1,620 research outputs found
Strong Stein neighborhood bases
Let D be a smooth bounded pseudoconvex domain in C^n. We give several
characterizations for the closure of D to have a strong Stein neighborhood
basis in the sense that D has a defining function r such that {z\in C^n:r(z)<a}
is pseudoconvex for sufficiently small a>0. We also show that this condition is
invariant under proper holomorphic maps that extend smoothly to the boundary.Comment: 14 pages, fixed same references, to appear in Complex Var. Elliptic
Eq
Pointwise estimates for the Bergman kernel of the weighted Fock space
We prove upper pointwise estimates for the Bergman kernel of the weighted
Fock space of entire functions in where is a
subharmonic function with a doubling measure. We derive estimates
for the canonical solution operator to the inhomogeneous Cauchy-Riemann
equation and we characterize the compactness of this operator in terms of
Fine structure and functional morphology of the mouthparts of a male Veigaia sp (Gamasida: Veigaiidae) with remarks on the spermatodactyl and related sensory structures
Mites of the genus Veigaia are common gamasid
inhabitants of forest litter. They engage in the
peculiar reproductive strategy of podospermy which, along
with other morphological and behavioral adaptations, involves
modification of the chelicerae of the relatively rare
males into gonopods. Each movable digit is provided with
an appendage (spermatodactyl) that is involved in sperm
transfer. We describe the gross anatomy, fine structure,
and functional morphology of the mouthparts of a male
Veigaia species and give ultrastructural details for the
corniculi, laciniae, preoral cavity, labrum, pharynx, and
movable and fixed digits. The fine structure of the spermatodactyl
is illustrated here for the first time in detail. A
semischematic reconstruction of the gnathosoma and
spermatodactyl is provided. The spermatodactyl is totally
fused with the movable digit and a sperm transfer duct
runs along its entire length. This duct starts at the adaxial
base of the movable digit, continues inside the digit into
the tube of the spermatodactyl, and finally opens at the
distal abaxial surface of the spermatodactyl. Several sensory
structures associated with the spermatodactyl probably
provide the male with mechanical and chemical
clues
Geometric phase around exceptional points
A wave function picks up, in addition to the dynamic phase, the geometric
(Berry) phase when traversing adiabatically a closed cycle in parameter space.
We develop a general multidimensional theory of the geometric phase for
(double) cycles around exceptional degeneracies in non-Hermitian Hamiltonians.
We show that the geometric phase is exactly for symmetric complex
Hamiltonians of arbitrary dimension and for nonsymmetric non-Hermitian
Hamiltonians of dimension 2. For nonsymmetric non-Hermitian Hamiltonians of
higher dimension, the geometric phase tends to for small cycles and
changes as the cycle size and shape are varied. We find explicitly the leading
asymptotic term of this dependence, and describe it in terms of interaction of
different energy levels.Comment: 4 pages, 1 figure, with revisions in the introduction and conclusio
Shelf arthroplasties long-term outcome: Influence of labral tears. A prospective study at a minimal 16 years’ follows up
SummaryIntroductionOsteoarthritis lesions extent and dysplasia severity (negative vertical center edge [CE] angle) are recognized as unfavorable criteria for the survival of shelf arthroplasties performed for correcting hip dysplasia. Labral tears have recently been described on dysplastic hips, indicating beginning osteoarthritis and worsening the risk of instability.HypothesisThe labral tears identified in the course of shelf arthroplasty procedures for correction of hip dysplasia carry a predictive value for the survival of this operation.ObjectivesEvaluate this hypothesis at the intermediate term in a long-term prospective observational study.Patient and methodsEighteen adult patients (18 dysplastic hips) having undergone shelf arthroplasty were included consecutively in a continuous prospective study. At the time the shelf arthroplasty was performed, a hip arthroscopic exam was carried out to search for and resect a labral tear if necessary. Fifteen patients were reviewed with