Architectural issues related to the optical implementation of an EGS network based on embedded control

Free-space optical implementations of switching networks have been proposed to circumvent many of the system-level problems that may be encountered in systems that require many high-density, high-bandwidth connections. The details of a new class of switching network (the EGS network), that is well-suited to free-space implementations, is described. The common control injection problem that plagues most free-space photonic networks, i.e. how can control information from an electronic source be injected into the network for applications that require relatively high network reconfiguration rates, is examined. A new technique for control injection, called embedded control, which permits network operation even with relatively high network reconfiguration rates is also proposed.     

Zur Trennung des Nickels von Eisen

Ohne Zusammenfassung     

Total Positivity Properties of Generalized Hypergeometric Functions of Matrix Argument

In multivariate statistical analysis, several authors have studied the total positivity properties of the generalized (₀ F ₁) hypergeometric function of two real symmetric matrix arguments. In this paper, we make use of zonal polynomial expansions to obtain a new proof of a result that these ₀ F ₁functions fail to satisfy certain pairwise total positivity properties; this proof extends both to arbitrary generalized ( _r F _s ) functions of two matrix arguments and to the generalized hypergeometric functions of Hermitian matrix arguments. In the case of the generalized hypergeometric functions of two Hermitian matrix arguments, we prove that these functions satisfy certain modified pairwise TP₂properties; the proofs of these results are based on Sylvester's formula for compound determinants and the condensation formula of C. L. Dodgson [Lewis Carroll] (1866).     

Structural and electrical characterization of PZT on gold for micromachined piezoelectric membranes

Piezoelectric membranes have been fabricated that incorporate a gold bottom electrode with an adhesion layer of titanium–tungsten (10:90 wt. %). For solution-deposited acetic acid based lead zirconate titanate (HoAc-PZT) with a Zr:Ti ratio of 40:60, the film’s average piezoelectric coefficient, e₃₁, is -5.31 C/m², with a dielectric constant of 814 at 200 Hz, which is similar to values for platinum bottom electrodes. The PZT structure remains columnar on both types of bottom electrodes. Initial fabrication attempts resulted in cracking that initiated in the PZT layer of the structure. X-ray photoelectron spectroscopy was utilized to establish how processing affects diffusion throughout the composite membrane structure. Crack-free membranes were fabricated and tested. This paper discusses the performance properties and piezoelectric fatigue results for these membranes. PACS 77.84.-s; 77.84.Lf     

Detection of a systemic effect of malignancy in vivo by magnetic resonance imaging

In animals bearing tumors prolongation of spin lattice relaxation time (T1) has been detected in vitro in organs not directly affected by the malignancy. This has been termed the "Systemic Effect." In this study the possible existence of such an effect in the liver, muscle and fat of humans with lymphoma has been investigated. In vivo T1 measurements were made using a low field strength (0.08 Tesla) magnetic resonance imager. The mean liver T1 for 19 lymphoma patients with normal liver histology was 206 ms, compared with a mean of 191 ms for 61 volunteers (p less than 0.0001). Among these patients prolongation of liver T1 was related to the extent of disease elsewhere in the body. For 23 patients with Hodgkin's disease (HD) examined at the time of diagnosis, liver T1 was significantly correlated with other known markers of disease extent or activity (alkaline phosphatase level, erythrocyte sedimentation rate and the presence of systemic symptoms). No such correlations were observed among 25 patients with non-Hodgkin's lymphoma (NHL). Muscle and fat T1 was measured in 26 patients with lymphoma, 14 patients with acute leukemia and 88 volunteers. Seven of the patients with lymphoma and 2 of those with leukemia had muscle T1 values above the range observed for volunteers. Similarly, 3 patients with lymphoma and 1 with leukemia had prolonged fat T1. These findings indicate that a systemic effect of malignancy on T1 is detectable in a proportion of humans with lymphoma or leukemia.