1,720,966 research outputs found
Sensors and algorithms development for body sensor networks in healthcare environment
No full textLa rapida diffusione e la grande popolaritá di laptops, smartphones,PDAs, dispositivi GPS e altri apparecchi elettronici nell'era
post-PC, hanno alimentato la tendenza di produrre apparecchi elettronici sempre piú portatili, versatili e a buon mercato, con capacitá di calcolo sempre piú elevate. I continui progressi tecnologici hanno condotto ad un'abbondante disponibilitá di microprocessori e microcontrollori sempre piú piccoli ed economici, equipaggiati con
sensori sempre piú avanzati, storage e dotati di connessione wireless.
In quest' ottica si colloca l'emergere di una nuova tipologia di reti di telecomunicazioni: le Wireless Sensor Networks (WSNs), le quali rappresentano pienamente l'ultima tendenza della famosa
legge di Moore nei confronti della miniaturizzazione e dell'ubiquitá
dei dispositivi elettronici. L'integrazione di capacitá di calcolo, memorizzazione e comunicazione in dispositivi di dimensioni ridotte e a basso costo ha portato alla de finizione delle WSNs. Le reti
di sensori sono state pensate come possibili strumenti per l'activity
recognition in campo biomedico, i risultati di tale applicazione mostrano come questa essa sia molto e fficace nel monitoraggio della azioni di pazienti.
Viene inoltre presentata un applicazione realizzata attraverso una WSN. Si tratta di un un applicazione per HRV (Heart Rate Variability).
L'HRV é basata sull'analisi tempo-frequenza degli intervalli
R-peak raccolti da un segnale ECG. Tale studio propone un
toolkit realizzato attraverso una rete di sensori wireless per l'analisi
temporale dell'HRV, chiamata SPINE-HRV (Signal Processing In Node Environment SPINE). SPINE-HRV é composto da un sistema
indossabile per il monitoring dell'attivitá cardiaca in grado di raccogliere continuamente gli R-peak e un applicazione in grado di processare cosí i dati raccolti. L'analisi fatta attaverso lo SPINEHRV
toolkit fornisce sette parametri ben noti in letteratura medica in grado di aiutare i cardiologi nella diagnosi relativa a diverse problematiche.
Inoltre tale toolkit fornisce uno strumento automatico per rilevazione di stati di stress acuti rilevabili durante tutte le attivitá svolte quotidianamente.
Nella seconda parte verrá presentata una panoramica sui media gateway in particolare sui transcoder video per gli standard di codi
ca video H.263+ e H.264. L'eterogeneitá sempre piú diffusa dei dispositivi presenti all'interno della rete Internet, rende necessaria lo sviluppo di dispositivi hardware o software in grado da permettere
una a dabile intercomunicazione tra tali diversi dispositivi.
In particolare si mostrerá come é possibile riutilizzare i modi Intra estratti durante il processo di decodi fica per aumentare l'efficienza della codifi ca in altro standard di codi ca video. Sono stati sviluppati due algoritmi in grado di selezionare attraverso una decisore
a soglia, utilizzato sia per i modi 4x4 che 16x16. Verranno presentati le prestazioni in termini di PSNR e tempi di elaborazione
confrontati con quelle relative l'approccio full transcoding. Tali risultati mostrano come siano stati ottenuti signi ficativi riduzioni dei tempi computazionali pur mantenendo un livello di PSNR confrontabile
con quello relativo al processo di full transcoding.With the wide diffusion and popularity of laptops, cell-phones, Personal Digital Assistants (PDAs), GPS devices and other intelligent electronic in the post-PC era, computing devices have become more portable, mobile and cheap. Nowadays the electronic in uences the daily life of each man and many tasks hard to do in the past now have become reality and easy to perform thanks to the
signi cant advances in technology. From this viewpoint the emergence of wireless sensor networks (WSNs) is essentially the latest
trend of Moore's Law toward the miniaturization and ubiquity of
computing devices. Wireless sensor networks are used in order to
perform activity recognition in heath care eld, the results of this
application show how that it is effective in patient's actions monitoring.
