanolÈ3 mol/L HCl. In separate experiments acetyl-, decanoylor octadecanoylcarnitine hydrochlorides (0.5 mmol/L) and hydrochloride (2.5 mmol/L) in n-butanolÈ3 mol/L HCl were heated L-(2H3)carnitine at 65¡C for 2 h. Five timed aliquots were removed, evaporated in a stream of nitrogen and dissolved in acetonitrileÈwaterÈformic acid (50 : 50 : 0.25). They were infused into the Ionspray of a PE Sciex API365 tandem mass spectrometer. The ratios of protonated molecular ions for butylated acylcarnitine to butylated Lwere measured from precursor ions scans of product ion m/z 85 and (2H3)carnitine plotted on a log scale against time for each acylcarnitine. From the straight-line decay graphs the half-life of each acylcarnitine in the butylating reagent was determined as well as the percentage butanolysed in 15 min. Acetylcarnitine has a half-life of 31 min and 30% butanolyses in 15 min ; decanoylcarnitine has a half-life of 125 min and 8% butanolyses in 15 min ; and octadecanoylcarnitine has a half-life of 172 min and 6% butanolyses in 15 min. Several implications derive from these observations. Some of the carnitine measured in the blood spot analysis comes from the acylcarnitines (including the deuterated internal standards). Consider a sample with low free carnitine and high acetylcarnitine. Thirty per cent of the acetylcarnitine as well as smaller amounts of higher molecular mass acylcarnitines are converted to carnitine and the lowcarnitine sample could appear to be normal. Prolonging the butylation time will not only result in a grossly inaccurate carnitine determination but will also reduce the signal intensity of the acylcarnitine ions during mass spectral analysis. Overnight butylation (15 h) will hydrolyse 97% of the high molecular mass acylcarnitines, i.e.

Tokamak fusion test reactor poloidal rotation diagnostic (invited)

Abstract: A new spectroscopic diagnostic was developed to measure poloidal velocity profiles of Tokamak fusion test reactor (TFTR) plasmas. Carbon poloidal velocities were measured using the Doppler shift of the C VI 5291 A impurity line of both intrinsic emission and charge exchange emission from neutral beams. Poloidal velocities are typically small (vθ⩽104 m/s) requiring small wavelength shifts (Δλ⩽0.2 A) to be measured. However, the high central ion temperatures in TFTR required the use of a low dispersion spectrometer to view the entire linewidth (full width at half maximum ⩽25 A). A very high throughput spectrometer/detector system was assembled to achieve the necessary precision in vθ. Statistical errors in the chord-averaged poloidal velocity less than 100 m/s have been obtained. The short focal length spectrometer features f/1.8 input optics, a transmission grating, and refractive optics. A thinned back-illuminated charge coupled device detector provided a high quantum efficiency (QE=75%). The diagnostic h...

Fibrogenic effects of cyclosporin A on the tubulointerstitium : Role of cytokines and growth factors

Abstract: The clinical utility of cyclosporin A (CyA) as an immunosuppressive agent has been significantly limited by the frequent occurrence of chronic nephrotoxicity, characterised by tubular atrophy, interstitial fibrosis and progressive renal impairment. The pathogenesis of this condition remains poorly understood, but has been postulated to be due to either direct cytotoxicity or indirect injury secondary to chronic renal vasoconstriction. Using primary cultures of human proximal tubule cells (PTCs) and renal cortical fibroblasts (CFs) as an in vitro model of the tubulointerstitium, we have been able to demonstrate that clinically relevant concentrations of CyA are directly toxic to these cells and promote fibrogenesis by a combination of suppressed matrix metalloproteinase activity and augmented fibroblast collagen synthesis. The latter effect occurs secondary to the ability of CyA to stimulate autocrine secretion of insulin-like growth factor-I by CFs and paracrine secretion of transforming growth factor-beta(1) by PTCs. Many of these pro-fibrotic mechanisms are completely reversed by concurrent administration of the angiotensin-converting enzyme inhibitor, enalaprilat, which has proven efficacy in preventing chronic CyA nephropathy in vivo. These studies highlight the unique potential that human renal cell cultures offer for studying the role of local cytokine networks in tubulointerstitial disease and for developing more effective treatment strategies which specifically target fibrogenic growth factor activity following nephrotoxic injuries.

