Efficient Linear Scaling Approach for Computing the Kubo Hall Conductivity

We report an order-N approach to compute the Kubo Hall conductivity for disorderd two-dimensional systems reaching tens of millions of orbitals, and realistic values of the applied external magnetic fields (as low as a few Tesla). A time-evolution scheme is employed to evaluate the Hall conductivity $\sigma_{xy}$ using a wavepacket propagation method and a continued fraction expansion for the computation of diagonal and off-diagonal matrix elements of the Green functions. The validity of the method is demonstrated by comparison of results with brute-force diagonalization of the Kubo formula, using (disordered) graphene as system of study. This approach to mesoscopic system sizes is opening an unprecedented perspective for so-called reverse engineering in which the available experimental transport data are used to get a deeper understanding of the microscopic structure of the samples. Besides, this will not only allow addressing subtle issues in terms of resistance standardization of large scale materials (such as wafer scale polycrystalline graphene), but will also enable the discovery of new quantum transport phenomena in complex two-dimensional materials, out of reach with classical methods.Comment: submitted PRB pape

Unconventional Features in the Quantum Hall Regime of Disordered Graphene: Percolating Impurity States and Hall Conductance Quantization

We report on the formation of critical states in disordered graphene, at the origin of variable and unconventional transport properties in the quantum Hall regime, such as a zero-energy Hall conductance plateau in the absence of an energy bandgap and Landau level degeneracy breaking. By using efficient real-space transport methodologies, we compute both the dissipative and Hall conductivities of large size graphene sheets with random distribution of model single and double vacancies. By analyzing the scaling of transport coefficients with defect density, system size and magnetic length, we elucidate the origin of anomalous quantum Hall features as magnetic-field dependent impurity states, which percolate at some critical energies. These findings shed light on unidentified states and quantum transport anomalies reported experimentally.Comment: 7 pages, 7 figures. Accepted in PR

Real-world research and its importance in respiratory medicine

Peer reviewedPublisher PD

Magnetoresistance and Magnetic Ordering Fingerprints in Hydrogenated Graphene

Spin-dependent features in the conductivity of graphene, chemically modified by a random distribution of hydrogen adatoms, are explored theoretically. The spin effects are taken into account using a mean-field self-consistent Hubbard model derived from first-principles calculations. A Kubo-Greenwood transport methodology is used to compute the spin-dependent transport fingerprints of weakly hydrogenated graphene-based systems with realistic sizes. Conductivity responses are obtained for paramagnetic, antiferromagnetic, or ferromagnetic macroscopic states, constructed from the mean-field solutions obtained for small graphene supercells. Magnetoresistance signals up to $\sim 7$ are calculated for hydrogen densities around 0.25%. These theoretical results could serve as guidance for experimental observation of induced magnetism in graphene.Comment: 4 pages, 4 figure

How to Combine Text-Mining Methods to Validate Induced Verb-Object Relations?

International audienceThis paper describes methods using Natural Language Processing approaches to extract and validate induced syntactic relations (here restricted to the Verb-Object relation). These methods use a syntactic parser and a semantic closeness measure to extract such relations. Then, their validation is based on two different techniques: A Web Validation system on one part, then a Semantic-Vectorbased approach, and finally different combinations of both techniques in order to rank induced Verb-Object relations. The Semantic Vector approach is a Roget-based method which computes a syntactic relation as a vector. Web Validation uses a search engine to determine the relevance of a syntactic relation according to its popularity. An experimental protocol is set up to judge automatically the relevance of the sorted induced relations. We finally apply our approach on a French corpus of news by using ROC Curves to evaluate the results

Clinical practice guidelines: Medical follow-up of patients with asthma—Adults and adolescents

