160 research outputs found
Deformable Voxel Grids for Shape Comparisons
We present Deformable Voxel Grids (DVGs) for 3D shapes comparison and
processing. It consists of a voxel grid which is deformed to approximate the
silhouette of a shape, via energy-minimization. By interpreting the DVG as a
local coordinates system, it provides a better embedding space than a regular
voxel grid, since it is adapted to the geometry of the shape. It also allows to
deform the shape by moving the control points of the DVG, in a similar manner
to the Free Form Deformation, but with easier interpretability of the control
points positions. After proposing a computation scheme of the energies
compatible with meshes and pointclouds, we demonstrate the use of DVGs in a
variety of applications: correspondences via cubification, style transfer,
shape retrieval and PCA deformations. The first two require no learning and can
be readily run on any shapes in a matter of minutes on modest hardware. As for
the last two, they require to first optimize DVGs on a collection of shapes,
which amounts to a pre-processing step. Then, determining PCA coordinates is
straightforward and brings a few parameters to deform a shape
Vascular smooth muscle Sirtuin-1 protects against aortic dissection during Angiotensin II-induced hypertension
BACKGROUND: Sirtuin-1 (SirT1), a nicotinamide adenine dinucleotide(+)-dependent deacetylase, is a key enzyme in the cellular response to metabolic, inflammatory, and oxidative stresses; however, the role of endogenous SirT1 in the vasculature has not been fully elucidated. Our goal was to evaluate the role of vascular smooth muscle SirT1 in the physiological response of the aortic wall to angiotensin II, a potent hypertrophic, oxidant, and inflammatory stimulus. METHODS AND RESULTS: Mice lacking SirT1 in vascular smooth muscle (ie, smooth muscle SirT1 knockout) had drastically high mortality (70%) caused by aortic dissection after angiotensin II infusion (1 mg/kg per day) but not after an equipotent dose of norepinephrine, despite comparable blood pressure increases. Smooth muscle SirT1 knockout mice did not show any abnormal aortic morphology or blood pressure compared with wild-type littermates. Nonetheless, in response to angiotensin II, aortas from smooth muscle SirT1 knockout mice had severely disorganized elastic lamellae with frequent elastin breaks, increased oxidant production, and aortic stiffness compared with angiotensin II-treated wild-type mice. Matrix metalloproteinase expression and activity were increased in the aortas of angiotensin II-treated smooth muscle SirT1 knockout mice and were prevented in mice overexpressing SirT1 in vascular smooth muscle or with use of the oxidant scavenger tempol. CONCLUSIONS: Endogenous SirT1 in aortic smooth muscle is required to maintain the structural integrity of the aortic wall in response to oxidant and inflammatory stimuli, at least in part, by suppressing oxidant-induced matrix metalloproteinase activity. SirT1 activators could potentially be a novel therapeutic approach to prevent aortic dissection and rupture in patients at risk, such as those with hypertension or genetic disorders, such as Marfan's syndrome.R01 HL098028 - NHLBI NIH HHS; HL098028 - NHLBI NIH HHS; HL105287 - NHLBI NIH HHS; T32 HL07224 - NHLBI NIH HH
Tribute to Jean-Yves Jaffray July 22, 1939 - February 26, 2009
International audienceTribute to Jean-Yves Jaffray by the French Group of Decision TheoryHommage à Jean-Yves Jaffray par le groupe français de Théorie de la Décisio
Autoparametric resonance extending the bit-flip time of a cat qubit up to 0.3 s
Cat qubits, for which logical and are coherent states
of a harmonic mode, offer a promising route towards quantum
error correction. Using dissipation to our advantage so that photon pairs of
the harmonic mode are exchanged with single photons of its environment, it is
possible to stabilize the logical states and exponentially increase the
bit-flip time of the cat qubit with the photon number . Large
two-photon dissipation rate ensures fast qubit manipulation and
short error correction cycles, which are instrumental to correct the remaining
phase-flip errors in a repetition code of cat qubits. Here we introduce and
operate an autoparametric superconducting circuit that couples a mode
containing the cat qubit to a lossy mode whose frequency is set at twice that
of the cat mode. This passive coupling does not require a parametric pump and
reaches a rate . With such a strong
two-photon dissipation, bit-flip errors of the autoparametric cat qubit are
prevented for a characteristic time up to 0.3 s with only a mild impact on
phase-flip errors. Besides, we illustrate how the phase of a quantum
superposition between and can be arbitrarily
changed by driving the harmonic mode while keeping the engineered dissipation
active
Androgen receptor signaling regulates follicular growth and steroidogenesis in interaction with gonadotropins in the ovary during mini-puberty in mice
