121 research outputs found
Fourier Modeling of the Left Ventricle Parasternal Boundary
Any parasternal boundary of the left ventricle of the heart, manually extracted
from an echocardiographic image, can be modeled using smoothing by truncating
the Fourier serie of its polar development round an inner origin . The choice
of a central origin, that annulates the Fourier coefficient at the first harmonic,
minimizes the quadratic distance between the manual boundary and the modeled
one. The parameters of the model are the coordinates of this central origin, and
the non-truncated Fourier coefficients. The geometrical interpretation of each of
these parameters, very simple, gives them a useful significance for the medical
diagnosis. In an other hand, the analysis of the smoothed boundaries evolution
for a complete cardiac cycle yields to measuring the isotropy of the contractions.
Finally, it is possible to extract the parameters ofa non-closed boundary by implicit
interpolation on the lacking portions.ZRToéuts
cuonmtéour parasternal du ventricule gauche du coeur, extrait manuellement sur
une image échocardiographique, est modélisable par lissage en tronquant la série de
Fourier de son développement polaire autour d'une origine interne . Le choix d'une
origine centrale, qui correspond à l'annulation du coefficient de Fourier au premier
harmonique, minimise l'écart quadratique entre le contour manuel et le contour
modélisé . Les paramètres du modèle sont les coordonnées de cette origine centrale
ainsi que les coefficients de Fourier non tronqués . L'interprétation géométrique de
ces paramètres, très simple, leur confère une signification utile pour le diagnostic
médical. D'autre part, l'analyse de l'évolution des contours lissés pendant le cycle
cardiaque conduit à une mesure de l'isotropie des contractions . Enfin, il est possible
d'extraire les paramètres d'un contour non fermé par interpolation implicite sur
les portions manquantes
The effect of induced forelimb lameness on thoracolumbar kinematics during treadmill locomotion
Reasons for performing study: Lameness has often been suggested to result in altered movement of the back, but there are no detailed studies describing such a relationship in quantitative terms. Objectives: To quantify the effect of induced subtle forelimb lameness on thoracolumbar kinematics in the horse. Methods: Kinematics of 6 riding horses was measured at walk and at trot on a treadmill before and after the induction of reversible forelimb lameness grade 2 (AAEP scale 1-5). Ground reaction forces (GRF) for individual limbs were calculated from kinematics. Results: The horses significantly unloaded the painful limb by 11.5% at trot, while unloading at walk was not significant. The overall flexion-extension range of back motion decreased on average by 0.2° at walk and increased by 3.3° at trot (P<0.05). Changes in angular motion patterns of vertebral joints were noted only at trot, with an increase in flexion of 0.9° at T10 (i.e. angle between T6, T10 and T13) during the stance phase of the sound diagonal and an increase in extension of the thoracolumbar area during stance of the lame diagonal (0.7° at T13, 0.8° at T17, 0.5° at L1, 0.4° at L3 and 0.3° at L5) (P<0.05). Lameness further caused a lateral bending of the cranial thoracic vertebral column towards the lame side (1.3° at T10 and 0.9° at T13) (P<0.05) during stance of the lame diagonal. Conclusions: Both range of motion and vertebral angular motion patterns are affected by subtle forelimb lameness. At walk, the effect is minimal, at trot the horses increased the vertebral range of motion and changed the pattern of thoracolumbar motion in the sagittal and horizontal planes, presumably in an attempt to move the centre of gravity away from the lame side and reduce the force on the affected limb. Potential relevance: Subtle forelimb lameness affects thoracolumbar kinematics. Future studies should aim at elucidating whether the altered movement patterns lead to back and/or neck dysfunction in the case of chronic lameness
First light of VLT/HiRISE: High-resolution spectroscopy of young giant exoplanets
A major endeavor of this decade is the direct characterization of young giant
exoplanets at high spectral resolution to determine the composition of their
atmosphere and infer their formation processes and evolution. Such a goal
represents a major challenge owing to their small angular separation and
luminosity contrast with respect to their parent stars. Instead of designing
and implementing completely new facilities, it has been proposed to leverage
the capabilities of existing instruments that offer either high contrast
imaging or high dispersion spectroscopy, by coupling them using optical fibers.
