1,423 research outputs found
Infantile de novo primary antiphospholipid syndrome revealed by neonatal stroke
International audiencepas de résum
Probing star formation in the dense environments of z ~ 1 lensing haloes aligned with dusty star-forming galaxies detected with the South Pole Telescope
We probe star formation in the environments of massive (∼10^(13) M_⊙) dark matter haloes at redshifts of z ∼ 1. This star formation is linked to a submillimetre clustering signal which we detect in maps of the Planck High Frequency Instrument that are stacked at the positions of a sample of high redshift (z > 2) strongly lensed dusty star-forming galaxies (DSFGs) selected from the South Pole Telescope (SPT) 2500 deg^2 survey. The clustering signal has submillimetre colours which are consistent with the mean redshift of the foreground lensing haloes (z ∼ 1). We report a mean excess of star formation rate (SFR) compared to the field, of (2700 ± 700) M_⊙ yr^(−1) from all galaxies contributing to this clustering signal within a radius of 3.5 arcmin from the SPT DSFGs. The magnitude of the Planck excess is in broad agreement with predictions of a current model of the cosmic infrared background. The model predicts that 80 per cent of the excess emission measured by Planck originates from galaxies lying in the neighbouring haloes of the lensing halo. Using Herschel maps of the same fields, we find a clear excess, relative to the field, of individual sources which contribute to the Planck excess. The mean excess SFR compared to the field is measured to be (370 ± 40) M_⊙ yr^(−1) per resolved, clustered source. Our findings suggest that the environments around these massive z ∼ 1 lensing haloes host intense star formation out to about 2 Mpc. The flux enhancement due to clustering should also be considered when measuring flux densities of galaxies in Planck data
Decomposition and factorisation of transients in Functional Graphs
Functional graphs (FGs) model the graph structures used to analyze the
behavior of functions from a discrete set to itself. In turn, such functions
are used to study real complex phenomena evolving in time. As the systems
involved can be quite large, it is interesting to decompose and factorize them
into several subgraphs acting together. Polynomial equations over functional
graphs provide a formal way to represent this decomposition and factorization
mechanism, and solving them validates or invalidates hypotheses on their
decomposability. The current solution method breaks down a single equation into
a series of \emph{basic} equations of the form (with , ,
and being FGs) to identify the possible solutions. However, it is able to
consider just FGs made of cycles only. This work proposes an algorithm for
solving these basic equations for general connected FGs. By exploiting a
connection with the cancellation problem, we prove that the upper bound to the
number of solutions is closely related to the size of the cycle in the
coefficient of the equation. The cancellation problem is also involved in
the main algorithms provided by the paper. We introduce a polynomial-time
semi-decision algorithm able to provide constraints that a potential solution
will have to satisfy if it exists. Then, exploiting the ideas introduced in the
first algorithm, we introduce a second exponential-time algorithm capable of
finding all solutions by integrating several `hacks' that try to keep the
exponential as tight as possible
Nutritional Evaluation and Optimisation in Neonates (NEON): a randomised double-blind controlled trial of amino-acid regimen and intravenous lipid composition in preterm parenteral nutrition
Exploiting Cross Correlations and Joint Analyses
In this report, we present a wide variety of ways in which information from
multiple probes of dark energy may be combined to obtain additional information
not accessible when they are considered separately. Fundamentally, because all
major probes are affected by the underlying distribution of matter in the
regions studied, there exist covariances between them that can provide
information on cosmology. Combining multiple probes allows for more accurate
(less contaminated by systematics) and more precise (since there is
cosmological information encoded in cross-correlation statistics) measurements
of dark energy. The potential of cross-correlation methods is only beginning to
be realized. By bringing in information from other wavelengths, the
capabilities of the existing probes of dark energy can be enhanced and
systematic effects can be mitigated further. We present a mixture of work in
progress and suggestions for future scientific efforts. Given the scope of
future dark energy experiments, the greatest gains may only be realized with
more coordination and cooperation between multiple project teams; we recommend
that this interchange should begin sooner, rather than later, to maximize
scientific gains.Comment: Report from the "Dark Energy and CMB" working group for the American
Physical Society's Division of Particles and Fields long-term planning
exercise ("Snowmass"
Conditions de formation de composés organoiodés sapides lors de l'oxydation par le chlore d'eaux contenant des ions iodure
