Marcatili's Lossless Tapers and Bends: an Apparent Paradox and its Solution

Numerical results based on an extended BPM algorithm indicate that, in Marcatili's lossless tapers and bends, through-flowing waves are drastically different from standing waves. The source of this surprising behavior is inherent in Maxwell's equations. Indeed, if the magnetic field is correctly derived from the electric one, and the Poynting vector is calculated, then the analytical results are reconciled with the numerical ones. Similar considerations are shown to apply to Gaussian beams in free space.Comment: 4 pages, figures include

Information exchanges between competitors: the Italian Competition Authority’s recent practice

In 2004, two cases on exchanges of information between competitors were decided by the Italian competition authority (“AGCM” – the Autorità Garante per la Concorrenza ed il Mercato). This revived a lively debate on the conditions in which these practices should be prohibited and whether they are anticompetitive per se. Over the years, the AGCM has taken a firm stand against such practices, in some cases beyond that taken by the European Commission and the European Court. This article reviews the rules and outlines the innovative approach that the AGCM has recently adopted

Antitrust Enforcement: Four New Investigations Opened by the AGCM in the First Months of 2005

The first three months of this year have witnessed extensive enforcement activity by Italy’s Autorità Garante per la Concorrenza ed il Mercato (“AGCM”). In the closing 90 days of the chairmanship of Professor Tesauro, former Advocate General at the European Court of Justice, the AGCM initiated a number of investigations for infringement of EC competition rules in various key markets: natural gas, telecommunication services, pharmaceuticals and postal services. The cases reported below are of particular interest since they are the first examples of enforcement of EC competition rules by the AGCM in the new “modernised” system of European enforcement

The regulation of fat metabolism during aerobic exercise

Since the lipid profile is altered by physical activity, the study of lipid metabolism is a remarkable element in understanding if and how physical activity affects the health of both professional athletes and sedentary subjects. Although not fully defined, it has become clear that resistance exercise uses fat as an energy source. The fatty acid oxidation rate is the result of the following processes: (a) triglycerides lipolysis, most abundant in fat adipocytes and intramuscular triacylglycerol (IMTG) stores, (b) fatty acid transport from blood plasma to muscle sarcoplasm, (c) availability and hydrolysis rate of intramuscular triglycerides, and (d) transport of fatty acids through the mitochondrial membrane. In this review, we report some studies concerning the relationship between exercise and the aforementioned processes also in light of hormonal controls and molecular regulations within fat and skeletal muscle cells

Electronically reconfigurable parasitic antenna array for pattern selectivity

Antenna arrays are commonly used to achieve high gains and beam steering, but they require complex feeding networks. For applications demanding moderate antenna gains (≃6 dB) and planar radiating structures, printed Yagi-Uda antennas can offer many advantages, but clearly, they cannot cover the whole azimuth plane. A symmetric structure made of two Yagi-Uda antennas with two active elements, a shared reflector and two directors of variable length is here presented and demonstrated to have switched beams that cover all the azimuth plane. By lengthening the physical lengths of the directors, they turn to act as reflectors: as a result, this antenna system has the ability to switch between broadside, bidirectional end-fire and two opposite end-fire patterns. The feeding is provided by a balanced parallel strip-slot line without the need for a balun section and thus reducing the overall size of the antenna. A modified design is also presented, obtained by adding a reflector board which allows for higher gains and focused radiation reconfigurability in the half-space. Simulated and measured results of both designs are reported showing good agreement. The antenna has a compact size, wideband characteristics and directive pattern reconfigurability

