Rearrangement procedures in regenerative multibeammobile communications satellites with frequency reuse

After a short overview on the European tendencies about a Land Mobile Satellite Service, this paper describes an advanced system architecture, based on multiple spot-beams and on-board processing, capable of providing message and voice services over a wide European coverage, including some North-Africa and Middle-East countries. A remarkable problem associated with spot-beam configurations is the requirement for flexibility in the capacity offer to the various coverage areas. This means incorporating procedures for changing the on-board modulator-to-spot associations, respecting the constraints imposed by frequency reuse. After discussing the requirements of the rearrangement procedure, an on-purpose algorithm is presented. This paper is derived from work performed on contract to the European Space Agency (ESA)

Il ruolo dell'ortodontista nel Surgery First Approach

Il “Surgery First Approach” (SFA) è un approccio alternativo al paziente con malocclusione dento-scheletrica in cui l’intervento di chirurgia ortognatica viene effettuato all’inizio del trattamento e tutte le fasi ortodontiche effettuate nel trattamento convenzionale, sia quella di preparazione delle arcate all’intervento chirurgico che quella di stabilizzazione dell’occlusione, vengono effettuate dopo l’intervento di chirurgia ortognatica. Con l’incremento dell’utilizzo del Surgery First Approach, diversi sono gli aspetti già indagati in letteratura man mano che tale protocollo viene adottato dalle Scuole chirurgiche e ortodontiche. Attualmente il punto di vista più valutato è quello chirurgico maxillo-facciale, mentre il ruolo dell’ortodontista nel Surgery First Approach e gli obiettivi dell’ortodonzia postchirurgica sono stati invece fino a oggi poco indagati. Lo scopo della ricerca è: riportare l'esperienza della UOC di Ortognatodonzia dell’Università “Sapienza” di Roma nel trattamento dei pazienti disgnatici con Surgery First Approach; presentare il protocollo Surgery First utilizzato presso la nostra UOC di Ortognatodonzia in collaborazione con la UOC di Chirurgia MaxilloFacciale; studiare il ruolo dell’ortodonzia post-chirurgica in questa nuova metodica.The Surgery First Approach is an alternative protocol to a dento-skeletal malocclusion. The first phase of the treatment is the orthognatic surgery followed by all the orthodonthic phases, both the pre-surgical preparation of the upper and lower arches and the post-surgical occlusal stabilization. At the present, the surgical point of view is the more studied by papers in literature, while the role of the post-surgical orthodontics is less analysed. Aim of the thesis is: to report the experience of the Unit of Orthodontics of the Rome "Sapienza" University with Surgery First approach in patients with dento-skeletal malocclusion; to present our protocol, developed in partnership with the Unit of Maxillo-Facial Surgery; to study the role of post-surgical orthodontics dealing with this new approach

TRATTAMENTO DEL MORSO APERTO ANTERIORE SCHELETRICO. CASI BORDERLINE

Il trattamento del morso aperto anteriore scheletrico costituisce una delle problematiche più complesse da affrontare per l’ortodontista. Alcuni casi di open-bite, a causa della leggera componente scheletrica, sono al confine fra l’essere di pertinenza di un trattamento ortodontico piuttosto che di un trattamento ortodontico-chirurgic

Ramus marginalis mandibulae nervus facialis palsy in hemifacial microsomia.

AIM: The paralysis of the ramus marginalis mandibulae nervus facialis may occur in Hemifacial Microsomia (HM); the combination of both HM and palsy contributes to an elongation of the mandibular body. This study explores a possible correlation between neurological deficit, muscular atony, and structural deficiency. STUDY DESIGN: Of 58 patients with HM who had come to the University of Rome (Sapienza) Pre-surgical Orthodontics Unit, 4 patients were afflicted with Hemifacial Microsomia and ramus marginalis mandibulae nervus palsy; these patients underwent physical, neurological, opthamologic and systemic examinations. The results were then analysed in order to determine a possible correlation between neuro-muscular and structural deficit. METHODS: Electroneurographic and electromyographic examinations were performed to estimate facial nerve and muscles involvement. RESULTS: Neuroelectrographic exam showed a damage of the nervous motor fibres of the facial nerve ipsilateral to HM, with an associated damage of the muscular function, while neuro-muscular functions on the healthy side were normal. CONCLUSIONS: The peripheral nervous and muscular deficits affect the function of facial soft tissues and the growth of mandibular body with an asymmetry characterised by a hypodevelopment of the ramus (due to the HM) and by an elongation of the mandibular body (due to ramus marginalis mandibulae nerve palsy), so that the chin deviation is contralateral to HM. In these forms, a neurological examination is necessary to assess the neurological damage on the HM side. Neuromuscular deficiency can also contribute to a relapse tendency after a surgical-orthodontic treatment

Caratteristiche biomeccaniche nella tecnica linguale

Objectives Esthetics is a major consideration in the decision to undergo an orthodontic treatment. This report focuses on lingual orthodontics as a valid alternative for patients who require a truly “invisible” treatment. Materials and methods In recent years, considerable progress has been made in the field of biomechanics. We carried out a review of the literature to analyze the main features of the lingual orthodontic technique and to compare this approach with the vestibular technique. Results The advantages of the lingual approach include reduced distance between the applied force and the Center of Resistance and a bite-opening effect. The disadvantages include a reduced interbracket distance and a bowing effect. Conclusions Compared with the vestibular approach, the biomechanics used in lingual orthodontics offer potential advantages in terms of esthetics and treatment time along with valid functional results