Cocycle Properties of String Theories on Orbifolds

We study cocycle properties of vertex operators and present an operator representation of cocycle operators, which are attached to vertex operators to ensure the duality of amplitudes. It is shown that this analysis makes it possible to obtain the general class of consistent string theories on orbifolds.Comment: 40 pages (Talk given at Workshop on ``Recent Developments in String and Field theory", Kyoto, Japan on September 9-12, 1991.

Analysis of the Wheeler-DeWitt Equation beyond Planck Scale and Dimensional Reduction

We solve the Wheeler-DeWitt equation for {\it four}-dimensional Einstein gravity as an expansion in powers of the Planck mass by means of a heat kernel regularization. Our results suggest that in the universe with a very small radius or with a very large curvature beyond a Planck scale expectation values of operators are reduced to calculations in a path integral representation of {\it three}-dimensional Einstein gravity.Comment: 9 pages, latex file, KOBE-TH-94-0

An additive basis for the cohomology rings of regular nilpotent Hessenberg varieties

In this paper we construct an additive basis for the cohomology ring of a regular nilpotent Hessenberg variety which is obtained by extending all Poincare duals of smaller regular nilpotent Hessenberg varieties. In particular, all of the Poincare duals of smaller regular nilpotent Hessenberg varieties in the given regular nilpotent Hessenberg variety are linearly independent.Comment: 41 pages, 7 figure

Topological Aspects of an Antisymmetric Background Field on Orbifolds

We study string theory on orbifolds in the presence of an antisymmetric constant background field in detail and discuss some of new aspects of the theory. It is pointed out that the term with the antisymmetric background field can be regarded as a topological term like a Chern-Simons term or a Wess-Zumino term. Detailed analysis in the operator formalism shows that orbifold models with topologically nontrivial twists exhibit various anomalous behavior: Zero mode variables obey nontrivial quantization conditions. Coordinate transformations which define orbifolds are modified at quantum level. Wave functions of twisted strings in general acquire nontrivial phases when they move around non-contractible loops on orbifolds. Zero mode eigenvalues are shifted from naively expected values, in favor of modular invariance.Comment: 45 pages, Latex file, NBI-HE-93-01, KOBE-TH-93-0

Impact of Tributyltin and Triphenyltin on Ivory Shell (Babylonia japonica) Populations

We histopathologically examined gonads and chemically determined organotin compounds in tissues of the ivory shell, Babylonia japonica. Imposex (a superimposition of male-type genital organs on females) occurred in approximately 80–90% of B. japonica specimens that we examined, with the penis and vas deferens both well developed. No oviduct blockage by vas deferens formation was observed. Ovarian spermatogenesis and suppressed ovarian maturation were observed in the females that exhibited imposex, although no histopathological abnormalities were found in males. Tissue distributions of organotin compounds [tributyltin (TBT), triphenyltin (TPhT), and their metabolites] were different for butyltins and phenyltins; a remarkably high accumulation of TBT was observed in the ctenidium, osphradium, and heart, whereas high concentrations of TPhT were detected in the ovary and digestive gland. More than one-third of TBT accumulated in the digestive glands of both males and females, followed by the testis, ctenidium, muscle, and heart tissues in males and in the muscle, ovary, ctenidium, and head tissues (including the central nervous system ganglia) in females. In both males and females, more than half of total TPhT accumulated in the digestive glands, followed by the gonads. The next highest values were in the muscle, ctenidium, and heart tissues in males and in the muscle, oviduct, and head tissues in females. Both TBT and TPhT concentrations in the gonads were positively correlated with penis length in females. Our findings strongly suggest that reproductive failure in adult females accompanied by imposex, possibly induced by TBT and TPhT from antifouling paints, may have caused the marked decline of B. japonica populations in Japan

Contamination of organotin compounds and endocrine disruption in gastropods

Abstracts of 2nd UNU-ORI joint international workshop for marine environment第2回海洋環境国際ワークショップ講演要

Long-term Survival of a Case of Rectal Neuroendocrine Carcinoma with Liver Metastasis

Colorectal neuroendocrine carcinoma（NEC）is extremely rare and has a dismal prognosis. However, no standardized treatment strategy has been established for this lesion. For patients with NEC and distant metastasis, disease stabilization is difficult even after treatment with multidisciplinary strategies including chemotherapy. Here we describe a case of rectal NEC that presented as multiple liver metastases; a favorable prognosis was obtained after treatment with a multidisciplinary strategy that included surgery, irradiation, and chemotherapy. A 66-year-old male presented with diarrhea and constipation. Colonoscopy and a computed tomography（CT）scan revealed a rectal mass involving all of the luminal circumference, after which a diagnosis of NEC was confirmed by pathological examination. A CT scan also revealed several liver metastases in S5, S6, and S8. Abdominoperineal resection with total mesenteric excision and lymphadenectomy, including the lateral area, was performed. After resection, we administered radiation for local disease control in the lateral area. We also administered chemotherapy consisting of cisplatin and irinotecan for the liver metastases because only the endocrine cell component constituted this tumor. After chemotherapy, a CT scan was performed to confirm that the liver metastasis in S5 and S6 had disappeared, and it was shown that the other lesion in S8 had shrunk substantially（it eventually disappeared）. Then, 48 months after resection, all metastatic liver tumors were under good control, and no other recurrent lesion was recognized. In conclusion, a multidisciplinary strategy including optimal chemotherapy seems to be important to achieve a favorable prognosis of NEC of the colorectum with distant metastasis