Waveform-independent frame-timing acquisition for UWB signals

In this paper, the problem of frame-level symbol timing acquisition for UWB signals is addressed. The main goal is the derivation of a frame-level timing estimator which does not require any prior knowledge of neither the transmitted symbols nor the received template waveform. The independence with respect to the received waveform is of special interest in UWB communication systems, where a fast and accurate estimation of the end-to-end channel response is a challenging and computationally demanding task. The proposed estimator is derived under the unconditional maximum likelihood criterion, and because of the low power of UWB signals, the low-SNR assumption is adopted. As a result, an optimal frame-level timing estimator is derived which outperforms existing acquisition methods in low-SNR scenarios.Peer Reviewe

NDA waveform estimation in the low-SNR regime

This correspondence addresses the problem of nondata-aided waveform estimation for digital communications. Based on the unconditional maximum likelihood criterion, the main contribution of this correspondence is the derivation of a closed-form solution to the waveform estimation problem in the low signal-to-noise ratio regime. The proposed estimation method is based on the second-order statistics of the received signal and a clear link is established between maximum likelihood estimation and correlation matching techniques. Compression with the signal-subspace is also proposed to improve the robustness against the noise and to mitigate the impact of abnormals or outliers.Peer Reviewe

Asymptotic equivalence between the unconditional maximum likelihood and the square-law nonlinearity symbol timing estimation

This paper provides a systematic approach to the problem of nondata aided symbol-timing estimation for linear modulations. The study is performed under the unconditional maximum likelihood framework where the carrier-frequency error is included as a nuisance parameter in the mathematical derivation. The second-order moments of the received signal are found to be the sufficient statistics for the problem at hand and they allow the provision of a robust performance in the presence of a carrier-frequency error uncertainty. We particularly focus on the exploitation of the cyclostationary property of linear modulations. This enables us to derive simple and closed-form symbol-timing estimators which are found to be based on the well-known square timing recovery method by Oerder and Meyr. Finally, we generalize the OM method to the case of linear modulations with offset formats. In this case, the square-law nonlinearity is found to provide not only the symbol-timing but also the carrier-phase error.Peer Reviewe

Detection of PPM-UWB random signals

This paper focuses on the symbol detection problem of random pulse-position modulation (PPM) ultrawideband (UWB) signals in the absence of interframe interference. Particular attention is devoted to severely time-varying channels where optimal detectors are proposed for both uncorrelated and correlated scattering scenarios. This is done by assuming the received waveforms to be unknown parameters. In UWB communication systems, the assumption of unknown random waveforms is consistent with the fact that the received waveform has very little resemblance with the original transmitted pulse. In order to circumvent this limitation, a conditional approach is presented herein by compressing the likelihood ratio test with the information regarding the second-order moments of the end-to-end channel response. Both full-rank and rank-one detectors are derived. For the reduced complexity rank-one detector, an iterative procedure is presented that maximizes the J-divergence between the hypotheses to be tested. Finally, simulation results are provided to compare the performance of the proposed detectors in different propagation environments.Peer Reviewe