Moreover an application regarding Heart Rate Variability (HRV)will be presented. This work is based on the analysis of the Rpeak
to R-peak intervals (RR-intervals) of the ECG signal in the time and/or frequency domains. Doctors and psychologists are increasingly recognizing the importance of HRV; in fact, a number of studies have demonstrated that patients with anxiety, phobias and posttraumatic stress disorder consistently show lower HRV,even when not exposed to a trauma related prompt. Importantly,this relationship existed independently of age, gender, trait anxiety,
cardio-respiratory tness, heart rate, blood pressure and respiration rate. The SPINE-HRV is composed of a wearable heart activity
monitoring system to continuously acquire the RR-intervals, and a processing application developed using the SPINE framework. The RR-intervals are processed using the SPINE framework at the base station side through a time-domain analysis of HRV. The analysis provides seven common parameters known in medical literature to help cardiologists in the diagnosis related to several heart diseases. In particular, SPINE-HRV is applied for stress detection of people during activities in their everyday life. Experimentations carried out by monitoring subjects in speci c
activities have shown the effectiveness of SPINE-HRV in detecting stress. Currently few research prototypes based on BSNs exist
that allow for HRV analysis. However SPINE-HRV represents the fi rst prototype using a wireless chest belt so making the system more comfortable than systems using wired electrodes or handheld devices. Furthermore, because the chest belt is a commercial product for sport and tness activities, it has been designed to be
robust against body movements. SPINE-HRV is currently applied to stress detection that is computed through an effective threshold
based algorithm. The experimentation of such an application has
been carried out on different subjects performing different activities
of the everyday life: walking, working at the PC, watching TV, sleeping, and driving. The obtained result are interesting as
they show that SPINE-HRV is able to detect stress by performing only a time-domain analysis of HRV with respect to more complex
computational methods based on the frequency-domain analysis.
Thus, SPINE-HRV can be actually used to detect stress of human beings in real-time. Currently, we are focusing our research efforts in improving the stress analysis algorithm by introducing frequency
domain features as well as comparing the obtained results to the clinical blood test for the stress hormone, which has been identi ed by the medical community as the quantitative measurement of the
emotional stress level. In the second part of this thesis will be described two smart video transcoder processes in order to develop a media gateway. The aim
of this network device is to bring about a conversion of the input
bitstream into another one characterized by a different video codec.
The codecs involved in the transcoding algorithm are the H.263+
(Annex I) and the H.264 baseline pro le. The scope of this study focuses on the possibility of reusing the Intra modes extracted from the input bitstream. Regarding H.263+ to H.264 transcoding, two
different thresholds are evaluated for 4x4 blocks and 16x16 macroblocks:
all the incoming modes that lead to costs over threshold are rejected and a re-estimation is performed. Otherwise, the incoming Intra mode is directly passed to the H.264 encoder. On the other hand, all the H.264 Intra modes are mapped into the H.263+ Intra modes and passed to the H.263+ encoder skipping the Intra prediction stage. Performance in terms of PSNR and elaboration
time of our algorithms are compared to that of the full transcoding approach. A high correlation with PSNR scores is obtained and a significant reduction of computational burden for both transcoding processes is also achieved. The two video transcoder architectures are proposed in order to perform the H.263+ to H.264 conversion
and vice versa. Referring to the rst transcoder, two adaptive
thresholds are implemented. Both thresholds, used for 4x4 Intra block mode decision and 16x16 Intra block mode decision, vary
according to the overall macroblock cost in order to consider the level of detail of the under-study macroblock. This solution is an
innovation relating to the approaches proposed in literature based
on the usage of a single xed threshold. We can assert that these algorithms represent a basis for the implementation of a low complexity fast transcoder for real-time applications thanks to the low complexity of the modi cation introduced, and also for the reduced computational burden of the entire trancoding process. In fact, we demonstrate a decrease of about 32% in the overall elaboration procedure using an arbitrary QP. The proposed platform also shows
high reliability in terms of perceived quality. This is confi rmed by PSNR evaluations for fast transcoding output. PSNR differences are limited to 0.1 dB for all sequences used in the tests. So,
the quality of the full transcoding output is very close to the one
obtained by the fast transcoding technique. In addition, the overall increase in the bitrate is less than 12%. The H.264 to H.263+
transcoder uses a mapping between the incoming H.264 modes that is rather different to the one proposed in literature. The obtained results, using several standard sequences and QP, show that the overall quality is the same for the output bitstream obtained by the full transcoder and the proposed smart transcoder algorithm,
and the bitrate increase is limited to 9% in the worst case. With this mapping it is possible to cancel the computational burden of the Intra mode prediction process. All these considerations allow us to assert that the proposed algorithm can be used in real-time transcoding architectures. Similar analysis concerning Inter frame pictures are actually under study by the authors in order to reduce the complexity of motion estimation procedure in transcoding architectures
Scaling and Multiscaling in Financial Indexes: A Simple Model
Full text linkIn this Ph.D Thesis we propose a simple stochastic model for time series which is analytically tractable, easy to simulate and which captures some relevant stylized facts of financial indexes, including scaling properties.
