Bessel beam through a dielectric slab at oblique incidence: the case of total reflection

The oblique incidence of a Bessel beam on a dielectric slab with refractive index n1 surrounded by a medium of a refractive index n>n1 may be studied simply by expanding the Bessel beam into a set of plane waves forming the same angle with the axis of the beam. In the present paper we examine a Bessel beam that impinges at oblique incidence onto a layer in such a way that each plane-wave component impinges with an angle larger than the critical angle.Comment: 10 pages, 6 figure

Gravitational diffraction radiation

We show that if the visible universe is a membrane embedded in a higher-dimensional space, particles in uniform motion radiate gravitational waves because of spacetime lumpiness. This phenomenon is analogous to the electromagnetic diffraction radiation of a charge moving near to a metallic grating. In the gravitational case, the role of the metallic grating is played by the inhomogeneities of the extra-dimensional space, such as a hidden brane. We derive a general formula for gravitational diffraction radiation and apply it to a higher-dimensional scenario with flat compact extra dimensions. Gravitational diffraction radiation may carry away a significant portion of the particle's initial energy. This allows to set stringent limits on the scale of brane perturbations. Physical effects of gravitational diffraction radiation are briefly discussed.Comment: 5 pages, 2 figures, RevTeX4. v2: References added. Version to appear in Phys. Rev.

Temporary Acceleration of Electrons While Inside an Intense Electromagnetic Pulse

A free electron can temporarily gain a very significant amount of energy if it is overrun by an intense electromagnetic wave. In principle, this process would permit large enhancements in the center-of-mass energy of electron-electron, electron-positron and electron-photon interactions if these take place in the presence of an intense laser beam. Practical considerations severely limit the utility of this concept for contemporary lasers incident on relativistic electrons. A more accessible laboratory phenomenon is electron-positron production via an intense laser beam incident on a gas. Intense electromagnetic pulses of astrophysical origin can lead to very energetic photons via bremsstrahlung of temporarily accelerated electrons

Obstructive sleep apnea syndrome in the pediatric age: The role of the pneumologist

OBJECTIVE: This review paper aims to summarize the current state of knowledge on the role of the pneumologist in the diagnosis and respiratory treatment of children affected by obstructive Sleep Disordered Breathing (SDB). MATERIALS AND METHODS: A literature review has been performed on the following topics: obstructive SDB and its clinical entities, indications for respiratory treatment of pediatric SDB, and Continuous Positive Airway Pressure (CPAP) and Noninvasive Positive Pressure Ventilation (NIPPV) treatment approach to obstructive SDB. RESULTS: OSDB is related to obesity, craniofacial pathologies, neuromuscular disorders and, most commonly, adenotonsillar hypertrophy. Adenotonsillectomy is the first-choice treatment in children with obstructive apnea secondary to adenotonsillar hypertrophy. CPAP and NIPPV are recommended in cases where Obstructive Sleep Apnea (OSA) persists after surgery or when surgery is contraindicated. Treatment interventions are usually implemented gradually by separately addressing each abnormality that would predispose to obstructive SDB, then reevaluating after each intervention to detect any residual disease and to assess the need for additional treatment. CONCLUSIONS: Many pediatric patients continue to experience problems and symptoms such as hypersomnia and apnea after adenotonsillectomy and need CPAP/NIPPV treatment. Current knowledge is still incomplete, especially with regard to the mechanisms of pathogenesis of pediatric OSA, the factors affecting pediatric OSA, and the phenotypic variability of the disease. A better understanding of these aspects would contribute to the development of new therapies

'From mosh pit to posh pit': Festival imagery in the context of the boutique festival

This paper addresses market-based cultural production in the context of the UK festival field, with a focus on the framing of the festival experience through anticipation. In particular, boutique festivals are discussed as examples of a contemporary cultural ?product category? which has emerged and proliferated in the last decade. Through discourse analysis of media representations of boutique festivals, we situate the boutique festival in a broader sociocultural discourse of agency and choice, which makes it meaningful and desirable, and outline the type of consumer it is meant to attract. For the contemporary consumer, the boutique festival is presented as an anticipated experience based on countercultural festival imagery, while simultaneously framing cultural participation through consumption. The paper contributes to a wider debate on the construction of the consumer in the cultural economy

Obstructive sleep apnea syndrome in the pediatric age: the role of the otorhinolaryngologist

OBJECTIVE: Obstructive sleep apnea (OSA) is the primary indication for tonsillectomy, one of the most common pediatric surgical procedures, commonly performed in association with adenoidectomy. The objective of this review article is to evaluate the role of the otorhinolaryngologist in pediatric OSA. MATERIALS AND METHODS: A literature review has been performed on the following topics: peculiarities of sleep-disordered breathing in pediatric age; discrimination of sleep disorders; adenotonsillar hypertrophy; surgical techniques; adjuvant surgical procedures. RESULTS: The role of the otorhinolaryngologist in pediatric OSA is important for the evaluation of the upper airways and of essential biometric and polysomnographic data and for indication and execution of appropriate surgical treatment. In the majority of healthy children, adenotonsillectomy for OSA results in a dramatic improvement in respiratory parameters as measured by polysomnography. When post-surgical residual OSA occurs, it is essential to monitor patients by means of drug-induced sleep endoscopy (DISE). CONCLUSIONS: Otolaryngologic assessment is of paramount importance to correctly classify a child with OSA. Correct inspection of the upper airway and quantification of the quality of sleep through polysomnography lead to the right therapeutic choice. Knowledge of different surgical techniques helps to deal with residual OSA after studying the obstruction sites by drug-induced sedation endoscopy