Beam-forming capabilities of a plasma circular reflector antenna

A gaseous plasma antenna array (PAA) is an aggregate of plasma discharges and possibly conventional metallic radiating elements, and it constitutes a promising alternative to metallic antennas for applications in which fast reconfiguration of radiation pattern, and gain is desired; such properties can be achieved by exploiting the electronic switch on/off condition of plasma discharges, and tuning of the plasma parameters. Here, the authors present a reconfigurable PAA that features a central metallic half-wavelength dipole working around 1.45\u2005GHz, surrounded by a planar circular lattice of cylindrical plasma discharges. Customised plasma discharges have been realised, and filled with argon gas at 2\u2005mbar so as to have a complete control on the plasma discharge properties (e.g. plasma frequency, collisional frequency). The magnitude of the reflection coefficient, and the gain pattern on the H-plane have been investigated numerically and experimentally; numerical and experimental results exhibit a good agreement and show that the central intrinsically omnidirectional antenna can provide simple beamforming capabilities upon turning on a subset of plasma discharges; as these plasma discharges are turned on, the authors have observed a maximum gain of 3c5\u2005dBi, a half-power beam width of 80 18, and an angular steering resolution of 3c15 18

Graphene sustained nonlinear modes in dielectric waveguides

We discuss the existence of nonlinear modes sustained by graphene layers in dielectric waveguides. Taking advantage of the almost two dimensional nature of graphene, we introduce the nonlinear effect as a parameter in the continuity equations. We then apply our modeling to a simple slab waveguide to enlighten how graphene can be used to induce huge nonlinear phase shifts at easily accessible power levels

Spotting Insects from Satellites: Modeling the Presence of Culicoides Imicola Through Deep CNNs

Nowadays, Vector-Borne Diseases (VBDs) raise a severe threat for public health, accounting for a considerable amount of human illnesses. Recently, several surveillance plans have been put in place for limiting the spread of such diseases, typically involving on-field measurements. Such a systematic and effective plan still misses, due to the high costs and efforts required for implementing it. Ideally, any attempt in this field should consider the triangle vectors-host-pathogen, which is strictly linked to the environmental and climatic conditions. In this paper, we exploit satellite imagery from Sentinel-2 mission, as we believe they encode the environmental factors responsible for the vector's spread. Our analysis - conducted in a data-driver fashion - couples spectral images with ground-truth information on the abundance of Culicoides imicola. In this respect, we frame our task as a binary classification problem, underpinning Convolutional Neural Networks (CNNs) as being able to learn useful representation from multi-band images. Additionally, we provide a multi-instance variant, aimed at extracting temporal patterns from a short sequence of spectral images. Experiments show promising results, providing the foundations for novel supportive tools, which could depict where surveillance and prevention measures could be prioritized

Anal sphincter dysfunction in multiple sclerosis: An observation manometric study

Constipation, obstructed defecation, and fecal incontinence are frequent complaints in multiple sclerosis. The literature on the pathophysiological mechanisms underlying these disorders is scant. Using anorectal manometry, we compared the anorectal function in patients with and without multiple sclerosis. 136 patients referred from our Center for Multiple Sclerosis to the Coloproctology Outpatient Clinic, between January 2005 and December 2011, were enrolled. The patients were divided into four groups: multiple sclerosis patients with constipation (group A); multiple sclerosis patients with fecal incontinence (group B); non-multiple sclerosis patients with constipation (group C); non-multiple sclerosis patients with fecal incontinence (group D). Anorectal manometry was performed to measure: resting anal pressure; maximum squeeze pressure; rectoanal inhibitory reflex; filling pressure and urge pressure. The difference between resting anal pressure before and after maximum squeeze maneuvers was defined as the change in resting anal pressure calculated for each patient. RESULTS: Group A patients were noted to have greater sphincter hypotonia at rest and during contraction compared with those in group C (p=0.02); the rectal sensitivity threshold was lower in group B than in group D patients (p=0.02). No voluntary postcontraction sphincter relaxation was observed in either group A or group B patients (p=0.891 and p=0.939, respectively). CONCLUSIONS: The decrease in the difference in resting anal pressure before and after maximum squeeze maneuvers suggests post-contraction sphincter spasticity, indicating impaired pelvic floor coordination in multiple sclerosis patients. A knowledge of manometric alterations in such patients may be clinically relevant in the selection of patients for appropriate treatments and for planning targeted rehabilitation therapy