MHODE: a local-homogeneity theory for improved source-parameter estimation of potential fields

NASA Astrophysics Data System (ADS)

Fedi, Maurizio; Florio, Giovanni; Paoletti, Valeria

2015-08-01

We describe a multihomogeneity theory for source-parameter estimation of potential fields. Similar to what happens for random source models, where the monofractal scaling-law has been generalized into a multifractal law, we propose to generalize the homogeneity law into a multihomogeneity law. This allows a theoretically correct approach to study real-world potential fields, which are inhomogeneous and so do not show scale invariance, except in the asymptotic regions (very near to or very far from their sources). Since the scaling properties of inhomogeneous fields change with the scale of observation, we show that they may be better studied at a set of scales than at a single scale and that a multihomogeneous model is needed to explain its complex scaling behaviour. In order to perform this task, we first introduce fractional-degree homogeneous fields, to show that: (i) homogeneous potential fields may have fractional or integer degree; (ii) the source-distributions for a fractional-degree are not confined in a bounded region, similarly to some integer-degree models, such as the infinite line mass and (iii) differently from the integer-degree case, the fractional-degree source distributions are no longer uniform density functions. Using this enlarged set of homogeneous fields, real-world anomaly fields are studied at different scales, by a simple search, at any local window W, for the best homogeneous field of either integer or fractional-degree, this yielding a multiscale set of local homogeneity-degrees and depth estimations which we call multihomogeneous model. It is so defined a new technique of source parameter estimation (Multi-HOmogeneity Depth Estimation, MHODE), permitting retrieval of the source parameters of complex sources. We test the method with inhomogeneous fields of finite sources, such as faults or cylinders, and show its effectiveness also in a real-case example. These applications show the usefulness of the new concepts, multihomogeneity and

Externally applied electric fields up to 1.6 × 10(5) V/m do not affect the homogeneous nucleation of ice in supercooled water.

PubMed

Stan, Claudiu A; Tang, Sindy K Y; Bishop, Kyle J M; Whitesides, George M

2011-02-10

The freezing of water can initiate at electrically conducting electrodes kept at a high electric potential or at charged electrically insulating surfaces. The microscopic mechanisms of these phenomena are unknown, but they must involve interactions between water molecules and electric fields. This paper investigates the effect of uniform electric fields on the homogeneous nucleation of ice in supercooled water. Electric fields were applied across drops of water immersed in a perfluorinated liquid using a parallel-plate capacitor; the drops traveled in a microchannel and were supercooled until they froze due to the homogeneous nucleation of ice. The distribution of freezing temperatures of drops depended on the rate of nucleation of ice, and the sensitivity of measurements allowed detection of changes by a factor of 1.5 in the rate of nucleation. Sinusoidal alternation of the electric field at frequencies from 3 to 100 kHz prevented free ions present in water from screening the electric field in the bulk of drops. Uniform electric fields in water with amplitudes up to (1.6 ± 0.4) × 10(5) V/m neither enhanced nor suppressed the homogeneous nucleation of ice. Estimations based on thermodynamic models suggest that fields in the range of 10(7)-10(8) V/m might cause an observable increase in the rate of nucleation.

Apparatus for unilateral generation of a homogeneous magnetic field

DOEpatents

Fukushima, Eiichi; Rath, Alan R.; Roeder, Stephen B. W.

1988-01-01

An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coil in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

Apparatus for unilateral generation of a homogeneous magnetic field

DOEpatents

Fukushima, E.; Rath, A.R.; Roeder, S.B.W.

1984-05-01

An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coils in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

Observation of force-detected nuclear magnetic resonance in a homogeneous field

PubMed Central

Madsen, L. A.; Leskowitz, G. M.; Weitekamp, D. P.

2004-01-01

We report the experimental realization of BOOMERANG (better observation of magnetization, enhanced resolution, and no gradient), a sensitive and general method of magnetic resonance. The prototype millimeter-scale NMR spectrometer shows signal and noise levels in agreement with the design principles. We present 1H and 19F NMR in both solid and liquid samples, including time-domain Fourier transform NMR spectroscopy, multiple-pulse echoes, and heteronuclear J spectroscopy. By measuring a 1H-19F J coupling, this last experiment accomplishes chemically specific spectroscopy with force-detected NMR. In BOOMERANG, an assembly of permanent magnets provides a homogeneous field throughout the sample, while a harmonically suspended part of the assembly, a detector, is mechanically driven by spin-dependent forces. By placing the sample in a homogeneous field, signal dephasing by diffusion in a field gradient is made negligible, enabling application to liquids, in contrast to other force-detection methods. The design appears readily scalable to μm-scale samples where it should have sensitivity advantages over inductive detection with microcoils and where it holds great promise for application of magnetic resonance in biology, chemistry, physics, and surface science. We briefly discuss extensions of the BOOMERANG method to the μm and nm scales. PMID:15326302

Comparison of B0 versus B0 and B1 field inhomogeneity correction for glycosaminoglycan chemical exchange saturation transfer imaging.

PubMed

Müller-Lutz, Anja; Ljimani, Alexandra; Stabinska, Julia; Zaiss, Moritz; Boos, Johannes; Wittsack, Hans-Jörg; Schleich, Christoph

2018-05-14

The study compares glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging of intervertebral discs corrected for solely B 0 inhomogeneities or both B 0 and B 1 inhomogeneities. Lumbar intervertebral discs of 20 volunteers were examined with T 2 -weighted and gagCEST imaging. Field inhomogeneity correction was performed with B 0 correction only and with correction of both B 0 and B 1 . GagCEST effects measured by the asymmetric magnetization transfer ratio (MTR asym ) and signal-to-noise ratio (SNR) were compared between both methods. Significant higher MTR asym and SNR values were obtained in the nucleus pulposus using B 0 and B 1 correction compared with B 0 -corrected gagCEST. The GagCEST effect was significantly different in the nucleus pulposus compared with the annulus fibrosus for both methods. The B 0 and B 1 field inhomogeneity correction method leads to an improved quality of gagCEST imaging in IVDs compared with only B 0 correction.

Effects of end-ring/shield configuration on homogeneity and signal-to-noise ratio in a birdcage-type coil loaded with a human head.

PubMed

Liu, Wanzhan; Collins, Christopher M; Delp, Pamela J; Smith, Michael B

2004-01-01

We modeled four different end-ring/shield configurations of a birdcage coil to examine their effects on field homogeneity and signal-to-noise ratio (SNR) at 64 MHz and 125 MHz. The configurations are defined as: 1) conventional: a conventional cylindrical shield; 2) surrounding shield: a shield with annular extensions to closely shield the end rings; 3) solid connection: a shield with annular extensions connected to the rungs; and 4) thin wire connection: a shield with thin wires connected to the rungs. At both frequencies, the coil with conventional end-ring/shield configuration produces the most homogeneous RF magnetic (B1) field when the coil is empty, but produces the least homogeneous B1 field when the coil is loaded with a human head. The surrounding shield configuration results in the most homogeneous B1 and highest SNR in the coil loaded with the human head at both frequencies, followed closely by the solid connection configuration. Copyright 2003 Wiley-Liss, Inc.

Tests of a Prototype for Assessing the Field Homogeneity of the Iseult/Inumac 11.7T Whole Body MRI Magnet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quettier, Lionel

A neuroscience research center with very high field MRI equipments has been opened in November 2006 by the CEA life science division. One of the imaging systems will require a 11.75 T magnet with a 900 mm warm bore, the so-call Iseult/Inumac magnet. Regarding the large aperture and field strength, this magnet is a challenge as compared to the largest MRI systems ever built, and is then developed within an ambitious R&D program. With the objective of demonstrating the possibility of achieving field homogeneity better than 1 ppm using double pancake windings, a 24 double pancakes model coil, working atmore » 1.5 T has been designed. This model magnet has been manufactured by Alstom MSA and tested at CEA. It has been measured with a very high precision, in order to fully characterize the field homogeneity, and then to investigate and discriminate the parameters that influence the field map. This magnet has reached the bare magnet field homogeneity specification expected for Iseult and thus successfully demonstrated the feasibility of building a homogenous magnet with the double pancake winding technique.« less

Enhancement of crystal homogeneity of protein crystals under application of an external alternating current electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koizumi, H.; Uda, S.; Fujiwara, K.

X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white (HEW) lysozyme crystals grown with and without the application of an external alternating current (AC) electric field. The crystal quality was assessed by the full width at half maximum (FWHM) value for each rocking curve. For two-dimensional maps of the FWHMs measured on the 440 and the 12 12 0 reflection, the crystal homogeneity was improved under application of an external electric field at 1 MHz, compared with that without. In particular, the significant improvement of the crystal homogeneity was observed for the 12 12 0 reflection.

Cerebral TOF Angiography at 7T: Impact of B1+ Shimming with a 16-Channel Transceiver Array

PubMed Central

Schmitter, Sebastian; Wu, Xiaoping; Adriany, Gregor; Auerbach, Edward J.; Uğurbil, Kâmil; Van de Moortele, Pierre-François

2014-01-01

Purpose Time-of-flight (TOF) MR imaging is clinically among the most common cerebral non-contrast enhanced MR angiography techniques allowing for high spatial resolution. As shown by several groups TOF contrast significantly improves at ultra-high field (UHF) of B0=7T, however, spatially varying transmit B1 (B1+) fields at 7T reduce TOF contrast uniformity, typically resulting in sub-optimal contrast and reduced vessel conspicuity in the brain periphery. Methods Using a 16-channel B1+ shimming system we compare different dynamically applied B1+ phase shimming approaches on the RF excitation to improve contrast homogeneity for a (0.5 mm)3 resolution multi-slab TOF acquisition. In addition, B1+ shimming applied on the venous saturation pulse was investigated to improve venous suppression, subcutaneous fat signal reduction and enhanced background suppression originating from MT effect. Results B1+ excitation homogeneity was improved by a factor 2.2 to 2.6 on average depending on the shimming approach, compared to a standard CP-like phase setting, leading to improved vessel conspicuity particularly in the periphery. Stronger saturation, higher fat suppression and improved background suppression were observed when dynamically applying B1+ shimming on the venous saturation pulse. Conclusion B1+ shimming can significantly improve high resolution TOF vascular investigations at UHF, holding strong promise for non contrast-enhanced clinical applications. PMID:23640915

Permanent magnet assembly producing a strong tilted homogeneous magnetic field: towards magic angle field spinning NMR and MRI.

PubMed

Sakellariou, Dimitris; Hugon, Cédric; Guiga, Angelo; Aubert, Guy; Cazaux, Sandrine; Hardy, Philippe

2010-12-01

We introduce a cylindrical permanent magnet design that generates a homogeneous and strong magnetic field having an arbitrary inclination with respect to the axis of the cylinder. The analytical theory of 3 D magnetostatics has been applied to this problem, and a hybrid magnet structure has been designed. This structure contains two magnets producing a longitudinal and transverse component for the magnetic field, whose amplitudes and homogeneities can be fully controlled by design. A simple prototype has been constructed using inexpensive small cube magnets, and its magnetic field has been mapped using Hall and NMR probe sensors. This magnet can, in principle, be used for magic angle field spinning NMR and MRI experiments allowing for metabolic chemical shift profiling in small living animals. Copyright © 2010 John Wiley & Sons, Ltd.

Investigation of the B1 field distribution and RF power deposition in a birdcage coil as functions of the number of coil legs at 4.7 T, 7.0 T, and 11.7 T

NASA Astrophysics Data System (ADS)

Seo, Jeung-Hoon; Han, Sang-Doc; Kim, Kyoung-Nam

2015-06-01

The proper design of birdcage (BC) coils plays a very important role in the acquisition of highresolution magnetic resonance imaging (MRI) of small animals such as rodents. In this context, we investigate multiple-leg (8-, 16-, 32-, 64-, and 128-leg) BC coils operating at ultra-high fields (UHF) of 7.0 T and 11.7 T and a high-field (HF) of 4.7 T for rodent magnetic resonance imaging (MRI). Primarily, Our study comparatively examines the parameters of the radiofrequency (RF) transmission (|B1 +|)-field, the magnetic flux (|B1|)-field, and RF power deposition (RF-PD) as functions of the number of BC-coil legs via finite-difference time-domain (FDTD) calculations under realistic loading conditions with a biological phantom. In particular, the specific ratio |E/B1 +| is defined for predicting RF-PD values in different coil structures. Our results indicate that the optimal number of legs of the BC coil can be chosen for different resonance frequencies of 200 MHz, 300 MHz, and 500 MHz and that this choice can be lead to superior |B1 +|-field intensity and |B1|-field homogeneity and decreased RF-PD. We believe that our approach to determining the optimal number of legs for a BC coil can contribute to rodent MR imaging.

Some aspects of TLC in homogenous magnetic fields.

PubMed

Malinowska, Irena; Studziński, Marek; Malinowski, Henryk

2011-08-01

This article consists of two parts. First part is a short review about the role of magnetic phenomena in natural environment, human surroundings, and his activities such as science, engineering, and medicine. The second part of the article presents a set of experiments, their results, and data obtained in a static homogenous magnetic field, generated by a pair of permanent magnets and outside it. Adsorption chromatographic systems were investigated: as chromatographed substances - polyaromatic hydrocarbon (PAH), as stationary phase - silica gel 60, as monocomponent mobile phases - n-hexane, n-heptane, n-octane, and benzene were used and binary mobile phases n-hydrocarbons - benzene. Magnetic field influences retention and efficiency of investigated chromatographic systems. Experimental data analysis (RF, N) allows us to propose some explanations of the differences between experiment results performed in induced magnetic field and outside it, and in consequence on the changes in the interfacial phenomena induced by field presence. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

B1 field-insensitive transformers for RF-safe transmission lines.

PubMed

Krafft, Axel; Müller, Sven; Umathum, Reiner; Semmler, Wolfhard; Bock, Michael

2006-11-01

Integration of transformers into transmission lines suppresses radiofrequency (RF)-induced heating. New figure-of-eight-shaped transformer coils are compared to conventional loop transformer coils to assess their signal transmission properties and safety profile. The transmission properties of figure-of-eight-shaped transformers were measured and compared to transformers with loop coils. Experiments to quantify the effect of decoupling from the B1 field of the MR system were conducted. Temperature measurements were performed to demonstrate the effective reduction of RF-induced heating. The transformers were investigated during active tracking experiments. Coupling to the B1 field was reduced by 18 dB over conventional loop-shaped transformer coils. MR images showed a significantly reduced artifact for the figure-of-eight- shaped coils generated by local flip-angle amplification. Comparable transmission properties were seen for both transformer types. Temperature measurements showed a maximal temperature increase of 30 K/3.5 K for an unsegmented/segmented cable. With a segmented transmission line a robotic assistance system could be successfully localized using active tracking. The figure-of-eight-shaped transformer design reduces both RF field coupling with the MR system and artifact sizes. Anatomical structure close to the figure-of-eight-shaped transformer may be less obscured as with loop-shaped transformers if these transformers are integrated into e.g. intravascular catheters.

Occurrence of CYP1B1 Mutations in Juvenile Open-Angle Glaucoma With Advanced Visual Field Loss.

PubMed

Souzeau, Emmanuelle; Hayes, Melanie; Zhou, Tiger; Siggs, Owen M; Ridge, Bronwyn; Awadalla, Mona S; Smith, James E H; Ruddle, Jonathan B; Elder, James E; Mackey, David A; Hewitt, Alex W; Healey, Paul R; Goldberg, Ivan; Morgan, William H; Landers, John; Dubowsky, Andrew; Burdon, Kathryn P; Craig, Jamie E

2015-07-01

Juvenile open-angle glaucoma (JOAG) is a severe neurodegenerative eye disorder in which most of the genetic contribution remains unexplained. To assess the prevalence of pathogenic CYP1B1 sequence variants in an Australian cohort of patients with JOAG and severe visual field loss. For this cohort study, we recruited 160 patients with JOAG classified as advanced (n = 118) and nonadvanced (n = 42) through the Australian and New Zealand Registry of Advanced Glaucoma from January 1, 2007, through April 1, 2014. Eighty individuals with no evidence of glaucoma served as a control group. We defined JOAG as diagnosis before age 40 years and advanced JOAG as visual field loss in 2 of the 4 central fixation squares on a reliable visual field test result. We performed direct sequencing of the entire coding region of CYP1B1. Data analysis was performed in October 2014. Identification and characterization of CYP1B1 sequence variants. We identified 7 different pathogenic variants among 8 of 118 patients with advanced JOAG (6.8%) but none among the patients with nonadvanced JOAG. Three patients were homozygous or compound heterozygous for CYP1B1 pathogenic variants, which provided a likely basis for their disease. Five patients were heterozygous. The allele frequency among the patients with advanced JOAG (11 in 236 [4.7%]) was higher than among our controls (1 in 160 [0.6%]; P = .02; odds ratio, 7.8 [95% CI, 0.02-1.0]) or among the control population from the Exome Aggregation Consortium database (2946 of 122 960 [2.4%]; P = .02; odds ratio, 2.0 [95% CI, 0.3-0.9]). Individuals with CYP1B1 pathogenic variants, whether heterozygous or homozygous, had worse mean (SD) deviation on visual fields (-24.5 [5.1] [95% CI, -31.8 to -17.2] vs -15.6 [10.0] [95% CI, -17.1 to -13.6] dB; F1,126 = 5.90; P = .02; partial ηp2 = 0.05) and were younger at diagnosis (mean [SD] age, 23.1 [8.4] [95% CI, 17.2-29.1] vs 31.5 [8.0] [95% CI, 30.1-33.0] years; F1,122 = 7

Ab initio molecular dynamics in a finite homogeneous electric field.

PubMed

Umari, P; Pasquarello, Alfredo

2002-10-07

We treat homogeneous electric fields within density functional calculations with periodic boundary conditions. A nonlocal energy functional depending on the applied field is used within an ab initio molecular dynamics scheme. The reliability of the method is demonstrated in the case of bulk MgO for the Born effective charges, and the high- and low-frequency dielectric constants. We evaluate the static dielectric constant by performing a damped molecular dynamics in an electric field and avoiding the calculation of the dynamical matrix. Application of this method to vitreous silica shows good agreement with experiment and illustrates its potential for systems of large size.

Dependence of B1+ and B1- Field Patterns of Surface Coils on the Electrical Properties of the Sample and the MR Operating Frequency.

PubMed

Vaidya, Manushka V; Collins, Christopher M; Sodickson, Daniel K; Brown, Ryan; Wiggins, Graham C; Lattanzi, Riccardo

2016-02-01

In high field MRI, the spatial distribution of the radiofrequency magnetic ( B 1 ) field is usually affected by the presence of the sample. For hardware design and to aid interpretation of experimental results, it is important both to anticipate and to accurately simulate the behavior of these fields. Fields generated by a radiofrequency surface coil were simulated using dyadic Green's functions, or experimentally measured over a range of frequencies inside an object whose electrical properties were varied to illustrate a variety of transmit [Formula: see text] and receive [Formula: see text] field patterns. In this work, we examine how changes in polarization of the field and interference of propagating waves in an object can affect the B 1 spatial distribution. Results are explained conceptually using Maxwell's equations and intuitive illustrations. We demonstrate that the electrical conductivity alters the spatial distribution of distinct polarized components of the field, causing "twisted" transmit and receive field patterns, and asymmetries between [Formula: see text] and [Formula: see text]. Additionally, interference patterns due to wavelength effects are observed at high field in samples with high relative permittivity and near-zero conductivity, but are not present in lossy samples due to the attenuation of propagating EM fields. This work provides a conceptual framework for understanding B 1 spatial distributions for surface coils and can provide guidance for RF engineers.

Searching regional rainfall homogeneity using atmospheric fields

NASA Astrophysics Data System (ADS)

Gabriele, Salvatore; Chiaravalloti, Francesco

2013-03-01

The correct identification of homogeneous areas in regional rainfall frequency analysis is fundamental to ensure the best selection of the probability distribution and the regional model which produce low bias and low root mean square error of quantiles estimation. In an attempt at rainfall spatial homogeneity, the paper explores a new approach that is based on meteo-climatic information. The results are verified ex-post using standard homogeneity tests applied to the annual maximum daily rainfall series. The first step of the proposed procedure selects two different types of homogeneous large regions: convective macro-regions, which contain high values of the Convective Available Potential Energy index, normally associated with convective rainfall events, and stratiform macro-regions, which are characterized by low values of the Q vector Divergence index, associated with dynamic instability and stratiform precipitation. These macro-regions are identified using Hot Spot Analysis to emphasize clusters of extreme values of the indexes. In the second step, inside each identified macro-region, homogeneous sub-regions are found using kriging interpolation on the mean direction of the Vertically Integrated Moisture Flux. To check the proposed procedure, two detailed examples of homogeneous sub-regions are examined.

Topology optimization based design of unilateral NMR for generating a remote homogeneous field.

PubMed

Wang, Qi; Gao, Renjing; Liu, Shutian

2017-06-01

This paper presents a topology optimization based design method for the design of unilateral nuclear magnetic resonance (NMR), with which a remote homogeneous field can be obtained. The topology optimization is actualized by seeking out the optimal layout of ferromagnetic materials within a given design domain. The design objective is defined as generating a sensitive magnetic field with optimal homogeneity and maximal field strength within a required region of interest (ROI). The sensitivity of the objective function with respect to the design variables is derived and the method for solving the optimization problem is presented. A design example is provided to illustrate the utility of the design method, specifically the ability to improve the quality of the magnetic field over the required ROI by determining the optimal structural topology for the ferromagnetic poles. Both in simulations and experiments, the sensitive region of the magnetic field achieves about 2 times larger than that of the reference design, validating validates the feasibility of the design method. Copyright © 2017. Published by Elsevier Inc.

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets.

PubMed

Chou, Ching-Yu; Ferrage, Fabien; Aubert, Guy; Sakellariou, Dimitris

2015-07-17

Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation.

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets

PubMed Central

Chou, Ching-Yu; Ferrage, Fabien; Aubert, Guy; Sakellariou, Dimitris

2015-01-01

Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation. PMID:26182891

Encoding methods for B1+ mapping in parallel transmit systems at ultra high field

NASA Astrophysics Data System (ADS)

Tse, Desmond H. Y.; Poole, Michael S.; Magill, Arthur W.; Felder, Jörg; Brenner, Daniel; Jon Shah, N.

2014-08-01

Parallel radiofrequency (RF) transmission, either in the form of RF shimming or pulse design, has been proposed as a solution to the B1+ inhomogeneity problem in ultra high field magnetic resonance imaging. As a prerequisite, accurate B1+ maps from each of the available transmit channels are required. In this work, four different encoding methods for B1+ mapping, namely 1-channel-on, all-channels-on-except-1, all-channels-on-1-inverted and Fourier phase encoding, were evaluated using dual refocusing acquisition mode (DREAM) at 9.4 T. Fourier phase encoding was demonstrated in both phantom and in vivo to be the least susceptible to artefacts caused by destructive RF interference at 9.4 T. Unlike the other two interferometric encoding schemes, Fourier phase encoding showed negligible dependency on the initial RF phase setting and therefore no prior B1+ knowledge is required. Fourier phase encoding also provides a flexible way to increase the number of measurements to increase SNR, and to allow further reduction of artefacts by weighted decoding. These advantages of Fourier phase encoding suggest that it is a good choice for B1+ mapping in parallel transmit systems at ultra high field.

Modeling real shim fields for very high degree (and order) B0 shimming of the human brain at 9.4 T.

PubMed

Chang, Paul; Nassirpour, Sahar; Henning, Anke

2018-01-01

To describe the process of calibrating a B 0 shim system using high-degree (or high order) spherical harmonic models of the measured shim fields, to provide a method that considers amplitude dependency of these models, and to show the advantage of very high-degree B 0 shimming for whole-brain and single-slice applications at 9.4 Tesla (T). An insert shim with up to fourth and partial fifth/sixth degree (order) spherical harmonics was used with a Siemens 9.4T scanner. Each shim field was measured and modeled as input for the shimming algorithm. Optimal shim currents can therefore be calculated in a single iteration. A range of shim currents was used in the modeling to account for possible amplitude nonlinearities. The modeled shim fields were used to compare different degrees of whole-brain B 0 shimming on healthy subjects. The ideal shim fields did not correctly shim the subject brains. However, using the modeled shim fields improved the B 0 homogeneity from 55.1 (second degree) to 44.68 Hz (partial fifth/sixth degree) on the whole brains of 9 healthy volunteers, with a total applied current of 0.77 and 6.8 A, respectively. The necessity of calibrating the shim system was shown. Better B 0 homogeneity drastically reduces signal dropout and distortions for echo-planar imaging, and significantly improves the linewidths of MR spectroscopy imaging. Magn Reson Med 79:529-540, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Genetic homogeneity of Clostridium botulinum type A1 strains with unique toxin gene clusters.

PubMed

Raphael, Brian H; Luquez, Carolina; McCroskey, Loretta M; Joseph, Lavin A; Jacobson, Mark J; Johnson, Eric A; Maslanka, Susan E; Andreadis, Joanne D

2008-07-01

A group of five clonally related Clostridium botulinum type A strains isolated from different sources over a period of nearly 40 years harbored several conserved genetic properties. These strains contained a variant bont/A1 with five nucleotide polymorphisms compared to the gene in C. botulinum strain ATCC 3502. The strains also had a common toxin gene cluster composition (ha-/orfX+) similar to that associated with bont/A in type A strains containing an unexpressed bont/B [termed A(B) strains]. However, bont/B was not identified in the strains examined. Comparative genomic hybridization demonstrated identical genomic content among the strains relative to C. botulinum strain ATCC 3502. In addition, microarray data demonstrated the absence of several genes flanking the toxin gene cluster among the ha-/orfX+ A1 strains, suggesting the presence of genomic rearrangements with respect to this region compared to the C. botulinum ATCC 3502 strain. All five strains were shown to have identical flaA variable region nucleotide sequences. The pulsed-field gel electrophoresis patterns of the strains were indistinguishable when digested with SmaI, and a shift in the size of at least one band was observed in a single strain when digested with XhoI. These results demonstrate surprising genomic homogeneity among a cluster of unique C. botulinum type A strains of diverse origin.

The effect of rotating magnetic field on the microstructure of in situ TiB2/Cu composites

NASA Astrophysics Data System (ADS)

Zou, C.; Kang, H.; Li, R.; Li, M.; Wang, W.; Chen, Z.; Wang, T.

2016-03-01

Nano ceramic particulate reinforced metal matrix composites are confronted with the problem of particle aggregation emerging in the process of solidification. It sharply deteriorates the mechanical properties of the composites. In order to improve the microstructure and particle distribution, in situ TiB2/Cu composites were prepared using Ti and Cu-B master alloys in a vacuum medium frequency induction furnace equipped with a rotating magnetic field (RMF). The effect of RMF magnetic field intensity employed on the microstructure and particles distribution of the TiB2/Cu composites were investigated. The results show that with the applied RMF, TiB2 particles are homogeneously distributed in the copper matrix, which significantly improves the mechanical properties of TiB2/Cu composites. The mechanism of RMF may be ascribed to the following two aspects. On the one hand, the electromagnetic body force generated by appropriate RMF drives forced convection in the equatorial plane of composite melt during solidification. On the other hand, a secondary flow in the meridional plane is engendered by a radial pressure gradient, thus making a strong agitation in the melt. These two effects result in a homogenous dispersion of TiB2 particles in the copper matrix, and hence excellent properties of TiB2/Cu composites were obtained.

TH-AB-BRA-05: Lung Cannot Be Treated as Homogeneous in Radiation Transport Simulations in Magnetic Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malkov, V; Rogers, D; Jaffray, D

2016-06-15

Purpose: Magnetic fields in MRgRT are known to induce dose perturbations near lung-tissue interfaces. The goal of this study is to determine if the heterogeneous structure of the lung influences the dose distribution in a magnetic field. Method: The dose distribution from a 4 cm X 4 cm 6 MV photon beam in a 0, 0.6, or 1.5 T magnetic field in a homogeneous lung density (0.333 g/cm{sup 3}) geometry is compared to that in a heterogeneous segmented slab configuration. The heterogeneous phantom is composed of 2/3 water vapour and 1/3 liquid water such that the overall density of themore » lung regions in the two phantoms are equivalent. The EGSnrc DOSXYZnrc user code is used with a previously implemented magnetic field transport code. Results: For water vapour gap thickness of 2 mm, compared to the homogeneous lung case (which already exhibits significant dose perturbations in a magnetic field) differences as large as 12.3 ± 0.2 % are observed for a 0.6 T field and 9.3 ± 0.1 % for a 1.5 T field at the tissuelung interface, and on the order of several percent within the lung-like tissue region for both magnetic fields. Thicker gaps produced larger deviations while a gap thickness of 0.2 mm does not result in notable differences. Regardless of gap thickness, the heterogeneities had little effect on the 0 T simulations. Further, using smaller scoring regions revealed that dose averaging effects could obscure dose differences as large as 10 – 20 % within the heterogeneous structures of the lung-like media. Conclusions: This simple model demonstrates that media heterogeneities can play an important role in MRgRT dose distributions, and care must be taken in setting up any dose calculation in the lung in the presence of a magnetic field, especially for air regions larger than 2 mm.« less

Simultaneous mapping of water shift and B1 (WASABI)-Application to field-Inhomogeneity correction of CEST MRI data.

PubMed

Schuenke, Patrick; Windschuh, Johannes; Roeloffs, Volkert; Ladd, Mark E; Bachert, Peter; Zaiss, Moritz

2017-02-01

Together with the development of MRI contrasts that are inherently small in their magnitude, increased magnetic field accuracy is also required. Hence, mapping of the static magnetic field (B 0 ) and the excitation field (B 1 ) is not only important to feedback shim algorithms, but also for postprocess contrast-correction procedures. A novel field-inhomogeneity mapping method is presented that allows simultaneous mapping of the water shift and B 1 (WASABI) using an off-resonant rectangular preparation pulse. The induced Rabi oscillations lead to a sinc-like spectrum in the frequency-offset dimension and allow for determination of B 0 by its symmetry axis and of B 1 by its oscillation frequency. Stability of the WASABI method with regard to the influences of T 1 , T 2 , magnetization transfer, and repetition time was investigated and its convergence interval was verified. B 0 and B 1 maps obtained simultaneously by means of WASABI in the human brain at 3 T and 7 T can compete well with maps obtained by standard methods. Finally, the method was applied successfully for B 0 and B 1 correction of chemical exchange saturation transfer MRI (CEST-MRI) data of the human brain. The proposed WASABI method yields a novel simultaneous B 0 and B 1 mapping within 1 min that is robust and easy to implement. Magn Reson Med 77:571-580, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Extracting fields snow coverage information with HJ-1A/B satellites data

NASA Astrophysics Data System (ADS)

Dong, Wenquan; Meng, Jihua

2015-10-01

The distribution and change of snow coverage are sensitive factors of climate change. In northeast part of China, farmlands are still covered with snow in spring. Since sowing activity can only be done when the snow melted, fields snow coverage monitoring provides reference for the determination of sowing date. Because of the restriction of the sensors and application requirements, current researches on remote sensing of snow focus more on the study of musicale and large scale, rather than the study of small scale, and especially research on snow melting period is rarely reported.HJ-1A/B satellites are parts of little satellite constellation, focusing on environment and disaster monitoring and meteorological forecast. Compared to other data sources, HJ-1A/B satellites both have comparatively higher temporal and spatial resolution and are more conducive to monitor the variations of melting snow coverage at small watershed. This paper was based on HJ-1A/1B data, taking Hongxing farm of Bei'an, Heilongjiang Province, China as the study area. In this paper, we exploited the methods for extraction of snow cover information on farmland in two cases, both HJ-1A/1B CCD with HJ-1B IRS data and just HJ-1A/1B CCD data. The reason we chose the two cases is that, the two optical satellites HJ-1A/B are capable of providing a whole territory coverage period in visible light spectrum in two days, infrared spectrum in four days. So sometimes we can only obtain CCD image. In this case, the method of normalized snow index cannot be used to extract snow coverage information. Using HJ-1A/1B CCD with HJ-1B IRS data, combined with the theory of snow remote sensing monitoring, this paper analyzed spectral response characteristics of HJ-1A/1B satellites data, then the widely used Normalized Difference Snow Index(NDSI) and S3 Index were quoted to the HJ-1A/1B satellites data. The NDSI uses reflectance values of Red and SWIR spectral bands of HJ-1B, and S3 index uses reflectance values of

Potential-field sounding using Euler's homogeneity equation and Zidarov bubbling

USGS Publications Warehouse

Cordell, Lindrith

1994-01-01

Potential-field (gravity) data are transformed into a physical-property (density) distribution in a lower half-space, constrained solely by assumed upper bounds on physical-property contrast and data error. A two-step process is involved. The data are first transformed to an equivalent set of line (2-D case) or point (3-D case) sources, using Euler's homogeneity equation evaluated iteratively on the largest residual data value. Then, mass is converted to a volume-density product, constrained to an upper density bound, by 'bubbling,' which exploits circular or radial expansion to redistribute density without changing the associated gravity field. The method can be developed for gravity or magnetic data in two or three dimensions. The results can provide a beginning for interpretation of potential-field data where few independent constraints exist, or more likely, can be used to develop models and confirm or extend interpretation of other geophysical data sets.

Bianchi class B spacetimes with electromagnetic fields

NASA Astrophysics Data System (ADS)

Yamamoto, Kei

2012-02-01

We carry out a thorough analysis on a class of cosmological space-times which admit three spacelike Killing vectors of Bianchi class B and contain electromagnetic fields. Using dynamical system analysis, we show that a family of electro-vacuum plane-wave solutions of the Einstein-Maxwell equations is the stable attractor for expanding universes. Phase dynamics are investigated in detail for particular symmetric models. We integrate the system exactly for some special cases to confirm the qualitative features. Some of the obtained solutions have not been presented previously to the best of our knowledge. Finally, based on those analyses, we discuss the relation between those homogeneous models and perturbations of open Friedmann-Lemaitre-Robertson-Walker universes. We argue that the electro-vacuum plane-wave modes correspond to a certain long-wavelength limit of electromagnetic perturbations.

Magnetic phase diagrams of CexLa1-xB6 in high magnetic fields

NASA Astrophysics Data System (ADS)

Akatsu, Mitsuhiro; Kazama, Nanako; Goto, Terutaka; Nemoto, Yuichi; Suzuki, Osamu; Kido, Giyuu; Kunii, Satoru

We have performed ultrasonic measurements under high magnetic fields up to 30 T by using the hybrid magnet at the National Institute for Materials Science to investigate the magnetic phase diagram for antiferroquadrupole (AFQ) phase II in CexLa1-xB6. With increasing Ce concentration x from x=0.50, the AFQ phase transition temperatures TQ indicate an almost linear increase in various fields. The large magnetic anisotropy of AFQ phase II, in which TQH∥[0 0 1] is much smaller than TQH∥[1 1 0] and TQH∥[1 1 1] in high magnetic fields, is revealed in x=0.75,0.60 as well as in x=0.50. These experimental results support the theoretical calculation based on the Γ5-type AFQ ordering and the magnetic field induced octupole Txyz.

Mechanical Homogenization Increases Bacterial Homogeneity in Sputum

PubMed Central

Stokell, Joshua R.; Khan, Ammad

2014-01-01

Sputum obtained from patients with cystic fibrosis (CF) is highly viscous and often heterogeneous in bacterial distribution. Adding dithiothreitol (DTT) is the standard method for liquefaction prior to processing sputum for molecular detection assays. To determine if DTT treatment homogenizes the bacterial distribution within sputum, we measured the difference in mean total bacterial abundance and abundance of Burkholderia multivorans between aliquots of DTT-treated sputum samples with and without a mechanical homogenization (MH) step using a high-speed dispersing element. Additionally, we measured the effect of MH on bacterial abundance. We found a significant difference between the mean bacterial abundances in aliquots that were subjected to only DTT treatment and those of the aliquots which included an MH step (all bacteria, P = 0.04; B. multivorans, P = 0.05). There was no significant effect of MH on bacterial abundance in sputum. Although our results are from a single CF patient, they indicate that mechanical homogenization increases the homogeneity of bacteria in sputum. PMID:24759710

Homogeneity of lava flows - Chemical data for historic Mauna Loan eruptions

NASA Technical Reports Server (NTRS)

Rhodes, J. M.

1983-01-01

Chemical analyses of basalts collected from the major historic eruptions of Mauna Loa volcano show that many of the flow fields are remarkably homogeneous in composition. Despite their large size (lengths 9-85 km), large areal extents (13-114 sq km), and various durations of eruption (1-450 days), many of the flow fields have compositional variability that is within, or close to, the analytical error for most elements. The flow fields that are not homogeneous vary mainly in olivine content in an otherwise homogeneous melt. Some are composite flow fields made up of several, apparently homogeneous subunits erupted at different elevations along the active volcanic rifts. Not all volcanoes produce lavas that are homogeneous like those of Mauna Loa. If studies such as this are to be used to evaluate compositional diversity in lavas where there is a lack of sampling control, such as on other planets, it is necessary to understand why some flow units and flow fields are compositionally homogeneous and others are not, and to develop criteria for distinguishing between them.

Evaluating a novel application of optical fibre evanescent field absorbance: rapid measurement of red colour in winegrape homogenates

NASA Astrophysics Data System (ADS)

Lye, Peter G.; Bradbury, Ronald; Lamb, David W.

Silica optical fibres were used to measure colour (mg anthocyanin/g fresh berry weight) in samples of red wine grape homogenates via optical Fibre Evanescent Field Absorbance (FEFA). Colour measurements from 126 samples of grape homogenate were compared against the standard industry spectrophotometric reference method that involves chemical extraction and subsequent optical absorption measurements of clarified samples at 520 nm. FEFA absorbance on homogenates at 520 nm (FEFA520h) was correlated with the industry reference method measurements of colour (R2 = 0.46, n = 126). Using a simple regression equation colour could be predicted with a standard error of cross-validation (SECV) of 0.21 mg/g, with a range of 0.6 to 2.2 mg anthocyanin/g and a standard deviation of 0.33 mg/g. With a Ratio of Performance Deviation (RPD) of 1.6, the technique when utilizing only a single detection wavelength, is not robust enough to apply in a diagnostic sense, however the results do demonstrate the potential of the FEFA method as a fast and low-cost assay of colour in homogenized samples.

Improved normal tissue protection by proton and X-ray microchannels compared to homogeneous field irradiation.

PubMed

Girst, S; Marx, C; Bräuer-Krisch, E; Bravin, A; Bartzsch, S; Oelfke, U; Greubel, C; Reindl, J; Siebenwirth, C; Zlobinskaya, O; Multhoff, G; Dollinger, G; Schmid, T E; Wilkens, J J

2015-09-01

The risk of developing normal tissue injuries often limits the radiation dose that can be applied to the tumour in radiation therapy. Microbeam Radiation Therapy (MRT), a spatially fractionated photon radiotherapy is currently tested at the European Synchrotron Radiation Facility (ESRF) to improve normal tissue protection. MRT utilizes an array of microscopically thin and nearly parallel X-ray beams that are generated by a synchrotron. At the ion microprobe SNAKE in Munich focused proton microbeams ("proton microchannels") are studied to improve normal tissue protection. Here, we comparatively investigate microbeam/microchannel irradiations with sub-millimetre X-ray versus proton beams to minimize the risk of normal tissue damage in a human skin model, in vitro. Skin tissues were irradiated with a mean dose of 2 Gy over the irradiated area either with parallel synchrotron-generated X-ray beams at the ESRF or with 20 MeV protons at SNAKE using four different irradiation modes: homogeneous field, parallel lines and microchannel applications using two different channel sizes. Normal tissue viability as determined in an MTT test was significantly higher after proton or X-ray microchannel irradiation compared to a homogeneous field irradiation. In line with these findings genetic damage, as determined by the measurement of micronuclei in keratinocytes, was significantly reduced after proton or X-ray microchannel compared to a homogeneous field irradiation. Our data show that skin irradiation using either X-ray or proton microchannels maintain a higher cell viability and DNA integrity compared to a homogeneous irradiation, and thus might improve normal tissue protection after radiation therapy. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

TH-CD-BRA-05: First Water Calorimetric Dw Measurement and Direct Measurement of Magnetic Field Correction Factors, KQ,B, in a 1.5 T B-Field of An MRI Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prez, L de; Pooter, J de; Jansen, B

2016-06-15

Purpose: Reference dosimetry in MR-guided radiotherapy is performed in the presence of a B-field. As a consequence the response of ionization chambers changes considerably and depends on parameters not considered in traditional reference dosimetry. Therefore future Codes of Practices need ionization chamber correction factors to correct for both the change in beam quality and the presence of a B-field. The objective was to study the feasibility of water calorimetric absorbed-dose measurements in a 1.5 T B-field of an MRLinac and the direct measurement of kQ,B calibration of ionization chambers. Methods: Calorimetric absorbed dose to water Dw was measured with amore » new water calorimeter in the bore of an MRLinac (TPR20,10 of 0.702). Two waterproof ionization chambers (PTW 30013, IBA FC-65G) were calibrated inside the calorimeter phantom (ND,w,Q,B). Both measurements were normalized to a monitor ionization chamber. Ionization chamber measurements were corrected for conventional influence parameter. Based on the chambers’ Co-60 calibrations (ND,w,Q0), measured directly against the calorimeter. In this study the correction factors kQ,B was determined as the ratio of the calibration coefficients in the MRLinac and in Co-60. Additionally, kB was determined based on kQ values obtained with the IAEA TRS-398 Code of Practice. Results: The kQ,B factors of the ionization chambers mentioned above were respectively 0.9488(8) and 0.9445(8) with resulting kB factors of 0.961(13) and 0.952(13) with standard uncertainties on the least significant digit(s) between brackets. Conclusion: Calorimetric Dw measurements and calibration of waterproof ionization chambers were successfully carried out in the 1.5 T B-field of an MRLinac with a standard uncertainty of 0.7%. Preliminary kQ,B and kB factors were determined with standard uncertainties of respectively 0.8% and 1.3%. The kQ,B agrees with an alternative method within 0.4%. The feasibility of water calorimetry in the presence

Homogeneous microwave field emitted propagating spin waves: Direct imaging and modeling

NASA Astrophysics Data System (ADS)

Lohman, Mathis; Mozooni, Babak; McCord, Jeffrey

2018-03-01

We explore the generation of propagating dipolar spin waves by homogeneous magnetic field excitation in the proximity of the boundaries of magnetic microstructures. Domain wall motion, precessional dynamics, and propagating spin waves are directly imaged by time-resolved wide-field magneto-optical Kerr effect microscopy. The aspects of spin wave generation are clarified by micromagnetic calculations matching the experimental results. The region of dipolar spin wave formation is confined to the local resonant excitation due to non-uniform internal demagnetization fields at the edges of the patterned sample. Magnetic domain walls act as a border for the propagation of plane and low damped spin waves, thus restraining the spin waves within the individual magnetic domains. The findings are of significance for the general understanding of structural and configurational magnetic boundaries for the creation, the propagation, and elimination of spin waves.

Accelerating parallel transmit array B1 mapping in high field MRI with slice undersampling and interpolation by kriging.

PubMed

Ferrand, Guillaume; Luong, Michel; Cloos, Martijn A; Amadon, Alexis; Wackernagel, Hans

2014-08-01

Transmit arrays have been developed to mitigate the RF field inhomogeneity commonly observed in high field magnetic resonance imaging (MRI), typically above 3T. To this end, the knowledge of the RF complex-valued B1 transmit-sensitivities of each independent radiating element has become essential. This paper details a method to speed up a currently available B1-calibration method. The principle relies on slice undersampling, slice and channel interleaving and kriging, an interpolation method developed in geostatistics and applicable in many domains. It has been demonstrated that, under certain conditions, kriging gives the best estimator of a field in a region of interest. The resulting accelerated sequence allows mapping a complete set of eight volumetric field maps of the human head in about 1 min. For validation, the accuracy of kriging is first evaluated against a well-known interpolation technique based on Fourier transform as well as to a B1-maps interpolation method presented in the literature. This analysis is carried out on simulated and decimated experimental B1 maps. Finally, the accelerated sequence is compared to the standard sequence on a phantom and a volunteer. The new sequence provides B1 maps three times faster with a loss of accuracy limited potentially to about 5%.

KPS-1b: The First Transiting Exoplanet Discovered Using an Amateur Astronomer's Wide-field CCD Data

NASA Astrophysics Data System (ADS)

Burdanov, Artem; Benni, Paul; Sokov, Eugene; Krushinsky, Vadim; Popov, Alexander; Delrez, Laetitia; Gillon, Michael; Hébrard, Guillaume; Deleuil, Magali; Wilson, Paul A.; Demangeon, Olivier; Baştürk, Özgür; Pakštiene, Erika; Sokova, Iraida; Rusov, Sergei A.; Dyachenko, Vladimir V.; Rastegaev, Denis A.; Beskakotov, Anatoliy; Marchini, Alessandro; Bretton, Marc; Shadick, Stan; Ivanov, Kirill

2018-07-01

We report the discovery of the transiting hot Jupiter KPS-1b. This exoplanet orbits a V = 13.0 K1-type main-sequence star every 1.7 days, has a mass of {1.090}-0.087+0.086 M Jup and a radius of {1.03}-0.12+0.13 R Jup. The discovery was made by the prototype Kourovka Planet Search (KPS) project, which used wide-field CCD data gathered by an amateur astronomer using readily available and relatively affordable equipment. Here we describe the equipment and observing technique used for the discovery of KPS-1b, its characterization with spectroscopic observations by the SOPHIE spectrograph and with high-precision photometry obtained with 1 m class telescopes. We also outline the KPS project evolution into the Galactic Plane eXoplanet survey. The discovery of KPS-1b represents a new major step of the contribution of amateur astronomers to the burgeoning field of exoplanetology.

Quadrature transmit coil for breast imaging at 7 tesla using forced current excitation for improved homogeneity.

PubMed

McDougall, Mary Preston; Cheshkov, Sergey; Rispoli, Joseph; Malloy, Craig; Dimitrov, Ivan; Wright, Steven M

2014-11-01

To demonstrate the use of forced current excitation (FCE) to create homogeneous excitation of the breast at 7 tesla, insensitive to the effects of asymmetries in the electrical environment. FCE was implemented on two breast coils: one for quadrature (1) H imaging and one for proton-decoupled (13) C spectroscopy. Both were a Helmholtz-saddle combination, with the saddle tuned to 298 MHz for imaging and 75 MHz for spectroscopy. Bench measurements were acquired to demonstrate the ability to force equal currents on elements in the presence of asymmetric loading to improve homogeneity. Modeling and temperature measurements were conducted per safety protocol. B1 mapping, imaging, and proton-decoupled (13) C spectroscopy were demonstrated in vivo. Using FCE to ensure balanced currents on elements enabled straightforward tuning and maintaining of isolation between quadrature elements of the coil. Modeling and bench measurements confirmed homogeneity of the field, which resulted in images with excellent fat suppression and in broadband proton-decoupled carbon-13 spectra. FCE is a straightforward approach to ensure equal currents on multiple coil elements and a homogeneous excitation field, insensitive to the effects of asymmetries in the electrical environment. This enabled effective breast imaging and proton-decoupled carbon-13 spectroscopy at 7T. © 2014 Wiley Periodicals, Inc.

