Laser Noise Reduction in Air

Fluctuations of the white-light supercontinuum produced by ultrashort laser pulses in selfguided filaments (spatio-temporal solitons) in air are investigated. We demonstrate that correlations exist within the white-light supercontinuum, and that they can be used to significantly reduce the laser intensity noise by filtering the spectrum. More precisely, the fundamental wavelength is anticorrelated with the wings of the continuum, while conjugated wavelength pairs on both sides of the continuum are strongly correlated. Spectral filtering of the continuum reduces the laser intensity noise by 1.2 dB, showing that fluctuations are rejected to the edges of the spectrum.Comment: 8 page

High current permanent discharges in air induced by femtosecond laser filamentation

International audienceFilaments created in air by an intense femtosecond laser pulse in the presence of an electric field generate a highly conductive permanent plasma column

Revival of femtosecond laser plasma filaments in air by a nanosecond laser

International audienceShort lived plasma channels generated through filamentation of femtosecond laser pulses in air can be revived after several milliseconds by a delayed nanosecond pulse. Electrons initially ionized from oxygen molecules and subsequently captured by neutral oxygen molecules provide the long-lived reservoir of low affinity allowing this process. A Bessel-like nanosecond-duration laser beam can easily detach these weakly bound electrons and multiply them in an avalanche process. We have experimentally demonstrated such revivals over a channel length of 50 cm by focusing the nanosecond laser with an axicon

Use of Antiviral Drugs to Reduce Household Transmission of Pandemic (H1N1) 2009, United Kingdom1

TOC Summary: Early treatment of primary case-patients and prophylaxis of household contacts provides effective protection

A biobank of pediatric patient-derived-xenograft models in cancer precision medicine trial MAPPYACTS for relapsed and refractory tumors

Pediatric patients with recurrent and refractory cancers are in most need for new treatments. This study developed patient-derived-xenograft (PDX) models within the European MAPPYACTS cancer precision medicine trial (NCT02613962). To date, 131 PDX models were established following heterotopical and/or orthotopical implantation in immunocompromised mice: 76 sarcomas, 25 other solid tumors, 12 central nervous system tumors, 15 acute leukemias, and 3 lymphomas. PDX establishment rate was 43%. Histology, whole exome and RNA sequencing revealed a high concordance with the primary patient's tumor profile, human leukocyte-antigen characteristics and specific metabolic pathway signatures. A detailed patient molecular characterization, including specific mutations prioritized in the clinical molecular tumor boards are provided. Ninety models were shared with the IMI2 ITCC Pediatric Preclinical Proof-of-concept Platform (IMI2 ITCC-P4) for further exploitation. This PDX biobank of unique recurrent childhood cancers provides an essential support for basic and translational research and treatments development in advanced pediatric malignancies

A biobank of pediatric patient-derived-xenograft models in cancer precision medicine trial MAPPYACTS for relapsed and refractory tumors

Pediatric patients with recurrent and refractory cancers are in most need for new treatments. This study developed patient-derived-xenograft (PDX) models within the European MAPPYACTS cancer precision medicine trial (NCT02613962). To date, 131 PDX models were established following heterotopical and/or orthotopical implantation in immunocompromised mice: 76 sarcomas, 25 other solid tumors, 12 central nervous system tumors, 15 acute leukemias, and 3 lymphomas. PDX establishment rate was 43%. Histology, whole exome and RNA sequencing revealed a high concordance with the primary patient's tumor profile, human leukocyte-antigen characteristics and specific metabolic pathway signatures. A detailed patient molecular characterization, including specific mutations prioritized in the clinical molecular tumor boards are provided. Ninety models were shared with the IMI2 ITCC Pediatric Preclinical Proof-of-concept Platform (IMI2 ITCC-P4) for further exploitation. This PDX biobank of unique recurrent childhood cancers provides an essential support for basic and translational research and treatments development in advanced pediatric malignancies

Correction des phases spectrale et temporelle pour les lasers ultra-intenses.

