Universal Tunnelling Time in photonic Barriers

Tunnelling transit time for a frustrated total internal reflection in a double-prism experiment was measured using microwave radiation. We have found that the transit time is of the same order of magnitude as the corresponding transit time measured either in an undersized waveguide (evanescent modes) or in a photonic lattice. Moreover we have established that in all such experiments the tunnelling transit time is approximately equal to the reciprocal 1/f of the corresponding frequency of radiation.Comment: 8 pages, 4 figures, 1 tabl

Cerenkov's Effect and Neutrino Oscillations in Loop Quantum Gravity

Bounds on the scale parameter {\cal L} arising in loop quantum gravity theory are derived in the framework of Cerenkov's effect and neutrino oscillations. Assuming that {\cal L} is an universal constant, we infer {\cal L}> 10^{-18}eV^{-1}, a bound compatible with ones inferred in different physical context.Comment: 6 pages, no figures, in print on MPL

Sex hormones in allergic conjunctivitis: altered levels of circulating androgens and estrogens in children and adolescents with vernal keratoconjunctivitis

PURPOSE: Vernal keratoconjunctivitis (VKC) is a chronic allergic disease mainly affecting boys in prepubertal age and usually recovering after puberty. To evaluate a possible role of sex hormones in VKC, serum levels of sex hormones in children and adolescents with VKC were assessed. METHODS: 12 prepubertal and 7 early pubertal boys with active VKC and 6 male patients with VKC in remission phase at late pubertal age and 48 healthy age and sex-matched subjects were included. Serum concentration of estrone, 17 beta-estradiol, dehydroepiandrosterone-sulfate, total testosterone and free testosterone, dihydrotestosterone (DHT), cortisol, delta-4-androstenedione, follicle-stimulating hormone, luteinizing hormone, and sex-hormones binding globuline (SHBG) were evaluated. RESULTS: Serum levels of Estrone were significantly increased in all groups of patients with VKC when compared to healthy controls (P < 0.001). Prepubertal and early pubertal VKC showed a significant decrease in DHT (P = 0.007 and P = 0.028, resp.) and SHBG (P = 0.01 and P = 0.002, resp.) when compared to controls and serum levels of SHBG were increased in late pubertal VKC in remission phase (P = 0.007). CONCLUSIONS AND RELEVANCE: VKC patients have different circulating sex hormone levels in different phases of the disease and when compared to nonallergic subjects. These findings suggest a role played by sex hormones in the pathogenesis and/or activity of VKC

Maximal Acceleration Corrections to the Lamb Shift of Muonic Hydrogen

The maximal acceleration corrections to the Lamb shift of muonic hydrogen are calculated by using the relativistic Dirac wave functions. The correction for the $2S-2P$ transition is $\sim 0.38$ meV and is higher than the accuracy of present QED calculations and of the expected accuracy of experiments in preparation.Comment: LaTex file, 9 pages, to be published in Il Nuovo Cimento

A review of the role of ultrasound biomicroscopy in glaucoma associated with rare diseases of the anterior segment

Ultrasound biomicroscopy is a non-invasive imaging technique, which allows high-resolution evaluation of the anatomical features of the anterior segment of the eye regardless of optical media transparency. This technique provides diagnostically significant information in vivo for the cornea, anterior chamber, chamber angle, iris, posterior chamber, zonules, ciliary body, and lens, and is of great value in assessment of the mechanisms of glaucoma onset. The purpose of this paper is to review the use of ultrasound biomicroscopy in the diagnosis and management of rare diseases of the anterior segment such as mesodermal dysgenesis of the neural crest, iridocorneal endothelial syndrome, phakomatoses, and metabolic disorders

Probing the Brans-Dicke Gravitational Field by Cerenkov Radiation

The possibility that a charged particle propagating in a gravitational field described by Brans-Dicke theory of gravity could emit Cerenkov radiation is explored. This process is kinematically allowed depending on parameters occurring in the theory. The Cerenkov effect disappears as the BD parameter omega tends to inftinity, i.e. in the limit in which the Einstein theory is recovered, giving a signature to probe the validity of the Brans-Dicke theory.Comment: 8 pages, no figure

Ocular manifestations in Gorlin-Goltz syndrome

Background: Gorlin-Goltz syndrome, also known as nevoid basal cell carcinoma syndrome, is a rare genetic disorder that is transmitted in an autosomal dominant manner with complete penetrance and variable expressivity. It is caused in 85% of the cases with a known etiology by pathogenic variants in the PTCH1 gene, and is characterized by a wide range of developmental abnormalities and a predisposition to multiple neoplasms. The manifestations are multiple and systemic and consist of basal cell carcinomas in various regions, odontogenic keratocistic tumors and skeletal anomalies, to name the most frequent. Despite the scarce medical literature on the topic, ocular involvement in this syndrome is frequent and at the level of various ocular structures. Our study focuses on the visual apparatus and its annexes in subjects with this syndrome, in order to better understand how this syndrome affects the ocular system, and to evaluate with greater accuracy and precision the nature of these manifestations in this group of patients. Results: Our study confirms the presence of the commonly cited ocular findings in the general literature regarding the syndrome [hypertelorism (45.5%), congenital cataract (18%), nystagmus (9%), colobomas (9%)] and highlights strabismus (63% of the patients), epiretinal membranes (36%) and myelinated optic nerve fiber layers (36%) as the most frequent ophthalmological findings in this group of patients. Conclusions: The presence of characteristic and frequent ocular signs in the Gorlin- Goltz syndrome could help with the diagnostic process in subjects suspected of having the syndrome who do not yet have a diagnosis. The ophthalmologist has a role as part of a multidisciplinary team in managing these patients. The ophthalmological follow-up that these patients require, can allow, if necessary, a timely therapy that could improve the visual prognosis of such patients