Fate of avermectin B1a on citrus fruits. 1. Distribution and magnitude of the avermectin B sub 1a and sup 14 C residue on citrus fruits from a field study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maynard, M.S.; Iwata, Y.; Wislocki, P.G.

An 8{mu}g/mL solution of ({sup 14}C)avermectin B{sub 1a}, the approximate field application rate, was applied to oranges, lemons, and grapefruit; a 10-fold higher rate was also applied to oranges. Immediately postapplication, {sup 14}C residues were 20-38 ng/g for the fruit treated at the field rate. Most of the residue was recovered in the surface solvent rinse at less than 2 weeks postapplication; however, after this time more of the residue was recovered from the rind fraction. The total recoveries of applied radioactivity were 61-90% and 33-50% at 1 and 12 weeks postapplication, respectively. The level of unextractable rind {sup 14}Cmore » residue from oranges treated at the 10{times} rate and harvested at 12 weeks (a worse case) was 4.9% of the applied dose (<2 ppb at the field rate). The inner pulp samples for all treatments had {sup 14}C residue levels below the detection limit of 0.4-0.8 ppb. The initial depletion half-life of avermectin B{sub 1a} was <1 week, with losses occurring within 30-40 min. For the 1-12-week postapplication period, the avermectin B{sub 1a} and {sup 14}C residue depletion half-lives were 20-38 and 56-98 days, respectively. Differences in the rate of dissipation of avermectin B{sub 1a} due to fruit type and application rate were observed.« less

[Measurement of the electric field of the heart in a homogeneous volume conductor].

PubMed

Tsukerman, B M; Titomir, L I

1975-01-01

The paper describes a technique and some results of experimental measurements of electrical potentials generated by an isolated dog heart in homogeneous conductor, drawing equipotential maps of the field, and calculating the characteristics of the dipole equivalent generator of the heart. The form of potential distribution on a spherical surface around the heart and its ideal orthogonal vectorcardiograms are discussed.

Insecticidal components from field pea extracts: sequences of some variants of pea albumin 1b.

PubMed

Taylor, Wesley G; Sutherland, Daniel H; Olson, Douglas J H; Ross, Andrew R S; Fields, Paul G

2004-12-15

Methanol soluble insecticidal peptides with masses of 3752, 3757, and 3805 Da, isolated from crude extracts (C8 extracts) derived from the protein-enriched flour of commercial field peas [Pisum sativum (L.)], were purified by reversed phase chromatography and, after reduction and alkylation, were sequenced by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry with the aid of various peptidases. These major peptides were variants of pea albumin 1b (PA1b) with methionine sulfoxide rather than methionine at position 12. Peptide 3752 showed additional variations at positions 29 (valine for isoleucine) and 34 (histidine for asparagine). A minor, 37 amino acid peptide with a molecular mass of 3788 Da was also sequenced and differed from a known PA1b variant at positions 1, 25, and 31. Sequence variants of PA1b with their molecular masses were compiled, and variants that matched the accurate masses of the experimental peptides were used to narrow the search. MALDI postsource decay experiments on pronase fragments helped to confirm the sequences. Whole and dehulled field peas gave insecticidal C8 extracts in the laboratory that were enriched in peptides with masses of 3736, 3741, and 3789 Da, as determined by high-performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry. It was therefore concluded that oxidation of the methionine residues to methionine sulfoxide occurred primarily during the processing of dehulled peas in a mill.

Partial homogeneity based high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Zhiliang; Lin, Liangjie; Lin, Yanqin, E-mail: linyq@xmu.edu.cn, E-mail: chenz@xmu.edu.cn

2014-09-29

In nuclear magnetic resonance (NMR) technique, it is of great necessity and importance to obtain high-resolution spectra, especially under inhomogeneous magnetic fields. In this study, a method based on partial homogeneity is proposed for retrieving high-resolution one-dimensional NMR spectra under inhomogeneous fields. Signals from series of small voxels, which characterize high resolution due to small sizes, are recorded simultaneously. Then, an inhomogeneity correction algorithm is developed based on pattern recognition to correct the influence brought by field inhomogeneity automatically, thus yielding high-resolution information. Experiments on chemical solutions and fish spawn were carried out to demonstrate the performance of the proposedmore » method. The proposed method serves as a single radiofrequency pulse high-resolution NMR spectroscopy under inhomogeneous fields and may provide an alternative of obtaining high-resolution spectra of in vivo living systems or chemical-reaction systems, where performances of conventional techniques are usually degenerated by field inhomogeneity.« less

Absence of B1-B2 structural transition in lithium halides under hydrostatic pressure

NASA Astrophysics Data System (ADS)

de Coss, Romeo; Murrieta, Gabriel

2005-03-01

We have investigated the B1-B2 structural transition in LiF, LiCl, LiBr, and LiI under hydrostatic pressure by means of first-principles total-energy calculations using the Full- Potential LAPW method. In order to analyze the gradient effects, we have performed calculations using the local density approximation (LDA) and the generalized gradient approximation (GGA), for the exchange and correlation potential. In agreement with the experimental observations, we find that even for pressures higher than 100 GPa, the Li halides do not present the B1-B2 structural transition. In order to understand this behavior, we have calculated the distribution of the electron densities. From the analysis of the distribution of electron densities for the Li halides in the B1 and B2 phases, we find that for this group of ionic compounds the B1 phase have a distribution of electron densities more homogeneous than in the B2 phase, preventing the B1-B2 structural transition. This work was partially supported by Consejo Nacional de Ciencia y Tecnolog'ia (CONACYT, M'exico) under Grant No. 43830-F.

Root mean square fluctuation of a weak magnetic field in an infinite medium of homogeneous stationary turbulence.

NASA Technical Reports Server (NTRS)

Low, B.-C.

1972-01-01

The generation of a magnetic field by statistically homogeneous, stationary velocity turbulence is considered. The generation of rms magnetic fluctuation is explicitly demonstrated in the limit of short turbulence correlation time. It is shown that the fluctuation associated with a growing or stationary mean field grows with time such that the ratio of the fluctuation and the square of the mean field tends to a steady value, which is a monotonically decreasing function of the growth rate of the mean field.

A homogeneous superconducting magnet design using a hybrid optimization algorithm

NASA Astrophysics Data System (ADS)

Ni, Zhipeng; Wang, Qiuliang; Liu, Feng; Yan, Luguang

2013-12-01

This paper employs a hybrid optimization algorithm with a combination of linear programming (LP) and nonlinear programming (NLP) to design the highly homogeneous superconducting magnets for magnetic resonance imaging (MRI). The whole work is divided into two stages. The first LP stage provides a global optimal current map with several non-zero current clusters, and the mathematical model for the LP was updated by taking into account the maximum axial and radial magnetic field strength limitations. In the second NLP stage, the non-zero current clusters were discretized into practical solenoids. The superconducting conductor consumption was set as the objective function both in the LP and NLP stages to minimize the construction cost. In addition, the peak-peak homogeneity over the volume of imaging (VOI), the scope of 5 Gauss fringe field, and maximum magnetic field strength within superconducting coils were set as constraints. The detailed design process for a dedicated 3.0 T animal MRI scanner was presented. The homogeneous magnet produces a magnetic field quality of 6.0 ppm peak-peak homogeneity over a 16 cm by 18 cm elliptical VOI, and the 5 Gauss fringe field was limited within a 1.5 m by 2.0 m elliptical region.

Gynogenesis in carp, Cyprinus Carpio L. and tench, Tinca Tinca L. induced by 60Co radiation in highly homogeneous radiating field

NASA Astrophysics Data System (ADS)

Pipota, J.; Linhart, O.

The paper deals with a method of fertility inactivation of fish spermatozoa by gamma radiation. Spermatozoa motility remained unchanged after irradiation. Irradiated sperm has been utilized to induced gynogenesis by means of retention of the second polar body and of mitotic gynogenesis, realized in carp for the first time. Homogeneity of gamma-rays field was + - 1 %.

Crystallization and preliminary X-ray analysis of human MTH1 with a homogeneous N-terminus.

PubMed

Koga, Yukari; Inazato, Miyuki; Nakamura, Teruya; Hashikawa, Chie; Chirifu, Mami; Michi, Asuka; Yamashita, Taku; Toma, Sachiko; Kuniyasu, Akihiko; Ikemizu, Shinji; Nakabeppu, Yusaku; Yamagata, Yuriko

2013-01-01

Human MTH1 (hMTH1) is an enzyme that hydrolyses several oxidized purine nucleoside triphosphates to their corresponding nucleoside monophosphates. Crystallographic studies have shown that the accurate mode of interaction between 8-oxoguanine and hMTH1 cannot be understood without determining the positions of the H atoms, as can be observed in neutron and/or ultrahigh-resolution X-ray diffraction studies. The hMTH1 protein prepared in the original expression system from Escherichia coli did not appear to be suitable for obtaining high-quality crystals because the hMTH1 protein had heterogeneous N-termini of Met1 and Gly2 that resulted from N-terminal Met excision by methionine aminopeptidase from the E. coli host. To obtain homogeneous hMTH1, the Gly at the second position was replaced by Lys. As a result, mutant hMTH1 protein [hMTH1(G2K)] with a homogeneous N-terminus could be prepared and high-quality crystals which diffracted to near 1.1 Å resolution using synchrotron radiation were produced. The new crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 46.36, b = 47.58, c = 123.89 Å.

Optimization study on the magnetic field of superconducting Halbach Array magnet

NASA Astrophysics Data System (ADS)

Shen, Boyang; Geng, Jianzhao; Li, Chao; Zhang, Xiuchang; Fu, Lin; Zhang, Heng; Ma, Jun; Coombs, T. A.

2017-07-01

This paper presents the optimization on the strength and homogeneity of magnetic field from superconducting Halbach Array magnet. Conventional Halbach Array uses a special arrangement of permanent magnets which can generate homogeneous magnetic field. Superconducting Halbach Array utilizes High Temperature Superconductor (HTS) to construct an electromagnet to work below its critical temperature, which performs equivalently to the permanent magnet based Halbach Array. The simulations of superconducting Halbach Array were carried out using H-formulation based on B-dependent critical current density and bulk approximation, with the FEM platform COMSOL Multiphysics. The optimization focused on the coils' location, as well as the geometry and numbers of coils on the premise of maintaining the total amount of superconductor. Results show Halbach Array configuration based superconducting magnet is able to generate the magnetic field with intensity over 1 Tesla and improved homogeneity using proper optimization methods. Mathematical relation of these optimization parameters with the intensity and homogeneity of magnetic field was developed.

Crystallization and preliminary X-ray analysis of human MTH1 with a homogeneous N-terminus

PubMed Central

Koga, Yukari; Inazato, Miyuki; Nakamura, Teruya; Hashikawa, Chie; Chirifu, Mami; Michi, Asuka; Yamashita, Taku; Toma, Sachiko; Kuniyasu, Akihiko; Ikemizu, Shinji; Nakabeppu, Yusaku; Yamagata, Yuriko

2013-01-01

Human MTH1 (hMTH1) is an enzyme that hydrolyses several oxidized purine nucleoside triphosphates to their corresponding nucleoside monophosphates. Crystallographic studies have shown that the accurate mode of interaction between 8-oxoguanine and hMTH1 cannot be understood without determining the positions of the H atoms, as can be observed in neutron and/or ultrahigh-resolution X-ray diffraction studies. The hMTH1 protein prepared in the original expression system from Escherichia coli did not appear to be suitable for obtaining high-quality crystals because the hMTH1 protein had heterogeneous N-termini of Met1 and Gly2 that resulted from N-terminal Met excision by methionine aminopeptidase from the E. coli host. To obtain homogeneous hMTH1, the Gly at the second position was replaced by Lys. As a result, mutant hMTH1 protein [hMTH1(G2K)] with a homogeneous N-terminus could be prepared and high-quality crystals which diffracted to near 1.1 Å resolution using synchrotron radiation were produced. The new crystals belonged to space group P212121, with unit-cell parameters a = 46.36, b = 47.58, c = 123.89 Å. PMID:23295485

The ace-1 Locus Is Amplified in All Resistant Anopheles gambiae Mosquitoes: Fitness Consequences of Homogeneous and Heterogeneous Duplications

PubMed Central

Djogbénou, Luc S.; Berthomieu, Arnaud; Makoundou, Patrick; Baba-Moussa, Lamine S.; Fiston-Lavier, Anna-Sophie; Belkhir, Khalid; Labbé, Pierrick; Weill, Mylène

2016-01-01

Gene copy-number variations are widespread in natural populations, but investigating their phenotypic consequences requires contemporary duplications under selection. Such duplications have been found at the ace-1 locus (encoding the organophosphate and carbamate insecticides’ target) in the mosquito Anopheles gambiae (the major malaria vector); recent studies have revealed their intriguing complexity, consistent with the involvement of various numbers and types (susceptible or resistant to insecticide) of copies. We used an integrative approach, from genome to phenotype level, to investigate the influence of duplication architecture and gene-dosage on mosquito fitness. We found that both heterogeneous (i.e., one susceptible and one resistant ace-1 copy) and homogeneous (i.e., identical resistant copies) duplications segregated in field populations. The number of copies in homogeneous duplications was variable and positively correlated with acetylcholinesterase activity and resistance level. Determining the genomic structure of the duplicated region revealed that, in both types of duplication, ace-1 and 11 other genes formed tandem 203kb amplicons. We developed a diagnostic test for duplications, which showed that ace-1 was amplified in all 173 resistant mosquitoes analyzed (field-collected in several African countries), in heterogeneous or homogeneous duplications. Each type was associated with different fitness trade-offs: heterogeneous duplications conferred an intermediate phenotype (lower resistance and fitness costs), whereas homogeneous duplications tended to increase both resistance and fitness cost, in a complex manner. The type of duplication selected seemed thus to depend on the intensity and distribution of selection pressures. This versatility of trade-offs available through gene duplication highlights the importance of large mutation events in adaptation to environmental variation. This impressive adaptability could have a major impact on vector

Soluble Molecularly Imprinted Nanorods for Homogeneous Molecular Recognition

NASA Astrophysics Data System (ADS)

Liang, Rongning; Wang, Tiantian; Zhang, Huan; Yao, Ruiqing; Qin, Wei

2018-03-01

Nowadays, it is still difficult for molecularly imprinted polymer (MIPs) to achieve homogeneous recognition since they cannot be easily dissolved in organic or aqueous phase. To address this issue, soluble molecularly imprinted nanorods have been synthesized by using soluble polyaniline doped with a functionalized organic protonic acid as the polymer matrix. By employing 1-naphthoic acid as a model, the proposed imprinted nanorods exhibit an excellent solubility and good homogeneous recognition ability. The imprinting factor for the soluble imprinted nanoroads is 6.8. The equilibrium dissociation constant and the apparent maximum number of the proposed imprinted nanorods are 248.5 μM and 22.1 μmol/g, respectively. We believe that such imprinted nanorods may provide an appealing substitute for natural receptors in homogeneous recognition related fields.

Cell Identity Switching Regulated by Retinoic Acid Signaling Maintains Homogeneous Segments in the Hindbrain.

PubMed

Addison, Megan; Xu, Qiling; Cayuso, Jordi; Wilkinson, David G

2018-06-04

The patterning of tissues to form subdivisions with distinct and homogeneous regional identity is potentially disrupted by cell intermingling. Transplantation studies suggest that homogeneous segmental identity in the hindbrain is maintained by identity switching of cells that intermingle into another segment. We show that switching occurs during normal development and is mediated by feedback between segment identity and the retinoic acid degrading enzymes, cyp26b1 and cyp26c1. egr2, which specifies the segmental identity of rhombomeres r3 and r5, underlies the lower expression level of cyp26b1 and cyp26c1 in r3 and r5 compared with r2, r4, and r6. Consequently, r3 or r5 cells that intermingle into adjacent segments encounter cells with higher cyp26b1/c1 expression, which we find is required for downregulation of egr2b expression. Furthermore, egr2b expression is regulated in r2, r4, and r6 by non-autonomous mechanisms that depend upon the number of neighbors that express egr2b. These findings reveal that a community regulation of retinoid signaling maintains homogeneous segmental identity. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Synthesis of focused beam with controllable arbitrary homogeneous polarization using engineered vectorial optical fields.

PubMed

Rui, Guanghao; Chen, Jian; Wang, Xiaoyan; Gu, Bing; Cui, Yiping; Zhan, Qiwen

2016-10-17

The propagation and focusing properties of light beams continue to remain a research interest owning to their promising applications in physics, chemistry and biological sciences. One of the main challenges to these applications is the control of polarization distribution within the focal volume. In this work, we propose and experimentally demonstrate a method for generating a focused beam with arbitrary homogeneous polarization at any transverse plane. The required input field at the pupil plane of a high numerical aperture objective lens can be found analytically by solving an inverse problem with the Richard-Wolf vectorial diffraction method, and can be experimentally created with a vectorial optical field generator. Focused fields with various polarizations are successfully generated and verified using a Stokes parameter measurement to demonstrate the capability and versatility of proposed technique.

Significantly enhanced critical current density in nano-MgB2 grains rapidly formed at low temperature with homogeneous carbon doping

NASA Astrophysics Data System (ADS)

Liu, Yongchang; Lan, Feng; Ma, Zongqing; Chen, Ning; Li, Huijun; Barua, Shaon; Patel, Dipak; Shahriar, M.; Hossain, Al; Acar, S.; Kim, Jung Ho; Xue Dou, Shi

2015-05-01

High performance MgB2 bulks using carbon-coated amorphous boron as a boron precursor were fabricated by Cu-activated sintering at low temperature (600 °C, below the Mg melting point). Dense nano-MgB2 grains with a high level of homogeneous carbon doping were formed in these MgB2 samples. This type of microstructure can provide a stronger flux pinning force, together with depressed volatility and oxidation of Mg owing to the low-temperature Cu-activated sintering, leading to a significant improvement of critical current density (Jc) in the as-prepared samples. In particular, the value of Jc for the carbon-coated (Mg1.1B2)Cu0.05 sample prepared here is even above 1 × 105 A cm-2 at 20 K, 2 T. The results herein suggest that the combination of low-temperature Cu-activated sintering and employment of carbon-coated amorphous boron as a precursor could be a promising technique for the industrial production of practical MgB2 bulks or wires with excellent Jc, as the carbon-coated amorphous boron powder can be produced commercially at low cost, while the addition of Cu is very convenient and inexpensive.

B1 gradient coherence selection using a tapered stripline.

PubMed

van Meerten, S G J; Tijssen, K C H; van Bentum, P J M; Kentgens, A P M

2018-01-01

Pulsed-field gradients are common in modern liquid state NMR pulse sequences. They are often used instead of phase cycles for the selection of coherence pathways, thereby decreasing the time required for the NMR experiment. Soft off-resonance pulses with a B 1 gradient result in a spatial encoding similar to that created by pulsed-field (B 0 ) gradients. In this manuscript we show that pulse sequences with pulsed-field gradients can easily be converted to one which uses off-resonance B 1 field gradient (OFFBEAT) pulses. The advantage of B 1 gradient pulses for coherence selection is that the chemical shift evolution during the pulses is (partially) suppressed. Therefore no refocusing echos are required to correct for evolution during the gradient pulses. A tapered stripline is shown to be a convenient tool for creating a well-defined gradient in the B 1 field strength. B 1 gradient coherence selection using a tapered stripline is a simple and cheap alternative to B 0 pulsed-field gradients. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Comparison of homogenization techniques and incidence of aflatoxin contamination in dried figs for export.

PubMed

Bircan, Cavit

2009-01-01

To determine differences in mean aflatoxin contamination and subsample variance from dry and slurry homogenizations, 10 kg of six different, naturally contaminated dried fig samples were collected from various exporting companies in accordance with the EU Commission Directive. The samples were first dry-mixed for 5 min using a blender and sub-sampled seven times; the remainder was slurry homogenized (1 : 1, v/v) and sub-sampled seven times. Aflatoxin B1 and total aflatoxin levels were recorded and coefficient of variations (CV) computed for all sub-samples. Only a small reduction in sub-sample variations, indicated by the lower CV values, and slight differences in mean aflatoxin B1 and total aflatoxin levels were observed when slurry homogenization was applied. Therefore, 7326 dried figs, destined for export from Turkey to the EU and collected during the 2008 crop year, were dry-homogenized and tested for aflatoxins (B1, B2, G1 and G2) by immunoaffinity column clean-up using RP-HPLC. While 34% of the samples contained detectable levels of total aflatoxins (0.20-208.75 µg kg(-1)), only 9% of them exceeded the EU limit of 4 µg kg(-1) in the range 2.0-208.75 µg kg(-1), respectively. A substantial increase in the incidence of aflatoxins was observed in 2008, most likely due to the drought stress experienced in Aydin province as occurred in 2007.

Evolution of Fermi Surface Properties in CexLa1-xB6 and PrxLa1-xB6

NASA Astrophysics Data System (ADS)

Endo, Motoki; Nakamura, Shintaro; Isshiki, Toshiyuki; Kimura, Noriaki; Nojima, Tsutomu; Aoki, Haruyoshi; Harima, Hisatomo; Kunii, Satoru

2006-11-01

We report the de Haas-van Alphen (dHvA) effect measurements of the Fermi surface properties in LaB6, CexLa1-xB6 (x = 0.1, 0.25, 0.5, 0.75, 1.0) and PrxLa1-xB6 (x = 0.25, 0.5, 0.75, 1.0) with particular attention to the spin dependence of the Fermi surface properties. The Fermi surface shape and dimension of CexLa1-xB6 change considerably with Ce concentration, while those of PrxLa1-xB6 change very slightly up to x = 0.75, and in PrB6 the Fermi surface splits into the up and down spin Fermi surfaces. The effective mass of CexLa1-xB6 increases considerably with Ce concentration and is nearly proportional to the number of Ce ions, whereas that of PrxLa1-xB6 increases slightly with Pr concentration. In CexLa1-xB6 the effective mass depends very strongly on field and increases divergently with decreasing field, while that of PrxLa1-xB6 increases slightly with decreasing field. The contribution to the dHvA signal from the conduction electrons of one spin direction diminishes with Ce concentration and appears to disappear somewhere around x = 0.25--0.5. A weak spin dependence is also found in PrxLa1-xB6. The behaviors of CexLa1-xB6 and PrxLa1-xB6 are compared to discuss the origin of the spin dependence of the Fermi surface properties.

Peripheral nerve magnetic stimulation: influence of tissue non-homogeneity

PubMed Central

Krasteva, Vessela TZ; Papazov, Sava P; Daskalov, Ivan K

2003-01-01

Background Peripheral nerves are situated in a highly non-homogeneous environment, including muscles, bones, blood vessels, etc. Time-varying magnetic field stimulation of the median and ulnar nerves in the carpal region is studied, with special consideration of the influence of non-homogeneities. Methods A detailed three-dimensional finite element model (FEM) of the anatomy of the wrist region was built to assess the induced currents distribution by external magnetic stimulation. The electromagnetic field distribution in the non-homogeneous domain was defined as an internal Dirichlet problem using the finite element method. The boundary conditions were obtained by analysis of the vector potential field excited by external current-driven coils. Results The results include evaluation and graphical representation of the induced current field distribution at various stimulation coil positions. Comparative study for the real non-homogeneous structure with anisotropic conductivities of the tissues and a mock homogeneous media is also presented. The possibility of achieving selective stimulation of either of the two nerves is assessed. Conclusion The model developed could be useful in theoretical prediction of the current distribution in the nerves during diagnostic stimulation and therapeutic procedures involving electromagnetic excitation. The errors in applying homogeneous domain modeling rather than real non-homogeneous biological structures are demonstrated. The practical implications of the applied approach are valid for any arbitrary weakly conductive medium. PMID:14693034

Geologic Field Notes, Geochemical Analyses, and Field Photographs of Outcrops and Rock Samples from the Big Delta B-1 Quadrangle, East-Central Alaska

USGS Publications Warehouse

Day, Warren C.; O'Neill, J. Michael

2008-01-01

The U.S. Geological Survey, in cooperation with the Alaska Department of Natural Resources Division of Mining, Land, and Water, has released a geologic map of the Big Delta B-1 quadrangle of east-central Alaska (Day and others, 2007). This companion report presents the major element oxide and trace element geochemical analyses, including those for gold, silver, and base metals, for representative rock units and for grab samples from quartz veins and mineralized zones within the quadrangle. Also included are field station locations, field notes, structural data, and field photographs based primarily on observations by W.C. Day with additions by J.M. O'Neill and B.M. Gamble, all of the U.S. Geological Survey. The data are provided in both Microsoft Excel spread sheet format and as a Microsoft Access database.

GOME/ERS-2: New Homogeneous Level 1B Data from an Old Instrument

NASA Astrophysics Data System (ADS)

Slijkhuis, S.; Aberle, B.; Coldewey-Egbers, M.; Loyola, D.; Dehn, A.; Fehr, T.

2015-11-01

In the framework of ESA's "GOME Evolution Project", a reprocessing will be made of the entire 16 year GOME Level 1 dataset. The GOME Evolution Project further includes the generation of a new GOME water vapour product, and a public outreach programme.In this paper we will describe the reprocessing of the Level 1 data, carried out with the latest version of the GOME Data Processor at DLR. The change most visible to the user will be the new product format in NetCDF, plus supporting documentation (ATBD and PUM). Full-mission reprocessed L1b data are expected to be released in the 4th quarter of 2015.

Heat treatment of unclarified Escherichia coli homogenate improved the recovery efficiency of recombinant hepatitis B core antigen.

PubMed

Ng, Michelle Y T; Tan, Wen Siang; Abdullah, Norhafizah; Ling, Tau Chuan; Tey, Beng Ti

2006-10-01

Heat precipitation procedure has been regularly incorporated as a selective purification step in various thermostable proteins expressed in different hosts. This method is efficient in precipitation of most of the host proteins and also deactivates various host proteases that can be harmful to the desired gene products. In this study, introduction of heat treatment procedure in the purification of hepatitis B core antigen (HBcAg) produced in Escherichia coli has been investigated. Thermal treatment of the cell homogenate at 60 degrees C for 30 min prior to subsequent clarification steps has resulted in 1.4 times and 18% higher in purity and recovery yield, respectively, compared to the non-heat-treated cell homogenate. In direct capture of HBcAg by using anion-exchangers from unclarified feedstock, pre-conditioning the feedstock by heat treatment at 60 degrees C for 45 min has increased the recovery yield of HBcAg by 2.9-fold and 42% in purity compared to that treated for 10 min. Enzyme-linked immunosorbent assay (ELISA) analysis showed that the antigenicity of the core particles was not affected by the heat treatment process.

Quantum transport and the Wigner distribution function for Bloch electrons in spatially homogeneous electric and magnetic fields

NASA Astrophysics Data System (ADS)

Iafrate, G. J.; Sokolov, V. N.; Krieger, J. B.

2017-10-01

The theory of Bloch electron dynamics for carriers in homogeneous electric and magnetic fields of arbitrary time dependence is developed in the framework of the Liouville equation. The Wigner distribution function (WDF) is determined from the single-particle density matrix in the ballistic regime, i.e., collision effects are excluded. In the theory, the single-particle transport equation is established with the electric field described in the vector potential gauge, and the magnetic field is treated in the symmetric gauge. No specific assumptions are made concerning the form of the initial distribution in momentum or configuration space. The general approach is to employ the accelerated Bloch state representation (ABR) as a basis so that the dependence upon the electric field, including multiband Zener tunneling, is treated exactly. Further, in the formulation of the WDF, we transform to a new set of variables so that the final WDF is gauge invariant and is expressed explicitly in terms of the position, kinetic momentum, and time. The methodology for developing the WDF is illustrated by deriving the exact WDF equation for free electrons in homogeneous electric and magnetic fields resulting in the same form as given by the collisionless Boltzmann transport equation (BTE). The methodology is then extended to the case of electrons described by an effective Hamiltonian corresponding to an arbitrary energy band function; the exact WDF equation results for the effective Hamiltonian case are shown to approximate the free electron results when taken to second order in the magnetic field. As a corollary, in these cases, it is shown that if the WDF is a wave packet, then the time rate of change of the electron quasimomentum is given by the Lorentz force. In treating the problem of Bloch electrons in a periodic potential in the presence of homogeneous electric and magnetic fields, the methodology for deriving the WDF reveals a multiband character due to the inherent nature of

Method of Mapping Anomalies in Homogenous Material

NASA Technical Reports Server (NTRS)

Taylor, Bryant D. (Inventor); Woodard, Stanley E. (Inventor)

2016-01-01

An electrical conductor and antenna are positioned in a fixed relationship to one another. Relative lateral movement is generated between the electrical conductor and a homogenous material while maintaining the electrical conductor at a fixed distance from the homogenous material. The antenna supplies a time-varying magnetic field that causes the electrical conductor to resonate and generate harmonic electric and magnetic field responses. Disruptions in at least one of the electric and magnetic field responses during this lateral movement are indicative of a lateral location of a subsurface anomaly. Next, relative out-of-plane movement is generated between the electrical conductor and the homogenous material in the vicinity of the anomaly's lateral location. Disruptions in at least one of the electric and magnetic field responses during this out-of-plane movement are indicative of a depth location of the subsurface anomaly. A recording of the disruptions provides a mapping of the anomaly.

Stimulus homogeneity enhances implicit learning: evidence from contextual cueing.

PubMed

Feldmann-Wüstefeld, Tobias; Schubö, Anna

2014-04-01

Visual search for a target object is faster if the target is embedded in a repeatedly presented invariant configuration of distractors ('contextual cueing'). It has also been shown that the homogeneity of a context affects the efficiency of visual search: targets receive prioritized processing when presented in a homogeneous context compared to a heterogeneous context, presumably due to grouping processes at early stages of visual processing. The present study investigated in three Experiments whether context homogeneity also affects contextual cueing. In Experiment 1, context homogeneity varied on three levels of the task-relevant dimension (orientation) and contextual cueing was most pronounced for context configurations with high orientation homogeneity. When context homogeneity varied on three levels of the task-irrelevant dimension (color) and orientation homogeneity was fixed, no modulation of contextual cueing was observed: high orientation homogeneity led to large contextual cueing effects (Experiment 2) and low orientation homogeneity led to low contextual cueing effects (Experiment 3), irrespective of color homogeneity. Enhanced contextual cueing for homogeneous context configurations suggest that grouping processes do not only affect visual search but also implicit learning. We conclude that memory representation of context configurations are more easily acquired when context configurations can be processed as larger, grouped perceptual units. However, this form of implicit perceptual learning is only improved by stimulus homogeneity when stimulus homogeneity facilitates grouping processes on a dimension that is currently relevant in the task. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultrasound and polar homogeneous reactions.

PubMed

Tuulmets, A

1997-04-01

The effect of ultrasound on the rates of homogeneous heterolytic reactions not switched to a free radical pathway can be explained by the perturbation of the molecular organization of or the solvation in the reacting system. A quantitative analysis of the sonochemical acceleration on the basis of the microreactor concept was carried out. It was found that (1) the Diels-Alder reaction cannot be accelerated by ultrasound except when SET or free radical processes are promoted, (2) the rectified diffusion during cavitation cannot be responsible for the acceleration of reactions, and (3) the sonochemical acceleration of polar homogeneous reactions takes place in the bulk reaction medium. This implies the presence of a 'sound-field' sonochemistry besides the 'hot-spot' sonochemistry. The occurrence of a sonochemical deceleration effect can be predicted.

[Growth Factors and Interleukins in Amniotic Membrane Tissue Homogenate].

PubMed

Stachon, T; Bischoff, M; Seitz, B; Huber, M; Zawada, M; Langenbucher, A; Szentmáry, N

2015-07-01

Application of amniotic membrane homogenate eye drops may be a potential treatment alternative for therapy resistant corneal epithelial defects. The purpose of this study was to determine the concentrations of epidermal growth factor (EGF), fibroblast growth factor basic (bFGF), hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), interleukin-6 (IL-6) and interleukin-8 (IL-8) in amniotic membrane homogenates. Amniotic membranes of 8 placentas were prepared and thereafter stored at - 80 °C using the standard methods of the LIONS Cornea Bank Saar-Lor-Lux, Trier/Westpfalz. Following defreezing, amniotic membranes were cut in two pieces and homogenized in liquid nitrogen. One part of the homogenate was prepared in cell-lysis buffer, the other part was prepared in PBS. The tissue homogenates were stored at - 20 °C until enzyme-linked immunosorbent assay (ELISA) analysis for EGF, bFGF, HGF, KGF, IL-6 and IL-8 concentrations. Concentrations of KGF, IL-6 and IL-8 were below the detection limit using both preparation techniques. The EGF concentration in tissue homogenates treated with cell-lysis buffer (2412 pg/g tissue) was not significantly different compared to that of tissue homogenates treated with PBS (1586 pg/g tissue, p = 0.72). bFGF release was also not significantly different using cell-lysis buffer (3606 pg/g tissue) or PBS treated tissue homogenates (4649 pg/g tissue, p = 0.35). HGF release was significantly lower using cell-lysis buffer (23,555 pg/g tissue), compared to PBS treated tissue (47,766 pg/g tissue, p = 0.007). Containing EGF, bFGF and HGF, and lacking IL-6 and IL-8, the application of amniotic membrane homogenate eye drops may be a potential treatment alternative for therapy-resistant corneal epithelial defects. Georg Thieme Verlag KG Stuttgart · New York.

Ultrahigh-Resolution Magnetic Resonance in Inhomogeneous Magnetic Fields: Two-Dimensional Long-Lived-Coherence Correlation Spectroscopy

NASA Astrophysics Data System (ADS)

Chinthalapalli, Srinivas; Bornet, Aurélien; Segawa, Takuya F.; Sarkar, Riddhiman; Jannin, Sami; Bodenhausen, Geoffrey

2012-07-01

A half-century quest for improving resolution in Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) has enabled the study of molecular structures, biological interactions, and fine details of anatomy. This progress largely relied on the advent of sophisticated superconducting magnets that can provide stable and homogeneous fields with temporal and spatial variations below ΔB0/B0<0.01ppm. In many cases however, inherent properties of the objects under investigation, pulsating arteries, breathing lungs, tissue-air interfaces, surgical implants, etc., lead to fluctuations and losses of local homogeneity. A new method dubbed “long-lived-coherence correlation spectroscopy” (LLC-COSY) opens the way to overcome both inhomogeneous and homogeneous broadening, which arise from local variations in static fields and fluctuating dipole-dipole interactions, respectively. LLC-COSY makes it possible to obtain ultrahigh resolution two-dimensional spectra, with linewidths on the order of Δν=0.1 to 1 Hz, even in very inhomogeneous fields (ΔB0/B0>10ppm or 5000 Hz at 9.7 T), and can improve resolution by a factor up to 9 when the homogeneous linewidths are determined by dipole-dipole interactions. The resulting LLC-COSY spectra display chemical shift differences and scalar couplings in two orthogonal dimensions, like in “J spectroscopy.” LLC-COSY does not require any sophisticated gradient switching or frequency-modulated pulses. Applications to in-cell NMR and to magnetic resonance spectroscopy (MRS) of selected volume elements in MRI appear promising, particularly when susceptibility variations tend to preclude high resolution.

ODE/IM correspondence for modified B2(1) affine Toda field equation

NASA Astrophysics Data System (ADS)

Ito, Katsushi; Shu, Hongfei

2017-03-01

We study the massive ODE/IM correspondence for modified B2(1) affine Toda field equation. Based on the ψ-system for the solutions of the associated linear problem, we obtain the Bethe ansatz equations. We also discuss the T-Q relations, the T-system and the Y-system, which are shown to be related to those of the A3 /Z2 integrable system. We consider the case that the solution of the linear problem has a monodromy around the origin, which imposes nontrivial boundary conditions for the T-/Y-system. The high-temperature limit of the T- and Y-system and their monodromy dependence are studied numerically.

Synthesis of organosilicon derivatives of [1]benzothieno[3,2-b][1]-benzothiophene for efficient monolayer Langmuir-Blodgett organic field effect transistors.

PubMed

Borshchev, O V; Sizov, A S; Agina, E V; Bessonov, A A; Ponomarenko, S A

2017-01-16

For the first time, the synthesis of organosilicon derivatives of dialkyl[1]benzothieno[3,2-b][1]-benzothiophene (BTBT) capable of forming a semiconducting monolayer at the water-air interface is reported. Self-assembled monolayer organic field-effect transistors prepared from these materials using the Langmuir-Blodgett technique showed high hole mobilities and excellent air stability.

Searching for primordial magnetic fields with CMB B-modes

NASA Astrophysics Data System (ADS)

Pogosian, Levon; Zucca, Alex

2018-06-01

Was the primordial universe magnetized? The answer to this question would help explain the origin of micro-Gauss strength magnetic fields observed in galaxies. It is also of fundamental importance in developing a complete theory of the early universe. While there can be other signatures of cosmological magnetic fields, a signature in the cosmic microwave background (CMB) would prove their primordial origin. The B-mode polarization of CMB is particularly promising in this regard because there are relatively few other sources of B-modes, and because the vortical modes sourced by the primordial magnetic field (PMF) survive diffusion damping up to a small fraction of the Silk length. At present, the Planck temperature and polarization spectra combined with the B-mode spectrum measured by the South Pole Telescope (SPT) constrain the PMF strength to be no more than  ∼1 nano-Gauss (nG). Because of the quartic scaling of the CMB anisotropy spectra with the PMF strength, this bound will not change by much even with the significantly better measurements of the B-mode spectrum by the Stage III and Stage IV CMB experiments. On the other hand, tightening the bound well below the 1 nG threshold would rule out the purely primordial origin (requiring no dynamo action) of galactic fields. Considering Faraday rotation, which converts some of the E-modes into B-modes and scales linearly with the field strength, will help to achieve this goal. As we demonstrate, the upcoming experiments, such as SPT-3G and the Simons Observatory, will be sensitive to fields of  ∼0.5 nG strength thanks to the mode-coupling signature induced by Faraday rotation. A future Stage IV ground based experiment or a space probe will be capable of probing fields below 0.1 nG, and would detect a scale-invariant PMF of 0.2 nG strength without de-lensing or subtracting the galactic rotation measure.

Anomalous B-field Dependence of Spin-flip Time in High Purity InP

NASA Astrophysics Data System (ADS)

Linpeng, Xiayu; Karin, Todd; Barbour, Russell; Glazov, Mikhail; Fu, Kai-Mei

2015-03-01

We observe an anomalous B-field dependence of the spin-flip time (T1) of electrons bound to shallow donors which cannot be explained by current spin-relaxation theories. We conduct resonant pump-probe measurements in high-purity InP from the low to high magnetic field regimes, with a maximum T1 (400 μs) observed near the turning point gμB B ~=kB T . At low B, the T1 dependence on B is consistent with an electron correlation time (τc) in the tens of nanoseconds. The physical mechanism for the short τc in this high-purity sample (n ~= 2 ×1014 cm-3) is unclear, but a strong temperature (T) dependence indicates T1 can be further increased by lowering T below the 1.5 K experimental temperature. At high B, a B-3 dependence is observed, in contrast to the expected B-5 predicted by single-phonon spin-orbit mediated interactions. An understanding of the anomalous B-field dependence is expected to elucidate the effect of electron transport (low-field) and phonons (high-field) on T1 for shallow donors, which is of interest for both ensemble and single-spin quantum information applications. This material is based upon work supported by the National Science Foundation under Grant No. 1150647, DGE-0718124 and DGE-1256082. InP samples were graciously provided by Simon Watkins at Simon Fraser University.

Calculations of B1 Distribution, Specific Energy Absorption Rate, and Intrinsic Signal-to-Noise Ratio for a Body-Size Birdcage Coil Loaded with Different Human Subjects at 64 and 128 MHz.

PubMed

Liu, W; Collins, C M; Smith, M B

2005-03-01

A numerical model of a female body is developed to study the effects of different body types with different coil drive methods on radio-frequency magnetic ( B 1 ) field distribution, specific energy absorption rate (SAR), and intrinsic signal-to-noise ratio (ISNR) for a body-size birdcage coil at 64 and 128 MHz. The coil is loaded with either a larger, more muscular male body model (subject 1) or a newly developed female body model (subject 2), and driven with two-port (quadrature), four-port, or many (ideal) sources. Loading the coil with subject 1 results in significantly less homogeneous B 1 field, higher SAR, and lower ISNR than those for subject 2 at both frequencies. This dependence of MR performance and safety measures on body type indicates a need for a variety of numerical models representative of a diverse population for future calculations. The different drive methods result in similar B 1 field patterns, SAR, and ISNR in all cases.

Refined Zigzag Theory for Homogeneous, Laminated Composite, and Sandwich Plates: A Homogeneous Limit Methodology for Zigzag Function Selection

NASA Technical Reports Server (NTRS)

Tessler, Alexander; DiSciuva, Marco; Gherlone, marco

2010-01-01

The Refined Zigzag Theory (RZT) for homogeneous, laminated composite, and sandwich plates is presented from a multi-scale formalism starting with the inplane displacement field expressed as a superposition of coarse and fine contributions. The coarse kinematic field is that of first-order shear-deformation theory, whereas the fine kinematic field has a piecewise-linear zigzag distribution through the thickness. The condition of limiting homogeneity of transverse-shear properties is proposed and yields four distinct sets of zigzag functions. By examining elastostatic solutions for highly heterogeneous sandwich plates, the best-performing zigzag functions are identified. The RZT predictive capabilities to model homogeneous and highly heterogeneous sandwich plates are critically assessed, demonstrating its superior efficiency, accuracy ; and a wide range of applicability. The present theory, which is derived from the virtual work principle, is well-suited for developing computationally efficient CO-continuous finite elements, and is thus appropriate for the analysis and design of high-performance load-bearing aerospace structures.

Single-channel, box-shaped, monopole-type antenna for B1+ field manipulation in conjunction with the traveling-wave concept in 9.4 T MRI.

PubMed

Zivkovic, Irena; Scheffler, Klaus

2015-08-01

We have developed a single-channel, box-shaped, monopole-type antenna which, if used in two different configurations, excites complementary B1+ field distributions in the traveling-wave setup. A new monopole-type, single-channel antenna for RF excitation in 9.4 T magnetic resonance imaging is proposed. The antenna is entirely made of copper without lumped elements. Two complementary B1+ field distributions of two different antenna configurations were measured and combined as a root sum of squares. B1+ field inhomogeneity of the combined maps was calculated and compared with published results. By combining B1+ field distributions generated by two antenna configurations, a "no voids" pattern was achieved for the entire upper brain. B1+ inhomogeneity of approximately 20 % was achieved for sagittal and transverse slices; it was <24 % for coronal slices. The results were comparable with those from CP, with "no voids" in slice B1+ inhomogeneity of multichannel loop arrays. The efficiency of the proposed antenna was lower than that of a multichannel array but comparable with that of a patch antenna. The proposed single-channel antenna is a promising candidate for traveling-wave brain imaging. It can be combined with the time-interleaved acquisition of modes (TIAMO) concept if reconfigurability is obtained with a single-antenna element.

Influence of homogeneous magnetic fields on the flow of a ferrofluid in the Taylor-Couette system.

PubMed

Altmeyer, S; Hoffmann, Ch; Leschhorn, A; Lücke, M

2010-07-01

We investigate numerically the influence of a homogeneous magnetic field on a ferrofluid in the gap between two concentric, independently rotating cylinders. The full Navier-Stokes equations are solved with a combination of a finite difference method and a Galerkin method. Structure, dynamics, symmetry properties, bifurcation, and stability behavior of different vortex structures are investigated for axial and transversal magnetic fields, as well as combinations of them. We show that a transversal magnetic field modulates the Taylor vortex flow and the spiral vortex flow. Thus, a transversal magnetic field induces wavy structures: wavy Taylor vortex flow (wTVF) and wavy spiral vortex flow. In contrast to the classic wTVF, which is a secondarily bifurcating structure, these magnetically generated wavy Taylor vortices are pinned by the magnetic field, i.e., they are stationary and they appear via a primary forward bifurcation out of the basic state of circular Couette flow.

Displacement Fields and Self-Energies of Circular and Polygonal Dislocation Loops in Homogeneous and Layered Anisotropic Solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Yanfei; Larson, Ben C.

There are large classes of materials problems that involve the solutions of stress, displacement, and strain energy of dislocation loops in elastically anisotropic solids, including increasingly detailed investigations of the generation and evolution of irradiation induced defect clusters ranging in sizes from the micro- to meso-scopic length scales. Based on a two-dimensional Fourier transform and Stroh formalism that are ideal for homogeneous and layered anisotropic solids, we have developed robust and computationally efficient methods to calculate the displacement fields for circular and polygonal dislocation loops. Using the homogeneous nature of the Green tensor of order -1, we have shown thatmore » the displacement and stress fields of dislocation loops can be obtained by numerical quadrature of a line integral. In addition, it is shown that the sextuple integrals associated with the strain energy of loops can be represented by the product of a pre-factor containing elastic anisotropy effects and a universal term that is singular and equal to that for elastic isotropic case. Furthermore, we have found that the self-energy pre-factor of prismatic loops is identical to the effective modulus of normal contact, and the pre-factor of shear loops differs from the effective indentation modulus in shear by only a few percent. These results provide a convenient method for examining dislocation reaction energetic and efficient procedures for numerical computation of local displacements and stresses of dislocation loops, both of which play integral roles in quantitative defect analyses within combined experimental–theoretical investigations.« less

Displacement Fields and Self-Energies of Circular and Polygonal Dislocation Loops in Homogeneous and Layered Anisotropic Solids

DOE PAGES

Gao, Yanfei; Larson, Ben C.

