649 research outputs found
High-precision GPS survey of Via Appia: Archaeoastronomy-related aspects
Via Appia was built by the Romans around 312 BCE to connect Rome with Capua during the Samnite wars. The road is an astonishing engineering masterpiece. In particular, the segment which runs from Collepardo to Terracina – 61 km long – is renowned for being virtually straight; however this “straightness” was never investigated quantitatively. As a consequence, the techniques used by the ancient surveyors and their scope – whether it was only practical, or also symbolic – remain obscure. We report here a high-precision GPS survey of the road, performed with a u-blox receiver and further checked with a dual frequency receiver. We give a detailed analysis of the methods used and of the errors, which are shown to be less than 6’. To our knowledge it is the first time that such a long ancient manufactured structure has been surveyed with such a high accuracy. The results lead us to conclude that astronomy was certainly used in the construction of the road and in that of the associated grid, oriented to the setting of the star Castor and to the cardinal points respectively
GTE. A new software for gravitational terrain effect computation: theory and performances
The computation of the vertical attraction due to the topographic masses, the so-called Terrain Correction, is a fundamental step in geodetic and geophysical applications: it is required in high-precision geoid estimation by means of the remove–restore technique and it is used to isolate the gravitational effect of anomalous masses in geophysical exploration. The increasing resolution of recently developed digital terrain models, the increasing number of observation points due to extensive use of airborne gravimetry in geophysical exploration and the increasing accuracy of gravity data represents nowadays major issues for the terrain correction computation. Classical methods such as prism or point masses approximations are indeed too slow while Fourier based techniques are usually too approximate for the required accuracy. In this work a new software, called Gravity Terrain Effects (GTE), developed to guarantee high accuracy and fast computation of terrain corrections is presented. GTE has been thought expressly for geophysical applications allowing the computation not only of the effect of topographic and bathymetric masses but also those due to sedimentary layers or to the Earth crust-mantle discontinuity (the so-called Moho). In the present contribution, after recalling the main classical algorithms for the computation of the terrain correction we summarize the basic theory of the software and its practical implementation. Some tests to prove its performances are also described showing GTE capability to compute high accurate terrain corrections in a very short time: results obtained for a real airborne survey with GTE ranges between few hours and few minutes, according to the GTE profile used, with differences with respect to both planar and spherical computations (performed by prism and tesseroid respectively) of the order of 0.02 mGal even when using fastest profiles
Deployment and design of multiantenna solutions for fixed WiMAX systems
WiMax has already attracted the attention of operators and manifacturing industries for its promise of large throughput and coverage in broadband wireless access. However, towards the goal of an efficient deployment of this technology, a thorough analysis of its performance in presence of frequency reuse under realistic traffic conditions is mandatory. In particular, an important performance limiting factor is the inter-cell interference, which has strong non-stationary features. This paper investigates the deployment of multi-antenna base stations and the related design of signal processing algorithms for interference mitigation, for the uplink of IEEE 802.16-2004 systems. Extensive numerical results for realistic interference models show the advantages of the proposed multi-antenna system
Resectable IIIA-N2 non-small-cell lung cancer (NSCLC): In search for the proper treatment
Locally advanced non-small cell lung cancer accounts for one third of non-small cell lung cancer (NSCLC) at the time of initial diagnosis and presents with a wide range of clinical and pathological heterogeneity. To date, the combined multimodality approach involving both local and systemic control is the gold standard for these patients, since occult distant micrometastatic disease should always be suspected. With the rapid increase in treatment options, the need for an interdisciplinary discussion involving oncologists, surgeons, radiation oncologists and radiologists has become essential. Surgery should be recommended to patients with non-bulky, discrete, or single-level N2 involvement and be included in the multimodality treatment. Resectable stage IIIA patients have been the subject of a number of clinical trials and retrospective analysis, discussing the efficiency and survival benefits on patients treated with the available therapeutic approaches. However, most of them have some limitations due to their retrospective nature, lack of exact pretreatment staging, and the involvement of heterogeneous populations leading to the awareness that each patient should undergo a tailored therapy in light of the nature of his tumor, its extension and his performance status
Highly Sensitive Magnetic Array-based Platform for Neuronal Signal Recording
This work presents a platform for the detection of the neuronal magnetic signal arising from the propagation of the action potential along the axon, via an array of highly sensitive magnetoresistive sensors and a low noise front-end electronic setup. We report the results of calculations and experiments for estimating the limit of detection of such platform in terms of minimum detectable magnetic field. Furthermore, an experimental setup for recording the magnetic signal in a brain slice is presented. (C) 2017 The Authors. Published by Elsevier Ltd
Studio della quota di volo mediante GNSS, altimetro radar e barometro per rilievi di spettroscopia gamma da velivolo
Lo studio della distribuzione dei radionuclidi terrestri (238U, 232Th e 40K) realizzato mediante tecniche di spettroscopia gamma da velivolo è influenzato dalla quota a cui il rivelatore si trova rispetto al suolo. Un'incertezza del 10% a 100 m di altezza origina un errore nella stima del segnale gamma del 208Tl, appartenente alla catena di decadimenti del 232Th, dell’ordine del 7%. L'impiego di una nuova classe di spettrometri montati a bordo di UAV (Unmanned Aerial Vehicle) per raffinate misure in contesti ostili o remoti rende necessaria un'accurata stima in real time della quota di volo. Il Radgyro è un velivolo dedicato a survey multiparametrici, capace di trasportare strumentazione pari ad un payload massimo di 120 kg, tra cui quattro spettrometri gamma NaI(Tl). Una stazione inerziale con ricevitore integrato GNSS (Global Navigation Satellite System) restituisce l'assetto del velivolo con una frequenza massima di 400 Hz. Il velivolo è dotato di un network di tre ricevitori GNSS posizionati alle estremità della carena del velivolo. Un altimetro radar a 24 GHz rileva la quota con una frequenza di 60 Hz. La misura di pressione e temperatura consente di ricavare la quota barometrica a 2 Hz. Con l'obiettivo di studiare le incertezze associate alle misure della quota di volo acquisite dagli altimetri in relazione ai dati GNSS, sono stati realizzati tre voli sul mare in un range di altezze comprese tra 31 m e 249 m, per un totale di 4702 secondi di volo effettivo. Al termine dello studio è possibile concludere che l'errore complessivo delle abbondanze di K, U e Th aumenta di 7.7%, 0.5% e 2.7% rispettivamente, a causa delle incertezze della quota di volo
Determining the optimal communication channels of arbitrary optical systems using integrated photonic processors
Towards a magnetoresistive platform for neural signal recording
A promising strategy to get deeper insight on brain functionalities relies on the investigation of neural activities at the cellular and sub-cellular level. In this framework, methods for recording neuron electrical activity have gained interest over the years. Main technological challenges are associated to finding highly sensitive detection schemes, providing considerable spatial and temporal resolution. Moreover, the possibility to perform non-invasive assays would constitute a noteworthy benefit. In this work, we present a magnetoresistive platform for the detection of the action potential propagation in neural cells. Such platform allows, in perspective, the in vitro recording of neural signals arising from single neurons, neural networks and brain slices
Integrating Empirical Analysis and Normative Inquiry in Health Technology Assessment:The Values in Doing Assessments of Health Technologies Approach
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