1,109 research outputs found
In-Chain Tunneling Through Charge-Density Wave Nanoconstrictions and Break-Junctions
We have fabricated longitudinal nanoconstrictions in the charge-density wave
conductor (CDW) NbSe using a focused ion beam and using a mechanically
controlled break-junction technique. Conductance peaks are observed below the
TK and TK CDW transitions, which correspond closely
with previous values of the full CDW gaps and
obtained from photo-emission. These results can be explained by assuming
CDW-CDW tunneling in the presence of an energy gap corrugation
comparable to , which eliminates expected peak at
. The nanometer length-scales our experiments imply
indicate that an alternative explanation based on tunneling through
back-to-back CDW-normal junctions is unlikely.Comment: 5 pages, 3 figures, submitted to physical review letter
Boundary effect on CDW: Friedel oscillations, STM image
We study the effect of open boundary condition on charge density waves (CDW).
The electron density oscillates rapidly close to the boundary, and additional
non-oscillating terms (~ln(r)) appear. The Friedel oscillations survive beyond
the CDW coherence length (v_F/Delta), but their amplitude gets heavily
suppressed. The scanning tunneling microscopy image (STM) of CDW shows clear
features of the boundary. The local tunneling conductance becomes asymmetric
with respect to the Fermi energy, and considerable amount of spectral weight is
transferred to the lower gap edge. Also it exhibits additional zeros reflecting
the influence of the boundary.Comment: 7 pages, 6 figure
Deep Saturated Free Electron Laser Oscillators and Frozen Spikes
We analyze the behavior of Free Electron Laser (FEL) oscillators operating in
the deep saturated regime and point out the formation of sub-peaks of the
optical pulse. They are very stable configurations, having a width
corresponding to a coherence length. We speculate on the physical mechanisms
underlying their growth and attempt an identification with FEL mode locked
structures associated with Super Modes. Their impact on the intra-cavity
nonlinear harmonic generation is also discussed along with the possibility of
exploiting them as cavity out-coupler.Comment: 28 page
Habitual physical activity and cardiometabolic risk factors in adults with cerebral palsy
2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license(http://creativecommons.org/licenses/by/3.0/).This article has been made available through the Brunel Open Access Publishing Fund.Adults with cerebral palsy (CP) are known to participate in reduced levels of total physical activity. There is no information available however, regarding levels of moderate-to-vigorous physical activity (MVPA) in this population. Reduced participation in MVPA is associated with several cardiometabolic risk factors. The purpose of this study was firstly to compare levels of sedentary, light, MVPA and total activity in adults with CP to adults without CP. Secondly, the objective was to investigate the association between physical activity components, sedentary behavior and cardiometabolic risk factors in adults with CP. Adults with CP (n = 41) age 18–62 yr (mean ± SD = 36.5 ± 12.5 yr), classified in Gross Motor Function Classification System level I (n = 13), II (n = 18) and III (n = 10) participated in this study. Physical activity was measured by accelerometry in adults with CP and in age- and sex-matched adults without CP over 7 days. Anthropometric indicators of obesity, blood pressure and several biomarkers of cardiometabolic disease were also measured in adults with CP. Adults with CP spent less time in light, moderate, vigorous and total activity, and more time in sedentary activity than adults without CP (p < 0.01 for all). Moderate physical activity was associated with waist-height ratio when adjusted for age and sex (β = −0.314, p < 0.05). When further adjustment was made for total activity, moderate activity was associated with waist-height ratio (β = −0.538, p < 0.05), waist circumference (β = −0.518, p < 0.05), systolic blood pressure (β = −0.592, p < 0.05) and diastolic blood pressure (β = −0.636, p < 0.05). Sedentary activity was not associated with any risk factor. The findings provide evidence that relatively young adults with CP participate in reduced levels of MVPA and spend increased time in sedentary behavior, potentially increasing their risk of developing cardiometabolic disease
One-dimensional conduction in Charge-Density Wave nanowires
We report a systematic study of the transport properties of coupled
one-dimensional metallic chains as a function of the number of parallel chains.
When the number of parallel chains is less than 2000, the transport properties
show power-law behavior on temperature and voltage, characteristic for
one-dimensional systems.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let
Crossover from 2-dimensional to 1-dimensional collective pinning in NbSe3
We have fabricated NbSe structures with widths comparable to the
Fukuyama-Lee-Rice phase-coherence length. For samples already in the
2-dimensional pinning limit, we observe a crossover from 2-dimensional to
1-dimensional collective pinning when the crystal width is less than 1.6
m, corresponding to the phase-coherence length in this direction. Our
results show that surface pinning is negligible in our samples, and provide a
means to probe the dynamics of single domains giving access to a new regime in
charge-density wave physics.Comment: 4 pages, 2 figures, and 1 table. Accepted for publication in Physical
Review
Safety of Oscillatingâ Rotating Powered Brushes Compared to Manual Toothbrushes: A Systematic Review
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141660/1/jper0005.pd
Thrombin Stimulates Glucose Transport in Human Platelets via the Translocation of the Glucose Transporter GLUT-3 from α-Granules to the Cell Surface
Increased energy metabolism in the circulating blood platelet plays an essential role in platelet plug
formation and clot retraction. This increased energy
consumption is mainly due to enhanced anaerobic consumption of glucose via the glycolytic pathway. The aim
of the present study was to determine the role of glucose transport as a potential rate-limiting step for human platelet glucose metabolism. We measured in isolated platelet preparations the effect of thrombin and
ADP activation, on glucose transport (2-deoxyglucose
uptake), and the cellular distribution of the platelet glucose transporter (GLUT), GLUT-3. Thrombin (0.5
U/ml) caused a pronounced shape change and secretion
of most α-granules within 10 min. During that time glucose transport increased approximately threefold, concomitant with a similar increase in expression of
GLUT-3 on the plasma membrane as observed by immunocytochemistry. A major shift in GLUT-3 labeling
was observed from the α-granule membranes in resting
platelets to the plasma membrane after thrombin treatment. ADP induced shape change but no significant
α-granule secretion. Accordingly, ADP-treated platelets showed no increased glucose transport and no increased GLUT-3 labeling on the plasma membrane.
These studies suggest that, in human blood platelets, increased energy metabolism may be precisely coupled to
the platelet activation response by means of the translocation of GLUT-3 by regulated secretion of α-granules. Observations in megakaryocytes and platelets
freshly fixed from blood confirmed the predominant
GLUT-3 localization in α-granules in the isolated cells,
except that even less GLUT-3 is present at the plasma
membrane in the circulating cells (∼15%), indicating
that glucose uptake may be upregulated five to six
times during in vivo activation of platelets
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