Clustering-based Redshift Estimation: Comparison to Spectroscopic Redshifts

We investigate the potential and accuracy of clustering-based redshift estimation using the method proposed by M\'enard et al. (2013). This technique enables the inference of redshift distributions from measurements of the spatial clustering of arbitrary sources, using a set of reference objects for which redshifts are known. We apply it to a sample of spectroscopic galaxies from the Sloan Digital Sky Survey and show that, after carefully controlling the sampling efficiency over the sky, we can estimate redshift distributions with high accuracy. Probing the full colour space of the SDSS galaxies, we show that we can recover the corresponding mean redshifts with an accuracy ranging from $\delta$z=0.001 to 0.01. We indicate that this mapping can be used to infer the redshift probability distribution of a single galaxy. We show how the lack of information on the galaxy bias limits the accuracy of the inference and show comparisons between clustering redshifts and photometric redshifts for this dataset. This analysis demonstrates, using real data, that clustering-based redshift inference provides a powerful data-driven technique to explore the redshift distribution of arbitrary datasets, without any prior knowledge on the spectral energy distribution of the sources.Comment: 13 pages. Submitted to MNRAS. Comments welcom

Surface induced magnetization reversal of MnP nanoclusters embedded in GaP

We investigate the quasi-static magnetic behavior of ensembles of non-interacting ferromagnetic nanoparticles consisting of MnP nanoclusters embedded in GaP(001) epilayers grown at 600, 650 and 700{\deg}C. We use a phenomenological model, in which surface effects are included, to reproduce the experimental hysteresis curves measured as a function of temperature (120-260 K) and direction of the applied field. The slope of the hysteresis curve during magnetization reversal is determined by the MnP nanoclusters size distribution, which is a function of the growth temperature. Our results show that the coercive field is very sensitive to the strength of the surface anisotropy, which reduces the energy barrier between the two states of opposite magnetization. Notably, this reduction in the energy barrier increases by a factor of 3 as the sample temperature is lowered from 260 to 120 K.Comment: 7 pages, 5 figure

A diffuse interface approach for disperse two-phase flows involving dual-scale kinematics of droplet deformation based on geometrical variables

The purpose of this contribution is to derive a reduced-order two-phase flow model in- cluding interface subscale modeling through geometrical variables based on Stationary Action Principle (SAP) and Second Principle of Thermodynamics in the spirit of [6, 14]. The derivation is conducted in the disperse phase regime for the sake of clarity but the resulting paradigm can be used in a more general framework. One key issue is the definition of the proper potential and kinetic energies in the Lagrangian of the system based on geometrical variables (Interface area density, mean and Gauss curvatures...), which will drive the subscale kinematics and dissipation, and their coupling with large scales of the flow. While [14] relied on bubble pulsation, that is normal deformation of the interface with shape preservation related to pressure changes, we aim here at tackling inclusion deformation at constant volume, thus describing self-sustained oscillations. In order to identify the proper energies, we use Direct Numerical Simulations (DNS) of oscillating droplets using ARCHER code and recently devel- oped library, Mercur(v)e, for mean geometrical variable evaluation and analysis preserving topological invariants. This study is combined with historical analytical studies conducted in the small perturba- tion regime and shows that the proper potential energy is related to the surface difference compared to the spherical minimal surface. A geometrical quasi-invariant is also identified and a natural definition of subscale momentum is proposed. The set of Partial Differential Equations (PDEs) including the conservation equations as well as dissipation source terms are eventually derived leading to an original two-scale diffuse interface model involving geometrical variables

Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes: parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine.

Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001 : were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine

The SAMI Galaxy Survey: : extraplanar gas, galactic winds, and their association with star formation history

