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Search Results: 1 - 10 of 374328 matches for " C. P. Bidinosti "
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Passive Magnetic Shielding in Gradient Fields
C. P. Bidinosti,J. W. Martin
Physics , 2013,
Abstract: The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied. It is found that for concentric cylindrical or spherical shells of high permeability material, higher order multipoles in the magnetic field are shielded progressively better, by a factor related to the order of the multipole. In regard to the design of internal coil systems for the generation of uniform internal fields, we show how one can take advantage of the coupling of the coils to the innermost magnetic shield to further optimize the uniformity of the field. These results demonstrate quantitatively a phenomenon that was previously well-known qualitatively: that the resultant magnetic field within a passively magnetically shielded region can be much more uniform than the applied magnetic field itself. Furthermore we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields close to the outermost magnetic shielding layer. Overall this work provides a comprehensive framework needed to analyze and optimize dc magnetic shields, serving as a theoretical and conceptual design guide as well as a starting point and benchmark for finite-element analysis.
MRI of the lung using hyperpolarized He-3 at very low magnetic field (3 mT)
C. P. Bidinosti,J. Choukeife,G. Tastevin,A. Vignaud,P. -J. Nacher
Physics , 2004,
Abstract: Optical pumping of He-3 produces large (hyper) nuclear-spin polarizations independent of the magnetic resonance imaging (MRI) field strength. This allows lung MRI to be performed at reduced fields with many associated benefits, such as lower tissue susceptibility gradients and decreased power absorption rates. Here we present results of 2D imaging as well as accurate 1D gas diffusion mapping of the human lung using He-3 at very low field (3 mT). Furthermore, measurements of transverse relaxation in zero applied gradient are shown to accurately track pulmonary oxygen partial pressure, opening the way for novel imaging sequences.
Measurements of the Magnetic Field Dependence of Lambda in YBa_2Cu_3O_6.95: Results as a Function of Temperature and Field Orientation
C. P. Bidinosti,W. N. Hardy,D. A. Bonn,Ruixing Liang
Physics , 1998, DOI: 10.1103/PhysRevLett.83.3277
Abstract: We present measurements of the magnetic field dependence of the penetration depth Lambda(H) for untwinned YBa_2Cu_3O_6.95 for temperatures from 1.2 to 70 K in dc fields up to 42 gauss and directions 0, 45 and 90 degrees with respect to the crystal b-axis. The experiment uses an ac susceptometer with fields applied parallel to the ab-plane of thin platelet samples. The resolution is about 0.15 Angstroms in zero dc field, degrading to 0.2 or 0.3 Angstroms at the higher fields. At low temperatures the field dependencies are essentially linear in H, ranging from 0.04 Angstroms/gauss for Delta-Lambda_a to 0.10 Angstroms/gauss for Delta-Lambda_b, values comparable to the T=0 Yip and Sauls prediction for a d-wave superconductor. However, the systematics versus temperature and orientation do not agree with the d-wave scenario probably due, in part, to residual sample problems.
CeCoIn5 - a quantum critical superfluid
S. Ozcan,D. M. Broun,B. Morgan,R. K. W. Haselwimmer,J. R. Waldram,J. L. Sarrao,Saeid Kamal,C. P. Bidinosti,P. J. Turner
Physics , 2002, DOI: 10.1209/epl/i2003-00411-9
Abstract: We have made the first complete measurements of the London penetration depth $\lambda(T)$ of CeCoIn5, a quantum-critical metal where superconductivity arises from a non-Fermi-liquid normal state. Using a novel tunnel diode oscillator designed to avoid spurious contributions to $\lambda(T)$, we have established the existence of intrinsic and anomalous power-law behaviour at low temperature. A systematic analysis raises the possibility that the unusual observations are due to an extension of quantum criticality into the superconducting state.
