Signal Design and Analysis for Time Delay Estimation with Application to Satellite Positioning

Positioning accuracy in satellite navigation systems depends on time-delay estimation (TDE) between satellite transmitted codes and local receiver replicas. This thesis explores the fundamental limits of TDE accuracy of spread spectrum (SS) signals making use of estimation theory and signal synchronization tools, which makes the proposed analysis suitable for both navigation and communication systems and independent from receiver configurations. In particular, this contribution derives some criteria to improve positioning accuracy in the additive white Gaussian noise (multipath-free) scenario, focusing on the (satellite) transmitter side of a SS system. Four different solutions, based on the minimization of the variance of the TDE, are presented by means of signal design. The first method speculates on the shaping of the pulse format of a linearly modulated Direct Sequence (DS)-SS signal. A pulse loss parameter useful for comparing performance of different pulse signals in a dedicated receiver bandwidth is thus defined. The second approach still considers DS-SS linearly modulated signals, proposing a joint shaping pulse-spreading code optimization. A design criterion to derive an optimal spreading waveform is thus derived both theoretically and numerically. A set of non-binary band-limited (NBBL) spreading waveforms that further improve the TDE accuracy while maintaining good properties of code acquisition and interference management are thus obtained. The third solution encompasses the design of SS-Continuous Phase Modulation (SS-CPM) that allows good TDE performance while guaranteing a constant complex envelope of the signal, thus showing high robustness to non-linear distortions introduced by non-linear HPA. Finally, as fourth approach, we show how a multicarrier signal can be formatted to obtain maximum estimation accuracy. Capitalizing on this, we also demonstrate that the inherent flexibility about power and frequency allocation possessed by such signal is expedient to the achievement of a cognitive localization system that adapts to the changing situation of availability and interference of a wideband radio channel. Performance of the proposed solutions for future GNSS systems is compared with that of existing DS-SS signals for current satellite positioning systems. Performance of some schemes is evaluated as signal options to be used in the C-band portion envisioned for GNSS evolutions. Possible countermeasures to the effects of multipath propagation are also discussed

Le spin-off di ricerca e la loro sopravvivenza

The paper tries to explain the strange survivorship of Italian spin-off firms generated by Italian Universities in order to test how much in the next future this phenomenon will turn out to be a link between Research and Industry. After a brief description of the features of the Italian case we show results coming from Survival Analysis, which demonstrate that both excellence of scientific research produced in University Departments and Industrial Sectors affect negatively the survival of spin-off firms

A population-based study of the years of life lost in the Friuli Venezia Giulia region, Italy

Background. The number of years of life lost (YLL) in a population depends not only on the number of deaths but also on the age at which the deaths have occurred, and, as a measure of the burden of premature mortality, is an important piece of information for public health professionals. Methods. We calculated YLL in the population of Friuli Venezia Giulia, a 1 200 000 inhabitant Italian region, in 2013 and the trend in the past 14 years, through a populationbased study using the regional mortality database as the source of information. The same projected life expectancy estimates for 2050 were used for calculating YLL both in males and females, for each calendar year. Results. In 2013, we counted 14 080 deaths and estimated 220 961 YLL. Malignant neoplasms and cardiovascular diseases accounted for the greatest number of YLL. Injuries had the highest number of YLL per death. Overall, YLL decreased from 2000 to 2013, but differences were observed for different causes of death. Cancers, cardiovascular diseases, and unintentional injuries showed a decreasing trend, whereas infectious diseases resulted increasing over time. Conclusion. This study, estimating the relative impact of different conditions on the society though the YLL, is a relevant input for the regional public health agenda

Link-Layer Coding for GNSS Navigation Messages

In this paper, we face the problem of ensuring reliability of Global Navigation Satellite Systems (GNSSs) in harsh channel conditions, where obstacles and scatter cause long outage events that cannot be counteracted with channel coding only. Our novel approach, stemming from information-theoretic considerations, is based on link-layer coding (LLC). LLC allows us to significantly improve the efficiency in terms of time-to-first-fix with respect to current operational GNSSs, which adopt carousel transmission. First, we investigate the maximum theoretical LLC gain under different Land Mobile Satellite channel conditions. Then, some practical LLC coding schemes, namely, fountain codes and a novel low-density parity-check plus low-rate repetition coding, are proposed and tested in realistic single-satellite and multi-satellite Land Mobile Satellite scenarios, considering the Galileo I/NAV message as study case. Simulation results show that our designed schemes largely improve on carousel transmission and achieve near-optimal performance with limited increase in complexity. Also, back-compatibility of LLC is assessed with respect to present-time GNSS specifications. © 2018 Institute of Navigation

ISS mapped from ICD-9-CM by a novel freeware versus traditional coding: a comparative study