2015-06-19

There are large classes of materials problems that involve the solutions of stress, displacement, and strain energy of dislocation loops in elastically anisotropic solids, including increasingly detailed investigations of the generation and evolution of irradiation induced defect clusters ranging in sizes from the micro- to meso-scopic length scales. Based on a two-dimensional Fourier transform and Stroh formalism that are ideal for homogeneous and layered anisotropic solids, we have developed robust and computationally efficient methods to calculate the displacement fields for circular and polygonal dislocation loops. Using the homogeneous nature of the Green tensor of order -1, we have shown thatmore » the displacement and stress fields of dislocation loops can be obtained by numerical quadrature of a line integral. In addition, it is shown that the sextuple integrals associated with the strain energy of loops can be represented by the product of a pre-factor containing elastic anisotropy effects and a universal term that is singular and equal to that for elastic isotropic case. Furthermore, we have found that the self-energy pre-factor of prismatic loops is identical to the effective modulus of normal contact, and the pre-factor of shear loops differs from the effective indentation modulus in shear by only a few percent. These results provide a convenient method for examining dislocation reaction energetic and efficient procedures for numerical computation of local displacements and stresses of dislocation loops, both of which play integral roles in quantitative defect analyses within combined experimental–theoretical investigations.« less

Simplified correction of B1 inhomogeneity for chemical exchange saturation transfer (CEST) MRI measurement with surface transceiver coil

NASA Astrophysics Data System (ADS)

Sun, Phillip Z.; Zhou, Iris Y.; Igarashi, Takahiro; Guo, Yingkun; Xiao, Gang; Wu, Renhua

2015-03-01

Chemical exchange saturation transfer (CEST) MRI is sensitive to dilute exchangeable protons and local properties such as pH and temperate, yet its susceptibility to field inhomogeneity limits its in vivo applications. Particularly, CEST measurement varies with RF irradiation power, the dependence of which is complex due to concomitant direct RF saturation (RF spillover) effect. Because the volume transmitters provide relatively homogeneous RF field, they have been conventionally used for CEST imaging despite of their elevated specific absorption rate (SAR) and relatively low sensitivity than surface coils. To address this limitation, we developed an efficient B1 inhomogeneity correction algorithm that enables CEST MRI using surface transceiver coils. This is built on recent work that showed the inverse CEST asymmetry analysis (CESTRind) is not susceptible to confounding RF spillover effect. We here postulated that the linear relationship between RF power level and CESTRind can be extended for correcting B1 inhomogeneity induced CEST MRI artifacts. Briefly, we prepared a tissue-like Creatine gel pH phantom and collected multiparametric MRI including relaxation, field map and CEST MRI under multiple RF power levels, using a conventional surface transceiver coil. The raw CEST images showed substantial heterogeneity due to B1 inhomogeneity, with pH contrast to noise ratio (CNR) being 8.8. In comparison, pH MRI CNR of the fieldinhomogeneity corrected CEST MRI was found to be 17.2, substantially higher than that without correction. To summarize, our study validated an efficient field inhomogeneity correction that enables sensitive CEST MRI with surface transceiver, promising for in vivo translation.

Unveiling the thermal entanglement in a mixed-spin XXZ model with Dzyaloshinskii-Moriya interaction under a homogeneous magnetic field

NASA Astrophysics Data System (ADS)

Liu, Cheng-Cheng; Xu, Shuai; He, Juan; Ye, Liu

2015-10-01

We analytically investigate the thermal entanglement of three-mixed-spin (1/2, 1, 1/2) XXZ model with the DM interaction under an external magnetic field B. Two different cases are considered: one subsystem (1/2, 1/2) consists of two spin-1/2 fermions and the other subsystem (1/2, 1) contains a spin-1/2 fermion and a spin-1 boson. It is shown that the DM interaction parameter D, the external magnetic field strength B and coupling constant J have different effects on Fermi and mixed Fermi-Bose systems. All of the factors mentioned above can be utilized to control entanglement switch of any two particles in mixed spins model.

Genetic homogeneity of Fascioloides magna in Austria.

PubMed

Husch, Christian; Sattmann, Helmut; Hörweg, Christoph; Ursprung, Josef; Walochnik, Julia

2017-08-30

The large American liver fluke, Fascioloides magna, is an economically relevant parasite of both domestic and wild ungulates. F. magna was repeatedly introduced into Europe, for the first time already in the 19th century. In Austria, a stable population of F. magna has established in the Danube floodplain forests southeast of Vienna. The aim of this study was to determine the genetic diversity of F. magna in Austria. A total of 26 individuals from various regions within the known area of distribution were investigated for their cytochrome oxidase subunit 1 (cox1) and nicotinamide dehydrogenase subunit 1 (nad1) gene haplotypes. Interestingly, all 26 individuals revealed one and the same haplotype, namely concatenated haplotype Ha5. This indicates a homogenous population of F. magna in Austria and may argue for a single introduction. Alternatively, genetic homogeneity might also be explained by a bottleneck effect and/or genetic drift. Copyright © 2017 Elsevier B.V. All rights reserved.

Exploring entropic uncertainty relation in the Heisenberg XX model with inhomogeneous magnetic field

NASA Astrophysics Data System (ADS)

Huang, Ai-Jun; Wang, Dong; Wang, Jia-Ming; Shi, Jia-Dong; Sun, Wen-Yang; Ye, Liu

2017-08-01

In this work, we investigate the quantum-memory-assisted entropic uncertainty relation in a two-qubit Heisenberg XX model with inhomogeneous magnetic field. It has been found that larger coupling strength J between the two spin-chain qubits can effectively reduce the entropic uncertainty. Besides, we observe the mechanics of how the inhomogeneous field influences the uncertainty, and find out that when the inhomogeneous field parameter b<1, the uncertainty will decrease with the decrease of the inhomogeneous field parameter b, conversely, the uncertainty will increase with decreasing b under the condition that b>1. Intriguingly, the entropic uncertainty can shrink to zero when the coupling coefficients are relatively large, while the entropic uncertainty only reduces to 1 with the increase of the homogeneous magnetic field. Additionally, we observe the purity of the state and Bell non-locality and obtain that the entropic uncertainty is anticorrelated with both the purity and Bell non-locality of the evolution state.

Purification and characterization of a rice class I chitinase, OsChia1b, produced in Esherichia coli.

PubMed

Mizuno, Ryoji; Itoh, Yoshikane; Nishizawa, Yoko; Kezuka, Yuichiro; Suzuki, Kazushi; Nonaka, Takamasa; Watanabe, Takeshi

2008-03-01

To determine the properties and structure of OsChia1b, a family 19 chitinase from Oryza sativa L. cv. Nipponbare (japonica ssp.), recombinant OsChia1b was produced in Esherichia coli cells and purified to homogeneity by chitin affinity column chromatography. OsChia1b was highly active against soluble chitinous substrate, but not against crystalline chitin, and clearly inhibited hyphal extension of Trichoderma reesei.

Multifractal spectra in homogeneous shear flow

NASA Technical Reports Server (NTRS)

Deane, A. E.; Keefe, L. R.

1988-01-01

Employing numerical simulations of 3-D homogeneous shear flow, the associated multifractal spectra of the energy dissipation, scalar dissipation and vorticity fields were calculated. The results for (128) cubed simulations of this flow, and those obtained in recent experiments that analyzed 1- and 2-D intersections of atmospheric and laboratory flows, are in some agreement. A two-scale Cantor set model of the energy cascade process which describes the experimental results from 1-D intersections quite well, describes the 3-D results only marginally.

Multicomponent homogeneous alloys and method for making same

DOEpatents

Dutta, Partha S.; Miller, Thomas R.

2003-09-02

The present application discloses a method for preparing a homogeneous ternary or quaternary alloy from a quaternary melt. The method includes providing a family of phase diagrams for the quaternary melt which shows (i) composition/temperature data, (ii) tie lines connecting equilibrium liquid and solid compositions, and (iii) isotherms representing boundaries of a miscibility gap. Based on the family of phase diagrams, a quaternary melt composition and an alloy growth temperature is selected. A quaternary melt having the selected quaternary melt composition is provided and a ternary or quaternary alloy is grown from the quaternary melt at the selected alloy growth temperature. A method for making homogeneous ternary or quaternary alloy from a ternary or quaternary melt is also disclosed, as are homogeneous quaternary single-crystal alloys which are substantially free from crystal defects and which have the formula A.sub.x B.sub.1-x C.sub.y D.sub.1-y, x and y being the same or different and in the range of 0.001 to 0.999.

Whole-body continuously moving table fat-water MRI with dynamic B0 shimming at 3 Tesla.

PubMed

Sengupta, Saikat; Smith, David S; Gifford, Aliya; Welch, E Brian

2016-07-01

The purpose of this work was to develop a rapid and robust whole-body fat-water MRI (FWMRI) method using a continuously moving table (CMT) with dynamic field corrections at 3 Tesla. CMT FWMRI was developed at 3 Tesla with a multiecho golden angle (GA) radial trajectory and dynamic B0 field shimming. Whole-body imaging was performed with 4 echoes and superior-inferior coverage of 1.8 meters without shims in 90 s. 716 axial images were reconstructed with GA profile binning followed by B0 field map generation using fast three-point seeded region growing fat-water separation and slice-specific 0(th) and 1(st) order shim calculation. Slice-specific shims were applied dynamically in a repeated CMT FWMRI scan in the same session. The resulting images were evaluated for field homogeneity improvements and quality of fat-water separation with a whole-image energy optimized algorithm. GA sampling allowed high quality whole-body FWMRI from multiecho CMT data. Dynamic B0 shimming greatly improved field homogeneity in the body and produced high quality water and fat only images as well as fat signal fraction and R2 * relaxivity maps. A rapid and robust technique for whole-body fat-water quantification has been developed with CMT MRI with dynamic B0 field correction. Magn Reson Med 76:183-190, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Homogeneous photometry and star counts in the field of 9 Galactic star clusters

NASA Astrophysics Data System (ADS)

Seleznev, A. F.; Carraro, G.; Costa, E.; Loktin, A. V.

2010-01-01

We present homogeneous V, I CCD photometry of nine stellar fields in the two inner quadrants of the Galactic plane. The lines-of-view to most of these fields aim in the direction of the very inner Galaxy, where the Galactic field is very dense, and extinction is high and patchy. Our nine fields are, according to several catalogs, centred on Galactic star clusters, namely Trumpler 13, Trumpler 20, Lynga 4, Hogg 19, Lynga 12, Trumpler 25, Trumpler 26, Ruprecht 128, and Trumpler 34. Apart from their coordinates, and in some cases additional basic data (mainly from the 2MASS archive), their properties are poorly known. By means of star count techniques and field star decontaminated Color Magnitude diagrams, the nature and size of these visual over-densities has been established; and, when possible, new cluster fundamental parameters have been derived. To strengthen our findings, we complement our data-set with JHKs photometry from the 2MASS archive, that we analyze using a suitably defined Q-parameter. Most clusters are projected towards the Carina-Sagittarium spiral arm. Because of that, we detect in the Color Magnitude diagrams of most of the other fields several distinctive sequences produced by young population within the arm. All the clusters are of intermediate or old age. The most interesting cases detected by our study are, perhaps, that of Trumpler 20, which seems to be much older than previously believed, as indicated by its prominent - and double - red clump; and that of Hogg 19, a previously overlooked old open cluster, whose existence in such regions of the Milky Way is puzzling.

Homogeneous buoyancy-generated turbulence

NASA Technical Reports Server (NTRS)

Batchelor, G. K.; Canuto, V. M.; Chasnov, J. R.

1992-01-01

Using a theoretical analysis of fundamental equations and a numerical simulation of the flow field, the statistically homogeneous motion that is generated by buoyancy forces after the creation of homogeneous random fluctuations in the density of infinite fluid at an initial instant is examined. It is shown that analytical results together with numerical results provide a comprehensive description of the 'birth, life, and death' of buoyancy-generated turbulence. Results of numerical simulations yielded the mean-square density mean-square velocity fluctuations and the associated spectra as functions of time for various initial conditions, and the time required for the mean-square density fluctuation to fall to a specified small value was estimated.

Fracture of Rolled Homogeneous Steel Armor (Nucleation Threshold Stress).

DTIC Science & Technology

1980-01-01

AD-AO81 618 ARMY ARMAMENT RESEARCH AND DEVELOPMENT COMMAND ABERD--ETC F/B 19/4 FRACTURE OF ROLLED HOMOGENEOUS STEEL ARMOR (NUCLEATION THRESHOL--ETC(U...ARBRL-MR-02984A QQ FRACTURE OF ROLLED HOMOGENEOUS STEEL ARMOR (NUCLEATION THRESHOLD STRESS) Gerald L Moss Lynn SeamanLy~ S, ,.DTIC S ELECTED January...nucleation stress, Crack threshold stress, Fracture, Fracture stress, Spallation, Armor, Rolled homogeneous steel armor M~ AS$TRACr (Vita ssf -- ebb

Comparison of chromospheric and photospheric magnetic fields in two solar flares of X1.1/4N and X17.2/4B importance

NASA Astrophysics Data System (ADS)

Lozitsky, V.; Lozitska, N.

2017-12-01

We compare the specral-polarized obsevations of magnetic fields in two powerful solar flares of October 28, 2003 (of X17.2 / 4B class) and July 17, 2004 (of X1.1 / 2N class) using FeI and D1 NaI lines. We found that in both flares the effective magnetic field Beff was stronger in the chromosphere than in the photosphere. The strongest magnetic field (4600 Gs) was measured at the chromospheric level of a weaker flare, and this field was 1.6 times stronger than the magnetic field in the nearest sunspot. Comparing the obtained results with similar data by Lozitska et al [8] for flares of 1981 and 1989 (i.e., for cycles Nos. 21 and 22), we can see a significant difference. In both flares of 2003 and 2004, which relate to 23rd cycle of solar activity, we have Beff (FeI) < Beff(D1) for splitting of emission peaks, whereas for flares of cycles Nos. 21 and 22, the inverse in equality Beff (FeI)>Beff(D1) istrue. This result is still unclear and requires additional scrutiny on a base of new observational data.

A non-asymptotic homogenization theory for periodic electromagnetic structures.

PubMed

Tsukerman, Igor; Markel, Vadim A

2014-08-08

Homogenization of electromagnetic periodic composites is treated as a two-scale problem and solved by approximating the fields on both scales with eigenmodes that satisfy Maxwell's equations and boundary conditions as accurately as possible. Built into this homogenization methodology is an error indicator whose value characterizes the accuracy of homogenization. The proposed theory allows one to define not only bulk, but also position-dependent material parameters (e.g. in proximity to a physical boundary) and to quantify the trade-off between the accuracy of homogenization and its range of applicability to various illumination conditions.

Shear viscosity of the quark-gluon plasma in a weak magnetic field in perturbative QCD: Leading log

NASA Astrophysics Data System (ADS)

Li, Shiyong; Yee, Ho-Ung

2018-03-01

We compute the shear viscosity of two-flavor QCD plasma in an external magnetic field in perturbative QCD at leading log order, assuming that the magnetic field is weak or soft: e B ˜g4log (1 /g )T2. We work in the assumption that the magnetic field is homogeneous and static, and the electrodynamics is nondynamical in a formal limit e →0 while e B is kept fixed. We show that the shear viscosity takes a form η =η ¯(B ¯)T3/(g4log (1 /g )) with a dimensionless function η ¯(B ¯) in terms of a dimensionless variable B ¯=(e B )/(g4log (1 /g )T2). The variable B ¯ corresponds to the relative strength of the effect of cyclotron motions compared to the QCD collisions: B ¯˜lmfp/lcyclo. We provide a full numerical result for the scaled shear viscosity η ¯(B ¯).

ESA Swarm Mission - Level 1b Products

NASA Astrophysics Data System (ADS)

Tøffner-Clausen, Lars; Floberghagen, Rune; Mecozzi, Riccardo; Menard, Yvon

2014-05-01

Swarm, a three-satellite constellation to study the dynamics of the Earth's magnetic field and its interactions with the Earth system, has been launched in November 2013. The objective of the Swarm mission is to provide the best ever survey of the geomagnetic field and its temporal evolution, which will bring new insights into the Earth system by improving our understanding of the Earth's interior and environment. The Level 1b Products of the Swarm mission contain time-series of the quality screened, calibrated, corrected, and fully geo-localized measurements of the magnetic field intensity, the magnetic field vector (provided in both instrument and Earth-fixed frames), the plasma density, temperature, and velocity. Additionally, quality screened and pre-calibrated measurements of the nongravitational accelerations are provided. Geo-localization is performed by 24- channel GPS receivers and by means of unique, three head Advanced Stellar Compasses for high-precision satellite attitude information. The Swarm Level 1b data will be provided in daily products separately for each of the three Swarm spacecrafts. This poster will present detailed lists of the contents of the Swarm Level 1b Products and brief descriptions of the processing algorithms used in the generation of these data.

Homogeneity of gels and gel-derived glasses

NASA Technical Reports Server (NTRS)

Mukherjee, S. P.

1984-01-01

The significance and implications of gel preparation procedures in controlling the homogeneity of multicomponent oxide gels are discussed. The role of physicochemical factors such as the structure and chemical reactivities of alkoxides, the formation of double-metal alkoxides, and the nature of solvent(s) are critically analyzed in the context of homogeneity of gels during gelation. Three procedures for preparing gels in the SiO2-B2O3-Na2O system are examined in the context of cation distribution. Light scattering results for glasses in the SiO2-B2O3-Na2O system prepared by both the gel technique and the conventional technique are examined.

A non-asymptotic homogenization theory for periodic electromagnetic structures

PubMed Central

Tsukerman, Igor; Markel, Vadim A.

2014-01-01

Homogenization of electromagnetic periodic composites is treated as a two-scale problem and solved by approximating the fields on both scales with eigenmodes that satisfy Maxwell's equations and boundary conditions as accurately as possible. Built into this homogenization methodology is an error indicator whose value characterizes the accuracy of homogenization. The proposed theory allows one to define not only bulk, but also position-dependent material parameters (e.g. in proximity to a physical boundary) and to quantify the trade-off between the accuracy of homogenization and its range of applicability to various illumination conditions. PMID:25104912

Homogenous BSCCO-2212 Round Wires for Very High Field Magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dr. Scott Campbell

2012-06-30

materials have the very significant advantage of an extremely high H{sub c2}. For this reason, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212, or 2212) in the form of a multifilamentary Ag alloy matrix composite is beginning to attract the interest of the magnet community for future extremely high-field magnets or magnet-insert coils for 4.2K operation. Fig. 1 shows an example of excellent JE (engineering current density) in Bi-2212 round wire at fields up to 45 T, demonstrating the potential for high field applications of this material. For comparison, the Nb{sub 3}Sn wires used in magnets in the 16-18 T range typically perform with J{sub E} in the range 200-500 A/mm{sup 2}; the Bi-2212 wire retains this level of performance to fields at least as high as 45 T, and probably significantly higher. Bi-2212 conductors have in fact been used to generate a 25 T field in a superconducting insert magnet. These two factors- the very high field critical current performance of Bi-2212, and the already demonstrated capability of this material for high field magnets up to 25 T, strongly suggest this material as a leading contender for the next generation high field superconducting (HFS) wire. This potential was recognized by the US Academy of Science's Committee on Opportunities in High Magnetic Field Science. Their report of the same name specifically calls out the high field potential for this material, and suggests that 30 T magnets appear feasible based on the performance of 2212. There are several requirements for HFS conductors. The most obvious is J{sub E} (B, T), the engineering current density at the field and temperature of operation. As shown in Fig. 1, Bi-2212 excels in this regard. Stability requirements for magnets dictate that the effective filament diameter should be less than 30 micrometers, something that Bi-2212 multifilamentary wire can uniquely satisfy among the HFS superconducting wire technologies. Additional requirements include mechanical properties that prevent

Homogenized description and retrieval method of nonlinear metasurfaces

NASA Astrophysics Data System (ADS)

Liu, Xiaojun; Larouche, Stéphane; Smith, David R.

2018-03-01

A patterned, plasmonic metasurface can strongly scatter incident light, functioning as an extremely low-profile lens, filter, reflector or other optical device. When the metasurface is patterned uniformly, its linear optical properties can be expressed using effective surface electric and magnetic polarizabilities obtained through a homogenization procedure. The homogenized description of a nonlinear metasurface, however, presents challenges both because of the inherent anisotropy of the medium as well as the much larger set of potential wave interactions available, making it challenging to assign effective nonlinear parameters to the otherwise inhomogeneous layer of metamaterial elements. Here we show that a homogenization procedure can be developed to describe nonlinear metasurfaces, which derive their nonlinear response from the enhanced local fields arising within the structured plasmonic elements. With the proposed homogenization procedure, we are able to assign effective nonlinear surface polarization densities to a nonlinear metasurface, and link these densities to the effective nonlinear surface susceptibilities and averaged macroscopic pumping fields across the metasurface. These effective nonlinear surface polarization densities are further linked to macroscopic nonlinear fields through the generalized sheet transition conditions (GSTCs). By inverting the GSTCs, the effective nonlinear surface susceptibilities of the metasurfaces can be solved for, leading to a generalized retrieval method for nonlinear metasurfaces. The application of the homogenization procedure and the GSTCs are demonstrated by retrieving the nonlinear susceptibilities of a SiO2 nonlinear slab. As an example, we investigate a nonlinear metasurface which presents nonlinear magnetoelectric coupling in near infrared regime. The method is expected to apply to any patterned metasurface whose thickness is much smaller than the wavelengths of operation, with inclusions of arbitrary geometry

Sewage sludge solubilization by high-pressure homogenization.

PubMed

Zhang, Yuxuan; Zhang, Panyue; Guo, Jianbin; Ma, Weifang; Fang, Wei; Ma, Boqiang; Xu, Xiangzhe

2013-01-01

The behavior of sludge solubilization using high-pressure homogenization (HPH) treatment was examined by investigating the sludge solid reduction and organics solubilization. The sludge volatile suspended solids (VSS) decreased from 10.58 to 6.67 g/L for the sludge sample with a total solids content (TS) of 1.49% after HPH treatment at a homogenization pressure of 80 MPa with four homogenization cycles; total suspended solids (TSS) correspondingly decreased from 14.26 to 9.91 g/L. About 86.15% of the TSS reduction was attributed to the VSS reduction. The increase of homogenization pressure from 20 to 80 MPa or homogenization cycle number from 1 to 4 was favorable to the sludge organics solubilization, and the protein and polysaccharide solubilization linearly increased with the soluble chemical oxygen demand (SCOD) solubilization. More proteins were solubilized than polysaccharides. The linear relationship between SCOD solubilization and VSS reduction had no significant change under different homogenization pressures, homogenization cycles and sludge solid contents. The SCOD of 1.65 g/L was solubilized for the VSS reduction of 1.00 g/L for the three experimental sludge samples with a TS of 1.00, 1.49 and 2.48% under all HPH operating conditions. The energy efficiency results showed that the HPH treatment at a homogenization pressure of 30 MPa with a single homogenization cycle for the sludge sample with a TS of 2.48% was the most energy efficient.

A Tabletop Persistent-Mode, Liquid-Helium-Free, 1.5-T/90-mm MgB2 "Finger" MRI Magnet for Osteoporosis Screening: Two Design Options.

PubMed

Park, Dongkeun; Bascuñán, Juan; Michael, Philip C; Iwasa, Yukikazu

2018-04-01

In this paper we present two design options for a tabletop liquid-helium-free, persistent-mode 1.5-T/90-mm MgB 2 "finger" MRI magnet for osteoporosis screening. Both designs, one with and the other without an iron yoke, satisfy the following criteria: 1) 1.5-T center field with a 90-mm room-temperature bore for a finger to be placed at the magnet center; 2) spatial field homogeneity of <5 ppm over a 20-mm diameter of spherical volume (DSV); 3) persistent-mode operation with temporal stability of <0.1 ppm/hr; 4) liquid-helium-free operation; 5) 5-gauss fringe field radius of <50 cm from the magnet center; and 6) small and light enough for placement on an exam table. Although the magnet is designed to operate nominally at 10 K, maintained by a cryocooler, it has a 5-K temperature margin to keep its 1.5-T persistent field up to 15 K. The magnet will be immersed in a volume of solid nitrogen (SN 2 ) that provides additional thermal mass when the cryocooler is switched off to provide a vibration-free measurement environment. The SN 2 enables the magnet to maintain its persistent field over a period of time sufficient for quiescent measurement, while still limiting the magnet operating temperature to ≤15 K. We discuss first pros and cons of each design, and then further studies of our proposed MgB 2 finger MRI magnet.

Highly soluble [1]benzothieno[3,2-b]benzothiophene (BTBT) derivatives for high-performance, solution-processed organic field-effect transistors.

PubMed

Ebata, Hideaki; Izawa, Takafumi; Miyazaki, Eigo; Takimiya, Kazuo; Ikeda, Masaaki; Kuwabara, Hirokazu; Yui, Tatsuto

2007-12-26

2,7-Dialkyl[1]benzothieno[3,2-b]benzothiophenes were tested as solution-processible molecular semiconductors. Thin films of the organic semiconductors deposited on Si/SiO2 substrates by spin coating have well-ordered structures as confirmed by XRD analysis. Evaluations of the devices under ambient conditions showed typical p-channel FET responses with the field-effect mobility higher than 1.0 cm2 V-1 s-1 and Ion/Ioff of approximately 10(7).

Homogenized moment tensor and the effect of near-field heterogeneities on nonisotropic radiation in nuclear explosion

NASA Astrophysics Data System (ADS)

Burgos, Gaël.; Capdeville, Yann; Guillot, Laurent

2016-06-01

We investigate the effect of small-scale heterogeneities close to a seismic explosive source, at intermediate periods (20-50 s), with an emphasis on the resulting nonisotropic far-field radiation. First, using a direct numerical approach, we show that small-scale elastic heterogeneities located in the near-field of an explosive source, generate unexpected phases (i.e., long period S waves). We then demonstrate that the nonperiodic homogenization theory applied to 2-D and 3-D elastic models, with various pattern of small-scale heterogeneities near the source, leads to accurate waveforms at a reduced computational cost compared to direct modeling. Further, it gives an interpretation of how nearby small-scale features interact with the source at low frequencies, through an explicit correction to the seismic moment tensor. In 2-D simulations, we find a deviatoric contribution to the moment tensor, as high as 21% for near-source heterogeneities showing a 25% contrast of elastic values (relative to a homogeneous background medium). In 3-D this nonisotropic contribution reaches 27%. Second, we analyze intermediate-periods regional seismic waveforms associated with some underground nuclear explosions conducted at the Nevada National Security Site and invert for the full moment tensor, in order to quantify the relative contribution of the isotropic and deviatoric components of the tensor. The average value of the deviatoric part is about 35%. We conclude that the interactions between an explosive source and small-scale local heterogeneities of moderate amplitude may lead to a deviatoric contribution to the seismic moment, close to what is observed using regional data from nuclear test explosions.

High-frequency homogenization for travelling waves in periodic media.

PubMed

Harutyunyan, Davit; Milton, Graeme W; Craster, Richard V

2016-07-01

We consider high-frequency homogenization in periodic media for travelling waves of several different equations: the wave equation for scalar-valued waves such as acoustics; the wave equation for vector-valued waves such as electromagnetism and elasticity; and a system that encompasses the Schrödinger equation. This homogenization applies when the wavelength is of the order of the size of the medium periodicity cell. The travelling wave is assumed to be the sum of two waves: a modulated Bloch carrier wave having crystal wavevector [Formula: see text] and frequency ω 1 plus a modulated Bloch carrier wave having crystal wavevector [Formula: see text] and frequency ω 2 . We derive effective equations for the modulating functions, and then prove that there is no coupling in the effective equations between the two different waves both in the scalar and the system cases. To be precise, we prove that there is no coupling unless ω 1 = ω 2 and [Formula: see text] where Λ =(λ 1 λ 2 …λ d ) is the periodicity cell of the medium and for any two vectors [Formula: see text] the product a ⊙ b is defined to be the vector ( a 1 b 1 , a 2 b 2 ,…, a d b d ). This last condition forces the carrier waves to be equivalent Bloch waves meaning that the coupling constants in the system of effective equations vanish. We use two-scale analysis and some new weak-convergence type lemmas. The analysis is not at the same level of rigour as that of Allaire and co-workers who use two-scale convergence theory to treat the problem, but has the advantage of simplicity which will allow it to be easily extended to the case where there is degeneracy of the Bloch eigenvalue.

Arc melting and homogenization of ZrC and ZrC + B alloys

NASA Technical Reports Server (NTRS)

Darolia, R.; Archbold, T. F.

1973-01-01

A description is given of the methods used to arc-melt and to homogenize near-stoichiometric ZrC and ZrC-boron alloys, giving attention to the oxygen contamination problem. The starting material for the carbide preparation was ZrC powder with an average particle size of 4.6 micron. Pellets weighing approximately 3 g each were prepared at room temperature from the powder by the use of an isostatic press operated at 50,000 psi. These pellets were individually melted in an arc furnace containing a static atmosphere of purified argon. A graphite resistance furnace was used for the homogenization process.

CRITICAL EVALUATION OF MAGNETIC FIELD DETECTIONS REPORTED FOR PULSATING B-TYPE STARS IN LIGHT OF ESPaDOnS, NARVAL, AND REANALYZED FORS1/2 OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shultz, M.; Wade, G. A.; Grunhut, J.

2012-05-01

Recent spectropolarimetric studies of seven slowly pulsating B (SPB) and {beta} Cep stars have suggested that photospheric magnetic fields are more common in B-type pulsators than in the general population of B stars, suggesting a significant connection between magnetic and pulsational phenomena. We present an analysis of new and previously published spectropolarimetric observations of these stars. New Stokes V observations obtained with the high-resolution ESPaDOnS and Narval instruments confirm the presence of a magnetic field in one of the stars ({epsilon} Lup), but find no evidence of magnetism in five others. A re-analysis of the published longitudinal field measurements obtainedmore » with the low-resolution FORS1/2 spectropolarimeters finds that the measurements of all stars show more scatter from zero than can be attributed to Gaussian noise, suggesting the presence of a signal and/or systematic underestimation of error bars. Re-reduction and re-measurement of the FORS1/2 spectra from the ESO archive demonstrates that small changes in reduction procedure lead to substantial changes in the inferred longitudinal field, and substantially reduces the number of field detections at the 3{sigma} level. Furthermore, we find that the published periods are not unique solutions to the time series of either the original or the revised FORS1/2 data. We conclude that the reported field detections, proposed periods, and field geometry models for {alpha} Pyx, 15 CMa, 33 Eri, and V1449 Aql are artifacts of the data analysis and reduction procedures, and that magnetic fields at the reported strength are no more common in SPB/{beta} Cep stars than in the general population of B stars.« less

Independent validation of Swarm Level 2 magnetic field products and `Quick Look' for Level 1b data

NASA Astrophysics Data System (ADS)

Beggan, Ciarán D.; Macmillan, Susan; Hamilton, Brian; Thomson, Alan W. P.

2013-11-01

Magnetic field models are produced on behalf of the European Space Agency (ESA) by an independent scientific consortium known as the Swarm Satellite Constellation Application and Research Facility (SCARF), through the Level 2 Processor (L2PS). The consortium primarily produces magnetic field models for the core, lithosphere, ionosphere and magnetosphere. Typically, for each magnetic product, two magnetic field models are produced in separate chains using complementary data selection and processing techniques. Hence, the magnetic field models from the complementary processing chains will be similar but not identical. The final step in the overall L2PS therefore involves inspection and validation of the magnetic field models against each other and against data from (semi-) independent sources (e.g. ground observatories). We describe the validation steps for each magnetic field product and the comparison against independent datasets, and we show examples of the output of the validation. In addition, the L2PS also produces a daily set of `Quick Look' output graphics and statistics to monitor the overall quality of Level 1b data issued by ESA. We describe the outputs of the `Quick Look' chain.

Drag reduction in homogeneous turbulence by scale-dependent effective viscosity.

PubMed

Benzi, Roberto; Ching, Emily S C; Procaccia, Itamar

2004-08-01

We demonstrate, by using suitable shell models, that drag reduction in homogeneous turbulence is usefully discussed in terms of a scale-dependent effective viscosity. The essence of the phenomenon of drag reduction found in models that couple the velocity field to the polymers can be recaptured by an "equivalent" equation of motion for the velocity field alone, with a judiciously chosen scale-dependent effective viscosity that succinctly summarizes the important aspects of the interaction between the velocity and the polymer fields. Finally, we clarify the differences between drag reduction in homogeneous and in wall bounded flows.

On the chemical homogeneity of In xGa 1–xN alloys – Electron microscopy at the edge of technical limits

DOE PAGES

Specht, Petra; Kisielowski, Christian

2016-08-30

Ternary In xGa 1–xN alloys became technologically attractive when p-doping was achieved to produce blue and green light emitting diodes (LED)s. Starting in the mid 1990th, investigations of their chemical homogeneity were driven by the need to understand carrier recombination mechanisms in optical device structures to optimize their performance. Transmission electron microscopy (TEM) is the technique of choice to complement optical data evaluations, which suggests the coexistence of local carrier recombination mechanisms based on piezoelectric field effects and on indium clustering in the quantum wells of LEDs. We summarize the historic context of homogeneity investigations using electron microscopy techniques thatmore » can principally resolve the question of indium segregation and clustering in In xGa 1–xN alloys if optimal sample preparation and electron dose-controlled imaging techniques are employed together with advanced data evaluation.« less

A Tabletop Persistent-Mode, Liquid-Helium-Free, 1.5-T/90-mm MgB2 “Finger” MRI Magnet for Osteoporosis Screening: Two Design Options

PubMed Central

Park, Dongkeun; Bascuñán, Juan; Michael, Philip C.; Iwasa, Yukikazu

2017-01-01

In this paper we present two design options for a tabletop liquid-helium-free, persistent-mode 1.5-T/90-mm MgB2 “finger” MRI magnet for osteoporosis screening. Both designs, one with and the other without an iron yoke, satisfy the following criteria: 1) 1.5-T center field with a 90-mm room-temperature bore for a finger to be placed at the magnet center; 2) spatial field homogeneity of <5 ppm over a 20-mm diameter of spherical volume (DSV); 3) persistent-mode operation with temporal stability of <0.1 ppm/hr; 4) liquid-helium-free operation; 5) 5-gauss fringe field radius of <50 cm from the magnet center; and 6) small and light enough for placement on an exam table. Although the magnet is designed to operate nominally at 10 K, maintained by a cryocooler, it has a 5-K temperature margin to keep its 1.5-T persistent field up to 15 K. The magnet will be immersed in a volume of solid nitrogen (SN2) that provides additional thermal mass when the cryocooler is switched off to provide a vibration-free measurement environment. The SN2 enables the magnet to maintain its persistent field over a period of time sufficient for quiescent measurement, while still limiting the magnet operating temperature to ≤15 K. We discuss first pros and cons of each design, and then further studies of our proposed MgB2 finger MRI magnet. PMID:29456437

Ultra-high field MRI for primate imaging using the travelling-wave concept.

PubMed

Mallow, Johannes; Herrmann, Tim; Kim, Kyoung-Nam; Stadler, Joerg; Mylius, Judith; Brosch, Michael; Bernarding, Johannes

2013-08-01

Ultra-high field (UHF) neuroimaging is usually conducted with volume transmit (Tx) and phased array receive (Rx) coils, both tightly enclosing the object. The travelling-wave (TW) concept allows a remote excitation offering more flexible experimental setups. To investigate the feasibility of primate MRI in horizontal UHF MRI, we first compared the distribution of the electromagnetic fields in an oil phantom and then verified the concept with an in vivo experiment. In the phantom experiments an in-house circularly polarized hybrid birdcage coil and a self-developed patch antenna were used for Tx and an eight-element phased array antenna for Rx. B1+ fields were calculated and measured for both approaches. For in vivo experiments the Rx part was replaced with an optimized three-element phased array head coil. The SAR was calculated using field simulation. In the phantom the field distribution was homogenous in a central volume of interest of about 10 cm diameter. The TW concept showed a slightly better homogeneity. Examination of a female crab-eating macaque led to homogeneous high-contrast images with a good delineation of anatomical details. The TW concept opens up a new approach for MRI of medium-sized animals in horizontal UHF scanners.

Breadth of neutralizing antibodies elicited by stable, homogeneous clade A and clade C HIV-1 gp140 envelope trimers in guinea pigs.

PubMed

Nkolola, Joseph P; Peng, Hanqin; Settembre, Ethan C; Freeman, Michael; Grandpre, Lauren E; Devoy, Colleen; Lynch, Diana M; La Porte, Annalena; Simmons, Nathaniel L; Bradley, Ritu; Montefiori, David C; Seaman, Michael S; Chen, Bing; Barouch, Dan H

2010-04-01

The native envelope (Env) spike on the surface of human immunodeficiency virus type 1 (HIV-1) is trimeric, and thus trimeric Env vaccine immunogens are currently being explored in preclinical immunogenicity studies. Key challenges have included the production and purification of biochemically homogeneous and stable trimers and the evaluation of these immunogens utilizing standardized virus panels for neutralization assays. Here we report the binding and neutralizing antibody (NAb) responses elicited by clade A (92UG037.8) and clade C (CZA97.012) Env gp140 trimer immunogens in guinea pigs. These trimers have been selected and engineered for optimal biochemical stability and have defined antigenic properties. Purified gp140 trimers with Ribi adjuvant elicited potent, cross-clade NAb responses against tier 1 viruses as well as detectable but low-titer NAb responses against select tier 2 viruses from clades A, B, and C. In particular, the clade C trimer elicited NAbs that neutralized 27%, 20%, and 47% of tier 2 viruses from clades A, B, and C, respectively. Heterologous DNA prime, protein boost as well as DNA prime, recombinant adenovirus boost regimens expressing these antigens, however, did not result in an increased magnitude or breadth of NAb responses in this system. These data demonstrate the immunogenicity of stable, homogeneous clade A and clade C gp140 trimers and exemplify the utility of standardized tier 1 and tier 2 virus panels for assessing the NAb responses of candidate HIV-1 Env immunogens.

R1 dispersion contrast at high field with fast field-cycling MRI

NASA Astrophysics Data System (ADS)

Bödenler, Markus; Basini, Martina; Casula, Maria Francesca; Umut, Evrim; Gösweiner, Christian; Petrovic, Andreas; Kruk, Danuta; Scharfetter, Hermann

2018-05-01

Contrast agents with a strong R1 dispersion have been shown to be effective in generating target-specific contrast in MRI. The utilization of this R1 field dependence requires the adaptation of an MRI scanner for fast field-cycling (FFC). Here, we present the first implementation and validation of FFC-MRI at a clinical field strength of 3 T. A field-cycling range of ±100 mT around the nominal B0 field was realized by inserting an additional insert coil into an otherwise conventional MRI system. System validation was successfully performed with selected iron oxide magnetic nanoparticles and comparison to FFC-NMR relaxometry measurements. Furthermore, we show proof-of-principle R1 dispersion imaging and demonstrate the capability of generating R1 dispersion contrast at high field with suppressed background signal. With the presented ready-to-use hardware setup it is possible to investigate MRI contrast agents with a strong R1 dispersion at a field strength of 3 T.

Homogeneity Pursuit

PubMed Central

Ke, Tracy; Fan, Jianqing; Wu, Yichao

2014-01-01

This paper explores the homogeneity of coefficients in high-dimensional regression, which extends the sparsity concept and is more general and suitable for many applications. Homogeneity arises when regression coefficients corresponding to neighboring geographical regions or a similar cluster of covariates are expected to be approximately the same. Sparsity corresponds to a special case of homogeneity with a large cluster of known atom zero. In this article, we propose a new method called clustering algorithm in regression via data-driven segmentation (CARDS) to explore homogeneity. New mathematics are provided on the gain that can be achieved by exploring homogeneity. Statistical properties of two versions of CARDS are analyzed. In particular, the asymptotic normality of our proposed CARDS estimator is established, which reveals better estimation accuracy for homogeneous parameters than that without homogeneity exploration. When our methods are combined with sparsity exploration, further efficiency can be achieved beyond the exploration of sparsity alone. This provides additional insights into the power of exploring low-dimensional structures in high-dimensional regression: homogeneity and sparsity. Our results also shed lights on the properties of the fussed Lasso. The newly developed method is further illustrated by simulation studies and applications to real data. Supplementary materials for this article are available online. PMID:26085701

Quantum memory with a controlled homogeneous splitting

NASA Astrophysics Data System (ADS)

Hétet, G.; Wilkowski, D.; Chanelière, T.

2013-04-01

We propose a quantum memory protocol where an input light field can be stored onto and released from a single ground state atomic ensemble by controlling dynamically the strength of an external static and homogeneous field. The technique relies on the adiabatic following of a polaritonic excitation onto a state for which the forward collective radiative emission is forbidden. The resemblance with the archetypal electromagnetically induced transparency is only formal because no ground state coherence-based slow-light propagation is considered here. As compared to the other grand category of protocols derived from the photon-echo technique, our approach only involves a homogeneous static field. We discuss two physical situations where the effect can be observed, and show that in the limit where the excited state lifetime is longer than the storage time; the protocols are perfectly efficient and noise free. We compare the technique with other quantum memories, and propose atomic systems where the experiment can be realized.

Homogeneity of the geochemical reference material BRP-1 (paraná basin basalt) and assessment of minimum mass

USGS Publications Warehouse

Cotta, Aloisio J. B.; Enzweiler, Jacinta; Wilson, Stephen A.; Perez, Carlos A.; Nardy, Antonio J. R.; Larizzatti, Joao H.

2007-01-01

Reference materials (RM) are required for quantitative analyses and their successful use is associated with the degree of homogeneity, and the traceability and confidence limits of the values established by characterisation. During the production of a RM, the chemical characterisation can only commence after it has been demonstrated that the material has the required level of homogeneity. Here we describe the preparation of BRP-1, a proposed geochemical reference material, and the results of the tests to evaluate its degree of homogeneity between and within bottles. BRP-1 is the first of two geochemical RM being produced by Brazilian institutions in collaboration with the United States Geological Survey (USGS) and the International Association of Geoanalysts (IAG). Two test portions of twenty bottles of BRP-1 were analysed by wavelength dispersive-XRF spectrometry and major, minor and eighteen trace elements were determined. The results show that for most of the investigated elements, the units of BRP-1 were homogeneous at conditions approximately three times more rigorous than those strived for by the test of “sufficient homogeneity”. Furthermore, the within bottle homogeneity of BRP-1 was evaluated using small beam (1 mm2) synchrotron radiation XRF spectrometry and, for comparison, the USGS reference materials BCR-2 and GSP-2 were also evaluated. From our data, it has been possible to assign representative minimum masses for some major constituents (1 mg) and for some trace elements (1-13 mg), except Zr in GSP-2, for which test portions of 74 mg are recommended.

Interaction of proflavin with aromatic amines in homogeneous and micellar media: Photoinduced electron transfer probed by magnetic field effect

NASA Astrophysics Data System (ADS)

Chakraborty, Brotati; Basu, Samita

2010-02-01

Photoinduced electron transfer (PET) between proflavin (PF +) and two aromatic amines viz., dimethylaniline (DMA) and 4,4'-bis(dimethylamino)diphenylmethane (DMDPM) is studied in homogeneous and heterogeneous media using steady-state as well as time-resolved fluorescence spectroscopy and laser flash photolysis with an associated magnetic field. Ionic micelles have been used to study the effect of charge of proflavin on PET with amines. Magnetic field effect on PET reactions reveals that the parent spin-state of precursors of PET for DMA-PF + system is singlet while for DMDPM-PF + system is triplet, implying that the dynamics of PET is influenced by the structure of the donor.

A homogeneous cell-based assay for measurement of endogenous paraoxonase 1 activity.

PubMed

Ahmad, Syed; Carter, Jade J; Scott, John E

2010-05-01

Paraoxonase 1 (PON1) is a high-density lipoprotein-associated enzyme that plays an important role in organophosphate detoxification and prevention of atherosclerosis. Thus, there is significant interest in identifying nutritional and pharmacological enhancers of PON1 activity. To identify such compounds, we developed a rapid homogeneous assay to detect endogenous cell-associated PON1 activity. PON1 activity was measured by the simple addition of fluorigenic PON1 substrate DEPFMU to live Huh7 cells in medium and monitoring change in fluorescence. A specific PON1 inhibitor, 2-hydroxyquinoline, was used to confirm that the observed activity was due to PON1. The assay was optimized and characterized with regard to time course, substrate and sodium chloride concentration, number of cells, and tolerance to dimethyl sulfoxide and serum. Aspirin, quercetin, and simvastatin are compounds reported to increase PON1 expression. Consistent with the literature and Western blot data, these compounds enhanced PON1 activity in this assay with comparable efficacies and potencies. A known toxic compound did not increase assay signal. This assay method also detected PON1 activity in normal hepatocytes. Thus, a novel homogeneous assay for detection of endogenous PON1 expression has been developed and is amenable to high-throughput screening for the identification of small molecules that enhance PON1 expression. 2010 Elsevier Inc. All rights reserved.

Tidal dissipation in a homogeneous spherical body. II. Three examples: Mercury, Io, and Kepler-10 b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makarov, Valeri V.; Efroimsky, Michael, E-mail: vvm@usno.navy.mil, E-mail: michael.efroimsky@usno.navy.mil

In Efroimsky and Makarov (Paper I), we derived from the first principles a formula for the tidal heating rate in a homogeneous sphere, compared it with the previously used formulae, and noted the differences. Now we present case studies: Mercury, Kepler-10 b, and a triaxial Io. A sharp frequency dependence of k {sub 2}/Q near spin-orbit resonances yields a sharp dependence of k {sub 2}/Q (and, therefore, of tidal heating) upon the spin rate. Thereby physical libration plays a major role in tidal heating of synchronously rotating planets. The magnitude of libration in the spin rate being defined by themore » planet's triaxiality, the latter becomes a factor determining the dissipation rate. Other parameters equal, a strongly triaxial synchronized body generates more heat than a similar body of a more symmetrical shape. After an initially triaxial object melts and loses its triaxiality, dissipation becomes less intensive; the body can solidify, with the tidal bulge becoming a new figure with triaxiality lower than the original. We derive approximate expressions for the dissipation rate in a Maxwell planet with the Maxwell time longer than the inverse tidal frequency. The expressions derived pertain to the 1:1 and 3:2 resonances and a nonresonant case; so they are applicable to most close-in super-Earths detected. In these planets, the heating outside synchronism is weakly dependent on the eccentricity and obliquity, provided both these parameters's values are moderate. According to our calculation, Kepler-10 b could hardly survive the intensive tidal heating without being synchronized, circularized, and reshaped through a complete or partial melt-down.« less

Homogeneous crystal nucleation in polymers.

PubMed

Schick, C; Androsch, R; Schmelzer, J W P

2017-11-15

The pathway of crystal nucleation significantly influences the structure and properties of semi-crystalline polymers. Crystal nucleation is normally heterogeneous at low supercooling, and homogeneous at high supercooling, of the polymer melt. Homogeneous nucleation in bulk polymers has been, so far, hardly accessible experimentally, and was even doubted to occur at all. This topical review summarizes experimental findings on homogeneous crystal nucleation in polymers. Recently developed fast scanning calorimetry, with cooling and heating rates up to 10 6 K s -1 , allows for detailed investigations of nucleation near and even below the glass transition temperature, including analysis of nuclei stability. As for other materials, the maximum homogeneous nucleation rate for polymers is located close to the glass transition temperature. In the experiments discussed here, it is shown that polymer nucleation is homogeneous at such temperatures. Homogeneous nucleation in polymers is discussed in the framework of the classical nucleation theory. The majority of our observations are consistent with the theory. The discrepancies may guide further research, particularly experiments to progress theoretical development. Progress in the understanding of homogeneous nucleation is much needed, since most of the modelling approaches dealing with polymer crystallization exclusively consider homogeneous nucleation. This is also the basis for advancing theoretical approaches to the much more complex phenomena governing heterogeneous nucleation.

