4,234 research outputs found
Energy Conversion Using New Thermoelectric Generator
During recent years, microelectronics helped to develop complex and varied
technologies. It appears that many of these technologies can be applied
successfully to realize Seebeck micro generators: photolithography and
deposition methods allow to elaborate thin thermoelectric structures at the
micro-scale level. Our goal is to scavenge energy by developing a miniature
power source for operating electronic components. First Bi and Sb micro-devices
on silicon glass substrate have been manufactured with an area of 1cm2
including more than one hundred junctions. Each step of process fabrication has
been optimized: photolithography, deposition process, anneals conditions and
metallic connections. Different device structures have been realized with
different micro-line dimensions. Each devices performance will be reviewed and
discussed in function of their design structure.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Left ventricular ejection time, not heart rate, is an independent correlate of aortic pulse wave velocity.
Salvi P, Palombo C, Salvi GM, Labat C, Parati G, Benetos A. Left
ventricular ejection time, not heart rate, is an independent correlate of
aortic pulse wave velocity. J Appl Physiol 115: 1610–1617, 2013. First
published September 19, 2013; doi:10.1152/japplphysiol.00475.2013.—
Several studies showed a positive association between heart rate and
pulse wave velocity, a sensitive marker of arterial stiffness. However, no
study involving a large population has specifically addressed the dependence
of pulse wave velocity on different components of the cardiac
cycle. The aim of this study was to explore in subjects of different age the
link between pulse wave velocity with heart period (the reciprocal of
heart rate) and the temporal components of the cardiac cycle such as left
ventricular ejection time and diastolic time. Carotid-femoral pulse wave
velocity was assessed in 3,020 untreated subjects (1,107 men). Heart
period, left ventricular ejection time, diastolic time, and early-systolic
dP/dt were determined by carotid pulse wave analysis with high-fidelity
applanation tonometry. An inverse association was found between pulse
wave velocity and left ventricular ejection time at all ages (25 years,
r2 0.043; 25–44 years, r2 0.103; 45–64 years, r2 0.079; 65–84
years, r2 0.044; 85 years, r2 0.022; P 0.0001 for all). A
significant (P 0.0001) negative but always weaker correlation between
pulse wave velocity and heart period was also found, with the exception
of the youngest subjects (P0.20). A significant positive correlation was
also found between pulse wave velocity and dP/dt (P 0.0001). With
multiple stepwise regression analysis, left ventricular ejection time and
dP/dt remained the only determinant of pulse wave velocity at all ages,
whereas the contribution of heart period no longer became significant.
Our data demonstrate that pulse wave velocity is more closely related to
left ventricular systolic function than to heart period. This may have
methodological and pathophysiological implications
Skeleton and fractal scaling in complex networks
We find that the fractal scaling in a class of scale-free networks originates
from the underlying tree structure called skeleton, a special type of spanning
tree based on the edge betweenness centrality. The fractal skeleton has the
property of the critical branching tree. The original fractal networks are
viewed as a fractal skeleton dressed with local shortcuts. An in-silico model
with both the fractal scaling and the scale-invariance properties is also
constructed. The framework of fractal networks is useful in understanding the
utility and the redundancy in networked systems.Comment: 4 pages, 2 figures, final version published in PR
Validity of Italian adaptation of the Dizziness Handicap Inventory (DHI) and evaluation of the quality of life in patients with acute dizziness
The impact of dizziness on Quality of Life (QoL) can be assessed by the Dizziness Handicap Inventory (DHI), which is used as a discriminative
and evaluative tool. Although the DHI is available in several languages, an equivalent version for the Italian population is not yet
available. Aim of this study was to translate the DHI into the Italian language (DHI-I), assess its correlation to the Italian version of the
Short Form-36 Health Survey and to investigate its reliability in evaluating the QoL of patients with acute dizziness. The study population
consisted of 50 patients (76% females and 24% males), mean age 51.6 years, range 25-85 years (SD = 14.5). A cross-sectional design was
