On the existence of K\"ahler metrics of constant scalar curvature

For certain compact complex Fano manifolds $M$ with reductive Lie algebras of holomorphic vector fields, we determine the analytic subvariety of the second cohomology group of $M$ consisting of K\"ahler classes whose Bando-Calabi-Futaki character vanishes. Then a K\"ahler class contains a K\"ahler metric of constant scalar curvature if and only if the K\"ahler class is contained in the analytic subvariety. On examination of the analytic subvariety, it is shown that $M$ admits infinitely many nonhomothetic K\"ahler classes containing K\"ahler metrics of constant scalar curvature but does not admit any K\"ahler-Einstein metric

定スカラー曲率ケーラー計量を持つ複素多様体のBCF特性数について

東京海洋大学海洋科学部海洋環境学

Discovery of X rays from Class 0 protostar candidates in OMC-3

We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with the Chandra X-ray Observatory (CXO). The northern part of OMC-3 is found to be particularly rich in new X-ray features; four hard X-ray sources are located in and along the filament of cloud cores. Two sources coincide positionally with the sub$mm$-$mm$ dust condensations of MMS 2 and 3 or an outflow radio source VLA 1, which are in a very early phase of star formation. The X-ray spectra of these sources show an absorption column of (1-3) x 10^23 H cm-2. Assuming a moderate temperature plasma, the X-ray luminosity in the 0.5-10 keV band is estimated to be ~10^30 erg s^-1 at a distance of 450 pc. From the large absorption, positional coincidence and moderate luminosity, we infer that the hard X-rays are coming from very young stellar objects embedded in the molecular cloud cores. We found another hard X-ray source near the edge of the dust filament. The extremely high absorption of 3 x 10^23 H cm^-2 indicates that the source must be surrounded by dense gas, suggesting that it is either a YSO in an early accretion phase or a Type II AGN (e.g. a Seyfert 2), although no counterpart is found at any other wavelength. In contrast to the hard X-ray sources, soft X-ray sources are found spread around the dust filaments, most of which are identified with IR sources in the T Tauri phase.Comment: 9 pages, To be appeared in ApJ v554 n2 Jun 20, 2001 issue, related press release is available at http://science.psu.edu/alert/Tsuboi11-2000.htm, Figure 1 and figure 2 with the best resolution is available at ftp.astro.psu.edu/pub/tsuboi/OMC/010205

Gastrectomia parcial e vagotomia troncular anterior: alterações no metabolismo de cálcio. Estudo experimental em ratos

BACKGROUND: The calcium is not absorbed in the lack of hydrochloric acid and the osteomalacia and osteoporosis may occurs; it is well recognized in patients that had gastric resection. AIM: To evaluate the effects of the partial gastrectomy associated to anterior truncal vagotomy in the absorption and metabolism of calcium. METHODS: Eighteen adults male Wistar rats were submitted to partial gastrectomy associated to anterior truncal vagotomy (GXT, eight animals) and the sham operation (10 animals, control group). The diet consumption and the weight gains of the animals were measured three times during the week. The animals received formulated experimental diet orally (AIN-93M) by eight weeks. The serum calcium, urinary and fecal calcium, apparent absorption of the calcium, activity of the enzyme alkaline fosfatase and calcium in the bone were measured after 60 days. RESULTS: The sham operated animals showed higher diet consumption, weight gains, serum and urinary calcium, excretion of calcium in feces, apparent absorption of calcium and activity of the enzyme alkaline fosfatase (P<0,05) as compared to the animals of the gastrectomized group. However, the concentration of the bone calcium was increased in the animals of the gastrectomized group. CONCLUSION: Partial gastrectomy associated to anterior truncal vagotomy showed to be a good experimental model the study calcium metabolism, decreasing the calcium absorption, serum and urinary calcium and activity of the enzyme alkaline fosfatase. However, for alterations at bone level in rats suggests an experimental study in larger period.RACIONAL: O cálcio não é absorvido na ausência de ácido clorídrico e a osteomalácia e osteoporose podem ocorrer; este fato é bem reconhecido em pacientes que se submeteram à gastrectomias. OBJETIVO: Avaliar os efeitos da gastrectomia parcial associada à vagotomia troncular anterior na absorção e metabolismo de cálcio. MÉTODOS: Dezoito ratos Wistar machos e adultos foram submetidos à gastrectomia parcial e vagotomia troncular anterior (oito animais) e à laparotomia simples como grupo controle (10 animais). O consumo de dieta e o peso dos animais foram monitorados três vezes por semana. Os animais receberam dieta oral formulada experimentalmente (AIN-93M), durante 8 semanas. O cálcio sérico, cálcio urinário e fecal, absorção aparente de cálcio, atividade da enzima fosfatase alcalina e cálcio ósseo foram mensurados após 60 dias de observação. RESULTADOS: Os animais controle apresentaram médias estatísticas maiores (P<0.05) para o consumo de dieta, ganho de peso, cálcio sérico, cálcio urinário, excreção de cálcio nas fezes, absorção aparente de cálcio e atividade da enzima fosfatase alcalina comparados aos animais do grupo gastrectomizado. Entretanto, a concentração de cálcio ósseo foi superior no grupo de animais gastrectomizados (P<0,05) quando comparado com o grupo controle. CONCLUSÃO: A gastrectomia parcial associada à vagotomia troncular anterior mostrou ser um bom modelo experimental para estudo com o metabolismo de cálcio, ocasionando diminuição da absorção de cálcio, cálcio sérico, cálcio urinário e fosfatase alcalina. No entanto, para alterações a nível ósseo em ratos, sugere-se um estudo experimental em período maior.105109Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Ingestion Of Polydextrose Increase The Iron Absorption In Rats Submitted To Partial Gastrectomy.

To investigate whether polydextrose stimulates iron absorption in rats submitted to partial gastrectomy and sham operated. The rats were submitted to partial gastrectomy (Billroth II) or laparotomy (sham-operated control), in groups of 20 and 20 each respectively. The animals were fed with a control diet (AIN-93M) without polydextrose or a diet containing polydextrose (50g/Kg of diet) for eight weeks. They were divided into four subgroups: sham-operated and Billroth II gastrectomy and with or without polydextrose. Two animals died during the experiment. All rats submitted to gastrectomy received B-12 vitamin (intramuscular) each two weeks. The hematocrit and hemoglobin concentration were measured at the start and on day 30 and 56 after the beginning of the experimental period. At the end of the study, the blood was collected for determination of serum iron concentration. The diet with polydextrose reduced the excretion of iron. Apparent iron absorption was higher in the polydextrose fed groups than in the control group. The haematocrit and haemoglobin concentration were lower after Billroth II gastrectomy rats fed the control diet as compared to the polydextrose diet groups. Polydextrose increase iron absorption and prevents postgastrectomy anemia.25518-2