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Sample records for high-resolution magnetic tweezer

  1. A high-resolution magnetic tweezer for single-molecule measurements

    PubMed Central

    Kim, Kipom; Saleh, Omar A.

    2009-01-01

    Magnetic tweezers (MT) are single-molecule manipulation instruments that utilize a magnetic field to apply force to a biomolecule-tethered magnetic bead while using optical bead tracking to measure the biomolecule’s extension. While relatively simple to set up, prior MT implementations have lacked the resolution necessary to observe sub-nanometer biomolecular configuration changes. Here, we demonstrate a reflection-interference technique for bead tracking, and show that it has much better resolution than traditional diffraction-based systems. We enhance the resolution by fabricating optical coatings on all reflecting surfaces that optimize the intensity and contrast of the interference image, and we implement feedback control of the focal position to remove drift. To test the system, we measure the length change of a DNA hairpin as it undergoes a folding/unfolding transition. PMID:19729511

  2. High-Resolution Optical Tweezers for Single-Molecule Manipulation

    PubMed Central

    Zhang, Xinming; Ma, Lu; Zhang, Yongli

    2013-01-01

    Forces hold everything together and determine its structure and dynamics. In particular, tiny forces of 1-100 piconewtons govern the structures and dynamics of biomacromolecules. These forces enable folding, assembly, conformational fluctuations, or directional movements of biomacromolecules over sub-nanometer to micron distances. Optical tweezers have become a revolutionary tool to probe the forces, structures, and dynamics associated with biomacromolecules at a single-molecule level with unprecedented resolution. In this review, we introduce the basic principles of optical tweezers and their latest applications in studies of protein folding and molecular motors. We describe the folding dynamics of two strong coiled coil proteins, the GCN4-derived protein pIL and the SNARE complex. Both complexes show multiple folding intermediates and pathways. ATP-dependent chromatin remodeling complexes translocate DNA to remodel chromatin structures. The detailed DNA translocation properties of such molecular motors have recently been characterized by optical tweezers, which are reviewed here. Finally, several future developments and applications of optical tweezers are discussed. These past and future applications demonstrate the unique advantages of high-resolution optical tweezers in quantitatively characterizing complex multi-scale dynamics of biomacromolecules. PMID:24058311

  3. Magnetic tweezers microscope for cellular manipulation

    NASA Astrophysics Data System (ADS)

    Dong, Chen-Yuan; Huang, Hayden; Sutin, Jason D. B.; Kwon, Hyuk-Sang; Cragg, George E.; Gilbert, R.; Lee, Richard T.; Gratton, Enrico; Kamm, Roger D.; Lauffenburger, Douglas A.; So, Peter T. C.

    2000-04-01

    We present the design of a magnetic tweezers microscope for cellular manipulation. Our design allows versatile and significant 3D stress application over a large sample region. For linear force application, forces up to 250 pN per 4.5 micrometers magnetic bead can be applied. Finite element analysis shows that variance in force level is around 10 percent within an area of 300 X 300 micrometers 2. Our eight-pole design potentially allows 3D liner force application and exertion of torsional stress. Furthermore, our design allows high resolution imaging using high numerical aperture objective. Both finite element analysis of magnetic field distribution and force calibration of our design are presented. As a feasibility study, we incubated fibronectin coated 4.5 micrometers polystyrene beads with Swiss 3T3 mouse fibroblast cells. Under application around 250 pN of force per magnetic particle, we observed relative movement between attached magnetic and polystyrene beads to be on the order of 1 micrometers . Elastic, viscoelastic, and creeping responses of cell surfaces were observed. Our results are consistent with previous observations using similar magnetic techniques.

  4. High-resolution dual-trap optical tweezers with differential detection: alignment of instrument components.

    PubMed

    Bustamante, Carlos; Chemla, Yann R; Moffitt, Jeffrey R

    2009-10-01

    Optical traps or "optical tweezers" have become an indispensable tool in understanding fundamental biological processes. Using our design, a dual-trap optical tweezers with differential detection, we can detect length changes to a DNA molecule tethering the trapped beads of 1 bp. By forming two traps from the same laser and maximizing the common optical paths of the two trapping beams, we decouple the instrument from many sources of environmental and instrumental noise that typically limit spatial resolution. The performance of a high-resolution instrument--the formation of strong traps, the minimization of background signals from trap movements, or the mitigation of the axial coupling, for example--can be greatly improved through careful alignment. This procedure, which is described in this article, starts from the laser and advances through the instrument, component by component. Alignment is complicated by the fact that the trapping light is in the near infrared (NIR) spectrum. Standard infrared viewing cards are commonly used to locate the beam, but unfortunately, bleach quickly. As an alternative, we use an IR-viewing charge-coupled device (CCD) camera equipped with a C-mount telephoto lens and display its image on a monitor. By visualizing the scattered light on a pair of irises of identical height separated by >12 in., the beam direction can be set very accurately along a fixed axis. PMID:20147041

  5. Magnetic Tweezers for the Measurement of Twist and Torque

    PubMed Central

    Lipfert, Jan; Lee, Mina; Ordu, Orkide; Kerssemakers, Jacob W. J.; Dekker, Nynke H.

    2014-01-01

    Single-molecule techniques make it possible to investigate the behavior of individual biological molecules in solution in real time. These techniques include so-called force spectroscopy approaches such as atomic force microscopy, optical tweezers, flow stretching, and magnetic tweezers. Amongst these approaches, magnetic tweezers have distinguished themselves by their ability to apply torque while maintaining a constant stretching force. Here, it is illustrated how such a “conventional” magnetic tweezers experimental configuration can, through a straightforward modification of its field configuration to minimize the magnitude of the transverse field, be adapted to measure the degree of twist in a biological molecule. The resulting configuration is termed the freely-orbiting magnetic tweezers. Additionally, it is shown how further modification of the field configuration can yield a transverse field with a magnitude intermediate between that of the “conventional” magnetic tweezers and the freely-orbiting magnetic tweezers, which makes it possible to directly measure the torque stored in a biological molecule. This configuration is termed the magnetic torque tweezers. The accompanying video explains in detail how the conversion of conventional magnetic tweezers into freely-orbiting magnetic tweezers and magnetic torque tweezers can be accomplished, and demonstrates the use of these techniques. These adaptations maintain all the strengths of conventional magnetic tweezers while greatly expanding the versatility of this powerful instrument. PMID:24894412

  6. Probing Protein Folding Kinetics with High-resolution, Stabilized Optical Tweezers

    NASA Astrophysics Data System (ADS)

    Wong, Wesley; Halvorsen, Ken

    2009-03-01

    Single-molecule techniques provide a powerful means of exploring molecular transitions such as the unfolding and refolding of a protein. However, the quantification of bi-directional transitions and near-equilibrium phenomena poses unique challenges, and is often limited by the detection resolution and long-term stability of the instrument. We have developed unique optical tweezers methods that address these problems, including an interference-based method for high-resolution 3D bead tracking (˜1 nm laterally, ˜0.3 nm vertically, at > 100 Hz), and a continuous autofocus system that stabilizes the trap height to within 1-2 nm longterm [1,2]. We have used our instruments to quantify the force-dependent unfolding and refolding kinetics of single protein domains (e.g. spectrin in collaboration with E. Evans). These single-molecule studies are presented, together with the accompanying probabilistic analysis that we have developed. References: 1. W.P. Wong, V. Heinrich, E. Evans, Mat. Res. Soc. Symp. Proc., 790, P5.1-P5.10 (2004). 2. V. Heinrich, W.P. Wong, K. Halvorsen, E. Evans, Langmuir, 24, 1194-1203 (2008).

  7. A force calibration standard for magnetic tweezers

    NASA Astrophysics Data System (ADS)

    Yu, Zhongbo; Dulin, David; Cnossen, Jelmer; Köber, Mariana; van Oene, Maarten M.; Ordu, Orkide; Berghuis, Bojk A.; Hensgens, Toivo; Lipfert, Jan; Dekker, Nynke H.

    2014-12-01

    To study the behavior of biological macromolecules and enzymatic reactions under force, advances in single-molecule force spectroscopy have proven instrumental. Magnetic tweezers form one of the most powerful of these techniques, due to their overall simplicity, non-invasive character, potential for high throughput measurements, and large force range. Drawbacks of magnetic tweezers, however, are that accurate determination of the applied forces can be challenging for short biomolecules at high forces and very time-consuming for long tethers at low forces below ˜1 piconewton. Here, we address these drawbacks by presenting a calibration standard for magnetic tweezers consisting of measured forces for four magnet configurations. Each such configuration is calibrated for two commonly employed commercially available magnetic microspheres. We calculate forces in both time and spectral domains by analyzing bead fluctuations. The resulting calibration curves, validated through the use of different algorithms that yield close agreement in their determination of the applied forces, span a range from 100 piconewtons down to tens of femtonewtons. These generalized force calibrations will serve as a convenient resource for magnetic tweezers users and diminish variations between different experimental configurations or laboratories.

  8. Single molecule studies of helicases with magnetic tweezers.

    PubMed

    Hodeib, Samar; Raj, Saurabh; Manosas, M; Zhang, Weiting; Bagchi, Debjani; Ducos, Bertrand; Allemand, Jean-François; Bensimon, David; Croquette, Vincent

    2016-08-01

    Helicases are a broad family of enzymes that perform crucial functions in DNA replication and in the maintenance of DNA and RNA integrity. A detailed mechanical study of helicases on DNA and RNA is possible using single molecule manipulation methods. Among those, magnetic tweezers (or traps) present a convenient, moderate throughput assay (tens of enzymes can be monitored simultaneously) that allow for high resolution (single base-pair) studies of these enzymes in various conditions and on various substrates (double and single stranded DNA and RNA). Here we discuss various implementation of the basic assay relevant for these studies. PMID:27371121

  9. Quantitative Modeling and Optimization of Magnetic Tweezers

    PubMed Central

    Lipfert, Jan; Hao, Xiaomin; Dekker, Nynke H.

    2009-01-01

    Abstract Magnetic tweezers are a powerful tool to manipulate single DNA or RNA molecules and to study nucleic acid-protein interactions in real time. Here, we have modeled the magnetic fields of permanent magnets in magnetic tweezers and computed the forces exerted on superparamagnetic beads from first principles. For simple, symmetric geometries the magnetic fields can be calculated semianalytically using the Biot-Savart law. For complicated geometries and in the presence of an iron yoke, we employ a finite-element three-dimensional PDE solver to numerically solve the magnetostatic problem. The theoretical predictions are in quantitative agreement with direct Hall-probe measurements of the magnetic field and with measurements of the force exerted on DNA-tethered beads. Using these predictive theories, we systematically explore the effects of magnet alignment, magnet spacing, magnet size, and of adding an iron yoke to the magnets on the forces that can be exerted on tethered particles. We find that the optimal configuration for maximal stretching forces is a vertically aligned pair of magnets, with a minimal gap between the magnets and minimal flow cell thickness. Following these principles, we present a configuration that allows one to apply ≥40 pN stretching forces on ≈1-μm tethered beads. PMID:19527664

  10. Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy

    PubMed Central

    Neuman, Keir C.; Nagy, Attila

    2012-01-01

    Single-molecule force spectroscopy has emerged as a powerful tool to investigate the forces and motions associated with biological molecules and enzymatic activity. The most common force spectroscopy techniques are optical tweezers, magnetic tweezers and atomic force microscopy. These techniques are described and illustrated with examples highlighting current capabilities and limitations. PMID:18511917

  11. Magnetic tweezers for manipulation of magnetic particles in single cells

    NASA Astrophysics Data System (ADS)

    Ebrahimian, H.; Giesguth, M.; Dietz, K.-J.; Reiss, G.; Herth, S.

    2014-02-01

    Magnetic tweezers gain increasing interest for applications in biology. Here, a setup of magnetic tweezers is introduced using micropatterned conducting lines on transparent glass slides. Magnetic particles of 1 μm diameter were injected in barley cell vacuoles using a microinject system under microscopic control. Time dependent tracking of the particles after application of a magnetic field was used to determine the viscosity of vacuolar sap in vivo relative to water and isolated vacuolar fluid. The viscosity of vacuolar sap in cells was about 2-fold higher than that of extracted vacuolar fluid and 5 times higher than that of water.

  12. Extending the Range for Force Calibration in Magnetic Tweezers

    PubMed Central

    Daldrop, Peter; Brutzer, Hergen; Huhle, Alexander; Kauert, Dominik J.; Seidel, Ralf

    2015-01-01

    Magnetic tweezers are a wide-spread tool used to study the mechanics and the function of a large variety of biomolecules and biomolecular machines. This tool uses a magnetic particle and a strong magnetic field gradient to apply defined forces to the molecule of interest. Forces are typically quantified by analyzing the lateral fluctuations of the biomolecule-tethered particle in the direction perpendicular to the applied force. Since the magnetic field pins the anisotropy axis of the particle, the lateral fluctuations follow the geometry of a pendulum with a short pendulum length along and a long pendulum length perpendicular to the field lines. Typically, the short pendulum geometry is used for force calibration by power-spectral-density (PSD) analysis, because the movement of the bead in this direction can be approximated by a simple translational motion. Here, we provide a detailed analysis of the fluctuations according to the long pendulum geometry and show that for this direction, both the translational and the rotational motions of the particle have to be considered. We provide analytical formulas for the PSD of this coupled system that agree well with PSDs obtained in experiments and simulations and that finally allow a faithful quantification of the magnetic force for the long pendulum geometry. We furthermore demonstrate that this methodology allows the calibration of much larger forces than the short pendulum geometry in a tether-length-dependent manner. In addition, the accuracy of determination of the absolute force is improved. Our force calibration based on the long pendulum geometry will facilitate high-resolution magnetic-tweezers experiments that rely on short molecules and large forces, as well as highly parallelized measurements that use low frame rates. PMID:25992733

  13. Extending the range for force calibration in magnetic tweezers.

    PubMed

    Daldrop, Peter; Brutzer, Hergen; Huhle, Alexander; Kauert, Dominik J; Seidel, Ralf

    2015-05-19

    Magnetic tweezers are a wide-spread tool used to study the mechanics and the function of a large variety of biomolecules and biomolecular machines. This tool uses a magnetic particle and a strong magnetic field gradient to apply defined forces to the molecule of interest. Forces are typically quantified by analyzing the lateral fluctuations of the biomolecule-tethered particle in the direction perpendicular to the applied force. Since the magnetic field pins the anisotropy axis of the particle, the lateral fluctuations follow the geometry of a pendulum with a short pendulum length along and a long pendulum length perpendicular to the field lines. Typically, the short pendulum geometry is used for force calibration by power-spectral-density (PSD) analysis, because the movement of the bead in this direction can be approximated by a simple translational motion. Here, we provide a detailed analysis of the fluctuations according to the long pendulum geometry and show that for this direction, both the translational and the rotational motions of the particle have to be considered. We provide analytical formulas for the PSD of this coupled system that agree well with PSDs obtained in experiments and simulations and that finally allow a faithful quantification of the magnetic force for the long pendulum geometry. We furthermore demonstrate that this methodology allows the calibration of much larger forces than the short pendulum geometry in a tether-length-dependent manner. In addition, the accuracy of determination of the absolute force is improved. Our force calibration based on the long pendulum geometry will facilitate high-resolution magnetic-tweezers experiments that rely on short molecules and large forces, as well as highly parallelized measurements that use low frame rates. PMID:25992733

  14. Combined versatile high-resolution optical tweezers and single-molecule fluorescence microscopy

    PubMed Central

    Sirinakis, George; Ren, Yuxuan; Gao, Ying; Xi, Zhiqun; Zhang, Yongli

    2012-01-01

    Optical trapping and single-molecule fluorescence are two major single-molecule approaches. Their combination has begun to show greater capability to study more complex systems than either method alone, but met many fundamental and technical challenges. We built an instrument that combines base-pair resolution dual-trap optical tweezers with single-molecule fluorescence microscopy. The instrument has complementary design and functionalities compared with similar microscopes previously described. The optical tweezers can be operated in constant force mode for easy data interpretation or in variable force mode for maximum spatiotemporal resolution. The single-molecule fluorescence detection can be implemented in either wide-field or confocal imaging configuration. To demonstrate the capabilities of the new instrument, we imaged a single stretched λ DNA molecule and investigated the dynamics of a DNA hairpin molecule in the presence of fluorophore-labeled complementary oligonucleotide. We simultaneously observed changes in the fluorescence signal and pauses in fast extension hopping of the hairpin due to association and dissociation of individual oligonucleotides. The combined versatile microscopy allows for greater flexibility to study molecular machines or assemblies at a single-molecule level. PMID:23020384

  15. Magnetic Forces and DNA Mechanics in Multiplexed Magnetic Tweezers

    PubMed Central

    van Loenhout, Marijn T. J.; Burnham, Daniel R.; Dekker, Cees

    2012-01-01

    Magnetic tweezers (MT) are a powerful tool for the study of DNA-enzyme interactions. Both the magnet-based manipulation and the camera-based detection used in MT are well suited for multiplexed measurements. Here, we systematically address challenges related to scaling of multiplexed magnetic tweezers (MMT) towards high levels of parallelization where large numbers of molecules (say 103) are addressed in the same amount of time required by a single-molecule measurement. We apply offline analysis of recorded images and show that this approach provides a scalable solution for parallel tracking of the xyz-positions of many beads simultaneously. We employ a large field-of-view imaging system to address many DNA-bead tethers in parallel. We model the 3D magnetic field generated by the magnets and derive the magnetic force experienced by DNA-bead tethers across the large field of view from first principles. We furthermore experimentally demonstrate that a DNA-bead tether subject to a rotating magnetic field describes a bicircular, Limaçon rotation pattern and that an analysis of this pattern simultaneously yields information about the force angle and the position of attachment of the DNA on the bead. Finally, we apply MMT in the high-throughput investigation of the distribution of the induced magnetic moment, the position of attachment of DNA on the beads, and DNA flexibility. The methods described herein pave the way to kilo-molecule level magnetic tweezers experiments. PMID:22870220

  16. High-resolution detection of Brownian motion for quantitative optical tweezers experiments.

    PubMed

    Grimm, Matthias; Franosch, Thomas; Jeney, Sylvia

    2012-08-01

    We have developed an in situ method to calibrate optical tweezers experiments and simultaneously measure the size of the trapped particle or the viscosity of the surrounding fluid. The positional fluctuations of the trapped particle are recorded with a high-bandwidth photodetector. We compute the mean-square displacement, as well as the velocity autocorrelation function of the sphere, and compare it to the theory of Brownian motion including hydrodynamic memory effects. A careful measurement and analysis of the time scales characterizing the dynamics of the harmonically bound sphere fluctuating in a viscous medium directly yields all relevant parameters. Finally, we test the method for different optical trap strengths, with different bead sizes and in different fluids, and we find excellent agreement with the values provided by the manufacturers. The proposed approach overcomes the most commonly encountered limitations in precision when analyzing the power spectrum of position fluctuations in the region around the corner frequency. These low frequencies are usually prone to errors due to drift, limitations in the detection, and trap linearity as well as short acquisition times resulting in poor statistics. Furthermore, the strategy can be generalized to Brownian motion in more complex environments, provided the adequate theories are available. PMID:23005790

  17. High Spatiotemporal-Resolution Magnetic Tweezers: Calibration and Applications for DNA Dynamics.

    PubMed

    Dulin, David; Cui, Tao Ju; Cnossen, Jelmer; Docter, Margreet W; Lipfert, Jan; Dekker, Nynke H

    2015-11-17

    The observation of biological processes at the molecular scale in real time requires high spatial and temporal resolution. Magnetic tweezers are straightforward to implement, free of radiation or photodamage, and provide ample multiplexing capability, but their spatiotemporal resolution has lagged behind that of other single-molecule manipulation techniques, notably optical tweezers and AFM. Here, we present, to our knowledge, a new high-resolution magnetic tweezers apparatus. We systematically characterize the achievable spatiotemporal resolution for both incoherent and coherent light sources, different types and sizes of beads, and different types and lengths of tethered molecules. Using a bright coherent laser source for illumination and tracking at 6 kHz, we resolve 3 Å steps with a 1 s period for surface-melted beads and 5 Å steps with a 0.5 s period for double-stranded-dsDNA-tethered beads, in good agreement with a model of stochastic bead motion in the magnetic tweezers. We demonstrate how this instrument can be used to monitor the opening and closing of a DNA hairpin on millisecond timescales in real time, together with attendant changes in the hairpin dynamics upon the addition of deoxythymidine triphosphate. Our approach opens up the possibility of observing biological events at submillisecond timescales with subnanometer resolution using camera-based detection. PMID:26588570

  18. High-Resolution Nuclear Magnetic Resonance of Solids.

    ERIC Educational Resources Information Center

    Maciel, Gary E.

    1984-01-01

    Examines recent developments in techniques for obtaining high-resolution nuclear magnetic resonance (NMR) spectra on solid samples, discussing the kinds of applications for which these techniques are well suited. Also discusses the characteristics of NMR of solids and generating magnetization for NMR in solids. (JN)

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

    SciTech Connect

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

    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 proposed 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.

  20. Clinical applications of high-resolution ocular magnetic resonance imaging.

    PubMed

    Tanitame, Keizo; Sone, Takashi; Kiuchi, Yoshiaki; Awai, Kazuo

    2012-11-01

    Magnetic resonance imaging (MRI) using fast sequences with subjects staring at a target can provide motion-free ocular images, and small receiver surface coils make it possible to produce ocular images with high spatial resolution. MRI using half-Fourier single-shot rapid acquisition with a relaxation enhancement sequence as a fast T2-weighted imaging yields useful images for the morphologic diagnosis of ocular diseases, and MRI using a fast spoiled gradient-recalled-echo sequence as a T1-weighted imaging yields additional information by the administration of gadolinium-based contrast material for assessing the vascularity of intraocular tumors. These ocular imaging techniques are useful for the evaluation of patients with angle closure glaucoma, congenital abnormality of ocular globes, intraocular tumors and several types of detachments, as well as patients after ocular surgery. In this pictorial essay, we demonstrate the clinical applications of fast high-resolution ocular MRI with fixation of the subjects' visual foci. PMID:22923185

  1. High-resolution breath-hold cardiac magnetic resonance imaging

    SciTech Connect

    Liu, Yu.

    1993-01-01

    This dissertation work is composed of investigations of three methods for fast cardiac magnetic resonance imaging (MRI). These methods include (1) 2D breath-hold magnetization prepared gradient echo and fast spin-echo (FSE) cardiac imaging, (2) 3D breath-hold magnetization prepared gradient echo cardiac imaging, and (3) real-time monitoring, feedback, and triggering for breath-hold MRI. The hypothesis of this work is that high resolution 2D and 3D magnetic resonance data sets for the heart can be acquired with the combination of magnetization prepared blood suppression for gradient echo techniques and accurate breath-holding methods. The 2D method included development of magnetic resonance data acquisition for cardiac imaging. The acquisition time is within a single breath-hold of 16 seconds (assuming heart 60/min). The data acquisition is synchronized with the electrocardiogram signal. Based on consistent observations of specific small cardiac structures like the papillary muscle, trabeculae, moderator band, and coronary vessels in studies of normal volunteers, the image quality represents a significant improvement over that obtained with fast imaging methods previously. To further improve the image quality provided by the 2D method, the first 3D cardiac MRI technique was developed. This method provides even better spatial resolution for cardiac images, with a voxel size of 1.09 [times] 2.19 [times] 4 mm[sup 3]. A 3D acquisition is completed in 8 breath-holds. The data acquisition for 3D cardiac imaging requires a consistent breath-hold position to avoid respiratory artifacts. To improve the reliability of the 3DFT acquisition, a new technique called MR breath-hold feedback was developed to provide reproducible breathholding. The diaphragm location is used as the index for breath-hold reproducibility measurement. The range of the diaphragm displacement in different breath-hold is reduced from 8.3 mm without the technique, to 1.3 mm with the technique.

  2. Near-field-magnetic-tweezer manipulation of single DNA molecules.

    PubMed

    Yan, Jie; Skoko, Dunja; Marko, John F

    2004-07-01

    We have developed an instrument for micromanipulation of single DNA molecules end labeled with 3-microm-diameter paramagnetic particles. A small, permanent magnet that can be moved as close as 10 microm to the particle being manipulated can generate forces in excess of 200 pN, significantly larger than obtained in other recent "magnetic-tweezer" studies. Our instrument generates these forces in the focal plane of a microscope objective, allowing straightforward real-time observation of molecule extension with a position resolution of approximately 30 nm. We show how our magnetic manipulation system can be combined with manipulation and force measurement using glass micropipettes to allow rapid switching between measurements in fixed-force and fixed-extension ensembles. We demonstrate the use of our system to study formation of DNA loops by an enzyme which strongly binds two copies of a specific 6-base-pair sequence. PMID:15324086

  3. Skewed Brownian Fluctuations in Single-Molecule Magnetic Tweezers

    PubMed Central

    Burnham, Daniel R.; De Vlaminck, Iwijn; Henighan, Thomas; Dekker, Cees

    2014-01-01

    Measurements in magnetic tweezers rely upon precise determination of the position of a magnetic microsphere. Fluctuations in the position due to Brownian motion allows calculation of the applied force, enabling deduction of the force-extension response function for a single DNA molecule that is attached to the microsphere. The standard approach relies upon using the mean of position fluctuations, which is valid when the microsphere axial position fluctuations obey a normal distribution. However, here we demonstrate that nearby surfaces and the non-linear elasticity of DNA can skew the distribution. Through experiment and simulations, we show that such a skewing leads to inaccurate position measurements which significantly affect the extracted DNA extension and mechanical properties, leading to up to two-fold errors in measured DNA persistence length. We develop a simple, robust and easily implemented method to correct for such mismeasurements. PMID:25265383

  4. Line broadening interference for high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields

    SciTech Connect

    Wei, Zhiliang; Yang, Jian; Lin, Yanqin E-mail: chenz@xmu.edu.cn; Chen, Zhong E-mail: chenz@xmu.edu.cn; Chen, Youhe

    2015-04-07

    Nuclear magnetic resonance spectroscopy serves as an important tool for analyzing chemicals and biological metabolites. However, its performance is subject to the magnetic-field homogeneity. Under inhomogeneous fields, peaks are broadened to overlap each other, introducing difficulties for assignments. Here, we propose a method termed as line broadening interference (LBI) to provide high-resolution information under inhomogeneous magnetic fields by employing certain gradients in the indirect dimension to interfere the magnetic-field inhomogeneity. The conventional spectral-line broadening is thus interfered to be non-diagonal, avoiding the overlapping among adjacent resonances. Furthermore, an inhomogeneity correction algorithm is developed based on pattern recognition to recover the high-resolution information from LBI spectra. Theoretical deductions are performed to offer systematic and detailed analyses on the proposed method. Moreover, experiments are conducted to prove the feasibility of the proposed method for yielding high-resolution spectra in inhomogeneous magnetic fields.

  5. Structure and dynamics of single DNA molecules manipulated by magnetic tweezers and or flow

    PubMed Central

    Leuba, Sanford H.; Wheeler, Travis B.; Cheng, Chao-Min; LeDuc, Philip R.; Fernández-Sierra, Mónica; Quiñones, Edwin

    2009-01-01

    Here we describe experiments which employ magnetic tweezers and or microfluidics to manipulate single DNA molecules. We describe the use of magnetic tweezers coupled to an inverted microscope as well as the use of a magnetic tweezers setup with an upright microscope. Using a chamber prepared via soft lithography, we also describe a microfluidic device for the manipulation of individual DNA molecules. Finally, we present some past successful examples of using these approaches to elucidate unique information about protein-nucleic acid interactions. PMID:19015032

  6. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications.

    PubMed

    Zacchia, Nicholas A; Valentine, Megan T

    2015-05-01

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy. PMID:26026529

  7. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    SciTech Connect

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-15

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  8. High-Resolution Vertical Observation of Intracellular Structure Using Magnetically Responsive Microplates.

    PubMed

    Teshima, Tetsuhiko; Onoe, Hiroaki; Tottori, Soichiro; Aonuma, Hiroka; Mizutani, Takeomi; Kamiya, Koki; Ishihara, Hirotaka; Kanuka, Hirotaka; Takeuchi, Shoji

    2016-07-01

    A vertical confocal observation system capable of high-resolution observation of intracellular structure is demonstrated. The system consists of magnet-active microplates to rotate, incline, and translate single adherent cells in the applied magnetic field. Appended to conventional confocal microscopes, this system enables high-resolution cross-sectional imaging with single-molecule sensitivity in single scanning. PMID:27185344

  9. Simple horizontal magnetic tweezers for micromanipulation of single DNA molecules and DNA-protein complexes.

    PubMed

    McAndrew, Christopher P; Tyson, Christopher; Zischkau, Joseph; Mehl, Patrick; Tuma, Pamela L; Pegg, Ian L; Sarkar, Abhijit

    2016-01-01

    We report the development of a simple-to-implement magnetic force transducer that can apply a wide range of piconewton (pN) scale forces on single DNA molecules and DNA-protein complexes in the horizontal plane. The resulting low-noise force-extension data enable very high-resolution detection of changes in the DNA tether's extension: ~0.05 pN in force and <10 nm change in extension. We have also verified that we can manipulate DNA in near equilibrium conditions through the wide range of forces by ramping the force from low to high and back again, and observing minimal hysteresis in the molecule's force response. Using a calibration technique based on Stokes' drag law, we have confirmed our force measurements from DNA force-extension experiments obtained using the fluctuation-dissipation theorem applied to transverse fluctuations of the magnetic microsphere. We present data on the force-distance characteristics of a DNA molecule complexed with histones. The results illustrate how the tweezers can be used to study DNA binding proteins at the single molecule level. PMID:26757808

  10. Simple horizontal magnetic tweezers for micromanipulation of single DNA molecules and DNA–protein complexes

    PubMed Central

    McAndrew, Christopher P.; Tyson, Christopher; Zischkau, Joseph; Mehl, Patrick; Tuma, Pamela L.; Pegg, Ian L.; Sarkar, Abhijit

    2016-01-01

    We report the development of a simple-to-implement magnetic force transducer that can apply a wide range of piconewton (pN) scale forces on single DNA molecules and DNA–protein complexes in the horizontal plane. The resulting low-noise force-extension data enable very high-resolution detection of changes in the DNA tether’s extension: ~0.05 pN in force and <10 nm change in extension. We have also verified that we can manipulate DNA in near equilibrium conditions through the wide range of forces by ramping the force from low to high and back again, and observing minimal hysteresis in the molecule’s force response. Using a calibration technique based on Stokes’ drag law, we have confirmed our force measurements from DNA force-extension experiments obtained using the fluctuation-dissipation theorem applied to transverse fluctuations of the magnetic microsphere. We present data on the force-distance characteristics of a DNA molecule complexed with histones. The results illustrate how the tweezers can be used to study DNA binding proteins at the single molecule level. PMID:26757808

  11. High resolution imaging of tunnels by magnetic resonance neurography

    PubMed Central

    Wang, Kenneth C.; Thawait, Shrey K.; Williams, Eric H.; Hashemi, Shahreyar Shar; Machado, Antonio J.; Carrino, John A.; Chhabra, Avneesh

    2011-01-01

    Peripheral nerves often traverse confined fibro-osseous and fibro-muscular tunnels in the extremities, where they are particularly vulnerable to entrapment and compressive neuropathy. This gives rise to various tunnel syndromes, characterized by distinct patterns of muscular weakness and sensory deficits. This article focuses on several upper and lower extremity tunnels, in which direct visualization of the normal and abnormal nerve in question is possible with high resolution 3T MR neurography (MRN). MRN can also serve as a useful adjunct to clinical and electrophysiologic exams by discriminating adhesive lesions (perineural scar) from compressive lesions (such as tumor, ganglion, hypertrophic callous, or anomalous muscles) responsible for symptoms, thereby guiding appropriate treatment. PMID:21479520

  12. Probing DNA Helicase Kinetics with Temperature‐Controlled Magnetic Tweezers

    PubMed Central

    Gollnick, Benjamin; Carrasco, Carolina; Zuttion, Francesca; Gilhooly, Neville S.; Dillingham, Mark S.

    2015-01-01

    Motor protein functions like adenosine triphosphate (ATP) hydrolysis or translocation along molecular substrates take place at nanometric scales and consequently depend on the amount of available thermal energy. The associated rates can hence be investigated by actively varying the temperature conditions. In this article, a thermally controlled magnetic tweezers (MT) system for single‐molecule experiments at up to 40 °C is presented. Its compact thermostat module yields a precision of 0.1 °C and can in principle be tailored to any other surface‐coupled microscopy technique, such as tethered particle motion (TPM), nanopore‐based sensing of biomolecules, or super‐resolution fluorescence imaging. The instrument is used to examine the temperature dependence of translocation along double‐stranded (ds)DNA by individual copies of the protein complex AddAB, a helicase‐nuclease motor involved in dsDNA break repair. Despite moderately lower mean velocities measured at sub‐saturating ATP concentrations, almost identical estimates of the enzymatic reaction barrier (around 21–24 k B T) are obtained by comparing results from MT and stopped‐flow bulk assays. Single‐molecule rates approach ensemble values at optimized chemical energy conditions near the motor, which can withstand opposing loads of up to 14 piconewtons (pN). Having proven its reliability, the temperature‐controlled MT described herein will eventually represent a routinely applied method within the toolbox for nano‐biotechnology. PMID:25400244

  13. Torsional sensing of small-molecule binding using magnetic tweezers.

    PubMed

    Lipfert, Jan; Klijnhout, Sven; Dekker, Nynke H

    2010-11-01

    DNA-binding small molecules are widespread in the cell and heavily used in biological applications. Here, we use magnetic tweezers, which control the force and torque applied to single DNAs, to study three small molecules: ethidium bromide (EtBr), a well-known intercalator; netropsin, a minor-groove binding anti-microbial drug; and topotecan, a clinically used anti-tumor drug. In the low-force limit in which biologically relevant torques can be accessed (<10 pN), we show that ethidium intercalation lengthens DNA ∼1.5-fold and decreases the persistence length, from which we extract binding constants. Using our control of supercoiling, we measure the decrease in DNA twist per intercalation to be 27.3±1° and demonstrate that ethidium binding delays the accumulation of torsional stress in DNA, likely via direct reduction of the torsional modulus and torque-dependent binding. Furthermore, we observe that EtBr stabilizes the DNA duplex in regimes where bare DNA undergoes structural transitions. In contrast, minor groove binding by netropsin affects neither the contour nor persistence length significantly, yet increases the twist per base of DNA. Finally, we show that topotecan binding has consequences similar to those of EtBr, providing evidence for an intercalative binding mode. These insights into the torsional consequences of ligand binding can help elucidate the effects of small-molecule drugs in the cellular environment. PMID:20624816

  14. MOURA Martian magnetometer potential for high resolution magnetic mapping

    NASA Astrophysics Data System (ADS)

    Díaz-Michelena, Marina; Kilian, Rolf

    2013-04-01

    Mars Global Surveyor (MGS) mission mapped the magnetic signature all along the Martian globe during its operation between 1996 and 2006. These data shows that Mars does not present an active global magnetic field as the Earth. However, the Martian crust has an overall magnetic signature stronger than the Earth which was inherited from the active magnetic field of the Martian core during its early cooling history. The MGS survey shows plenty of magnetic anomalies located in particular within high lands of its Southern Hemisphere. Several magnetic models have been derived to explain the MGS data considering magnetic dipoles distribution in the Martian crust with moderate to high magnetic intensities and pronounced regional anomalies. However, the origin of major magnetic anomalies remains highly disputed [1]. From the magnetic investigation point of view it would be of major importance to perform near-surface magnetic measurements [2] to compare both surface and in orbit (between 100 and 440 km) data. This would help to comprehend not only the distribution of the magnetic dipoles but also to make progress in the identification of different rock types and understanding of their degree of alteration which could have modified superficial magnetic signatures. In the frame of Finnish-Russian and Spanish MetNet mission, to perform meteorological studies on Martian surface, a miniaturized magnetometer and gradiometer named MOURA was developed with the objective to improve the interpretation of the magnetic anomalies and their origin. In order to test this magnetometer, comparative on Earth magnetic measurements were performed with MOURA and a reference absolute scalar magnetometer (Geometrics 853) in areas with a representative and large variation of magmatic rocks compositions. The final goal is to test the appropriateness of the developed magnetometer for the in situ measurements on Mars. The active continental margin of the Patagonian Andes was used for this case study

  15. Toroidal magnetic detector for high resolution measurement of muon momenta

    DOEpatents

    Bonanos, Peter

    1992-01-01

    A muon detector system including central and end air-core superconducting toroids and muon detectors enclosing a central calorimeter/detector. Muon detectors are positioned outside of toroids and all muon trajectory measurements are made in a nonmagnetic environment. Internal support for each magnet structure is provided by sheets, located at frequent and regularly spaced azimuthal planes, which interconnect the structural walls of the toroidal magnets. In a preferred embodiment, the shape of the toroidal magnet volume is adjusted to provide constant resolution over a wide range of rapidity.

  16. Toroidal magnetic detector for high resolution measurement of muon momenta

    DOEpatents

    Bonanos, P.

    1992-01-07

    A muon detector system including central and end air-core superconducting toroids and muon detectors enclosing a central calorimeter/detector. Muon detectors are positioned outside of toroids and all muon trajectory measurements are made in a nonmagnetic environment. Internal support for each magnet structure is provided by sheets, located at frequent and regularly spaced azimuthal planes, which interconnect the structural walls of the toroidal magnets. In a preferred embodiment, the shape of the toroidal magnet volume is adjusted to provide constant resolution over a wide range of rapidity. 4 figs.

  17. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads.

