Ultra Low Power Communication Protocols for UWB Impulse Radio Wireless Sensor Networks

This thesis evaluates the potential of Ultra Wideband Impulse Radio for wireless sensor network applications. Wireless sensor networks are collections of small electronic devices composed of one or more sensors to acquire information on their environment, an energy source (typically a battery), a microcontroller to control the measurements, process the information and communicate with its peers, and a radio transceiver to enable these communications. They are used to regularly collect information within their deployment area, often for very long periods of time (up to several years). The large number of devices often considered, as well as the long deployment durations, makes any manual intervention complex and costly. Therefore, these networks must self-configure, and automatically adapt to changes in their electromagnetic environment (channel variations, interferers) and network topology modifications: some nodes may run out of energy, or suffer from a hardware failure. Ultra Wideband Impulse Radio is a novel wireless technology that, thanks to its extremely large bandwidth, is more robust to frequency dependent propagation effects. Its impulsional nature makes it robust to multipath fading, as the short duration of the pulses leads most multipath components to arrive isolated. This technology should also enable high precision ranging through time of flight measurements, and operate at ultra low power levels. The main challenge is to design a system that reaches the same or higher degree of energy savings as existing narrowband systems considering all the protocol layers. As these radios are not yet widely available, the first part of this thesis presents Maximum Pulse Amplitude Estimation, a novel approach to symbol-level modeling of UWB-IR systems that enabled us to implement the first network simulator of devices compatible with the UWB physical layer of the IEEE 802.15.4A standard for wireless sensor networks. In the second part of this thesis, WideMac, a novel ultra low power MAC protocol specifically designed for UWB-IR devices is presented. It uses asynchronous duty cycling of the radio transceiver to minimize the power consumption, combined with periodic beacon emissions so that devices can learn each other's wake-up patterns and exchange packets. After an analytical study of the protocol, the network simulation tool presented in the first part of the thesis is used to evaluate the performance of WideMac in a medical body area network application. It is compared to two narrowband and an FM-UWB solutions. The protocol stack parameters are optimized for each solution, and it is observed that WideMac combined to UWB-IR is a credible technology for such applications. Similar simulations, considering this time a static multi-hop network are performed. It is found that WideMac and UWB-IR perform as well as a mature and highly optimized narrowband solution (based on the WiseMAC ULP MAC protocol), despite the lack of clear channel assessment functionality on the UWB radio. The last part of this thesis studies analytically a dual mode MAC protocol named WideMac-High Availability. It combines the Ultra Low PowerWideMac with the higher performance Aloha protocol, so that ultra low power consumption and hence long deployment times can be combined with high performance low latency communications when required by the application. The potential of this scheme is quantified, and it is proposed to adapt it to narrowband radio transceivers by combining WiseMAC and CSMA under the name WiseMAC-HA

Physical Properties of (2) Pallas

We acquired and analyzed adaptive-optics imaging observations of asteroid (2) Pallas from Keck II and the Very Large Telescope taken during four Pallas oppositions between 2003 and 2007, with spatial resolution spanning 32-88 km (image scales 13-20 km/pix). We improve our determination of the size, shape, and pole by a novel method that combines our AO data with 51 visual light-curves spanning 34 years of observations as well as occultation data. The shape model of Pallas derived here reproduces well both the projected shape of Pallas on the sky and light-curve behavior at all the epochs considered. We resolved the pole ambiguity and found the spin-vector coordinates to be within 5 deg. of [long, lat] = [30 deg., -16 deg.] in the ECJ2000.0 reference frame, indicating a high obliquity of ~84 deg., leading to high seasonal contrast. The best triaxial-ellipsoid fit returns radii of a=275 km, b= 258 km, and c= 238 km. From the mass of Pallas determined by gravitational perturbation on other minor bodies [(1.2 +/- 0.3) x 10-10 Solar Masses], we derive a density of 3.4 +/- 0.9 g.cm-3 significantly different from the density of C-type (1) Ceres of 2.2 +/- 0.1 g.cm-3. Considering the spectral similarities of Pallas and Ceres at visible and near-infrared wavelengths, this may point to fundamental differences in the interior composition or structure of these two bodies. We define a planetocentric longitude system for Pallas, following IAU guidelines. We also present the first albedo maps of Pallas covering ~80% of the surface in K-band. These maps reveal features with diameters in the 70-180 km range and an albedo contrast of about 6% wrt the mean surface albedo.Comment: 16 pages, 8 figures, 6 table