The production of ultra-short pulses and ultra-intense of great interest exploration of the physics of laser-matter interaction. Recent development years oscillator generating pulses shorter and shorter combined with technique of chirped amplification yielded powers of few hundred terawatt. The next generation of power line should produce pulses with a power order of tens of petawatts. Such channel could penetrate the Laser Integration Line (LIL) at CESTA in Bordeaux. The PW laser sizing study in the LIL has shown the need to correct the phases spectral and temporal. The objective of this thesis is the correction of the spectral phase using a modulator temporal phase for pulses of relatively low spectral width (a few nanometers) centered around 1.053 mu.m and temporally highly stretched. Specificity pulses required a particular work of adapting the methods of absolute measurement and spectral phase modulation. Controlling the spectral phase of pulses allows Indeed not only the correction of phase defects to compress the pulse frequency drift but also the temporal form of these pulses. Setting instead of the analogy between the temporal and spatial domains has given all the achievements of space to analyze the pulse spectral phase. We also formal correspondence of the phase modulation between the time domain and the spectral range for highly stretched pulses, using Theorem phase stationary. We present in this manuscript, the experimental results of measurements of spectral phase and spectral phase correction. An extension to the correction of the temporal phase is proposed: the correction effects Nonlinear directly in the time domain (using the phase modulator time). We present results of numerical simulations of the correction time phase to improve performance by a factor of three power LIL facility of the type.La production d'impulsions ultra-courtes et ultra-intenses présente un grand intérêt pour l'exploration de la physique de l'interaction laser-matière. Le développement ces dernières années d'oscillateurs engendrant des impulsions de plus en plus courtes combinées à une technique de l'amplification à dérive de fréquence a permis d'obtenir des puissances de quelques centaines de térawatts. La prochaine génération de chaîne de puissance devrait produire des impulsions ayant une puissance de l'ordre de la dizaine de pétawatts. Une telle chaîne pourrait s'implanter sur la Ligne d'Intégration Laser (LIL) au CESTA à Bordeaux. Le dimensionnement du laser PW en étude sur la LIL a montré la nécessité de corriger les phases spectrale et temporelle. L'objectif de la thèse est la correction de la phase spectrale en utilisant un modulateur de phase temporelle pour des impulsions de relativement faible largeur spectrale (quelques nanomètres) centrées autour de 1,053 µm et fortement étirées temporellement. La spécificité des impulsions a nécessité un travail particulier d'adaptation des méthodes de mesure absolue et de modulation de phase spectrale. La maîtrise de la phase spectrale des impulsions permet en effet non seulement la correction des défauts de phase pour comprimer les impulsions à dérive de fréquence mais aussi la mise en forme temporelle de ces impulsions. La mise en place de l'analogie entre les domaines temporel et spatial a permis de bénéficier de tout l'acquis du domaine spatial pour analyser la phase spectrale de l'impulsion. Nous avons aussi formalisé la correspondance de la modulation de la phase entre le domaine temporel et le domaine spectral pour des impulsions fortement étirées, en utilisant le théorème de la phase stationnaire. Nous présentons dans ce manuscrit les résultats expérimentaux de mesures de la phase spectrale et de la correction de la phase spectrale. Une extension à la correction de la phase temporelle est proposée : la correction des effets non linéaires directement dans le domaine temporel (en utilisant le modulateur de phase temporelle). Nous présentons les résultats des simulations numériques de la correction de la phase temporelle permettant d'améliorer les performances d'un facteur trois en puissance sur une installation du type LIL