    PubMed

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim

    2015-04-01

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm(2), a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle's position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads. PMID:25933874

  18. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads

    SciTech Connect

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim

    2015-04-15

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm{sup 2}, a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle’s position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

  19. A high-speed magnetic tweezer beyond 10,000 frames per second.

    PubMed

    Lansdorp, Bob M; Tabrizi, Shawn J; Dittmore, Andrew; Saleh, Omar A

    2013-04-01

    The magnetic tweezer is a single-molecule instrument that can apply a constant force to a biomolecule over a range of extensions, and is therefore an ideal tool to study biomolecules and their interactions. However, the video-based tracking inherent to most magnetic single-molecule instruments has traditionally limited the instrumental resolution to a few nanometers, above the length scale of single DNA base-pairs. Here we have introduced superluminescent diode illumination and high-speed camera detection to the magnetic tweezer, with graphics processing unit-accelerated particle tracking for high-speed analysis of video files. We have demonstrated the ability of the high-speed magnetic tweezer to resolve particle position to within 1 Å at 100 Hz, and to measure the extension of a 1566 bp DNA with 1 nm precision at 100 Hz in the presence of thermal noise. PMID:23635212

  20. High Resolution Marine Magnetic Survey of Shallow Water Littoral Area

    PubMed Central

    Ginzburg, Boris; Cohen, Tsuriel Ram; Zafrir, Hovav; Alimi, Roger; Salomonski, Nizan; Sharvit, Jacob

    2007-01-01

    The purpose of this paper is to present a system developed for detection and accurate mapping of ferro-metallic objects buried below the seabed in shallow waters. The system comprises a precise magnetic gradiometer and navigation subsystem, both installed on a non-magnetic catamaran towed by a low-magnetic interfering boat. In addition we present the results of a marine survey of a near-shore area in the vicinity of Atlit, a town situated on the Mediterranean coast of Israel, about 15 km south of Haifa. The primary purpose of the survey was to search for a Harvard airplane that crashed into the sea in 1960. A magnetic map of the survey area (3.5 km2 on a 0.5 m grid) was created revealing the anomalies at sub-meter accuracy. For each investigated target location a corresponding ferro-metallic item was dug out, one of which turned to be very similar to a part of the crashed airplane. The accuracy of location was confirmed by matching the position of the actual dug artifacts with the magnetic map within a range of ± 1 m, in a water depth of 9 m.

  1. Microfabrication of High Resolution X-ray Magnetic Calorimeters

    SciTech Connect

    Hsieh, W.-T.; Stevenson, Thomas R.; Bandler, Simon R.; Kelly, Daniel P.; Porst, Jan P.; Rotzinger, Hannes; Seidel, George M.

    2009-12-16

    Metallic magnetic calorimeter (MMC) is one of the most promising x-ray detector technologies for providing the very high energy resolution needed for future astronomical x-ray imaging spectroscopy. For this purpose, we have developed micro-fabricated 5x5 arrays of MMC of which each individual pixel has excellent energy resolution as good as 3.4 eV at 6 keV x-ray. Here we report on the fabrication techniques developed to achieve good resolution and high efficiency. These include: processing of a thin insulation layer for strong magnetic coupling between the AuEr sensor film and the niobium pick-up coil; production of overhanging absorbers for enhanced efficiency of x-ray absorption; fabrication on SiN membranes to minimize the effects on energy resolution from athermal phonon loss. We have also improved the deposition of the magnetic sensor film such that the film magnetization is nearly completely that is expected from the AuEr sputter target bulk material. In addition, we have included a study of a positional sensitive design, the Hydra design, which allows thermal coupling of four absorbers to a common MMC sensor and circuit.

  2. Microfabrication of High Resolution X-ray Magnetic Calorimeters

    NASA Astrophysics Data System (ADS)

    Hsieh, Wen-Ting; Bandler, Simon R.; Kelly, Daniel P.; Porst, Jan P.; Rotzinger, Hannes; Seidel, George M.; Stevenson, Thomas R.

    2009-12-01

    Metallic magnetic calorimeter (MMC) is one of the most promising x-ray detector technologies for providing the very high energy resolution needed for future astronomical x-ray imaging spectroscopy. For this purpose, we have developed micro-fabricated 5×5 arrays of MMC of which each individual pixel has excellent energy resolution as good as 3.4 eV at 6 keV x-ray. Here we report on the fabrication techniques developed to achieve good resolution and high efficiency. These include: processing of a thin insulation layer for strong magnetic coupling between the AuEr sensor film and the niobium pick-up coil; production of overhanging absorbers for enhanced efficiency of x-ray absorption; fabrication on SiN membranes to minimize the effects on energy resolution from athermal phonon loss. We have also improved the deposition of the magnetic sensor film such that the film magnetization is nearly completely that is expected from the AuEr sputter target bulk material. In addition, we have included a study of a positional sensitive design, the Hydra design, which allows thermal coupling of four absorbers to a common MMC sensor and circuit.

  3. High-Resolution and Frequency, Printed Miniature Magnetic Probes

    NASA Astrophysics Data System (ADS)

    Prager, James; Ziemba, Timothy; Miller, Kenneth; Picard, Julian

    2013-10-01

    Eagle Harbor Technologies, Inc. (EHT) is developing a technique to significantly reduce the cost and development time of producing magnetic field diagnostics. EHT is designing probes that can be printed on flexible PCBs thereby allowing for extremely small coils to be produced while essentially eliminating the time to wind the coils. The coil size can be extremely small when coupled with the EHT Hybrid Integrator, which is capable of high bandwidth measurements over short and long pulse durations. This integrator is currently being commercialized with the support of a DOE SBIR. Additionally, the flexible PCBs allow probes to be attached to complex surface and/or probes that have a complex 3D structure to be designed and fabricated. During the Phase I, EHT will design and construct magnetic field probes on flexible PCBs, which will be tested at the University of Washington's HIT-SI experiment and in EHT's material science plasma reactor. Funding provided by DOE SBIR/STTR Program.

  4. Finding the Magnetic Center of a Quadrupole to High Resolution

    SciTech Connect

    Fischer, G.E.; Cobb, J.K.; Jenson, D.R.; /SLAC

    2005-08-12

    In a companion pro, collposal it is proposed to align quadrupoles of a transport line to within transverse tolerances of 5 to 10 micrometers. Such a proposal is meaningful only if the effective magnetic center of such lenses can in fact be repeatably located with respect to some external mechanical tooling to comparable accuracy. It is the purpose of this note to describe some new methods and procedures that will accomplish this aim. It will be shown that these methods are capable of yielding greater sensitivity than the more traditional methods used in the past. The notion of the ''nodal'' point is exploited.

  5. Improved High-Force Magnetic Tweezers for Stretching and Refolding of Proteins and Short DNA

    PubMed Central

    Chen, Hu; Fu, Hongxia; Zhu, Xiaoying; Cong, Peiwen; Nakamura, Fumihiko; Yan, Jie

    2011-01-01

    Although magnetic tweezers have many unique advantages in terms of specificity, throughput, and force stability, this tool has had limited application on short tethers because accurate measurement of force has been difficult for short tethers under large tension. Here, we report a method that allows us to apply magnetic tweezers to stretch short biomolecules with accurate force calibration over a wide range of up to 100 pN. We demonstrate the use of the method by overstretching of a short DNA and unfolding/refolding a protein of filamin A immunoglobulin domains 1–8. Other potential applications of this method are also discussed. PMID:21244848

  6. High-Resolution Proton Nuclear Magnetic Resonance Analysis of Metastatic Cancer Cells

    NASA Astrophysics Data System (ADS)

    Mountford, Carolyn E.; Wright, Lesley C.; Holmes, Kerry T.; MacKinnon, Wanda B.; Gregory, Patricia; Fox, Richard M.

    1984-12-01

    High-resolution proton nuclear magnetic resonance (NMR) studies of intact cancer cells revealed differences between cells with the capacity to metastasize and those that produce locally invasive tumors. The NMR resonances that characterize the metastatic cells were associated with an increased ratio of cholesterol to phospholipid and an increased amount of plasma membrane--bound cholesterol ester. High-resolution NMR spectroscopy could therefore be used to assess the metastatic potential of primary tumors.

  7. High-resolution heteronuclear multi-dimensional NMR spectroscopy in magnetic fields with unknown spatial variations

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiyong; Huang, Yuqing; Smith, Pieter E. S.; Wang, Kaiyu; Cai, Shuhui; Chen, Zhong

    2014-05-01

    Heteronuclear NMR spectroscopy is an extremely powerful tool for determining the structures of organic molecules and is of particular significance in the structural analysis of proteins. In order to leverage the method’s potential for structural investigations, obtaining high-resolution NMR spectra is essential and this is generally accomplished by using very homogeneous magnetic fields. However, there are several situations where magnetic field distortions and thus line broadening is unavoidable, for example, the samples under investigation may be inherently heterogeneous, and the magnet’s homogeneity may be poor. This line broadening can hinder resonance assignment or even render it impossible. We put forth a new class of pulse sequences for obtaining high-resolution heteronuclear spectra in magnetic fields with unknown spatial variations based on distant dipolar field modulations. This strategy’s capabilities are demonstrated with the acquisition of high-resolution 2D gHSQC and gHMBC spectra. These sequences’ performances are evaluated on the basis of their sensitivities and acquisition efficiencies. Moreover, we show that by encoding and decoding NMR observables spatially, as is done in ultrafast NMR, an extra dimension containing J-coupling information can be obtained without increasing the time necessary to acquire a heteronuclear correlation spectrum. Since the new sequences relax magnetic field homogeneity constraints imposed upon high-resolution NMR, they may be applied in portable NMR sensors and studies of heterogeneous chemical and biological materials.

  8. Scanning magnetic tunnel junction (MTJ) microscopy: High-resolution magnetic imaging of geologic samples

    NASA Astrophysics Data System (ADS)

    Lascu, I.; Harrison, R. J.

    2014-12-01

    characterised by spatial heterogeneity. In addition, the high-resolution capability of the MTJ microscope makes it extremely useful for investigating sedimentary archives formed under low accumulation conditions (e.g., speleothems, stromatolites, Fe-Mn nodules) that hold a detectable environmental magnetic signal.

  9. Fast acquisition of high-resolution 2D NMR spectroscopy in inhomogeneous magnetic fields

    NASA Astrophysics Data System (ADS)

    Lin, Liangjie; Wei, Zhiliang; Zeng, Qing; Yang, Jian; Lin, Yanqin; Chen, Zhong

    2016-05-01

    High-resolution nuclear magnetic resonance (NMR) spectroscopy plays an important role in chemical and biological analyses. In this study, we combine the J-coupling coherence transfer module with the echo-train acquisition technique for fast acquisition of high-resolution 2D NMR spectra in magnetic fields with unknown spatial variations. The proposed method shows satisfactory performance on a 5 mM ethyl 3-bromopropionate sample, under a 5-kHz (10 ppm at 11.7 T) B0 inhomogeneous field, as well as under varying degrees of pulse-flip-angle deviations. Moreover, a simulative ex situ NMR measurement is also conducted to show the effectiveness of the proposed pulse sequence.

  10. High-Resolution Vessel Wall Magnetic Resonance Imaging in Varicella-Zoster Virus Vasculitis.

    PubMed

    Tsivgoulis, Georgios; Lachanis, Stefanos; Magoufis, Georgios; Safouris, Apostolos; Kargiotis, Odysseas; Stamboulis, Elefterios

    2016-06-01

    Varicella-zoster virus vasculopathy is a rare but potentially treatable condition. Diagnosis has been based on angiography, brain magnetic resonance imaging (MRI), and cerebrospinal fluid analysis. High-resolution vessel wall MRI may aid to the diagnosis by differentiating inflammation from other vessel wall pathologies. We present the characteristic MRI findings of this condition in a young patient presenting with ischemic stroke. PMID:27067878

  11. Scanning a DNA molecule for bound proteins using hybrid magnetic and optical tweezers.

    PubMed

    van Loenhout, Marijn T J; De Vlaminck, Iwijn; Flebus, Benedetta; den Blanken, Johan F; Zweifel, Ludovit P; Hooning, Koen M; Kerssemakers, Jacob W J; Dekker, Cees

    2013-01-01

    The functional state of the genome is determined by its interactions with proteins that bind, modify, and move along the DNA. To determine the positions and binding strength of proteins localized on DNA we have developed a combined magnetic and optical tweezers apparatus that allows for both sensitive and label-free detection. A DNA loop, that acts as a scanning probe, is created by looping an optically trapped DNA tether around a DNA molecule that is held with magnetic tweezers. Upon scanning the loop along the λ-DNA molecule, EcoRI proteins were detected with ~17 nm spatial resolution. An offset of 33 ± 5 nm for the detected protein positions was found between back and forwards scans, corresponding to the size of the DNA loop and in agreement with theoretical estimates. At higher applied stretching forces, the scanning loop was able to remove bound proteins from the DNA, showing that the method is in principle also capable of measuring the binding strength of proteins to DNA with a force resolution of 0.1 pN/[Formula: see text]. The use of magnetic tweezers in this assay allows the facile preparation of many single-molecule tethers, which can be scanned one after the other, while it also allows for direct control of the supercoiling state of the DNA molecule, making it uniquely suitable to address the effects of torque on protein-DNA interactions. PMID:23755219

  12. Partial-Homogeneity-Based Two-Dimensional High-Resolution Nuclear Magnetic Resonance Spectroscopy under Inhomogeneous Magnetic Fields.

    PubMed

    Qiu, Wenqi; Wei, Zhiliang; Ding, Nan; Yang, Yu; Ye, Qimiao; Lin, Yulan; Chen, Zhong

    2016-05-18

    High-resolution multidimensional nuclear magnetic resonance (NMR) spectroscopy serves as an irreplaceable and versatile tool in various chemical investigations. In this study, a method based on the concept of partial homogeneity is developed to offer two-dimensional (2D) high-resolution NMR spectra under inhomogeneous fields. Oscillating gradients are exerted to encode the high-resolution information, and a field-inhomogeneity correction algorithm based on pattern recognition is designed to recover high-resolution spectra. Under fields where inhomogeneity primarily distributes along a single orientation, the proposed method will improve performances of 2D NMR spectroscopy without increasing the experimental duration or significant loss in sensitivity, and thus may open important perspectives for studies of inhomogeneous chemical systems. PMID:26891886

  13. Magnetic lens apparatus for a low-voltage high-resolution electron microscope

    DOEpatents

    Crewe, Albert V.

    1996-01-01

    A lens apparatus in which a beam of charged particles of low accelerating voltage is brought to a focus by a magnetic field, the lens being situated behind the target position. The lens comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. The lens apparatus comprises the sole focusing lens for high-resolution imaging in a low-voltage scanning electron microscope.

  14. An Analytical Approach towards Passive Ferromagnetic Shimming Design for a High-Resolution NMR Magnet

    PubMed Central

    Li, Frank X.; Voccio, John P.; Cheol Ahn, Min; Hahn, Seungyong; Bascuñán, Juan; Iwasa, Yukikazu

    2015-01-01

    This paper presents a warm bore ferromagnetic shimming design for a high resolution NMR magnet based on spherical harmonic coefficient reduction techniques. The passive ferromagnetic shimming along with the active shimming is a critically important step to improve magnetic field homogeneity for an NMR Magnet. Here, the technique is applied to an NMR magnet already designed and built at the MIT's Francis Bitter Magnet Lab. Based on the actual magnetic field measurement data, a total of twenty-two low order spherical harmonic coefficients is derived. Another set of spherical harmonic coefficients was calculated for iron pieces attached to a 54 mm diameter and 72 mm high tube. To improve the homogeneity of the magnet, a multiple objective linear programming method was applied to minimize unwanted spherical harmonic coefficients. A ferromagnetic shimming set with seventy-four iron pieces was presented. Analytical comparisons are made for the expected magnetic field after Ferromagnetic shimming. The theoretically reconstructed magnetic field plot after ferromagnetic shimming has shown that the magnetic field homogeneity was significantly improved. PMID:26516300

  15. High Resolution Observations and Modeling of Small-Scale Solar Magnetic Elements

    NASA Technical Reports Server (NTRS)

    Berger, Thomas E.

    2001-01-01

    This research contract investigating the radiative transfer and dynamic physics of the smallest observable magnetic structures in the solar photosphere. Due to the lack of a high-resolution visible light satellite instrument for solar studies, all data were acquired using ground-based instrumentation. The primary goal of the investigation was to understand the formation and evolution of "G-band bright points" in relation to the associated magnetic elements. G-band bright points are small (on the order of 100 kin or less in diameter) bright signatures associated with magnetic flux elements in the photosphere. They are seen in the A2A-X2 4308 A molecular bandhead of the CH radical ill the solar spectrum and offer the highest spatial resolution and highest contrast "tracers" of small magnetic structure on the Sun.

  16. Detection of single mammalian cells by high-resolution magnetic resonance imaging.

    PubMed Central

    Dodd, S J; Williams, M; Suhan, J P; Williams, D S; Koretsky, A P; Ho, C

    1999-01-01

    This study reports the detection of single mammalian cells, specifically T cells (T lymphocytes) labeled with dextran-coated superparamagnetic iron oxide particles, using magnetic resonance microscopy. Size amplification due to sequestration of the superparamagnetic particles in vacuoles enhances contrast in localized areas in high-resolution magnetic resonance imaging. Magnetic resonance images of samples containing differing concentrations of T cells embedded in 3% gelatin show a number of dark regions due to the superparamagnetic iron oxide particles, consistent with the number predicted by transmission electron microscopy. Colabeling of T cell samples with a fluorescent dye leads to strong correlations between magnetic resonance and fluorescence microscopic images, showing the presence of the superparamagnetic iron oxide particles at the cell site. This result lays the foundation for our approach to tracking the movement of a specific cell type in live animals and humans. PMID:9876127

  17. Observation of thermomagnetically recorded domains with high-resolution magnetic soft x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Tsunashima, S.; Takagi, Nayuki; Yamaguchi, Atushi; Kume, Minoru; Fischer, P.; Kumazawa, M.

    2003-04-01

    Magnetic domains were thermomagnetically recorded on TbFeCo films using laser pulsed magnetic field modulation (LP-MFM) and light intensity modulation (LIM). The domains were observed with high resolution magnetic transmission X-ray microscopy (M-TXM) before and after the heat treatment in order to clarify the recording characteristics and the thermal stability of recorded domains. From the results of M-TXM images, it was found that isolated single marks whose lengths are much smaller than 100 nm can be recorded by LP-MFM but their mark lengths become often longer than designed. It was further confirmed that the heat treatment at 120 degree C for 50 hours does not influence significantly the crescent-shaped magnetic domains of 100 nm in width recorded using LP-MFM method and circular domains of 150 nm in diameter recorded using LIM method.

  18. The Need for High-Resolution Crustal Magnetic Field Data on Mars

    NASA Technical Reports Server (NTRS)

    Raymond, C. A.; Russell, C. T.; Purucker, M. E.; Smrekar, S. E.

    2000-01-01

    Magnetometer observations from the Mars Global Surveyor spacecraft (MAG/ER on MGS) have confirmed that Mars does not presently have an internally-generated dipole magnetic field, and have also revealed intense remanent magnetism in the Martian crust. The remanent magnetic anomalies, most prevalent in the southern highlands region, are a record of the past history of the internal Mars dipole field. The MAG/ER data constitute a valuable data set for constraining the early thermal evolution of Mars and the history of the planetary magnetic field. However, the data lack the resolution needed to draw definite conclusions regarding the time history of the field. High-resolution magnetometer observations, obtained at low-altitude, are needed to complement and extend the MGS/ER data set and allow a definitive time history of the internal Mars dynamo to be constructed.

  19. High resolution in-operando microimaging of solar cells with pulsed electrically-detected magnetic resonance.

    PubMed

    Katz, Itai; Fehr, Matthias; Schnegg, Alexander; Lips, Klaus; Blank, Aharon

    2015-02-01

    The in-operando detection and high resolution spatial imaging of paramagnetic defects, impurities, and states becomes increasingly important for understanding loss mechanisms in solid-state electronic devices. Electron spin resonance (ESR), commonly employed for observing these species, cannot meet this challenge since it suffers from limited sensitivity and spatial resolution. An alternative and much more sensitive method, called electrically-detected magnetic resonance (EDMR), detects the species through their magnetic fingerprint, which can be traced in the device's electrical current. However, until now it could not obtain high resolution images in operating electronic devices. In this work, the first spatially-resolved electrically-detected magnetic resonance images (EDMRI) of paramagnetic states in an operating real-world electronic device are provided. The presented method is based on a novel microwave pulse sequence allowing for the coherent electrical detection of spin echoes in combination with powerful pulsed magnetic-field gradients. The applicability of the method is demonstrated on a device-grade 1-μm-thick amorphous silicon (a-Si:H) solar cell and an identical device that was degraded locally by an electron beam. The degraded areas with increased concentrations of paramagnetic defects lead to a local increase in recombination that is mapped by EDMRI with ∼20-μm-scale pixel resolution. The novel approach presented here can be widely used in the nondestructive in-operando three-dimensional characterization of solid-state electronic devices with a resolution potential of less than 100 nm. PMID:25557860

  20. High resolution in-operando microimaging of solar cells with pulsed electrically-detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Katz, Itai; Fehr, Matthias; Schnegg, Alexander; Lips, Klaus; Blank, Aharon

    2015-02-01

    The in-operando detection and high resolution spatial imaging of paramagnetic defects, impurities, and states becomes increasingly important for understanding loss mechanisms in solid-state electronic devices. Electron spin resonance (ESR), commonly employed for observing these species, cannot meet this challenge since it suffers from limited sensitivity and spatial resolution. An alternative and much more sensitive method, called electrically-detected magnetic resonance (EDMR), detects the species through their magnetic fingerprint, which can be traced in the device's electrical current. However, until now it could not obtain high resolution images in operating electronic devices. In this work, the first spatially-resolved electrically-detected magnetic resonance images (EDMRI) of paramagnetic states in an operating real-world electronic device are provided. The presented method is based on a novel microwave pulse sequence allowing for the coherent electrical detection of spin echoes in combination with powerful pulsed magnetic-field gradients. The applicability of the method is demonstrated on a device-grade 1-μm-thick amorphous silicon (a-Si:H) solar cell and an identical device that was degraded locally by an electron beam. The degraded areas with increased concentrations of paramagnetic defects lead to a local increase in recombination that is mapped by EDMRI with ∼20-μm-scale pixel resolution. The novel approach presented here can be widely used in the nondestructive in-operando three-dimensional characterization of solid-state electronic devices with a resolution potential of less than 100 nm.

  1. High-Resolution SQUID imaging of Magnetic Fields Generated by Propagating Cardiac Action Currents

    NASA Astrophysics Data System (ADS)

    Holzer, Jenny R.; Sidorov, Veniamin; Fong, Luis; Peters, Nicholas; Baudenbacher, Petra; Baudenbacher, Franz

    2004-03-01

    The heart's magnetic field is exquisitely sensitive to anisotropy ratios in the cardiac bidomain model; Therefore, magnetic imaging of cardiac action currents is an ideally suited technique for testing the accuracy of cardiac models and elucidating the effects of anisotropy in the spread of stimulus and action currents. We mapped the magnetocardiogram (MCG) as a function of position over a 10mm x 10mm area of the left ventricle of a Langendorff perfused isolated rabbit heart using high-resolution scanning SQUID microscopy and epi-fluorescent imaging with a high speed CCD camera and the transmembrane voltage sensitive dye di-4-ANEPPS. The combination of these two methods allowed us to map the transmembrane potential, the magnetic field, and consequently the total current, over the same area. The MCGs were combined to produce a time series of 2D field maps that show a clear octupolar pattern during the cathodal current injection, a similar pattern with a reversal of currents immediately after terminating the stimulus, and the generation and propagation of an elliptical action current wave front. The observed patterns are in agreement with predictions using a bidomain model. Our high-resolution SQUID images have confirmed that unequal anisotropies in the intra- and extracellular spaces must be considered to explain the magnetic field associated with action current propagation However, a realistic cardiac bidomain model incorporating fiber rotation, cleavage planes, and tissue heterogeneities are required to reproduce the complete experimental observations.

  2. Simultaneous Single-Molecule Force and Fluorescence Sampling of DNA Nanostructure Conformations Using Magnetic Tweezers.

    PubMed

    Kemmerich, Felix E; Swoboda, Marko; Kauert, Dominik J; Grieb, M Svea; Hahn, Steffen; Schwarz, Friedrich W; Seidel, Ralf; Schlierf, Michael

    2016-01-13

    We present a hybrid single-molecule technique combining magnetic tweezers and Förster resonance energy transfer (FRET) measurements. Through applying external forces to a paramagnetic sphere, we induce conformational changes in DNA nanostructures, which are detected in two output channels simultaneously. First, by tracking a magnetic bead with high spatial and temporal resolution, we observe overall DNA length changes along the force axis. Second, the measured FRET efficiency between two fluorescent probes monitors local conformational changes. The synchronized orthogonal readout in different observation channels will facilitate deciphering the complex mechanisms of biomolecular machines. PMID:26632021

  3. Distribution of buried hydrothermal alteration deduced from high-resolution magnetic surveys in Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Bouligand, Claire; Glen, Jonathan M. G.; Blakely, Richard J.

    2014-04-01

    Yellowstone National Park (YNP) displays numerous and extensive hydrothermal features. Although hydrothermal alteration in YNP has been extensively studied, the volume, geometry, and type of rock alteration at depth remain poorly constrained. In this study, we use high-resolution airborne and ground magnetic surveys and measurements of remanent and induced magnetization of field and drill core samples to provide constraints on the geometry of hydrothermal alteration within the subsurface of three thermal areas in YNP (Firehole River, Smoke Jumper Hot Springs, and Norris Geyser Basin). We observe that hydrothermal zones from both liquid- and vapor-dominated systems coincide with magnetic lows observed in aeromagnetic surveys and with a decrease of the amplitude of short-wavelength anomalies seen in ground magnetic surveys. This suggests a strong demagnetization of both the shallow and deep substratum within these areas associated with the removal of magnetic minerals by hydrothermal alteration processes. Such demagnetization is confirmed by measurements of rock samples from hydrothermal areas which display significantly decreased total magnetization. A pronounced negative anomaly is observed over the Lone Star Geyser and suggests a significant demagnetization of the substratum associated with areas displaying large-scale fluid flow. The ground and airborne magnetic surveys are used to evaluate the distribution of magnetization in the subsurface. This study shows that significant demagnetization occurs over a thickness of at least a few hundred meters in hydrothermal areas at YNP and that the maximum degree or maximum thickness of demagnetization correlates closely with the location of hydrothermal activity and mapped alteration.

  4. Quasi-static high-resolution magnetic-field detection based on dielectric optical resonators

    NASA Astrophysics Data System (ADS)

    Ioppolo, Tindaro; Rubino, Edoardo

    2013-06-01

    In this paper we present a high resolution magnetic field sensor that is based on the perturbation of the optical modes (whispering gallery mode, WGM) of a spherical dielectric resonator. The optical resonator is side coupled to a tapered single mode optical fiber. One side of the optical fiber is coupled to a distribute feedback diode laser, while the other end is connected to a photodiode. The optical modes of the dielectric cavity are perturbed using a metglas sheet that is in contact with the resonator. When the metglas sheet is exposed to an external magnetic field it elongates perturbing the optical modes of the dielectric cavity. This in turn leads to a shift in the optical resonances. By measuring the induced WGM shift the magnetic field can be measured. Preliminary results show sensor resolution of a few nanoteslas.

  5. Development of a High Resolution Analyzing Magnet System for Heavy Molecular Ions

    NASA Astrophysics Data System (ADS)

    Ghazaly, Mohamed O. A. El; Dehnel, Morgan; Defrance, Pierre

    At the King Abdulaziz City for Science and Technology (KACST, Saudi Arabia), a versatile ion-beam injector was constructed to provide the electrostatic storage ring with the required high-quality ion beams. In order to remove the ambiguity over the ion mass due to the exclusive application of electric fields in the set-up, the injector is being equipped with a high resolution mass analyzing magnet. A high resolution Analyzing Magnet System has been designed to provide a singly-charged ion beam of kinetic energy up to 50 keV, mass up to 1500 Amu, and with the mass resolution fixed to Δm/m =1:1500. The system includes specific entrance and exit slits, designed to sustain the required mass resolution. Furthermore, specific focusing and shaping optics have been added upstream and downstream the system, in order to monitor and adapt the shape of the ion beam at the entrance and exit of the system, respectively. The present paper gives an overview on the design of this mass analyzing magnet system together with the upstream/downstream adapting optics.

  6. High-resolution proton nuclear magnetic resonance characterization of seminolipid from bovine spermatozoa.

    PubMed

    Alvarez, J G; Storey, B T; Hemling, M L; Grob, R L

    1990-06-01

    The high-resolution one- and two-dimensional proton nuclear magnetic resonance (1H-NMR) characterization of seminolipid from bovine spermatozoa is presented. The 1H-NMR data was confirmed by gas-liquid chromatography-mass spectrometric analysis of the partially methylated alditol acetates of the sugar unit, mild alkaline methanolysis of the glyceryl ester, mobility on normal phase and diphasic thin-layer chromatography (HPTLC), and fast atom bombardment mass spectrometry (FAB-MS). The structure of the molecule corresponds to 1-O-hexadecyl-2-O-hexadecanoyl-3-O-beta-D-(3'-sulfo)-galactopyranosyl- sn-glycerol. PMID:2373957

  7. High resolution magnetostriction measurements in pulsed magnetic fields using fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Daou, Ramzy; Weickert, Franziska; Nicklas, Michael; Steglich, Frank; Haase, Ariane; Doerr, Mathias

    2010-03-01

    We report on a new high resolution apparatus for measuring magnetostriction suitable for use at cryogenic temperatures in pulsed high magnetic fields which we have developed at the Hochfeld-Magnetlabor Dresden. Optical fiber strain gauges based on fiber Bragg gratings are used to measure the strain in small (˜1 mm) samples. We describe the implementation of a fast measurement system capable of resolving strains in the order of 10-7 with a full bandwidth of 47 kHz, and demonstrate its use on single crystal samples of GdSb and GdSi.

  8. High-resolution magnetic resonance imaging of the lower extremity nerves.

    PubMed

    Burge, Alissa J; Gold, Stephanie L; Kuong, Sharon; Potter, Hollis G

    2014-02-01

    Magnetic resonance (MR) imaging of the nerves, commonly known as MR neurography is increasingly being used as noninvasive means of diagnosing peripheral nerve disease. High-resolution imaging protocols aimed at imaging the nerves of the hip, thigh, knee, leg, ankle, and foot can demonstrate traumatic or iatrogenic injury, tumorlike lesions, or entrapment of the nerves, causing a potential loss of motor and sensory function in the affected area. A thorough understanding of normal MR imaging and gross anatomy, as well as MR findings in the presence of peripheral neuropathies will aid in accurate diagnosis and ultimately help guide clinical management. PMID:24210318

  9. First high-resolution near-seafloor survey of magnetic anomalies of the South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, J.; Xu, X.; Li, C.; Sun, Z.; Zhu, J.; Zhou, Z.; Qiu, N.

    2013-12-01

    We successfully conducted the first high-resolution near-seafloor magnetic survey of the Central, Southwest, and Northern Central Basins of the South China Sea (SCS) during two cruises on board Chinese R/V HaiYangLiuHao in October-November 2012 and March-April 2013, respectively. Measurements of magnetic field were made along four long survey lines, including (1) a NW-SE across-isochron profile transecting the Southwest Basin and covering all ages of the oceanic crust (Line CD); (2) a N-S across-isochron profile transecting the Central Basin (Line AB); and (3) two sub-parallel NE-SW across-isochron profiles transecting the Northern Central Basin of the SCS (Lines D and E). A three-axis magnetometer was mounted on a deep-tow vehicle, flying within 0.6 km above the seafloor. The position of the tow vehicle was provided by an ultra-short baseline navigation system along Lines D and E, while was estimated using shipboard GPS along Lines AB and CD. To investigate crustal magnetization, we first removed the International Geomagnetic Reference Field (IGRF) of 2010 from the measured magnetic data, and then downward continued the resultant magnetic field data to a horizontal plane at a water depth of 4.5 km to correct for variation due to the fishing depth of the deep-tow vehicle. Finally, we calculated magnetic anomalies at various water depths after reduction-to-the-pole corrections. We also constructed polarity reversal block (PRB) models of crustal magnetization by matching peaks and troughs of the observed magnetic field anomaly. Our analysis yielded the following results: (1) The near-bottom magnetic anomaly showed peak-to-trough amplitudes of more than 2,500 nT, which are several times of the anomaly amplitudes at the sea surface, illustrating that deep-tow measurements acquired much higher spatial resolutions. (2) The deep-tow data revealed several distinctive magnetic anomalies with wavelengths of 5-15 km and amplitudes of several hundred nT. These short

  10. High-resolution Magnetic Resonance Vessel Wall Imaging for Intracranial Arterial Stenosis

    PubMed Central

    Zhu, Xian-Jin; Wang, Wu; Liu, Zun-Jing

    2016-01-01

    Objective: To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging (HRMR VWI) for intracranial arterial stenosis. Date Sources: We retrieved information from PubMed database up to December 2015, using various search terms including vessel wall imaging (VWI), high-resolution magnetic resonance imaging, intracranial arterial stenosis, black blood, and intracranial atherosclerosis. Study Selection: We reviewed peer-reviewed articles printed in English on imaging technique of VWI and characteristic findings of various intracranial vasculopathies on VWI. We organized this data to explain the value of VWI in clinical application. Results: VWI with black blood technique could provide high-quality images with submillimeter voxel size, and display both the vessel wall and lumen of intracranial artery simultaneously. Various intracranial vasculopathies (atherosclerotic or nonatherosclerotic) had differentiating features including pattern of wall thickening, enhancement, and vessel remodeling on VWI. This technique could be used for determining causes of stenosis, identification of stroke mechanism, risk-stratifying patients, and directing therapeutic management in clinical practice. In addition, a new morphological classification based on VWI could be established for predicting the efficacy of endovascular therapy. Conclusions: This review highlights the value of HRMR VWI for discrimination of different intracranial vasculopathies and directing therapeutic management. PMID:27231176

  11. High resolution neurography of the brachial plexus by 3 Tesla magnetic resonance imaging.

    PubMed

    Cejas, C; Rollán, C; Michelin, G; Nogués, M

    2016-01-01

    The study of the structures that make up the brachial plexus has benefited particularly from the high resolution images provided by 3T magnetic resonance scanners. The brachial plexus can have mononeuropathies or polyneuropathies. The mononeuropathies include traumatic injuries and trapping, such as occurs in thoracic outlet syndrome due to cervical ribs, prominent transverse apophyses, or tumors. The polyneuropathies include inflammatory processes, in particular chronic inflammatory demyelinating polyneuropathy, Parsonage-Turner syndrome, granulomatous diseases, and radiation neuropathy. Vascular processes affecting the brachial plexus include diabetic polyneuropathy and the vasculitides. This article reviews the anatomy of the brachial plexus and describes the technique for magnetic resonance neurography and the most common pathologic conditions that can affect the brachial plexus. PMID:26860655

  12. High-Resolution Observations of Flare Precursors and Their Relationship with Magnetic Channels

    NASA Astrophysics Data System (ADS)

    Wang, Haimin; Xu, Yan; Ahn, Kwangsu; Jing, Ju; Liu, Chang; Deng, Na; Huang, Nengyi; Gary, Dale E.; Cao, Wenda

    2016-05-01

    The study of precursors of flares is important for understanding the basic magnetic instability leading to solar flares, which can aid the forecasting of eruptions potentially related to severe space weather effects. Although literatures reported many important clues, high-resolution observations of pre-flare activities before a well-observed solar flare have been rare. Even rarely, the associated magnetic structures in fine scale (below 1") were also observed. In this study we take advantage of multiwavelength high-resolution observations completely covering the 2015 June 22 M6.6 flare, which were obtained under excellent seeing condition with the 1.6 m New Solar Telescope (NST) at Big Bear Solar Observatory. The NST data includes observations of the H-alpha line in five spectral positions at a spatial resolution of 0.1" and magnetograms at a resolution of 0.25". These are complemented by IRIS UV observations with a resolution of 0.25". We find that there are two episodes of pre-flare brightenings (precursors), which are spatially associated with magnetic channels, i.e., elongated structures comprising alternating magnetic polarity inversion lines (Zirin & Wang, 1993, Nature, 363, 426). The pre-flare chromospheric and coronal features reflect an extremely sheared magnetic topology, while the initiation of main flare brightenings correspond to a much less sheared configuration. RHESSI HXR observations reveal that the precursors have both thermal and nonthermal components, and the latter is further evidenced by the microwave observations of the newly expanded Solar Radio Array at Owens Valley.We further investigate the electric current system above the magnetic channels using NLFFF extrapolations, which show strong current sheets above the channel structure. This is consistent with the MHD modeling of Kusano et al (2012, Ap.J., 760, 31), who noted the importance of localized small-scale magnetic structure in triggering the eruption of the whole active region. We

  13. Improved determination of seafloor absolute magnetization from uneven, near-seafloor magnetic measurements and high-resolution bathymetry

    NASA Astrophysics Data System (ADS)

    Szitkar, F.; Dyment, J.; Choi, Y.; Fouquet, Y.

    2012-12-01

    Vector magnetometers installed on deep-sea submersibles offer a unique opportunity to achieve high resolution magnetic investigations at the scale of hundred to thousand meters. Once corrected for the vehicle induced and remanent magnetization, the measurements mostly reflect variations of the topography and the submersible path - i.e. the distance between the sources and the observation points. The interesting parameter, however, is the seafloor magnetization that can be interpreted in terms of geological processes. Here we present methods to compute absolute magnetization of the seafloor by taking advantage of the uneven track of the submersible. In these methods, synthetic anomalies are computed for a unit magnetization assuming the geometry of the experiment, i.e. the source and the submersible path. The absolute magnetization is determined by a comparison between the observed anomalies and the synthetic ones along sliding windows. The coherency between the two signals gives an estimation of the quality of the determination, and the phase provides information on the magnetic polarity, and therefore the age of volcanic features. Such a method has been developed by Honsho et al. (JGR, 2009) using deep-sea submersible data only, i.e. magnetic anomaly, depth and altitude of the submersible. The synthetic anomalies are computed using 2D forward modeling, i.e. assuming the structures to be infinite in the direction perpendicular to the submersible path. The method has been applied with success to linear profiles crossing elongated structures such as mid-ocean ridges, but may fail for structures departing from the 2D assumption. The adaptation of improving multibeam systems to autonomous underwater vehicles (AUVs) has opened the way to the collection of very high resolution bathymetric data (around 2m between each measurement). This development has triggered a new strategy to explore the seafloor using manned submersibles: an AUV is operated during night time to

  14. High-resolution observations of the polar magnetic fields of the sun

    NASA Technical Reports Server (NTRS)

    Lin, H.; Varsik, J.; Zirin, H.

