Science.gov

Sample records for 4-form field strength

  1. Airborne field strength monitoring

    NASA Astrophysics Data System (ADS)

    Bredemeyer, J.; Kleine-Ostmann, T.; Schrader, T.; Münter, K.; Ritter, J.

    2007-06-01

    In civil and military aviation, ground based navigation aids (NAVAIDS) are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS) increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR) is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000) by the International Civil Aviation Organization (ICAO). One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz), the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA) accelerated method of moments (MoM) using a complex geometric model of the aircraft. First results will be presented in this paper.

  2. Magnetic field strength in solar coronal waveguides

    NASA Astrophysics Data System (ADS)

    Arregui, I.; Asensio Ramos, A.

    2017-03-01

    We applied Bayesian techniques to the problem of inferring the magnetic field strength in transversely oscillating solar coronal loops from observed periods and damping times. This was done by computing the marginal posterior probability density for parameters such as the waveguide density, the density contrast, the transverse inhomogeneity length scale, and the magnetic field strength under the assumption that the observed waves can be modelled as standing or propagating magnetohydrodynamic (MHD) kink modes of magnetic flux tubes. Our results indicate that the magnetic field strength can be inferred, even if the densities inside and outside the structure are largely unknown. When information on plasma density is available, the method enables to self-consistently include this knowledge to further constrain the inferred magnetic field strength. The inclusion of the observed oscillation damping enables to obtain information on the transverse density structuring and considerably alters the obtained posterior for the magnetic field strength.

  3. Validity of Field Tests of Upper Body Muscular Strength.

    ERIC Educational Resources Information Center

    Pate, Russell, R; And Others

    1993-01-01

    Examined the validity of field tests of elementary students' upper body muscular strength and endurance. Field tests were found to be moderately valid measures of weight-relative muscular strength but not of absolute strength and muscular endurance. (SM)

  4. 47 CFR 24.236 - Field strength limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Field strength limits. 24.236 Section 24.236... SERVICES Broadband PCS § 24.236 Field strength limits. The predicted or measured median field strength at... to a higher field strength....

  5. 47 CFR 90.671 - Field strength limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Field strength limits. 90.671 Section 90.671... 896-901/935-940 Mhz Band § 90.671 Field strength limits. The predicted or measured field strength at... all bordering MTA licensees agree to a higher field strength. MTA licensees are also required...

  6. 47 CFR 90.671 - Field strength limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Field strength limits. 90.671 Section 90.671... 896-901/935-940 Mhz Band § 90.671 Field strength limits. The predicted or measured field strength at... all bordering MTA licensees agree to a higher field strength. MTA licensees are also required...

  7. 47 CFR 24.236 - Field strength limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Field strength limits. 24.236 Section 24.236... SERVICES Broadband PCS § 24.236 Field strength limits. The predicted or measured median field strength at... to a higher field strength....

  8. 47 CFR 90.671 - Field strength limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Field strength limits. 90.671 Section 90.671... 896-901/935-940 Mhz Band § 90.671 Field strength limits. The predicted or measured field strength at... all bordering MTA licensees agree to a higher field strength. MTA licensees are also required...

  9. 47 CFR 90.671 - Field strength limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Field strength limits. 90.671 Section 90.671... 896-901/935-940 Mhz Band § 90.671 Field strength limits. The predicted or measured field strength at... all bordering MTA licensees agree to a higher field strength. MTA licensees are also required...

  10. 47 CFR 24.236 - Field strength limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Field strength limits. 24.236 Section 24.236... SERVICES Broadband PCS § 24.236 Field strength limits. The predicted or measured median field strength at... to a higher field strength....

  11. 47 CFR 24.236 - Field strength limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Field strength limits. 24.236 Section 24.236... SERVICES Broadband PCS § 24.236 Field strength limits. The predicted or measured median field strength at... to a higher field strength....

  12. 47 CFR 90.671 - Field strength limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Field strength limits. 90.671 Section 90.671... 896-901/935-940 Mhz Band § 90.671 Field strength limits. The predicted or measured field strength at... all bordering MTA licensees agree to a higher field strength. MTA licensees are also required...

  13. 47 CFR 24.236 - Field strength limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Field strength limits. 24.236 Section 24.236... SERVICES Broadband PCS § 24.236 Field strength limits. The predicted or measured median field strength at... to a higher field strength....

  14. 47 CFR 73.683 - Field strength contours and presumptive determination of field strength at individual locations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Field strength contours and presumptive... Stations § 73.683 Field strength contours and presumptive determination of field strength at individual locations. (a) In the authorization of TV stations, two field strength contours are considered. These...

  15. 47 CFR 73.683 - Field strength contours and presumptive determination of field strength at individual locations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Field strength contours and presumptive... Stations § 73.683 Field strength contours and presumptive determination of field strength at individual locations. (a) In the authorization of TV stations, two field strength contours are considered. These...

  16. 47 CFR 73.683 - Field strength contours and presumptive determination of field strength at individual locations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Field strength contours and presumptive determination of field strength at individual locations. 73.683 Section 73.683 Telecommunication FEDERAL... Stations § 73.683 Field strength contours and presumptive determination of field strength at...

  17. 47 CFR 90.689 - Field strength limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Field strength limits. 90.689 Section 90.689...-824/851-869 Mhz Band § 90.689 Field strength limits. (a) For purposes of implementing §§ 90.689... or measured field strength at any location on the border of the EA-based service area for...

  18. 47 CFR 90.689 - Field strength limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Field strength limits. 90.689 Section 90.689...-824/851-869 Mhz Band § 90.689 Field strength limits. (a) For purposes of implementing §§ 90.689... or measured field strength at any location on the border of the EA-based service area for...

  19. 47 CFR 90.689 - Field strength limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Field strength limits. 90.689 Section 90.689...-824/851-869 Mhz Band § 90.689 Field strength limits. (a) For purposes of implementing §§ 90.689... or measured field strength at any location on the border of the EA-based service area for...

  20. 47 CFR 90.689 - Field strength limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Field strength limits. 90.689 Section 90.689...-824/851-869 Mhz Band § 90.689 Field strength limits. (a) For purposes of implementing §§ 90.689... or measured field strength at any location on the border of the EA-based service area for...

  1. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  2. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  3. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b)...

  4. 47 CFR 90.689 - Field strength limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Field strength limits. 90.689 Section 90.689...-824/851-869 Mhz Band § 90.689 Field strength limits. (a) For purposes of implementing §§ 90.689... or measured field strength at any location on the border of the EA-based service area for...

  5. Interpretation of Solar Magnetic Field Strength Observations

    NASA Astrophysics Data System (ADS)

    Ulrich, R. K.; Bertello, L.; Boyden, J. E.; Webster, L.

    2009-03-01

    This study based on longitudinal Zeeman effect magnetograms and spectral line scans investigates the dependence of solar surface magnetic fields on the spectral line used and the way the line is sampled to estimate the magnetic flux emerging above the solar atmosphere and penetrating to the corona from magnetograms of the Mt. Wilson 150-foot tower synoptic program (MWO). We have compared the synoptic program λ5250 Å line of Fe i to the line of Fe i at λ5233 Å since this latter line has a broad shape with a profile that is nearly linear over a large portion of its wings. The present study uses five pairs of sampling points on the λ5233 Å line. Line profile observations show that the determination of the field strength from the Stokes V parameter or from line bisectors in the circularly polarized line profiles lead to similar dependencies on the spectral sampling of the lines, with the bisector method being the less sensitive. We recommend adoption of the field determined with the line bisector method as the best estimate of the emergent photospheric flux and further recommend the use of a sampling point as close to the line core as is practical. The combination of the line profile measurements and the cross-correlation of fields measured simultaneously with λ5250 Å and λ5233 Å yields a formula for the scale factor δ -1 that multiplies the MWO synoptic magnetic fields. By using ρ as the center-to-limb angle (CLA), a fit to this scale factor is δ -1=4.15-2.82sin 2( ρ). Previously δ -1=4.5-2.5sin 2( ρ) had been used. The new calibration shows that magnetic fields measured by the MDI system on the SOHO spacecraft are equal to 0.619±0.018 times the true value at a center-to-limb position 30°. Berger and Lites (2003, Solar Phys. 213, 213) found this factor to be 0.64±0.013 based on a comparison using the Advanced Stokes Polarimeter.

  6. 47 CFR 18.305 - Field strength limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Field strength limits. 18.305 Section 18.305... Standards § 18.305 Field strength limits. (a) ISM equipment operating on a frequency specified in § 18.301... strength levels of emissions which lie outside the bands specified in § 18.301, unless otherwise...

  7. 47 CFR 90.771 - Field strength limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Field strength limits. 90.771 Section 90.771... strength limits. (a) The transmissions from base stations, or fixed stations transmitting on base station transmit frequencies, of EA and Regional licensees may not exceed a predicted 38 dBu field strength...

  8. 47 CFR 90.771 - Field strength limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Field strength limits. 90.771 Section 90.771... Policies Governing the Licensing and Use of Phase II Ea, Regional and Nationwide Systems § 90.771 Field... transmit frequencies, of EA and Regional licensees may not exceed a predicted 38 dBu field strength...

  9. 47 CFR 90.771 - Field strength limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Field strength limits. 90.771 Section 90.771... Policies Governing the Licensing and Use of Phase II Ea, Regional and Nationwide Systems § 90.771 Field... transmit frequencies, of EA and Regional licensees may not exceed a predicted 38 dBu field strength...

  10. 47 CFR 90.771 - Field strength limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Field strength limits. 90.771 Section 90.771... Policies Governing the Licensing and Use of Phase II Ea, Regional and Nationwide Systems § 90.771 Field... transmit frequencies, of EA and Regional licensees may not exceed a predicted 38 dBu field strength...

  11. 47 CFR 90.771 - Field strength limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Field strength limits. 90.771 Section 90.771... Policies Governing the Licensing and Use of Phase II Ea, Regional and Nationwide Systems § 90.771 Field... transmit frequencies, of EA and Regional licensees may not exceed a predicted 38 dBu field strength...

  12. PERMANENT MAGNET DESIGNS WITH LARGE VARIATIONS IN FIELD STRENGTH.

    SciTech Connect

    GUPTA,R.

    2004-01-21

    The use of permanent magnets has been investigated as an option for electron cooling ring for the proposed luminosity upgrade of RHIC. Several methods have been developed that allow a large variation in field strength. These design concepts were verified with computer simulations using finite element codes. It will be shown that the field uniformity is maintained while the field strength is mechanically adjusted.

  13. 47 CFR 73.184 - Groundwave field strength graphs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Groundwave field strength graphs. 73.184... RADIO BROADCAST SERVICES AM Broadcast Stations § 73.184 Groundwave field strength graphs. (a) Graphs 1... graph paper and each is to be used for the range of frequencies shown thereon. Computations are based...

  14. 47 CFR 73.184 - Groundwave field strength graphs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Groundwave field strength graphs. 73.184... RADIO BROADCAST SERVICES AM Broadcast Stations § 73.184 Groundwave field strength graphs. (a) Graphs 1... graph paper and each is to be used for the range of frequencies shown thereon. Computations are based...

  15. 47 CFR 73.184 - Groundwave field strength graphs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Groundwave field strength graphs. 73.184... RADIO BROADCAST SERVICES AM Broadcast Stations § 73.184 Groundwave field strength graphs. (a) Graphs 1... graph paper and each is to be used for the range of frequencies shown thereon. Computations are based...

  16. 47 CFR 73.184 - Groundwave field strength graphs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Groundwave field strength graphs. 73.184... RADIO BROADCAST SERVICES AM Broadcast Stations § 73.184 Groundwave field strength graphs. (a) Graphs 1... graph paper and each is to be used for the range of frequencies shown thereon. Computations are based...

  17. Energy flux determines magnetic field strength of planets and stars.

    PubMed

    Christensen, Ulrich R; Holzwarth, Volkmar; Reiners, Ansgar

    2009-01-08

    The magnetic fields of Earth and Jupiter, along with those of rapidly rotating, low-mass stars, are generated by convection-driven dynamos that may operate similarly (the slowly rotating Sun generates its field through a different dynamo mechanism). The field strengths of planets and stars vary over three orders of magnitude, but the critical factor causing that variation has hitherto been unclear. Here we report an extension of a scaling law derived from geodynamo models to rapidly rotating stars that have strong density stratification. The unifying principle in the scaling law is that the energy flux available for generating the magnetic field sets the field strength. Our scaling law fits the observed field strengths of Earth, Jupiter, young contracting stars and rapidly rotating low-mass stars, despite vast differences in the physical conditions of the objects. We predict that the field strengths of rapidly rotating brown dwarfs and massive extrasolar planets are high enough to make them observable.

  18. Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices

    SciTech Connect

    Geoffrey Krafft

    2005-09-15

    Since the earliest papers on undulaters were published, it has been known how to calculate the spontaneous emission spectrum from ''short'' undulaters when the magnetic field strength parameter is small compared to unity, or in ''single'' frequency sinusoidal undulaters where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulater. Fewer general results have been obtained in the case where the insertion device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the insertion device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field insertion devices. It is used to calculate the emission from some insertion device designs of recent interest.

  19. Pulsar Emission Geometry and Accelerating Field Strength

    NASA Technical Reports Server (NTRS)

    DeCesar, Megan E.; Harding, Alice K.; Miller, M. Coleman; Kalapotharakos, Constantinos; Parent, Damien

    2012-01-01

    The high-quality Fermi LAT observations of gamma-ray pulsars have opened a new window to understanding the generation mechanisms of high-energy emission from these systems, The high statistics allow for careful modeling of the light curve features as well as for phase resolved spectral modeling. We modeled the LAT light curves of the Vela and CTA I pulsars with simulated high-energy light curves generated from geometrical representations of the outer gap and slot gap emission models. within the vacuum retarded dipole and force-free fields. A Markov Chain Monte Carlo maximum likelihood method was used to explore the phase space of the magnetic inclination angle, viewing angle. maximum emission radius, and gap width. We also used the measured spectral cutoff energies to estimate the accelerating parallel electric field dependence on radius. under the assumptions that the high-energy emission is dominated by curvature radiation and the geometry (radius of emission and minimum radius of curvature of the magnetic field lines) is determined by the best fitting light curves for each model. We find that light curves from the vacuum field more closely match the observed light curves and multiwavelength constraints, and that the calculated parallel electric field can place additional constraints on the emission geometry

  20. 47 CFR 73.184 - Groundwave field strength graphs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... versus distance used to plot Graphs 1 to 20 are available in tabular form. For information on obtaining... strength at 1 kilometer. This is accomplished by plotting the measured field strengths on transparent log... and phase angle b. On graph paper with coordinates similar to those of Graph 21, plot the...

  1. 47 CFR 18.305 - Field strength limits.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., shall not exceed the following: Equipment Operating frequency RF Power generated by equipment (watts... more 1515×SQRT(power/500) 300 1300 Industrial heaters and RF stabilized arc welders On or below 5,725... strength limits for RF lighting devices shall be the following: Frequency (MHz) Field strength limit at...

  2. 47 CFR 18.305 - Field strength limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., shall not exceed the following: Equipment Operating frequency RF Power generated by equipment (watts... more 1515×SQRT(power/500) 300 1300 Industrial heaters and RF stabilized arc welders On or below 5,725... strength limits for RF lighting devices shall be the following: Frequency (MHz) Field strength limit at...

  3. 47 CFR 18.305 - Field strength limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., shall not exceed the following: Equipment Operating frequency RF Power generated by equipment (watts... more 1515×SQRT(power/500) 300 1300 Industrial heaters and RF stabilized arc welders On or below 5,725... strength limits for RF lighting devices shall be the following: Frequency (MHz) Field strength limit at...

  4. 47 CFR 18.305 - Field strength limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., shall not exceed the following: Equipment Operating frequency RF Power generated by equipment (watts... more 1515×SQRT(power/500) 300 1300 Industrial heaters and RF stabilized arc welders On or below 5,725... strength limits for RF lighting devices shall be the following: Frequency (MHz) Field strength limit at...

  5. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... antenna impedance to the transmission line at all frequencies measured, and, if using an unbalanced line... transmission line between the testing antenna and the field strength meter. Match the antenna impedance to...

  6. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... antenna impedance to the transmission line at all frequencies measured, and, if using an unbalanced line... transmission line between the testing antenna and the field strength meter. Match the antenna impedance to...

  7. Microchip electrophoresis at elevated temperatures and high separation field strengths.

    PubMed

    Mitra, Indranil; Marczak, Steven P; Jacobson, Stephen C

    2014-02-01

    We report free-solution microchip electrophoresis performed at elevated temperatures and high separation field strengths. We used microfluidic devices with 11 cm long separation channels to conduct separations at temperatures between 22 (ambient) and 45°C and field strengths from 100 to 1000 V/cm. To evaluate separation performance, N-glycans were used as a model system and labeled with 8-aminopyrene-1,3,6-trisulfonic acid to impart charge for electrophoresis and render them fluorescent. Typically, increased diffusivity at higher temperatures leads to increased axial dispersion and poor separation performance; however, we demonstrate that sufficiently high separation field strengths offset the impact of increased diffusivity in order to maintain separation efficiency. Efficiencies for these free-solution separations are the same at temperatures of 25, 35, and 45°C with separation field strengths ≥ 500 V/cm.

  8. Minimum Field Strength Simulator for Proton Density Weighted MRI

    PubMed Central

    Chen, Weiyi; Nayak, Krishna S.

    2016-01-01

    Objective To develop and evaluate a framework for simulating low-field proton-density weighted MRI acquisitions based on high-field acquisitions, which could be used to predict the minimum B0 field strength requirements for MRI techniques. This framework would be particularly useful in the evaluation of de-noising and constrained reconstruction techniques. Materials and Methods Given MRI raw data, lower field MRI acquisitions can be simulated based on the signal and noise scaling with field strength. Certain assumptions are imposed for the simulation and their validity is discussed. A validation experiment was performed using a standard resolution phantom imaged at 0.35 T, 1.5 T, 3 T, and 7 T. This framework was then applied to two sample proton-density weighted MRI applications that demonstrated estimation of minimum field strength requirements: real-time upper airway imaging and liver proton-density fat fraction measurement. Results The phantom experiment showed good agreement between simulated and measured images. The SNR difference between simulated and measured was ≤ 8% for the 1.5T, 3T, and 7T cases which utilized scanners with the same geometry and from the same vendor. The measured SNR at 0.35T was 1.8- to 2.5-fold less than predicted likely due to unaccounted differences in the RF receive chain. The predicted minimum field strength requirements for the two sample applications were 0.2 T and 0.3 T, respectively. Conclusions Under certain assumptions, low-field MRI acquisitions can be simulated from high-field MRI data. This enables prediction of the minimum field strength requirements for a broad range of MRI techniques. PMID:27136334

  9. Technique for Predicting the RF Field Strength Inside an Enclosure

    NASA Technical Reports Server (NTRS)

    Hallett, M.; Reddell, J.

    1998-01-01

    This Memorandum presents a simple analytical technique for predicting the RF electric field strength inside an enclosed volume in which radio frequency radiation occurs. The technique was developed to predict the radio frequency (RF) field strength within a launch vehicle's fairing from payloads launched with their telemetry transmitters radiating and to the impact of the radiation on the vehicle and payload. The RF field strength is shown to be a function of the surface materials and surface areas. The method accounts for RF energy losses within exposed surfaces, through RF windows, and within multiple layers of dielectric materials which may cover the surfaces. This Memorandum includes the rigorous derivation of all equations and presents examples and data to support the validity of the technique.

  10. Magnetic field in molecular cloud cores: Limits on field strengths and linewidths

    NASA Technical Reports Server (NTRS)

    Goodman, A. A.

    1986-01-01

    Preliminary observations by others indicate that the magnetic field strength in dense molecular cloud cores is on the order of 30 micro G, much closer to the background field strength than to the flux-freezing prediction for this density. This result implies that some process must exist to decrease the magnetic field strength in these regions to much less than its flux-frozen value, e.g., ambipolar diffusion. At these moderate field strengths, magnetohydrodynamic waves in the cores provide a good explanation of observed supra-thermal molecular linewidths.

  11. Measurements of magnetic field strengths in the vicinity of Orion

    NASA Astrophysics Data System (ADS)

    Heiles, C.; Troland, T. H.

    1982-09-01

    The line-of-sight magnetic field in two regions associated with the Orion Nebula was measured. One region is the large H I cloud which envelops the ionized and molecular clouds; the field strength is 10 microgauss. The other is the large CO cloud just south of the Orion Nebula discovered by Kutner, Tucker, and Chin (1977); the field strength here is also 10 microgauss. These results are discussed using the virial theorem. In the H I cloud, gravity appears to be weaker than the kinetic and magnetic forces, making this cloud unstable to expansion. In the CO cloud, gravity and the kinetic forces balance, and the magnetic field may be important in supporting the cloud.

  12. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....314 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.314 Field strength measurements. (a) Except as provided for in § 73.209, FM broadcast stations shall not be protected from any type of interference or...

  13. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must... applicant for an FM broadcast station. (2) In connection with problems of coverage arising out...

  14. 47 CFR 73.311 - Field strength contours.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must... applicant for an FM broadcast station. (2) In connection with problems of coverage arising out...

  15. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ....314 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.314 Field strength measurements. (a) Except as provided for in § 73.209, FM broadcast stations shall not be protected from any type of interference or...

  16. Laser Measurements of Transient High-Strength Electric Fields

    DTIC Science & Technology

    1987-07-15

    Measurements of Electric Field Strength," Poster Session of Applied Spectroscopy (Miami Valley Section), University of Dayton, January 11, 1985. 2...Buswell, A. T., "Quantum Perturbation Theory of Stark- Induced Polarizability," Poster Session of Applied Spectroscopy (Miami Valley Section), University...34Theoretical Calculations of Stark- Induced Polarizabilities," Poster Session of Applied Spectroscopy (Miami Valley Section), The Ohio State University

  17. Critical electric field strengths of onion tissues treated by pulsed electric fields.

    PubMed

    Asavasanti, Suvaluk; Ersus, Seda; Ristenpart, William; Stroeve, Pieter; Barrett, Diane M

    2010-09-01

    The impact of pulsed electric fields (PEF) on cellular integrity and texture of Ranchero and Sabroso onions (Allium cepa L.) was investigated. Electrical properties, ion leakage rate, texture, and amount of enzymatically formed pyruvate were measured before and after PEF treatment for a range of applied field strengths and number of pulses. Critical electric field strengths or thresholds (E(c)) necessary to initiate membrane rupture were different because dissimilar properties were measured. Measurement of electrical characteristics was the most sensitive method and was used to detect the early stage of plasma membrane breakdown, while pyruvate formation by the enzyme alliinase was used to identify tonoplast membrane breakdown. Our results for 100-μs pulses indicate that breakdown of the plasma membrane occurs above E(c)= 67 V/cm for 10 pulses, but breakdown of the tonoplast membrane is above either E(c)= 200 V/cm for 10 pulses or 133 V/cm for 100 pulses. This disparity in field strength suggests there may be 2 critical electrical field strengths: a lower field strength for plasma membrane breakdown and a higher field strength for tonoplast membrane breakdown. Both critical electric field strengths depended on the number of pulses applied. Application of a single pulse at an electric field up to 333 V/cm had no observable effect on any measured properties, while significant differences were observed for n≥10. The minimum electric field strength required to cause a measurable property change decreased with the number of pulses. The results also suggest that PEF treatment may be more efficient if a higher electric field strength is applied for a fewer pulses.

  18. Biaxial Flexural Strength of Poled Lead Zirconate Titanate under High Electric Field with Extended Field Range

    SciTech Connect

    Zhang, Kewei; Zeng, Fan W; Wang, Hong; Lin, Hua-Tay

    2013-01-01

    In the present work, as-received poled lead zirconate titanate, or PZT 5A, was examined using ball-on-ring (BoR) mechanical testing coupled with an electric field. Electric fields in the range of 4Ec (Ec, coercive field) with controlled loading paths were applied, and mechanical tests at a substantial number of characteristic electric field levels were conducted. Commercial electronic liquid FC-40 was used to prevent the setup from dielectric breakdown under a high electric field. Weibull strength distribution was used to interpret the mechanical strength data. The data showed that the strength levels of the PZT-5A tested under OC (open circuit) in air and in FC-40 were almost the same. It was further revealed that , for the studied cases, the effect of loading history on the biaxial flexural strength of the PZT was significant in -Ec, but not in OC or zero field as well as 4Ec . An asymmetry V curve was observed for the characteristic strength-electric field graph, and the bottom of V curve was located near the negative coercive field. Microscopy analysis showed that surface-located volume-distributed flaws were the strength limiter and responsible for the failure of the tested PZT under electromechanical loadings.

  19. Controlling flow direction in nanochannels by electric field strength

    NASA Astrophysics Data System (ADS)

    Gao, Xiang; Zhao, Tianshou; Li, Zhigang

    2015-08-01

    Molecular dynamics simulations are conducted to study the flow behavior of CsF solutions in nanochannels under external electric fields E . It is found that the channel surface energy greatly affects the flow behavior. In channels of high surface energy, water molecules, on average, move in the same direction as that of the electric field regardless of the strength of E . In low surface energy channels, however, water transports in the opposite direction to the electric field at weak E and the flow direction is changed when E becomes sufficiently large. The direction change of water flow is attributed to the coupled effects of different water-ion interactions, inhomogeneous water viscosity, and ion distribution changes caused by the electric field. The flow direction change observed in this work may be employed for flow control in complex micro- or nanofluidic systems.

  20. Dielectronic recombination as a function of electric field strength

    NASA Technical Reports Server (NTRS)

    Reisenfeld, Daniel B.

    1992-01-01

    Dielectronic recombination (DR) is the dominant recombination mechanism at coronal temperatures and densities. We present a procedure for calculating DR rate coefficients as a function of electric field strength and apply this method to carbon ions. We focus on the competing effects of enhancement by plasma microfields and rate decrease through collisional excitation and ionization. We find that, in the case of C(3+), a significant rate enhancement results, leading to a reinterpretation of C IV emission-line intensities in the sun and late-type stars. We further consider how macroscopic electric fields, in particular motional electric fields, can affect DR rate coefficients, demonstrating dramatic rate increases for a number of the carbon ions.

  1. Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.

    PubMed

    Harris, C; Boivin, W; Boyd, S; Coletta, J; Kerr, L; Kempa, K; Aronow, S

    2000-01-01

    Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms

  2. Magnetic field strength, water and life on the early Earth

    NASA Astrophysics Data System (ADS)

    Tarduno, J. A.; Cottrell, R. D.; Van Kranendonk, M. J.

    2011-12-01

    The early geomagnetic field shielded Earth from intense solar winds from the rapidly rotating young Sun. Therefore, the onset and strength of the earliest field are of prime interest for understanding evolution of the planet. Recent paleomagnetic investigations of Archean single silicate crystals hosting minute magnetic inclusions from the Kaapvaal craton, using highly sensitive SQUID magnetometers and CO2 laser demagnetization, have allowed definition of geomagnetic field intensities at 3.2, 3.4 and 3.45 Ga. Here we extend this time line to 3.47 Ga through the study of single silicate crystals from granitic rocks that are subvolcanic feeders to the Duffer Formation of the Pilbara craton. Preliminary paleointensity data are consistent with the presence of a geomagnetic field, supporting prior paleointensity results from the Kaapvaal craton that indicate a protective magnetic field was present when some of the first physical evidence for life has been reported. However, the new measured field intensities are only 25% of the modern value. These magnetic paleofield results suggest that the magnetopause was much closer to Earth during Paleoarchean times. The decreased standoff of the solar wind, together with the higher frequency of coronal mass ejections, would have promoted loss of volatiles and water from the atmosphere. Efforts to further extend observations through the paleomagnetic study of Hadean minerals will be discussed.

  3. Paleomagnetic field strength over the last million years

    NASA Astrophysics Data System (ADS)

    Ziegler, L. B.; Johnson, C. L.; Constable, C. G.

    2012-04-01

    Absolute paleomagnetic intensity data derived from thermally magnetized lavas and archeological objects provide information about past geomagnetic field behavior, but the average field strength, its variability, and the expected statistical distribution of these observations remain uncertain despite growing data sets. We present statistical characterizations of the 0-1 Ma field strength, in terms of virtual axial dipole moment (VADM), using data from the PINT, MagIC, and Geomagia50 databases. Uneven temporal sampling and large age uncertainties in the available data produce biased estimates for the mean field and its statistical distribution. We describe and apply bootstrap resampling techniques to correct for these effects. The influence of material type is assessed using independent data compilations to compare Holocene data from lava flows, Submarine Basaltic Glass (SBG), and archeological objects. The comparison to SBG is inconclusive because of dating issues, but paleointensity estimates from lavas are on average about 10% higher than for archeological materials and show greater dispersion. A further interesting basis for comparison is provided by PADM2M, a continuous model of temporal variations in axial dipole moment principally derived from relative paleointensity time series, but calibrated by incorporating absolute measurements. On average, absolute VADMs are higher than the axial dipole moment estimated in PADM2M, with greater spread in the VADM distribution. Both VADM and PADM2M distribution estimates from lavas show more structure than might be expected: neither has a smooth, unimodal distribution despite the large numbers of data used in the estimation. Simulations from a stochastic model based on the geomagnetic field spectrum demonstrate that long period intensity variations can have a strong impact on the observed distributions and could plausibly explain apparent bimodality.

  4. [3 Tesla MRI: successful results with higher field strengths].

    PubMed

    Schmitt, F; Grosu, D; Mohr, C; Purdy, D; Salem, K; Scott, K T; Stoeckel, B

    2004-01-01

    The recent development of 3 Tesla MRI (3T MRI) has been fueled by promise of increased signal-to-noise ratio(SNR). Many are excited about the opportunity to not only use the increased SNR for clearer images, but also the chance to exchange it for better resolution or faster scans. These possibilities have caused a rapid increase in the market for 3T MRI, where the faster scanning tips an already advantageous economic outlook in favor of the user. As a result, the global market for 3T has grown from a research only market just a few years ago to an ever-increasing clinically oriented customer base. There are, however, significant obstacles to 3T MRI presented by the physics at higher field strengths. For example, the T1 relaxation times are prolonged with increasing magnet field strength. Further, the increased RF-energy deposition (SAR), the larger the chemical shift and the stronger susceptibility effect have to be considered as challenges. It is critical that one looks at both the advantages and disadvantages of using 3T. While there are many issues to address aand a number of different methods for doing so, to properly tackle each of these concerns will take time and effort on the part od researchers and clinicians. The optimization of 3T MRI scanning will have to be a combined effort, though much of the work to date has been in neuroimaging. Multiple applications have been explored in addition to clinical anatomical imaging, where resolution is improved showing structure in the brain never seen before in human MRI. Body and cardiac imaging provide a great challenge but are also achievable at 3T. As an example, the full range of clinical applications currently achieved on today's state-of-the-art 1.5T cardiac MR scanners has also been demonstrated at 3T. In the body, the full range of contrast is available over large fields of view allowing whole liver studies in the clinic or, as needed, one may choose a smaller field of view for high-resolution imaging of the

  5. 47 CFR 90.359 - Field strength limits for EA-licensed LMS systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Field strength limits for EA-licensed LMS... § 90.359 Field strength limits for EA-licensed LMS systems. EA-licensed multilateration systems shall limit the field strength of signals transmitted from their base stations to 47 dBuV/m at their...

  6. 47 CFR 73.153 - Field strength measurements in support of applications or evidence at hearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Field strength measurements in support of... (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.153 Field strength..., groundwave field strength measurements will take precedence over theoretical values, provided...

  7. Review of VHF Band 1 field strength prediction

    NASA Astrophysics Data System (ADS)

    Sandell, R. S.; Lee, R. W.; Malcolm-Coe, J.

    1986-06-01

    The results of a review of Very High Frequency (VHF) Band I field strength measurements and prediction methods are described. Most of the measurements were made by the British Broadcasting Company (BBC) and many were used in the early 1960s to prepare CCIR propagation curves. Modern computational methods have permitted a fuller analysis of the data than was possible previously. This led to conculsions about the accuracy of the CCIR prediction method, how it should best be used, and the extent of discrepancies in the existing procedures. In addition, this review examines the BBC's more detailed path loss computerized prediction method. This has the potential to give more accurate results than the CCIR curves, although the program is not yet developed for operations at Band I frequencies. Finally the report makes proposals for future improvements to these prediction techniques, and considers the possibility of developing a harmonized approach.

  8. Metamaterial magnetoinductive lens performance as a function of field strength.

    PubMed

    Algarín, José M; Freire, Manuel J; Breuer, Felix; Behr, Volker C

    2014-10-01

    Metamaterials are artificial composites that exhibit exotic electromagnetic properties, as the ability of metamaterial slabs to behave like lenses with sub-wavelength resolution for the electric or the magnetic field. In previous works, the authors investigated magnetic resonance imaging (MRI) applications of metamaterial slabs that behave like lenses for the radiofrequency magnetic field. In particular, the authors investigated the ability of MRI metamaterial lenses to increase the signal-to-noise ratio (SNR) of surface coils, and to localize the field of view (FOV) of the coils, which is of interest for parallel MRI (pMRI) applications. A metamaterial lens placed between a surface coil and the tissue enhances the sensitivity of the coil. Although the metamaterial lens introduces losses which add to the losses of the tissue, the enhancement of the sensitivity can compensate these additional losses and the SNR of the coil is increased. In a previous work, an optimization procedure was followed to find a metamaterial structure with minimum losses that will maximize the SNR. This structure was termed magnetoinductive (MI) lens by the authors. The properties of surface coils in the presence of MI lenses were investigated in previous works at the proton frequency of 1.5 T systems. The different frequency dependence of the losses in both the MI lenses and the tissue encouraged us to investigate the performance of MI lenses at different frequencies. Thus, in the present work, the SNR and the pMRI ability of MI lenses are investigated as a function of field strength. A numerical analysis is carried out with an algorithm developed by the authors to predict the SNR behavior of a surface coil loaded with a MI lens at the proton frequencies of 0.5 T, 1.5 T and 3 T systems. The results show that, at 0.5 T, there is a gain in the SNR for short distances, but the SNR is highly degraded at deeper distances. However, at 1.5 T and 3T, the MI lenses provide a gain in the SNR up to a

  9. 47 CFR 27.804 - Field strength limits at WMTS facility.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Field strength limits at WMTS facility. 27.804... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 1.4 GHz Band § 27.804 Field strength limits at WMTS facility. For any operation in the 1392-1395 MHz band, the predicted or measured field strength—into the WMTS...

  10. 47 CFR 27.804 - Field strength limits at WMTS facility.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Field strength limits at WMTS facility. 27.804... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 1.4 GHz Band § 27.804 Field strength limits at WMTS facility. For any operation in the 1392-1395 MHz band, the predicted or measured field strength—into the WMTS...

  11. 47 CFR 27.804 - Field strength limits at WMTS facility.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Field strength limits at WMTS facility. 27.804... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 1.4 GHz Band § 27.804 Field strength limits at WMTS facility. For any operation in the 1392-1395 MHz band, the predicted or measured field strength—into the WMTS...

  12. 47 CFR 27.804 - Field strength limits at WMTS facility.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Field strength limits at WMTS facility. 27.804... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 1.4 GHz Band § 27.804 Field strength limits at WMTS facility. For any operation in the 1392-1395 MHz band, the predicted or measured field strength—into the WMTS...

  13. Fretting friction and wear characteristics of magnetorheological fluid under different magnetic field strengths

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Lee, K. H.; Lee, C. H.

    2017-01-01

    A magnetorheological fluid (MRF) performs differently under different magnetic field strength. This study examined the fretting friction and wear characteristics of MRFs under a range of magnetic field strengths and oscillation frequencies. The fretting friction and wear behaviors of MRF are investigated using a fretting friction and wear tester. The surfaces of specimen are examined by optical microscopy and 3D surface profilometer before and after the tests and wear surface profiles, the wear volume loss and wear coefficient for each magnetic field strength are evaluated. The results show that the friction and wear properties of MRF change according to the magnetic field strength and oscillation frequency.

  14. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  15. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  16. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  17. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  18. 47 CFR 73.61 - AM directional antenna field strength measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false AM directional antenna field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.61 AM directional antenna field strength measurements. (a) Each AM station using a directional antenna with monitoring point...

  19. Optical Field-Strength Polarization of Two-Mode Single-Photon States

    ERIC Educational Resources Information Center

    Linares, J.; Nistal, M. C.; Barral, D.; Moreno, V.

    2010-01-01

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of…

  20. 47 CFR 27.804 - Field strength limits at WMTS facility.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Field strength limits at WMTS facility. 27.804... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES 1.4 GHz Band § 27.804 Field strength limits at WMTS facility. For... at 1395-1400 MHz—shall not exceed 150 uV/m at the location of any registered WMTS healthcare...

  1. A Field Test for Upper Body Strength and Endurance.

    ERIC Educational Resources Information Center

    Nelson, Jack K.; And Others

    1991-01-01

    Researchers studied the reliability of the modified push-up test in measuring upper body strength and endurance in elementary through college students. It also examined the accuracy of partner scoring. The test proved much easier to administer than the regular floor push-up. It was valid and reliable for all students and suitable for partner…

  2. The Strength of PIN-PMN-PT Single Crystals under Bending with a Longitudinal Electric Field

    DTIC Science & Technology

    2011-04-06

    The strength of PIN– PMN – PT single crystals under bending with a longitudinal electric field This article has been downloaded from IOPscience. Please...COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE The Strength Of PIN- PMN - PT Single Crystals Under Bending With A Longitudinal Electric Field... PMN ? PT ) single crystals was measured using a four point bending apparatus with a longitudinal electric field applied to the bar during bending. The

  3. Solar Cycle Variations of Sunspot Magnetic Field Strengths from the Mount Wilson Observatory

    NASA Astrophysics Data System (ADS)

    Pevtsov, Alexei A.; Bertello, L.; Tlatov, A.; Nagovitsyn, Y.; Kilcik, A.

    2012-05-01

    We used historical synoptic data the Mount Wilson Observatory (MWO) to study long-term changes in sunspot magnetic field strengths over the period of 1920-1959. By selecting sunspots with the strongest field strength for each observing day, we find that the average field strengths in sunspots vary with solar cycle with amplitude of a few hundred Gauss. The data show no statistically significant long-term trend over the period of about 40 years covered by these observations. We also find that the fractional distribution of sunspots changes from cycle to cycle. From Cycle 15 to Cycle 19, MWO data show a steady increase in fraction of sunspots with weaker field strengths (<1000 G), while the fraction of sunspots with strongest field strengths (>3000 G) steadily decreases. The fraction of sunspots with field strengths between 1000-3000 Gauss does not change in any systematic way. In contract, the fractional distribution of sunspots by their area (i.e., small, intermediate, and large) taken from the Greenwich observatory data set does not change during the same period of time. The different behavior in these two fractional distributions might indicate some physical changes in the properties of sunspots (e.g., sunspots of about the same area show progressively smaller field strengths), or it could be the result of some systematic instrumental/observational effects. We discuss our findings in the framework of these two possible explanations.

  4. Oscillator strength spectrum of hydrogen in strong magnetic and electric fields with arbitrary mutual orientation

    SciTech Connect

    Guan Xiaoxu

    2006-08-15

    We present oscillator strength spectra of the hydrogen Balmer {alpha} series in crossed strong magnetic and electric fields. Field strength regimes of interest ({gamma}{<=}0.02 a.u. and F{<=}1x10{sup 8} V/m) are the characteristic strengths observed on the surface of white dwarf stars. Based on the pseudospectral discretization technique, two independent methods have been developed to achieve reliable oscillator strengths in crossed fields. The effect of relative orientation between the magnetic and electric fields is clarified. Compared to the parallel configuration, we have observed that for the field strength regimes of interest, the perpendicular component of electric fields only results in a weaker coupling between the states belonging to the different subspaces of magnetic quantum numbers. This observation explains why the spectrum of oscillator strengths in crossed electric and magnetic fields with arbitrary mutual orientation shows similar behavior compared to that in parallel fields. However, a careful analysis shows that the two stronger transition lines at 5546 and 5620 A ring previously attributed to the Balmer {alpha} series are now identified to belong to the Balmer {beta} series. An effective scheme has also been suggested to calculate the bound-free opacities of hydrogen atoms in crossed fields.

  5. Radial dependence of HF wave field strength in the BPD column. [Beam Plasma Discharge

    NASA Technical Reports Server (NTRS)

    Jost, R. J.; Anderson, H. R.; Bernstein, W.; Kellogg, P. J.

    1982-01-01

    The results of a recent set of RF frequency measurements of the beam plasma discharge (BPD) performed in order to determine a quantitative value for the field strength in the plasma frequency region of the spectrum are presented. The parallel and perpendicular components of the plasma wave electric fields inside the BPD column have comparable field strengths, on the order of 10 volts/m. The radial dependence of the field strength is very strong, decreasing by as much as 40 dB within one meter from the beam center, with the illumination or discharge column approximately one meter in diameter. The field strength inside the column increases as a function of distance along the beam at least for several meters from the gun aperture. The frequency and amplitude of the plasma wave increases with beam current. A particularly rapid increase in these parameters occurs as the beam current approaches the critical current.

  6. STRENGTH PROPERTIES OF POLED PZT SUBJECTED TO BIAXIAL FLEXURAL LOADING IN HIGH ELECTRIC FIELD

    SciTech Connect

    Wang, Hong; Lin, Hua-Tay; Wereszczak, Andrew A

    2010-01-01

    Failure of poled PZT has been experimentally studied using ball-on-ring (BoR) biaxial flexure strength tests with an electric field concurrently applied. The as-received and aged PZTs were tested in high electric fields of -3 to 4 times the coercive field. Both the sign and the magnitude of electric field had a significant effect on the strength of poled PZT. A surface flaw type with a depth of around 18 m was identified as the strength limiter and responsible for the failure of the tested PZT. With a value of 0.76 MPa m1/2 in the open circle condition, the fracture toughness of the poled PZT was affected by an applied electric field just as the strength was affected. These results and observations have the potential to serve probabilistic reliability analysis and design optimization of multilayer PZT piezo actuators.

  7. Atomic hydrogen storage. [cryotrapping and magnetic field strength

    NASA Technical Reports Server (NTRS)

    Woollam, J. A. (Inventor)

    1980-01-01

    Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compound is maintained at liquid temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

  8. Probing High-Velocity Transient-Field Strength Using Heavy-ions Traversing Fe and Gd

    SciTech Connect

    Fiori, E.; Georgiev, G.; Cabaret, S.; Lozeva, R.; Jungclaus, A.; Modamio, V.; Walker, J.; Balabanski, D. L.; Blazhev, A.; Clement, E.; Grevy, S.; Stodel, C.; Thomas, J. C.; Danchev, M.; Daugas, J. M.; Hass, M.; Kumar, V.; Leske, J.; Pietralla, N.

    2009-08-26

    The transient field strength for {sup 76}Ge ions, passing through iron and gadolinium layers at velocities approxZv{sub 0}, has been measured. Although a sizeable value has been obtained for Gd, a vanishing strength has been observed in Fe.

  9. 47 CFR 5.87 - Frequencies for field strength surveys or equipment demonstrations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Frequencies for field strength surveys or equipment demonstrations. 5.87 Section 5.87 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... strength surveys or equipment demonstrations. (a) Authorizations issued under §§ 5.3 (e) and (f) of...

  10. Heliospheric magnetic field strength out to 66 AU: Voyager 1, 1978-1996

    NASA Astrophysics Data System (ADS)

    Burlaga, L. F.; Ness, N. F.; Wang, Y.-M.; Sheeley, N. R.

    1998-10-01

    We discuss Voyager 1 (V1) observations of the heliospheric magnetic field strength from 1978 through 1996. During this period the distance of V1 from the Sun increased from ~3 AU to 66 AU and its heliographic latitude increased from ~5°S to 33°N. The magnetic field strength profile observed by V1 is consistent with Parker's spiral field model when one considers (1) the solar cycle variation of the observed magnetic field strength at 1 AU, B1(t) (which is a measure of the source field strength) and (2) the latitudinal and solar cycle variations of the solar wind speed, V(t,θ). Both B1(t) and V(t,θ) make significant contributions to the variation of the magnetic field strength variations observed by V1. There is no evidence for a ``magnetic flux deficit'' increasing with distance from the Sun. There is a solar cycle variation of the magnetic field strength in the outer heliosphere, which will affect the modulation of cosmic rays.

  11. ON A POSSIBLE EXPLANATION OF THE LONG-TERM DECREASE IN SUNSPOT FIELD STRENGTH

    SciTech Connect

    Nagovitsyn, Yury A.; Pevtsov, Alexei A.; Livingston, William C. E-mail: apevtsov@nso.edu

    2012-10-10

    Recent studies revealed a controversy in long-term variations in sunspot field strengths. On one hand, the sunspot field strengths computed by averaging both large and small sunspots and pores show a gradual decrease over the declining phase of solar Cycle 23 and the rising phase of Cycle 24. On the other hand, the strongest sunspot field strengths demonstrate only solar cycle variations with no long-term decline. Here, we investigate the field strength and area properties of sunspots in an attempt to reconcile the presence of both tendencies in recent sunspot field strength measurements. First, we analyze the data set from Penn and Livingston, and we show that in addition to the previously reported long-term decline, the data show the solar cycle variation when only sunspots with the strongest magnetic fields are included. Next, we investigate the variations in the number of sunspots of different sizes, and we find a negative correlation between the numbers of small and large sunspots. Finally, we show that during the period of 1998-2011, the number of large sunspots gradually decreased, while the number of small sunspots steadily increased. We suggest that this change in the fraction of small and large sunspots (perhaps, due to changes in the solar dynamo) can explain the gradual decline in average sunspot field strength as observed by Penn and Livingston.

