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Search Results: 1 - 10 of 85946 matches for " Brandon W. Carr "
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Protein Phosphatase 1 β Paralogs Encode the Zebrafish Myosin Phosphatase Catalytic Subunit
Vaishali Jayashankar, Michael J. Nguyen, Brandon W. Carr, Dale C. Zheng, Joseph B. Rosales, Joshua B. Rosales, Douglas C. Weiser
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075766
Abstract: Background The myosin phosphatase is a highly conserved regulator of actomyosin contractility. Zebrafish has emerged as an ideal model system to study the in vivo role of myosin phosphatase in controlling cell contractility, cell movement and epithelial biology. Most work in zebrafish has focused on the regulatory subunit of the myosin phosphatase called Mypt1. In this work, we examined the critical role of Protein Phosphatase 1, PP1, the catalytic subunit of the myosin phosphatase. Methodology/Principal Findings We observed that in zebrafish two paralogous genes encoding PP1β, called ppp1cba and ppp1cbb, are both broadly expressed during early development. Furthermore, we found that both gene products interact with Mypt1 and assemble an active myosin phosphatase complex. In addition, expression of this complex results in dephosphorylation of the myosin regulatory light chain and large scale rearrangements of the actin cytoskeleton. Morpholino knock-down of ppp1cba and ppp1cbb results in severe defects in morphogenetic cell movements during gastrulation through loss of myosin phosphatase function. Conclusions/Significance Our work demonstrates that zebrafish have two genes encoding PP1β, both of which can interact with Mypt1 and assemble an active myosin phosphatase. In addition, both genes are required for convergence and extension during gastrulation and correct dosage of the protein products is required.
Effect of temperature on quantum criticality in the frustrated two-leg Heisenberg ladder
Brandon W. Ramakko,Mohamed Azzouz
Physics , 2007, DOI: 10.1103/PhysRevB.76.064419
Abstract: The antiferromagnetic Heisenberg model on the two-leg ladder with exchange interactions along the chains, rungs, and diagonals is studied using the Jordan-Wigner transformation and bond-mean-field theory. The inclusion of all three couplings introduces frustration to the system and depending on their relative strengths the ladder can adopt one of three possible magnetically-disordered gapped states. The phase diagram found in this mean-field approach is in very good agreement with the one calculated by Weihong and colleagues using the Lanczos exact diagonalization method. By analyzing the ground-state energy we study quantum criticality when the coupling parameters are varied at zero temperature. We study the effect of temperature on the phase boundaries, and find that the system shows thermally-induced criticality for some values of the rung and diagonal coupling constants. All the phase transitions encountered in this system occur between disordered phases, and are all caused by frustration.
Quantum and classical criticalities in the frustrated two-leg Heisenberg ladder
Mohamed Azzouz,Brandon W. Ramakko
Physics , 2007, DOI: 10.1139/P08-003
Abstract: This talk was about the frustration-induced criticality in the antiferromagnetic Heisenberg model on the two-leg ladder with exchange interactions along the chains, rungs, and diagonals, and also about the effect of thermal fluctuations on this criticlity. The method used is the bond mean-field theory, which is based on the Jordan-Wigner transformation in dimensions higher than one. In this paper, we will summarize the main results presented in this talk, and report on new results about the couplings and temperature dependences of the spin susceptibility.
Interplay between field-induced and frustration-induced quantum criticalities in the frustrated two-leg Heisenberg ladder
Brandon W. Ramakko,Mohamed Azzouz
Physics , 2007, DOI: 10.1139/P08-050
Abstract: The antiferromagnetic Heisenberg two-leg ladder in the presence of frustration and an external magnetic field is a system that is characterized by two sorts of quantum criticalities, not only one. One criticality is the consequence of intrinsic frustration, and the other one is a result of the external magnetic field. So the behaviour of each of them in the presence of the other deserves to be studied. Using the Jordan-Wigner transformation in dimensions higher than one and bond-mean-field theory we examine the interplay between the field-induced and frustration-induced quantum criticalities in this system. The present work could constitute a prototype for those systems showing multiple, perhaps sometimes competing, quantum criticalities. We calculate several physical quantities like the magnetization and spin susceptibility as functions of field and temperature.
Differentiating solutions to the gauge hierarchy problem through rare muon decays
David W. Maybury,Brandon Murakami
Physics , 2004,
Abstract: We demonstrate the potential of forthcoming mu -> e gamma and mu-e conversion experiments to implicate or disfavor solutions to the gauge hierarchy problem before the advent of the CERN Large Hadron Collider. Solutions of dynamical electroweak symmetry breaking, little Higgs, supersymmetry, and extra dimensions are considered. Correlations of mu -> e gamma and mu-e conversion branching ratios are analyzed for discriminating patterns. Measurements of these exotic muon decays may have compelling implications for supersymmetric solutions.
