Pulse ignition characterization of mercury ion thruster hollow cathode using an improved pulse ignitor

An investigation of the high voltage pulse ignition characteristics of the 8 cm mercury ion thruster neutralizer cathode identified a low rate of voltage rise and long pulse duration as desirable factors for reliable cathode starting. Cathode starting breakdown voltages were measured over a range of mercury flow rates and tip heater powers for pulses with five different rates of voltage rise. Breakdown voltage requirements for the fastest rising pulse (2.5 to 3.0 kV/micro sec) were substantially higher (2 kV or more) than for the slowest rising pulse (0.3 to 0.5 kV/micro sec) for the same starting conditions. Also described is an improved, low impedance pulse ignitor circuit which reduces power losses and eliminates problems with control and packaging associated with earlier designs

Defect Identification and Sizing by the Ultrasonic Satellite-Pulse Technique

Type and size are the most important defect characteristics that need to be determined for reliable prediction of the remaining service lifetime of a defective structure or part. The analytical and supporting experimental results presented in this paper concern a universal ultrasonic defect-identificationand- subsequent-sizing method. The conceived satellite-pulse technique (SPT) is based on the interpretation, in terms of defect types and dimensions, of the separation in time-of-arrival between the specularly-reflected pulse and its tip-diffracted or tangentially-scattered satellite contained in the composite defect signal. Several alternate calibration procedures were also developed, any one of which enables the ultrasonic examiner to make the time scale of the oscilloscope read directly in terms of equivalent crack depth or void diameter as appropriate

Removal, Remand, and Review in Pendent Claim and Pendent Party Cases

This Article examines the removability of civil actions that include either pendent claims or pendent parties joined in addition to parties against whom federal questions are alleged. It discusses the remandability of those civil actions or segments of them, and comments on the law governing appellate review of district court remands to state court.\u27 In an effort to reach the wisest resolutions of the various issues posed, it confronts issues of statutory construction, interprets Supreme Court cases, especially Thermtron Products, Inc. v. Hermansdorfer,\u27and wades in the murky waters of federalism. In the course of this enterprise, the Article analyzes and strongly takes issue with the recent decision of the Supreme Court in Carnegie-Mellon University v. Cohill. The implications of Carnegie-Mellon also are explored. The Article focuses on the problems that have arisen and can arise in federal question cases removable, if at all, under 28 U.S.C. sections 1441(a) and (b).\u27 It is noteworthy that these issues arise frequently, as evidenced by the number of pertinent decisions, and promise to continue to plague the federal courts in view of the substantial number of cases removed to federal court. The issues of removal jurisdiction, remandability, and reviewability tackled here are questions of federal court jurisdiction, powers, and discretion, that broadly implicate our federalism

Microarray gene expression profiling of neural tissues in bovine spastic paresis

Abstract: Background: Bovine Spastic Paresis (BSP) is a neuromuscular disorder which affects both male and female cattle. BSP is characterized by spastic contraction and overextension of the gastrocnemious muscle of one or both limbs and is associated with a scarce increase in body weight. This disease seems to be caused by an autosomal and recessive gene, with incomplete penetration, although no genes clearly involved with its onset have been so far identified. We employed cDNA microarrays to identify metabolic pathways affected by BSP in Romagnola cattle breed. Investigation of those pathways at the genome level can help to understand this disease. Results: Microarray analysis of control and affected individuals resulted in 268 differentially expressed genes. These genes were subjected to KEGG pathway functional clustering analysis, revealing that they are predominantly involved in Cell Communication, Signalling Molecules and Interaction and Signal Transduction, Diseases and Nervous System classes. Significantly enriched KEGG pathway's classes for the differentially expressed genes were calculated; interestingly, all those significantly under-expressed in the affected samples are included in Neurodegenerative Diseases. To identify genome locations possibly harbouring gene(s) involved in the disease, the chromosome distribution of the differentially expressed genes was also investigated. Conclusions: The cDNA microarray we used in this study contains a brain library and, even if carrying an incomplete transcriptome representation, it has proven to be a valuable tool allowing us to add useful and new information to a poorly studied disease. By using this tool, we examined nearly 15000 transcripts and analysed gene pathways affected by the disease. Particularly, our data suggest also a defective glycinergic synaptic transmission in the development of the disease and an alteration of calcium signalling proteins. We provide data to acquire knowledge of a genetic disease for which literature still presents poor results and that could be further and specifically analysed in the next future. Moreover this study, performed in livestock, may also harbour molecular information useful for understanding human diseases

Electrically detected magnetic resonance of carbon dangling bonds at the Si-face 4H-SiC/SiO2_2 interface

SiC based metal-oxide-semiconductor field-effect transistors (MOSFETs) have gained a significant importance in power electronics applications. However, electrically active defects at the SiC/SiO$_2$ interface degrade the ideal behavior of the devices. The relevant microscopic defects can be identified by electron paramagnetic resonance (EPR) or electrically detected magnetic resonance (EDMR). This helps to decide which changes to the fabrication process will likely lead to further increases of device performance and reliability. EDMR measurements have shown very similar dominant hyperfine (HF) spectra in differently processed MOSFETs although some discrepancies were observed in the measured $g$-factors. Here, the HF spectra measured of different SiC MOSFETs are compared and it is argued that the same dominant defect is present in all devices. A comparison of the data with simulated spectra of the C dangling bond (P$_\textrm{bC}$) center and the silicon vacancy (V$_\textrm{Si}$) demonstrates that the P$_\textrm{bC}$ center is a more suitable candidate to explain the observed HF spectra.Comment: Accepted for publication in the Journal of Applied Physic