127 research outputs found
A new technique for reconstruction of the aortic bifurcation with saphenous vein panel graft
A 60-year-old male patient presented with a false aneurysm of the common iliac artery and methicillin-resistant Staphylococcus aureus septicemia complicating previously placed kissing covered stents of the aortic bifurcation. We removed the prosthetic material and repaired the aortic bifurcation with a composite saphenous vein panel graft. To our knowledge, this technique is presented for the first time in the literature
Gas inflows, star formation and metallicity evolution in galaxy pairs
It has been known since many decades that galaxy interactions can induce star
formation (hereafter SF) enhancements and that one of the driving mechanisms of
this enhancement is related to gas inflows into the central galaxy regions,
induced by asymmetries in the stellar component, like bars. In the last years
many evidences have been accumulating, showing that interacting pairs have
central gas-phase metallicities lower than those of field galaxies, by {\sim}
0.2-0.3 dex on average. These diluted ISM metallicities have been explained as
the result of inflows of metal-poor gas from the outer disk to the galaxy
central regions. A number of questions arises: What's the timing and the
duration of this dilution? How and when does the SF induced by the gas inflow
enrich the circumnuclear gas with re-processed material? Is there any
correlation between the timing and strength of the dilution and the timing and
intensity of the SF? By means of Tree-SPH simulations of galaxy major
interactions, we have studied the effect that gas inflows have on the ISM
dilution, and the effect that the induced SF has, subsequently, in re-enriching
the nuclear gas. In this contribution, we present the main results of this
study.Comment: Proceedings of the IAU Symposium 277 "Tracing the Ancestry of
Galaxies", 4 pages, 2 figure
Loss of mass and stability of galaxies in MOND
The self-binding energy and stability of a galaxy in MOND-based gravity are
curiously decreasing functions of its center of mass acceleration towards
neighbouring mass concentrations. A tentative indication of this breaking of
the Strong Equivalence Principle in field galaxies is the RAVE-observed escape
speed in the Milky Way. Another consequence is that satellites of field
galaxies will move on nearly Keplerian orbits at large radii (100 - 500 kpc),
with a declining speed below the asymptotically constant naive MOND prediction.
But consequences of an environment-sensitive gravity are even more severe in
clusters, where member galaxies accelerate fast: no more Dark-Halo-like
potential is present to support galaxies, meaning that extended axisymmetric
disks of gas and stars are likely unstable. These predicted reappearance of
asymptotic Keplerian velocity curves and disappearance of "stereotypic
galaxies" in clusters are falsifiable with targeted surveys.Comment: 4 pages, 2 figures, ApJ Letter
Lopsidedness of cluster galaxies in modified gravity
We point out an interesting theoretical prediction for elliptical galaxies
residing inside galaxy clusters in the framework of modified Newtonian dynamics
(MOND), that could be used to test this paradigm. Apart from the central
brightest cluster galaxy, other galaxies close enough to the centre experience
a strong gravitational influence from the other galaxies of the cluster. This
influence manifests itself only as tides in standard Newtonian gravity, meaning
that the systematic acceleration of the centre of mass of the galaxy has no
consequence. However, in the context of MOND, a consequence of the breaking of
the strong equivalence principle is that the systematic acceleration changes
the own self-gravity of the galaxy. We show here that, in this framework,
initially axisymmetric elliptical galaxies become lopsided along the external
field's direction, and that the centroid of the galaxy, defined by the outer
density contours, is shifted by a few hundreds parsecs with respect to the
densest point.Comment: accepted for publication in JCA
Free-surface flows from Kinect: Feasibility and limits
[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]SPEEInternational audienceIn this work, we investigate the combined use of a Kinect depth sensor and of a stochastic data assimilation method to recover free-surface flows. For this purpose, we first show that the Kinect is likely to capture temporal sequences of depth observations of wave-like surfaces with wavelengths and amplitudes sufficiently small to characterise medium/large scale flows. Then, we illustrate the ability of a stochastic data assimilation method to estimate both time-dynamic water surface elevations and velocities from sequences of synthetical depth images having characteristics close to the Kinect ones
Do old globular clusters in low mass galaxies disprove modified gravity?