a minimum follow-up of 16 years. Two patients died and one patient was lost to follow-up.ResultsDuring arthroscopic exploration, 10 hips presented labral tears (55.6%). At a mean follow-up of 16.3 years (range, 16–18 years), eight hips underwent hip arthroplasty. Of these hips, only one did not present a labral tear. The seven other hips had a tear of the labrum (p<0.001). The overall survival rate was 41.3%; it was 83.3% for hips with no labral tear and 15.2% for hips with a lesion of the labrum (p=0.048).Discussion and conclusionLabral tears had a negative impact on the outcome of shelf arthroplasty for hip dysplasia. This lesion therefore warrants being sought using appropriate exploration techniques (MRI or CT-arthrography) before shelf arthroplasty surgery. The existence of a preoperative labral tear does not seem to cast doubt on shelf arthroplasty itself. However, it should be identified so as to set objectives and expectations: long-term survival is significantly lower in the presence of a labral tear. It seems preferable to repair this type of lesion with arthroscopic guidance during shelf arthroplasty to prevent a potential source of residual pain, keeping in mind that secondary resection will be more difficult after covering the lesion.Level of evidenceLevel 3 prospective observational prognostic study
Electronic Raman scattering in YBCO and other superconducting cuprates
Superconductivity induced structures in the electronic Raman spectra of
high-Tc superconductors are computed using the results of ab initio LDA-LMTO
three-dimensional band structure calculations via numerical integrations of the
mass fluctuations, either in the whole 3D Brillouin zone or limiting the
integrations to the Fermi surface. The results of both calculations are rather
similar, the Brillouin zone integration yielding additional weak structures
related to the extended van Hove singularities. Similar calculations have been
performed for the normal state of these high-Tc cuprates. Polarization
configurations have been investigated and the results have been compared to
experimental spectra. The assumption of a simple d_(x^2-y^2)-like gap function
allows us to explain a number of experimental features but is hard to reconcile
with the relative positions of the A1g and B1g peaks.Comment: 14 pages, LaTeX (RevTeX), 5 PostScript figures, uses multicol.sty,
submitted to PR
Electronic Raman-scattering study of low-energy excitations in single and double CuO_2-layer Tl-Ba-(Ca)-Cu-O superconductors
Low energy Raman continuum and the redistribution of the continuum to a peak
(2\Delta-peak) in the superconducting state have been studied in
Tl-Ba-(Ca)-Cu-O superconductors with single (Tl-2201) and double (Tl-2212)
CuO_2 layer. The 2\Delta/k_BT_c ratios in A_1g and B_1g symmetries are larger
for Tl-2212 than for Tl-2201. The B_1g/A_1g gap ratio is also larger in
Tl-2212. The A_1g intensities of the continuum and the 2\Delta-peak are
significantly weaker than the B_1g intensities in Tl-2201, but are comparable
in Tl-2212. This shows that the Coulomb screening is much stronger in Tl-2201.
The change from Tl-2201 to Tl-2212 of the normalized A_1g 2\Delta-peak
intensity is identical within experimental error to that of normalized A_1g
continuum intensity. This suggests that the excitations forming the
2\Delta-peak and the continuum couple to light by the same mechanism.Comment: 4 pages, PDF forma
Raman study of carrier-overdoping effects on the gap in high-Tc superconducting cuprates
Raman scattering in the heavily overdoped (Y,Ca)Ba_2Cu_3O_{7-d} (T_c = 65 K)
and Bi_2Sr_2CaCu_2O_{8+d} (T_c = 55 K) crystals has been investigated. For the
both crystals, the electronic pair-breaking peaks in the A_{1g} and B_{1g}
polarizations were largely shifted to the low energies close to a half of
2Delta_0, Delta_0 being the maximum gap. It strongly suggests s-wave mixing
into the d-wave superconducting order parameter and the consequent
manifestation of the Coulomb screening effect in the B_{1g}-channel. Gradual
mixing of s-wave component with overdoping is not due to the change of crystal
structure symmetry but a generic feature in all high-T_c superconducting
cuprates.Comment: 5 pages, 4 figures, to be published in Phys. Rev. B, Rapid
communicaito
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