80 research outputs found
Strong 3D correlations in vortex system of Bi2212:Pb
The experimental study of magnetic flux penetration under crossed magnetic
fields in Bi2212:Pb single crystal performed by magnetooptic technique (MO)
reveals remarkable field penetration pattern alteration (flux configuration
change) and superconducting current anisotropy enhancement by the in-plane
field. The anisotropy increases with the temperature rise up to . At an abrupt change in the flux behavior is found; the
correlation between the in-plane magnetic field and the out-of-plane magnetic
flux penetration disappears. No correlation is observed for . The
transition temperature does not depend on the magnetic field strength.
The observed flux penetration anisotropy is considered as an evidence of a
strong 3D - correlation between pancake vortices in different CuO planes at . This enables understanding of a remarkable pinning observed in
Bi2212:Pb at low temperatures.Comment: 8 pages, 9 figure
First-order disorder-driven transition and inverse melting of the vortex lattice
Vortex matter phase transitions in the high-temperature superconductor
Bi2Sr2CaCu2O8 were studied using local magnetization measurements combined with
a vortex 'shaking' technique. The measurements revealed thermodynamic evidence
of a first-order transition along the second magnetization peak line, at
temperatures below the apparent critical point Tcp. We found that the
first-order transition line does not terminate at Tcp, but continues down to at
least 30 K. This observation suggests that the ordered vortex lattice phase is
destroyed through a unified first-order transition that changes its character
from thermally induced melting at high temperatures to a disorder-induced
transition at low temperatures. At intermediate temperatures the transition
line shows an upturn, which implies that the vortex matter displays 'inverse'
melting behavior.Comment: 9 pages, 6 figures, Physica C, in pres
Brownian motion: a paradigm of soft matter and biological physics
This is a pedagogical introduction to Brownian motion on the occasion of the
100th anniversary of Einstein's 1905 paper on the subject. After briefly
reviewing Einstein's work in its contemporary context, we pursue some lines of
further developments and applications in soft condensed matter and biology.
Over the last century Brownian motion became promoted from an odd curiosity of
marginal scientific interest to a guiding theme pervading all of the modern
(live) sciences.Comment: 30 pages, revie
News framing effects on destination risk perception
News coverage of hazards is often commented to be of critical importance to individuals' perceived risk associated with tourist destinations. Despite the significance of this issue to the global tourism industry, the link between portrayals of hazards and audience reception is rarely studied in this context. This study adopted the framing theory to evaluate media effect on tourists' perceived risk of portrayals of terrorism and political instability incidents. This involved a survey-embedded experiment which manipulated potential elements of a news report concerning a hazard. The content of fictitious articles used in the experiment was created on the basis of extant risk perception theories. Results revealed that the use of risk amplifying frame and risk attenuating frame result in higher and lower ratings of risk respectively. Moreover, tourist psychographic characteristics were found to moderate the influence of news frames on perceived risk. Implications for tourism destination managers and marketers were discussed
A Myo6 Mutation Destroys Coordination between the Myosin Heads, Revealing New Functions of Myosin VI in the Stereocilia of Mammalian Inner Ear Hair Cells
Myosin VI, found in organisms from Caenorhabditis elegans to humans, is essential for auditory and vestibular function in mammals, since genetic mutations lead to hearing impairment and vestibular dysfunction in both humans and mice. Here, we show that a missense mutation in this molecular motor in an ENU-generated mouse model, Tailchaser, disrupts myosin VI function. Structural changes in the Tailchaser hair bundles include mislocalization of the kinocilia and branching of stereocilia. Transfection of GFP-labeled myosin VI into epithelial cells and delivery of endocytic vesicles to the early endosome revealed that the mutant phenotype displays disrupted motor function. The actin-activated ATPase rates measured for the D179Y mutation are decreased, and indicate loss of coordination of the myosin VI heads or ‘gating’ in the dimer form. Proper coordination is required for walking processively along, or anchoring to, actin filaments, and is apparently destroyed by the proximity of the mutation to the nucleotide-binding pocket. This loss of myosin VI function may not allow myosin VI to transport its cargoes appropriately at the base and within the stereocilia, or to anchor the membrane of stereocilia to actin filaments via its cargos, both of which lead to structural changes in the stereocilia of myosin VI–impaired hair cells, and ultimately leading to deafness
Vortex phase diagram in BSCCO with damage tracks created by 30 MeV fullerene irradiation
Using 30 MeV C60 fullerene irradiation, we have produced latent tracks of
diameter 20 nm and length 200 nm, near the surface of single crystalline BSCCO.
A preliminary transmission electron microscopy study shows evidence for a very
high density of deposited energy, and the ejection of material from the track
core in very thin specimens. The latent tracks reveal themselves to be
exceptionally strong pinning centers for vortices in the superconducting mixed
state. Both the critical current density and magnetic irreversibility line are
significantly enhanced. The irradiated crystals present salient features of the
(B,T) phase diagram of vortex matter both of pristine crystals, such as the
first order vortex phase transition, and the exponential Bose-glass line
characteristic of heavy ion-irradiated crystals. We show that the latter is
manifestly independent of the pinning potential.Comment: 10 pages, 13 figure
Transcriptional Dynamics Reveal Critical Roles for Non-coding RNAs in the Immediate-Early Response
<div><p>The immediate-early response mediates cell fate in response to a variety of extracellular stimuli and is dysregulated in many cancers. However, the specificity of the response across stimuli and cell types, and the roles of non-coding RNAs are not well understood. Using a large collection of densely-sampled time series expression data we have examined the induction of the immediate-early response in unparalleled detail, across cell types and stimuli. We exploit cap analysis of gene expression (CAGE) time series datasets to directly measure promoter activities over time. Using a novel analysis method for time series data we identify transcripts with expression patterns that closely resemble the dynamics of known immediate-early genes (IEGs) and this enables a comprehensive comparative study of these genes and their chromatin state. Surprisingly, these data suggest that the earliest transcriptional responses often involve promoters generating non-coding RNAs, many of which are produced in advance of canonical protein-coding IEGs. IEGs are known to be capable of induction without de novo protein synthesis. Consistent with this, we find that the response of both protein-coding and non-coding RNA IEGs can be explained by their transcriptionally poised, permissive chromatin state prior to stimulation. We also explore the function of non-coding RNAs in the attenuation of the immediate early response in a small RNA sequencing dataset matched to the CAGE data: We identify a novel set of microRNAs responsible for the attenuation of the IEG response in an estrogen receptor positive cancer cell line. Our computational statistical method is well suited to meta-analyses as there is no requirement for transcripts to pass thresholds for significant differential expression between time points, and it is agnostic to the number of time points per dataset.</p></div
Stimulus-dependent differences in signalling regulate epithelial-mesenchymal plasticity and change the effects of drugs in breast cancer cell lines
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