The Neuropsychological Profile of Attention Deficits of Patients with Obstructive Sleep Apnea: An Update on the Daytime Attentional Impairment

none7noAbstract: Introduction: Patients with obstructive sleep apnea (OSA) suffer from several neurocognitive disturbances. One of the neuropsychological processes most investigated in OSA patients is attention, but the results have been controversial. Here, we update the attention profile of OSA patients with the final aim to improve attention assessment, with a possible impact on clinical and medical-legal practices, in terms of which attention subdomains and parameters need consideration and which one is a high-risk OSA phenotype for attention dysfunctions. Method: For this purpose, we assessed 32 previously untreated OSA patients (26 men and 6 women) under 65 years of age (mean age 53.2 ± 7.3; mean education level 10.4 ± 3.4 years) suffering from moderate to severe sleep apnea and hypopnea (mean apnea-hypopnea index (AHI) 45.3 ± 22.9, range 16.1–69.6). A control group of 34 healthy participants matched with OSA patients for age, education level, and general cognitive functioning were also enrolled. The OSA patients and healthy participants were tested through an extensive computerized battery (Test of Attentional Performance, TAP) that evaluated intensive (i.e., alertness and vigilance) and selective (i.e., divided and selective) dimensions of attention and returned different outcome parameters (i.e., reaction time, stability of performance, and various types of errors). Data analysis: The data were analyzed by ANCOVA which compared the speed and accuracy performance of the OSA and control participants (cognitive reserve was treated as a covariate). The possible mechanisms underlying attention deficits in OSA patients were examined through correlation analysis among AHI, oxygenation parameters, sleepiness scores, and TAP outcomes and by comparing the following three phenotypes of patients: severe OSA and severe nocturnal desaturators (AHI++D+), severe OSA nondesaturators (AHI++D−), and moderate OSA nondesaturators (AHI+D−). Results: The results suggest that the OSA patients manifest deficits in both intensive and selective attention processes and that reaction time (RT) alone is ineffective for detecting and characterizing their problems, for which error analysis and stability of performance also have to be considered. Patients with severe OSA and severe hypoxemia underperformed on alertness and vigilance attention subtests. Conclusions: The data suggest the importance of evaluating attention deficits among OSA patients through several parameters (including performance instability). Moreover, the data suggest a multifaceted mechanism underlying attention dysfunction in OSA patients.openAngelelli P., Macchitella L., Toraldo D.M., Abbate E., Marinelli C.V., Ariglian M., De Benedetto M.Angelelli, P.; Macchitella, L.; Toraldo, D. M.; Abbate, E.; Marinelli, C. V.; Ariglian, M.; De Benedetto, M

Circularly Symmetric Apodization via Starshaped Masks

Recently, we introduced a class of shaped pupil masks, called spiderweb masks, that produce point spread functions having annular dark zones. With such masks, a single image can be used to probe a star for extrasolar planets. In this paper, we introduce a new class of shaped pupil masks that also provide annular dark zones. We call these masks starshaped masks. Given any circularly symmetric apodization function, we show how to construct a corresponding starshaped mask that has the same point-spread function (out to any given outer working distance) as obtained by the apodization.Comment: Paper also at: http://www.orfe.princeton.edu/~rvdb/tex/starshape/ms.pdf Updated to clarify misleading statements regarding total throughput for apodizations and their corresponding starshaped mask

A New Berlin Questionnaire Simplified by Machine Learning Techniques in a Population of Italian Healthcare Workers to Highlight the Suspicion of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) syndrome is a condition characterized by the presence of repeated complete or partial collapse of the upper airways during sleep associated with episodes of intermittent hypoxia, leading to fragmentation of sleep, sympathetic nervous system activation, and oxidative stress. To date, one of the major aims of research is to find out a simplified non-invasive screening system for this still underdiagnosed disease. The Berlin questionnaire (BQ) is the most widely used questionnaire for OSA and is a beneficial screening tool devised to select subjects with a high likelihood of having OSA. We administered the original ten-question Berlin questionnaire, enriched with a set of questions purposely prepared by our team and completing the socio-demographic, clinical, and anamnestic picture, to a sample of Italian professional nurses in order to investigate the possible impact of OSA disease on healthcare systems. According to the Berlin questionnaire, respondents were categorized as high-risk and low-risk of having OSA. For both risk groups, baseline characteristics, work information, clinical factors, and symptoms were assessed. Anthropometric data, work information, health status, and symptoms were significantly different between OSA high-risk and low-risk groups. Through supervised feature selection and Machine Learning, we also reduced the original BQ to a very limited set of items which seem capable of reproducing the outcome of the full BQ: this reduced group of questions may be useful to determine the risk of sleep apnea in screening cases where questionnaire compilation time must be kept as short as possible