Statistical comparison of ARGO‐ and SVP‐derived velocities

XXXII Trobades Científiques de la Mediterrània, Planeta Oceà - Planet Ocean, celebradas del 5 al 7 de octubre de 2016 en Maó, Menorca.-- Homenatge als Drs. Marta Estrada, Jordi Font i Jordi Salat, pioners de l'oceanografia mediterrània moderna. A tribute to Drs. Marta Estrada, Jordi Font and Jordi Salat, pioneers of modern Mediterranean oceanography.-- 1 pageSince now more than a decade, the ARGO program has been implementing a marine observation system that provides T/S observations on the 0‐2000 dbar ocean layer. Apart from the thermohaline observations, surface and deep parking locations are available and provide information on oceanic currents both in the near‐surface (0‐1 db) and deep (1000 db) layers. ARGO deep displacements have been exploited to study currents at depth (Ollitrault 2013, Lebedev 2007, Rosell‐Fieschi 2013, 2014). Nevertheless, studies using ARGO surface displacements are very sparse (Rosell‐Fieschi, 2014). In this work, we present some recent results about the analysis of ARGO surface velocities. Comparison with SVP current estimates are shown, suggesting that ARGO provides complementary geophysical observations that should be of interest for the ocean description and the validation of operational analysis and prediction systemsPeer Reviewe

Cerebrospinal fluid and blood biomarkers of status epilepticus

International audienceStatus epilepticus is a condition resulting either from the failure of the mechanisms responsible for seizure termination or from the initiation of mechanisms that lead to abnormally prolonged seizures and require urgent administration of antiepileptic drugs. Refractory status epilepticus requires anesthetics drugs and may lead to brain injury with molecular and cellular alterations (eg, inflammation, and neuronal and astroglial injury) that could induce neurologic sequels and further development of epilepsy. Outcome scores based on demographic, clinical, and electroencephalography (EEG) condition are available, allowing prediction of the risk of mortality, but the severity of brain injury in survivors is poorly evaluated. New biomarkers are needed to predict with higher accuracy the outcome of patients admitted with status in an intensive care unit. Here, we summarize the findings of studies from patients and animal models of status epilepticus. Specific protein markers can be detected in the cerebrospinal fluid and the blood. One of the first described markers of neuronal death is the neuron-specific enolase. Gliosis resulting from inflammatory responses after status can be detected through the increase of S100-beta, or some cytokines, like the High Mobility Group Box 1. Other proteins, like progranulin may reflect the neuroprotective mechanisms resulting from the brain adaptation to excitotoxicity. These new biomarkers aim to prospectively identify the severity and development of disability, and subsequent epilepsy of patients with status. We discuss the advantages and disadvantages of each biomarker, by evaluating their brain specificity, stability in the fluids, and sensitivity to external interferences, such as hemolysis. Finally, we emphasize the need for further development and validation of such biomarkers in order to better assess patients with severe status epilepticus

Serum Neuron Specific Enolase: a new tool for seizure risk monitoring after status epilepticus

International audienceObjectiveThere is a need for accurate biomarkers to monitor EEG activity and assess seizure risk in patients with acute brain injury. Seizure recurrence may lead to cellular alterations and subsequent neurological sequels. We investigated whether Neuron Specific Enolase (NSE) and S100-beta (S100B), brain injury biomarkers, can reflect EEG activity and help to evaluate the seizure risk.MethodsWe included 11 patients, admitted to an intensive care unit for refractory status epilepticus, who underwent a minimum of 3 days of continuous EEG, concomitantly with daily serum NSE and S100B assays.We investigated on 103 days the relationships between serum NSE and S100B levels and two EEG scores to monitor the seizure risk. We looked for biochemical biomarker thresholds able to predict seizure recurrence.ResultsOnly NSE levels positively correlated with EEG scores. Similar temporal dynamics were observed for the time courses of EEG scores and NSE levels. NSE levels above 17 ng/mL were associated with seizure in 71% of patients. An increase of more than 15% of NSE levels was associated with seizure recurrence in 80% of patients.ConclusionsOur study highlights the potential of NSE as a biomarker of EEG activity and to assess risk of seizure recurrence

Epidemiology, clinical picture and long‐term outcomes of FIP1L1‐PDGFRA ‐positive myeloid neoplasm with eosinophilia: Data from 151 patients

