3,230,114 research outputs found

    Geometry of the symmetrized polydisc

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    We describe all proper holomorphic mappings of the symmetrized polydisc and study its geometric properties. We also apply the obtained results to the study of the spectral unit ball in \MM_n(\CC^n).Comment: 9 page

    Investigation on two polymorphisms effective on HDL-C concentration in patients with coronary artery disease using restriction fragment length polymorphism

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    Background and aim: High density lipoprotein cholesterol (HDL-C) is a known inverse predictor of coronary heart disease (CHD). Cholesteryl ester transfer protein (CETP) and hepatic lipase (HL) are key proteins in HDL-C metabolism so that decreased CETP or HL activity is associated with high HDL-C. -629C/A polymorphism in promoter of CETP gene and-514C/T in promoter of HL gene were previously reported to reduce related protein level in plasma. In this study association of these polymorphisms with CHD related to HDL-C level were investigated. Methods: In this analytical-descriptive study 321 subjects underwent coronary angiography and divided in two groups base on angiogram (non CAD = 135 and CAD = 186). Serum lipids profile was measured by standard procedure and genotype was detected using PCR-RFLP method. Results: Overall the CETP genotype frequencies were in CAD patients: 58.8% (n=110), 28.9% (n=54) and 12.3% (n=23) and in non CAD patients: 45.2% (n=61), 41.5% (n=56) and 13.3% (n=18) for AA, CA and CC respectively. HL genotype frequencies were in CAD patients: 61.6% (n=114), 33.5% (n=62) and 4.9% (n=9) and in non CAD patients: 65.9% (n=89), 27.4% (n=37) and 6.7% (n=9) for CC, CT and TT respectively. In control group HDL-C concentration was higher for AA than CC genotype in -629C/A, and also for TT than CC genotype in -514C/T. Allele A in all subjects and T allele in woman were higher in CAD than non CAD group. A high increase in HDL-C level (10. mg/dl) was observed in individuals with CETP-AA/LIPC-TT and CETP-CA/LIPC-TT relative to CETP-CC/LIPC-CC across all subjects (P< 0.001) but there was no difference in CAD prevalence. Conclusion: Allele A from -629C/A, and T from -514C/T even with the increasing of HDL-C concentration had higher frequency in CAD than non CAD group. Therefore, it seems that HDL-C didn’t protect coronary artery when CETP or HL activity was reduced by these polymorphisms

    Prospective randomized comparison of laparoscopic versus open adrenalectomy for sporadic pheochromocytoma.

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    BACKGROUND: Laparoscopic adrenalectomy for pheochromocytoma remains subject of debate, owing to the systemic consequences of pneumoperitoneum in patients with catecholamine-secreting tumors. METHODS: A prospective randomized study was conducted (2000-2006), evaluating cardiovascular instability during open (n = 9, group A) or laparoscopic (n = 13, group B) adrenalectomy for pheochromocytoma. Haemodynamic parameters were recorded by invasive monitoring. RESULTS: Haemodynamic instability was observed in 3/9 (group A) and 6/13 patients (group B), with a mean of 1.8 and 2.2 hypertensive peaks per patient (p = n.s.). Blood loss (164 +/- 94 cc versus 48 +/- 36 cc, p < 0.05) and operative time (180 +/- 40 versus 158 +/- 45 min, p = n.s.) favored laparoscopic procedures. Postoperative morbidity and mortality were nil. Hospital stay was shorter in group B (p < 0.05). Long-term follow-up was always normal. CONCLUSIONS: Laparoscopic approach for pheochromocytoma can be as safe as open surgery; intraoperative haemodynamic instability, although usually controlled with success, remains a source of concern

    Medium-sized Sin- (n=14-20) clusters: a combined study of photoelectron spectroscopy and DFT calculations