Multipulse Thomson scattering system for the National Spherical Torus Experiment

Abstract: A design using a backscattering geometry is presented, which emphasizes high sensitivity and high spatial resolution at the outer edge of the National Spherical Torus Experiment, while providing full profile capability with a moderate number of channels. The design is based on Nd:YAG lasers and avalanche photodiode detectors to allow for high repetition rate measurements.

Hegemonic discourse revisited

Abstract: It is necessary to trust in the oppressed and in their ability to reason. Whoever lacks this trust will fail to initiate (or will abandon) dialogue, reflection, and communication, and will fall into using slogans, communiques, monologues, and instructions. Paulo Freire (1970: 53)

Effective Staff Development in Cooperative Learning: Training, Transfer, and Long-Term Use.

Abstract: Staff development in cooperative learning must focus on three stages of staff development (pre-training, training, and post-training) to achieve at least five purposes. The five purposes are: creating conditions for successful staff development prior to training; conducting high-quality training sessions that result in mastery of the conceptual framework and procedures for using cooperative learning; providing support for the transfer of what is learned in the sessions to the classroom; providing support for the long-term maintenance of the learned procedures; and institutionalization of cooperative learning as a standard instructional practice supported by the district. To achieve the five purposes, eight principles of staff development must be followed: (1) establish long-term goals; (2) avoid the barriers to effective staff development; (3) create collegial teaching teams as the heart of staff development efforts; (4) plan multi-year staff development programs; (5) follow the guidelines for effective preparation for staff development sessions; (6) practice what one teaches in staff development sessions (use cooperative procedures); (7) support implementation between and after training sessions; and (8) change the school's organizational structure from a mass production structure to a team-based, high-performance structure. (Contains 58 references.) (SM) Reproductions supplied by EDRS are the best that can be made from the original document.

In vitro effects of simvastatin on tubulointerstitial cells in a human model of cyclosporin nephrotoxicity

Abstract: To investigate the possibility that 3-hydroxy-3-methylglutaryl CoA (HMGCoA) reductase inhibitors ameliorate renal disease via direct effects on the tubulointerstitium, primary cultures of human proximal tubule cells (PTC) and renal cortical fibroblasts (CF) were exposed for 24 h to simvastatin (0.1–10 μmol/l) under basal conditions and in the presence of 1,000 ng/ml of cyclosporin (CsA), which we have previously shown to promote in vitro interstitial matrix accumulation at least partially via activation of local cytokine networks. Simvastatin, in micromolar concentrations, engendered cholesterol-independent inhibition of CF and PTC thymidine incorporation and cholesterol-dependent suppression of PTC apical Na+/H+exchange (NHE) (ethylisopropylamiloride-sensitive apical22Na+uptake). Similarly, CF secretion of insulin-like growth factor-I (IGF-I) and IGF binding protein-3 were depressed, whereas CF collagen synthesis ([3H]proline incorporation) and PTC secretion of the fibrogenic cytokines, transforming grow...