used to examine the internal consistency (Cronbach’s α) and concurrent validity (Pearson’s product moment correlation r). The application
followed the stages of translation from English to Italian and linguistic adaptation, grammatical and idiomatic equivalence review. To
confirm the external validity of DHI-I, the Pearson correlation test between the total score and single subscales of DHI-I and the 8 scales
of the Short Form Health Survey (SF-36) was performed. The Cronbach α coefficients for internal consistency were 0.92 for the DHI-I and
0.82, 0.84 and 0.75 for the sub-scale functional, emotional and physical, respectively. The frequency distribution of no one item showed
a percentage higher than 75% in a single possible answer (0, 2, 4), excluding a ceiling or floor effect. Correlations with the total score of
DHI-I were consistent and the correlation between total score of DHI-I and total score on SF-36 was -0.593. Of the single subscales, the
emotional scale showed a closer correlation with almost all scales of the SF-36. The correlation between the total score of SF-36 and the
single sub-scale of DHI-I (functional, emotional, physical) were respectively -0.599, -0.563, -0.398. The DHI was culturally and linguistically
adapted for its application in the Italian population. The DHI-I demonstrated a good reliability and is recommended as a measure of
disability in patients with dizziness and unsteadiness. According to the DHI-I, patients with acute dizziness and with a clinical diagnosis of
vestibular syndrome presented a decreased QoL; the physical aspects were the most compromised
One-shot domain adaptation in multiple sclerosis lesion segmentation using convolutional neural networks
In recent years, several convolutional neural network (CNN) methods have been
proposed for the automated white matter lesion segmentation of multiple
sclerosis (MS) patient images, due to their superior performance compared with
those of other state-of-the-art methods. However, the accuracies of CNN methods
tend to decrease significantly when evaluated on different image domains
compared with those used for training, which demonstrates the lack of
adaptability of CNNs to unseen imaging data. In this study, we analyzed the
effect of intensity domain adaptation on our recently proposed CNN-based MS
lesion segmentation method. Given a source model trained on two public MS
datasets, we investigated the transferability of the CNN model when applied to
other MRI scanners and protocols, evaluating the minimum number of annotated
images needed from the new domain and the minimum number of layers needed to
re-train to obtain comparable accuracy. Our analysis comprised MS patient data
from both a clinical center and the public ISBI2015 challenge database, which
permitted us to compare the domain adaptation capability of our model to that
of other state-of-the-art methods. For the ISBI2015 challenge, our one-shot
domain adaptation model trained using only a single image showed a performance
similar to that of other CNN methods that were fully trained using the entire
available training set, yielding a comparable human expert rater performance.
We believe that our experiments will encourage the MS community to incorporate
its use in different clinical settings with reduced amounts of annotated data.
This approach could be meaningful not only in terms of the accuracy in
delineating MS lesions but also in the related reductions in time and economic
costs derived from manual lesion labeling
High Enthalpy Flow Characterization Using Tunable Diode Laser Absorption Spectroscopy
This research aims at analysing thermo-chemical properties of the hypersonic high-enthalpy flow in the L2K wind tunnel, situated in Köln at the German Aerospace Center (DLR). In the L2K wind tunnel, Martian atmosphere can be created, and the facility can simulate heat load conditions encountered during atmospheric entry of Martian missions. The focus of this project is the analysis of the non-intrusive experimental technique "Tunable Diode Laser Absorption Spectroscopy" (TDLAS), based on line of sight absorption spectroscopy, and applied to hypersonic flow. A simplified Martian atmosphere (97% CO2 and 3% N2) was used. A new interpretation for CO-TDLAS experimental technique applied to hypersonic wind tunnel flow analysis was developed. Numerical simulations with the DLR-TAU non-equilibrium flow solver were used as support of this analysis, and match between simulations and experiments was observed. Flow speed and absorption line’s width were measured, and the knowledge of L2K’s flow structure was extended
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