Langmuir probe electronics upgrade on the tokamak à configuration variable.

A detailed description of the Langmuir probe electronics upgrade for TCV (Tokamak à Configuration Variable) is presented. The number of amplifiers and corresponding electronics has been increased from 48 to 120 in order to simultaneously connect all of the 114 Langmuir probes currently mounted in the TCV divertor and main-wall tiles. Another set of 108 amplifiers is ready to be installed in order to connect 80 new probes, built in the frame of the TCV divertor upgrade. Technical details of the amplifier circuitry are discussed as well as improvements over the first generation of amplifiers developed at SPC (formerly CRPP) in 1993/1994 and over the second generation developed in 2012/2013. While the new amplifiers have been operated successfully for over a year, it was found that their silicon power transistors can be damaged during some off-normal plasma events. Possible solutions are discussed.

Concept development for the ITER equatorial port visible∕infrared wide angle viewing system.

The ITER equatorial port visible∕infrared wide angle viewing system concept is developed from the measurement requirements. The proposed solution situates 4 viewing systems in the equatorial ports 3, 9, 12, and 17 with 4 views each (looking at the upper target, the inner divertor, and tangentially left and right). This gives sufficient coverage. The spatial resolution of the divertor system is 2 times higher than the other views. For compensation of vacuum-vessel movements, an optical hinge concept is proposed. Compactness and low neutron streaming is achieved by orienting port plug doglegs horizontally. Calibration methods, risks, and R&D topics are outlined.

Nonlinear impact of edge localized modes on carbon erosion in the divertor of the JET tokamak.

The impact of edge localized modes (ELMs) carrying energies of up to 450 kJ on carbon erosion in the JET inner divertor is assessed by means of time resolved measurements using an in situ quartz microbalance diagnostic. The inner target erosion is strongly nonlinearly dependent on the ELM energy: a single 400 kJ ELM produces the same carbon erosion as ten 150 kJ events. The ELM-induced enhanced erosion is attributed to the presence of codeposited carbon-deuterium layers on the inner divertor target, which are thermally decomposed under the impact of ELMs.

Prognostic factors and postoperative course following single-plate Molteno implantation.

We evaluated potential preoperative and early postoperative prognostic indicators for chronic intraocular pressure control in 38 consecutive glaucoma patients undergoing single-plate Molteno implantation. Six months following surgery 22 patients had an intraocular pressure < or = 18 mm Hg and were considered successes. Twelve patients had an intraocular pressure > 18 mm Hg and were considered failures. Factors such as age, race, sex, type of glaucoma, phakic status, eye treated, intraocular pressure, bleb elevation, or number of glaucoma medicines were not significantly related to postoperative intraocular pressure control (p > 0.05). Postoperatively a significant difference in intraocular pressure was not observed between success and failure groups until three (13.8 +/- 5.4 versus 20.8 +/- 6.4 mm Hg, p = 0.010) and six (11.2 +/- 3.3 mm Hg versus 21.2 +/- 1.2 mm Hg, p < 0.001) months. Approximately 50% of patients who had an intraocular pressure > 20 mm Hg and 75% of those who measured < 20 mm Hg at any given examination in the early postoperative period were controlled six months postoperatively. Patients controlled at six months maintained control for as long as 43 months postoperatively. This study indicates that in the early postoperative period after a single-plate Molteno implant some patients have an ocular hypertensive phase but may ultimately be controlled, whereas most patients with an intraocular pressure within the normal range maintain control long-term.

Postoperative prognostic indicators following trabeculectomy.

We evaluated prognostic indicators for long-term filtration from the ocular examination within the first three months following primary trabeculectomy without antimetabolite therapy. We found that in patients who were more easily controlled at one year postoperatively (intraocular pressure < or = 16 mmHg and using 0-2 medications), compared to those who were more difficult to control (> 16 mmHg or on three medications), the intraocular pressure became significantly different between groups at three months and the number of glaucoma medications at eight weeks postoperatively. More easily controlled patients had greater bleb elevation by one month and extent of bleb formation at two weeks postoperatively. The presence of microcysts, anterior chamber depth, and avascularity did not differ between the two groups. This study suggests that differences in the ocular examination exist within the first three months following trabeculectomy which reflect the postoperative intraocular pressure control at one year.

Conjunctival structure and cell counts and the results of filtering surgery.

