552 research outputs found
In-vivo measurement of the human soft tissues constitutive laws. Applications to Computer Aided Surgery
In the 80's, biomechanicians were asked to work on Computer Aided Surgery
applications since orthopaedic surgeons were looking for numerical tools able
to predict risks of fractures. More recently, biomechanicians started to
address soft tissues arguing that most of the human body is made of such
tissues that can move as well as deform during surgical gestures [1]. An
intra-operative use of a continuous Finite Element (FE) Model of a given tissue
mainly faces two problems: (1) the numerical simulations have to be
"interactive", i.e. sufficiently fast to provide results during surgery (which
can be a strong issue in the context of hyperelastic models for example) and
(2) during the intervention, the surgeon needs a device that can be used to
provide to the model an estimation of the patient-specific constitutive
behaviour of the soft tissues. This work proposes an answer to the second
point, with the design of a new aspiration device aiming at characterizing the
in vivo constitutive laws of human soft tissues. The device was defined in
order to permit sterilization as well an easy intra-operative use
Niobium Silicon alloys for Kinetic Inductance Detectors
We are studying the properties of Niobium Silicon amorphous alloys as a
candidate material for the fabrication of highly sensitive Kinetic Inductance
Detectors (KID), optimized for very low optical loads. As in the case of other
composite materials, the NbSi properties can be changed by varying the relative
amounts of its components. Using a NbSi film with T_c around 1 K we have been
able to obtain the first NbSi resonators, observe an optical response and
acquire a spectrum in the band 50 to 300 GHz. The data taken show that this
material has very high kinetic inductance and normal state surface resistivity.
These properties are ideal for the development of KID. More measurements are
planned to further characterize the NbSi alloy and fully investigate its
potential.Comment: Accepted for publication on Journal of Low Temperature Physics.
Proceedings of the LTD15 conference (Caltech 2013
Psychological Impairment and Extreme Weather Event (EWE) Exposure, 1980â2020: A Global Pooled Analysis Integrating Mental Health and Well-being Metrics
Extreme Weather Events (EWEs) impose a substantial health and socio-economic burden on exposed populations. Projected impacts on public health, based on increasing EWE frequencies since the 1950s, alongside evidence of human-mediated climatic change represents a growing concern. To date, the impacts of EWEs on mental health remain ambiguous, largely due to the inherent complexities in linking extreme weather phenomena with psychological status. This exploratory investigation provides a new empirical and global perspective on the psychological toll of EWEs by exclusively focusing on psychological morbidity among individuals exposed to such events. Morbidity data collated from a range of existing psychological and well-being measures have been integrated to develop a single (âholisticâ) metric, namely, psychological impairment. Morbidity, and impairment, were subsequently pooled for key disorders-, specifically PTSD, anxiety and depression. A âcompositeâ (any impairment) post-exposure pooled-prevalence rate of 23% was estimated, with values of 24% calculated for depression and â17% for both PTSD and anxiety. Notably, calculated pooled odds ratios (pOR = 1.9) indicate a high likelihood of any negative psychological outcome (+90%) following EWE exposure. Pooled analyses of reported risk factors (p \u3c 0.05) highlight the pronounced impacts of EWEs among individuals with higher levels of event exposure or experienced stressors (14.5%) and socio-demographic traits traditionally linked to vulnerable sub-populations, including female gender (10%), previous history (i.e., pre-event) of psychological impairment (5.5%), lower socio-economic status (5.5%), and a lower education level (5.2%). Inherent limitations associated with collating mental health data from populations exposed to EWEs, and key knowledge gaps in the field are highlighted. Study findings provide a robust evidence base for developing and implementing public health intervention strategies aimed at ameliorating the psychological impacts of extreme weather among exposed populations
Scavenger 0.1: A Theorem Prover Based on Conflict Resolution
This paper introduces Scavenger, the first theorem prover for pure
first-order logic without equality based on the new conflict resolution
calculus. Conflict resolution has a restricted resolution inference rule that