<p>Abstract</p> <p>Background</p> <p>Injury severity measures are based either on the Abbreviated Injury Scale (AIS) or the International Classification of diseases (ICD). The latter is more convenient because routinely collected by clinicians for administrative reasons. To exploit this advantage, a proprietary program that maps ICD-9-CM into AIS codes has been used for many years. Recently, a program called ICDPIC trauma and developed in the USA has become available free of charge for registered STATA^®users. We compared the ICDPIC calculated Injury Severity Score (ISS) with the one from direct, prospective AIS coding by expert trauma registrars (dAIS).</p> <p>Methods</p> <p>The administrative records of the 289 major trauma cases admitted to the hospital of Udine-Italy from 1 July 2004 to 30 June 2005 and enrolled in the Italian Trauma Registry were retrieved and ICDPIC-ISS was calculated. The agreement between ICDPIC-ISS and dAIS-ISS was assessed by Cohen's Kappa and Bland-Altman charts. We then plotted the differences between the 2 scores against the ratio between the number of traumatic ICD-9-CM codes and the number of dAIS codes for each patient (DIARATIO). We also compared the absolute differences in ISS among 3 groups identified by DIARATIO. The discriminative power for survival of both scores was finally calculated by ROC curves.</p> <p>Results</p> <p>The scores matched in 33/272 patients (12.1%, k 0.07) and, when categorized, in 80/272 (22.4%, k 0.09). The Bland-Altman average difference was 6.36 (limits: minus 22.0 to plus 34.7). ICDPIC-ISS of 75 was particularly unreliable. The differences increased (p < 0.01) as DIARATIO increased indicating incomplete administrative coding as a cause of the differences. The area under the curve of ICDPIC-ISS was lower (0.63 vs. 0.76, p = 0.02).</p> <p>Conclusions</p> <p>Despite its great potential convenience, ICPIC-ISS agreed poorly with its conventionally calculated counterpart. Its discriminative power for survival was also significantly lower. Incomplete ICD-9-CM coding was a main cause of these findings. Because this quality of coding is standard in Italy and probably in other European countries, its effects on the performances of other trauma scores based on ICD administrative data deserve further research. Mapping ICD-9-CM code 862.8 to AIS of 6 is an overestimation.</p

Spectrally Compatible Iterative Water Filling

Until now static spectrum management has ensured that DSL lines in the same cable are spectrally compatible under worst-case crosstalk conditions. Recently dynamic spectrum management (DSM) has been proposed aiming at an increased capacity utilization by adaptation of the transmit spectra of DSL lines to the actual crosstalk interference. In this paper, a new DSM method for downstream ADSL is derived from the well-known iterative water-filling (IWF) algorithm. The amount of boosting of this new DSM method is limited, such that it is spectrally compatible with ADSL. Hence it is referred to as spectrally compatible iterative water filling (SC-IWF). This paper focuses on the performance gains of SC-IWF. This method is an autonomous DSM method (DSM level 1) and it will be investigated together with two other DSM level-1 algorithms, under various noise conditions, namely, iterative water-filling algorithm, and flat power back-off (flat PBO)

Neuroprotection in traumatic brain injury : mesenchymal stromal cells can potentially overcome some limitations of previous clinical trials

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. In the last 30 years several neuroprotective agents, attenuating the downstream molecular and cellular damaging events triggered by TBI, have been extensively studied. Even though many drugs have shown promising results in the pre-clinical stage, all have failed in large clinical trials. Mesenchymal stromal cells (MSCs) may offer a promising new therapeutic intervention, with preclinical data showing protection of the injured brain. We selected three of the critical aspects identified as possible causes of clinical failure: the window of opportunity for drug administration, the double-edged contribution of mechanisms to damage and recovery, and the oft-neglected role of reparative mechanisms. For each aspect, we briefly summarized the limitations of previous trials and the potential advantages of a newer approach using MSCs

The influence of patients’ complexity and general practitioners’ characteristics on referrals to outpatient health services in an Italian region

Background. Patient referrals to outpatient health services may affect both health outcomes and health expenditures. General practitioners (GP) have a crucial role in driving the use of outpatient services and recognizing factors which affect referrals is important for health managers and planners. Objectives. We investigated patient- and physician-related determinants of patient referrals in an Italian region. Methods. This was cross-sectional study based on the individual linkage of administrative databases from the health information system of the Friuli Venezia Giulia region. For each GP of the region, the association of the number of patient referrals to different types of outpatient services with the proportion of patients with chronic conditions, with the number of hospital admissions and drug prescriptions in 2012, and with GP’s characteristics was investigated through multilevel multivariable Poisson regression models. Results. Some chronic conditions (e.g., cancer, autoimmune diseases, endocrine diseases, digestive system diseases) were positively associated with the number of referrals, as were hospital admissions and drug prescriptions. Time since GP’s graduation was inversely related with referrals. Conclusion. Patient complexity and GP’s experience affect referral rates. These factors should be considered in case of a reorganization of the general practice structure in Friuli Venezia Giulia

Single severe traumatic brain injury produces progressive pathology with ongoing contralateral white matter damage one year after injury

There is increasing recognition that traumatic brain injury (TBI) may initiate long-term neurodegenerative processes, particularly chronic traumatic encephalopathy. However, insight into the mechanisms transforming an initial biomechanical injury into a neurodegenerative process remain elusive, partly as a consequence of the paucity of informative pre-clinical models. This study shows the functional, whole brain imaging and neuropathological consequences at up to one year survival from single severe TBI by controlled cortical impact in mice. TBI mice displayed persistent sensorimotor and cognitive deficits. Longitudinal T2 weighted magnetic resonance imaging (MRI) showed progressive ipsilateral (il) cortical, hippocampal and striatal volume loss, with diffusion tensor imaging demonstrating decreased fractional anisotropy (FA) at up to one year in the il-corpus callosum (CC: − 30%) and external capsule (EC: − 21%). Parallel neuropathological studies indicated reduction in neuronal density, with evidence of microgliosis and astrogliosis in the il-cortex, with further evidence of microgliosis and astrogliosis in the il-thalamus. One year after TBI there was also a decrease in FA in the contralateral (cl) CC (− 17%) and EC (− 13%), corresponding to histopathological evidence of white matter loss (cl-CC: − 68%; cl-EC: − 30%) associated with ongoing microgliosis and astrogliosis. These findings indicate that a single severe TBI induces bilateral, long-term and progressive neuropathology at up to one year after injury. These observations support this model as a suitable platform for exploring the mechanistic link between acute brain injury and late and persistent neurodegeneration