We evaluated perioperative conjunctival biopsy specimens in 28 consecutive patients with primary open-angle glaucoma undergoing trabeculectomy who had not undergone previous intraocular surgery. We found six months postoperatively that the number of goblet cells was significantly greater (6.40 +/- 5.40 vs 1.68 +/- 1.60 per field of view; P = .004, Student's t-test) in patients with easier postoperative intraocular pressure control (intraocular pressure < or = 15 mm Hg with zero to two glaucoma medications) than in patients with more difficult intraocular pressure control (> 15 mm Hg with three or more glaucoma medications). No statistical differences between groups were observed in mast cells, neutrophils, eosinophils, macrophages, plasma cells, lymphocytes, or fibroblasts (P > .05). Also, no statistical difference between groups existed in conjunctival structure, including mucopolysaccharide and collagen composition, vascular density, or epithelial thickness (P > .05). This study suggests that the number of conjunctival goblet cells may be related to intraocular pressure control after trabeculectomy.

The influence of age upon inflammatory cell counts and structure of conjunctiva in chronic open-angle glaucoma.

We evaluated the influence of age upon conjunctival structure and number of inflammatory cells by studying perioperative conjunctival biopsies from 54 consecutive primary open-angle glaucoma patients undergoing initial filtering surgery (trabeculectomy alone or combined cataract extraction and trabeculectomy). All patients had received chronic topical glaucoma therapy for > 1 year. We divided the patients into three age groups for analysis: 40-60 (n = 10), 61-74 (n = 28), and > 75 (n = 16) years. We found no statistical difference (p > 0.05, chi-square) in cell counts of neutrophils, eosinophils, mast cells, macrophages, fibroblasts, lymphocytes, plasma cells and goblet cells across the three age groups. In addition, no statistical differences were observed between age groups in vascular density, epithelial thickness as well as mucopolysaccharide and collagen composition (p > 0.05, chi square). This study suggests that conjunctival structure and inflammatory cell counts change little with advancing age in primary open-angle glaucoma patients.

The results of trabeculectomy surgery in african-american versus white glaucoma patients.

SUMMARY: We evaluated differences in the results of trabeculectomy surgery in primary open-angle glaucoma in 24 consecutive white glaucoma patients matched to 24 African-American glaucoma patients acting as case controls. One year after surgery we found no statistical difference (p = 0.09, paired t test) in the average intraocular pressure between white (13.4 $pM 3.5 mm Hg) and African-American patients (15.8 $pM 5.0 mm Hg). However, African-American patients had a significantly greater distribution of intraocular pressures (p = 0.04, F distribution test), were taking more glaucoma medicines (1.6 compared with 1.0 for white patients; p = 0.03, Wilcoxon sign rank test), and showed less bleb formation (p = 0.04, Wilcoxon sign rank test). This study suggests that after trabeculectomy, on average, the intraocular pressure in both African-American and white patients may be controlled. However, among different individuals intraocular pressure control may be more inconsistent, require more medicines, and be associated with less bleb formation in African-American than in white patients.

Genomic exclusion and other micronuclear anomalies are common in genetically defective clones of tetrahymena thermophila.

Genomic exclusion (GE) is an abnormal form of conjugation which has previously been described in detail for three hypodiploid strains of Tetrahymena thermophila. These strains cannot form gametic nuclei and by failing to participate in normal reciprocal fertilization their genes are excluded from exconjugants. To determine whether GE is a general property of infertile strains, we surveyed genetically and cytogenetically 19 additional strains of T. thermophila to determine why they failed to contribute genes to sexual progeny. Crosses to genetically marked tester strains showed that seventeen of these strains undergo GE. In each case GE appears to be due to the failure of the defective partner to form functional gametic nuclei. The normal conjugant, however, contributes to its defective partner a haploid nucleus identical to its own, and following diploidization of the unfertilized nuclei, the conjugants separate retaining the old macronuclei. Cytofluorimetric measurement of micronuclear DNA content in 18 strains suggests that aneuploidy is the proximate cause of GE; eleven strains were hypodiploid, five were diploid and three were hyperdiploid. Many irregular cytogenetic events were observed in conjugants presumably not undergoing GE, including, in some instances, abnormal meiosis in the normal partner. Since genomic exclusion was found in both wildtype and mutant clones, the results suggest that it should be possible by appropriate crosses to identify genomic exclusion strains of any genotype.