    1994-01-01

    High-resolution magnetograms of the solar polar region were used for the study of the polar magnetic field. In contrast to low-resolution magnetograph observations which measure the polar magnetic field averaged over a large area, we focused our efforts on the properties of the small magnetic elements in the polar region. Evolution of the filling factor (the ratio of the area occupied by the magnetic elements to the total area) of these magnetic elements, as well as the average magnetic field strength, were studied during the maximum and declining phase of solar cycle 22, from early 1991 to mid-1993. We found that during the sunspot maximum period, the polar regions were occupied by about equal numbers of positive and negative magnetic elements, with equal average field strength. As the solar cycle progresses toward sunspot minimum, the magnetic field elements in the polar region become predominantly of one polarity. The average magnetic field of the dominant polarity elements also increases with the filling factor. In the meanwhile, both the filling factor and the average field strength of the non-dominant polarity elements decrease. The combined effects of the changing filling factors and average field strength produce the observed evolution of the integrated polar flux over the solar cycle. We compared the evolutionary histories of both filling factor and average field strength, for regions of high (70-80 deg) and low (60-70 deg) latitudes. For the south pole, we found no significant evidence of difference in the time of reversal. However, the low-latitude region of the north pole did reverse polarity much earlier than the high-latitude region. It later showed an oscillatory behavior. We suggest this may be caused by the poleward migration of flux from a large active region in 1989 with highly imbalanced flux.

  15. Magnetic tweezers-based force clamp reveals mechanically distinct apCAM domain interactions.

    PubMed

    Kilinc, Devrim; Blasiak, Agata; O'Mahony, James J; Suter, Daniel M; Lee, Gil U

    2012-09-19

    Cell adhesion molecules of the immunoglobulin superfamily (IgCAMs) play a crucial role in cell-cell interactions during nervous system development and function. The Aplysia CAM (apCAM), an invertebrate IgCAM, shares structural and functional similarities with vertebrate NCAM and therefore has been considered as the Aplysia homolog of NCAM. Despite these similarities, the binding properties of apCAM have not been investigated thus far. Using magnetic tweezers, we applied physiologically relevant, constant forces to apCAM-coated magnetic particles interacting with apCAM-coated model surfaces and characterized the kinetics of bond rupture. The average bond lifetime decreased with increasing external force, as predicted by theoretical considerations. Mathematical simulations suggest that the apCAM homophilic interaction is mediated by two distinct bonds, one involving all five immunoglobulin (Ig)-like domains in an antiparallel alignment and the other involving only two Ig domains. In summary, this study provides biophysical evidence that apCAM undergoes homophilic interactions, and that magnetic tweezers-based, force-clamp measurements provide a rapid and reliable method for characterizing relatively weak CAM interactions. PMID:22995484

  16. High resolution dating of young magmatic oceanic crust using near-seafloor magnetics

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Kitazawa, M.; Hemond, C.; Guillou, H.; Chauvin, A.; Ravilly, M.; Honsho, C.

    2015-12-01

    We compare two independent dating methods on a section of oceanic crust created within the last million year on the Central Indian Ridge axis at 19°10'S, an area affected by the Reunion hotspot. First, near-seafloor magnetic anomalies display characteristic sequences of magnetic intensity variations that we confidently identified by comparison with published paleointensity curves for the Brunhes period and used as a dating tool. This approach is further confirmed by the linear trend relating the NRM (Natural Remanent Magnetization) and paleointensity measured on rock samples along the same section. Second, valid K-Ar and Ar-Ar ages are determined on enriched basalt samples collected by deep-sea submersible. They show an excellent coincidence with the magnetic ages and support the use of high-resolution, near-seafloor marine magnetic anomalies as an efficient tool to date the young magmatic oceanic crust, where radiometric methods are generally unpractical, with unprecedented resolution. The ages obtained on the CIR reveal a 150-200 kyr cyclicity in the magmatic and tectonic processes of seafloor formation, two ridge jumps of 2.5 km and 1.2 km, respectively, and a systematic spreading asymmetry in favor to the Indian flank which may result from the interaction of the CIR with the Reunion hotspot.

  17. Magnetic lens apparatus for use in high-resolution scanning electron microscopes and lithographic processes

    DOEpatents

    Crewe, Albert V.

    2000-01-01

    Disclosed are lens apparatus in which a beam of charged particlesis brought to a focus by means of a magnetic field, the lens being situated behind the target position. In illustrative embodiments, a lens apparatus is employed in a scanning electron microscopeas the sole lens for high-resolution focusing of an electron beam, and in particular, an electron beam having an accelerating voltage of from about 10 to about 30,000 V. In one embodiment, the lens apparatus comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. In other embodiments, the lens apparatus comprises a magnetic dipole or virtual magnetic monopole fabricated from a variety of materials, including permanent magnets, superconducting coils, and magnetizable spheres and needles contained within an energy-conducting coil. Multiple-array lens apparatus are also disclosed for simultaneous and/or consecutive imaging of multiple images on single or multiple specimens. The invention further provides apparatus, methods, and devices useful in focusing charged particle beams for lithographic processes.

  18. High Resolution Observations of Magnetic Elements in the Visible and the Infrared

    NASA Astrophysics Data System (ADS)

    Rimmele, T.; Lin, H.

    1997-05-01

    High resolution observations of magnetic elements in the visible and infrared. We report on multi-wavelength observations of plage regions obtained at the Vacuum Tower Telescope at NSO/Sac-Peak . The data set includes high resolution images in the G-band (0.43 mu ), the visible (0.69 mu ) continuum and the infrared (1.6 mu ) continuum. In addition, deep integration full Stokes vector measurements in the FeI 1.56 mu lines, as well as, Ca-K slit jaw images were obtained. G-band bright points, which are observed mostly in supergranular lanes, are also visible as bright points in the visible continuum. Although the infrared observations are limited in spatial resolution to about 0."4 (the diffraction limit of the VTT/SP), the data indicates that G-band bright points are also bright in the infrared (1.6 mu ). We also discuss and compare properties of magnetic knots and small pores. Magnetic knots, which recently also have been referred to as azimuth centers (Lites et al. 1994), by definition show no darkening in individual continuum images. However, in the time-averaged imaging data, and in particular in the infrared, azimuth centers appear as dark features, which are clearly distinguishable from the quiet sun background. In the infrared most azimuth centers are visible as dark features even in individual snapshots. Many azimuth centers as well as some small pores are surrounded by a highly structured bright ring, which becomes more apparent with increasing height of formation. Results of the polarization analysis in the FeI 1.56 mu lines, including measurements of weak fields, are presented as well.

  19. Reverse DNA translocation through a solid-state nanopore by magnetic tweezers

    PubMed Central

    Peng, Hongbo; Ling, Xinsheng Sean

    2009-01-01

    Voltage-driven DNA translocation through nanopores has attracted wide interest for many potential applications in molecular biology and biotechnology. However, it is intrinsically difficult to control the DNA motion in standard DNA translocation processes in which a strong electric field is required in drawing DNA into the pore, but it also leads to uncontrollable fast DNA translocation. Here we explore a new type of DNA translocation. We dub it ‘reverse DNA translocation’, in which the DNA is pulled through a nanopore mechanically by a magnetic bead, driven by a magnetic-field gradient. This technique is compatible with simultaneous ionic current measurements and is suitable for multiple nanopores, paving the way for large scale applications. We report the first experiment of reverse DNA translocation through a solid-state nanopore using magnetic tweezers. PMID:19420602

  20. High-force NdFeB-based magnetic tweezers device optimized for microrheology experiments

    SciTech Connect

    Lin Jun; Valentine, Megan T.

    2012-05-15

    We present the design, calibration, and testing of a magnetic tweezers device that employs two pairs of permanent neodymium iron boron magnets surrounded by low-carbon steel focusing tips to apply large forces to soft materials for microrheology experiments. Our design enables the application of forces in the range of 1-1800 pN to {approx}4.5 {mu}m paramagnetic beads using magnet-bead separations in the range of 0.3-20 mm. This allows the use of standard coverslips and sample geometries. A high speed camera, custom LED-based illumination scheme, and mechanically stabilized measurement platform are employed to enable the measurement of materials with viscoelastic moduli as high as {approx}1 kPa.

  1. High-resolution Observations of Siphon Flows in a Solar Magnetic Pore

    NASA Astrophysics Data System (ADS)

    Guglielmino, Salvo L.; Zuccarello, Francesca

    2011-12-01

    We investigate signatures of siphon flows in a region around a solar magnetic pore, observed in the photosphere at μ = 0.6, during its decay phase. We analyze high-resolution Stokes spectra acquired by Hinode/Solar Optical Telescope along the Fe I pair at 630.2 nm. We determine the vector magnetic field and the line-of-sight velocity by an inversion of the full Stokes vector using the SIR code. We also analyze photospheric G-band filtergrams. We find evidence of a transient siphon (counter)flow at the edge of the pore. An arch-shaped structure is found to have upflow motions of 4 km s-1 in the footpoint with a stronger magnetic field and positive polarity, and downflows of the same order of magnitude in the footpoint with opposite polarity and a weaker magnetic field. The event is different from those reported in previous observations of the Sun's atmosphere and may represent a physical constraint for numerical models.

  2. High-Resolution Magnetic Analyzer MAVR for the Study of Exotic Weakly-Bound Nuclei

    NASA Astrophysics Data System (ADS)

    Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.

    2015-11-01

    A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ~1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400-U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.

  3. Analysis of cell mechanics in single vinculin-deficient cells using a magnetic tweezer

    NASA Technical Reports Server (NTRS)

    Alenghat, F. J.; Fabry, B.; Tsai, K. Y.; Goldmann, W. H.; Ingber, D. E.

    2000-01-01

    A magnetic tweezer was constructed to apply controlled tensional forces (10 pN to greater than 1 nN) to transmembrane receptors via bound ligand-coated microbeadswhile optically measuring lateral bead displacements within individual cells. Use of this system with wild-type F9 embryonic carcinoma cells and cells from a vinculin knockout mouse F9 Vin (-/-) revealed much larger differences in the stiffness of the transmembrane integrin linkages to the cytoskeleton than previously reported using related techniques that measured average mechanical properties of large cell populations. The mechanical properties measured varied widely among cells, exhibiting an approximately log-normal distribution. The median lateral bead displacement was 2-fold larger in F9 Vin (-/-) cells compared to wild-type cells whereas the arithmetic mean displacement only increased by 37%. We conclude that vinculin serves a greater mechanical role in cells than previously reported and that this magnetic tweezer device may be useful for probing the molecular basis of cell mechanics within single cells. Copyright 2000 Academic Press.

  4. Measurement of magnetic field aligned potential differences using high resolution conjugate photoelectron energy spectra

    NASA Technical Reports Server (NTRS)

    Peterson, W. K.; Doering, J. P.; Potemra, T. A.; Bostrom, C. O.; Brace, L. H.; Heelis, R. A.; Hanson, W. B.

    1977-01-01

    Simultaneous high-resolution observations of a distinctive feature in the energy spectrum of conjugate photoelectrons and spacecraft potential relative to the local ionosphere have allowed the net potential difference between magnetic conjugate points at latitudes below the region of low-energy (i.e., lower than 100 eV) auroral electron precipitation to be determined. Measurements made at 300 km from Atmosphere Explorer C show that there is normally no net potential difference between hemispheres in this region, which extended up to invariant latitudes as high as 74 deg. Two types of apparently related anomalous behavior were infrequently observed at high latitudes. During these periods the incident flux of conjugate photoelectrons was either decelerated by about 3 eV or was not detected.

  5. The magnetic fields of Ap stars from high resolution Stokes IQUV spectropolarimetry

    NASA Astrophysics Data System (ADS)

    Silvester, James

    In this thesis we describe the acquisition of high resolution time resolved spectropolarimetric observations of 7 (bright and well understood) Ap stars in Stokes IQUV using the ESPaDOnS and Narval spectropolarimeters at the Canada-France-Hawaii Telescope and the 2m Telescope Bernard Lyot at Pic du Midi Observatory. We compare these observations with those obtained a decade earlier using the MuSiCoS spectropolarimeter to confirm consistency with the older data and provide evidence that both ESPaDOnS and Narval perform as expected in all Stokes parameters. We demonstrate that our refined longitudinal magnetic field and linear polarisation measurements for these 7 stars are of much greater quality than was previously obtained with MuSiCoS and that the global magnetic properties of these stars are stable over a long timescale. The ultimate aim of these new data is to provide a basis from which mapping of both the magnetic field and abundance structures can be performed on our target stars. We then describe magnetic field mapping of the Ap star alpha 2 CVn using these data. This mapping is achieved with the use of tomographic inversion of Doppler-broadened Stokes IQUV profiles of a large variety of spectral lines using the INVERS10 Magnetic Doppler imaging code. We show that not only are the new magnetic field maps of alpha 2 CVn consistent with a previous generation of maps of alpha 2 CVn, but that the same magnetic field topology can be derived from a variety of atomic line sets. This indicates that the magnetic field we derive for alpha2 CVn is a realistic representation of the star's true magnetic topology. Finally we investigate surface abundance structures for alpha 2 CVn for various chemical elements. We investigate the correlation between the location of these abundance features and the magnetic field of alpha 2 CVn. We will demonstrate that whilst the magnetic field plays a role in the formation of abundance structures, the current theoretical framework does

  6. Crocus sativus Petals: Waste or Valuable Resource? The Answer of High-Resolution and High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance.

    PubMed

    Righi, Valeria; Parenti, Francesca; Tugnoli, Vitaliano; Schenetti, Luisa; Mucci, Adele

    2015-09-30

    Intact Crocus sativus petals were studied for the first time by high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy, revealing the presence of kinsenoside (2) and goodyeroside A (3), together with 3-hydroxy-γ-butyrolactone (4). These findings were confirmed by HR-NMR analysis of the ethanol extract of fresh petals and showed that, even though carried out rapidly, partial hydrolysis of glucopyranosyloxybutanolides occurs during extraction. On the other hand, kaempferol 3-O-sophoroside (1), which is "NMR-silent" in intact petals, is present in extracts. These results suggest to evaluate the utilization of saffron petals for phytopharmaceutical and nutraceutical purposes to exploit a waste product of massive production of commercial saffron and point to the application of HR-MAS NMR for monitoring bioactive compounds directly on intact petals, avoiding the extraction procedure and the consequent hydrolysis reaction. PMID:26367873

  7. Transcranial magnetic stimulation of mouse brain using high-resolution anatomical models

    NASA Astrophysics Data System (ADS)

    Crowther, L. J.; Hadimani, R. L.; Kanthasamy, A. G.; Jiles, D. C.

    2014-05-01

    Transcranial magnetic stimulation (TMS) offers the possibility of non-invasive treatment of brain disorders in humans. Studies on animals can allow rapid progress of the research including exploring a variety of different treatment conditions. Numerical calculations using animal models are needed to help design suitable TMS coils for use in animal experiments, in particular, to estimate the electric field induced in animal brains. In this paper, we have implemented a high-resolution anatomical MRI-derived mouse model consisting of 50 tissue types to accurately calculate induced electric field in the mouse brain. Magnetic field measurements have been performed on the surface of the coil and compared with the calculations in order to validate the calculated magnetic and induced electric fields in the brain. Results show how the induced electric field is distributed in a mouse brain and allow investigation of how this could be improved for TMS studies using mice. The findings have important implications in further preclinical development of TMS for treatment of human diseases.

  8. High Resolution Magnetic Anomaly Imaging of Southern McMurdo Sound (Antarctica)

    NASA Astrophysics Data System (ADS)

    Chiappini, M.; Gaya Pique, L. R.; Pignatelli, A.; Wilson, T.

    2004-12-01

    During the 2003-04 austral summer season, a low-altitude, high-resolution airborne magnetic survey was conducted in the area of Southern McMurdo Sound, western Ross Sea, in the framework of the joint Italian-US initiative called GEOIMAG (GEOphysical IMAGing of Antarctic tectonic and volcanic units in the Transantarctic Mountains and Ross Sea area). The survey was flown by helicopter from McMurdo Station, at a constant terrain clearance of 70 m. Profile spacing was 350 m. The resolution of the survey, the accuracy of the data acquisition, and a preliminary digital enhancement of the processed magnetic data have contributed to highlight the short-wavelength component of the regional magnetic anomaly field, resolving volcanic bodies and faults. A broad positive anomaly tapers northward from the volcanic Brown Peninsula. The breadth and low amplitude of the anomaly suggests this may mark relatively thin deposits of volcanic material on or near the seafloor. High-frequency and high-amplitude anomalies are associated with the volcanic Daily Islands at the edge of the Ross Ice Shelf. Anomalies of similar amplitude and size in adjacent areas indicate additional volcanic cones occur on the seafloor and beneath the ice sheet. Low-amplitude, curvilinear anomalies with a convex shape toward McMurdo Sound occur offshore of the outlet of Ferrar Glacier and extending southward parallel to the coastline. The new data are being integrated with a multi-source database (magnetic, digital terrain data, bathymetry, regional structural trends) to obtain an unprecedented view of the magnetic signature of the major tectonic elements in the area. The structural and volcanic framework resulting from this investigation will provide important site survey information for the proposed ANDRILL drill sites in southern McMurdo Sound.

  9. Characterization of the mechanical properties of HL-1 cardiomyocytes with high throughput magnetic tweezers

    SciTech Connect

    Chen, La; Maybeck, Vanessa; Offenhäusser, Andreas; Krause, Hans-Joachim

    2015-08-03

    We characterized the mechanical properties of cardiomyocyte-like HL-1 cells using our recently developed multi-pole magnetic tweezers. With the optimized design, both high force and high throughput are achieved at the same time. Force up to 100 pN can be applied on a 1 μm diameter superparamagnetic bead in a workspace with 60 μm radius, which is encircled symmetrically by 3 sharp magnetic tips. By adjusting the coil currents, both the strength and direction of force can be controlled. The result shows that both viscosity and shear elastic modulus of HL-1 cells exhibit an approximately log-normal distribution. The cells became stiffer as they matured, consistent with a transition from proliferating cells to contractile muscle tissue. Moreover, the mechanical properties of HL-1 cells show high heterogeneity, which agrees well with their physiological structure.

  10. High-resolution dichroic imaging of magnetic flux distributions in superconductors with scanning x-ray microscopy

    SciTech Connect

    Ruoß, S. Stahl, C.; Weigand, M.; Schütz, G.; Albrecht, J.

    2015-01-12

    The penetration of magnetic flux into high-temperature superconductors has been observed using a high-resolution technique based on x-ray magnetic circular dichroism. Superconductors coated with thin soft-magnetic layers are observed in a scanning x-ray microscope under the influence of external magnetic fields. Resulting electric currents in the superconductor create an inhomogeneous magnetic field distribution above the superconductor and lead to a local reorientation of the ferromagnetic layer. Measuring the local magnetization of the ferromagnet by x-ray absorption microscopy with circular-polarized radiation allows the analysis of the magnetic flux distribution in the superconductor with a spatial resolution on the nanoscale.

  11. High-Resolution Mechanical Imaging of Glioblastoma by Multifrequency Magnetic Resonance Elastography

    PubMed Central

    Freimann, Florian Baptist; Bayerl, Simon; Guo, Jing; Arlt, Felix; Wuerfel, Jens; Braun, Jürgen; Hoffmann, Karl-Titus; Sack, Ingolf

    2014-01-01

    Objective To generate high-resolution maps of the viscoelastic properties of human brain parenchyma for presurgical quantitative assessment in glioblastoma (GB). Methods Twenty-two GB patients underwent routine presurgical work-up supplemented by additional multifrequency magnetic resonance elastography. Two three-dimensional viscoelastic parameter maps, magnitude |G*|, and phase angle φ of the complex shear modulus were reconstructed by inversion of full wave field data in 2-mm isotropic resolution at seven harmonic drive frequencies ranging from 30 to 60 Hz. Results Mechanical brain maps confirmed that GB are composed of stiff and soft compartments, resulting in high intratumor heterogeneity. GB could be easily differentiated from healthy reference tissue by their reduced viscous behavior quantified by φ (0.37±0.08 vs. 0.58±0.07). |G*|, which in solids more relates to the material's stiffness, was significantly reduced in GB with a mean value of 1.32±0.26 kPa compared to 1.54±0.27 kPa in healthy tissue (P = 0.001). However, some GB (5 of 22) showed increased stiffness. Conclusion GB are generally less viscous and softer than healthy brain parenchyma. Unrelated to the morphology-based contrast of standard magnetic resonance imaging, elastography provides an entirely new neuroradiological marker and contrast related to the biomechanical properties of tumors. PMID:25338072

  12. Scanning magnetic tunnel junction microscope for high-resolution imaging of remanent magnetization fields

    NASA Astrophysics Data System (ADS)

    Lima, E. A.; Bruno, A. C.; Carvalho, H. R.; Weiss, B. P.

    2014-10-01

    Scanning magnetic microscopy is a new methodology for mapping magnetic fields with high spatial resolution and field sensitivity. An important goal has been to develop high-performance instruments that do not require cryogenic technology due to its high cost, complexity, and limitation on sensor-to-sample distance. Here we report the development of a low-cost scanning magnetic microscope based on commercial room-temperature magnetic tunnel junction (MTJ) sensors that typically achieves spatial resolution better than 7 µm. By comparing different bias and detection schemes, optimal performance was obtained when biasing the MTJ sensor with a modulated current at 1.0 kHz in a Wheatstone bridge configuration while using a lock-in amplifier in conjunction with a low-noise custom-made preamplifier. A precision horizontal (x-y) scanning stage comprising two coupled nanopositioners controls the position of the sample and a linear actuator adjusts the sensor-to-sample distance. We obtained magnetic field sensitivities better than 150 nT/Hz1/2 between 0.1 and 10 Hz, which is a critical frequency range for scanning magnetic microscopy. This corresponds to a magnetic moment sensitivity of 10-14 A m2, a factor of 100 better than achievable with typical commercial superconducting moment magnetometers. It also represents an improvement in sensitivity by a factor between 10 and 30 compared to similar scanning MTJ microscopes based on conventional bias-detection schemes. To demonstrate the capabilities of the instrument, two polished thin sections of representative geological samples were scanned along with a synthetic sample containing magnetic microparticles. The instrument is usable for a diversity of applications that require mapping of samples at room temperature to preserve magnetic properties or viability, including paleomagnetism and rock magnetism, nondestructive evaluation of materials, and biological assays.

  13. High Resolution Environmental Magnetic Study of a Holocene Sedimentary Record from Zaca Lake, Ca

    NASA Astrophysics Data System (ADS)

    Platzman, E. S.; Lund, S.; Kirby, M. E.; Feakins, S. J.

    2012-12-01

    Magnetic studies of Holocene lake sediments recovered from Zaca lake have yielded a 3000-year high resolution record of environmental variability and paleolimnology. Zaca lake is a small oligomictic lake ~12m deep situated 730 m above sea level in the steep canyons of the San Rafael mountains, NW of Santa Barbara. Throughout much of the year Zaca lake is anaerobic below 7m. Hydrogen sulfide, fed into the lake via runoff and local sulphur springs, is present throughout the hypolimnion with concentrations sometime exceeding 30 mg/ l. During the summer months when the lake is stratified, light colored carbonate rich microlaminae are formed; and often during the winter months when the lake overturns, killing the anaerobic bacteria, black microlamina rich in iron sulfide are deposited on the lake floor, creating a stratigraphy reflecting patterns of environmental variability on annual to millennial scales. Samples for magnetic analysis were obtained from 8.5 m of core recovered from the central region of Zaca lake. Ages, constrained using radiocarbon chronostratigraphy, yielded sedimentation rates of 2-10 mm/yr with an average rate of 3 mm per yr over the 3000 yr interval. Parameters reflecting decadal scale variability in magnetic concentration (susceptibility, ARM, SIRM) and grainsize (ARM/Chi) were measured every 2 cm. Additional rock magnetic tests, including thermal demagnetization of three component IRM, were applied at selected intervals to constrain the magnetic mineralogy. These data were combined with analyses of clastic grain size, % calcium carbonate and % organics to create a multiproxy record of environmental variability. Results show that Zaca lake has had a complex depositional history. Anthropogenic effects associated with European colonization are present in the upper meters. Most notable, however, is a dramatic shift in the magnetic parameters and mineralogy between the upper and lower half of the core (circa 1300 ybp) indicating a shift in regime

  14. 3-Dimensional modelling of chick embryo eye development and growth using high resolution magnetic resonance imaging.

    PubMed

    Goodall, Nicola; Kisiswa, Lilian; Prashar, Ankush; Faulkner, Stuart; Tokarczuk, Paweł; Singh, Krish; Erichsen, Jonathan T; Guggenheim, Jez; Halfter, Willi; Wride, Michael A

    2009-10-01

    Magnetic resonance imaging (MRI) is a powerful tool for generating 3-dimensional structural and functional image data. MRI has already proven valuable in creating atlases of mouse and quail development. Here, we have exploited high resolution MRI to determine the parameters necessary to acquire images of the chick embryo eye. Using a 9.4 Tesla (400 MHz) high field ultra-shielded and refrigerated magnet (Bruker), MRI was carried out on paraformaldehyde-fixed chick embryos or heads at E4, E6, E8, and E10. Image data were processed using established and custom packages (MRICro, ImageJ, ParaVision, Bruker and mri3dX). Voxel dimensions ranged from 62.5 microm to 117.2 microm. We subsequently used the images obtained from the MRI data in order to make precise measurements of chick embryo eye surface area, volume and axial length from E4 to E10. MRI was validated for accurate sizing of ocular tissue features by direct comparison with previously published literature. Furthermore, we demonstrate the utility of high resolution MRI for making accurate measurements of morphological changes due to experimental manipulation of chick eye development, thereby facilitating a better understanding of the effects on chick embryo eye development and growth of such manipulations. Chondroitin sulphate or heparin were microinjected into the vitreous cavity of the right eyes of each of 3 embryos at E5. At E10, embryos were fixed and various eye parameters (volume, surface area, axial length and equatorial diameter) were determined using MRI and normalised with respect to the un-injected left eyes. Statistically significant alterations in eye volume (p < 0.05; increases with chondroitin sulphate and decreases with heparin) and changes in vitreous homogeneity were observed in embryos following microinjection of glycosaminoglycans. Furthermore, in the heparin-injected eyes, significant disturbances at the vitreo-retinal boundary were observed as well as retinal folding and detachment

  15. Microfluidic platform combining droplets and magnetic tweezers: application to HER2 expression in cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Ferraro, Davide; Champ, Jérôme; Teste, Bruno; Serra, Marco; Malaquin, Laurent; Viovy, Jean-Louis; de Cremoux, Patricia; Descroix, Stephanie

    2016-05-01

    The development of precision medicine, together with the multiplication of targeted therapies and associated molecular biomarkers, call for major progress in genetic analysis methods, allowing increased multiplexing and the implementation of more complex decision trees, without cost increase or loss of robustness. We present a platform combining droplet microfluidics and magnetic tweezers, performing RNA purification, reverse transcription and amplification in a fully automated and programmable way, in droplets of 250nL directly sampled from a microtiter-plate. This platform decreases sample consumption about 100 fold as compared to current robotized platforms and it reduces human manipulations and contamination risk. The platform’s performance was first evaluated on cell lines, showing robust operation on RNA quantities corresponding to less than one cell, and then clinically validated with a cohort of 21 breast cancer samples, for the determination of their HER2 expression status, in a blind comparison with an established routine clinical analysis.

  16. Interrogating the activities of conformational deformed enzyme by single-molecule fluorescence-magnetic tweezers microscopy.

    PubMed

    Guo, Qing; He, Yufan; Lu, H Peter

    2015-11-10

    Characterizing the impact of fluctuating enzyme conformation on enzymatic activity is critical in understanding the structure-function relationship and enzymatic reaction dynamics. Different from studying enzyme conformations under a denaturing condition, it is highly informative to manipulate the conformation of an enzyme under an enzymatic reaction condition while monitoring the real-time enzymatic activity changes simultaneously. By perturbing conformation of horseradish peroxidase (HRP) molecules using our home-developed single-molecule total internal reflection magnetic tweezers, we successfully manipulated the enzymatic conformation and probed the enzymatic activity changes of HRP in a catalyzed H2O2-amplex red reaction. We also observed a significant tolerance of the enzyme activity to the enzyme conformational perturbation. Our results provide a further understanding of the relation between enzyme behavior and enzymatic conformational fluctuation, enzyme-substrate interactions, enzyme-substrate active complex formation, and protein folding-binding interactions. PMID:26512103

  17. Microfluidic platform combining droplets and magnetic tweezers: application to HER2 expression in cancer diagnosis

    PubMed Central

    Ferraro, Davide; Champ, Jérôme; Teste, Bruno; Serra, Marco; Malaquin, Laurent; Viovy, Jean-Louis; de Cremoux, Patricia; Descroix, Stephanie

    2016-01-01

    The development of precision medicine, together with the multiplication of targeted therapies and associated molecular biomarkers, call for major progress in genetic analysis methods, allowing increased multiplexing and the implementation of more complex decision trees, without cost increase or loss of robustness. We present a platform combining droplet microfluidics and magnetic tweezers, performing RNA purification, reverse transcription and amplification in a fully automated and programmable way, in droplets of 250nL directly sampled from a microtiter-plate. This platform decreases sample consumption about 100 fold as compared to current robotized platforms and it reduces human manipulations and contamination risk. The platform’s performance was first evaluated on cell lines, showing robust operation on RNA quantities corresponding to less than one cell, and then clinically validated with a cohort of 21 breast cancer samples, for the determination of their HER2 expression status, in a blind comparison with an established routine clinical analysis. PMID:27157697

  18. Interrogating the activities of conformational deformed enzyme by single-molecule fluorescence-magnetic tweezers microscopy

    PubMed Central

    Guo, Qing; He, Yufan; Lu, H. Peter

    2015-01-01

    Characterizing the impact of fluctuating enzyme conformation on enzymatic activity is critical in understanding the structure–function relationship and enzymatic reaction dynamics. Different from studying enzyme conformations under a denaturing condition, it is highly informative to manipulate the conformation of an enzyme under an enzymatic reaction condition while monitoring the real-time enzymatic activity changes simultaneously. By perturbing conformation of horseradish peroxidase (HRP) molecules using our home-developed single-molecule total internal reflection magnetic tweezers, we successfully manipulated the enzymatic conformation and probed the enzymatic activity changes of HRP in a catalyzed H2O2–amplex red reaction. We also observed a significant tolerance of the enzyme activity to the enzyme conformational perturbation. Our results provide a further understanding of the relation between enzyme behavior and enzymatic conformational fluctuation, enzyme–substrate interactions, enzyme–substrate active complex formation, and protein folding–binding interactions. PMID:26512103

  19. Microfluidic platform combining droplets and magnetic tweezers: application to HER2 expression in cancer diagnosis.

    PubMed

    Ferraro, Davide; Champ, Jérôme; Teste, Bruno; Serra, Marco; Malaquin, Laurent; Viovy, Jean-Louis; de Cremoux, Patricia; Descroix, Stephanie

    2016-01-01

    The development of precision medicine, together with the multiplication of targeted therapies and associated molecular biomarkers, call for major progress in genetic analysis methods, allowing increased multiplexing and the implementation of more complex decision trees, without cost increase or loss of robustness. We present a platform combining droplet microfluidics and magnetic tweezers, performing RNA purification, reverse transcription and amplification in a fully automated and programmable way, in droplets of 250nL directly sampled from a microtiter-plate. This platform decreases sample consumption about 100 fold as compared to current robotized platforms and it reduces human manipulations and contamination risk. The platform's performance was first evaluated on cell lines, showing robust operation on RNA quantities corresponding to less than one cell, and then clinically validated with a cohort of 21 breast cancer samples, for the determination of their HER2 expression status, in a blind comparison with an established routine clinical analysis. PMID:27157697

  20. Surface-based analysis methods for high-resolution functional magnetic resonance imaging

    PubMed Central

    Khan, Rez; Zhang, Qin; Darayan, Shayan; Dhandapani, Sankari; Katyal, Sucharit; Greene, Clint; Bajaj, Chandra; Ress, David

    2011-01-01

    Functional magnetic resonance imaging (fMRI) has become a popular technique for studies of human brain activity. Typically, fMRI is performed with >3-mm sampling, so that the imaging data can be regarded as two-dimensional samples that average through the 1.5—4-mm thickness of cerebral cortex. The increasing use of higher spatial resolutions, <1.5-mm sampling, complicates the analysis of fMRI, as one must now consider activity variations within the depth of the brain tissue. We present a set of surface-based methods to exploit the use of high-resolution fMRI for depth analysis. These methods utilize white-matter segmentations coupled with deformable-surface algorithms to create a smooth surface representation at the gray-white interface and pial membrane. These surfaces provide vertex positions and normals for depth calculations, enabling averaging schemes that can increase contrast-to-noise ratio, as well as permitting the direct analysis of depth profiles of functional activity in the human brain. PMID:22125419

  1. A full range detector for the HIRRBS high resolution RBS magnetic spectrometer

    SciTech Connect

    Skala, Wayne G.; Haberl, Arthur W.; Bakhru, Hassaram; Lanford, William

    2013-04-19

    The UAlbany HIRRBS (High Resolution RBS) system has been updated for better use in rapid analysis. The focal plane detector now covers the full range from U down to O using a linear stepper motor to translate the 1-cm detector across the 30-cm range. Input is implemented with zero-back-angle operation in all cases. The chamber has been modified to allow for quick swapping of sample holders, including a channeling goniometer. A fixed standard surface-barrier detector allows for normal RBS simultaneously with use of the magnetic spectrometer. The user can select a region on the standard spectrum or can select an element edge or an energy point for collection of the expanded spectrum portion. The best resolution currently obtained is about 2-to-3 keV, probably representing the energy width of the incoming beam. Calibration is maintained automatically for any spectrum portion and any beam energy from 1.0 to 3.5 MeV. Element resolving power, sensitivity and depth resolution are shown using several examples. Examples also show the value of simultaneous conventional RBS.

  2. Alignment of high resolution magic angle spinning magnetic resonance spectra using warping methods.

    PubMed

    Giskeødegård, Guro F; Bloemberg, Tom G; Postma, Geert; Sitter, Beathe; Tessem, May-Britt; Gribbestad, Ingrid S; Bathen, Tone F; Buydens, Lutgarde M C

    2010-12-17

    The peaks of magnetic resonance (MR) spectra can be shifted due to variations in physiological and experimental conditions, and correcting for misaligned peaks is an important part of data processing prior to multivariate analysis. In this paper, five warping algorithms (icoshift, COW, fastpa, VPdtw and PTW) are compared for their feasibility in aligning spectral peaks in three sets of high resolution magic angle spinning (HR-MAS) MR spectra with different degrees of misalignments, and their merits are discussed. In addition, extraction of information that might be present in the shifts is examined, both for simulated data and the real MR spectra. The generic evaluation methodology employs a number of frequently used quality criteria for evaluation of the alignments, together with PLS-DA to assess the influence of alignment on the classification outcome. Peak alignment greatly improved the internal similarity of the data sets. Especially icoshift and COW seem suitable for aligning HR-MAS MR spectra, possibly because they perform alignment segment-wise. The choice of reference spectrum can influence the alignment result, and it is advisable to test several references. Information from the peak shifts was extracted, and in one case cancer samples were successfully discriminated from normal tissue based on shift information only. Based on these findings, general recommendations for alignment of HR-MAS MRS data are presented. Where possible, observations are generalized to other data types (e.g. chromatographic data). PMID:21094376

  3. Design of High Resolution Soft X-Ray Microcalorimeters Using Magnetic Penetration Thermometers

    NASA Technical Reports Server (NTRS)

    Busch. Sarah; Balvin, Manuel; Bandler, Simon; Denis, Kevin; Finkbeiner, Fred; Porst, Jan-Patrick; Sadlier, Jack; Smith, Stephen; Stevenson, Thomas

    2012-01-01

    We have designed high-resolution soft x-ray microcalorimeters using magnetic penetration thermometers (MPTs) in an array of pixels covering a total of 2 square centimeters to have a resolving power of 300 at energies around 300 eV. This performance is desirable for studying the soft x-ray background from the warm hot intergalactic medium. MPT devices have small sensor heat capacity and high responsivities, which makes them excellent detector technology for attempting to attain sub-eV resolution. We are investigating the feasibility of pixels with absorbers that are 625 x 625 square micrometers, up to 1 x 1 square millimeters in area and 0.35 micrometer thick and thinner. Our tests have shown that suspended gold absorbers 0.35 micrometers thick (RRR = 6.7) are feasible to fabricate. We modeled the thermal diffusion from such thin gold over the size of a 625 x 625 square micrometer absorber, and conclude that the effect of the thermalization on the resolution of a 300 eV photon is an additional approximately 0.2 eV FWHM of broadening. We discuss the thermal effects of small absorber attachment sterns on solid substrate, as well as considerations for multiplexed readout. We will present the progress we have made towards building and testing this soft x-ray detector.

  4. A full range detector for the HIRRBS high resolution RBS magnetic spectrometer

    NASA Astrophysics Data System (ADS)

    Skala, Wayne G.; Haberl, Arthur W.; Bakhru, Hassaram; Lanford, William

    2013-04-01

    The UAlbany HIRRBS (High Resolution RBS) system has been updated for better use in rapid analysis. The focal plane detector now covers the full range from U down to O using a linear stepper motor to translate the 1-cm detector across the 30-cm range. Input is implemented with zero-back-angle operation in all cases. The chamber has been modified to allow for quick swapping of sample holders, including a channeling goniometer. A fixed standard surface-barrier detector allows for normal RBS simultaneously with use of the magnetic spectrometer. The user can select a region on the standard spectrum or can select an element edge or an energy point for collection of the expanded spectrum portion. The best resolution currently obtained is about 2-to-3 keV, probably representing the energy width of the incoming beam. Calibration is maintained automatically for any spectrum portion and any beam energy from 1.0 to 3.5 MeV. Element resolving power, sensitivity and depth resolution are shown using several examples. Examples also show the value of simultaneous conventional RBS.