Computer-Aided Validation of Formal Conceptual Models

Conceptual modelling is the process of the software life cycle concerned with the identification and specification of requirements for the system to be built. The use of formal specification languages provides more precise and concise specifications. Nevertheless, there is still a need for techniques to support the validation of formal specifications against the informal user requirements. A limitation of formal specifications is that they cannot readily be understood by users unless they have been specially trained. However, user validation can be facilitated by exploiting the executable aspects of formal specification languages. This thesis presents a systematic approach and workbench environment to support the construction and validation through animation of TROLL specifications. Our approach is an iterative requirements definition process consisting of the formal specification of requirements, the automatic transformation of the specification into an executable form, and the interactive animation of the executable version to validate user requirements. To provide objects with persistence in the animation environment, we analyse how the static structure of TROLL objects can be mapped into relational tables. In order to execute the specification, we analyse the operational meaning of state transitions in TROLL, determine an execution model, and describe the transformation of the specifications into C++ code. We present a prototype implementation of the workbench environment.Die konzeptionelle Modellierung ist die Phase im Softwareentwurf, die sich mit der Identifikation und der Spezifikation von Systemanforderungen befasst. Formale Spezifikationssprachen ermöglichen präzisere und eindeutigere Spezifikationen. Trotzdem werden Techniken zur Validierung von formalen Spezifikationen bezüglich der informellen Benutzeranforderungen weiterhin benötigt. Ein Nachteil von formalen Spezifikationen ist, dass sie für Benutzer ohne entsprechende Vorkenntnisse nicht leicht verständlich sind. Die Einbeziehung der Benutzer in den Validierungsprozess kann jedoch durch die Ausführung der Spezifikation vereinfacht werden. Diese Arbeit liefert einen systematischen Ansatz und eine Entwicklungsumgebung für die Konstruktion von TROLL-Spezifikationen und deren Validierung durch Animation. Unser Ansatz basiert auf einem iterativen Prozess zur Anforderungsdefinition bestehend aus der formalen Spezifikation von Anforderungen, der automatischen Übersetzung der Spezifikation in eine ausführbare Form, und der interaktiven Animation um die Benutzeranforderungen zu validieren. Um die Objektzustände in der Animationsumgebung persistent zu halten, wird untersucht, wie die statische Struktur von TROLL-Objekten in relationale Tabellen umgesetzt werden kann. Um die Spezifikationen auszuführen, wird die operationale Bedeutung von TROLL-Zustandsübergängen analysiert und ein Ausführungsmodell festgelegt. Anschließend wird die Übersetzung von den Spezifikationen in C++ beschrieben. Wir zeigen eine prototypische Implementierung der Animationsumgebung

Wide-Geographic and Long-Term Analysis of the Role of Pathogens in the Decline of Pinna nobilis to Critically Endangered Species

A mass mortality event (MME) affecting the fan mussel Pinna nobilis was first detected in Spain in autumn 2016 and spread north- and eastward through the Mediterranean Sea. Various pathogens have been blamed for contributing to the MME, with emphasis in Haplosporidium pinnae, Mycobacterium sp. and Vibrio spp. In this study, samples from 762 fan mussels (necropsies from 263 individuals, mantle biopsies from 499) of various health conditions, with wide geographic and age range, taken before and during the MME spread from various environments along Mediterranean Sea, were used to assess the role of pathogens in the MME. The number of samples processed by both histological and molecular methods was 83. The most important factor playing a main role on the onset of the mass mortality of P. nobilis throughout the Mediterranean Sea was the infection by H. pinnae. It was the only non-detected pathogen before the MME while, during MME spreading, its prevalence was higher in sick and dead individuals than in asymptomatic ones, in MME-affected areas than in non-affected sites, and it was not associated with host size, infecting both juveniles and adults. Conversely, infection with mycobacteria was independent from the period (before or during MME), from the affection of the area by MME and from the host health condition, and it was associated with host size. Gram (-) bacteria neither appeared associated with MME.En prens

Wide-Geographic and Long-Term Analysis of the Role of Pathogens in the Decline of Pinna nobilis to Critically Endangered Species

20 Pág.A mass mortality event (MME) affecting the fan mussel Pinna nobilis was first detected in Spain in autumn 2016 and spread north- and eastward through the Mediterranean Sea. Various pathogens have been blamed for contributing to the MME, with emphasis in Haplosporidium pinnae, Mycobacterium sp. and Vibrio spp. In this study, samples from 762 fan mussels (necropsies from 263 individuals, mantle biopsies from 499) of various health conditions, with wide geographic and age range, taken before and during the MME spread from various environments along Mediterranean Sea, were used to assess the role of pathogens in the MME. The number of samples processed by both histological and molecular methods was 83. The most important factor playing a main role on the onset of the mass mortality of P. nobilis throughout the Mediterranean Sea was the infection by H. pinnae. It was the only non-detected pathogen before the MME while, during MME spreading, its prevalence was higher in sick and dead individuals than in asymptomatic ones, in MME-affected areas than in non-affected sites, and it was not associated with host size, infecting both juveniles and adults. Conversely, infection with mycobacteria was independent from the period (before or during MME), from the affection of the area by MME and from the host health condition, and it was associated with host size. Gram (-) bacteria neither appeared associated with MME.This work was funded by: DG Pesca i Medi Mari (GOIB),EsMarEs (order IEO by MITECO, Spanish government), Life UFE IP-PAF INTEMARES (LIFE15 IPE ES 012) “Gestión integrada, innovadora y participativa de la Red Natura 2000 en el medio marino español,” the research project “Estado de conservación del bivalvo amenazado Pinna nobilis en el PNAC” (OAPN 024/2010), the project RECONNECT (MIS 5017160) of the Programme Interreg V-B “Balkan-Mediterranean 2014–2020.” MTES (French Government), DREAL (Direction Régionale Environnement Aménagement Logement) and Région Occitanie (France) for funding research and monitoring of Pinna.GC and PP were contracted under the INIA-CCAA cooperative research programme for postdoctoral incorporation from the Spanish National Institute for Agricultural and Food Research and Technology (INIA) (DOC INIA 8/2013 and 15/2015). MV-L was supported by a Juan de la Cierva-Incorporación postdoctoral contract (ICJI-2016-29329, MICIU Programme). ML-S and EÁ were supported by a Personal Técnico de Apoyo contract MINECO programme (PTA2015-11709-I and PTA2015-10829- I, respectively). CP and GS were supported by the project RECONNECT (MIS 5017160) financed by the Transnational Cooperation Programme Interreg V-B “Balkan-Mediterranean 2014–2020” and co-funded by the European Union and national funds of the participating countries. CP was supported by Sorbonne University.Peer reviewe