CORRECTION DES PHASES SPECTRALE ET TEMPORELLE POUR LES LASERS ULTRA-INTENSES

LA PRODUCTION D'IMPULSIONS ULTRA-COURTES ET ULTRA-INTENSES PRESENTE UN GRAND INTERET POUR L'EXPLORATION DE LA PHYSIQUE DE L'INTERACTION LASER-MATIERE. LES CHAINES DE PUISSANCE ACTUELLES DELIVRENT DES IMPULSIONS DE QUELQUES CENTAINES DE TERAWATTS ; LA PROCHAINE GENERATION DE L'ORDRE DE LA DIZAINE DE PETAWATTS. UNE TELLE CHAINE POURRAIT S'IMPLANTER SUR LA LIGNE D'INTEGRATION LASER (LIL) AU CESTA A BORDEAUX. LE DIMENSIONNEMENT DU LASER PW EN ETUDE SUR LA LIL A MONTRE LA NECESSITE DE CORRIGER LES PHASES SPECTRALE ET TEMPORELLE. L'OBJECTIF DE CETTE THESE EST LA CORRECTION DE LA PHASE SPECTRALE EN UTILISANT UN MODULATEUR DE PHASE TEMPORELLE POUR DES IMPULSIONS DE RELATIVEMENT FAIBLE LARGEUR SPECTRALE (QUELQUES MANOMETRES) CENTREES AUTOUR DE 1,053 M ET FORTEMENT ETIREES TEMPORELLEMENT. LA SPECIFICITE DES IMPULSIONS A NECESSITE UN TRAVAIL D'ADAPTATION DES METHODES DE MESURE ABSOLUE ET DE MODULATION DE PHASE SPECTRALE. LA MAITRISE DE LA PHASE SPECTRALE PERMET EN EFFET NON SEULEMENT LA CORRECTION DES DEFAUTS DE PHASE POUR COMPRIMER LES IMPULSIONS A DERIVE DE FREQUENCE MAIS AUSSI LEUR MISE EN FORME TEMPORELLE. LA MISE EN PLACE DE L'ANALOGIE ENTRE LES DOMAINES TEMPOREL ET SPATIAL A PERMIS DE BENEFICIER DE TOUT L'ACQUIS DU DOMAINE SPATIAL POUR ANALYSER LA PHASE SPECTRALE DE L'IMPULSION. NOUS AVONS AUSSI FORMALISE LA CORRESPONDANCE ENTRE LA MODULATION DE LA PHASE TEMPORELLE ET SPECTRALE POUR DES IMPULSIONS FORTEMENT ETIREES, EN UTILISANT LE THEOREME DE LA PHASE STATIONNAIRE. NOUS PRESENTONS DANS CE MANUSCRIT LES RESULTATS EXPERIMENTAUX DE MESURES ET DE CORRECTION DE LA PHASE SPECTRALE. UNE EXTENSION A LA CORRECTION DE LA PHASE TEMPORELLE EST PROPOSEE : LA CORRECTION DES EFFETS NON LINEAIRES DIRECTEMENT DANS LE DOMAINE TEMPOREL (EN UTILISANT LE MODULATEUR DE PHASE TEMPORELLE). NOUS PRESENTONS LES RESULTATS DES SIMULATIONS NUMERIQUES DE LA CORRECTION DE LA PHASE TEMPORELLE PERMETTANT D'AMELIORER LES PERFORMANCES D'UN FACTEUR TROIS EN PUISSANCE SUR UNE INSTALLATION TYPE LIL.PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

Variations et liens fonctionnels entre les compartiments épigés et endogés le long d’un gradient d’inondation

International audienc

Data from: Shifts and linkages of functional diversity between above- and below-ground compartments along a flooding gradient

Trait-based approaches have the potential to reveal general and predictive relationships between organisms and ecosystem functioning. However, the mechanisms underlying the functional structure of communities are still unclear. Within terrestrial ecosystems, several studies have shown that many ecological processes are controlled by the interacting above- and below-ground compartments. However, few studies have used traits to reveal the functional relationships between plants and soil fauna. Mostly, research combining plants and soil fauna solely used the traits of one assemblage in predictive studies. Above-ground (plants) and below-ground (Collembola) compartments were sampled over a flooding gradient in northern France along the Seine River. First, we measured the effect of flooding on functional and taxonomic assembly within both communities. We then considered the linkages between plant and Collembolan species richness, community traits and assessed whether traits of both compartments converged at high flooding intensity (abiotic filtering) and diverged when this constraint is released (biotic filtering). Species richness of both taxa followed the same bell-shaped pattern along the gradient, while a similar significant pattern of functional richness was only observed for plants. Further analyses revealed a progressive shift from trait convergence to divergence for plants, but not for Collembola, as constraints intensity decreased. Instead, our results highlighted that Collembola traits were mainly linked to the variations in plant traits. This leads, within Collembola assemblages, to convergence of a subset of perception and habitat-related traits for which the relationship with plant traits was assessed. Synthesis. Using a trait-based approach, our study highlighted that functional relationships occur between above- and below-ground compartments. We underlined that functional composition of plant communities plays a key role in structuring Collembola assemblages in addition to the role of abiotic variables. Our study clearly shows that functional diversity provides a new approach to link the above- and below-ground compartments and might, therefore, be further considered when studying ecological processes at the interface between both compartments