  5. Relating speech production to tongue muscle compressions using tagged and high-resolution magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Xing, Fangxu; Ye, Chuyang; Woo, Jonghye; Stone, Maureen; Prince, Jerry

    2015-03-01

    The human tongue is composed of multiple internal muscles that work collaboratively during the production of speech. Assessment of muscle mechanics can help understand the creation of tongue motion, interpret clinical observations, and predict surgical outcomes. Although various methods have been proposed for computing the tongue's motion, associating motion with muscle activity in an interdigitated fiber framework has not been studied. In this work, we aim to develop a method that reveals different tongue muscles' activities in different time phases during speech. We use fourdimensional tagged magnetic resonance (MR) images and static high-resolution MR images to obtain tongue motion and muscle anatomy, respectively. Then we compute strain tensors and local tissue compression along the muscle fiber directions in order to reveal their shortening pattern. This process relies on the support from multiple image analysis methods, including super-resolution volume reconstruction from MR image slices, segmentation of internal muscles, tracking the incompressible motion of tissue points using tagged images, propagation of muscle fiber directions over time, and calculation of strain in the line of action, etc. We evaluated the method on a control subject and two postglossectomy patients in a controlled speech task. The normal subject's tongue muscle activity shows high correspondence with the production of speech in different time instants, while both patients' muscle activities show different patterns from the control due to their resected tongues. This method shows potential for relating overall tongue motion to particular muscle activity, which may provide novel information for future clinical and scientific studies.

  6. Inductively-overcoupled coil design for high resolution magnetic resonance imaging

    PubMed Central

    Bilgen, Mehmet

    2006-01-01

    Background Maintaining the quality of magnetic resonance images acquired with the current implantable coil technology is challenging in longitudinal studies. To overcome this challenge, the principle of 'inductive overcoupling' is introduced as a method to tune and match a dual coil system. This system consists of an imaging coil built with fixed electrical elements and a matching coil equipped with tuning and matching capabilities. Overcoupling here refers to the condition beyond which the peak of the current in the imaging coil splits. Methods The combined coils are coupled inductively to operate like a transformer. Each coil circuit is electrically represented by equivalent lumped-elements. A theoretical analysis is given to identify the frequency response characteristics of the currents in each coil. The predictions from this analysis are translated into experiments and applied to locally image rat spinal cord at 9.4 T using an implantable coil as the imaging coil and an external volume coil as the matching coil. Results The theoretical analysis indicated that strong coupling between the coils divides the resonance peaks on the response curves of the currents. Once these newly generated peaks were tuned and matched to the desired frequency and impedance of operation, in vivo images were acquired from the rat spinal cord at high quality and high resolution. Conclusion After proper implementation, inductive overcoupling provides a unique opportunity for tuning and matching the coil system, and allows reliable and repeatable acquisitions of magnetic resonance data. This feature is likely to be useful in experimental studies, such as those aimed at longitudinally imaging the rat following spinal cord injury. PMID:16401343

  7. Effect of Low-Pass Filtering in Force Calibration of Magnetic Tweezers

    NASA Astrophysics Data System (ADS)

    Zheng, Hai-Zi; Nong, Da-Guan; Li, Ming

    2013-11-01

    In typical experiments where magnetic tweezers are involved, precise measurement of the magnetic forces is of crucial importance. To achieve this, a widely applied method is to track the bead's Brownian motion trajectory and to calculate the force from its mean-squared-displacement. However, this method does not take into account the fact that the bead-tracking device always has a finite bandwidth, acting effectively as a low-pass filter. The result could be subjected to significant system errors, which overestimates the magnetic force. We analyze the power spectrum of the bead's Brownian motion, and provide a corrected formula to calculate the magnetic force, which is free of system errors induced by limited detection bandwidth. A dsDNA force-extension curve is experimentally measured. The curve is consistent with the WLC model, exhibiting correctness of the new formula. On the other hand, the force given by the traditional method shows significant deviation from the WLC model, which is 3 times larger at most.

  8. High-resolution Measurement Of Magnetic Anomalies With An Unmanned Airship

    NASA Astrophysics Data System (ADS)

    Petzke, M.; Hofmeister, P.; Auster, H.; Hoerdt, A.; Glassmeier, K.

    2011-12-01

    High-resolution magnetic mapping of areas is a suitable way to determine location, geometry and physical parameters of disturbing objects that cause magnetic anomalies. Areas are often difficult to walk and handheld measurements can become costly. It can also be dangerous to enter areas where ordnance is suspected. In these cases it may be advantageous to use an aircraft to perform the measurement. We use a 6.5 m long unmanned airship. Compared to helicopters or gyrocopters, an advantage is that the damage in case of hazards is almost negligible. We made considerable efforts to construct a system that is easy to control without intense training under moderate wind conditions (up to 2 m/s wind speed). The airship has a mass of 10 kg and is powered by four electric motors with a maximum total power of 4.8 kW. Two of the rotors are used to control the altitude of the ship; the other two can be used to control direction and speed. The required energy is provided by four 4S1P Lithium-Polymer battery packs. Batteries are designed to provide a maximum of 125 A at 14.8 V. They have a capacity of 0.3 kWh and can be recharged in 20 minutes. The airship carries a differential GPS receiver that measures the position of the airship at 100 Hz with a precision of 10 cm. The distance to the ground is measured with ultrasonic sensors. A fluxgate magnetometer measures the magnetic field with an accuracy of 1 nT, also at 100 Hz. The flight path does not follow a rigid measuring grid but is a random walk, with roughly constant altitude to achieve a mean sensor position of 2 m above the ground. Thus, near-surface disturbing bodies are well resolved if their distance from each other is greater than 4 m. First measurements demonstrate the feasibility of the system. Future applications will be mid-scale measurements which are too large or too cumbersome for handheld measurements, and too small to justify the use of a manned helicopter.

  9. Lymphedematous skin and subcutis: in vivo high resolution magnetic resonance imaging evaluation.

    PubMed

    Idy-Peretti, I; Bittoun, J; Alliot, F A; Richard, S B; Querleux, B G; Cluzan, R V

    1998-05-01

    Physico-chemical and morphologic parameters of skin layers and subcutaneous tissue in lymphedematous limb were studied in vivo using magnetic resonance imaging. High resolution images were obtained with a depth resolution of about 70 microm, using a specific surface gradient coil specially designed for skin imaging and connected to a standard whole-body imager at 1.5 T. Twenty-one patients with unilateral lower extremity lymphedema (11 primary and 10 secondary) were examined. Skin thickness, relaxation times, and relative proton density were calculated in lymphedematous limbs and in contralateral extremities. In diseased limbs, the average skin thickness (2.17 mm) was significantly larger (p = 1.5 x 10(-4)) than that of contralateral limb (1.14 mm). Major cutaneous alterations due to lymphedema took place in dermis. In lymphedematous dermis, the significant increase of relaxation time values could be due to a shift in the equilibrium of water inside this tissue in relation to the interactions between macromolecules and water molecules. In lymphedematous epidermis our results showed an increase in the number of free water protons. Information about water and fat distribution in lymphedema was also obtained using chemical shift weighted images. Our results demonstrated a water retention diffusely spread over the entire dermis, and an important fluid retention located in the interlobular spacing and beside the superficial fascia. Inside the subcutis, the mean thickness of the superficial fat lobules was increased more than that of the deep fat lobules. From all the various measurements we could not distinguish primary from secondary lymphedema. PMID:9579546

  10. The potential of 3T high-resolution magnetic resonance imaging for diagnosis, staging, and follow-up of retinoblastoma.

    PubMed

    de Jong, Marcus C; de Graaf, Pim; Brisse, Hervé J; Galluzzi, Paolo; Göricke, Sophia L; Moll, Annette C; Munier, Francis L; Popovic, Maja Beck; Moulin, Alexandre P; Binaghi, Stefano; Castelijns, Jonas A; Maeder, Philippe

    2015-01-01

    We demonstrate the value of high-resolution magnetic resonance imaging (MRI) in diagnosing, staging, and follow-up of retinoblastoma during eye-saving treatment. We have included informative retinoblastoma cases scanned on a 3T MRI system from a retrospective retinoblastoma cohort from 2009 through 2013. We show that high-resolution MRI has the potential to detect small intraocular seeds, hemorrhage, and metastatic risk factors not visible with fundoscopy (e.g., optic nerve invasion and choroidal invasion), and treatment response. Unfortunately, however, the diagnostic accuracy of high-resolution MRI is not perfect, especially for subtle intraocular seeds or minimal postlaminar optic nerve invasion. The most important application of MRI is the detection of metastatic risk factors, as these cannot be found by fundoscopy and ultrasound. PMID:25891031

  11. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment

    NASA Astrophysics Data System (ADS)

    Huang, Yuqing; Lin, Yung-Ya; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin; Chen, Zhong

    2016-03-01

    High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.

  12. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment.

    PubMed

    Huang, Yuqing; Lin, Yung-Ya; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin; Chen, Zhong

    2016-03-14

    High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising. PMID:26979686

  13. High resolution 1H nuclear magnetic resonance of a transmembrane peptide.

    PubMed Central

    Davis, J. H.; Auger, M.; Hodges, R. S.

    1995-01-01

    Although the strong 1H-1H dipolar interaction is known to result in severe homogeneous broadening of the 1H nuclear magnetic resonance (NMR) spectra of ordered systems, in the fluid phase of biological and model membranes the rapid, axially symmetric reorientation of the molecules about the local bilayer normal projects the dipolar interaction onto the motional symmetry axis. Because the linewidth then scales as (3 cos2 theta-1)/2, where theta is the angle between the local bilayer normal and the magnetic field, the dipolar broadening has been reduced to an "inhomogeneous" broadening by the rapid axial reorientation. It is then possible to obtain high resolution 1H-NMR spectra of membrane components by using magic angle spinning (MAS). Although the rapid axial reorientation effectively eliminates the homogeneous dipolar broadening, including that due to n = 0 rotational resonances, the linewidths observed in both lipids and peptides are dominated by low frequency motions. For small peptides the most likely slow motions are either a "wobble" or reorientation of the molecular diffusion axis relative to the local bilayer normal, or the reorientation of the local bilayer normal itself through surface undulations or lateral diffusion over the curved surface. These motions render the peptide 1H-NMR lines too broad to be observed at low spinning speeds. However, the linewidths due to these slow motions are very sensitive to spinning rate, so that at higher speeds the lines become readily visible. The synthetic amphiphilic peptide K2GL20K2A-amide (peptide-20) has been incorporated into bilayers of 1,2-di-d 27-myristoyl-sn-glycero-3-phosphocholine (DMPC-d54) and studied by high speed 1H-MAS-NMR. The linewidths observed for this transbilayer peptide, although too broad to be observable at spinning rates below -5 kHz, are reduced to 68 Hz at a spinning speed of 14 kHz (at 500C). Further improvements in spinning speed and modifications in sample composition designed to reduce

  14. Portable magnetic tweezers device enables visualization of the three-dimensional microscale deformation of soft biological materials.

    PubMed

    Yang, Yali; Lin, Jun; Meschewski, Ryan; Watson, Erin; Valentine, Megan T

    2011-07-01

    We have designed and built a magnetic tweezers device that enables the application of calibrated stresses to soft materials while simultaneously measuring their microscale deformation using confocal microscopy. Unlike previous magnetic tweezers designs, our device is entirely portable, allowing easy use on microscopes in core imaging facilities or in collaborators' laboratories. The imaging capabilities of the microscope are unimpaired, enabling the 3-D structures of fluorescently labeled materials to be precisely determined under applied load. With this device, we can apply a large range of forces (~1-1200 pN) over micron-scale contact areas to beads that are either embedded within 3-D matrices or attached to the surface of thin slab gels. To demonstrate the usefulness of this instrument, we have studied two important and biologically relevant materials: polyacrylamide-based hydrogel films typical of those used in cell traction force microscopy, and reconstituted networks of microtubules, essential cytoskeletal filaments. PMID:21781050

  15. High-resolution magnetic resonance imaging: three-dimensional trabecular bone architecture and biomechanical properties.

    PubMed

    Majumdar, S; Kothari, M; Augat, P; Newitt, D C; Link, T M; Lin, J C; Lang, T; Lu, Y; Genant, H K

    1998-05-01

    The purpose of this study was to use high-resolution magnetic resonance (MR) imaging combined with image analysis to investigate the three-dimensional (3D) trabecular structure, anisotropy, and connectivity of human vertebral, femoral, and calcaneal specimens. The goal was to determine whether: (a) MR-derived measures depict known skeletal-site-specific differences in architecture and orientation of trabeculae; (b) 3D architectural parameters combined with bone mineral density (BMD) improve the prediction of the elastic modulus using a fabric tensor formulation; (c) MR-derived 3D architectural parameters combined with BMD improve the prediction of strength using a multiple regression model, and whether these results corresponded to the results obtained using higher resolution depictions of trabecular architecture. A total of 94 specimens (12 x 12 x 12 mm cubes) consisting of trabecular bone only were obtained, of which there were 7 from the calcaneus, 15 from distal femur, 47 from the proximal femur, and 25 from the vertebral bodies. MR images were obtained using a 1.5 Tesla MR scanner at a spatial resolution of 117 x 117 x 300 microm. Additionally, BMD was determined using quantitative computed tomography (QCT), and the specimens were nondestructively tested and the elastic modulus (YM) was measured along three orthogonal axes corresponding to the anatomic superior-inferior (axial), medial-lateral (sagittal), and anterior-posterior (coronal) directions. A subset of the specimens (n=67) was then destructively tested in the superior-inferior (axial) direction to measure the ultimate compressive strength. The MR images were segmented into bone and marrow phases and then analyzed in 3D. Ellipsoids were fitted to the mean intercept lengths, using single value decomposition and the primary orientation of the trabeculae and used to calculate the anisotropy of trabecular architecture. Stereological measures were derived using a previously developed model and measures such

  16. Improved dosimetry in prostate brachytherapy using high resolution contrast enhanced magnetic resonance imaging: a feasibility study

    PubMed Central

    Morancy, Tye; Kaplan, Irving; Qureshi, Muhammad M.; Hirsch, Ariel E.; Rofksy, Neil M.; Holupka, Edward; Oismueller, Renee; Hawliczek, Robert; Helbich, Thomas H.; Bloch, B. Nicolas

    2014-01-01

    Purpose To assess detailed dosimetry data for prostate and clinical relevant intra- and peri-prostatic structures including neurovascular bundles (NVB), urethra, and penile bulb (PB) from postbrachytherapy computed tomography (CT) versus high resolution contrast enhanced magnetic resonance imaging (HR-CEMRI). Material and methods Eleven postbrachytherapy prostate cancer patients underwent HR-CEMRI and CT imaging. Computed tomography and HR-CEMRI images were randomized and 2 independent expert readers created contours of prostate, intra- and peri-prostatic structures on each CT and HR-CEMRI scan for all 11 patients. Dosimetry data including V100, D90, and D100 was calculated from these contours. Results Mean V100 values from CT and HR-CEMRI contours were as follows: prostate (98.5% and 96.2%, p = 0.003), urethra (81.0% and 88.7%, p = 0.027), anterior rectal wall (ARW) (8.9% and 2.8%, p < 0.001), left NVB (77.9% and 51.5%, p = 0.002), right NVB (69.2% and 43.1%, p = 0.001), and PB (0.09% and 11.4%, p = 0.005). Mean D90 (Gy) derived from CT and HR-CEMRI contours were: prostate (167.6 and 150.3, p = 0.012), urethra (81.6 and 109.4, p = 0.041), ARW (2.5 and 0.11, p = 0.003), left NVB (98.2 and 58.6, p = 0.001), right NVB (87.5 and 55.5, p = 0.001), and PB (11.2 and 12.4, p = 0.554). Conclusions Findings of this study suggest that HR-CEMRI facilitates accurate and meaningful dosimetric assessment of prostate and clinically relevant structures, which is not possible with CT. Significant differences were seen between CT and HR-CEMRI, with volume overestimation of CT derived contours compared to HR-CEMRI. PMID:25834576

  17. Grooved multi-pole magnetic gratings for high-resolution positioning systems

    NASA Astrophysics Data System (ADS)

    Xu, Zhi-Hao; Tseng, Bin-Hui; Chang, Ching; Wang, Sheng-Ching; Chin, Tsung-Shune; Sung, Cheng-Kuo

    2015-06-01

    Magnetic encoders are much advantageous for precision positioning specifically under harsh environments. The finer the magnetic pole-pitches of the magnetic scale in a magnetic encoder the higher the resolution of the encoder. In this paper, a grooved multi-pole magnetic grating (MPMG) is substituted for conventional non-structured magnetic scale. A MPMG with pole-pitch of 200 µm was prepared by photo-lithography and electro-deposition. Simulation was first done to attain the relationship among magnetic flux density, magnetic properties of electrodeposited alloy layers, magnetizing directions and the grating dimensions. The MPMG can be fully magnetized for use by just a single pulse in a solenoid coil. Magnetic properties were investigated in which CoNiP layers were electrodeposited under various current densities. Measured magnetic flux densities versus grating heights, magnetizing directions and detection gaps on magnetized MPMG validate the applicability of ultra-fine pitched MPMG.

  18. Integrated magnetic tweezers and single-molecule FRET for investigating the mechanical properties of nucleic acid.

    PubMed

    Long, Xi; Parks, Joseph W; Stone, Michael D

    2016-08-01

    Many enzymes promote structural changes in their nucleic acid substrates via application of piconewton forces over nanometer length scales. Magnetic tweezers (MT) is a single molecule force spectroscopy method widely used for studying the energetics of such mechanical processes. MT permits stable application of a wide range of forces and torques over long time scales with nanometer spatial resolution. However, in any force spectroscopy experiment, the ability to monitor structural changes in nucleic acids with nanometer sensitivity requires the system of interest to be held under high degrees of tension to improve signal to noise. This limitation prohibits measurement of structural changes within nucleic acids under physiologically relevant conditions of low stretching forces. To overcome this challenge, researchers have integrated a spatially sensitive fluorescence spectroscopy method, single molecule-FRET, with MT to allow simultaneous observation and manipulation of nanoscale structural transitions over a wide range of forces. Here, we describe a method for using this hybrid instrument to analyze the mechanical properties of nucleic acids. We expect that this method for analysis of nucleic acid structure will be easily adapted for experiments aiming to interrogate the mechanical responses of other biological macromolecules. PMID:27320203

  19. Disturbance-free rapid solution exchange for magnetic tweezers single-molecule studies

    PubMed Central

    Le, Shimin; Yao, Mingxi; Chen, Jin; Efremov, Artem K.; Azimi, Sara; Yan, Jie

    2015-01-01

    Single-molecule manipulation technologies have been extensively applied to studies of the structures and interactions of DNA and proteins. An important aspect of such studies is to obtain the dynamics of interactions; however the initial binding is often difficult to obtain due to large mechanical perturbation during solution introduction. Here, we report a simple disturbance-free rapid solution exchange method for magnetic tweezers single-molecule manipulation experiments, which is achieved by tethering the molecules inside microwells (typical dimensions–diameter (D): 40–50 μm, height (H): 100 μm; H:D∼2:1). Our simulations and experiments show that the flow speed can be reduced by several orders of magnitude near the bottom of the microwells from that in the flow chamber, effectively eliminating the flow disturbance to molecules tethered in the microwells. We demonstrate a wide scope of applications of this method by measuring the force dependent DNA structural transitions in response to solution condition change, and polymerization dynamics of RecA on ssDNA/SSB-coated ssDNA/dsDNA of various tether lengths under constant forces, as well as the dynamics of vinculin binding to α-catenin at a constant force (< 5 pN) applied to the α-catenin protein. PMID:26007651

  20. Disturbance-free rapid solution exchange for magnetic tweezers single-molecule studies.

    PubMed

    Le, Shimin; Yao, Mingxi; Chen, Jin; Efremov, Artem K; Azimi, Sara; Yan, Jie

    2015-09-30

    Single-molecule manipulation technologies have been extensively applied to studies of the structures and interactions of DNA and proteins. An important aspect of such studies is to obtain the dynamics of interactions; however the initial binding is often difficult to obtain due to large mechanical perturbation during solution introduction. Here, we report a simple disturbance-free rapid solution exchange method for magnetic tweezers single-molecule manipulation experiments, which is achieved by tethering the molecules inside microwells (typical dimensions-diameter (D): 40-50 μm, height (H): 100 μm; H:D∼2:1). Our simulations and experiments show that the flow speed can be reduced by several orders of magnitude near the bottom of the microwells from that in the flow chamber, effectively eliminating the flow disturbance to molecules tethered in the microwells. We demonstrate a wide scope of applications of this method by measuring the force dependent DNA structural transitions in response to solution condition change, and polymerization dynamics of RecA on ssDNA/SSB-coated ssDNA/dsDNA of various tether lengths under constant forces, as well as the dynamics of vinculin binding to α-catenin at a constant force (< 5 pN) applied to the α-catenin protein. PMID:26007651

  1. Stem cell implantation in ischemic mouse heart: a high-resolution magnetic resonance imaging investigation.

    PubMed

    Küstermann, Ekkehard; Roell, Wilhelm; Breitbach, Martin; Wecker, Stefan; Wiedermann, Dirk; Buehrle, Christian; Welz, Armin; Hescheler, Juergen; Fleischmann, Bernd K; Hoehn, Mathias

    2005-10-01

    Advances in the biology of stem cells have evoked great interest in cell replacement therapies for the regeneration of heart tissue after myocardial infarction. However, results from human trials are controversial, since the destination of the injected cells, their engraftment and their long-term fate have remained unclear. Here we investigate whether transplanted cells can be identified in the intact and lesioned murine myocardium employing high-resolution MRI. Cardiac progenitor cells, expressing the enhanced green fluorescent protein (EGFP), were labeled with ultra-small paramagnetic iron-oxide (USPIO) nanoparticles and transplanted into the intact or injured myocardium of mice. Their precise location was determined with high-resolution MRI and compared with histological tissue sections, stained with Prussian blue for iron content. These experiments showed that iron nanoparticle-loaded cells could be identified at high resolution in the mouse heart. However, ischemic myocardium (after cryoinjury or left coronary artery ligation) was characterized by a signal attenuation similar to that induced by USPIO-labeled cells in T2*-weighted MR images, making detection of labeled stem cells in this area by T2*-sensitive contrast rather difficult. In animals with myocardial injury only, the signal attenuated areas were of the same size in proton density- and T2*-weighted MR images. In injured animals also receiving labeled cells the lesioned area appeared larger in T2*--than in proton density-weighted MR images. This sequence-dependent lesion size change is due to the increased signal loss caused by the iron oxide nanoparticles, most sensitively detectable in the T2*-sensitive images. Thus, using the novel combination of these two parameter weightings, USPIO-labeled cells can be detected at high resolution in ischemic myocardium. PMID:15948224

  2. High-precision three-dimensional field mapping of a high resolution magnetic spectrometer for hypernuclear spectroscopy at JLab

    SciTech Connect

    Fujii, Yuu; Hashimoto, Osamu; Miyoshi, Toshinobu; Nakamura, Satoshi N.; Ohtani, Atsushi; Okayasu, Yuichi; Oyamada, Masamichi; Yamamoto, Yosuke; Kato, Seigo; Matsui, Jumei; Sako, Katsuhisa; Brindza, Paul

    2015-09-01

    The High Resolution Kaon Spectrometer (HKS), which consists of two quadrupole magnets and one dipole magnet, was designed and constructed for high-resolution spectroscopy of hypernuclei using the (e,e'K+) reaction in Hall C, Jefferson Lab (JLab). It was used to analyze momenta of around 1.2 GeV/c K^+ s with a resolution of 2 ×10^-4 (FWHM). To achieve the target resolution, a full three-dimensional magnetic field measurement of each magnet was successfully performed, and a full three-dimensional magnetic field map of the HKS magnets was reconstructed. Using the measured field map, the initial reconstruction function was generated. The target resolution would be achieved via careful tuning of the reconstruction function of HKS with the p(e,e'K+)Lambda,Sigma^0 and C-12 (e,e'K+)12_Lambda B_g.s. reactions. After tuning of the initial reconstruction function generated from the measured map, the estimated HKS momentum resolution was 2.2×10^-4 (FWHM).

  3. High resolution T2(*)-weighted Magnetic Resonance Imaging at 3 Tesla using PROPELLER-EPI.

    PubMed

    Krämer, Martin; Reichenbach, Jürgen R

    2014-05-01

    We report the application of PROPELLER-EPI for high resolution T2(*)-weighted imaging with sub-millimeter in-plane resolution on a clinical 3 Tesla scanner. Periodically rotated blades of a long-axis PROPELLER-EPI sequence were acquired with fast gradient echo readout and acquisition matrix of 320 × 50 per blade. Images were reconstructed by using 2D-gridding, phase and geometric distortion correction and compensation of resonance frequency drifts that occurred during extended measurements. To characterize these resonance frequency offsets, short FID calibration measurements were added to the PROPELLER-EPI sequence. Functional PROPELLER-EPI was performed with volunteers using a simple block design of right handed finger tapping. Results indicate that PROPELLER-EPI can be employed for fast, high resolution T2(*)-weighted imaging provided geometric distortions and possible resonance frequency drifts are properly corrected. Even small resonance frequency drifts below 10 Hz as well as non-corrected geometric distortions degraded image quality substantially. In the initial fMRI experiment image quality and signal-to-noise ratio was sufficient for obtaining high resolution functional activation maps. PMID:24439698

  4. Spatially resolved high resolution x-ray spectroscopy for magnetically confined fusion plasmas (invited)

    SciTech Connect

    Ince-Cushman, A.; Rice, J. E.; Reinke, M. L.; Podpaly, Y.; Marmar, E. S.; Bitter, M.; Hill, K. W.; Scott, S.; Gu, M. F.; Eikenberry, E.; Broennimann, Ch.; Lee, S. G.

    2008-10-15

    The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage of a new x-ray imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in x-ray detector technology [Ch. Broennimann et al., J. Synchrotron Radiat. 13, 120 (2006)], a spatially resolving high resolution x-ray spectrometer has been built and installed on the Alcator C-Mod tokamak. This instrument utilizes a spherically bent quartz crystal and a set of two dimensional x-ray detectors arranged in the Johann configuration [H. H. Johann, Z. Phys. 69, 185 (1931)] to image the entire plasma cross section with a spatial resolution of about 1 cm. The spectrometer was designed to measure line emission from H-like and He-like argon in the wavelength range 3.7 and 4.0 A with a resolving power of approximately 10 000 at frame rates up to 200 Hz. Using spectral tomographic techniques [I. Condrea, Phys. Plasmas 11, 2427 (2004)] the line integrated spectra can be inverted to infer profiles of impurity emissivity, velocity, and temperature. From these quantities it is then possible to calculate impurity density and electron temperature profiles. An overview of the instrument, analysis techniques, and example profiles are presented.

  5. Radiation-Induced Damage to Microstructure of Parotid Gland: Evaluation Using High-Resolution Magnetic Resonance Imaging

    SciTech Connect

    Kan, Tomoko; Kodani, Kazuhiko; Michimoto, Koichi; Fujii, Shinya; Ogawa, Toshihide

    2010-07-15

    Purpose: To elucidate the radiation-induced damage to the microstructure of the parotid gland using high-resolution magnetic resonance imaging. Methods and Materials: High-resolution magnetic resonance imaging of the parotid gland was performed before radiotherapy (RT) and during the RT period or {<=}3 weeks after RT completion for 12 head-and-neck cancer patients using a 1.5-T scanner with a microscopy coil. The maximal cross-sectional area of the gland was evaluated, and changes in the internal architecture of the gland were assessed both visually and quantitatively. Results: Magnetic resonance images were obtained at a median parotid gland dose of 36 Gy (range, 11-64). According to the quantitative analysis, the maximal cross-sectional area of the gland was reduced, the width of the main duct was narrowed, and the intensity ratio of the main duct lumen to background was significantly decreased after RT (p <.0001). According to the visual assessment, the width of the main duct tended to narrow and the contrast of the duct lumen tended to be decreased, but no significant differences were noted. The visibility of the duct branches was unclear in 10 patients (p = .039), and the septum became dense in 11 patients (p = .006) after RT. Conclusion: High-resolution magnetic resonance imaging is a noninvasive method of evaluating radiation-induced changes to the internal architecture of the parotid gland. Morphologic changes in the irradiated parotid gland were demonstrated during the RT course even when a relatively small dose was delivered to the gland.

  6. Optical Tweezers

    NASA Astrophysics Data System (ADS)

    Jones, Philip H.; Maragò, Onofrio M.; Volpe, Giovanni

    2015-12-01

    1. Introduction; Part I. Theory: 2. Ray optics; 3. Dipole approximation; 4. Optical beams and focusing; 5. Electromagnetic theory; 6. Computational methods; 7. Brownian motion; Part II. Practice: 8. Building an optical tweezers; 9. Data acquisition and optical tweezers calibration; 10. Photonic force microscope; 11. Wavefront engineering and holographic optical tweezers; 12. Advanced techniques; Part III. Applications: 13. Single molecule biophysics; 14. Cell biology; 15. Spectroscopy; 16. Optofluidics and lab on a chip; 17. Colloid science; 18. Microchemistry; 19. Aerosol science; 20. Statistical physics; 21. Nanothermodynamics; 22. Plasmonics; 23. Nanostructures; 24. Laser cooling and trapping of atoms; 25. Towards the quantum regime at the mesoscale; Index.

  7. Experimental phase diagram of negatively supercoiled DNA measured by magnetic tweezers and fluorescence

    NASA Astrophysics Data System (ADS)

    Vlijm, Rifka; Mashaghi, Alireza; Bernard, Stéphanie; Modesti, Mauro; Dekker, Cees

    2015-02-01

    The most common form of DNA is the well-known B-structure of double-helix DNA. Many processes in the cell, however, exert force and torque, inducing structural changes to the DNA that are vital to biological function. Virtually all DNA in cells is in a state of negative supercoiling, with a DNA structure that is complex. Using magnetic tweezers combined with fluorescence imaging, we here study DNA structure as a function of negative supercoiling at the single-molecule level. We classify DNA phases based on DNA length as a function of supercoiling, down to a very high negative supercoiling density σ of -2.5, and forces up to 4.5 pN. We characterize plectonemes using fluorescence imaging. DNA bubbles are visualized by the binding of fluorescently labelled RPA, a eukaryotic single-strand-binding protein. The presence of Z-DNA, a left-handed form of DNA, is probed by the binding of Zα77, the minimal binding domain of a Z-DNA-binding protein. Without supercoiling, DNA is in the relaxed B-form. Upon going toward negative supercoiling, plectonemic B-DNA is being formed below 0.6 pN. At higher forces and supercoiling densities down to about -1.9, a mixed state occurs with plectonemes, multiple bubbles and left-handed L-DNA. Around σ = -1.9, a buckling transition occurs after which the DNA end-to-end length linearly decreases when applying more negative turns, into a state that we interpret as plectonemic L-DNA. By measuring DNA length, Zα77 binding, plectoneme and ssDNA visualisation, we thus have mapped the co-existence of many DNA structures and experimentally determined the DNA phase diagram at (extreme) negative supercoiling.The most common form of DNA is the well-known B-structure of double-helix DNA. Many processes in the cell, however, exert force and torque, inducing structural changes to the DNA that are vital to biological function. Virtually all DNA in cells is in a state of negative supercoiling, with a DNA structure that is complex. Using magnetic tweezers

  8. High-resolution solid-state nuclear magnetic resonance experiments on highly radioactive ceramics

    NASA Astrophysics Data System (ADS)

    Farnan, Ian; Cho, Herman; Weber, William J.; Scheele, Randall D.; Johnson, Nigel R.; Kozelisky, Anne E.

    2004-12-01

    A triple-containment magic-angle spinning rotor insert system has been developed and a sample handling procedure formulated for safely analyzing highly radioactive solids by high-resolution solid-state NMR. The protocol and containment system have been demonstrated for magic-angle spinning (MAS) experiments on ceramic samples containing 5-10 wt % 239Pu and 238Pu at rotation speeds of 3500 Hz. The technique has been used to demonstrate that MAS NMR experiments can be used to measure amorphous atomic number fractions produced by accelerated internal radiation damage. This will allow incorporated α-emitters with short half-lives to be used to model the long-term radiation tolerance of potential ceramic radioactive waste forms. This is an example of MAS NMR spectroscopy on samples containing fissionable isotopes.

  9. Plasma-assisted synthesis and high-resolution characterization of anisotropic elemental and bimetallic core–shell magnetic nanoparticles

    PubMed Central

    Lotnyk, A

    2014-01-01

    Summary Magnetically anisotropic as well as magnetic core–shell nanoparticles (CS-NPs) with controllable properties are highly desirable in a broad range of applications. With this background, a setup for the synthesis of heterostructured magnetic core–shell nanoparticles, which relies on (optionally pulsed) DC plasma gas condensation has been developed. We demonstrate the synthesis of elemental nickel nanoparticles with highly tunable sizes and shapes and Ni@Cu CS-NPs with an average shell thickness of 10 nm as determined with scanning electron microscopy, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements. An analytical model that relies on classical kinetic gas theory is used to describe the deposition of Cu shell atoms on top of existing Ni cores. Its predictive power and possible implications for the growth of heterostructured NP in gas condensation processes are discussed. PMID:24778973

  10. High Resolution Magic Angle Spinning 1H-NMR Metabolic Profiling of Nanoliter Biological Tissues at High Magnetic Field

    SciTech Connect

    Feng, Ju; Hu, Jian Z.; Burton, Sarah D.; Hoyt, David W.

    2013-03-05

    It is demonstrated that a high resolution magic angle spinning 1H-NMR spectrum of biological tissue samples with volumes as small as 150 nanoliters, or 0.15 mg in weight, can be acquired in a few minutes at 21.1 T magnetic field using a commercial 1.6 mm fast-MAS probe with minor modification of the MAS rotor. The strategies of sealing the samples inside the MAS rotor to avoid fluid leakage as well as the ways of optimizing the signal to noise are discussed.

  11. Simulation of High-Resolution Magnetic Resonance Images on the IBM Blue Gene/L Supercomputer Using SIMRI

    DOE PAGESBeta

    Baum, K. G.; Menezes, G.; Helguera, M.

    2011-01-01

    Medical imaging system simulators are tools that provide a means to evaluate system architecture and create artificial image sets that are appropriate for specific applications. We have modified SIMRI, a Bloch equation-based magnetic resonance image simulator, in order to successfully generate high-resolution 3D MR images of the Montreal brain phantom using Blue Gene/L systems. Results show that redistribution of the workload allows an anatomically accurate 256 3 voxel spin-echo simulation in less than 5 hours when executed on an 8192-node partition of a Blue Gene/L system.

  12. The Spokane fault, Washington, Imaged with High-Resolution Airborne Magnetic Data—Implications for the 2001 Spokane Earthquake Sequence

    NASA Astrophysics Data System (ADS)

    Blakely, R. J.; Sherrod, B. L.; Weaver, C. S.; Stephenson, W. J.

    2015-12-01

    A newly acquired, high-resolution aeromagnetic survey provides insights into the near-surface lithology and tectonic structure throughout the greater Spokane area of northeastern Washington and northwestern Idaho. The region has a diverse array of magnetic lithologies, ranging from highly magnetic flood basalts of the Columbia River Basalt Group (CRBG) to weakly magnetic Mesozoic plutonic and metamorphic rocks. Faults within these magnetic lithologies produce linear magnetic anomalies that permit mapping of geologic structures over tens of kilometers. A high-amplitude, linear magnetic anomaly overlies the NW- striking Cheney fracture zone 37 km southwest of Spokane and is interpreted as a basaltic dike swarm intruded during the extensional event that opened the fractures, possibly feeder dikes for overlying CRBG flows. A sub-parallel anomaly near the town of Cheney reflects another dike swarm, likely formed during the same extensional event. The Latah fault is seen as a discontinuous alignment of magnetic anomalies extending north-northwestward from south of Spokane to the northern edge of the magnetic survey, a distance of 44 km. An arcuate, north-striking magnetic lineament ~20 km northeast of Spokane may mark the Newport fault, the detachment that promoted exhumation of the Priest River metamorphic complex. A subtle northeast-striking magnetic lineament passes through downtown Spokane and may indicate the trace of the Spokane fault, suspected of producing more than 105 small (M≤4), shallow earthquakes within Spokane city limits in 2001, accompanied by 15 mm of vertical uplift. This magnetic lineament extends 22 km and, to the northwest, merges with the lineament interpreted as the Newport fault. The Spokane fault may represent a reactivated section of the Newport fault that otherwise is not known to be active today. New LiDAR data from the Spokane area does not show distinct fault scarps associated with these magnetic anomalies, but a more comprehensive

  13. Magnetic tweezers measurement of the bond lifetime-force behavior of the IgG-protein A specific molecular interaction.

    PubMed

    Shang, Hao; Lee, Gil U

    2007-05-23

    The bond lifetime-force behavior of the immunoglobulin G (IgG)-protein A interaction has been studied with magnetic tweezers to characterize the physical properties of the bond under nonequilibrium conditions. Super-paramagnetic microparticles were developed that have a high and uniform magnetization to simultaneously apply a piconewton-scale tensile force to many thousands of IgG-protein A bonds. A strong and a weak slip bond were detected with an effective bond length that is characteristic of short-range, stiff intermolecular interactions. These bonds are attributed to the interaction of protein A with the constant region (Fc) and heavy chain variable domain (VH) of IgG, respectively. The IgG-VH interaction appears to be one of the weakest specific molecular interactions that has been identified with a single molecule force measurement technique. This study demonstrates that magnetic tweezers can be used to rapidly characterize very weak biomolecular interactions as well as strong biomolecular interactions with a high degree of accuracy. PMID:17465553

  14. High-Resolution Local Crustal Magnetic Field Modeling of the Martian South Pole

    NASA Astrophysics Data System (ADS)

    Plattner, A.; Simons, F. J.