  12. Oscillator strength sum rules with an external electromagnetic field

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Sabin, John R.; Öhrn, Yngve; Oddershede, J.

    1998-04-01

    We demonstrate that the Bethe, and therefore the Thomas-Reiche-Kuhn, sum rule is unaffected by the presence of an applied external electromagnetic field in the exact case. We use the consequence that the first-order perturbation contribution must also vanish to derive a necessary condition for the completeness of computational one-electron basis sets.

  13. PUTTING CORONAL SEISMOLOGY ESTIMATES OF THE MAGNETIC FIELD STRENGTH TO THE TEST

    SciTech Connect

    De Moortel, I.; Pascoe, D. J.

    2009-07-10

    The magnetic field strength inside a model coronal loop is 'estimated' using coronal seismology, to examine the reliability of magnetic field strengths derived from observed, transverse coronal loop oscillations. Three-dimensional numerical simulations of the interaction of an external pressure pulse with a coronal loop (modeled as a three-dimensional density enhancement inside a two-dimensional magnetic arcade) are analyzed and the 'observed' properties of the excited transverse loop oscillations are used to derive the value of the local magnetic field strength, following the method of Nakariakov and Ofman. Due to the (unexpected) change in periodicity, the magnetic field derived from our 'observed' oscillation is substantially different from the actual (input) magnetic field value (approximately 50%). Coronal seismology can derive useful information about the local magnetic field, but the combined effect of the loop curvature, the density ratio, and aspect ratio of the loop appears to be more important than previously expected.

  14. Study on technology of high-frequency pulsed magnetic field strength measurement.

    PubMed

    Chen, Yi-Mei; Liu, Zhi-Peng; Yin, Tao

    2012-01-01

    High-frequency transient weak magnetic field is always involved in researches about biomedical engineering field while common magnetic-field sensors cannot work properly at frequencies as high as MHz. To measure the value of MHz-level weak pulsed magnetic-field strength accurately, this paper designs a measurement and calibration method for pulsed magnetic-field. In this paper, a device made of Nonferromagnetic material was independently designed and applied to pulsed magnetic field measurement. It held an accurately relative position between the magnetic field generating coil and the detecting coil. By applying a sinusoidal pulse to the generator, collecting the induced electromotive force of the detector, the final magnetic field strength was worked out through algorithms written in Matlab according to Faraday's Law. Experiments were carried out for measurement and calibration. Experiments showed that, under good stability and consistency, accurate measurement of magnetic-field strength of a sinepulse magnetic-field can be achieved, with frequency at 0.5, 1, 1.5 MHz and strength level at micro-Tesla. Calibration results carried out a measuring relative error about 2.5%.

  15. Tidal dissipation and the strength of the Earth's internal magnetic field.

    PubMed

    Buffett, Bruce A

    2010-12-16

    Magnetic fields at the Earth's surface represent only a fraction of the field inside the core. The strength and structure of the internal field are poorly known, yet the details are important for our understanding of the geodynamo. Here I obtain an indirect estimate for the field strength from measurements of tidal dissipation. Tidally driven flow in the Earth's liquid core develops internal shear layers, which distort the internal magnetic field and generate electric currents. Ohmic losses damp the tidal motions and produce detectable signatures in the Earth's nutations. Previously reported evidence of anomalous dissipation in nutations can be explained with a core-averaged field of 2.5 mT, eliminating the need for high fluid viscosity or a stronger magnetic field at the inner-core boundary. Estimates for the internal field constrain the power required for the geodynamo.

  16. Electric field strength determination in filamentary DBDs by CARS-based four-wave mixing

    NASA Astrophysics Data System (ADS)

    Boehm, Patrick; Kettlitz, Manfred; Brandenburg, Ronny; Hoeft, Hans; Czarnetzki, Uwe

    2016-09-01

    The electric field strength is a basic parameter of non-thermal plasmas. Therefore, a profound knowledge of the electric field distribution is crucial. In this contribution a four wave mixing technique based on Coherent Anti-Stokes Raman spectroscopy (CARS) is used to measure electric field strengths in filamentary dielectric barrier discharges (DBDs). The discharges are operated with a pulsed voltage in nitrogen at atmospheric pressure. Small amounts hydrogen (10 vol%) are admixed as tracer gas to evaluate the electric field strength in the 1 mm discharge gap. Absolute values of the electric field strength are determined by calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. Alteration of the electric field strength has been observed during the internal polarity reversal and the breakdown process. In this case the major advantage over emission based methods is that this technique can be used independently from emission, e.g. in the pre-phase and in between two consecutive, opposite discharge pulses where no emission occurs at all. This work was supported by the Deutsche Forschungsgemeinschaft, Forschergruppe FOR 1123 and Sonderforschungsbereich TRR 24 ``Fundamentals of complex plasmas''.

  17. EFFECTS OF MAGNETIC FIELD STRENGTH AND ORIENTATION ON MOLECULAR CLOUD FORMATION

    SciTech Connect

    Heitsch, Fabian; Hartmann, Lee W.; Stone, James M.

    2009-04-10

    We present a set of numerical simulations addressing the effects of magnetic field strength and orientation on the flow-driven formation of molecular clouds. Fields perpendicular to the flows sweeping up the cloud can efficiently prevent the formation of massive clouds but permit the buildup of cold, diffuse filaments. Fields aligned with the flows lead to substantial clouds, whose degree of fragmentation and turbulence strongly depends on the background field strength. Adding a random field component leads to a 'selection effect' for molecular cloud formation: high column densities are only reached at locations where the field component perpendicular to the flows is vanishing. Searching for signatures of colliding flows should focus on the diffuse, warm gas, since the cold gas phase making up the cloud will have lost the information about the original flow direction because the magnetic fields redistribute the kinetic energy of the inflows.

  18. 47 CFR 73.189 - Minimum antenna heights or field strength requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Minimum antenna heights or field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.189 Minimum antenna heights or field..., frequency, or transmitter location must also request authority to install a new antenna system or to...

  19. 47 CFR 73.189 - Minimum antenna heights or field strength requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Minimum antenna heights or field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.189 Minimum antenna heights or field..., frequency, or transmitter location must also request authority to install a new antenna system or to...

  20. 47 CFR 73.189 - Minimum antenna heights or field strength requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Minimum antenna heights or field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.189 Minimum antenna heights or field..., frequency, or transmitter location must also request authority to install a new antenna system or to...

  1. 47 CFR 73.189 - Minimum antenna heights or field strength requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Minimum antenna heights or field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.189 Minimum antenna heights or field..., frequency, or transmitter location must also request authority to install a new antenna system or to...

  2. 47 CFR 73.189 - Minimum antenna heights or field strength requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Minimum antenna heights or field strength... RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.189 Minimum antenna heights or field..., frequency, or transmitter location must also request authority to install a new antenna system or to...

  3. Technique for Predicting the Radio Frequency Field Strength Inside an Enclosure

    NASA Technical Reports Server (NTRS)

    Hallett, Michael P.; Reddell, Jerry P.

    1997-01-01

    This technical memo represents a simple analytical technique for predicting the Radio Frequency (RF) field inside an enclosed volume in which radio frequency occurs. The technique was developed to predict the RF field strength within a launch vehicle fairing in which some payloads desire to launch with their telemetry transmitter radiating. This technique considers both the launch vehicle and the payload aspects.

  4. Dependence of Brownian and Néel relaxation times on magnetic field strength

    SciTech Connect

    Deissler, Robert J. Wu, Yong; Martens, Michael A.

    2014-01-15

    Purpose: In magnetic particle imaging (MPI) and magnetic particle spectroscopy (MPS) the relaxation time of the magnetization in response to externally applied magnetic fields is determined by the Brownian and Néel relaxation mechanisms. Here the authors investigate the dependence of the relaxation times on the magnetic field strength and the implications for MPI and MPS. Methods: The Fokker–Planck equation with Brownian relaxation and the Fokker–Planck equation with Néel relaxation are solved numerically for a time-varying externally applied magnetic field, including a step-function, a sinusoidally varying, and a linearly ramped magnetic field. For magnetic fields that are applied as a step function, an eigenvalue approach is used to directly calculate both the Brownian and Néel relaxation times for a range of magnetic field strengths. For Néel relaxation, the eigenvalue calculations are compared to Brown's high-barrier approximation formula. Results: The relaxation times due to the Brownian or Néel mechanisms depend on the magnitude of the applied magnetic field. In particular, the Néel relaxation time is sensitive to the magnetic field strength, and varies by many orders of magnitude for nanoparticle properties and magnetic field strengths relevant for MPI and MPS. Therefore, the well-known zero-field relaxation times underestimate the actual relaxation times and, in particular, can underestimate the Néel relaxation time by many orders of magnitude. When only Néel relaxation is present—if the particles are embedded in a solid for instance—the authors found that there can be a strong magnetization response to a sinusoidal driving field, even if the period is much less than the zero-field relaxation time. For a ferrofluid in which both Brownian and Néel relaxation are present, only one relaxation mechanism may dominate depending on the magnetic field strength, the driving frequency (or ramp time), and the phase of the magnetization relative to the

  5. Single-step electrical field strength screening to determine electroporation induced transmembrane transport parameters.

    PubMed

    Blumrosen, Gadi; Abazari, Alireza; Golberg, Alexander; Yarmush, Martin L; Toner, Mehmet

    2016-09-01

    The design of effective electroporation protocols for molecular delivery applications requires the determination of transport parameters including diffusion coefficient, membrane resealing, and critical electric field strength for electroporation. The use of existing technologies to determine these parameters is time-consuming and labor-intensive, and often results in large inconsistencies in parameter estimation due to variations in the protocols and setups. In this work, we suggest using a set of concentric electrodes to screen a full range of electric field strengths in a single test to determine the electroporation-induced transmembrane transport parameters. Using Calcein as a fluorescent probe, we developed analytical methodology to determine the transport parameters based on the electroporation-induced pattern of fluorescence loss from cells. A monolayer of normal human dermal fibroblast (NHDF) cells were pre-loaded with Calcein and electroporated with an applied voltage of 750V with 10 and 50 square pulses with 50μs duration. Using our analytical model, the critical electric field strength for electroporation was found for the 10 and 50 pulses experiments. An inverse correlation between the field strength and the molecular transport time decay constant, and a direct correlation between field strength and the membrane permeability were observed. The results of this work can simplify the development of electroporation-assisted technologies for research and therapies.

  6. Electrokinetic transport of aerobic microorganisms under low-strength electric fields.

    PubMed

    Maillacheruvu, Krishnanand Y; Chinchoud, Preethi R

    2011-01-01

    To investigate the feasibility of utilizing low strength electric fields to transport commonly available mixed cultures such as those from an activated sludge process, bench scale batch reactor studies were conducted in sand and sandy loam soils. A readily biodegradable substrate, dextrose, was used to test the activity of the transported microorganisms. Electric field strengths of 7V, 10.5V, and 14V were used. Results from this investigation showed that an electric field strength of 0.46 Volts per cm was sufficient to transport activated sludge microorganisms across a sandy loam soil across a distance of about 8 cm in 72 h. More importantly, the electrokinetically transported microbial culture remained active and viable after the transport process and was biodegrade 44% of the dextrose in the soil medium. Electrokinetic treatment without microorganisms resulted in removal of 37% and the absence of any treatment yielded a removal of about 15%.

  7. Registration of weak ULF/ELF oscillations of the surface electric field strength

    NASA Astrophysics Data System (ADS)

    Boldyrev, A. I.; Vyazilov, A. E.; Ivanov, V. N.; Kemaev, R. V.; Korovin, V. Ya.; Melyashinskii, A. V.; Pamukhin, K. V.; Panov, V. N.; Shvyrev, Yu. N.

    2016-07-01

    Measurements of the atmospheric electric field strength made by an electrostatic fluxmeter with a unique threshold sensitivity for such devices (6 × 10-2-10-3 V m-1 Hz-1/2 in the 10-3-25 Hz frequency range) and wide dynamic (120 dB) and spectral (0-25 Hz) ranges, are presented. The device parameters make it possible to observe the electric component of global electromagnetic Schumann resonances and long-period fluctuations in the atmospheric electric field strength.

  8. First application of proton reflection magnetometry with MESSENGER to estimate Mercury's surface magnetic field strength (Invited)

    NASA Astrophysics Data System (ADS)

    Winslow, R. M.; Johnson, C. L.; Anderson, B. J.; Gershman, D. J.; Raines, J. M.; Lillis, R. J.; Korth, H.; Slavin, J. A.; Solomon, S. C.

    2013-12-01

    We present the first use of proton reflection magnetometry, a novel adaptation of electron reflectometry, to estimate Mercury's surface field strength. We use measurements of protons by MESSENGER's Fast Imaging Plasma Spectrometer (FIPS) in 8-s integration times. Because of the limited field of view of FIPS, we average pitch-angle distributions by accumulating proton data from multiple integration periods and orbits over selected geographical regions. Proton loss cones are evident in both the northern hemisphere cusp region as well as on the nightside at low latitudes in the southern hemisphere. The existence of the loss cones provides confirmation of proton precipitation to the surface in these regions. The loss cone pitch-angle cut-offs are gradual rather than sharp, which we attribute in part to wave-particle scattering causing pitch-angle diffusion. Fitting diffusion curves to the pitch-angle distributions yields estimates of both the cut-off pitch angle, αc, and an average Dαt, where Dα is the pitch-angle diffusion coefficient and t is the diffusion time. The in-situ magnetic field together with αc provide an estimate of the surface magnetic field strength. The results are within 10% of a magnetospheric model for the surface field at the mapped surface locations, but are systematically lower than the model predictions. This discrepancy is consistent with the presence of near-surface plasma, which locally lowers the actual total magnetic field at the surface but is not included in the vacuum-field magnetospheric model. As consistency checks, we have confirmed that the loss cone size decreases with increasing altitude and that the surface magnetic field strength increases with increasing latitude. Our results confirm the offset dipole structure at the surface and demonstrate that proton reflection magnetometry is a practical method for inferring the surface magnetic field strength at Mercury. Further observations may resolve regional-scale structure in the

  9. Effect of muscle contraction strength on gating of somatosensory magnetic fields.

    PubMed

    Sugawara, Kazuhiro; Onishi, Hideaki; Yamashiro, Koya; Kotan, Shinichi; Kojima, Sho; Miyaguchi, Shota; Tsubaki, Atsuhiro; Kirimoto, Hikari; Tamaki, Hiroyuki; Shirozu, Hiroshi; Kameyama, Shigeki

    2016-11-01

    Afferent somatosensory information is modulated before the afferent input arrives at the primary somatosensory cortex during voluntary movement. The aim of the present study was to clarify the effect of muscular contraction strength on somatosensory evoked fields (SEFs) during voluntary movement. In addition, we examined the differences in gating between innervated and non-innervated muscle during contraction. We investigated the changes in gating effect by muscular contraction strength and innervated and non-innervated muscles in human using 306-channel magnetoencephalography. SEFs were recorded following the right median nerve stimulation in a resting condition and during isometric muscular contractions from 10 % electromyographic activity (EMG), 20 and 30 % EMG of the right extensor indicis muscle and abductor pollicis brevis muscle. Our results showed that the equivalent current dipole (ECD) strength for P35m decreased with increasing strength of muscular contraction of the right abductor pollicis brevis muscle. However, changes were observed only at 30 % EMG contraction level of the right extensor indicis muscle, which was not innervated by the median nerve. There were no significant changes in the peak latencies and ECD locations of each component in all conditions. The ECD strength did not differ significantly for N20m and P60m regardless of the strength of muscular contraction and innervation. Therefore, we suggest that the gating of SEF waveforms following peripheral nerve stimulation was affected by the strength of muscular contraction and innervation of the contracting muscle.

  10. Lower-extremity strength ratios of professional soccer players according to field position.

    PubMed

    Ruas, Cassio V; Minozzo, Felipe; Pinto, Matheus D; Brown, Lee E; Pinto, Ronei S

    2015-05-01

    Previous investigators have proposed that knee strength, hamstrings to quadriceps, and side-to-side asymmetries may vary according to soccer field positions. However, different results have been found in these variables, and a generalization of this topic could lead to data misinterpretation by coaches and soccer clubs. Thus, the aim of this study was to measure knee strength and asymmetry in soccer players across different field positions. One hundred and two male professional soccer players performed maximal concentric and eccentric isokinetic knee actions on the preferred and nonpreferred legs at a velocity of 60° · s. Players were divided into their field positions for analysis: goalkeepers, side backs, central backs, central defender midfielders, central attacking midfielders, and forwards. Results demonstrated that only goalkeepers (GK) differed from most other field positions on players' characteristics, and concentric peak torque across muscles. Although all players presented functional ratios of the preferred (0.79 ± 0.14) and nonpreferred (0.75 ± 0.13) legs below accepted normative values, there were no differences between positions for conventional or functional strength ratios or side-to-side asymmetry. The same comparisons were made only between field players, without inclusion of the GK, and no differences were found between positions. Therefore, the hamstrings to quadriceps and side-to-side asymmetries found here may reflect knee strength functional balance required for soccer skills performance and game demands across field positions. These results also suggest that isokinetic strength profiles should be considered differently in GK compared with other field positions due to their specific physiological and training characteristics.

  11. THEORETICAL LIMITS ON MAGNETIC FIELD STRENGTHS IN LOW-MASS STARS

    SciTech Connect

    Browning, Matthew K.; Weber, Maria A.; Chabrier, Gilles; Massey, Angela P.

    2016-02-20

    Observations have suggested that some low-mass stars have larger radii than predicted by 1D structure models. Some theoretical models have invoked very strong interior magnetic fields (of order 1 MG or more) as a possible cause of such large radii. Whether fields of that strength could in principle be generated by dynamo action in these objects is unclear, and we do not address the matter directly. Instead, we examine whether such fields could remain in the interior of a low-mass object for a significant amount of time, and whether they would have any other obvious signatures. First, we estimate the timescales for the loss of strong fields by magnetic buoyancy instabilities. We consider a range of field strengths and simple morphologies, including both idealized flux tubes and smooth layers of field. We confirm some of our analytical estimates using thin flux tube magnetohydrodynamic simulations of the rise of buoyant fields in a fully convective M-dwarf. Separately, we consider the Ohmic dissipation of such fields. We find that dissipation provides a complementary constraint to buoyancy: while small-scale, fibril fields might be regenerated faster than they rise, the dissipative heating associated with such fields would in some cases greatly exceed the luminosity of the star. We show how these constraints combine to yield limits on the internal field strength and morphology in low-mass stars. In particular, we find that for stars of 0.3 solar masses, no fields in flux tubes stronger than about 800 kG are simultaneously consistent with both constraints.

  12. Resolution of high molecular weight proteins in dependence on electric field strength in polyacrylamide gel electrophoresis.

    PubMed

    Starita-Geribaldi, M; Houri, A

    1997-01-01

    Resolution of high molecular weight proteins, in the upper region of polyacrylamide gels, was studied in relation to the type of electric field. Separations by constant field gel electrophoresis (CFGE) were compared to those in pulsed oscillatory high-performance electrophoresis (POPE), a novel technique which allows electrophoresis at high field strengths owing to a novel local field distribution. This distribution contributes to structural and mechanical stability of the gel with resultant well-reproducible separation, enhanced resolution, and higher absolute mobility of proteins in POPE.

  13. 47 CFR 90.359 - Field strength limits for EA-licensed LMS systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Field strength limits for EA-licensed LMS systems. 90.359 Section 90.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio...

  14. NEW APPROACHES: Magnetic and electric field strengths of high voltage power lines and household appliances

    NASA Astrophysics Data System (ADS)

    Austin, Lydia

    1997-03-01

    A readily obtainable meter can be used to measure the magnetic and electric field strengths of high voltage power lines and household appliances. Simple calculations show that all likely exposures are below, mostly well below, the maximum exposures recommended by the World Health Organisation.

  15. ELF (Extremely Low Frequency) PVS (Propagation Validation System) Field Strength Measurements, March 1977.

    DTIC Science & Technology

    1983-02-03

    field-strength measurements were taken in Connecticut and aboard three submarines located in the North-Atlantic/Norwegian- Sea area. The daytime...Develco, Inc., 404 Tasman Dr. Sunnyvale, CA 94086 Dr. Eivind Trane, NDRE, P.O. Box 25, 2007 Kjeller, Norway RCA David Sarnoff Research Center (K

  16. 47 CFR 90.359 - Field strength limits for EA-licensed LMS systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... systems. 90.359 Section 90.359 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.359 Field strength limits for EA-licensed LMS systems. EA-licensed multilateration systems...

  17. Constraining regular and turbulent magnetic field strengths in M 51 via Faraday depolarization

    NASA Astrophysics Data System (ADS)

    Shneider, C.; Haverkorn, M.; Fletcher, A.; Shukurov, A.

    2014-08-01

    We employ an analytical model that incorporates both wavelength-dependent and wavelength-independent depolarization to describe radio polarimetric observations of polarization at λλλ 3.5,6.2,20.5 cm in M 51 (NGC 5194). The aim is to constrain both the regular and turbulent magnetic field strengths in the disk and halo, modeled as a two- or three-layer magneto-ionic medium, via differential Faraday rotation and internal Faraday dispersion, along with wavelength-independent depolarization arising from turbulent magnetic fields. A reduced chi-squared analysis is used for the statistical comparison of predicted to observed polarization maps to determine the best-fit magnetic field configuration at each of four radial rings spanning 2.4 - 7.2 kpc in 1.2 kpc increments. We find that a two-layer modeling approach provides a better fit to the observations than a three-layer model, where the near and far sides of the halo are taken to be identical, although the resulting best-fit magnetic field strengths are comparable. This implies that all of the signal from the far halo is depolarized at these wavelengths. We find a total magnetic field in the disk of approximately 18 μG and a total magnetic field strength in the halo of ~4-6 μG. Both turbulent and regular magnetic field strengths in the disk exceed those in the halo by a factor of a few. About half of the turbulent magnetic field in the disk is anisotropic, but in the halo all turbulence is only isotropic.

  18. Estimating the daytime Equatorial Ionization Anomaly strength from electric field proxies

    NASA Astrophysics Data System (ADS)

    Stolle, C.; Manoj, C.; Lühr, H.; Maus, S.; Alken, P.

    2008-09-01

    The Equatorial Ionization Anomaly (EIA) is a significant feature of the low-latitude ionosphere. During daytime, the eastward electric field drives a vertical plasma fountain at the magnetic equator creating the EIA. Since the eastward electric field is also the driving force for the Equatorial Electrojet (EEJ), the latter is positively correlated with the EIA strength. We investigate the correlation between the zonal electric field and the EIA in the Peruvian sector and compare the results with correlations of the EEJ versus EIA strength. Analyzing 5 years of Challenging Minisatellite Payload (CHAMP) electron density measurements, plasma drift readings from the Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere (JULIA) radar, and magnetic field observations at Huancayo and Piura, we find the EEJ strength and the zonal electric field to be suitable proxies for the EIA intensity. Both analyses reveal high correlation coefficients of cc > 0.8. A typical response time of the EIA to variations in the zonal electric field is ˜1-2 h, and it is ˜2-4 h after EEJ strength variations. Quantitative expressions are provided, which directly relate the EIA parameters to both proxies. From these relations, we infer that an EIA develops also during weak Counter Electrojets (CEJs), but no EIA forms when the vertical plasma drift is zero. For positive EEJ magnetic signatures to form, a minimum eastward electric field of 0.2 mV/m is required on average. The above-mentioned delay between EIA and EEJ variations of ˜3 h is further confirmed by the investigation of the EIA response to transitions from CEJ to EEJ, e.g., during late morning hours.

  19. White-light corona and solar polar magnetic field strength over solar cycles

    NASA Astrophysics Data System (ADS)

    Rušin, V.; Saniga, M.; Komžík, R.

    2014-10-01

    We discuss the large-scale structure of the solar corona, in particular its helmet streamers, as observed during total solar eclipses around maxima of solar cycles and make its comparison with solar polar magnetic field strength as observed by the Wilcox Solar Observatory (WSO) since 1976. Even though the magnetic field strength at the solar poles around cycle minima decreased minimally twice in the last forty years, distributions of helmet streamers around the Sun in different cycles around cycle maxima remain nearly the same. This indicates that large-scale magnetic structures governing the shape and evolution of helmet streamers must be of a different nature than those related with solar polar fields.

  20. Dust Grain Alignment and Magnetic Field Strength in the Wall of the Local Bubble

    NASA Astrophysics Data System (ADS)

    Andersson, B.-G.; Medan, Ilija

    2017-01-01

    We use archival data on polarization (Berdyugin 2014) and extinction in the wall of the Local Bubble to study the grain alignment efficiency and the magnetic field strength. We find that the grain alignment efficiency variations can be directly tied to the location of the known OB-associations within 200pc from the Sun, strongly supporting modern, radiation-driven dust grain alignment. Based on the Davis-Chandrasekhar-Fermi method, we find a bimodal magnetic field-strength distribution, where the locations of the strongest fields correlate with the directions towards the near-by OB associations. We hypothesize that this strengthening is due to compression of the bubble wall by the opposing outflows in the Local Bubble and from the surrounding OB associations.

  1. MAGNETIC BRAKING FORMULATION FOR SUN-LIKE STARS: DEPENDENCE ON DIPOLE FIELD STRENGTH AND ROTATION RATE

    SciTech Connect

    Matt, Sean P.; Pinsonneault, Marc H.; Greene, Thomas P. E-mail: kmac@ucar.edu E-mail: thomas.p.greene@nasa.gov

    2012-08-01

    We use two-dimensional axisymmetric magnetohydrodynamic simulations to compute steady-state solutions for solar-like stellar winds from rotating stars with dipolar magnetic fields. Our parameter study includes 50 simulations covering a wide range of relative magnetic field strengths and rotation rates, extending from the slow- and approaching the fast-magnetic-rotator regimes. Using the simulations to compute the angular momentum loss, we derive a semi-analytic formulation for the external torque on the star that fits all of the simulations to a precision of a few percent. This formula provides a simple method for computing the magnetic braking of Sun-like stars due to magnetized stellar winds, which properly includes the dependence on the strength of the magnetic field, mass loss rate, stellar radius, surface gravity, and spin rate, and which is valid for both slow and fast rotators.

  2. A new estimate of average dipole field strength for the last five million years

    NASA Astrophysics Data System (ADS)

    Cromwell, G.; Tauxe, L.; Halldorsson, S. A.

    2013-12-01

    The Earth's ancient magnetic field can be approximated by a geocentric axial dipole (GAD) where the average field intensity is twice as strong at the poles than at the equator. The present day geomagnetic field, and some global paleointensity datasets, support the GAD hypothesis with a virtual axial dipole moment (VADM) of about 80 ZAm2. Significant departures from GAD for 0-5 Ma are found in Antarctica and Iceland where paleointensity experiments on massive flows (Antarctica) (1) and volcanic glasses (Iceland) produce average VADM estimates of 41.4 ZAm2 and 59.5 ZAm2, respectively. These combined intensities are much closer to a lower estimate for long-term dipole field strength, 50 ZAm2 (2), and some other estimates of average VADM based on paleointensities strictly from volcanic glasses. Proposed explanations for the observed non-GAD behavior, from otherwise high-quality paleointensity results, include incomplete temporal sampling, effects from the tangent cylinder, and hemispheric asymmetry. Differences in estimates of average magnetic field strength likely arise from inconsistent selection protocols and experiment methodologies. We address these possible biases and estimate the average dipole field strength for the last five million years by compiling measurement level data of IZZI-modified paleointensity experiments from lava flows around the globe (including new results from Iceland and the HSDP-2 Hawaii drill core). We use the Thellier Gui paleointensity interpreter (3) in order to apply objective criteria to all specimens, ensuring consistency between sites. Specimen level selection criteria are determined from a recent paleointensity investigation of modern Hawaiian lava flows where the expected magnetic field strength was accurately recovered when following certain selection parameters. Our new estimate of average dipole field strength for the last five million years incorporates multiple paleointensity studies on lava flows with diverse global and

  3. Consistency restrictions on maximal electric-field strength in quantum field theory.

    PubMed

    Gavrilov, S P; Gitman, D M

    2008-09-26

    Quantum field theory with an external background can be considered as a consistent model only if backreaction is relatively small with respect to the background. To find the corresponding consistency restrictions on an external electric field and its duration in QED and QCD, we analyze the mean-energy density of quantized fields for an arbitrary constant electric field E, acting during a large but finite time T. Using the corresponding asymptotics with respect to the dimensionless parameter eET2, one can see that the leading contributions to the energy are due to the creation of particles by the electric field. Assuming that these contributions are small in comparison with the energy density of the electric background, we establish the above-mentioned restrictions, which determine, in fact, the time scales from above of depletion of an electric field due to the backreaction.

  4. ARE THERE DIFFERENCES IN STRENGTH TESTS USING ISOKINETIC DYNAMOMETRY BETWEEN FIELD AND INDOOR PROFESSIONAL SOCCER PLAYERS?

    PubMed Central

    de Aguiar Leonardi, Adriano Barros; Martinelli, Mauro Olivio; Junior, Aires Duarte

    2015-01-01

    Objective: The objective of this study was to conduct a comparative analysis on isokinetic strength assessments between field and indoor male professional soccer players and correlate the findings with the higher levels of injury risk described in the literature. Methods: We analyzed 16 field soccer players and 15 indoor soccer players. All these professionals were male. Isokinetic muscle strength assessments were made on their knees. Results: The mean weight was 81.81 kg for field soccer and 80.33 kg for indoor soccer. The right and left peak extensor torque left and right for field soccer and indoor soccer were, respectively, 302.50 and 313.31 Nm and 265.20 and 279.80 Nm, and for flexors, 178 and 184.88 Nm and 158.27 and 154 Nm. The peak torque rates according to body weight for the left and right extensors for field soccer and indoor soccer were, respectively, 3.84 and 3.7 Nm/kg and 3.32 and 3.52 Nm/kg, and for flexors, 2.17 and 2.26 Nm/kg and 1.98 and 1.93 Nm/kg. The balance relationships between flexors and extensors on the right and left sides for field soccer and indoor soccer were, respectively, 59.81 and 59.44% and 60.47% and 54.80%. The relationships for extensors between the right and left sides for field soccer and indoor soccer were, respectively, 11.44 and 9.20%, and for the flexors, 7.31 and 8.80%. Conclusions: In accordance with international parameters, comparative analysis on isokinetic strength assessments between field and indoor male professional soccer players before the season showed that there was muscle balance and low probability of injury. There were no statistically significant differences in the parameters analyzed between the players of the two types of soccer. PMID:27042649

  5. Galactic magnetic field strengths, from three different methods - a cautionary note.

    NASA Astrophysics Data System (ADS)

    Vallee, J. P.

    1995-04-01

    Recent cosmic-ray data have led to the suggestion that the magnetic field B in late-type galaxies may be quite large, i.e. B>3B_eq_, where B_ eq_ is the magnetic field derived from the equipartition method (e.g., Chi & Wolfendale 1993; Zweibel 1993). Previous radio data had led to the claim that the magnetic field B in late-type galaxies was close to B_eq_, i.e. 0.3B_eq_field B is far or close to B_eq_. Here, a statistical study is carried out of the three methods often employed to give magnetic field strengths, namely (i) the Faraday rotation method, (ii) the Equipartition method, and (iii) the Cosmic-ray particle method. I use statistics with small observational samples to find that two independent methods (Faraday rotation B_fa_ and Equipartition B_eq_) are converging on similar values of the magnetic field strength. For the available observational data, I find on average that 1.0B_eq_field B=~B_fa_=~B_eq_. The third method (cosmic-ray particle B_cr_) appears at times to predict magnetic field strengths different than those of the other two methods. Thus a caution is in order; possible reasons for that divergence are discussed.

  6. Effect of carrier ionic strength in microscale cyclical electrical field-flow fractionation.

    PubMed

    Kantak, Ameya S; Srinivas, Merugu; Gale, Bruce K

    2006-04-15

    Recent work with cyclical electrical field-flow fractionation systems has shown promise for the technique as a separation and analysis tool, but little is understood about how the carrier composition in the system affects its capabilities. The electrical properties of microscale CyElFFF systems change when the carrier ionic conditions are altered, and it is well known that the effects of increasing ionic strength carriers on retention in normal ElFFF systems are severe. Specifically, retention levels fall significantly. Accordingly, this work seeks to understand the effect that increasing carrier ionic strength in CyElFFF has on nanoparticle retention in the channels. The retention of polystyrene particles in the CyElFFF microsystem is reported at various ionic strengths of ammonium carbonate and at a variety of pH levels. The experiments are compared to the theory of CyElFFF available in the literature. The results indicate that the ionic strength of the carrier has a significant impact on retention and that high ionic strength carrier solutions lead to poor performance of the CyElFFF system. These results have significant impact on the possible uses of the technique and its applications, especially in the biomedical arena.

  7. Electromagnetic field strength prediction in an urban environment: A useful tool for the planning of LMSS

    NASA Technical Reports Server (NTRS)

    Vandooren, G. A. J.; Herben, M. H. A. J.; Brussaard, G.; Sforza, M.; Poiaresbaptista, J. P. V.

    1993-01-01

    A model for the prediction of the electromagnetic field strength in an urban environment is presented. The ray model, that is based on the Uniform Theory of Diffraction (UTD), includes effects of the non-perfect conductivity of the obstacles and their surface roughness. The urban environment is transformed into a list of standardized obstacles that have various shapes and material properties. The model is capable of accurately predicting the field strength in the urban environment by calculating different types of wave contributions such as reflected, edge and corner diffracted waves, and combinations thereof. Also, antenna weight functions are introduced to simulate the spatial filtering by the mobile antenna. Communication channel parameters such as signal fading, time delay profiles, Doppler shifts and delay-Doppler spectra can be derived from the ray-tracing procedure using post-processing routines. The model has been tested against results from scaled measurements at 50 GHz and proves to be accurate.

  8. [The role of low-field strength magnetic resonance imaging in bladder cancer staging].

    PubMed

    Lutsenko, P E; Bulanova, T V; Chernyshev, I V; Churaiants, V V

    2007-01-01

    This article shows the role of magnetic resonance imaging (MRI) in complex diagnostics of urinary bladder cancer. The paper analyzes the authors' own data of urinary bladder MRI in 40 patients with histologically proven bladder cancer. This study demonstrates the additional capacities of low-field strength MRI with enhanced technique including conventional T1-, T2-weighted images along with FLAIR and PD images.

  9. H:Q Ratios and Bilateral Leg Strength in College Field and Court Sports Players

    PubMed Central

    Cheung, Roy T.H.; Smith, Andrew W.; Wong, Del P.

    2012-01-01

    One of the key components in sports injury prevention is the identification of imbalances in leg muscle strength. However, different leg muscle characteristics may occur in large playing area (field) sports and small playing area (court) sports, which should be considered in regular injury prevention assessment. This study examined the isokinetic hamstrings-to-quadriceps (H:Q) ratio and bilateral leg strength balance in 40 male college (age: 23.4 ± 2.5 yrs) team sport players (field sport = 23, soccer players; court sport = 17, volleyball and basketball players). Five repetitions of maximal knee concentric flexion and concentric extension were performed on an isokinetic dynamometer at two speeds (slow: 60°·s−1 and fast: 300°·s−1) with 3 minutes rest between tests. Both legs were measured in counterbalanced order with the dominant leg being determined as the leg used to kick a ball. The highest concentric peak torque values (Nm) of the hamstrings and quadriceps of each leg were analyzed after body mass normalization (Nm·kg−1). Court sport players showed significantly weaker dominant leg hamstrings muscles at both contraction speeds (P < 0.05). The H:Q ratio was significantly larger in field players in their dominant leg at 60°·s−1 (P < 0.001), and their non-dominant leg at 300°·s−1 (P < 0.001) respectively. Sport-specific leg muscle strength was evident in college players from field and court sports. These results suggest the need for different muscle strength training and rehabilitation protocols for college players according to the musculature requirements in their respective sports. PMID:23487043

  10. Magnetic field strength influence on the reactive magnetron sputter deposition of Ta2O5

    NASA Astrophysics Data System (ADS)

    Hollerweger, R.; Holec, D.; Paulitsch, J.; Rachbauer, R.; Polcik, P.; Mayrhofer, P. H.

    2013-08-01

    Reactive magnetron sputtering enables the deposition of various thin films to be used for protective as well as optical and electronic applications. However, progressing target erosion during sputtering results in increased magnetic field strengths at the target surface. Consequently, the glow discharge, the target poisoning, and hence the morphology, crystal structure and stoichiometry of the prepared thin films are influenced. Therefore, these effects were investigated by varying the cathode current Im between 0.50 and 1.00 A, the magnetic field strength B between 45 and 90 mT, and the O2/(Ar + O2) flow rate ratio Γ between 0% and 100%. With increasing oxygen flow ratio a substoichiometric TaOx oxide forms at the metallic Ta target surface which further transfers to a non-conductive tantalum pentoxide Ta2O5, impeding a stable dc glow discharge. These two transition zones (from Ta to TaOx and from TaOx to Ta2O5) shift to higher oxygen flow rates for increasing target currents. In contrast, increasing the magnetic field strength (e.g., due to sputter erosion) mainly shifts the TaOx to Ta2O5 transition to lower oxygen flow rates while marginally influencing the Ta to TaOx transition. To allow for a stable dc glow discharge (and to suppress the formation of non-conductive Ta2O5 at the target) even at Γ = 100% either a high target current (Im ⩾ 1 A) or a low magnetic field strength (B ⩽ 60 mT) is necessary. These conditions are required to prepare stoichiometric and fully crystalline Ta2O5 films.

  11. H:q ratios and bilateral leg strength in college field and court sports players.

    PubMed

    Cheung, Roy T H; Smith, Andrew W; Wong, Del P

    2012-06-01

    One of the key components in sports injury prevention is the identification of imbalances in leg muscle strength. However, different leg muscle characteristics may occur in large playing area (field) sports and small playing area (court) sports, which should be considered in regular injury prevention assessment. This study examined the isokinetic hamstrings-to-quadriceps (H:Q) ratio and bilateral leg strength balance in 40 male college (age: 23.4 ± 2.5 yrs) team sport players (field sport = 23, soccer players; court sport = 17, volleyball and basketball players). Five repetitions of maximal knee concentric flexion and concentric extension were performed on an isokinetic dynamometer at two speeds (slow: 60°·s(-1) and fast: 300°·s(-1)) with 3 minutes rest between tests. Both legs were measured in counterbalanced order with the dominant leg being determined as the leg used to kick a ball. The highest concentric peak torque values (Nm) of the hamstrings and quadriceps of each leg were analyzed after body mass normalization (Nm·kg(-1)). Court sport players showed significantly weaker dominant leg hamstrings muscles at both contraction speeds (P < 0.05). The H:Q ratio was significantly larger in field players in their dominant leg at 60°·s(-1) (P < 0.001), and their non-dominant leg at 300°·s(-1) (P < 0.001) respectively. Sport-specific leg muscle strength was evident in college players from field and court sports. These results suggest the need for different muscle strength training and rehabilitation protocols for college players according to the musculature requirements in their respective sports.

  12. Resolution Improvements in in Vivo1H NMR Spectra with Increased Magnetic Field Strength

    NASA Astrophysics Data System (ADS)

    Gruetter, Rolf; Weisdorf, Sally A.; Rajanayagan, Vasantham; Terpstra, Melissa; Merkle, Hellmut; Truwit, Charles L.; Garwood, Michael; Nyberg, Scott L.; Ugurbil, Kâmil

    1998-11-01

    The measurement of cerebral metabolites using highly homologous localization techniques and similar shimming methods was performed in the human brain at 1.5 and 4 T as well as in the dog and rat brain at 9.4 T. In rat brain, improved resolution was achieved by shimming all first- and second-order shim coils using a fully adiabatic FASTMAP sequence. The spectra showed a clear improvement in spectral resolution for all metabolite resonances with increased field strength. Changes in cerebral glutamine content were clearly observed at 4 T compared to 1.5 T in patients with hepatic encephalopathy. At 9.4 T, glutamine H4 at 2.46 ppm was fully resolved from glutamate H4 at 2.37 ppm, as was the potential resonance from γ-amino-butyric acid at 2.30 ppm and N-acetyl-aspartyl-glutamate at 2.05 ppm. Singlet linewidths were found to be as low as 6 Hz (0.015 ppm) at 9.4 T, indicating a substantial decrease in ppm linewidth with field strength. Furthermore, the methylene peak of creatine was partially resolved from phosphocreatine, indicating a close to 1:1 relationship in gray matter. We conclude that increasing the magnetic field strength increases spectral resolution also for1H NMR, which can lead to more than linear sensitivity gains.

  13. Constraining the Solar Coronal Magnetic Field Strength using Split-band Type II Radio Burst Observations

    NASA Astrophysics Data System (ADS)

    Kishore, P.; Ramesh, R.; Hariharan, K.; Kathiravan, C.; Gopalswamy, N.

    2016-11-01

    We report on low-frequency radio (85-35 MHz) spectral observations of four different type II radio bursts, which exhibited fundamental-harmonic emission and split-band structure. Each of the bursts was found to be closely associated with a whitelight coronal mass ejection (CME) close to the Sun. We estimated the coronal magnetic field strength from the split-band characteristics of the bursts, by assuming a model for the coronal electron density distribution. The choice of the model was constrained, based on the following criteria: (1) when the radio burst is observed simultaneously in the upper and lower bands of the fundamental component, the location of the plasma level corresponding to the frequency of the burst in the lower band should be consistent with the deprojected location of the leading edge (LE) of the associated CME; (2) the drift speed of the type II bursts derived from such a model should agree closely with the deprojected speed of the LE of the corresponding CMEs. With the above conditions, we find that: (1) the estimated field strengths are unique to each type II burst, and (2) the radial variation of the field strength in the different events indicate a pattern. It is steepest for the case where the heliocentric distance range over which the associated burst is observed is closest to the Sun, and vice versa.

  14. DISPERSAL OF G-BAND BRIGHT POINTS AT DIFFERENT LONGITUDINAL MAGNETIC FIELD STRENGTHS

    SciTech Connect

    Yang, Yunfei; Ji, Kaifai; Feng, Song; Deng, Hui; Wang, Feng

    2015-09-10

    G-band bright points (GBPs) are thought to be the foot-points of magnetic flux tubes. The aim of this paper is to investigate the relation between the diffusion regimes of GBPs and the associated longitudinal magnetic field strengths. Two high resolution observations of different magnetized environments were acquired with the Hinode/Solar Optical Telescope. Each observation was recorded simultaneously with G-band filtergrams and Narrow-band Filter Imager (NFI) Stokes I and V images. GBPs are identified and tracked automatically, and then categorized into several groups by their longitudinal magnetic field strengths, which are extracted from the calibrated NFI magnetograms using a point-by-point method. The Lagrangian approach and the distribution of diffusion indices approach are adopted separately to explore the diffusion regime of GBPs for each group. It is found that the values of diffusion index and diffusion coefficient both decrease exponentially with the increasing longitudinal magnetic field strengths whichever approach is used. The empirical formulas deduced from the fitting equations are proposed to describe these relations. Stronger elements tend to diffuse more slowly than weak elements, independently of the magnetic flux of the surrounding medium. This may be because the magnetic energy of stronger elements is not negligible compared with the kinetic energy of the gas, and therefore the flows cannot perturb them so easily.

  15. Tailoring magnetostriction sign of ferromagnetic composite by increasing magnetic field strength

    NASA Astrophysics Data System (ADS)

    Gou, Junming; Liu, Xiaolian; Wu, Kaiyun; Wang, Yue; Hu, Shanshan; Zhao, Hui; Xiao, Andong; Ma, Tianyu; Yan, Mi

    2016-08-01

    The unitary deformation of single-phase ferromagnets by a magnetic field, i.e., either positive or negative linear magnetostriction, allows only monotonous control. Here we report a proof-of-principle ferromagnetic composite Fe73Ga27, for which the magnetostriction sign changes from positive to negative by increasing the magnetic field strength. Based on the transformation from body-centered-cubic (BCC) to face-centered-cubic (FCC) phases in this binary system, Fe73Ga27 composite is prepared by aging the BCC averaged precursor for 3 days at 803 K. Magnetic measurements indicate that the BCC phase exhibits smaller magnetocrystalline anisotropy constant than the FCC phase. The offset effect between BCC and FCC phases produces positive net magnetostriction at low magnetic fields but negative net magnetostriction at high magnetic fields. By tuning the field strength, such composites can mediate compressive and tensile strains to other functional materials, e.g., piezoelectric material or optic-fibers, which is beneficial to design multifunctional devices.

  16. 12 CFR 978.4 - Form of request.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... REQUESTS FOR INFORMATION § 978.4 Form of request. A request by a Bank to a financial regulatory agency for... and the financial regulatory agency. The request shall reference section 22 of the Act (12 U.S.C....

