3,230,114 research outputs found
Geometry of the symmetrized polydisc
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
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.
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
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
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
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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