Optical density of states near planar ENZ materials.

We study the local density of optical states (LDOS) for lossy dielectric substrates whose electric permittivity has a vanishing real part, approaching zero from the positive side of the real axis. A criterion for evaluating the threshold height above (below) which radiative (non-radiative) processes dominate for a dipole emitter is established. We focus on the case of a vertical dipole above the ϵ-near-zero (ENZ) substrate and show that, in the lossless case, complete LDOS cancellation originates from radiative modes in its near field. We evaluate the performance of commercially available ENZ materials and quantify the limits of such cancellation effects with the intrinsic losses of the substrate.

[Safety of reintroducing platelet-inhibitory doses of aspirin in patients with urticaria or angioedema induced by anti-inflammatory doses]. / Réintroduction de l'aspirine à dose antiagrégante après urticaire ou angio-oedème induits par des doses anti-inflammatoires.

BACKGROUND: Aspirin is one of the most widely prescribed drugs in the world on account of its analgesic, antipyretic, and anti-inflammatory properties. Its effect on platelet aggregation makes it the first choice for prophylaxis in cardiovascular, neurological and obstetric diseases. However, a history of aspirin-induced urticaria and/or angioedema is usually a contraindication for further prescription of the drug. The aim of this article was to demonstrate that patients presenting aspirin-induced cutaneous reactions at anti-inflammatory doses can safely benefit from aspirin reintroduction at platelet-inhibitory doses. PATIENTS AND METHODS: Patients with a history of aspirin-induced urticaria and/or angioedema referred to our department between January 2000 and June 2008 for double-blind placebo-controlled reintroduction at platelet-inhibitory doses for a medical indication were enrolled in this study. RESULTS: Seventy patients with aspirin hypersensitivity as well as a medical indication for this therapy were referred to our department. Of these, 38 (54.3%) had a history of aspirin-induced urticaria and/or angioedema, including three laryngeal oedemas (7.9%). All subjects received platelet-inhibitory doses of aspirin (maximal total dose: 400mg/day) in double-blind placebo-controlled fashion during a one-day hospitalization period. None of the patients presented an immediate hypersensitivity reaction. Only one patient, who had received a cumulative dose of 200mg/day, reported diffuse urticaria and facial angioedema of no clinical significance the following day. He had a history of chronic urticaria. CONCLUSION: This article demonstrates the safety of reintroducing platelet-inhibitory doses of aspirin in patients in whom it is indicated and reporting aspirin-induced urticaria and/or angioedema with anti-inflammatory doses. However, patients with a history of chronic urticaria should undergo a challenge with the lowest platelet-inhibitory dose (75mg/day) in order to minimize the risk of aggravating their condition.

Modelling of the near-field of metallic nanoparticle gratings: localized surface plasmon resonance and SERS applications.

We numerically study the influence of the shape of gold nanostructures on the spectral position of their localized surface plasmon resonance and on Surface Enhanced Raman Scattering efficiency. Calculations are performed using a Finite-Difference Time-Domain (FDTD) method, whose accuracy for dispersive media is enhanced through the use of a Drude-Lorentz model. The relevance of this method is then pointed out by comparing the calculations with experimental data for both the plasmon resonance and the Raman signal enhancement. The influence of a thin layer of water is also investigated.

Controlling the plasmon resonance of single metal nanoparticles by near-field anisotropic nanoscale photopolymerization.

We propose a new approach for tuning the Surface Plasmon (SP) resonance wavelength using hybrid nanoparticles. Our approach is based on nanoscale photopolymerization around metal nanoparticles. The enhanced optical near-field of silver nanoparticles triggers local photopolymerization. As a result, atomic force microscopy reveals two nanoscale polymerized lobes around nanoparticles, with a controlled effective index distribution. A spectral breaking degeneracy of surface plasmon resonance of the nanoparticles has been demonstrated by polarized extinction spectroscopy.

Staff comfort/discomfort with problem-based learning. A preliminary study.

Crucial to the implementation and success of any educational program, especially problem-based learning (PBL), is the support and co-operation from staff involved in its use. It is suggested that this support and co-operation is dependent on their understanding of and comfort with the process especially when PBL may require substantial change in teaching practices. This paper reports the results of a pilot survey of staff responses to several aspects of the PBL approach of which the authors became aware. The survey focuses on issues of comfort with the process, knowledge and understanding of PBL, and preparation for the teaching role in PBL. As a preliminary study, it provides some indicators of staff responses to PBL implementation as well as highlighting sources of comfort/discomfort with the process.

