2,145 research outputs found
Scheme Independence of the Effective Hamiltonian for and Decays
We present a calculation of the effective weak Hamiltonian which governs and transitions in two different
renormalization schemes (NDR and HV). In the leading logarithmic approximation,
we show that the coefficients of the effective Hamiltonian are scheme
independent only when one takes correctly into account the scheme dependence of
one- and two- loop diagrams. We demonstrate that in NDR there are contributions
which were missed in previous calculations. These contributions are necessary
to obtain scheme independent coefficients in the final results.Comment: 16 pp + 5 figures not included (available by anonymous ftp at
amisan.iss.infn.it (141.108.15.215), directory /ftp/bsgamma), LaTeX, LPTENS
93/28, ROME 93/958, ULB-TH 93/0
Localized magnetoplasmon modes arising from broken translational symmetry in semiconductor superlattices
The electromagnetic propagator associated with the localized collective
magnetoplasmon excitations in a semiconductor superlattice with broken
translational symmetry, is calculated analytically within linear response
theory. We discuss the properties of these collective excitations in both
radiative and non-radiative regimes of the electromagnetic spectra. We find
that low frequency retarded modes arise when the surface density of carriers at
the symmetry breaking layer is lower than the density at the remaining layers.
Otherwise a doublet of localized, high-frequency magnetoplasmon-like modes
occurs.Comment: Revtex file + separate pdf figure
CP violation in the decay mode
Within the framework of Standard Model, the exclusive decay mode is studied. Although the usual short distance contribution is
small compared to the similar mode, the process offers the
possibility of studying the CP violation, a feature absent in the
counterpart.Comment: 11 page latex file including 2 ps figures. Typos corrected, minor
changes. To appear in PR
Anterior Segment Optical Coherence Tomography Imaging of Filtering Blebs after Deep Sclerectomy with Esnoper-Clip Implant: One-year Follow-up
Purpose: To describe the technique of deep sclerectomy with the new Esnoper-ClipÂź implant, the clinical outcome and the anatomic characteristics of filtering blebs, using anterior segment optical coherence tomography (AS-OCT).
Methods: A prospective case-series study was conducted in five eyes (5 patients) with open angle glaucoma. The fornixbased deep sclerectomy with Esnoper-ClipÂź implant was done by the same surgeon. In one case, mitomycin C was used during surgery. All participants underwent a complete ophthalmic examination and AS-OCT (VisanteÂź) preoperatively, then at each follow-up visit, at 1 day, 1 week, 1 month, 6 months and 1 year postoperatively. Scans were obtained through sagittal and transversal plans to the implant.
Results: Intraocular pressure (IOP) was significantly reduced (p < 0.05) from a mean preoperative value of 23.4 ± 8.6 mm Hg (n = 3.8 glaucoma medications) to a postoperative value of 6.0 ± 2.5 (n = 0), 10.6 ± 5.4 (n = 0), 13 ± 1.6 (n = 0.4), 12.4 ± 2.1 (n = 0.2) and 14.4 ± 1.5 (n = 0.2) at 1 day, 1 week, 1 month,
6 months and 1 year respectively. AS-OCT allowed the visualization of the two plates of the implant (scleral and suprasciliary), the trabeculodescemetic membrane and the hyporeflective spaces in the bleb wall thickness and in suprascleral and suprachoroidal localizations. An immediate postoperative hypotony and an anteriorization of the implant associated to trabeculodescemetic membrane rupture, were detected, although without significant clinical repercussions.
Conclusion: Our first five deep sclerectomy with Esnoper-Clip implantation analysis suggest an effective and well-tolerated method to reduce IOP. AS-OCT is a noninvasive imaging technique that allows the anatomic analysis of the drainage mechanisms after glaucoma surgery.info:eu-repo/semantics/publishedVersio
On Electrostatic Positron Acceleration In The Accretion Flow Onto Neutron Stars
As first shown by Shvartsman (1970), a neutron star accreting close to the
Eddington limit must acquire a positive charge in order for electrons and
protons to move at the same speed. The resulting electrostatic field may
contribute to accelerating positrons produced near the star surface in
conjunction with the radiative force. We reconsider the balance between energy
gains and losses, including inverse Compton (IC), bremsstrahlung and
non--radiative scatterings. It is found that, even accounting for IC losses
only, the maximum positron energy never exceeds keV. The
electrostatic field alone may produce energies keV at most. We
also show that Coulomb collisions and annihilation with accreting electrons
severely limit the number of positrons that escape to infinity.Comment: 9 pages plus 3 postscript figures, to be published in Ap
Associated Production of a W Boson and One b Jet
We calculate the production of a W boson and a single b jet to
next-to-leading order in QCD at the Fermilab Tevatron and the CERN Large Hadron
Collider. Both exclusive and inclusive cross sections are presented. We
separately consider the cross section for jets containing a single b quark and
jets containing a b-anti b pair. There are a wide variety of processes that
contribute, and it is necessary to include them all in order to have a complete
description at both colliders.Comment: LaTeX, 16 pages, 22 postscript figures; version published in Phys.
Rev.
Intraocular Pressure in Eyes Receiving Intravitreal Antivascular Endothelial Growth Factor Injections
PURPOSE: The aim of the this study was to determine the effect of intravitreal antivascular endothelial growth factor injections on intraocular pressure (IOP) and identify possible risk factors for the development of increased IOP.
MATERIALS AND METHODS:
This prospective study included a total of 106 eyes receiving intravitreal injection of bevacizumab as treatment for macular edema or active choroidal neovascularization. IOP was measured by Goldmann applanation tonometry immediately before the intravitreal injection and 5 min, 1 h and 15 days after the procedure. The records of the study patients were reviewed for age, gender, history of glaucoma, diabetes mellitus, phakic status, systemic and topical medication and number of previous injections. Subconjunctival reflux was registered. IOP elevation was defined as IOP â„21 mm Hg and/or a change from baseline of â„5 mm Hg recorded at least on two or more measurements on the same visit.
RESULTS:
Mean preoperative IOP was 15.31 ± 3.90 mm Hg and postoperative IOP values were 27.27 ± 11.87 mm Hg (after 5 min), 17.59 ± 6.24 mm Hg (after 1 h) and 16.86 ± 3.62 mm Hg (after 15 days). The IOP variation was statistically significant between pre- and postoperative measurements (p < 0.05). Subconjunctival reflux was recorded in 11.3%, and in this subgroup the IOP at 5 min and at 1 h was lower than preoperative IOP (p < 0.05).
CONCLUSIONS:
More than one third of the eyes achieved IOPs >30 mm Hg 5 min after injection. Subconjunctival reflux contributed to a lower mean postoperative IOP (p < 0.05). Considerations for the management include prophylactic IOP lowering with medical therapy and/or preinjection ocular decompression for patients with a history of glaucoma or ocular hypertension and switching to an as-needed injection protocol in patients suffering a marked IOP rise in previous injections. © 2015 S. Karger AG, Basel
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