Where does selective laser trabeculoplasty stand now? A review

Background: Chronic treatment of glaucoma can present a challenge in patients who lack the means and/or the discipline to use daily glaucoma medication. We wondered if selective laser trabeculoplasty (SLT) could be a useful alternative. Methods: Inclusion criteria: controlled trials comparing efficacy of SLT in adult patients with any form of open angle glaucoma or ocular hypertension and case reports on side effects of SLT. Two recent meta-analyses identified eight randomized clinical trials (RCTs) comparing the effect of SLT with medication (prostaglandin analogs) and with argon laser trabeculoplasty (ALT). We took these eight RCTs as reference base and calculated their success rates where they were not given. Other articles were added to elaborate on technique and side effects. Results: Mean intraocular pressure (IOP) reduction after SLT was 3.8-8.0 mmHg after 6 months to 1 year. Mean success rate of SLT at 6 months to 1 year is 55-82 %. Higher IOP before laser predicts a higher IOP-lowering effect. In terms of mean IOP reduction, reduction in number of medications and treatment success, the effect of SLT was found to show no clinically relevant difference from that of contemporary medication (prostaglandin analogs) and from ALT. Conclusions: The evidence indicates that SLT is an efficacious primary or adjunctive therapy for treating glaucoma

Field Theory reformulated without self-energy parts.Divergence-free classical electrodynamics

A manifestly gauge-invariant hamiltonian formulation of classical electrodynamics has been shown to be relativistic invariant by the construction of the adequate generators of the Poincare Lie algebra [Physica, 76, No. 3, 421-444 (1974)]. The original formulation in terms of reduced distribution functions for the particles and the fields is applied here to the case of two charges interacting through a classical electrodynamical field. On the other hand, we have been able in previous work to introduce irreversibility at the fundamental level of description [Ann. Phys., 311, 314-349 (2004)] by reformulating field theory without self-energy parts by integrating all processes associated with self-energy in a kinetic operator, while keeping the equivalence with the original description [Prog. Theor. Phys.,109, 881-909 (2003)]. In this paper, the two approaches are combined to provide a formalism that enables the use of methods of statistical physics to tackle the problem of the divergence of the self-mass. Our approach leads to expressions that are finite even for point-like charged particles: the limit of a infinite cutoff can be taken in an harmless way on self consistent equations. In order to check our theory, we recover the power dissipated by radiation in geometries where the usual mass divergence does not play a roleComment: 82 pages, submitted Annals of Physics, Interpretation revised completel

Field Theory reformulated without Self-energy Parts. The dressing Operator

The reformulation of field theory for avoiding self-energy parts in the dynamical evolution has been applied successfully in the framework of the Lee model, [M. de Haan. Ann. Phys., 311, 314-349 (2004)] enabling a kinetic extension of the description. The basic ingredient is the recognition of these self-energy parts. [M. de Haan and C. George. Trends in Statistical Physics 3 (2000), 115] The original reversible description is embedded in the new one and appears now as a restricted class of initial conditions. [M. de Haan and C. George. Prog. Theor. Phys.,109, 881-909 (2003)] This program is realized here in the reduced formalism for a scalar field, interacting with a two-level atom, beyond the usual rotating wave approximation. The kinetic evolution operator, previously surmised, [M. de Haan. Physica, A171 (1991), 159] is here derived from first principles, justifying the usual practice in optics where the common use of the so-called pole approximation should no longer be viewed as an approximation but as an alternative description in the appropriate formalism. That model illustrates how some dressing of the atomic levels (and vertices), through an appropriate operator, finds its place naturally into the new formalism since the bare and dressed ground states do no longer coincide. Moreover, finite velocity for field propagation is now possible in all cases, without the presence of precursors for multiple detections.Comment: 55 pages. Revised version for Annals of Physics. Typos and English corrections, references and precisions adde

Phase diagram and dependence of the critical temperature T_c on the pressure for Tl_{0.5}Pb_{0.5}Sr_2Ca_{1-x}Y_xCu_2)_7