Phoretic drag reduction of chemically active homogeneous spheres under force fields and shear flows

NASA Astrophysics Data System (ADS)

Yariv, Ehud; Kaynan, Uri

2017-01-01

Surrounded by a spherically symmetric solute cloud, chemically active homogeneous spheres do not undergo conventional autophoresis when suspended in an unbounded liquid domain. When exposed to external flows, solute advection deforms that cloud, resulting in a generally asymmetric distribution of diffusio-osmotic slip which, in turn, modifies particle motion. Inspired by classical forced-convection analyses [Acrivos and Taylor, Phys. Fluids 5, 387 (1962), 10.1063/1.1706630; Frankel and Acrivos, Phys. Fluids 11, 1913 (1968), 10.1063/1.1692218] we illustrate this phoretic phenomenon using two prototypic configurations, one where the particle sediments under a uniform force field and one where it is subject to a simple shear flow. In addition to the Péclet number Pe associated with the imposed flow, the governing nonlinear problem also depends upon α , the intrinsic Péclet number associated with the chemical activity of the particle. As in the forced-convection problems, the small-Péclet-number limit is nonuniform, breaking down at large distances away from the particle. Calculation of the leading-order autophoretic effects thus requires use of matched asymptotic expansions, the outer region being at distances that scale inversely with Pe and Pe1 /2 in the respective sedimentation and shear problems. In the sedimentation problem we find an effective drag reduction of fractional amount α /8 ; in the shear problem we find that the magnitude of the stresslet is decreased by a fractional amount α /4 . For a dilute particle suspension the latter result is manifested by a reduction of the effective viscosity.

Genetic progress in homogeneous regions of wheat cultivation in Rio Grande do Sul State, Brazil.

PubMed

Follmann, D N; Cargnelutti Filho, A; Lúcio, A D; de Souza, V Q; Caraffa, M; Wartha, C A

2017-03-30

The State of Rio Grande do Sul (RS) stands out as the largest wheat producer in Brazil. Wheat is the most emphasized winter cereal in RS, attracting public and private investments directed to wheat genetic breeding. The study of genetic progress should be performed routinely at breeding programs to study the behavior of cultivars developed for homogeneous regions of cultivation. The objectives of this study were: 1) to evaluate the genetic progress of wheat grain yield in RS; 2) to evaluate the influence of cultivar competition trial stratification in homogeneous regions of cultivation on the study of genetic progress. Grain yield data of 122 wheat cultivars evaluated in 137 trials arranged in randomized block design with three or four replications were used. Field trials were carried out in 23 locations in RS divided into two homogeneous regions during the period from 2002 to 2013. Genetic progress for RS and homogeneous regions was studied utilizing the method proposed by Vencovsky. Annual genetic progress for wheat grain yield during the period of 12 years in the State of RS was 2.86%, oscillating between homogeneous regions of cultivation. The difference of annual genetic progress in region 1 (1.82%) in relation to region 2 (4.38%) justifies the study of genetic progress by homogeneous regions of cultivation.

Study of grain boundary transparency in (Y b1 -xC ax) B a2C u3O bicrystal thin films over a wide temperature, field, and field orientation range

NASA Astrophysics Data System (ADS)

Li, Pei; Abraimov, Dmytro; Polyanskii, Anatolii; Kametani, Fumitake; Larbalestier, David

2015-03-01

The residual low-angle grain boundary (GB) network is still the most important current-limiting mechanism operating in biaxially textured rare-earth barium-copper-oxide (REBCO) coated conductors. While Ca doping is well established to improve supercurrent flow across low-angle GBs in weak fields at high temperatures, Ca doping also depresses Tc, making it so far impractical for high-temperature applications of REBCO coated conductors. On the other hand, high-field-magnet applications of REBCO require low temperatures. Here we systematically evaluate the effectiveness of Ca doping in improving the GB transparency, rGB=JcGB/ Jcgrain , of low-angle Y b1 -xC axBaCuO [001] tilt bicrystal films down to 10 K and with magnetic fields perpendicular and parallel to the film surfaces, while varying the Ca and oxygen doping level. Using low-temperature scanning laser microscopy and magneto-optical imaging, we found rGB to strongly depend on the angle between magnetic field and the GB plane and clearly identified regimes in which JcGB can exceed Jcgrain(rGB>1 ) where the GB pinning is optimized by the field being parallel to the GB dislocations. However, even in this favorable situation, we found that rGB became much smaller at lower temperatures. Calculations of the GB Ca segregation profile predict that the high-Jc channels between the GB dislocation cores are almost Ca free. It may be therefore that the positive effects of Ca doping seen by many authors near Tc are partly a consequence of the higher Tc of these Ca-free channels.

R1 dispersion contrast at high field with fast field-cycling MRI.

PubMed

Bödenler, Markus; Basini, Martina; Casula, Maria Francesca; Umut, Evrim; Gösweiner, Christian; Petrovic, Andreas; Kruk, Danuta; Scharfetter, Hermann

2018-05-01

Contrast agents with a strong R 1 dispersion have been shown to be effective in generating target-specific contrast in MRI. The utilization of this R 1 field dependence requires the adaptation of an MRI scanner for fast field-cycling (FFC). Here, we present the first implementation and validation of FFC-MRI at a clinical field strength of 3 T. A field-cycling range of ±100 mT around the nominal B 0 field was realized by inserting an additional insert coil into an otherwise conventional MRI system. System validation was successfully performed with selected iron oxide magnetic nanoparticles and comparison to FFC-NMR relaxometry measurements. Furthermore, we show proof-of-principle R 1 dispersion imaging and demonstrate the capability of generating R 1 dispersion contrast at high field with suppressed background signal. With the presented ready-to-use hardware setup it is possible to investigate MRI contrast agents with a strong R 1 dispersion at a field strength of 3 T. Copyright © 2018 Elsevier Inc. All rights reserved.

A charged particle in a homogeneous magnetic field accelerated by a time-periodic Aharonov-Bohm flux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalvoda, T.; Stovicek, P., E-mail: stovicek@kmlinux.fjfi.cvut.cz

2011-10-15

We consider a nonrelativistic quantum charged particle moving on a plane under the influence of a uniform magnetic field and driven by a periodically time-dependent Aharonov-Bohm flux. We observe an acceleration effect in the case when the Aharonov-Bohm flux depends on time as a sinusoidal function whose frequency is in resonance with the cyclotron frequency. In particular, the energy of the particle increases linearly for large times. An explicit formula for the acceleration rate is derived with the aid of the quantum averaging method, and then it is checked against a numerical solution and a very good agreement is found.more » - Highlights: > A nonrelativistic quantum charged particle on a plane. > A homogeneous magnetic field and a periodically time-dependent Aharonov-Bohm flux. > The quantum averaging method applied to a time-dependent system. > A resonance of the AB flux with the cyclotron frequency. > An acceleration with linearly increasing energy; a formula for the acceleration rate.« less

ANALYSIS OF FISH HOMOGENATES FOR PERFLUORINATED COMPOUNDS

EPA Science Inventory

Perfluorinated compounds (PFCs) which include PFOS and PFOA are widely distributed in wildlife. Whole fish homogenates were analyzed for PFCs from the upper Mississippi, the Missouri and the Ohio rivers. Methods development, validation data, and preliminary study results will b...

Homogenization in micro-magneto-mechanics

NASA Astrophysics Data System (ADS)

Sridhar, A.; Keip, M.-A.; Miehe, C.

2016-07-01

Ferromagnetic materials are characterized by a heterogeneous micro-structure that can be altered by external magnetic and mechanical stimuli. The understanding and the description of the micro-structure evolution is of particular importance for the design and the analysis of smart materials with magneto-mechanical coupling. The macroscopic response of the material results from complex magneto-mechanical interactions occurring on smaller length scales, which are driven by magnetization reorientation and associated magnetic domain wall motions. The aim of this work is to directly base the description of the macroscopic magneto-mechanical material behavior on the micro-magnetic domain evolution. This will be realized by the incorporation of a ferromagnetic phase-field formulation into a macroscopic Boltzmann continuum by the use of computational homogenization. The transition conditions between the two scales are obtained via rigorous exploitation of rate-type and incremental variational principles, which incorporate an extended version of the classical Hill-Mandel macro-homogeneity condition covering the phase field on the micro-scale. An efficient two-scale computational scenario is developed based on an operator splitting scheme that includes a predictor for the magnetization on the micro-scale. Two- and three-dimensional numerical simulations demonstrate the performance of the method. They investigate micro-magnetic domain evolution driven by macroscopic fields as well as the associated overall hysteretic response of ferromagnetic solids.

Sewage sludge disintegration by high-pressure homogenization: a sludge disintegration model.

PubMed

Zhang, Yuxuan; Zhang, Panyue; Ma, Boqiang; Wu, Hao; Zhang, Sheng; Xu, Xin

2012-01-01

High-pressure homogenization (HPH) technology was applied as a pretreatment to disintegrate sewage sludge. The effects of homogenization pressure, homogenization cycle number, and total solid content on sludge disintegration were investigated. The sludge disintegration degree (DD(COD)), protein concentration, and polysaccharide concentration increased with the increase of homogenization pressure and homogenization cycle number, and decreased with the increase of sludge total solid (TS) content. The maximum DD(COD) of 43.94% was achieved at 80 MPa with four homogenization cycles for a 9.58 g/L TS sludge sample. A HPH sludge disintegration model of DD(COD) = kNaPb was established by multivariable linear regression to quantify the effects of homogenization parameters. The homogenization cycle exponent a and homogenization pressure exponent b were 0.4763 and 0.7324 respectively, showing that the effect of homogenization pressure (P) was more significant than that of homogenization cycle number (N). The value of the rate constant k decreased with the increase of sludge total solid content. The specific energy consumption increased with the increment of sludge disintegration efficiency. Lower specific energy consumption was required for higher total solid content sludge.

Synthesis, properties, crystal structures, and semiconductor characteristics of naphtho[1,2-b:5,6-b']dithiophene and -diselenophene derivatives.

PubMed

Shinamura, Shoji; Miyazaki, Eigo; Takimiya, Kazuo

2010-02-19

In this paper we present the synthesis, structures, characterization, and applications to field-effect transistors (FETs) of naphtho[1,2-b:5,6-b']dithiophene (NDT) and -diselenophene (NDS) derivatives. Treatment of 1,5-dichloro-2,6-diethynylnaphthalenes, easily derived from commercially available 2,6-dihydroxynaphthalene, with sodium chalcogenide afforded a straightforward access to NDTs and NDSs including the parent and dioctyl and diphenyl derivatives. Physicochemical evaluations of NDT and NDS derivatives showed that these heteroarenes have a similar electronic structure with isomeric [1]benzothieno[2,3-b][1]benzothiophene (BTBT) and [1]benzoselenopheneno[2,3-b][1]benzoselenophene (BSBS) derivatives, respectively. Although attempts to fabricate solution-processed field-effect transistors (FETs) with soluble dioctyl-NDT (C(8)-NDT) and -NDS (C(8)-NDS) failed, diphenyl derivatives (DPh-NDT and DPh-NDS) afforded vapor-processed FETs showing field-effect mobility as high as 0.7 cm(2) V(-1) s(-1). These results indicated that NDT and NDS are new potential heteroarene core structures for organic semiconducting materials.

A micromechanical approach for homogenization of elastic metamaterials with dynamic microstructure.

PubMed

Muhlestein, Michael B; Haberman, Michael R

2016-08-01

An approximate homogenization technique is presented for generally anisotropic elastic metamaterials consisting of an elastic host material containing randomly distributed heterogeneities displaying frequency-dependent material properties. The dynamic response may arise from relaxation processes such as viscoelasticity or from dynamic microstructure. A Green's function approach is used to model elastic inhomogeneities embedded within a uniform elastic matrix as force sources that are excited by a time-varying, spatially uniform displacement field. Assuming dynamic subwavelength inhomogeneities only interact through their volume-averaged fields implies the macroscopic stress and momentum density fields are functions of both the microscopic strain and velocity fields, and may be related to the macroscopic strain and velocity fields through localization tensors. The macroscopic and microscopic fields are combined to yield a homogenization scheme that predicts the local effective stiffness, density and coupling tensors for an effective Willis-type constitutive equation. It is shown that when internal degrees of freedom of the inhomogeneities are present, Willis-type coupling becomes necessary on the macroscale. To demonstrate the utility of the homogenization technique, the effective properties of an isotropic elastic matrix material containing isotropic and anisotropic spherical inhomogeneities, isotropic spheroidal inhomogeneities and isotropic dynamic spherical inhomogeneities are presented and discussed.

A micromechanical approach for homogenization of elastic metamaterials with dynamic microstructure

PubMed Central

Haberman, Michael R.

2016-01-01

An approximate homogenization technique is presented for generally anisotropic elastic metamaterials consisting of an elastic host material containing randomly distributed heterogeneities displaying frequency-dependent material properties. The dynamic response may arise from relaxation processes such as viscoelasticity or from dynamic microstructure. A Green's function approach is used to model elastic inhomogeneities embedded within a uniform elastic matrix as force sources that are excited by a time-varying, spatially uniform displacement field. Assuming dynamic subwavelength inhomogeneities only interact through their volume-averaged fields implies the macroscopic stress and momentum density fields are functions of both the microscopic strain and velocity fields, and may be related to the macroscopic strain and velocity fields through localization tensors. The macroscopic and microscopic fields are combined to yield a homogenization scheme that predicts the local effective stiffness, density and coupling tensors for an effective Willis-type constitutive equation. It is shown that when internal degrees of freedom of the inhomogeneities are present, Willis-type coupling becomes necessary on the macroscale. To demonstrate the utility of the homogenization technique, the effective properties of an isotropic elastic matrix material containing isotropic and anisotropic spherical inhomogeneities, isotropic spheroidal inhomogeneities and isotropic dynamic spherical inhomogeneities are presented and discussed. PMID:27616932

A micromechanical approach for homogenization of elastic metamaterials with dynamic microstructure

NASA Astrophysics Data System (ADS)

Muhlestein, Michael B.; Haberman, Michael R.

2016-08-01

An approximate homogenization technique is presented for generally anisotropic elastic metamaterials consisting of an elastic host material containing randomly distributed heterogeneities displaying frequency-dependent material properties. The dynamic response may arise from relaxation processes such as viscoelasticity or from dynamic microstructure. A Green's function approach is used to model elastic inhomogeneities embedded within a uniform elastic matrix as force sources that are excited by a time-varying, spatially uniform displacement field. Assuming dynamic subwavelength inhomogeneities only interact through their volume-averaged fields implies the macroscopic stress and momentum density fields are functions of both the microscopic strain and velocity fields, and may be related to the macroscopic strain and velocity fields through localization tensors. The macroscopic and microscopic fields are combined to yield a homogenization scheme that predicts the local effective stiffness, density and coupling tensors for an effective Willis-type constitutive equation. It is shown that when internal degrees of freedom of the inhomogeneities are present, Willis-type coupling becomes necessary on the macroscale. To demonstrate the utility of the homogenization technique, the effective properties of an isotropic elastic matrix material containing isotropic and anisotropic spherical inhomogeneities, isotropic spheroidal inhomogeneities and isotropic dynamic spherical inhomogeneities are presented and discussed.

Homogeneous electrochemical immunoassay of aflatoxin B1 in foodstuff using proximity-hybridization-induced omega-like DNA junctions and exonuclease III-triggered isothermal cycling signal amplification.

PubMed

Tang, Juan; Huang, Yapei; Liu, Huiqiong; Zhang, Cengceng; Tang, Dianping

2016-12-01

A new homogeneous electrochemical immunosensing platform was designed for sensitive detection of aflatoxin B 1 (AFB 1 ) in foodstuff. The system consisted of anti-AFB 1 antibody labeled DNA 1 (Ab-DNA 1 ), AFB 1 -bovine serum albumin (BSA)-conjugated DNA 2 (AFB 1 -DNA 2 ), and methylene blue functionalized hairpin DNA. Owing to a specific antigen-antibody reaction between anti-AFB 1 and AFB 1 -BSA, the immunocomplex formed assisted the proximity hybridization of DNA 1 with DNA 2 , thus resulting in the formation of an omega-like DNA junction. Thereafter, the junction opened the hairpin DNA to construct a new double-stranded DNA, which could be readily cleaved by exonuclease III to release the omega-like DNA junction and methylene blue. The dissociated DNA junction could repeatedly hybridize with residual hairpin DNA molecules with exonuclease III-based isothermal cycling amplification, thereby releasing numerous free methylene blue molecules into the detection solution. The as-produced free methylene blue molecules could be captured by a negatively charged indium tin oxide electrode, each of which could produce an electronic signal within the applied potentials. On introduction of target AFB 1 , the analyte competed with AFB 1 -DNA 2 for the conjugated anti-AFB 1 on the Ab-DNA 1 , subsequently decreasing the amount of omega-like DNA junctions formed, hence causing methylene blue labeled hairpin DNA to move far away from the electrode surface. Under optimal conditions the detectable electrochemical signal decreased with increasing amount of target AFB 1 in a dynamic working range of 0.01-30 ng mL -1 with a detection limit of 4.8 pg mL -1 . In addition, the precision and reproducibility of this system were acceptable. Finally, the method was further evaluated for analysis of naturally contaminated or AFB 1 -spiked peanut samples, giving results that matched well with those obtained with a commercial AFB 1 ELISA kit.

Control over Janus micromotors by the strength of a magnetic field

NASA Astrophysics Data System (ADS)

Baraban, Larysa; Makarov, Denys; Schmidt, Oliver G.; Cuniberti, Gianaurelio; Leiderer, Paul; Erbe, Artur

2013-01-01

For transportation of molecules or biological cells using artificial motors, the control over their motion, i.e. direction and speed of transfer, is important. Here, we demonstrate that modification of the velocity and orientation of a magnetic Janus particle can be efficiently controlled by tuning the strength of an applied homogeneous magnetic field. Interestingly, by keeping the same orientation of the magnetic field but changing its magnitude not only the velocity of capped particles can be altered but even their direction of motion can be reversed. We put forth a simple qualitative model, which allows us to explain this intriguing observation.For transportation of molecules or biological cells using artificial motors, the control over their motion, i.e. direction and speed of transfer, is important. Here, we demonstrate that modification of the velocity and orientation of a magnetic Janus particle can be efficiently controlled by tuning the strength of an applied homogeneous magnetic field. Interestingly, by keeping the same orientation of the magnetic field but changing its magnitude not only the velocity of capped particles can be altered but even their direction of motion can be reversed. We put forth a simple qualitative model, which allows us to explain this intriguing observation. Electronic supplementary information (ESI) available: Videos (1-3) describe the behavior of the magnetic Janus micromotors at different magnetic fields applied. The magnetic field is always applied along the positive direction of the y-axis. All the movies are recorded at the same frame rate of 21 images per second. Experiments were performed at 30 wt% of hydrogen peroxide in aqueous solution. Video 1 shows the motion of the Janus micromotors when a small magnetic field is applied (B = 0.2 mT). The particle is propelled in the direction ``opposite to the cap'' with a velocity of about 6 μm s-1. Video 2 displays the motion of the same Janus bead when an intermediately strong

Inactivation of Bacillus spores inoculated in milk by Ultra High Pressure Homogenization.

PubMed

Amador Espejo, Genaro Gustavo; Hernández-Herrero, M M; Juan, B; Trujillo, A J

2014-12-01

Ultra High-Pressure Homogenization treatments at 300 MPa with inlet temperatures (Ti) of 55, 65, 75 and 85 °C were applied to commercial Ultra High Temperature treated whole milk inoculated with Bacillus cereus, Bacillus licheniformis, Bacillus sporothermodurans, Bacillus coagulans, Geobacillus stearothermophilus and Bacillus subtilis spores in order to evaluate the inactivation level achieved. Ultra High-Pressure Homogenization conditions at 300 MPa with Ti = 75 and 85 °C were capable of a spore inactivation of ∼5 log CFU/mL. Furthermore, under these processing conditions, commercial sterility (evaluated as the complete inactivation of the inoculated spores) was obtained in milk, with the exception of G. stearothermophilus and B. subtilis treated at 300 MPa with Ti = 75 °C. The results showed that G. stearothermophilus and B. subtilis have higher resistance to the Ultra High-Pressure Homogenization treatments applied than the other microorganisms inoculated and that a treatment performed at 300 MPa with Ti = 85 °C was necessary to completely inactivate these microorganisms at the spore level inoculated (∼1 × 10(6) CFU/mL). Besides, a change in the resistance of B. licheniformis, B. sporothermodurans, G. stearothermophilus and B. subtilis spores was observed as the inactivation obtained increased remarkably in treatments performed with Ti between 65 and 75 °C. This study provides important evidence of the suitability of UHPH technology for the inactivation of spores in high numbers, leading to the possibility of obtaining commercially sterile milk. Copyright © 2014 Elsevier Ltd. All rights reserved.

Magnon-induced superconductivity in field-cooled spin-1/2 antiferromagnets

NASA Astrophysics Data System (ADS)

Karchev, Naoum

2017-12-01

If, during the preparation, an external magnetic field is applied upon cooling we say it has been field cooled. A novel mechanism for insulator-metal transition and superconductivity in field-cooled spin-1 /2 antiferromagnets on bcc lattice is discussed. Applying a magnetic field along the sublattice B magnetization, we change the magnetic and transport properties of the material. There is a critical value Hcr1. When the magnetic field is below the critical one H 1 the prepared material is a spin-1 /2 antiferromagnetic insulator. When H >Hcr1 the sublattice A electrons are delocalized and the material is metal. There is a second critical value Hcr2>Hcr1 . When H =Hcr2 , it is shown that the Zeeman splitting of the sublattice A electrons is zero and they do not contribute to the magnetization of the system. At this quantum partial order point (QPOP) the sublattice B transversal spin fluctuations (magnons) interact with sublattice A electrons inducing spin antiparallel p -wave superconductivity which coexists with magnetism. At zero temperature the magnetic moment of sublattice B electrons is maximal. Below the Néel temperature (TN) the gap is approximately constant with a small increase when the system approaches TN. It abruptly falls down to zero at temperatures above TN.

Collective strong coupling with homogeneous Rabi frequencies using a 3D lumped element microwave resonator

NASA Astrophysics Data System (ADS)

Angerer, Andreas; Astner, Thomas; Wirtitsch, Daniel; Sumiya, Hitoshi; Onoda, Shinobu; Isoya, Junichi; Putz, Stefan; Majer, Johannes

2016-07-01

We design and implement 3D-lumped element microwave cavities that spatially focus magnetic fields to a small mode volume. They allow coherent and uniform coupling to electron spins hosted by nitrogen vacancy centers in diamond. We achieve large homogeneous single spin coupling rates, with an enhancement of more than one order of magnitude compared to standard 3D cavities with a fundamental resonance at 3 GHz. Finite element simulations confirm that the magnetic field distribution is homogeneous throughout the entire sample volume, with a root mean square deviation of 1.54%. With a sample containing 1017 nitrogen vacancy electron spins, we achieve a collective coupling strength of Ω = 12 MHz, a cooperativity factor C = 27, and clearly enter the strong coupling regime. This allows to interface a macroscopic spin ensemble with microwave circuits, and the homogeneous Rabi frequency paves the way to manipulate the full ensemble population in a coherent way.

Collective strong coupling with homogeneous Rabi frequencies using a 3D lumped element microwave resonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Angerer, Andreas, E-mail: andreas.angerer@tuwien.ac.at; Astner, Thomas; Wirtitsch, Daniel

We design and implement 3D-lumped element microwave cavities that spatially focus magnetic fields to a small mode volume. They allow coherent and uniform coupling to electron spins hosted by nitrogen vacancy centers in diamond. We achieve large homogeneous single spin coupling rates, with an enhancement of more than one order of magnitude compared to standard 3D cavities with a fundamental resonance at 3 GHz. Finite element simulations confirm that the magnetic field distribution is homogeneous throughout the entire sample volume, with a root mean square deviation of 1.54%. With a sample containing 10{sup 17} nitrogen vacancy electron spins, we achieve amore » collective coupling strength of Ω = 12 MHz, a cooperativity factor C = 27, and clearly enter the strong coupling regime. This allows to interface a macroscopic spin ensemble with microwave circuits, and the homogeneous Rabi frequency paves the way to manipulate the full ensemble population in a coherent way.« less

On the spatial distribution of small heavy particles in homogeneous shear turbulence

NASA Astrophysics Data System (ADS)

Nicolai, C.; Jacob, B.; Piva, R.

2013-08-01

We report on a novel experiment aimed at investigating the effects induced by a large-scale velocity gradient on the turbulent transport of small heavy particles. To this purpose, a homogeneous shear flow at Reλ = 540 and shear parameter S* = 4.5 is set-up and laden with glass spheres whose size d is comparable with the Kolmogorov lengthscale η of the flow (d/η ≈ 1). The particle Stokes number is approximately 0.3. The analysis of the instantaneous particle fields by means of Voronoï diagrams confirms the occurrence of intense turbulent clustering at small scales, as observed in homogeneous isotropic flows. It also indicates that the anisotropy of the velocity fluctuations induces a preferential orientation of the particle clusters. In order to characterize the fine-scale features of the dispersed phase, spatial correlations of the particle field are employed in conjunction with statistical tools recently developed for anisotropic turbulence. The scale-by-scale analysis of the particle field clarifies that isotropy of the particle distribution is tendentially recovered at small separations, even though the signatures of the mean shear persist down to smaller scales as compared to the fluid velocity field.

γ Pegasi: testing Vega-like magnetic fields in B stars

NASA Astrophysics Data System (ADS)

Neiner, C.; Monin, D.; Leroy, B.; Mathis, S.; Bohlender, D.

2014-02-01

Context. The bright B pulsator γ Peg shows both p and g modes of β Cep and SPB types. It has also been claimed that it is a magnetic star, while others do not detect any magnetic field. Aims: We check for the presence of a magnetic field, with the aim to characterise it if it exists, or else provide a firm upper limit of its strength if it is not detected. If γ Peg is magnetic as claimed, it would make an ideal asteroseismic target for testing various theoretical scenarios. If it is very weakly magnetic, it would be the first observation of an extension of Vega-like fields to early B stars. Finally, if it is not magnetic and we can provide a very low upper limit on its non-detected field, it would make an important result for stellar evolution models. Methods: We acquired high resolution, high signal-to-noise spectropolarimetric Narval data at Telescope Bernard Lyot (TBL). We also gathered existing dimaPol spectropolarimetric data from the Dominion Astrophysical Observatory (DAO) and Musicos spectropolarimetric data from TBL. We analysed the Narval and Musicos observations using the least-squares deconvolution (LSD) technique to derive the longitudinal magnetic field and Zeeman signatures in lines. The longitudinal field strength was also extracted from the Hβ line observed with the DAO. With a Monte Carlo simulation we derived the maximum strength of the field possibly hosted by γ Peg. Results: We find that no magnetic signatures are visible in the very high quality spectropolarimetric data. The average longitudinal field measured in the Narval data is Bl = -0.1 ± 0.4 G. We derive a very strict upper limit of the dipolar field strength of Bpol ~ 40 G. Conclusions: We conclude that γ Peg is not magnetic: it hosts neither a strong stable fossil field as observed in a fraction of massive stars nor a very weak Vega-like field. There is therefore no evidence that Vega-like fields exist in B stars, contrary to the predictions by fossil field dichotomy scenarios

The use of MR B+1 imaging for validation of FDTD electromagnetic simulations of human anatomies.

PubMed

Van den Berg, Cornelis A T; Bartels, Lambertus W; van den Bergen, Bob; Kroeze, Hugo; de Leeuw, Astrid A C; Van de Kamer, Jeroen B; Lagendijk, Jan J W

2006-10-07

In this study, MR B(+)(1) imaging is employed to experimentally verify the validity of FDTD simulations of electromagnetic field patterns in human anatomies. Measurements and FDTD simulations of the B(+)(1) field induced by a 3 T MR body coil in a human corpse were performed. It was found that MR B(+)(1) imaging is a sensitive method to measure the radiofrequency (RF) magnetic field inside a human anatomy with a precision of approximately 3.5%. A good correlation was found between the B(+)(1) measurements and FDTD simulations. The measured B(+)(1) pattern for a human pelvis consisted of a global, diagonal modulation pattern plus local B(+)(1) heterogeneties. It is believed that these local B(+)(1) field variations are the result of peaks in the induced electric currents, which could not be resolved by the FDTD simulations on a 5 mm(3) simulation grid. The findings from this study demonstrate that B(+)(1) imaging is a valuable experimental technique to gain more knowledge about the dielectric interaction of RF fields with the human anatomy.

TH-AB-BRA-03: Backscatter Dose Factors Re-Evaluated for Inhomogeneities in the Presence of a 1.5 T Magnetic Field Using the GPUMCD Monte Carlo Algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, S; Sarfehnia, A; Sahgal, A

Purpose: To quantify the backscatter dose factors near the interfaces for clinically relevant high atomic number materials using GPUMCD for the Elekta MRI Linac. Methods: Backscatter dose factors (BSDF) were calculated as the ratio of the dose with and without the presence of the heterogeneity. The BSDF’s were calculated either in the absence or presence of an orthogonal 1.5 T magnetic field. Doses were scored in small voxels of side 1 mm in a water phantom with dimensions of 20×20×20 cm using GPUMCD (Elekta). The minimum uncertainty in dose calculations was kept to 0.5%. A slab of thickness 2 cm,more » representing the inhomogeneity, was placed inside the phantom with variable position from the surface of the phantom. The slab was filled with either bone, aluminum, titanium, stainless steel, or dental amalgam. The phantom was irradiated using particles sampled from a histogram which represented the true MRI Linac spectrum. Results: With the application of the 1.5 T magnetic field (B-On), all of the BSDF’s were reduced by at least 8% compared to the no magnetic field (B-Off) cases. For the B-Off case, the BSDF decreases exponentially with the upstream distance away from the interface. With B-On, the BSDF decreases exponentially for titanium, SS, and amalgam. However, it remains constant for Aluminum. In the case of bone, the BSDF increases up to a distance of 4 mm away from the interface in the presence of the magnetic field. Conclusion: The BSDF does not depend upon the thickness of the homogeneous material above the inhomogeneity for either the B-Off or B-On cases. For all the materials investigated, the BSDF is lower at the interface for the B-On case. The exponential fall-off of the BSDF away from the interface is not valid for all the materials when the magnetic field is turned ON. Funding support for this research was provided by Elekta.« less

POTHMF: A program for computing potential curves and matrix elements of the coupled adiabatic radial equations for a hydrogen-like atom in a homogeneous magnetic field

NASA Astrophysics Data System (ADS)

Chuluunbaatar, O.; Gusev, A. A.; Gerdt, V. P.; Rostovtsev, V. A.; Vinitsky, S. I.; Abrashkevich, A. G.; Kaschiev, M. S.; Serov, V. V.

2008-02-01

discrete and continuous spectrum problems and obtaining asymptotic regular and irregular matrix radial solutions at r=100 for continuous spectrum problem on the Intel Pentium IV 2.4 GHz. The number of radial differential equations was equal to 6. The accompanying test run using the KANTBP program took 2 s for solving discrete and continuous spectrum problems using the above calculated potential curves, matrix elements and asymptotic regular and irregular matrix radial solutions. Note, that in the accompanied benchmark calculations of the photoionization cross-sections from the bound states of a hydrogen atom in a homogeneous magnetic field to continuum we have used interval [ r=0, r=1000] for continuous spectrum problem. The total number of radial differential equations was varied from 10 to 18. References:W.H. Press, S.A. Teukolsky, W.T. Vetterling, B.P. Flannery, Numerical Recipes: The Art of Scientific Computing, Cambridge University Press, Cambridge, 1986. http://www.netlib.org/lapack/. M. Abramovits, I.A. Stegun, Handbook of Mathematical Functions, Dover, New York, 1965. U. Fano, Colloq. Int. C.N.R.S. 273 (1977) 127; A.F. Starace, G.L. Webster, Phys. Rev. A 19 (1979) 1629-1640; C.V. Clark, K.T. Lu, A.F. Starace, in: H.G. Beyer, H. Kleinpoppen (Eds.), Progress in Atomic Spectroscopy, Part C, Plenum, New York, 1984, pp. 247-320; U. Fano, A.R.P. Rau, Atomic Collisions and Spectra, Academic Press, Florida, 1986. M.G. Dimova, M.S. Kaschiev, S.I. Vinitsky, J. Phys. B 38 (2005) 2337-2352; O. Chuluunbaatar, A.A. Gusev, V.L. Derbov, M.S. Kaschiev, V.V. Serov, T.V. Tupikova, S.I. Vinitsky, Proc. SPIE 6537 (2007) 653706-1-18. M.J. Seaton, Rep. Prog. Phys. 46 (1983) 167-257. M. Gailitis, J. Phys. B 9 (1976) 843-854; J. Macek, Phys. Rev. A 30 (1984) 1277-1278; S.I. Vinitsky, V.P. Gerdt, A.A. Gusev, M.S. Kaschiev, V.A. Rostovtsev, V.N. Samoylov, T.V. Tupikova, O. Chuluunbaatar, Programming and Computer Software 33 (2007) 105-116. H. Friedrich, Theoretical Atomic Physics, Springer

Properties of an ultrarelativistic charged particle radiation in a constant homogeneous crossed electromagnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogdanov, O.V., E-mail: bov@tpu.ru; Department of Higher Mathematics and Mathematical Physics, Tomsk Polytechnic University, Tomsk, 634050; Kazinski, P.O., E-mail: kpo@phys.tsu.ru

The properties of radiation created by a classical ultrarelativistic scalar charged particle in a constant homogeneous crossed electromagnetic field are described both analytically and numerically with radiation reaction taken into account in the form of the Landau–Lifshitz equation. The total radiation naturally falls into two parts: the radiation formed at the entrance point of a particle into the crossed field (the synchrotron entrance radiation), and the radiation coming from the late-time asymptotics of a particle motion (the de-excited radiation). The synchrotron entrance radiation resembles, although does not coincide with, the ultrarelativistic limit of the synchrotron radiation: its distribution over energiesmore » and angles possesses almost the same properties. The de-excited radiation is soft, not concentrated in the plane of motion of a charged particle, and almost completely circularly polarized. The photon energy delivering the maximum to its spectral angular distribution decreases with increasing the initial energy of a charged particle, while the maximum value of this distribution remains the same at the fixed photon observation angle and entrance angle of a charged particle. The ultraviolet and infrared asymptotics of the total radiation are also described. - Highlights: • Properties of an electron radiation in a crossed electromagnetic field are studied. • Spectral angular distribution of the synchrotron entrance radiation is described. • Spectral angular distribution of the de-excited radiation is described. • De-excited radiation is almost completely circularly polarized. • Photon energy at the maximum of the de-excited radiation decreases with increasing the initial energy of an electron.« less

Determining Electrical Properties Based on B1 Fields Measured in an MR Scanner Using a Multi-channel Transmit/Receive Coil: a General Approach

PubMed Central

Liu, Jiaen; Zhang, Xiaotong; Van de Moortele, Pierre-Francois; Schmitter, Sebastian

2013-01-01

Electrical Property Tomography (EPT) is a recently developed noninvasive technology to image the electrical conductivity and permittivity of biological tissues at Larmor frequency in Magnetic Resonance (MR) scanners. The absolute phase of the complex radio-frequency (RF) magnetic field (B1) is necessary for electrical property calculation. However, due to the lack of practical methods to directly measure the absolute B1 phases, current EPT techniques have been achieved with B1 phase estimation based on certain assumptions on object anatomy, coil structure and/or electromagnetic wave behavior associated with the main magnetic field, limiting EPT from a larger variety of applications. In this study, using a multi-channel transmit/receive coil, the framework of a new general approach for EPT has been introduced, which is independent on the assumptions utilized in previous studies. Using a human head model with realistic geometry, a series of computer simulations at 7T were conducted to evaluate the proposed method under different noise levels. Results showed that the proposed method can be used to reconstruct the conductivity and permittivity images with noticeable accuracy and stability. The feasibility of this approach was further evaluated in a phantom experiment at 7T. PMID:23743673

Sensitivity of fields generated within magnetically shielded volumes to changes in magnetic permeability

NASA Astrophysics Data System (ADS)

Andalib, T.; Martin, J. W.; Bidinosti, C. P.; Mammei, R. R.; Jamieson, B.; Lang, M.; Kikawa, T.

2017-09-01

Future experiments seeking to measure the neutron electric dipole moment (nEDM) require stable and homogeneous magnetic fields. Normally these experiments use a coil internal to a passively magnetically shielded volume to generate the magnetic field. The stability of the magnetic field generated by the coil within the magnetically shielded volume may be influenced by a number of factors. The factor studied here is the dependence of the internally generated field on the magnetic permeability μ of the shield material. We provide measurements of the temperature-dependence of the permeability of the material used in a set of prototype magnetic shields, using experimental parameters nearer to those of nEDM experiments than previously reported in the literature. Our measurements imply a range of 1/μ dμ/dT from 0-2.7%/K. Assuming typical nEDM experiment coil and shield parameters gives μ/B0 dB0/dμ = 0.01, resulting in a temperature dependence of the magnetic field in a typical nEDM experiment of dB0/dT = 0 - 270 pT/K for B0 = 1 μT. The results are useful for estimating the necessary level of temperature control in nEDM experiments.

Hyperfine field and magnetic structure in the B phase of CeCoIn5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graf, Matthias J; Curro, Nicholas J; Young, Ben - Li

2009-01-01

We re-analyze Nuclear Magnetic Resonance (NMR) spectra observed at low temperatures and high magnetic fields in the field-induced B-phase of CeCoIn{sub 5}. The NMR spectra are consistent with incommensurate antiferromagnetic order of the Ce magnetic moments. However, we find that the spectra of the In(2) sites depend critically on the direction of the ordered moments, the ordering wavevector and the symmetry of the hyperfine coupling to the Ce spins. Assuming isotropic hyperfine coupling, the NMR spectra observed for H {parallel} [100] are consistent with magnetic order with wavevector Q = {pi}(1+{delta}/a, 1/a, 1/c) and Ce moments ordered antiferromagnetically along themore » [100] direction in real space. If the hyperfine coupling has dipolar symmetry, then the NMR spectra require Ce moments along the [001] direction. The dipolar scenario is also consistent with recent neutron scattering measurements that find an ordered moment of 0.15{micro}{sub B} along [001] and Q{sub n} = {pi}(1+{delta}/a, 1+{delta}c, 1/c) with incommensuration {delta} = 0.12 for field H {parallel} [1{bar 1}0]. Using these parameters, we find that the hyperfine field is consistent with both experiments. We speculate that the B phase of CeCoIn{sub 5} represents an intrinsic phase of modulated superconductivity and antiferromagnetism that can only emerge in a highly clean system.« less

Aldo-keto Reductase 1B15 (AKR1B15)

PubMed Central

Weber, Susanne; Salabei, Joshua K.; Möller, Gabriele; Kremmer, Elisabeth; Bhatnagar, Aruni; Adamski, Jerzy; Barski, Oleg A.

2015-01-01

Aldo-keto reductases (AKRs) comprise a superfamily of proteins involved in the reduction and oxidation of biogenic and xenobiotic carbonyls. In humans, at least 15 AKR superfamily members have been identified so far. One of these is a newly identified gene locus, AKR1B15, which clusters on chromosome 7 with the other human AKR1B subfamily members (i.e. AKR1B1 and AKR1B10). We show that alternative splicing of the AKR1B15 gene transcript gives rise to two protein isoforms with different N termini: AKR1B15.1 is a 316-amino acid protein with 91% amino acid identity to AKR1B10; AKR1B15.2 has a prolonged N terminus and consists of 344 amino acid residues. The two gene products differ in their expression level, subcellular localization, and activity. In contrast with other AKR enzymes, which are mostly cytosolic, AKR1B15.1 co-localizes with the mitochondria. Kinetic studies show that AKR1B15.1 is predominantly a reductive enzyme that catalyzes the reduction of androgens and estrogens with high positional selectivity (17β-hydroxysteroid dehydrogenase activity) as well as 3-keto-acyl-CoA conjugates and exhibits strong cofactor selectivity toward NADP(H). In accordance with its substrate spectrum, the enzyme is expressed at the highest levels in steroid-sensitive tissues, namely placenta, testis, and adipose tissue. Placental and adipose expression could be reproduced in the BeWo and SGBS cell lines, respectively. In contrast, AKR1B15.2 localizes to the cytosol and displays no enzymatic activity with the substrates tested. Collectively, these results demonstrate the existence of a novel catalytically active AKR, which is associated with mitochondria and expressed mainly in steroid-sensitive tissues. PMID:25577493

Aflatoxin B1 in common Egyptian foods.

PubMed

Selim, M I; Popendorf, W; Ibrahim, M S; el Sharkawy, S; el Kashory, E S

1996-01-01

Samples of common Egyptian foods (17 nuts and seeds, 10 spices, 31 herbs and medicinal plants, 12 dried vegetables, and 28 cereal grains) were collected from markets in Cairo and Giza. A portion of each sample was extracted with chloroform, and the concentrated extract was cleaned by passing through a silica gel column. Aflatoxin B1 was determined by reversed-phase liquid chromatography with UV detection. The highest prevalence of aflatoxin B1 was in nuts and seeds (82%), followed by spices (40%), herbs and medicinal plants (29%), dried vegetables (25%), and cereal grains (21%). The highest mean concentration of aflatoxin B1 was in herb and medicinal plants (49 ppb), followed by cereals (36 ppb), spices (25 ppb), nuts and seeds (24 ppb), and dried vegetables (20 ppb). Among nuts and seeds, the prevalence of aflatoxin B1 was highest (100%) in watermelon seeds, inshell peanuts, and unshelled peanuts. The lowest prevalence and concentrations were in hommos (garbanzo beans). The highest concentrations of aflatoxin B1 were detected in foods that had no potential for field contamination but required drying during processing and storage, such as pomegranate peel, watermelon seeds, and molokhia.

Nascent bipolar outflows associated with the first hydrostatic core candidates Barnard 1b-N and 1b-S

NASA Astrophysics Data System (ADS)

Gerin, M.; Pety, J.; Fuente, A.; Cernicharo, J.; Commerçon, B.; Marcelino, N.

2015-05-01

In the theory of star formation, the first hydrostatic core (FHSC) phase is a critical step in which a condensed object emerges from a prestellar core. This step lasts about one thousand years, a very short time compared with the lifetime of prestellar cores, and therefore is hard to detect unambiguously. We present IRAM Plateau de Bure observations of the Barnard 1b dense molecular core, combining detections of H2CO and CH3OH spectral lines and dust continuum at 2.3'' resolution (~500 AU). The two compact cores B1b-N and B1b-S are detected in the dust continuum at 2 mm, with fluxes that agree with their spectral energy distribution. Molecular outflows associated with both cores are detected. They are inclined relative to the direction of the magnetic field, in agreement with predictions of collapse in turbulent and magnetized gas with a ratio of mass to magnetic flux somewhat higher than the critical value, μ ~ 2-7. The outflow associated with B1b-S presents sharp spatial structures, with ejection velocities of up to ~7 km s-1 from the mean velocity. Its dynamical age is estimated to be ~2000 yr. The B1b-N outflow is smaller and slower, with a short dynamical age of ~1000 yr. The B1b-N outflow mass, mass-loss rate, and mechanical luminosity agree well with theoretical predictions of FHSC. These observations confirm the early evolutionary stage of B1b-N and the slightly more evolved stage of B1b-S. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).Appendices are available in electronic form at http://www.aanda.orgFITS files for the H2CO and CH3OH mosaics are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/L2

B-1 phagocytes: the myeloid face of B-1 cells.

PubMed

Popi, Ana Flavia

2015-12-01

The relationship between malignant B cells and macrophages has long been established. Furthermore, evolutionary studies have demonstrated that B cells from early vertebrates have both phagocytic and antibody production capabilities. In addition to their lymphoid nature, B-1 cells retain several myeloid characteristics. Various reports have demonstrated that B-1 cells can differentiate into phagocytes. However, descriptions of B-1 cells as a novel phagocyte cell member are rarely found in the literature. This review aims to present the available data regarding B-1 cell-derived phagocytes and also discusses how their existence might be relevant to hematopoiesis and immune responses. © 2015 New York Academy of Sciences.

The interplanetary magnetic field B sub y -dependent field-aligned current in the dayside polar cap under quiet conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamauchi, M.; Araki, T.

1989-03-01

Spatial distribution and temporal variation of the interplanetary magnetic field (IMF) B{sub y}-dependent cusp region field-aligned currents (FACs) during quiet periods were studied by use of magnetic data observed by Magsat. The analysis was made for 11 events (each event lasts more than one and a half days) when the IMF B{sub y} component was steadily large and B{sub x} was relatively small ({vert bar}B{sub z}{vert bar} < {vert bar}B{sub y}{vert bar}). Results of the analysis of total 62 half-day periods for the IMF B{sub y}-dependent cusp region FAC are summarized as follows: (1) the IMF B{sub y}-dependent cusp regionmore » FAC is located at around 86{degree}-87{degree} invariant latitude local noon, which is more poleward than the location of the IMF B{sub z}-dependent cusp region FAC; (2) the current density of this FAC is greater than previous studies ({ge} 4 {mu}A/m{sup 2} for IMF B{sub y} = 6 nT); (3) there are two time scales for the IMF B{sub y}-dependent cusp region FAC to appear: the initial rise of the current is on a short time scale, {approximately} 10 min, and it is followed by a gradual increase on a time scale of several hours to a half day; (4) the seasonal change of this FAC is greater than that of the nightside region 1 or region 2 FACs; (5) the IMF B{sub z}-dependent cusp region FAC is not well observed around the cusp when the IMF B{sub y}-dependent cusp region FAC is intense.« less

Effect of magnetic field inhomogeneity on ion cyclotron motion coherence at high magnetic field.