  17. 1 CFR 18.4 - Form of document.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... DOCUMENTS PREPARATION AND TRANSMITTAL OF DOCUMENTS GENERALLY § 18.4 Form of document. (a) A printed or... data in the publication process. (b) A document in the form of a letter or press release may not...

  18. 1 CFR 18.4 - Form of document.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... DOCUMENTS PREPARATION AND TRANSMITTAL OF DOCUMENTS GENERALLY § 18.4 Form of document. (a) A printed or... data in the publication process. (b) A document in the form of a letter or press release may not...

  19. 1 CFR 18.4 - Form of document.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... DOCUMENTS PREPARATION AND TRANSMITTAL OF DOCUMENTS GENERALLY § 18.4 Form of document. (a) A printed or... data in the publication process. (b) A document in the form of a letter or press release may not...

  20. 1 CFR 18.4 - Form of document.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... DOCUMENTS PREPARATION AND TRANSMITTAL OF DOCUMENTS GENERALLY § 18.4 Form of document. (a) A printed or... data in the publication process. (b) A document in the form of a letter or press release may not...

  1. 1 CFR 18.4 - Form of document.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... DOCUMENTS PREPARATION AND TRANSMITTAL OF DOCUMENTS GENERALLY § 18.4 Form of document. (a) A printed or... data in the publication process. (b) A document in the form of a letter or press release may not...

  2. Nonlinear theory of pattern formation in ferrofluid films at high field strengths.

    PubMed

    Richardi, J; Pileni, M P

    2004-01-01

    When a magnetic field is applied to a thin layer of a suspension of magnetic nanoparticles (ferrofluid), the formation of labyrinthine and hexagonal patterns is observed. We introduce a theory to describe ferrofluid patterns at high field, where a nonlinear relationship between field and magnetization is expected. The computational difficulties due to the use of a nonlinear magnetization curve are solved by a reformulation of the magnetic energy equation. The evolution of the pattern size at intermediate and very high fields can be understood by an analysis of limiting cases of the magnetization curve. In particular, at a very high field the pattern size reaches a constant saturation value which has been recently confirmed by experiments. The field for the onset of a nonlinear behavior is shifted to higher field strength due to a demagnetization effect. This can partially explain the ability of linear approaches to reproduce experimental data even at a high field. Finally, the impact of the nonlinearity of the magnetization curve on the transition between hexagonal and labyrinthine patterns is discussed.

  3. Effect of excitation field strength on magnetic Barkhausen noise profile in case carburized EN 36 steel

    NASA Astrophysics Data System (ADS)

    Blaow, M. M.; Shaw, B. A.

    2015-03-01

    The sensitivity of magnetic Barkhausen noise (MBN) profile to changes in the excitation field strength has been investigated in case carburized EN36 steel. In general, the 0.5 mm case depth EN 36 steel specimen induces a double peak profile indicative of inhomogeneity through the detected depth in the magnetized landscape. Various excitation field amplitudes have been applied to the electromagnet to generate various excitation fields on the specimen surface. Excitation field at the lowest level induced an MBN emission of two peaks of equivalent heights at low current value. The first peak occurs at lower field than the second peak in each half magnetization cycle. As the excitation field increases, the height of both peaks increased but the second peak, at higher field, increases in a higher rate than that of the first peak at lower field. Beyond certain magnetizing voltage, both peaks heights began to saturate and no further increase in the MBN intensity has been noticed. The results are discussed on the basis of the available theories on MBN.

  4. The Spectrovideomagnetograph Reveals the True Strength of Quiet Sun Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Zirin, H.; Cameron, R.

    2000-12-01

    We present new observations of weak solar magnetic fields with a technique, which we term the spectro-videomagnetograph (SPVMG) which permits direct measurement of splittings as small as 200 gauss. Using the technique of Stenflo we compared the Stokes V-component for the 5250 and 5247 lines. Contrary to Stenflo's results, we find no evidence for strong fields with small filling factor; i. e., the field strengths measured as 200 gaussare really 200 gauss and not some stronger field partly filling the sample. For the weakest measured fields this cannot be absolutely established, but the evidence supports the existence of field elements at least as weak as 200 gauss. Observations of active regions also yield new results. In many cases of fields near inversion lines, we find doubled sets of Zeeman components, as well as `flags,' broad components, usually confined to one side of the line, extending to displacements corresponding to thousands of gauss, with no corresponding component on the opposite side of the line. We show examples of these spectra, along with slit jaw images, but have only a limited understanding of the field structures they represent. We also have examples of the V-splitting increasing as we approach the inversion line. We are struggling to understand these and will at least show them, with or without explanation. Finally, the regions involving these anomalous Zeeman patterns seem to flare more frequently, although statistics are limited. This work has been supported by the NSF under ATM-9726147.

  5. Prostate MR imaging at high-field strength: evolution or revolution?

    PubMed

    Rouvière, Olivier; Hartman, Robert P; Lyonnet, Denis

    2006-02-01

    As 3 T MR scanners become more available, body imaging at high field strength is becoming the subject of intensive research. However, little has been published on prostate imaging at 3 T. Will high-field imaging dramatically increase our ability to depict and stage prostate cancer? This paper will address this question by reviewing the advantages and drawbacks of body imaging at 3 T and the current limitations of prostate imaging at 1.5 T, and by detailing the preliminary results of prostate 3 T MRI. Even if slight adjustments of imaging protocols are necessary for taking into account the changes in T1 and T2 relaxation times at 3 T, tissue contrast in T2-weighted (T2w) imaging seems similar at 1.5 T and 3 T. Therefore, significant improvement in cancer depiction in T2w imaging is not expected. However, increased spatial resolution due to increased signal-to-noise ratio (SNR) may improve the detection of minimal capsular invasion. Higher field strength should provide increased spectral and spatial resolution for spectroscopic imaging, but new pulse sequences will have to be designed for overcoming field inhomogeneities and citrate J-modulation issues. Finally, dynamic contrast-enhanced MRI is the method of imaging that is the most likely to benefit from the increased SNR, with a significantly better trade-off between temporal and spatial resolution.

  6. Digital tabulation of historical sunspot field strength measurements from the Mount Wilson Observatory

    NASA Astrophysics Data System (ADS)

    Pevtsov, Alexei; Tlatov, Andrey; Bertello, Luca; Ulrich, Roger

    2015-08-01

    Direct (manual) measurements of magnetic fields in sunspots based on Zeeman effect represent the longest magnetic observations pertinent to the Sun. Regular (daily) observations started in about 1917 and continue till present. The data consist of daily drawings of sunspots with the corresponding field strength and polarity measurements handwritten on these drawings. All the drawings are now scanned to digital images (JPEG format). However, the lack of tabulated data severely limits the use of this unique data set. Here we report on status and the results of several recent projects aimed at the digital tabulation of MWO drawings. While the individual projects are funded independently by the American (USA) and Russian funding agencies, the groups collaborate closely with each other to achieve a common goal - creation of tabulated data set contacting magnetic field and sunspot position information derived from the drawings. The collaboration is coordinated by the IAU working group on Coordination of Synoptic Observations of the Sun.

  7. Educational application for visualization and analysis of electric field strength in multiple electrode electroporation

    PubMed Central

    2012-01-01

    Background Electrochemotherapy is a local treatment that utilizes electric pulses in order to achieve local increase in cytotoxicity of some anticancer drugs. The success of this treatment is highly dependent on parameters such as tissue electrical properties, applied voltages and spatial relations in placement of electrodes that are used to establish a cell-permeabilizing electric field in target tissue. Non-thermal irreversible electroporation techniques for ablation of tissue depend similarly on these parameters. In the treatment planning stage, if oversimplified approximations for evaluation of electric field are used, such as U/d (voltage-to-distance ratio), sufficient field strength may not be reached within the entire target (tumor) area, potentially resulting in treatment failure. Results In order to provide an aid in education of medical personnel performing electrochemotherapy and non-thermal irreversible electroporation for tissue ablation, assist in visualizing the electric field in needle electrode electroporation and the effects of changes in electrode placement, an application has been developed both as a desktop- and a web-based solution. It enables users to position up to twelve electrodes in a plane of adjustable dimensions representing a two-dimensional slice of tissue. By means of manipulation of electrode placement, i.e. repositioning, and the changes in electrical parameters, the users interact with the system and observe the resulting electrical field strength established by the inserted electrodes in real time. The field strength is calculated and visualized online and instantaneously reflects the desired changes, dramatically improving the user friendliness and educational value, especially compared to approaches utilizing general-purpose numerical modeling software, such as finite element modeling packages. Conclusion In this paper we outline the need and offer a solution in medical education in the field of electroporation

  8. Geomagnetic field strength 3.2 billion years ago recorded by single silicate crystals.

    PubMed

    Tarduno, John A; Cottrell, Rory D; Watkeys, Michael K; Bauch, Dorothy

    2007-04-05

    The strength of the Earth's early geomagnetic field is of importance for understanding the evolution of the Earth's deep interior, surface environment and atmosphere. Palaeomagnetic and palaeointensity data from rocks formed near the boundary of the Proterozoic and Archaean eons, some 2.5 Gyr ago, show many hallmarks of the more recent geomagnetic field. Reversals are recorded, palaeosecular variation data indicate a dipole-dominated morphology and available palaeointensity values are similar to those from younger rocks. The picture before 2.8 Gyr ago is much less clear. Rocks of the Archaean Kaapvaal craton (South Africa) are among the best-preserved, but even they have experienced low-grade metamorphism. The variable acquisition of later magnetizations by these rocks is therefore expected, precluding use of conventional palaeointensity methods. Silicate crystals from igneous rocks, however, can contain minute magnetic inclusions capable of preserving Archaean-age magnetizations. Here we use a CO2 laser heating approach and direct-current SQUID magnetometer measurements to obtain palaeodirections and intensities from single silicate crystals that host magnetite inclusions. We find 3.2-Gyr-old field strengths that are within 50 per cent of the present-day value, indicating that a viable magnetosphere sheltered the early Earth's atmosphere from solar wind erosion.

  9. Strength of the spontaneously emitted collective aperiodic magnetic field fluctuations in the reionized early intergalactic medium

    SciTech Connect

    Schlickeiser, R.; Felten, T. E-mail: tim.felten@rub.de

    2013-11-20

    Nonmagnetized, fully ionized plasmas spontaneously emit aperiodic turbulent magnetic field fluctuations. Its fluctuation intensities are dominated by the contribution from a recently discovered collective, damped mode, which modifies the earlier estimate of the total magnetic field strength in a thermal nonrelativistic electron-proton plasma to |δB|=24β{sub e}{sup 1/4}(gn{sub e}m{sub e}c{sup 2}){sup 1/2} G, where g denotes the plasma parameter and β {sub e} the thermal electron velocity in units of the speed of light, in the case of no collisional damping. Accounting for simultaneous viscous damping reduces the estimate to |δB|{sub eq} = 2305g(n{sub e}m{sub e}c {sup 2}){sup 1/2} G, depending only on the plasma parameter g and the electron density n{sub e} . For the unmagnetized intergalactic medium, immediately after the reionization onset the field strengths from this mechanism are about 6.8 × 10{sup –13} G for no collisional damping and 1.5 × 10{sup –16} G for viscous damping. Maximum spatial scales of 10{sup 15} cm of the emitted aperiodic fluctuations in cosmic voids are possible.

  10. Separation of DNA fragments for fast diagnosis by microchip electrophoresis using programmed field strength gradient.

    PubMed

    Kang, Seong Ho; Park, Mira; Cho, Keunchang

    2005-08-01

    We evaluated a novel strategy for fast diagnosis by microchip electrophoresis (ME), using programmed field strength gradients (PFSG) in a conventional glass double-T microfluidic chip. The ME-PFSG allows for the ultrafast separation and enhanced resolving power for target DNA fragments. These results are based on electric field strength gradients (FSG) that use an ME separation step in a sieving gel matrix poly-(ethylene oxide). The gradient can develop staircase or programmed shapes FSG over the time. The PFSG method could be easily used to increase separation efficiency and resolution in ME separation of specific size DNA fragments. Compared to ME that uses a conventional and constantly applied electric field (isoelectrostatic) method, the ME-PFSG achieved about 15-fold faster analysis time during the separation of 100 bp DNA ladder. The ME-PFSG was also applied to the fast analysis of the PCR products, 591 and 1191 bp DNA fragments from the 18S rRNA of Babesia gibsoni and Babesia caballi.

  11. High radio-frequency field strength nutation NMR of quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Franssen, W. M. J.; Rezus, Y. L. A.; Kentgens, A. P. M.

    2016-12-01

    Owing to the introduction of microcoils, high RF field strength nutation NMR is a viable candidate for the study of quadrupolar nuclei with strong quadrupolar couplings, not accessible using contemporary NMR techniques. We show powder 23 Na nutation spectra on sodium nitrite for RF field strengths of up to 1170 kHz, that conform to theoretical predictions. For lanthanum fluoride powder, 139 La nutation spectra taken at elevated RF field amplitudes show clear discrepancies when compared to the theory. These errors are shown to be mainly caused by pulse transients at the end of the pulse, which proved to be detrimental to the shape of the nutation spectra. Using a nutation pulse which ends in a sudden frequency jump, we show that these errors can be reduced, and nutation spectra that conform to theory can be readily acquired. This enables nutation NMR for the study of quadrupolar nuclei with a strong quadrupolar coupling, bridging the gap between NMR, which can only analyse nuclei with a weak to medium quadrupolar coupling, and NQR, were extensive searching for the right quadrupolar frequency is the limiting factor.

  12. Comparisons of 76Hz Transverse and Radial Magnetic Field Strength Components Received in Connecticut.

    DTIC Science & Technology

    1986-03-11

    Measurements Made in Connecticut During 1974, NUSC Technical Report 4927, Naval Underwater Systems Center, New London, CT, 1 October 1975. 4 . P. R. Bannister and...Connecticut Radial , lanetic Field Strength \\crsIis GMT, 24 and 25 April 1981 . - 290 Jei [ -- ,. 4 TR 7523 -150 -152 -154 0 0 4 /26/84 -156 0 0 -158 -148 -150...Received in Connecticut Peter R. Bannister Submarine Electromagnetic Systems Department DTIC ~PR1 4 11986L .-- aO?,f Naval Underwater Systems Center

  13. Wearable sensors for skin heating and electric field strength in harsh environments

    NASA Astrophysics Data System (ADS)

    Lewis, Jay; Klem, Ethan; Cunningham, Garry; Dummer, Andrew

    2010-04-01

    Two novel sensor technologies have been developed for the measurement of skin surface temperature and RF field strength in an RF environment. Such a sensor system would be particularly useful in the test and evaluation of directed energy systems. The sensors operate without being affected by the presence of RF fields and with minimal perturbation of the fields, therefore having a minimal effect on a test. The sensors are designed to be wearable and interface with a portable, battery powered electronics pack by optical fibers. The temperature sensor is based on the variation in fluorescence intensity of a sensor layer with temperature. The RF field sensors operate using a passive circuit that converts the RF field into an optical signal that is measured remotely. Both sensors have been demonstrated in high power microwave lab tests. RF sensor operability has been demonstrated for fields in the range of 0.4 - 8.9 W/cm2, while the temperature sensor has been demonstrated over the 30 - 60°C temperature range.

  14. MECHANICAL STRENGTH RESPONSES OF POLED LEAD ZIRCONATE TITANATE UNDER EXTREME ELECTRIC FIELD AND VARIOUS TEMPERATURE CONDITIONS

    SciTech Connect

    Wang, Hong; Matsunaga, Tadashi; Zhang, Kewei; Lin, Hua-Tay; Wereszczak, Andrew A

    2016-01-01

    PZT (lead zirconate titanate), particularly PZT-5A, is used in a variety of critical actuation and sensing systems because of its high Curie temperature and large piezoelectric coefficients. However, PZT is susceptible to mechanical failure. The evaluation of the mechanical strength of the material under the target working conditions is very important. This study presents part of the recent experimental developments in mechanical testing and evaluation of PZT materials at Oak Ridge National Laboratory. Ball-on-ring and four-point bending testing setups were used, with modifications made to account for testing requirements from high-level electric field and elevated temperature. The poled PZT-5A or equivalent material was tested under various specimen and testing conditions. The parameters of the distribution of strengths (characteristic strength and Weibull modulus) are discussed in relation to the testing conditions. Fractographic results based on scanning electron microscopy are also presented and discussed. The related data can serve as input for the design of piezoceramic devices, not only those used in energy systems like fuel injectors in heavy-duty diesel engines, but also those used in structural health monitoring, energy harvesting, and other critical systems in aerospace and civil engineering.

  15. Behavioral effects on rats of high strength magnetic fields generated by a resistive electromagnet.

    PubMed

    Houpt, Thomas A; Pittman, David W; Riccardi, Christina; Cassell, Jennifer A; Lockwood, Denesa R; Barranco, Jan M; Kwon, Bumsup; Smith, James C

    2005-10-15

    It has been reported previously that exposure to static high magnetic fields of 7 T or above in superconducting magnets has behavioral effects on rats. In particular, magnetic field exposure acutely but transiently suppressed rearing and induced walking in tight circles; the direction of circular locomotion was dependent on the rats' orientation within the magnet. Furthermore, when magnet exposure was paired with consumption of a palatable, novel solution, rats acquired a persistent taste aversion. In order to confirm these results under more controlled conditions, we exposed rats to static magnetic fields of 4 to 19.4 T in a 189 mm bore, 20 T resistive magnet. By using a resistive magnet, field strengths could be arbitrary varied from -19.4 to 19.4 T within the same bore. Rearing was suppressed after exposure to 4 T and above; circling was observed after 7 T and above. Conditioned taste aversion was acquired after 14 T and above. The effects of the magnetic fields were dependent on orientation. Exposure to +14 T induced counter-clockwise circling, while exposure to -14 T induced clockwise circling. Exposure with the rostral-caudal axis of the rat perpendicular to the magnetic field produced an attenuated behavioral response compared to exposure with the rostral-caudal axis parallel to the field. These results in a single resistive magnet confirm and extend our earlier findings using multiple superconducting magnets. They demonstrate that the behavioral effects of exposure within large magnets are dependent on the magnetic field, and not on non-magnetic properties of the machinery. Finally, the effects of exposure to 4 T are clinically relevant, as 4 T magnetic fields are commonly used in functional MRI assays.

  16. National surveys of radiofrequency field strengths from radio base stations in Africa.

    PubMed

    Joyner, Ken H; Van Wyk, Marthinus J; Rowley, Jack T

    2014-01-01

    The authors analysed almost 260 000 measurement points from surveys of radiofrequency (RF) field strengths near radio base stations in seven African countries over two time frames from 2001 to 2003 and 2006 to 2012. The results of the national surveys were compared, chronological trends investigated and potential exposures compared by technology and with frequency modulation (FM) radio. The key findings from thes data are that irrespective of country, the year and mobile technology, RF fields at a ground level were only a small fraction of the international human RF exposure recommendations. Importantly, there has been no significant increase in typical measured levels since the introduction of 3G services. The mean levels in these African countries are similar to the reported levels for countries of Asia, Europe and North America using similar mobile technologies. The median level for the FM services in South Africa was comparable to the individual but generally lower than the combined mobile services.

  17. National surveys of radiofrequency field strengths from radio base stations in Africa

    PubMed Central

    Joyner, Ken H.; Van Wyk, Marthinus J.; Rowley, Jack T.

    2014-01-01

    The authors analysed almost 260 000 measurement points from surveys of radiofrequency (RF) field strengths near radio base stations in seven African countries over two time frames from 2001 to 2003 and 2006 to 2012. The results of the national surveys were compared, chronological trends investigated and potential exposures compared by technology and with frequency modulation (FM) radio. The key findings from thes data are that irrespective of country, the year and mobile technology, RF fields at a ground level were only a small fraction of the international human RF exposure recommendations. Importantly, there has been no significant increase in typical measured levels since the introduction of 3G services. The mean levels in these African countries are similar to the reported levels for countries of Asia, Europe and North America using similar mobile technologies. The median level for the FM services in South Africa was comparable to the individual but generally lower than the combined mobile services. PMID:24044904

  18. Earth-strength magnetic field affects the rheotactic threshold of zebrafish swimming in shoals.

    PubMed

    Cresci, Alessandro; De Rosa, Rosario; Putman, Nathan F; Agnisola, Claudio

    2017-02-01

    Rheotaxis, the unconditioned orienting response to water currents, is a main component of fish behavior. Rheotaxis is achieved using multiple sensory systems, including visual and tactile cues. Rheotactic orientation in open or low-visibility waters might also benefit from the stable frame of reference provided by the geomagnetic field, but this possibility has not been explored before. Zebrafish (Danio rerio) form shoals living in freshwater systems with low visibility, show a robust positive rheotaxis, and respond to geomagnetic fields. Here, we investigated whether a static magnetic field in the Earth-strength range influenced the rheotactic threshold of zebrafish in a swimming tunnel. The direction of the horizontal component of the magnetic field relative to water flow influenced the rheotactic threshold of fish as part of a shoal, but not of fish tested alone. Results obtained after disabling the lateral line of shoaling individuals with Co(2+) suggest that this organ system is involved in the observed magneto-rheotactic response. These findings constitute preliminary evidence that magnetic fields influence rheotaxis and suggest new avenues for further research.

  19. Magnetically responsive nanoparticles for drug delivery applications using low magnetic field strengths.

    PubMed

    McGill, Shayna L; Cuylear, Carla L; Adolphi, Natalie L; Osiński, Marek; Smyth, Hugh D C

    2009-03-01

    The purpose of this study is to investigate the potential of magnetic nanoparticles for enhancing drug delivery using a low oscillating magnetic field (OMF) strength. We investigated the ability of magnetic nanoparticles to cause disruption of a viscous biopolymer barrier to drug delivery and the potential to induce triggered release of drug conjugated to the surfaces of these particles. Various magnetic nanoparticles were screened for thermal response under a 295-kHz OMF with an amplitude of 3.1 kA/m. Based on thermal activity of particles screened, we selected the nanoparticles that displayed desired characteristics for evaluation in a simplified model of an extracellular barrier to drug delivery, using lambda DNA/HindIII. Results indicate that nanoparticles could be used to induce DNA breakage to enhance local diffusion of drugs, despite low temperatures of heating. Additional studies showed increased diffusion of quantum dots in this model by single-particle tracking methods. Bimane was conjugated to the surface of magnetic nanoparticles. Fluorescence and transmission electron microscope images of the conjugated nanoparticles indicated little change in the overall appearance of the nanoparticles. A release study showed greater drug release using OMF, while maintaining low bulk heating of the samples (T = 30 degrees C). This study indicates that lower magnetic field strengths may be successfully utilized for drug delivery applications as a method for drug delivery transport enhancement and drug release switches.

  20. CORONAL SEISMOLOGY USING EIT WAVES: ESTIMATION OF THE CORONAL MAGNETIC FIELD STRENGTH IN THE QUIET SUN

    SciTech Connect

    West, M. J.; Zhukov, A. N.; Dolla, L.; Rodriguez, L.

    2011-04-01

    Coronal EIT waves have been observed for many years. The nature of EIT waves is still contentious, however, there is strong evidence that some of them might be fast magnetosonic waves, or at least have a fast magnetosonic wave component. The fast magnetosonic wave speed is formed from two components; the Alfven speed (magnetic) and the sound speed (thermal). By making measurements of the wave speed, coronal density and temperature it is possible to calculate the quiet-Sun coronal magnetic field strength through coronal seismology. In this paper, we investigate an EIT wave observed on 2009 February 13 by the SECCHI/EUVI instruments on board the STEREO satellites. The wave epicenter was observed at disk center in the STEREO B (Behind) satellite. At this time, the STEREO satellites were separated by approximately 90 deg., and as a consequence the STEREO A (Ahead) satellite observed the wave on the solar limb. These observations allowed us to make accurate speed measurements of the wave. The background coronal density was derived through Hinode/Extreme-ultraviolet Imaging Spectrometer observations of the quiet Sun and the temperature was estimated through the narrow temperature response in the EUVI bandpasses. The density, temperature, and speed measurements allowed us to estimate the quiet-Sun coronal magnetic field strength to be approximately 0.7 {+-} 0.7 G.

  1. Initial experience of using high field strength intraoperative MRI for neurosurgical procedures.

    PubMed

    Raheja, Amol; Tandon, Vivek; Suri, Ashish; Sarat Chandra, P; Kale, Shashank S; Garg, Ajay; Pandey, Ravindra M; Kalaivani, Mani; Mahapatra, Ashok K; Sharma, Bhawani S

    2015-08-01

    We report our initial experience to optimize neurosurgical procedures using high field strength intraoperative magnetic resonance imaging (IOMRI) in 300 consecutive patients as high field strength IOMRI rapidly becomes the standard of care for neurosurgical procedures. Three sequential groups (groups A, B, C; n=100 each) were compared with respect to time management, complications and technical difficulties to assess improvement in these parameters with experience. We observed a reduction in the number of technical difficulties (p<0.001), time to induction (p<0.001) and total anesthesia time (p=0.007) in sequential groups. IOMRI was performed for neuronavigation guidance (n=252) and intraoperative validation of extent of resection (EOR; n=67). Performing IOMRI increased the EOR over and beyond the primary surgical attempt in 20.5% (29/141) and 18% (11/61) of patients undergoing glioma and pituitary surgery, respectively. Overall, EOR improved in 59.7% of patients undergoing IOMRI (40/67). Intraoperative tractography and real time navigation using re-uploaded IOMRI images (accounting for brain shift) helps in intraoperative planning to reduce complications. IOMRI is an asset to neurosurgeons, helping to augment the EOR, especially in glioma and pituitary surgery, with no significant increase in morbidity to the patient.

  2. A feasibility study of high-strength Bi-2223 conductor for high-field solenoids

    NASA Astrophysics Data System (ADS)

    Godeke, A.; Abraimov, D. V.; Arroyo, E.; Barret, N.; Bird, M. D.; Francis, A.; Jaroszynski, J.; Kurteva, D. V.; Markiewicz, W. D.; Marks, E. L.; Marshall, W. S.; McRae, D. M.; Noyes, P. D.; Pereira, R. C. P.; Viouchkov, Y. L.; Walsh, R. P.; White, J. M.

    2017-03-01

    We performed a feasibility study on a high-strength Bi{}2-xPb x Sr2Ca2Cu3O{}10-x(Bi-2223) tape conductor for high-field solenoid applications. The investigated conductor, DI-BSCCO Type HT-XX, is a pre-production version of Type HT-NX, which has recently become available from Sumitomo Electric Industries. It is based on their DI-BSCCO Type H tape, but laminated with a high-strength Ni-alloy. We used stress–strain characterizations, single- and double-bend tests, easy- and hard-way bent coil-turns at various radii, straight and helical samples in up to 31.2 T background field, and small 20-turn coils in up to 17 T background field to systematically determine the electro-mechanical limits in magnet-relevant conditions. In longitudinal tensile tests at 77 K, we found critical stress- and strain-levels of 516 MPa and 0.57%, respectively. In three decidedly different experiments we detected an amplification of the allowable strain with a combination of pure bending and Lorentz loading to ≥slant 0.92 % (calculated elastically at the outer tape edge). This significant strain level, and the fact that it is multi-filamentary conductor and available in the reacted and insulated state, makes DI-BSCCO HT-NX highly suitable for very high-field solenoids, for which high current densities and therefore high loads are required to retain manageable magnet dimensions.

  3. Examining the Magnetic Field Strength and the Horizontal and Vertical Motions in an Emerging Active Region

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Hsien; Chen, Yu-Che

    2016-03-01

    Earlier observational studies have used the time evolution of emerging magnetic flux regions at the photosphere to infer their subsurface structures, assuming that the flux structure does not change significantly over the near-surface layer. In this study, we test the validity of this assumption by comparing the horizontal and vertical motions of an emerging active region. The two motions would be correlated if the emerging structure is rigid. The selected active region (AR) NOAA 11645 is not embedded in detectable preexisting magnetic field. The observed horizontal motion is quantified by the separation of the two AR polarities and the width of the region. The vertical motion is derived from the magnetic buoyancy theory. Our results show that the separation of the polarities is fastest at the beginning with a velocity of {≈ }4 Mm hr^{-1} and decreases to ≤ 1 Mm hr^{-1} after the main growing phase of flux emergence. The derived thick flux-tube buoyant velocity is between 1 and 3 Mm hr^{-1}, while the thin flux-tube approximation results in an unreasonably high buoyant velocity, consistent with the expectation that the approximation is inappropriate at the surface layer. The observed horizontal motion is not found to directly correlate with either the magnetic field strength or the derived buoyant velocities. However, the percentage of the horizontally oriented fields and the temporal derivatives of the field strength and the buoyant velocity show some positive correlations with the separation velocity. The results of this study imply that the assumption that the emerging active region is the cross section of a rising flux tube whose structure can be considered rigid as it rises through the near-surface layer should be taken with caution.

  4. 22 CFR 19.7-4 - Form of agreement.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Form of agreement. 19.7-4 Section 19.7-4... THE FOREIGN SERVICE RETIREMENT AND DISABILITY SYSTEM § 19.7-4 Form of agreement. (a) A spousal agreement is any legal agreement between the parties accepted by PER/ER/RET as meeting the requirements...

  5. Monte Carlo characterization of skin doses in 6 MV transverse field MRI-linac systems: Effect of field size, surface orientation, magnetic field strength, and exit bolus

    SciTech Connect

    Oborn, B. M.; Metcalfe, P. E.; Butson, M. J.; Rosenfeld, A. B.

    2010-10-15

    Purpose: The main focus of this work is to continue investigations into the Monte Carlo predicted skin doses seen in MRI-guided radiotherapy. In particular, the authors aim to characterize the 70 {mu}m skin doses over a larger range of magnetic field strength and x-ray field size than in the current literature. The effect of surface orientation on both the entry and exit sides is also studied. Finally, the use of exit bolus is also investigated for minimizing the negative effects of the electron return effect (ERE) on the exit skin dose. Methods: High resolution GEANT4 Monte Carlo simulations of a water phantom exposed to a 6 MV x-ray beam (Varian 2100C) have been performed. Transverse magnetic fields of strengths between 0 and 3 T have been applied to a 30x30x20 cm{sup 3} phantom. This phantom is also altered to have variable entry and exit surfaces with respect to the beam central axis and they range from -75 deg. to +75 deg. The exit bolus simulated is a 1 cm thick (water equivalent) slab located on the beam exit side. Results: On the entry side, significant skin doses at the beam central axis are reported for large positive surface angles and strong magnetic fields. However, over the entry surface angle range of -30 deg. to -60 deg., the entry skin dose is comparable to or less than the zero magnetic field skin dose, regardless of magnetic field strength and field size. On the exit side, moderate to high central axis skin dose increases are expected except at large positive surface angles. For exit bolus of 1 cm thickness, the central axis exit skin dose becomes an almost consistent value regardless of magnetic field strength or exit surface angle. This is due to the almost complete absorption of the ERE electrons by the bolus. Conclusions: There is an ideal entry angle range of -30 deg. to -60 deg. where entry skin dose is comparable to or less than the zero magnetic field skin dose. Other than this, the entry skin dose increases are significant, especially at

  6. Effect of various electric field strengths and current durations on stunning and spinal injuries of Atlantic herring.

    PubMed

    Nordgreen, Andreas Hoel; Slinde, Erik; Møller, Dag; Roth, Bjorn

    2008-06-01

    The aim of this study was to evaluate the effect of electric field strength and current duration on wild-caught Atlantic herring Clupea harengus stunned with sinusoidal 50-Hz AC in seawater. The fish were exposed to electric field strengths ranging from 16 to 142 V/m and current durations from 1 to 12 s. We recorded the elapsed times between the point at which each fish became unconscious and the points at which it resumed normal behavioral functions. We also investigated injuries such as broken spinal columns and hematomas after the fish were filleted. The threshold electric field strength required to stun all of the fish to unconsciousness was 33 V/m for 1 s. The duration of the unconscious condition increased as both electric field strength and current duration increased. Of a total of 260 Atlantic herring, 60% had broken spinal columns. The proportion of fish with fractured spines was independent of field strength and duration, but the number of fractures per fish increased with field strength. We conclude that electrical stunning would promote the welfare of Atlantic herring that are landed alive but negatively affect fillet quality owing to hematomas associated with the fractures.

  7. Magnetic Field Strength in an Intermediate-velocity Ionized Filament in the First Galactic Quadrant

    NASA Astrophysics Data System (ADS)

    Stil, J. M.; Hryhoriw, A.

    2016-08-01

    We investigate the magnetic field in an intermediate-velocity filament for which the Hα intensity in the WHAM survey correlates with excess Faraday rotation of extragalactic radio sources over the length of the filament from b ≈ 20° to b ≈ 55°. The density-weighted mean magnetic field is 2.8 +/- 0.8 μ {{G}}, derived from rotation measures and an empirical relation between Hα emission measure and dispersion measure from Berkhuijsen et al. In view of the uncertainties in the derived magnetic field strength, we propose an alternative use of the available data, rotation measure, and emission measure, to derive a lower limit to the Alfvén speed, weighted by electron density {n}e3/2. We find lower limits to the Alfvén speed that are comparable to or larger than the sound speed in a {10}4 {{K}} plasma, and conclude that the magnetic field is dynamically important. We discuss the role of intermediate-velocity gas as a locus of Faraday rotation in the interstellar medium, and propose that this lower limit to the Alfvén speed may also be applicable to Faraday rotation by galaxy clusters.

  8. Surface Magnetic Field Strengths: New Tests of Magnetoconvective Models of M Dwarfs

    NASA Astrophysics Data System (ADS)

    MacDonald, James; Mullan, D. J.

    2014-05-01

    Precision modeling of M dwarfs has become worthwhile in recent years due to the increasingly precise values of masses and radii which can be obtained from eclipsing binary studies. In a recent paper, Torres has identified four prime M dwarf pairs with the most precise empirical determinations of masses and radii. The measured radii are consistently larger than standard stellar models predict by several percent. These four systems potentially provide the most challenging tests of precision evolutionary models of cool dwarfs at the present time. We have previously modeled M dwarfs in the context of a criterion due to Gough & Tayler in which magnetic fields inhibit the onset of convection according to a physics-based prescription. In the present paper, we apply our magnetoconvective approach to the four prime systems in the Torres list. Going a step beyond what we have already modeled in CM Dra (one of the four Torres systems), we note that new constraints on magnetoconvective models of M dwarfs are now available from empirical estimates of magnetic field strengths on the surfaces of these stars. In the present paper, we consider how well our magnetoconvective models succeed when confronted with this new test of surface magnetic field strengths. Among the systems listed by Torres, we find that plausible magnetic models work well for CM Dra, YY Gem, and CU Cnc. (The fourth system in Torres's list does not yet have enough information to warrant magnetic modeling.) Our magnetoconvection models of CM Dra, YY Gem, and CU Cnc yield predictions of the magnetic fluxes on the stellar surface which are consistent with the observed correlation between magnetic flux and X-ray luminosity.

  9. 3D phase-field modelling of dislocation loop sink strengths

    NASA Astrophysics Data System (ADS)

    Thuinet, L.; Rouchette, H.; Legris, A.

    2017-01-01

    This work presents a 3D phase-field model to correctly evaluate dislocation loop sink strength. This method is applied to a wide range of microstructures (dislocation loops of various types with isotropic or anisotropic elasticity, like in Zr, cohabitation of different types of loop in the same calculation domain), which allows to exhibit several original results. Among them, in the case of isotropic elasticity, our model shows that the sink strength of vacancy loops is higher than that of interstitial ones for low loop radii. In the case of Zr, the effect on sink biases of the shape anisotropy of self-interstitial atoms, already exhibited in the case of straight dislocations, is enhanced for loops and stabilizes basal vacancy and prism-plane interstitial ones. Moreover, isotropic elastic interactions promote the coexistence of parallel vacancy and interstitial loops. This result is still valid in the case of prism-plane loops in Zr, which could provide explanations to several experimental facts.

  10. A low-cost, high-field-strength magnetic resonance imaging-compatible actuator.

    PubMed

    Secoli, Riccardo; Robinson, Matthew; Brugnoli, Michele; Rodriguez y Baena, Ferdinando

    2015-03-01

    To perform minimally invasive surgical interventions with the aid of robotic systems within a magnetic resonance imaging scanner offers significant advantages compared to conventional surgery. However, despite the numerous exciting potential applications of this technology, the introduction of magnetic resonance imaging-compatible robotics has been hampered by safety, reliability and cost concerns: the robots should not be attracted by the strong magnetic field of the scanner and should operate reliably in the field without causing distortion to the scan data. Development of non-conventional sensors and/or actuators is thus required to meet these strict operational and safety requirements. These demands commonly result in expensive actuators, which mean that cost effectiveness remains a major challenge for such robotic systems. This work presents a low-cost, high-field-strength magnetic resonance imaging-compatible actuator: a pneumatic stepper motor which is controllable in open loop or closed loop, along with a rotary encoder, both fully manufactured in plastic, which are shown to perform reliably via a set of in vitro trials while generating negligible artifacts when imaged within a standard clinical scanner.

  11. POSSIBLE CONSTRAINTS ON EXOPLANET MAGNETIC FIELD STRENGTHS FROM PLANET-STAR INTERACTION

    SciTech Connect

    Scharf, Caleb A.

    2010-10-20

    A small percentage of normal stars harbor giant planets that orbit within a few tenths of an astronomical unit. At such distances, the potential exists for significant tidal and magnetic field interaction resulting in energy dissipation that may manifest as changes within the stellar corona. We examine the X-ray emission of stars hosting planets and find a positive correlation between X-ray luminosity and the projected mass of the most closely orbiting exoplanets. We investigate possible systematics and observational biases that could mimic or confuse this correlation but find no strong evidence for any, especially for planets more massive than {approx}0.1 M{sub J} . Luminosities and upper limits are consistent with the interpretation that there is a lower floor to stellar X-ray emission dependent on close-in planetary mass. Under the hypothesis that this is a consequence of planet-star magnetic field interaction, and energy dissipation, we estimate a possible field strength increase of a factor of {approx}8 between planets of 1 and 10 M{sub J} . Intriguingly, this is consistent with recent geodynamo scaling law predictions. The high-energy photon emission of planet-star systems may therefore provide unique access to the detailed magnetic, and hence geodynamic, properties of exoplanets.

  12. Dynamical features and electric field strengths of double layers driven by currents. [in auroras

    NASA Technical Reports Server (NTRS)

    Singh, N.; Thiemann, H.; Schunk, R. W.

    1985-01-01

    In recent years, a number of papers have been concerned with 'ion-acoustic' double layers. In the present investigation, results from numerical simulations are presented to show that the shapes and forms of current-driven double layers evolve dynamically with the fluctuations in the current through the plasma. It is shown that double layers with a potential dip can form even without the excitation of ion-acoustic modes. Double layers in two-and one-half-dimensional simulations are discussed, taking into account the simulation technique, the spatial and temporal features of plasma, and the dynamical behavior of the parallel potential distribution. Attention is also given to double layers in one-dimensional simulations, and electrical field strengths predicted by two-and one-half-dimensional simulations.

  13. Volcanic sanidinites: an example for the mobilization of high field strength elements (HFSE) in magmatic systems

    NASA Astrophysics Data System (ADS)

    Aßbichler, Donjá; Heuss-Aßbichler, Soraya; Müller, Dirk; Kunzmann, Thomas

    2016-04-01

    In earth science the mobility of high field strength elements (HFSE) is generally discussed in context of hydrothermal processes. Recent investigations mainly address processes in (late) magmatic-, metamorphic- and submarine hydrothermal systems. They have all in common that H2O is main solvent. The transport of HFSE is suggested to be favored by volatiles, like boron, fluorine, phosphate and sulfate (Jiang et al., 2005). In this study processes in magmatic system are investigated. Sanidinites are rare rocks of igneous origin and are found as volcanic ejecta of explosive volcanoes. They consist mainly of sanidine and minerals of the sodalite group. The very porous fabric of these rocks is an indication of their aggregation from a gaseous magmatic phase. The large sanidine crystals (up to several centimeters) are mostly interlocking, creating large cavities between some crystals. In these pores Zr crystallizes as oxide (baddeleyite, ZrO2) or silicate (zircon, ZrSiO4). The euhedral shape of these minerals is a further indication of their formation out of the gas phase. Furthermore, bubbles in glass observed in some samples are evidence for gas-rich reaction conditions during the formation of the sanidinites. The formation of sanidinites is suggested to be an example for solvothermal processes in natural systems. Solvothermal processes imply the solvation, transport and recrystallization of elements in a gas phase. Results obtained from whole rock analysis from sanidinites from Laacher See (Germany) show a positive correlation between LOI, sulfate, Cl, and Na with the HFSE like Zr. Na-rich conditions seem to ameliorate the solvothermal transport of Zr. All these features point to the formation of sanidinites in the upper part of a magma chamber, where fluid consisting of SO3 and Cl compounds in addition to H2O, CO2 and HFSE (high field strength elements) like Zr accumulate.

  14. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics.

    PubMed

    Harwood, Jeremy J; Croston, Judith H; Intema, Huib T; Stewart, Adam J; Ineson, Judith; Hardcastle, Martin J; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W

    2016-06-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths have meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR (LOw Frequency ARray) observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C 452 and 3C 223. We find that the morphology of 3C 452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total energy content of the lobes is greater than previous estimates by a factor of around 5 for 3C 452 and 2 for 3C 223. We go on to discuss possible causes of these steeper-than-expected spectra and provide revised estimates of the internal pressures and magnetic field strengths for the intrinsically steep case. We find that the ratio between the equipartition magnetic field strengths and those derived through synchrotron/inverse-Compton model fitting remains consistent with previous findings and show that the observed departure from equipartition may in some cases provide a solution to the spectral versus dynamical age disparity.

  15. FR II radio galaxies at low frequencies - I. Morphology, magnetic field strength and energetics

    NASA Astrophysics Data System (ADS)

    Harwood, Jeremy J.; Croston, Judith H.; Intema, Huib T.; Stewart, Adam J.; Ineson, Judith; Hardcastle, Martin J.; Godfrey, Leith; Best, Philip; Brienza, Marisa; Heesen, Volker; Mahony, Elizabeth K.; Morganti, Raffaella; Murgia, Matteo; Orrú, Emanuela; Röttgering, Huub; Shulevski, Aleksandar; Wise, Michael W.

    2016-06-01

    Due to their steep spectra, low-frequency observations of Fanaroff-Riley type II (FR II) radio galaxies potentially provide key insights in to the morphology, energetics and spectrum of these powerful radio sources. However, limitations imposed by the previous generation of radio interferometers at metre wavelengths have meant that this region of parameter space remains largely unexplored. In this paper, the first in a series examining FR IIs at low frequencies, we use LOFAR (LOw Frequency ARray) observations between 50 and 160 MHz, along with complementary archival radio and X-ray data, to explore the properties of two FR II sources, 3C 452 and 3C 223. We find that the morphology of 3C 452 is that of a standard FR II rather than of a double-double radio galaxy as had previously been suggested, with no remnant emission being observed beyond the active lobes. We find that the low-frequency integrated spectra of both sources are much steeper than expected based on traditional assumptions and, using synchrotron/inverse-Compton model fitting, show that the total energy content of the lobes is greater than previous estimates by a factor of around 5 for 3C 452 and 2 for 3C 223. We go on to discuss possible causes of these steeper-than-expected spectra and provide revised estimates of the internal pressures and magnetic field strengths for the intrinsically steep case. We find that the ratio between the equipartition magnetic field strengths and those derived through synchrotron/inverse-Compton model fitting remains consistent with previous findings and show that the observed departure from equipartition may in some cases provide a solution to the spectral versus dynamical age disparity.

  16. Relationships between field-based measures of strength and power and golf club head speed.

    PubMed

    Read, Paul J; Lloyd, Rhodri S; De Ste Croix, Mark; Oliver, Jon L

    2013-10-01

    Increased golf club head speed (CHS) has been shown to result in greater driving distances and is also correlated with golf handicap. The purpose of this study was to investigate the relationships between field-based measures of strength and power and golf CHS with a secondary aim to determine the reliability of the selected tests. A correlation design was used to assess the following variables: anthropometrics, squat jump (SJ) height and squat jump peak power (SJPP), unilateral countermovement jump (CMJ) heights (right leg countermovement jump and left leg countermovement jump [LLCMJ]), bilateral CMJ heights, countermovement jump peak power (CMJPP), and medicine ball seated throw (MBST) and medicine ball rotational throw (MBRT). Fouty-eight male subjects participated in the study (age: 20.1 ± 3.2 years, height: 1.76 ± 0.07 m, mass: 72.8 ± 7.8 kg, handicap: 5.8 ± 2.2). Moderate significant correlations were reported between CHS and MBRT (r = 0.67; p < 0.01), MBST (r = 0.63; p < 0.01), CMJPP (r = 0.54; p < 0.01), and SJPP (r = 0.53; p < 0.01). Weak significant correlations (r = 0.3-0.5) were identified between CHS and the other remaining variables excluding LLCMJ. Stepwise multiple regression analysis identified that the MBST and SJ were the greatest predictors of CHS, explaining 49% of the variance. Additionally the intraclass correlation coefficients reported for tests of CHS and all performance variables were deemed acceptable (r = 0.7-0.9). The results of this study suggest that the strength and conditioning coach can accurately assess and monitor the physical abilities of golf athletes using the proposed battery of field tests. Additionally, movements that are more concentrically dominant in nature may display stronger relationships with CHS due to MBST and SJ displaying the highest explained variance after a stepwise linear regression.

