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GaN device is a potential alternative to SiC as a wide band gap device. At present, there are almost no high-voltage GaN devices above 650 V, which makes an inverter design difficult for three-phase input using the standard two-level (2L) inverters. Therefore, at present, a three-level (3L) inverter is an obvious choice for the GaN inverter for three-phase 400/480 V input applications. Moreover, a 2L inverter suffers from drawbacks like increased filtering efforts, high dv/dt and limited switching frequency due to the effect of power loss on semiconductors. Therefore, at the medium-to-high-power level, a hard switched GaN inverter with a 2L structure is still questionable. To address some of the challenges, this study brings in a 700 V dc-link-based three-phase, 3L inverter with GaN and SiC diodes. This study discusses multiple aspects of the design such as (a) advantages over the 2L design at a higher power, (b) filters designs, (c) power losses in the devices and (d) design challenges of the inverter through comprehensive simulation models and experimental investigations. The study claims that the GaN inverter for the medium-to-high-power level makes more sense with a 3L design.

The Advanced Photon Source Upgrade includes four 4.8-m-long superconducting undulator (SCU) cryostats, each containing two planar undulator NbTi magnets up to 1.9 m long. The cooling is provided by six cryocoolers arranged in three thermal circuits. The magnets are indirectly cooled with LHe penetrating through channels in the magnet cores. This 4 K circuit, which also includes a LHe tank, is cooled by five 4 K cryocooler 2nd stages. A beam vacuum, which is thermally isolated from the magnets, is cooled by one 10 K cryocooler 2nd stage. A thermal shield and warm parts of current leads are cooled by the 1st stages of all six cryocoolers. This paper presents an ANSYS-based thermal analysis of the new SCU cryostat including all thermal circuits. The benchmarked thermal conductance between the cryocooler cold heads and the LHe tank are used in the calculations as well as the measured cryocooler load lines. The model predicts temperatures in the system, total 4 K heat loads, and excess cooling power for various operational modes of the undulator.

The Advanced Photon Source (APS) is in the midst of a major facility upgrade including both a new electron storage ring (SR) and many new insertion devices (IDs) providing x-ray photon beams to a new suite of experimental end stations. Included among the new IDs are four 4.8-meter superconducting undulator (SCU) cryostats, each containing two 1.8-meter planar undulator magnets operating at 4.2 K in either a phase shifted or canted configuration. We describe a new, compact cryocooler-based cryostat design which supports the magnets and associated subsystems and also fits the space constraints of the SR ID straight sections. The design is an evolution of earlier single-magnet 2-meter cryostats, retaining some subsystem commonality while incorporating lessons learned and several features unique to the challenge of supporting two independently operable undulator magnets in a single device.

It has been suggested that elevated concentrations of ovarian steroids during superovulatory treatment may be a cause of poor superovulatory yields in ewes. The aim of this study was to examine the correlations between daily serum concentrations of estradiol-17β (E2-17β) and progesterone concentrations, ovarian responses and in vivo embryo production in anestrous ewes superovulated in a multiple-dose pFSH regimen. Twelve clinically healthy Rideau Arcott ewes were used in the study (May–June). Medroxyprogesterone acetate (MAP)-releasing intravaginal sponges (60 mg) were inserted for 14 days, and 12 days after insertion of the sponges, 6 im injections of pFSH (Folltropin®-V) were administered (1 × 2.5 ml and 5 × 1.25 ml) at 12-h intervals. Injections were administered at 20:00 and 08:00 h, beginning on Day 12 and finishing on Day 15 following sponge insertion. At the first pFSH treatment, all ewes received a single im injection of eCG (500 IU). Sponges were removed at the time of the 5th pFSH injection, and on the evening of Day 15 all ewes received an im injection of GnRH (50 μg). Ewes were then placed in an enclosed paddock with 2 adult Rideau Arcott rams for a 36-h period and embryos were recovered surgically 7 days after the GnRH injection. Daily blood samples (14:00 h) were drawn for the 10-day period from the onset of ovarian superstimulation. Serum concentrations of E2-17β on the day of the 1st pFSH dose were negatively correlated to the numbers of embryo (Grades 1–3) (r = −0.62; P