SummaryThe follow-up of patients with asthma should focus on asthma control (disease course over a number of weeks)→ There are 3 levels of asthma control•Acceptable:All control criteria (Table 1 below) are met•Unacceptable:One or more criteria are not met•Optimal:All control criteria are normal or, in a patient with acceptable control, the best compromise has been achieved between degree of control, acceptance of treatment and possible side effectsTable 1 Criteria defining acceptable asthma control.CriterionValue or frequency*Day-time symptoms<4 days/weekNight-time symptoms<1 night/weekPhysical activityNormalExacerbationsMild, infrequentAbsence from work or schoolNoneUse of short-acting β2-agonists<4 doses/weekFEV1 or PEF>85% of personal bestPEF diurnal variation (optional)<15%*Mean during control assessment period (1 week–3 months).FEV: forced expiratory volume; PEF: peak expiratory flow.→ Follow-up includes monitoring of treatment side effects and adherence.→ Treatment should be adjusted to level of control and current long-term therapy.•If control is unacceptable:○Check: that the disease is asthma, adherence, correct use of inhalation devices.○Look for and treat: aggravating factors, concomitant disease, specific clinical forms.○Adjust long-term therapy (see Table 2 below) in steps of 1–3 months.•If control is acceptable or optimal:○Find the minimum effective treatment to maintain at least acceptable and ideally optimal control. Each step should last 3 months.Table 2 Adjusting long-term therapy if control is unacceptable.Current therapyNew treatmentaOption 1Option 2No ICSAverage-dose ICSAverage ICS dose+AMbPatients on ICS onlyLow- or average-dose ICSAdd AMIncrease ICS dose with or without AMHigh-dose ICSAdd AMPatients on ICS and additional medication (AM)Low dose of ICS (+1 AM)Increase ICS doseAverage dose of ICS (+1 AM)Increase ICS doseAdd second AM with or without increasing ICS doseHeavy dose of ICS (+1 AM)Add second AMOral corticosteroidscHeavy dose of ICS (+2 AMs)Oral corticosteroidscAdd third AMaThe choice between options will depend on symptom frequency and respiratory function (particularly post-bronchodilator FEV1).bAdditional medication (AM) covers long-acting β2-agonists, cysteinyl-leukotriene receptor antagonists, theophylline and its derivatives (bamiphylline).cOral corticosteroids are rarely used in adolescents.→ Frequency of follow-up visits (V) and lung function tests (LFTs) according to the dose of inhaled corticosteroids (ICS) needed for acceptable control (see Table 3 below)Table 3 Frequency of follow-up visits and LFTs.ICS doseV (months)LFT (months)High33–6Low or average66–12None1212 or +Low, average and high daily dose of ICS (μg/day) in adults.Low doseAverage doseHigh doseBeclomethasonea<500500–1000>1000Budesonide<400400–800>800Fluticasone<250250–500>500aDose should be halved for QVAR® and NEXXAIR®SynopsisTitleMedical follow-up of patients with asthma—adults and adolescentsPublication dateSeptember 2004Requested byFrench National Health DirectorateProduced byAnaes—French National Agency for Accreditation and Evaluation in Healthcare (Guidelines Department)Intended forAll health professionals who manage patients with asthmaAssessment method•Systematic review of the literature (with evidence levels)•Discussion among members of an ad hoc working group•External validation by peer reviewers (see Anaes guide “Recommandations pour la pratique clinique—base méthodologique pour leur réalisation en France—1999”)ObjectivesAddress the practical aspects of long-term medical follow-up of patients with asthma (adults and adolescents only)Literature searchJanuary 1997–December 20032957 articles identified of which 696 analysedEconomic studyNoneAnaes project leader(s)Dr. Philippe Martel (Department head: Dr. Patrice Dosquet)(Literature search: Emmanuelle Blondet with the help of Maud Lefèvre (Department head: Rabia Bazi); secretarial work: Elodie Sallez)Authors of draft reportDr. Hugues Morel, chest physician, DinanDr. Nicolas Roche, chest physician, ParisCollaborations and participants•Learned societies•Steering committee•Working group (Chair: Professor Philippe Godard, chest physician/allergologist, Montpellier)•Peer reviewers(Appendix A)Internal validationAnaes Scientific Council (Referees: Professor Bruno Housset, chest physician, Créteil; Michel Paparemborde, Head of physiotherapy training college, Lille)Validated on September 2, 2004Other Anaes publications on the topicMedical follow-up is complemented by ongoing patient education, which is dealt with in the guidelines “Therapeutic education for patients with asthma—adults and adolescents” (Anaes 2001

An Embedded Gait Analysis System for CNS Injury Patients

Clinical evaluation of CNS injury patients before and after treatment is an essential step in gait rehabilitation. Medical care of gait disturbance for stroke patients is based on different treatments based on clinical and functional evaluations. Evaluation of gait aims at characterizing the motor performance to provide clinicians with information on the patient’s organizational or performance status and to allow them to consider the most appropriate treatment options. A 3D instrumented gait analysis system allows quantification of several parameters at each instant of walking but does not represent gait in daily life conditions. The absence of devices usable in daily life situation constitutes a lack pointed out by clinical practitioners and is at the origin of this work. In the following are described the design and implementation of a wireless embedded system for the collection of spatiotemporal parameters of pathological gait in everyday life. Algorithms estimate joint angles, step length, and gait events and automatically partition data into gait cycles. Experiments have been carried out to accurately evaluate the joint angles, the precision of sensor synchronization, the precision of gait event detection, and the robustness in the case of pathological walk. Comparisons with references given by the 3D instrumented gait analysis system are detailed

SequencesViewer : comment rendre accessible des motifs séquentiels de gènes trop nombreux ?

National audienceLes techniques d'extraction de connaissances ppliquées aux gros volumes de données, issus de l'analyse de puces ADN, permettent de découvrir des connaissances jusqu'alors inconnues. Or, ces techniques produisent de très nombreux résultats, difficilement exploitables par les experts. Nous proposons un outil dédié à l'accompagnement de ces experts dans l'appropriation et l'exploitation de ces résultats. Cet outil est basé sur trois techniques de visualisation (nuages, systèmes solaire et treemap) qui permettent aux biologistes d'appréhender de grandes quantités de motifs séquentiels (séquences ordonnées de gènes)