Using a mean-field BCS-like approach on the bidimensional extended Hubbard Hamiltonian we calculate the superconducting transition temperature Tc as a function of the hole content nh, for the d-wave and extended-s wave gap symmetries. To describe the pressure effect on Tc we assume it induces a change in the magnitude V of the attractive superconductor potential. This assumption yields an explanation for the intrinsic term, and together with the well known change in nh, we set the critical temperature as Tc=Tc(nh(P),V(P)). With this we obtain a general expansion of Tc in terms of the pressure P and the hole content nh. We apply this expansion to the Tl_{0.5}Pb_{0.5}Sr_2Ca_{1-x}Y_xCu_2)_7 system

Heisenberg model in a random field: phase diagram and tricritical behavior

By using the differential operator technique and the effective field theory scheme we study the tricritical behavior of Heisenberg classical model of spin-1/2 in a random field. The phase diagram in the T-h plane on a square and simple cubic lattice for a cluster with two spins is obtained when the random field is bimodal distributed.Comment: 10 pages, 1 figur

Code of good research practices

Podeu consultar la versió en català a: http://hdl.handle.net/2445/28542 i en castellà a: http://hdl.handle.net/2445/28543As stated in its Statutes, one of the University of Barcelona's (UB) priority objectives is to carry out the highest level of research. This quality research should contribute to the following: progress in all knowledge areas, qualityof-life improvements, environmental preservation and improvement, the promotion of peace, the elimination of social and economic inequalities between individuals and peoples, and scientific and artistic progress in general. The equal opportunities of women and men are respected in all of these areas. The University does not participate in research projects that are incompatible with this objective. In particular, it does not take part in projects that could contribute to the arms race. The UB ensures that all of its research is of a high quality. To achieve this, it evaluates studies undertaken by individuals, research groups and any other forms of research collaboration (Article 100.6, University of Barcelona Statutes). The entities in the UB Group are responsible for ensuring that all of their research is undertaken in accordance with the current legislation and using good scientific practices

Review and classification of fretting fatigue test rigs

There is no standard or generally accepted test rig for fretting fatigue experiments. Therefore, researchers adopt an existing concept, or build a new test rig that meets their specific requirements. However, too many different test rigs may be disadvantageous because the results of two different test rigs are hard to compare. The increasing amount of diversity is mainly caused by the lack of a recent literature survey on fretting fatigue test rigs. In 1994, Hills and Nowell described a few test rigs in Mechanics Of Fretting Fatigue. In this study, the authors made a classification of test rigs based on the contact geometry, which is determined by the test specimens, not by the test rig itself. The authors of this article present a review of the available literature, and present a classification based on the properties of test rigs. Fretting fatigue test rigs are first divided in two categories based on the geometry of the test specimen: full scale and coupon scale test rigs. The latter are mostly used to perform research and are subdivided in categories based on increasing functionalities. This is the ability to apply a fatigue load, a constant normal force, and an alternating slip in the range of some micrometers. In time, from the fifties until now, progress has been seen in the design of fretting fatigue test rigs. More parameters can be controlled during experiments and more measuring techniques are incorporated. State of the art test rigs are classified in the last category with mostffunctionalities, but still have imperfections. Future designers can use this article to classify their needs, or help to design a better test rig knowing the imperfections of the state of the art test rigs

The higher rank qq-deformed Bannai-Ito and Askey-Wilson algebra

The $q$-deformed Bannai-Ito algebra was recently constructed in the threefold tensor product of the quantum superalgebra $\mathfrak{osp}_q(1\vert 2)$. It turned out to be isomorphic to the Askey-Wilson algebra. In the present paper these results will be extended to higher rank. The rank $n-2$ $q$-Bannai-Ito algebra $\mathcal{A}_n^q$, which by the established isomorphism also yields a higher rank version of the Askey-Wilson algebra, is constructed in the $n$-fold tensor product of $\mathfrak{osp}_q(1\vert 2)$. An explicit realization in terms of $q$-shift operators and reflections is proposed, which will be called the $\mathbb{Z}_2^n$ $q$-Dirac-Dunkl model. The algebra $\mathcal{A}_n^q$ is shown to arise as the symmetry algebra of the constructed $\mathbb{Z}_2^n$ $q$-Dirac-Dunkl operator and to act irreducibly on modules of its polynomial null-solutions. An explicit basis for these modules is obtained using a $q$-deformed $\mathbf{CK}$-extension and Fischer decomposition.Comment: 38 pages, minor changes and references adde