A superconducting transmission line magnet test facility was built and commissioned at Fermilab. The test facility is capable of generating a 100 kA current in a 17-meter length short-circuited superconducting loop, as well as driving 15 m long test magnets. The current is excited by a room temperature primary winding and iron yoke operated as a current transformer. This approach avoids the expense and difficulty of 100 kA current leads, and allows the facility to be Dewar-based. The loop has a replaceable superconductor section 4 m long for testing various types of VLHC transmission line cables. The system design, 3D magnetic field analysis, magnetic force distribution and test results are discussed.

We describe a 50-year-old man with a 10-year history of gradually enlarging limbal tumors and conjunctival injection. An excised limbal mass presented a diagnostic challenge histopathologically and was initially believed to be a fibrous histiocytoma. Special stains, however, revealed acid-fast organisms in the fibrous histiocytes, and the diagnosis was changed to corneal leproma. This case confirms the existence of fibrous histiocytoma-like lesions in leprosy, which in this form can be termed fibrous histiocytoid leprosy. Furthermore, it suggests the need for special stains to rule out infectious cause in lesions believed to be atypical fibrous histiocytomas.

The synchronization of follicular waves with medroxyprogesterone acetate (MAP) and oestradiol-17beta (E(2)-17beta) prior to ovarian superstimulation in anoestrous ewes reduces the variability in superovulatory responses by an unknown mechanism. Follicle stimulating hormone (FSH) is a primary promoter of antral follicular development, but the relevance of circulating FSH concentrations to the superovulation performance in ewes has not been examined. Eighteen anoestrous Rideau Arcott ewes (May-June) were superovulated with Folltropin-V (porcine FSH), with (n = 8; treated ewes) or without (n = 10; control ewes) a single i.m. dose of 350 microg of E(2)-17beta, given on the sixth day of a 14-day treatment with MAP-releasing intravaginal sponges (60 mg). The superovulatory treatment, begun 6 days after E(2)-17beta injection, consisted of six i.m. applications of Folltropin-V given twice daily (at 08:00 and 16:00 h), followed by an i.m. injection of GnRH (50 microg). Blood samples collected every 8 h throughout the 3-day treatment, were analysed by radioimmunoassays for concentrations of ovine and porcine FSH, using species-specific standards and primary antibodies. Serum concentrations of oFSH were greater (p0.05) in the controls compared to treated ewes at 40, 64 and 72 h and the variability in mean oFSH concentrations was greater (p0.05) in control ewes at 40, 48, 64 and 72 h after the 1(st) Folltropin-V injection. There were no differences (p0.05) between the two groups in serum concentrations of pFSH. Significant correlations were recorded between the number of corpora lutea (CL) and oFSH concentrations at 8 h (r = 0.72, p0.05), 16 h (r=0.63, p0.05) and 64 h (r = 0.84, p0.01) after the 1(st) Folltropin-V injection. The total number of recovered embryos was positively correlated to oFSH concentrations at 56 h (r = 0.69, p0.05). We concluded that changes in endogenous FSH concentrations during ovarian superstimulation with pFSH might contribute to the variability in superovulatory responses in ewes.

The roles of different free exciton formation mechanisms in bulk AlGaAs were studied. The dependencies of the shape of Hanle curves on excitation power were analyzed. It was shown that geminate exciton formation mechanism dominates at low excitation intensities.

The Hanle effect for free excitons in high purity AlGaAs alloys is studied. At very low excitation by interband transitions due to absorption of nonresonant light, a high degree of circular polarization (about 35 %) was observed. The effect is explained by relaxation of geminate excitons into localized states near band edge due to emission of LO‐phonons.