Phenomenology of a-axis and b-axis charge dynamics from microwave spectroscopy of highly ordered YBa2Cu3O6.50 and YBa2Cu3O6.993
R. Harris,P. J. Turner,Saeid Kamal,A. R. Hosseini,P. Dosanjh,G. K. Mullins,J. S. Bobowski,C. P. Bidinosti,D. M. Broun,Ruixing Liang,W. N. Hardy,D. A. Bonn
Physics , 2006, DOI: 10.1103/PhysRevB.74.104508
Abstract: Extensive measurements of the microwave conductivity of highly pure and oxygen-ordered \YBCO single crystals have been performed as a means of exploring the intrinsic charge dynamics of a d-wave superconductor. Broadband and fixed-frequency microwave apparatus together provide a very clear picture of the electrodynamics of the superconducting condensate and its thermally excited nodal quasiparticles. The measurements reveal the existence of very long-lived excitations deep in the superconducting state, as evidenced by sharp cusp-like conductivity spectra with widths that fall well within our experimental bandwidth. We present a phenomenological model of the microwave conductivity that captures the physics of energy-dependent quasiparticle dynamics in a d-wave superconductor which, in turn, allows us to examine the scattering rate and oscillator strength of the thermally excited quasiparticles as functions of temperature. Our results are in close agreement with the Ferrell-Glover-Tinkham sum rule, giving confidence in both our experiments and the phenomenological model. Separate experiments for currents along the $\hat a$ and $\hat b$ directions of detwinned crystals allow us to isolate the role of the CuO chain layers in \YBCO, and a model is presented that incorporates both one-dimensional conduction from the chain electrons and two-dimensional transport associated with the \cuplane plane layers.
High LRRK2 Levels Fail to Induce or Exacerbate Neuronal Alpha-Synucleinopathy in Mouse Brain
Martin C. Herzig, Michael Bidinosti, Tatjana Schweizer, Thomas Hafner, Christine Stemmelen, Andreas Weiss, Simone Danner, Nella Vidotto, Daniela Stauffer, Carmen Barske, Franziska Mayer, Peter Schmid, Giorgio Rovelli, P. Herman van der Putten, Derya R. Shimshek
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036581
Abstract: The G2019S mutation in the multidomain protein leucine-rich repeat kinase 2 (LRRK2) is one of the most frequently identified genetic causes of Parkinson’s disease (PD). Clinically, LRRK2(G2019S) carriers with PD and idiopathic PD patients have a very similar disease with brainstem and cortical Lewy pathology (α-synucleinopathy) as histopathological hallmarks. Some patients have Tau pathology. Enhanced kinase function of the LRRK2(G2019S) mutant protein is a prime suspect mechanism for carriers to develop PD but observations in LRRK2 knock-out, G2019S knock-in and kinase-dead mutant mice suggest that LRRK2 steady-state abundance of the protein also plays a determining role. One critical question concerning the molecular pathogenesis in LRRK2(G2019S) PD patients is whether α-synuclein (aSN) has a contributory role. To this end we generated mice with high expression of either wildtype or G2019S mutant LRRK2 in brainstem and cortical neurons. High levels of these LRRK2 variants left endogenous aSN and Tau levels unaltered and did not exacerbate or otherwise modify α-synucleinopathy in mice that co-expressed high levels of LRRK2 and aSN in brain neurons. On the contrary, in some lines high LRRK2 levels improved motor skills in the presence and absence of aSN-transgene-induced disease. Therefore, in many neurons high LRRK2 levels are well tolerated and not sufficient to drive or exacerbate neuronal α-synucleinopathy.
In-Vivo NMR of Hyperpolarized Helium-3 in the Human Lung at Very Low Magnetic Fields
Christopher P. Bidinosti,Jamal Choukeife,Pierre-Jean Nacher,Geneviève Tastevin
Physics , 2002, DOI: 10.1016/S1090-7807(02)00198-2
Abstract: We present NMR measurements of the diffusion of hyperpolarized helium-3 in the human lung performed at fields much lower than those of conventional MRI scanners. The measurements were made on standing subjects using homebuilt apparatus operating at 3 mT. Oxygen-limited transverse relaxation (T2 up to 15-35 s) could be measured in-vivo. Accurate global diffusion measurements have been performed in-vivo and in-vitro. 1D ADC mapping with high SNR demonstrates the real possibility of performing quality lung imaging at extremely low fields.