resembles (a first-order generalization of) unit propagation as well as a rule
for assuming decision literals and a rule for deriving new clauses by (a
first-order generalization of) conflict-driven clause learning.Comment: Published at CADE 201
Reconstruction en imagerie gamma Ă partir d'acquisitions multi-Ă©nergie
Le problÚme traité concerne la reconstruction de la distribution 3D de sources radioactives lors d'examens scintigraphiques. Nous proposons une approche de reconstruction permettant d'exploiter les informations issues de capteurs spectrométriques et en particulier les informations portées par le rayonnement diffusé pour améliorer la qualité des images. La communication présente les résultats obtenus par une approche d'inversion s'appuyant sur un modÚle précis de la physique de formation des projections en imagerie gamma. Cette méthode a été baptisée SCARECO (scatter recovery)
Fluorescent oxide nanoparticles adapted to active tips for near-field optics
We present a new kind of fluorescent oxide nanoparticles with properties well
suited to active-tip based near-field optics. These particles with an average
diameter in the range 5-10 nm are produced by Low Energy Cluster Beam
Deposition (LECBD) from a YAG:Ce3+ target. They are studied by transmission
electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), classical
photoluminescence, cathodoluminescence and near-field scanning optical
microscopy (NSOM). Particles of extreme photo-stability as small as 10 nm in
size are observed. These emitters are validated as building blocks of active
NSOM tips by coating a standard optical tip with a 10 nm thick layer of
YAG:Ce3+ particles directly in the LECBD reactor and by subsequently performing
NSOM imaging of test surfaces.Comment: Changes made following Referee's comments; added references; one
added figure. See story on this article at:
http://nanotechweb.org/cws/article/tech/3606
On the dynamical behavior of the ABC model
We consider the ABC dynamics, with equal density of the three species, on the
discrete ring with sites. In this case, the process is reversible with
respect to a Gibbs measure with a mean field interaction that undergoes a
second order phase transition. We analyze the relaxation time of the dynamics
and show that at high temperature it grows at most as while it grows at
least as at low temperature
Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells
Diamond nanoparticles (nanodiamonds) have been recently proposed as new
labels for cellular imaging. For small nanodiamonds (size <40 nm) resonant
laser scattering and Raman scattering cross-sections are too small to allow
single nanoparticle observation. Nanodiamonds can however be rendered
photoluminescent with a perfect photostability at room temperature. Such a
remarkable property allows easier single-particle tracking over long
time-scales. In this work we use photoluminescent nanodiamonds of size <50 nm
for intracellular labeling and investigate the mechanism of their uptake by
living cells . By blocking selectively different uptake processes we show that
nanodiamonds enter cells mainly by endocytosis and converging data indicate
that it is clathrin mediated. We also examine nanodiamonds intracellular
localization in endocytic vesicles using immunofluorescence and transmission
electron microscopy. We find a high degree of colocalization between vesicles
and the biggest nanoparticles or aggregates, while the smallest particles
appear free in the cytosol. Our results pave the way for the use of
photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule
deliver
High resolution SZ observations at the IRAM 30-m telescope with NIKA
High resolution observations of the thermal Sunyaev-Zel'dovich (tSZ) effect
are necessary to allow the use of clusters of galaxies as a probe for large
scale structures at high redshifts. With its high resolution and dual-band
capability at millimeter wavelengths, the NIKA camera can play a significant
role in this context. NIKA is based on newly developed Kinetic Inductance
Detectors (KIDs) and operates at the IRAM 30m telescope, Pico Veleta, Spain. In
this paper, we give the status of the NIKA camera, focussing on the KID
technology. We then present observations of three galaxy clusters: RX
J1347.5-1145 as a demonstrator of the NIKA capabilities and the recent
observations of CL J1226.9+3332 (z = 0.89) and MACS J0717.5+3745 (z = 0.55). We
also discuss prospects for the final NIKA2 camera, which will have a 6.5
arcminute field of view with about 5000 detectors in two bands at 150 and 260
GHz
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