A research and development program is underway to construct superconducting cavities to be used for radiofrequency separation of a kaon beam at Fermilab. The design calls for installation of twelve 13-cell cavities operating in the 3.9 GHz transverse mode with a deflection gradient of 5 MV/m. We present the mechanical, cryogenic and vacuum design of the cavity, cryomodule, rf power coupler, cold tuner and supporting hardware. The electromagnetic design of the cavity is presented in a companion paper by Wanzenberg and McAshan (2001). The warm tuning system (for field flatness) and the vertical test system will be presented along with test results of bench measurements and cold tests on single-cell and five-cell prototypes.

The Na(+)/H(+) exchangers (NHEs) are among the major ion transporters involved in cell volume regulation. NHE activation leads to a cellular influx of Na(+) ions and extrusion of H(+) ions, which are readily replenished from intracellular buffers. This will result in a net import of Na(+). In many systems NHE operates in parallel to Cl(-)/ HCO3(-) exchange, resulting in cellular uptake of NaCl. The influx of osmotically obliged water will consequently lead to cell swelling. This makes NHEs suitable to serve as powerful mechanisms for increasing cell volume (CV). The low volume threshold for NHE activation enables the cells to respond to very minute reductions of the CV. By the coupling to the export of H(+) ions cell volume regulatory NHE activation may lead to changes in intracellular pH. On the other hand NHEs are activated by a broad variety of ligands and by intracellular acidosis, which, in turn, may consequently lead to cell swelling. In addition, NHEs are linked to other intracellular proteins and structures, like e.g. the cytoskeleton, which themelves are involved in the regulation of numerous cellular processes. Therefore NHEs link CV regulation to a diversity of cellular functions, both in physiological and pathophysiological conditions. Six isoforms of the Na(+)/H(+) exchanger, termed NHE1--6, have been cloned so far. NHE 1--5 are located in the plasma membrane, whereas NHE6 is sorted to the mitochondrial membrane. NHE1 and NHE6 are the ubiquitously expressed isoforms. The expression of the isoforms NHE2 to NHE5 is restricted to specific tissues and the pattern of their expression, as well as their subcellular localization indicate that they fulfill specialized functions. Cell shrinkage induced activation has been shown for NHE1,2 and 4. In contrast, NHE3 is inhibited by cell shrinkage. In many cells several isoforms are present and assigned to specific membrane domains where they may serve a functional crosstalk between the different ion transporters.

In an alluvial basin with an area of about 1000 km2 agricultural, domestic and industrial water requirements are covered by groundwater pumping. Due to the overexploitation of the aquifer which is hydraulically linked with the Danube, the groundwater table has become remarkably lower within the last twenty years. To overcome water shortage and to improve environmental conditions several water management alternatives have been elaborated. All the plans are related to improved groundwater management strategies. The objective of this paper is to describe an integrated model assisting governmental water authorities in water and environmental decision making. For this purpose water management scenarios can be easily interactively generated and subsequently analysed in its hydrological consequences. The scenarios include alternative sites for hydropower schemes and alternative measures for artificial groundwater recharge. The model consists of several components such as a relational data base, analytical tools, a two dimensional finite difference groundwater model and functional units from a geographical information system. These tools are integrated by a user friendly interface. The data base is designed to handle time series, spatial data, tables and texts. The analytical tools refer to time series analysis, spatial statistical analysis and facilities for overlays.

Fermilab is upgrading the Tevatron for lower temperature/higher beam energy operation. Portions of the satellite refrigeration system will operate below atmospheric pressure after the upgrade is complete. Contamination must be prevented by hermetically sealing the subatmospheric helium to air interfaces. Bayonet connections in the low pressure flow path require a reliable, leak tight isolation valve instead of the standard quarter turn ball valve. Design, development, and production of a new valve are described.