PubMed

Vladimirov, Gleb; Kostyukevich, Yury; Hendrickson, Christopher L; Blakney, Greg T; Nikolaev, Eugene

2015-01-01

A three-dimensional code based on the particle-in-cell algorithm modified to account for the inhomogeneity of the magnetic field was applied to determine the effect of Z(1), Z(2), Z(3), Z(4), X, Y, ZX, ZY, XZ(2) YZ(2), XY and X(2)-Y(2) components of an orthogonal magnetic field expansion on ion motion during detection in an FT-ICR cell. Simulations were performed for magnetic field strengths of 4.7, 7, 14.5 and 21 Tesla, including experimentally determined magnetic field spatial distributions for existing 4.7 T and 14.5 T magnets. The effect of magnetic field inhomogeneity on ion cloud stabilization ("ion condensation") at high numbers of ions was investigated by direct simulations of individual ion trajectories. Z(1), Z(2), Z(3) and Z(4) components have the largest effect (especially Z(1)) on ion cloud stability. Higher magnetic field strength and lower m/z demand higher relative magnetic field homogeneity to maintain cloud coherence for a fixed time period. The dependence of mass resolving power upper limit on Z(1) inhomogeneity is evaluated for different magnetic fields and m/z. The results serve to set the homogeneity requirements for various orthogonal magnetic field components (shims) for future FT-ICR magnet design.

75 FR 16664 - Airworthiness Directives; Turbomeca ARRIEL 1B, 1D, 1D1, 2B, and 2B1 Turboshaft Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-02

... limited to, Eurocopter AS 350 B, AS 350 BA, AS 350 B1, AS 350 B2, AS 350 B3, and EC 130 B4 helicopters... an aviation product. The MCAI describes the unsafe condition as: During production of Arriel 1 and... by Turbom[eacute]ca. Potentially non-conforming PT blades have been traced as having been installed...

Preliminary characterization of Thy-1.1 and Ag-B antigens from rat tissues solubilized in detergents

PubMed Central

Letarte-Muirhead, Michelle; Acton, Ronald T.; Williams, Alan F.

1974-01-01

1. A radioactive binding assay for Thy-1.1 alloantigen which functions in the presence of detergents was established by using glutaraldehyde-fixed thymocytes as target cells. Thy-1.1 activity in detergent extracts was then assayed by measuring inhibition of the binding assay. 2. Solubilization of Thy-1.1 from whole thymocytes, and their membranes by a large number of non-ionic detergents and deoxycholate was studied. In the same extracts Ag-B(4) histocompatibility antigenic activities were measured. With the exception of Nonidet P-40, the detergents did not affect the antigenicity of Thy-1.1, but only Lubrol-PX and deoxycholate gave effective solubilization as measured by activity remaining in the supernatant after centrifugation at 200000g for 40min. With Ag-B(4) antigen, Triton X-100, Triton X-67 and Nonidet P-40 gave effective solubilization as well as Lubrol-PX and deoxycholate. Solubilization of Thy-1.1 activity from leukaemia cells and a brain homogenate was also studied, but none of the non-ionic detergents gave satisfactory results with these tissues. 3. Extracts from thymocyte membranes were further examined by gel filtration and sucrose gradient centrifugation. The Thy-1.1 activity behaved as a single component in deoxycholate with a density similar to that of a globular protein, but in Lubrol-PX the antigen was contained in a low-density complex. In Lubrol-PX extracts Ag-B(4) was also found in aggregates not observed in deoxycholate. 4. The s20,w values for Thy-1.1 and Ag-B(4) antigens in deoxycholate were 2.4 and 4.4, and v̄ values were 0.70 and 0.75 respectively. The Stokes radius observed for Thy-1.1 was 3.1nm and for Ag-B(4) 5.3nm. By using these values the molecular weights for the antigen–detergent complexes were calculated to be 28000 for Thy-1.1 and 100000 for Ag-B(4). PMID:4219284

Magnetic field control of microstructural development in melt-spun Pr2Co14 B

NASA Astrophysics Data System (ADS)

McGuire, Michael A.; Rios, Orlando; Conner, Ben S.; Carter, William G.; Huang, Mianliang; Sun, Kewei; Palasyuk, Olena; Jensen, Brandt; Zhou, Lin; Dennis, Kevin; Nlebedim, Ikenna C.; Kramer, Matthew J.

2017-05-01

In the processing of commercial rare earth permanent magnets, use of external magnetic fields is limited mainly to the alignment of anisotropic particles and the polarization of the finished magnets. Here we explore the effects of high magnetic fields on earlier stages of magnet synthesis, including the crystallization and chemical phase transformations that produce the 2:14:1 phase in the Pr-Co-B system. Pr2Co14 B alloys produced by melt-spinning were annealed in the presence of strong applied magnetic fields (H=90 kOe). The resulting materials were characterized by x-ray diffraction, electron microscopy, and magnetization measurements. We find that magnetic fields suppress the nucleation and growth of crystalline phases, resulting in significantly smaller particle sizes. In addition, magnetic fields applied during processing strongly affects chemical phase selection, suppressing the formation of Pr2Co14 B and α-Co in favor of Pr2Co17 . The results demonstrate that increased control over key microstructural properties is achievable by including a strong magnetic field as a processing parameter for rare-earth magnet materials.

Relaxor-ferroelectric crossover in (B i1 /2K1 /2)Ti O3 : Origin of the spontaneous phase transition and the effect of an applied external field

NASA Astrophysics Data System (ADS)

Hagiwara, Manabu; Ehara, Yoshitaka; Novak, Nikola; Khansur, Neamul H.; Ayrikyan, Azatuhi; Webber, Kyle G.; Fujihara, Shinobu

2017-07-01

The temperature evolution of polar order in an A -site complex perovskite (B i1 /2K1 /2)Ti O3 (BKT) has been investigated by measurements of dielectric permittivity, depolarization current, and stress-stain curves at elevated temperatures. Upon cooling from high temperatures, BKT first enters a relaxor state and then spontaneously transforms into a ferroelectric state. The analyses of temperature and frequency dependence of permittivity have revealed that polar nanoregions of the relaxor phase appear at temperatures higher than 560°C, and also that their freezing at 296°C triggers the spontaneous relaxor-ferroelectric transition. We discuss the key factors determining the development of long-range polar order in A -site complex perovskites through a comparison with the relaxor (B i1 /2N a1 /2)Ti O3 . We also show that application of biasing electric fields and compressive stresses to BKT favors its ferroelectric phase, resulting in a significant shift of the relaxor-ferroelectric transition temperature towards higher temperatures. Based on the obtained results, electric field-temperature and stress-temperature phase diagrams are firstly determined for BKT.

Homogenization versus homogenization-free method to measure muscle glycogen fractions.

PubMed

Mojibi, N; Rasouli, M

2016-12-01

The glycogen is extracted from animal tissues with or without homogenization using cold perchloric acid. Three methods were compared for determination of glycogen in rat muscle at different physiological states. Two groups of five rats were kept at rest or 45 minutes muscular activity. The glycogen fractions were extracted and measured by using three methods. The data of homogenization method shows that total glycogen decreased following 45 min physical activity and the change occurred entirely in acid soluble glycogen (ASG), while AIG did not change significantly. Similar results were obtained by using "total-glycogen-fractionation methods". The findings of "homogenization-free method" indicate that the acid insoluble fraction (AIG) was the main portion of muscle glycogen and the majority of changes occurred in AIG fraction. The results of "homogenization method" are identical with "total glycogen fractionation", but differ with "homogenization-free" protocol. The ASG fraction is the major portion of muscle glycogen and is more metabolically active form.

Beyond relationships between homogeneous and heterogeneous catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dixon, David A.; Katz, Alexander; Arslan, Ilke

2014-08-13

Scientists who regard catalysis as a coherent field have been striving for decades to articulate the fundamental unifying principles. But because these principles seem to be broader than chemistry, chemical engineering, and materials science combined, catalytic scientists commonly interact within the sub-domains of homogeneous, heterogeneous, and bio-catalysis, and increasingly within even narrower domains such as organocatalysis, phase-transfer catalysis, acid-base catalysis, zeolite catalysis, etc. Attempts to unify catalysis have motivated researchers to find relationships between homogeneous and heterogeneous catalysis and to mimic enzymes. These themes have inspired vibrant international meetings and workshops, and we have benefited from the idea exchanges andmore » have some thoughts about a path forward.« less

Assessment the effect of homogenized soil on soil hydraulic properties and soil water transport

NASA Astrophysics Data System (ADS)

Mohawesh, O.; Janssen, M.; Maaitah, O.; Lennartz, B.

2017-09-01

Soil hydraulic properties play a crucial role in simulating water flow and contaminant transport. Soil hydraulic properties are commonly measured using homogenized soil samples. However, soil structure has a significant effect on the soil ability to retain and to conduct water, particularly in aggregated soils. In order to determine the effect of soil homogenization on soil hydraulic properties and soil water transport, undisturbed soil samples were carefully collected. Five different soil structures were identified: Angular-blocky, Crumble, Angular-blocky (different soil texture), Granular, and subangular-blocky. The soil hydraulic properties were determined for undisturbed and homogenized soil samples for each soil structure. The soil hydraulic properties were used to model soil water transport using HYDRUS-1D.The homogenized soil samples showed a significant increase in wide pores (wCP) and a decrease in narrow pores (nCP). The wCP increased by 95.6, 141.2, 391.6, 3.9, 261.3%, and nCP decreased by 69.5, 10.5, 33.8, 72.7, and 39.3% for homogenized soil samples compared to undisturbed soil samples. The soil water retention curves exhibited a significant decrease in water holding capacity for homogenized soil samples compared with the undisturbed soil samples. The homogenized soil samples showed also a decrease in soil hydraulic conductivity. The simulated results showed that water movement and distribution were affected by soil homogenizing. Moreover, soil homogenizing affected soil hydraulic properties and soil water transport. However, field studies are being needed to find the effect of these differences on water, chemical, and pollutant transport under several scenarios.

Asymmetric Conjugated Molecules Based on [1]Benzothieno[3,2-b][1]benzothiophene for High-Mobility Organic Thin-Film Transistors: Influence of Alkyl Chain Length.

PubMed

He, Keqiang; Li, Weili; Tian, Hongkun; Zhang, Jidong; Yan, Donghang; Geng, Yanhou; Wang, Fosong

2017-10-11

Herein, we report the synthesis and characterization of a series of [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based asymmetric conjugated molecules, that is, 2-(5-alkylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-Tn, in which T and n represent thiophene and the number of carbons in the alkyl group, respectively). All of the molecules with n ≥ 4 show mesomorphism and display smectic A, smectic B (n = 4), or smectic E (n > 4) phases and then crystalline phases in succession upon cooling from the isotropic state. Alkyl chain length has a noticeable influence on the microstructures of vacuum-deposited films and therefore on the performance of the organic thin-film transistors (OTFTs). All molecules except for 2-(thiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-ethylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene showed OTFT mobilities above 5 cm 2 V -1 s -1 . 2-(5-Hexylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-heptylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene showed the greatest OTFT performance with reliable hole mobilities (μ) up to 10.5 cm 2 V -1 s -1 because they formed highly ordered and homogeneous films with diminished grain boundaries.

Magnetic design and method of a superconducting magnet for muon g - 2/EDM precise measurements in a cylindrical volume with homogeneous magnetic field

NASA Astrophysics Data System (ADS)

Abe, M.; Murata, Y.; Iinuma, H.; Ogitsu, T.; Saito, N.; Sasaki, K.; Mibe, T.; Nakayama, H.

2018-05-01

A magnetic field design method of magneto-motive force (coil block (CB) and iron yoke) placements for g - 2/EDM measurements has been developed and a candidate placements were designed under superconducting limitations of current density 125 A/mm2 and maximum magnetic field on CBs less than 5.5 T. Placements of CBs and an iron yoke with poles were determined by tuning SVD (singular value decomposition) eigenmode strengths. The SVD was applied on a response matrix from magneto-motive forces to the magnetic fields in the muon storage region and two-dimensional (2D) placements of magneto-motive forces were designed by tuning the magnetic field eigenmode strengths obtained by the magnetic field. The tuning was performed iteratively. Magnetic field ripples in the azimuthal direction were minimized for the design. The candidate magnetic design had five CBs and an iron yoke with center iron poles. The magnet satisfied specifications of homogeneity (0.2 ppm peak-to-peak in 2D placements (the cylindrical coordinate of the radial position R and axial position Z) and less than 1.0 ppm ripples in the ring muon storage volume (0.318 m < R < 0 . 348 m and -0.05 < Z < 0.05 m) with 3.0 T strength and a slightly negative BR (magnetic field radial component) at Z > 0.0 m) for the spiral muon injection from the iron yoke at top.

Plane-parallel waves as duals of the flat background III: T-duality with torsionless B-field

NASA Astrophysics Data System (ADS)

Hlavatý, Ladislav; Petr, Ivo; Petrásek, Filip

2018-04-01

By addition of non-zero, but torsionless B-field, we expand the classification of (non-)Abelian T-duals of the flat background in four dimensions with respect to 1, 2, 3 and 4D subgroups of the Poincaré group. We discuss the influence of the additional B-field on the process of dualization, and identify essential parts of the torsionless B-field that cannot in general be eliminated by coordinate or gauge transformation of the dual background. These effects are demonstrated using particular examples. Due to their physical importance, we focus on duals whose metrics represent plane-parallel (pp-)waves. Besides the previously found metrics, we find new pp-waves depending on parameters originating from the torsionless B-field. These pp-waves are brought into their standard forms in Brinkmann and Rosen coordinates.

Gravity field information from Gravity Probe-B

NASA Technical Reports Server (NTRS)

Smith, D. E.; Lerch, F. J.; Colombo, O. L.; Everitt, C. W. F.

1989-01-01

The Gravity Probe-B Mission will carry the Stanford Gyroscope relativity experiment into orbit in the mid 1990's, as well as a Global Positioning System (GPS) receiver whose tracking data will be used to study the earth gravity field. Estimates of the likely quality of a gravity field model to be derived from the GPS data are presented, and the significance of this experiment to geodesy and geophysics are discussed.

Insecticidal components from field pea extracts: isolation and separation of peptide mixtures related to pea albumin 1b.

PubMed

Taylor, Wesley G; Fields, Paul G; Elder, James L

2004-12-15

Chromatographic fractionation of crude extracts (C8 extracts) from the protein-enriched flour of commercial field peas (Pisum sativum L.) has been shown here to yield peptide mixtures related to the pea albumin 1b (PA1b) family of cysteine-rich plant peptides. The mixtures were obtained initially by flash chromatography with silica gel. Following elution of soyasaponins and lysolecithins, the end fractions obtained with the use of two flash chromatographic solvent systems displayed activity in a flour disk antifeedant bioassay with the rice weevil [Sitophilus oryzae (L.)]. Chemical properties of these mixtures were compared by thin-layer chromatography, high-performance liquid chromatography (HPLC), IR, MS, and amino acid analyses. The major peptides of C8 extracts, with average masses of 3752, 3757, and 3805 Da, were isolated by anion exchange chromatography. Samples enriched in the peptide of mass 3752 were isolated by cation exchange chromatography. Reduction plus alkylation experiments in combination with electrospray ionization mass spectrometry showed that C8 extracts contained about 10 peptides and, like PA1b, each peptide possessed six cysteine residues (three disulfide bonds). Disulfide bond reduction with 2-mercaptoethanol destroyed the antifeedant activity. The native peptides of C8 extracts were found to be resolved into nine peaks with XTerra HPLC columns operating at alkaline pH. These columns were employed to assess the distribution of pea peptides in the isolated fractions, with photodiode array and electrospray detection.

Electric field dependent local structure of (KxNa1-x) 0.5B i0.5Ti O3

NASA Astrophysics Data System (ADS)

Goetzee-Barral, A. J.; Usher, T.-M.; Stevenson, T. J.; Jones, J. L.; Levin, I.; Brown, A. P.; Bell, A. J.

2017-07-01

The in situ x-ray pair-distribution function (PDF) characterization technique has been used to study the behavior of (KxNa1-x) 0.5B i0.5Ti O3 , as a function of electric field. As opposed to conventional x-ray Bragg diffraction techniques, PDF is sensitive to local atomic displacements, detecting local structural changes at the angstrom to nanometer scale. Several field-dependent ordering mechanisms can be observed in x =0.15 , 0.18 and at the morphotropic phase boundary composition x =0.20 . X-ray total scattering shows suppression of diffuse scattering with increasing electric-field amplitude, indicative of an increase in structural ordering. Analysis of PDF peaks in the 3-4-Å range shows ordering of Bi-Ti distances parallel to the applied electric field, illustrated by peak amplitude redistribution parallel and perpendicular to the electric-field vector. A transition from <110 > to <112 > -type off-center displacements of Bi relative to the neighboring Ti atoms is observable with increasing x . Analysis of PDF peak shift with electric field shows the effects of Bi-Ti redistribution and onset of piezoelectric lattice strain. The combination of these field-induced ordering mechanisms is consistent with local redistribution of Bi-Ti distances associated with domain reorientation and an overall increase in order of atomic displacements.

Effect of head motion on MRI B0 field distribution.

PubMed

Liu, Jiaen; de Zwart, Jacco A; van Gelderen, Peter; Murphy-Boesch, Joseph; Duyn, Jeff H

2018-05-16

To identify and characterize the sources of B 0 field changes due to head motion, to reduce motion sensitivity in human brain MRI. B 0 fields were measured in 5 healthy human volunteers at various head poses. After measurement of the total field, the field originating from the subject was calculated by subtracting the external field generated by the magnet and shims. A subject-specific susceptibility model was created to quantify the contribution of the head and torso. The spatial complexity of the field changes was analyzed using spherical harmonic expansion. Minor head pose changes can cause substantial and spatially complex field changes in the brain. For rotations and translations of approximately 5 º and 5 mm, respectively, at 7 T, the field change that is associated with the subject's magnetization generates a standard deviation (SD) of about 10 Hz over the brain. The stationary torso contributes to this subject-associated field change significantly with a SD of about 5 Hz. The subject-associated change leads to image-corrupting phase errors in multi-shot T2*-weighted acquisitions. The B 0 field changes arising from head motion are problematic for multishot T2*-weighted imaging. Characterization of the underlying sources provides new insights into mitigation strategies, which may benefit from individualized predictive field models in addition to real-time field monitoring and correction strategies. © 2018 International Society for Magnetic Resonance in Medicine.

Mean-field theory on mixed ferro-ferrimagnetic compounds with (A aB bC c) yD

NASA Astrophysics Data System (ADS)

Wei, Guo-Zhu; Xin, Zihua; Liang, Yaqiu; Zhang, Qi

2004-01-01

The magnetic properties of the mixed ferro-ferrimagnetic compounds with (A aB bC c) yD, in which A, B, C and D are four different magnetic ions and form four different sublattices, are studied by using the Ising model. And the Ising model was dealt with standard mean-field approximation. The regions of concentration in which two compensation points or one compensation point exit are given in c- a, b- c and a- b planes. The phase diagrams of the transition temperature Tc and compensation temperature Tcomp are obtained. The temperature dependences of the magnetization are also investigated. Some of the result can be used to explain the experimental work of the molecule-based ferro-ferrimagnet (Ni IIaMn IIbFe IIc) 1.5[Cr III(CN) 6]· zH 2O.

Robust reconstruction of B1 (+) maps by projection into a spherical functions space.

PubMed

Sbrizzi, Alessandro; Hoogduin, Hans; Lagendijk, Jan J; Luijten, Peter; van den Berg, Cornelis A T

2014-01-01

Several parallel transmit MRI techniques require knowledge of the transmit radiofrequency field profiles (B1 (+) ). During the past years, various methods have been developed to acquire this information. Often, these methods suffer from long measurement times and produce maps exhibiting regions with poor signal-to-noise ratio and artifacts. In this article, a model-based reconstruction procedure is introduced that improves the robustness of B1 (+) mapping. The missing information from undersampled B1 (+) maps and the regions of poor signal to noise ratio are reconstructed through projection into the space of spherical functions that arise naturally from the solution of the Helmholtz equations in the spherical coordinate system. As a result, B1 (+) data over a limited range of the field of view/volume is sufficient to reconstruct the B1 (+) over the full spatial domain in a fast and robust way. The same model is exploited to filter the noise of the measured maps. Results from simulations and in vivo measurements confirm the validity of the proposed method. A spherical functions model can well approximate the magnetic fields inside the body with few basis terms. Exploiting this compression capability, B1 (+) maps are reconstructed in regions of unknown or corrupted values. Copyright © 2013 Wiley Periodicals, Inc.

Magnetic Susceptibility as a B0 Field Strength Independent MRI Biomarker of Liver Iron Overload

PubMed Central

Hernando, Diego; Cook, Rachel J.; Diamond, Carol; Reeder, Scott B.

2013-01-01

Purpose MR-based quantification of liver magnetic susceptibility may enable field strength-independent measurement of liver iron concentration (LIC). However, susceptibility quantification is challenging, due to non-local effects of susceptibility on the B0 field. The purpose of this work is to demonstrate feasibility of susceptibility-based LIC quantification using a fat-referenced approach. Methods Phantoms consisting of vials with increasing iron concentrations immersed between oil/water layers, and twenty-seven subjects (9 controls/18 subjects with liver iron overload) were scanned. Ferriscan (1.5T) provided R2-based reference LIC. Multi-echo 3D-SPGR (1.5T/3T) enabled fat-water, B0- and R2*-mapping. Phantom iron concentration (mg Fe/l) was estimated from B0 differences (ΔB0) between vials and neighboring oil. Liver susceptibility and LIC (mg Fe/g dry tissue) was estimated from ΔB0 between the lateral right lobe of the liver and adjacent subcutaneous adipose tissue (SAT). Results Estimated phantom iron concentrations had good correlation with true iron concentrations (1.5T:slope=0.86, intercept=0.72, r2=0.98; 3T:slope=0.85, intercept=1.73, r2=0.98). In liver, ΔB0 correlated strongly with R2* (1.5T:r2=0.86; 3T:r2=0.93) and B0-LIC had good agreement with Ferriscan-LIC (slopes/intercepts nearly 1.0/0.0, 1.5T:r2=0.67, slope=0.93±0.13, p≈0.50, intercept=1.93±0.78, p≈0.02; 3T:r2=0.84, slope=1.01±0.09, p≈0.90, intercept=0.23±0.52, p≈0.68). Discussion Fat-referenced, susceptibility-based LIC estimation is feasible at both field strengths. This approach may enable improved susceptibility mapping in the abdomen. PMID:23801540

The rotation-vibration structure of the SO 2 C 1B 2 state explained by a new internal coordinate force field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Jun; Park, G. Barratt; Field, Robert W.

A new quartic force field for the SO 2 C ~ 1B 2 state has been derived, based on high resolution data from S 16O 2 and S 18O 2. Included are eight b 2 symmetry vibrational levels of S 16O 2 reported in the first paper of this series [G. B. Park, et al., J. Chem. Phys. 144, 144311 (2016)]. Many of the experimental observables not included in the fit, such as the Franck-Condon intensities and the Coriolis-perturbed effective C rotational constants of highly anharmonic C ~ state vibrational levels, are well reproduced using our force field. Because themore » two stretching modes of the C ~ state are strongly coupled via Fermi-133 interaction, the vibrational structure of the C state is analyzed in a Fermi-system basis set, constructed explicitly in this work via partial diagonalization of the vibrational Hamiltonian. The physical significance of the Fermi-system basis is discussed in terms of semiclassical dynamics, based on study of Fermi-resonance systems by Kellman and coworkers [M. E. Kellman and L. Xiao, J. Chem. Phys. 93, 5821 (1990)]. By diagonalizing the vibrational Hamiltonian in the Fermi-system basis, the vibrational characters of all vibrational levels can be determined unambiguously. It is shown that the bending mode cannot be treated separately from the coupled stretching modes, particularly at vibrational energies of more than 2000 cm –1. Based on our force field, the structure of the Coriolis interactions in the C ~ state of SO 2 is also discussed. As a result, we identify the origin of the alternating patterns in the effective C rotational constants of levels in the vibrational progressions of the symmetry-breaking mode, ν β (which correlates with the antisymmetric stretching mode in our assignment scheme).« less

The rotation-vibration structure of the SO 2 C 1B 2 state explained by a new internal coordinate force field

DOE PAGES

Jiang, Jun; Park, G. Barratt; Field, Robert W.

2016-04-14

A new quartic force field for the SO 2 C ~ 1B 2 state has been derived, based on high resolution data from S 16O 2 and S 18O 2. Included are eight b 2 symmetry vibrational levels of S 16O 2 reported in the first paper of this series [G. B. Park, et al., J. Chem. Phys. 144, 144311 (2016)]. Many of the experimental observables not included in the fit, such as the Franck-Condon intensities and the Coriolis-perturbed effective C rotational constants of highly anharmonic C ~ state vibrational levels, are well reproduced using our force field. Because themore » two stretching modes of the C ~ state are strongly coupled via Fermi-133 interaction, the vibrational structure of the C state is analyzed in a Fermi-system basis set, constructed explicitly in this work via partial diagonalization of the vibrational Hamiltonian. The physical significance of the Fermi-system basis is discussed in terms of semiclassical dynamics, based on study of Fermi-resonance systems by Kellman and coworkers [M. E. Kellman and L. Xiao, J. Chem. Phys. 93, 5821 (1990)]. By diagonalizing the vibrational Hamiltonian in the Fermi-system basis, the vibrational characters of all vibrational levels can be determined unambiguously. It is shown that the bending mode cannot be treated separately from the coupled stretching modes, particularly at vibrational energies of more than 2000 cm –1. Based on our force field, the structure of the Coriolis interactions in the C ~ state of SO 2 is also discussed. As a result, we identify the origin of the alternating patterns in the effective C rotational constants of levels in the vibrational progressions of the symmetry-breaking mode, ν β (which correlates with the antisymmetric stretching mode in our assignment scheme).« less

The relationship between the boron dipyrromethene (BODIPY) structure and the effectiveness of homogeneous and heterogeneous solar hydrogen-generating systems as well as DSSCs.

PubMed

Luo, Geng-Geng; Lu, Hui; Zhang, Xiao-Long; Dai, Jing-Cao; Wu, Ji-Huai; Wu, Jia-Jia

2015-04-21

A series of boron dipyrromethene (BODIPY) dyes (B1–B5) having H atoms at 2,6-positions or heavy-atom I at 2-/2,6-positions, and an ortho- or a para-COOH substituted phenyl moiety at the 8-position on the BODIPY core were synthesized and characterized. These organic dyes were applied for investigating the relationship between the BODIPY structure and the effectiveness of homogeneous and heterogeneous visible-light-driven hydrogen production as well as dye-sensitized solar cells (DSSCs). For the homogeneous photocatalytic hydrogen production systems with a cobaloxime catalyst, the efficiency of hydrogen production could be tuned by substituting with heavy atoms and varying carboxyl group orientations of BODIPYs. As a result, B5 containing two I atoms and an ortho-COOH anchoring group was the most active one (TONs = 197). The activity of hydrogen generation followed the order B5 > B3 > B2 > B1 = B4 = 0. An interesting “ortho-position effect” was observed in the present homogeneous systems, i.e., substitution groups were located at the ortho-position and higher hydrogen production activities were obtained. For the heterogeneous hydrogen production systems with a platinized TiO2 catalyst, the effectiveness of hydrogen evolution was highly influenced by the intersystem crossing efficiency, molar absorptivity and positions of the anchoring group of dyes. Thus, B3 having two core iodine atoms and a para-COOH group with TONs of 70 excelled other BODIPYs and the TONs of hydrogen generation showed the trend of B3 > B5 > B2 > B1 = B4 = 0. The results demonstrate that the present photocatalytic H2 production proceeds with higher efficiency and stability in the homogeneity than in the heterogeneity. In the case of DSSCs, the overall cell performance of BODIPY chromophores was highly dependent on both the absence or the presence of iodine atoms on the BODIPY core and –COOH anchoring positions. The B1–TiO2 system showed the best cell performance, because the most

Magnetic field control of microstructural development in melt-spun Pr 2 Co 14 B

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGuire, Michael A.; Rios, Orlando; Conner, Ben S.

In the processing of commercial rare earth permanent magnets, use of external magnetic fields is limited mainly to the alignment of anisotropic particles and the polarization of the finished magnets. Here we explore the effects of high magnetic fields on earlier stages of magnet synthesis, including the crystallization and chemical phase transformations that produce the 2:14:1 phase in the Pr-Co-B system. Pr 2Co 14B alloys produced by melt-spinning were annealed in the presence of strong applied magnetic fields (H=90 kOe). The resulting materials were characterized by x-ray diffraction, electron microscopy, and magnetization measurements. We find that magnetic fields suppress themore » nucleation and growth of crystalline phases, resulting in significantly smaller particle sizes. In addition, magnetic fields applied during processing strongly affects chemical phase selection, suppressing the formation of Pr 2Co 14B and α-Co in favor of Pr 2Co 17. Here, the results demonstrate that increased control over key microstructural properties is achievable by including a strong magnetic field as a processing parameter for rare-earth magnet materials.« less

Magnetic field control of microstructural development in melt-spun Pr 2 Co 14 B

DOE PAGES

McGuire, Michael A.; Rios, Orlando; Conner, Ben S.; ...

2017-01-27

In the processing of commercial rare earth permanent magnets, use of external magnetic fields is limited mainly to the alignment of anisotropic particles and the polarization of the finished magnets. Here we explore the effects of high magnetic fields on earlier stages of magnet synthesis, including the crystallization and chemical phase transformations that produce the 2:14:1 phase in the Pr-Co-B system. Pr 2Co 14B alloys produced by melt-spinning were annealed in the presence of strong applied magnetic fields (H=90 kOe). The resulting materials were characterized by x-ray diffraction, electron microscopy, and magnetization measurements. We find that magnetic fields suppress themore » nucleation and growth of crystalline phases, resulting in significantly smaller particle sizes. In addition, magnetic fields applied during processing strongly affects chemical phase selection, suppressing the formation of Pr 2Co 14B and α-Co in favor of Pr 2Co 17. Here, the results demonstrate that increased control over key microstructural properties is achievable by including a strong magnetic field as a processing parameter for rare-earth magnet materials.« less

Field emission investigations of single crystal LaB6 FEA fabricated by femtosecond laser direct writing

NASA Astrophysics Data System (ADS)

Liu, Hongliang; Zhang, Xin; Li, Yuancheng; Xiao, Yixin; Zhang, Wei; Zhang, Jiu-Xing

2018-04-01

The femtosecond laser direct writing method has been used to fabricate the single crystal lanthanum hexaboride (LaB6) field-emission tip arrays (FEAs). The morphologies, structure phase, and field emission of the single crystal LaB6 FEAs are systematically studied. The nanostructures on the surface of tips with the LaB6 phase were formed, resulting in favor of improving field emission, particularly for samples with the nanohill shaped bulges having the size of about 100 nm. The produced single crystal LaB6 FEAs have a uniform structure and a controllable curvature radius of about 0.5-3.0 μm. The FEAs with a curvature radius of about 0.5 μm as field emitters have the best field emission performance, which the field emission turns on and the threshold electric fields are as low as 2.2 and 3.8 V/μm with an emission current of 1.0 A/cm2 at 8.0 V/μm, and the emission current exhibits high stability. These indicate that the processed LaB6 FEAs have a good prospect applied in vacuum microelectronic devices and the simple femtosecond laser direct writing method could lead to an approach for the development of electron sources.

Penetration of the Interplanetary Magnetic Field B(sub y) into Earth's Plasma Sheet

NASA Technical Reports Server (NTRS)

Hau, L.-N.; Erickson, G. M.

1995-01-01

There has been considerable recent interest in the relationship between the cross-tail magnetic field component B(sub y) and tail dynamics. The purpose of this paper is to give an overall description of the penetration of the interplanetary magnetic field (IMF) B(sub y) into the near-Earth plasma sheet. We show that plasma sheet B(sub y) may be generated by the differential shear motion of field lines and enhanced by flux tube compression. The latter mechanism leads to a B(sub y) analogue of the pressure-balance inconsistency as flux tubes move from the far tail toward the Earth. The growth of B(sub y), however, may be limited by the dawn-dusk asymmetry in the shear velocity as a result of plasma sheet tilting. B(sub y) penetration into the plasma sheet implies field-aligned currents flowing between hemispheres. These currents together with the IMF B(sub y) related mantle field-aligned currents effectively shield the lobe from the IMF B(sub y).

Nonlinear ionic transport through microstructured solid electrolytes: homogenization estimates

NASA Astrophysics Data System (ADS)

Curto Sillamoni, Ignacio J.; Idiart, Martín I.

2016-10-01

We consider the transport of multiple ionic species by diffusion and migration through microstructured solid electrolytes in the presence of strong electric fields. The assumed constitutive relations for the constituent phases follow from convex energy and dissipation potentials which guarantee thermodynamic consistency. The effective response is heuristically deduced from a multi-scale convergence analysis of the relevant field equations. The resulting homogenized response involves an effective dissipation potential per species. Each potential is mathematically akin to that of a standard nonlinear heterogeneous conductor. A ‘linear-comparison’ homogenization technique is then used to generate estimates for these nonlinear potentials in terms of available estimates for corresponding linear conductors. By way of example, use is made of the Maxwell-Garnett and effective-medium linear approximations to generate estimates for two-phase systems with power-law dissipation. Explicit formulas are given for some limiting cases. In the case of threshold-type behavior, the estimates exhibit non-analytical dilute limits and seem to be consistent with fields localized in low energy paths.

Multi-turn transmit coil to increase b1 efficiency in current source amplification.

PubMed

Gudino, N; Griswold, M A

2013-04-01

A multi-turn transmit surface coil design was presented to improve B1 efficiency when used with current source amplification. Three different coil designs driven by an on-coil current-mode class-D amplifier with current envelope feedback were tested on the benchtop and through imaging in a 1.5 T scanner. Case temperature of the power field-effect transistor at the amplifier output stage was measured to evaluate heat dissipation for the different current levels and coil configurations. In addition, a lower power rated device was tested to exploit the potential gain in B1 obtained with the multi-turn coil. As shown both on the benchtop and in a 1.5 T scanner, B1 was increased by almost 3-fold without increasing heat dissipation on the power device at the amplifier's output using a multi-turn surface coil. Similar gain was obtained when connecting a lower power rated field-effect transistor to the multi-turn coil. In addition to reduce heat dissipation per B1 in the device, higher B1 per current efficiency allows the use of field-effect transistors with lower current ratings and lower port capacitances, which could improve the overall performance of the on-coil current source transmit system. Copyright © 2013 Wiley Periodicals, Inc.

Construction of Optimal-Path Maps for Homogeneous-Cost-Region Path-Planning Problems

DTIC Science & Technology

1989-09-01

of Artificial Inteligence , 9%,4. 24. Kirkpatrick, S., Gelatt Jr., C. D., and Vecchi, M. P., "Optinization by Sinmulated Ani- nealing", Science, Vol...studied in depth by researchers in such fields as artificial intelligence, robot;cs, and computa- tional geometry. Most methods require homogeneous...the results of the research. 10 U. L SLEVANT RESEARCH A. APPLICABLE CONCEPTS FROM ARTIFICIAL INTELLIGENCE 1. Search Methods One of the central

Nature of low-frequency noise in homogeneous semiconductors

PubMed Central

Palenskis, Vilius; Maknys, Kęstutis

2015-01-01

This report deals with a 1/f noise in homogeneous classical semiconductor samples on the base of silicon. We perform detail calculations of resistance fluctuations of the silicon sample due to both a) the charge carrier number changes due to their capture–emission processes, and b) due to screening effect of those negative charged centers, and show that proportionality of noise level to square mobility appears as a presentation parameter, but not due to mobility fluctuations. The obtained calculation results explain well the observed experimental results of 1/f noise in Si, Ge, GaAs and exclude the mobility fluctuations as the nature of 1/f noise in these materials and their devices. It is also shown how from the experimental 1/f noise results to find the effective number of defects responsible for this noise in the measured frequency range. PMID:26674184

Evidence for the η(b)(2S) and observation of h(b)(1P)→η(b)(1S)γ and h(b)(2P)→η(b)(1S)γ.

PubMed

Mizuk, R; Asner, D M; Bondar, A; Pedlar, T K; Adachi, I; Aihara, H; Arinstein, K; Aulchenko, V; Aushev, T; Aziz, T; Bakich, A M; Bay, A; Belous, K; Bhardwaj, V; Bhuyan, B; Bischofberger, M; Bonvicini, G; Bozek, A; Bračko, M; Brodzicka, J; Browder, T E; Chekelian, V; Chen, A; Chen, P; Cheon, B G; Chilikin, K; Chistov, R; Cho, I-S; Cho, K; Choi, S-K; Choi, Y; Dalseno, J; Danilov, M; Doležal, Z; Drásal, Z; Drutskoy, A; Eidelman, S; Epifanov, D; Fast, J E; Gaur, V; Gabyshev, N; Garmash, A; Golob, B; Haba, J; Hara, T; Hayasaka, K; Hayashii, H; Horii, Y; Hoshi, Y; Hou, W-S; Hsiung, Y B; Hyun, H J; Iijima, T; Ishikawa, A; Itoh, R; Iwabuchi, M; Iwasaki, Y; Iwashita, T; Jaegle, I; Julius, T; Kang, J H; Kapusta, P; Kawasaki, T; Kim, H J; Kim, H O; Kim, J H; Kim, K T; Kim, M J; Kim, Y J; Kinoshita, K; Ko, B R; Koblitz, S; Kodyš, P; Korpar, S; Kouzes, R T; Križan, P; Krokovny, P; Kuhr, T; Kumita, T; Kuzmin, A; Kwon, Y-J; Lange, J S; Lee, S-H; Li, J; Libby, J; Liu, C; Liu, Y; Liu, Z Q; Liventsev, D; Louvot, R; Matvienko, D; McOnie, S; Miyabayashi, K; Miyata, H; Mohanty, G B; Mohapatra, D; Moll, A; Muramatsu, N; Mussa, R; Nakao, M; Natkaniec, Z; Ng, C; Nishida, S; Nishimura, K; Nitoh, O; Nozaki, T; Ohshima, T; Okuno, S; Olsen, S L; Onuki, Y; Pakhlov, P; Pakhlova, G; Park, C W; Park, H; Pestotnik, R; Petrič, M; Piilonen, L E; Poluektov, A; Röhrken, M; Sakai, Y; Sandilya, S; Santel, D; Sanuki, T; Sato, Y; Schneider, O; Schwanda, C; Senyo, K; Seon, O; Sevior, M E; Shapkin, M; Shen, C P; Shibata, T-A; Shiu, J-G; Shwartz, B; Sibidanov, A; Simon, F; Smerkol, P; Sohn, Y-S; Sokolov, A; Solovieva, E; Stanič, S; Starič, M; Sumihama, M; Sumiyoshi, T; Tanida, K; Tatishvili, G; Teramoto, Y; Tikhomirov, I; Trabelsi, K; Tsuboyama, T; Uchida, M; Uehara, S; Uglov, T; Unno, Y; Uno, S; Vanhoefer, P; Varner, G; Varvell, K E; Vinokurova, A; Vorobyev, V; Wang, C H; Wang, M-Z; Wang, P; Wang, X L; Watanabe, M; Watanabe, Y; Williams, K M; Won, E; Yabsley, B D; Yamaoka, J; Yamashita, Y; Yuan, C Z; Zhang, Z P; Zhilich, V

2012-12-07

We report the first evidence for the η(b)(2S) using the h(b)(2P)→η(b)(2S)γ transition and the first observation of the h(b)(1P)→η(b)(1S)γ and h(b)(2P)→η(b)(1S)γ transitions. The mass and width of the η(b)(1S) and η(b)(2S) are measured to be m(η(b)(1S))=(9402.4±1.5±1.8) MeV/c(2), m(η(b)(2S))=(9999.0±3.5(-1.9)(+2.8)) MeV/c(2), and Γ(η(b)(1S))=(10.8(-3.7-2.0)(+4.0+4.5)) MeV. We also update the h(b)(1P) and h(b)(2P) mass measurements. We use a 133.4 fb(-1) data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider.

Mean Field Limits for Interacting Diffusions in a Two-Scale Potential

NASA Astrophysics Data System (ADS)

Gomes, S. N.; Pavliotis, G. A.

2018-06-01

In this paper, we study the combined mean field and homogenization limits for a system of weakly interacting diffusions moving in a two-scale, locally periodic confining potential, of the form considered in Duncan et al. (Brownian motion in an N-scale periodic potential, arXiv:1605.05854, 2016b). We show that, although the mean field and homogenization limits commute for finite times, they do not, in general, commute in the long time limit. In particular, the bifurcation diagrams for the stationary states can be different depending on the order with which we take the two limits. Furthermore, we construct the bifurcation diagram for the stationary McKean-Vlasov equation in a two-scale potential, before passing to the homogenization limit, and we analyze the effect of the multiple local minima in the confining potential on the number and the stability of stationary solutions.

Generating highly uniform electromagnetic field characteristics

DOEpatents

Crow, James T.

1998-01-01

An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

MR fingerprinting with simultaneous B1 estimation.

PubMed

Buonincontri, Guido; Sawiak, Stephen J

2016-10-01

MR fingerprinting (MRF) can be used for quantitative estimation of physical parameters in MRI. Here, we extend the method to incorporate B1 estimation. The acquisition is based on steady state free precession MR fingerprinting with a Cartesian trajectory. To increase the sensitivity to the B1 profile, abrupt changes in flip angle were introduced in the sequence. Slice profile and B1 effects were included in the dictionary and the results from two- and three-dimensional (3D) acquisitions were compared. Acceleration was demonstrated using retrospective undersampling in the phase encode directions of 3D data exploiting redundancy between MRF frames at the edges of k-space. Without B1 estimation, T2 and B1 were inaccurate by more than 20%. Abrupt changes in flip angle improved B1 maps. T1 and T2 values obtained with the new MRF methods agree with classical spin echo measurements and are independent of the B1 field profile. When using view sharing reconstruction, results remained accurate (error <10%) when sampling under 10% of k-space from the 3D data. The methods demonstrated here can successfully measure T1, T2, and B1. Errors due to slice profile can be substantially reduced by including its effect in the dictionary or acquiring data in 3D. Magn Reson Med 76:1127-1135, 2016. © 2015 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2015 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

New developments on the homogenization of Canadian daily temperature data

NASA Astrophysics Data System (ADS)

Vincent, Lucie A.; Wang, Xiaolan L.

2010-05-01

Long-term and homogenized surface air temperature datasets had been prepared for the analysis of climate trends in Canada (Vincent and Gullett 1999). Non-climatic steps due to instruments relocation/changes and changes in observing procedures were identified in the annual mean of the daily maximum and minimum temperatures using a technique based on regression models (Vincent 1998). Monthly adjustments were derived from the regression models and daily adjustments were obtained from an interpolation procedure using the monthly adjustments (Vincent et al. 2002). Recently, new statistical tests have been developed to improve the power of detecting changepoints in climatological data time series. The penalized maximal t (PMT) test (Wang et al. 2007) and the penalized maximal F (PMF) test (Wang 2008b) were developed to take into account the position of each changepoint in order to minimize the effect of unequal and small sample size. A software package RHtestsV3 (Wang and Feng 2009) has also been developed to implement these tests to homogenize climate data series. A recursive procedure was developed to estimate the annual cycle, linear trend, and lag-1 autocorrelation of the base series in tandem, so that the effect of lag-1 autocorrelation is accounted for in the tests. A Quantile Matching (QM) algorithm (Wang 2009) was also developed for adjusting Gaussian daily data so that the empirical distributions of all segments of the detrended series match each other. The RHtestsV3 package was used to prepare a second generation of homogenized temperatures in Canada. Both the PMT test and the PMF test were applied to detect shifts in monthly mean temperature series. Reference series was used in conducting a PMT test. Whenever possible, the main causes of the shifts were retrieved through historical evidence such as the station inspection reports. Finally, the QM algorithm was used to adjust the daily temperature series for the artificial shifts identified from the respective

Homogeneous illusion device exhibiting transformed and shifted scattering effect

NASA Astrophysics Data System (ADS)

Mei, Jin-Shuo; Wu, Qun; Zhang, Kuang; He, Xun-Jun; Wang, Yue

2016-06-01

Based on the theory of transformation optics, a type of homogeneous illusion device exhibiting transformed and shifted scattering effect is proposed in this paper. The constitutive parameters of the proposed device are derived, and full-wave simulations are performed to validate the electromagnetic properties of transformed and shifted scattering effect. The simulation results show that the proposed device not only can visually shift the image of target in two dimensions, but also can visually transform the shape of target. It is expected that such homogeneous illusion device could possess potential applications in military camouflage and other field of electromagnetic engineering.

Homogeneity revisited: analysis of updated precipitation series in Turkey

NASA Astrophysics Data System (ADS)

Bickici Arikan, Bugrayhan; Kahya, Ercan

2018-01-01

Homogeneous time series of meteorological variables are necessary for hydrologic and climate studies. Dependability of historical precipitation data is subjected to keen evaluation prior to every study in water resources, hydrology, and climate change fields. This study aims to characterize the homogeneity of long-term Turkish precipitation data in order to ensure that they can be reliably used. The homogeneity of monthly precipitation data set was tested using the standard normal homogeneity test, Buishand test, Von Neumann ratio test, and Pettitt test at the 5% significance level across Turkey. Our precipitation records including the most updated observations, extracted from 160 meteorological stations, for the periods 1974-2014 were analyzed by all the four homogeneity tests. According to the results of all tests, five out of 160 stations have an inhomogeneity. With regard to our strict confirmation rule, 44 out of 160 stations are said to be inhomogeneous since they failed from at least one of the four tests. The breaks captured by the Buishand and Pettitt tests usually tend to appear in the middle of the precipitation series, whereas the ability of standard normal homogeneity test is in favor of identifying inhomogeneities mostly at the beginning or at the end of the records. Our results showed that 42 out of 44 inhomogeneous stations passed all the four tests after applying a correction procedure based on the double mass curve analysis. Available metadata was used to interpret the detected inhomogeneity.

18 CFR 1b.1 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Definitions. 1b.1 Section 1b.1 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES RULES RELATING TO INVESTIGATIONS § 1b.1 Definitions. For purposes of this part— (a...

18 CFR 1b.1 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Definitions. 1b.1 Section 1b.1 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES RULES RELATING TO INVESTIGATIONS § 1b.1 Definitions. For purposes of this part— (a...

18 CFR 1b.1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Definitions. 1b.1 Section 1b.1 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES RULES RELATING TO INVESTIGATIONS § 1b.1 Definitions. For purposes of this part— (a...

18 CFR 1b.1 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Definitions. 1b.1 Section 1b.1 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES RULES RELATING TO INVESTIGATIONS § 1b.1 Definitions. For purposes of this part— (a...

Presence of B. thailandensis and B. thailandensis expressing B. pseudomallei-like capsular polysaccharide in Thailand, and their associations with serological response to B. pseudomallei.