Energy dependent chest wall thickness equations for male lung monitoring with germanium detectors.

The thickness and fat fraction of the chest wall are important parameters for in vivo lung monitoring. They have been measured from ultrasonic images on 374 male workers of the French nuclear industry using four measurement locations, as dictated by the size and position of the germanium detectors used for monitoring. The plastic muscle equivalent chest wall thickness (PMECWT) and the plastic 50% muscle-50% adipose equivalent chest wall thickness (X5050) have been calculated for each worker at 17, 59.5, and 185.7 keV, respectively. Multi-linear regression models have been tested to predict PMECWT and X5050 as a function of anthropometric measurements. Finally, it was considered whether the average chest wall thickness could be used instead of the material equivalent chest wall thickness. It was found that the mean chest wall thickness was (27 ± 5) mm and the mean fat fraction was (25 ± 8)%. The best and more convenient model for material equivalent chest wall thickness is a linear function of the body mass index. Depending on the energy, the standard errors of estimate for this model range between 3.2-3.4 mm for PMECWT and between 3.2-3.7 mm for X5050. At 59.5 and 185.7 keV, it was determined, to an excellent approximation, that the fat fraction and consideration of an equivalent material are unnecessary, contrary to the case at 17 keV.

Rol de la imagenología en el proceso diagnóstico de la patología ginecológica benigna

En la actualidad, la selección y uso correcto de los diferentes métodos de imágenes disponibles (ecografía, tomografía axial computada y resonancia magnética) constituye uno de los pilares fundamentales para el adecuado proceso diagnóstico en ginecología. Para la mayoría de las patologías benignas que comprometen al aparato genital femenino, la ecografía transvaginal es una herramienta sensible, de fácil acceso, costo-efectiva y por tanto debiese constituir el método inicial de elección. Sin embargo, su eficacia depende de que el operador sea entrenado y experimentado en su interpretación. El uso de la tomografía computada (TC) y la resonancia magnética (RM) debiese restringirse a condiciones específicas, en especial para caracterizar lesiones que no son completamente evaluables por ultrasonido. La mayor utilidad de la TC está en el diagnóstico diferencial de las urgencias ginecológicas, en evaluar el compromiso extra pelviano de neoplasias anexiales y en el estudio preoperatorio de anomalías de la vía urinaria. Respecto de la RM, su mayor utilidad está en el estudio de lesiones anexiales complejas a la ultrasonografía, endometriosis pélvica profunda y extra pelviana, adenomiosis, malformaciones uterinas, etapificación local de neoplasias endometriales, cervicales y vaginales, y en la evaluación de miomas múltiples o extra pelvianos.

In gynecology, the selection and proper use of the different available imaging methods (ultrasound, computed tomography and magnetic resonance) is paramount for a proper diagnostic process. For most benign conditions affecting the female genital tract, transvaginal ultrasound constitutes an exam with has excellent sensitive, is readily accessible and cost-effective, therefore being the initial method of choice. However, its effectiveness depends on the operator training and expertise in interpretation. The use of computed tomography (CT) and magnetic resonance imaging (MRI) ought to be restricted for specific conditions, especially to characterize lesions not completely evaluated by ultrasound. The main benefit of CT is in the differential diagnosis of gynecological emergencies, in assessing extra pelvic extension of adnexal masses and in the preoperative assessment of urinary tract abnormalities. Regarding MRI it is most useful in the study of complex adnexal lesions, extra pelvic and deep pelvic endometriosis, adenomyosis, uterine malformations, local staging of endometrial, cervical and vaginal neoplasms, and multiple or extra pelvic leiomyomas.

How nanoparticles encapsulating fluorophores allow a double detection of biomolecules by localized surface plasmon resonance and luminescence.

The paper shows how polysiloxane particles encapsulating fluorophores can be successfully used to detect biotin-streptavidin binding by two types of technique. After functionalization of the particles by streptavidin, the fixation of the biomolecule can indeed be detected by a shift of the localized surface plasmon resonance of the biotinylated gold dots used as substrate and by the luminescence of the fluorophores evidenced by scanning near-field optical microscopy. The development of particles allowing such a double detection opens a route for increasing the reliability of biological detection and for multi-labelling strategies crossing both detection principles.