  17. 47 CFR 1.544 - Application for broadcast station to conduct field strength measurements and for experimental...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Application for broadcast station to conduct field strength measurements and for experimental operation. 1.544 Section 1.544 Telecommunication... General Filing Requirements § 1.544 Application for broadcast station to conduct field...

  18. Radial transport of large-scale magnetic fields in accretion disks. I. Steady solutions and an upper limit on the vertical field strength

    SciTech Connect

    Okuzumi, Satoshi; Takeuchi, Taku; Muto, Takayuki

    2014-04-20

    Large-scale magnetic fields are key ingredients of magnetically driven disk accretion. We study how large-scale poloidal fields evolve in accretion disks, with the primary aim of quantifying the viability of magnetic accretion mechanisms in protoplanetary disks. We employ a kinematic mean-field model for poloidal field transport and focus on steady states where inward advection of a field balances with outward diffusion due to effective resistivities. We analytically derive the steady-state radial distribution of poloidal fields in highly conducting accretion disks. The analytic solution reveals an upper limit on the strength of large-scale vertical fields attainable in steady states. Any excess poloidal field will diffuse away within a finite time, and we demonstrate this with time-dependent numerical calculations of the mean-field equations. We apply this upper limit to large-scale vertical fields threading protoplanetary disks. We find that the maximum attainable strength is about 0.1 G at 1 AU, and about 1 mG at 10 AU from the central star. When combined with recent magnetic accretion models, the maximum field strength translates into the maximum steady-state accretion rate of ∼10{sup –7} M {sub ☉} yr{sup –1}, in agreement with observations. We also find that the maximum field strength is ∼1 kG at the surface of the central star provided that the disk extends down to the stellar surface. This implies that any excess stellar poloidal field of strength ≳ kG can be transported to the surrounding disk. This might in part resolve the magnetic flux problem in star formation.

  19. Influence of magnetic field strength on potential well in the ionization stage of a double stage Hall thruster

    SciTech Connect

    Yu Daren; Song Maojiang; Liu Hui; Zhang Xu; Li Hong

    2012-07-15

    Similar to a single stage Hall thruster, the magnetic field, which controls electron trajectory and electric field distribution, is the most important factor determining the performance of a double stage Hall thruster. Especially, a potential well, which is helpful to reduce the ion loss on the thruster walls, is shaped in the ionization stage due to the existence of an annular magnetic field topology there. In this paper, the influence of magnetic field strength in the ionization stage on the potential well is researched with both experiments and particle-in-cell simulations. It is found that the depth of potential well increases with the magnetic field strength as a result of enhanced magnetic confinement and lowered electron conductivity. Consequently, the plasma density as well as the ion current entering the acceleration stage increases. However, an excessive magnetic field strength leads to an excess of ion loss on the walls of the acceleration stage. Therefore, there is an appropriate magnetic field strength in the ionization stage that results in a proper potential well and consequently an optimal performance of a double stage Hall thruster.

  20. Location of γ-ray emission and magnetic field strengths in OJ 287

    NASA Astrophysics Data System (ADS)

    Hodgson, J. A.; Krichbaum, T. P.; Marscher, A. P.; Jorstad, S. G.; Rani, B.; Marti-Vidal, I.; Bach, U.; Sanchez, S.; Bremer, M.; Lindqvist, M.; Uunila, M.; Kallunki, J.; Vicente, P.; Fuhrmann, L.; Angelakis, E.; Karamanavis, V.; Myserlis, I.; Nestoras, I.; Chidiac, C.; Sievers, A.; Gurwell, M.; Zensus, J. A.

    2017-01-01

    Context. The γ-ray BL Lac object OJ 287 is known to exhibit inner-parsec "jet-wobbling", high degrees of variability at all wavelengths and quasi-stationary features, including an apparent (≈100°) position-angle change in projection on the sky plane. Aims: Sub-50 micro-arcsecond resolution 86 GHz observations with the global mm-VLBI array (GMVA) supplement ongoing multi-frequency VLBI blazar monitoring at lower frequencies. Using these maps, together with cm/mm total intensity and γ-ray observations from Fermi-LAT from 2008-2014, we aim to determine the location of γ-ray emission and to explain the inner-mas structural changes. Methods: Observations with the GMVA offer approximately double the angular resolution compared with 43 GHz VLBA observations and enable us to observe above the synchrotron self-absorption peak frequency. Fermi-LAT γ-ray data were reduced and analysed. The jet was spectrally decomposed at multiple locations along the jet. From this, we could derive estimates of the magnetic field using equipartition and synchrotron self-absorption arguments. How the field decreases down the jet provided an estimate of the distance to the jet apex and an estimate of the magnetic field strength at the jet apex and in the broad line region. Combined with accurate kinematics, we attempt to locate the site of γ-ray activity, radio flares, and spectral changes. Results: Strong γ-ray flares appeared to originate from either the so-called core region, a downstream stationary feature, or both, with γ-ray activity significantly correlated with radio flaring in the downstream quasi-stationary feature. Magnetic field estimates were determined at multiple locations along the jet, with the magnetic field found to be ≥1.6 G in the core and ≤0.4 G in the downstream quasi-stationary feature. We therefore found upper limits on the location of the VLBI core as ≲6.0 pc from the jet apex and determined an upper limit on the magnetic field near the jet base of the

  1. Levels of electric field strength within the immediate vicinity of FM radio stations in Accra, Ghana.

    PubMed

    Azah, C K; Amoako, J K; Fletcher, J J

    2013-10-01

    Heightened awareness of the ever-expanding use of radiofrequency (RF) techniques and technology has led to mounting concerns from the general public and the scientific community regarding the possible health effects that may arise as a consequence of exposure to RF radiations and has drawn the attention of many researchers the world over. A survey of the RF electromagnetic radiation at public access points in the vicinity of 20 frequency-modulated (FM) radio stations has been made in Accra, Ghana. The fundamental object was to determine the levels of RF fields from FM broadcast antennae within 10-200 m radius about the foot of the FM base station and at a height of 1.5 m above the ground at selected locations. A spectrum analyser and a bi-conical antenna element sensitive and effective within the frequency band of 30-300 MHz were used. Results obtained indicated that the levels of electric field strength ranged from 5.4E-04 V m(-1) at FM station 'O' to 7.4E-08 V m(-1) at FM station 'D'. At a transmission frequency range of 88-108 MHz, the variation of power densities is from 2.5E-10 to 1.5E-17 Wm(-2). These values are very low and are far below the reference level set by the International Commission on Non-Ionizing Radiation Protection and therefore do not pose any known hazard to the inhabitants of Accra, Ghana. The electric field levels presented in this work are comparable with those reported from epidemiological studies conducted elsewhere.

  2. Nuclear magnetic resonance relaxation and diffusion in the presence of internal gradients: the effect of magnetic field strength.

    PubMed

    Mitchell, J; Chandrasekera, T C; Johns, M L; Gladden, L F; Fordham, E J

    2010-02-01

    It is known that internal magnetic field gradients in porous materials, caused by susceptibility differences at the solid-fluid interfaces, alter the observed effective Nuclear Magnetic Resonance transverse relaxation times T2,eff. The internal gradients scale with the strength of the static background magnetic field B0. Here, we acquire data at various magnitudes of B0 to observe the influence of internal gradients on T2-T2 exchange measurements; the theory discussed and observations made are applicable to any T2-T2 analysis of heterogeneous materials. At high magnetic field strengths, it is possible to observe diffusive exchange between regions of local internal gradient extrema within individual pores. Therefore, the observed exchange pathways are not associated with pore-to-pore exchange. Understanding the significance of internal gradients in transverse relaxation measurements is critical to interpreting these results. We present the example of water in porous sandstone rock and offer a guideline to determine whether an observed T2,eff relaxation time distribution reflects the pore size distribution for a given susceptibility contrast (magnetic field strength) and spin echo separation. More generally, we confirm that for porous materials T1 provides a better indication of the pore size distribution than T2,eff at high magnetic field strengths (B0>1 T), and demonstrate the data analysis necessary to validate pore size interpretations of T2,eff measurements.

  3. Semiclassical circular strings in AdS{sub 5} and 'long' gauge field strength operators

    SciTech Connect

    Park, I.Y.; Tirziu, A.; Tseytlin, A.A.

    2005-06-15

    We consider circular strings rotating with equal spins S{sub 1}=S{sub 2}=S in two orthogonal planes in AdS{sub 5} and suggest that they may be dual to long gauge-theory operators built out of self-dual components of gauge field strength. As was found in hep-th/0404187, the one-loop anomalous dimensions of the such gauge-theory operators are described by an antiferromagnetic XXX{sub 1} spin chain and scale linearly with length L>>1. We find that in the case of rigid rotating string both the classical energy E{sub 0} and the 1-loop string correction E{sub 1} depend linearly on the spin S (within the stability region of the solution). This supports the identification of the rigid rotating string with the gauge-theory operator corresponding to the maximal-spin (ferromagnetic) state of the XXX{sub 1} spin chain. The energy of more general rotating and pulsating strings also happens to scale linearly with both the spin and the oscillation number. Such solutions should be dual to other lower-spin states of the spin chain, with the antiferromagnetic ground state presumably corresponding to the string pulsating in two planes with no rotation.

  4. Magnetic resonance elastography: A comparison between pulse sequences across field strengths

    NASA Astrophysics Data System (ADS)

    Owen, Graham

    Several Magnetic Resonance Elastography (MRE) techniques have been developed to non-invasively measure tissue stiffness which can be altered by disease processes such as liver fibrosis. Different MRE sequences are needed to fill various roles clinically such as spin-echo based sequences for patients with iron overload, or rapid sequences for patients who cannot execute long breath holds. The purpose of this study was to compare the mean stiffness, variance, and presence of artifacts using three MRE sequences at 1.5T and 3T in phantoms and healthy volunteers. In the phantom study variance was found to decrease with increasing slice thickness as well as at higher field strength. The SE-EPI sequence tended to overestimate low stiffness and underestimate high stiffness while the rapid sequence significantly overestimated stiffness of both the soft and stiff phantom. In the volunteers no significant difference was found between the sequences in terms of measured stiffness. The variability between acquisitions in a single setup as well as between setups was minimal, showing that MRE is a very robust technique.

  5. Electrochemical properties of columns in capillary electrochromatography. I. Ohm's law, resistivity and field strength.

    PubMed

    Henry, Michael P; Ratnayake, Chitra K

    2005-06-24

    The most commonly used type of column in capillary electrochromatography (CEC) consists of a packed segment and an open (but buffer-filled) segment. The two segments differ importantly in two respects: firstly, their electrical resistivity; and secondly, their zeta potentials at a multitude of solid-liquid interfaces. Determination of the magnitude of these properties for each segment cannot be made using only results from the column as a whole. Instead, measurements of resistivity and zeta potentials of an entirely open, unpacked column can be used in conjunction with those of the CEC column to determine the electrochemical nature of both segments. This review of basic electrochemical properties will describe simple procedures that can be used to determine resistance, resistivity, conductivity, conductance, and field strength in each segment. In addition, it will be shown how the properties of each segment add together to give the same properties of the CEC column as a whole. The equations so derived will be applied to data from the literature and conclusions drawn from the results.

  6. Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

    SciTech Connect

    Han, K.; Embury, J.D.

    1998-10-01

    This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.

  7. A fast parallel code for calculating energies and oscillator strengths of many-electron atoms at neutron star magnetic field strengths in adiabatic approximation

    NASA Astrophysics Data System (ADS)

    Engel, D.; Klews, M.; Wunner, G.

    2009-02-01

    We have developed a new method for the fast computation of wavelengths and oscillator strengths for medium-Z atoms and ions, up to iron, at neutron star magnetic field strengths. The method is a parallelized Hartree-Fock approach in adiabatic approximation based on finite-element and B-spline techniques. It turns out that typically 15-20 finite elements are sufficient to calculate energies to within a relative accuracy of 10-5 in 4 or 5 iteration steps using B-splines of 6th order, with parallelization speed-ups of 20 on a 26-processor machine. Results have been obtained for the energies of the ground states and excited levels and for the transition strengths of astrophysically relevant atoms and ions in the range Z=2…26 in different ionization stages. Catalogue identifier: AECC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECC_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3845 No. of bytes in distributed program, including test data, etc.: 27 989 Distribution format: tar.gz Programming language: MPI/Fortran 95 and Python Computer: Cluster of 1-26 HP Compaq dc5750 Operating system: Fedora 7 Has the code been vectorised or parallelized?: Yes RAM: 1 GByte Classification: 2.1 External routines: MPI/GFortran, LAPACK, PyLab/Matplotlib Nature of problem: Calculations of synthetic spectra [1] of strongly magnetized neutron stars are bedevilled by the lack of data for atoms in intense magnetic fields. While the behaviour of hydrogen and helium has been investigated in detail (see, e.g., [2]), complete and reliable data for heavier elements, in particular iron, are still missing. Since neutron stars are formed by the collapse of the iron cores of massive stars, it may be assumed that their atmospheres contain an iron plasma. Our objective is to fill the gap

  8. MAGNETIC FIELD STRENGTH FLUCTUATIONS IN THE HELIOSHEATH: VOYAGER 1 OBSERVATIONS DURING 2009

    SciTech Connect

    Burlaga, L. F.; Ness, N. F. E-mail: nfnudel@yahoo.com

    2012-01-01

    We analyze the ''microscale fluctuations'' of the magnetic field strength B on a scale of several hours observed by Voyager1 (V1) in the heliosheath during 2009. The microscale fluctuations of B range from coherent to stochastic structures. The amplitude of microscale fluctuations of B during 1 day is measured by the standard deviation (SD) of 48 s averages of B. The distribution of the daily values of SD is lognormal. SD(t) from day of year (DOY) 1 to 331, 2009, is very intermittent. SD(t) has a 1/f or 'pink noise' spectrum on scales from 1 to 100 days, and it has a broad multifractal spectrum f({alpha}) with 0.57 {<=} {alpha} {<=} 1.39. The time series of increments SD(t + {tau}) - SD(t) has a pink noise spectrum with {alpha}' = 0.88 {+-} 0.14 on scales from 1 to 100 days. The increments have a Tsallis (q-Gaussian) distribution on scales from 1 to 165 days, with an average q = 1.75 {+-} 0.12. The skewness S and kurtosis K have Gaussian and lognormal distributions, respectively. The largest spikes in K(t) and S(t) are often associated with a change in B across a data gap and with identifiable physical structures. The 'turbulence' observed by V1 during 2009 was weakly compressible on average but still very intermittent, highly variable, and highly compressible at times. The turbulence observed just behind the termination shock by Voyager 2 was twice as strong. These observations place strong constraints on any model of 'turbulence' in the heliosheath.

  9. Magnetic Field Strength Fluctuations in the Heliosheath: Voyager 1 Observations during 2009

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Ness, N. F.

    2011-01-01

    We analyze the "microscale fluctuations" of the magnetic field strength Beta on a scale of several hours observed by Voyager I (VI) in the heliosheath during 2009. The microscale fluctuations of Beta range from coherent to stochastic structures. The amplitude of microscale fluctuations of Beta during 1 day is measured by the standard deviation (SD) of 48 s averages of B. The distribution of the daily values of SD is lognormal. SD(t) from day of year (DOY) I to 331, 2009, is very intermittent. SD(t) has a 1/f or "pink noise" spectrum on scales from I to 100 days, and it has a broad multi fractal spectrum f(alpha) with 0.57 much < alpha much < 1.39. The time series of increments SD(t + r) - SD(t) has a pink noise spectrum with alpha' = 0.88 +/- 0.14 on scales from 1 to 100 days. The increments have a Tsallis (q-Gaussian) distribution on scales from 1 to 165 days, with an average q = 1.75 +/- 0.12. The skewness S and kurtosis K have Gaussian and lognormal distributions, respectively. The largest spikes in K(t) and Set) are often associated with a change in Beta across a data gap and with identifiable physical structures. The "turbulence" observed by VI during 2009 was weakly compressible on average but still very intermittent, highly variable, and highly compressible at times. The turbulence observed just behind the termination shock by Voyager 2 was twice as strong. These observations place strong constraints on any model of "turbulence" in the heliosheath.

  10. Magnetic Field Strength Fluctuations in the Heliosheath: Voyager 1 Observations During 2009

    NASA Technical Reports Server (NTRS)

    Brulaga, L. F.; Ness, N. F.

    2012-01-01

    We analyze the microscale fluctuations of the magnetic field strength B on a scale of several hours observed by Voyager1 (V1) in the heliosheath during 2009. The microscale fluctuations of B range from coherent to stochastic structures. The amplitude of microscale fluctuations of B during 1 day is measured by the standard deviation (SD) of 48 s averages of B. The distribution of the daily values of SD is lognormal. SD(t) from day of year (DOY) 1 to 331, 2009, is very intermittent. SD(t) has a 1/f or "pink noise" spectrum on scales from 1 to 100 days, and it has a broad multifractal spectrum f(alpha) with 0.57 less than or equal to alpha less than or equal to 1.39. The time series of increments SD(t + tau) -- SD(t) has a pink noise spectrum with alpha(1) = 0.88 plus or minus 0.14 on scales from 1 to 100 days. The increments have a Tsallis (q-Gaussian) distribution on scales from 1 to 165 days, with an average q = 1.75 plus or minus 0.12. The skewness S and kurtosis K have Gaussian and lognormal distributions, respectively. The largest spikes in K(t) and S(t) are often associated with a change in B across a data gap and with identifiable physical structures. The "turbulence" observed by V1 during 2009 was weakly compressible on average but still very intermittent, highly variable, and highly compressible at times. The turbulence observed just behind the termination shock by Voyager 2 was twice as strong. These observations place strong constraints on any model of turbulence in the heliosheath.

  11. Effect of temperature on the uniform field breakdown strength of electronegative gases

    SciTech Connect

    Christophorou, L.G.; Mathis, R.A.; Hunter, S.R.; Carter, J.G.

    1987-03-01

    In general, the electron attachment rate constant, k/sub a/ (,UPSILON), as a function of the mean electron energy and temperature UPSILON for electronegative gases which attach electrons nondissociatively decreases greatly with UPSILON from room temperature to UPSILON less than or equal to 600K, while that for electronegative gases which attach electrons dissociatively increases with increasing UPSILON. Based on recent studies in our laboratory on k/sub a/ (,UPSILON), we investigated the variation with UPSILON (approx.295-575K) of the uniform field breakdown strength, (E/N)/sub lim/, for three classes of electronegative gases: (a) gases such as c-C/sub 4/F/sub 8/ (and c-C/sub 4/F/sub 6/, 1-C/sub 3/F/sub 6/) which attach strongly low-energy (less than or equal to 1 eV) electrons nondissociatively and for which k/sub a/ (,UPSILON), decreases precipitously with UPSILON above ambient; (b) gases such as C/sub 2/F/sub 6/ and CF/sub 3/Cl which attach electrons exclusively dissociatively and whose k/sub a/ (,UPSILON) increases with UPSILON; and (c) gases such as C/sub 3/F/sub 8/ and n-C/sub 4/F/sub 10/ which attach electrons both nondissociatively and dissociatively over a common low-energy range and whose k/sub a/ (,UPSILON) first decreases and then increases with UPSILON above ambient. The (E/N)/sub lim/(UPSILON) has been found to decrease significantly with UPSILON for (a), to decrease slowly with UPSILON for (c), and to increase slightly with UPSILON for (b). These changes in (E/N)/sub lim/ follow those in k/sub a/ (,UPSILON). A similar behavior is expected for other electronegative gaseous dielectrics in the respective three groups.

  12. On the nature of the magnetic Rayleigh-Taylor instability in astrophysical plasma: the case of uniform magnetic field strength

    NASA Astrophysics Data System (ADS)

    Hillier, Andrew S.

    2016-10-01

    The magnetic Rayleigh-Taylor instability has been shown to play a key role in many astrophysical systems. The equation for the growth rate of this instability in the incompressible limit, and the most-unstable mode that can be derived from it, are often used to estimate the strength of the magnetic field that is associated with the observed dynamics. However, there are some issues with the interpretations given. Here, we show that the class of most unstable modes ku for a given θ, the class of modes often used to estimate the strength of the magnetic field from observations, for the system leads to the instability growing as σ2 = 1/2Agku, a growth rate which is independent of the strength of the magnetic field and which highlights that small scales are preferred by the system, but not does not give the fastest growing mode for that given k. We also highlight that outside of the interchange (k ṡ B = 0) and undular (k parallel to B) modes, all the other modes have a perturbation pair of the same wavenumber and growth rate that when excited in the linear regime can result in an interference pattern that gives field aligned filamentary structure often seen in 3D simulations. The analysis was extended to a sheared magnetic field, where it was found that it was possible to extend the results for a non-sheared field to this case. We suggest that without magnetic shear it is too simplistic to be used to infer magnetic field strengths in astrophysical systems.

  13. Dust coagulation and magnetic field strength in a planet-induced gap subject to MRI turbulence

    NASA Astrophysics Data System (ADS)

    Carballido, Augusto; Matthews, Lorin; Hyde, Truell

    2017-01-01

    We investigate the coagulation of dust particles in and around a gap opened by a Jupiter-mass planet. To this end, we carry out a high-resolution magnetohydrodynamic (MHD) simulation of the gap environment, which is turbulent due to the magneto rotational instability. From the MHD simulation, we obtain values of the gas velocities, densities and turbulent stresses close to the gap edge, in one of the two gas streams that accrete onto the planet, and inside the low-density gap. The MHD values are then supplied to a Monte Carlo dust coagulation algorithm, which models grain sticking, compaction and bouncing. We consider two dust populations for each region: one whose initial size distribution is monodisperse, with monomer radius equal to 1 micron, and another one whose initial size distribution follows the Mathis-Rumpl-Nordsieck distribution for interstellar dust grains, with an initial range of monomer radii between 0.5 and 10 microns. Without bouncing, our Monte Carlo calculations show steady growth of dust aggregates in all regions, and the mass-weighted (MW) average porosity of the initially mono disperse population reaches extremely high final values of 98%. The final MW porosities in all other cases without bouncing range from 30% to 82%. The efficiency of compaction is due to high turbulent relative speeds between dust particles. When bouncing is introduced, growth is slowed down in the planetary wake and inside the gap.We also analyze the strength of the magnetic field threading the gaps opened by planets of different sub-Jovian masses. Preliminary results show that, in a gap opened by a large-mass planet (~ 1 MJ), the time-averaged radial profile of the vertical component of the field (Bz) increases sharply inside the gap, and less sharply in the case of less massive planets. In gaps opened by intermediate-mass planets (~ 0.5 — 0.75 MJ), the radial profile of Bz exhibits local maxima in the vicinity of the planet, but not at the gap center.

  14. BIPOLAR JETS LAUNCHED FROM MAGNETICALLY DIFFUSIVE ACCRETION DISKS. I. EJECTION EFFICIENCY VERSUS FIELD STRENGTH AND DIFFUSIVITY

    SciTech Connect

    Sheikhnezami, Somayeh; Fendt, Christian; Porth, Oliver; Vaidya, Bhargav; Ghanbari, Jamshid E-mail: fendt@mpia.de

    2012-09-20

    We investigate the launching of jets and outflows from magnetically diffusive accretion disks. Using the PLUTO code, we solve the time-dependent resistive magnetohydrodynamic equations taking into account the disk and jet evolution simultaneously. The main question we address is which kind of disks launch jets and which kind of disks do not? In particular, we study how the magnitude and distribution of the (turbulent) magnetic diffusivity affect mass loading and jet acceleration. We apply a turbulent magnetic diffusivity based on {alpha}-prescription, but also investigate examples where the scale height of diffusivity is larger than that of the disk gas pressure. We further investigate how the ejection efficiency is governed by the magnetic field strength. Our simulations last for up to 5000 dynamical timescales corresponding to 900 orbital periods of the inner disk. As a general result, we observe a continuous and robust outflow launched from the inner part of the disk, expanding into a collimated jet of superfast-magnetosonic speed. For long timescales, the disk's internal dynamics change, as due to outflow ejection and disk accretion the disk mass decreases. For magnetocentrifugally driven jets, we find that for (1) less diffusive disks, (2) a stronger magnetic field, (3) a low poloidal diffusivity, or (4) a lower numerical diffusivity (resolution), the mass loading of the outflow is increased-resulting in more powerful jets with high-mass flux. For weak magnetization, the (weak) outflow is driven by the magnetic pressure gradient. We consider in detail the advection and diffusion of magnetic flux within the disk and we find that the disk and outflow magnetization may substantially change in time. This may have severe impact on the launching and formation process-an initially highly magnetized disk may evolve into a disk of weak magnetization which cannot drive strong outflows. We further investigate the jet asymptotic velocity and the jet rotational velocity in

  15. Electric-field strength and doping level controlled spin-valley transport in a silicene np junction

    NASA Astrophysics Data System (ADS)

    Hua, Tao; Zhai, Xuechao; Yang, Zhihong; Wang, Shendong; Li, Bin

    2016-10-01

    The performance of np junction, as the basic unit of electronic devices, often determines the prospect of a material. We here investigate the spin- and valley-polarized transport in a silicene np junction, where a ferromagnetic field and a perpendicular electric field are applied in the p-doped region. It is found that pure spin current with valley polarization can be obtained under the control of electric-field strength and doping level, arising from the specific dispersion with spin- and valley-polarizations. By tuning the electric field properly, one can even realize a controllable state that supports 100% spin- and valley-polarized transport. At fixed electric field, we also demonstrate that the ferromagnetic field can greatly affect the ratios of spin- and valley-polarizations. These findings suggest that silicene is a promising material for application in future spintronics and valleytronics devices.

  16. Correlation of the 27-day variation of cosmic rays to the interplanetary magnetic field strength

    NASA Astrophysics Data System (ADS)

    Sabbah, I.

    2001-08-01

    We analyze cosmic ray data as well as interplanetary magnetic field (IMF) data, to examine the relation and correlation between their 27-day variations during the time interval 1965-1995. The amplitude of the 27day variation of galactic cosmic rays is linearly correlated with: the IMF strength (B), the z-component (Bz) of the IMF vector and the product of the solar wind speed (V) times B (VB). It is well correlated with the heliospheric current sheet tiltangle.Thecross-correlationfunctionofthe27-daycosmic ray variation versus the solar wind speed shows a negative correlation. The solar wind speed leads the cosmic ray variation by 2 years. The 27-day variation of cosmic rays is correlated with the variation in both the xand y-components of the IMF, it lags with 3-5 years. 1. Introduction Galactic cosmic rays are modulated (modified) through their propagation in the heliosphere by the effect of the large scale structure of the interplanetary medium. A wavy structured neutralcurrentsheet(NCS) separatesthe heliosphereintotwo regions of opposite magnetic polarity. During positive magnetic phase, the interplanetary magnetic field (IMF) is directed away from the Sun above the NCS and toward the Sun south of it. During negative magnetic phase the IMF direction is reversed. The angle between the Sun's equatorial plane and the NCS is referred as the tilt angle R, of the neutral sheet. It exhibits a solar activity dependence, R is small near sunspot minimum and large near solar maximum. The 27-day variations of galactic cosmic rays have been related to the changing position of the interplanetary NCS (Swinson and Yasue, 1992; Valdes-Galicia and Dorman, 1997). Here we examine the effect of the interplanetary parameters upon the 27-day variation of galactic cosmic rays during the last three solar cycles. 2. Solar Cycle Dependance We used hourly averaged cosmic ray counts observed with neutron monitors at Deep River (DR) and Huancayo (HU) and muon surface telescope at Nagoya (NA

  17. Atomic-level Pseudo-degeneracy of Atomic Levels Giving Transitions Induced by Magnetic Fields, of Importance for Determining the Field Strengths in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Li, Wenxian; Yang, Yang; Tu, Bingsheng; Xiao, Jun; Grumer, Jon; Brage, Tomas; Watanabe, Tetsuya; Hutton, Roger; Zou, Yaming

    2016-08-01

    We present a measured value for the degree of pseudo-degeneracy between two fine-structure levels in Fe9+ from line intensity ratios involving a transition induced by an external magnetic field. The extracted fine-structure energy difference between the 3{p}43d{}4{D}5/2 and {}4{D}7/2 levels, where the latter is the upper state for the magnetic-field induced line, is needed in our recently proposed method to measure magnetic-field strengths in the solar corona. The intensity of the 3{p}43d{}4{D}7/2\\to 3{p}5{}2{P}3/2 line at 257.262 Å is sensitive to the magnetic field external to the ion. This sensitivity is in turn strongly dependent on the energy separation in the pseudo-degeneracy through the mixing induced by the external magnetic field. Our measurement, which uses an Electron Beam Ion Trap with a known magnetic-field strength, indicates that this energy difference is 3.5 cm-1. The high abundance of Fe9+ and the sensitivity of the line’s transition probability to field strengths below 0.1 T opens up the possibility of diagnosing coronal magnetic fields. We propose a new method to measure the magnetic field in the solar corona, from similar intensity ratios in Fe9+. In addition, the proposed method to use the line ratio of the blended line 3{p}43d{}4{D}7/{2,5/2}\\to 3{p}5{}2{P}3/2 with another line from Fe x as the density diagnostic should evaluate the effect of the magnetic-field-induced transition line.

  18. Dielectric strength, swelling and weight loss of the ITER Toroidal Field Model Coil insulation after low temperature reactor irradiation

    NASA Astrophysics Data System (ADS)

    Humer, K.; Weber, H. W.; Hastik, R.; Hauser, H.; Gerstenberg, H.

    2000-04-01

    The insulation system for the Toroidal Field Model Coil of ITER is a fiber reinforced plastic (FRP) laminate, which consists of a combined Kapton/R-glass-fiber reinforcement tape, vacuum-impregnated with an epoxy DGEBA system. Pure disk shaped laminates, FRP/stainless-steel sandwiches, and conductor insulation prototypes were irradiated at 5 K in a fission reactor up to a fast neutron fluence of 10 22 m -2 ( E>0.1 MeV) to investigate the radiation induced degradation of the dielectric strength of the insulation system. After warm-up to room temperature, swelling, weight loss, and the breakdown strength were measured at 77 K. The sandwich swells by 4% at a fluence of 5×10 21 m-2 and by 9% at 1×10 22 m-2. The weight loss of the FRP is 2% at 1×10 22 m-2. The dielectric strength remained unchanged over the whole dose range.

  19. ROLE OF MAGNETIC FIELD STRENGTH AND NUMERICAL RESOLUTION IN SIMULATIONS OF THE HEAT-FLUX-DRIVEN BUOYANCY INSTABILITY

    SciTech Connect

    Avara, Mark J.; Reynolds, Christopher S.; Bogdanovic, Tamara E-mail: chris@astro.umd.edu

    2013-08-20

    The role played by magnetic fields in the intracluster medium (ICM) of galaxy clusters is complex. The weakly collisional nature of the ICM leads to thermal conduction that is channeled along field lines. This anisotropic heat conduction profoundly changes the instabilities of the ICM atmosphere, with convective stabilities being driven by temperature gradients of either sign. Here, we employ the Athena magnetohydrodynamic code to investigate the local non-linear behavior of the heat-flux-driven buoyancy instability (HBI) relevant in the cores of cooling-core clusters where the temperature increases with radius. We study a grid of two-dimensional simulations that span a large range of initial magnetic field strengths and numerical resolutions. For very weak initial fields, we recover the previously known result that the HBI wraps the field in the horizontal direction, thereby shutting off the heat flux. However, we find that simulations that begin with intermediate initial field strengths have a qualitatively different behavior, forming HBI-stable filaments that resist field-line wrapping and enable sustained vertical conductive heat flux at a level of 10%-25% of the Spitzer value. While astrophysical conclusions regarding the role of conduction in cooling cores require detailed global models, our local study proves that systems dominated by the HBI do not necessarily quench the conductive heat flux.

  20. The high field strength element budget of atmospheric aerosols (puy de Dôme, France)

    NASA Astrophysics Data System (ADS)

    Vlastelic, Ivan; Suchorski, Krzysztof; Sellegri, Karine; Colomb, Aurélie; Nauret, François; Bouvier, Laetitia; Piro, Jean-Luc

    2015-10-01

    High field strength elements (HFSE), including Zr, Hf, Nb, Ta and Ti have low solubility in aqueous fluids and partition into dense and resistant minerals. HFSE proved useful in studying terrestrial weathering and sediment transport, but little is known about their behavior during atmospheric processes, which play an important role in global sedimentary cycles. The atmospheric budget of HFSE is evaluated from the sequential dissolution of aerosol samples collected between 2011 and 2014 at puy de Dôme (1465 m elevation, French Massif Central). Aerosols were sampled during nighttime, while the site is generally located above the planetary boundary layer. Systematic, partial recovery of HFSE during gentle dissolution of aerosols indicates that resistant minerals are ubiquitous in air samples. Total dissolution of aerosols in pressure vessels reveals that Zr and Hf occur on average in sub-crustal abundance, which is consistent with the sampling site being dominantly influenced by oceanic air masses depleted in zircons. Conversely, zircon excess occasionally occurs in continental air masses, in particular those originating from northern Africa. Overall, the Hf/Nd ratio, a proxy for zircon fractionation, varies from 0.26 to 3.94 times the Upper Continental Crust (UCC) value, encompassing the range of worldwide loess. This wide compositional range is consistent with (1) the occurrence of coarse zircons (10-30 μm) in dust source, with possible local enrichments relative to bulk UCC in residual wind-winnowed soils, and (2) gravitational settling of coarse zircons during long-distance (>ca. 1000 km) transport. Niobium and Ta are systematically more abundant (by a mean factor of ∼3) in puy de Dôme aerosols than expected from average crustal or soil concentrations. The volume-weighted average Nb/Ta ratio of 15.5 ± 2.6 (1σ) is also higher than in bulk UCC (11.4-13.3). The positive Nb-Ta anomaly of free troposphere aerosols unlikely reflects a net Nb-Ta enrichment but

  1. Magnetic nanoparticles with high specific absorption rate of electromagnetic energy at low field strength for hyperthermia therapy.

    PubMed

    Shubitidze, Fridon; Kekalo, Katsiaryna; Stigliano, Robert; Baker, Ian

    2015-03-07

    Magnetic nanoparticles (MNPs), referred to as the Dartmouth MNPs, which exhibit high specific absorption rate at low applied field strength have been developed for hyperthermia therapy applications. The MNPs consist of small (2-5 nm) single crystals of gamma-Fe2O3 with saccharide chains implanted in their crystalline structure, forming 20-40 nm flower-like aggregates with a hydrodynamic diameter of 110-120 nm. The MNPs form stable (>12 months) colloidal solutions in water and exhibit no hysteresis under an applied quasistatic magnetic field, and produce a significant amount of heat at field strengths as low as 100 Oe at 99-164 kHz. The MNP heating mechanisms under an alternating magnetic field (AMF) are discussed and analyzed quantitatively based on (a) the calculated multi-scale MNP interactions obtained using a three dimensional numerical model called the method of auxiliary sources, (b) measured MNP frequency spectra, and (c) quantified MNP friction losses based on magneto-viscous theory. The frequency responses and hysteresis curves of the Dartmouth MNPs are measured and compared to the modeled data. The specific absorption rate of the particles is measured at various AMF strengths and frequencies, and compared to commercially available MNPs. The comparisons demonstrate the superior heating properties of the Dartmouth MNPs at low field strengths (<250 Oe). This may extend MNP hyperthermia therapy to deeper tumors that were previously non-viable targets, potentially enabling the treatment of some of the most difficult cancers, such as pancreatic and rectal cancers, without damaging normal tissue.

  2. Magnetic nanoparticles with high specific absorption rate of electromagnetic energy at low field strength for hyperthermia therapy

    NASA Astrophysics Data System (ADS)

    Shubitidze, Fridon; Kekalo, Katsiaryna; Stigliano, Robert; Baker, Ian

    2015-03-01

    Magnetic nanoparticles (MNPs), referred to as the Dartmouth MNPs, which exhibit high specific absorption rate at low applied field strength have been developed for hyperthermia therapy applications. The MNPs consist of small (2-5 nm) single crystals of gamma-Fe2O3 with saccharide chains implanted in their crystalline structure, forming 20-40 nm flower-like aggregates with a hydrodynamic diameter of 110-120 nm. The MNPs form stable (>12 months) colloidal solutions in water and exhibit no hysteresis under an applied quasistatic magnetic field, and produce a significant amount of heat at field strengths as low as 100 Oe at 99-164 kHz. The MNP heating mechanisms under an alternating magnetic field (AMF) are discussed and analyzed quantitatively based on (a) the calculated multi-scale MNP interactions obtained using a three dimensional numerical model called the method of auxiliary sources, (b) measured MNP frequency spectra, and (c) quantified MNP friction losses based on magneto-viscous theory. The frequency responses and hysteresis curves of the Dartmouth MNPs are measured and compared to the modeled data. The specific absorption rate of the particles is measured at various AMF strengths and frequencies, and compared to commercially available MNPs. The comparisons demonstrate the superior heating properties of the Dartmouth MNPs at low field strengths (<250 Oe). This may extend MNP hyperthermia therapy to deeper tumors that were previously non-viable targets, potentially enabling the treatment of some of the most difficult cancers, such as pancreatic and rectal cancers, without damaging normal tissue.

  3. Magnetic nanoparticles with high specific absorption rate of electromagnetic energy at low field strength for hyperthermia therapy

    PubMed Central

    Stigliano, Robert; Baker, Ian

    2015-01-01

    Magnetic nanoparticles (MNPs), referred to as the Dartmouth MNPs, which exhibit high specific absorption rate at low applied field strength have been developed for hyperthermia therapy applications. The MNPs consist of small (2–5 nm) single crystals of gamma-Fe2O3 with saccharide chains implanted in their crystalline structure, forming 20–40 nm flower-like aggregates with a hydrodynamic diameter of 110–120 nm. The MNPs form stable (>12 months) colloidal solutions in water and exhibit no hysteresis under an applied quasistatic magnetic field, and produce a significant amount of heat at field strengths as low as 100 Oe at 99–164 kHz. The MNP heating mechanisms under an alternating magnetic field (AMF) are discussed and analyzed quantitatively based on (a) the calculated multi-scale MNP interactions obtained using a three dimensional numerical model called the method of auxiliary sources, (b) measured MNP frequency spectra, and (c) quantified MNP friction losses based on magneto-viscous theory. The frequency responses and hysteresis curves of the Dartmouth MNPs are measured and compared to the modeled data. The specific absorption rate of the particles is measured at various AMF strengths and frequencies, and compared to commercially available MNPs. The comparisons demonstrate the superior heating properties of the Dartmouth MNPs at low field strengths (<250 Oe). This may extend MNP hyperthermia therapy to deeper tumors that were previously non-viable targets, potentially enabling the treatment of some of the most difficult cancers, such as pancreatic and rectal cancers, without damaging normal tissue. PMID:25825545

  4. Long-term Trends in Interplanetary Magnetic Field Strength and Solar Wind Structure during the 20th Century

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cliver, E. W.; Cane, H. V.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Lockwood et al have recently reported an approximately 40% increase in the radial component of the interplanetary magnetic field (IMF) at Earth between 1964 and 1996. We argue that this increase does not constitute a secular trend but is largely the consequence of lower than average fields during solar cycle 20 (1964-1976) in comparison with surrounding cycles. For times after 1976 the average IMF strength has actually decreased slightly. Examination of the cosmic ray intensity, an indirect measure of the IMF strength, over the last five solar cycles (19-23) also indicates that cycle averages of the IMF strength have been relatively constant since approximately 1954. We also consider the origin of the well-documented increase in the geomagnetic alphaalpha index that occurred primarily during the first half of the twentieth century. We surmise that the coronal mass ejection (CME) rate for recent solar cycles was approximately twice as high as that for solar cycles 100 years ago. However, this change in the CME rate and the accompanying increase in 27-day recurrent storm activity reported by others are unable to account completely for the increase in alphaalpha. Rather, the CMEs and recurrent high-speed streams at the beginning of the twentieth century must have been embedded in a background of slow solar wind that was less geoeffective (having, for example, lower IMF strength and/or flow speed) than its modern counterpart.

  5. Mineralogic reservoirs for high-field strength elements in deeply subducted continental sediments

    NASA Astrophysics Data System (ADS)

    Rapp, R. P.; Shimizu, N.; Irifune, T.; Nishiyama, N.

    2013-12-01

    For more than 40 years now, mantle geochemists have interpreted the isotopic signature of ocean-island basalts (OIB) in terms of deeply recycled crustal lithologies, including terrigeneous sediments, being transported via subduction into the source region for mantle plumes, which reside in the transition zone (MTZ) and/or lower mantle. As such, continent-derived sediments in particular represent domains of extreme isotopic and trace-element heterogeneity relative to the deep primitive mantle (PM). In an effort to understand the extent to which the original geochemical signature of deeply subducted continental material is preserved, and to determine which mineral phases act as reservoirs for transporting key trace-elements (e.g., large-ion lithophile elements, LILE; high-field strength elements, HFSE) into the deep mantle, we have conducted a series of phase-equilibria multi-anvil experiments on natural terrigeneous sediments at pressures appropriate to the base of the MTZ and uppermost lower mantle. The starting materials for these experiments contain modest amounts of water, and a small carbonate component, and their major- and trace-element composition are a close approximation to that of average 'global subducting sediment' (i.e., GLOSS; Plank and Langmuir, 1998). Experiments were conducted over the pressure range ~15-23 GPa, and temperatures between ~1200-1800°C. Below ~22 GPa, the high-pressure phase assemblage consists of K-hollandite, majoritic garnet, stishovite, and depending on temperature, either a hydrous alumino-silicate (e.g., phase-EGG or δ-AlOOH), or kyanite or corundum. Stable accessory minerals at these conditions include rutile, and zircon, where much of the whole-rock complement of HFSE resides, and occasionally monazite. At higher pressure (>23 GPa), the breakdown of garnet produces a Fe-Al-Mg perovskite phase, which is exceptionally rich in TiO2 (up to 9 wt%), and the aforementioned accessory phases are no longer stable. The full phase

  6. The IDV Index: Its Derivation and Use in Inferring Long-Term Variations of the Interplanetary Magnetic Field Strength

    DTIC Science & Technology

    2005-12-13

    day solar A preliminary report of our results has been published minimum interval examined, Mayaud was "astonished" elsewhere [Svalgaard et al, 2003... 2020 Figure 7. Inferred (reconstructed) near-Earth interplanetary magnetic field strength, B since 1872 (blue curve). Before 1890 (light blue), B is...IDV) P(sqr (ql ()) B(obs) B(guess) 0 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 Figure 9. Variation of yearly

  7. Aggregate tensile strength and friability characteristics of furrow and sprinkler irrigated fields in Southern Idaho

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural crops grown in southern Idaho are furrow or sprinkler irrigated. Therefore, the soil experiences several wetting and drying cycles each growing season that can contribute to changes in aggregate tensile strength and friability. The objective of the research was to evaluate the influence...

  8. Relationship of magnetic field strength and brightness of fine-structure elements in the solar temperature minimum region

    NASA Technical Reports Server (NTRS)

    Cook, J. W.; Ewing, J. A.

    1990-01-01

    A quantitative relationship was determined between magnetic field strength (or magnetic flux) from photospheric magnetograph observations and the brightness temperature of solar fine-structure elements observed at 1600 A, where the predominant flux source is continuum emission from the solar temperature minimum region. A Kitt Peak magnetogram and spectroheliograph observations at 1600 A taken during a sounding rocket flight of the High Resolution Telescope and Spectrograph from December 11, 1987 were used. The statistical distributions of brightness temperature in the quiet sun at 1600 A, and absolute value of magnetic field strength in the same area were determined from these observations. Using a technique which obtains the best-fit relationship of a given functional form between these two histogram distributions, a quantitative relationship was determined between absolute value of magnetic field strength B and brightness temperature which is essentially linear from 10 to 150 G. An interpretation is suggested, in which a basal heating occurs generally, while brighter elements are produced in magnetic regions with temperature enhancements proportional to B.

  9. Strength of Cu-28 wt%Ag composite solidified under high magnetic field followed by cold drawing

    NASA Astrophysics Data System (ADS)

    Zhao, Congcong; Zuo, Xiaowei; Wang, Engang; Han, Ke

    2017-03-01

    Cu-Ag composite is one of the best conductors for high-field magnets. Increasing its strength is crucial for designing newer high-field magnets. Cu-28 wt%Ag samples were solidified with and without a 12-T high magnetic field (HMF), and then cold-drawn. We investigated the influence of HMF on microstructure, hardness and strength of Cu-Ag samples both before and after cold-drawing. The introduction of external HMF during solidification increased both the dendrite arm spacing and the dissolved Ag in Cu, and it reduced the spacing between both the Ag precipitates in proeutectic Cu and the eutectic lamellae. The transversal microstructure after cold-drawing inherited the network solidification structure, but at a refined scale. The Cu dendrite spacing in the 12-T HMF samples at all deformation strain was larger than that without HMF. HMF slightly increased the intensity of <111> fiber texture of Cu, which strengthened proeutectic Cu at the level of 3.5 deformation strain. In samples deformed to strain of 3.5, refined Ag precipitation spacing, increased Ag solubility in Cu matrix, and refined eutectic lamellar spacing by 12-T HMF increased the strength by 5% in the sample compared with that without HMF.