PubMed

Hantrakun, Viriya; Thaipadungpanit, Janjira; Rongkard, Patpong; Srilohasin, Prapaporn; Amornchai, Premjit; Langla, Sayan; Mukaka, Mavuto; Chantratita, Narisara; Wuthiekanun, Vanaporn; Dance, David A B; Day, Nicholas P J; Peacock, Sharon J; Limmathurotsakul, Direk

2018-01-01

Burkholderia pseudomallei is an environmental Gram-negative bacillus and the cause of melioidosis. B. thailandensis, some strains of which express a B. pseudomallei-like capsular polysaccharide (BTCV), is also commonly found in the environment in Southeast Asia but is considered non-pathogenic. The aim of the study was to determine the distribution of B. thailandensis and its capsular variant in Thailand and investigate whether its presence is associated with a serological response to B. pseudomallei. We evaluated the presence of B. pseudomallei and B. thailandensis in 61 rice fields in Northeast (n = 21), East (n = 19) and Central (n = 21) Thailand. We found BTCV in rice fields in East and Central but not Northeast Thailand. Fourteen fields were culture positive for B. pseudomallei alone, 8 for B. thailandensis alone, 11 for both B. pseudomallei and B. thailandensis, 6 for both B. thailandensis and BTCV, and 5 for B. pseudomallei, B. thailandensis and BTCV. Serological testing using the indirect hemagglutination assay (IHA) of 96 farmers who worked in the study fields demonstrated that farmers who worked in B. pseudomallei-positive fields had higher IHA titers than those who worked in B. pseudomallei-negative fields (median 1:40 [range: <1:10-1:640] vs. <1:10 [range: <1:10-1:320], p = 0.002). In a multivariable ordered logistic regression model, IHA titers were significantly associated with the presence of B. pseudomallei (aOR = 3.7; 95% CI 1.8-7.8, p = 0.001) but were not associated with presence of B. thailandensis (p = 0.32) or BTCV (p = 0.32). One sequence type (696) was identified for the 27 BTCV isolates tested. This is the first report of BTCV in Thailand. The presence of B. pseudomallei and B. thailandensis in the same field was not uncommon. Our findings suggest that IHA positivity of healthy rice farmers in Thailand is associated with the presence of B. pseudomallei in rice fields rather than B. thailandensis or BTCV.

Homogenized electromechanical properties of crystalline and ceramic relaxor ferroelectric 0.58Pb(Mg1/3Nb2/3)O3 0.42PbTiO3

NASA Astrophysics Data System (ADS)

Jayachandran, K. P.; Guedes, J. M.; Rodrigues, H. C.

2007-10-01

A modelling framework that incorporates the peculiarities of microstructural features, such as the spatial correlation of crystallographic orientations and morphological texture in piezoelectrics, is established. The mathematical homogenization theory of a piezoelectric medium is implemented using the finite element method by solving the coupled equilibrium electrical and mechanical fields. The dependence of the domain orientation on the macroscopic electromechanical properties of crystalline as well as polycrystalline ceramic relaxor ferroelectric 0.58Pb(Mg1/3Nb2/3)O3-0.42PbTiO3 (PMN-42% PT) is studied based on this model. The material shows large anisotropy in the piezoelectric coefficient ejK in its crystalline form. The homogenized electromechanical moduli of polycrystalline ceramic also exhibit significantly anisotropic behaviours. An optimum texture at which the piezoceramic exhibits its maximum longitudinal piezoelectric response is identified.

Allele frequencies in the VRN-A1, VRN-B1 and VRN-D1 vernalization response and PPD-B1 and PPD-D1 photoperiod sensitivity genes, and their effects on heading in a diverse set of wheat cultivars (Triticum aestivum L.).

PubMed

Kiss, Tibor; Balla, Krisztina; Veisz, Ottó; Láng, László; Bedő, Zoltán; Griffiths, Simon; Isaac, Peter; Karsai, Ildikó

2014-01-01

Heading of cereals is determined by complex genetic and environmental factors in which genes responsible for vernalization and photoperiod sensitivity play a decisive role. Our aim was to use diagnostic molecular markers to determine the main allele types in VRN - A1 , VRN - B1 , VRN - D1 , PPD - B1 and PPD - D1 in a worldwide wheat collection of 683 genotypes and to investigate the effect of these alleles on heading in the field. The dominant VRN - A1 , VRN - B1 and VRN - D1 alleles were present at a low frequency. The PPD - D1a photoperiod-insensitive allele was carried by 57 % of the cultivars and was most frequent in Asian and European cultivars. The PPD - B1 photoperiod-insensitive allele was carried by 22 % of the genotypes from Asia, America and Europe. Nine versions of the PPD - B1 -insensitive allele were identified based on gene copy number and intercopy structure. The allele compositions in PPD - D1 , PPD - B1 and VRN - D1 significantly influenced heading and together explained 37.5 % of the phenotypic variance. The role of gene model increased to 39.1 % when PPD - B1 intercopy structure was taken into account instead of overall PPD - B1 type (sensitive vs. insensitive). As a single component, PPD - D1 had the most important role (28.0 % of the phenotypic variance), followed by PPD - B1 (12.3 % for PPD - B1 _overall, and 15.1 % for PPD - B1 _intercopy) and VRN - D1 (2.2 %). Significant gene interactions were identified between the marker alleles within PPD - B1 and between VRN - D1 and the two PPD1 genes. The earliest heading genotypes were those with the photoperiod-insensitive allele in PPD - D1 and PPD - B1 , and with the spring allele for VRN - D1 and the winter alleles for VRN - A1 and VRN - B1 . This combination could only be detected in genotypes from Southern Europe and Asia. Late-heading genotypes had the sensitivity alleles for both PPD1 genes, regardless of the allelic composition of the VRN1 genes. There was a 10-day difference in

Generating highly uniform electromagnetic field characteristics

DOEpatents

Crow, James Terry

1998-01-01

An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

Generating highly uniform electromagnetic field characteristics

DOEpatents

Crow, J.T.

1998-05-05

An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 55 figs.

Generating highly uniform electromagnetic field characteristics

DOEpatents

Crow, James T.

1997-01-01

An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially cancelling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

Political homogeneity can nurture threats to research validity.

PubMed

Chambers, John R; Schlenker, Barry R

2015-01-01

Political homogeneity within a scientific field nurtures threats to the validity of many research conclusions by allowing ideologically compatible values to influence interpretations, by minimizing skepticism, and by creating premature consensus. Although validity threats can crop in any research, the usual corrective activities in science are more likely to be minimized and delayed.

Geometrical Design of a Scalable Overlapping Planar Spiral Coil Array to Generate a Homogeneous Magnetic Field.

PubMed

Jow, Uei-Ming; Ghovanloo, Maysam

2012-12-21

We present a design methodology for an overlapping hexagonal planar spiral coil (hex-PSC) array, optimized for creation of a homogenous magnetic field for wireless power transmission to randomly moving objects. The modular hex-PSC array has been implemented in the form of three parallel conductive layers, for which an iterative optimization procedure defines the PSC geometries. Since the overlapping hex-PSCs in different layers have different characteristics, the worst case coil-coupling condition should be designed to provide the maximum power transfer efficiency (PTE) in order to minimize the spatial received power fluctuations. In the worst case, the transmitter (Tx) hex-PSC is overlapped by six PSCs and surrounded by six other adjacent PSCs. Using a receiver (Rx) coil, 20 mm in radius, at the coupling distance of 78 mm and maximum lateral misalignment of 49.1 mm (1/√3 of the PSC radius) we can receive power at a PTE of 19.6% from the worst case PSC. Furthermore, we have studied the effects of Rx coil tilting and concluded that the PTE degrades significantly when θ > 60°. Solutions are: 1) activating two adjacent overlapping hex-PSCs simultaneously with out-of-phase excitations to create horizontal magnetic flux and 2) inclusion of a small energy storage element in the Rx module to maintain power in the worst case scenarios. In order to verify the proposed design methodology, we have developed the EnerCage system, which aims to power up biological instruments attached to or implanted in freely behaving small animal subjects' bodies in long-term electrophysiology experiments within large experimental arenas.

Mixing Dynamics Induced by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Mazuruk, Konstantin; Rose, M. Franklin (Technical Monitor)

2001-01-01

Microstructural and compositional homogeneity in metals and alloys can only be achieved if the initial melt is homogeneous prior to the onset of solidification processing. Naturally induced convection may initially facilitate this requirement but upon the onset of solidification significant compositional variations generally arise leading to undesired segregation. Application of alternating magnetic fields to promote a uniform bulk liquid concentration during solidification processing has been suggested. To investigate such possibilities an initial study of using traveling magnetic fields (TMF) to promote melt homogenization is reported in this work. Theoretically, the effect of TMF-induced convection on mixing phenomena is studied in the laminar regime of flow. Experimentally, with and without applied fields, both 1) mixing dynamics by optically monitoring the spreading of an initially localized dye in transparent fluids and, 2) compositional variations in metal alloys have been investigated.

Estimating B1+ in the breast at 7 T using a generic template.

PubMed

van Rijssel, Michael J; Pluim, Josien P W; Luijten, Peter R; Gilhuijs, Kenneth G A; Raaijmakers, Alexander J E; Klomp, Dennis W J

2018-05-01

Dynamic contrast-enhanced MRI is the workhorse of breast MRI, where the diagnosis of lesions is largely based on the enhancement curve shape. However, this curve shape is biased by RF transmit (B 1 + ) field inhomogeneities. B 1 + field information is required in order to correct these. The use of a generic, coil-specific B 1 + template is proposed and tested. Finite-difference time-domain simulations for B 1 + were performed for healthy female volunteers with a wide range of breast anatomies. A generic B 1 + template was constructed by averaging simulations based on four volunteers. Three-dimensional B 1 + maps were acquired in 15 other volunteers. Root mean square error (RMSE) metrics were calculated between individual simulations and the template, and between individual measurements and the template. The agreement between the proposed template approach and a B 1 + mapping method was compared against the agreement between acquisition and reacquisition using the same mapping protocol. RMSE values (% of nominal flip angle) comparing individual simulations with the template were in the range 2.00-4.01%, with mean 2.68%. RMSE values comparing individual measurements with the template were in the range8.1-16%, with mean 11.7%. The agreement between the proposed template approach and a B 1 + mapping method was only slightly worse than the agreement between two consecutive acquisitions using the same mapping protocol in one volunteer: the range of agreement increased from ±16% of the nominal angle for repeated measurement to ±22% for the B 1 + template. With local RF transmit coils, intersubject differences in B 1 + fields of the breast are comparable to the accuracy of B 1 + mapping methods, even at 7 T. Consequently, a single generic B 1 + template suits subjects over a wide range of breast anatomies, eliminating the need for a time-consuming B 1 + mapping protocol. © 2018 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

Estimating B 1 + in the breast at 7 T using a generic template

PubMed Central

Pluim, Josien P. W.; Luijten, Peter R.; Gilhuijs, Kenneth G. A.; Raaijmakers, Alexander J. E.; Klomp, Dennis W. J.

2018-01-01

Dynamic contrast‐enhanced MRI is the workhorse of breast MRI, where the diagnosis of lesions is largely based on the enhancement curve shape. However, this curve shape is biased by RF transmit (B 1 +) field inhomogeneities. B 1 + field information is required in order to correct these. The use of a generic, coil‐specific B 1 + template is proposed and tested. Finite‐difference time‐domain simulations for B 1 + were performed for healthy female volunteers with a wide range of breast anatomies. A generic B 1 + template was constructed by averaging simulations based on four volunteers. Three‐dimensional B 1 + maps were acquired in 15 other volunteers. Root mean square error (RMSE) metrics were calculated between individual simulations and the template, and between individual measurements and the template. The agreement between the proposed template approach and a B 1 + mapping method was compared against the agreement between acquisition and reacquisition using the same mapping protocol. RMSE values (% of nominal flip angle) comparing individual simulations with the template were in the range 2.00‐4.01%, with mean 2.68%. RMSE values comparing individual measurements with the template were in the range8.1‐16%, with mean 11.7%. The agreement between the proposed template approach and a B 1 + mapping method was only slightly worse than the agreement between two consecutive acquisitions using the same mapping protocol in one volunteer: the range of agreement increased from ±16% of the nominal angle for repeated measurement to ±22% for the B 1 + template. With local RF transmit coils, intersubject differences in B 1 + fields of the breast are comparable to the accuracy of B 1 + mapping methods, even at 7 T. Consequently, a single generic B 1 + template suits subjects over a wide range of breast anatomies, eliminating the need for a time‐consuming B 1 + mapping protocol. PMID:29570887

Homogenization of Mammalian Cells.

PubMed

de Araújo, Mariana E G; Lamberti, Giorgia; Huber, Lukas A

2015-11-02

Homogenization is the name given to the methodological steps necessary for releasing organelles and other cellular constituents as a free suspension of intact individual components. Most homogenization procedures used for mammalian cells (e.g., cavitation pump and Dounce homogenizer) rely on mechanical force to break the plasma membrane and may be supplemented with osmotic or temperature alterations to facilitate membrane disruption. In this protocol, we describe a syringe-based homogenization method that does not require specialized equipment, is easy to handle, and gives reproducible results. The method may be adapted for cells that require hypotonic shock before homogenization. We routinely use it as part of our workflow to isolate endocytic organelles from mammalian cells. © 2015 Cold Spring Harbor Laboratory Press.

New Methods of Low-Field Magnetic Resonance Imaging for Application to Traumatic Brain Injury

DTIC Science & Technology

2015-02-15

attempt to reduce coupling whilst maintaining B1 homogeneity. Shielding at the ends of the reso- nator prevents high electric fields at the capacitors...penetrating the imaging volume, important because PRF-absorbed ~ E2. Slits in the shielding prevent the formation of closed loops that couple to 19...2, pp. 789–794, May 2007. [23] P. A. Rashid, A. Whitehurst, N. Lawson, and P. M. W. Bath, “ Plasma nitric oxide (ni- trate/nitrite) levels in acute

Homogeneous Biosensing Based on Magnetic Particle Labels

PubMed Central

Schrittwieser, Stefan; Pelaz, Beatriz; Parak, Wolfgang J.; Lentijo-Mozo, Sergio; Soulantica, Katerina; Dieckhoff, Jan; Ludwig, Frank; Guenther, Annegret; Tschöpe, Andreas; Schotter, Joerg

2016-01-01

The growing availability of biomarker panels for molecular diagnostics is leading to an increasing need for fast and sensitive biosensing technologies that are applicable to point-of-care testing. In that regard, homogeneous measurement principles are especially relevant as they usually do not require extensive sample preparation procedures, thus reducing the total analysis time and maximizing ease-of-use. In this review, we focus on homogeneous biosensors for the in vitro detection of biomarkers. Within this broad range of biosensors, we concentrate on methods that apply magnetic particle labels. The advantage of such methods lies in the added possibility to manipulate the particle labels by applied magnetic fields, which can be exploited, for example, to decrease incubation times or to enhance the signal-to-noise-ratio of the measurement signal by applying frequency-selective detection. In our review, we discriminate the corresponding methods based on the nature of the acquired measurement signal, which can either be based on magnetic or optical detection. The underlying measurement principles of the different techniques are discussed, and biosensing examples for all techniques are reported, thereby demonstrating the broad applicability of homogeneous in vitro biosensing based on magnetic particle label actuation. PMID:27275824

NMR, MRI, and spectroscopic MRI in inhomogeneous fields

DOEpatents

Demas, Vasiliki; Pines, Alexander; Martin, Rachel W; Franck, John; Reimer, Jeffrey A

2013-12-24

A method for locally creating effectively homogeneous or "clean" magnetic field gradients (of high uniformity) for imaging (with NMR, MRI, or spectroscopic MRI) both in in-situ and ex-situ systems with high degrees of inhomogeneous field strength. THe method of imaging comprises: a) providing a functional approximation of an inhomogeneous static magnetic field strength B.sub.0({right arrow over (r)}) at a spatial position {right arrow over (r)}; b) providing a temporal functional approximation of {right arrow over (G)}.sub.shim(t) with i basis functions and j variables for each basis function, resulting in v.sub.ij variables; c) providing a measured value .OMEGA., which is an temporally accumulated dephasing due to the inhomogeneities of B.sub.0({right arrow over(r)}); and d) minimizing a difference in the local dephasing angle .phi.({right arrow over (r)},t)=.gamma..intg..sub.0.sup.t{square root over (|{right arrow over (B)}.sub.1({right arrow over (r)},t')|.sup.2+({right arrow over (r)}{right arrow over (G)}.sub.shimG.sub.shim(t')+.parallel.{right arrow over (B)}.sub.0({right arrow over (r)}).parallel..DELTA..omega.({right arrow over (r)},t'/.gamma/).sup.2)}dt'-.OMEGA. by varying the v.sub.ij variables to form a set of minimized v.sub.ij variables. The method requires calibration of the static fields prior to minimization, but may thereafter be implemented without such calibration, may be used in open or closed systems, and potentially portable systems.

Homogeneous ice nucleation from aqueous inorganic/organic particles representative of biomass burning: water activity, freezing temperatures, nucleation rates.

PubMed

Knopf, Daniel A; Rigg, Yannick J

2011-02-10

Homogeneous ice nucleation plays an important role in the formation of cirrus clouds with subsequent effects on the global radiative budget. Here we report on homogeneous ice nucleation temperatures and corresponding nucleation rate coefficients of aqueous droplets serving as surrogates of biomass burning aerosol. Micrometer-sized (NH(4))(2)SO(4)/levoglucosan droplets with mass ratios of 10:1, 1:1, 1:5, and 1:10 and aqueous multicomponent organic droplets with and without (NH(4))(2)SO(4) under typical tropospheric temperatures and relative humidities are investigated experimentally using a droplet conditioning and ice nucleation apparatus coupled to an optical microscope with image analysis. Homogeneous freezing was determined as a function of temperature and water activity, a(w), which was set at droplet preparation conditions. The ice nucleation data indicate that minor addition of (NH(4))(2)SO(4) to the aqueous organic droplets renders the temperature dependency of water activity negligible in contrast to the case of aqueous organic solution droplets. The mean homogeneous ice nucleation rate coefficient derived from 8 different aqueous droplet compositions with average diameters of ∼60 μm for temperatures as low as 195 K and a(w) of 0.82-1 is 2.18 × 10(6) cm(-3) s(-1). The experimentally derived freezing temperatures and homogeneous ice nucleation rate coefficients are in agreement with predictions of the water activity-based homogeneous ice nucleation theory when taking predictive uncertainties into account. However, the presented ice nucleation data indicate that the water activity-based homogeneous ice nucleation theory overpredicts the freezing temperatures by up to 3 K and corresponding ice nucleation rate coefficients by up to ∼2 orders of magnitude. A shift of 0.01 in a(w), which is well within the uncertainty of typical field and laboratory relative humidity measurements, brings experimental and predicted freezing temperatures and homogeneous ice

Generating highly uniform electromagnetic field characteristics

DOEpatents

Crow, J.T.

1997-06-24

An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 26 figs.

Generating highly uniform electromagnetic field characteristics

DOEpatents

Crow, J.T.

1998-02-10

An apparatus and method for generating homogeneous electromagnetic fields within a volume is disclosed. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 39 figs.

Deconfinement phase transition in a magnetic field in 2 + 1 dimensions from holographic models

NASA Astrophysics Data System (ADS)

M. Rodrigues, Diego; Capossoli, Eduardo Folco; Boschi-Filho, Henrique

2018-05-01

Using two different models from holographic quantum chromodynamics (QCD) we study the deconfinement phase transition in 2 + 1 dimensions in the presence of a magnetic field. Working in 2 + 1 dimensions lead us to exact solutions on the magnetic field, in contrast with the case of 3 + 1 dimensions where the solutions on the magnetic field are perturbative. As our main result we predict a critical magnetic field Bc where the deconfinement critical temperature vanishes. For weak fields meaning B field indicating an inverse magnetic catalysis (IMC). On the other hand, for strong magnetic fields B >Bc we find that the critical temperature raises with growing field showing a magnetic catalysis (MC). These results for IMC and MC are in agreement with the literature.

Undoped polythiophene field-effect transistors with mobility of 1 cm2 V-1 s-1

NASA Astrophysics Data System (ADS)

Hamadani, B. H.; Gundlach, D. J.; McCulloch, I.; Heeney, M.

2007-12-01

We report on charge transport in organic field-effect transistors based on poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) as the active polymer layer with saturation field-effect mobilities as large as 1cm2V-1s-1. This is achieved by employing Pt instead of the commonly used Au as the contacting electrode and allows for a significant reduction in the metal/polymer contact resistance. The mobility increases as a function of decreasing channel length, consistent with a Poole-Frenkel model of charge transport, and reaches record mobilities of 1cm2V-1s-1 or more at channel lengths on the order of few microns in an undoped solution-processed polymer cast on an oxide gate dielectric.

Ultrafast transient photocarrier dynamics of the bulk-insulating topological insulator B i1.5S b0.5T e1.7S e1.3

NASA Astrophysics Data System (ADS)

Choi, Young Gwan; Zhung, Chan June; Park, Sun-Hee; Park, Joonbum; Kim, Jun Sung; Kim, Seongheun; Park, Jaehun; Lee, J. S.

2018-02-01

Using optical-pump terahertz-probe spectroscopy, we investigated an ultrafast photocarrier relaxation behavior in a B i1.5S b0.5T e1.7S e1.3 (BSTS) single crystal, which is one of the most bulk-insulating topological insulators. Compared to n -type bulk-metallic B i2S e3 , we found that BSTS endows distinct behaviors in its photocarrier dynamics; the relaxation time turns out to be an order of magnitude longer, and the transient conductance spectrum exhibits a nonlinear increase as a function of the pumping power. Also, we observed an abrupt reduction of the photocarrier scattering rate in several picoseconds after the initial photoexcitation. We discuss these intriguing experimental observations based on a bulk-to-surface carrier injection assisted by the built-in electric field near the surface and electron-phonon scattering.

Homogeneous quantum electrodynamic turbulence

NASA Technical Reports Server (NTRS)

Shebalin, John V.

1992-01-01

The electromagnetic field equations and Dirac equations for oppositely charged wave functions are numerically time-integrated using a spatial Fourier method. The numerical approach used, a spectral transform technique, is based on a continuum representation of physical space. The coupled classical field equations contain a dimensionless parameter which sets the strength of the nonlinear interaction (as the parameter increases, interaction volume decreases). For a parameter value of unity, highly nonlinear behavior in the time-evolution of an individual wave function, analogous to ideal fluid turbulence, is observed. In the truncated Fourier representation which is numerically implemented here, the quantum turbulence is homogeneous but anisotropic and manifests itself in the nonlinear evolution of equilibrium modal spatial spectra for the probability density of each particle and also for the electromagnetic energy density. The results show that nonlinearly interacting fermionic wave functions quickly approach a multi-mode, dynamic equilibrium state, and that this state can be determined by numerical means.

Remote sensing of rice fields and sea pollution by SIR-B

NASA Technical Reports Server (NTRS)

Fugono, N.; Furuhama, Y.; Takasugi, T.; Okamoto, K.; Fujita, M.; Yoshikado, S.; Masuko, H.; Shinozuka, T.; Inomata, H.; Shiro, I.

1984-01-01

Sensor calibration, rice fields, and sea pollution are to be investigated with respect to shuttle imaging radar-B (SIR-B). It is planned that the resolution characteristics of the SIR-B be evaluated, the sidelobe characteristics of the SIR-B be investigated, and the relationship between backscatter cross section and image intensity be established. The microwave-scattering characteristics of rice fields are to be studied using SIR-B data. The possibility of classifying crops from SIR-B data is to be explored. The characteristics of the radar image of oil-like surface films under several sea surface conditions are to be determined. The absolute measurement capability of the sea surface scattering cross section is to be estimated using the SIR.

Generation of Bayesian prediction models for OATP-mediated drug-drug interactions based on inhibition screen of OATP1B1, OATP1B1∗15 and OATP1B3.

PubMed

van de Steeg, E; Venhorst, J; Jansen, H T; Nooijen, I H G; DeGroot, J; Wortelboer, H M; Vlaming, M L H

2015-04-05

Human organic anion-transporting polypeptide 1B1 (OATP1B1) and OATP1B3 are important hepatic uptake transporters. Early assessment of OATP1B1/1B3-mediated drug-drug interactions (DDIs) is therefore important for successful drug development. A promising approach for early screening and prediction of DDIs is computational modeling. In this study we aimed to generate a rapid, single Bayesian prediction model for OATP1B1, OATP1B1∗15 and OATP1B3 inhibition. Besides our previously generated HEK-OATP1B1 and HEK-OATP1B1∗15 cells, we now generated and characterized HEK-OATP1B3 cells. Using these cell lines we investigated the inhibitory potential of 640 FDA-approved drugs from a commercial library (10μM) on the uptake of [(3)H]-estradiol-17β-d-glucuronide (1μM) by OATP1B1, OATP1B1∗15, and OATP1B3. Using a cut-off of ⩾60% inhibition, 8% and 7% of the 640 drugs were potent OATP1B1 and OATP1B1∗15 inhibitors, respectively. Only 1% of the tested drugs significantly inhibited OATP1B3, which was not sufficient for Bayesian modeling. Modeling of OATP1B1 and OATP1B1∗15 inhibition revealed that presence of conjugated systems and (hetero)cycles with acceptor/donor atoms in- or outside the ring enhance the probability of a molecule binding these transporters. The overall performance of the model for OATP1B1 and OATP1B1∗15 was ⩾80%, including evaluation with a true external test set. Our Bayesian classification model thus represents a fast, inexpensive and robust means of assessing potential binding of new chemical entities to OATP1B1 and OATP1B1∗15. As such, this model may be used to rank compounds early in the drug development process, helping to avoid adverse effects in a later stage due to inhibition of OATP1B1 and/or OATP1B1∗15. Copyright © 2015 Elsevier B.V. All rights reserved.

Diversifying Homogenous Au(I)-Catalysis through New Reaction Discovery

NASA Astrophysics Data System (ADS)

Motika, Stephen

Homogenous Au(I)-catalysis has become a valuable synthetic tool to activate a host of unsaturated carbon functional groups towards nucleophilic addition. Over the course of the past two decades, many have embarked on new journeys within this field. Notably, the advancements in this field hinge on the development of new ligand systems that impart novel reactivity at the metal. Our group has focused on this area, as we have successfully demonstrated the utility of 1,2,3-triazoles as ligands for gold and a host of other transition metals and Lewis acids. With respect to gold catalysis, these ligands enhance the stability of the metal center, thus inhibiting typical reductive decomposition pathways that have plagued this field. The enhanced stability comes with a price though as higher temperatures can be required. We've addressed this challenge by discovering an interesting synergy between triazole-gold and Lewis acids, allowing us to overcome the lower reactivity of these catalysts. During my time as a graduate student, I have focused heavily on enlisting these catalytic systems for new reaction discovery. In my first experimental chapter, I was able to develop an interesting reaction cascade in which triazole-gold and secondary amine catalysts were used. I started with a well-known gold-catalyzed Claisen rearrangement of propargyl vinyl ether, yielding functionalized allenes. The identical oxidation state between these allenes and synthetically appealing dienals was an impetus to develop a new isomerization strategy. After screening various conditions, I was able to successfully execute this design. Most of the work I have been involved in over the past two years has surrounded a gold-catalyzed hydroboration to yield interesting hetercocycles containing a N-B bond. The N-B bond offers some unique properties as it is isoelectronic to a C-C double bond. Despite the simplicity in this design, it would become apparent early on in this research that mitigating the

CO2-assisted high pressure homogenization: a solvent-free process for polymeric microspheres and drug-polymer composites.

PubMed

Kluge, Johannes; Mazzotti, Marco

2012-10-15

The study explores the enabling role of near-critical CO(2) as a reversible plasticizer in the high pressure homogenization of polymer particles, aiming at their comminution as well as at the formation of drug-polymer composites. First, the effect of near-critical CO(2) on the homogenization of aqueous suspensions of poly lactic-co-glycolic acid (PLGA) was investigated. Applying a pressure drop of 900 bar and up to 150 passes across the homogenizer, it was found that particles processed in the presence of CO(2) were generally of microspherical morphology and at all times significantly smaller than those obtained in the absence of a plasticizer. The smallest particles, exhibiting a median x(50) of 1.3 μm, were obtained by adding a small quantity of ethyl acetate, which exerts on PLGA an additional plasticizing effect during the homogenization step. Further, the study concerns the possibility of forming drug-polymer composites through simultaneous high pressure homogenization of the two relevant solids, and particularly the effect of near-critical CO(2) on this process. Therefore, PLGA was homogenized together with crystalline S-ketoprofen (S-KET), a non-steroidal anti-inflammatory drug, at a drug to polymer ratio of 1:10, a pressure drop of 900 bar and up to 150 passes across the homogenizer. When the process was carried out in the presence of CO(2), an impregnation efficiency of 91% has been reached, corresponding to 8.3 wt.% of S-KET in PLGA; moreover, composite particles were of microspherical morphology and significantly smaller than those obtained in the absence of CO(2). The formation of drug-polymer composites through simultaneous homogenization of the two materials is thus greatly enhanced by the presence of CO(2), which increases the efficiency for both homogenization and impregnation. Copyright © 2012 Elsevier B.V. All rights reserved.

Endophilin B1

PubMed Central

Cheung, Zelda H

2009-01-01

Endophilin B1 is a member of the endophilin family that is localized predominantly to intracellular membranes. Also known as Bax-interacting factor-1 (Bif-1), this protein has been observed to regulate the membrane dynamics of various intracellular compartments, such as the control of mitochondrial morphology and autophagosome formation in fibroblast. Endophilin B1 is expressed in the brain, but its functions in neurons had remained unknown. Recently, we have observed a novel role of endophilin B1 in neurons where it controls the trafficking of TrkA, cognate receptor for the prototypic neurotrophin nerve growth factor (NGF). Knock-down of endophilin B1 expression induces precocious targeting of NGF/TrkA to late endosomes and lysosomes, thereby leading to reduced TrkA levels. This is accompanied by marked attenuation of NGF-induced gene transcription and neurite outgrowth. Our observations suggest that endophilin B1 regulates TrkA level and downstream functions by controlling the movement of TrkA to late endosomes/lysosomes, possibly acting at the level of early endosomes. PMID:19704909

A generalized strategy for designing (19)F/(1)H dual-frequency MRI coil for small animal imaging at 4.7 Tesla.

PubMed

Hu, Lingzhi; Hockett, Frank D; Chen, Junjie; Zhang, Lei; Caruthers, Shelton D; Lanza, Gregory M; Wickline, Samuel A

2011-07-01

To propose and test a universal strategy for building (19) F/(1) H dual-frequency RF coil that permits multiple coil geometries. The feasibility to design (19) F/(1) H dual-frequency RF coil based on coupled resonator model was investigated. A series capacitive matching network enables robust impedance matching for both harmonic oscillating modes of the coupled resonator. Two typical designs of (19) F/(1) H volume coils (birdcage and saddle) at 4.7T were implemented and evaluated with electrical bench test and in vivo (19) F/(1) H dual-nuclei imaging. For various combinations of internal resistances of the sample coil and secondary resonator, numerical solutions for the tunable capacitors to optimize impedance matching were obtained using a root-seeking program. Identical and homogeneous B1 field distribution at (19) F and (1) H frequencies were observed in bench test and phantom image. Finally, in vivo mouse imaging confirmed the sensitivity and homogeneity of the (19) F/(1) H dual-frequency coil design. A generalized strategy for designing (19) F/(1) H dual-frequency coils based on the coupled resonator approach was developed and validated. A unique feature of this design is that it preserves the B1 field homogeneity of the RF coil at both resonant frequencies. Thus it minimizes the susceptibility effect on image co-registration. Copyright © 2011 Wiley-Liss, Inc.

Starch nanoparticles resulting from combination of dry heating under mildly acidic conditions and homogenization.

PubMed

Kim, Jong Hun; Kim, Jiyeon; Park, Eun Young; Kim, Jong-Yea

2017-07-15

To modify starch granular structure, normal maize starch was subjected to dry heating with various amounts of 1.0M HCl (1.2, 1.4 or 1.6mL) and different treatment times (2, 4 or 8h). For all reaction conditions, at least 80% of the starch substance was recovered, and amylose and amylopectin B1 chains were preferentially cleaved. As acidic condition and/or treatment time increased, the treated granules were readily fragmented by homogenization. The treatment appeared to alter short-range crystalline structure (FT-IR), but long-range crystalline structure (XRD) remained intact. Homogenization for 60min fragmented the treated starch granules (subjected to reaction condition of 1.4mL/4h, 1.6mL/2h, and 1.6mL/4h) into nanoparticles consisting of individual platelet-like and spherical particles with diameters less than 100nm. However, the fragmentation caused obvious damage in the long-range crystalline structure of starch nanoparticles, while the short-range chain associations remained relatively intact. Copyright © 2017 Elsevier Ltd. All rights reserved.

76 FR 70046 - Airworthiness Directives; Eurocopter France Model AS350B, B1, B2, B3, BA, C, D, and D1; and...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-10

... Airworthiness Directives; Eurocopter France Model AS350B, B1, B2, B3, BA, C, D, and D1; and AS355E, F, F1, F2, N... France (Eurocopter) Model AS350B, B1, B2, B3, BA, C, D, and D1 helicopters; and Model AS355E, F, F1, F2... (AD 2003- 22-06), for Eurocopter Model AS350B, B1, B2, B3, BA, C, D, and D1; and Model AS355E, F, F1...

Broken Ergodicity in Ideal, Homogeneous, Incompressible Turbulence

NASA Technical Reports Server (NTRS)

Morin, Lee; Shebalin, John; Fu, Terry; Nguyen, Phu; Shum, Victor

2010-01-01

We discuss the statistical mechanics of numerical models of ideal homogeneous, incompressible turbulence and their relevance for dissipative fluids and magnetofluids. These numerical models are based on Fourier series and the relevant statistical theory predicts that Fourier coefficients of fluid velocity and magnetic fields (if present) are zero-mean random variables. However, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation. We explain this phenomena in terms of broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We review the theoretical basis of broken ergodicity, apply it to 2-D and 3-D fluid and magnetohydrodynamic simulations of homogeneous turbulence, and show new results from simulations using GPU (graphical processing unit) computers.

Homogenization theory for designing graded viscoelastic sonic crystals

NASA Astrophysics Data System (ADS)

Qu, Zhao-Liang; Ren, Chun-Yu; Pei, Yong-Mao; Fang, Dai-Ning

2015-02-01

In this paper, we propose a homogenization theory for designing graded viscoelastic sonic crystals (VSCs) which consist of periodic arrays of elastic scatterers embedded in a viscoelastic host material. We extend an elastic homogenization theory to VSC by using the elastic-viscoelastic correspondence principle and propose an analytical effective loss factor of VSC. The results of VSC and the equivalent structure calculated by using the finite element method are in good agreement. According to the relation of the effective loss factor to the filling fraction, a graded VSC plate is easily and quickly designed. Then, the graded VSC may have potential applications in the vibration absorption and noise reduction fields. Project supported by the National Basic Research Program of China (Grant No. 2011CB610301).

Influence of homogenization treatment on physicochemical properties and enzymatic hydrolysis rate of pure cellulose fibers.

PubMed

Jacquet, N; Vanderghem, C; Danthine, S; Blecker, C; Paquot, M

2013-02-01

The aim of this study is to compare the effect of different homogenization treatments on the physicochemical properties and the hydrolysis rate of a pure bleached cellulose. Results obtained show that homogenization treatments improve the enzymatic hydrolysis rate of the cellulose fibers by 25 to 100 %, depending of the homogenization treatment applied. Characterization of the samples showed also that homogenization had an impact on some physicochemical properties of the cellulose. For moderate treatment intensities (pressure below 500 b and degree of homogenization below 25), an increase of water retention values (WRV) that correlated to the increase of the hydrolysis rate was highlighted. Result also showed that the overall crystallinity of the cellulose properties appeared not to be impacted by the homogenization treatment. For higher treatment intensities, homogenized cellulose samples developed a stable tridimentional network that contributes to decrease cellulase mobility and slowdown the hydrolysis process.

Spinorial characterizations of surfaces into three-dimensional homogeneous manifolds

NASA Astrophysics Data System (ADS)

Roth, Julien

2010-06-01

We give spinorial characterizations of isometrically immersed surfaces into three-dimensional homogeneous manifolds with four-dimensional isometry group in terms of the existence of a particular spinor field. This generalizes works by Friedrich for R3 and Morel for S3 and H3. The main argument is the interpretation of the energy-momentum tensor of such a spinor field as the second fundamental form up to a tensor depending on the structure of the ambient space.

Large-scale Organized Magnetic Fields in O, B and A Stars

NASA Astrophysics Data System (ADS)

Mathys, G.

2009-06-01

The status of our current knowledge of magnetic fields in stars of spectral types ranging from early F to O is reviewed. Fields with large-scale organised structure have now been detected and measured throughout this range. These fields are consistent with the oblique rotator model. In early F to late B stars, their occurrence is restricted to the subgroup of the Ap stars, which have the best studied fields among the early-type stars. Presence of fields with more complex topologies in other A and late B stars has been suggested, but is not firmly established. Magnetic fields have not been studied in a sufficient number of OB stars yet so as to establish whether they occur in all or only in some subset of these stars.

An enzyme-free homogenous electrochemical assay for sensitive detection of the plasmid-mediated colistin resistance gene mcr-1.

PubMed

Li, Bo; Chai, Zhixin; Yan, Xiaohui; Liu, Chunchen; Situ, Bo; Zhang, Ye; Pan, Weilun; Luo, Shihua; Liu, Jianhua; Zheng, Lei

2018-05-22

Antibiotic resistance associated with the mcr-1 gene of Gram-negative bacteria, which confers resistance to drugs of last resort and has the potential to spread via plasmids, is one of the most pressing issues facing global health today. Point-of-care testing for the mcr-1 gene is needed to aid in the identification of colistin resistance in the field and to control its horizontal transmission. Here, we report the successful development of an enzyme-free homogenous electrochemical strategy for sensitive detection of the antibiotic resistance gene mcr-1 using the hybridization chain reaction and mcr-1-specific toehold probe. The long double-stranded DNA polymer produced using this strategy could be detected by assessing the diffusion of methylene blue towards the surface of a screen-printed gold electrode. Under optimized conditions, a linear relationship was observed between the variation of peak current and the natural logarithm of the mcr-1 gene concentration in the range of 1 nM to 1 μM with a detection limit of 0.78 nM (S/N = 3). This enzyme-free, isothermal platform is a rapid, portable, disposable, and sensitive method for detection of plasmid-mediated colistin resistance.

Revisiting the temperature dependence of the homogeneous R 1 linewidth in ruby

NASA Astrophysics Data System (ADS)

Riesen, Hans; Szabo, Alex

2010-01-01

Transient spectral-hole-burning studies of the R 1(±3/2) line ( E¯ ( 2E) ← 4A 2(±3/2)) in 20 ppm ruby were conducted between 2.4 and 50 K in a low magnetic field ( B|| = 9.15 mT) and the results were supplemented with the original data of McCumber and Sturge. A direct one-phonon process, 2A¯←E¯, is the main contribution to the linewidth up to 50 K whereas at higher temperatures two-phonon Raman scattering becomes dominant. The two processes are well described by ΔΓdirect=Γ0/(exp(Δ/kT)-1) and a non-perturbative expression for the electron-phonon interaction developed by Hsu and Skinner. The value of Γ0 = 141 (±4) MHz is in excellent agreement with the result of 142 ± 6 MHz previously obtained for the R 2 line.

Refractive index of B1-xGaxN semiconductors

NASA Astrophysics Data System (ADS)

Vyas, P. S.; Baria, J. K.; Jivani, A. R.; Gajjar, P. N.; Jani, A. R.

2013-06-01

A theoretical procedure is presented for the study of refractive index of ternary alloy B1-xGaxN. The calculations based on the pseudopotential formalism in which local potential coupled with the virtual crystal approximation (VCA) is applied to evaluate energy band gap at point X on the Jones-zone face, refractive index for the entire range of the alloy composition x of the ternary alloy B1-xGaxN. To include exchange and correlation effects, local field correction function due to Nagy is employed. Our results for parent compounds are compared to experiment and other available theoretical findings and showed generally good agreement. During present study it is found that the refractive index of the ternary alloy B1-xGaxN has minimum value at gallium concentration x = 0.4.

The effect of organic anion-transporting polypeptides 1B1, 1B3 and 2B1 on the antitumor activity of flavopiridol in breast cancer cells.

PubMed

Brenner, Stefan; Riha, Juliane; Giessrigl, Benedikt; Thalhammer, Theresia; Grusch, Michael; Krupitza, Georg; Stieger, Bruno; Jäger, Walter

2015-01-01

The contribution of organic anion transporting polypeptides (OATPs) to the cellular uptake of flavopiridol was investigated in OATP1B1-, OATP1B3- and OATP2B1-expressing Chinese hamster ovary (CHO) cells. Uptake of flavopiridol into these cells showed typical Michaelis-Menten kinetics with much higher transport capacity for OATP1B3 compared to OATP1B1 and OATP2B1 (Vmax/Km, 33.9 vs. 8.84 and 2.41 µl/mg/min, respectively). The predominant role of OATPs was further supported by a dramatic inhibition of flavopiridol uptake in the presence of the OATP substrate rifampicin. Uptake of flavopiridol by OATPs also seems to be an important determinant in breast cancer cells. The much higher mRNA level for OATP1B1 found in wild-type compared to ZR-75-1 OATP1B1 knockdown cells correlated with higher flavopiridol initial uptake leading to 4.6-fold decreased IC50 values in the cytotoxicity assay (IC50, 1.45 vs. 6.64 µM). Cell cycle profile also showed a clear incidence for a stronger cell cycle arrest in the G2/M phase for ZR-75-1 wild-type cells compared to OATP1B1 knockdown cells, further indicating an active uptake via OATP1B1. In conclusion, our results revealed OATP1B1, OATP1B3 and OATP2B1 as uptake transporters for flavopiridol in cancer cells, which may also apply in patients during cancer therapy.

Zebrafish Lmx1b.1 and Lmx1b.2 are required for maintenance of the isthmic organizer.

PubMed

O'Hara, F Patrick; Beck, Ernestine; Barr, Lauren K; Wong, Lily L; Kessler, Daniel S; Riddle, Robert D

2005-07-01

The mesencephalic and metencephalic region (MMR) of the vertebrate central nervous system develops in response to signals produced by the isthmic organizer (IsO). We have previously reported that the LIM homeobox transcription factor Lmx1b is expressed within the chick IsO, where it is sufficient to maintain expression of the secreted factor wnt1. In this paper, we show that zebrafish express two Lmx1b orthologs, lmx1b.1 and lmx1b.2, in the rostral IsO, and demonstrate that these genes are necessary for key aspects of MMR development. Simultaneous knockdown of Lmx1b.1 and Lmx1b.2 using morpholino antisense oligos results in a loss of wnt1, wnt3a, wnt10b, pax8 and fgf8 expression at the IsO, leading ultimately to programmed cell death and the loss of the isthmic constriction and cerebellum. Single morpholino knockdown of either Lmx1b.1 or Lmx1b.2 has no discernible effect on MMR development. Maintenance of lmx1b.1 and lmx1b.2 expression at the isthmus requires the function of no isthmus/pax2.1, as well as Fgf signaling. Transient misexpression of Lmx1b.1 or Lmx1b.2 during early MMR development induces ectopic wnt1 and fgf8 expression in the MMR, as well as throughout much of the embryo. We propose that Lmx1b.1- and Lmx1b.2-mediated regulation of wnt1, wnt3a, wnt10b, pax8 and fgf8 maintains cell survival in the isthmocerebellar region.

Nuclear factor κB inhibitor BAY 11-7082 suppresses oxidative stress induced by endothelin-1 (ET-1) in rat kidney.

PubMed

Kowalczyk, Agata; Kołodziejczyk, Michał; Gorąca, Anna

2015-12-31

The aim of the study was to evaluate the effect of BAY 11-7082, an NF-κB inhibitor, on basal and ET-1-induced production of reactive oxygen species (ROS), TNF-α and p65 protein in rat kidney. The experimental animals were divided into five groups (n=7) receiving: 1) saline (control); 2 and 3) ET-1 in a dose of 3 μg/kg body weight (b.w.) or 12.5 μg/kg b.w.; 4) BAY 11-7082 (10 mg/kg b.w.); 5) BAY 11-7082 (10 mg/kg b.w.) and ET-1 (12.5 μg/kg b.w.), respectively. In kidney homogenates the concentration of thiobarbituric acid reactive substances (TBARS), H2O2, TNF-α, p65 protein and GSH/GSSG ratio were determined. ET-1 resulted in a dose-dependent increase in TBARS and hydrogen peroxide (H2O2) levels, and a decrease in GSH/GSSG ratio when compared to the controls. BAY 11-7082 administered 1 h before ET-1 administration at a dose of 12.5 μg/kg resulted in a decrease (P<0.001) in TBARS and H2O2 levels and an increase (P<0.001) in GSH/GSSG ratio compared to the ET-1 groups. The level of TNF-α was increased (P<0.001) in the presence of ET-1, while BAY 11-7082 reduced the TNF-α level (P<0.001). The rats receiving BAY 11-7082 showed a decrease in NF-κB p65 protein level in the nuclear fraction and an increase in the cytoplasmic fraction. The results suggest that BAY 11-7082 plays a protective role against ET-1 induced oxidative stress in kidney tissue. These actions of BAY 11-7082 may result from reduced activity of NF-κB signaling pathways. Inhibition of the NF-κB pathway may be a promising strategy for preventing the progression of kidney damage.

Homogenization of tissues via picosecond-infrared laser (PIRL) ablation: Giving a closer view on the in-vivo composition of protein species as compared to mechanical homogenization.

PubMed

Kwiatkowski, M; Wurlitzer, M; Krutilin, A; Kiani, P; Nimer, R; Omidi, M; Mannaa, A; Bussmann, T; Bartkowiak, K; Kruber, S; Uschold, S; Steffen, P; Lübberstedt, J; Küpker, N; Petersen, H; Knecht, R; Hansen, N O; Zarrine-Afsar, A; Robertson, W D; Miller, R J D; Schlüter, H

2016-02-16

Posttranslational modifications and proteolytic processing regulate almost all physiological processes. Dysregulation can potentially result in pathologic protein species causing diseases. Thus, tissue species proteomes of diseased individuals provide diagnostic information. Since the composition of tissue proteomes can rapidly change during tissue homogenization by the action of enzymes released from their compartments, disease specific protein species patterns can vanish. Recently, we described a novel, ultrafast and soft method for cold vaporization of tissue via desorption by impulsive vibrational excitation (DIVE) using a picosecond-infrared-laser (PIRL). Given that DIVE extraction may provide improved access to the original composition of protein species in tissues, we compared the proteome composition of tissue protein homogenates after DIVE homogenization with conventional homogenizations. A higher number of intact protein species was observed in DIVE homogenates. Due to the ultrafast transfer of proteins from tissues via gas phase into frozen condensates of the aerosols, intact protein species were exposed to a lesser extent to enzymatic degradation reactions compared with conventional protein extraction. In addition, total yield of the number of proteins is higher in DIVE homogenates, because they are very homogenous and contain almost no insoluble particles, allowing direct analysis with subsequent analytical methods without the necessity of centrifugation. Enzymatic protein modifications during tissue homogenization are responsible for changes of the in-vivo protein species composition. Cold vaporization of tissues by PIRL-DIVE is comparable with taking a snapshot at the time of the laser irradiation of the dynamic changes that occur continuously under in-vivo conditions. At that time point all biomolecules are transferred into an aerosol, which is immediately frozen. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Enhancement of the in-field Jc of MgB2 via SiCl4 doping

NASA Astrophysics Data System (ADS)

Wang, Xiao-Lin; Dou, S. X.; Hossain, M. S. A.; Cheng, Z. X.; Liao, X. Z.; Ghorbani, S. R.; Yao, Q. W.; Kim, J. H.; Silver, T.