    2014-12-01

    The Mars Global Surveyor (MGS) satellite mission has brought us a wealth of information about the Martian magnetic field. Besides determining that Mars currently does not possess an active core field, MGS revealed that Mars contains an unexpectedly wide crustal magnetic field intensity range. In its orbit insertion, MGS performed a series of low altitude passes down to around 100 km above surface. During this mission phase the magnetic field measurements were active. In particular the nighttime low-altitude data are of high interest because they contain minimal noise from solar wind. Since these data only cover a small portion of the planet's surface, to date all Martian crustal magnetic field models blend the highest-quality data with lower quality measurements collected either at higher satellite altitudes or during daytime. In this contribution we present a locally inverted crustal magnetic field model for the Martian South Polar region calculated from only the highest-quality MGS data using locally constructed altitude vector Slepian functions. The South Polar region of Mars contains the southern part of the strongly magnetized Terra Sirenum and the area south of the Tharsis volcanic highland. Besides parts of planetary scale features our area of data coverage also contains local features such as the presumably volcanic Australe Montes and the Prometheus impact crater. These ingredients compose a highly heterogeneous crustal magnetic field. We show that even for our dense low-altitude low-noise data set the inversion for the crustal magnetic field of a weakly magnetized region adjacent to a region containing a strong magnetic field leads to artifacts in the weak region. With our local method we can avoid these artifacts by selecting subregions of roughly homogeneous field intensity and individually invert for crustal magnetic fields from data within only these subregions. This regional and subregional modeling allows us to reveal previously obscured crustal

  15. Method for high resolution magnetic resonance analysis using magic angle technique

    DOEpatents

    Wind, Robert A.; Hu, Jian Zhi

    2004-12-28

    A method of performing a magnetic resonance analysis of a biological object that includes placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. The object may be reoriented about the magic angle axis between three predetermined positions that are related to each other by 120.degree.. The main magnetic field may be rotated mechanically or electronically. Methods for magnetic resonance imaging of the object are also described.

  16. Method for high resolution magnetic resonance analysis using magic angle technique

    DOEpatents

    Wind, Robert A.; Hu, Jian Zhi

    2003-12-30

    A method of performing a magnetic resonance analysis of a biological object that includes placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. The object may be reoriented about the magic angle axis between three predetermined positions that are related to each other by 120.degree.. The main magnetic field may be rotated mechanically or electronically. Methods for magnetic resonance imaging of the object are also described.

  17. Ultra-High-Resolution Observations of MHD Waves in Photospheric Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Jess, D. B.; Verth, G.

    2016-02-01

    This chapter reviews the recent observations of waves and oscillations manifesting in fine-scale magnetic structures in the solar photosphere, which are often interpreted as the "building blocks' of the magnetic Sun. The authors found, through phase relationships between the various waveforms, that small-scale magnetic bright points (MBPs) in the photosphere demonstrated signatures of specific magnetoacoustic waves, in particular the sausage and kink modes. Modern magnetohydrodynamic (MHD) simulations of the lower solar atmosphere clearly show how torsional motions can easily be induced in magnetic elements in the photosphere through the processes of vortical motions and/or buffeting by neighboring granules. The authors detected significant power associated with high-frequency horizontal motions, and suggested that these cases may be especially important in the creation of a turbulent environment that efficiently promotes Alfvén wave dissipation.

  18. Method for high resolution magnetic resonance analysis using magic angle technique

    DOEpatents

    Wind, Robert A.; Hu, Jian Zhi

    2003-11-25

    A method of performing a magnetic resonance analysis of a biological object that includes placing the biological object in a main magnetic field and in a radio frequency field, the main magnetic field having a static field direction; rotating the biological object at a rotational frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. According to another embodiment, the radio frequency is pulsed to provide a sequence capable of producing a spectrum that is substantially free of spinning sideband peaks.

  19. High-Resolution Seismic-Reflection and Marine Magnetic Data Along the Hosgri Fault Zone, Central California

    USGS Publications Warehouse

    Sliter, Ray W.; Triezenberg, Peter J.; Hart, Patrick E.; Watt, Janet T.; Johnson, Samuel Y.; Scheirer, Daniel S.

    2009-01-01

    The U.S. Geological Survey (USGS) collected high-resolution shallow seismic-reflection and marine magnetic data in June 2008 in the offshore areas between the towns of Cayucos and Pismo Beach, Calif., from the nearshore (~6-m depth) to just west of the Hosgri Fault Zone (~200-m depth). These data are in support of the California State Waters Mapping Program and the Cooperative Research and Development Agreement (CRADA) between the Pacific Gas & Electric Co. and the U.S. Geological Survey. Seismic-reflection and marine magnetic data were acquired aboard the R/V Parke Snavely, using a SIG 2Mille minisparker seismic source and a Geometrics G882 cesium-vapor marine magnetometer. More than 550 km of seismic and marine magnetic data was collected simultaneously along shore-perpendicular transects spaced 800 m apart, with an additional 220 km of marine magnetometer data collected across the Hosgri Fault Zone, resulting in spacing locally as smallas 400 m. This report includes maps of the seismic-survey sections, linked to Google Earth software, and digital data files showing images of each transect in SEG-Y, JPEG, and TIFF formats, as well as preliminary gridded marine-magnetic-anomaly and residual-magnetic-anomaly (shallow magnetic source) maps.

  20. Structure and dynamics of small scale magnetic fields in the solar atmosphere Results of high resolution polarimetry and image reconstruction

    NASA Astrophysics Data System (ADS)

    Janssen, K.

    2003-07-01

    Two-dimensional spectrograms were obtained at the Vacuum Tower Telescope, Tenerife, in order to study the structure of small scale magnetic fields on the Sun. The speckle reconstruction method that is used for data processing gives high resolution images and wavelength scans in left and right circular polarized light, from which magnetic field maps are calculated using the center of gravity method. The geometric similarity of magnetic structures is studied via the area- perimeter-relation, from which the Hausdorff-dimension of the rim of a structure is determined. The investigation shows that the actual value of the fractal dimension depends on the threshold that is used to determine the borders of the magnetic areas. Higher treshold values lead to smaller fractal dimensions. This can be explained by the concentration of strong magnetic fields while weak fields spread out in more complex structures. With a treshold of 80 Gauss a fractal dimension of D=1,40(5) is obtained. Furthermore, the dimension obtained by observed data is compared to the fractal dimension gained from MHD simulations. It is found that if the measurement scales are adjusted correctly the dimensions for both datasets match quite well. In a second part the dynamics of the mass motions were analysed and a coarse estimate of the energy conveyed by these movements to the magnetic field is given. The energy flux is strong enough to participate in the heating of the solar chromosphere and corona over active regions.

  1. High-Resolution B Dot Probe for Measuring 3D Magnetic Fields in the MOCHI Labjet Experiment

    NASA Astrophysics Data System (ADS)

    Azuara Rosales, Manuel; von der Linden, Jens; You, Setthivoine

    2014-10-01

    The MOCHI Labjet experiment will use a triple electrode planar plasma gun to explore canonical helicity transport in laboratory astrophysical jets. Canonical helicity transport suggests that destabilizing magnetic energy can be converted into stabilizing shear flows at two-fluid spatial scales li ~c/wpi . A high-resolution . B probe array, capable of measuring magnetic field dynamics at length and time scales important to canonical helicity transport is being built. The probe array consists of three tridents, made of 5 . 13 mm OD and 4 . 32 mm ID stainless steel tubes of 102 cm length, enclosing a total of 1215 commercial inductor chips with a three axis spatial resolution of 11 mm. The average value for the effective NA of each inductor chip is 1 . 21 .10-4 m2. The probe array lays in a plane perpendicular to the jet, and is axially translatable. This work is supported by US DOE Grant DE-SC0010340.

  2. Local high-resolution crustal magnetic field analysis from satellite data

    NASA Astrophysics Data System (ADS)

    Plattner, Alain; Simons, Frederik J.

    2016-04-01

    Planetary crustal magnetic fields are key to understanding a planet or moon's structure and history. Due to satellite orbit parameters such as aerobraking (Mars) or only partial coverage (Mercury), or simply because of the strongly heterogeneous crustal field strength, satellite data of planetary magnetic fields vary regionally in their signal-to noise ratio and data coverage. To take full advantage of data quality within one region of a planet or moon without diluting the data with lower quality measurements outside of that region we resort to local methods. Slepian functions are linear combinations of spherical harmonics that provide local sensitivity to structure. Here we present a selection of crustal magnetic field models obtained from vector-valued variable-altitude satellite observations using an altitude-cognizant gradient-vector Slepian approach. This method is based on locally maximizing energy concentration within the region of data availability while simultaneously bandlimiting the model in terms of its spherical-harmonic degree and minimizing noise amplification due to downward continuation. For simple regions such as spherical caps, our method is computationally efficient and allows us to calculate local crustal magnetic field solutions beyond spherical harmonic degree 800, if the data permit. We furthermore discuss extensions of the method that are optimized for the analysis and separation of internal and external magnetic fields.

  3. Single molecule measurements of DNA helicase activity with magnetic tweezers and t-test based step-finding analysis.

    PubMed

    Seol, Yeonee; Strub, Marie-Paule; Neuman, Keir C

    2016-08-01

    Magnetic tweezers is a versatile and easy to implement single-molecule technique that has become increasingly prevalent in the study of nucleic acid based molecular motors. Here, we provide a description of the magnetic tweezers instrument and guidelines for measuring and analyzing DNA helicase activity. Along with experimental methods, we describe a robust method of single-molecule trajectory analysis based on the Student's t-test that accommodates continuous transitions in addition to the discrete transitions assumed in most widely employed analysis routines. To illustrate the single-molecule unwinding assay and the analysis routine, we provide DNA unwinding measurements of Escherichia coli RecQ helicase under a variety of conditions (Na+, ATP, temperature, and DNA substrate geometry). These examples reveal that DNA unwinding measurements under various conditions can aid in elucidating the unwinding mechanism of DNA helicase but also emphasize that environmental effects on DNA helicase activity must be considered in relation to in vivo activity and mechanism. PMID:27131595

  4. High Resolution Magnetic Images of Planar Wave Fronts Reveal Bidomain Properties of Cardiac Tissue

    PubMed Central

    Holzer, Jenny R.; Fong, Luis E.; Sidorov, Veniamin Y.; Wikswo, John P.; Baudenbacher, Franz

    2004-01-01

    We magnetically imaged the magnetic action field and optically imaged the transmembrane potentials generated by planar wavefronts on the surface of the left ventricular wall of Langendorff-perfused isolated rabbit hearts. The magnetic action field images were used to produce a time series of two-dimensional action current maps. Overlaying epifluorescent images allowed us to identify a net current along the wavefront and perpendicular to gradients in the transmembrane potential. This is in contrast to a traditional uniform double-layer model where the net current flows along the gradient in the transmembrane potential. Our findings are supported by numerical simulations that treat cardiac tissue as a bidomain with unequal anisotropies in the intra- and extracellular spaces. Our measurements reveal the anisotropic bidomain nature of cardiac tissue during plane wave propagation. These bidomain effects play an important role in the generation of the whole-heart magnetocardiogram and cannot be ignored. PMID:15377521

  5. High Resolution Phase-Sensitive Magnetomotive Optical Coherence Microscopy for Tracking Magnetic Microbeads and Cellular Mechanics

    PubMed Central

    Crecea, Vasilica; Graf, Benedikt W.; Kim, Taewoo; Popescu, Gabriel; Boppart, Stephen A.

    2014-01-01

    We present a real-time multimodal near-infrared imaging technology that tracks externally induced axial motion of magnetic microbeads in single cells in culture. The integrated multimodal imaging technique consists of phase-sensitive magnetomotive optical coherence microscopy (MM-OCM) and multiphoton microscopy (MPM).MPMis utilized for the visualization of multifunctional fluorescent and magnetic microbeads, while MM-OCM detects, with nanometer-scale sensitivity, periodic displacements of the microbeads induced by the modulation of an external magnetic field. Magnetomotive signals are measured from mouse macrophages, human breast primary ductal carcinoma cells, and human breast epithelial cells in culture, and validated with full-field phase-sensitive microscopy. This methodology demonstrates the capability for imaging controlled cell dynamics and has the potential for measuring cell biomechanical properties, which are important in assessing the health and pathological state of cells. PMID:25400496

  6. High-resolution near-bottom vector magnetic anomalies over Raven Hydrothermal Field, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Tivey, Maurice A.; Johnson, H. Paul; Salmi, Marie S.; Hutnak, Michael

    2014-10-01

    High-resolution, near-bottom vector magnetic data were collected by remotely operated vehicle Jason over the Raven hydrothermal vent field (47°57.3'N 129°5.75'W) located north of Main Endeavour vent field on the Endeavour segment of the Juan de Fuca Ridge. The survey was part of a comprehensive heat flow study of the Raven site using innovative thermal blanket technology to map the heat flux and crustal fluid pathways around a solitary hydrothermal vent field. Raven hydrothermal activity is presently located along the western axial valley wall, while additional inactive hydrothermal deposits are found to the NW on the upper rift valley wall. Magnetic inversion results show discrete areas of reduced magnetization associated with both active and inactive hydrothermal vent deposits that also show high conductive heat flow. Higher spatial variability in the heat flow patterns compared to the magnetization is consistent with the heat flow reflecting the currently active but ephemeral thermal environment of fluid flow, while crustal magnetization is representative of the static time-averaged effect of hydrothermal alteration. A general NW to SE trend in reduced magnetization across the Raven area correlates closely with the distribution of hydrothermal deposits and heat flux patterns and suggests that the fluid circulation system at depth is likely controlled by local crustal structure and magma chamber geometry. Magnetic gradient tensor components computed from vector magnetic data improve the resolution of the magnetic anomaly source and indicate that the hydrothermally altered zone directly beneath the Raven site is approximately 15 × 106 m3 in volume.

  7. Concept for a high-resolution thermometer utilizing the temperature dependence of the magnetic penetration depth

    NASA Technical Reports Server (NTRS)

    Shirron, P. J.; Dipirro, M. J.

    1993-01-01

    A thermometer using the temperature dependence of the magnetic penetration depth in superconductors is described which has the potential for temperature resolution, when using a dc SQUID readout, on the order of 1 pK. One such device has been fabricated and characterized to demonstrate proof of concept. It consists of primary and secondary coils of NbTi wire wound on a copper toroidal core on which a thin layer of In (Tc = 3.4 K) has been deposited. The temperature dependence of the mutual inductance, M(T), or self-inductance, is used to detect changes in temperature. Measurements of M(T) have been made with an ac excitation of the primary for various frequencies and peak magnetic field strengths. Estimates of ultimate temperature resolution are given.

  8. Concept for a high-resolution thermometer utilizing the temperature dependence of the magnetic penetration depth

    NASA Astrophysics Data System (ADS)

    Shirron, P. J.; Dipirro, M. J.

    1993-03-01

    A thermometer using the temperature dependence of the magnetic penetration depth in superconductors is described which has the potential for temperature resolution, when using a dc SQUID readout, on the order of 1 pK. One such device has been fabricated and characterized to demonstrate proof of concept. It consists of primary and secondary coils of NbTi wire wound on a copper toroidal core on which a thin layer of In (Tc = 3.4 K) has been deposited. The temperature dependence of the mutual inductance, M(T), or self-inductance, is used to detect changes in temperature. Measurements of M(T) have been made with an ac excitation of the primary for various frequencies and peak magnetic field strengths. Estimates of ultimate temperature resolution are given.

  9. High Resolution Magnetic and Gravity Surveys to Constrain Maar Geometry and Eruption Mechanisms, Rattlesnake Crater, Arizona

    NASA Astrophysics Data System (ADS)

    Marshall, A. M.; Kruse, S. E.; Connor, C.; Connor, L.; Abdollahzadeh, M.; Harburger, A.; Richardson, J. A.; Courtland, L. M.; Farrell, A. K.; Kiflu, H. G.; Malservisi, R.; McNiff, C. M.; Njoroge, M.; Nushart, N.; Rookey, K.

    2013-12-01

    Located 25 kilometers east of Flagstaff, Arizona, Rattlesnake Crater is an oblong phreatomagmatic feature in the San Francisco Volcanic Field. The shallow crater is approximately 1.4 kilometers at its widest point, and surrounded by an uneven tuff ring which is overlapped by a scoria cone volcano on the southeastern side. Improved understanding of its formation and evolution requires geophysical study because there are very few outcrops, and no digging is permitted on site. Geologic features related to the crater are further obscured by deposits from the overlapping scoria cone, as well as tephra from eruptions at nearby Sunset Crater. We present the results of a detailed magnetic and gravity survey in and around Rattlesnake Crater. A substantial NW-SE trending elongate magnetic anomaly (1400 nT) and a smaller similarly trending anomaly are observed inside the crater, as well as a longer wavelength positive gravitational anomaly (+1.0-1.5 mGal) across the crater. The magnetic survey was completed on foot with a 50 meter line spacing inside the crater, and 100 meter line spacing across a portion of the surrounding area outside the crater. The gravity survey was done on two intersecting survey lines - one running west to east, and another roughly north to south, with recordings every 100 meters extending at least 1000 meters outside the crater in all four directions. 2D models of the magnetic and gravity data are presented illustrating the possible geometry of the diatreme, and the approximate size and shape of the major intrusive features. Eruption estimates based on the models are calculated, and the models are favorably compared to the size and depth estimates given in a recent publication (Valentine 2012) that used xenolith content to estimate the size and depth of the diatreme.

  10. High resolution neurography of the lumbosacral plexus on 3T magneteic resonance imaging.

    PubMed

    Cejas, C; Escobar, I; Serra, M; Barroso, F

    2015-01-01

    Magnetic resonance neurography is a technique that complements clinical and electrophysiological study of the peripheral nerves and brachial and lumbosacral plexuses. Numerous focal processes (inflammatory, traumatic, primary tumors, secondary tumors) and diffuse processes (diabetic polyneuropathy, chronic idiopathic demyelinating polyneuropathy due to amyloidosis or Charcot-Marie-Tooth disease) can involve the lumbosacral plexus. This article reviews the anatomy of the lumbosacral plexus, describes the technique for neurography of the plexus at our institution, and shows the diverse diseases that affect it. PMID:25447367

  11. New Developments at the XMaS Beamline For Magnetic and High Resolution Diffraction

    SciTech Connect

    Thompson, P.B.J.; Bouchenoire, L.; Brown, S.D.; Mannix, D.; Paul, D.F.; Lucas, C.; Kervin, J.; Cooper, M.J.; Arakawa, P.; Laughon, G.

    2004-05-12

    We report here on a number of developments that include enhancements of the sample environment on the XMaS beamline and the flux available at low energy. A 4 Tesla superconducting magnet has been designed to fit within the Euler cradle of a six circle Huber diffractometer, allowing scattering in both horizontal and vertical planes. The geometry of the magnet allows the application of longitudinal, transverse horizontal, and vertical fields. A further conventional magnet ({approx} 0.1 T) to minimize air absorption at low energies ({approx} 3KeV) has been designed for two circle applications, such as reflectivity. A novel in-vacuum slit screen has been developed, also minimizing absorption at low energies. New equipment for performing in-situ studies of surfaces in the electrochemical environment has been developed to allow control of the solution and sample temperature over the region of -5C to 80C. Preliminary experiments on the surface reconstructions of Au(111) in an electrolyte have been performed, whilst commissioning at the same time a MAR CCD detector for the beamline.

  12. CONNECTING THE SUN'S HIGH-RESOLUTION MAGNETIC CARPET TO THE TURBULENT HELIOSPHERE

    SciTech Connect

    Cranmer, Steven R.; Van Ballegooijen, Adriaan A.; Woolsey, Lauren N.

    2013-04-20

    The solar wind is connected to the Sun's atmosphere by flux tubes that are rooted in an ever-changing pattern of positive and negative magnetic polarities on the surface. Observations indicate that the magnetic field is filamentary and intermittent across a wide range of spatial scales. However, we do not know to what extent the complex flux-tube topology seen near the Sun survives as the wind expands into interplanetary space. In order to study the possible long-distance connections between the corona and the heliosphere, we developed new models of turbulence-driven solar wind acceleration along empirically constrained field lines. We used a potential field model of the quiet Sun to trace field lines into the ecliptic plane with unprecedented spatial resolution at their footpoints. For each flux tube, a one-dimensional model was created with an existing wave/turbulence code that solves equations of mass, momentum, and energy conservation from the photosphere to 4 AU. To take account of stream-stream interactions between flux tubes, we used those models as inner boundary conditions for a time-steady magnetohydrodynamic description of radial and longitudinal structure in the ecliptic. Corotating stream interactions smear out much of the smallest-scale variability, making it difficult to see how individual flux tubes on granular or supergranular scales can survive out to 1 AU. However, our models help clarify the level of ''background'' variability with which waves and turbulent eddies should be expected to interact. Also, the modeled fluctuations in magnetic field magnitude were seen to match measured power spectra quite well.

  13. Magnetic dynamics studied by high-resolution electron spectroscopy and time-resolved electron microscopy

    NASA Astrophysics Data System (ADS)

    Jayaraman, Rajeswari

    Future information technology requires an increased magnetically encoded data density and novel electromagnetic modes of data transfer. While to date magnetic properties are observed and characterized mostly statically, the need emerges to monitor and capture their fast dynamics. In this talk, I will focus on the spin dynamics i.e. spin wave excitations and the dynamics of a new topological distribution of spins termed ``skyrmions''. Wave packets of spin waves offer the unique capability to transport a quantum bit, the spin, without the transport of charge or mass. Here, large wave-vector spin waves are of particular interest as they admit spin localization within a few nanometers. By using our recently developed electron energy loss spectrometer, we could study such spin waves in ultrathin films with an unprecedented energy resolution of 4 meV. By virtue of the finite penetration depth of low energy electrons, spin waves localized at interfaces between a substrate and a thin capping layer can be been studied yielding information about the exchange coupling between atoms at the interface. The quantization of spin waves with wave vectors perpendicular to the film gives rise to standing modes to which EELS has likewise access. Such studies when carried out as function of the film thickness again yield information on the layer dependence of the exchange coupling. Magnetic skyrmions are promising candidates as information carriers in logic or storage devices. Currently, little is known about the influence of disorder, defects, or external stimuli on the spatial distribution and temporal evolution of the skyrmion lattice. In this talk, I will describe the dynamical role of disorder in a large and flat thin film of Cu2OSeO3, exhibiting a skyrmion phase in an insulating material. We image up to 70,000 skyrmions by means of cryo-Lorentz Transmission Electron Microscopy as a function of the applied magnetic field. In the skyrmion phase, dislocations are shown to cause the

  14. A scanning Hall probe microscope for high resolution magnetic imaging down to 300 mK

    SciTech Connect

    Khotkevych, V. V.; Bending, S. J.; Milosevic, M. V.

    2008-12-15

    We present the design, construction, and performance of a low-temperature scanning Hall probe microscope with submicron lateral resolution and a large scanning range. The detachable microscope head is mounted on the cold flange of a commercial {sup 3}He-refrigerator (Oxford Instruments, Heliox VT-50) and operates between room temperature and 300 mK. It is fitted with a three-axis slip-stick nanopositioner that enables precise in situ adjustment of the probe location within a 6x6x7 mm{sup 3} space. The local magnetic induction at the sample surface is mapped with an easily changeable microfabricated Hall probe [typically GsAs/AlGaAs or AlGaAs/InGaAs/GaAs Hall sensors with integrated scanning tunnel microscopy (STM) tunneling tips] and can achieve minimum detectable fields {>=}10 mG/Hz{sup 1/2}. The Hall probe is brought into very close proximity to the sample surface by sensing and controlling tunnel currents at the integrated STM tip. The instrument is capable of simultaneous tunneling and Hall signal acquisition in surface-tracking mode. We illustrate the potential of the system with images of superconducting vortices at the surface of a Nb thin film down to 372 mK, and also of labyrinth magnetic-domain patterns of an yttrium iron garnet film captured at room temperature.

  15. SOLAR MAGNETIC TRACKING. III. APPARENT UNIPOLAR FLUX EMERGENCE IN HIGH-RESOLUTION OBSERVATIONS

    SciTech Connect

    Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J.; Parnell, C. E.; Welsch, B. T.

    2010-09-10

    Understanding the behavior of weak magnetic fields near the detection limit of current instrumentation is important for determining the flux budget of the solar photosphere at small spatial scales. Using 0.''3-resolution magnetograms from the Solar Optical Telescope's Narrowband Filter Imager (NFI) on the Hinode spacecraft, we confirm that the previously reported apparent unipolar magnetic flux emergence seen in intermediate-resolution magnetograms is indeed the coalescence of previously existing flux. We demonstrate that similar but smaller events seen in NFI magnetograms are also likely to correspond to the coalescence of previously existing weak fields. The uncoalesced flux, detectable only in the ensemble average of hundreds of these events, accounts for 50% of the total flux within 3 Mm of the detected features. The spatial scale at which apparent unipolar emergence can be directly observed as coalescence remains unknown. The polarity of the coalescing flux is more balanced than would be expected given the imbalance of the data set, however without further study we cannot speculate whether this implies that the flux in the apparent unipolar emergence events is produced by a granulation-scale dynamo or is recycled from existing field.

  16. A scanning Hall probe microscope for high resolution magnetic imaging down to 300 mK

    NASA Astrophysics Data System (ADS)

    Khotkevych, V. V.; Milošević, M. V.; Bending, S. J.

    2008-12-01

    We present the design, construction, and performance of a low-temperature scanning Hall probe microscope with submicron lateral resolution and a large scanning range. The detachable microscope head is mounted on the cold flange of a commercial H3e-refrigerator (Oxford Instruments, Heliox VT-50) and operates between room temperature and 300 mK. It is fitted with a three-axis slip-stick nanopositioner that enables precise in situ adjustment of the probe location within a 6×6×7 mm3 space. The local magnetic induction at the sample surface is mapped with an easily changeable microfabricated Hall probe [typically GsAs/AlGaAs or AlGaAs/InGaAs/GaAs Hall sensors with integrated scanning tunnel microscopy (STM) tunneling tips] and can achieve minimum detectable fields ⩾10 mG/Hz1/2. The Hall probe is brought into very close proximity to the sample surface by sensing and controlling tunnel currents at the integrated STM tip. The instrument is capable of simultaneous tunneling and Hall signal acquisition in surface-tracking mode. We illustrate the potential of the system with images of superconducting vortices at the surface of a Nb thin film down to 372 mK, and also of labyrinth magnetic-domain patterns of an yttrium iron garnet film captured at room temperature.

  17. High-resolution low-field molecular magnetic resonance imaging of hyperpolarized liquids.

    PubMed

    Coffey, Aaron M; Kovtunov, Kirill V; Barskiy, Danila A; Koptyug, Igor V; Shchepin, Roman V; Waddell, Kevin W; He, Ping; Groome, Kirsten A; Best, Quinn A; Shi, Fan; Goodson, Boyd M; Chekmenev, Eduard Y

    2014-09-16

    We demonstrate the feasibility of microscale molecular imaging using hyperpolarized proton and carbon-13 MRI contrast media and low-field (47.5 mT) preclinical scale (38 mm i.d.) 2D magnetic resonance imaging (MRI). Hyperpolarized proton images with 94 × 94 μm(2) spatial resolution and hyperpolarized carbon-13 images with 250 × 250 μm(2) in-plane spatial resolution were recorded in 4-8 s (largely limited by the electronics response), surpassing the in-plane spatial resolution (i.e., pixel size) achievable with micro-positron emission tomography (PET). These hyperpolarized proton and (13)C images were recorded using large imaging matrices of up to 256 × 256 pixels and relatively large fields of view of up to 6.4 × 6.4 cm(2). (13)C images were recorded using hyperpolarized 1-(13)C-succinate-d2 (30 mM in water, %P(13C) = 25.8 ± 5.1% (when produced) and %P(13C) = 14.2 ± 0.7% (when imaged), T1 = 74 ± 3 s), and proton images were recorded using (1)H hyperpolarized pyridine (100 mM in methanol-d4, %P(H) = 0.1 ± 0.02% (when imaged), T1 = 11 ± 0.1 s). Both contrast agents were hyperpolarized using parahydrogen (>90% para-fraction) in an automated 5.75 mT parahydrogen induced polarization (PHIP) hyperpolarizer. A magnetized path was demonstrated for successful transportation of a (13)C hyperpolarized contrast agent (1-(13)C-succinate-d2, sensitive to fast depolarization when at the Earth's magnetic field) from the PHIP polarizer to the 47.5 mT low-field MRI. While future polarizing and low-field MRI hardware and imaging sequence developments can further improve the low-field detection sensitivity, the current results demonstrate that microscale molecular imaging in vivo is already feasible at low (<50 mT) fields and potentially at low (~1 mM) metabolite concentrations. PMID:25162371

  18. High-Resolution Low-Field Molecular Magnetic Resonance Imaging of Hyperpolarized Liquids

    PubMed Central

    2015-01-01

    We demonstrate the feasibility of microscale molecular imaging using hyperpolarized proton and carbon-13 MRI contrast media and low-field (47.5 mT) preclinical scale (38 mm i.d.) 2D magnetic resonance imaging (MRI). Hyperpolarized proton images with 94 × 94 μm2 spatial resolution and hyperpolarized carbon-13 images with 250 × 250 μm2 in-plane spatial resolution were recorded in 4–8 s (largely limited by the electronics response), surpassing the in-plane spatial resolution (i.e., pixel size) achievable with micro-positron emission tomography (PET). These hyperpolarized proton and 13C images were recorded using large imaging matrices of up to 256 × 256 pixels and relatively large fields of view of up to 6.4 × 6.4 cm2. 13C images were recorded using hyperpolarized 1-13C-succinate-d2 (30 mM in water, %P13C = 25.8 ± 5.1% (when produced) and %P13C = 14.2 ± 0.7% (when imaged), T1 = 74 ± 3 s), and proton images were recorded using 1H hyperpolarized pyridine (100 mM in methanol-d4, %PH = 0.1 ± 0.02% (when imaged), T1 = 11 ± 0.1 s). Both contrast agents were hyperpolarized using parahydrogen (>90% para-fraction) in an automated 5.75 mT parahydrogen induced polarization (PHIP) hyperpolarizer. A magnetized path was demonstrated for successful transportation of a 13C hyperpolarized contrast agent (1-13C-succinate-d2, sensitive to fast depolarization when at the Earth’s magnetic field) from the PHIP polarizer to the 47.5 mT low-field MRI. While future polarizing and low-field MRI hardware and imaging sequence developments can further improve the low-field detection sensitivity, the current results demonstrate that microscale molecular imaging in vivo is already feasible at low (<50 mT) fields and potentially at low (∼1 mM) metabolite concentrations. PMID:25162371

  19. Construction of hydrodynamic bead models from high-resolution X-ray crystallographic or nuclear magnetic resonance data.

    PubMed Central

    Byron, O

    1997-01-01

    Computer software such as HYDRO, based upon a comprehensive body of theoretical work, permits the hydrodynamic modeling of macromolecules in solution, which are represented to the computer interface as an assembly of spheres. The uniqueness of any satisfactory resultant model is optimized by incorporating into the modeling procedure the maximal possible number of criteria to which the bead model must conform. An algorithm (AtoB, for atoms to beads) that permits the direct construction of bead models from high resolution x-ray crystallographic or nuclear magnetic resonance data has now been formulated and tested. Models so generated then act as informed starting estimates for the subsequent iterative modeling procedure, thereby hastening the convergence to reasonable representations of solution conformation. Successful application of this algorithm to several proteins shows that predictions of hydrodynamic parameters, including those concerning solvation, can be confirmed. PMID:8994627

  20. Magnetic resonance imaging and high-resolution computed tomography in tumors of the lung and the mediastinum.

    PubMed

    Casamassima, F; Villari, N; Fargnoli, R; Di Lollo, S; Cellerini, A; Ruggiero, C

    1988-01-01

    Magnetic resonance (MR) imaging and high resolution computed tomography (CT) have been compared in 37 patients who had expansive processes of the lung and the mediastinum. MR imaging and CT scanning gave identical results in 32 patients; in 5 patients, CT scanning has proved more useful in evaluating the stag e of primary lung tumors. MR imaging often gives more information about the actual size of the tumor, and the involvement of close structures, although it does not modify staging of the tumor. MR imaging has the advantage to differentiate hilar adenopathy from blood vessel structures. Evaluation of T2 relaxing time (that we have performed in the same location of thin-needle biopsy aspiration), however, did not prove to be of diagnostic significance; this indicates that MR imaging at the moment is not suitable for tissue typification. PMID:3344352

  1. High-resolution (13)C nuclear magnetic resonance spectroscopy pattern recognition of fish oil capsules.

    PubMed

    Aursand, Marit; Standal, Inger B; Axelson, David E

    2007-01-10

    13C NMR (nuclear magnetic resonance) spectroscopy, in conjunction with multivariate analysis of commercial fish oil-related health food products, have been used to provide discrimination concerning the nature, composition, refinement, and/or adulteration or authentication of the products. Supervised (probabilistic neural networks, PNN) and unsupervised (principal component analysis, PCA; Kohonen neural networks; generative topographic mapping, GTM) pattern recognition techniques were used to visualize and classify samples. Simple PCA score plots demonstrated excellent, but not totally unambiguous, class distinctions, whereas Kohonen and GTM visualization provided better results. Quantitative class predictions with accuracies >95% were achieved with PNN analysis. Trout, salmon, and cod oils were completely and correctly classified. Samples reported to be salmon oils and cod liver oils did not cluster with true salmon and cod liver oil samples, indicating mislabeling or adulteration. PMID:17199311

  2. A novel high-resolution optical imaging modality: photo-magnetic imaging

    NASA Astrophysics Data System (ADS)

    Luk, Alex T.; Thayer, David; Lin, Yuting; Nouizi, Farouk; Gao, Hao; Gulsen, Gultekin

    2013-03-01

    We introduce an entirely new technique, termed Photo-Magnetic Imaging (PMI), which overcomes the limitation of pure optical imaging and provides optical absorption at MRI spatial resolution. PMI uses laser light to heat the medium under investigation and employs MR thermometry for the determination of spatially resolved optical absorption in the probed medium. A FEM-based PMI forward solver has been developed by modeling photon migration and heat diffusion in tissue to compare simulation results with measured MRI maps. We have successfully performed PMI using 2.5 cm diameter agar phantom with two low optical absorption contrast (x 4) inclusions under the ANSI limit. Currently, we are developing the PMI inverse solver and undertaking further phantom and in vivo experiments.

  3. Study of hydrogen in coals, polymers, oxides, and muscle water by nuclear magnetic resonance; extension of solid-state high-resolution techniques. [Hydrogen molybdenum bronze

    SciTech Connect

    Ryan, L.M.

    1981-10-01

    Nuclear magnetic resonance (NMR) spectroscopy has been an important analytical and physical research tool for several decades. One area of NMR which has undergone considerable development in recent years is high resolution NMR of solids. In particular, high resolution solid state /sup 13/C NMR spectra exhibiting features similar to those observed in liquids are currently achievable using sophisticated pulse techniques. The work described in this thesis develops analogous methods for high resolution /sup 1/H NMR of rigid solids. Applications include characterization of hydrogen aromaticities in fossil fuels, and studies of hydrogen in oxides and bound water in muscle.

  4. Cardiac dysfunction in the diabetic rat: quantitative evaluation using high resolution magnetic resonance imaging

    PubMed Central

    Loganathan, Rajprasad; Bilgen, Mehmet; Al-Hafez, Baraa; Alenezy, Mohammed D; Smirnova, Irina V

    2006-01-01

    Background Diabetes is a major risk factor for cardiovascular disease. In particular, type 1 diabetes compromises the cardiac function of individuals at a relatively early age due to the protracted course of abnormal glucose homeostasis. The functional abnormalities of diabetic myocardium have been attributed to the pathological changes of diabetic cardiomyopathy. Methods In this study, we used high field magnetic resonance imaging (MRI) to evaluate the left ventricular functional characteristics of streptozotocin treated diabetic Sprague-Dawley rats (8 weeks disease duration) in comparison with age/sex matched controls. Results Our analyses of EKG gated cardiac MRI scans of the left ventricle showed a 28% decrease in the end-diastolic volume and 10% increase in the end-systolic volume of diabetic hearts compared to controls. Mean stroke volume and ejection fraction in diabetic rats were decreased (48% and 28%, respectively) compared to controls. Further, dV/dt changes were suggestive of phase sensitive differences in left ventricular kinetics across the cardiac cycle between diabetic and control rats. Conclusion Thus, the MRI analyses of diabetic left ventricle suggest impairment of diastolic and systolic hemodynamics in this rat model of diabetic cardiomyopathy. Our studies also show that in vivo MRI could be used in the evaluation of cardiac dysfunction in this rat model of type 1 diabetes. PMID:16595006

  5. A moving hum filter to suppress rotor noise in high-resolution airborne magnetic data

    USGS Publications Warehouse

    Xia, J.; Doll, W.E.; Miller, R.D.; Gamey, T.J.; Emond, A.M.

    2005-01-01

    A unique filtering approach is developed to eliminate helicopter rotor noise. It is designed to suppress harmonic noise from a rotor that varies slightly in amplitude, phase, and frequency and that contaminates aero-magnetic data. The filter provides a powerful harmonic noise-suppression tool for data acquired with modern large-dynamic-range recording systems. This three-step approach - polynomial fitting, bandpass filtering, and rotor-noise synthesis - significantly reduces rotor noise without altering the spectra of signals of interest. Two steps before hum filtering - polynomial fitting and bandpass filtering - are critical to accurately model the weak rotor noise. During rotor-noise synthesis, amplitude, phase, and frequency are determined. Data are processed segment by segment so that there is no limit on the length of data. The segment length changes dynamically along a line based on modeling results. Modeling the rotor noise is stable and efficient. Real-world data examples demonstrate that this method can suppress rotor noise by more than 95% when implemented in an aeromagnetic data-processing flow. ?? 2005 Society of Exploration Geophysicists. All rights reserved.