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    Size-selected anionic silicon clusters, Sin- (n=14-20), have been investigated by photoelectron spectroscopy and density functional theory (DFT) calculations. Low-energy structures of the clusters are globally searched for by using a genetic algorithm based on DFT calculations. The electronic density of states and VDEs have been simulated by using ten DFT functionals and compared to the experimental results. We systematically evaluated the DFT functionals for the calculation of the energetics of silicon clusters. CCSD(T) single-point energies based on MP2 optimized geometries for selected isomers of Sin- are also used as benchmark for the energy sequence. The HSE06 functional with aug-cc-pVDZ basis set is found to show the best performance. Our global minimum search corroborates that most of the lowest-energy structures of Sin- (n=14-20) clusters can be derived from assembling tricapped trigonal prisms (TTP) in various ways. For most sizes previous structures are confirmed, whereas for Si20- a new structure has been found.Comment: 9 pages, 4 figures, 3 table

    Relativistic fine structure oscillator strengths for Li-like ions: C IV - Si XII, S XIV, Ar XVI, Ca XVIII, Ti XX, Cr XXII, and Ni XXVI

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    Ab initio calculations including relativistic effects employing the Breit-Pauli R-matrix (BPRM) method are reported for fine structure energy levels and oscillator strengths upto n = 10 and 0.leq. l .leq.9 for 15 Li-like ions: C IV, N V, O VI, F VII, Ne VIII, Na IX, Mg X, Al XI, Si XII, S XIV, Ar XVI, Ca XIII, Ti XX, Cr XXII, and Ni XXVI. About one hundred bound fine structure energy levels of total angular momenta, 1/2 .leq. J .leq. 17/2 of even and odd parities, total orbital angular momentum, 0 .leq L .leq. 9 and spin multiplicity (2S+1) = 2, 4 are considered for each ion. The levels provide almost 900 dipole allowed and intercombination bound-bound transitions. The BPRM method enables consideration of large set of transitions with uniform accuracy compared to the best available theoretical methods. The CC eigenfunction expansion for each ion includes the lowest 17 fine structure energy levels of the core configurations 1s^2, 1s2s, 1s2p, 1s3s, 1s3p, and 1s3d. The calculated energies of the ions agree with the measured values to within 1% for most levels. The transition probabilities show good agreement with the best available calculated values. The results provide the largest sets of energy levels and transition rates for the ions and are expected to be useful in the analysis of X-ray and EUV spectra from astrophysical sources.Comment: 16 pgs., to appear in Astronomy and Astrophysic

    Absense of slow transients, and the effect of imperfect vertical alignment, in turbulent Rayleigh-Benard convection

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    We report experimental results for the influence of a tilt angle beta relative to gravity on turbulent Rayleigh-Benard convection of cylindrical samples. The measurements were made at Rayleigh numbers R up to 10^11 with two samples of height L equal to the diameter D (aspect ratio Gamma = D/L = 1). The fluid was water with a Prandtl number sigma = 4.38. In contrast to the experiences reported by Chilla et. al. (2004) for a similar sample but with Gamma = 0.5 (D = 0.5 and L = 1.0 m), we found no long relaxation times. For R = 9.4 times 10^10 we measured the Nusselt number N as a function of tilt angle beta and obtained a small beta dependence about a factor of 50 smaller than the result found by Chilla et. al. (2004) for their Gamma = 0.5 sample. We measured side-wall temperatures at eight equally spaced azimuthal locations on the horizontal mid-plane of the sample and used their cross-correlation functions to find the turn-over time of the large-scale circulation (LSC). The resulting Reynolds numbers R_e^cc were found to increase with beta. An important conclusion is that the increase of R_e^cc with beta of the LSC does not significantly influence the heat transport. Over the range 10^9 < R < 10^11 the enhancement of R_e^cc at constant beta due to the tilt could be described by a power law of R with an exponent of -1/6, consistent with a simple model that balances the additional buoyancy due to the tilt angle by the shear stress across the boundary layers. Even a small tilt angle dramatically suppressed the azimuthal meandering and the sudden reorientations characteristic of the LSC in a sample with beta = 0. The azimuthal mean of the temperature at the horizontal mid-plane within our resolution was independent of beta.Comment: 32 pages, 17 figures. Under consideration for publication in J. Fluid Mec
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