Spectral degeneracy breaking of the plasmon resonance of single metal nanoparticles by nanoscale near-field photopolymerization.

We report on controlled nanoscale photopolymerization triggered by enhanced near fields of silver nanoparticles excited close to their dipolar plasmon resonance. By anisotropic polymerization, symmetry of the refractive index of the surrounding medium was broken: C infinity v symmetry turned to C2v symmetry. This allowed for spectral degeneracy breaking in particles plasmon resonance whose apparent peak became continuously tunable with the incident polarization. From the spectral peak, we deduced the refractive-index ellipsoid fabricated around the particles. In addition to this control of optical properties of metal nanoparticles, this method opens new routes for nanoscale photochemistry and provides a new way of quantification of the magnitude of near fields of localized surface plasmons.

Spectroscopic study of the image formation in near-field microscopy, near an evanescent-homogeneous switching.

Near-field optical microscopes provide highly resolved images of various samples. However, images are difficult to interpret owing to their sensitivity to illumination conditions. Moreover, by contrast with classical microscopy, the near-field signal combines the contributions of evanescent and propagative modes. In this study, we present results of a spectroscopic study in near-field. Our purpose is to explain how a switching of one diffracted mode from homogeneous to evanescent can modify image formation. The main point is to establish a relation between the evanescence of one diffracted mode and the fringes that are often observed in near-field experimental images. Moreover, on a metallic sample, the possible occurrence of plasmon resonance contributes to image distortion in a mainly different way. We use a Fourier series Rayleigh 3D method to explain image formation.

Theoretical comparison of illumination and collection mode images of magneto-optical dots.

We compare theoretical images of the same sample obtained with two different scanning near-field optical microscopes. The sample is a two-dimensional periodic array of magnetic sub-micrometric dots. The magnetization is perpendicular to the sample plane (polar magnetization). The first configuration is a scanning tunnelling optical near-field microscope (STOM) where the tip is used in the detection mode and the sample is illuminated by total internal reflection. The second configuration is an inverted STOM: the tip is used in the emission mode and the diffracted field is far-field detected in one direction. We present the models used to describe the two configurations and then explain the main lines of the formalism used to calculate the diffracted fields by a magneto-optical sample.

[Evaluation and validation of controls of aerobiocontamination in the prevention of nosocomial invasive aspergillosis]. / Evaluation et validation de contrôles d'aérobiocontamination dans la prévention d'aspergilloses invasives nosocomiales.

Further to an invasive epidemic pulmonary aspergillosis, occurred in an onco-hematologic pediatric unit, an emergency plan has been organised and prophylactic precautions has been taken. The authors have retrospectively analysed the results concerning the aerial contamination. The authors have evaluated the efficacy of these prophylactic precautions. Their good results allow them to validate cleaning, disinfection and surveillance protocols.

Neurofibromatosis plexiforme: estudio con RM de dos casos clínicos y revisión de la literatura / Plexiform neurofibromatosis: MRI study of two clinical cases and review of the literature

Von Recklinghausen's disease orneurofibromatosis type 1 is a genetic disorder characterized by cutaneous lesions, skeletal malformations and some degree of mental impairment. It is common that neurofibromas appear, these are slow growing, benign tumours of the neural sheath. Plexiform neurofibromas are patognomonic ofNF 1. These are characterized by a late diagnosis when they compromise nerve function or when they have associated soft tissue deformity. They must be studied directly because they have a higher risk of malignant transformation. We present two patients that debuted with plexiform neurofibromas with a review of the literature on the subject.

La enfermedad de Von Recklinghausen o neurofibromatosis tipo 1 es una enfermedad genética caracterizada por lesiones cutáneas, malformaciones esqueléticas y algún grado de retraso mental. En el curso de la enfermedad la presencia de neurofibromas, tumores de la vaina nerviosa de comportamiento benigno y crecimiento lento es altamente probable, siendo los plexiformes patognomónicos de la enfermedad. Estos generalmente se diagnostican en estadios avanzados con compromiso de la función de los nervios involucrados o gran deformidad de partes blandas. Deben estudiarse de manera muy dirigida ya que tienen mayor riesgo de hacer una transformación maligna. Presentamos dos pacientes que debutaron con neurofibromas plexiformes, con una revisión de la literatura sobre el tema.