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society, the version of record is available on line at doi: 10.1093/mnras/stw017We investigate a sample of 40 local, main-sequence, edge-on disc galaxies using integral field spectroscopy with the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey to understand the link between properties of the extraplanar gas and their host galaxies. The kinematics properties of the extraplanar gas, including velocity asymmetries and increased dispersion, are used to differentiate galaxies hosting large-scale galactic winds from those dominated by the extended diffuse ionized gas. We find rather that a spectrum of diffuse gas-dominated to wind dominated galaxies exist. The wind-dominated galaxies span a wide range of star formation rates ($-1 \lesssim \log({\rm SFR/M_{\odot} yr^{-1}}) \lesssim 0.5$) across the whole stellar mass range of the sample ($8.5 \lesssim \log({\rm M_{*}/M_{\odot}}) \lesssim 11$). The wind galaxies also span a wide range in SFR surface densities ($10^{-3} \textrm{--} 10^{-1.5}\rm~M_{\odot} ~yr^{-1}~kpc^{-2}$) that is much lower than the canonical threshold of $\rm0.1~M_{\odot} ~yr^{-1}~kpc^{-2}$. The wind galaxies on average have higher SFR surface densities and higher $\rm H\delta_A$ values than those without strong wind signatures. The enhanced $\rm H\delta_A$ indicates that bursts of star formation in the recent past are necessary for driving large-scale galactic winds. We demonstrate with Sloan Digital Sky Survey data that galaxies with high SFR surface density have experienced bursts of star formation in the recent past. Our results imply that the galactic winds revealed in our study are indeed driven by bursts of star formation, and thus probing star formation in the time domain is crucial for finding and understanding galactic winds.Peer reviewe

Étude des propriétés magnéto-optiques de structures à points quantiques indium(x) gallium(1-x) arsenic/arsenure de gallium

La structure électronique de points quantiques auto-assemblés InAs/GaAs et la dynamique de capture des porteurs ont été étudiées à l'aide d'expériences de magnéto-photoluminescence à faible température (4.5 K) et pour des champs magnétiques variant entre 0 et 16 T. Dans ce mémoire nous rapporterons les résultats obtenus sur deux séries d'échantillons interdiffusés par recuit rapide thermique pour différentes températures et différentes durées de recuit. La première série d'échantillons ne possédait qu'une seule couche de boîtes quantiques, ce qui la différenciait de la seconde série qui en comportait 25. Le processus d'interdiffusion conduit à une réduction significative de la largeur des raies d'émission PL associées aux différents états des points quantiques. Grâce à cette diminution de la largeur de ces raies, la dépendance en champ magnétique des états des points quantiques a pu être mise en évidence plus facilement. Nous avons ainsi pu corréler nos résultats expérimentaux aux calculs effectués dans le contexte des états de Fock Darwin. Nous avons également observé que le rapport entre l'intensité de la raie d'émission associée à la couche de mouillage et celle du pic d'émission correspondant aux points quantiques variait de façon non linéaire avec le champ magnétique. Le comportement observé semble être corrélé aux dépendances en champ magnétique du temps de capture des porteurs par les boîtes quantiques et du temps de recombinaison radiatif des excitons dans la couche de mouillage

Étude des propriétés magnéto-optiques de structures à points quantiques indium(x) gallium(1-x) arsenic/arsenure de gallium

La structure électronique de points quantiques auto-assemblés InAs/GaAs et la dynamique de capture des porteurs ont été étudiées à l'aide d'expériences de magnéto-photoluminescence à faible température (4.5 K) et pour des champs magnétiques variant entre 0 et 16 T. Dans ce mémoire nous rapporterons les résultats obtenus sur deux séries d'échantillons interdiffusés par recuit rapide thermique pour différentes températures et différentes durées de recuit. La première série d'échantillons ne possédait qu'une seule couche de boîtes quantiques, ce qui la différenciait de la seconde série qui en comportait 25. Le processus d'interdiffusion conduit à une réduction significative de la largeur des raies d'émission PL associées aux différents états des points quantiques. Grâce à cette diminution de la largeur de ces raies, la dépendance en champ magnétique des états des points quantiques a pu être mise en évidence plus facilement. Nous avons ainsi pu corréler nos résultats expérimentaux aux calculs effectués dans le contexte des états de Fock Darwin. Nous avons également observé que le rapport entre l'intensité de la raie d'émission associée à la couche de mouillage et celle du pic d'émission correspondant aux points quantiques variait de façon non linéaire avec le champ magnétique. Le comportement observé semble être corrélé aux dépendances en champ magnétique du temps de capture des porteurs par les boîtes quantiques et du temps de recombinaison radiatif des excitons dans la couche de mouillage