  10. Estimations of the magnetic field strength in the torus of IC 5063 using near-infrared polarimetry

    NASA Astrophysics Data System (ADS)

    Lopez-Rodriguez, E.; Packham, C.; Young, S.; Elitzur, M.; Levenson, N. A.; Mason, R. E.; Ramos Almeida, C.; Alonso-Herrero, A.; Jones, T. J.; Perlman, E.

    2013-05-01

    An optically and geometrically thick torus obscures the central engine of active galactic nuclei (AGN) from some lines of sight. From a magnetohydrodynamical framework, the torus can be considered to be a particular region of clouds surrounding the central engine where the clouds are dusty and optically thick. In this framework, the magnetic field plays an important role in the creation, morphology and evolution of the torus. If the dust grains within the clouds are assumed to be aligned by paramagnetic alignment, then the ratio of the intrinsic polarization and visual extinction, P(per cent)/Av, is a function of the magnetic field strength. To estimate the visual extinction through the torus and constrain the polarization mechanisms in the nucleus of the type 2 AGN, IC 5063, we developed a polarization model to fit both the total and polarized flux in a 1.2-arcsec (˜263 pc) aperture. The polarization model is consistent with the nuclear polarization observed at Kn (2.0-2.3 μm) being produced by dichroic absorption from aligned dust grains with a visual extinction through the torus of 48 ± 2 mag. We estimated the intrinsic polarization arising from dichroic absorption to be P^{{dic}}_{{{K_n}}} = 12.5 ± 2.7 per cent. We consider the physical conditions and environment of the gas and dust for the torus of IC 5063. Then, through paramagnetic alignment, we estimate a magnetic field strength in the range of 12-128 mG in the near-infrared emitting regions of the torus of IC 5063. Alternatively, we estimate the magnetic field strength in the plane of the sky using the Chandrasekhar-Fermi method. The minimum magnetic field strength in the plane of the sky is estimated to be 13 and 41 mG depending of the conditions within the torus of IC 5063. These techniques afford the chance to make a survey of AGN, to investigate the effects of magnetic field strength on the torus, accretion and interaction to the host galaxy.

  11. On the importance of body posture and skin modelling with respect to in situ electric field strengths in magnetic field exposure scenarios

    NASA Astrophysics Data System (ADS)

    Schmid, Gernot; Hirtl, Rene

    2016-06-01

    The reference levels and maximum permissible exposure values for magnetic fields that are currently used have been derived from basic restrictions under the assumption of upright standing body models in a standard posture, i.e. with arms laterally down and without contact with metallic objects. Moreover, if anatomical modelling of the body was used at all, the skin was represented as a single homogeneous tissue layer. In the present paper we addressed the possible impacts of posture and skin modelling in scenarios of exposure to a 50 Hz uniform magnetic field on the in situ electric field strength in peripheral tissues, which must be limited in order to avoid peripheral nerve stimulation. We considered different body postures including situations where body parts form large induction loops (e.g. clasped hands) with skin-to-skin and skin-to-metal contact spots and compared the results obtained with a homogeneous single-layer skin model to results obtained with a more realistic two-layer skin representation consisting of a low-conductivity stratum corneum layer on top of a combined layer for the cellular epidermis and dermis. Our results clearly indicated that postures with loops formed of body parts may lead to substantially higher maximum values of induced in situ electric field strengths than in the case of standard postures due to a highly concentrated current density and in situ electric field strength in the skin-to-skin and skin-to-metal contact regions. With a homogeneous single-layer skin, as is used for even the most recent anatomical body models in exposure assessment, the in situ electric field strength may exceed the basic restrictions in such situations, even when the reference levels and maximum permissible exposure values are not exceeded. However, when using the more realistic two-layer skin model the obtained in situ electric field strengths were substantially lower and no violations of the basic restrictions occurred, which can be explained by the

  12. Region of interest correction factors improve reliability of diffusion imaging measures within and across scanners and field strengths.

    PubMed

    Venkatraman, Vijay K; Gonzalez, Christopher E; Landman, Bennett; Goh, Joshua; Reiter, David A; An, Yang; Resnick, Susan M

    2015-10-01

    Diffusion tensor imaging (DTI) measures are commonly used as imaging markers to investigate individual differences in relation to behavioral and health-related characteristics. However, the ability to detect reliable associations in cross-sectional or longitudinal studies is limited by the reliability of the diffusion measures. Several studies have examined the reliability of diffusion measures within (i.e. intra-site) and across (i.e. inter-site) scanners with mixed results. Our study compares the test-retest reliability of diffusion measures within and across scanners and field strengths in cognitively normal older adults with a follow-up interval less than 2.25 years. Intra-class correlation (ICC) and coefficient of variation (CoV) of fractional anisotropy (FA) and mean diffusivity (MD) were evaluated in sixteen white matter and twenty-six gray matter bilateral regions. The ICC for intra-site reliability (0.32 to 0.96 for FA and 0.18 to 0.95 for MD in white matter regions; 0.27 to 0.89 for MD and 0.03 to 0.79 for FA in gray matter regions) and inter-site reliability (0.28 to 0.95 for FA in white matter regions, 0.02 to 0.86 for MD in gray matter regions) with longer follow-up intervals were similar to earlier studies using shorter follow-up intervals. The reliability of across field strengths comparisons was lower than intra- and inter-site reliabilities. Within and across scanner comparisons showed that diffusion measures were more stable in larger white matter regions (>1500 mm(3)). For gray matter regions, the MD measure showed stability in specific regions and was not dependent on region size. Linear correction factor estimated from cross-sectional or longitudinal data improved the reliability across field strengths. Our findings indicate that investigations relating diffusion measures to external variables must consider variable reliability across the distinct regions of interest and that correction factors can be used to improve consistency of measurement

  13. Application of Quantitative MRI for Brain Tissue Segmentation at 1.5 T and 3.0 T Field Strengths

    PubMed Central

    West, Janne; Blystad, Ida; Engström, Maria; Warntjes, Jan B. M.; Lundberg, Peter

    2013-01-01

    Background Brain tissue segmentation of white matter (WM), grey matter (GM), and cerebrospinal fluid (CSF) are important in neuroradiological applications. Quantitative Mri (qMRI) allows segmentation based on physical tissue properties, and the dependencies on MR scanner settings are removed. Brain tissue groups into clusters in the three dimensional space formed by the qMRI parameters R1, R2 and PD, and partial volume voxels are intermediate in this space. The qMRI parameters, however, depend on the main magnetic field strength. Therefore, longitudinal studies can be seriously limited by system upgrades. The aim of this work was to apply one recently described brain tissue segmentation method, based on qMRI, at both 1.5 T and 3.0 T field strengths, and to investigate similarities and differences. Methods In vivo qMRI measurements were performed on 10 healthy subjects using both 1.5 T and 3.0 T MR scanners. The brain tissue segmentation method was applied for both 1.5 T and 3.0 T and volumes of WM, GM, CSF and brain parenchymal fraction (BPF) were calculated on both field strengths. Repeatability was calculated for each scanner and a General Linear Model was used to examine the effect of field strength. Voxel-wise t-tests were also performed to evaluate regional differences. Results Statistically significant differences were found between 1.5 T and 3.0 T for WM, GM, CSF and BPF (p<0.001). Analyses of main effects showed that WM was underestimated, while GM and CSF were overestimated on 1.5 T compared to 3.0 T. The mean differences between 1.5 T and 3.0 T were -66 mL WM, 40 mL GM, 29 mL CSF and -1.99% BPF. Voxel-wise t-tests revealed regional differences of WM and GM in deep brain structures, cerebellum and brain stem. Conclusions Most of the brain was identically classified at the two field strengths, although some regional differences were observed. PMID:24066153

  14. The effects of different speed training protocols on sprint acceleration kinematics and muscle strength and power in field sport athletes.

    PubMed

    Lockie, Robert G; Murphy, Aron J; Schultz, Adrian B; Knight, Timothy J; Janse de Jonge, Xanne A K

    2012-06-01

    A variety of resistance training interventions are used to improve field sport acceleration (e.g., free sprinting, weights, plyometrics, resisted sprinting). The effects these protocols have on acceleration performance and components of sprint technique have not been clearly defined in the literature. This study assessed 4 common protocols (free sprint training [FST], weight training [WT], plyometric training [PT], and resisted sprint training [RST]) for changes in acceleration kinematics, power, and strength in field sport athletes. Thirty-five men were divided into 4 groups (FST: n = 9; WT: n = 8; PT: n = 9; RST: n = 9) matched for 10-m velocity. Training involved two 60-minute sessions per week for 6 weeks. After the interventions, paired-sample t-tests identified significant (p ≤ 0.05) within-group changes. All the groups increased the 0- to 5-m and 0- to 10-m velocity by 9-10%. The WT and PT groups increased the 5- to 10-m velocity by approximately 10%. All the groups increased step length for all distance intervals. The FST group decreased 0- to 5-m flight time and step frequency in all intervals and increased 0- to 5-m and 0- to 10-m contact time. Power and strength adaptations were protocol specific. The FST group improved horizontal power as measured by a 5-bound test. The FST, PT, and RST groups all improved reactive strength index derived from a 40-cm drop jump, indicating enhanced muscle stretch-shortening capacity during rebound from impacts. The WT group increased absolute and relative strength measured by a 3-repetition maximum squat by approximately 15%. Step length was the major limiting sprint performance factor for the athletes in this study. Correctly administered, each training protocol can be effective in improving acceleration. To increase step length and improve acceleration, field sport athletes should develop specific horizontal and reactive power.

  15. ELF (Extremely Low Frequency) PVS (Propagation Validation System) Field Strength Measurements, January 1977.

    DTIC Science & Technology

    1983-03-21

    in the North-Atlantic/Norwegian- Sea area at a range of approximately 5 Mm from WTF. Signal-strength data (both amplitude and relative phase) were...measured on all three submarines is plotted in figure 1* versus GMT. Previous January effective-noise measure- ments in the Norwegian- Sea area (Tromso...Inc., 404 Tasman Dr. Sunnyvale, CA 94086 1 Dr. Eivind Trane, NDRE, P.O. Box 25, 2007 Kjeller, Norway 1 RCA David Sarnoff Research Center (K. Powers

  16. In situ rock strength and far field stress in the Nankai accretionary complex: Integration of downhole data from multiple wells

    NASA Astrophysics Data System (ADS)

    Huffman, K. A.; Saffer, D. M.

    2014-12-01

    Knowing the magnitude of tectonic stress and rock strength at seismically active margins is important towards understanding fault strength and failure mechanics, yet both are difficult to measure in situ. Recent work at subduction margins, including Integrated Ocean Drilling Program (IODP) Nankai Trough Subduction Zone Experiment (NanTroSEIZE) drillsites, uses the width of compressional wellbore breakouts (BO), which depends on far field stress conditions, rock strength, and borehole annular pressure (APRS), to estimate the magnitude of horizontal principal stresses (SHmax and Shmin); estimates are problematic due to uncertainty in rock strength (unconfined compressive strength/UCS- for which direct measurements are scarce) and rheology that govern stress distribution at the wellbore. We conduct a novel case study at IODP Site C0002, where a hole was drilled twice with different boundary conditions, providing an opportunity to define in situ stress and strength from field data. Site C0002 is the main deep riser borehole for NanTroSEIZE, located near the seaward edge of the Kumano Basin above the seismogenic plate boundary, ~30 km from the trench. Several boreholes were drilled at the site. During IODP Expedition 314 in 2007, Hole C0002A was drilled with a suite of logging while drilling (LWD) tools to 1401 mbsf in a riserless mode. Hole C0002F, ~70 m away, was drilled to 862 mbsf in riserless mode during Exp. 326 in 2010 and deepened to 2005 mbsf in a riser mode during Expedition 338 in 2012-2013. Increased APRS achieved by riser drilling stabilizes the borehole and suppresses BO, consistent with resistivity imaging data from Exp. 314 that document well-developed, continuous BO throughout the borehole, and data from Expedition 338 indicating few BO. We use a semi-Newtonian approach to solve for stress and UCS consistent with the observed BO width and measured APRS in the two holes over the interval from 862-2005 mbsf. Effective SHmax ranges from ~10-30 MPa and

  17. Design and characterization of a system for exposure of cultured cells to extremely low frequency electric and magnetic fields over a wide range of field strengths.

    PubMed

    Mullins, R D; Sisken, J E; Hejase, H A; Sisken, B F

    1993-01-01

    A system is described that is capable of producing extremely low frequency (ELF) magnetic fields for relatively short-term exposure of cultured mammalian cells. The system utilizes a ferromagnetic core to contain and direct the magnetic field of a 1,000 turn solenoidal coil and can produce a range of flux densities and induced electric fields much higher than those produced by Helmholtz coils. The system can generate magnetic fields from the microtesla (microT) range up to 0.14 T with induced electric field strengths on the order of 1.0 V/m. The induced electric field can be accurately varied by changing the sample chamber configuration without changing the exposure magnetic field. This gives the system the ability to separate the bioeffects of magnetic and induced electric fields. In the frequency range of 4-100 Hz and magnetic flux density range of 0.005-0.14 T, the maximum total harmonic distortion of the induced electric field is typically less than 1.0%. The temperature of the samples is held constant to within 0.4 degrees C by constant perfusion of warmed culture medium through the sample chamber.

  18. Characterisation of cationic potato starch by asymmetrical flow field-flow fractionation. Influence of ionic strength and degree of substitution.

    PubMed

    Santacruz, Stalin

    2014-06-15

    The properties of a paper sheet depend on the absorption together with the physico-chemical properties of additives used in the paper processing. The effect of ionic strength and degree of substitution of cationic potato starch on the elution pattern of asymmetrical flow field-flow fractionation was analysed. The effect of starch derivatisation, in either dry or wet phase, was also investigated. Average molar mass showed no difference between the starches obtained from the two derivatisation processes. Apparent densities showed that dry cationic starch had higher density than wet cationic starch for a hydrodynamic radius between 50 and 100 nm. Elution times of native and three cationic starches increased when the ionic strength increased from 50 to 100mM. No differences in the molar mass among cationic starches with different degree of substitution suggested no degradation due to a derivatisation process. Large sample loads can be used at 100mM without overloading.

  19. 47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization.... For equipment operating on frequencies below 890 MHz, an open field test is normally required, with the measuring instrument antenna located in the far-field at all test frequencies. In the event it...

  20. 47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization.... For equipment operating on frequencies below 890 MHz, an open field test is normally required, with the measuring instrument antenna located in the far-field at all test frequencies. In the event it...

  1. 47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization.... For equipment operating on frequencies below 890 MHz, an open field test is normally required, with the measuring instrument antenna located in the far-field at all test frequencies. In the event it...

  2. 47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization.... For equipment operating on frequencies below 890 MHz, an open field test is normally required, with the measuring instrument antenna located in the far-field at all test frequencies. In the event it...

  3. Analytical solutions of the Schroedinger equation for a two-dimensional exciton in magnetic field of arbitrary strength

    SciTech Connect

    Hoang-Do, Ngoc-Tram; Hoang, Van-Hung; Le, Van-Hoang

    2013-05-15

    The Feranchuk-Komarov operator method is developed by combining with the Levi-Civita transformation in order to construct analytical solutions of the Schroedinger equation for a two-dimensional exciton in a uniform magnetic field of arbitrary strength. As a result, analytical expressions for the energy of the ground and excited states are obtained with a very high precision of up to four decimal places. Especially, the precision is uniformly stable for the whole range of the magnetic field. This advantage appears due to the consideration of the asymptotic behaviour of the wave-functions in strong magnetic field. The results could be used for various physical analyses and the method used here could also be applied to other atomic systems.

  4. Office-based versus high-field strength MRI: diagnostic and technical considerations.

    PubMed

    Sanal, Hatice Tuba; Cardoso, Fabiano; Chen, Lina; Chung, Christine

    2009-03-01

    Low-field office magnetic resonance scanners have been an exciting, innovative, and controversial development in medical imaging. These units boost cost efficiency, with ease of installation and no additional external radiofrequency shielding necessary. The open design enables imaging of those who are claustrophobic and overweight, and offer the potential of dynamic imaging for athletes. Experienced centers have reported that the diagnostic accuracy obtained with office-based systems is satisfactory and comparable with that of high-field systems. However, with the advantages afforded by these convenient units, some significant limitations owing primarily to decreased signal-to-noise ratio of low-field MR imaging and lower image quality compared with conventional high-field magnetic resonance scanners. In this article, we comprehensively reviewed the literature focusing on the diagnostic accuracy of low-field imaging with respect to individual joints and the major pathology that occur in these joints. According to most studies, there are still a number of patients in whom clinical treatment is affected owing to under or misdiagnosis by low-field MR imaging. For clinicians and radiologists who are an integral part of this office-based diagnostic system, it is important to be knowledgeable of the potential limitations of these low-field scanners compared with conventional systems. Specialized training and expertize is required to optimize imaging parameters, and provide quality control and accurate interpretation.

  5. Feasibility of normal tissue dose reduction in radiotherapy using low strength magnetic field

    PubMed Central

    Shin, Youngseob; Jung, In-Hye; Kwak, Jungwon

    2015-01-01

    Purpose Toxicity of mucosa is one of the major concerns of radiotherapy (RT), when a target tumor is located near a mucosal lined organ. Energy of photon RT is transferred primarily by secondary electrons. If these secondary electrons could be removed in an internal cavity of mucosal lined organ, the mucosa will be spared without compromising the target tumor dose. The purpose of this study was to present a RT dose reduction in near target inner-surface (NTIS) of internal cavity, using Lorentz force of magnetic field. Materials and Methods Tissue equivalent phantoms, composed with a cylinder shaped internal cavity, and adjacent a target tumor part, were developed. The phantoms were irradiated using 6 MV photon beam, with or without 0.3 T of perpendicular magnetic field. Two experimental models were developed: single beam model (SBM) to analyze central axis dose distributions and multiple beam model (MBM) to simulate a clinical case of prostate cancer with rectum. RT dose of NTIS of internal cavity and target tumor area (TTA) were measured. Results With magnetic field applied, bending effect of dose distribution was visualized. The depth dose distribution of SBM showed 28.1% dose reduction of NTIS and little difference in dose of TTA with magnetic field. In MBM, cross-sectional dose of NTIS was reduced by 33.1% with magnetic field, while TTA dose were the same, irrespective of magnetic field. Conclusion RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field. PMID:26484306

  6. Determination of the electric field strength of filamentary DBDs by CARS-based four-wave mixing

    NASA Astrophysics Data System (ADS)

    Böhm, P.; Kettlitz, M.; Brandenburg, R.; Höft, H.; Czarnetzki, U.

    2016-10-01

    It is demonstrated that a four-wave mixing technique based on coherent anti-Stokes Raman spectroscopy (CARS) can determine the electric field strength of a pulsed-driven filamentary dielectric barrier discharge (DBD) of 1 mm gap, using hydrogen as a tracer medium in nitrogen at atmospheric pressure. The measurements are presented for a hydrogen admixture of 10%, but even 5% H2 admixture delivers sufficient infrared signals. The lasers do not affect the discharge by photoionization or by other radiation-induced processes. The absolute values of the electric field strength can be determined by the calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. This procedure also enables the determination of the applied breakdown voltage. The alteration of the electric field is observed during the internal polarity reversal and the breakdown process. One advantage of the CARS technique over emission-based methods is that it can be used independently of emission, e.g. in the pre-phase and in between two consecutive discharges, where no emission occurs at all.

  7. MR Imaging Detection of Cerebral Microbleeds: Effect of Susceptibility-Weighted Imaging, Section Thickness, and Field Strength

    PubMed Central

    Nandigam, R.N.K.; Viswanathan, A.; Delgado, P.; Skehan, M.E.; Smith, E.E.; Rosand, J.; Greenberg, S.M.; Dickerson, B.C.

    2009-01-01

    BACKGROUND AND PURPOSE: The emergence of cerebral microbleeds (CMB) as common MR imaging findings raises the question of how MR imaging parameters influence CMB detection. To evaluate the effects of modified gradient recalled-echo (GRE) MR imaging methods, we performed an analysis of sequence, section thickness, and field strength on CMB imaging properties and detection in subjects with cerebral amyloid angiopathy (CAA), a condition associated with microhemorrhage. MATERIALS AND METHODS: Multiple MR images were obtained from subjects with probable CAA, with varying sequences (GRE versus susceptibility-weighted imaging [SWI]), section thicknesses (1.2–1.5 versus 5 mm), and magnetic field strengths (1.5T versus 3T). Individual CMB were manually identified and analyzed for contrast index (lesion intensity normalized to normal-appearing white matter signal intensity) and diameter. CMB counts were compared between 1.5T thick-section GRE and thin-section SWI for 3 subjects who underwent both protocols in the same scanning session. RESULTS: With other parameters constant, use of SWI, thinner sections, and a higher field strength yielded medium-to-large gains in CMB contrast index (CI; Cohen d 0.71–1.87). SWI was also associated with small increases in CMB diameter (Cohen d <0.3). Conventional thick-section GRE identified only 33% of CMB (103 of 310) seen on thin-section SWI. Lesions prospectively identified on GRE had significantly greater CI and diameter measured on the GRE image than those not prospectively identified. CONCLUSIONS: The examined alternatives to conventional GRE MR imaging yield substantially improved CMB contrast and sensitivity for detection. Future studies based on these techniques will most likely yield even higher prevalence estimates for CMB. PMID:19001544

  8. WE-G-18C-05: Characterization of Cross-Vendor, Cross-Field Strength MR Image Intensity Variations

    SciTech Connect

    Paulson, E; Prah, D

    2014-06-15

    Purpose: Variations in MR image intensity and image intensity nonuniformity (IINU) can challenge the accuracy of intensity-based image segmentation and registration algorithms commonly applied in radiotherapy. The goal of this work was to characterize MR image intensity variations across scanner vendors and field strengths commonly used in radiotherapy. Methods: ACR-MRI phantom images were acquired at 1.5T and 3.0T on GE (450w and 750, 23.1), Siemens (Espree and Verio, VB17B), and Philips (Ingenia, 4.1.3) scanners using commercial spin-echo sequences with matched parameters (TE/TR: 20/500 ms, rBW: 62.5 kHz, TH/skip: 5/5mm). Two radiofrequency (RF) coil combinations were used for each scanner: body coil alone, and combined body and phased-array head coils. Vendorspecific B1- corrections (PURE/Pre-Scan Normalize/CLEAR) were applied in all head coil cases. Images were transferred offline, corrected for IINU using the MNI N3 algorithm, and normalized. Coefficients of variation (CV=σ/μ) and peak image uniformity (PIU = 1−(Smax−Smin)/(Smax+Smin)) estimates were calculated for one homogeneous phantom slice. Kruskal-Wallis and Wilcoxon matched-pairs tests compared mean MR signal intensities and differences between original and N3 image CV and PIU. Results: Wide variations in both MR image intensity and IINU were observed across scanner vendors, field strengths, and RF coil configurations. Applying the MNI N3 correction for IINU resulted in significant improvements in both CV and PIU (p=0.0115, p=0.0235). However, wide variations in overall image intensity persisted, requiring image normalization to improve consistency across vendors, field strengths, and RF coils. These results indicate that B1- correction routines alone may be insufficient in compensating for IINU and image scaling, warranting additional corrections prior to use of MR images in radiotherapy. Conclusions: MR image intensities and IINU vary as a function of scanner vendor, field strength, and RF coil

  9. Disorder strength and field-driven ground state domain formation in artificial spin ice: experiment, simulation, and theory.

    PubMed

    Budrikis, Zoe; Morgan, J P; Akerman, J; Stein, A; Politi, Paolo; Langridge, S; Marrows, C H; Stamps, R L

    2012-07-20

    Quenched disorder affects how nonequilibrium systems respond to driving. In the context of artificial spin ice, an athermal system comprised of geometrically frustrated classical Ising spins with a twofold degenerate ground state, we give experimental and numerical evidence of how such disorder washes out edge effects and provide an estimate of disorder strength in the experimental system. We prove analytically that a sequence of applied fields with fixed amplitude is unable to drive the system to its ground state from a saturated state. These results should be relevant for other systems where disorder does not change the nature of the ground state.

  10. On the strength of oceanic fracture zones and their influence on the intraplate stress field

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1992-01-01

    We use the locations and source mechanisms of oceanic intraplate earthquakes to test the hypothesis that the strength of oceanic fracture zones is less than that of normal oceanic lithosphere. The 77 earthquakes selected for the study have well-determined focal mechanisms and epicenters in regions where fracture zones are well mapped. We have search for dependence of faulting style, fault orientation, or principal stress direction on the distance from the nearest fracture zone. If fracture zones were generally weaker than the surrounding lithosphere, one of the principal horizontal stresses would be oriented nearly perpendicular to the fracture zone; we find no evidence that principal stresses near fracture zones are oriented preferentially in this manner. There is a slight tendency for earthquakes to occur near fracture zones, and patterns of fault orientation and sense of slip support the view that differential cooling and horizontal contraction on fracture zones may contribute seismogenic stress.

  11. On the strength of oceanic fracture zones and their influence on the intraplate stress field

    SciTech Connect

    Bergman, E.A.; Solomon, S.C. )

    1992-10-01

    We use the locations and source mechanisms of oceanic intraplate earthquakes to test the hypothesis that the strength of oceanic fracture zones is less than that of normal oceanic lithosphere. The 77 earthquakes selected for the study have well-determined focal mechanisms and epicenters in regions where fracture zones are well mapped. We have search for dependence of faulting style, fault orientation, or principal stress direction on the distance from the nearest fracture zone. If fracture zones were generally weaker than the surrounding lithosphere, one of the principal horizontal stresses would be oriented nearly perpendicular to the fracture zone; we find no evidence that principal stresses near fracture zones are oriented preferentially in this manner. There is a slight tendency for earthquakes to occur near fracture zones, and patterns of fault orientation and sense of slip support the view that differential cooling and horizontal contraction on fracture zones may contribute seismogenic stress. 56 refs.

  12. The 'Arm Force Field' method to predict manual arm strength based on only hand location and force direction.

    PubMed

    La Delfa, Nicholas J; Potvin, Jim R

    2017-03-01

    This paper describes the development of a novel method (termed the 'Arm Force Field' or 'AFF') to predict manual arm strength (MAS) for a wide range of body orientations, hand locations and any force direction. This method used an artificial neural network (ANN) to predict the effects of hand location and force direction on MAS, and included a method to estimate the contribution of the arm's weight to the predicted strength. The AFF method predicted the MAS values very well (r(2) = 0.97, RMSD = 5.2 N, n = 456) and maintained good generalizability with external test data (r(2) = 0.842, RMSD = 13.1 N, n = 80). The AFF can be readily integrated within any DHM ergonomics software, and appears to be a more robust, reliable and valid method of estimating the strength capabilities of the arm, when compared to current approaches.

  13. VLF Radio Field Strength Measurement of power line carrier system in San Diego, California

    NASA Technical Reports Server (NTRS)

    Mertel, H. K.

    1981-01-01

    The radio frequency interference (RFI) potential was evaluated for a Powerline Carriet (PLC) installed in San Diego which monitors the performance of an electrical power system. The PLC system generated 30 amperes at 5.79 kHz. The RF radiations were measured to be (typically) 120 dBuV/m at the beginning of the 12 kV powerline and 60 dBuV/m at the end of the powerline. The RF fields varied inversely as the distance squared. Measurements were also performed with a 45 kHz PLC system. The RF fields were of similar amplitude.

  14. Nonlinear EEG activation evoked by low-strength low-frequency magnetic fields.

    PubMed

    Carrubba, Simona; Frilot, Clifton; Chesson, Andrew L; Marino, Andrew A

    2007-05-01

    Recent electrophysiological evidence suggested the existence of a human magnetic sense, but the kind of dynamical law that governed the stimulus-response relationship was not established. We tested the hypothesis that brain potentials evoked by the onset of a weak, low-frequency magnetic field were nonlinearly related to the stimulus. A field of 1G, 60 Hz was applied for 2s, with a 5s inter-stimulus period, and brain potentials were recorded from occipital electrodes in eight subjects, each of whom were measured twice, with at least 1 week between measurements. The recorded signals were subjected to nonlinear (recurrence analysis) and linear (time averaging) analyses. Using recurrence analysis, magnetosensory evoked potentials (MEPs) were detected in each subject in both the initial and replicate studies, with one exception. All MEPs exhibited the expected latency but differed in dynamical characteristics, indicating that they were nonlinearly related to the stimulus. MEPs were not detected using time averaging, thereby further confirming their nonlinearity. Evolutionarily conditioned structures that help mediate linear field-transduction in lower life forms may be expressed and functionally utilized in humans, but in a role where they facilitate vulnerability to man-made environmental fields.

  15. Reliability of a Field Test of Defending and Attacking Agility in Australian Football and Relationships to Reactive Strength.

    PubMed

    Young, Warren B; Murray, Mitch P

    2017-02-01

    Young, WB and Murray, MP. Reliability of a field test of defending and attacking agility in Australian football and relationships to reactive strength. J Strength Cond Res 31(2): 509-516, 2017-Defending and attacking agility tests for Australian football do not exist, and it is unknown whether any physical qualities correlate with these types of agility. The purposes of this study were to develop new field tests of defending and attacking agility for Australian Rules football, to determine whether they were reliable, and to describe the relationship between the agility tests to determine their specificity. Because the reactive strength (RS) of the lower limb muscles has been previously correlated with change-of-direction speed, we also investigated the relationship between this quality and the agility tests. Nineteen male competitive recreational-level Australian Rules football players were assessed on the agility tests and a drop jump test to assess RS. Interday and interrater reliability was also assessed. The agility tests involved performing 10 trials of one-on-one agility tasks against 2 testers (opponents), in which the objective was to be in a position to tackle (defending) or to evade (attacking) the opponent. Both agility tests had good reliability (intraclass correlation > 0.8, %CV < 3, and no significant differences between test occasions [p > 0.05], and interrater reliability was very high [r = 0.997, p < 0.001]). The common variance between the agility tests was 45%, indicating that they represented relatively independent skills. There was a large correlation between RS and defending agility (r = 0.625, p = 0.004), and a very large correlation with attacking agility (r = 0.731, p < 0.001). Defending and attacking agility have different characteristics, possibly related to the footwork, physical, and cognitive demands of each. Nonetheless, RS seems to be important for agility, especially for attacking agility.

  16. Local Electric Field Strength in a Hollow Cathode Determined by Stark Splitting of the 2S Level of Hydrogen Isotopes by Optogalvanic Spectroscopy

    SciTech Connect

    Perez, C.; Rosa, M. I. de la; Gruetzmacher, K.; Fuentes, L. M.; Gonzalo, A. B.

    2008-10-22

    In this work we present Doppler-free two-photon optogalvanic spectroscopy as a tool to measure the electric field strength in the cathode fall region of a hollow cathode discharge via the Stark splitting of the 2S level of atomic deuterium. The strong electric field strength present in the hollow cathode is determined for various discharge conditions which allows studying the corresponding variations of the cathode fall, and its changes with discharge operation time.

  17. Principles and Application of Magnetic Rubber Testing for Crack Detection in High-Strength Steel Components: I. Active-Field Inspection

    DTIC Science & Technology

    2014-12-01

    D6ac Denotes a grade of high strength steel MLE Maximum likelihood estimate MPI Magnetic particle inspection MRT Magnetic rubber testing NDE...crack detection if the coercive field of the grade of steel is increased [45]. Field values quoted in the general MRT literature† are of limited value...UNCLASSIFIED UNCLASSIFIED Principles and Application of Magnetic Rubber Testing for Crack Detection in High-Strength Steel Components: I

  18. Fiber-Optic Magnetic-Field-Strength Measurement System for Lightning Detection

    NASA Technical Reports Server (NTRS)

    Gurecki, Jay; Scully, Robert; Davis, Allen; Kirkendall, Clay; Bucholtz, Frank

    2011-01-01

    A fiber-optic sensor system is designed to measure magnetic fields associated with a lightning stroke. Field vector magnitudes are detected and processed for multiple locations. Since physical limitations prevent the sensor elements from being located in close proximity to highly conductive materials such as aluminum, the copper wire sensor elements (3) are located inside a 4-cubic-in. (.66-cubic-cm) plastic housing sensor head and connected to a fiber-optic conversion module by shielded cabling, which is limited to the shortest length feasible. The signal path between the conversion module and the avionics unit which processes the signals are fiber optic, providing enhanced immunity from electromagnetic radiation incident in the vicinity of the measurements. The sensors are passive, lightweight, and much smaller than commercial B-dot sensors in the configuration which measures a three-dimensional magnetic field. The system is expandable, and provides a standard-format output signal for downstream processing. Inside of the sensor head, three small search coils, each having a few turns on a circular form, are mounted orthogonally inside the non-metallic housing. The fiber-optic conversion module comprises three interferometers, one for each search coil. Each interferometer has a high bandwidth optical phase modulator that impresses the signal received from its search coil onto its output. The output of each interferometer travels by fiber optic cable to the avionics unit, and the search coil signal is recovered by an optical phase demodulator. The output of each demodulator is fed to an analog-to-digital converter, whose sampling rate is determined by the maximum expected rate of rise and peak signal magnitude. The output of the digital processor is a faithful reproduction of the coil response to the incident magnetic field. This information is provided in a standard output format on a 50-ohm port that can be connected to any number of data collection and processing

  19. Study of the behavioral and biological effects of high-strength 60-Hz electric fields. Quarterly technical progress report number 10, 18 December 1982-18 March 1983

    SciTech Connect

    Not Available

    1983-04-20

    The objective of this contract is to use the baboon as a surrogate for the human in studies of the possible deleterious effects of exposure to high strength, 60 Hz electric fields. The specific aims of this contract are to (1) design and construct an exposure facility in which baboons can be exposed to an electric field up to 60 kV/m in intensity for experiments and (2) to develop computer models relating the fields and currents produced in both baboons and humans by exposure to high strength, 60 Hz electric fields.

  20. Is the general conclusion justified that higher applicable field strength results in shorter analysis time with organic solvents in CE?

    PubMed

    Téllez, Adolfo; Kenndler, Ernst

    2009-11-01

    In this paper, a widespread opinion in CE with organic solvents for the background electrolyte is critically questioned, namely that in general a shorter analysis time can be achieved due to the higher field strength applicable compared with aqueous electrolyte systems. This view, common in the literature, is based on the supposition that the conductance in organic solvents is lower than in water. Indeed in many organic solvents with higher viscosity than water lower ion mobility is observed, and higher fields can be applied in these cases. However, in this paper the problem is sharper defined and treated two-fold: (i) in all solvents conditions are such that either the same electric power is generated, or (ii) the same temperature increase is taken into account. It was shown that for the same electric power the field strength in the organic solvent can be changed to a less extent than the ionic mobility changes. As a result, the migration velocity of the analytes is lower and the analysis time is longer in most organic solvents compared with water; acetonitrile (MeCN) is an exception (in this solvent the mobilities are higher than in water). The more stringent treatment of the problem takes an equal temperature increase due to Joule heating into account rather than equal electric power. The temperature increase in the capillary depends on the thermal conductivity of the solvent, which is only about one-third of that of water for organic liquids. The consequence is that in none of the organic solvent systems a shorter analysis time can be achieved compared with water (given that the experimental conditions are comparable, e.g. zero EOF). The theoretical predictions were confirmed by measurements with water, methanol, propylenecarbonate, and MeCN as solvents.

  1. Electron beam injection experiments - The beam-plasma discharge at low pressures and magnetic field strengths

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Leinbach, H.; Kellogg, P.; Monson, S.; Hallinan, T.; Garriott, O. K.; Konradi, A.; Mccoy, J.; Daly, P.; Baker, B.

    1978-01-01

    The paper describes electron beam injection experiments which clarify observational results obtained in rocket flights. A column of enhanced density plasma, exceeding the density expected from ionization by primary beam electrons, was observed in a large vacuum system at low magnetic fields (1 to 1.5 G) and low ambient pressures (10 to the minus 6 to 10 to the minus 5 torr). The peak luminosity of the discharge was about 10 times that of the beam alone, and the radius increased by a factor of three. In the absence of the discharge, RF emission is observed at 1.1 to 1.2 times the cyclotron frequency, and a strong band of RF noise with upper frequency cutoff at about the cyclotron frequency is observed in the discharge mode, along with higher frequency noise at or near the plasma frequency. The onset of the plasma discharge is critically dependent on beam current. The described results agree with observations obtained at much higher densities and magnetic fields in fusion research studies.

  2. A NEW DIAGNOSTIC OF MAGNETIC FIELD STRENGTHS IN RADIATIVELY COOLED SHOCKS

    SciTech Connect

    Hartigan, P.; Wright, A.

    2015-09-20

    We show that it is possible to measure Alfvénic Mach numbers, defined as the shock velocity in the flow divided by the Alfvén velocity, for low-velocity (V{sub shock} ≲ 100 km s{sup −1}) radiative shocks. The method combines observations of bright forbidden lines with a measure of the size of the cooling zone, the latter typically obtained from spatial separation between the Balmer emission lines and the forbidden lines. Because magnetic fields become compressed as gas in the postshock region cools, even relatively weak preshock magnetic fields can be detected with this method. We derive analytical formulae that explain how the spatial separations relate to emission-line ratios, and compute a large grid of radiatively cooled shock models to develop diagnostic diagrams that can be used to derive Alfvénic Mach numbers in flows. Applying the method to existing data for a bright knot in the HH 111 jet, we obtain a relatively low Alfvénic Mach number of ∼2, indicative of a magnetized jet that has super-magnetosonic velocity perturbations within it.

  3. Microhardness, strength and strain field characterization of self-reacting friction stir and plug welds of dissimilar aluminum alloys

    NASA Astrophysics Data System (ADS)

    Horton, Karla Renee

    Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. This work reports on material properties and strain patterns developed in a SR-FSW with a friction plug weld. Specifically, this study examines the behavior of a SR-FSW formed between an AA2014-T6 plate on the advancing side and an AA2219-T87 plate on the retreating side and a SR-FSW (AA2014-T6 to AA2219-T87) with a 2219-T87 plug weld. This study presents the results of a characterization of the micro-hardness, joint strength, and strain field characterization of SR-FSW and FPW joints tested at room temperature and cryogenic temperatures. The initial weld microstructure analysis showed a nugget region with fine grains and a displaced weld seam from the advancing side past the thermo-mechanical affected zone (TMAZ) into the nugget region. The displaced material shared the same hardness as the parent material. Dynamic recrystallization was observed in the SR-FSW zone and the displaced weld seam region. The welds revealed a fine grain structure in the SR-FSW zone with a sharp demarcation seen on the advancing side and fairly diffuse flow observed on the retreating side. The parent material hardness is 145 HV700g with a drop in hardness starting at the HAZ to 130 HV700g. The hardness further drops in the TMAZ to118 HV700g with an increase representing a dispersed interface of AA2014-T6 material to 135 HV700g. The hardness then drops significantly within the nugget region to 85 HV700g followed by an increase through the retreating side TMAZ into the HAZ to 135 HV 700g. There was a sharp increase in the hardness value within

  4. Non-bridging Oxygen and Five-coordinated Aluminum in Aluminosilicate Glasses: A Cation Field Strength Study

    NASA Astrophysics Data System (ADS)

    Thompson, L. M.; Stebbins, J. F.

    2011-12-01

    Linda M. Thompson Jonathan F. Stebbins Dept. of Geological and Environmental Sciences, Stanford University, Stanford CA 94305 Although it is understood in aluminosilicate melts and glasses that non-bridging oxygens (NBO) have significant influence on thermodynamic and transport properties, questions remain about its role and the extent of its influence, particularly in metaluminous and peraluminous compositions. One major question persists regarding whether the formation of NBO is in any way coupled with the formation of VAl (AlO5), which is significantly impacted by cation field strength (defined as the cation charge divided by the square of the distance between the cation and oxygen atoms) (Kelsey et al., 2009). Previous work on calcium and potassium aluminosilicate glasses has shown the presence of NBO on the metaluminous join and persisting into the peraluminous region, with significantly more NBO present in Ca glasses compared to K glasses of similar composition (Thompson and Stebbins, 2011). However, it is unclear if there is any systematic impact on NBO content by cation field strength similar to the impact on VAl. Expanding on the previous study, barium aluminosilicate glasses were synthesized covering a range of compositions crossing the metaluminous (e.g. BaAl2O4-SiO2) join to observe changes in the NBO for comparison against the calcium aluminosilicate glasses, thus looking at the impact of cation size on NBO versus cation charge. In the barium glasses on the 30 mol% SiO2 isopleth, the highest NBO content was 6.9% for the barium rich glass (R = 0.51, where R is Ba2+ / (Ba2+ + 2Al3+)) while the most peraluminous glass (R = 0.45) had an NBO content of 1.9%. Comparison of these results to earlier data shows these numbers are similar to what is observed in the Ca glasses, indicating cation size alone does not have a significant impact on NBO content. However the VAl content does show a decrease (compared to calcium aluminosilicate glasses at similar R values

  5. Linearly polarized radiation from astrophysical masers due to magnetic fields of intermediate strength

    NASA Technical Reports Server (NTRS)

    Nedoluha, Gerald E.; Watson, William D.

    1990-01-01

    Previous solutions for polarization of astrophysical maser radiation due to closed-shell molecules in a magnetic field have potentially serious limitations. These solutions are mostly based on the approximation that the Zeeman frequency g-Omega is much greater than the rate for stimulated emission R and the rate for decay Gamma of the molecular state. Others are asymptotic solutions obtained for an angular momentum J = 1-0 transition. It has been unclear whether the polarizations due to plausible Zeeman splittings are adequately represented by the solutions obtained for g-Omega/Gamma much greater than 1 and g-Omega/R much greater than 1. Actual masing transitions tend to involve molecular states with angular momenta that are higher than J = 1 and 0. Numerical solutions for the linear polarization are presented here which do not have the foregoing restrictions on the g-Omega and which are not limited to a J = 1-0 transition.

  6. AN UPDATE OF ITALIAN ARCHEAOINTENSITY DATA AND GEOMAGNETIC FIELD STRENGTH VARIATION DURING THE LAST THREE MILLENNIA

    NASA Astrophysics Data System (ADS)

    Tema, E.; Goguitchaichrili, A.

    2009-12-01

    Beside of the impressive cultural heritage and the abundant archaeological sites, Italian archaeointensity data are still sparse. We present here a new compilation and analysis of existing absolute intensity data in order to estimate the variation of the Earth’s magnetic field over the past three millennia. The current dataset consists of 140 intensity data mainly belonging to southern Italy. Vesuvius and Etna contribute 83 per cent of total while only 17 per cent comes from archaeological material. The time distribution is also irregular with the majority of determinations concentrated at the last four centuries. Still, older periods are very poorly covered. All data have been reduced at the latitude of Viterbo (42.45° N, 12.03° E) and plotted versus time. Data coming from historical volcanic eruptions show important discrepancies while those coming from archaeological material are still not sufficiently numerous to reliably describe the fine characteristics of geomagnetic field intensity variations. In order to increase the representativity of the data, archaeointensity results from nearby regions (approximately 700 km and 900 km radius from Viterbo) have been considered. The 700 km circle dataset still remains poor with only 20 additional data added. In contrast, the 900 km dataset includes 122 more archaeointensity data mainly coming from France, Switzerland, Czech Republic, Slovakia, Hungary, Greece and Bulgaria that partially fill the gap between 4-7th centuries BC and 3-4th and 9-11th AD for which no Italian data are available. A preliminary Italian intensity secular variation curve has been calculated by using sliding windows of 100 years shifted by 50 years. The results have been compared with regional and global models predictions. Clearly more Italian archaeointensity data are still needed in order to draw a robust Italian intensity secular variation curve that could be used for archaeomagnetic dating in combination with directional data.

  7. Signal Amplification in Field Effect-Based Sandwich Enzyme-Linked Immunosensing by Tuned Buffer Concentration with Ionic Strength Adjuster.

    PubMed

    Kumar, Satyendra; Kumar, Narendra; Panda, Siddhartha

    2016-04-01

    Miniaturization of the sandwich enzyme-based immunosensor has several advantages but could result in lower signal strength due to lower enzyme loading. Hence, technologies for amplification of the signal are needed. Signal amplification in a field effect-based electrochemical immunosensor utilizing chip-based ELISA is presented in this work. First, the molarities of phosphate buffer saline (PBS) and concentrations of KCl as ionic strength adjuster were optimized to maximize the GOx glucose-based enzymatic reactions in a beaker for signal amplification measured by change in the voltage shift with an EIS device (using 20 μl of solution) and validated with a commercial pH meter (using 3 ml of solution). The PBS molarity of 100 μM with 25 mM KCl provided the maximum voltage shift. These optimized buffer conditions were further verified for GOx immobilized on silicon chips, and similar trends with decreased PBS molarity were obtained; however, the voltage shift values obtained on chip reaction were lower as compared to the reactions occurring in the beaker. The decreased voltage shift with immobilized enzyme on chip could be attributed to the increased Km (Michaelis-Menten constant) values in the immobilized GOx. Finally, a more than sixfold signal enhancement (from 8 to 47 mV) for the chip-based sandwich immunoassay was obtained by altering the PBS molarity from 10 to 100 μM with 25 mM KCl.

