Multiple-plane image formation by Walsh zone plates.

A radial Walsh filter is a phase binary diffractive optical element characterized by a set of concentric rings that take the phase values 0 or π, corresponding to the values + 1 or -1 of a given radial Walsh function. Therefore, a Walsh filter can be re-interpreted as an aperiodic multifocal zone plate, capable to produce images of multiple planes simultaneously in a single output plane of an image forming system. In this paper, we experimentally demonstrate for the first time the focusing capabilities of these structures. Additionally, we report the first achievement of images of multiple-plane objects in a single image plane with these aperiodic diffractive lenses.

Bifractal focusing and imaging properties of Thue-Morse Zone Plates.

We present a new family of Zone Plates (ZPs) designed using the Thue-Morse sequence. The focusing and imaging properties of these aperiodic diffractive lenses coined Thue-Morse Zone Plates (TMZPs) are examined. It is demonstrated that TMZPs produce a pair of self-similar and equally intense foci along the optical axis. As a consequence of this property, under broadband illumination, a TMZP produces two foci with an extended depth of focus and a strong reduction of the chromatic aberration compared with conventional periodic ZPs. This distinctive optical characteristic is experimentally confirmed.

Cantor dust zone plates.

In this paper we use the Cantor Dust to design zone plates based on a two-dimensional fractal for the first time. The pupil function that defines the coined Cantor Dust Zone Plates (CDZPs) can be written as a combination of rectangle functions. Thus CDZPs can be considered as photon sieves with rectangular holes. The axial irradiances produced by CDZPs of different fractal orders are obtained analitically and experimentally, analyzing the influence of the fractality. The transverse irradiance patterns generated by this kind of zone plates has been also investigated.

Multifractal zone plates.

We present multifractal zone plates (MFZPs) as what is to our knowledge a new family of diffractive lenses whose structure is based on the combination of fractal zone plates (FZPs) of different orders. The typical result is a composite of two FZPs with the central one having a first-order focal length f surrounded by outer zones with a third-order focal length f. The focusing properties of different members of this family are examined and compared with conventional composite Fresnel zone plates. It is shown that MFZPs improve the axial resolution and also give better performance under polychromatic illumination.

The Valuation of Recreational Use of Wetlands and the Impact of the Economic Crisis.

The economic valuation of environmental resources is of great interest to society in general and to public managers in particular. It can promote more sustainable environmental policies, as it clearly shows the high economic value of natural resources. Thus, these valuation tools can provide useful evidence to support such policies by quantifying the economic value associated with the protection of such resources. However, there is an inherent difficulty in the implementation of methods to assess the economic valuation of environmental resources, mainly as a result of the absence of a market and hence a price that explains its social demand. However, both the travel cost method and the contingent valuation method used in this paper offer an approach to the economic values of the recreational services for wetlands. The aim is to analyze whether these values have been influenced by the economic crisis, so two time periods are compared separated for a decade. Results do not show an unequivocal influence between values in both periods, with different behaviors among natural areas, although with a certain tendency to increase in the decade being analyzed.

Devil's vortex-lenses.

In this paper we present a new kind of vortex lenses in which the radial phase distribution is characterized by the "devil's staircase" function. The focusing properties of these fractal DOEs coined Devil's vortex-lenses are analytically studied and the influence of the topological charge is investigated. It is shown that under monochromatic illumination a vortex devil's lens give rise a focal volume containing a delimited chain of vortices that are axially distributed according to the self-similarity of the lens.

Devil's lenses.

In this paper we present a new kind of kinoform lenses in which the phase distribution is characterized by the "devil's staircase" function. The focusing properties of these fractal DOEs coined devil's lenses (DLs) are analytically studied and compared with conventional Fresnel kinoform lenses. It is shown that under monochromatic illumination a DL give rise a single fractal focus that axially replicates the self-similarity of the lens. Under broadband illumination the superposition of the different monochromatic foci produces an increase in the depth of focus and also a strong reduction in the chromaticity variation along the optical axis.

Abciximab offers greater benefits to insulin-dependent diabetic patients undergoing coronary stent implantation.

INTRODUCTION AND OBJECTIVES: Abciximab use does not exceed 25% in most of the studies on diabetic patients undergoing stent implantation. The aim of this study was to evaluate whether abciximab could be more beneficial in different subgroups such as insulin-dependent (ID) patients and whether its use could provide additional benefits to those afforded by drug-eluting stents in these patients. PATIENTS AND METHODS: A total of 373 consecutive diabetics [223 non-insulin-dependent (NID) and 150 ID patients] who had undergone stent implantation were examined with a follow-up of 25.6+/-16.2 months. Abciximab was used in 21.7%. RESULTS: The abciximab-treated group had a lower rate of revascularization (26.8% vs. 15.8%. P=.02). The results by subgroups were as follows: NID nonabciximab, 23.5%; NID abciximab, 19% (P=NS); ID nonabciximab, 32.7%; ID abciximab, 12.2% (P=.05). In multivariate analysis, the restenosis predictors were insulin dependency (OR, 2.7), abciximab use (OR, 0.18), stent diameter (OR, 0.18). CONCLUSIONS: Abciximab use in diabetics with stent implantation has a favorable effect by reducing the need for new revascularization. This benefit is more evident in ID patients; the negative prognosis effect of being insulin-dependent is eliminated, and the percentage of events in this population over a long follow-up period is equal to those in NID patients.

Fractal photon sieve.

A novel focusing structure with fractal properties is presented. It is a photon sieve in which the pinholes are appropriately distributed over the zones of a fractal zone plate. The focusing properties of the fractal photon sieve are analyzed. The good performance of our proposal is demonstrated experimentally with a series of images obtained under white light illumination. It is shown that compared with a conventional photon sieve, the fractal photon sieve exhibits an extended depth of field and a reduced chromatic aberration.

Acute phase immune response to exercise coexists with decreased neutrophil antioxidant enzyme defences.

Long-duration or damaging exercise initiates reactions that resemble the acute phase response to infection and induces neutrophil priming for oxidative activity. Our objective was to establish the status of the antioxidant defences and of the oxidative equilibrium in the neutrophils of sportsmen prior to and after intense physical exercise. Nine voluntary male professional cyclists participated in this study. The exercise was a cycling mountain stage (171 km) and the cyclists took a mean +/- SEM of 270 +/- 12 min to complete it. We determined the activities of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), the levels and activity of superoxide dismutase (SOD), the concentrations of ascorbate, glutathione and glutathione disulphide (GSSG) and DNA levels in neutrophils. The cycling stage decreased enzyme activities expressed per DNA units: CAT (33%), SOD (38%), GPx (65%); increased ascorbate concentration in neutrophils and decreased the GSH/GSSG ratio and the enzyme activities expressed per DNA units. Neutrophils could contribute to plasma antioxidant defences against oxidative stress induced by exercise because they probably provide antioxidant enzymes and ascorbate.

Laparoscopic repair of vaginal evisceration: a case report.

Vaginal evisceration, although rare, is usually present in postmenopausal women with a history of vaginal surgery and high-grade pelvic floor dysfunction. Operative management is directed toward resecting any compromised bowel, repairing vaginal defect, and correcting the defect in the pelvic floor, which is associated with most cases, either in the same intervention or in a second procedure. Laparoscopy allows for assessment of the viability of the compromised bowel and the vaginal defect suture with advantages common to minimally invasive techniques. We report the first case in the international literature of vaginal evisceration managed by laparoscopy.