696 research outputs found
Determinants of lung function changes in athletic swimmers. A review.
To summarise lung function characteristics of athletic swimmers and discuss mechanisms explaining these changes while putting forward the lack of a clear understanding of the precise physiological factors implicated.
Literature search until 07.2021 on Medline and EMBASE using keywords swimming, athletes, respiratory physiology, lung development, lung function tests. Relevant articles in French and English were reviewed.
We found insufficient data to perform a meta-analysis. However, there is evidence that swimmers have better expiratory flows and increased baseline lung volumes than non-athletes or non-swimmers. Although these features can result from changes in lung development following intense training over the years, the contribution of a genetic predisposition and positive selection cannot be totally excluded.
Disentangling the participation of constitutional factors and years of hard training to explain the larger lung volumes of athletic swimmers is in favour of an adaptative response of the lungs to early swim training through modification of the pathway of lung development. There seems to be an optimal window of opportunity before the end of growth for these adaptational changes to occur. Precise mechanisms, and contribution of adaptative change on lung physiology, remain to be further studied
Interaction of surface acoustic waves with a two-dimensional electron gas in the presence of spin splitting of the Landau bands
The absorption and variation of the velocity of a surface acoustic wave of
frequency = 30 MHz interacting with two-dimensional electrons are
investigated in GaAs/AlGaAs heterostructures with an electron density at =1.5 - 4.2 K in magnetic fields up to 7 T.
Characteristic features associated with spin splitting of the Landau level are
observed. The effective g factor and the width of the spin-split Landau bands
are determined: and =0.6 meV. The greater width of the
orbital-split Landau bands (2 meV) relative to the spin-split bands is
attributed to different shielding of the random fluctuation potential of
charged impurities by 2D electrons. The mechanisms of the nonlinearities
manifested in the dependence of the absorption and the velocity increment of
the SAW on the SAW power in the presence of spin splitting of the Landau levels
are investigated.Comment: Revtex 5 pages + 5 EPS Figures, v.2 - minor corrections in text and
pic
Electron localization in sound absorption oscillations in the quantum Hall effect regime
The absorption coefficient for surface acoustic waves in a piezoelectric
insulator in contact with a GaAs/AlGaAs heterostructure (with two-dimensional
electron mobility at T=4.2K) via a small
gap has been investigated experimentally as a function of the frequency of the
wave, the width of the vacuum gap, the magnetic field, and the temperature. The
magnetic field and frequency dependencies of the high-frequency conductivity
(in the region 30-210 MHz) are calculated and analyzed. The experimental
results can be explained if it assumed that there exists a fluctuation
potential in which current carrier localization occurs. The absorption of the
surface acoustic waves in an interaction with two-dimensional electrons
localized in the energy "tails" of Landau levels is discussed.Comment: RevTeX 6 pages+6 EPS pic
Magnetism, Spin-Orbit Coupling, and Superconducting Pairing in UGe
A consistent picture on the mean-field level of the magnetic properties and
electronic structure of the superconducting itinerant ferromagnet UGe is
shown to require inclusion of correlation effects beyond the local density
approximation (LDA). The "LDA+U" approach reproduces both the magnitude of the
observed moment, composed of strongly opposing spin and orbital parts, and the
magnetocrystalline anisotropy. The largest Fermi surface sheet is comprised
primarily of spin majority states with orbital projection =0,
suggesting a much simpler picture of the pairing than is possible for general
strong spin-orbit coupled materials. This occurrence, and the
quasi-two-dimensional geometry of the Fermi surface, support the likelihood of
magnetically mediated p-wave triplet pairing.Comment: accepted for publication in Phys. Rev. Lett; URL for better quality
image of Fig.3 (2MB) at http://yammer.ucdavis.edu/public/UGe2/fig3.ep
Orbital-based Scenario for Magnetic Structure of Neptunium Compounds
In order to understand a crucial role of orbital degree of freedom in the
magnetic structure of recently synthesized neptunium compounds NpTGa_5 (T=Fe,
Co, and Ni), we propose to discuss the magnetic phase of an effective
two-orbital model, which has been constructed based on a j-j coupling scheme to
explain the magnetic structure of uranium compounds UTGa_5. By analyzing the
model with the use of numerical technique such as exact diagonalization, we
obtain the phase diagram including several kinds of magnetic states. An
orbital-based scenario is discussed to understand the change in the magnetic
structure among C-, A-, and G-type antiferromagnetic phases, experimentally
observed in NpFeGa_5, NpCoGa_5, and NpNiGa_5.Comment: 18 pages, 8 figures, to appear in New Journal of Physic
A comparative analysis of job quality among immigrant workers in Europe : who is accessing to better jobs?
Project-based, collaborative, algorithmic robotics for high school students: Programming self-driving race cars at MIT
We describe the pedagogy behind the MIT Beaver Works Summer Institute Robotics Program, a new high-school STEM program in robotics. The program utilizes state-of-the-art sensors and embedded computers for mobile robotics. These components are carried on an exciting 1/10-scale race-car platform. The program has three salient, distinguishing features: (i) it focuses on robotics software systems: the students design and build robotics software towards real-world applications, without being distracted by hardware issues; (ii) it champions project-based learning: the students learn through weekly project assignments and a final course challenge; (iii) the learning is implemented in a collaborative fashion: the students learn the basics of collaboration and technical communication in lectures, and they work in teams to design and implement their software systems. The program was offered as a four-week residential program at MIT in the summer of 2016. In this paper, we provide the details of this new program, its teaching objectives, and its results. We also briefly discuss future directions and opportunities
Regulatory de novo mutations underlying intellectual disability
The genetic aetiology of a major fraction of patients with intellectual disability (ID) remains unknown. De novo mutations (DNMs) in protein-coding genes explain up to 40% of cases, but the potential role of regulatory DNMs is still poorly understood. We sequenced 63 whole genomes from 21 ID probands and their unaffected parents. In addition, we analysed 30 previously sequenced genomes from exome-negative ID probands. We found that regulatory DNMs were selectively enriched in fetal brain-specific enhancers as compared with adult brain enhancers. DNM-containing enhancers were associated with genes that show preferential expression in the prefrontal cortex. Furthermore, we identified recurrently mutated enhancer clusters that regulate genes involved in nervous system development (CSMD1, OLFM1, and POU3F3). Most of the DNMs from ID probands showed allele-specific enhancer activity when tested using luciferase assay. Using CRISPR-mediated mutation and editing of epigenomic marks, we show that DNMs at regulatory elements affect the expression of putative target genes. Our results, therefore, provide new evidence to indicate that DNMs in fetal brain-specific enhancers play an essential role in the aetiology of ID
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