Compatible pairs of orthogonal polynomials

19 pages, no figures.-- MSC1991 code: 33C45.MR#: MR1736624 (2001a:33009)Zbl#: Zbl 0944.33012We find necessary and sufficient conditions for an orthogonal polynomial system to be compatible with another orthogonal polynomial system. As applications, we find new characterizations of semi-classical and classical orthogonal polynomials.The work of D. H. Kim and K. H. Kwon was partially supported by KOSEF (98-0701-03-01-5) and GARC at Seoul National University. The work of F. Marcellán was partially supported by Dirección General de Enseñanza Superior (DGES) of Spain under grant PB96-0120-C03-0l.Publicad

On kernel polynomials and self perturbation of orthogonal polynomials

20 pages, no figures.-- MSC2000 code: 42C05.MR#: MR1847402 (2002h:42049)Zbl#: Zbl 1034.42022Given an orthogonal polynomial system $(Q_n(x))_{n=0} infty$, define another polynomial system by where αn are complex numbers and t is a positive integer. We find conditions for $(P_n(x))_{n=0} infty$ to be an orthogonal polynomial system. When t=1 and α1≠0, it turns out that $(Q_n(x))_{n=0} infty$ must be kernel polynomials for $(P_n(x))_{n=0} infty$ for which we study, in detail, the location of zeros and semi-classical character.The first author (KHK) was partially supported by the BK-21 project and KOSEF(98-0701-03-01-5). The second author (DWL) was partially supported by BK-21 project. The third author (FM) was partially supported by Dirección General de Enseñanza Superior (DGES) of Spain under grant PB96-0120-C03-01. The fourth author (SBP) was partially supported by the Hwarangdae Research Institute.Publicad

Prediction on lengths of stay in the postanesthesia care unit following general anesthesia: preliminary study of the neural network and logistic regression modelling.

The length of stay in the postanesthesia care unit (PACU) following general anesthesia in adults is an important issue. A model, which can predict the results of PACU stays, could improve the utilization of PACU and operating room resources through a more efficient arrangement. The purpose of study was to compare the performance of neural network to logistic regression analysis using clinical sets of data from adult patients undergoing general anesthesia. An artificial neural network was trained with 409 clinical sets using backward error propagation and validated through independent testing of 183 records. Twenty-two inputs were used to find determinants and to predict categorical values. Logistic regression analysis was performed to provide a comparison. The neural network correctly predicted in 81.4% of situations and identified discriminating variables (intubated state, sex, neuromuscular blocker and intraoperative use of opioid), whereas the figure was 65.0% in logistic regression analysis. We concluded that the neural network could provide a useful predictive model for the optimization of limited resources. The neural network is a new alternative classifying method for developing a predictive paradigm, and it has a higher classifying performance compared to the logistic regression model

A Note on Tachyons in the D3+D3ˉD3+{\bar {D3}} System

The periodic bounce of Born-Infeld theory of $D3$-branes is derived, and the BPS limit of infinite period is discussed as an example of tachyon condensation. The explicit bounce solution to the Born--Infeld action is interpreted as an unstable fundamental string stretched between the brane and its antibrane.Comment: 10 pages, 2 figures. v2: minor changes, acknowledgement added; v3: explanations and references added. Final version to appear in Mod. Phys. Lett.

Effects of general and locoregional anesthesia on reproductive outcome for in vitro fertilization: a meta-analysis.

The objective of this meta-analysis was to evaluate prospective trials of general or locoregional anesthesia on reproductive outcomes (cleavage and pregnancy rate) for in vitro fertilization (IVF). Of 115 published studies retrieved from a search of articles indexed on MEDLINE from 1966 to February 1999, four studies with distinct general and locoregional anesthesia were deemed eligible for meta- analysis. The pooled relative risk and odds ratios were calculated. A test for homogeneity was also performed. The pooled log odds ratio was 1.03 (95% CI 0.90-1.18) in cleavage rate and 0.71 (95% CI 0.47-1.08) in pregnancy rate. Heterogeneity was negative. Cleavage and pregnancy rates were not significantly different in both the general anesthesia and locoregional anesthesia groups. Both anesthetic techniques were favorable to IVF procedure by available published evidence when anesthesia was needed

Development and Validation of the Whole Atmosphere Community Climate Model With Thermosphere and Ionosphere Extension (WACCM‐X 2.0)

Key developments have been made to the NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM‐X). Among them, the most important are the self‐consistent solution of global electrodynamics, and transport of O+ in the F‐region. Other ionosphere developments include time‐dependent solution of electron/ion temperatures, metastable O+ chemistry, and high‐cadence solar EUV capability. Additional developments of the thermospheric components are improvements to the momentum and energy equation solvers to account for variable mean molecular mass and specific heat, a new divergence damping scheme, and cooling by O(3P) fine structure. Simulations using this new version of WACCM‐X (2.0) have been carried out for solar maximum and minimum conditions. Thermospheric composition, density, and temperatures are in general agreement with measurements and empirical models, including the equatorial mass density anomaly and the midnight density maximum. The amplitudes and seasonal variations of atmospheric tides in the mesosphere and lower thermosphere are in good agreement with observations. Although global mean thermospheric densities are comparable with observations of the annual variation, they lack a clear semiannual variation. In the ionosphere, the low‐latitude E × B drifts agree well with observations in their magnitudes, local time dependence, seasonal, and solar activity variations. The prereversal enhancement in the equatorial region, which is associated with ionospheric irregularities, displays patterns of longitudinal and seasonal variation that are similar to observations. Ionospheric density from the model simulations reproduces the equatorial ionosphere anomaly structures and is in general agreement with observations. The model simulations also capture important ionospheric features during storms

Screen for IDH1, IDH2, IDH3, D2HGDH and L2HGDH Mutations in Glioblastoma

Isocitrate dehydrogenases (IDHs) catalyse oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG). IDH1 functions in the cytosol and peroxisomes, whereas IDH2 and IDH3 are both localized in the mitochondria. Heterozygous somatic mutations in IDH1 occur at codon 132 in 70% of grade II–III gliomas and secondary glioblastomas (GBMs), and in 5% of primary GBMs. Mutations in IDH2 at codon 172 are present in grade II–III gliomas at a low frequency. IDH1 and IDH2 mutations cause both loss of normal enzyme function and gain-of-function, causing reduction of α-KG to D-2-hydroxyglutarate (D-2HG) which accumulates. Excess hydroxyglutarate (2HG) can also be caused by germline mutations in D- and L-2-hydroxyglutarate dehydrogenases (D2HGDH and L2HGDH). If loss of IDH function is critical for tumourigenesis, we might expect some tumours to acquire somatic IDH3 mutations. Alternatively, if 2HG accumulation is critical, some tumours might acquire somatic D2HGDH or L2HGDH mutations. We therefore screened 47 glioblastoma samples looking for changes in these genes. Although IDH1 R132H was identified in 12% of samples, no mutations were identified in any of the other genes. This suggests that mutations in IDH3, D2HGDH and L2HGDH do not occur at an appreciable frequency in GBM. One explanation is simply that mono-allelic IDH1 and IDH2 mutations occur more frequently by chance than the bi-allelic mutations expected at IDH3, D2HGDH and L2HGDH. Alternatively, both loss of IDH function and 2HG accumulation might be required for tumourigenesis, and only IDH1 and IDH2 mutations have these dual effects