Doubly magic trapping for Cs atom hyperfine clock transitions
A. W. Carr,M. Saffman
Physics , 2014,
Abstract: We analyze doubly magic trapping of Cs hyperfine transitions including previously neglected contributions from the ground state hyperpolarizability and the interaction of the laser light and a static magnetic field. Extensive numerical searches do not reveal any doubly magic trapping conditions for any pair of hyperfine states. However, including the hyperpolarizability reveals light intensity insensitive traps for a wide range of wavelengths at specific intensities. We then investigate the possibility of using bichromatic trapping light fields. Deploying a bichromatic scheme, we demonstrate doubly magic red and blue detuned traps for pairs of states separated by one or two single photon transitions.
Preparation of entangled and antiferromagnetic states by dissipative Rydberg pumping
A. W. Carr,M. Saffman
Physics , 2013, DOI: 10.1103/PhysRevLett.111.033607
Abstract: We propose and analyze an approach for preparation of high fidelity entanglement and antiferromagnetic states using Rydberg mediated interactions with dissipation. Using asymmetric Rydberg interactions the two-atom Bell singlet is a dark state of the Rydberg pumping process. Master equation simulations demonstrate Bell singlet preparation fidelity $\mcF=0.998$. Antiferromagnetic states are generated on a four spin plaquette in agreement with results found from diagonalization of the transverse field Ising Hamiltonian.
Differential Modulation of TCF/LEF-1 Activity by the Soluble LRP6-ICD
Brandon Beagle,Gail V. W. Johnson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011821
Abstract: The canonical Wnt/β-catenin (Wnt) pathway is a master transcriptional regulatory signaling pathway that controls numerous biological processes including proliferation and differentiation. As such, transcriptional activity of the Wnt pathway is tightly regulated and/or modulated by numerous proteins at the level of the membrane, cytosol and/or nucleus. In the nucleus, transcription of Wnt target genes by TCF/LEF-1 is repressed by the long Groucho/TLE co-repressor family. However, a truncated member of the Groucho/TLE family, amino terminal enhancer of Split (AES) can positively modulate TCF/LEF-1 activity by antagonizing long Groucho/TLE members in a dominant negative manner. We have previously shown the soluble intracellular domain of the LRP6 receptor, a receptor required for activation of the Wnt pathway, can positively regulate transcriptional activity within the Wnt pathway. In the current study, we show the soluble LRP6 intracellular domain (LRP6-ICD) can also translocate to the nucleus in CHO and HEK 293T cells and in contrast to cytosolic LRP6-ICD; nuclear LRP6-ICD represses TCF/LEF-1 activity. In agreement with previous reports, we show AES enhances TCF/LEF-1 mediated reporter transcription and further we demonstrate that AES activity is spatially regulated in HEK 293T cells. LRP6-ICD interacts with AES exclusively in the nucleus and represses AES mediated TCF/LEF-1 reporter transcription. These results suggest that LRP6-ICD can differentially modulate Wnt pathway transcriptional activity depending upon its subcellular localization and differential protein-protein interactions.
Sources of Bias in Teacher Ratings of Adolescents with ADHD
Brandon K. Schultz,Steven W. Evans
Journal of Educational and Developmental Psychology , 2012, DOI: 10.5539/jedp.v2n1p151
Abstract: Best practice assessment of childhood ADHD includes behavior ratings from multiple sources across multiple environments. However, adolescents in secondary schools interact with several teachers each day, and research has shown that teacher perceptions of the same child can be highly inconsistent. As a result, rating scale data can be equivocal, depending on which teachers are selected. The intent of the present study was two-fold: 1) to assess the consistency between teacher behavior ratings of adolescents with ADHD, and 2) to explore predictors of rater leniency or severity (i.e., sources of bias). Results suggest that interrater reliability within our sample was moderate, consistent with previous research. Further, teacher characteristics, including sex and age, were related to biases on ratings of student hyperactivity-impulsivity. Specifically, women and younger teachers provided significantly more severe ratings on average than did men and older teachers. Implications for the interpretation and statistical norming of ADHD rating scales are discussed.
CallSim: Evaluation of Base Calls Using Sequencing Simulation
Jarrett D. Morrow,Brandon W. Higgs
ISRN Bioinformatics , 2012, DOI: 10.5402/2012/371718
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