In females, androgens contribute to ovarian diseases such as polycystic ovarian syndrome (PCOS), but their action is also crucial for ovarian physiology, i.e., follicular growth and estradiol (E2) synthesis during reproductive life, in interaction with the gonadotropins LH and FSH. However, it is unclear whether androgens already play a role in the ovary at mini-puberty, a phase of postnatal development with active follicular growth and high E2 levels. Therefore, we analyzed the potential actions of androgens on the ovary and their possible interaction with gonadotropins during this period in mice. We used molecular-based studies and pharmacological approaches in vivo and on cultured ovaries. We found that mini-pubertal ovaries produce significant amounts of testosterone and display androgen receptor (AR) expression in growing follicles, both under the control of LH. By blocking AR signaling either in vivo or in ovarian cultures, we found that this pathway may participate in the regulation of prepubertal E2 synthesis and follicular growth, possibly by regulating the expression of a number of key intra-ovarian regulators, including FSH receptor (Fshr), the aromatase enzyme converting androgens into estrogens (Cyp19a1) and the cell cycle inhibitor p27KIP1 (Cdkn1b). We further showed that AR may stimulate FSH-mediated regulation of Cyp19a1 through its action on Fshr mRNA abundance. Overall, this work supports the idea that AR signaling is already activated in mini-pubertal ovaries to regulate E2 synthesis and follicular growth, at the interplay with LH and FSH signaling. Its early action may, thus, contribute to the implementation of early ovarian function with possible impacts on reproductive function
Fluctuation Relations for Diffusion Processes
The paper presents a unified approach to different fluctuation relations for
classical nonequilibrium dynamics described by diffusion processes. Such
relations compare the statistics of fluctuations of the entropy production or
work in the original process to the similar statistics in the time-reversed
process. The origin of a variety of fluctuation relations is traced to the use
of different time reversals. It is also shown how the application of the
presented approach to the tangent process describing the joint evolution of
infinitesimally close trajectories of the original process leads to a
multiplicative extension of the fluctuation relations.Comment: 38 page
The Cerenkov effect revisited: from swimming ducks to zero modes in gravitational analogs
We present an interdisciplinary review of the generalized Cerenkov emission
of radiation from uniformly moving sources in the different contexts of
classical electromagnetism, superfluid hydrodynamics, and classical
hydrodynamics. The details of each specific physical systems enter our theory
via the dispersion law of the excitations. A geometrical recipe to obtain the
emission patterns in both real and wavevector space from the geometrical shape
of the dispersion law is discussed and applied to a number of cases of current
experimental interest. Some consequences of these emission processes onto the
stability of condensed-matter analogs of gravitational systems are finally
illustrated.Comment: Lecture Notes at the IX SIGRAV School on "Analogue Gravity" in Como,
Italy from May 16th-21th, 201
Probing the in vitro mechanism of action of cationic lipid/DNA lipoplexes at a nanometric scale
Cationic lipids are used for delivering nucleic acids (lipoplexes) into cells for both therapeutic and biological applications. A better understanding of the identified key-steps, including endocytosis, endosomal escape and nuclear delivery is required for further developments to improve their efficacy. Here, we developed a labelling protocol using aminated nanoparticles as markers for plasmid DNA to examine the intracellular route of lipoplexes in cell lines using transmission electron microscopy. Morphological changes of lipoplexes, membrane reorganizations and endosomal membrane ruptures were observed allowing the understanding of the lipoplex mechanism until the endosomal escape mediated by cationic lipids. The study carried out on two cationic lipids, bis(guanidinium)-tris(2-aminoethyl)amine-cholesterol (BGTC) and dioleyl succinyl paramomycin (DOSP), showed two pathways of endosomal escape that could explain their different transfection efficiencies. For BGTC, a partial or complete dissociation of DNA from cationic lipids occurred before endosomal escape while for DOSP, lipoplexes remained visible within ruptured vesicles suggesting a more direct pathway for DNA release and endosome escape. In addition, the formation of new multilamellar lipid assemblies was noted, which could result from the interaction between cationic lipids and cellular compounds. These results provide new insights into DNA transfer pathways and possible implications of cationic lipids in lipid metabolism
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