Four-wave mixing of incoherent light in a dispersion-shifted fiberusing a spectrum-sliced fiber amplifier light source

We investigate the FWM efficiency of incoherent light in a dispersion-shifted fiber (DSF) using a spectrum-sliced fiber amplifier light source. A theoretical model is provided to describe the FWM mechanism of incoherent light. The FWM efficiencies of coherent and incoherent light are compared theoretically and experimentally. Unlike the FWM of coherent light, the FWM signals of incoherent light are mostly generated by nondegenerate FWM regardless of the number of input signals. Thus, when two input signals are mixed, incoherent light has about 6 dB higher mixing efficiency than coherent light due to the difference in their degeneracy factor     

Optimal time-frequency deconvolution filter design fornonstationary signal transmission through a fading channel: AF filterbank approach

The purpose of this paper is to develop a new approach-time-frequency deconvolution filter-to optimally reconstruct the nonstationary (or time-varying) signals that are transmitted through a multipath fading and noisy channel. A deconvolution filter based on an ambiguity function (AF) filter bank is proposed to solve this problem via a three-stage filter bank. First, the signal is transformed via an AF analysis filter bank so that the nonstationary (or time-varying) component is removed from each subband of the signal. Then, a Wiener filter bank is developed to remove the effect of channel fading and noise to obtain the optimal estimation of the ambiguity function of the transmitted signal in the time-frequency domain. Finally, the estimated ambiguity function of the transmitted signal in each subband is sent through an AF synthesis filter bank to reconstruct the transmitted signal. In this study, the channel noise may be time-varying or nonstationary. Therefore, the optimal separation problem of multicomponent nonstationary signals is also solved by neglecting the transmission channel     

Increased living donor volunteer rates with a formal recipient family education program

As part of our ongoing studies to characterize molecular alterations in a well-defined series of surgically resected esophageal cancers, we examined the expression of 2 ras-regulated genes, whose products (osteopontin and cathepsin L) previously were shown to be associated with tumor invasion and metastasis. RNA was extracted from primary esophageal tumors (adenocarcinomas, 19; squamous-cell carcinomas, 6) and matched histologically normal esophageal mucosa from the distant resection margin. Northern analysis was used to quantitate RNA, relative to an 18S rRNA control, and immunohistochemistry to assess the tissue distribution of osteopontin. In addition, H-, K- and N-ras mutations were studied in the same tissues using PCR and hybridization with allele (mutant)-specific oligonucleotide probes. We demonstrated a K-ras mutation (codon 12, GTT) in one esophageal adenocarcinoma. The ras-regulated gene osteopontin was over-expressed in 100% of squamous-cell carcinomas and in 58% of adenocarcinomas relative to matched normal esophageal mucosa. Patterns of immunoreactivity for osteopontin protein also varied between squamous-cell carcinomas (tumor cell staining) and adenocarcinomas (predominantly tumor-infiltrating macrophages). Expression of cathepsin L also varied with esophageal tumor histology, with over-expression in 58% of primary esophageal adenocarcinomas and 33% of squamous-cell cancers.     

Pressure electrical contact improved by carbon black paste

Pressure and pressureless electrical contacts were evaluated by measuring the contact electrical resistivity between copper mating surfaces. Pressure electrical contacts with a contact resistivity of 2×10⁻⁵ Ω·cm² have been attained using a carbon black paste of a thickness of less than 25 μm as the interface material. In contrast, a pressureless contact with silver paint as the interface material exhibits a higher resistivity of 3×10⁻⁵ Ω·cm² or above. A pressureless contact with colloidal graphite as the interface material exhibits the same high contact resistivity (1×10⁻⁴ Ω·cm²) as a pressure contact without any interface material. On the other hand, pressureless contacts involving solder and silver epoxy exhibit lower contact resistivity than carbon black pressure contacts.     

Malignancy associated with hepatolithiasis

BACKGROUND/AIMS: Malignancy is known to be associated with hepatolithiasis. The present report summarizes the results of our management of patients with cholangiocarcinoma associated with hepatolithiasis. MATERIALS AND METHODS: Twenty patients with cholangiocarcinoma and associated hepatolithiasis were analyzed retrospectively. There were 12 males and 8 females, with a mean age of 59.3 years. The clinical records of these patients were reviewed to determine demographic characteristics, clinical features, laboratory findings, diagnostic tests, operative management and results of therapy. RESULTS: One patient was moribund on presentation and was treated conservatively. Fourteen patients underwent hepatic resection. Three of them had palliative resection. Hepatic resection was less likely to be performed in patients having right lobe disease (50%) as compared to patients having left lobe disease (90%) (p = NS). The overall operative morbidity and mortality rates after hepatic resection were 36% and 7%, respectively. Non-resective operations were performed in five patients. The overall operative morbidity and mortality rates after non-resective operations were 20% and 0%, respectively. After curative hepatic resection (11 patients), the 1- and 2-year survival rates were 81% and 51%, respectively. CONCLUSIONS: A suspicion of malignancy is necessary in managing patients with hepatolithiasis. Hepatic resection is the treatment of choice for cholangiocarcinoma when it is resectable.     

Analysis and reduction of dark zone in ultra‐thin wedge‐plate displays

Abstract— A wedge plate can be used as the screen of a display, and the thickness of the display can be incredibly thin. In this paper, a basic formula for ray tracing in such a wedge plate is deduced. The fundamental limitation on the display quality of a wedge plate is explored, and the formation of a dark zone on the display screen is analyzed and verified numerically. Experimental exploration and confirmation of one 14‐in. acrylic wedge plate with a white‐light‐emitting diode is also provided. Two approaches to eliminate the dark zone are proposed, and the corresponding numerical demonstration of a 52‐in. wedge‐plate display is also shown.     

Parallel Algorithms for Perceptual Grouping on Distributed Memory Machines

Perceptual grouping is a key intermediate-level vision problem. Parallel solutions to this problem are characterized by uneven distribution of symbolic features among the processors, unbalanced workload, and irregular interprocessor data dependency caused by the input image. In this paper, we propose two load-balancing techniques for parallelizing perceptual grouping on distributed-memory machines. By using an initial workload estimate, we first partition the computations to distribute the workload across the processors. In addition, we asynchronously perform ongoing task migrations to adapt to the unbalanced workload which may evolve differently from the initial estimate. We also discuss two strategies to manage the irregular interprocessor data dependency. To illustrate our ideas, perceptual grouping steps used in an integrated vision system for building detection are used as examples. Our experimental results show that, given 8K extracted line segments from a 1K × 1K image, both the line and junction grouping steps can be completed in 0.644 s on a 32-node SP2 and in 0.585 s on a 32-node T3D. For the same grouping steps, a serial implementation requires 10.550 s and 10.023 s on a single node of SP2 and T3D, respectively. The implementations were performed using the message passing interface standard and are portable to other high performance computing platforms.