357 research outputs found
Anomalous Roughening of Viscous Fluid Fronts in Spontaneous Imbibition
We report experiments on spontaneous imbibition of a viscous fluid by a model
porous medium in the absence of gravity. The average position of the interface
satisfies Washburn's law. Scaling of the interface fluctuations provides a
dynamic exponent z \simeq 3, indicative of global dynamics driven by capillary
forces. The complete set of exponents clearly shows that interfaces are not
self-affine, exhibiting distinct local and global scaling, both for time
(b=0.64\pm 0.02, b* =0.33 \pm 0.03) and space (a=1.94 \pm 0.20, a_loc=0.94 \pm
0.10). These values are compatible with an intrinsic anomalous scaling
scenario.Comment: 4 pages, 5 figure
KAP1 targets actively transcribed genomic loci to exert pleomorphic effects on RNA polymerase II activity
KAP1 (KRAB-associated protein 1) is best known as a co-repressor responsible for inducing heterochromatin formation, notably at transposable elements. However, it has also been observed to bind the transcription start site of actively expressed genes. To address this paradox, we characterized the protein interactome of KAP1 in the human K562 erythro-leukaemia cell line. We found that the regulator can associate with a wide range of nucleic acid binding proteins, nucleosome remodellers, chromatin modifiers and other transcription modulators. We further determined that KAP1 is recruited at actively transcribed polymerase II promoters, where its depletion resulted in pleomorphic effects, whether expression of these genes was normally constitutive or inducible, consistent with the breadth of possible KAP1 interactors.
This article is part of a discussion meeting issue 'Crossroads between transposons and gene regulation'
When high similarity copycats lose and moderate similarity copycats gain: The impact of comparative evaluation
Copycats imitate features of leading brands to free ride on their equity. The prevailing belief is that the more similar copycats are to the leader brand, the more positive their evaluation is, and thus the more they free ride. Three studies demonstrate when the reverse holds true: Moderate-similarity copycats are actually evaluated more positively than high-similarity copycats when evaluation takes place comparatively, such as when the leader brand is present rather than absent. The results demonstrate that blatant copycats can be less and subtle copycats can be more perilous than is commonly believed. This finding has implications for marketing theory and practice and trademark law
Interferometric Observatories in Earth Orbit
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76217/1/AIAA-1728-623.pd
Automated simultaneous analysis phylogenetics (ASAP) : an enabling tool for phlyogenomics
© 2008 Sarkar et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The definitive version was published in BMC Bioinformatics 9 (2008): 103, doi:10.1186/1471-2105-9-103.The availability of sequences from whole genomes to reconstruct the tree of life has the potential to enable the development of phylogenomic hypotheses in ways that have not been before possible. A significant bottleneck in the analysis of genomic-scale views of the tree of life is the time required for manual curation of genomic data into multi-gene phylogenetic matrices.
To keep pace with the exponentially growing volume of molecular data in the genomic era, we have developed an automated technique, ASAP (Automated Simultaneous Analysis Phylogenetics), to assemble these multigene/multi species matrices and to evaluate the significance of individual genes within the context of a given phylogenetic hypothesis.
Applications of ASAP may enable scientists to re-evaluate species relationships and to develop new phylogenomic hypotheses based on genome-scale data.This work is funded in part by NSF DBI-0421604 to GC and RD. INS is supported in part by the Ellison Medical Foundation
Limits on Stellar and Planetary Companions in Microlensing Event OGLE-1998-BUL-14
We present the PLANET photometric data set for \ob14, a high magnification
() event alerted by the OGLE collaboration toward the
Galactic bulge in 1998. The PLANET data set consists a total of 461 I-band and
139 band points, the majority of which was taken over a three month period.
The median sampling interval during this period is about 1 hour, and the
scatter over the peak of the event is 1.5%. The excellent data
quality and high maximum magnification of this event make it a prime candidate
to search for the short duration, low amplitude perturbations that are
signatures of a planetary companion orbiting the primary lens. The observed
light curve for \ob14 is consistent with a single lens (no companion) within
photometric uncertainties. We calculate the detection efficiency of the light
curve to lensing companions as a function of the mass ratio and angular
separation of the two components. We find that companions of mass ratio are ruled out at the 95% confidence level for projected separations
between 0.4-2.4 \re, where \re is the Einstein ring radius of the primary
lens. Assuming that the primary is a G-dwarf with \re\sim3 {\rm AU} our
detection efficiency for this event is for a companion with the mass
and separation of Jupiter and for a companion with the mass and
separation of Saturn. Our efficiencies for planets like those around Upsilon
And and 14 Her are > 75%.Comment: Data available at http://www.astro.rug.nl/~planet/planetpapers.html
20 pages, 10 figures. Minor changes. ApJ, accepte
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