In this work we present the implementation and first on-sky results of the
HiRISE instrument at the very large telescope (VLT), which combines the
exoplanet imager SPHERE with the recently upgraded high resolution spectrograph
CRIRES using single-mode fibers. The goal of HiRISE is to enable the
characterization of known companions in the band, at a spectral resolution
of the order of , in a few hours of
observing time. We present the main design choices and the technical
implementation of the system, which is constituted of three major parts: the
fiber injection module inside of SPHERE, the fiber bundle around the telescope,
and the fiber extraction module at the entrance of CRIRES. We also detail the
specific calibrations required for HiRISE and the operations of the instrument
for science observations. Finally, we detail the performance of the system in
terms of astrometry, temporal stability, optical aberrations, and transmission,
for which we report a peak value of 3.9% based on sky measurements in
median observing conditions. Finally, we report on the first astrophysical
detection of HiRISE to illustrate its potential.Comment: 17 pages, 15 figures, 3 tables. Submitted to A&A on 19 September 202
Direct characterization of young giant exoplanets at high spectral resolution by coupling SPHERE and CRIRES+
This is the final version. Available on open access from EDP Sciences via the DOI in this recordStudies of atmospheres of directly imaged extrasolar planets with high-resolution spectrographs have shown that their characterization
is predominantly limited by noise on the stellar halo at the location of the studied exoplanet. An instrumental combination of highcontrast imaging and high spectral resolution that suppresses this noise and resolves the spectral lines can therefore yield higher quality
spectra. We study the performance of the proposed HiRISE fiber coupling between the direct imager SPHERE and the spectrograph
CRIRES+ at the Very Large Telescope for spectral characterization of directly imaged planets. Using end-to-end simulations of
HiRISE we determine the signal-to-noise ratio (S/N) of the detection of molecular species for known extrasolar planets in H and K
bands, and compare them to CRIRES+. We investigate the ultimate detection limits of HiRISE as a function of stellar magnitude, and
we quantify the impact of different coronagraphs and of the system transmission. We find that HiRISE largely outperforms CRIRES+
for companions around bright hosts like β Pictoris or 51 Eridani. For an H = 3.5 host, we observe a gain of a factor of up to 36 in
observing time with HiRISE to reach the same S/N on a companion at 200 mas. More generally, HiRISE provides better performance
than CRIRES+ in two-hour integration times between 50–400 mas for hosts with H < 8.5 and between 50–800 mas for H < 7. For
fainter hosts like PDS 70 and HIP 65426, no significant improvements are observed. We find that using no coronagraph yields the
best S/N when characterizing known exoplanets due to higher transmission and fiber-based starlight suppression. We demonstrate
that the overall transmission of the system is in fact the main driver of performance. Finally, we show that HiRISE outperforms the
best detection limits of SPHERE for bright stars, opening major possibilities for the characterization of future planetary companions
detected by other techniquesEuropean Union Horizon 202
Mathematical Modelling as a Proof of Concept for MPNs as a Human Inflammation Model for Cancer Development
<p><b>Left:</b> Typical development in stem cells (top panel A) and mature cells (bottom panel B). Healthy hematopoietic cells (full blue curves) dominate in the early phase where the number of malignant cells (stipulated red curves) are few. The total number of cells is also shown (dotted green curves). When a stem cell mutates without repairing mechanisms, a slowly increasing exponential growth starts. At a certain stage, the malignant cells become dominant, and the healthy hematopoietic cells begin to show a visible decline. Finally, the composition between the cell types results in a takeover by the malignant cells, leading to an exponential decline in hematopoietic cells and ultimately their extinction. The development is driven by an approximately exponential increase in the MPN stem cells, and the development is closely followed by the mature MPN cells. <b>Right:</b> B)The corresponding allele burden (7%, 33% and 67% corresponding to ET, PV, and PMF, respectively) defined as the ratio of MPN mature cells to the total number of mature cells.</p
The role of the mitochondria and the endoplasmic reticulum contact sites in the development of the immune responses
Abstract Mitochondria and endoplasmic reticulum (ER) contact sites (MERCs) are dynamic modules enriched in subset of lipids and specialized proteins that determine their structure and functions. The MERCs regulate lipid transfer, autophagosome formation, mitochondrial fission, Ca2+ homeostasis and apoptosis. Since these functions are essential for cell biology, it is therefore not surprising that MERCs also play a critical role in organ physiology among which the immune system stands by its critical host defense function. This defense system must discriminate and tolerate host cells and beneficial commensal microorganisms while eliminating pathogenic ones in order to preserve normal homeostasis. To meet this goal, the immune system has two lines of defense. First, the fast acting but unspecific innate immune system relies on anatomical physical barriers and subsets of hematopoietically derived cells expressing germline-encoded receptors called pattern recognition receptors (PRR) recognizing conserved motifs on the pathogens. Second, the slower but very specific adaptive immune response is added to complement innate immunity. Adaptive immunity relies on another set of specialized cells, the lymphocytes, harboring receptors requiring somatic recombination to be expressed. Both innate and adaptive immune cells must be activated to phagocytose and process pathogens, migrate, proliferate, release soluble factors and destroy infected cells. Some of these functions are strongly dependent on lipid transfer, autophagosome formation, mitochondrial fission, and Ca2+ flux; this indicates that MERCs could regulate immunity
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