  8. Crystal Field Splitting is Limiting the Stability and Strength of Ultra-incompressible Orthorhombic Transition Metal Tetraborides

    PubMed Central

    Zhang, R. F.; Wen, X. D.; Legut, D.; Fu, Z. H.; Veprek, S.; Zurek, E.; Mao, H. K.

    2016-01-01

    The lattice stability and mechanical strengths of the supposedly superhard transition metal tetraborides (TmB4, Tm = Cr, Mn and Fe) evoked recently much attention from the scientific community due to the potential applications of these materials, as well as because of general scientific interests. In the present study, we show that the surprising stabilization of these compounds from a high symmetry to a low symmetry structure is accomplished by an in-plane rotation of the boron network, which maximizes the in-plane hybridization by crystal field splitting between d orbitals of Tm and p orbitals of B. Studies of mechanical and electronic properties of TmB4 suggest that these tetraborides cannot be intrinsically superhard. The mechanical instability is facilitated by a unique in-plane or out-of-plane weakening of the three-dimensional covalent bond network of boron along different shear deformation paths. These results shed a novel view on the origin of the stability and strength of orthorhombic TmB4, highlighting the importance of combinational analysis of a variety of parameters related to plastic deformation of the crystalline materials when attempting to design new ultra-incompressible, and potentially strong and hard solids. PMID:26976479

  9. Strength of visual percept generated by famous faces perceived without awareness: effects of affective valence, response latency, and visual field.

    PubMed

    Stone, Anna; Valentine, Tim

    2005-09-01

    Participants who were unable to detect familiarity from masked 17 ms faces (Stone and Valentine, 2004 and Stone and Valentine, in press-b) did report a vague, partial visual percept. Two experiments investigated the relative strength of the visual percept generated by famous and unfamiliar faces, using masked 17 ms exposure. Each trial presented simultaneously a famous and an unfamiliar face, one face in LVF and the other in RVF. In one task, participants responded according to which of the faces generated the stronger visual percept, and in the other task, they attempted an explicit familiarity decision. The relative strength of the visual percept of the famous face compared to the unfamiliar face was moderated by response latency and participants' attitude towards the famous person. There was also an interaction of visual field with response latency, suggesting that the right hemisphere can generate a visual percept differentiating famous from unfamiliar faces more rapidly than the left hemisphere. Participants were at chance in the explicit familiarity decision, confirming the absence of awareness of facial familiarity.

  10. Graphene p n junction in a quantizing magnetic field: Conductance at intermediate disorder strength

    NASA Astrophysics Data System (ADS)

    Fräßdorf, Christian; Trifunovic, Luka; Bogdanoff, Nils; Brouwer, Piet W.

    2016-11-01

    In a graphene p n junction at high magnetic field, unidirectional "snake states" are formed at the p n interface. In a clean p n junction, each snake state exists in one of the valleys of the graphene band structure, and the conductance of the junction as a whole is determined by microscopic details of the coupling between the snake states at the p n interface and quantum Hall edge states at the sample boundaries [Tworzydło et al., Phys. Rev. B 76, 035411 (2007), 10.1103/PhysRevB.76.035411]. Disorder mixes and couples the snake states. We here report a calculation of the full conductance distribution in the crossover between the clean limit and the strong-disorder limit, in which the conductance distribution is given by random matrix theory [Abanin and Levitov, Science 317, 641 (2007), 10.1126/science.1144672]. Our calculation involves an exact solution of the relevant scaling equation for the scattering matrix, and the results are formulated in terms of parameters describing the microscopic disorder potential in bulk graphene.

  11. PAH Strength and the Interstellar Radiation Field around the Massive Young Cluster NGC 3603

    NASA Astrophysics Data System (ADS)

    Lebouteiller, V.; Brandl, B.; Bernard-Salas, J.; Devost, D.; Houck, J. R.

    2007-08-01

    We present spatial distribution of polycyclic aromatic hydrocarbons (PAHs) and ionized gas within the Galactic giant H II region NGC 3603. Using the IRS instrument on board the Spitzer Space Telescope, we study in particular the PAH emission features at ~5.7, 6.2, 7.7, 8.6, and 11.3 μm, and the [Ar II] 6.99 μm, [Ne II] 12.81 μm, [Ar III] 8.99 μm, and [S IV] 10.51 μm forbidden emission lines. The observations probe both ionized regions and photodissociation regions. Silicate emission is detected close to the central cluster while silicate absorption is seen further away. We find no significant variation of the PAH ionization fraction across the whole region. The emission of very small grains (VSGs) lies closer to the central stellar cluster than emission of PAHs. The PAH/VSG ratio anticorrelates with the hardness of the interstellar radiation field suggesting a destruction mechanism of the molecules within the ionized gas, as shown for low-metallicity galaxies by Madden et al.

  12. The Dependence of the Strength and Thickness of Field-Aligned Currents on Solar Wind and Ionospheric Parameters

    SciTech Connect

    Johnson, Jay R.; Wing, Simon

    2014-08-01

    Sheared plasma flows at the low-latitude boundary layer correlate well with early afternoon auroral arcs and eld-aligned currents [Sonnerup, 1980; Lundin and Evans, 1985]. We present a simple analytic model that relates solar wind and ionospheric parameters to the strength and thickness of field-aligned currents in a region of sheared velocity, such as the low latitude boundary layer. We compare the predictions of the model with DMSP observations and nd remarkably good scaling of the currents with solar wind and ionospheric parameters. The sheared boundary layer thickness is inferred to be around 3000km consistent with observational studies. The analytic model provides a simple way to organize data and to infer boundary layer structures from ionospheric data.

  13. Impact of field strength and iron oxide nanoparticle concentration on the linearity and diagnostic accuracy of off-resonance imaging.

    PubMed

    Farrar, Christian T; Dai, Guangping; Novikov, Mikhail; Rosenzweig, Anthony; Weissleder, Ralph; Rosen, Bruce R; Sosnovik, David E

    2008-06-01

    Off-resonance imaging (ORI) techniques are being increasingly used to image iron oxide imaging agents such as monocrystalline iron oxide nanoparticles (MION). However, the diagnostic accuracy, linearity, and field dependence of ORI have not been fully characterized. In this study, the sensitivity, specificity, and linearity of ORI were thus examined as a function of both MION concentration and magnetic field strength (4.7 and 14 T). MION phantoms with and without an air interface as well as MION uptake in a mouse model of healing myocardial infarction were imaged. MION-induced resonance shifts were shown to increase linearly with MION concentration. In contrast, the ORI signal/sensitivity was highly non-linear, initially increasing with MION concentration until T2 became comparable to the TE and decreasing thereafter. The specificity of ORI to distinguish MION-induced resonance shifts from on-resonance water was found to decrease with increasing field because of the increased on-resonance water linewidths (15 Hz at 4.7 T versus 45 Hz at 14 T). Large resonance shifts ( approximately 300 Hz) were observed at air interfaces at 4.7 T, both in vitro and in vivo, and led to poor ORI specificity for MION concentrations less than 150 microg Fe/mL. The in vivo ORI sensitivity was sufficient to detect the accumulation of MION in macrophages infiltrating healing myocardial infarcts, but the specificity was limited by non-specific areas of positive contrast at the air/tissue interfaces of the thoracic wall and the descending aorta. Improved specificity and linearity can, however, be expected at lower fields where decreased on-resonance water linewidths, reduced air-induced resonance shifts, and longer T2 relaxation times are observed. The optimal performance of ORI will thus likely be seen at low fields, with moderate MION concentrations and with sequences containing very short TEs.

  14. Enhancing the quantification of tissue sodium content by MRI: time-efficient sodium B1 mapping at clinical field strengths.

    PubMed

    Lommen, Jonathan; Konstandin, Simon; Krämer, Philipp; Schad, Lothar R

    2016-02-01

    Tissue sodium content (TSC) is a sensitive measure of pathological changes and can be detected non-invasively by MRI. For the absolute quantification of TSC, B1 inhomogeneities must be corrected, which is not well established beyond research applications. An in-depth analysis of B1 mapping methods which are suitable for application in TSC quantification is presented. On the basis of these results, a method for simultaneous B1 mapping and imaging is proposed in order to enhance accuracy and to reduce measurement time at clinical field strengths. The B1 mapping techniques used were phase-sensitive (PS), Bloch-Siegert shift (BSS), double-angle (DAM) and actual flip-angle imaging (AFI) methods. Experimental and theoretical comparisons demonstrated that the PS technique yields the most accurate field profiles and exhibits the highest signal-to-noise ratio (SNR). Simultaneous B1 mapping and imaging was performed for the PS method, employing both degrees of freedom of the MR signal: the B1 field is encoded into signal phase and the amplitude provides the concentration information. In comparison with the more established DAM, a 13% higher SNR was obtained and field effects could be corrected more accurately without the need for additional measurement time. The protocol developed was applied to measure TSC in the healthy human head at an isotropic resolution of 4 mm. TSC was determined to be 35 ± 1 mM in white matter and 134 ± 3 mM in vitreous humor. By employing the proposed simultaneous characterization of the B1 field and acquisition of the spin density-weighted sodium signal, the accuracy of the non-invasive measurement of TSC is enhanced and the measurement time is reduced. This should allow (23)Na MRI to be better incorporated into clinical studies and routine.

  15. Bi-Component T2* Analysis of Bound and Pore Bone Water Fractions Fails at High Field Strengths

    PubMed Central

    Seifert, Alan C.; Wehrli, Suzanne L.; Wehrli, Felix W.

    2015-01-01

    Osteoporosis involves degradation of bone’s trabecular architecture, cortical thinning, and enlargement of cortical pores. Increased cortical porosity is a major cause of the decreased strength of osteoporotic bone. The majority of cortical pores, however, are below the resolution limit of MRI. Recent work has shown that porosity can be evaluated by MRI-based quantification of bone water. Bi-exponential T2* fitting and adiabatic inversion preparation are the two most common methods purported to distinguish bound and pore water in order to quantify matrix density and porosity. To assess the viability of T2* bi-component analysis as a method for quantifying bound and pore water fractions, we have applied this method to human cortical bone at 1.5T, 3T, 7T, and 9.4T, and validated the resulting pool fractions against μCT-derived porosity and gravimetrically-determined bone densities. We also investigated alternative methods: 2D T1–T2* bi-component fitting by incorporating saturation-recovery, 1D and 2D fitting of CPMG echo amplitudes, and deuterium inversion recovery. Short-T2* pool fraction was moderately correlated with porosity (R2 = 0.70) and matrix density (R2 = 0.63) at 1.5T, but the strengths of these associations were found to diminish rapidly as field strength increases, falling below R2 = 0.5 at 3T. Addition of the T1 dimension to bi-component analysis only slightly improved the strengths of these correlations. T2*-based bi-component analysis should therefore be used with caution. Performance of deuterium inversion-recovery at 9.4T was also poor (R2 = 0.50 versus porosity and R2 = 0.46 versus matrix density). CPMG-derived short-T2 fraction at 9.4T, however, is highly correlated with porosity (R2 = 0.87) and matrix density (R2 = 0.88), confirming the utility of this method for independent validation of bone water pools. PMID:25981785

  16. 31P NMR Relaxation of Cortical Bone Mineral at Multiple Magnetic Field Strengths and Levels of Demineralization

    PubMed Central

    Seifert, Alan C.; Wright, Alexander C.; Wehrli, Suzanne L.; Ong, Henry H.; Li, Cheng; Wehrli, Felix W.

    2013-01-01

    Purpose Recent work has shown that solid-state 1H and 31P MRI can provide detailed insight into bone matrix and mineral properties, thereby potentially enabling differentiation of osteoporosis from osteomalacia. However, 31P MRI of bone mineral is hampered by unfavorable relaxation properties. Hence, accurate knowledge of these properties is critical to optimizing MRI of bone phosphorus. Methods In this work, 31P MRI signal-to-noise ratio (SNR) was predicted on the basis of T1 and T2* (effective transverse relaxation time) measured in lamb bone at six field strengths (1.5 – 11.7 T) and subsequently verified by 3-D ultra-short echo-time and zero echo-time imaging. Further, T1 was measured in deuterium-exchanged bone and partially demineralized bone. Results 31P T2* was found to decrease from 220.3 ± 4.3 μs to 98.0 ± 1.4 μs from 1.5 to 11.7 T, and T1 to increase from 12.8 ± 0.5 s to 97.3 ± 6.4 s. Deuteron substitution of exchangeable water showed that 76% of the 31P longitudinal relaxation rate is due to 1H-31P dipolar interactions. Lastly, hypomineralization was found to decrease T1, which may have implications for 31P MRI based mineralization density quantification. Conclusion Despite the steep decrease in the T2*/T1 ratio, SNR should increase with field strength as Bo0.4 for sample-dominated noise and as Bo1.1 for coil-dominated noise. This was confirmed by imaging experiments. PMID:23505120

  17. The paleomagnetism of single silicate crystals: Recording geomagnetic field strength during mixed polarity intervals, superchrons, and inner core growth

    NASA Astrophysics Data System (ADS)

    Tarduno, J. A.; Cottrell, R. D.; Smirnov, A. V.

    2006-03-01

    The basic features of the geomagnetic reversal chronology of the last 160 million years are well established. The relationship between this history and other features of the field, however, has been elusive. The determination of past field strength (paleointensity) is especially challenging. Commonly accepted results have come from analyses of bulk samples of lava. Historic lavas have been shown to faithfully record the past field strength when analyzed using the Thellier double-heating method. Data from older lavas, however, tend to show effects of in situ and laboratory-induced alteration. Here we review an alternative approach. Single plagioclase crystals can contain minute magnetic inclusions, 50-350 nm in size, that are potential high-fidelity field recorders. Thellier experiments using plagioclase feldspars from an historic lava on Hawaii provide a benchmark for the method. Rock magnetic data from older lavas indicate that the feldspars are less susceptible to experimental alteration than bulk samples. This resistance is likely related to the lack of clays. In addition, magnetic minerals are sheltered by the encasing silicate matrix from natural alteration that can otherwise transform the well-defined thermoremanent magnetization into an irresolute chemical remanent magnetization. If there is a relationship between geomagnetic reversal frequency and paleointensity, it should be best expressed during superchrons, intervals with few (or no) reversals. Thellier data sets based on single plagioclase crystals from lavas erupted during the Cretaceous Normal Polarity Superchron (~83-120 million years ago) suggest a strong (>12 × 1022 Am2), stable field, consistent with an inverse relationship between reversal frequency and paleointensity. Superchrons may represent times when the pattern of core-mantle boundary heat flux allows the geodynamo to operate at peak efficiency, as suggested in some numerical models. Thellier data from single plagioclase crystals formed

  18. Magnetic Field Strength Dependence of Transverse Relaxation and Signal-to-Noise Ratio for Hyperpolarized Xenon-129 and Helium-3 Gas Magnetic Resonance Imaging of Lungs

    NASA Astrophysics Data System (ADS)

    Dominguez-Viqueira, William

    Magnetic resonance (MR) imaging with hyperpolarized noble gases (HNG), 3He or 129Xe, has become a promising approach for studying lung anatomy and function. Unlike conventional MR imaging, the magnetization in HNG MR is independent of the magnetic field strength. This means that no improvement in signal-to-noise ratio (SNR) is expected with increasing clinical field strength above ˜0.25T. Furthermore, it has been predicted that the SNR may decline at clinical field strength due to decreases in the apparent transverse relaxation time (T2*), caused by the increased magnetic susceptibility induced field gradients at the air-tissue interface. In this thesis the magnetic field strength dependence of T2* and SNR in HNG MR is investigated experimentally in rodent and human lungs. For rodent imaging, a novel broad-band (0.1-100MHz) variable field strength MR imaging system for rodents was built. This system permitted imaging of 129Xe, 3He and 1H at low magnetic field strengths (3-73.5mT) to experimentally investigate the field dependence of HNG imaging SNR in rodent lungs. In vivo 129Xe and 3He signals were acquired at 73.5mT and T 2* was estimated to be approximately 180+/-8 ms, in good agreement with previously reported values. At 73.5mT, image noise is dominated by losses originated from the radiofrequency (RF) coils. To address this issue, RF coils were built using different types of copper wire and compared in phantoms and in vivo in rat lungs using hyperpolarized 3He and 129Xe gas. An SNR improvement of up to 200% was obtained with Litz wire compared to conventional copper wire. This improvement demonstrated the feasibility of HNG lung imaging in rodents at 73.5mT with SNR comparable to that obtained at clinical field strengths. To verify the SNR field dependence in humans, hyperpolarized 3He lung imaging at two commonly used clinical field strengths (1.5T and 3T) was performed in the same volunteers and compared. No significant differences in SNR were obtained

  19. Microchip capillary gel electrophoresis using programmed field strength gradients for the ultra-fast analysis of genetically modified organisms in soybeans.

    PubMed

    Kim, Yun-Jeong; Chae, Joon-Seok; Chang, Jun Keun; Kang, Seong Ho

    2005-08-12

    We have developed a novel method for the ultra-fast analysis of genetically modified organisms (GMOs) in soybeans by microchip capillary gel electrophoresis (MCGE) using programmed field strength gradients (PFSG) in a conventional glass double-T microchip. Under the programmed electric field strength and 0.3% poly(ethylene oxide) sieving matrix, the GMO in soybeans was analyzed within only 11 s of the microchip. The MCGE-PFSG method was a program that changes the electric field strength during GMO analysis, and was also applied to the ultra-fast analysis of PCR products. Compared to MCGE using a conventional and constantly applied electric field, the MCGE-PFSG analysis generated faster results without the loss of resolving power and reproducibility for specific DNA fragments (100- and 250-bp DNA) of GM-soybeans. The MCGE-PFSG technique may prove to be a new tool in the GMO analysis due to its speed, simplicity, and high efficiency.

  20. The influence of magnetic field strength in ionization stage on ion transport between two stages of a double stage Hall thruster

    SciTech Connect

    Yu Daren; Song Maojiang; Li Hong; Liu Hui; Han Ke

    2012-11-15

    It is futile for a double stage Hall thruster to design a special ionization stage if the ionized ions cannot enter the acceleration stage. Based on this viewpoint, the ion transport under different magnetic field strengths in the ionization stage is investigated, and the physical mechanisms affecting the ion transport are analyzed in this paper. With a combined experimental and particle-in-cell simulation study, it is found that the ion transport between two stages is chiefly affected by the potential well, the potential barrier, and the potential drop at the bottom of potential well. With the increase of magnetic field strength in the ionization stage, there is larger plasma density caused by larger potential well. Furthermore, the potential barrier near the intermediate electrode declines first and then rises up while the potential drop at the bottom of potential well rises up first and then declines as the magnetic field strength increases in the ionization stage. Consequently, both the ion current entering the acceleration stage and the total ion current ejected from the thruster rise up first and then decline as the magnetic field strength increases in the ionization stage. Therefore, there is an optimal magnetic field strength in the ionization stage to guide the ion transport between two stages.

  1. The Effect of Dissipation Mechanism and Guide Field Strength on X-line Spreading in 3D Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Shepherd, Lucas; Cassak, P.; Drake, J.; Gosling, J.; Phan, T.; Shay, M. A.

    2013-07-01

    In two-ribbon flares, the fact that the ribbons separate in time is considered evidence of magnetic reconnection. However, in addition to the ribbons separating, they can also elongate (as seen in animations of, for example, the Bastille Day flare). The elongation is undoubtedly related to the reconnection spreading in the out-of-plane direction. Indeed, naturally occurring magnetic reconnection generally begins in a spatially localized region and spreads in the direction perpendicular to the reconnection plane as time progresses. For example, it was suggested that X-line spreading is necessary to explain the observation of X-lines extending more than 390 Earth radii (Phan et al., Nature, 404, 848, 2006), and has been seen in reconnection experiments. A sizeable out-of-plane (guide) magnetic field is present at flare sites and in the solar wind. Here, we study the effect of dissipation mechanism and the strength of the guide field has on X-line spreading. We present results from three-dimensional numerical simulations of magnetic reconnection, comparing spreading with the Hall term to spreading with anomalous resistivity. Applications to solar flares and magnetic reconnection in the solar wind will be discussed.

  2. Crystal-field analysis and calculation of two-photon absorption line strengths of dicesium sodium hexachlorogadolinate(III).

    PubMed

    Duan, Chang-Kui; Tanner, Peter A

    2010-03-31

    The crystal-field energy level calculation of the 4f(7) ion Gd(3+) in the crystal Cs(2)NaGdCl(6) has fitted 45 levels with standard deviation 12 cm(-1), with the energy parameters being consistent with those from other studies. The resulting eigenvectors have been employed in the calculation of two-photon absorption (TPA) intensities of transitions from the electronic ground state (8)S(7/2) to the crystal-field levels of excited (6)P, (6)I and (6)D multiplet terms. The TPA line strengths are highly polarization dependent and exhibit striking differences for linearly polarized incident radiation compared with circularly polarized radiation. The relative intensities are compared with those available from previous experimental studies and some reassignments have been made. Good agreement of calculated and experimental TPA spectra is found, except for the intensity ratio of the transitions to (6)P(7/2) or (6)P(5/2) compared with that to (6)P(3/2), for linear and circular polarizations, where the calculation overestimates the ratio. Reasons for this disagreement are presented.

  3. Long-term variation of statistical properties of sunspot field strengths and their relation to the characteristics of solar cycles in 1917-2013

    NASA Astrophysics Data System (ADS)

    Tlatova, Kseniya; Pevtsov, Alexei; Tlatov, Andrey; Vasilieva, Valeria; Kalevi Mursula

    We use the digitized sunspot daily drawings from the Mount Wilson Observatory (MWO) from 1917—2013 to study the long-term variations in sunspot magnetic fields. Tabulated data include the heliographic coordinates, area and magnetic field strength of all sunspots on solar disk. Sunspot field strengths exhibit several trends, which can be of instrumental or truly solar in its nature. For example, in depth analysis of the sunspot field strength and the sunspot areas indicates long-term changes in the observing system at the MWO, when systematically larger number of measurements in sub-features (e.g., multiple umbrae) was made beginning mid-20th century. The final data set is used to study several properties of active regions including difference (in field strength and area) between leading and following sunspots, the orientation of magnetic field in sunspots and pores relative to vertical direction, and the Hale (polarity) and Joy (tilt) laws over the period of about ten solar cycles.

  4. MRS thermometry calibration at 3 T: effects of protein, ionic concentration and magnetic field strength.

    PubMed

    Babourina-Brooks, Ben; Simpson, Robert; Arvanitis, Theodoros N; Machin, Graham; Peet, Andrew C; Davies, Nigel P

    2015-07-01

    MRS thermometry has been utilized to measure temperature changes in the brain, which may aid in the diagnosis of brain trauma and tumours. However, the temperature calibration of the technique has been shown to be sensitive to non-temperature-based factors, which may provide unique information on the tissue microenvironment if the mechanisms can be further understood. The focus of this study was to investigate the effects of varied protein content on the calibration of MRS thermometry at 3 T, which has not been thoroughly explored in the literature. The effects of ionic concentration and magnetic field strength were also considered. Temperature reference materials were controlled by water circulation and freezing organic fixed-point compounds (diphenyl ether and ethylene carbonate) stable to within 0.2 °C. The temperature was measured throughout the scan time with a fluoro-optic probe, with an uncertainty of 0.16 °C. The probe was calibrated at the National Physical Laboratory (NPL) with traceability to the International Temperature Scale 1990 (ITS-90). MRS thermometry measures were based on single-voxel spectroscopy chemical shift differences between water and N-acetylaspartate (NAA), Δ(H20-NAA), using a Philips Achieva 3 T scanner. Six different phantom solutions with varying protein or ionic concentration, simulating potential tissue differences, were investigated within a temperature range of 21-42 °C. Results were compared with a similar study performed at 1.5 T to observe the effect of field strengths. Temperature calibration curves were plotted to convert Δ(H20-NAA) to apparent temperature. The apparent temperature changed by -0.2 °C/% of bovine serum albumin (BSA) and a trend of 0.5 °C/50 mM ionic concentration was observed. Differences in the calibration coefficients for the 10% BSA solution were seen in this study at 3 T compared with a study at 1.5 T. MRS thermometry may be utilized to measure temperature and the tissue

  5. Review and analysis of VHF/UHF field strength measurements: Measurements at VHF over path lengths greater than 100 km

    NASA Astrophysics Data System (ADS)

    Sandell, R. S.; Bell, C. P.; Taplin, D. W.

    1986-12-01

    In 1983 CCIRIWP 5/5 put forward a number of proposals for improvements to the field strength prediction methods of CCIR Recommendation 370 and associated Report 239, as used for international planning negotiations in the VHF and UHF Broadcast Bands. Described are the results of studies carried out by the BBC, in conjunction with other propagation investigations, to assess the validity of those proposals of IWP 5/5 which relate to propagation over path lengths in excess of about 100 km in the VHF Bands. It is concluded that these proposals can be supported with only one exception, relating to an addition of 7 dB to beyond-horizon oversea curves. Subsequently, the VHF proposals (excepting the one relating to the 7 dB correction) have been endorsed by CCIR Study Group 5 and adopted by the Plenar Meeting in 1986 for inclusion as modifications to Recommendation 370. Even so, limitations in the exsiting methods are identified and further work is proposed.

  6. The effects of nonuniform magnetic field strength on density flux and test particle transport in drift wave turbulence

    SciTech Connect

    Dewhurst, J. M.; Hnat, B.; Dendy, R. O.

    2009-07-15

    The extended Hasegawa-Wakatani equations generate fully nonlinear self-consistent solutions for coupled density n and vorticity {nabla}{sup 2}{phi}, where {phi} is electrostatic potential, in a plasma with background density inhomogeneity {kappa}=-{partial_derivative} ln n{sub 0}/{partial_derivative}x and magnetic field strength inhomogeneity C=-{partial_derivative} ln B/{partial_derivative}x. Finite C introduces interchange effects and {nabla}B drifts into the framework of drift turbulence through compressibility of the ExB and diamagnetic drifts. This paper addresses the direct computation of the radial ExB density flux {gamma}{sub n}=-n{partial_derivative}{phi}/{partial_derivative}y, tracer particle transport, the statistical properties of the turbulent fluctuations that drive {gamma}{sub n} and tracer motion, and analytical underpinnings. Systematic trends emerge in the dependence on C of the skewness of the distribution of pointwise {gamma}{sub n} and in the relative phase of density-velocity and density-potential pairings. It is shown how these effects, together with conservation of potential vorticity {pi}={nabla}{sup 2}{phi}-n+({kappa}-C)x, account for much of the transport phenomenology. Simple analytical arguments yield a Fickian relation {gamma}{sub n}=({kappa}-C)D{sub x} between the radial density flux {gamma}{sub n} and the radial tracer diffusivity D{sub x}, which is shown to explain key trends in the simulations.

  7. Effect of electrical field strength applied by PEF processing and storage temperature on the outgrowth of yeasts and moulds naturally present in a fresh fruit smoothie.

    PubMed

    Timmermans, R A H; Nederhoff, A L; Nierop Groot, M N; van Boekel, M A J S; Mastwijk, H C

    2016-08-02

    Pulsed electrical field (PEF) technology offers an alternative to thermal pasteurisation of high-acid fruit juices, by extending the shelf life of food products, while retaining its fresh taste and nutritional value. Substantial research has been performed on the effect of electrical field strength on the inactivation kinetics of spoilage and pathogenic micro-organisms and on the outgrowth of spoilage micro-organisms during shelf life. However, studies on the effect of electrical field strength on the inactivation and outgrowth of surviving populations during shelf life are missing. In this study, we assessed the influence of electrical field strength applied by PEF processing and storage temperature on the outgrowth of surviving yeast and mould populations naturally present in fresh fruit smoothie in time. Therefore, an apple-strawberry-banana smoothie was treated in a continuous-flow PEF system (130L/h), using similar inlet and outlet conditions (preheating temperature 41°C, maximum temperature 58°C) to assure that the amount of energy across the different conditions was kept constant. Smoothies treated with variable electrical field strengths (13.5, 17.0, 20.0 and 24.0kV/cm) were compared to smoothies without treatment for outgrowth of yeasts and moulds. Outgrowth of yeasts and moulds stored at 4°C and 7°C was analysed by plating and visual observation and yeast growth was modelled using the modified logistic growth model (Zwietering model). Results showed that the intensity of the electrical field strength had an influence on the degree of inactivation of yeast cells, resulting in a faster outgrowth over time at lower electrical field strength. Outgrowth of moulds over time was not affected by the intensity of the electrical field strength used. Application of PEF introduces a trade-off between type of spoilage: in untreated smoothie yeasts lead to spoilage after 8days when stored at 4 or 7°C, whereas in PEF treated smoothie yeasts were (partly

  8. The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-Driven Shock

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat; Yashiro, Seiji

    2011-01-01

    We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfven Mach number, and hence the Alfven speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from approximately 48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances.

  9. The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-driven Shock

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Nat; Yashiro, Seiji

    2011-07-01

    We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfvén Mach number, and hence the Alfvén speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from ~48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances.

  10. Microchip gel electrophoresis with programmed field strength gradients for ultra-fast detection of canine T-cell lymphoma in dogs.

    PubMed

    Suresh, Kumar K; Lee, Mi-Jin; Park, Jinho; Kang, Seong Ho

    2008-03-15

    This paper describes the applicability of microchip gel electrophoresis using a programmed field strength gradients (MGE-PFSG) method coupled with a polymerase chain reaction (PCR) for the ultra-fast diagnosis of canine T-cell lymphoma. The variable region in the T-cell receptor gamma (TCRgamma) gene from a T-cell lymphoma was used in PCR amplification. The contributions of the various parameters, including the effects of the molecular weight, concentration of the sieving matrix and field strength in MGE, were examined. 0.5% poly (ethyleneoxide) (PEO, M(r) 8000000) was used as the sieving matrix for the ultra-rapid separation of the amplified-PCR products (90 and 130-bp DNA fragments) from the PFSG at an effective length of 20mm in a glass microchip. The PCR products (90 and 130-bp DNA) of the T-cell lymphoma were analyzed within 41.7+/-0.1s, 15.5+/-0.2s and only 7.0+/-0.1s using a low-constant field strength, high-constant field strength and the PFSG, respectively. When 11 clinical samples were analyzed using the MGE-PFSG method, there was a 100% correlation with those obtained using conventional slab gel electrophoresis. The ultra-fast detection and rapid separation capabilities of MGE-PFSG make it an efficient tool for diagnosing T-cell lymphoma in clinical samples with high sensitivity.

  11. Using a Combination of Experimental and Computational Methods to Explore the Impact of Metal Identity and Ligand Field Strength on the Electronic Structure of Metal Ions

    ERIC Educational Resources Information Center

    Pernicone, Naomi C.; Geri, Jacob B.; York, John T.

    2011-01-01

    In this exercise, students apply a combination of techniques to investigate the impact of metal identity and ligand field strength on the spin states of three d[superscript 5] transition-metal complexes: Fe(acac)[subscript 3], K[subscript 3][Fe(CN)[subscript 6

  12. An Evaluation of a Numerical Prediction Method for Electric Field Strength of Low Frequency Radio Waves based on Wave-Hop Ionospheric Propagation

    NASA Astrophysics Data System (ADS)

    Kitauchi, H.; Nozaki, K.; Ito, H.; Kondo, T.; Tsuchiya, S.; Imamura, K.; Nagatsuma, T.; Ishii, M.

    2014-12-01

    We present our recent efforts on an evaluation of the numerical prediction method of electric field strength for ionospheric propagation of low frequency (LF) radio waves based on a wave-hop propagation theory described in Section 2.4 of Recommendation ITU-R P.684-6 (2012), "Prediction of field strength at frequencies below about 150 kHz," made by International Telecommunication Union Radiocommunication Sector (ITU-R). As part of the Japanese Antarctic Research Expedition (JARE), we conduct on-board measurements of the electric field strengths and phases of LF 40 kHz and 60 kHz of radio signals (call sign JJY) continuously along both the ways between Tokyo, Japan and Syowa Station, the Japanese Antarctic station, at 69° 00' S, 39° 35' E on East Ongul Island, Lützow-Holm Bay, East Antarctica. The measurements are made by a newly developed, highly sensitive receiving system installed on board the Japanese Antarctic research vessel (RV) Shirase. We obtained new data sets of the electric field strength up to approximately 13,000-14,000 km propagation of LF JJY 40 kHz and 60 kHz radio waves by utilizing a newly developed, highly sensitive receiving system, comprised of an orthogonally crossed double-loop antenna and digital-signal-processing lock-in amplifiers, on board RV Shirase during the 55th JARE from November 2013 to April 2014. We have made comparisons between those on-board measurements and the numerical predictions of field strength for long-range propagation of low frequency radio waves based on a wave-hop propagation theory described in Section 2.4 of Recommendation ITU-R P.684-6 (2012) to show that our results qualitatively support the recommended wave-hop theory for the great-circle paths approximately 7,000-8,000 km and 13,000-14,000 km propagations.

  13. Validation of a scaling law for the coronal magnetic field strength and loop length of solar and stellar flares

    NASA Astrophysics Data System (ADS)

    Namekata, Kosuke; Sakaue, Takahito; Watanabe, Kyoko; Asai, Ayumi; Shibata, Kazunari

    2017-02-01

    Shibata and Yokoyama (1999, ApJ, 526, L49; 2002, ApJ, 577, 422) proposed a method of estimating the coronal magnetic field strength (B) and magnetic loop length (L) of solar and stellar flares, on the basis of magnetohydrodynamic simulations of the magnetic reconnection model. Using the scaling law provided by Shibata and Yokoyama (1999, ApJ, 526, L49; 2002, ApJ, 577, 422), we obtain B and L as functions of the emission measure (EM = n2L3) and temperature (T) at the flare peak. Here, n is the coronal electron density of the flares. This scaling law enables the estimation of B and L for unresolved stellar flares from the observable physical quantities EM and T, which is helpful for studying stellar surface activities. To apply this scaling law to stellar flares, we discuss its validity for spatially resolved solar flares. Quantities EM and T are calculated from GOES (Geostationary Operational Environmental Satellite) soft X-ray flux data, and B and L are theoretically estimated using the scaling law. For the same flare events, B and L were also observationally estimated with images taken by the Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) Magnetogram and Atmospheric Imaging Assembly (AIA) 94 Å pass band. As expected, a positive correlation was found between the theoretically and observationally estimated values. We interpret this result as indirect evidence that flares are caused by magnetic reconnection. Moreover, this analysis makes us confident about the validity of applying this scaling law to stellar flares as well as solar flares.

  14. Ligand Field Strength Mediates Electron Delocalization in Octahedral [((H)L)2Fe6(L')m](n+) Clusters.

    PubMed

    Hernández Sánchez, Raúl; Zheng, Shao-Liang; Betley, Theodore A

    2015-09-02

    To assess the impact of terminal ligand binding on a variety of cluster properties (redox delocalization, ground-state stabilization, and breadth of redox state accessibility), we prepared three electron-transfer series based on the hexanuclear iron cluster [((H)L)2Fe6(L')m](n+) in which the terminal ligand field strength was modulated from weak to strong (L' = DMF, MeCN, CN). The extent of intracore M-M interactions is gauged by M-M distances, spin ground state persistence, and preference for mixed-valence states as determined by electrochemical comproportionation constants. Coordination of DMF to the [((H)L)2Fe6] core leads to weaker Fe-Fe interactions, as manifested by the observation of ground states populated only at lower temperatures (<100 K) and by the greater evidence of valence trapping within the mixed-valence states. Comproportionation constants determined electrochemically (Kc = 10(4)-10(8)) indicate that the redox series exhibits electronic delocalization (class II-III), yet no intervalence charge transfer (IVCT) bands are observable in the near-IR spectra. Ligation of the stronger σ donor acetonitrile results in stabilization of spin ground states to higher temperatures (∼300 K) and a high degree of valence delocalization (Kc = 10(2)-10(8)) with observable IVCT bands. Finally, the anionic cyanide-bound series reveals the highest degree of valence delocalization with the most intense IVCT bands (Kc = 10(12)-10(20)) and spin ground state population beyond room temperature. Across the series, at a given formal oxidation level, the capping ligand on the hexairon cluster dictates the overall properties of the aggregate, modulating the redox delocalization and the persistence of the intracore coupling of the metal sites.

  15. Image Charge and Electric Field Effects on Hydrogen-like Impurity-bound Polaron Energies and Oscillator Strengths in a Quantum Dot

    NASA Astrophysics Data System (ADS)

    Vardanyan, L. A.; Vartanian, A. L.; Asatryan, A. L.; Kirakosyan, A. A.

    2016-11-01

    By using Landau-Pekar variational method, the ground and the first excited state energies and the transition frequencies between the ground and the first excited states of a hydrogen-like impurity-bound polaron in a spherical quantum dot (QD) have been studied by taking into account the image charge effect (ICE). We employ the dielectric continuum model to describe the phonon confinement effects. The oscillator strengths (OSs) of transitions from the 1 s-like state to excited states of 2 s, 2 p x , and 2 p z symmetries are calculated as functions of the applied electric field and strength of the confinement potential. We have shown that with and without image charge effect, the increase of the strength of the parabolic confinement potential leads to the increase of the oscillator strengths of 1 s - 2 p x and 1 s - 2 p z transitions. This indicates that the energy differences between 1 s- and 2 p x - as well as 1 s- and 2 p z -like states have a dominant role determining the oscillator strength. Although there is almost no difference in the oscillator strengths for transitions 1 s - 2 p x and 1 s -2 p z when the image charge effect is not taken into account, it becomes significant with the image charge effect.

  16. No increase of the blood oxygenation level-dependent functional magnetic resonance imaging signal with higher field strength: implications for brain activation studies.

    PubMed

    Seehafer, Jörg U; Kalthoff, Daniel; Farr, Tracy D; Wiedermann, Dirk; Hoehn, Mathias

    2010-04-14

    Experimental data up to 7.0 T show that the blood oxygenation level-dependent (BOLD) signal of functional magnetic resonance imaging (fMRI) increases with higher magnetic field strength. Although several studies at 11.7 T report higher BOLD signal compared with studies at 7.0 T, no direct comparison at these two field strengths has been performed under the exact same conditions. It therefore remains unclear whether the expected increase of BOLD effect with field strength will still continue to hold for fields >7.0 T. To examine this issue, we compared the BOLD activation signal at 7.0 and 11.7 T with the two common sequences, spin-echo (SE) and gradient-echo (GE) echo planar imaging (EPI). We chose the physiologically well controlled rat model of electrical forepaw stimulation under medetomidine sedation. While a linear to superlinear increase in activation with field strengths up to 7.0 T was reported in the literature, we observed no significant activation difference between 7.0 and 11.7 T with either SE or GE. Discussing the results in light of the four-component model of the BOLD signal, we showed that at high field only two extravascular contributions remain relevant, while both intravascular components vanish. Constancy of the BOLD effect is discussed due to motional narrowing, i.e., susceptibility gradients become so strong that phase variance of diffusing spins decreases and therefore the BOLD signal also decreases. This finding will be of high significance for the planning of future human and animal fMRI studies at high fields and their quantitative analysis.

  17. Dependences of Q-branch integrated intensity of linear-molecule pendular spectra on electric-field strength and rotational temperature and its potential applications

    PubMed Central

    Deng, Min; Wang, Hailing; Wang, Qin; Yin, Jianping

    2016-01-01

    We calculate the pendular-state spectra of cold linear molecules, and investigated the dependences of “Q-branch” integrated intensity of pendular spectra on both electric-field strength and molecular rotation-temperature. A new multi-peak structure in the “Q-branch” spectrum is appearing when the Stark interaction strength ω = μE/B equal to or larger than the critical value. Our study shows that the above results can be used not only to measure the electric-field vector and its spatial distribution in some electrostatic devices, such as the Stark decelerator, Stark velocity filter and electrostatic trap and so on, but also to survey the orientation degree of cold linear molecules in a strong electrostatic field. PMID:27231057

  18. Variations in the geomagnetic field strength in the 5th 3rd centuries BC in the eastern Mediterranean (according to narrowly dated ceramics)

    NASA Astrophysics Data System (ADS)

    Nachasova, I. E.; Burakov, K. S.; Il'Ina, T. A.

    2008-06-01

    The magnetization of ceramics from the eastern Mediterranean dated within a short period (mostly shorter than ±20 years) has been studied, which made it possible to specify the geomagnetic field variations on the time interval 5th 3rd centuries BC. The 11-year time series of the geomagnetic field strength values has been constructed. The field strength changes have been considered, which indicated that the centennial variation with a characteristic time of ˜130 years (according to the obtained data) is observed on this time interval as well as during the last two millennia. The ceramic material from the Mayskaya Gora archeological site (Taman), the preparation succession of which was established based on the shape of pottery but the problem of absolute dating was not solved, has been dated.

  19. Dependences of Q-branch integrated intensity of linear-molecule pendular spectra on electric-field strength and rotational temperature and its potential applications

    NASA Astrophysics Data System (ADS)

    Deng, Min; Wang, Hailing; Wang, Qin; Yin, Jianping

    2016-05-01

    We calculate the pendular-state spectra of cold linear molecules, and investigated the dependences of “Q-branch” integrated intensity of pendular spectra on both electric-field strength and molecular rotation-temperature. A new multi-peak structure in the “Q-branch” spectrum is appearing when the Stark interaction strength ω = μE/B equal to or larger than the critical value. Our study shows that the above results can be used not only to measure the electric-field vector and its spatial distribution in some electrostatic devices, such as the Stark decelerator, Stark velocity filter and electrostatic trap and so on, but also to survey the orientation degree of cold linear molecules in a strong electrostatic field.

  20. Relative strength of lithospheric mantle compared to granulite lower crust in orogenic roots: insight from field laboratory.

    NASA Astrophysics Data System (ADS)

    Kusbach, V.; Ulrich, S.; Schulmann, K.

    2009-04-01

    The continental lithosphere is composed by strong lithospheric mantle and weak lower crust for average and hot geotherms. However, some experiments and seismic studies show that the strength contrast between mantle and crust can vary in order of several magnitudes. The internal zone of the European Variscan orogen (Bohemian Massif, Czech Republic) contains large complexes of Ky - K-feldspar granulites with incorporated spinel and garnet peridotites that can respond to question of mantle-lower crust strength contrast from the field perspective. The studied spinel-garnet harzburgite body (the Mohelno peridotite) represents probably a fragment of strongly depleted oceanic lithosphere showing peak conditions of 22,4-27,6 kbar and 1120-1275°C. The peridotite forms large folded sheet with steep hinge and vertical axial plane. It exhibits presence of spinel along the outer arc and the internal part of the fold and garnet along inner arc, both related to coarse-grained orthopyroxene - olivine microstructure. This coarse microstructure is dynamically recrystallized forming fine-grained matrix (~10 - 20 microns) and the EBSD measurements show presence of axial [100] LPO olivine pattern dominantly along the outer arc of the fold and in spinel harzburgite, while the inner arc of the fold and partly also garnet harzburgite reveals presence of axial [010] LPO pattern. Steep foliation and sub-horizontal to moderately plunging lineation determined from olivine EBSD data defines the shape of the megafold. Host rocks exhibit transposed mylonitic fabric S1-2 revealing peak conditions of 18 kbar, 800°C and heterogeneous D3 retrogression at about 10 - 7 kbar, 650°C. The foliation S2-3 is fully concordant with limbs of peridotite megafold, but close to the outer arc it is affected by asymmetrical folds with axial planar leucosomes coherent with the shape of the megafold hinge zone. In contrast, the S2 in the internal part of the megafold is affected by sinistral and dextral melt

  1. Pulsed electromagnetic fields partially preserve bone mass, microarchitecture, and strength by promoting bone formation in hindlimb-suspended rats.