Le travail a consisté à préciser les conditions de formation d'une molécule iodée sapide, l'iodoforme, lors de l'oxydation d'une eau brute par le chlore et à proposer une voie réactionnelle possible.L'étude de la chloration d'une eau brute en présence d'azote ammoniacal et d'ions iodure conduit à la formation d'iodoforme uniquement pour des taux inférieurs au point de rupture. Les résultats montrent que l'oxydation de l'ion ammonium conduit à la formation de monochloramine dont le pouvoir oxydant totalement disponible pourrait être impliqué dans la formation de iodamines ou de chloroiodamines. Ces réactions sont plus favorables en présence d'iode qu'en présence d'ions iodure. Mais l'action de l'iode seul en présence d'ammoniaque et en absence de monochloramine ne permet pas d'expliquer la production des composés organoiodés observés. Ce sont les précurseurs intermédiaires formés à partir des chloramines qui, par action sur la matière organique naturelle, seraient responsables de la formation d'iodoforme. Dans une moindre mesure, certains composés azotés organiques tels les amines et les acides aminés pourraient prendre part à la production des composés organoiodés lors de la chloration.This work consisted of specifying the conditions of iodoform formation during chlorination of a raw water containing iodides. To reach this objective, there was need to spike the studied natural water with potassium iodide (200 µg.L-1) in order to increase the low natural iodide content. Free and combined chlorine, chlorinated and brominated trihalomethanes (THMs) and iodoform were analyzed.It was shown that :- iodoform is formed for chlorine doses prior to the breakpoint, in a region where the formation of the most classical chlorinated and brominated THMs is usually disfavored (Figures 1-4); - in the presence of chloramines the rate of production of iodoform increases with increasing I- or I2 (Figure 5); - the direct reaction of I2 with THM precursors to produce iodoform is slow and independent of the presence of ammonia (Table 1). - Nitrogenated compounds such as amines and amino acids would also take part in the production of organoiodinated compounds during chlorination (Figure 7). However, under water treatment conditions, taking into account the amine and amino acid content of natural waters, this class of compounds will only take a small part in the mechanism of iodoform formation. Among the possible routes that could account for the observations made in this research, the formation of iodamines or chloroiodamines as intermediates is suggested (Figure 8). From a practical point of view, the removal of ammonia from water by a biological process (nitrification step) would inhibit the iodoform formation potential and allow the application of the final chlorination step. Another alternative would involve replacing the chlorination step by oxidation with chlorine dioxide
Limitation of energy deposition in classical N body dynamics
Energy transfers in collisions between classical clusters are studied with
Classical N Body Dynamics calculations for different entrance channels. It is
shown that the energy per particle transferred to thermalised classical
clusters does not exceed the energy of the least bound particle in the cluster
in its ``ground state''. This limitation is observed during the whole time of
the collision, except for the heaviest system.Comment: 13 pages, 15 figures, 1 tabl
Probing the dynamical state of galaxy clusters
We show how hydrostatic equilibrium in galaxy clusters can be quantitatively
probed combining X-ray, SZ, and gravitational-lensing data. Our previously
published method for recovering three-dimensional cluster gas distributions
avoids the assumption of hydrostatic equilibrium. Independent reconstructions
of cumulative total-mass profiles can then be obtained from the gas
distribution, assuming hydrostatic equilibrium, and from gravitational lensing,
neglecting it. Hydrostatic equilibrium can then be quantified comparing the
two. We describe this procedure in detail and show that it performs well on
progressively realistic synthetic data. An application to a cluster merger
demonstrates how hydrostatic equilibrium is violated and restored as the merger
proceeds.Comment: 10 pages, 6 figures, submitted to A&
A step towards testing general relativity using weak gravitational lensing and redshift surveys
Using the linear theory of perturbations in General Relativity, we express a
set of consistency relations that can be observationally tested with current
and future large scale structure surveys. We then outline a stringent
model-independent program to test gravity on cosmological scales. We illustrate
the feasibility of such a program by jointly using several observables like
peculiar velocities, galaxy clustering and weak gravitational lensing. After
addressing possible observational or astrophysical caveats like galaxy bias and
redshift uncertainties, we forecast in particular how well one can predict the
lensing signal from a cosmic shear survey using an over-lapping galaxy survey.
We finally discuss the specific physics probed this way and illustrate how
gravity models would fail such a test.Comment: 12 pages, 10 figure
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