Many U.S. Army installation directorates of Engineering and Housing, having introduced equipment management systems, now seek to optimize use of the vast amount of information these systems can provide. This report presents outline specifications for a computerized expert system to support fleet management decisions. Included are: (1) an outline of some of the decisions that equipment management systems can help to make, (2) an explanation of the principles of economic analysis that underlie such decisions, (3) a description of the data structures required by an equipment management system, and (4) a description of the kinds of forecasts such a system can generate. Most of the findings of this report are equally applicable to any public works organization. Keywords: Army facilities, Army equipment, Inventory analysis, Inventory control, Management information systems.

Equipment shops in the U.S. Army Directorates of Engineering and Housing (DEHs) normally use written files to maintain records and inventories, and to author reports. This report describes criteria for selection and implementation of commercially available, computer-based vehicle and equipment maintenance management systems that automate those tasks. Capabilities of appropriate management systems are described, including the use of bar code technology. Two systems (JP systems' ShopFax, and Prototype's EMS/PC) were selected for test implementation at three Army installations (Fort Lee, VA; Fort Riley, KS; and Fort Meade, MD). This report details the experiences of each installation with the introduction of a computer-based management system, and the benefits derived from that introduction. Recommendations are made as to the circumstances under which each system is more suitable.

The effects of four subtypes of recombinant human alpha interferon (RIFN alpha), (A,B,D, and the hybrid A/D) were tested on six strains of herpes simplex virus (HSV). RIFN alpha -D was the most effective subtype in rabbit kidney cells, which is consistent with our previous in vivo results in the rabbit herpetic keratitis model. In human corneal cells, however, RIFN alpha -D was one of the least effective IFN subtypes tested. Conversely, RIFN alpha-A appeared to be relatively more effective in the human corneal cells than in the rabbit kidney cells, but RIFN alpha -B and RIFN alpha -A/D were the most effective interferon subtypes in human corneal cells. Different strains of HSV had different susceptibilities to the various IFN subtypes tested.

Overcorrection and progressive hyperopia are known complications of radial keratotomy. In an attempt to develop a surgical correction for this complication, a relative hyperopia was induced in New Zealand white rabbits by radial keratotomy. Six to eight weeks after surgery, hexagonal keratotomy was performed. Two months after hexagonal keratotomy, refraction indicated an average reduction in the surgically induced hyperopia of 2.74 diopters. This study indicates that hyperopia induced by radial keratotomy can be corrected by hexagonal keratotomy

A technic is described for the treatment of the “difficult” duodenal stump. It uses the stomach remnant with its rather healthy tissue to “close” the duodenal stump, no matter how short its cuff and to what degree the tissue texture had been changed by the underlying disease process. This technic eliminates an unsafe closure of the duodenum and a catheter duosenostomy with their associated mortality and morbidity. Its application in ten typical cases resulted in postoperative courses free of mortality and morbidity related to the gastroduodenostomy.

Nine patients had birdshot retinochoroidopathy. Associated ophthalmologic findings included rhegmatogenous retinal detachment, rubeosis iridis, glaucoma, and a high incidence of disciform macular degeneration. Four patterns of birdshot spot distribution were noted on fundus examination. Immunologic studies showed a significantly elevated percentage of EA rosettes and an elevated C4 complement level. Electroretinograms showed b-wave amplitude reduction, with a disproportionate implicit time prolongation. The etiology of this syndrome remains unknown.

K-582, a new basic peptide antibiotic, was tested in rabbits with experimental Candida keratitis. It was shown that the K-582-treated group showed statistically highly significant therapeutic effects on days 2 and 3, as compared with the control group (day 2: P less than 0.001; day 3: P less than 0.001). The culture study showed that the average number of colonies was 1,573.1 in the controls and 463.3 in the treated group, and the difference was highly significant statistically (P less than 0.001). No ocular or systemic toxic effects were observed with this drug. K-582 is a promising new drug for the treatment of Candida keratitis.