  6. Monitoring gold nanoparticle distribution with high resolution using photo-magnetic imaging

    NASA Astrophysics Data System (ADS)

    Luk, Alex T.; Nouizi, Farouk; Marks, Michael; Kart, Turkay; Gulsen, Gultekin

    2016-03-01

    One major advantage of using gold nanoparticles is the possibility of tuning their absorption peak by modifying their surface plasma resonance. They are proven to be a promising multi-functional platform that can be used for many imaging and therapeutic applications. As a true multi-modality imaging technique, Photo-Magnetic Imaging (PMI) has a great potential to monitor the distribution of gold nanoparticles non-invasively with MR resolution. With a simple addon of a continuous wave laser to an MRI system, PMI uses the laser induced temperature increase, measured by MR Thermometry (MRT), to provide tissue optical absorption maps at MR resolution. PMI utilizes a Finite Element Method (FEM) based algorithm to solve the combined diffusion and bio-heat equations. This system of combined equations models the photon distribution in the tissue and heat generation due to the absorption of the light and consequent heat diffusion. The key characteristic of PMI is that its spatial resolution is preserved at any depth as long as the temperature change within the imaged medium is detectable by MRT. Agar phantoms containing gold nanoparticles are used to validate the ability of PMI in monitoring their distribution. To make PMI suitable for diagnostic purposes, the laser powers has been kept under the American National Standard Institute maximum skin exposure limits in this study.

  7. High-resolution transmission electron microscopy observations on textured rapidly quenched NdFeB permanent magnets

    NASA Astrophysics Data System (ADS)

    Li, Lin; Luzzi, D. E.; Graham, C. D., Jr.

    1991-11-01

    High-resolution transmission electron microscopy (HRTEM) has been used to examine the microstructures of NdFeB magnets made by rapid solidification. The samples were General Motors MQ-3 magnets, and also MQ-3 magnets that had been recompressed perpendicular to the original compression axis. A major finding is that the Nd-rich grain-boundary phase is not uniformly distributed on all grain boundaries of the Nd2Fe14B phase. Some boundaries are completely clean, and where the Nd-rich phase does appear, its thickness varies widely. The grain-boundary phase (whose structure has been variously identified) is partially ordered at room temperature after slow cooling. Ordered domains and antiphase boundaries have been observed in this phase by HRTEM. Using the Nd2Fe14B fringe spacing as calibration, the lattice parameter of the grain-boundary phase is found to be 5.58 Å. In the completely ordered state, this phase is neither bcc nor fcc; it is simple cubic with a lower-symmetry space group Pm3m.

  8. GLOBAL TWIST OF SUNSPOT MAGNETIC FIELDS OBTAINED FROM HIGH-RESOLUTION VECTOR MAGNETOGRAMS

    SciTech Connect

    Tiwari, Sanjiv Kumar; Venkatakrishnan, P.; Sankarasubramanian, K. E-mail: pvk@prl.res.in

    2009-09-10

    The presence of fine structures in sunspot vector magnetic fields has been confirmed from Hinode as well as other earlier observations. We studied 43 sunspots based on the data sets taken from ASP/DLSP, Hinode (SOT/SP), and SVM (USO). In this Letter, (1) we introduce the concept of signed shear angle (SSA) for sunspots and establish its importance for non-force-free fields. (2) We find that the sign of global {alpha} (force-free parameter) is well correlated with that of the global SSA and the photospheric chirality of sunspots. (3) Local {alpha} patches of opposite signs are present in the umbra of each sunspot. The amplitude of the spatial variation of local {alpha} in the umbra is typically of the order of the global {alpha} of the sunspot. (4) We find that the local {alpha} is distributed as alternately positive and negative filaments in the penumbra. The amplitude of azimuthal variation of the local {alpha} in the penumbra is approximately an order of magnitude larger than that in the umbra. The contributions of the local positive and negative currents and {alpha} in the penumbra cancel each other giving almost no contribution for their global values for the whole sunspot. (5) Arc-like structures (partial rings) with a sign opposite to that of the dominant sign of {alpha} of the umbral region are seen at the umbral-penumbral boundaries of some sunspots. (6) Most of the sunspots studied belong to the minimum epoch of the 23rd solar cycle and do not follow the so-called hemispheric helicity rule.

  9. High resolution magnetic field mapping of complex magmatic rock suites and associated tectonic structures in the Southern Andes

    NASA Astrophysics Data System (ADS)

    Díaz-Michelena, Marina; Kilian, Rolf

    2013-04-01

    Magmatic and metamorphic rocks of the southernmost Andes (50 to 55°S) document a complex magmatic and tectonic history of an active continental margin during the past >140 Ma [1]. However, the regional distribution of the multiple magmatic intrusive rock suites and younger systems of basaltic dykes as well as the tectonic control of associated hydrothermal systems are widely unexplored. Since the rocks are often bare exposed they represent an ideal test site for a magnetic field investigation with significant implication for future aeromagnetic mapping. Thus we performed a high resolution near-surface grid of measurements with a scalar and vector magnetometer at selected sites which include different intrusive rocks, tectonic lineaments and hydrothermal alteration with an associated mineralization. The magnetic signature corresponding to the Natural Remanent Magnetisation (NRM) was measured on Mesozoic and Cenozoic gabbroid to granitic plutons with large range chemical and mineralogical variations [1], on distinct basaltic dykes, as well as on mylonites, gneisses and hornfels rocks. The whole-rock chemistry of the selected rock types was determined by Atomic Absorption Spectroscopy and X-ray Fluorescence. The analysed and mapped rocks include the SiO2 range from 45 to 76 wt.%, FeO (tot) contents from 2 to 18 wt.% and Ti2O contents from 0.2 to 2.5 wt.%. The mineral assemblages were analysed by polarization microscopy, with an electron microprobe and X-ray diffraction. In the plutonic rocks the whole rock chemistry often is related to the amount of magnetite and NRM intensities [2]. However, measured magnetic intensities let us estimate the degree of chloritization and associated demagnetisation by magnetite alteration and transformation to maghemite and/or iron-hydroxides. For Miocene basaltic dyke systems of decimetre to several meters extension within granitic plutons, a high resolution magnetic mapping has been also performed. We expected a relationship of

  10. High-Resolution Ground-Based Magnetic Survey of a Buried Volcano: Anomaly B, Amargosa Desert, NV

    NASA Astrophysics Data System (ADS)

    McIlrath, J.; George, O.; Farrell, A. K.; Gallant, E.; Tavarez, S.; Downs, C. M.; Njoroge, M. W.; Wilson, J. A.; Connor, C.; Connor, L.; Kruse, S.

    2015-12-01

    Aeromagnetic surveys over the Amargosa Desert, Nevada, have revealed the presence of several magnetic anomalies that have been interpreted to be caused by buried volcanoes; many of these anomalies have been confirmed by drilling. We present data collected from a high-resolution, ground-based magnetic survey over Anomaly B, the largest of these anomalies, that reveal details about a buried crater and its associated lava flow, not previously observed in the aeromagnetic surveys. These details provide insight into the nature of the eruption and the volume of this buried volcano. Results from non-linear inversion demarcate a crater with a diameter of approximately 700 m and a base approximately 150 m below the ground surface. Coupled with well log data, the inversion results suggest a total volume for the Anomaly B crater area and associated lava flows of approximately 1.0 ± 0.4 km3, based on an estimated lava flow field area of 24 km2 and a lava thickness of 42 ± 15 m.

  11. Beamline 9.3.2 - a high-resolution, bend-magnet beamline with circular polarization capability

    SciTech Connect

    Moler, E.J.; Hussain, Z.; Howells, M.R.

    1997-04-01

    Beamline 9.3.2 is a high resolution, SGM beamline on an ALS bending magnet with access to photon energies from 30-1500 eV. Features include circular polarization capability, a rotating chamber platform that allows switching between experiments without breaking vacuum, an active feedback system that keeps the beam centered on the entrance slit of the monochromator, and a bendable refocusing mirror. The beamline optics consist of horizontally and vertically focussing mirrors, a Spherical Grating Monochromator (SGM) with movable entrance and exit slits, and a bendable refocussing mirror. In addition, a movable aperature has been installed just upstream of the vertically focussing mirror which can select the x-rays above or below the plane of the synchrotron storage ring, allowing the user to select circularly or linearly polarized light. Circularly polarized x-rays are used to study the magnetic properties of materials. Beamline 9.3.2 can supply left and right circularly polarized x-rays by a computer controlled aperture which may be placed above or below the plane of the synchrotron storage ring. The degree of linear and circular polarization has been measured and calibrated.

  12. [Connection of magnetic antisense probe with SK-Br-3 oncocyte mRNA nucleotide detected by high resolution atomic force microscope].

    PubMed

    Tan, Shude; Ouyang, Yu; Li, Xinyou; Wen, Ming; Li, Shaolin

    2011-06-01

    The present paper is aimed to detect superparamagnetic iron oxide labeled c-erbB2 oncogene antisense oligonucleotide probe (magnetic antisense probe) connected with SK-Br-3 oncocyte mRNA nucleotide by high resolution atomic force microscope (AFM). We transfected SK-Br-3 oncocyte with magnetic antisense probe, then observed the cells by AFM with high resolution and detected protein expression and magnetic resonance imagine (MRI). The high resolution AFM clearly showed the connection of the oligonucleotide remote end of magnetic antisense probe with the mRNA nucleotide of oncocyte. The expression of e-erbB2 protein in SK-Br3 cells were highly inhibited by using magnetic antisense probe. We then obtained the lowest signal to noise ratio (SNR) of SK-Br-3 oncocyte transfected with magnetic antisense probe by MRI (P<0.05). These experiments demonstrated that the high resolution AFM could be used to show the binding of magnetic antisense probe and SK-Br-3 mRNA of tumor cell nuclear. PMID:21774198

  13. Very-high-resolution seismic and magnetic investigations of a chemical munition dumpsite in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Missiaen, Tine; Feller, Pascal

    2008-09-01

    Very-high-resolution (VHR) seismic and magnetic investigations were carried out over a chemical munition dumpsite in the Bornholm Basin, south-western Baltic Sea. The main goal of the investigations was to image the shallow internal structure of the dumpsite and to map the lateral and vertical distribution of the dumped war material. The shallow geology was imaged in great detail on the seismic data. Seven seismic-stratigraphic units were identified, related to different stages in the Holocene and late-glacial history. A large number of diapir-like features were observed that most likely represent fluid expulsion phenomena. Four shipwrecks were identified in the dumpsite area. The wrecks have partly sunk into the soft upper sediments, their height above the sea floor reaching no more than 2 m. Seismic and magnetic data indicate the presence of a large number of buried objects. In most cases there is a good correlation between the seismic and magnetic data sets. The objects are generally buried no deeper than 1 to 2 m. Their size varies between 1.5 and 5 m, occasionally up to 10 m. Shallow pits in the sea bed are likely due to the impact of dumping. The data confirm the wide variety of dumped war material ranging from bombs and shells to encasements and containers. The distribution of the buried objects seems rather heterogeneous, with locally high object concentrations surrounded by areas of lower object density. The results of this case study demonstrate the benefit of complementary, concurrent geophysical investigations for munition dumpsite research. Finally this will yield a better assessment of the current status of the dumpsite and the possible ecological risks related to the dumped war material.

  14. High-resolution AUV-based near bottom magnetic surveys at Palinuro volcanic complex (Southern Tyrrhenian Sea)

    NASA Astrophysics Data System (ADS)

    Cocchi, L.; Plunkett, S.; Augustin, N.; Petersen, S.

    2013-12-01

    In this paper we present the preliminary results of new near bottom magnetic datasets collected during the recent POS442 cruise using the autonomous underwater vehicle (AUV) Abyss. The Southern Tyrrhenian basin is characterized by deep seafloor interspersed with huge volcanic seamounts (e.g Vavilov and Marsili and those associated to the Aeolian volcanic arc), which were formed during eastward roll back of the Apennine subduction system. These submarine edifices often are affected by significant hydrothermal activity and associated mineral deposits such as those observed at Marsili, Palinuro and Panarea. The western part of the Palinuro volcanic complex is characterized by a half rim of a caldera-like structure and hosts hydrothermal barite-pyrite deposits. Until recently, the full extent of the hydrothermal system remained poorly defined, as exploration has been limited to a few specific sites. In November 2012, a set of high resolution near seafloor geophysical surveys were carried out using GEOMAR's AUV Abyss to attempt to better define the hydrothermal mineralization at Palinuro. Five AUV dives were performed, mapping a total area of 3.7 km2 over the western part of Palinuro. Geomar's Abyss AUV (a Remus6000 class vehicle) was equipped with an Applied Physics Systems flux gate magnetometer, writing to a stand alone data logger, powered by the AUV's main batteries. The 5 dives were performed within the same area but with different primary geophysical sensors (multibeam, sidescan sonar, subbottom profiler), survey altitudes above seafloor (100m, 40m) and line spacing (150m, 100m, 20m). Magnetic data was collect on all five dives. At the beginning of each dive, the AUV performed a set of calibration manoeuvres, involving a 360 degree heading variation, a set of three upwards/downwards pitches, and three port and starboard yaws. This magnetic data reveals the magnetization features of the seafloor in unprecedented detail, highlighting a complex pattern mostly due to

  15. Investigation of high-resolution functional magnetic resonance imaging by means of surface and array radiofrequency coils at 7 T.

    PubMed

    van der Zwaag, Wietske; Marques, José P; Hergt, Martin; Gruetter, Rolf

    2009-10-01

    In this investigation, high-resolution, 1x1x1-mm(3) functional magnetic resonance imaging (fMRI) at 7 T is performed using a multichannel array head coil and a surface coil approach. Scan geometry was optimized for each coil separately to exploit the strengths of both coils. Acquisitions with the surface coil focused on partial brain coverage, while whole-brain coverage fMRI experiments were performed with the array head coil. BOLD sensitivity in the occipital lobe was found to be higher with the surface coil than with the head array, suggesting that restriction of signal detection to the area of interest may be beneficial for localized activation studies. Performing independent component analysis (ICA) decomposition of the fMRI data, we consistently detected BOLD signal changes and resting state networks. In the surface coil data, a small negative BOLD response could be detected in these resting state network areas. Also in the data acquired with the surface coil, two distinct components of the positive BOLD signal were consistently observed. These two components were tentatively assigned to tissue and venous signal changes. PMID:19261421

  16. High-resolution numerical simulation of Left Ventricular Hemodynamics Guided by in-vivo Cardiac Magnetic Resonance Data

    NASA Astrophysics Data System (ADS)

    Le, Trung; Sotiropoulos, Fotis; Mirabella, Lucia; Chaffins, Brandon; Santhanakrishnan, Arvind; Oshinski, John; Yoganathan, Ajit; University of Minnesota Collaboration; Georgia Institute of Technology Collaboration

    2012-11-01

    We study the fluid dynamics within a patient-specific left ventricle (LV) during diastole using both numerical simulations and in-vivo data. The kinematics of the LV is reconstructed from high-resolution Magnetic Resonance Imaging (MRI) data acquired on a healthy volunteer, using image segmentation and a surface registration process. The flow velocity is acquired using phase-contrast MRI at the mitral orifice and at an additional parallel plane inside the ventricle. Numerical simulations are carried out using the CURVIB method (Ge et al., JCP, 2007) with the MRI reconstructed LV wall motion imposed as boundary condition. The numerical simulations show the highly dynamic environment of the flow field. The mitral vortex ring is formed during early diastolic filling and breaks down into small scale structures. The simulated hemodynamics are compared with phase-contrast MRI measurements and previous simulations in which the LV wall motion was obtained from a lumped parameter model (Le and Sotiropoulos, Eur. J. Mechanics B - Fluids, 2012). We acknowlege NIH Grant RO1-HL-07262 and the Minnesota Supercomputing Institute support.

  17. The Thermal and Magnetic Structure of Umbral Dots from the Inversion of High-Resolution Full Stokes Observations

    NASA Astrophysics Data System (ADS)

    Socas-Navarro, H.; Martínez Pillet, V.; Sobotka, M.; Vázquez, M.

    2004-10-01

    This paper presents the analysis of high-resolution Stokes observations of eight different umbral dots in a sunspot. The spectra were recorded with the La Palma Stokes Polarimeter, attached to the Swedish Vacuum Solar Telescope. The observed line profiles have been inverted to yield the height stratifications of temperature, magnetic field, and line-of-sight velocity, as well as their respective Wilson depressions. We report on systematic differences in the properties of umbral dots with respect to the nearby umbra, including small upflows (~100 m s-1), higher temperatures (~1 kK), and weaker fields (~500 G) with more horizontal orientations (~10°). The field weakening is strongly correlated with the Wilson depression, suggesting that it may be due to an opacity effect (as one is looking at higher layers). The inclination excess, on the other hand, is real and cannot be ascribed to formation height issues. The results obtained from our semiempirical modeling are discussed within the context of the currently existing scenarios for the subsurface structure of sunspots. The observational signatures revealed by our analysis fit well within both the ``spaghetti'' and the monolithic models.

  18. Evaluation of Cancer Metabolomics Using ex vivo High Resolution Magic Angle Spinning (HRMAS) Magnetic Resonance Spectroscopy (MRS)

    PubMed Central

    Fuss, Taylor L.; Cheng, Leo L.

    2016-01-01

    According to World Health Organization (WHO) estimates, cancer is responsible for more deaths than all coronary heart disease or stroke worldwide, serving as a major public health threat around the world. High resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy (MRS) has demonstrated its usefulness in the identification of cancer metabolic markers with the potential to improve diagnosis and prognosis for the oncology clinic, due partially to its ability to preserve tissue architecture for subsequent histological and molecular pathology analysis. Capable of the quantification of individual metabolites, ratios of metabolites, and entire metabolomic profiles, HRMAS MRS is one of the major techniques now used in cancer metabolomic research. This article reviews and discusses literature reports of HRMAS MRS studies of cancer metabolomics published between 2010 and 2015 according to anatomical origins, including brain, breast, prostate, lung, gastrointestinal, and neuroendocrine cancers. These studies focused on improving diagnosis and understanding patient prognostication, monitoring treatment effects, as well as correlating with the use of in vivo MRS in cancer clinics. PMID:27011205

  19. High resolution 23Na-nuclear magnetic resonance study of stroke-prone spontaneously hypertensive rat erythrocytes.

    PubMed

    Kwan, C Y; Seo, Y; Ito, H; Murakami, M; Watari, H

    1987-06-01

    The intracellular Na+ content of washed erythrocytes from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto normotensive rats (WKY) was measured by a high resolution 23Na-nuclear magnetic resonance (NMR) technique using a non-permeant aqueous shift reagent, dysprosium triethylenetetramine hexaacetic acid, Dy(TTHA)3-. The initial intracellular Na+ of freshly isolated and washed erythrocytes was very low (approximately 5 mmol/l) and increased progressively with prolonged incubation in isotonic salt solution at 37 degrees C. There was no significant difference in the erythrocyte Na+ concentration between SHRSP and WKY over the entire period of measurement, nor was any difference detected in their osmotic fragility or total cellular volume, although the osmotic fragility decreased with incubation time. The high energy phosphate metabolites were also studied in the same erythrocytes by 31P-NMR. The level of intracellular ATP decreased with incubation at 37 degrees C but showed no difference between the SHRSP and WKY samples. Inclusion of 1 mmol/l ouabain in the incubation medium substantially retarded the breakdown of intracellular ATP and resulted in a concomitant increase in intracellular Na+. However, neither the ouabain-sensitive nor the ouabain-insensitive component of Na+ influx altered in SHRSP erythrocytes compared with WKY erythrocytes in paired experiments. Our results do not support the hypothesis that altered Na+ transport, resulting in an increase in erythrocyte Na+ concentration, is associated with spontaneous hypertension. PMID:3611783

  20. Calcium silicate hydrates investigated by solid-state high resolution {sup 1}H and {sup 29}Si nuclear magnetic resonance

    SciTech Connect

    Meducin, Fabienne . E-mail: meducin@cnrs-orleans.fr; Bresson, Bruno; Lequeux, Nicolas; Noirfontaine, Marie-Noelle de; Zanni, Helene

    2007-05-15

    This work focuses on phases formed during cement hydration under high pressure and temperature: portlandite Ca(OH){sub 2} (CH); hillebrandite Ca{sub 2}(SiO{sub 3})(OH){sub 2} ({beta}-dicalcium silicate hydrate); calcium silicate hydrate (C-S-H); jaffeite Ca{sub 6}(Si{sub 2}O{sub 7})(OH){sub 6} (tricalcium silicate hydrate); {alpha}-C{sub 2}SH Ca{sub 2}(SiO{sub 3})(OH){sub 2} ({alpha}-dicalcium silicate hydrate); xonotlite Ca{sub 6}(Si{sub 6}O{sub 17})(OH){sub 2} and kilchoanite Ca{sub 6}(SiO{sub 4})(Si{sub 3}O{sub 10}). Portlandite and hillebrandite were synthesized and characterised by high resolution solid-state {sup 1}H and {sup 29}Si Nuclear Magnetic Resonance. In addition, information from the literature concerning the last five phases was gathered. In certain cases, a schematic 3D-structure could be determined. These data allow identification of the other phases present in a mixture. Their morphology was also observed by Scanning Electron Microscopy.

  1. High-Resolution, Single-Molecule Measurements of Biomolecular Motion

    PubMed Central

    Greenleaf, William J.; Woodside, Michael T.; Block, Steven M.

    2007-01-01

    Many biologically important macromolecules undergo motions that are essential to their function. Biophysical techniques can now resolve the motions of single molecules down to the nanometer scale or even below, providing new insights into the mechanisms that drive molecular movements. This review outlines the principal approaches that have been used for high-resolution measurements of single-molecule motion, including centroid tracking, fluorescence resonance energy transfer, magnetic tweezers, atomic force microscopy, and optical traps. For each technique, the principles of operation are outlined, the capabilities and typical applications are examined, and various practical issues for implementation are considered. Extensions to these methods are also discussed, with an eye toward future application to outstanding biological problems. PMID:17328679

  2. Combined use of high-resolution α-glucosidase inhibition profiling and high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy for investigation of antidiabetic principles in crude plant extracts.

    PubMed

    Kongstad, Kenneth T; Özdemir, Ceylan; Barzak, Asmah; Wubshet, Sileshi G; Staerk, Dan

    2015-03-01

    Type 2 diabetes is a metabolic disorder affecting millions of people worldwide, and new drug leads or functional foods containing selective α-glucosidase inhibitors are needed. Crude extract of 24 plants were assessed for α-glucosidase inhibitory activity. Methanol extracts of Cinnamomum zeylanicum bark, Rheum rhabarbarum peel, and Rheum palmatum root and ethyl acetate extracts of C. zeylanicum bark, Allium ascalonicum peel, and R. palmatum root showed IC50 values below 20 μg/mL. Subsequently, high-resolution α-glucosidase profiling was used in combination with high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy for identification of metabolites responsible for the α-glucosidase inhibitory activity. Quercetin (1) and its dimer (2), trimer (3), and tetramer (4) were identified as main α-glucosidase inhibitors in A. ascalonicum peel, whereas (E)-piceatannol 3'-O-β-D-glucopyranoside (5), (E)-rhapontigenin 3'-O-β-D-glucopyranoside (6), (E)-piceatannol (8), and emodin (12) were identified as main α-glucosidase inhibitors in R. palmatum root. PMID:25652946

  3. Intratumoral Agreement of High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopic Profiles in the Metabolic Characterization of Breast Cancer

    PubMed Central

    Park, Vivian Youngjean; Yoon, Dahye; Koo, Ja Seung; Kim, Eun-Kyung; Kim, Seung Il; Choi, Ji Soo; Park, Seho; Park, Hyung Seok; Kim, Suhkmann; Kim, Min Jung

    2016-01-01

    Abstract High-resolution magic angle spinning (HR-MAS) magnetic resonance (MR) spectroscopy data may serve as a biomarker for breast cancer, with only a small volume of tissue sample required for assessment. However, previous studies utilized only a single tissue sample from each patient. The aim of this study was to investigate whether intratumoral location and biospecimen type affected the metabolic characterization of breast cancer assessed by HR-MAS MR spectroscopy This prospective study was approved by the institutional review board and informed consent was obtained. Preoperative core-needle biopsies (CNBs), central, and peripheral surgical tumor specimens were prospectively collected under ultrasound (US) guidance in 31 patients with invasive breast cancer. Specimens were assessed with HR-MAS MR spectroscopy. The reliability of metabolite concentrations was evaluated and multivariate analysis was performed according to intratumoral location and biospecimen type. There was a moderate or higher agreement between the relative concentrations of 94.3% (33 of 35) of metabolites in the center and periphery, 80.0% (28 of 35) of metabolites in the CNB and central surgical specimens, and 82.9% (29 of 35) of metabolites between all 3 specimen types. However, there was no significant agreement between the concentrations of phosphocholine (PC) and phosphoethanolamine (PE) in the center and periphery. The concentrations of several metabolites (adipate, arginine, fumarate, glutamate, PC, and PE) had no significant agreement between the CNB and central surgical specimens. In conclusion, most HR-MAS MR spectroscopic data do not differ based on intratumoral location or biospecimen type. However, some metabolites may be affected by specimen-related variables, and caution is recommended in decision-making based solely on metabolite concentrations, particularly PC and PE. Further validation through future studies is needed for the clinical implementation of these biomarkers based

  4. Live-cell high resolution magic angle spinning magnetic resonance spectroscopy for in vivo analysis of Pseudomonas aeruginosa metabolomics.

    PubMed

    Righi, Valeria; Constantinou, Caterina; Kesarwani, Meenu; Rahme, Laurence G; Tzika, Aria A

    2013-09-01

    Pseudomonas aeruginosa (PA) is a pathogenic gram-negative bacterium that is widespread in nature, inhabiting soil, water, plants and animals. PA is a prevalent cause of deleterious human infections, particularly in patients whose host defense mechanisms have been compromised. Metabolomics is an important tool used to study host-pathogen interactions and to identify novel therapeutic targets and corresponding compounds. The aim of the present study was to report the metabolic profile of live PA bacteria using in vivo high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance spectroscopy (NMR), in combination with 1- and 2-dimensional HRMAS NMR. This methodology provides a new and powerful technique to rapidly interrogate the metabolome of intact bacterial cells and has several advantages over traditional techniques that identify metabolome components from disrupted cells. Furthermore, application of multidimensional HRMAS NMR, in combination with the novel technique total through-Bond correlation Spectroscopy (TOBSY), is a promising approach that may be used to obtain in vivo metabolomics information from intact live bacterial cells and can mediate such analyses in a short period of time. Moreover, HRMAS (1)H NMR enables the investigation of the associations between metabolites and cell processes. In the present study, we detected and quantified several informative metabolic molecules in live PA cells, including N-acetyl, betaine, citrulline, alanine and glycine, which are important in peptidoglycan synthesis. The results provided a complete metabolic profile of PA for future studies of PA clinical isolates and mutants. In addition, this in vivo NMR biomedical approach might have clinical utility and should prove useful in gene function validation, the study of pathogenetic mechanisms, the classification of microbial strains into functional/clinical groups, the testing of anti-bacterial agents and the determination of metabolic profiles of bacterial

  5. Magnetic Tweezers-based 3D Microchannel Electroporation for High-Throughput Gene Transfection in Living Cells

    PubMed Central

    Liao, Wei-Ching; Chiang, Chi-Ling; Gallego-Perez, Daniel; Yang, Zhaogang; Lu, Wu; Byrd, John C.; Muthusamy, Natarajan; Lee, L. James.; Sooryakumar, Ratnasingham

    2015-01-01

    We report a novel, high throughput magnetic-tweezers based 3D microchannel electroporation system capable of transfecting 40,000 cells/cm2 on a single-chip for gene therapy, regenerative medicine and intracellular detection of target mRNA for screening cellular heterogeneity. A single cell or an ordered array of individual cells are remotely guided by programmable magnetic fields to poration sites with high (> 90%) cell alignment efficiency to enable various transfection reagents to be delivered simultaneously into the cells. The present technique, in contrast to the conventional vacuum based approach, is significantly gentler on the cellular membrane yielding > 90% cell viability and, moreover, allows transfected cells to be transported for further analysis. Illustrating the versatility of the system, the GATA2 molecular beacon was delivered into leukemia cells to detect the regulation level of the GATA2 gene that is associated with the initiation of leukemia. The uniform delivery and a sharp contrast of fluorescence intensity between GATA2 positive and negative cells demonstrate key aspects of the platform for gene transfer, screening and detection of targeted intracellular markers in living cells. PMID:25469659

  6. NAP1-Assisted Nucleosome Assembly on DNA Measured in Real Time by Single-Molecule Magnetic Tweezers

    PubMed Central

    Vlijm, Rifka; Smitshuijzen, Jeremy S. J.; Lusser, Alexandra; Dekker, Cees

    2012-01-01

    While many proteins are involved in the assembly and (re)positioning of nucleosomes, the dynamics of protein-assisted nucleosome formation are not well understood. We study NAP1 (nucleosome assembly protein 1) assisted nucleosome formation at the single-molecule level using magnetic tweezers. This method allows to apply a well-defined stretching force and supercoiling density to a single DNA molecule, and to study in real time the change in linking number, stiffness and length of the DNA during nucleosome formation. We observe a decrease in end-to-end length when NAP1 and core histones (CH) are added to the dsDNA. We characterize the formation of complete nucleosomes by measuring the change in linking number of DNA, which is induced by the NAP1-assisted nucleosome assembly, and which does not occur for non-nucleosomal bound histones H3 and H4. By rotating the magnets, the supercoils formed upon nucleosome assembly are removed and the number of assembled nucleosomes can be counted. We find that the compaction of DNA at low force is about 56 nm per assembled nucleosome. The number of compaction steps and associated change in linking number indicate that NAP1-assisted nucleosome assembly is a two-step process. PMID:23050009

  7. Optical tweezers study life under tension

    NASA Astrophysics Data System (ADS)

    Fazal, Furqan M.; Block, Steven M.

    2011-06-01

    Optical tweezers have become one of the primary weapons in the arsenal of biophysicists, and have revolutionized the new field of single-molecule biophysics. Today's techniques allow high-resolution experiments on biological macromolecules that were mere pipe dreams only a decade ago.

  8. Cryogenic phased-array for high resolution magnetic resonance imaging (MRI); assessment of clinical and research applications

    NASA Astrophysics Data System (ADS)

    Ip, Flora S.

    Magnetic Resonance (MR) imaging is one of the most powerful tools in diagnostic medicine for soft tissue imaging. Image acquisition techniques and hardware receivers are very important in achieving high contrast and high resolution MR images. An aim of this dissertation is to design single and multi-element room and cryogenic temperature arrays and make assessments of their signal-to-noise ratio (SNR) and SNR gain. In this dissertation, four sets of MR receiver coils are built. They are the receiver-only cryo-coils that are not commercially available. A tuning and matching circuit is attached to each coil. The tuning and matching circuits are simple; however, each device component has to operate at a high magnetic field and cryogenic temperature environment. Remote DC bias of the varactor controls the tuning and matching outside the scanner room. Active detuning of the resonator is done by two p-i-n junction (PIN) diodes. Cooling of the receiver is done by a customized liquid nitrogen cryostat. The first application is to build a 3-Tesla 2x1 horseshoe counter-rotating current (CRC) cryogenic array to image the tibia in a human body. With significant increase in SNR, the surface coil should deliver high contrast and resolution images that can show the trabecular bone and bone marrow structure. This structural image will be used to model the mechanical strength of the bone as well as bone density and chance of fracture. The planar CRC is a unique design of this surface array. The second application is to modify the coil design to 7-Tesla to study the growth of infant rhesus monkey eyes. Fast scan MR images of the infant monkey heads are taken for monitoring shapes of their eyeballs. The monkeys are induced with shortsightedness by eye lenses, and they are scanned periodically to get images of their eyeballs. The field-of-view (FOV) of these images is about five centimeters and the area of interest is two centimeters deep from the surface. Because of these reasons

  9. High-Resolution Mapping of Lunar Crustal Magnetic Fields: Correlations with Albedo Markings of the Reiner Gamma Class

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Yingst, A.; Mitchell, D. L.; Lin, R. P.; Acuna, M.; Binder, A.

    1999-01-01

    During the last eight months of the Lunar Prospector mission (December 1999-July 1999), the spacecraft was placed in a relatively low-altitude (15-30-km perapsis), near-polar orbit that allowed high-resolution mapping of crustal magnetic fields. We report here initial studies of the correlation of locally strong magnetic anomalies with unusual, swirl-like albedo markings of the Reiner Gamma class. Based on this correlation, which is known from earlier studies of Apollo subsatellite magnetometer data, it has been proposed that the swirls represent regions whose higher albedos have been preserved via deflection of the solar-wind ion bombardment by strong crustal fields. This model in turn depends on the hypothesis that solar-wind implanted H is at least one component of the process that optically matures exposed silicate surfaces in the inner solar system . Specifically, it is hypothesized that implanted H acts as an effective reducing agent to enhance the rate of production of nanophase metallic Fe particles from preexisting silicates during micrometeoroid impacts. According to the model, the curvilinear shapes of these albedo markings are caused, at least in part, by the geometry of ion deflections in a magnetic field. The improved resolution and coverage of the Prospector data allow more detailed mapping of the fields, especially on the lunar farside. This permits a more quantitative test of whether all albedo markings of this class are associated with strong local magnetic fields.Only if the latter condition is met can the solar-wind deflection hypothesis he valid. The basic procedure for mapping crustal magnetic fields using Lunar Prospector magnetometer data follows that developed for analysis of Apollo subsatellite magnetometer data. The specific mapping steps are (1) selection of mission time intervals suitable for mapping crustal fields; these are limited essentially either to times when the Moon is in a lobe of the geomagnetic tail or to times when the Moon

  10. Observing dynamics of chromatin fibers in Xenopus egg extracts by single DNA manipulation using a transverse magnetic tweezer setup

    NASA Astrophysics Data System (ADS)

    Yan, Jie; Skoko, Dunja; Marko, John; Maresca, Tom; Heald, Rebecca

    2005-03-01

    We have studied assembly of chromatin on single DNAs using Xenopus egg extracts and a specially designed magnetic tweezer setup which generates controlled force in the focal plane of the objective, allowing us to visualize and measure DNA extension under a wide range of constant tensions. We found, in the absence of ATP, interphase extracts assembled nucleosomes against DNA tensions of up to 3.5 piconewtons (pN). We observed force-induced disassembly and opening-closing fluctuations indicating our experiments were in mechano-chemical equilibrium. We found that the ATP-depleted reaction can do mechanical work of 27 kcal/mol per nucleosome, providing a measurement of the free energy difference between core histone octamers on and off DNA. Addition of ATP leads to highly dynamic behavior: time courses show processive runs of assembly and disassembly of not observed in the -ATP case, with forces of 2 pN leading to nearly complete fiber disassembly. Our study shows that ATP hydrolysis plays a major role in nucleosome rearrangement and removal, and suggests that chromatin in vivo may be subject to continual assembly and disassembly.

  11. Mechanical unfolding of human telomere G-quadruplex DNA probed by integrated fluorescence and magnetic tweezers spectroscopy.

    PubMed

    Long, Xi; Parks, Joseph W; Bagshaw, Clive R; Stone, Michael D

    2013-02-01

    Single-molecule techniques facilitate analysis of mechanical transitions within nucleic acids and proteins. Here, we describe an integrated fluorescence and magnetic tweezers instrument that permits detection of nanometer-scale DNA structural rearrangements together with the application of a wide range of stretching forces to individual DNA molecules. We have analyzed the force-dependent equilibrium and rate constants for telomere DNA G-quadruplex (GQ) folding and unfolding, and have determined the location of the transition state barrier along the well-defined DNA-stretching reaction coordinate. Our results reveal the mechanical unfolding pathway of the telomere DNA GQ is characterized by a short distance (<1 nm) to the transition state for the unfolding reaction. This mechanical unfolding response reflects a critical contribution of long-range interactions to the global stability of the GQ fold, and suggests that telomere-associated proteins need only disrupt a few base pairs to destabilize GQ structures. Comparison of the GQ unfolded state with a single-stranded polyT DNA revealed the unfolded GQ exhibits a compacted non-native conformation reminiscent of the protein molten globule. We expect the capacity to interrogate macromolecular structural transitions with high spatial resolution under conditions of low forces will have broad application in analyses of nucleic acid and protein folding. PMID:23303789

  12. High-Resolution Mapping of Lunar Crustal Magnetic Fields: Correlations with Albedo Markings of the Reiner Gamma Class

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Yingst, A.; Mitchell, D. L.; Lin, R. P.; Acuna, M.; Binder, A.

    1999-01-01

    During the last eight months of the Lunar Prospector mission (December 1999-July 1999), the spacecraft was placed in a relatively low-altitude (15-30-km perapsis), near-polar orbit that allowed high-resolution mapping of crustal magnetic fields. We report here initial studies of the correlation of locally strong magnetic anomalies with unusual, swirl-like albedo markings of the Reiner Gamma class. Based on this correlation, which is known from earlier studies of Apollo subsatellite magnetometer data, it has been proposed that the swirls represent regions whose higher albedos have been preserved via deflection of the solar-wind ion bombardment by strong crustal fields. This model in turn depends on the hypothesis that solar-wind implanted H is at least one component of the process that optically matures exposed silicate surfaces in the inner solar system . Specifically, it is hypothesized that implanted H acts as an effective reducing agent to enhance the rate of production of nanophase metallic Fe particles from preexisting silicates during micrometeoroid impacts. According to the model, the curvilinear shapes of these albedo markings are caused, at least in part, by the geometry of ion deflections in a magnetic field. The improved resolution and coverage of the Prospector data allow more detailed mapping of the fields, especially on the lunar farside. This permits a more quantitative test of whether all albedo markings of this class are associated with strong local magnetic fields.Only if the latter condition is met can the solar-wind deflection hypothesis he valid. The basic procedure for mapping crustal magnetic fields using Lunar Prospector magnetometer data follows that developed for analysis of Apollo subsatellite magnetometer data. The specific mapping steps are (1) selection of mission time intervals suitable for mapping crustal fields; these are limited essentially either to times when the Moon is in a lobe of the geomagnetic tail or to times when the Moon

  13. Detection of tannins in modern and fossil barks and in plant residues by high-resolution solid-state 13C nuclear magnetic resonance

    USGS Publications Warehouse

    Wilson, M.A.; Hatcher, P.G.

    1988-01-01

    Bark samples isolated from brown coal deposits in Victoria, Australia, and buried wood from Rhizophora mangle have been studies by high-resolution solid-state nuclear magnetic resonance (NMR) techniques. Dipolar dephasing 13C NMR appears to be a useful method of detecting the presence of tannins in geochemical samples including barks, buried woods, peats and leaf litter. It is shown that tannins are selectively preserved in bark during coalification to the brown coal stage. ?? 1988.