International audienceFIP1L1-PDGFRA-positive myeloid neoplasm with eosinophilia (F/P+ MN-eo) is a rare disease: robust epidemiological data are lacking and reported issues are scarce, of low sample-size and limited follow-up. Imatinib mesylate (IM) is highly efficient but no predictive factor of relapse after discontinuation has yet been identified. One hundred and fifty-one patients with F/P+ MN-eo (143 males; mean age at diagnosis 49 years; mean annual incidence: 0.18 case per million population) were included in this retrospective nationwide study involving all French laboratories who perform the search of F/P fusion gene (study period: 2003-2019). The main organs involved included the spleen (44%), skin (32%), lungs (30%), heart (19%) and central nervous system (9%). Serum vitamin B12 and tryptase levels were elevated in 74/79 (94%) and 45/57 (79%) patients, respectively, and none of the 31 patients initially treated with corticosteroids achieved complete hematologic remission. All 148 (98%) IM-treated patients achieved complete hematologic and molecular (when tested, n = 84) responses. Forty-six patients eventually discontinued IM, among whom 20 (57%) relapsed. In multivariate analysis, time to IM initiation (continuous HR: 1,01 [0.99-1,03]; P = .05) and duration of IM treatment (continuous HR: 0,97 [0,95-0,99]; P = .004) were independent factors of relapse after discontinuation of IM. After a mean follow-up of 80 (56) months, the 1, 5- and 10-year overall survival rates in IM-treated patients were 99%, 95% and 84% respectively. In F/P+ MN-eo, prompt initiation of IM and longer treatment durations may prevent relapses after discontinuation of IM

Burden of grade 3 or 4 liver injury associated with immune checkpoint inhibitors

Background &amp; Aims: There is concern about the burden of liver injury in patients with cancer exposed to immune checkpoints inhibitors (ICIs). Methods: In a retrospective cohort study, we evaluated the likelihood of grade 3/4 liver injury, of grade 3/4 cholestatic liver injury, and of liver failure, as per the Common Terminology Criteria for Adverse Events (CTCAE) version 5, following treatment with ICIs. We compared these occurrences with a group of cancer patients who were propensity-matched and treated with conventional chemotherapy. For all ICI patients experiencing grade 3/4 liver injury, we conducted a causality assessment using the RUCAM method and examined patient outcomes. Results: Among 952 patients (median [IQR] age 66 [57–73] years, 64% males) who were treated with ICI between January 1, 2015, and December 31, 2019, a total of 86 (9%) progressed to grade 3/4 liver injury, and liver failure was not observed. Anti-PD-(L)1/anti-CTLA-4 antibodies combinations (adjusted hazard ratio 3.36 [95% CI: 1.67–6.79]; p <0.001), and chronic hepatitis B (adjusted hazard ratio 5.48 [95% CI: 1.62–18.5]; p = 0.006], were independent risk factors. Liver injury was attributed to ICI treatment in 19 (2.0%) patients. Patients with ICI toxicity typically presented with granulomatous hepatitis or cholangiocyte inflammation. ICI withdrawal was associated with cancer progression and mortality. Re-introduction of ICI was not associated with recurrent grade 3/4 liver injury. Compared with matched patients treated with conventional, non-ICI-based chemotherapy, anti-PD-(L)1/anti-CTLA-4 combinations (p <0.001) and anti-PD-(L)1 monotherapies (p = 0.053) increased the risk of grade 3/4 liver injury and of grade 3/4 cholestatic liver injury, respectively. Conclusions: An increased risk of grade 3/4 liver injury under anti-PD-(L)1/anti-CTLA-4 antibodies was observed, whereas no substantial increase in the likelihood of liver failure occurred even after treatment reintroduction. Impact and implications: There is concern about liver injury in patients with cancer exposed to immune checkpoints inhibitors (ICIs). We investigated the burden of grade 3/4 liver injury after treatment with ICIs in a multicentric cohort of patients with cancer. Overall, a 9% incidence of grade 3/4 liver injury was detected after ICIs, and direct ICI hepatotoxicity was demonstrated in 2% of patients. Anti-PD-(L)1/Anti-CTLA-4 antibody combinations, and chronic HBV infection were independent risk factors. ICI withdrawal for grade 3/4 liver injury was associated with cancer progression. Re-introduction of ICI treatment was not associated with recurrent grade 3/4 liver injury