2010-06-01

We present the following results. (1) We introduce a doping source for MgB2 , liquid SiCl4 , which is free of C, to significantly enhance the irreversibility field (Hirr) , the upper critical field (Hc2) , and the critical current density (Jc) with a little reduction in the critical temperature (Tc) . (2) Although Si can not be incorporated into the crystal lattice, a significant reduction in the a -axis lattice parameter was found, to the same extent as for carbon doping. (3) Based on the first-principles calculation, it is found that it is reliable to estimate the C concentration just from the reduction in the a -lattice parameter for C-doped MgB2 polycrystalline samples that are prepared at high sintering temperatures, but not for those prepared at low sintering temperatures. Strain effects and magnesium deficiency might be reasons for the a -lattice reduction in non-C or some of the C-added MgB2 samples. (4) The SiCl4 -doped MgB2 shows much higher Jc with superior field dependence above 20 K compared to undoped MgB2 and MgB2 doped with various carbon sources. (5) We introduce a parameter, RHH (Hc2/Hirr) , which can clearly reflect the degree of flux-pinning enhancement, providing us with guidance for further enhancing Jc . (6) It was found that spatial variation in the charge-carrier mean free path is responsible for the flux-pinning mechanism in the SiCl4 treated MgB2 with large in-field Jc .

Directed Thermal Diffusions through Metamaterial Source Illusion with Homogeneous Natural Media

PubMed Central

Xu, Guoqiang; Zhang, Haochun; Jin, Liang

2018-01-01

Owing to the utilization of transformation optics, many significant research and development achievements have expanded the applications of illusion devices into thermal fields. However, most of the current studies on relevant thermal illusions used to reshape the thermal fields are dependent of certain pre-designed geometric profiles with complicated conductivity configurations. In this paper, we propose a methodology for designing a new class of thermal source illusion devices for achieving directed thermal diffusions with natural homogeneous media. The employments of the space rotations in the linear transformation processes allow the directed thermal diffusions to be independent of the geometric profiles, and the utilization of natural homogeneous media improve the feasibility. Four schemes, with fewer types of homogeneous media filling the functional regions, are demonstrated in transient states. The expected performances are observed in each scheme. The related performance are analyzed by comparing the thermal distribution characteristics and the illusion effectiveness on the measured lines. The findings obtained in this paper see applications in the development of directed diffusions with minimal thermal loss, used in novel “multi-beam” thermal generation, thermal lenses, solar receivers, and waveguide. PMID:29671833

RF sheaths for arbitrary B field angles

NASA Astrophysics Data System (ADS)

D'Ippolito, Daniel; Myra, James

2014-10-01

RF sheaths occur in tokamaks when ICRF waves encounter conducting boundaries and accelerate electrons out of the plasma. Sheath effects reduce the efficiency of ICRF heating, cause RF-specific impurity influxes from the edge plasma, and increase the plasma-facing component damage. The rf sheath potential is sensitive to the angle between the B field and the wall, the ion mobility and the ion magnetization. Here, we obtain a numerical solution of the non-neutral rf sheath and magnetic pre-sheath equations (for arbitrary values of these parameters) and attempt to infer the parametric dependences of the Child-Langmuir law. This extends previous work on the magnetized, immobile ion regime. An important question is how the rf sheath voltage distributes itself between sheath and pre-sheath for various B field angles. This will show how generally previous estimates of the rf sheath voltage and capacitance were reasonable, and to improve the RF sheath BC. Work supported by US DOE grants DE-FC02-05ER54823 and DE-FG02-97ER54392.

SQUID readout and ultra-low magnetic fields for Gravity Probe-B (GP-B)

NASA Technical Reports Server (NTRS)

Lockhart, James M.

1986-01-01

The superconducting readout system to be used for resolving 0.001 arcsec changes in the gyroscope spin direction in the Relativity Gyroscope (GP-B) experiment is described. This system couples the London magnetic moment flux of the spinning gyro to a low noise superconducting quantum interference device (SQUID) detector. Resolution limits and noise performance of the detection system are discussed, and improvements obtained and expected with advanced SQUIDs are presented. Also described is the novel use of superconducting magnetic shielding techniques to obtain a 250 dB attenuation of the earth's magnetic field at the location of the gyroscopes. In this approach, expanded superconducting foil shields are coupled with fixed cylindrical superconducting shields and special geometric considerations to obtain the extremely high attenuation factor required. With these shielding techniques, it appears that the 0.5-Gauss earth field (which appears to the gyroscopes as an ac field at the satellite roll rate) can be reduced to the 10 to the -13th G level required by the experiment. Recent results concerning improvements in the performance of the superconducting foil techniques obtained with the use of a new computer-controlled cooling system are presented.

Idiopathic paraproteinaemia V. Expression of Igh1 and Igh5 allotypes within the homogeneous immunoglobulins of ageing (C57BL/LiARij X CBA/BrARij)F1 mouse.

PubMed Central

Radl, J; Vieveen, M H; van den Akker, T W; Benner, R; Haaijman, J J; Zurcher, C

1985-01-01

The role of genetic factors linked to the immunoglobulin loci and the development of idiopathic paraproteinaemia (IP)--a benign B-cell proliferative disorder--was investigated in F1 hybrid mice of low (CBA/BrARij) and high (C57BL/LiARij) IP frequency strains. Igh1 and Igh5 allotypes were used as markers for the (parental type) origin of homogeneous immunoglobulins (H-Ig) which appeared in the sera of the F1 mice with ageing. The frequencies of H-Ig in the F1 mice were intermediate with those of the parental strains. The isotype distribution of the H-Ig was 27%, 24%, 12%, 12%, 11%, 10%, 3% and 1% for IgG2a, IgM, IgG1, IgG3, IgG2b, IgD, IgA and IgE, respectively. H-Ig of the IgG2 subclass carried the Igh1b (C57BL) allotype in 98% and the Igh1a (CBA) allotype in 2% cases. Of the IgD H-Ig, 70% carried the Igh5b and 30% the Igh5a determinant. The Igh1 allotype distribution in the bone marrow and spleen plasma cells showed a large variation in the Igh1a/Igh1b ratio among old individual mice and often also between bone marrow and spleen within a single animal with or without a H-Ig component. The categorization of the paraproteinaemias on the basis of their origin showed that 10% of the H-Ig were the result of a transient monoclonal B-cell proliferation; multiple myeloma or lymphoma was found to be responsible for about 1% of the paraproteinaemias; H-Ig fulfilling the criteria for IP were detected in about 42% of cases. The origin of the remaining old age paraproteinaemias could not be determined. These data indicate that the F1 mice develop monoclonal proliferative disorders in a manner more similar to the C57BL than to the CBA parental strain. The allotype associated genetic material from the parental C57BL strain was shown to be mainly responsible for the development of IP in ageing F1 mice. Images Fig. 4 PMID:3936651

A new gradient shimming method based on undistorted field map of B0 inhomogeneity.

PubMed

Bao, Qingjia; Chen, Fang; Chen, Li; Song, Kan; Liu, Zao; Liu, Chaoyang

2016-04-01

Most existing gradient shimming methods for NMR spectrometers estimate field maps that resolve B0 inhomogeneity spatially from dual gradient-echo (GRE) images acquired at different echo times. However, the distortions induced by B0 inhomogeneity that always exists in the GRE images can result in estimated field maps that are distorted in both geometry and intensity, leading to inaccurate shimming. This work proposes a new gradient shimming method based on undistorted field map of B0 inhomogeneity obtained by a more accurate field map estimation technique. Compared to the traditional field map estimation method, this new method exploits both the positive and negative polarities of the frequency encoded gradients to eliminate the distortions caused by B0 inhomogeneity in the field map. Next, the corresponding automatic post-data procedure is introduced to obtain undistorted B0 field map based on knowledge of the invariant characteristics of the B0 inhomogeneity and the variant polarity of the encoded gradient. The experimental results on both simulated and real gradient shimming tests demonstrate the high performance of this new method. Copyright © 2015 Elsevier Inc. All rights reserved.

Preparation and characterization of paclitaxel nanosuspension using novel emulsification method by combining high speed homogenizer and high pressure homogenization.

PubMed

Li, Yong; Zhao, Xiuhua; Zu, Yuangang; Zhang, Yin

2015-07-25

The aim of this study was to develop an alternative, more bio-available, better tolerated paclitaxel nanosuspension (PTXNS) for intravenous injection in comparison with commercially available Taxol(®) formulation. In this study, PTXNS was prepared by emulsification method through combination of high speed homogenizer and high pressure homogenization, followed by lyophilization process for intravenous administration. The main production parameters including volume ratio of organic phase in water and organic phase (Vo:Vw+o), concentration of PTX, content of PTX and emulsification time (Et), homogenization pressure (HP) and passes (Ps) for high pressure homogenization were optimized and their effects on mean particle size (MPS) and particle size distribution (PSD) of PTXNS were investigated. The characteristics of PTXNS, such as, surface morphology, physical status of paclitaxel (PTX) in PTXNS, redispersibility of PTXNS in purified water, in vitro dissolution study and bioavailability in vivo were all investigated. The PTXNS obtained under optimum conditions had an MPS of 186.8 nm and a zeta potential (ZP) of -6.87 mV. The PTX content in PTXNS was approximately 3.42%. Moreover, the residual amount of chloroform was lower than the International Conference on Harmonization limit (60 ppm) for solvents. The dissolution study indicated PTXNS had merits including effect to fast at the side of raw PTX and sustained-dissolution character compared with Taxol(®) formulation. Moreover, the bioavailability of PTXNS increased 14.38 and 3.51 times respectively compared with raw PTX and Taxol(®) formulation. Copyright © 2015 Elsevier B.V. All rights reserved.

Duality linking standard and tachyon scalar field cosmologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avelino, P. P.; Bazeia, D.; Losano, L.

2010-09-15

In this work we investigate the duality linking standard and tachyon scalar field homogeneous and isotropic cosmologies in N+1 dimensions. We determine the transformation between standard and tachyon scalar fields and between their associated potentials, corresponding to the same background evolution. We show that, in general, the duality is broken at a perturbative level, when deviations from a homogeneous and isotropic background are taken into account. However, we find that for slow-rolling fields the duality is still preserved at a linear level. We illustrate our results with specific examples of cosmological relevance, where the correspondence between scalar and tachyon scalarmore » field models can be calculated explicitly.« less

Tunable SERS signals of Rhodamine B molecules on Fe3O4@Au nanocomposite substrates controlled by magnetic field

NASA Astrophysics Data System (ADS)

Song, Hao; Fang, Rui Yang; Li, Ling

2018-02-01

In this work, we experimentally synthesized the Fe3O4@Au nanocomposites and used them as surface-enhanced Raman scattering (SERS) substrates. The Fe3O4@Au nanocomposites retained the metallic plasmon resonant effect and possessed the magnetic field controllable characteristics. The Raman spectra of Rhodamine B (RhB) probe molecules were studied under different external magnetic field. The magnitude of external magnetic field varied from 0 Gs to 700 Gs (1 Gs = 10-4 T) with intervals of 100 Gs. When the magnetic field magnitude increased, the Raman intensity of RhB probe molecules at 1356 cm-1 increased linearly. The slope of the linear fitting curves for the Raman intensity and area were 0.118/Gs and 3.700/Gs. The Raman enhancement could raise up to 7 times for RhB probe molecules when the magnetic field magnitude increased to 700 Gs. After removing the external magnetic field, the Raman peaks returned to its original intensity in several minutes. Under the external magnetic field, the Fe3O4@Au nanocomposites were concentrated, leading to the increase number of SERS "hot spots" and the surface Au density. The results show that the magnetic field controlled Fe3O4@Au nanocomposites can realize the enhanced and controllable SERS effect, which can be used in the reversible optical sensing and bio-medical applications.

Review of high field superconducting magnet development at Oxford Instruments

NASA Astrophysics Data System (ADS)

Brown, F. J.; Kerley, N. W.; Knox, R. B.; Timms, K. W.

1996-02-01

Present commercial development activity for high field superconducting magnets is focused clearly in three directions. The development of solenoid magnets with flux densities in excess of 20 T, the production of highly homogeneous fields at 20 T, and development of large split pair magnets in excess of 12 T. Recent developments in split pair technology allows us to build magnets with useful access, transverse to the field, up to 15 T. Compact solenoid magnets to 20 T have been available commercially for over 3 yr now with a progressive increment in bore size, providing associated engineering challenges. A 20 T solenoid with a clear bore of 52 mm and a homogeneity of 0.1% is now a standard production item. Improving the homogeneity to the 1 ppm level involves re-assessment of critical design parameters and choice of materials. Our development over the last twelve months has culminated in a 20 T solenoid with base homogeneity of 5 ppm over a 10 mm sphere. In order to realise persistent fields in excess of 20 T, requires the priority on development to be switched from engineering and manufacturing towards material development and enhancement. We present the findings and conclusions of our high field development program over the last 3 yr, together with an outline of our requirements and activities in materials and engineering leading to the next step in high field magnet manufacture, using conventional low Tc conductors.

B1 transmit phase gradient coil for single-axis TRASE RF encoding.

PubMed

Deng, Qunli; King, Scott B; Volotovskyy, Vyacheslav; Tomanek, Boguslaw; Sharp, Jonathan C

2013-07-01

TRASE (Transmit Array Spatial Encoding) MRI uses RF transmit phase gradients instead of B0 field gradients for k-space traversal and high-resolution MR image formation. Transmit coil performance is a key determinant of TRASE image quality. The purpose of this work is to design an optimized RF transmit phase gradient array for spatial encoding in a transverse direction (x- or y- axis) for a 0.2T vertical B0 field MRI system, using a single transmitter channel. This requires the generation of two transmit B1 RF fields with uniform amplitude and positive and negative linear phase gradients respectively over the imaging volume. A two-element array consisting of a double Maxwell-type coil and a Helmholtz-type coil was designed using 3D field simulations. The phase gradient polarity is set by the relative phase of the RF signals driving the simultaneously energized elements. Field mapping and 1D TRASE imaging experiments confirmed that the constructed coil produced the fields and operated as designed. A substantially larger imaging volume relative to that obtainable from a non-optimized Maxwell-Helmholtz design was achieved. The Maxwell (sine)-Helmholtz (cosine) approach has proven successful for a horizontal phase gradient coil. A similar approach may be useful for other phase-gradient coil designs. Copyright © 2013 Elsevier Inc. All rights reserved.

Fragile morphotropic phase boundary and phase stability in the near-surface region of the relaxor ferroelectric (1 -x ) Pb (Z n1 /3N b2 /3) O3-x PbTi O3 : [001] field-cooled phase diagrams

NASA Astrophysics Data System (ADS)

Wang, Yaojin; Wang, Ding; Yuan, Guoliang; Ma, He; Xu, Feng; Li, Jiefang; Viehland, D.; Gehring, Peter M.

2016-11-01

We have examined the effects of field cooling on the phase diagram of the relaxor system (1 -x ) Pb (Z n1 /3N b2 /3) O3-x PbTi O3 (PZN-x PT ) for compositions near the morphotropic phase boundary (MPB). High-resolution diffraction measurements using Cu Kα x rays, which probe ≈3 μ m below the crystal surface, were made on field-cooled (FC) single-crystal specimens of PZN-4.5 %PT and PZN-6.5 %PT under electric fields of 1 and 2 kV/cm applied along [001] and combined with previous neutron diffraction data, which probe the entire crystal volume, for FC PZN-8 %PT [Ohwada et al., Phys. Rev. B 67, 094111 (2003), 10.1103/PhysRevB.67.094111]. A comparison to the zero-field-cooled (ZFC) PZN-x PT phase diagram reveals several interesting features: (1) The short-range monoclinic phase observed in the ZFC state on the low-PT side of the MPB is replaced by a monoclinic MA phase; (2) field cooling extends the tetragonal phase to higher temperatures and lower-PT concentrations; (3) the orthorhombic phase near the MPB is replaced by a monoclinic MC phase; (4) the vertical MPB in the ZFC phase diagram bends significantly towards the low-PT side in the FC state. These results demonstrate that both the phase stability and the nature of the MPB in PZN-PT within the near-surface regions are fragile in the presence of electric fields.

SU-F-J-50: Study On the Magnetic Field Effect On the Exradin W1 Plastic Scintillation Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Z; Therriault-Proulx, F; Owens, C

2016-06-15

Purpose: To study the response of the Exradin W1 plastic scintillator detector to a 6 MV photon field in the presence of a strong magnetic field (B). Methods: An Exradin W1 scintillator detector coupled to a SuperMax two-channel electrometer, both manufactured by Standard Imaging, Inc., was first calibrated in a Co-60 beam. The Cerenkov Light Ratio (CLR) was obtained following the procedure recommended by the manufacturer. Subtracting signal in channel 2 multiplied by CLR from the signal in channel 1 should lead to a Cerenkov-free signal. The W1 scintillator was placed in a plastic phantom inside a dipole electromagnet (GMWmore » Associates) that could produce a strong B field, and irradiated using a 6 MV beam from an Elekta Versa HD LINAC. Signals from both channels of the W1 scintillator were acquired as a function of B (0 - 1.5 T). Results: The signals from both channels increased as a function of the B field strength. At 1.5 T, channel 1 increased by 11% compared to the baseline (B=0 T), while channel 2 increased by 22%. Applying the recommended Cerenkov correction led to a 2% difference between dose measurement with and without a magnetic field. The values between B=0.3 T and B=1.5 T remained constant. Conclusion: Signals from the Exradin W1 plastic scintillation detector increased as the B field increased. This increase mainly comes from a change in the amount of Cerenkov light coupled within the optical fiber. Removing the Cerenkov component following the procedure recommended by the manufacturer showed to be an effective way to measure dose accurately in strong magnetic fields. The cause for the residual 2% difference is currently under investigation. We acknowledge research support from Elekta AB.« less

Homogeneous and Heterogeneous (Fex, Cr1-x)(OH)3 Precipitation: Implications for Cr Sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Chong; Zuo, Xiaobing; Cao, B

2016-02-16

The formation of (Fe, Cr)(OH)3 nanoparticles determines the fate of aqueous Cr in many aquatic environments. Using small angle X-ray scattering, precipitation rates of (Fe, Cr)(OH)3 nanoparticles in solution and on quartz were quantified from 0.1 mM Fe(III) solutions containing 0 – 0.25 mM Cr(III) at pH = 3.7 ± 0.2. Concentration ratio of aqueous Cr(III)/Fe(III) controlled the chemical composition (x) of (Fex, Cr1-x)(OH)3 precipitates, solutions’ supersaturation with respect to precipitates, and the surface charge of quartz. Therefore, aqueous Cr(III)/Fe(III) ratio affected homogeneous (in solution) and heterogeneous (on quartz) precipitation rates of (Fex, Cr1-x)(OH)3 through different mechanisms. The sequestration mechanismsmore » of Cr(III) in precipitates were also investigated. In solutions with high aqueous Cr(III)/Fe(III) ratios, surface enrichment of Cr(III) on the precipitates occurred, resulting in slower particle growth in solution. From solutions with 0 – 0.1 mM Cr(III), the particles on quartz grew from 2 to 4 nm within 1 h. Interestingly, from solution with 0.25 mM Cr(III), particles of two distinct sizes (2 and 6 nm) formed on quartz, and their sizes remained unchanged throughout the reaction. Our study provided new insights on homogeneous and heterogeneous precipitation of (Fex, Cr1-x)(OH)3 nanoparticles, which can help determine the fate of Cr in aquatic environments.« less

High-temperature viscoelastic creep constitutive equations for polymer composites: Homogenization theory and experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skontorp, A.; Wang, S.S.; Shibuya, Y.

1994-12-31

In this paper, a homogenization theory is developed to determine high-temperature effective viscoelastic constitutive equations for fiber-reinforced polymer composites. The homogenization theory approximates the microstructure of a fiber composite, and determine simultaneously effective macroscopic constitutive properties of the composite and the associated microscopic strain and stress in the heterogeneous material. The time-temperature dependent homogenization theory requires that the viscoelastic constituent properties of the matrix phase at elevated temperatures, the governing equations for the composites, and the boundary conditions of the problem be Laplace transformed to a conjugate problem. The homogenized effective properties in the transformed domain are determined, using amore » two-scale asymptotic expansion of field variables and an averaging procedure. Field solutions in the unit cell are determined from basic and first-order governing equations with the aid of a boundary integral method (BIM). Effective viscoelastic constitutive properties of the composite at elevated temperatures are determined by an inverse transformation, as are the microscopic stress and deformation in the composite. Using this method, interactions among fibers and between the fibers and the matrix can be evaluated explicitly, resulting in accurate solutions for composites with high-volume fraction of reinforcing fibers. Examples are given for the case of a carbon-fiber reinforced thermoplastic polyamide composite in an elevated temperature environment. The homogenization predictions are in good agreement with experimental data available for the composite.« less

Variable valve timing in a homogenous charge compression ignition engine

DOEpatents

Lawrence, Keith E.; Faletti, James J.; Funke, Steven J.; Maloney, Ronald P.

2004-08-03

The present invention relates generally to the field of homogenous charge compression ignition engines, in which fuel is injected when the cylinder piston is relatively close to the bottom dead center position for its compression stroke. The fuel mixes with air in the cylinder during the compression stroke to create a relatively lean homogeneous mixture that preferably ignites when the piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. The present invention utilizes internal exhaust gas recirculation and/or compression ratio control to control the timing of ignition events and combustion duration in homogeneous charge compression ignition engines. Thus, at least one electro-hydraulic assist actuator is provided that is capable of mechanically engaging at least one cam actuated intake and/or exhaust valve.

Applications of High and Ultra High Pressure Homogenization for Food Safety.

PubMed

Patrignani, Francesca; Lanciotti, Rosalba

2016-01-01

Traditionally, the shelf-life and safety of foods have been achieved by thermal processing. Low temperature long time and high temperature short time treatments are the most commonly used hurdles for the pasteurization of fluid foods and raw materials. However, the thermal treatments can reduce the product quality and freshness. Consequently, some non-thermal pasteurization process have been proposed during the last decades, including high hydrostatic pressure, pulsed electric field, ultrasound (US), and high pressure homogenization (HPH). This last technique has been demonstrated to have a great potential to provide "fresh-like" products with prolonged shelf-life. Moreover, the recent developments in high-pressure-homogenization technology and the design of new homogenization valves able to withstand pressures up to 350-400 MPa have opened new opportunities to homogenization processing in the food industries and, consequently, permitted the development of new products differentiated from traditional ones by sensory and structural characteristics or functional properties. For this, this review deals with the principal mechanisms of action of HPH against microorganisms of food concern in relation to the adopted homogenizer and process parameters. In addition, the effects of homogenization on foodborne pathogenic species inactivation in relation to the food matrix and food chemico-physical and process variables will be reviewed. Also the combined use of this alternative technology with other non-thermal technologies will be considered.

Applications of High and Ultra High Pressure Homogenization for Food Safety

PubMed Central

Patrignani, Francesca; Lanciotti, Rosalba

2016-01-01

Traditionally, the shelf-life and safety of foods have been achieved by thermal processing. Low temperature long time and high temperature short time treatments are the most commonly used hurdles for the pasteurization of fluid foods and raw materials. However, the thermal treatments can reduce the product quality and freshness. Consequently, some non-thermal pasteurization process have been proposed during the last decades, including high hydrostatic pressure, pulsed electric field, ultrasound (US), and high pressure homogenization (HPH). This last technique has been demonstrated to have a great potential to provide “fresh-like” products with prolonged shelf-life. Moreover, the recent developments in high-pressure-homogenization technology and the design of new homogenization valves able to withstand pressures up to 350–400 MPa have opened new opportunities to homogenization processing in the food industries and, consequently, permitted the development of new products differentiated from traditional ones by sensory and structural characteristics or functional properties. For this, this review deals with the principal mechanisms of action of HPH against microorganisms of food concern in relation to the adopted homogenizer and process parameters. In addition, the effects of homogenization on foodborne pathogenic species inactivation in relation to the food matrix and food chemico-physical and process variables will be reviewed. Also the combined use of this alternative technology with other non-thermal technologies will be considered. PMID:27536270

Hadronic decays of B →a1(1260 )b1(1235 ) in the perturbative QCD approach

NASA Astrophysics Data System (ADS)

Jing, Hao-Yang; Liu, Xin; Xiao, Zhen-Jun

2017-12-01

We calculate the branching ratios and polarization fractions of the B →a1b1 decays in the perturbative QCD(pQCD) approach at leading order, where a1(b1) stands for the axial-vector a1(1260 )[b1(1235 )] state. By combining the phenomenological analyses with the perturbative calculations, we find the following results: (a) the large decay rates around 10-5 to 10-6 of the B →a1b1 decays dominated by the longitudinal polarization(except for the B+→b1+a10 mode) are predicted and basically consistent with those in the QCD factorization(QCDF) within errors, which are expected to be tested by the Large Hadron Collider and Belle-II experiments. The large B0→a10b10 branching ratio could provide hints to help explore the mechanism of the color-suppressed decays. (b) the rather different QCD behaviors between the a1 and b1 mesons result in the destructive(constructive) contributions in the nonfactorizable spectator diagrams with a1(b1) emission. Therefore, an interesting pattern of the branching ratios appears for the color-suppressed B0→a10a10,a10b10, and b10b10 modes in the pQCD approach, BR (B0→b10b10)>BR (B0→a10b10)≳BR (B0→a10a10), which is different from BR (B0→b10b10)˜BR (B0→a10b10)≳BR (B0→a10a10) in the QCDF and would be verified at future experiments. (c) the large naive factorization breaking effects are observed in these B →a1b1 decays. Specifically, the large nonfactorizable spectator(weak annihilation) amplitudes contribute to the B0→b1+a1-(B+→a1+b10andB+→b1+a10) mode(s), which demand confirmations via the precise measurements. Furthermore, the different phenomenologies shown among B →a1b1, B →a1a1, and B →b1b1 decays are also expected to be tested stringently, which could shed light on the typical QCD dynamics involved in these modes, even further distinguish those two popular pQCD and QCDF approaches.

Feasibility of detecting Aflatoxin B1 in single maize kernels using hyperspectral imaging

USDA-ARS?s Scientific Manuscript database

The feasibility of detecting Aflatoxin B1 (AFB1) in single maize kernel inoculated with Aspergillus flavus conidia in the field, as well as its spatial distribution in the kernels, was assessed using near-infrared hyperspectral imaging (HSI) technique. Firstly, an image mask was applied to a pixel-b...

B1-control receive array coil (B-RAC) for reducing B1+ inhomogeneity in abdominal imaging at 3T-MRI

NASA Astrophysics Data System (ADS)

Kaneko, Yukio; Soutome, Yoshihisa; Habara, Hideta; Bito, Yoshitaka; Ochi, Hisaaki

2018-02-01

B1+ inhomogeneity in the human body increases as the nuclear magnetic resonance (NMR) frequency increases. Various methods have thus been developed to reduce B1+ inhomogeneity, such as a dielectric pad, a coupling coil, parallel transmit, and radio-frequency (RF) shimming. However, B1+ inhomogeneity still remains in some cases of abdominal imaging. In this study, we developed a B1-control receive array coil (B-RAC). Unlike the conventional receive array coil, B-RAC reduces B1+ inhomogeneity by using additional PIN diodes to generate the inductive loop during the RF transmit period. The inductive loop can generate dense and sparse regions of the magnetic flux, which can be used to compensate for B1+ inhomogeneity. First, B-RAC is modeled in the numerical simulation, and the spatial distributions of B1+ in a phantom and a human model were analyzed. Next, we fabricated a 12-channel B-RAC and measured receive sensitivity and B1+ maps in a 3T-MRI experiment. It was demonstrated that B-RAC can reduce B1+ inhomogeneity in the phantom and human model without increasing the maximum local specific absorption rate (SAR) in the body. B-RAC was also found to have almost the same the receive sensitivity as the conventional receive coil. Using RF shimming combined with B-RAC was revealed to more effectively reduce B1+ inhomogeneity than using only RF shimming. Therefore, B-RAC can reduce B1+ inhomogeneity while maintaining the receive sensitivity.

26 CFR 1.267(b)-1 - Relationships.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 26 Internal Revenue 3 2011-04-01 2011-04-01 false Relationships. 1.267(b)-1 Section 1.267(b)-1...) INCOME TAXES (CONTINUED) Items Not Deductible § 1.267(b)-1 Relationships. (a) In general. (1) The persons... partnership separately. Therefore, if the other person and a partner are within any one of the relationships...

26 CFR 1.267(b)-1 - Relationships.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 3 2010-04-01 2010-04-01 false Relationships. 1.267(b)-1 Section 1.267(b)-1...) INCOME TAXES Items Not Deductible § 1.267(b)-1 Relationships. (a) In general. (1) The persons referred to... partnership separately. Therefore, if the other person and a partner are within any one of the relationships...

Characterization of ursodeoxycholic and norursodeoxycholic acid as substrates of the hepatic uptake transporters OATP1B1, OATP1B3, OATP2B1 and NTCP.

PubMed

König, Jörg; Klatt, Sabine; Dilger, Karin; Fromm, Martin F

2012-08-01

Ursodeoxycholic acid (UDCA) is the only approved treatment for primary biliary cirrhosis, and norursodeoxycholic acid (norUDCA) is currently tested in clinical trials for future treatment of primary sclerosing cholangitis because of beneficial effects in cholestatic Mdr2 knock-out mice. Uptake of UDCA and norUDCA into hepatocytes is believed to be a prerequisite for subsequent metabolism and therapeutic action. However, the molecular determinants of hepatocellular uptake of UDCA and norUDCA are poorly understood. We therefore investigated whether UDCA and norUDCA are substrates of the hepatic uptake transporters OATP1B1, OATP1B3, OATP2B1 and Na(+) -taurocholate co-transporting polypeptide (NTCP), which are localized in the basolateral membrane of hepatocytes. Uptake of [(3) H]UDCA and [(14) C]norUDCA into Human embryonic kidney (HEK) cells stably expressing OATP1B1, OATP1B3, OATP2B1 or NTCP was investigated and compared with uptake into vector control cells. Uptake ratios were calculated by dividing uptake into transporter-transfected cells by uptake into respective control cells. Uptake ratios of OATP1B1-, OATP1B3- and OATP2B1-mediated UDCA and norUDCA uptake were at maximum 1.23 and 1.49, respectively. Uptake of UDCA was significantly higher into HEK-NTCP cells only at the lowest tested concentration (1 μM, p < 0.001) compared with the control cells with an uptake ratio of 1.34-fold. NorUDCA was not significantly transported by NTCP. The low uptake rates suggest that OATP1B1, OATP1B3, OATP2B1 and NTCP are not relevant for hepatocellular uptake and effects of UDCA and norUDCA in human beings. © 2012 The Authors Basic & Clinical Pharmacology & Toxicology © 2012 Nordic Pharmacological Society.

CNR considerations for rapid real-time MRI tumor tracking in radiotherapy hybrid devices: Effects of B{sub 0} field strength

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wachowicz, K., E-mail: keith.wachowicz@albertaheal

2016-08-15

Purpose: This work examines the subject of contrast-to-noise ratio (CNR), specifically between tumor and tissue background, and its dependence on the MRI field strength, B{sub 0}. This examination is motivated by the recent interest and developments in MRI/radiotherapy hybrids where real-time imaging can be used to guide treatment beams. The ability to distinguish a tumor from background tissue is of primary importance in this field, and this work seeks to elucidate the complex relationship between the CNR and B{sub 0} that is too often assumed to be purely linear. Methods: Experimentally based models of B{sub 0}-dependant relaxation for various tumormore » and normal tissues from the literature were used in conjunction with signal equations for MR sequences suitable for rapid real-time imaging to develop field-dependent predictions for CNR. These CNR models were developed for liver, lung, breast, glioma, and kidney tumors for spoiled gradient-echo, balanced steady-state free precession (bSSFP), and single-shot half-Fourier fast spin echo sequences. Results: Due to the pattern in which the relaxation properties of tissues are found to vary over B{sub 0} field (specifically the T{sub 1} time), there was always an improved CNR at lower fields compared to linear dependency. Further, in some tumor sites, the CNR at lower fields was found to be comparable to, or sometimes higher than those at higher fields (i.e., bSSFP CNR for glioma, kidney, and liver tumors). Conclusions: In terms of CNR, lower B{sub 0} fields have been shown to perform as well or better than higher fields for some tumor sites due to superior T{sub 1} contrast. In other sites this effect was less pronounced, reversing the CNR advantage. This complex relationship between CNR and B{sub 0} reveals both low and high magnetic fields as viable options for tumor tracking in MRI/radiotherapy hybrids.« less

18 CFR 1b.1 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Definitions. 1b.1 Section 1b.1 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF... pipelines, electric utilities and hydroelectric projects. [43 FR 27174, June 23, 1978, as amended by Order...

Polycyclic phloroglucinols as PTP1B inhibitors from Hypericum longistylum: Structures, PTP1B inhibitory activities, and interactions with PTP1B.

PubMed

Cao, Xiangrong; Yang, Xueyuan; Wang, Peixia; Liang, Yue; Liu, Feng; Tuerhong, Muhetaer; Jin, Da-Qing; Xu, Jing; Lee, Dongho; Ohizumi, Yasushi; Guo, Yuanqiang

2017-12-01

Protein tyrosine phosphatase 1B (PTP1B) has been regarded asa target for the research and development of new drugs to treat type II diabetes and PTP1B inhibitors are potential lead compounds for this type of new drugs. A phytochemical investigation to obtain new PTP1B inhibitors resulted in the isolation of four new phloroglucinols, longistyliones A-D (1-4) from the aerial parts of Hypericum longistylum. The structures of 1-4 were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analysis, and the absolute configurations of these compounds were established by comparing their experimental electronic circular dichroism (ECD) spectra with those calculated by the time-dependent density functional theory method. Compounds 1-4 possess a rare polycyclic phloroglucinol skeleton. The following biological evaluation revealed that all of the compounds showed PTP1B inhibitory effects. The further molecular docking studies indicated the strong interactions between these bioactive compounds with the PTP1B protein, which revealed the possible mechanism of PTP1B inhibition of bioactive compounds. All of the results implied that these compounds are potentially useful for the treatment of type II diabetes. Copyright © 2017 Elsevier Inc. All rights reserved.

Symbiotic effects of a lipase-secreting bacterium, Burkholderia arboris SL1B1, and a glycerol-assimilating yeast, Candida cylindracea SL1B2, on triacylglycerol degradation.

PubMed

Matsuoka, Hiroshi; Miura, Atsuto; Hori, Katsutoshi

2009-04-01

Although microbial degradation of oils and fats has been developed for application in wastewater treatment, microbial degraders are not always effective in the field, for example, in grease-traps installed for the treatment of wastewater from restaurants and food industries. Wastewater in grease-traps is usually in a pH range of 5.5 to 6.5 due to hydrolysis of triacylglycerol (TAG). Because many microorganisms commercialized for use in grease-traps cannot grow at pH 6.0, we screened oil-degrading microorganisms from the environment by growing in a medium at pH 6.0 containing canola oil as the sole carbon source. We succeeded in isolating the bacterial strain Burkholderia arboris SL1B1, which secretes lipase and assimilates fatty acids, and the yeast strain Candida cylindracea SL1B2, which assimilates glycerol. The former cannot utilize glycerol as a carbon source while the latter shows only faint lipase activity that cannot support its active growth on TAG. Canola oil was degraded rapidly by a pure culture of SL1B1 at pH 6.0. However, the degradation was markedly enhanced by a mixed culture of SL1B1 and SL1B2, although lipase activity during cultivation was similar between the pure and mixed cultures. This suggests that the reversible reaction proceeds in the direction of hydrolysis of TAG due to consumption of the reaction product, glycerol, by the symbiotic yeast strain. The optimum pH and temperature of lipase secreted by B. arboris SL1B1 were 8.0 and 60 degrees C, respectively. This lipase showed highly thermal stability; the residual activity after incubation at 70 degrees C for 2 h did not decline.

Regional Homogeneity

PubMed Central

Jiang, Lili; Zuo, Xi-Nian

2015-01-01

Much effort has been made to understand the organizational principles of human brain function using functional magnetic resonance imaging (fMRI) methods, among which resting-state fMRI (rfMRI) is an increasingly recognized technique for measuring the intrinsic dynamics of the human brain. Functional connectivity (FC) with rfMRI is the most widely used method to describe remote or long-distance relationships in studies of cerebral cortex parcellation, interindividual variability, and brain disorders. In contrast, local or short-distance functional interactions, especially at a scale of millimeters, have rarely been investigated or systematically reviewed like remote FC, although some local FC algorithms have been developed and applied to the discovery of brain-based changes under neuropsychiatric conditions. To fill this gap between remote and local FC studies, this review will (1) briefly survey the history of studies on organizational principles of human brain function; (2) propose local functional homogeneity as a network centrality to characterize multimodal local features of the brain connectome; (3) render a neurobiological perspective on local functional homogeneity by linking its temporal, spatial, and individual variability to information processing, anatomical morphology, and brain development; and (4) discuss its role in performing connectome-wide association studies and identify relevant challenges, and recommend its use in future brain connectomics studies. PMID:26170004

Erbium-doped phosphate glass waveguide on silicon with 4.1 dB/cm gain at 1.535 µm

NASA Astrophysics Data System (ADS)

Yan, Y. C.; Faber, A. J.; de Waal, H.; Kik, P. G.; Polman, A.

1997-11-01

Erbium-doped multicomponent phosphate glass waveguides were deposited by rf sputtering techniques. The Er concentration was 5.3×1020cm-3. By pumping the waveguide at 980 nm with a power of ˜21 mW, a net optical gain of 4.1 dB at 1.535 μm was achieved. This high gain per unit length at low pump power could be achieved because the Er-Er cooperative upconversion interactions in this heavily Er-doped phosphate glass are very weak [the upconversion coefficient is (2.0±0.5)×10-18 cm3/s], presumably due to the homogeneous distribution of Er in the glass and due to the high optical mode confinement in the waveguide which leads to high pump power density at low pump power.

Benchmarking monthly homogenization algorithms

NASA Astrophysics Data System (ADS)

Venema, V. K. C.; Mestre, O.; Aguilar, E.; Auer, I.; Guijarro, J. A.; Domonkos, P.; Vertacnik, G.; Szentimrey, T.; Stepanek, P.; Zahradnicek, P.; Viarre, J.; Müller-Westermeier, G.; Lakatos, M.; Williams, C. N.; Menne, M.; Lindau, R.; Rasol, D.; Rustemeier, E.; Kolokythas, K.; Marinova, T.; Andresen, L.; Acquaotta, F.; Fratianni, S.; Cheval, S.; Klancar, M.; Brunetti, M.; Gruber, C.; Prohom Duran, M.; Likso, T.; Esteban, P.; Brandsma, T.

2011-08-01

The COST (European Cooperation in Science and Technology) Action ES0601: Advances in homogenization methods of climate series: an integrated approach (HOME) has executed a blind intercomparison and validation study for monthly homogenization algorithms. Time series of monthly temperature and precipitation were evaluated because of their importance for climate studies and because they represent two important types of statistics (additive and multiplicative). The algorithms were validated against a realistic benchmark dataset. The benchmark contains real inhomogeneous data as well as simulated data with inserted inhomogeneities. Random break-type inhomogeneities were added to the simulated datasets modeled as a Poisson process with normally distributed breakpoint sizes. To approximate real world conditions, breaks were introduced that occur simultaneously in multiple station series within a simulated network of station data. The simulated time series also contained outliers, missing data periods and local station trends. Further, a stochastic nonlinear global (network-wide) trend was added. Participants provided 25 separate homogenized contributions as part of the blind study as well as 22 additional solutions submitted after the details of the imposed inhomogeneities were revealed. These homogenized datasets were assessed by a number of performance metrics including (i) the centered root mean square error relative to the true homogeneous value at various averaging scales, (ii) the error in linear trend estimates and (iii) traditional contingency skill scores. The metrics were computed both using the individual station series as well as the network average regional series. The performance of the contributions depends significantly on the error metric considered. Contingency scores by themselves are not very informative. Although relative homogenization algorithms typically improve the homogeneity of temperature data, only the best ones improve precipitation data

Opposing roles of the aldo-keto reductases AKR1B1 and AKR1B10 in colorectal cancer.

PubMed

Taskoparan, Betul; Seza, Esin Gulce; Demirkol, Secil; Tuncer, Sinem; Stefek, Milan; Gure, Ali Osmay; Banerjee, Sreeparna

2017-12-01

Aldo-keto reductases (including AKR1B1 and AKR1B10) constitute a family of oxidoreductases that have been implicated in the pathophysiology of diabetes and cancer, including colorectal cancer (CRC). Available data indicate that, despite their similarities in structure and enzymatic functions, their roles in CRC may be divergent. Here, we aimed to determine the expression and functional implications of AKR1B1 and AKR1B10 in CRC. AKR1B1 and AKR1B10 gene expression levels were analyzed using publicly available microarray data and ex vivo CRC-derived cDNA samples. Gene Set Enrichment Analysis (GSEA), The Cancer Genome Atlas (TCGA) RNA-seq data and The Cancer Proteome Atlas (TCPA) proteome data were analyzed to determine the effect of high and low AKR1B1 and AKR1B10 expression levels in CRC patients. Proliferation, cell cycle progression, cellular motility, adhesion and inflammation were determined in CRC-derived cell lines in which these genes were either exogenously overexpressed or silenced. We found that the expression of AKR1B1 was unaltered, whereas that of AKR1B10 was decreased in primary CRCs. GSEA revealed that, while high AKR1B1 expression was associated with increased cell cycle progression, cellular motility and inflammation, high AKR1B10 expression was associated with a weak inflammatory phenotype. Functional studies carried out in CRC-derived cell lines confirmed these data. Microarray data analysis indicated that high expression levels of AKR1B1 and AKR1B10 were significantly associated with shorter and longer disease-free survival rates, respectively. A combined gene expression signature of AKR1B10 (low) and AKR1B1 (high) showed a better prognostic stratification of CRC patients independent of confounding factors. Despite their similarities, the expression levels and functions of AKR1B1 and AKR1B10 are highly divergent in CRC, and they may have prognostic implications.

Quantitation Error in 1H MRS Caused by B1 Inhomogeneity and Chemical Shift Displacement.

PubMed

Watanabe, Hidehiro; Takaya, Nobuhiro

2017-11-08

The quantitation accuracy in proton magnetic resonance spectroscopy ( 1 H MRS) improves at higher B 0 field. However, a larger chemical shift displacement (CSD) and stronger B 1 inhomogeneity exist. In this work, we evaluate the quantitation accuracy for the spectra of metabolite mixtures in phantom experiments at 4.7T. We demonstrate a position-dependent error in quantitation and propose a correction method by measuring water signals. All experiments were conducted on a whole-body 4.7T magnetic resonance (MR) system with a quadrature volume coil for transmission and reception. We arranged three bottles filled with metabolite solutions of N-acetyl aspartate (NAA) and creatine (Cr) in a vertical row inside a cylindrical phantom filled with water. Peak areas of three singlets of NAA and Cr were measured on three 1 H spectra at three volume of interests (VOIs) inside three bottles. We also measured a series of water spectra with a shifted carrier frequency and measured a reception sensitivity map. The ratios of NAA and Cr at 3.92 ppm to Cr at 3.01 ppm differed amongst the three VOIs in peak area, which leads to a position-dependent error. The nature of slope depicting the relationship between peak areas and the shifted values of frequency was like that between the reception sensitivities and displacement at every VOI. CSD and inhomogeneity of reception sensitivity cause amplitude modulation along the direction of chemical shift on the spectra, resulting in a quantitation error. This error may be more significant at higher B 0 field where CSD and B 1 inhomogeneity are more severe. This error may also occur in reception using a surface coil having inhomogeneous B 1 . Since this type of error is around a few percent, the data should be analyzed with greater attention while discussing small differences in the studies of 1 H MRS.

The relationship between the IMF B(y) and the distant tail (150-238 Re) lobe and plasmasheet B(y) fields

NASA Technical Reports Server (NTRS)

Tsurutani, B. T.; Smith, E. J.; Jones, D. E.; Lepping, R. P.; Sibeck, D. G.

1984-01-01

The relationships between the Solar Magnetospheric (SM) y-component of the interplanetary magnetic field (IMF) and the lobe and plasmasheet magnetic fields have been studied for the two ISEE-3 deep tail passes. It is found that for positive sector IMFs, 13 percent of the interplanetary magnetic field penetrates into the aberrated north-dawn and south-dusk lobe quadrants, and about the same amount in the north-dusk and south-dawn lobe quadrants for negative sector IMFs. For the above cases, field penetration is significantly less for opposite polarity IMFs. The former results are generally consistent with open magnetospheric models, but the latter (the lack of response in certain quadrants) are unexplained by theory at this time. If the magnitude of the plasmasheet B(y) fields are related to plasma pressure anisotropies, very small anisotropies of about 1.01 are expected.

Upper critical field and Kondo effects in Fe(Te 0.9Se 0.1) thin films by pulsed field measurements

DOE PAGES

Salamon, Myron B.; Cornell, Nicholas; Jaime, Marcelo; ...

2016-02-10

The transition temperatures of epitaxial films of Fe(Te 0:9Se 0:1) are remarkably insensitive to applied magnetic field, leading to predictions of upper critical fields B c2(T = 0) in excess of 100 T. Using pulsed magnetic fields, we find B c2(0) to be on the order of 45 T, similar to values in bulk material and still in excess of the paramagnetic limit. The same films show strong magnetoresistance in fields above B c2(T), consistent with the observed Kondo minimum seen above T c. Fits to the temperature dependence in the context of the WHH model, using the experimental valuemore » of the Maki parameter, require an effective spin-orbit relaxation parameter of order unity. Lastly, we suggest that Kondo localization plays a similar role to spin-orbit pair breaking in making WHH fits to the data.« less

Generation of a parvovirus B19 vaccine candidate.

