Egalisation vectorielle pour signaux OFDM sans intervalle de garde

La modulation OFDM utilise habituellement un intervalle de garde inséré avant chaque symbole, qui permet de lutter efficacement contre la dispersion du canal. En revanche, cette approche génère une perte de débit utile pouvant atteindre 20%. On propose dans cette contribution une solution sans intervalle de garde qui met en oeuvre une égalisation vectorielle avec décision dans la boucle. La structure du récepteur repose sur 2 matrices triangulaires, dont les coefficients doivent être estimés et adaptés en fonction des variations du canal, à partir d'un ensemble de pilotes répartis à l'intérieur de chaque symbole. On décrit différents algorithmes d'estimation et on montre en particulier qu'il est nécessaire de tenir compte des dépendances existantes à l'intérieur et entre ces matrices pour atteindre des performances acceptables en terme de convergence

Changes in the flexion relaxation response induced by lumbar muscle fatigue

<p>Abstract</p> <p>Background</p> <p>The flexion relaxation phenomenon (FRP) is an interesting model to study the modulation of lumbar stability. Previous investigations have explored the effect of load, angular velocity and posture on this particular response. However, the influence of muscular fatigue on FRP parameters has not been thoroughly examined. The objective of the study is to identify the effect of erector spinae (ES) muscle fatigue and spine loading on myoelectric silence onset and cessation in healthy individuals during a flexion-extension task.</p> <p>Methods</p> <p>Twenty healthy subjects participated in this study and performed blocks of 3 complete trunk flexions under 4 different experimental conditions: no fatigue/no load (1), no fatigue/load (2), fatigue/no load(3), and fatigue/load (4). Fatigue was induced according to the Sorenson protocol, and electromyographic (EMG) power spectral analysis confirmed that muscular fatigue was adequate in each subject. Trunk and pelvis angles and surface EMG of the ES L2 and L5 were recorded during a flexion-extension task. Trunk flexion angle corresponding to the onset and cessation of myoelectric silence was then compared across the different experimental conditions using 2 × 2 repeated-measures ANOVA.</p> <p>Results</p> <p>Onset of myoelectric silence during the flexion motion appeared earlier after the fatigue task. Additionally, the cessation of myoelectric silence was observed later during the extension after the fatigue task. Statistical analysis also yielded a main effect of load, indicating a persistence of ES myoelectric activity in flexion during the load condition.</p> <p>Conclusion</p> <p>The results of this study suggest that the presence of fatigue of the ES muscles modifies the FRP. Superficial back muscle fatigue seems to induce a shift in load-sharing towards passive stabilizing structures. The loss of muscle contribution together with or without laxity in the viscoelastic tissues may have a substantial impact on post fatigue stability.</p

Review of methods used by chiropractors to determine the site for applying manipulation

Background: With the development of increasing evidence for the use of manipulation in the management of musculoskeletal conditions, there is growing interest in identifying the appropriate indications for care. Recently, attempts have been made to develop clinical prediction rules, however the validity of these clinical prediction rules remains unclear and their impact on care delivery has yet to be established. The current study was designed to evaluate the literature on the validity and reliability of the more common methods used by doctors of chiropractic to inform the choice of the site at which to apply spinal manipulation. Methods: Structured searches were conducted in Medline, PubMed, CINAHL and ICL, supported by hand searches of archives, to identify studies of the diagnostic reliability and validity of common methods used to identify the site of treatment application. To be included, studies were to present original data from studies of human subjects and be designed to address the region or location of care delivery. Only English language manuscripts from peer-reviewed journals were included. The quality of evidence was ranked using QUADAS for validity and QAREL for reliability, as appropriate. Data were extracted and synthesized, and were evaluated in terms of strength of evidence and the degree to which the evidence was favourable for clinical use of the method under investigation. Results: A total of 2594 titles were screened from which 201 articles met all inclusion criteria. The spectrum of manuscript quality was quite broad, as was the degree to which the evidence favoured clinical application of the diagnostic methods reviewed. The most convincing favourable evidence was for methods which confirmed or provoked pain at a specific spinal segmental level or region. There was also high quality evidence supporting the use, with limitations, of static and motion palpation, and measures of leg length inequality. Evidence of mixed quality supported the use, with limitations, of postural evaluation. The evidence was unclear on the applicability of measures of stiffness and the use of spinal x-rays. The evidence was of mixed quality, but unfavourable for the use of manual muscle testing, skin conductance, surface electromyography and skin temperature measurement. Conclusions: A considerable range of methods is in use for determining where in the spine to administer spinal manipulation. The currently published evidence falls across a spectrum ranging from strongly favourable to strongly unfavourable in regard to using these methods. In general, the stronger and more favourable evidence is for those procedures which take a direct measure of the presumptive site of care– methods involving pain provocation upon palpation or localized tissue examination. Procedures which involve some indirect assessment for identifying the manipulable lesion of the spine–such as skin conductance or thermography–tend not to be supported by the available evidence.https://doi.org/10.1186/2045-709X-21-3

The sad story of Agaricus rhacodes/rachodes: Why would an orthographical error with limited current use become accepted through conservation?