Large Magnetic Shielding Factor Measured by Nonlinear Magneto-optical Rotation
Jeffery W. Martin,Russell R. Mammei,Wolfgang Klassen,Cameron Cerasani,Taraneh Andalib,Christopher P. Bidinosti,Michael Lang,David Ostapchuk
Physics , 2014, DOI: 10.1016/j.nima.2015.01.003
Abstract: A passive magnetic shield was designed and constructed for magnetometer tests for the future neutron electric dipole moment experiment at TRIUMF. The axial shielding factor of the magnetic shield was measured using a magnetometer based on non-linear magneto-optical rotation of the plane of polarized laser light upon passage through a paraffin-coated vapour cell containing natural Rb at room temperature. The laser was tuned to the Rb D1 line, near the $^{85}$Rb $F=2\rightarrow 2,3$ transition. The shielding factor was measured by applying an axial field externally and measuring the magnetic field internally using the magnetometer. The axial shielding factor was determined to be $(1.3\pm 0.1)\times 10^{7}$, from an applied axial field of 1.45~$\mu$T in the background of Earth's magnetic field.
Economically Precise Water Resource Management for Domestic Usage in India  [PDF]
P. Babu, C. Rajasekaran
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.710240
Abstract: In the present years water resource that can be utilized for domestic usage is getting reduced dramatically. In order to have sufficient water for the utilization of future generation, it is our duty to conserve and utilize the available water in a very efficient way. This paper is aimed to help the people to conserve water; it is done with the help of an embedded system that is reconfigurable depending on the number of persons in the family. The system consists of three modules. Each has a different purpose, one module senses the water level present in the tank and intimates the user regarding when the water is needed to be restored. The second module deals with the division of water based on the type of application for which is intended. The third module deals with intimating the municipality regarding the availability of water. All the three modules combine to work in conserving the water; as a result, we can consume nearly 30% per year per head. So this would result in a large amount of conservation of water. Thus the saved water can be reused for several applications.
A Variant Mimicking Hyperphosphorylated 4E-BP Inhibits Protein Synthesis in a Sea Urchin Cell-Free, Cap-Dependent Translation System
Nathalie Oulhen, Sandrine Boulben, Michael Bidinosti, Julia Morales, Patrick Cormier, Bertrand Cosson
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005070
Abstract: Background 4E-BP is a translational inhibitor that binds to eIF4E to repress cap-dependent translation initiation. This critical protein:protein interaction is regulated by the phosphorylation of 4E-BP. Hypophosphorylated 4E-BP binds to eIF4E and inhibits cap-dependent translation, whereas hyperphosphorylated forms do not. While three 4E-BP proteins exist in mammals, only one gene encoding for 4E-BP is present in the sea urchin genome. The protein product has a highly conserved core domain containing the eIF4E-binding domain motif (YxxxxLΦ) and four of the regulatory phosphorylation sites. Methodology/Principal Findings Using a sea urchin cell-free cap-dependent translation system prepared from fertilized eggs, we provide the first direct evidence that the sea urchin 4E-BP inhibits cap-dependent translation. We show here that a sea urchin 4E-BP variant, mimicking phosphorylation on four core residues required to abrogate binding to eIF4E, surprisingly maintains physical association to eIF4E and inhibits protein synthesis. Conclusions/Significance Here, we examine the involvement of the evolutionarily conserved core domain and phosphorylation sites of sea urchin 4E-BP in the regulation of eIF4E-binding. These studies primarily demonstrate the conserved activity of the 4E-BP translational repressor and the importance of the eIF4E-binding domain in sea urchin. We also show that a variant mimicking hyperphosphorylation of the four regulatory phosphorylation sites common to sea urchin and human 4E-BP is not sufficient for release from eIF4E and translation promotion. Therefore, our results suggest that there are additional mechanisms to that of phosphorylation at the four critical sites of 4E-BP that are required to disrupt binding to eIF4E.
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