We show that the model fits the Dow Jones Industrial Average time series in the period 1935-2009 with a remarkable accuracy and finally we derive some results on option pricingIn questa tesi di Dottorato proponiamo un semplice modello stocastico per serie storiche, che presenta le seguenti caratteristiche: è analiticamente trattabile, facile da simulare e cattura alcuni importanti fatti stilizzati degli indici finanziari, fra cui proprietà di scaling. Inoltre, mostriamo che il modello ha un ottimo fit con la serie storica del Dow Jones Industrial Average fra il 1935-2009, e infine deriviamo alcuni risultati di option pricing per tale modell
From insurance risk to credit portfolio management: a new approach to pricing CDOs
No full textWe present a new approach for pricing collateralized debt obligations (CDOs) which takes into account the issue of the market incompleteness. In particular, we develop a suitable extension of the actuarial framework proposed by Bayraktar et al. [Valuation of mortality risk via the instantaneous Sharpe ratio: Applications to life annuities. J. Econ. Dyn. Control, 2009, 33, 676–691], Milevsky et al. [Financial valuation of mortality risk via the instantaneous Sharpe-ratio: Applications to pricing pure endowments. Working Paper, 2007. Available at: http://arxiv.org/abs/0705.1302], Young [Pricing life insurance under stochastic mortality via the instantaneous Sharpe ratio: Theorems and proofs. Technical Report, 2007. Available at: http://arxiv.org/abs/0705.1297] and Young [Pricing life insurance under stochastic mortality via the instantaneous Sharpe ratio. Insurance: Math. Econ., 2008, 42, 691–703], which is based on the so-called instantaneous Sharpe ratio. Such a procedure allows us to incorporate the attitude of investors towards risk in a direct and rational way and, in addition, is also suitable for dealing with the often illiquid CDO market. Numerical experiments are presented which reveal that the market incompleteness can have a strong effect on the pricing of CDOs, and allows us to explain the high bid-ask spreads that are frequently observed in the markets
Computing survival probabilities based on stochastic differential models
No full textWe develop a new numerical method to compute survival probabilities based on stochastic differential models, a matter of great importance in several areas of science, such as finance, biology, medicine and geophysics. This novel approach is based on polynomial differential quadrature, which is combined with a high-order time discretization scheme. Numerical experiments are presented showing that the proposed method performs extremely well and is more efficient than the approaches recently developed in Costabile et al. (2013) and Guarin et al. (2011)
Questionnaire-based evaluation of occupational and non-occupational solar radiation exposure in a sample of Italian patients treated for actinic keratosis and other non-melanoma skin cancers
Full text linkBackground An adequate evaluation of the ultraviolet (UV) cumulative exposure is a major problem in epidemiological studies on chronic skin damage. Questionnaires may be applied as useful tools. Objective We developed an original questionnaire to evaluate individual cumulative exposure to solar radiation (SR) in patients affected by actinic keratosis (AK), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Method The questionnaire, considering both working and leisure exposure, was applied to evaluate the whole life history of solar UV radiation exposure in a group of patients of the Dermatologic Clinic of UNIMORE. Results In outdoor workers (OW), the co-presence of AK/in situ SCC and invasive non-melanoma skin cancers (NMSCs) was increased compared to indoor workers (IW), as was the frequency of multiple skin lesions. The prevalence of skin lesions of the face was significantly higher in OW. Work 'sometimes' or 'often' in the shades was associated with an absence of skin lesions on the shoulders and neck, while workers adopting 'sometimes' or 'often' a downward bent position were more likely to develop lesions on the top of the head. Considering leisure activities, the use of tanning beds was associated to the presence of skin lesions on the shoulders, neck and chest. Considering vacation periods, subjects spending at least 2 h outdoor in the period 11 am to 1 pm presented earlier diagnoses of skin cancers. Conclusion Results of the original questionnaire developed are coherent with current knowledge and confirm the important role of UV exposure, both occupational and recreational, in the development of AK and NMSCs. Data support the hypothesis that this questionnaire can be applied as useful tool for the evaluation of cumulative UV exposure in future epidemiological studies
A Fast Method for H.263 to H.264 Intra Smart Transcoder
No full textAtti Riunione annuale GTTI, Firenze, June 16-18, 200
Web Video Communication Framwork for a new e-Government Service
No full textThis paper proposes a new e-government service for the citizens of Regione Marche: the web call center. Starting from the existing call center, the Regione Marche wants to provide additional services for the citizens and useful information about all the local government environments. The proposed service will allow to retrieve more information than those available by using the call center. Moreover, thanks to the usage of Internet technologies, it will be completely free. Practically, the service is an extension of the existing web site: a new web page allows a video communication with an operator that helps any citizen to retrieve information in a very easy way. This service is based on the Flash Media Server Architecture. Therefore, it implies only the flash media server license charge, it does not imply additional costs neither for the local government nor for the citizens because it is not necessary a new infrastructure building (such as VoIP telephones and central). Moreover it is not necessary for the citizens to install any additional software, in fact the access to the service is possible for non-skilled users too. Finally, the proposed system allows the Firewall and NAT-traversal by HTTP tunneling and it guarantees the streams encryption
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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