525 research outputs found
Theory of the c-Axis Penetration Depth in the Cuprates
Recent measurements of the London penetration depth tensor in the cuprates
find a weak temperature dependence along the c-direction which is seemingly
inconsistent with evidence for d-wave pairing deduced from in-plane
measurements. We demonstrate in this paper that these disparate results are not
in contradiction, but can be explained within a theory based on incoherent
quasiparticle hopping between the CuO2 layers. By relating the calculated
temperature dependence of the penetration depth \lambda_c(T) to the c-axis
resistivity, we show how the measured ratio \lambda_c^2(0) / \lambda_c^2(T) can
provide insight into the behavior of c-axis transport below Tc and the related
issue of ``confinement.''Comment: 4 pages, REVTEX with psfig, 3 PostScript figures included in
compressed for
Normal-superconducting transition induced by high current densities in YBa2Cu3O7-d melt-textured samples and thin films: Similarities and differences
Current-voltage characteristics of top seeded melt-textured YBa2Cu3O7-d are
presented. The samples were cut out of centimetric monoliths. Films
characteristics were also measured on microbridges patterned on thin films
grown by dc sputtering. For both types of samples, a quasi-discontinuity or
quenching was observed for a current density J* several times the critical
current density Jc. Though films and bulks much differ in their magnitude of
both Jc and J*, a proposal is made as to a common intrinsic origin of the
quenching phenomenon. The unique temperature dependence observed for the ratio
J*/Jc, as well as the explanation of the pre-quenching regime in terms of a
single dissipation model lend support to our proposal.Comment: 10 pages, 10 figures, submitted to Physical Review
Deletion of SA β-Gal+ Cells Using Senolytics Improves Muscle Regeneration in Old Mice
Systemic deletion of senescent cells leads to robust improvements in cognitive, cardiovascular, and whole-body metabolism, but their role in tissue reparative processes is incompletely understood. We hypothesized that senolytic drugs would enhance regeneration in aged skeletal muscle. Young (3 months) and old (20 months) male C57Bl/6J mice were administered the senolytics dasatinib (5 mg/kg) and quercetin (50 mg/kg) or vehicle bi-weekly for 4 months. Tibialis anterior (TA) was then injected with 1.2% BaCl2 or PBS 7- or 28 days prior to euthanization. Senescence-associated β-Galactosidase positive (SA β-Gal+) cell abundance was low in muscle from both young and old mice and increased similarly 7 days following injury in both age groups, with no effect of D+Q. Most SA β-Gal+ cells were also CD11b+ in young and old mice 7- and 14 days following injury, suggesting they are infiltrating immune cells. By 14 days, SA β-Gal+/CD11b+ cells from old mice expressed senescence genes, whereas those from young mice expressed higher levels of genes characteristic of anti-inflammatory macrophages. SA β-Gal+ cells remained elevated in old compared to young mice 28 days following injury, which were reduced by D+Q only in the old mice. In D+Q-treated old mice, muscle regenerated following injury to a greater extent compared to vehicle-treated old mice, having larger fiber cross-sectional area after 28 days. Conversely, D+Q blunted regeneration in young mice. In vitro experiments suggested D+Q directly improve myogenic progenitor cell proliferation. Enhanced physical function and improved muscle regeneration demonstrate that senolytics have beneficial effects only in old mice
Computational exploration of molecular receptive fields in the olfactory bulb reveals a glomerulus-centric chemical map
© The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.Progress in olfactory research is currently hampered by incomplete knowledge about chemical receptive ranges of primary receptors. Moreover, the chemical logic underlying the arrangement of computational units in the olfactory bulb has still not been resolved. We undertook a large-scale approach at characterising molecular receptive ranges (MRRs) of glomeruli in the dorsal olfactory bulb (dOB) innervated by the MOR18-2 olfactory receptor, also known as Olfr78, with human ortholog OR51E2. Guided by an iterative approach that combined biological screening and machine learning, we selected 214 odorants to characterise the response of MOR18-2 and its neighbouring glomeruli. We found that a combination of conventional physico-chemical and vibrational molecular descriptors performed best in predicting glomerular responses using nonlinear Support-Vector Regression. We also discovered several previously unknown odorants activating MOR18-2 glomeruli, and obtained detailed MRRs of MOR18-2 glomeruli and their neighbours. Our results confirm earlier findings that demonstrated tunotopy, that is, glomeruli with similar tuning curves tend to be located in spatial proximity in the dOB. In addition, our results indicate chemotopy, that is, a preference for glomeruli with similar physico-chemical MRR descriptions being located in spatial proximity. Together, these findings suggest the existence of a partial chemical map underlying glomerular arrangement in the dOB. Our methodology that combines machine learning and physiological measurements lights the way towards future high-throughput studies to deorphanise and characterise structure-activity relationships in olfaction.Peer reviewe
Frequency Characteristics of Visually Induced Motion Sickness
This article was published in the journal, Human Factors [Sage Publications / © Human Factors and Ergonomics Society.]. The definitive version is available at: http://dx.doi.org/10.1177/0018720812469046Objective: The aim of this study was to explore
the frequency response of visually induced motion
sickness (VIMS) for oscillating linear motion in the foreand-
aft axis.
Background: Simulators, virtual environments,
and commercially available video games that create an
illusion of self-motion are often reported to induce
the symptoms seen in response to true motion. Often
this human response can be the limiting factor in the
acceptability and usability of such systems. Whereas
motion sickness in physically moving environments
is known to peak at an oscillation frequency around
0.2 Hz, it has recently been suggested that VIMS peaks
at around 0.06 Hz following the proposal that the
summed response of the visual and vestibular selfmotion
systems is maximized at this frequency. Methods: We exposed 24 participants to random
dot optical flow patterns simulating oscillating foreand-
aft motion within the frequency range of 0.025 to
1.6 Hz. Before and after each 20-min exposure, VIMS was
assessed with the Simulator Sickness Questionnaire.
Also, a standard motion sickness scale was used to rate
symptoms at 1-min intervals during each trial.
Results: VIMS peaked between 0.2 and 0.4 Hz with
a reducing effect at lower and higher frequencies.
Conclusion: The numerical prediction of the
“crossover frequency” hypothesis, and the design
guidance curve previously proposed, cannot be accepted
when the symptoms are purely visually induced.
Application: In conditions in which stationary
observers are exposed to optical flow that simulates
oscillating fore-and-aft motion, frequencies around 0.2
to 0.4 Hz should be avoided
C-jun Inhibits Mammary Apoptosis In Vivo
c-Jun mediates ROS production and apoptosis
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