Adopting a High-Polyphenolic Diet Is Associated with an Improved Glucose Profile: Prospective Analysis within the PREDIMED-Plus Trial

Previous studies suggested that dietary polyphenols could reduce the incidence and complications of type-2 diabetes (T2D); although the evidence is still limited and inconsistent. This work analyzes whether changing to a diet with a higher polyphenolic content is associated with an improved glucose profile. At baseline, and at 1 year of follow-up visits, 5921 participants (mean age 65.0 ± 4.9, 48.2% women) who had overweight/obesity and metabolic syndrome filled out a validated 143-item semi-quantitative food frequency questionnaire (FFQ), from which polyphenol intakes were calculated. Energy-adjusted total polyphenols and subclasses were categorized in tertiles of changes. Linear mixed-effect models with random intercepts (the recruitment centers) were used to assess associations between changes in polyphenol subclasses intake and 1-year plasma glucose or glycosylated hemoglobin (HbA1c) levels. Increments in total polyphenol intake and some classes were inversely associated with better glucose levels and HbA1c after one year of follow-up. These associations were modified when the analyses were run considering diabetes status separately. To our knowledge, this is the first study to assess the relationship between changes in the intake of all polyphenolic groups and T2D-related parameters in a senior population with T2D or at high-risk of developing T2

Association Between Preexisting Versus Newly Identified Atrial Fibrillation and Outcomes of Patients With Acute Pulmonary Embolism

Background Atrial fibrillation (AF) may exist before or occur early in the course of pulmonary embolism (PE). We determined the PE outcomes based on the presence and timing of AF. Methods and Results Using the data from a multicenter PE registry, we identified 3 groups: (1) those with preexisting AF, (2) patients with new AF within 2 days from acute PE (incident AF), and (3) patients without AF. We assessed the 90-day and 1-year risk of mortality and stroke in patients with AF, compared with those without AF (reference group). Among 16 497 patients with PE, 792 had preexisting AF. These patients had increased odds of 90-day all-cause (odds ratio [OR], 2.81; 95% CI, 2.33-3.38) and PE-related mortality (OR, 2.38; 95% CI, 1.37-4.14) and increased 1-year hazard for ischemic stroke (hazard ratio, 5.48; 95% CI, 3.10-9.69) compared with those without AF. After multivariable adjustment, preexisting AF was associated with significantly increased odds of all-cause mortality (OR, 1.91; 95% CI, 1.57-2.32) but not PE-related mortality (OR, 1.50; 95% CI, 0.85-2.66). Among 16 497 patients with PE, 445 developed new incident AF within 2 days of acute PE. Incident AF was associated with increased odds of 90-day all-cause (OR, 2.28; 95% CI, 1.75-2.97) and PE-related (OR, 3.64; 95% CI, 2.01-6.59) mortality but not stroke. Findings were similar in multivariable analyses. Conclusions In patients with acute symptomatic PE, both preexisting AF and incident AF predict adverse clinical outcomes. The type of adverse outcomes may differ depending on the timing of AF onset.info:eu-repo/semantics/publishedVersio