2,845 research outputs found
A Kobayashi metric version of Bun Wong's theorem
No full textWe study the classical theorem of Bun Wong and Rosay about domains with non-compact automorphism group and strongly pseudoconvex orbit accumulation point. We formulate and prove a version of the result in the language of the Kobayashi metricX1188sciescopu
Characterization of the Hilbert ball by its automorphisms
No full textWe show in this paper that every domain in a separable Hilbert space, say R, which has a C-2 smooth strongly pseudoconvex boundary point at which an automorphism orbit accumulates is biholomorphic to the unit ball of R. This is the complete generalization of the Wong-Rosay theorem to a separable Hilbert space of infinite dimension. Our work here is an improvement from the preceding work of Kim/Krantz [16] and subsequent improvement of Byun/Gaussier/Kim [3] in the infinite dimensions.X117sciescopuskc
Characterization of the Hilbert ball by its automorphism group
No full textLet Omega be a bounded, convex domain in a separable Hilbert space. The authors prove a version of the theorem of Bun Wong, which asserts that if such a domain admits an automorphism orbit accumulating at a strongly pseudoconvex boundary point, then it is biholomorphic to the ball. Key ingredients in the proof are a new localization argument using holomorphic peaking functions and the use of new "normal families" arguments in the construction of the limit biholomorphism.open1110sciescopu
Some new results on domains in complex space with non-compact automorphism group
No full textWe provide a new proof of the Wong-Rosay theorem, using the structure of the ring of holomorphic functions. As a byproduct, we provide an analogous theorem for classical bounded symmetric domains. The second main result of this article concerns a new existence theorem for holomorphic peaking functions at a hyperbolic orbit accumulation boundary point. Finally, we give a proof of a version of the Greene-Krantz conjecture using holomorphic vector fields and a strengthened Hopf lemma. (C) 2003 Published by Elsevier Science (USA).X117sciescopu
Correction of scaling mismatches in oligonucleotide microarray data
No full textBackground: Gene expression microarray data is notoriously subject to high signal variability. Moreover, unavoidable variation in the concentration of transcripts applied to microarrays may result in poor scaling of the summarized data which can hamper analytical interpretations. This is especially relevant in a systems biology context, where systematic biases in the signals of particular genes can have severe effects on subsequent analyses. Conventionally it would be necessary to replace the mismatched arrays, but individual time points cannot be rerun and inserted because of experimental variability. It would therefore be necessary to repeat the whole time series experiment, which is both impractical and expensive. Results: We explain how scaling mismatches occur in data summarized by the popular MAS5 (GCOS; Affymetrix) algorithm, and propose a simple recursive algorithm to correct them. Its principle is to identify a set of constant genes and to use this set to rescale the microarray signals. We study the properties of the algorithm using artificially generated data and apply it to experimental data. We show that the set of constant genes it generates can be used to rescale data from other experiments, provided that the underlying system is similar to the original. We also demonstrate, using a simple example, that the method can successfully correct existing imbalancesin the data. Conclusion: The set of constant genes obtained for a given experiment can be applied to other experiments, provided the systems studied are sufficiently similar. This type of rescaling is especially relevant in systems biology applications using microarray data. © 2006 Barenco et al; licensee BioMed Central Ltd
[[alternative]]The KT transition of YBCO films
No full text[[abstract]]我們想藉由觀察 YBaCuO 薄膜是否有 KT 變遷的現象,來瞭解薄膜厚度與
維度的關係。故我們製作二塊不同厚度 (240o,120o) 的薄膜,分別量測它
們的電阻率與 V-I 曲線, 並加以分析。其中240o 之 YBCO 薄膜由於厚度
較大,無法表現二維的行為。而120o 的薄膜其 V-I 曲線相關的次方定律
V=I,在 T<76.6K 時, n 滿足二維 Ginzberg- Landau 之線性關係式: n(
T)≒1+const(1-T/Tco)。以此直線與 n=1 之交點定出樣品的 T=79K。而
在n(T)約為5.1時, n 不再隨上述的線性關係式隨溫度下降,亦即發生了
KT 變遷中普遍躍遷的現象。我們分別以 n=3及 n=5.1 定出兩種不同的
Tkt, 來討論電阻率的結果。由電阻率的結果分析,無論那種決定 Tkt 的
方法在介於78.1及78.6K 間,其ln(R/Rn)與[(Tco-T)/(T-Tkt)]成線性關係
。亦就是出現 KT 理論中預測因二維渦流運動產生的特殊行為。所以其具
有二維的傳導現象。
In order to know the dimensionalities of YBCO films, we
measured the resistivities and I-V curves of two YBCO films(120
o,240o). According to our results,the film of 240o thickness
couldn't show the 2d behaviors.The power law of 120o film has
the universal jump phenomena and the resisti- vity behavior can
be explained by 2d free vortices mo- tion.We can say that the
YBCO film of 120o thickness is a 2d system.
