A Note on Matter Superenergy Tensors

We consider Bel-Robinson-like higher derivative conserved two-index tensors H_\mn in simple matter models, following a recently suggested Maxwell field version. In flat space, we show that they are essentially equivalent to the true stress-tensors. In curved Ricci-flat backgrounds it is possible to redefine H_\mn so as to overcome non-commutativity of covariant derivatives, and maintain conservation, but they become model- and dimension- dependent, and generally lose their simple "BR" form.Comment: 3 page

Charge density and electric charge in quantum electrodynamics

The convergence of integrals over charge densities is discussed in relation with the problem of electric charge and (non-local) charged states in Quantum Electrodynamics (QED). Delicate, but physically relevant, mathematical points like the domain dependence of local charges as quadratic forms and the time smearing needed for strong convergence of integrals of charge densities are analyzed. The results are applied to QED and the choice of time smearing is shown to be crucial for the removal of vacuum polarization effects responible for the time dependence of the charge (Swieca phenomenon). The possibility of constructing physical charged states in the Feynman-Gupta-Bleuler gauge as limits of local states vectors is discussed, compatibly with the vanishing of the Gauss charge on local states. A modification by a gauge term of the Dirac exponential factor which yields the physical Coulomb fields from the Feynman-Gupta-Bleuler fields is shown to remove the infrared divergence of scalar products of local and physical charged states, allowing for a construction of physical charged fields with well defined correlation functions with local fields

Changes in corneal parameters at confocal microscopy in treated glaucoma patients

The purpose of this study was to evaluate corneal parameters in treated glaucoma patients, nontreated glaucoma patients, and normal subjects using confocal microscop

Hidden symmetries in two dimensional field theory

The bosonization process elegantly shows the equivalence of massless scalar and fermion fields in two space-time dimensions. However, with multiple fermions the technique often obscures global symmetries. Witten's non-Abelian bosonization makes these symmetries explicit, but at the expense of a somewhat complicated bosonic action. Frenkel and Kac have presented an intricate mathematical formalism relating the various approaches. Here I reduce these arguments to the simplest case of a single massless scalar field. In particular, using only elementary quantum field theory concepts, I expose a hidden $SU(2)\times SU(2)$ chiral symmetry in this trivial theory. I then discuss in what sense this field should be interpreted as a Goldstone boson.Comment: 15 pages. Revision adds numerous references and puts things in better historical contex

Learning effect of humphrey matrix frequency doubling technology perimetry in patients with ocular hypertension

Aim: To evaluate the learning effect of Frequency Doubling Technology (FDT) perimetry using the Humphrey Matrix-FDT perimetry (Matrix) 24-2 full-threshold program on patients with 7 ocular hypertension experienced with standard automated perimetry. Methods: Twenty-four patients with Ocular hypertension underwent 5 full-threshold Matrix tests at intervals of 5 2 days. Learning effect was defined as an improvement at results for duration, perimetric indices, foveal sensitivity, Glaucoma Hemifield Test, and the number of points with a P < 5% and < 1% in the total and pattern deviation maps. Eccentricity, hemifield, and quadrant sensitivities were also addressed as Sources of differences in learning effect. Test-retest variability was also calculated for each repetition as the mean of the point-to-point interindividual standard deviations. Results: A learning effect was demonstrated for mean defect (P = 0.031, analysis of variance) and foveal sensitivity (P = 0.009) and it only affected the first test for both parameters. All the other parameters did not show any significant learning effect. The effect was independent From eccentricity and quadrant or hemifield sensitivities. Conclusions: The results of this study demonstrate that the learning effect for Matrix-FDT is mild and it may affect only the first test. Caution is needed in the analysis of the first Matrix-FDT examination and retest may be advisable in the presence of low mean defect

Circadian variations in central corneal thickness and intraocular pressure in patients with glaucoma

AIM: To analyse 24 hour variations in intraocular pressure (IOP) and central corneal thickness (CCT) in a group of glaucomatous patients. METHODS: 30 patients with primary open angle glaucoma were hospitalised and underwent circadian evaluations (at 8 pm, midnight, 4 am, 8 am, noon, and 4 pm) of supine and sitting IOP, respectively, measured using a Perkins and a Goldmann tonometer, and CCT measured using an ultrasonic pachymeter (the mean value of three measurements within 5 mum). All patients were treated with timolol 0.5% twice daily and latanoprost 0.005% once daily. RESULTS: Mean supine IOP was 15.3 (SD 3.7) mm Hg (range 10-25), with circadian fluctuations of 7.3 (3.3) mm Hg. Mean sitting IOP was 15.1 (3.9) mm Hg (range 8-26), with circadian fluctuations of 5.4 (3.1) mm Hg. Mean CCT was 534 (39) microm (range 443-637 microm) with circadian fluctuations of 16.5 (6.2) microm (range 6-31 microm). Both the within patient and within time point fluctuations in CCT were statistically significant (p<0.0001, ANOVA). CONCLUSIONS: The authors found considerable fluctuations in 24 hour IOP. The circadian fluctuations in CCT were small and, although statistically significant, did not seem to interfere with the circadian IOP assessment