    PubMed

    Jing, Da; Cai, Jing; Wu, Yan; Shen, Guanghao; Li, Feijiang; Xu, Qiaoling; Xie, Kangning; Tang, Chi; Liu, Juan; Guo, Wei; Wu, Xiaoming; Jiang, Maogang; Luo, Erping

    2014-10-01

    A large body of evidence indicates that pulsed electromagnetic fields (PEMF), as a safe and noninvasive method, could promote in vivo and in vitro osteogenesis. Thus far, the effects and underlying mechanisms of PEMF on disuse osteopenia and/or osteoporosis remain poorly understood. Herein, the efficiency of PEMF on osteoporotic bone microarchitecture, bone strength, and bone metabolism, together with its associated signaling pathway mechanism, was systematically investigated in hindlimb-unloaded (HU) rats. Thirty young mature (3-month-old), male Sprague-Dawley rats were equally assigned to control, HU, and HU + PEMF groups. The HU + PEMF group was subjected to daily 2-hour PEMF exposure at 15 Hz, 2.4 mT. After 4 weeks, micro-computed tomography (µCT) results showed that PEMF ameliorated the deterioration of trabecular and cortical bone microarchitecture. Three-point bending test showed that PEMF mitigated HU-induced reduction in femoral mechanical properties, including maximum load, stiffness, and elastic modulus. Moreover, PEMF increased serum bone formation markers, including osteocalcin (OC) and N-terminal propeptide of type 1 procollagen (P1NP); nevertheless, PEMF exerted minor inhibitory effects on bone resorption markers, including C-terminal crosslinked telopeptides of type I collagen (CTX-I) and tartrate-resistant acid phosphatase 5b (TRAcP5b). Bone histomorphometric analysis demonstrated that PEMF increased mineral apposition rate, bone formation rate, and osteoblast numbers in cancellous bone, but PEMF caused no obvious changes on osteoclast numbers. Real-time PCR showed that PEMF promoted tibial gene expressions of Wnt1, LRP5, β-catenin, OPG, and OC, but did not alter RANKL, RANK, or Sost mRNA levels. Moreover, the inhibitory effects of PEMF on disuse-induced osteopenia were further confirmed in 8-month-old mature adult HU rats. Together, these results demonstrate that PEMF alleviated disuse-induced bone loss by promoting skeletal anabolic activities

  2. Reduction of bone strength

    NASA Technical Reports Server (NTRS)

    Bingham, Cindy

    1990-01-01

    Viewgraphs on reduction of bone strength are presented. WEHI 231 B growth rates, experimental chambers used to apply the electric field to the cell cultures, and a mouse suspended by rotating cuff in electromagnetic field are shown.

  3. Multi-site study of diffusion metric variability: effects of site, vendor, field strength, and echo time on regions-of-interest and histogram-bin analyses

    NASA Astrophysics Data System (ADS)

    Helmer, K. G.; Chou, M.-C.; Preciado, R. I.; Gimi, B.; Rollins, N. K.; Song, A.; Turner, J.; Mori, S.

    2016-03-01

    It is now common for magnetic-resonance-imaging (MRI) based multi-site trials to include diffusion-weighted imaging (DWI) as part of the protocol. It is also common for these sites to possess MR scanners of different manufacturers, different software and hardware, and different software licenses. These differences mean that scanners may not be able to acquire data with the same number of gradient amplitude values and number of available gradient directions. Variability can also occur in achievable b-values and minimum echo times. The challenge of a multi-site study then, is to create a common protocol by understanding and then minimizing the effects of scanner variability and identifying reliable and accurate diffusion metrics. This study describes the effect of site, scanner vendor, field strength, and TE on two diffusion metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA) using two common analyses (region-of-interest and mean-bin value of whole brain histograms). The goal of the study was to identify sources of variability in diffusion-sensitized imaging and their influence on commonly reported metrics. The results demonstrate that the site, vendor, field strength, and echo time all contribute to variability in FA and MD, though to different extent. We conclude that characterization of the variability of DTI metrics due to site, vendor, field strength, and echo time is a worthwhile step in the construction of multi-center trials.

  4. Multi-site study of diffusion metric variability: effects of site, vendor, field strength, and echo time on regions-of-interest and histogram-bin analyses

    PubMed Central

    Helmer, K. G.; Chou, M-C.; Preciado, R. I.; Gimi, B.; Rollins, N. K.; Song, A.; Turner, J.; Mori, S.

    2016-01-01

    It is now common for magnetic-resonance-imaging (MRI) based multi-site trials to include diffusion-weighted imaging (DWI) as part of the protocol. It is also common for these sites to possess MR scanners of different manufacturers, different software and hardware, and different software licenses. These differences mean that scanners may not be able to acquire data with the same number of gradient amplitude values and number of available gradient directions. Variability can also occur in achievable b-values and minimum echo times. The challenge of a multi-site study then, is to create a common protocol by understanding and then minimizing the effects of scanner variability and identifying reliable and accurate diffusion metrics. This study describes the effect of site, scanner vendor, field strength, and TE on two diffusion metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA) using two common analyses (region-of-interest and mean-bin value of whole brain histograms). The goal of the study was to identify sources of variability in diffusion-sensitized imaging and their influence on commonly reported metrics. The results demonstrate that the site, vendor, field strength, and echo time all contribute to variability in FA and MD, though to different extent. We conclude that characterization of the variability of DTI metrics due to site, vendor, field strength, and echo time is a worthwhile step in the construction of multi-center trials. PMID:27330240

  5. 41 CFR 60-30.4 - Form, filing, service of pleadings and papers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... pleadings and papers. 60-30.4 Section 60-30.4 Public Contracts and Property Management Other Provisions... EXECUTIVE ORDER 11246 General Provisions § 60-30.4 Form, filing, service of pleadings and papers. (a) Form. The original of all pleadings and papers in a proceeding conducted under the regulations in this...

  6. 41 CFR 60-30.4 - Form, filing, service of pleadings and papers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... pleadings and papers. 60-30.4 Section 60-30.4 Public Contracts and Property Management Other Provisions... EXECUTIVE ORDER 11246 General Provisions § 60-30.4 Form, filing, service of pleadings and papers. (a) Form. The original of all pleadings and papers in a proceeding conducted under the regulations in this...

  7. 41 CFR 60-30.4 - Form, filing, service of pleadings and papers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... pleadings and papers. 60-30.4 Section 60-30.4 Public Contracts and Property Management Other Provisions... EXECUTIVE ORDER 11246 General Provisions § 60-30.4 Form, filing, service of pleadings and papers. (a) Form. The original of all pleadings and papers in a proceeding conducted under the regulations in this...

  8. Scaling submillimeter single-cycle transients toward megavolts per centimeter field strength via optical rectification in the organic crystal OH1.

    PubMed

    Ruchert, Clemens; Vicario, Carlo; Hauri, Christoph P

    2012-03-01

    We present the generation of high-power single-cycle terahertz (THz) pulses in the organic salt crystal 2-[3-(4-hydroxystyryl)-5.5-dimethylcyclohex-2-enylidene]malononitrile or OH1. Broadband THz radiation with a central frequency of 1.5 THz (λ(c)=200 μm) and high electric field strength of 440 kV/cm is produced by optical rectification driven by the signal of a powerful femtosecond optical parametric amplifier. A 1.5% pump to THz energy conversion efficiency is reported, and pulse energy stability better than 1% RMS is achieved. An approach toward the realization of higher field strength is discussed.

  9. Determination of inverse electric field strength of Ta 218O 5 film produced in biological electrolytes using 18O(p, α) 15N nuclear reaction analysis

    NASA Astrophysics Data System (ADS)

    Wosu, Sylvanus N.

    2005-08-01

    A 18O(p, α) 15N nuclear reaction analysis (NRA) method was developed for the determination of inverse electric field strengths (also referred to as anodic constants) of Ta 2O 5 oxide films prepared in biological solutions (urine, blood plasma and serum). The results show that fresh biological electrolytes have inverse electric field strengths equal to 17.5 ± 1.2, 17.3 ± 1.2, 17.3 ± 0.8 Å/V for plasma, serum and urine, respectively compared to 16.2 ± 0.2 and 15.7 Å/V, for 3% ammonium citrate water and distilled water, respectively. The inverse electric field strength is shown to depend on the pH variation, the metal substrate and the electrolytic ionic concentration. Freezing or aging of the biological sample results in greater variation and reduction of solution pH. Particle-induced X-ray emission (PIXE) and energy dispersive X-ray (EDS) analyses show no incorporation of ions of Z > 11.

  10. Rutile-Melt Partitioning of High Field Strength Elements: New Constraints on the Nature of the Subduction Component

    NASA Astrophysics Data System (ADS)

    Gaetani, G. A.

    2005-12-01

    A compositional feature that distinguishes subduction-related lavas from oceanic basalts is depletion of the high field strength elements (HFSE), such as Ti, Zr, Nb, and Ta [1,2]. Similar depletions also characterize many continental basalts [3,4], and have been inferred for the bulk continental crust [5,6]. Because the HFSE are compatible in rutile (TiO2), it has been posited that their depletion in island arc basalts (IAB) is due to its presence as a residual phase, either in the subducted oceanic crust or the mantle wedge. Here I present results from new experiments that investigate the influences of pressure, temperature, and composition on the partitioning of Zr4+, Nb5+, Hf4+, and Ta5+ between rutile and silicate melt. These results demonstrate that low-degree partial melting of rutile-bearing subducted oceanic crust would produce significant, identifiable fractionations among the HFSE, providing a test for the nature of the subduction component. Experiments were carried out on 2 SiO2-Al2O3-MgO-CaO-Na2O-K2O base melt compositions (rhyodacite; basalt). Rutile saturation was achieved by adding 10-40 wt% TiO2. Each starting composition was doped with ZrO2, Nb2O5, HfO2, and Ta2O5. Low-pressure experiments were carried out using sealed Pt capsules in a vertical quenching furnace. High pressure experiments were carried out in graphite capsules using a solid-medium piston-cylinder device. The major element composition of glass and rutile, as well as the trace element content of the rutile, were determined by electron microprobe. The trace element content of the glass was determined SIMS. At 1 bar and temperatures of 1250 ° to 1450 °C the concentration of TiO2 at rutile saturation is significantly higher in the basalt (17-38 wt%) than the rhyodacite (5-12 wt%). Rutile-melt partition coefficients for the HFSE are higher for the rhyodacite than for the basalt by a factor of ~2-5. Partition coefficients for Nb5+ and Ta5+ are larger than those for Zr4+ and Hf4+ in all

  11. Coronal Magnetic Field Strength from Decameter Zebra-Pattern Observations: Complementarity with Band-Splitting Measurements of an Associated Type II Burst

    NASA Astrophysics Data System (ADS)

    Stanislavsky, A. A.; Konovalenko, A. A.; Koval, A. A.; Dorovskyy, V. V.; Zarka, P.; Rucker, H. O.

    2015-01-01

    A zebra pattern and a type II burst with band splitting were analyzed to study the coronal magnetic field in the height range of 1.9 - 2 solar radii. To this aim we used an extremely sensitive telescope (the Ukrainian decameter radio telescope, UTR-2) with a low-noise, high-dynamic-range spectrometer for the observations below 32 MHz. Based on the analysis of the spectral structures, the field strength obtained is 0.43 G. The value was found by fitting two different field indicators together under the assumptions that the shock wave front was perpendicular to the radial direction, and the radio emission of the type II burst was in the fundamental frequency. The result is compared to and agrees with coronal magnetic-field models.

  12. MRI-derived measurements of human subcortical, ventricular and intracranial brain volumes: Reliability effects of scan sessions, acquisition sequences, data analyses, scanner upgrade, scanner vendors and field strengths.

    PubMed

    Jovicich, Jorge; Czanner, Silvester; Han, Xiao; Salat, David; van der Kouwe, Andre; Quinn, Brian; Pacheco, Jenni; Albert, Marilyn; Killiany, Ronald; Blacker, Deborah; Maguire, Paul; Rosas, Diana; Makris, Nikos; Gollub, Randy; Dale, Anders; Dickerson, Bradford C; Fischl, Bruce

    2009-05-15

    Automated MRI-derived measurements of in-vivo human brain volumes provide novel insights into normal and abnormal neuroanatomy, but little is known about measurement reliability. Here we assess the impact of image acquisition variables (scan session, MRI sequence, scanner upgrade, vendor and field strengths), FreeSurfer segmentation pre-processing variables (image averaging, B1 field inhomogeneity correction) and segmentation analysis variables (probabilistic atlas) on resultant image segmentation volumes from older (n=15, mean age 69.5) and younger (both n=5, mean ages 34 and 36.5) healthy subjects. The variability between hippocampal, thalamic, caudate, putamen, lateral ventricular and total intracranial volume measures across sessions on the same scanner on different days is less than 4.3% for the older group and less than 2.3% for the younger group. Within-scanner measurements are remarkably reliable across scan sessions, being minimally affected by averaging of multiple acquisitions, B1 correction, acquisition sequence (MPRAGE vs. multi-echo-FLASH), major scanner upgrades (Sonata-Avanto, Trio-TrioTIM), and segmentation atlas (MPRAGE or multi-echo-FLASH). Volume measurements across platforms (Siemens Sonata vs. GE Signa) and field strengths (1.5 T vs. 3 T) result in a volume difference bias but with a comparable variance as that measured within-scanner, implying that multi-site studies may not necessarily require a much larger sample to detect a specific effect. These results suggest that volumes derived from automated segmentation of T1-weighted structural images are reliable measures within the same scanner platform, even after upgrades; however, combining data across platform and across field-strength introduces a bias that should be considered in the design of multi-site studies, such as clinical drug trials. The results derived from the young groups (scanner upgrade effects and B1 inhomogeneity correction effects) should be considered as preliminary and in

  13. How accurately can subject-specific finite element models predict strains and strength of human femora? Investigation using full-field measurements.

    PubMed

    Grassi, Lorenzo; Väänänen, Sami P; Ristinmaa, Matti; Jurvelin, Jukka S; Isaksson, Hanna

    2016-03-21

    Subject-specific finite element models have been proposed as a tool to improve fracture risk assessment in individuals. A thorough laboratory validation against experimental data is required before introducing such models in clinical practice. Results from digital image correlation can provide full-field strain distribution over the specimen surface during in vitro test, instead of at a few pre-defined locations as with strain gauges. The aim of this study was to validate finite element models of human femora against experimental data from three cadaver femora, both in terms of femoral strength and of the full-field strain distribution collected with digital image correlation. The results showed a high accuracy between predicted and measured principal strains (R(2)=0.93, RMSE=10%, 1600 validated data points per specimen). Femoral strength was predicted using a rate dependent material model with specific strain limit values for yield and failure. This provided an accurate prediction (<2% error) for two out of three specimens. In the third specimen, an accidental change in the boundary conditions occurred during the experiment, which compromised the femoral strength validation. The achieved strain accuracy was comparable to that obtained in state-of-the-art studies which validated their prediction accuracy against 10-16 strain gauge measurements. Fracture force was accurately predicted, with the predicted failure location being very close to the experimental fracture rim. Despite the low sample size and the single loading condition tested, the present combined numerical-experimental method showed that finite element models can predict femoral strength by providing a thorough description of the local bone mechanical response.

  14. A Laboratory Study to Determine the Effect of Field Strength and Magnetic Susceptibility on the NMR Estimated Water Content in Unconsolidated Sediments

    NASA Astrophysics Data System (ADS)

    Keating, K.; Grunewald, E. D.; Walsh, D. O.

    2015-12-01

    Geophysical nuclear magnetic resonance (NMR) well logging data can provide direct information about subsurface water content. While NMR water content estimates are known to be accurate in low magnetic susceptibility materials, it has often been assumed that NMR measurements cannot be used in high magnetic susceptibility materials due to internal magnetic field inhomogeneities that arise due to magnetic susceptibility contrasts in the material. In this study we compare the NMR estimated water content using laboratory measurements made at two low magnetic field strengths (with Larmor frequencies of 275 kHz and 2 MHz) on both synthetic and natural unconsolidated sediments with a range of magnetic susceptibility values. NMR measurements were collected on seven water-saturated materials with magnetic susceptibility values spanning three orders of magnitude (3.6x10-6 SI to 7.0 x10-3 SI). T2 relaxation time data was collected with echo times, tE, ranging from 200 to 3000 μs. The results show that for the materials with low magnetic susceptibilities (< 5x10-4 SI), the total water content was accurately estimated at both field strengths. For the materials with high magnetic susceptibilities (> 5x10-4 SI) the water content was more accurately estimated using the data collected at 275 kHz (> 80% detected at tE = 400 μs) than the data collected at 2 MHz (< 40% detected at tE = 400 μs). Furthermore, the 275 kHz data showed water content underestimation errors increased only slightly with increased tE, compared to substantial increases in errors for the 2 MHz data as tE was increased. This finding suggests that there is an advantage for collecting measurements at lower field strengths even for long tE. We explain the differences in the water content estimates at the two field strengths by considering the shape of the echoes and the coil and pulse bandwidths, and find excellent agreement with the range of collected NMR data.

  15. A highly optimized code for calculating atomic data at neutron star magnetic field strengths using a doubly self-consistent Hartree-Fock-Roothaan method

    NASA Astrophysics Data System (ADS)

    Schimeczek, C.; Engel, D.; Wunner, G.

    2012-07-01

    Our previously published code for calculating energies and bound-bound transitions of medium-Z elements at neutron star magnetic field strengths [D. Engel, M. Klews, G. Wunner, Comput. Phys. Comm. 180 (2009) 302-311] was based on the adiabatic approximation. It assumes a complete decoupling of the (fast) gyration of the electrons under the action of the magnetic field and the (slow) bound motion along the field under the action of the Coulomb forces. For the single-particle orbitals this implied that each is a product of a Landau state and an (unknown) longitudinal wave function whose B-spline coefficients were determined self-consistently by solving the Hartree-Fock equations for the many-electron problem on a finite-element grid. In the present code we go beyond the adiabatic approximation, by allowing the transverse part of each orbital to be a superposition of Landau states, while assuming that the longitudinal part can be approximated by the same wave function in each Landau level. Inserting this ansatz into the energy variational principle leads to a system of coupled equations in which the B-spline coefficients depend on the weights of the individual Landau states, and vice versa, and which therefore has to be solved in a doubly self-consistent manner. The extended ansatz takes into account the back-reaction of the Coulomb motion of the electrons along the field direction on their motion in the plane perpendicular to the field, an effect which cannot be captured by the adiabatic approximation. The new code allows for the inclusion of up to 8 Landau levels. This reduces the relative error of energy values as compared to the adiabatic approximation results by typically a factor of three (1/3 of the original error), and yields accurate results also in regions of lower neutron star magnetic field strengths where the adiabatic approximation fails. Further improvements in the code are a more sophisticated choice of the initial wave functions, which takes into

  16. Cross-Calibrating Sunspot Magnetic Field Strength Measurements from the McMath-Pierce Solar Telescope and the Dunn Solar Telescope

    NASA Astrophysics Data System (ADS)

    Watson, Fraser T.; Beck, Christian; Penn, Matthew J.; Tritschler, Alexandra; Pillet, Valentín Martinez; Livingston, William C.

    2015-11-01

    In this article we describe a recent effort to cross-calibrate data from an infrared detector at the McMath-Pierce Solar Telescope and the Facility InfraRed Spectropolarimeter (FIRS) at the Dunn Solar Telescope. A synoptic observation program at the McMath-Pierce has measured umbral magnetic field strengths since 1998, and this data set has recently been compared with umbral magnetic field observations from SOHO/MDI and SDO/HMI. To further improve on the data from McMath-Pierce, we compared the data with measurements taken at the Dunn Solar Telescope with far greater spectral resolution than has been possible with space instrumentation. To minimise potential disruption to the study, concurrent umbral measurements were made so that the relationship between the two datasets can be most accurately characterised. We find that there is a strong agreement between the umbral magnetic field strengths recorded by each instrument, and we reduced the FIRS data in two different ways to successfully test this correlation further.

  17. Multi-site Study of Diffusion Metric Variability: Characterizing the Effects of Site, Vendor, Field Strength, and Echo Time using the Histogram Distance

    PubMed Central

    Helmer, K. G.; Chou, M-C.; Preciado, R. I.; Gimi, B.; Rollins, N. K.; Song, A.; Turner, J.; Mori, S.

    2016-01-01

    MRI-based multi-site trials now routinely include some form of diffusion-weighted imaging (DWI) in their protocol. These studies can include data originating from scanners built by different vendors, each with their own set of unique protocol restrictions, including restrictions on the number of available gradient directions, whether an externally-generated list of gradient directions can be used, and restrictions on the echo time (TE). One challenge of multi-site studies is to create a common imaging protocol that will result in a reliable and accurate set of diffusion metrics. The present study describes the effect of site, scanner vendor, field strength, and TE on two common metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA). We have shown in earlier work that ROI metrics and the mean of MD and FA histograms are not sufficiently sensitive for use in site characterization. Here we use the distance between whole brain histograms of FA and MD to investigate within- and between-site effects. We concluded that the variability of DTI metrics due to site, vendor, field strength, and echo time could influence the results in multi-center trials and that histogram distance is sensitive metrics for each of these variables. PMID:27350723

  18. ION KINETIC ENERGY CONSERVATION AND MAGNETIC FIELD STRENGTH CONSTANCY IN MULTI-FLUID SOLAR WIND ALFVÉNIC TURBULENCE

    SciTech Connect

    Matteini, L.; Horbury, T. S.; Schwartz, S. J.; Pantellini, F.; Velli, M.

    2015-03-20

    We investigate the properties of plasma fluid motion in the large-amplitude, low-frequency fluctuations of highly Alfvénic fast solar wind. We show that protons locally conserve total kinetic energy when observed from an effective frame of reference comoving with the fluctuations. For typical properties of the fast wind, this frame can be reasonably identified by alpha particles which, due to their drift with respect to protons at about the Alfvén speed along the magnetic field, do not partake in the fluid low-frequency fluctuations. Using their velocity to transform the proton velocity into the frame of Alfvénic turbulence, we demonstrate that the resulting plasma motion is characterized by a constant absolute value of the velocity, zero electric fields, and aligned velocity and magnetic field vectors as expected for unidirectional Alfvénic fluctuations in equilibrium. We propose that this constraint, via the correlation between velocity and magnetic field in Alfvénic turbulence, is the origin of the observed constancy of the magnetic field; while the constant velocity corresponding to constant energy can only be observed in the frame of the fluctuations, the corresponding constant total magnetic field, invariant for Galilean transformations, remains the observational signature in the spacecraft frame of the constant total energy in the Alfvén turbulence frame.

  19. A Robust Method to Predict the Near-Sun and Interplanetary Magnetic Field Strength of Coronal Mass Ejections: Parametric and Case Studies

    NASA Astrophysics Data System (ADS)

    Patsourakos, Spiros; Georgoulis, Manolis K.

    2016-07-01

    Predicting the near-Sun, and particularly the Interplanetary (IP), magnetic field structure of Coronal Mass Ejections (CMEs) and interplanetary counterparts (ICMEs) is a topic of intense research activity. This is because Earth-directed CMEs with strong southward magnetic fields are responsible for the most powerful geomagnetic storms. We have recently developed a simple two-tier method to predict the magnetic field strength of CMEs in the outer corona and in the IP medium, using as input the magnetic-helicity budget of the source solar active region and stereoscopic coronagraphic observations. Near-Sun CME magnetic fields are obtained by utilizing the principle of magnetic helicity conservation of flux-rope CMEs for coronagraphic observations. Interplanetary propagation of the inferred values is achieved by employing power-law prescriptions of the radial evolution of the CME-ICME magnetic fields. We hereby present a parametric study of our method, based on the observed statistics of input parameters, to infer the anticipated range of values for the near-Sun and interplanetary CME-ICME magnetic fields. This analysis is complemented by application of our method to several well-observed major CME-ICME events.

  20. Fast quantifying collision strength index of ethylene-vinyl acetate copolymer coverings on the fields based on near infrared hyperspectral imaging techniques

    PubMed Central

    Chen, Y. M.; Lin, P.; He, Y.; He, J. Q.; Zhang, J.; Li, X. L.

    2016-01-01

    A novel strategy based on the near infrared hyperspectral imaging techniques and chemometrics were explored for fast quantifying the collision strength index of ethylene-vinyl acetate copolymer (EVAC) coverings on the fields. The reflectance spectral data of EVAC coverings was obtained by using the near infrared hyperspectral meter. The collision analysis equipment was employed to measure the collision intensity of EVAC materials. The preprocessing algorithms were firstly performed before the calibration. The algorithms of random frog and successive projection (SP) were applied to extracting the fingerprint wavebands. A correlation model between the significant spectral curves which reflected the cross-linking attributions of the inner organic molecules and the degree of collision strength was set up by taking advantage of the support vector machine regression (SVMR) approach. The SP-SVMR model attained the residual predictive deviation of 3.074, the square of percentage of correlation coefficient of 93.48% and 93.05% and the root mean square error of 1.963 and 2.091 for the calibration and validation sets, respectively, which exhibited the best forecast performance. The results indicated that the approaches of integrating the near infrared hyperspectral imaging techniques with the chemometrics could be utilized to rapidly determine the degree of collision strength of EVAC. PMID:26875544

  1. Fast quantifying collision strength index of ethylene-vinyl acetate copolymer coverings on the fields based on near infrared hyperspectral imaging techniques.

    PubMed

    Chen, Y M; Lin, P; He, Y; He, J Q; Zhang, J; Li, X L

    2016-02-15

    A novel strategy based on the near infrared hyperspectral imaging techniques and chemometrics were explored for fast quantifying the collision strength index of ethylene-vinyl acetate copolymer (EVAC) coverings on the fields. The reflectance spectral data of EVAC coverings was obtained by using the near infrared hyperspectral meter. The collision analysis equipment was employed to measure the collision intensity of EVAC materials. The preprocessing algorithms were firstly performed before the calibration. The algorithms of random frog and successive projection (SP) were applied to extracting the fingerprint wavebands. A correlation model between the significant spectral curves which reflected the cross-linking attributions of the inner organic molecules and the degree of collision strength was set up by taking advantage of the support vector machine regression (SVMR) approach. The SP-SVMR model attained the residual predictive deviation of 3.074, the square of percentage of correlation coefficient of 93.48% and 93.05% and the root mean square error of 1.963 and 2.091 for the calibration and validation sets, respectively, which exhibited the best forecast performance. The results indicated that the approaches of integrating the near infrared hyperspectral imaging techniques with the chemometrics could be utilized to rapidly determine the degree of collision strength of EVAC.

  2. Fast quantifying collision strength index of ethylene-vinyl acetate copolymer coverings on the fields based on near infrared hyperspectral imaging techniques

    NASA Astrophysics Data System (ADS)

    Chen, Y. M.; Lin, P.; He, Y.; He, J. Q.; Zhang, J.; Li, X. L.

    2016-02-01

    A novel strategy based on the near infrared hyperspectral imaging techniques and chemometrics were explored for fast quantifying the collision strength index of ethylene-vinyl acetate copolymer (EVAC) coverings on the fields. The reflectance spectral data of EVAC coverings was obtained by using the near infrared hyperspectral meter. The collision analysis equipment was employed to measure the collision intensity of EVAC materials. The preprocessing algorithms were firstly performed before the calibration. The algorithms of random frog and successive projection (SP) were applied to extracting the fingerprint wavebands. A correlation model between the significant spectral curves which reflected the cross-linking attributions of the inner organic molecules and the degree of collision strength was set up by taking advantage of the support vector machine regression (SVMR) approach. The SP-SVMR model attained the residual predictive deviation of 3.074, the square of percentage of correlation coefficient of 93.48% and 93.05% and the root mean square error of 1.963 and 2.091 for the calibration and validation sets, respectively, which exhibited the best forecast performance. The results indicated that the approaches of integrating the near infrared hyperspectral imaging techniques with the chemometrics could be utilized to rapidly determine the degree of collision strength of EVAC.

  3. Performance of a static-anode/flat-panel x-ray fluoroscopy system in a diagnostic strength magnetic field: a truly hybrid x-ray/MR imaging system.

    PubMed

    Fahrig, R; Wen, Z; Ganguly, A; DeCrescenzo, G; Rowlands, J A; Stevens, G M; Saunders, R F; Pelc, N J

    2005-06-01

    Minimally invasive procedures are increasing in variety and frequency, facilitated by advances in imaging technology. Our hybrid imaging system (GE Apollo flat panel, custom Brand x-ray static anode x-ray tube, GE Lunar high-frequency power supply and 0.5 T Signa SP) provides both x-ray and MR imaging capability to guide complex procedures without requiring motion of the patient between two distant gantries. The performance of the x-ray tube in this closely integrated system was evaluated by modeling and measuring both the response of the filament to an externally applied field and the behavior of the electron beam for field strengths and geometries of interest. The performance of the detector was assessed by measuring the slanted-edge modulation transfer function (MTF) and when placed at zero field and at 0.5 T. Measured resonant frequencies of filaments can be approximated using a modified vibrating beam model, and were at frequencies well below the 25 kHz frequency of our generator for our filament geometry. The amplitude of vibration was not sufficient to cause shorting of the filament during operation within the magnetic field. A simple model of electrons in uniform electric and magnetic fields can be used to estimate the deflection of the electron beam on the anode for the fields of interest between 0.2 and 0.5 T. The MTF measured at the detector and the DQE showed no significant difference inside and outside of the magnetic field. With the proper modifications, an x-ray system can be fully integrated with a MR system, with minimal loss of image quality. Any x-ray tube can be assessed for compatibility when placed at a particular location within the field using the models. We have also concluded that a-Si electronics are robust against magnetic fields. Detailed knowledge of the x-ray system installation is required to provide estimates of system operation.

  4. SV40 late protein VP4 forms toroidal pores to disrupt membranes for viral release

    PubMed Central

    Raghava, Smita; Giorda, Kristina M.; Romano, Fabian B.; Heuck, Alejandro P.; Hebert, Daniel N.

    2014-01-01

    Nonenveloped viruses are generally released from the cell by the timely lysis of host cell membranes. SV40 has been used as a model virus for the study of the lytic nonenveloped virus life cycle. The expression of SV40 VP4 at later times during infection is concomitant with cell lysis. To investigate the role of VP4 in viral release and its mechanism of action, VP4 was expressed and purified from bacteria as a fusion protein for use in membrane disruption assays. Purified VP4 perforated membranes as demonstrated by the release of fluorescent markers encapsulated within large unilamellar vesicles or liposomes. Dynamic light scattering results found that VP4 treatment did not cause membrane lysis or change the size of the liposomes. Liposomes encapsulated with bodipy-labeled streptavidin were used to show that VP4 formed stable pores in membranes. These VP4 pores had an inner diameter of between 1 and 5 nm. Asymmetrical liposomes containing pyrene-labeled lipids in the outer monolayer were employed to monitor transbilayer lipid diffusion. Consistent with VP4 forming toroidal pore structures in membranes, VP4 induced transbilayer lipid diffusion or lipid flip-flop. Altogether, these studies support a central role for VP4 acting as a viroporin in the disruption of cellular membranes to trigger SV40 viral release by forming toroidal pores that unite the outer and inner leaflets of membrane bilayers. PMID:23651212

  5. The Effect of Shock Stress and Field Strength on Shock-Induced Depoling of Normally Poled PZT 95/5

    SciTech Connect

    CHHABILDAS,LALIT C.; FURNISH,MICHAEL D.; MONTGOMERY,STEPHEN T.; SETCHELL,ROBERT E.

    1999-09-01

    Shock-induced depoling of the ferroelectric ceramic PZT 95/5 is utilized in a number of pulsed power devices. Several experimental and theoretical efforts are in progress in order to improve numerical simulations of these devices. In this study we have examined the shock response of normally poled PZT 95/5 under uniaxial strain conditions. On each experiment the current produced in an external circuit and the transmitted waveform at a window interface were recorded. The peak electrical field generated within the PZT sample was varied through the choice of external circuit resistance. Shock pressures were varied from 0.6 to 4.6 GPa, and peak electrical fields were varied from 0.2 to 37 kV/cm. For a 2.4 GPa shock and the lowest peak field, a nearly constant current governed simply by the remanent polarization and the shock velocity was recorded. Both decreasing the shock pressure and increasing the electrical field resulted in reduced current generation, indicating a retardation of the depoling kinetics.

  6. The Correlation Between Electron Density and Temperature in Low and High Strength Crustal Magnetic Field Regions at Mars

    NASA Astrophysics Data System (ADS)

    Chamandy, T.; Andersson, L.; Fowler, C. M.; Ergun, R.; Connerney, J. E. P.; Brain, D. A.

    2015-12-01

    The Langmuir Probe and Waves Instrument (LPW) onboard the MAVEN spacecraft is the first Langmuir probe to map out the upper atmosphere of Mars. The instrument provides measurements (amongst other variables) of electron density (Ne) and temperature (Te). The overarching scientific goal of MAVEN is to determining how Mars lost its atmosphere and to understand the physical processes governing this escape and the above quantities play a crucial role in understanding this. Ne and Te information is critical for determining the efficiency of the different photochemical reaction rates and thereby in understanding the upper atmospheric composition. Understanding the upper atmosphere allows the MAVEN mission to calculate escape rates. Photochemical reactions and collisions dominate below the exobase region (~150-~180 km). Above the exobase, particles with energies greater than the Mars gravity well can escape. On the dayside solar EUV heats the atmosphere at lower altitudes and produces the ionosphere. It is of great interest to understand the how the electron density and temperature correlate. The presented study therefore shows the correlation between Ne and Te. This study investigates how different solar zenith angles affect these quantities and evaluates if closed magnetic field lines (as expected to occur over crustal magnetic fields) change the correlation between the two. Many previous studies have shown that crustal fields affect the plasma at high altitudes. In this study we present how the magnetic field influences the photochemical and the plasma processes close to the exobase via analyzing Ne and Te.

  7. On the Contribution of Curl-Free Current Patterns to the Ultimate Intrinsic Signal-to-Noise Ratio at Ultra-High Field Strength.

    PubMed

    Pfrommer, Andreas; Henning, Anke

    2017-02-10

    The ultimate intrinsic signal-to-noise ratio (SNR) is a coil independent performance measure to compare different receive coil designs. To evaluate this benchmark in a sample, a complete electromagnetic basis set is required. The basis set can be obtained by curl-free and divergence-free surface current distributions, which excite linearly independent solutions to Maxwell's equations. In this work, we quantitatively investigate the contribution of curl-free current patterns to the ultimate intrinsic SNR in a spherical head-sized model at 9.4 T. Therefore, we compare the ultimate intrinsic SNR obtained with having only curl-free or divergence-free current patterns, with the ultimate intrinsic SNR obtained from a combination of curl-free and divergence-free current patterns. The influence of parallel imaging is studied for various acceleration factors. Moreover results for different field strengths (1.5 T up to 11.7 T) are presented at specific voxel positions and acceleration factors. The full-wave electromagnetic problem is analytically solved using dyadic Green's functions. We show, that at ultra-high field strength (B0 ⩾7T) a combination of curl-free and divergence-free current patterns is required to achieve the best possible SNR at any position in a spherical head-sized model. On 1.5- and 3T platforms, divergence-free current patterns are sufficient to cover more than 90% of the ultimate intrinsic SNR.

  8. Quantum wells on 3C-SiC/NH-SiC heterojunctions. Calculation of spontaneous polarization and electric field strength in experiments

    SciTech Connect

    Sbruev, I. S.; Sbruev, S. B.

    2010-10-15

    The results of experiments with quantum wells on 3C-SiC/4H-SiC and 3C-SiC/6H-SiC heterojunctions obtained by various methods are reconsidered. Spontaneous polarizations, field strengths, and energies of local levels in quantum wells on 3C-SiC/NH-SiC heterojunctions were calculated within a unified model. The values obtained are in agreement with the results of all considered experiments. Heterojunction types are determined. Approximations for valence band offsets on heterojunctions between silicon carbide polytypes and the expression for calculating local levels in quantum wells on the 3C-SiC/NH-SiC heterojunction are presented. The spontaneous polarizations and field strengths induced by spontaneous polarization on 3C-SiC/4H-SiC and 3C-SiC/6H-SiC heterojunctions were calculated as 0.71 and 0.47 C/m{sup 2} and 0.825 and 0.55 MV/cm, respectively.

  9. In-situ investigation of the influence of the long-term shear strength of faults on the regional stress field in a granite rock mass

    NASA Astrophysics Data System (ADS)

    Figueiredo, Bruno; Cornet, Francois; Lamas, Luís; Muralha, José

    2016-04-01

    A case study is presented to show how stress field measurements may be used to assess the long-term rheological behaviour of an equivalent geo-material. The example concerns a granitic rock mass at the km3 scale, where an underground hydropower scheme including a new 10 km long power conduit and a powerhouse complex will be constructed. For design of the underground cavern and hydraulic pressure tunnel, several in situ stress measurements were carried out, using hydraulic borehole testing, overcoring and flat jack techniques. A first continuum mechanics model, with a homogenous material, was developed to integrate the several in situ test results and to assess the regional stress field. This model is based on elasticity and relaxation of the elastic properties measured through laboratory tests conducted on cores. Results of integration show that the long-term behavior of this granite rock mass differs markedly from the short-term behaviour as defined by laboratory tests. This suggests that the in-situ stress field depends mostly on the softer material that fills up the faults and hence results from the shear stress relaxation over a large number of pre-existing fractures and faults. A second continuum mechanics model, with consideration of two fault planes located nearby the hydraulic tests, was studied. This model is based on elasticity for the overall rock mass, with the elastic properties extracted from laboratory measurements, and visco-elasticity with small long-term shear strength for the two fault planes. Results show that the overall granite rock mass may be viewed as a combination of stiff elastic blocks separated by soft low strength material, leading to a fairly large scale homogeneous axisymmetrical stress field with vertical axis. Advantages and limitations of the two modelling approaches are discussed.

  10. Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

    PubMed Central

    Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

    2000-01-01

    An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of <60 V/cm. Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

  11. Instability of thermoremanence and the problem of estimating the ancient geomagnetic field strength from non-single-domain recorders

    PubMed Central

    Shaar, Ron; Tauxe, Lisa

    2015-01-01

    Data on the past intensity of Earth’s magnetic field (paleointensity) are essential for understanding Earth’s deep interior, climatic modeling, and geochronology applications, among other items. Here we demonstrate the possibility that much of available paleointensity data could be biased by instability of thermoremanent magnetization (TRM) associated with non-single-domain (SD) particles. Paleointensity data are derived from experiments in which an ancient TRM, acquired in an unknown field, is replaced by a laboratory-controlled TRM. This procedure is built on the assumption that the process of ancient TRM acquisition is entirely reproducible in the laboratory. Here we show experimental results violating this assumption in a manner not expected from standard theory. We show that the demagnetization−remagnetization relationship of non-SD specimens that were kept in a controlled field for only 2 y show a small but systematic bias relative to sister specimens that were given a fresh TRM. This effect, likely caused by irreversible changes in micromagnetic structures, leads to a bias in paleointensity estimates. PMID:26305946

  12. Electric field strength and focality in electroconvulsive therapy and magnetic seizure therapy: a finite element simulation study

    NASA Astrophysics Data System (ADS)

    Deng, Zhi-De; Lisanby, Sarah H.; Peterchev, Angel V.

    2011-02-01

    We present the first computational study comparing the electric field induced by various electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) paradigms. Four ECT electrode configurations (bilateral, bifrontal, right unilateral, and focal electrically administered seizure therapy) and three MST coil configurations (circular, cap, and double cone) were modeled. The model incorporated a modality-specific neural activation threshold. ECT (0.3 ms pulse width) and MST induced the maximum electric field of 2.1-2.5 V cm-1 and 1.1-2.2 V cm-1 in the brain, corresponding to 6.2-7.2 times and 1.2-2.3 times the neural activation threshold, respectively. The MST electric field is more confined to the superficial cortex compared to ECT. The brain volume stimulated was much larger with ECT (up to 100%) than with MST (up to 8.2%). MST with the double-cone coil was the most focal, and bilateral ECT was the least focal. Our results suggest a possible biophysical explanation of the reduced side effects of MST compared to ECT. Our results also indicate that the conventional ECT pulse amplitude (800-900 mA) is much higher than necessary for seizure induction. Reducing the ECT pulse amplitude should be explored as a potential means of diminishing side effects.

  13. Systematic study of low-lying E1 strength using the time-dependent mean field theory

    SciTech Connect

    Ebata, S.; Nakatsukasa, T.; Inakura, T.

    2012-11-12

    We carry out systematic investigation of electric dipole (E1) mode from light to heavy nuclei, using a new time-dependent mean field theory: the Canonical-basis Time-Dependent Hartree-Fock-Bogoliubov (Cb-TDHFB) theory. The Cb-TDHFB in the three-dimensional coordinate space representation can deal with pairing correlation and any kind of deformation in the timedependent framework. We report the neutron-number dependence of the low-energy E1 mode for light (A > 40) and heavy isotopes (A < 100) around N= 82.

  14. A highly optimized code for calculating atomic data at neutron star magnetic field strengths using a doubly self-consistent Hartree-Fock-Roothaan method

    NASA Astrophysics Data System (ADS)

    Schimeczek, C.; Engel, D.; Wunner, G.

    2014-05-01

    Our previously published code for calculating energies and bound-bound transitions of medium- Z elements at neutron star magnetic field strengths [D. Engel, M. Klews, G. Wunner, Comp. Phys. Comm. 180, 3-2-311 (2009)] was based on the adiabatic approximation. It assumes a complete decoupling of the (fast) gyration of the electrons under the action of the magnetic field and the (slow) bound motion along the field under the action of the Coulomb forces. For the single-particle orbitals this implied that each is a product of a Landau state and an (unknown) longitudinal wave function whose B-spline coefficients were determined self-consistently by solving the Hartree-Fock equations for the many-electron problem on a finite-element grid. In the present code we go beyond the adiabatic approximation, by allowing the transverse part of each orbital to be a superposition of Landau states, while assuming that the longitudinal part can be approximated by the same wave function in each Landau level. Inserting this ansatz into the energy variational principle leads to a system of coupled equations in which the B-spline coefficients depend on the weights of the individual Landau states, and vice versa, and which therefore has to be solved in a doubly self-consistent manner. The extended ansatz takes into account the back-reaction of the Coulomb motion of the electrons along the field direction on their motion in the plane perpendicular to the field, an effect which cannot be captured by the adiabatic approximation. The new code allows for the inclusion of up to 8 Landau levels. This reduces the relative error of energy values as compared to the adiabatic approximation results by typically a factor of three (1/3 of the original error) and yields accurate results also in regions of lower neutron star magnetic field strengths where the adiabatic approximation fails. Further improvements in the code are a more sophisticated choice of the initial wave functions, which takes into

  15. Interpretation of second solar spectrum observations of the Sr I 4607 Å line in a quiet region: Turbulent magnetic field strength determination

    NASA Astrophysics Data System (ADS)

    Bommier, V.; Derouich, M.; Landi Degl'Innocenti, E.; Molodij, G.; Sahal-Bréchot, S.

    2005-03-01

    This paper presents and interprets some observations of the limb polarization of Sr I 4607 Å obtained with the spectropolarimeter of the French-Italian telescope THEMIS in quiet regions close to the solar North Pole on 2002 December 7-9. The linear polarization was measured for a series of limb distances ranging from 4 to 160 arcsec, corresponding to heights of optical depth unity in the line core ranging from about 330 to 220 km, respectively, above the τ5000=1 level. To increase the polarimetric sensitivity, the data were averaged along the spectrograph slit (one arcmin long) set parallel to the solar limb. Since the data show no rotation of the linear polarization direction with respect to the limb direction, the observed depolarization is ascribed to the Hanle effect of a turbulent weak magnetic field, the zero-field polarization being derived from a model. The interpretation is performed by means of an algorithm which describes the process of line formation in terms of the atomic density matrix formalism, the solar atmosphere being described by an empirical, plane-parallel model. The collisional rates entering the model (inelastic collisions with electrons, elastic depolarizing collisions with neutral hydrogen), have been computed by applying fast semi-classical methods having a typical accuracy of the order of 20% or better (see Derouich [CITE]), leading to 6% inaccuracy on the magnetic field strength determination. We assume a unimodal distribution for the intensity of the turbulent field. The computed intensity profile has been adjusted to the observed one in both depth and width, by varying both microturbulent and macroturbulent velocities. The best adjustment is obtained for respectively 1.87 km s-1 (micro) and 1.78 km s-1 (macro). The evaluation of the magnetic depolarization leads then to the average value of 46 Gauss for the turbulent magnetic field strength, with a gradient of -0.12 Gauss/km. Our results are in very good agreement with the value of

  16. Strength Testing.

    ERIC Educational Resources Information Center

    Londeree, Ben R.

    1981-01-01

    Postural deviations resulting from strength and flexibility imbalances include swayback, scoliosis, and rounded shoulders. Screening tests are one method for identifying strength problems. Tests for the evaluation of postural problems are described, and exercises are presented for the strengthening of muscles. (JN)

  17. The Influence of Electron Temperature and Magnetic Field Strength on Cosmic-Ray Injection in High Mach Number Shocks

    NASA Astrophysics Data System (ADS)

    Schmitz, H.; Chapman, S. C.; Dendy, R. O.

    2002-05-01

    Electron preacceleration from thermal to mildly relativistic energies in high Mach number shocks (the injection problem) is an outstanding issue in understanding synchrotron radiation from supernova remnants. At high Alfvénic Mach numbers, collisionless perpendicular shocks reflect a fraction of the upstream ions. This gives rise to two-stream instabilities, which in turn can accelerate ions. However, in astrophysical plasmas, the value of β-the ratio of kinetic pressure to magnetic pressure-is not well known. We have used a particle in cell simulation code to investigate the influence of β on the shock structure and on the electron acceleration (assuming thermodynamic equilibrium in the undisturbed plasma, β=βi=βe). Previous simulations at low values of β showed that the phase space distributions of electrons and ions became highly structured: characteristic holes appear in the electron phase space, and the shock dynamics exhibit reformation processes. However, we find that all these features disappear at higher β due to the high initial thermal velocity of the electrons. It follows that the electron cosmic-ray injection mechanism depends strongly on β, that is, on the electron temperature normalized to the magnetic field upstream.