The use of ternary cations to control nucleation : avoiding binary compounds as reaction intermediates

Abstract: In this article we compare and contrast the evolution of ternary modulated reactants of the form M−Mo−Se (M = Ni, Zn, Sn, In, and Cu) with each other and with the binary Mo−Se system The binary elementally modulated reactants interfacially nucleate MoSe2 over a broad composition range surrounding that of the binary compound Mo6Se8 Increasing the concentration of any of the studied ternary elements except nickel above a critical value in the initial reactant suppressed interfacial nucleation of the diselenide The nickel-containing reactants all interfacially nucleated NixMoSe2 at low temperatures The subsequent nucleation and growth of crystalline compounds from the amorphous intermediates obtained in the other four systems was found to depend on both the identity and concentration of the ternary element In the Sn−Mo−Se system, a layered dichalcogenide was the first compound nucleated In the Zn−Mo−Se system, the dichalcogenide and the ternary compound ZnxMo6Se8 were observed to nucleate at approximat

NSTX high temperature sensor systems

Abstract: The design of the more than 300 in-vessel sensor systems for the National Spherical Torus Experiment (NSTX) has encountered several challenging fusion reactor diagnostic issues involving high temperatures and space constraints. This has resulted in unique miniature, high temperature invessel sensor systems mounted in small spaces behind plasma facing armor tiles, and they are prototypical of possible high power reactor first-wall applications. In the Center Stack, Divertor, Passive Plate, and vessel wall regions, the small magnetic sensors, large magnetic sensors, fluxloops, Rogowski coils, thermocouples, and Langmuir probes are qualified for 600 /spl deg/C operation. This rating will accommodate both peak rear-face graphite tile temperatures during operations and 350/spl deg/C bake-out conditions. Similar sensor systems including flux loops, on other vacuum vessel regions are qualified for 350 /spl deg/C operation. Cabling from the sensors embedded in the graphite tiles follows narrow routes to exit the vessel. The detailed sensor design and installation methods of these diagnostic systems developed for high-powered ST operation are discussed.

Pedestals and confinement in Alcator C-Mod H-modes

Abstract: The study of H-mode regimes, pedestal conditions and confinement is a focus of research on the Alcator C-Mod tokamak. In addition to the usual ELM-free regime, a new regime has been observed on C-Mod which has good energy confinement but lower particle and impurity confinement, named the "Enhanced D-alpha (EDA) H-mode" for one of its signatures [1]. This mode can be steady-state and usually has no discrete ELMs, making it potentially attractive for a reactor. Since the main changes in H-mode are in the plasma edge region, measurements of the pedestal are critical to this study. New, high resolution diagnostics and profiles are described below.

Making of the NSTX facility

Abstract: The NSTX (National Spherical Torus Experiment) facility located at Princeton Plasma Physics Laboratory is the newest national fusion science experimental facility for the restructured US Fusion Energy Science Program. The NSTX project was approved in FY 97 as the first proof-of-principle national fusion facility dedicated to the spherical torus research. On Feb. 15, 1999, the first plasma was achieved 10 weeks ahead of schedule. The project was completed on budget and with an outstanding safety record. This paper gives an overview of the NSTX facility construction and the initial plasma operations.

Diagnostics for initial plasma operations on the National Spherical Torus Experiment

Abstract: The goals of the diagnostic set for initial plasma operations on the National Spherical Torus Experiment (NSTX) are to provide information on the fundamental discharge parameters necessary to characterize NSTX plasmas, and guide NSTX operations for optimized performance. While most of these diagnostics involve relatively straightforward techniques requiring little or no research and development, and rely heavily on reusing existing equipment, a few pose considerable challenges due to the NSTX geometry. Magnetic diagnostics and visible discharge imaging will be the primary systems for plasma control and equilibrium. Confinement and transport studies will be supported by electron temperature, density, and impurity profile diagnostics. Scrapeoff layer and divertor physics will be investigated with spectroscopic and bolometric diagnostics, thermocouples, and edge Langmuir probes. X-ray fluctuation diagnostics and magnetic pickup coils will be provided for MHD stability analysis. The latter impose special difficulties for NSTX, because of the high temperature environment and the very limited space on the center stack. This article provides an overview of the diagnostics planned for the first phase of NSTX, and highlights the design features needed to satisfy the difficult constraints the device imposes on magnetic diagnostics.