Observing bulk diamond spin coherence in high-purity nanodiamonds

Nitrogen-vacancy centres (NVs) in diamond are attractive for research straddling quantum information science and nanoscale magnetometry and thermometry. While ultrapure bulk diamond NVs sustain the longest spin coherence times among optically accessible spins, nanodiamond NVs display persistently poor spin coherence. Here we introduce high-purity nanodiamonds accommodating record-long NV coherence times, >60 us, observed via universal dynamical decoupling. We show that the main contribution to decoherence comes from nearby nitrogen impurities rather than surface states. We protect the NV spin free precession, essential to DC magnetometry, by driving solely these impurities into the motional narrowing regime. This extends the NV free induction decay time from 440 ns, longer than that in type Ib bulk diamond, to 1.27 us, which is comparable to that in type IIa (impurity-free) diamond. These properties allow the simultaneous exploitation of both high sensitivity and nanometre resolution in diamond-based emergent quantum technologies.Comment: Additional data and analysis in PDF format is available for download at the publications section of http://www.amop.phy.cam.ac.uk/amop-m

Identifying cancer-causing noncoding RNAs

To circumvent the dependency on prediction models, we developed a microRNA-screen-based assay to establish links between cellular phenotypes and microRNAs (miRNAs). To this end, a miRNA expression library (miR-Lib) was built consisting of 300 annotated miRNAs and around 100 candidate miRNAs. These miRNA 'minigenes' were cloned from genomic DNA of human cells and inserted in a specially engineered retroviral expression vector. This vector, named miR-Vec, is a modified murine stem cell virus (pMSCV) vector, with the expression of the miRNA minigenes under the control of the CMV pol II promoter. The vast majority of naturally transcribed miRNA genes are known to be expressed by pol II promoters. In parallel with the miRNA library, a corresponding microarray was developed (miR-Array) containing DNA spots of the miRNA minigenes from the library. By combining the miRNA library and microarray tools, we designed and performed three distinct functional genetic approaches to identify cancerous microRNAs.UBL - phd migration 201

Élaboration et validation de critères de transfert des traumatisés majeurs vers les centres tertiaires de traumatologie

Introduction: L’organisation des réseaux de traumatologie a amélioré la survie des traumatisés majeurs. Toutefois, la littérature actuelle est imprécise quant aux indications de transfert vers les centres tertiaires de traumatologie. Objectifs : 1) Élaborer un consensus de critères de transfert des traumatisés majeurs en centre tertiaire, 2) évaluer l’association entre la présence des critères et la gravité des cas, 3) démontrer la validité prédictive de ces indications de transfert en centre tertiaire concernant les TCC. Méthode : Un consensus a été élaboré à l’aide de la méthode Delphi par un groupe d’experts multidisciplinaire provenant de centres primaires, secondaires et tertiaires. Toutes nos analyses ont été effectuées à l’aide d’un échantillon tiré du Registre des Traumatismes du Québec et comportant les données de 146 630 patients (1998-2008). Résultats : Douze situations cliniques ont été retenues par les experts. Pour la population admise directement en centre tertiaire, le risque ajusté de décès, d’admission à l’unité des soins intensifs et de complications majeures [IC 95 %] pour les patients répondant à l’un ou l’autre des critères du consensus est supérieur à celui des patients ne présentant aucun critère, soit respectivement RR = 6.2 [5.6-6.8], 3.5 [3.4-3.7] et 2.8 [2.7-3.0]. De plus, pour les patients ayant subi un TCC et initialement amenés dans un centre primaire ou secondaire, on a observé que la cote de décès [IC 95 %] des patients transférés est inférieure à celle des non transférés pour les situations cliniques suivantes: 1) score < 9 sur l’échelle de coma de Glasgow, RC = 0.18 [0.06-0.52], 2) fracture ouverte ou enfoncée du crâne, RC = 0.21 [0.06-0.71], 3) altération de l’état de conscience avec tomodensitométrie cérébrale anormale, RC = 0.35 [0.15-0.85], et 4) hématome sous-dural, épidural ou hémorragie intracérébrale, RC = 0.53 [0.36-0.79]. Conclusion : Des critères de transfert en centre tertiaire de traumatologie ont été élaborés et validés. Les victimes d’un TCC répondant à l’un des critères ci-haut mentionnés présentent un meilleur pronostic s’ils sont transférés en centre tertiaire. Une validation prospective et une mesure d’impact pourront être réalisées si ces critères sont implantés au sein du réseau de traumatologie.Introduction: Trauma care systems have improved the survival of major trauma patients. However, the current literature is unclear about the indications for these patients to be transferred to tertiary trauma centers. Objectives: 1) To develop consensus criteria for the transfer of major trauma, 2) to assess the association between the presence of criteria and severity of cases and 3) to demonstrate the predictive validity of the criteria for patients with traumatic brain injury (TBI). Methods: A Delphi consultation with experts led to a multidisciplinary consensus criteria for transfer to tertiary centers. The panel was composed of emergency physicians, surgeons, intensivists and neurosurgeons from primary, secondary and tertiary trauma center. All analyzes were performed using the Quebec Trauma Registry (QTR), with the data of 146 630 patients (1998-2008). Results: Twelve clinical situations were selected by the panel. For patients admitted directly to a tertiary trauma center, the adjusted risk of death, admission to intensive care unit and major complications [IC 95 %] among patients meeting one or other of the consensus criteria was higher than that of patients with no criteria, respectively RR = 6.2 [5.6-6.8], 3.5 [3.4-3.7] et 2.8 [2.7-3.0]. In addition, in a population of patients sustaining a traumatic brain injury (TBI) and initially transported to a primary or secondary center, it was observed that the adjusted odds of death [IC 95 %] for patients transferred was lower than that of non-transferred patients for the following clinical situations: 1) score < 9 on the Glasgow Coma Scale (GCS), OR = 0.18 [0.06-0.52], 2) open or depressed skull fracture, OR = 0.21 [0.06-0.71], 3) altered state of consciousness with abnormal CT scan, OR = 0.35 [0.15-0.85] and 4) subdural or epidural hematoma, or intracerebral hemorrhage, OR = 0.53 [0.36-0.79]. Conclusion: Criteria for transfer to tertiary trauma center were developed and validated. TBI victims with anyone of the proposed consensus criteria have a better prognosis if they are transferred to a tertiary trauma center. A prospective validation and an impact measurement will be possible if these criteria are implemented in a trauma system

Sensitivity And Out-Of-Sample Error in Continuous Time Data Assimilation

Data assimilation refers to the problem of finding trajectories of a prescribed dynamical model in such a way that the output of the model (usually some function of the model states) follows a given time series of observations. Typically though, these two requirements cannot both be met at the same time--tracking the observations is not possible without the trajectory deviating from the proposed model equations, while adherence to the model requires deviations from the observations. Thus, data assimilation faces a trade-off. In this contribution, the sensitivity of the data assimilation with respect to perturbations in the observations is identified as the parameter which controls the trade-off. A relation between the sensitivity and the out-of-sample error is established which allows to calculate the latter under operational conditions. A minimum out-of-sample error is proposed as a criterion to set an appropriate sensitivity and to settle the discussed trade-off. Two approaches to data assimilation are considered, namely variational data assimilation and Newtonian nudging, aka synchronisation. Numerical examples demonstrate the feasibility of the approach.Comment: submitted to Quarterly Journal of the Royal Meteorological Societ