In order to know the dimensionalities of YBCO films, we
Numerical analysis and discussion on the hot-spot stress concept applied to welded tubular KT joints
No full textNominal stresses have been used for a long time for the assessment of fatigue resistance of welded joints, however, this approach has strong limitations since the definition of the nominal stress may be subjective for complex welded details and/or complex loading. On the other hand, the hot-spot stress approach has been proposed to overcome these limitations considering the structural geometrical discontinuities. However, the hot-spot stress methods also present certain limitations, and the present study aims at evaluating the available numerical and analytical hot-spot stress methods proposed by DNVGL (2016) and IIW (2014). The particular case of an offshore tubular KT joint has been considered herein and discretized in two planes. It has been studied numerically using the ABAQUS software coupled with the hot-spot stress extrapolation methods described in IIW (2014) and DNVGL (2016). The influence of the weld geometry has been considered and evaluated. In addition to the numerical method, the present study has also considered the analytical approach proposed in DNVGL (2016) derived from the combination of Efthymiou solutions for the stress concentration factor with the method of superposition of stresses. The numerical models according to IIW (2014) have been found to be more conservative when compared with the mesh-size methods proposed by DNVGL (2016), both in numerical modelling without the weld or with weld. For the numerical models with weld cord, the mean values of normalized difference index obtained for all braces together, as a result of comparing numerical results with analytical solutions, are lower, when compared with results obtained from the numerical models without weld cord.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Steel & Composite Structure
Kt/V in CAPD by different estimations of V
No full textKt/V in CAPD by different estimations of V. This study compared the measurements of total body water (TBW) by 58% body weight (TBW58%), the Watson equation (TBWWV) and bioelectric impedance (TBWBIA) with the gold standard, Deuterium oxide (TBWD2O) dilution method in twenty continuous ambulatory peritoneal dialysis (CAPD) patients. TBW volumes were highest when calculated as TBW58% (42.6 ± 9.4 liter) and lowest when calculated from TBWWV (34.6 ± 6.8 liter). TBWBIA underestimated TBW when compared to TBWD2O, although the difference was not statistically significant (37.1 ± 9.8 liter and 38.8 ± 9.3 liter, respectively). In fact, TBWBIA correlated strongly with TBWD2O (r = 0.8, P < 0.0001). These discrepancies resulted in significant differences when Kt/V week-1 derived from the four methods were compared. To determine the effect of percent fat mass on the estimation of TBW by each method, we compared TBW and Kt/V week-1 derived from the four methods in nine CAPD patients who had normal percent fat mass (Non-Obese) and 11 CAPD patients who had greater than normal % fat mass (Obese). In the Non-Obese group, there was close correlation of TBWBIA, TBWWV and TBW58% when compared with TBWD2O (r = 0.93, P < 0.001, r = 0.89, P < 0.01 and R = 0.86, P < 0.01, respectively). Also, Kt/V week-1 derived from TBWBIA, TBWWV and TBW58% correlated strongly with Kt/V week-1 from TBWD2O (r = 0.93, P < 0.0005, r = 0.83, P < 0.01 and r = 0.8, P < 0.01, respectively). In the Obese patients, the correlations between TBWD2O and TBWBIA and TBWWV were only moderate in strength (r = 0.67, P = 0.02 and r = 0.61, P = 0.04, respectively). There was no significant correlation between TBW58% and TBWD2O in the Obese group (r = 0.44, P = NS). Kt/V week-1 derived from TBWBIA; TBWWV and TBW58% had only moderate correlation with Kt/V week-1 from D2O. Similar findings in TBW measurements and Kt/V week-1 were obtained in CAPD patients (N = 9) who had normal BMI (< 26 kg/m2; termed, Normal Weight) and those who had BMI > 26 kg/m2 (N = 11; termed, Overweight; data not shown). Our results suggest that the discrepancies in TBW and Kt/V in CAPD patients with different body habitus were a result of relative body fat mass. Thus, in CAPD patients who were not obese, all four methods gave good correlations of TBW and Kt/V. Even though TBWBIA had the smallest bias and the best correlation with TBWD2O, the wide limits of agreement between BIA and D2O dilution suggest that BIA is inappropriate at the present time for assessing TBW in CAPD patients, especially in the obese. In the case of discrepancy in Kt/V and clinical outcome, adequacy of dialysis in CAPD patients should be assessed by accurate measurement of V using the D2O dilution method
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