The controversy "dark matter vs. modified gravity" constitutes a major topic
of discussion. It was proposed that dynamical friction could be used to
discriminate between the two alternatives. Analytic calculations indicate that,
with modified gravity, globular clusters (GCs) of low-mass galaxies experience
much stronger dynamical friction than in the equivalent system with Newtonian
gravity and dark matter. As a result, in modified gravity the old GCs of low
mass galaxies should have already settled in the centers of the galaxies. This
is not observed. Here we report on our efforts to verify the analytic results
by self-consistent simulations with the MOND-type (modified Newtonian dynamics)
gravity. The core stalling mechanism, that was not considered in the analytic
calculations, prevents GCs to settle in centers of ultra-diffuse galaxies. For
isolated dwarf galaxies, which are gas-rich objects, supernova explosions
prevent the GCs from settling.Comment: 4 pages, 2 figures, accepted for publication in the proceedings of
IAU Symposium 379: Dynamical Masses of Local Group Galaxie
Ablation of supraventricular arrhythmias in adult congenital heart disease: A contemporary review
Reconciling MOND and dark matter?
Observations of galaxies suggest a one-to-one analytic relation between the
inferred gravity of dark matter at any radius and the enclosed baryonic mass, a
relation summarized by Milgrom's law of modified Newtonian dynamics (MOND).
However, present-day covariant versions of MOND usually require some additional
fields contributing to the geometry, as well as an additional hot dark matter
component to explain cluster dynamics and cosmology. Here, we envisage a
slightly more mundane explanation, suggesting that dark matter does exist but
is the source of MOND-like phenomenology in galaxies. We assume a canonical
action for dark matter, but also add an interaction term between baryonic
matter, gravity, and dark matter, such that standard matter effectively obeys
the MOND field equation in galaxies. We show that even the simplest realization
of the framework leads to a model which reproduces some phenomenological
predictions of cold dark matter (CDM) and MOND at those scales where these are
most successful. We also devise a more general form of the interaction term,
introducing the medium density as a new order parameter. This allows for new
physical effects which should be amenable to observational tests in the near
future. Hence, this very general framework, which can be furthermore related to
a generalized scalar-tensor theory, opens the way to a possible unification of
the successes of CDM and MOND at different scales.Comment: 9 page
Introducing the Dirac-Milne universe
The \Lambda CDM standard model, although an excellent parametrization of the
present cosmological data, requires two as yet unobserved components, Dark
Matter and Dark Energy, for more than 95% of the Universe. Faced to this
unsatisfactory situation, we study an unconventional cosmology, the Dirac-Milne
universe, a matter-antimatter symmetric cosmology, in which antimatter is
supposed to present a negative active gravitational mass. The main feature of
this cosmology is the linear evolution of the scale factor with time which
directly solves the age and horizon problems of a matter-dominated universe. We
study the concordance of this model to the cosmological test of Type Ia
Supernov\ae\ distance measurements and calculate the theoretical primordial
abundances of light elements for this cosmology. We also show that the acoustic
scale of the Cosmic Microwave Background naturally emerges at the degree scale
despite an open geometry.Comment: Replaced to match published versio
Identification of a novel BET bromodomain inhibitor-sensitive, gene regulatory circuit that controls Rituximab response and tumour growth in aggressive lymphoid cancers.: CYCLON-induced Rituximab resistance
International audienceImmuno-chemotherapy elicit high response rates in B-cell non-Hodgkin lymphoma but heterogeneity in response duration is observed, with some patients achieving cure and others showing refractory disease or relapse. Using a transcriptome-powered targeted proteomics screen, we discovered a gene regulatory circuit involving the nuclear factor CYCLON which characterizes aggressive disease and resistance to the anti-CD20 monoclonal antibody, Rituximab, in high-risk B-cell lymphoma. CYCLON knockdown was found to inhibit the aggressivity of MYC-overexpressing tumours in mice and to modulate gene expression programs of biological relevance to lymphoma. Furthermore, CYCLON knockdown increased the sensitivity of human lymphoma B cells to Rituximab in vitro and in vivo. Strikingly, this effect could be mimicked by in vitro treatment of lymphoma B cells with a small molecule inhibitor for BET bromodomain proteins (JQ1). In summary, this work has identified CYCLON as a new MYC cooperating factor that autonomously drives aggressive tumour growth and Rituximab resistance in lymphoma. This resistance mechanism is amenable to next-generation epigenetic therapy by BET bromodomain inhibition, thereby providing a new combination therapy rationale for high-risk lymphoma
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