PubMed

Chandramouli, Sumana; Medina-Selby, Angelica; Coit, Doris; Schaefer, Mary; Spencer, Terika; Brito, Luis A; Zhang, Pu; Otten, Gillis; Mandl, Christian W; Mason, Peter W; Dormitzer, Philip R; Settembre, Ethan C

2013-08-20

Parvovirus B19 is the causative agent of fifth disease in children, aplastic crisis in those with blood dyscrasias, and hydrops fetalis. Previous parvovirus B19 virus-like-particle (VLP) vaccine candidates were produced by co-infection of insect cells with two baculoviruses, one expressing wild-type VP1 and the other expressing VP2. In humans, the VLPs were immunogenic but reactogenic. We have developed new VLP-based parvovirus B19 vaccine candidates, produced by co-expressing VP2 and either wild-type VP1 or phospholipase-negative VP1 in a regulated ratio from a single plasmid in Saccharomyces cerevisiae. These VLPs are expressed efficiently, are very homogeneous, and can be highly purified. Although VP2 alone can form VLPs, in mouse immunizations, VP1 and the adjuvant MF59 are required to elicit a neutralizing response. Wild-type VLPs and those with phospholipase-negative VP1 are equivalently potent. The purity, homogeneity, yeast origin, and lack of phospholipase activity of these VLPs address potential causes of previously observed reactogenicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of a homogeneous immunoassay system using protein A fusion fragmented Renilla luciferase.

PubMed

Mie, Masayasu; Thuy, Ngo Phan Bich; Kobatake, Eiry

2012-03-07

A homogeneous immunoassay system was developed using fragmented Renilla luciferase (Rluc). The B domain of protein A was fused to two Rluc fragments. When complexes between an antibody and fragmented Rluc fusion proteins bind to target molecules, the Rluc fragments come into close proximity and the luminescence activity of fragmented Rluc is restored by complementation. As proof-of-principle, this fragmented Rluc system was used to detect E. coli homogeneously using an anti-E. coli antibody.

Trapped magnetic-field properties of prototype for Gd-Ba-Cu-O/MgB2 hybrid-type superconducting bulk magnet

NASA Astrophysics Data System (ADS)

Naito, Tomoyuki; Mochizuki, Hidehiko; Fujishiro, Hiroyuki; Teshima, Hidekazu

2016-03-01

We have studied experimentally and numerically the trapped magnetic-field properties of a hybrid-type superconducting bulk magnet, which comprised an inner Gd-Ba-Cu-O (GdBCO) disk-bulk and an outer MgB2 ring-bulk, under field-cooled magnetization (FCM) and pulsed-field magnetization (PFM). The trapped field by FCM at the center of the hybrid bulk was 4.5 T at 20 K, which was 0.2 T higher than that of the inner GdBCO disk-bulk without MgB2 ring-bulk. The experimental results by FCM were quantitatively reproduced by the numerical estimations for a model, which makes it possible to understand the trapped field properties of the hybrid bulk. The total magnetic flux by FCM, which was estimated numerically, was enhanced by about 1.7 times from 0.91 mWb of the single GdBCO bulk to 1.53 mWb of the hybrid bulk. We also succeeded in magnetizing the whole hybrid bulk by applying multi-pulsed-fields. The central trapped field of 1.88 T was not enhanced, but the total magnetic flux, which was obtained experimentally, was evidently increased by 2.5 times (0.25 \\to 0.62 mWb) for the hybrid bulk. The obtained results suggest that the hybridization is effective to enhance the total magnetic flux. To confirm the reinforcing effect of the MgB2 ring to the GdBCO disk during the cooling and magnetization processes, we have measured the thermal dilatation, {\\text{}}{dL}({\\text{}}T)/{\\text{}}L(300 K), of the GdBCO, MgB2 and stainless steel. As a result, the thermal dilatation of MgB2 was smaller than that of GdBCO. MgB2 ring-bulk shows no compression effect to resist the hoop stress of the GdBCO disk-bulk during the FCM process. The reinforcing material such as the stainless steel ring must be set outside the GdBCO disk-bulk.

Field Note--From MSW to J-O-B: Using Field Seminar to Prepare Students for Employment

ERIC Educational Resources Information Center

Deck, Stacy M.; Miller, Justin Jay; Conley, Cynthia L.

2017-01-01

Social work field education is expected to help students transition from the classroom to the practice setting. Yet, few social work programs adequately provide career development support to increase students' employability. This Field Note presents practical, relevant and immediate strategies for implementing the MSW to J-O-B curriculum…

Annual Data Summary and Climatological Evaluation CERC (Coastal Engineering Research Center) Field Research Facility, 1985. Volume 1. Main Text and Appendixes A and B.

DTIC Science & Technology

1987-09-01

AD-AI6 442 ANNUAL DATA SUMMARY AND CLINATOLOGICAL EVALUATION CEC I/ (COASTAL ENGINEERI.. (U) COASTAL ENGINEERING RESEARCH CENTER VICKSBURG NS H C ...MILLER ET RL. SEP 87 UNL ASSIF IED C RC-TR-87-i-L-1 F/0G/3 Mmsomommosmsss EmhhhmmmmmhEhEshhhhEhBhhE .EhI-EllhhlhhI mll/I/I l/I/u -1 I.I I ’ 22 I 1.8...SUMMARY AND ofEgier CLIMATOLOGICAL EVALUATION CERC FIELD RESEARCH FACILITY, 1985 NVolume I MAIN TEXT AND APPENDIXES A AND B, by ,, U Herman C . Miller

Dense Velocity Field of Turkey

NASA Astrophysics Data System (ADS)

Ozener, H.; Aktug, B.; Dogru, A.; Tasci, L.

2017-12-01

While the GNSS-based crustal deformation studies in Turkey date back to early 1990s, a homogenous velocity field utilizing all the available data is still missing. Regional studies employing different site distributions, observation plans, processing software and methodology not only create reference frame variations but also heterogeneous stochastic models. While the reference frame effect between different velocity fields could easily be removed by estimating a set of rotations, the homogenization of the stochastic models of the individual velocity fields requires a more detailed analysis. Using a rigorous Variance Component Estimation (VCE) methodology, we estimated the variance factors for each of the contributing velocity fields and combined them into a single homogenous velocity field covering whole Turkey. Results show that variance factors between velocity fields including the survey mode and continuous observations can vary a few orders of magnitude. In this study, we present the most complete velocity field in Turkey rigorously combined from 20 individual velocity fields including the 146 station CORS network and totally 1072 stations. In addition, three GPS campaigns were performed along the North Anatolian Fault and Aegean Region to fill the gap between existing velocity fields. The homogenously combined new velocity field is nearly complete in terms of geographic coverage, and will serve as the basis for further analyses such as the estimation of the deformation rates and the determination of the slip rates across main fault zones.

Bootstrap Percolation on Homogeneous Trees Has 2 Phase Transitions

NASA Astrophysics Data System (ADS)

Fontes, L. R. G.; Schonmann, R. H.

2008-09-01

We study the threshold θ bootstrap percolation model on the homogeneous tree with degree b+1, 2≤ θ≤ b, and initial density p. It is known that there exists a nontrivial critical value for p, which we call p f , such that a) for p> p f , the final bootstrapped configuration is fully occupied for almost every initial configuration, and b) if p< p f , then for almost every initial configuration, the final bootstrapped configuration has density of occupied vertices less than 1. In this paper, we establish the existence of a distinct critical value for p, p c , such that 0< p c < p f , with the following properties: 1) if p≤ p c , then for almost every initial configuration there is no infinite cluster of occupied vertices in the final bootstrapped configuration; 2) if p> p c , then for almost every initial configuration there are infinite clusters of occupied vertices in the final bootstrapped configuration. Moreover, we show that 3) for p< p c , the distribution of the occupied cluster size in the final bootstrapped configuration has an exponential tail; 4) at p= p c , the expected occupied cluster size in the final bootstrapped configuration is infinite; 5) the probability of percolation of occupied vertices in the final bootstrapped configuration is continuous on [0, p f ] and analytic on ( p c , p f ), admitting an analytic continuation from the right at p c and, only in the case θ= b, also from the left at p f .

Homogeneous catalyst formulations for methanol production

DOEpatents

Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

1991-02-12

There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.-), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

Homogeneous catalyst formulations for methanol production

DOEpatents

Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

1990-01-01

There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.13 ), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

BA3b and BA1 activate in a serial fashion after median nerve stimulation: direct evidence from combining source analysis of evoked fields and cytoarchitectonic probabilistic maps.

PubMed

Papadelis, Christos; Eickhoff, Simon B; Zilles, Karl; Ioannides, Andreas A

2011-01-01

This study combines source analysis imaging data for early somatosensory processing and the probabilistic cytoarchitectonic maps (PCMs). Human somatosensory evoked fields (SEFs) were recorded by stimulating left and right median nerves. Filtering the recorded responses in different frequency ranges identified the most responsive frequency band. The short-latency averaged SEFs were analyzed using a single equivalent current dipole (ECD) model and magnetic field tomography (MFT). The identified foci of activity were superimposed with PCMs. Two major components of opposite polarity were prominent around 21 and 31 ms. A weak component around 25 ms was also identified. For the most responsive frequency band (50-150 Hz) ECD and MFT revealed one focal source at the contralateral Brodmann area 3b (BA3b) at the peak of N20. The component ~25 ms was localised in Brodmann area 1 (BA1) in 50-150 Hz. By using ECD, focal generators around 28-30 ms located initially in BA3b and 2 ms later to BA1. MFT also revealed two focal sources - one in BA3b and one in BA1 for these latencies. Our results provide direct evidence that the earliest cortical response after median nerve stimulation is generated within the contralateral BA3b. BA1 activation few milliseconds later indicates a serial mode of somatosensory processing within cytoarchitectonic SI subdivisions. Analysis of non-invasive magnetoencephalography (MEG) data and the use of PCMs allow unambiguous and quantitative (probabilistic) interpretation of cytoarchitectonic identity of activated areas following median nerve stimulation, even with the simple ECD model, but only when the model fits the data extremely well. Copyright © 2010 Elsevier Inc. All rights reserved.

Immortal homogeneous Ricci flows

NASA Astrophysics Data System (ADS)

Böhm, Christoph; Lafuente, Ramiro A.

2018-05-01

We show that for an immortal homogeneous Ricci flow solution any sequence of parabolic blow-downs subconverges to a homogeneous expanding Ricci soliton. This is established by constructing a new Lyapunov function based on curvature estimates which come from real geometric invariant theory.

Estimating time since infection in early homogeneous HIV-1 samples using a poisson model

PubMed Central

2010-01-01

Background The occurrence of a genetic bottleneck in HIV sexual or mother-to-infant transmission has been well documented. This results in a majority of new infections being homogeneous, i.e., initiated by a single genetic strain. Early after infection, prior to the onset of the host immune response, the viral population grows exponentially. In this simple setting, an approach for estimating evolutionary and demographic parameters based on comparison of diversity measures is a feasible alternative to the existing Bayesian methods (e.g., BEAST), which are instead based on the simulation of genealogies. Results We have devised a web tool that analyzes genetic diversity in acutely infected HIV-1 patients by comparing it to a model of neutral growth. More specifically, we consider a homogeneous infection (i.e., initiated by a unique genetic strain) prior to the onset of host-induced selection, where we can assume a random accumulation of mutations. Previously, we have shown that such a model successfully describes about 80% of sexual HIV-1 transmissions provided the samples are drawn early enough in the infection. Violation of the model is an indicator of either heterogeneous infections or the initiation of selection. Conclusions When the underlying assumptions of our model (homogeneous infection prior to selection and fast exponential growth) are met, we are under a very particular scenario for which we can use a forward approach (instead of backwards in time as provided by coalescent methods). This allows for more computationally efficient methods to derive the time since the most recent common ancestor. Furthermore, the tool performs statistical tests on the Hamming distance frequency distribution, and outputs summary statistics (mean of the best fitting Poisson distribution, goodness of fit p-value, etc). The tool runs within minutes and can readily accommodate the tens of thousands of sequences generated through new ultradeep pyrosequencing technologies. The tool

Demagnetization of Nd 2Fe 14B, Pr 2Fe 14B, and Sm 2Co 17 Permanent Magnets in Spallation Irradiation Fields

DOE PAGES

Simos, Nikolaos; Ozaki, S.; Mokhov, N.; ...

2018-02-27

Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd 2Fe 14B and Pr 2Fe 14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd 2Fe 14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr 2Fe 14B magnets irradiated to a lower dose of 20 Mrad.more » In addition, annular Sm 2Co 17 and Nd 2Fe 14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm 2Co 17 and 20 Mrad for Nd 2Fe 14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd 2Fe 14B magnets after only 50 Mrad dose and over 87% for Pr 2Fe 14B after 10 Mrad dose. The annular-shaped Sm 2Co 17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd 2Fe 14B magnets also showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.« less

Demagnetization of Nd 2Fe 14B, Pr 2Fe 14B, and Sm 2Co 17 Permanent Magnets in Spallation Irradiation Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simos, Nikolaos; Ozaki, S.; Mokhov, N.

Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd 2Fe 14B and Pr 2Fe 14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd 2Fe 14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr 2Fe 14B magnets irradiated to a lower dose of 20 Mrad.more » In addition, annular Sm 2Co 17 and Nd 2Fe 14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm 2Co 17 and 20 Mrad for Nd 2Fe 14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd 2Fe 14B magnets after only 50 Mrad dose and over 87% for Pr 2Fe 14B after 10 Mrad dose. The annular-shaped Sm 2Co 17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd 2Fe 14B magnets also showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.« less

A multi-scale homogenization model for fine-grained porous viscoplastic polycrystals: I - Finite-strain theory

NASA Astrophysics Data System (ADS)

Song, Dawei; Ponte Castañeda, P.

2018-06-01

We make use of the recently developed iterated second-order homogenization method to obtain finite-strain constitutive models for the macroscopic response of porous polycrystals consisting of large pores randomly distributed in a fine-grained polycrystalline matrix. The porous polycrystal is modeled as a three-scale composite, where the grains are described by single-crystal viscoplasticity and the pores are assumed to be large compared to the grain size. The method makes use of a linear comparison composite (LCC) with the same substructure as the actual nonlinear composite, but whose local properties are chosen optimally via a suitably designed variational statement. In turn, the effective properties of the resulting three-scale LCC are determined by means of a sequential homogenization procedure, utilizing the self-consistent estimates for the effective behavior of the polycrystalline matrix, and the Willis estimates for the effective behavior of the porous composite. The iterated homogenization procedure allows for a more accurate characterization of the properties of the matrix by means of a finer "discretization" of the properties of the LCC to obtain improved estimates, especially at low porosities, high nonlinearties and high triaxialities. In addition, consistent homogenization estimates for the average strain rate and spin fields in the pores and grains are used to develop evolution laws for the substructural variables, including the porosity, pore shape and orientation, as well as the "crystallographic" and "morphological" textures of the underlying matrix. In Part II of this work has appeared in Song and Ponte Castañeda (2018b), the model will be used to generate estimates for both the instantaneous effective response and the evolution of the microstructure for porous FCC and HCP polycrystals under various loading conditions.

40 CFR Figure B-1 to Subpart B of... - Example

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Example B Figure B-1 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Fig. B-1 Figure B-1 to Subpart B of...

40 CFR Figure B-1 to Subpart B of... - Example

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Example B Figure B-1 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Fig. B-1 Figure B-1 to Subpart B of...

40 CFR Figure B-1 to Subpart B of... - Example

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Example B Figure B-1 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Fig. B-1 Figure B-1 to Subpart B of...

Asymptotic Expansion Homogenization for Multiscale Nuclear Fuel Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hales, J. D.; Tonks, M. R.; Chockalingam, K.

2015-03-01

Engineering scale nuclear fuel performance simulations can benefit by utilizing high-fidelity models running at a lower length scale. Lower length-scale models provide a detailed view of the material behavior that is used to determine the average material response at the macroscale. These lower length-scale calculations may provide insight into material behavior where experimental data is sparse or nonexistent. This multiscale approach is especially useful in the nuclear field, since irradiation experiments are difficult and expensive to conduct. The lower length-scale models complement the experiments by influencing the types of experiments required and by reducing the total number of experiments needed.more » This multiscale modeling approach is a central motivation in the development of the BISON-MARMOT fuel performance codes at Idaho National Laboratory. These codes seek to provide more accurate and predictive solutions for nuclear fuel behavior. One critical aspect of multiscale modeling is the ability to extract the relevant information from the lower length-scale sim- ulations. One approach, the asymptotic expansion homogenization (AEH) technique, has proven to be an effective method for determining homogenized material parameters. The AEH technique prescribes a system of equations to solve at the microscale that are used to compute homogenized material constants for use at the engineering scale. In this work, we employ AEH to explore the effect of evolving microstructural thermal conductivity and elastic constants on nuclear fuel performance. We show that the AEH approach fits cleanly into the BISON and MARMOT codes and provides a natural, multidimensional homogenization capability.« less

75 FR 22508 - Airworthiness Directives; Eurocopter France Model AS350B, BA, B1, B2, B3, C, D, and D1; AS 355E...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-29

... Airworthiness Directives; Eurocopter France Model AS350B, BA, B1, B2, B3, C, D, and D1; AS 355E, F, F1, F2, N... (b) None. Applicability (c) This AD applies to Model AS350B, BA, B1, B2, B3, C, D and D1; and AS 355E..., both dated November 16, 2005, is approved by the Director of the Federal Register as of May 14, 2010...

Broken Ergodicity in Two-Dimensional Homogeneous Magnetohydrodynamic Turbulence

NASA Technical Reports Server (NTRS)

Shebalin, John V.

2010-01-01

Two-dimensional (2-D) homogeneous magnetohydrodynamic (MHD) turbulence has many of the same qualitative features as three-dimensional (3-D) homogeneous MHD turbulence.The se features include several ideal invariants, along with the phenomenon of broken ergodicity. Broken ergodicity appears when certain modes act like random variables with mean values that are large compared to their standard deviations, indicating a coherent structure or dynamo.Recently, the origin of broken ergodicity in 3-D MHD turbulence that is manifest in the lowest wavenumbers was explained. Here, a detailed description of the origins of broken ergodicity in 2-D MHD turbulence is presented. It will be seen that broken ergodicity in ideal 2-D MHD turbulence can be manifest in the lowest wavenumbers of a finite numerical model for certain initial conditions or in the highest wavenumbers for another set of initial conditions.T he origins of broken ergodicity in ideal 2-D homogeneous MHD turbulence are found through an eigen analysis of the covariance matrices of the modal probability density functions.It will also be shown that when the lowest wavenumber magnetic field becomes quasi-stationary, the higher wavenumber modes can propagate as Alfven waves on these almost static large-scale magnetic structures

Compressible homogeneous shear: Simulation and modeling

NASA Technical Reports Server (NTRS)

Sarkar, S.; Erlebacher, G.; Hussaini, M. Y.

1992-01-01

Compressibility effects were studied on turbulence by direct numerical simulation of homogeneous shear flow. A primary observation is that the growth of the turbulent kinetic energy decreases with increasing turbulent Mach number. The sinks provided by compressible dissipation and the pressure dilatation, along with reduced Reynolds shear stress, are shown to contribute to the reduced growth of kinetic energy. Models are proposed for these dilatational terms and verified by direct comparison with the simulations. The differences between the incompressible and compressible fields are brought out by the examination of spectra, statistical moments, and structure of the rate of strain tensor.

Compressible homogeneous shear - Simulation and modeling

NASA Technical Reports Server (NTRS)

Sarkar, S.; Erlebacher, G.; Hussaini, M. Y.

1991-01-01

Compressibility effects were studied on turbulence by direct numerical simulation of homogeneous shear flow. A primary observation is that the growth of the turbulent kinetic energy decreases with increasing turbulent Mach number. The sinks provided by compressible dissipation and the pressure dilatation, along with reduced Reynolds shear stress, are shown to contribute to the reduced growth of kinetic energy. Models are proposed for these dilatational terms and verified by direct comparison with the simulations. The differences between the incompressible and compressible fields are brought out by the examination of spectra, statistical moments, and structure of the rate of strain tensor.

High throughput film dosimetry in homogeneous and heterogeneous media for a small animal irradiator

PubMed Central

Wack, L.; Ngwa, W.; Tryggestad, E.; Tsiamas, P.; Berbeco, R.; Ng, S.K.; Hesser, J.

2013-01-01

Purpose We have established a high-throughput Gafchromic film dosimetry protocol for narrow kilo-voltage beams in homogeneous and heterogeneous media for small-animal radiotherapy applications. The kV beam characterization is based on extensive Gafchromic film dosimetry data acquired in homogeneous and heterogeneous media. An empirical model is used for parameterization of depth and off-axis dependence of measured data. Methods We have modified previously published methods of film dosimetry to suit the specific tasks of the study. Unlike film protocols used in previous studies, our protocol employs simultaneous multichannel scanning and analysis of up to nine Gafchromic films per scan. A scanner and background correction were implemented to improve accuracy of the measurements. Measurements were taken in homogeneous and inhomogeneous phantoms at 220 kVp and a field size of 5 × 5 mm2. The results were compared against Monte Carlo simulations. Results Dose differences caused by variations in background signal were effectively removed by the corrections applied. Measurements in homogeneous phantoms were used to empirically characterize beam data in homogeneous and heterogeneous media. Film measurements in inhomogeneous phantoms and their empirical parameterization differed by about 2%–3%. The model differed from MC by about 1% (water, lung) to 7% (bone). Good agreement was found for measured and modelled off-axis ratios. Conclusions EBT2 films are a valuable tool for characterization of narrow kV beams, though care must be taken to eliminate disturbances caused by varying background signals. The usefulness of the empirical beam model in interpretation and parameterization of film data was demonstrated. PMID:23510532

Field Performance of an Optimized Stack of YBCO Square “Annuli” for a Compact NMR Magnet

PubMed Central

Hahn, Seungyong; Voccio, John; Bermond, Stéphane; Park, Dong-Keun; Bascuñán, Juan; Kim, Seok-Beom; Masaru, Tomita; Iwasa, Yukikazu

2011-01-01

The spatial field homogeneity and time stability of a trapped field generated by a stack of YBCO square plates with a center hole (square “annuli”) was investigated. By optimizing stacking of magnetized square annuli, we aim to construct a compact NMR magnet. The stacked magnet consists of 750 thin YBCO plates, each 40-mm square and 80- μm thick with a 25-mm bore, and has a Ø10 mm room-temperature access for NMR measurement. To improve spatial field homogeneity of the 750-plate stack (YP750) a three-step optimization was performed: 1) statistical selection of best plates from supply plates; 2) field homogeneity measurement of multi-plate modules; and 3) optimal assembly of the modules to maximize field homogeneity. In this paper, we present analytical and experimental results of field homogeneity and temporal stability at 77 K, performed on YP750 and those of a hybrid stack, YPB750, in which two YBCO bulk annuli, each Ø46 mm and 16-mm thick with a 25-mm bore, are added to YP750, one at the top and the other at the bottom. PMID:22081753

Cusp/cleft auroral activity in relation to solar wind dynamic pressure, interplanetary magnetic field B(sub z) and B(sub y)

NASA Technical Reports Server (NTRS)

Sandholt, P. E.; Farrugia, C. J.; Burlaga, L. F.; Holtet, J. A.; Moen, J.; Lybekk, B.; Jacobsen, B.; Opsvik, D.; Egeland, A.; Lepping, R.

1994-01-01

Continuous optical observations of cusp/cleft auroral activities within approximately equal to 09-15 MLT and 70-76 deg magnetic latitude are studied in relation to changes in solar wind dynamic pressure and interplanetary magnetic field (IMF) variability. The observed latitudinal movements of the cusp/cleft aurora in response to IMF B(sub z) changes may be explained as an effect of a variable magnetic field intensity in the outer dayside magnetosphere associated with the changing intensity of region 1 field-aligned currents and associated closure currents. Ground magnetic signatures related to such currents were observed in the present case (January 10, 1993). Strong, isolated enhancements in solar wind dynamic pressure (Delta p/p is greater than or equal to 0.5) gave rise to equatorward shifts of the cusp/cleft aurora, characteristic auroral transients, and distinct ground magnetic signatures of enhanced convection at cleft latitudes. A sequence of auroral events of approximately equal to 5-10 min recurrence time, moving eastward along the poleward boundary of the persistent cusp/cleft aurora in the approximately equal to 10-14 MLT sector, during negative IMF B(sub z) and B(sub y) conditions, were found to be correlated with brief pulses in solar wind dynamic pressure (0.1 is less than Delta p/p is less than 0.5). Simultaneous photometer observations from Ny Alesund, Svalbard, and Danmarkshavn, Greenland, show that the events often appeared on the prenoon side (approximately equal to 10-12 MLT), before moving into the postnoon sector in the case we study here, when IMF B(sub y) is less than 0. In other cases, similar auroral event sequences have been observed to move westward in the prenoon sector, during intervals of positive B(sub y). Thus a strong prenoon/postnoon asymmetry of event occurence and motion pattern related to the IMF B(sub y) polarity is observed. We find that this category of auroral event sequence is stimulated bursts of electron precipitation

Population dynamics in non-homogeneous environments

NASA Astrophysics Data System (ADS)

Alards, Kim M. J.; Tesser, Francesca; Toschi, Federico

2014-11-01

For organisms living in aquatic ecosystems the presence of fluid transport can have a strong influence on the dynamics of populations and on evolution of species. In particular, displacements due to self-propulsion, summed up with turbulent dispersion at larger scales, strongly influence the local densities and thus population and genetic dynamics. Real marine environments are furthermore characterized by a high degree of non-homogeneities. In the case of population fronts propagating in ``fast'' turbulence, with respect to the population duplication time, the flow effect can be studied by replacing the microscopic diffusivity with an effective turbulent diffusivity. In the opposite case of ``slow'' turbulence the advection by the flow has to be considered locally. Here we employ numerical simulations to study the influence of non-homogeneities in the diffusion coefficient of reacting individuals of different species expanding in a 2 dimensional space. Moreover, to explore the influence of advection, we consider a population expanding in the presence of simple velocity fields like cellular flows. The output is analyzed in terms of front roughness, front shape, propagation speed and, concerning the genetics, by means of heterozygosity and local and global extinction probabilities.

Centaurus Star-Forming Field Revisited

NASA Astrophysics Data System (ADS)

Kaltcheva, Nadia; Golev, V.; Moran, K.

2013-01-01

We analyze the structure of the star-forming field in Centaurus based on intermediate-band uvbyβ photometry of a large sample of O-B9 -stars. The derived precise homogeneous photometric distances and color excesses allow us to reveal spatially coherent groups and layers and to revise the membership and distance of the Cen OB1 association. In particular, we are seeking a correlation between the distribution of the massive OB-stars and that of ionized and neutral interstellar material that would allow a better understanding of the interactions among various ISM components in the Galactic stars-forming fields. For the purpose we combine the photometric findings with several multi-wavelength surveys (Wisconsin H-Alpha Mapper Northern Sky Survey, Southern H-Alpha Sky Survey Atlas, MSX Galactic Plane Survey, WISE All-Sky Data Release, CO survey of the Milky Way, and Southern Galactic Plane Survey). This allows us to map the OB-star distribution together with the super-shells of neutral and ionized material located toward Centaurus. Acknowledgments. This work was supported by NSF grant AST-0708950.

Testing the homogeneity of the Universe using gamma-ray bursts

NASA Astrophysics Data System (ADS)

Li, Ming-Hua; Lin, Hai-Nan

2015-10-01

Aims: The discovery of a statistically significant clustering in the distribution of gamma-ray bursts (GRBs) has recently been reported. Given that the cluster has a characteristic size of 2000-3000 Mpc and a redshift between 1.6 ≤ z ≤ 2.1, it has been claimed that this structure is incompatible with the cosmological principle of homogeneity and isotropy of our Universe. In this paper, we study the homogeneity of the GRB distribution using a subsample of the Greiner GRB catalogue, which contains 314 objects with redshift 0 < z < 2.5 (244 of them discovered by the Swift GRB mission). We try to reconcile the dilemma between the new observations and the current theory of structure formation and growth. Methods: To test the results against the possible biases in redshift determination and the incompleteness of the Greiner sample, we also apply our analysis to the 244 GRBs discovered by Swift and the subsample presented by the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS). The real space two-point correlation function (2PCF) of GRBs, ξ(r), is calculated using a Landy-Szalay estimator. We perform a standard least-χ2 fit to the measured 2PCFs of GRBs. We use the best-fit 2PCF to deduce a recently defined homogeneity scale. The homogeneity scale, RH, is defined as the comoving radius of the sphere inside which the number of GRBs N(1%, or equivalently above which the correlation dimension of the sample D2 is within 1% of D2 = 3. Results: For a flat ΛCDM Universe, a best-fit power law, ξ(r) = (r/r0)- γ, with the correlation length r0 = 413.64 ± 135.40 h-1 Mpc and slope γ = 1.57 ± 0.63 (at 1σ confidence level) for the real-space correlation function ξ(r) is obtained. We obtain a homogeneous distribution of GRBs with correlation dimension above D2 = 2.97 on scales of r ≥ 8200 h-1 Mpc. For the Swift subsample of 244 GRBs, the correlation length and slope are r0 = 387.51 ± 132.75 h-1 Mpc and γ = 1.57 ± 0.65 (at 1�

Soy Protein Isolate-Phosphatidylcholine Nanoemulsions Prepared Using High-Pressure Homogenization

PubMed Central

Li, Yang; Liu, Jun; Zhu, Ying; Zhang, Xiao-Yuan; Jiang, Lian-Zhou; Qi, Bao-Kun; Zhang, Xiao-Nan; Wang, Zhong-Jiang; Teng, Fei

2018-01-01

The nanoemulsions of soy protein isolate-phosphatidylcholine (SPI-PC) with different emulsion conditions were studied. Homogenization pressure and homogenization cycle times were varied, along with SPI and PC concentration. Evaluations included turbidity, particle size, ζ-potential, particle distribution index, and turbiscan stability index (TSI). The nanoemulsions had the best stability when SPI was at 1.5%, PC was at 0.22%, the homogenization pressure was 100 MPa and homogenization was performed 4 times. The average particle size of the SPI-PC nanoemulsions was 217 nm, the TSI was 3.02 and the emulsification yield was 93.4% of nanoemulsions. PMID:29735918

Soy Protein Isolate-Phosphatidylcholine Nanoemulsions Prepared Using High-Pressure Homogenization.

PubMed

Li, Yang; Wu, Chang-Ling; Liu, Jun; Zhu, Ying; Zhang, Xiao-Yuan; Jiang, Lian-Zhou; Qi, Bao-Kun; Zhang, Xiao-Nan; Wang, Zhong-Jiang; Teng, Fei

2018-05-07

The nanoemulsions of soy protein isolate-phosphatidylcholine (SPI-PC) with different emulsion conditions were studied. Homogenization pressure and homogenization cycle times were varied, along with SPI and PC concentration. Evaluations included turbidity, particle size, ζ-potential, particle distribution index, and turbiscan stability index (TSI). The nanoemulsions had the best stability when SPI was at 1.5%, PC was at 0.22%, the homogenization pressure was 100 MPa and homogenization was performed 4 times. The average particle size of the SPI-PC nanoemulsions was 217 nm, the TSI was 3.02 and the emulsification yield was 93.4% of nanoemulsions.

Axial resonances a$$_{1}$$(1260), b$$_{1}$$(1235) and their decays from the lattice

DOE PAGES

Lang, C. B.; Leskovec, Luka; Mohler, Daniel; ...

2014-04-28

The light axial-vector resonancesmore » $$a_1(1260)$$ and $$b_1(1235)$$ are explored in Nf=2 lattice QCD by simulating the corresponding scattering channels $$\\rho\\pi$$ and $$\\omega\\pi$$. Interpolating fields $$\\bar{q} q$$ and $$\\rho\\pi$$ or $$\\omega\\pi$$ are used to extract the s-wave phase shifts for the first time. The $$\\rho$$ and $$\\omega$$ are treated as stable and we argue that this is justified in the considered energy range and for our parameters $$m_\\pi\\simeq 266~$$MeV and $$L\\simeq 2~$$fm. We neglect other channels that would be open when using physical masses in continuum. Assuming a resonance interpretation a Breit-Wigner fit to the phase shift gives the $$a_1(1260)$$ resonance mass $$m_{a1}^{res}=1.435(53)(^{+0}_{-109})$$ GeV compared to $$m_{a1}^{exp}=1.230(40)$$ GeV. The $$a_1$$ width $$\\Gamma_{a1}(s)=g^2 p/s$$ is parametrized in terms of the coupling and we obtain $$g_{a_1\\rho\\pi}=1.71(39)$$ GeV compared to $$g_{a_1\\rho\\pi}^{exp}=1.35(30)$$ GeV derived from $$\\Gamma_{a1}^{exp}=425(175)$$ MeV. In the $$b_1$$ channel, we find energy levels related to $$\\pi(0)\\omega(0)$$ and $$b_1(1235)$$, and the lowest level is found at $$E_1 \\gtrsim m_\\omega+m_\\pi$$ but is within uncertainty also compatible with an attractive interaction. Lastly, assuming the coupling $$g_{b_1\\omega\\pi}$$ extracted from the experimental width we estimate $$m_{b_1}^{res}=1.414(36)(^{+0}_{-83})$$.« less

Compressibility Effects on the Passive Scalar Flux Within Homogeneous Turbulence

NASA Technical Reports Server (NTRS)

Blaisdell, G. A.; Mansour, N. N.; Reynolds, W. C.

1994-01-01

Compressibility effects on turbulent transport of a passive scalar are studied within homogeneous turbulence using a kinematic decomposition of the velocity field into solenoidal and dilatational parts. It is found that the dilatational velocity does not produce a passive scalar flux, and that all of the passive scalar flux is due to the solenoidal velocity.

Preference of Conjugated Bile Acids over Unconjugated Bile Acids as Substrates for OATP1B1 and OATP1B3

PubMed Central

Suga, Takahiro; Sato, Toshihiro; Maekawa, Masamitsu; Goto, Junichi; Mano, Nariyasu

2017-01-01

Bile acids, the metabolites of cholesterol, are signaling molecules that play critical role in many physiological functions. They undergo enterohepatic circulation through various transporters expressed in intestine and liver. Human organic anion-transporting polypeptides (OATP) 1B1 and OATP1B3 contribute to hepatic uptake of bile acids such as taurocholic acid. However, the transport properties of individual bile acids are not well understood. Therefore, we selected HEK293 cells overexpressing OATP1B1 and OATP1B3 to evaluate the transport of five major human bile acids (cholic acid, chenodeoxycholic acid, deoxycholic acid, ursodeoxycholic acid, lithocholic acid) together withtheir glycine and taurine conjugates via OATP1B1 and OATP1B3. The bile acids were quantified by liquid chromatography-tandem mass spectrometry. The present study revealed that cholic acid, chenodeoxyxcholic acid, and deoxycholic acid were transported by OATP1B1 and OATP1B3, while ursodeoxycholic acid and lithocholic acid were not significantly transported by OATPs. However, all the conjugated bile acids were taken up rapidly by OATP1B1 and OATP1B3. Kinetic analyses revealed the involvement of saturable OATP1B1- and OATP1B3-mediated transport of bile acids. The apparent Km values for OATP1B1 and OATP1B3 of the conjugated bile acids were similar (0.74–14.7 μM for OATP1B1 and 0.47–15.3 μM for OATP1B3). They exhibited higher affinity than cholic acid (47.1 μM for OATP1B1 and 42.2 μM for OATP1B3). Our results suggest that conjugated bile acids (glycine and taurine) are preferred to unconjugated bile acids as substrates for OATP1B1 and OATP1B3. PMID:28060902

Limit analysis of multi-layered plates. Part I: The homogenized Love-Kirchhoff model

NASA Astrophysics Data System (ADS)

Dallot, Julien; Sab, Karam

The purpose of this paper is to determine Gphom, the overall homogenized Love-Kirchhoff strength domain of a rigid perfectly plastic multi-layered plate, and to study the relationship between the 3D and the homogenized Love-Kirchhoff plate limit analysis problems. In the Love-Kirchhoff model, the generalized stresses are the in-plane (membrane) and the out-of-plane (flexural) stress field resultants. The homogenization method proposed by Bourgeois [1997. Modélisation numérique des panneaux structuraux légers. Ph.D. Thesis, University Aix-Marseille] and Sab [2003. Yield design of thin periodic plates by a homogenization technique and an application to masonry wall. C. R. Méc. 331, 641-646] for in-plane periodic rigid perfectly plastic plates is justified using the asymptotic expansion method. For laminated plates, an explicit parametric representation of the yield surface ∂Gphom is given thanks to the π-function (the plastic dissipation power density function) that describes the local strength domain at each point of the plate. This representation also provides a localization method for the determination of the 3D stress components corresponding to every generalized stress belonging to ∂Gphom. For a laminated plate described with a yield function of the form F(x3,σ)=σu(x3)F^(σ), where σu is a positive even function of the out-of-plane coordinate x3 and F^ is a convex function of the local stress σ, two effective constants and a normalization procedure are introduced. A symmetric sandwich plate consisting of two Von-Mises materials ( σu=σ1u in the skins and σu=σ2u in the core) is studied. It is found that, for small enough contrast ratios ( r=σ1u/σ2u≤5), the normalized strength domain G^phom is close to the one corresponding to a homogeneous Von-Mises plate [Ilyushin, A.-A., 1956. Plasticité. Eyrolles, Paris].

Association of Neuropeptide Y (NPY), Interleukin-1B (IL1B) Genetic Variants and Correlation of IL1B Transcript Levels with Vitiligo Susceptibility

PubMed Central

Laddha, Naresh C.; Dwivedi, Mitesh; Mansuri, Mohmmad Shoab; Singh, Mala; Patel, Hetanshi H.; Agarwal, Nishtha; Shah, Anish M.; Begum, Rasheedunnisa

2014-01-01

Background Vitiligo is a depigmenting disorder resulting from loss of functional melanocytes in the skin. NPY plays an important role in induction of immune response by acting on a variety of immune cells. NPY synthesis and release is governed by IL1B. Moreover, genetic variability in IL1B is reported to be associated with elevated NPY levels. Objectives Aim of the present study was to explore NPY promoter −399T/C (rs16147) and exon2 +1128T/C (rs16139) polymorphisms as well as IL1B promoter −511C/T (rs16944) polymorphism and to correlate IL1B transcript levels with vitiligo. Methods PCR-RFLP method was used to genotype NPY -399T/C SNP in 454 patients and 1226 controls; +1128T/C SNP in 575 patients and 1279 controls and IL1B −511C/T SNP in 448 patients and 785 controls from Gujarat. IL1B transcript levels in blood were also assessed in 105 controls and 95 patients using real-time PCR. Results Genotype and allele frequencies for NPY −399T/C, +1128T/C and IL1B −511C/T SNPs differed significantly (p<0.0001, p<0.0001; p = 0.0161, p = 0.0035 and p<0.0001, p<0.0001) between patients and controls. ‘TC’ haplotype containing minor alleles of NPY polymorphisms was significantly higher in patients and increased the risk of vitiligo by 2.3 fold (p<0.0001). Transcript levels of IL1B were significantly higher, in patients compared to controls (p = 0.0029), in patients with active than stable vitiligo (p = 0.015), also in female patients than male patients (p = 0.026). Genotype-phenotype correlation showed moderate association of IL1B -511C/T polymorphism with higher IL1B transcript levels. Trend analysis revealed significant difference between patients and controls for IL1B transcript levels with respect to different genotypes. Conclusion Our results suggest that NPY −399T/C, +1128T/C and IL1B −511C/T polymorphisms are associated with vitiligo and IL1B −511C/T SNP influences its transcript levels leading to increased risk for vitiligo in

Homogenous charge compression ignition engine having a cylinder including a high compression space

DOEpatents

Agama, Jorge R.; Fiveland, Scott B.; Maloney, Ronald P.; Faletti, James J.; Clarke, John M.

2003-12-30

The present invention relates generally to the field of homogeneous charge compression engines. In these engines, fuel is injected upstream or directly into the cylinder when the power piston is relatively close to its bottom dead center position. The fuel mixes with air in the cylinder as the power piston advances to create a relatively lean homogeneous mixture that preferably ignites when the power piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. Thus, the present invention divides the homogeneous charge between a controlled volume higher compression space and a lower compression space to better control the start of ignition.

26 CFR 1.681(b)-1 - Cross reference.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Cross reference. 1.681(b)-1 Section 1.681(b)-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Miscellaneous § 1.681(b)-1 Cross reference. For disallowance of certain charitable, etc...

Quantum Criticality of an Ising-like Spin-1 /2 Antiferromagnetic Chain in a Transverse Magnetic Field

NASA Astrophysics Data System (ADS)

Wang, Zhe; Lorenz, T.; Gorbunov, D. I.; Cong, P. T.; Kohama, Y.; Niesen, S.; Breunig, O.; Engelmayer, J.; Herman, A.; Wu, Jianda; Kindo, K.; Wosnitza, J.; Zherlitsyn, S.; Loidl, A.

2018-05-01

We report on magnetization, sound-velocity, and magnetocaloric-effect measurements of the Ising-like spin-1 /2 antiferromagnetic chain system BaCo2V2O8 as a function of temperature down to 1.3 K and an applied transverse magnetic field up to 60 T. While across the Néel temperature of TN˜5 K anomalies in magnetization and sound velocity confirm the antiferromagnetic ordering transition, at the lowest temperature the field-dependent measurements reveal a sharp softening of sound velocity v (B ) and a clear minimum of temperature T (B ) at B⊥c,3 D=21.4 T , indicating the suppression of the antiferromagnetic order. At higher fields, the T (B ) curve shows a broad minimum at B⊥c=40 T , accompanied by a broad minimum in the sound velocity and a saturationlike magnetization. These features signal a quantum phase transition, which is further characterized by the divergent behavior of the Grüneisen parameter ΓB∝(B -B⊥c)-1. By contrast, around the critical field, the Grüneisen parameter converges as temperature decreases, pointing to a quantum critical point of the one-dimensional transverse-field Ising model.

Compositional homogeneity and X-ray topographic analyses of CdTe xSe 1-x grown by the vertical Bridgman technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.

2015-02-01

We grew CdTe xSe 1-x crystals with nominal Se concentrations of 5%, 7%, and 10% by the vertical Bridgman technique, and evaluated their compositional homogeneity and structural quality at the NSLS’ X-ray fluorescence and white beam X-ray topography beam lines. Both X-ray fluorescence and photoluminescence mapping revealed very high compositional homogeneity of the CdTe xSe 1-x crystals. Here, we noted that those crystals with higher concentrations of Se were more prone to twinning than those with a lower content. The crystals were fairly free from strains and contained low concentrations of sub-grain boundaries and their networks.

Hypersurface Homogeneous Cosmological Model in Modified Theory of Gravitation

NASA Astrophysics Data System (ADS)

Katore, S. D.; Hatkar, S. P.; Baxi, R. J.

2016-12-01

We study a hypersurface homogeneous space-time in the framework of the f (R, T) theory of gravitation in the presence of a perfect fluid. Exact solutions of field equations are obtained for exponential and power law volumetric expansions. We also solve the field equations by assuming the proportionality relation between the shear scalar (σ ) and the expansion scalar (θ ). It is observed that in the exponential model, the universe approaches isotropy at large time (late universe). The investigated model is notably accelerating and expanding. The physical and geometrical properties of the investigated model are also discussed.

Homogeneous anisotropic solutions of topologically massive gravity with a cosmological constant and their homogeneous deformations

NASA Astrophysics Data System (ADS)

Moutsopoulos, George

2013-06-01

We solve the equations of topologically massive gravity (TMG) with a potentially non-vanishing cosmological constant for homogeneous metrics without isotropy. We only reproduce known solutions. We also discuss their homogeneous deformations, possibly with isotropy. We show that de Sitter space and hyperbolic space cannot be infinitesimally homogeneously deformed in TMG. We clarify some of their Segre-Petrov types and discuss the warped de Sitter spacetime.

The ratio of B-field and dB/dt time constants from time-domain electromagnetic data: a new tool for estimating size and conductivity of mineral deposits

NASA Astrophysics Data System (ADS)

Guo, Kun; Mungall, James E.; Smith, Richard S.

2013-09-01

A discrete conductive sphere model in which current paths are constrained to a single planar orientation (the `dipping sphere') is used to calculate the secondary response from Geotech Ltd's VTEM airborne time domain electromagnetic (EM) system. In addition to calculating the time constants of the B-field and dB/dt responses, we focus on the time-constant ratio at a late time interval and compare numerical results with several field examples. For very strong conductors with conductivity above a critical value, both the B-field and dB/dt responses show decreasing values as the conductivity increases. Therefore response does not uniquely define conductivity. However, calculation of time constants for the decay removes the ambiguity and allows discrimination of high and low conductivity targets. A further benefit is gained by comparing the time constants of the B-field and dB/dt decays, which co-vary systematically over a wide range of target conductance. An advantage of calculating time constant ratios is that the ratios are insensitive to the dip and the depth of the targets and are stable across the conductor. Therefore we propose to use their ratio rτ=τB/τdB/dt as a tool to estimate the size and conductivity of mineral deposits. Using the VTEM base frequency, the magnitude of rτ reaches a limiting value of 1.32 for the most highly conductive targets. Interpretations become more complicated in the presence of conductive overburden, which appears to cause the limiting value of rτ to increase to 2 or more.

High yield bacterial expression, purification and characterisation of bioactive Human Tousled-like Kinase 1B involved in cancer.

PubMed

Bhoir, Siddhant; Shaik, Althaf; Thiruvenkatam, Vijay; Kirubakaran, Sivapriya

2018-03-19

Human Tousled-like kinases (TLKs) are highly conserved serine/threonine protein kinases responsible for cell proliferation, DNA repair, and genome surveillance. Their possible involvement in cancer via efficient DNA repair mechanisms have made them clinically relevant molecular targets for anticancer therapy. Innovative approaches in chemical biology have played a key role in validating the importance of kinases as molecular targets. However, the detailed understanding of the protein structure and the mechanisms of protein-drug interaction through biochemical and biophysical techniques demands a method for the production of an active protein of exceptional stability and purity on a large scale. We have designed a bacterial expression system to express and purify biologically active, wild-type Human Tousled-like Kinase 1B (hTLK1B) by co-expression with the protein phosphatase from bacteriophage λ. We have obtained remarkably high amounts of the soluble and homogeneously dephosphorylated form of biologically active hTLK1B with our unique, custom-built vector design strategy. The recombinant hTLK1B can be used for the structural studies and may further facilitate the development of new TLK inhibitors for anti-cancer therapy using a structure-based drug design approach.