The spelling rachodes used by Vittadini in 1833 for a new species of Agaricus has often been considered a correct- able orthographical error for rhacodes. Use of the original spelling has however been occasional and was recently promoted by Vellinga and coworkers. The arguments used to support this practice, especially developed by Vellinga and Pennycook, when proposing conservation of rachodes in 2010 are refuted. It is shown that it is philologically illogical to assume an adjective rachodes could have been created, while the existing rhacodes was obviously meant. The use of the two spellings presented by Vellinga and Pennycook is shown to be incomplete. The conclusion is that rachodes should be corrected under Art. 60.1 to rhacodes, the spelling used for every other organism with that epithet, and that this correction is far more universal, including outside Europe, than the usage claimed for justifying a conservation of rachodes. The expenditure of energy caused by the Vellinga and Pennycook proposal shows that new ways to handle orthography of scientific names should be explored

Studies of marine epiphytic algae, Calvi Corsica. I. Determination of minimal sampling areas for microscopic algal epiphytes

Minimal sampling areas have been determined for marine Bangiophyceae and Cyanophyceaee epiphytic on Cladophora prolifera and Halopteris scoparia in Calvi, Corsica. This was done by observing the stabilization of species/area curves and of qualitative and quantitative similarity coefficients between samples of increasing size. For Cyanophyceae (studied only on Cladophora) the minimal sampling area is in the order of 15 - 38 mm2, depending on the method used. The sampling area is smaller when the quantitative similarity coefficient is used, apparently because of the rather homogeneous distribution of a few abundant taxa. For the same reason the quantitative similarity coefficient stabilizes at a high value (75 %). For Bangiophyceae on Cladophora, the area is of the order of 7 - 10 mm2, but a larger area is necessary for the quantitative than for the qualitative coefficient. The stabilized value of the quantitative coefficient is relatively low (66 %), despite the fact that the qualitative coefficient reaches 94 %. On Halopteris, by counting only on medium sized ramifications (about 100 um in diameter), one can use a sampling area as low as 0.1 - 0.5 mm2 and obtain a qualitative similarity coefficient of 100 % and a quantitative one of 80 %. This study demonstrates that techniques used for macrophytic vegetation can be applied with success to microscopic epiphytes

Arcangeliella stephensii

Fung

Establishing a check-list of "Macromycetes": the european "Gasteromycetes"

Before writing up a flora for a given area or a revision of a given taxonomic group, establishing a check-list is a useful preliminary work. For fungi, floras are not frequent and the necessity of check-lists even more urgent. Taxonomy of fungi is however less advanced than that of phanerogams because for many species fruiting is irregular, all characters do not preserve well in the herbarium and good microscopio observations are necessary. This creates problems at three levels in the establishment of a mycologica! check-list. Those levels are the choice of a given taxonomic framework, that of nomenclature and that of deciding which records should be accepted. Those problems are discussed and illustrated by examples met in the preparation of a check-list of european Gasteromycetes which includes some 250 species.Antes de escribir una flora para un área determinada o una revisión de algún grupo taxonómico, la preparación de un catálogo es una labor preliminar útil. Para los hongos, las floras no son frecuentes, y la necesidad de catálogos es aún más urgente. La taxonomía de hongos, sin embargo, está menos avanzada que la de fanerógamas porque en muchas especies la fructificación es irregular, no todos los caracteres se conservan bien en el herbario y hacen falta buenas observaciones microscópicas. Esto crea problemas a tres niveles para establecer un catálogo micológico: la elección de un marco taxonómico determinado, la nomenclatura, y la decisión acerca de qué citas deben ser aceptadas. Estos problemas se comentan e ilustran con ejemplos ocurridos durante la preparación de un catálogo de Gasteromycetes europeos que comprende unas 250 especies

UN TULOSTOMA (GASTÉROMYCÈTES) NOUVEAU POUR LA FRANCE : T. KOTLABAE POUZAR DANS LES PYRÉNÉES-ORIENTALES

International audienceTulostoma kotlabae Pouzar, qui n'avait été trouvé jusqu'ici qu'en Tchécoslovaquie, a été découvert à Banyuls-sur-Mer (Pyrénées-Orientales). A cette occasion, du matériel original de cette espèce et de T. moravecii,T. albicans, T. jourdanii et T. barlae a été revu et fait l'objet d'un commentaire

What is Polyporus burkillii Lloyd and how should it be spelled?

A study of the holotype (BPI) and isotype (SING) of Polyporus burkillii Lloyd shows that this ma- terial is homogeneous and does not belong to a species of the genus Polyporus as assumed by Ryvarden (1990) and Hattori (2001), but that Corner (1987) was correct in combining the name in Microporellus. At the specific level Corner however misinterpreted the taxon which should be in- cluded in M. clemensiae (Murrill) Ryvarden s.l. Further studies of Microporellus are needed and may show that this is a good species antedating other infudibuliform ones, especially M. inusitatus (Lloyd) Corner. The spelling of the name is discussed, the conclusion being that it should be corrected to Polyporus burkilliae. Microporellus burkillii (Lloyd) Corner ss. Corner is a good species that appar- ently lacks a name