  14. A high-resolution field-emission-gun, scanning electron microscope investigation of anisotropic hydrogen decrepitation in Nd-Fe-B-based sintered magnets

    SciTech Connect

    Soderznik, Marko; McGuiness, Paul; Zuzek-Rozman, Kristina; Kobe, Spomenka; Skulj, Irena; Yan Gaolin

    2010-05-15

    In this investigation commercial magnets based on (Nd,Dy){sub 14}(Fe,Co){sub 79}B{sub 7} were prepared by a conventional powder-metallurgy route with a degree of alignment equal to {approx}90% and then exposed to hydrogen at a pressure of 1 bar. The magnets, in the form of cylinders, were observed to decrepitate exclusively from the ends. High-resolution electron microscopy was able to identify the presence of crack formation within the Nd{sub 2}Fe{sub 14}B grains, with the cracks running parallel to the c axis of these grains. Based on the concentration profile for hydrogen in a rare-earth transition-metal material, it is clear that the presence of hydrogen-induced cracks running perpendicular to the ends of the magnet provides for a much more rapidly progressing hydrogen front in this direction than from the sides of the magnet. This results in the magnet exhibiting a macroscopic tendency to decrepitate from the poles of the magnet toward the center. This combination of microstructural modification via particle alignment as part of the sintering process and direct observation via high-resolution electron microscopy has led to a satisfying explanation for the anisotropic hydrogen-decrepitation effect.

  15. High-resolution magnetic signature of active hydrothermal systems in the back-arc spreading region of the southern Mariana Trough

    NASA Astrophysics Data System (ADS)

    Fujii, Masakazu; Okino, Kyoko; Honsho, Chie; Dyment, Jerome; Szitkar, Florent; Mochizuki, Nobutatsu; Asada, Miho

    2015-05-01

    High-resolution vector magnetic measurements were performed on five hydrothermal vent fields of the back-arc spreading region of the southern Mariana Trough using Shinkai 6500, a deep-sea manned submersible. A new 3-D forward scheme was applied that exploits the surrounding bathymetry and varying altitudes of the submersible to estimate absolute crustal magnetization. The results revealed that magnetic-anomaly-derived absolute magnetizations show a reasonable correlation with natural remanent magnetizations of rock samples collected from the seafloor of the same region. The distribution of magnetic-anomaly-derived absolute magnetization suggests that all five andesite-hosted hydrothermal fields are associated with a lack of magnetization, as is generally observed at basalt-hosted hydrothermal sites. Furthermore, both the Pika and Urashima sites were found to have their own distinct low-magnetization zones, which could not be distinguished in magnetic anomaly data collected at higher altitudes by autonomous underwater vehicle due to their limited extension. The spatial extent of the resulting low magnetization is approximately 10 times wider at off-axis sites than at on-axis sites, possibly reflecting larger accumulations of nonmagnetic sulfides, stockwork zones, and/or alteration zones at the off-axis sites.

  16. Experimental Fusion of Contrast Enhanced High-Field Magnetic Resonance Imaging and High-Resolution Micro-Computed Tomography in Imaging the Mouse Inner Ear

    PubMed Central

    Counter, S. Allen; Damberg, Peter; Aski, Sahar Nikkhou; Nagy, Kálmán; Berglin, Cecilia Engmér; Laurell, Göran

    2015-01-01

    Objective: Imaging cochlear, vestibular, and 8th cranial nerve abnormalities remains a challenge. In this study, the membranous and osseous labyrinths of the wild type mouse inner ear were examined using volumetric data from ultra high-field magnetic resonance imaging (MRI) with gadolinium contrast at 9.4 Tesla and high-resolution micro-computed tomography (µCT) to visualize the scalae and vestibular apparatus, and to establish imaging protocols and parameters for comparative analysis of the normal and mutant mouse inner ear. Methods: For in vivo MRI acquisition, animals were placed in a Milleped coil situated in the isocenter of a horizontal 9.4 T Varian magnet. For µCT examination, cone beam scans were performed ex vivo following MRI using the µCT component of a nanoScan PET/CT in vivo scanner. Results: The fusion of Gd enhanced high field MRI and high-resolution µCT scans revealed the dynamic membranous labyrinth of the perilymphatic fluid filled scala tympani and scala vestibule of the cochlea, and semicircular canals of the vestibular apparatus, within the µCT visualized contours of the contiguous osseous labyrinth. The ex vivo µCT segmentation revealed the surface contours and structural morphology of each cochlea turn and the semicircular canals in 3 planes. Conclusions: The fusion of ultra high-field MRI and high-resolution µCT imaging techniques were complementary, and provided high-resolution dynamic and static visualization of the complex morphological features of the normal mouse inner ear structures, which may offer a valuable approach for the investigation of cochlear and vestibular abnormalities that are associated with birth defects related to genetic inner ear disorders in humans. PMID:26401173

  17. Magnetic domain wall tweezers: a new tool for mechanobiology studies on individual target cells.

    PubMed

    Monticelli, M; Conca, D V; Albisetti, E; Torti, A; Sharma, P P; Kidiyoor, G; Barozzi, S; Parazzoli, D; Ciarletta, P; Lupi, M; Petti, D; Bertacco, R

    2016-08-01

    In vitro tests are of fundamental importance for investigating cell mechanisms in response to mechanical stimuli or the impact of the genotype on cell mechanical properties. In particular, the application of controlled forces to activate specific bio-pathways and investigate their effects, mimicking the role of the cellular environment, is becoming a prominent approach in the emerging field of mechanobiology. Here, we present an on-chip device based on magnetic domain wall manipulators, which allows the application of finely controlled and localized forces on target living cells. In particular, we demonstrate the application of a magnetic force in the order of hundreds of pN on the membrane of HeLa cells cultured on-chip, via manipulation of 1 μm superparamagnetic beads. Such a mechanical stimulus produces a sizable local indentation of the cellular membrane of about 2 μm. Upon evaluation of the beads' position within the magnetic field originated by the domain wall, the force applied during the experiments is accurately quantified via micromagnetic simulations. The obtained value is in good agreement with that calculated by the application of an elastic model to the cellular membrane. PMID:27364187

  18. Magnetic field induced enlargement of the regime of critical fluctuations in the classical superconductor V3Si from high-resolution specific heat experiments.

    PubMed

    Zheng, Y; Liu, Y; Toyota, N; Lortz, R

    2015-02-25

    We present high-resolution specific heat data from a high-purity single crystal of the classical superconductor V(3)Si, which reveal tiny lambda-shape anomalies at the superconducting transition superimposed onto the BCS specific heat jump in magnetic fields of 2 T and higher. The appearance of these anomalies is accompanied by a magnetic-field-induced broadening of the superconducting transition. We demonstrate, using scaling relations predicted by the fluctuation models of the 3d-XY and the 3d-lowest-Landau-level (3d-LLL) universality class that the effect of critical fluctuations becomes experimentally observable due to of a magnetic field-induced enlargement of the regime of critical fluctuations. The scaling indicates that a reduction of the effective dimensionality due to the confinement of quasiparticles into low Landau levels is responsible for this effect. PMID:25640214

  19. High-Resolution Geophysical 3D Imaging for Archaeology by Magnetic and EM data: The Case of the Iron Age Settlement of Torre Galli, Southern Italy

    NASA Astrophysics Data System (ADS)

    Cella, Federico; Fedi, Maurizio

    2015-11-01

    Magnetic and electromagnetic surveying are effective techniques frequently used in archaeology because the susceptibility and the electric resistivity contrast between the cover soil and several buried finds often lead to detectable anomalies. Significant advances were recently achieved by 3D imaging methods of potential field data that provide an estimate of the magnetization distribution within the subsurface. They provide a high-resolution image of the source distribution, thanks to the differentiation of the field and to the stability of the process. These techniques are fast and quite effective in the case of a compact, isolated, and depth-limited source, i.e., just the kind of source generally occurring in archaeological investigations. We illustrate the high-resolution imaging process for a geophysical study carried out at Torre Galli ( Vibo Valentia, Calabria, Italy), one of the most significant sites of the early Iron Age in Italy. Multi-scale derivative analysis of magnetic data revealed the trends of anomalies shaped and aligned with a regular geometry. This allowed us to make an outline of the buried structures, and then to characterize them in terms of size, shape, and depth by means of the imaging technique. Targeted excavations were therefore addressed to the locations selected by our analysis, revealing structures showing exactly the predicted features and confirming the archaeological hypothesis concerning the settlement organization partitioned in terms of functional differentiation: an intermediate area occupied mostly by defensive structures placed between the village, westward, and the necropolis, eastward.

  20. High-resolution magnetics reveal the deep structure of a volcanic-arc-related basalt-hosted hydrothermal site (Palinuro, Tyrrhenian Sea)

    NASA Astrophysics Data System (ADS)

    Szitkar, Florent; Petersen, Sven; Caratori Tontini, Fabio; Cocchi, Luca

    2015-06-01

    High-resolution magnetic surveys have been acquired over the partially sedimented Palinuro massive sulfide deposits in the Aeolian volcanic arc, Tyrrhenian Sea. Surveys flown close to the seafloor using an autonomous underwater vehicle (AUV) show that the volcanic-arc-related basalt-hosted hydrothermal site is associated with zones of lower magnetization. This observation reflects the alteration of basalt affected by hydrothermal circulation and/or the progressive accumulation of a nonmagnetic deposit made of hydrothermal and volcaniclastic material and/or a thermal demagnetization of titanomagnetite due to the upwelling of hot fluids. To discriminate among these inferences, estimate the shape of the nonmagnetic deposit and the characteristics of the underlying altered area—the stockwork—we use high-resolution vector magnetic data acquired by the AUV Abyss (GEOMAR) above a crater-shaped depression hosting a weakly active hydrothermal site. Our study unveils a relatively small nonmagnetic deposit accumulated at the bottom of the depression and locked between the surrounding volcanic cones. Thermal demagnetization is unlikely but the stockwork extends beyond the limits of the nonmagnetic deposit, forming lobe-shaped zones believed to be a consequence of older volcanic episodes having contributed in generating the cones.

  1. High resolution NMR study of T{sub 1} magnetic relaxation dispersion. IV. Proton relaxation in amino acids and Met-enkephalin pentapeptide

    SciTech Connect

    Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L.; Vieth, Hans-Martin

    2014-10-21

    Nuclear Magnetic Relaxation Dispersion (NMRD) of protons was studied in the pentapeptide Met-enkephalin and the amino acids, which constitute it. Experiments were run by using high-resolution Nuclear Magnetic Resonance (NMR) in combination with fast field-cycling, thus enabling measuring NMRD curves for all individual protons. As in earlier works, Papers I–III, pronounced effects of intramolecular scalar spin-spin interactions, J-couplings, on spin relaxation were found. Notably, at low fields J-couplings tend to equalize the apparent relaxation rates within networks of coupled protons. In Met-enkephalin, in contrast to the free amino acids, there is a sharp increase in the proton T{sub 1}-relaxation times at high fields due to the changes in the regime of molecular motion. The experimental data are in good agreement with theory. From modelling the relaxation experiments we were able to determine motional correlation times of different residues in Met-enkephalin with atomic resolution. This allows us to draw conclusions about preferential conformation of the pentapeptide in solution, which is also in agreement with data from two-dimensional NMR experiments (rotating frame Overhauser effect spectroscopy). Altogether, our study demonstrates that high-resolution NMR studies of magnetic field-dependent relaxation allow one to probe molecular mobility in biomolecules with atomic resolution.

  2. High-resolution {sup 13}C nuclear magnetic resonance evidence of phase transition of Rb,Cs-intercalated single-walled nanotubes

    SciTech Connect

    Bouhrara, M.; Saih, Y.; Waagberg, T.; Goze-Bac, C.; Abou-Hamad, E.

    2011-09-01

    We present 13 C high-resolution magic-angle-turning (MAT) and magic angle spinning nuclear magnetic resonance data of Cs and Rb intercalated single walled carbon nanotubes. We find two distinct phases at different intercalation levels. A simple charge transfer is applicable at low intercalation level. The new phase at high intercalation level is accompanied by a hybridization of alkali (s) orbitals with the carbon (sp2) orbitals of the single walled nanotubes, which indicate bundle surface sites is the most probable alkali site.

  3. Measurement of local viscoelasticity and forces in living cells by magnetic tweezers.

    PubMed

    Bausch, A R; Möller, W; Sackmann, E

    1999-01-01

    We measured the viscoelastic properties of the cytoplasm of J774 macrophages with a recently developed microrheometer. Ferromagnetic beads (1.3 microm in diameter) were used to determine the local viscoelastic moduli. Step-force pulses were applied to the magnetic beads and the displacement was observed by single particle tracking. By analyzing the creep response curves in terms of a triphasic mechanical equivalent circuit, we measured the shear elastic modulus, the effective viscosities, and the strain relaxation time. The values of the shear modulus vary by more than an order of magnitude within the cell population (range, 20-735 Pa; average, 343 Pa) and by a factor of 2 within single cells. The effective viscosity of the cytoplasm exhibits a relatively sharp distribution about an average of eta = 210 Pa s (+/- 143 Pa s). We measured the displacement field generated by the local forces by observing the induced motion of nonmagnetic beads. Even at distances of the order of 1 microm, no induced motion was seen, suggesting that the cytoplasm is composed of clusters of densely packed and cross-linked filaments separated by soft regions. In another series of experiments we analyzed the magnetophoretic motion of the ferromagnetic beads at a constant magnetic force. Measuring the bead velocity parallel and perpendicular to the applied force showed that local active forces on the beads varied from 50 to 900 pN. PMID:9876170

  4. Advanced field shimming technology to reduce the influence of a screening current in a REBCO coil for a high-resolution NMR magnet

    NASA Astrophysics Data System (ADS)

    Iguchi, S.; Piao, R.; Hamada, M.; Matsumoto, S.; Suematsu, H.; Takao, T.; Saito, A. T.; Li, J.; Nakagome, H.; Jin, X.; Takahashi, M.; Maeda, H.; Yanagisawa, Y.

    2016-04-01

    This paper describes a field shimming technology to obtain a spatially homogeneous magnetic field required for a high-resolution nuclear magnetic resonance (NMR) magnet under the influence of a screening current in a (RE)Ba2Cu3O7-x (REBCO) coil. Use of REBCO inner coils is one solution to realize a super-high field (>23.5 T, 1 GHz) NMR magnet. However, a REBCO coil generates a large amount of field error harmonics due to the inhomogeneous coil winding introduced by a thin tape conductor. In addition, the performance of a field correction coil and outer superconducting (SC) shim coils are significantly reduced due to the shielding effect of the screening current in the REBCO coil. Therefore, conventional shimming technology using SC shim coils and room temperature shim coils cannot adequately compensate those field error harmonics and high-resolution NMR measurements are not possible. In the present paper, an advanced field shimming technology including an inner SC shim coil and a novel type of ferromagnetic shim were installed in a 400 MHz low-temperature SC/REBCO NMR magnet. The inner SC shim coil and the ferromagnetic shim compensated for the reduction in the performances of the field correction coil and the SC shim coils, respectively. The field error harmonics were greatly compensated with the technology and a high NMR resolution <0.01 ppm was obtained. The results from the present work suggest an optimal shimming procedure for a super-high field NMR magnet with high-temperature superconductors inner coils, i.e. the best mix of shims.

  5. A new 3D parallel high resolution electromagnetic nonlinear inversion based on new global magnetic integral and local differential decomposition (GILD)

    SciTech Connect

    Xie, G.; Li, J.

    1997-05-01

    A new 3D electromagnetic modeling and nonlinear inversion algorithm is presented based on global integral and local differential equations decomposition (GILD). The GILD parallel nonlinear inversion algorithm consists of five parts: (1) the domain is decomposed into subdomain SI and subdomain SII; (2) a new global magnetic integral equation in SI and the local magnetic differential equations IN SII will be used together to obtain the magnetic field in the modeling step; (3) the new global magnetic integral Jacobian equation in SI and the local magnetic differential Jacobian equations in SII will be used together to update the electric conductivity and permittivity from the magnetic field data in the inversion step; (4) the subdomain SII can naturally and uniformly be decomposed into 2{sup n} smaller sub-cubic-domains; the sparse matrix in each sub-cubic-domain can be eliminated separately, in parallel; (5) a new parallel multiple hierarchy substructure algorithm will be used to solve the smaller full matrices in SI, in parallel. The applications of the new 3D parallel GILD EM modeling and nonlinear inversion algorithm and software are: (1) to create high resolution controlled-source electric conductivity and permittivity imaging for interpreting electromagnetic field data acquired from cross hole, surface to borehole, surface to surface, single hole, and multiple holes; (2) to create the magnetotelluric high resolution imaging from the surface impedance and field data. The new GILD parallel nonlinear inversion will be a 3D/2.5D powerful imaging tool for the oil geophysical exploration and environmental remediation and monitoring.

  6. Oxygen Nanodistributions in Cobalt-Iron Electrodeposited Thin Films: Some Effects on Magnetic Properties High Resolution Analytical Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Elhalawaty, Shereen

    Soft magnetic alloys play a significant role for magnetic recording applications and highly sensitivity magnetic field sensors. In order to sustain the magnetic areal density growth, development of new synthesis techniques and materials is necessary. In this work, the effect of oxygen incorporation during electrodeposition of CoFe alloys on magnetic properties, magnetoresistance and structural properties has been studied. Understanding the magnetic properties often required knowledge of oxygen distribution and structural properties of the grown films. Transmission electron microscopy (TEM) was a powerful tool in this study to correlate the oxygen-distribution nanostructure to the magnetic properties of deposited films. Off-axis electron holography in TEM was used to measure magnetic domain wall width in the deposited films. Elemental depth profiles of Fe, Co, O were investigated by secondary ion mass spectroscopy (SIMS). Magnetic properties have been determined by superconducting quantum interference device (SQUID) measurements. Oxygen content in the CoFe deposited films was controlled by electrolyte composition. Films were deposited on Si 100 substrates and on other substrates such as Cu and Al. However, a good film quality was achieved on Si substrate. Electron energy loss and x-ray spectroscopies showed that the low oxygen films contained intragranular Fe2+ oxide (FeO) particles and that the high oxygen films contained intergranular Fe 3+ (Fe2O3) along grain boundaries. The films with oxide present at the grain boundary had significantly increased coercivity, magnetoresistance and reduced saturation magnetization relative to the lower oxygen content films with intragranular oxide. The differences in magnetic properties between low oxygen and high oxygen concentration films were attributed to stronger mobile domain wall interactions with the grain boundary oxide layers. The very high magnetoresistance values were achieved for magnetic devices with nanocontact

  7. The Relationship Between Solar Coronal X-Ray Brightness and Active Region Magnetic Fields: A Study Using High-Resolution Hinode Observations

    NASA Astrophysics Data System (ADS)

    Hazra, Soumitra; Nandy, Dibyendu; Ravindra, B.

    2015-03-01

    By using high-resolution observations of nearly co-temporal and co-spatial Solar Optical Telescope spectropolarimeter and X-Ray Telescope coronal X-ray data onboard Hinode, we revisit the problematic relationship between global magnetic quantities and coronal X-ray brightness. Co-aligned vector magnetogram and X-ray data were used for this study. The total X-ray brightness over active regions is well correlated with integrated magnetic quantities such as the total unsigned magnetic flux, the total unsigned vertical current, and the area-integrated square of the vertical and horizontal magnetic fields. On accounting for the inter-dependence of the magnetic quantities, we inferred that the total magnetic flux is the primary determinant of the observed integrated X-ray brightness. Our observations indicate that a stronger coronal X-ray flux is not related to a higher non-potentiality of active-region magnetic fields. The data even suggest a slightly negative correlation between X-ray brightness and a proxy of active-region non-potentiality. Although there are small numerical differences in the established correlations, the main conclusions are qualitatively consistent over two different X-ray filters, the Al-poly and Ti-poly filters, which confirms the strength of our conclusions and validate and extend earlier studies that used low-resolution data. We discuss the implications of our results and the constraints they set on theories of solar coronal heating.

  8. Quantification of magnetic nanoparticles with broadband-frequency magnetic susceptibility measurements: High-resolution climatic records from an upper loess-paleosol succession at Luochuan, Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Kodama, K.; An, Z.; Chang, H.; Qiang, X.

    2013-12-01

    magnetic nanoparticles in soils and sediments. In addition, the loess and weak paleosols in the Chinese Loess Plateau, as well as the paleosols, have high potential as high-resolution climatic archives.

  9. The Potential of High Resolution Magnetic Resonance Microscopy in the Pathologic Analysis of Resected Breast and Lymph Tissue.

    PubMed

    Dashevsky, Brittany Z; D'Alfonso, Timothy; Sutton, Elizabeth J; Giambrone, Ashley; Aronowitz, Eric; Morris, Elizabeth A; Juluru, Krishna; Ballon, Douglas J

    2015-01-01

    Pathologic evaluation of breast specimens requires a fixation and staining procedure of at least 12 hours duration, delaying diagnosis and post-operative planning. Here we introduce an MRI technique with a custom-designed radiofrequency resonator for imaging breast and lymph tissue with sufficient spatial resolution and speed to guide pathologic interpretation and offer value in clinical decision making. In this study, we demonstrate the ability to image breast and lymphatic tissue using 7.0 Tesla MRI, achieving a spatial resolution of 59 × 59 × 94 μm(3) with a signal-to-noise ratio of 15-20, in an imaging time of 56 to 70 minutes. These are the first MR images to reveal characteristic pathologic features of both benign and malignant breast and lymph tissue, some of which were discernible by blinded pathologists who had no prior training in high resolution MRI interpretation. PMID:26639673

  10. The Potential of High Resolution Magnetic Resonance Microscopy in the Pathologic Analysis of Resected Breast and Lymph Tissue

    PubMed Central

    Dashevsky, Brittany Z.; D'Alfonso, Timothy; Sutton, Elizabeth J.; Giambrone, Ashley; Aronowitz, Eric; Morris, Elizabeth A.; Juluru, Krishna; Ballon, Douglas J.

    2015-01-01

    Pathologic evaluation of breast specimens requires a fixation and staining procedure of at least 12 hours duration, delaying diagnosis and post-operative planning. Here we introduce an MRI technique with a custom-designed radiofrequency resonator for imaging breast and lymph tissue with sufficient spatial resolution and speed to guide pathologic interpretation and offer value in clinical decision making. In this study, we demonstrate the ability to image breast and lymphatic tissue using 7.0 Tesla MRI, achieving a spatial resolution of 59 × 59 × 94 μm3 with a signal-to-noise ratio of 15–20, in an imaging time of 56 to 70 minutes. These are the first MR images to reveal characteristic pathologic features of both benign and malignant breast and lymph tissue, some of which were discernible by blinded pathologists who had no prior training in high resolution MRI interpretation. PMID:26639673

  11. Echo-planar magnetic resonance imaging (EPI) with high-resolution matrix in intra-axial brain tumors.

    PubMed

    Brüning, R; Seelos, K; Yousry, T; Scheidler, J; Exner, H; Porn, U; Reiser, M; Rosen, B R

    1999-01-01

    The aim of this study was to assess the potential of high-speed interleaved echo-planar imaging (EPI) to achieve diagnostic image quality comparable to T2-weighted imaging in patients with brain tumors. Seventeen patients with intra-axial, supratentorial tumors (10 untreated gliomas, 7 radiated gliomas) were investigated on a 1. 5-T scanner. The conventional scan (SE, TR/TE = 2200/80 ms, 18 slices) was acquired in 8 min, 4 s, and EPI (TR/TE = 3000/80 ms, 18 slices) was completed in 25 s. The films were compared in a blinded trail by three radiologists. On the general impression and anatomic display, both sequences were rated to be of similar quality. Artifacts were slightly more pronounced at the skull base and around surgical clips using EPI. Tumor delineation was nearly equivalent using EPI, compared with the T2-weighted sequence. Echo-planar imaging reached diagnostic quality in all patients. Interleaved high-resolution EPI yielded sufficient quality to depict intra-axial, supratentorial brain tumors. Since EPI can be obtained in a small fraction of the time needed for conventional spin echo, in addition to other indications it could be considered to study patients unable to cooperate. PMID:10460380

  12. Magnetic investigations along selected high-resolution seismic traverses in the central block of Yucca Mountain, Nevada

    SciTech Connect

    Ponce, D.A.; Sikora, R.F.; Roberts, C.W.; Morin, R.L.; Halvorson, P.F.

    1995-12-31

    Ground magnetic data collected along several traverses across the central block of Yucca Mountain in southwest Nevada are interpreted. These data were collected as part of an effort to evaluate faulting in the vicinity of a potential nuclear waste repository at Yucca Mountain. Magnetic data and models along traverses across the central block of Yucca Mountain reveal anomalies associated with known faults and indicate a number of possible concealed faults beneath the eastern flank of Yucca Mountain. The central part of the eastern flank of Yucca Mountain is characterized by numerous small-amplitude anomalies that probably reflect small-scale faulting. Magnetic modeling of the terrain along the eastern flank of Yucca Mountain indicates that terrain induced magnetic anomalies of about 100 to 150 nT are present along some profiles where steep terrain exists above the magnetometer.

  13. Slow Magic Angle Sample Spinning: A Non- or Minimally Invasive Method for High- Resolution 1H Nuclear Magnetic Resonance (NMR) Metabolic Profiling

    SciTech Connect

    Hu, Jian Z.

    2011-05-01

    High resolution 1H magic angle spinning nuclear magnetic resonance (NMR), using a sample spinning rate of several kHz or more (i.e., high resolution-magic angle spinning (hr-MAS)), is a well established method for metabolic profiling in intact tissues without the need for sample extraction. The only shortcoming with hr-MAS is that it is invasive and is thus unusable for non-destructive detections. Recently, a method called slow-MAS, using the concept of two dimensional NMR spectroscopy, has emerged as an alternative method for non- or minimal invasive metabolomics in intact tissues, including live animals, due to the slow or ultra-slow-sample spinning used. Although slow-MAS is a powerful method, its applications are hindered by experimental challenges. Correctly designing the experiment and choosing the appropriate slow-MAS method both require a fundamental understanding of the operation principles, in particular the details of line narrowing due to the presence of molecular diffusion. However, these fundamental principles have not yet been fully disclosed in previous publications. The goal of this chapter is to provide an in depth evaluation of the principles associated with slow-MAS techniques by emphasizing the challenges associated with a phantom sample consisting of glass beads and H2O, where an unusually large magnetic susceptibility field gradient is obtained.

  14. Computer-assisted superimposition of magnetic resonance and high-resolution technetium-99m-HMPAO and thallium-201 SPECT images of the brain

    SciTech Connect

    Holman, B.L.; Zimmerman, R.E.; Johnson, K.A.; Carvalho, P.A.; Schwartz, R.B.; Loeffler, J.S.; Alexander, E.; Pelizzari, C.A.; Chen, G.T. )

    1991-08-01

    A method for registering three-dimensional CT, MR, and PET data sets that require no special patient immobilization or other precise positioning measures was adapted to high-resolution SPECT and MRI and was applied in 14 subjects (five normal volunteers, four patients with dementia (Alzheimer's disease), two patients with recurrent glioblastoma, and three patients with focal lesions (stroke, arachnoid cyst and head trauma)). T2-weighted axial magnetic resonance images and transaxial 99mTc-HMPAO and 201Tl images acquired with an annular gamma camera were merged using an objective registration (translation, rotation and rescaling) program. In the normal subjects and patients with dementia and focal lesions, focal areas of high uptake corresponded to gray matter structures. Focal lesions observed on MRI corresponded to perfusion defects on SPECT. In the patients who had undergone surgical resection of glioblastoma followed by interstitial brachytherapy, increased 201Tl corresponding to recurrent tumor could be localized from the superimposed images. The method was evaluated by measuring the residuals in all subjects and translational errors due to superimposition of deep structures in the 12 subjects with normal thalamic anatomy and 99mTc-HMPAO uptake. This method for superimposing magnetic resonance and high-resolution SPECT images of the brain is a useful technique for correlating regional function with brain anatomy.

  15. Ultra-wide bore 900 MHz high-resolution NMR at the National High Magnetic Field Laboratory

    NASA Astrophysics Data System (ADS)

    Fu, R.; Brey, W. W.; Shetty, K.; Gor'kov, P.; Saha, S.; Long, J. R.; Grant, S. C.; Chekmenev, E. Y.; Hu, J.; Gan, Z.; Sharma, M.; Zhang, F.; Logan, T. M.; Brüschweller, R.; Edison, A.; Blue, A.; Dixon, I. R.; Markiewicz, W. D.; Cross, T. A.

    2005-11-01

    Access to an ultra-wide bore (105 mm) 21.1 T magnet makes possible numerous advances in NMR spectroscopy and MR imaging, as well as novel applications. This magnet was developed, designed, manufactured and tested at the National High Magnetic Field Laboratory and on July 21, 2004 it was energized to 21.1 T. Commercial and unique homebuilt probes, along with a standard commercial NMR console have been installed and tested with many science applications to develop this spectrometer as a user facility. Solution NMR of membrane proteins with enhanced resolution, new pulse sequences for solid state NMR taking advantage of narrowed proton linewidths, and enhanced spatial resolution and contrast leading to improved animal imaging have been documented. In addition, it is demonstrated that spectroscopy of single site 17O labeled macromolecules in a hydrated lipid bilayer environment can be recorded in a remarkably short period of time. 17O spectra of aligned samples show the potential for using this data for orientational restraints and for characterizing unique details of cation binding properties to ion channels. The success of this NHMFL magnet illustrates the potential for using a similar magnet design as an outsert for high temperature superconducting insert coils to achieve an NMR magnet with a field >25 T.

  16. A new high resolution total magnetic intensity data set of the Laacher See Volcano in the East-Eifel volcanic field, Germany

    NASA Astrophysics Data System (ADS)

    Goepel, A.; Queitsch, M.; Lonschinski, M.; Eitner, A.; Meisel, M.; Reißig, S.; Engelhardt, J.; Büchel, G.; Kukowski, N.

    2012-04-01

    The Laacher See Volcano (LSV) is part of the Quaternary East-Eifel volcanic field (EVF) located in the western part of Germany, where at least 103 eruptive centers have been identified. The Laacher See volcano explosively erupted about 6.3 km3 of phonolitic magma during a dominantly phreato-plinian eruption at about 12,900 BP. Despite numerous previous studies the eruptive history of LSV is not fully unveiled. For a better understanding of the eruptive history of LSV several geophysical methods, including magnetic, gravimetric and bathymetric surveys have been applied on and around Laacher See Volcano. Here we focus on the magnetic and bathymetric data. The presented high resolution magnetic data covering an area of about 25 km2 (20,000 sample points) and were collected using ground based proton magnetometers (GEM Systems GSM-19TGW, Geometrics G856) during several field campaigns. In addition, a magnetic survey on the lake was done using a non-magnetic boat as platform. The bathymetric survey was conducted on profiles (total length of 235 km) using an echo sounder GARMIN GPSMap 421. Depth data were computed to a bathymetric model on a 10 m spaced regular grid. A joint interpretation of magnetic, morphologic and bathymetric data allows us to search for common patterns which can be associated with typical volcanic features. From our data at least one new eruptive center and lava flow could be identified. Furthermore, the new data suggest that previously identified lava flows have not been accurately located.

  17. The use of high resolution ground and airborne magnetic surveys to evaluate the geometry of hydrothermal alteration zones over volcanic provinces (Invited)

    NASA Astrophysics Data System (ADS)

    Bouligand, C.; Glen, J. M.

    2013-12-01

    Geophysical methods can provide critical constraints on the distribution and volume of hydrothermal alteration, important parameters in understanding the evolution of geothermal systems. Because hydrothermal alteration modifies the magnetic properties of the volcanic substratum, magnetic surveys can be used to provide constraints on the distribution of hydrothermal alteration at depth. Using Yellowstone caldera as an example, we show that both ground and airborne magnetic surveys can be used to map and assess the volume of hydrothermal alteration. Ground magnetic surveys over unaltered volcanic terranes display high-amplitude, short-wavelength anomalies, in contrast to smooth, subdued magnetic anomalies over volcanic substrata demagnetized by hydrothermal alteration. We use this contrast to map areas of hydrothermal alteration in detail. Inverse methods applied to high-resolution airborne and ground magnetic data can be used to create three-dimensional models of the distribution of magnetization and thus illuminate the geometry of hydrothermal alteration. Because of the non-uniqueness of potential fields, the construction of inverse models requires simplifying assumptions on the distribution of magnetization, knowledge of induced and remanent magnetization of fresh and altered geological units, and detailed geological and geophysical data. Within the three hydrothermal sites that we investigated in Yellowstone National Park, subdued short-wavelength signal indicates pervasive demagnetization (alteration) of the shallow substratum that extends over larger areas than initially mapped by geology. These data also reveal that the largest degree of demagnetization (alteration) and maximum thicknesses of demagnetized (altered) substratum, reaching a few hundred meters, are associated with hydrothermal vents and with superficial hydrothermal alteration. Our three dimensional models of magnetization provide estimates of the volume of buried hydrothermal alteration ranging

  18. Estimation of Basal Depth of Magnetic Sources from High Resolution Aeromagnetic Data of Middle Niger Basin, Nigeria using Adapted Centroid Technique for Fractal Distribution of Sources

    NASA Astrophysics Data System (ADS)

    Nwankwo, L.

    2015-12-01

    An estimate of depths to the bottom of magnetic sources in the Middle Niger Basin, north-central Nigeria has been made from a recently acquired high-resolution aeromagnetic data using adapted centroid technique for fractal distribution of sources. The result shows that the depth varies between 11.71 and 26.53 km. Deeper values are found in northern and central regions while values as low as 12 km were observed in the southern part. The shallower depths to the bottom of magnetic sources may be representing the thermal/petrological boundaries in the basin. This study is therefore crucial for quantitative understanding of the geo-processes and geothermal parameters in the study area.

  19. Unilateral symptomatic intracranial arterial stenosis and myopathy in an adolescent with Graves disease: a case report of an high-resolution magnetic resonance imaging study.

    PubMed

    Yin, Jia; Zhu, Jiajia; Huang, Dongling; Shi, Changzheng; Guan, Yuqing; Zhou, Liang; Pan, Suyue

    2015-01-01

    Vascular and muscular involvements in Graves disease (GD) are rare. Here, we report a case of a 17-year-old patient with unilateral symptomatic middle cerebral artery stenosis concurrent with GD and myopathy. He presented with a 1-day history of acute severe right-sided hemiparesis and aphasia and a 3-week history of high metabolic syndrome. The pathogenesis of the stenosis is most likely vasculitis rather than atherosclerosis, based on contrast-enhanced high-resolution magnetic resonance imaging showing concentric wall enhancement. We suggest that lipid storage myopathy is secondary to GD, and it is likely mitochondrial dysfunction or immune dysfunction induced by GD responsible for the myopathy and that magnetic resonance spectroscopy (MRS) is capable of establishing the diagnosis of myopathy. Thus, MRS can be used for follow-up evaluations of the myopathy along with the pathology biopsy. PMID:25444029

  20. Witnessing magnetic twist with high-resolution observation from the 1.6-m New Solar Telescope

    PubMed Central

    Wang, Haimin; Cao, Wenda; Liu, Chang; Xu, Yan; Liu, Rui; Zeng, Zhicheng; Chae, Jongchul; Ji, Haisheng

    2015-01-01

    Magnetic flux ropes are highly twisted, current-carrying magnetic fields. They are crucial for the instability of plasma involved in solar eruptions, which may lead to adverse space weather effects. Here we present observations of a flaring using the highest resolution chromospheric images from the 1.6-m New Solar Telescope at Big Bear Solar Observatory, supplemented by a magnetic field extrapolation model. A set of loops initially appear to peel off from an overall inverse S-shaped flux bundle, and then develop into a multi-stranded twisted flux rope, producing a two-ribbon flare. We show evidence that the flux rope is embedded in sheared arcades and becomes unstable following the enhancement of its twists. The subsequent motion of the flux rope is confined due to the strong strapping effect of the overlying field. These results provide a first opportunity to witness the detailed structure and evolution of flux ropes in the low solar atmosphere. PMID:25919706

  1. Witnessing magnetic twist with high-resolution observation from the 1.6-m New Solar Telescope.

    PubMed

    Wang, Haimin; Cao, Wenda; Liu, Chang; Xu, Yan; Liu, Rui; Zeng, Zhicheng; Chae, Jongchul; Ji, Haisheng

    2015-01-01

    Magnetic flux ropes are highly twisted, current-carrying magnetic fields. They are crucial for the instability of plasma involved in solar eruptions, which may lead to adverse space weather effects. Here we present observations of a flaring using the highest resolution chromospheric images from the 1.6-m New Solar Telescope at Big Bear Solar Observatory, supplemented by a magnetic field extrapolation model. A set of loops initially appear to peel off from an overall inverse S-shaped flux bundle, and then develop into a multi-stranded twisted flux rope, producing a two-ribbon flare. We show evidence that the flux rope is embedded in sheared arcades and becomes unstable following the enhancement of its twists. The subsequent motion of the flux rope is confined due to the strong strapping effect of the overlying field. These results provide a first opportunity to witness the detailed structure and evolution of flux ropes in the low solar atmosphere. PMID:25919706

  2. Using magnetic coupling to implement 1H, 19F, 13C experiments in routine high resolution NMR probes

    NASA Astrophysics Data System (ADS)

    Bowyer, Paul; Finnigan, Jim; Marsden, Brian; Taber, Bob; Zens, Albert

    2015-12-01

    We report in this paper the design of 1H, 19F, 13C circuitry using magnetic coupling which can do on demand experiments where one of the three nuclei is observed and the other two are decoupled. The implementation of this circuitry in routine NMR probes is compared with capacitive coupling methods where it was found that by using magnetic coupling the performance of the routine NMR probe was not impacted by the addition of this circuitry. It is surmised that using this type of circuitry would be highly desirable for those chemists doing routine 19F NMR.

  3. Identification of unknown microcontaminants in Dutch river water by liquid chromatography-high resolution mass spectrometry and nuclear magnetic resonance spectroscopy.

