Soft-decision Viterbi decoding with diversity combining

Diversity combining methods for convolutional coded and soft-decision Viterbi decoded channels in mobile satellite communications systems are evaluated and it is clarified that the pre-Viterbi-decoding maximal ratio combining shows better performance than other methods in Rician fading channels by computer simulation. A novel practical technique for maximal ratio combining is proposed, in which the coefficients for weighting are derived from soft-decision demodulated signals only. The proposed diversity combining method with soft-decision Viterbi decoding requires simple hardware and shows satisfactory performance with slight degradation of 0.3 dB in Rician fading channels compared with an ideal weighting scheme. Furthermore, this diversity method is applied to trellis coded modulation and significant Pe performance improvement is achieved

Inverse Unfold Problem and Its Heuristic Solving

Unfold/fold transformations have been widely studied in various programming paradigms and are used in program transformations, theorem proving, and so on. This paper, by using an example, show that restoring an one-step unfolding is not easy, i.e., a challenging task, since some rules used by unfolding may be lost. We formalize this problem by regarding one-step program transformation as a relation. Next we discuss some issues on a specific framework, called pure-constructor systems, which constitute a subclass of conditional term rewriting systems. We show that the inverse of T preserves rewrite relations if T preserves rewrite relations and the signature. We propose a heuristic procedure to solve the problem, and show its successful examples. We improve the procedure, and show examples for which the improvement takes effect

Fluorescence diagnosis of metastatic lymph nodes using 5-aminolevulinic acid (5-ALA) in a mouse model of colon cancer.

[Background]Lymph node metastasis is one of the most critical prognostic factors in patients with colorectal cancer. Although regional lymph nodes should be surgically resected and pathologically examined, techniques for the intraoperative diagnosis of lymph node metastasis remain to be well established. Fluorescence diagnosis using 5-aminolevulinic acid (5-ALA) is a promising technique for evaluating various malignancies. After exogenous administration of 5-ALA, protoporphyrin IX (PPIX) accumulates in malignant cells and can be detected as red fluorescence. In this study, we investigated the usefulness of fluorescence diagnosis using 5-ALA for the detection of lymph node metastasis in a mouse model of colon cancer. [Materials and Methods]An orthotopic colon cancer model was prepared by inoculating the cecal wall of nude mice with HCA7, a human colon adenocarcinoma cell line. After 3 wk, 40 mg/kg of 5-ALA was administered intraperitoneally (IP) or orally (PO). Fluorescence diagnosis with a D-Light System (Karl Storz) was then performed after 3 or 6 h. [Results]In the IP group, PPIX fluorescence was detected in metastatic lymph nodes as well as in other malignant lesions, including primary tumors and abdominal implantations, while non-metastatic nodes were fluorescence-negative. In contrast, no obvious fluorescence was detected in cancerous tissues in the PO group. [Conclusions]PPIX fluorescence induced by intraperitoneal injection of 5-ALA allows metastatic lymph nodes to be accurately diagnosed in this mouse model. This technique may facilitate the intraoperative diagnosis of lymph node metastases from colon cancer in a clinical setting

Thermodynamics of the S=1 spin ladder as a composite S=2 chain model

A special class of S=1 spin ladder hamiltonians, with second- neighbor exchange interactions and with anisotropies in the $z$-direction, can be mapped onto one-dimensional composite S=2 (tetrahedral S=1) models. We calculate the high temperature expansion of the Helmoltz free energy for the latter class of models, and show that their magnetization behaves closely to that of standard XXZ models with a suitable effective spin $S_{eff}$, such that $S_{eff}(1+S_{eff})=$, where ${\bf S}_i$ refers to the components of spin in the composite model. It is also shown that the specific heat per site of the composite model, on the other hand, can be very different from that of the effective spin model, depending on the parameters of the hamiltonian.Comment: 17 pages, 4 figures. Submitted for publicatio