    PubMed

    van Leerdam, J A; Vervoort, J; Stroomberg, G; de Voogt, P

    2014-11-01

    In the past decade during automated surface water monitoring in the river Meuse at border station Eijsden in The Netherlands, a set of unknown compounds were repeatedly detected by online liquid chromatography-diode-array detection in a relatively high signal intensity. Because of the unknown nature of the compounds, the consequently unknown fate of this mixture in water treatment processes, the location being close to the water inlet of a drinking water supply company and their possible adverse public health effects, it was deemed necessary to elucidate the identity of the compounds. No data are available for the occurrence of these unknowns at downstream locations. After concentration and fractionation of a sample by preparative Liquid Chromatography, identification experiments were performed using Liquid Chromatography-High Resolution Mass Spectrometry (LC-HR-MS) combined with High Resolution Nuclear Magnetic Resonance Spectroscopy (HR-NMR). Accurate mass determination of the unknown parent compound and its fragments obtained in MS/MS provided relevant information on the elemental composition of the unknown compounds. With the use of NMR techniques and the information about the elemental composition, the identity of the compounds in the different sample fractions was determined. Beside some regularly detected compounds in surface water, like caffeine and bisphenol-S, five dihydroxydiphenylmethane isomers were identified. The major unknown compound was identified as 4,4'-dihydroxy-3,5,3',5'-tetra(hydroxymethyl)diphenylmethane. This compound was confirmed by analysis of the pure reference compound. This is one of the first studies that employs the combination of high resolution MS with NMR for identification of truly unknown compounds in surface waters at the μg/L level. Five of the seven identified compounds are unexpected and not contained in the CAS database, while they can be presumed to be products generated during the production of resins. PMID:25296128

  4. The last frontier? High-resolution, near-bottom measurements of the Hawaiian Jurassic magnetic anomaly sequence

    NASA Astrophysics Data System (ADS)

    Tivey, M.; Tominaga, M.; Sager, W. W.

    2012-12-01

    The Jurassic sequence of marine magnetic anomalies i.e. older than M29 remain the last part of the marine magnetic anomaly sequence of the geomagnetic polarity timescale (GPTS) that can be gleaned from the ocean crustal record. While Jurassic crust is present in several areas of the world's ocean basins, the oldest and arguably best preserved sequence is in the western Pacific where three lineations sets (Japanese, Hawaiian and Phoenix) converge on the oldest remaining ocean crust on the planet (i.e. crust that has not been subducted). The magnetic anomalies in these 3 lineation sets are marked by low amplitude, relatively indistinct anomalies (tiny wiggles) that collectively have been called the Jurassic quiet Zone (JQZ). Over the past 20 years we have been working on resolving the character and origin of these anomalies with various technologies to improve our resolution of this period. Following an aeromagnetic survey that revealed the possible presence of lineated anomalies older than M29 in the Japanese lineations, we conducted a deeptow magnetometer survey of the Japanese sequence in 1992. In 2002/03 we extended and confirmed this deeptow record with a deeptowed sidescan and magnetometer survey of the Japanese lineation sequence by tying in ODP Hole 801C and extending the anomaly sequence between M29 and M44. These surveys reveal remarkably fast reversals that are lineated and decrease in intensity back in time until M38, prior to which the sequence becomes somewhat confused (the LAZ or low amplitude zone) before recovering in both amplitude and lineated character around Hole 801C (M42). These results are partially supported by recently reported terrestrial magnetostratigraphy records that show the existence of reversals back to M38. A Jurassic GPTS was constructed from this Japanese anomaly sequence, but the overall global significance of the reversal sequence and systematic field intensity changes require confirmation from crustal records created at

  5. Magnetic susceptibility as a high-resolution climate proxy in lacustrine sediments of the Qaidam paleolake (NE Tibetan Plateau) throughout the Quaternary

    NASA Astrophysics Data System (ADS)

    Herb, Christian; Appel, Erwin; Koutsodendris, Andreas; Voigt, Silke; Pross, Jörg; Zhang, Weilin; Fang, Xiaomin

    2014-05-01

    Magnetic proxies in lacustrine archives play an important role as they are acquirable in high resolution due to short measurement times. One premise for building a link between magnetic properties and climate variation is to investigate what is controlling their changes. The magnetic record of drill core SG-1 (940-m-long) in the Qaidam Basin, in particular magnetic susceptibility (Ξ), is a good example for the value of magnetic properties concerning climate change. SG-1 was obtained from the Chahansilatu sub-basin in the western, presently hyper-arid Qaidam Basin and contains late Pliocene-Quaternary lacustrine sediments. Potential humidity sources in that region during the past were primarily the Westerlies but also the East Asian monsoon. Time markers for depth-time transformation of drill core SG-1 were previously acquired by magnetostratigraphic and optical stimulated luminescence (OSL) dating, indicating a time span from 2.8 to 0.1 Ma. Relating the high-amplitude variation of the Ξ record to orbital forcing and applying extensive time series analysis, a more detailed depth to time transformation is achieved. To assess the climate sensitivity of Ξ, the Ξ record is compared with other magnetic parameters and with palynological results. The pollen ratio Artemisia/Chenopodiaceae (A/C) shows a good anti-correlation with Ξ values, except of the interval around ~1.5 Ma. Thus, for core SG-1 high and low Ξ values predominantly document dryer and less dry conditions, respectively. Our observations reduce the possible mechanisms leading to the observed Ξ variation to two interfering scenarios: low-temperature oxidation (LTO) in the sedimentary source area and a change of the catchment area. As a bottom line of this study, the updated time frame of drill core SG-1 and the comparison of Ξ with other magnetic properties and palynological results lead to a well-dated, high-resolution record of humidity fluctuations during the late Pliocene-Quaternary on the NE fringe

  6. Interpenetration and deflection phenomena in collisions between supersonic, magnetized, tungsten plasma flows diagnosed using high resolution optical Thomson scattering

    SciTech Connect

    Swadling, G. F.; Lebedev, S. V.; Burdiak, G.; Suttle, L.; Patankar, S.; Smith, R. A.; Bennett, M.; Hall, G. N.; Suzuki-Vidal, F.; Bland, S.; Harvey-Thompson, A. J.; Rozmus, W.; Yuan, J.

    2015-07-15

    An optical Thomson scattering diagnostic has been used to investigate collisions between supersonic, magnetized plasma flows, in particular the transition from collisionless to collisional interaction dynamics. These flows were produced using tungsten wire array z-pinches, driven by the 1.4 MA 240 ns Magpie generator at Imperial College London. Measurements of the collective-mode Thomson scattering ion-feature clearly indicate that the ablation flows are interpenetrating at 100 ns (after current start), and this interpenetration continues until at least 140 ns. The Thomson spectrum at 150 ns shows a clear change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streams near the axis. The Thomson scattering data also provide indirect evidence of the presence of a significant toroidal magnetic field embedded in the “precursor” plasma near the axis of the array over the period 100–140 ns; these observations are in agreement with previous measurements [Swadling et al., Phys. Rev. Lett. 113, 035003 (2014)]. The Thomson scattering measurements at 150 ns suggest that this magnetic field must collapse at around the time the dense precursor column begins to form.

  7. Interpenetration and deflection phenomena in collisions between supersonic, magnetized, tungsten plasma flows diagnosed using high resolution optical Thomson scattering

    NASA Astrophysics Data System (ADS)

    Swadling, G. F.; Lebedev, S. V.; Harvey-Thompson, A. J.; Rozmus, W.; Burdiak, G.; Suttle, L.; Patankar, S.; Smith, R. A.; Bennett, M.; Hall, G. N.; Suzuki-Vidal, F.; Bland, S.; Yuan, J.

    2015-07-01

    An optical Thomson scattering diagnostic has been used to investigate collisions between supersonic, magnetized plasma flows, in particular the transition from collisionless to collisional interaction dynamics. These flows were produced using tungsten wire array z-pinches, driven by the 1.4 MA 240 ns Magpie generator at Imperial College London. Measurements of the collective-mode Thomson scattering ion-feature clearly indicate that the ablation flows are interpenetrating at 100 ns (after current start), and this interpenetration continues until at least 140 ns. The Thomson spectrum at 150 ns shows a clear change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streams near the axis. The Thomson scattering data also provide indirect evidence of the presence of a significant toroidal magnetic field embedded in the "precursor" plasma near the axis of the array over the period 100-140 ns; these observations are in agreement with previous measurements [Swadling et al., Phys. Rev. Lett. 113, 035003 (2014)]. The Thomson scattering measurements at 150 ns suggest that this magnetic field must collapse at around the time the dense precursor column begins to form.

  8. Feasibility of high-resolution one-dimensional relaxation imaging at low magnetic field using a single-sided NMR scanner applied to articular cartilage

    NASA Astrophysics Data System (ADS)

    Rössler, Erik; Mattea, Carlos; Stapf, Siegfried

    2015-02-01

    Low field Nuclear Magnetic Resonance increases the contrast of the longitudinal relaxation rate in many biological tissues; one prominent example is hyaline articular cartilage. In order to take advantage of this increased contrast and to profile the depth-dependent variations, high resolution parameter measurements are carried out which can be of critical importance in an early diagnosis of cartilage diseases such as osteoarthritis. However, the maximum achievable spatial resolution of parameter profiles is limited by factors such as sensor geometry, sample curvature, and diffusion limitation. In this work, we report on high-resolution single-sided NMR scanner measurements with a commercial device, and quantify these limitations. The highest achievable spatial resolution on the used profiler, and the lateral dimension of the sensitive volume were determined. Since articular cartilage samples are usually bent, we also focus on averaging effects inside the horizontally aligned sensitive volume and their impact on the relaxation profiles. Taking these critical parameters into consideration, depth-dependent relaxation time profiles with the maximum achievable vertical resolution of 20 μm are discussed, and are correlated with diffusion coefficient profiles in hyaline articular cartilage in order to reconstruct T2 maps from the diffusion-weighted CPMG decays of apparent relaxation rates.

  9. High-Resolution Magnetic Susceptibility Stratigraphy Spanning Late Devonian Global Change from a New Scientific Drillcore in Canning Basin, Northwest Australia

    NASA Astrophysics Data System (ADS)

    Diamond, M. R.; Raub, T. D.; Kirschvink, J. L.; Playton, T. E.; Hocking, R. M.; Haines, P.; Tulipani, S.

    2010-12-01

    New shallow scientific drillcore has been recovered through the Frasnian-Famennian extinction boundary in northwest Australia’s Canning Basin. Previous work in the McWhae Ridge outcrop belt has identified patterns of turnover in trilobites and other fauna, change from sponge- and coral-dominated reefs to post-extinction microbial-dominated reefs, apparent sea level changes, and carbon isotopic evidence of late Devonian crisis. Continuous magnetic susceptibility (MS) stratigraphy yields highly structured oscillations spanning ~42 m of reef-slope carbonate. These oscillations appear to identify late Frasnian “Kellwasser” events and they may record sedimentary response to orbital variations, establishing a high-resolution relative chronostratigraphy of late Devonian global change. Magnetic susceptibility stratigraphy has been proposed as a generally useful chronometer for late Devonian time. Most of fifteen published MS stratigraphies crossing the Frasnian-Famennian boundary appear to share major excursions with the new McWhae Ridge result. Although upland tectonism in Canning Basin may be a caveat to straightforward eustatic interpretation of magnetic susceptibility variations, we suggest the higher-resolution and fresh drillcore context of this result prioritizes it as a standard for Frasnian-Famennian magnetic susceptibility variation.

  10. Magnetic ordering in double perovskites R2CoMnO6 (R = Y, Tb) investigated by high resolution neutron spectroscopy.

    PubMed

    Chatterji, Tapan; Frick, Bernhard; Nair, Harikrishnan S

    2012-07-01

    We have investigated low energy nuclear spin excitations in double perovskite compounds R(2)CoMnO(6) (R=Y, Tb) by inelastic neutron scattering with a high resolution back-scattering spectrometer. We observed inelastic signals at about 2.1 μeV for Y(2)CoMnO(6) and also for Tb(2)CoMnO(6) at T = 2 K in both energy-loss and energy-gain sides. We interpret these inelastic peaks to be due to the transitions between the hyperfine split nuclear levels of the (59)Co nucleus. The inelastic peaks move towards the central elastic peak and finally merge with it at the magnetic ordering temperature T(C). The energy of the low energy excitations decreases continuously and becomes zero at T(C) ≈ 75 K for Y(2)CoMnO(6) and T(C) ≈ 100 K for Tb(2)CoMnO(6). For Tb(2)CoMnO(6), which contains magnetic rare earth ions, additional quasielastic scattering due presumably to the fluctuations of large Tb magnetic moments was observed. The present study reveals the magnetic ordering of the Co sublattice. The results of this investigation along with that obtained by us for other compounds indicate the presence of unquenched orbital moments in some of the Co compounds. PMID:22691537

  11. Domain wall transformations and hopping in La(0.7)Sr(0.3)MnO(3) nanostructures imaged with high resolution x-ray magnetic microscopy.

    PubMed

    Finizio, S; Foerster, M; Krüger, B; Vaz, C A F; Miyawaki, T; Mawass, M A; Peña, L; Méchin, L; Hühn, S; Moshnyaga, V; Büttner, F; Bisig, A; Le Guyader, L; El Moussaoui, S; Valencia, S; Kronast, F; Eisebitt, S; Kläui, M

    2014-11-12

    We investigate the effect of electric current pulse injection on domain walls in La(0.7)Sr(0.3)MnO(3) (LSMO) half-ring nanostructures by high resolution x-ray magnetic microscopy at room temperature. Due to the easily accessible Curie temperature of LSMO, we can employ reasonable current densities to induce the Joule heating necessary to observe effects such as hopping of the domain walls between different pinning sites and nucleation/annihilation events. Such effects are the dominant features close to the Curie temperature, while spin torque is found to play a small role close to room temperature. We are also able to observe thermally activated domain wall transformations and we find that, for the analyzed geometries, the vortex domain wall configuration is energetically favored, in agreement with micromagnetic simulations. PMID:25336527

  12. Direct high-resolution nuclear magnetic resonance studies of cation transport in vivo. Na/sup +/ transport in yeast cells

    SciTech Connect

    Balschi, J.A.; Cirillo, V.P.; Springer, C.S. Jr.

    1982-06-01

    A new nuclear magnetic resonance (NMR) method for monitoring transmembrane metal cation transport is reported. It is illustrated with a study of Na/sup +/ efflux from Na/sup +/-rich yeast cells. The technique involves the use of an anionic paramagnetic shift reagent, present only outside the cells, to induce a splitting of the sodium-23 NMR peak, in this case, into components representing intra- and extracellular Na/sup +/. The time course of the efflux is in good agreement with the literature and can be well fitted with a double exponential decay expression. Splitting of the lithium-7 NMR signal from a suspension of Li/sup +/-rich respiratory-deficient, petite yeasts is also reported.

  13. Coronal extension of flaring region magnetic fields inferred from high-resolution microwave and type III burst observations

    NASA Technical Reports Server (NTRS)

    Lantos, P.; Pick, M.; Kundu, M. R.

    1984-01-01

    Observations of three solar radio bursts, obtained with the Very Large Array of the National Radio Astronomy Observatory at 6 cm wavelength, have been combined with meter observations from the Mark III Nancay Radioheliograph. There is a good correlation between solar activity observed at the two wavelength domains. A small change by about 10 sec in the centimetric burst location corresponds to a large change, by about 0.5 solar radius, in the related metric type III burst location. This indicates discrete injection/acceleration regions and the presence of very divergent magnetic fields. The bursts come from two distinct active regions. With two-dimensional spatial resolution, it is shown that, in this sample, each active region possesses a coronal extension that is separated from that of the neighboring active region.

  14. Mechanisms of HCV NS3 Helicase Monitored by Optical Tweezers

    PubMed Central

    Cheng, Wei

    2015-01-01

    As one of the essential enzymes for viral genome replication, the hepatitis C virus NS3 helicase is one of the best characterized RNA helicases to date in understanding the mechanistic cycles in a helicase-catalyzed strand separation reaction. Recently, single-molecule studies on NS3, in particular the use of optical tweezers with sub-base pair spatial resolution, have allowed people to examine the potential elementary steps of NS3 in unwinding the double-stranded RNA fueled by ATP binding and hydrolysis. In this chapter, I detail the essential technical elements involved in conducting a high-resolution optical tweezers study of NS3 helicase, starting from the purification of the recombinant helicase protein from E. coli to setting up a high-resolution single-molecule experiment using optical tweezers. PMID:25579590

  15. Crustal architecture of the Faroe-Shetland Margin: insights from a newly merged high resolution gravity and magnetic dataset

    NASA Astrophysics Data System (ADS)

    Rippington, Stephen; Mazur, Stan; Anderson, Chris

    2014-05-01

    The Faroe-Shetland region is geologically complex; it has undergone several phases of extension and rifting since the middle Palaeozoic (Ritchie et al., 2011; Coward et al., 2003), culminating in the Eocene with continental breakup between Northwest Europe and Greenland (Gernigon et al., 2012). Final breakup may have been facilitated by the presence of the Iceland Plume and was accompanied by the emplacement of voluminous basaltic rocks, attributed to the North Atlantic Igneous Province (White and McKenzie, 1989). It is difficult to image beneath the thick Paleogene basalts in the region using conventional seismic methods, because the high impedance contrast between the sediments and shallow basalts causes strong reflections. These mask deeper and weaker reflections and cause prominent inter-bed multiples (White et al., 1999). Consequently, determining the location and shape of basins and basement highs, and elucidating the timing and manner of their formation, remains a major cause of uncertainty in the appraisal of the hydrocarbon potential of the region. Gravity and magnetic data record variations in the density and susceptibility of the entire crust. Consequently, the thick basalt piles that are shallow in the section do not hinder the ability to detect deeper features. Instead, the principal challenge is distinguishing superposed bodies, with different densities and susceptibilities, from the combined gravity and magnetic anomalies. In this study, seismic data and horizons from the shallow section are used in combination with gravity and magnetic data to produce map view interpretations, and 2D and 3D models of the crust in the Faroe-Shetland region. These models help distinguish important variations in timing of rifting in different basins, and reveal the crustal architecture of the Faroe-Shetland Basin from the seabed to the Moho. We present a new structural and kinematic interpretation of the geology of the region, and propose an asymmetric simple shear

  16. The effects of magnetic fields exposure on relative permittivity of saline solutions measured by a high resolution SPR system.

    PubMed

    Jiang, Li; Zhao, Xinyuan; Fei, Yue; Yu, Dongdong; Qian, Jun; Tong, Jinguang; Chen, Guangdi; He, Sailing

    2016-01-01

    A measurement system for the relative permittivity of a physiological solution under 50 Hz magnetic fields (MF) is presented. It is based on a phase-sensitive surface plasmon resonance (SPR) system. Relative permittivity was analyzed for different solute concentrations of sodium chloride under various MF exposure parameters. We found that MF exposure at 0.2-4.0 mT step-wise decreased significantly the SPR phase signal of a 0.9% sodium chloride solution while 0.1 mT of MF exposure did not. The decreases in the SPR phase signal depended on the duration of MF exposure, and the signal reached a plateau after 15 min of exposure. Interestingly, the decreased SPR phase signal showed a gradual increase and approached the background level when the exposure was drawn off. In addition, we found that the response of the sodium chloride solution to MF also depended on its concentration. In brief, the relative permittivity of sodium chloride in solutions appears to be practically affected by 50 Hz MF exposure. Our data indicates that the relative permittivity of the saline solution influenced by MF exposure should be considered when investigating the biological effects of MF exposure on organisms in experimental study. PMID:27121618

  17. The effects of magnetic fields exposure on relative permittivity of saline solutions measured by a high resolution SPR system

    NASA Astrophysics Data System (ADS)

    Jiang, Li; Zhao, Xinyuan; Fei, Yue; Yu, Dongdong; Qian, Jun; Tong, Jinguang; Chen, Guangdi; He, Sailing

    2016-04-01

    A measurement system for the relative permittivity of a physiological solution under 50 Hz magnetic fields (MF) is presented. It is based on a phase-sensitive surface plasmon resonance (SPR) system. Relative permittivity was analyzed for different solute concentrations of sodium chloride under various MF exposure parameters. We found that MF exposure at 0.2–4.0 mT step-wise decreased significantly the SPR phase signal of a 0.9% sodium chloride solution while 0.1 mT of MF exposure did not. The decreases in the SPR phase signal depended on the duration of MF exposure, and the signal reached a plateau after 15 min of exposure. Interestingly, the decreased SPR phase signal showed a gradual increase and approached the background level when the exposure was drawn off. In addition, we found that the response of the sodium chloride solution to MF also depended on its concentration. In brief, the relative permittivity of sodium chloride in solutions appears to be practically affected by 50 Hz MF exposure. Our data indicates that the relative permittivity of the saline solution influenced by MF exposure should be considered when investigating the biological effects of MF exposure on organisms in experimental study.

  18. Low- and high-resolution nuclear magnetic resonance (NMR) characterisation of hyaluronan-based native and sulfated hydrogels.

    PubMed

    Barbucci, Rolando; Leone, Gemma; Chiumiento, Antonio; Di Cocco, Maria Enrica; D'Orazio, Giovanni; Gianferri, Raffaella; Delfini, Maurizio

    2006-08-14

    Hyaluronan-based hydrogels were synthesised using different crosslinking agents, such as 1,3-diaminopropane (1,3-DAP) and 1,6-diaminohexane (1,6-DAE). The hydrogels were sulfated to provide materials (Hyal-1,3-DAP, Hyal-1,6-DAE, HyalS-1,3-DAP and HyalS-1,6-DAE) that were characterised by both high- and low-resolution nuclear magnetic resonance (NMR) spectroscopy. The (13)C NMR spectra of the materials were analysed to identify, characterise and study the crosslinking degree of the hydrogels. The crosslinking degree was also determined by potentiometric titration and the effectiveness of the two techniques was compared. Measurements of longitudinal relaxation times (spin-lattice) and of NOE enhancement were used to study the mobility of the hydrogels. Low-resolution NMR studies allowed the determination of the water transport properties in the hydrogels. In addition, the swelling degree for the various hydrogels was calculated as a function of the longitudinal and transversal relaxation times of the water molecules. Lastly, the self-diffusion coefficients of the water in interaction with the four polysaccharides were measured by the pulsed field gradient spin echo (PFGSE) sequence. PMID:16716277

  19. The effects of magnetic fields exposure on relative permittivity of saline solutions measured by a high resolution SPR system

    PubMed Central

    Jiang, Li; Zhao, Xinyuan; Fei, Yue; Yu, Dongdong; Qian, Jun; Tong, Jinguang; Chen, Guangdi; He, Sailing

    2016-01-01

    A measurement system for the relative permittivity of a physiological solution under 50 Hz magnetic fields (MF) is presented. It is based on a phase-sensitive surface plasmon resonance (SPR) system. Relative permittivity was analyzed for different solute concentrations of sodium chloride under various MF exposure parameters. We found that MF exposure at 0.2–4.0 mT step-wise decreased significantly the SPR phase signal of a 0.9% sodium chloride solution while 0.1 mT of MF exposure did not. The decreases in the SPR phase signal depended on the duration of MF exposure, and the signal reached a plateau after 15 min of exposure. Interestingly, the decreased SPR phase signal showed a gradual increase and approached the background level when the exposure was drawn off. In addition, we found that the response of the sodium chloride solution to MF also depended on its concentration. In brief, the relative permittivity of sodium chloride in solutions appears to be practically affected by 50 Hz MF exposure. Our data indicates that the relative permittivity of the saline solution influenced by MF exposure should be considered when investigating the biological effects of MF exposure on organisms in experimental study. PMID:27121618

  20. A high-resolution global Vlasov simulation of a small dielectric body with a weak intrinsic magnetic field on the K computer

    NASA Astrophysics Data System (ADS)

    Umeda, Takayuki; Fukazawa, Keiichiro

    2015-04-01

    The interaction between the solar wind and solar system bodies, such as planets, satellites, and asteroids, is one of the fundamental global-scale phenomena in space plasma physics. In the present study, the electromagnetic environment around a small dielectric body with a weak intrinsic magnetic field is studied by means of a first-principle kinetic plasma simulation, which is a challenging task in space plasma physics as well as high-performance computing. Due to several computational limitations, five-dimensional full electromagnetic Vlasov simulations with two configuration space and three velocity space coordinates are performed with two different spatial resolutions. The Debye-scale charge separation is not solved correctly in the simulation run with a low spatial resolution, while all the physical processes in collisionless plasma are included in the simulation run with a high spatial resolution. The direction comparison of electromagnetic fields between the two runs shows that there is small difference in the structure of magnetic field lines. On the other hand, small-scale fine structures of electrostatic fields are enhanced by the electric charge separation and the charge accumulation on the surface of the body in the high-resolution run, while these structures are absent in the low-resolution runs. These results are consistent with the conventional understanding of plasma physics that the structure and dynamics of global magnetic fields, which are generally described by the magneto-hydro-dynamics (MHD) equations, are not affected by electron-scale microphysics.

  1. Multi-wavelength High-resolution Observations of a Small-scale Emerging Magnetic Flux Event and the Chromospheric and Coronal Response

    NASA Astrophysics Data System (ADS)

    Vargas Domínguez, Santiago; Kosovichev, Alexander; Yurchyshyn, Vasyl

    2014-10-01

    State-of-the-art solar instrumentation is now revealing magnetic activity of the Sun with unprecedented temporal and spatial resolutions. Observations with the 1.6 m aperture New Solar Telescope (NST) of the Big Bear Solar Observatory are making next steps in our understanding of the solar surface structure. Granular-scale magnetic flux emergence and the response of the solar atmosphere are among the key research topics of high-resolution solar physics. As part of a joint observing program with NASA's Interface Region Imaging Spectrograph (IRIS) mission on 2013 August 7, the NST observed active region NOAA 11,810 in the photospheric TiO 7057 Å band with a resolution of pixel size of 0.''034 and chromospheric He I 10830 Å and Hα 6563 Å wavelengths. Complementary data are provided by the Solar Dynamics Observatory (SDO) and Hinode space-based telescopes. The region displayed a group of solar pores, in the vicinity of which we detect a small-scale buoyant horizontal magnetic flux tube causing granular alignments and interacting with the preexisting ambient field in the upper atmospheric layers. Following the expansion of distorted granules at the emergence site, we observed a sudden appearance of an extended surge in the He I 10830 Å data (bandpass of 0.05 Å). The IRIS transition region imaging caught ejection of a hot plasma jet associated with the He I surge. The SDO/HMI data used to study the evolution of the magnetic and Doppler velocity fields reveal emerging magnetic loop-like structures. Hinode/Ca II H and IRIS filtergrams detail the connectivities of the newly emerged magnetic field in the lower solar chromosphere. From these data, we find that the orientation of the emerging magnetic field lines from a twisted flux tube formed an angle of ~45° with the overlying ambient field. Nevertheless, the interaction of emerging magnetic field lines with the pre-existing overlying field generates high-temperature emission regions and boosts the surge

  2. Multi-wavelength high-resolution observations of a small-scale emerging magnetic flux event and the chromospheric and coronal response

    SciTech Connect

    Vargas Domínguez, Santiago; Kosovichev, Alexander; Yurchyshyn, Vasyl

    2014-10-20

    State-of-the-art solar instrumentation is now revealing magnetic activity of the Sun with unprecedented temporal and spatial resolutions. Observations with the 1.6 m aperture New Solar Telescope (NST) of the Big Bear Solar Observatory are making next steps in our understanding of the solar surface structure. Granular-scale magnetic flux emergence and the response of the solar atmosphere are among the key research topics of high-resolution solar physics. As part of a joint observing program with NASA's Interface Region Imaging Spectrograph (IRIS) mission on 2013 August 7, the NST observed active region NOAA 11,810 in the photospheric TiO 7057 Å band with a resolution of pixel size of 0.''034 and chromospheric He I 10830 Å and Hα 6563 Å wavelengths. Complementary data are provided by the Solar Dynamics Observatory (SDO) and Hinode space-based telescopes. The region displayed a group of solar pores, in the vicinity of which we detect a small-scale buoyant horizontal magnetic flux tube causing granular alignments and interacting with the preexisting ambient field in the upper atmospheric layers. Following the expansion of distorted granules at the emergence site, we observed a sudden appearance of an extended surge in the He I 10830 Å data (bandpass of 0.05 Å). The IRIS transition region imaging caught ejection of a hot plasma jet associated with the He I surge. The SDO/HMI data used to study the evolution of the magnetic and Doppler velocity fields reveal emerging magnetic loop-like structures. Hinode/Ca II H and IRIS filtergrams detail the connectivities of the newly emerged magnetic field in the lower solar chromosphere. From these data, we find that the orientation of the emerging magnetic field lines from a twisted flux tube formed an angle of ∼45° with the overlying ambient field. Nevertheless, the interaction of emerging magnetic field lines with the pre-existing overlying field generates high-temperature emission regions and boosts the surge

  3. High-resolution In Vivo Manual Segmentation Protocol for Human Hippocampal Subfields Using 3T Magnetic Resonance Imaging.

    PubMed

    Winterburn, Julie; Pruessner, Jens C; Sofia, Chavez; Schira, Mark M; Lobaugh, Nancy J; Voineskos, Aristotle N; Chakravarty, M Mallar

    2015-01-01

    The human hippocampus has been broadly studied in the context of memory and normal brain function and its role in different neuropsychiatric disorders has been heavily studied. While many imaging studies treat the hippocampus as a single unitary neuroanatomical structure, it is, in fact, composed of several subfields that have a complex three-dimensional geometry. As such, it is known that these subfields perform specialized functions and are differentially affected through the course of different disease states. Magnetic resonance (MR) imaging can be used as a powerful tool to interrogate the morphology of the hippocampus and its subfields. Many groups use advanced imaging software and hardware (>3T) to image the subfields; however this type of technology may not be readily available in most research and clinical imaging centers. To address this need, this manuscript provides a detailed step-by-step protocol for segmenting the full anterior-posterior length of the hippocampus and its subfields: cornu ammonis (CA) 1, CA2/CA3, CA4/dentate gyrus (DG), strata radiatum/lacunosum/moleculare (SR/SL/SM), and subiculum. This protocol has been applied to five subjects (3F, 2M; age 29-57, avg. 37). Protocol reliability is assessed by resegmenting either the right or left hippocampus of each subject and computing the overlap using the Dice's kappa metric. Mean Dice's kappa (range) across the five subjects are: whole hippocampus, 0.91 (0.90-0.92); CA1, 0.78 (0.77-0.79); CA2/CA3, 0.64 (0.56-0.73); CA4/dentate gyrus, 0.83 (0.81-0.85); strata radiatum/lacunosum/moleculare, 0.71 (0.68-0.73); and subiculum 0.75 (0.72-0.78). The segmentation protocol presented here provides other laboratories with a reliable method to study the hippocampus and hippocampal subfields in vivo using commonly available MR tools. PMID:26575133

  4. Paleomagnetic and rock magnetic study of IODP Site U1408 in the Northwest Atlantic - toward the high-resolution relative paleointensity estimate during the middle Eocene

    NASA Astrophysics Data System (ADS)

    Yamamoto, Y.; Yamazaki, T.; Oda, H.

    2015-12-01

    We have conducted paleomagnetic and rock magnetic measurements on the sedimentary sections recovered from Integrated Ocean Drilling Program (IODP) Site U1408 in the Northwest Atlantic, off Newfoundland. The measurements were done on u-channel samples using a pass-through superconducting rock magnetometer in a manner that remanent magnetizations (natural, anhysteretic and isothermal remanent magnetizations: NRM, ARM and IRM) were subjected to stepwise alternating field (AF) demagnetizations up to 80 mT and are measured with 1 cm spacing at each step.The characteristic remanent magnetization (ChRM) was resolved after AF demagnetization of 20-30 mT for most of the studied interval. As a result, we could identify several polarity reversals which were able to be correlated with the geomagnetic polarity time scale by Gradstein et al. (2012) (Geologic Time Scale 2012), with referring the shipboard biostratigraphy (Norris et al., 2014). The interval at ~ 33-157 mcd (meter composite depth) was interpreted to cover the Chrons C18n.1n to C20n with missing Chron C19n because of the somewhat ambiguous magnetic signals at the interval at ~ 70-110 mcd. The correlation provided an age model inferring sedimentation rate of about 2-4 cm/kyr during these chrons.There is the interval that shows relatively constant ARM and IRM intensities as well as ratios of ARM to IRM (ARM/IRM): the interval at ~ 37-90 mcd resulted in ARM intensity of 0.2-0.4 A/m, IRM intensity of 1-2 A/m and ARM/IRM of 0.17-0.20. This interval corresponds to the Chron C18 and the estimated sedimentation rate of the interval is ~ 2 cm/kyr. It is expected that high-resolution relative paleointensity estimate during the middle Eocene is potentially possible. We will report a preliminary estimate.

  5. Iron in the Fire: Searching for Fire's Magnetic Fingerprint using Controlled Heating Experiments, High-Resolution FORCs, IRM Coercivity Spectra, and Low-Temperature Remanence Experiments

    NASA Astrophysics Data System (ADS)

    Lippert, P. C.; Reiners, P. W.

    2014-12-01

    Evidence for recent climate-wildfire linkages underscores the need for better understanding of relationships between wildfire and major climate shifts in Earth history, which in turn offers the potential for prognoses for wildfire and human adaptations to it. In particular, what are the links between seasonality and wildfire frequency and severity, and what are the feedbacks between wildfire, landscape evolution, and biogeochemical cycles, particularly the carbon and iron cycles? A key first step in addressing these questions is recovering well-described wildfire records from a variety of paleolandscapes and paleoclimate regimes. Although charcoal and organic biomarkers are commonly used indicators of fire, taphonomic processes and time-consuming analytical preparations often preclude their routine use in some environments and in high-stratigraphic resolution paleowildfire surveying. The phenomenological relationship between fire and magnetic susceptibility can make it a useful surveying tool, but increased magnetic susceptibility in sediments is not unique to fire, and thus limits its diagnostic power. Here we utilize component-specific rock magnetic methods and analytical techniques to identify the rock magnetic fingerprint of wildfire. We use a custom-designed air furnace, a series of iron-free laboratory soils, natural saprolites and soils, and fuels from Arizona Ponderosa pine forests and grasslands to simulate wildfire in a controlled and monitored environment. Soil-ash residues and soil and fuel controls were then characterized using First Order Reversal Curve (FORC) patterns, DC backfield IRM coercivity spectra, low-temperature SIRM demagnetization behavior, and low-temperature cycling of room-temperature SIRM behavior. We will complement these magnetic analyses with high-resolution TEM of magnetic extracts. Here we summarize the systematic changes to sediment magnetism as pyrolitized organic matter is incorporated into artificial and natural soils. These

  6. High resolution magnetic resonance imaging of the calcaneus: age-related changes in trabecular structure and comparison with dual X-ray absorptiometry measurements

    NASA Technical Reports Server (NTRS)

    Ouyang, X.; Selby, K.; Lang, P.; Engelke, K.; Klifa, C.; Fan, B.; Zucconi, F.; Hottya, G.; Chen, M.; Majumdar, S.; Genant, H. K.

    1997-01-01

    A high-resolution magnetic resonance imaging (MRI) protocol, together with specialized image processing techniques, was applied to the quantitative measurement of age-related changes in calcaneal trabecular structure. The reproducibility of the technique was assessed and the annual rates of change for several trabecular structure parameters were measured. The MR-derived trabecular parameters were compared with calcaneal bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA) in the same subjects. Sagittal MR images were acquired at 1.5 T in 23 healthy women (mean age: 49.3 +/- 16.6 [SD]), using a three-dimensional gradient echo sequence. Image analysis procedures included internal gray-scale calibration, bone and marrow segmentation, and run-length methods. Three trabecular structure parameters, apparent bone volume (ABV/TV), intercept thickness (I.Th), and intercept separation (I.Sp) were calculated from the MR images. The short- and long-term precision errors (mean %CV) of these measured parameters were in the ranges 1-2% and 3-6%, respectively. Linear regression of the trabecular structure parameters vs. age showed significant correlation: ABV/TV (r2 = 33.7%, P < 0.0037), I.Th (r2 = 26.6%, P < 0.0118), I.Sp (r2 = 28.9%, P < 0.0081). These trends with age were also expressed as annual rates of change: ABV/TV (-0.52%/year), I.Th (-0.33%/year), and I.Sp (0.59%/year). Linear regression analysis also showed significant correlation between the MR-derived trabecular structure parameters and calcaneal BMD values. Although a larger group of subjects is needed to better define the age-related changes in trabecular structure parameters and their relation to BMD, these preliminary results demonstrate that high-resolution MRI may potentially be useful for the quantitative assessment of trabecular structure.

  7. High-resolution echocardiography

    NASA Technical Reports Server (NTRS)

    Nathan, R.

    1979-01-01

    High resolution computer aided ultrasound system provides two-and three-dimensional images of beating heart from many angles. System provides means for determining whether small blood vessels around the heart are blocked or if heart wall is moving normally without interference of dead and noncontracting muscle tissue.

  8. High-resolution headlamp

    NASA Astrophysics Data System (ADS)

    Gut, Carsten; Cristea, Iulia; Neumann, Cornelius

    2016-04-01

    The following article shall describe how human vision by night can be influenced. At first, front lighting systems that are already available on the market will be described, followed by their analysis with respect to the positive effects on traffic safety. Furthermore, how traffic safety by night can be increased since the introduction of high resolution headlamps shall be discussed.

  9. High resolution data acquisition

    DOEpatents

    Thornton, Glenn W.; Fuller, Kenneth R.

    1993-01-01

    A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock (38) pulse train (37) and analog circuitry (44) for generating a triangular wave (46) synchronously with the pulse train (37). The triangular wave (46) has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter (18, 32) forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter (26) counts the clock pulse train (37) during the interval to form a gross event interval time. A computer (52) then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

  10. High resolution data acquisition

    DOEpatents

    Thornton, G.W.; Fuller, K.R.

    1993-04-06

    A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock, pulse train, and analog circuitry for generating a triangular wave synchronously with the pulse train (as seen in diagram on patent). The triangular wave has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter counts the clock pulse train during the interval to form a gross event interval time. A computer then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.