  18. SU-E-T-590: Optimizing Magnetic Field Strengths with Matlab for An Ion-Optic System in Particle Therapy Consisting of Two Quadrupole Magnets for Subsequent Simulations with the Monte-Carlo Code FLUKA

    SciTech Connect

    Baumann, K; Weber, U; Simeonov, Y; Zink, K

    2015-06-15

    Purpose: Aim of this study was to optimize the magnetic field strengths of two quadrupole magnets in a particle therapy facility in order to obtain a beam quality suitable for spot beam scanning. Methods: The particle transport through an ion-optic system of a particle therapy facility consisting of the beam tube, two quadrupole magnets and a beam monitor system was calculated with the help of Matlab by using matrices that solve the equation of motion of a charged particle in a magnetic field and field-free region, respectively. The magnetic field strengths were optimized in order to obtain a circular and thin beam spot at the iso-center of the therapy facility. These optimized field strengths were subsequently transferred to the Monte-Carlo code FLUKA and the transport of 80 MeV/u C12-ions through this ion-optic system was calculated by using a user-routine to implement magnetic fields. The fluence along the beam-axis and at the iso-center was evaluated. Results: The magnetic field strengths could be optimized by using Matlab and transferred to the Monte-Carlo code FLUKA. The implementation via a user-routine was successful. Analyzing the fluence-pattern along the beam-axis the characteristic focusing and de-focusing effects of the quadrupole magnets could be reproduced. Furthermore the beam spot at the iso-center was circular and significantly thinner compared to an unfocused beam. Conclusion: In this study a Matlab tool was developed to optimize magnetic field strengths for an ion-optic system consisting of two quadrupole magnets as part of a particle therapy facility. These magnetic field strengths could subsequently be transferred to and implemented in the Monte-Carlo code FLUKA to simulate the particle transport through this optimized ion-optic system.

  19. Linear mode conversion of Langmuir/z-mode waves to radiation in plasmas with various magnetic field strength

    SciTech Connect

    Kim, Eun-Hwa; Johnson, Jay R.; Cairns, Iver H.

    2013-12-15

    Linear mode conversion of Langmuir/z waves to electromagnetic radiation near the plasma and upper hybrid frequency in the presence of density gradients is potentially relevant to type II and III solar radio bursts, ionospheric radar experiments, pulsars, and continuum radiation for planetary magnetospheres. Here, we study mode conversion in warm, magnetized plasmas using a numerical electron fluid simulation code when the density gradient has a wide range of angle, δ, to the ambient magnetic field, B{sub 0}, for a range of incident Langmuir/z wavevectors. Our results include: (1) Left-handed polarized ordinary (oL) and right-handed polarized extraordinary (xR) mode waves are produced in various ranges of δ for Ω{sub 0} = (ωL/c){sup 1/3}(ω{sub ce}/ω) < 1.5, where ω{sub ce} is the (angular) electron cyclotron frequency, ω is the angular wave frequency, L is the length scale of the (linear) density gradient, and c is the speed of light; (2) the xR mode is produced most strongly in the range, 40° < δ < 60°, for intermediately magnetized plasmas with Ω{sub 0} = 1.0 and 1.5, while it is produced over a wider range, 0° ≤ δ ≤ 90°, for weakly magnetized plasmas with Ω{sub 0} = 0.1 and 0.7; (3) the maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50%–99% and the corresponding energy conversion efficiencies are 5%–14% (depending on the adiabatic index γ and β = T{sub e}/m{sub e}c{sup 2}, where T{sub e} is the electron temperature and m{sub e} is the electron) for various Ω{sub 0}; (4) the mode conversion window becomes wider as Ω{sub 0} and δ increase. Hence, the results in this paper confirm that linear mode conversion under these conditions can explain the weak total circular polarization of interplanetary type II and III solar radio bursts because a strong xR mode can be generated via linear mode conversion near δ ∼ 45°.

  20. Constraining the Post-Shock Magnetic Field Strength of SN1006 from the Rotation Measure of Radio Galaxy ESO 328-13

    NASA Astrophysics Data System (ADS)

    Flewellen, Lilly; Dills, Sidney; Moffett, David A.

    2015-01-01

    could have a significant impact on estimates of the field strength, we are encouraged by this simple result.

  1. Strength Training

    MedlinePlus

    ... strengthens your heart and lungs. When you strength train with weights, you're using your muscles to ... see there are lots of different ways to train with weights. Try a few good basic routines ...

  2. How to determine the thermal electron density and the magnetic field strength from the Cluster/Whisper observations around the Earth

    NASA Astrophysics Data System (ADS)

    Trotignon, J. G.; Décréau, P. M. E.; Rauch, J. L.; Randriamboarison, O.; Krasnoselskikh, V.; Canu, P.; Alleyne, H.; Yearby, K.; Le Guirriec, E.; Séran, H. C.; Sené, F. X.; Martin, Ph.; Lévêque, M.; Fergeau, P.

    2001-10-01

    The Wave Experiment Consortium, WEC, is a highly integrated package of five instruments used to study the plasma environment around the Earth. One of these instruments, the Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation, Whisper, aims at the thermal electron density evaluation and natural wave monitoring in the 4-83 kHz frequency range. In its active working mode, which is our primarily concern here, the Whisper instrument transmits a short wave train at a swept frequency and receives echoes after a delay. Incidentally, it behaves like a classical ground-based ionosonde. Natural modes of oscillations may thus be excited in the surrounding medium. This means that with suitable interpretations, the Whisper sounding technique becomes a powerful tool for plasma diagnosis. By taking into account the characteristic frequencies of the magnetoplasmas encountered by the Cluster spacecraft, it is indeed possible to reliably and accurately determine the electron density and, to a lesser degree, the magnetic field strength from the Whisper electric field measurements. Due to the predominantly electrostatic nature of the waves that are excited, observations of resonances may also lead to information on the electron velocity distribution functions. The existence of a hot population may indeed be revealed and the hot to cold density ratio can be estimated.

  3. Utilizing Biopsychosocial and Strengths-Based Approaches Within the Field of Child Health: What We Know and Where We Can Grow

    PubMed Central

    Black, Jessica M.; Hoeft, Fumiko

    2015-01-01

    We continue to increase our understanding of the experiences and settings that contribute to positive developmental outcomes in childhood, and those that confer greater risk. Although the mechanisms by which the risk and protective factors affect developmental outcomes need to be further elucidated through research, converging findings from the field of child health (spanning both physical and mental health) indicate that a biopsychosocial approach is useful. Here, we examine the evidence that early experiences confer both risk and protective processes on biopsychosocial development in childhood, and touch on some implications for the life course. Although this interdisciplinary field of research has already garnered substantial attention, here we aim to highlight the opportunity to use a strengths-based approach with the biopsychosocial model, with particular focus on children who experience prolonged stress. We close with consideration for future directions with an emphasis on policy and practice in clinical and educational settings to improve well-being in these early stages of the life course. PMID:25732011

  4. Pulsed electromagnetic fields improve bone microstructure and strength in ovariectomized rats through a Wnt/Lrp5/β-catenin signaling-associated mechanism.

    PubMed

    Jing, Da; Li, Feijiang; Jiang, Maogang; Cai, Jing; Wu, Yan; Xie, Kangning; Wu, Xiaoming; Tang, Chi; Liu, Juan; Guo, Wei; Shen, Guanghao; Luo, Erping

    2013-01-01

    Growing evidence has demonstrated that pulsed electromagnetic field (PEMF), as an alternative noninvasive method, could promote remarkable in vivo and in vitro osteogenesis. However, the exact mechanism of PEMF on osteopenia/osteoporosis is still poorly understood, which further limits the extensive clinical application of PEMF. In the present study, the efficiency of PEMF on osteoporotic bone microarchitecture and bone quality together with its associated signaling pathway mechanisms was systematically investigated in ovariectomized (OVX) rats. Thirty rats were equally assigned to the Control, OVX and OVX+PEMF groups. The OVX+PEMF group was subjected to daily 8-hour PEMF exposure with 15 Hz, 2.4 mT (peak value). After 10 weeks, the OVX+PEMF group exhibited significantly improved bone mass and bone architecture, evidenced by increased BMD, Tb.N, Tb.Th and BV/TV, and suppressed Tb.Sp and SMI levels in the MicroCT analysis. Three-point bending test suggests that PEMF attenuated the biomechanical strength deterioration of the OVX rat femora, evidenced by increased maximum load and elastic modulus. RT-PCR analysis demonstrated that PEMF exposure significantly promoted the overall gene expressions of Wnt1, LRP5 and β-catenin in the canonical Wnt signaling, but did not exhibit obvious impact on either RANKL or RANK gene expressions. Together, our present findings highlight that PEMF attenuated OVX-induced deterioration of bone microarchitecture and strength in rats by promoting the activation of Wnt/LRP5/β-catenin signaling rather than by inhibiting RANKL-RANK signaling. This study enriches our basic knowledge to the osteogenetic activity of PEMF, and may lead to more efficient and scientific clinical application of PEMF in inhibiting osteopenia/osteoporosis.

  5. Fluid induced metamorphism and strength of the middle to lower continental crust - field and textural examples from Bergen Arcs, Western Norway

    NASA Astrophysics Data System (ADS)

    Austrheim, H.; Putnis, A.; Putnis, C. V.

    2011-12-01

    Fluids may change the rheology of the lithosphere both by changing the deformation mechanism of minerals and by inducing metamorphic reactions. In the present account the influence of fluid-induced metamorphic reactions on the mineralogical and structural evolution of a thickened continental crust is described from anorthositic granulites in the Lindås Nappe, Bergen Arcs, Norway, where the Grenvillian age (~930 My) granulites (T 800°C, P≤10kbar) are transformed to Caledonian age (~420My) eclogite (~650°C and ≤ 20kbar) and amphibolite facies assemblages. The anorthosite complex ranges in composition from pure anorthosite via gabbroic anorthosite to gabbro with lenses of peridotite and pyroxenites which allow us to study the mineral reactions and assess relative rock strength in a wide range of compositions. The complex is locally banded with up to meter thick garnet-pyroxene rich layers alternating with plagioclase rich layers. In other localities the granulite facies structure is defined by oriented disc-shaped corona textures in a plagioclase rich matrix. The eclogites (garnet, omphacite, amphibole, kyanite, white micas ± plagioclase) and amphibolites (plagioclase, hornblende, kyanite, and white micas) are formed along fluid pathways such as fractures and shear zones. Breccias, where rotated blocks of granulites are surrounded by anastamosing eclogite- and amphibolite facies shear zones, outcrop over areas of km2. Pseudotachylytes are developed in the granulites while the hydrated rocks in the shear zone respond by ductile deformation. A hierachy of rock strength can be inferred from these field observations. Notably the relict granulites form rotated angular blocks within the shear zones suggesting that granulites, independent of composition, are stronger than hydrous eclogitites and amphibolites. The garnet pyroxenite layer forms rigid blocks in eclogites suggesting that the mafic parts of the granulite complex must have been stronger than the

  6. T1 mapping of the myocardium: Intra-individual assessment of the effect of field strength, cardiac cycle and variation by myocardial region

    PubMed Central

    2012-01-01

    Background Myocardial T1 relaxation time (T1 time) and extracellular volume fraction (ECV) are altered in the presence of myocardial fibrosis. The purpose of this study was to evaluate acquisition factors that may result in variation of measured T1 time and ECV including magnetic field strength, cardiac phase and myocardial region. Methods 31 study subjects were enrolled and underwent one cardiovascular MR exam at 1.5 T and two exams at 3 T, each on separate days. A Modified Look-Locker Inversion Recovery (MOLLI) sequence was acquired before and 5, 10, 12, 20, 25 and 30 min after administration of 0.15 mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist) at 1.5 T (exam 1). For exam 2, MOLLI sequences were acquired at 3 T both during diastole and systole, before and after administration of Gd-DTPA (0.15 mmol/kg Magnevist).Exam 3 was identical to exam 2 except gadobenate dimeglumine was administered (Gd-BOPTA; 0.1 mmol/kg Multihance). T1 times were measured in myocardium and blood. ECV was calculated by (ΔR1myocardium/ΔR1blood)*(1-hematocrit). Results Before gadolinium, T1 times of myocardium and blood were significantly greater at 3 T versus 1.5 T (28% and 31% greater, respectively, p < 0.001); after gadolinium, 3 T values remained greater than those at 1.5 T (14% and 12% greater for myocardium and blood at 3 T with Gd-DTPA, respectively, p < 0.0001 and 18% and 15% greater at 3 T with Gd-BOPTA, respectively, p < 0.0001). However, ECV did not vary significantly with field strength when using the same contrast agent at equimolar dose (p = 0.2). Myocardial T1 time was 1% shorter at systole compared to diastole pre-contrast and 2% shorter at diastole compared to systole post-contrast (p < 0.01). ECV values were greater during diastole compared to systole on average by 0.01 (p < 0.01 to p < 0.0001). ECV was significantly higher for the septum compared to the non-septal myocardium for all three exams (p < 0

  7. Fracture strength and principal stress fields during crush testing of the SiC layer in TRISO-coated fuel particles

    NASA Astrophysics Data System (ADS)

    Davis, Brian C.; Ward, Logan; Butt, Darryl P.; Fillery, Brent; Reimanis, Ivar

    2016-08-01

    Diametrical compression testing is an important technique to evaluate fracture properties of the SiC layer in TRISO-coated nuclear fuel particles. This study was conducted to expand the understanding and improve the methodology of the test. An analytic solution and multiple FEA models are used to determine the development of the principal stress fields in the SiC shell during a crush test. An ideal fracture condition where the diametrical compression test best mimics in-service internal pressurization conditions was discovered. For a small set of empirical data points, results from different analysis methodologies were input to an iterative Weibull equation set to determine characteristic strength (332.9 MPa) and Weibull modulus (3.80). These results correlate well with published research. It is shown that SiC shell asphericity is currently the limiting factor of greatest concern to obtaining repeatable results. Improvements to the FEA are the only apparent method for incorporating asphericity and improving accuracy.

  8. ON THE NATURE OF THE FIRST TRANSIENT Z SOURCE XTE J1701-462: ITS ACCRETION DISK STRUCTURE, NEUTRON STAR MAGNETIC FIELD STRENGTH, AND HARD TAIL

    SciTech Connect

    Ding, G. Q.; Wang, N.; Yan, S. P.; Zhang, S. N.; Qu, J. L. E-mail: dinggq@gmail.com

    2011-08-15

    Using data from the Rossi X-Ray Timing Explorer, we investigate the spectral evolution along a 'Z' track and a '{nu}' track on the hardness-intensity diagrams of the first transient Z source XTE J1701-462. The spectral analyses suggest that the inner disk radius depends on the mass accretion rate, in agreement with the model prediction, R{sub in}{proportional_to}M-dot{sup 2/7}{sub disk}, for a radiation-pressure-dominated accretion disk interacting with the magnetosphere of a neutron star (NS). The changes in the disk mass accretion rate M-dot{sub disk} are responsible for the evolution of the 'Z' or '{nu}' track. Radiation pressure thickens the disk considerably and also produces significant outflows. The NS surface magnetic field strength, derived from the interaction between the magnetosphere and the radiation-pressure-dominated accretion disk, is {approx}(1-3) x 10{sup 9} G, which is possibly between normal atoll and Z sources. A significant hard tail is detected in the horizontal branches and we discuss several possible origins of the hard tail.

  9. Principles and Application of Magnetic Rubber Testing for Crack Detection in High-Strength Steel Components: II. Residual-Field Inspection

    DTIC Science & Technology

    2014-12-01

    DSTO Defence Science and Technology Organisation D6ac Denotes a grade of high strength steel FEM Finite element modelling (for calculating magnetic...UNCLASSIFIED UNCLASSIFIED Principles and Application of Magnetic Rubber Testing for Crack Detection in High-Strength Steel Components: II...ABSTRACT Since its introduction in the 1970s, magnetic rubber testing (MRT) has been used successfully to inspect critical high-strength steel

  10. WE-G-17A-08: Electron Gun Operation for in Line MRI-Linac Configurations: An Assessment of Beam Fidelity and Recovery Techniques for Different SIDs and Magnetic Field Strengths

    SciTech Connect

    Whelan, B; Keall, P; Constantin, D; Holloway, L; Kolling, S; Oborn, B; Fahrig, R

    2014-06-15

    Purpose: To test the functionality of medical electron guns within the fringe field of a purpose built superconducting MRI magnet, and to test different recovery techniques for a variety of imaging field strengths and SIDs. Methods: Three different electron guns were simulated using Finite Element Modelling; a standard diode gun, a standard triode gun, and a novel diode gun designed to operate within parallel magnetic fields. The approximate working regime of each gun was established by assessing exit current in constant magnetic fields of varying strength and defining ‘working’ as less than 10% change in injection current. Next, the 1.0T MRI magnet was simulated within Comsol Multiphysics. The coil currents in this model were also scaled to produce field strengths of .5, 1, 1.5 and 3T. Various magnetic shield configurations were simulated, varying the SID from 800 to 1300mm. The average magnetic field within the gun region was assessed together with the distortion in the imaging volume - greater than 150uT distortion was considered unacceptable. Results: The conventional guns functioned in fields of less than 7.5mT. Conversely, the redesigned diode required fields greater than .1T to function correctly. Magnetic shielding was feasible for SIDS of greater than 1000mm for field strengths of .5T and 1T, and 1100mm for 1.5 and 3.0T. Beyond these limits shielding resulted in unacceptable MRI distortion. In contrast, the redesigned diode could perform acceptably for SIDs of less than 812, 896, 931, and 974mm for imaging strengths of 0.5, 1.0, 1.5, 3.0T. Conclusions: For in-line MRIlinac configurations where the electron gun is operating in low field regions, shielding is a straight forward option. However, as magnetic field strength increases and the SID is reduced, shielding results in too great a distortion in the MRI and redesigning the electron optics is the preferable solution. The authors would like to acknowledge funding from the National Health and Research

  11. The alteration of metamict zircon and its role in the remobilization of high-field strength elements in the Georgeville granite, Nova Scotia

    SciTech Connect

    Anderson, A.J.; Wirth, R.; Thomas, R.

    2008-10-02

    The structure and composition of metamict zircon from the Georgeville epizonal A-type granite in the Antigonish Highlands, Nova Scotia, were determined using EMPA, SXRF, LA-ICP-MS, Raman microspectroscopy and TEM data. Individual crystals of zircon are variably altered and consist of four domains distinguished on the basis of texture and composition. Domain A consists of zircon and zirconium oxide nanocrystals in an amorphous matrix and is trace-element-enriched. Replacement of domain A in proximity to microfractures produced a porous and relatively trace-element-poor zircon (domain B) with disseminated Th-U- and Y-enriched inclusions (domain C). Domain D consists of amorphous zirconium silicate that is depleted in trace elements but enriched in Hf. It is found in fractures, together with minor amounts of thorite and thorianite. It Domain D is anhydrous and free of inclusions and pore spaces and has a composition similar to highly crystalline zircon. Micro- and nanoscale element-distribution maps indicate that high-field-strength trace elements in metamict zircon were redistributed during alteration by diffusion and by dissolution-and-reprecipitation processes near microfractures and other fluid channelways. The anomalous chondrite-normalized rare-earth-element patterns and Nd isotopic signature of the granite is attributed largely to the preferential transport and deposition of rare-earth elements during subsolidus re-equilibration of metamict zircon. Hydrothermally deposited zirconium silicate (domain D) has a composition similar to that of highly crystalline Hf-rich zircon but is completely amorphous. This observation emphasizes the need to verify the structural integrity and aqueous durability of hydrothermally deposited zircon before it is used to reconstruct hydrothermal processes.

  12. Changes in the effective gravitational field strength affect the state of phosphorylation of stress-related proteins in callus cultures of Arabidopsis thaliana

    PubMed Central

    Barjaktarović, Žarko; Schütz, Wolfgang; Madlung, Johannes; Fladerer, Claudia; Nordheim, Alfred; Hampp, Rüdiger

    2009-01-01

    In a recent study it was shown that callus cell cultures of Arabidopsis thaliana respond to changes in gravitational field strengths by changes in protein expression. Using ESI-MS/MS for proteins with differential abundance after separation by 2D-PAGE, 28 spots which changed reproducibly and significantly in amount (P <0.05) after 2 h of hypergravity (18 up-regulated, 10 down-regulated) could be identified. The corresponding proteins were largely involved in stress responses, including the detoxification of reactive oxygen species (ROS). In the present study, these investigations are extended to phosphorylated proteins. For this purpose, callus cell cultures of Arabidopsis thaliana were exposed to hypergravity (8 g) and simulated weightlessness (random positioning; RP) for up to 30 min, a period of time which yielded the most reliable data. The first changes, however, were visible as early as 10 min after the start of treatment. In comparison to 1 g controls, exposure to hypergravity resulted in 18 protein spots, and random positioning in 25, respectively, with increased/decreased signal intensity by at least 2-fold (P <0.05). Only one spot (alanine aminotransferase) responded the same way under both treatments. After 30 min of RP, four spots appeared, which could not be detected in control samples. Among the protein spots altered in phosphorylation, it was possible to identify 24 from those responding to random positioning and 12 which responded to 8 g. These 12 proteins (8 g) are partly (5 out of 12) the same as those changed in expression after exposure to 2 h of hypergravity. The respective proteins are involved in scavenging and detoxification of ROS (32%), primary metabolism (20.5%), general signalling (14.7%), protein translation and proteolysis (14.7%), and ion homeostasis (8.8%). Together with our recent data on protein expression, it is assumed that changes in gravitational fields induce the production of ROS. Our data further indicate that responses

  13. Mechanical loading with or without weight-bearing activity: influence on bone strength index in elite female adolescent athletes engaged in water polo, gymnastics, and track-and-field.

    PubMed

    Greene, David A; Naughton, Geraldine A; Bradshaw, Elizabeth; Moresi, Mark; Ducher, Gaele

    2012-09-01

    Bone health is considered not to benefit from water-based sports because of their weight-supported nature, but available evidence primarily relies on DXA technology. Our purpose was to investigate musculoskeletal health in the upper and lower body in well-trained adolescent female athletes using pQCT and compare these athletes with less-active, age- and sex-matched peers. Bone mineral content, volumetric cortical and trabecular BMD, total and cortical area, and bone strength index were assessed at the distal and proximal tibia and radius in four groups of adolescent females (mean age, 14.9 years) including water polo players (n = 30), gymnasts (n = 25), track-and-field athletes (n = 34), and nonactive controls (n = 28). Water polo players did not show any benefit in bone strength index or muscle size in the lower leg when compared with controls. In contrast, gymnasts showed 60.1 % and 53.4 % greater bone strength index at the distal and proximal tibia, respectively, than nonactive females (p < 0.05). Similarly, track-and-field athletes displayed 33.9 % and 14.7 % greater bone strength index at the distal and proximal tibia, respectively, compared with controls (p < 0.05). In the upper body, water polo players had 31.9 % greater bone strength index at the distal radius, but not the radial shaft, and 15.2 % larger forearm muscle cross-sectional area than controls (p < 0.05). The greatest musculoskeletal benefits in the upper body were found in gymnasts. In conclusion, despite training at an elite level, female water polo players did not show any benefits in musculoskeletal health in the lower leg and only limited benefits in the upper body when compared with nonactive girls.

  14. Oxidative mobilization of cerium and uranium and enhanced release of "immobile" high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Kraemer, Dennis; Kopf, Sebastian; Bau, Michael

    2015-09-01

    Polyvalent trace elements such as the high field strength elements (HFSE) are commonly considered rather immobile during low-temperature water-rock interaction. Hence, they have become diagnostic tools that are widely applied in geochemical studies. We present results of batch leaching experiments focused on the mobilization of certain HFSE (Y, Zr, Hf, Th, U and rare earth elements) from mafic, intermediate and felsic igneous rocks in the presence and absence, respectively, of the siderophore desferrioxamine B (DFOB). Our data show that DFOB strongly enhances the mobility of these trace elements during low-temperature water-rock interaction. The presence of DFOB produces two distinct features in the Rare Earths and Yttrium (REY) patterns of leaching solutions, regardless of the mineralogical and chemical composition or the texture of the rock type studied. Bulk rock-normalized REY patterns of leaching solutions with DFOB show (i) a very distinct positive Ce anomaly and (ii) depletion of La and other light REY relative to the middle REY, with a concave downward pattern between La and Sm. These features are not observed in experiments with hydrochloric acid, acetic acid or deionized water. In DFOB-bearing leaching solutions Ce and U are decoupled from and selectively enriched relative to light REY and Th, respectively, due to oxidation to Ce(IV) and U(VI). Oxidation of Ce3+ and U4+ is promoted by the significantly higher stability of the Ce(IV) and U(VI) DFOB complexes as compared to the Ce(III) and U(IV) DFOB complexes. This is similar to the relationship between the Ce(IV)- and Ce(III)-pentacarbonate complexes that cause positive Ce anomalies in alkaline lakes. However, while formation of Ce(IV) carbonate complexes is confined to alkaline environments, Ce(IV) DFOB complexes may produce positive Ce anomalies even in mildly acidic and near-neutral natural waters. Siderophore-promoted dissolution processes also significantly enhance mobility of other 'immobile' HFSE

  15. Character Strengths and Intellectual and Developmental Disability: A Strengths-Based Approach from Positive Psychology

    ERIC Educational Resources Information Center

    Niemiec, Ryan M.; Shogren, Karrie A.; Wehmeyer, Michael L.

    2017-01-01

    There has been limited focus in the disability field on assessing and intervening to promote strengths of character. However, character strengths have received significant attention in the broader field of positive psychology. This paper provides an overview of the growing science of character strengths and explores why and how character strengths…

  16. 47 CFR 27.55 - Power strength limits.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Power strength limits. 27.55 Section 27.55... COMMUNICATIONS SERVICES Technical Standards § 27.55 Power strength limits. (a) Field strength limits. For the following bands, the predicted or measured median field strength at any location on the geographical...

  17. Study of the behavioral and biological effects of high-strength 60-Hz electric fields. Quarterly progress report, 11 October 1981-10 January 1982. [Research plan

    SciTech Connect

    Rogers, W.R.

    1982-01-01

    The primary objective of this research is to study the effects of high intensity, 60 Hz electric fields on baboon behavior to obtain information which will assist in the determination of the degree of risk of deleterious consequences for humans exposed to such fields. The generalization of results obtained with the baboon to predictions concerning humans will be aided by the development of computer models relating the surface electric field intensities and internal current densities produced in baboons and humans by exposure to high intensity, 60 Hz electric fields. Research plans are described.

  18. Application of Strength Diagnosis.

    ERIC Educational Resources Information Center

    Newton, Robert U.; Dugan, Eric

    2002-01-01

    Discusses the various strength qualities (maximum strength, high- and low-load speed strength, reactive strength, rate of force development, and skill performance), noting why a training program design based on strength diagnosis can lead to greater efficacy and better performance gains for the athlete. Examples of tests used to assess strength…

  19. Study of the behavioral and biological effects of high strength 60 HZ electric fields. Quarterly technical progress report No. 15, 12 May 1984-3 August 1984

    SciTech Connect

    Not Available

    1984-08-15

    Progress is reported in the construction of a test facility for studying the effects of high intensity, 60 Hz electric fields on baboons. Effects to be studied include operant out social behaviors. (ACR)

  20. Second solar spectrum of the Sr I 4607 Å line: depth probing of the turbulent magnetic field strength in a quiet region

    NASA Astrophysics Data System (ADS)

    Derouich, M.; Bommier, V.; Malherbe, J. M.; Landi Degl'Innocenti, E.

    2006-10-01

    Aims.This paper is devoted to an interpretation of Quiet-Sun, spatially-resolved spectropolarimetric observations of the Hanle effect in terms of turbulent weak magnetic field determination. Methods: . Observations: the slit was positioned perpendicular to the limb, and the spatial resolution along the slit was 1 arcsec, leading to a depth probing along 132 different limb distances. The new polarimeter of the Pic-du-Midi Turret Dome was used on May 14, 2004 to observe a quiet region at the East limb equator in the resonance line of neutral Strontium at 4607 Å. Results: . For each limb distance, we properly adjusted the theoretical intensity profile obtained by applying a zero-field model to the observed one. Micro- and macroturbulent velocities were thus derived (average values v{micro}=1.77 km s-1 and v{macro}=1.95 km s-1). The magnetic field was determined in a second step by interpreting the Hanle effect on the line center linear polarization degree. The depolarizing collisions with neutral hydrogen were taken fully into account through a semi-classical calculation of their rates. An average value of B=38 Gauss was thus derived. Finally, error bars on the magnetic field values were evaluated from a) the polarimetric inaccuracy, b) the limb distance determination inaccuracy, and c) the uncertainty on our theoretical collisional depolarizing rates that we evaluated. This combination leads to 10-20% as total relative error on the magnetic field determination by the Hanle effect method. Since the inaccuracy due to the model itself was hard to properly evaluate, it was ignored. An uncertainty of ±60 km on the line formation depth was, however, derived from the contribution functions. The magnetic field is found to increase slowly with height in the height range 220-300 km above τ5000=1 and then decrease in the height range 300-370 km.

  1. Apparatus and procedure to characterize the surface quality of conductors by measuring the rate of cathode emission as a function of surface electric field strength

    DOEpatents

    Mestayer, Mac; Christo, Steve; Taylor, Mark

    2014-10-21

    A device and method for characterizing quality of a conducting surface. The device including a gaseous ionizing chamber having centrally located inside the chamber a conducting sample to be tested to which a negative potential is applied, a plurality of anode or "sense" wires spaced regularly about the central test wire, a plurality of "field wires" at a negative potential are spaced regularly around the sense, and a plurality of "guard wires" at a positive potential are spaced regularly around the field wires in the chamber. The method utilizing the device to measure emission currents from the conductor.

  2. Reduction of Polarization Field Strength in Fully Strained c-Plane InGaN/(In)GaN Multiple Quantum Wells Grown by MOCVD

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Ikeda, Masao; Zhang, Shu-Ming; Liu, Jian-Ping; Tian, Ai-Qin; Wen, Peng-Yan; Cheng, Yang; Yang, Hui

    2016-11-01

    The polarization fields in c-plane InGaN/(In)GaN multiple quantum well (MQW) structures grown on sapphire substrate by metal-organic chemical vapor deposition are investigated in this paper. The indium composition in the quantum wells varies from 14.8 to 26.5% for different samples. The photoluminescence wavelengths are calculated theoretically by fully considering the related effects and compared with the measured wavelengths. It is found that when the indium content is lower than 17.3%, the measured wavelengths agree well with the theoretical values. However, when the indium content is higher than 17.3%, the measured ones are much shorter than the calculation results. This discrepancy is attributed to the reduced polarization field in the MQWs. For the MQWs with lower indium content, 100% theoretical polarization can be maintained, while, when the indium content is higher, the polarization field decreases significantly. The polarization field can be weakened down to 23% of the theoretical value when the indium content is 26.5%. Strain relaxation is excluded as the origin of the polarization reduction because there is no sign of lattice relaxation in the structures, judging by the X-ray diffraction reciprocal space mapping. The possible causes of the polarization reduction are discussed.

  3. Reduction of Polarization Field Strength in Fully Strained c-Plane InGaN/(In)GaN Multiple Quantum Wells Grown by MOCVD.

    PubMed

    Zhang, Feng; Ikeda, Masao; Zhang, Shu-Ming; Liu, Jian-Ping; Tian, Ai-Qin; Wen, Peng-Yan; Cheng, Yang; Yang, Hui

    2016-12-01

    The polarization fields in c-plane InGaN/(In)GaN multiple quantum well (MQW) structures grown on sapphire substrate by metal-organic chemical vapor deposition are investigated in this paper. The indium composition in the quantum wells varies from 14.8 to 26.5% for different samples. The photoluminescence wavelengths are calculated theoretically by fully considering the related effects and compared with the measured wavelengths. It is found that when the indium content is lower than 17.3%, the measured wavelengths agree well with the theoretical values. However, when the indium content is higher than 17.3%, the measured ones are much shorter than the calculation results. This discrepancy is attributed to the reduced polarization field in the MQWs. For the MQWs with lower indium content, 100% theoretical polarization can be maintained, while, when the indium content is higher, the polarization field decreases significantly. The polarization field can be weakened down to 23% of the theoretical value when the indium content is 26.5%. Strain relaxation is excluded as the origin of the polarization reduction because there is no sign of lattice relaxation in the structures, judging by the X-ray diffraction reciprocal space mapping. The possible causes of the polarization reduction are discussed.

  4. Dose-Dependent ATP Depletion and Cancer Cell Death following Calcium Electroporation, Relative Effect of Calcium Concentration and Electric Field Strength

    PubMed Central

    Hansen, Emilie Louise; Sozer, Esin Bengisu; Romeo, Stefania; Frandsen, Stine Krog; Vernier, P. Thomas; Gehl, Julie

    2015-01-01

    Background Electroporation, a method for increasing the permeability of membranes to ions and small molecules, is used in the clinic with chemotherapeutic drugs for cancer treatment (electrochemotherapy). Electroporation with calcium causes ATP (adenosine triphosphate) depletion and cancer cell death and could be a novel cancer treatment. This study aims at understanding the relationship between applied electric field, calcium concentration, ATP depletion and efficacy. Methods In three human cell lines — H69 (small-cell lung cancer), SW780 (bladder cancer), and U937 (leukaemia), viability was determined after treatment with 1, 3, or 5 mM calcium and eight 99 μs pulses with 0.8, 1.0, 1.2, 1.4 or 1.6 kV/cm. Fitting analysis was applied to quantify the cell-killing efficacy in presence of calcium. Post-treatment intracellular ATP was measured in H69 and SW780 cells. Post-treatment intracellular ATP was observed with fluorescence confocal microscopy of quinacrine-labelled U937 cells. Results Both H69 and SW780 cells showed dose-dependent (calcium concentration and electric field) decrease in intracellular ATP (p<0.05) and reduced viability. The 50% effective cell kill was found at 3.71 kV/cm (H69) and 3.28 kV/cm (SW780), reduced to 1.40 and 1.15 kV/cm (respectively) with 1 mM calcium (lower EC50 for higher calcium concentrations). Quinacrine fluorescence intensity of calcium-electroporated U937 cells was one third lower than in controls (p<0.0001). Conclusions Calcium electroporation dose-dependently reduced cell survival and intracellular ATP. Increasing extracellular calcium allows the use of a lower electric field. General Significance This study supports the use of calcium electroporation for treatment of cancer and possibly lowering the applied electric field in future trials. PMID:25853661

  5. Accelerated mapping of magnetic susceptibility using 3D planes-on-a-paddlewheel (POP) EPI at ultra-high field strength.

    PubMed

    Stäb, Daniel; Bollmann, Steffen; Langkammer, Christian; Bredies, Kristian; Barth, Markus

    2017-04-01

    With the advent of ultra-high field MRI scanners in clinical research, susceptibility based MRI has recently gained increasing interest because of its potential to assess subtle tissue changes underlying neurological pathologies/disorders. Conventional, but rather slow, three-dimensional (3D) spoiled gradient-echo (GRE) sequences are typically employed to assess the susceptibility of tissue. 3D echo-planar imaging (EPI) represents a fast alternative but generally comes with echo-time restrictions, geometrical distortions and signal dropouts that can become severe at ultra-high fields. In this work we assess quantitative susceptibility mapping (QSM) at 7 T using non-Cartesian 3D EPI with a planes-on-a-paddlewheel (POP) trajectory, which is created by rotating a standard EPI readout train around its own phase encoding axis. We show that the threefold accelerated non-Cartesian 3D POP EPI sequence enables very fast, whole brain susceptibility mapping at an isotropic resolution of 1 mm and that the high image quality has sufficient signal-to-noise ratio in the phase data for reliable QSM processing. The susceptibility maps obtained were comparable with regard to QSM values and geometric distortions to those calculated from a conventional 4 min 3D GRE scan using the same QSM processing pipeline. Copyright © 2016 John Wiley & Sons, Ltd.

  6. A general model to calculate the spin-lattice (T1) relaxation time of blood, accounting for haematocrit, oxygen saturation and magnetic field strength.

    PubMed

    Hales, Patrick W; Kirkham, Fenella J; Clark, Christopher A

    2016-02-01

    Many MRI techniques require prior knowledge of the T1-relaxation time of blood (T1bl). An assumed/fixed value is often used; however, T1bl is sensitive to magnetic field (B0), haematocrit (Hct), and oxygen saturation (Y). We aimed to combine data from previous in vitro measurements into a mathematical model, to estimate T1bl as a function of B0, Hct, and Y. The model was shown to predict T1bl from in vivo studies with a good accuracy (± 87 ms). This model allows for improved estimation of T1bl between 1.5-7.0 T while accounting for variations in Hct and Y, leading to improved accuracy of MRI-derived perfusion measurements.

  7. Non-linear uplift Ansätze for the internal metric and the four-form field-strength of maximal supergravity

    NASA Astrophysics Data System (ADS)

    Krüger, Olaf

    2016-05-01

    The uplift of SO(8) gauged N = 8 supergravity to 11-dimensional supergravity is well studied in the literature. It is given by consistent relations between the respective vector and scalar fields of both theories. For example, recent work provided non-linear uplift Ansätze for the scalar degrees of freedom on the internal manifold: the inverse metric and the three-form flux with mixed index structure. However, one always found the metric of the compactified manifold by inverting the inverse metric — a task that was only possible in particular cases, e.g. for the G2, SO(3)×SO(3) or SU(3)×U(1)×U(1) invariant solutions of 11-dimensional supergravity.

  8. Magnetic field sensor based on selectively magnetic fluid infiltrated dual-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Gangwar, Rahul Kumar; Bhardwaj, Vanita; Singh, Vinod Kumar

    2016-02-01

    We reported the modeling result of selectively magnetic fluid infiltrated dual-core photonic crystal fiber based magnetic field sensor. Inside the cross-section of the designed photonic crystal fiber, the two fiber cores filled with magnetic fluid (Fe3O4) form two independent waveguides with mode coupling. The mode coupling under different magnetic field strengths is investigated theoretically. The sensitivity of the sensor as a function of the structural parameters of the photonic crystal fiber is calculated. The result shows that the proposed sensing device with 1 cm photonic crystal fiber length has a large sensitivity of 305.8 pm/Oe.

  9. Polycyclic Aromatic Hydrocarbon Emission in Spitzer/IRS Maps. II. A Direct Link between Band Profiles and the Radiation Field Strength

    NASA Astrophysics Data System (ADS)

    Stock, D. J.; Peeters, E.

    2017-03-01

    We decompose the observed 7.7 μm polycyclic aromatic hydrocarbon (PAH) emission complexes in a large sample of over 7000 mid-infrared spectra of the interstellar medium using spectral cubes observed with the Spitzer/IRS-SL instrument. In order to fit the 7.7 μm PAH emission complex we invoke four Gaussian components, which are found to be very stable in terms of their peak positions and widths across all of our spectra, and subsequently define a decomposition with fixed parameters, which gives an acceptable fit for all the spectra. We see a strong environmental dependence on the interrelationships between our band fluxes—in the H ii regions all four components are intercorrelated, while in the reflection nebulae (RNs) the inner and outer pairs of bands correlate in the same manner as previously seen for NGC 2023. We show that this effect arises because the maps of RNs are dominated by emission from strongly irradiated photodissociation regions, while the much larger maps of H ii regions are dominated by emission from regions much more distant from the exciting stars, leading to subtly different spectral behavior. Further investigation of this dichotomy reveals that the ratio of two of these components (centered at 7.6 and 7.8 μm) is linearly related to the UV-field intensity (log G 0). We find that this relationship does not hold for sources consisting of circumstellar material, which are known to have variable 7.7 μm spectral profiles.

  10. Flexibility and Muscular Strength.

    ERIC Educational Resources Information Center

    Liemohn, Wendell

    1988-01-01

    This definition of flexibility and muscular strength also explores their roles in overall physical fitness and focuses on how increased flexibility and muscular strength can help decrease or eliminate lower back pain. (CB)

  11. Strength Training for Girls.

    ERIC Educational Resources Information Center

    Connaughton, Daniel; Connaughton, Angela; Poor, Linda

    2001-01-01

    Strength training can be fun, safe, and appropriate for young girls and women and is an important component of any fitness program when combined with appropriate cardiovascular and flexibility activities. Concerns and misconceptions regarding girls' strength training are discussed, presenting general principles of strength training for children…

  12. Electronic properties of quasi one-dimensional quantum wire models under equal coupling strength superpositions of Rashba and Dresselhaus spin-orbit interactions in the presence of an in-plane magnetic field

    SciTech Connect

    Papp, E.; Micu, C.; Racolta, D.

    2013-11-13

    In this paper one deals with the theoretical derivation of energy bands and of related wavefunctions characterizing quasi 1D semiconductor heterostructures, such as InAs quantum wire models. Such models get characterized this time by equal coupling strength superpositions of Rashba and Dresselhaus spin-orbit interactions of dimensionless magnitude a under the influence of in-plane magnetic fields of magnitude B. We found that the orientations of the field can be selected by virtue of symmetry requirements. For this purpose one resorts to spin conservations, but alternative conditions providing sensible simplifications of the energy-band formula can be reasonably accounted for. Besides the wavenumber k relying on the 1D electron, one deals with the spin-like s=±1 factors in the front of the square root term of the energy. Having obtained the spinorial wavefunction, opens the way to the derivation of spin precession effects. For this purpose one resorts to the projections of the wavenumber operator on complementary spin states. Such projections are responsible for related displacements proceeding along the Ox-axis. This results in a 2D rotation matrix providing both the precession angle as well as the precession axis.

  13. Strength Modeling Report

    NASA Technical Reports Server (NTRS)

    Badler, N. I.; Lee, P.; Wong, S.

    1985-01-01

    Strength modeling is a complex and multi-dimensional issue. There are numerous parameters to the problem of characterizing human strength, most notably: (1) position and orientation of body joints; (2) isometric versus dynamic strength; (3) effector force versus joint torque; (4) instantaneous versus steady force; (5) active force versus reactive force; (6) presence or absence of gravity; (7) body somatotype and composition; (8) body (segment) masses; (9) muscle group envolvement; (10) muscle size; (11) fatigue; and (12) practice (training) or familiarity. In surveying the available literature on strength measurement and modeling an attempt was made to examine as many of these parameters as possible. The conclusions reached at this point toward the feasibility of implementing computationally reasonable human strength models. The assessment of accuracy of any model against a specific individual, however, will probably not be possible on any realistic scale. Taken statistically, strength modeling may be an effective tool for general questions of task feasibility and strength requirements.

  14. Test of QED at critical field strength

    SciTech Connect

    Bula, C.

    1997-01-01

    In a new experiment at the Final Focus Test Beam at SLAC, a low-emittance 46.6 GeV electron beam is brought into collisions with terawatt pulses of 1054 nm or 527 nm wavelength from a Nd:glass laser. Peak laser intensities of 10{sup 18} W/cm{sup 2} have been achieved corresponding to a value of 0.6 for the parameter {eta} = e{epsilon}/m{omega}{sub 0}c. In this case, an electron that crosses the center of the laser pulse has near-unit interaction probability. Results are presented for multiphoton Compton scattering in which an electron interacts with up to four laser photons, in agreement with theoretical calculations.

  15. Test of QED at critical field strength

    SciTech Connect

    Bula, C.; E-144 Collaboration

    1996-10-01

    In a new experiment at the Final Focus Test Beam at SLAC, a low-emittance 46.6 GeV electron beam is brought into collision with terawatt pulses of 1,054 nm or 527 nm wavelength from a Nd:glass laser. Peak laser intensities of 10{sup 18} W/cm{sup 2} have been achieved corresponding to a value of 0.6 for the parameter {eta} = e{var_epsilon}m{omega}{sub 0}c. In this case, an electron that crosses the center of the laser pulse has near-unit interaction probability. Results are presented for multiphoton Compton scattering in which an electron interacts with up to four laser photons, in agreement with theoretical calculations.

  16. Pulsar Emission Geometry and Accelerating Field Strength

    DTIC Science & Technology

    2011-11-01

    ar X iv :1 11 1. 03 25 v1 [ as tr o- ph .H E ] 1 N ov 2 01 1 2011 Fermi Symposium, Roma., May. 9-12 1 Pulsar Emission Geometry and Accelerating...observations of gamma-ray pulsars have opened a new window to understanding the generation mechanisms of high-energy emission from these systems. The high...the Vela and CTA 1 pulsars with simulated high-energy light curves generated from geometrical representations of the outer gap and slot gap emission

  17. Alumina fiber strength improvement

    NASA Technical Reports Server (NTRS)

    Pepper, R. T.; Nelson, D. C.

    1982-01-01

    The effective fiber strength of alumina fibers in an aluminum composite was increased to 173,000 psi. A high temperature heat treatment, combined with a glassy carbon surface coating, was used to prevent degradation and improve fiber tensile strength. Attempts to achieve chemical strengthening of the alumina fiber by chromium oxide and boron oxide coatings proved unsuccessful. A major problem encountered on the program was the low and inconsistent strength of the Dupont Fiber FP used for the investigation.

  18. Strength Training and Your Child

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Strength Training and Your Child KidsHealth > For Parents > Strength ... help prevent injuries and speed up recovery. About Strength Training Strength training is the practice of using ...

  19. Extreme high field strength element (HFSE) depletion and near-chondritic Nb/Ta ratios in Central Andean adakite-like lavas (~ 28°S, ~ 68°W)

    NASA Astrophysics Data System (ADS)

    Goss, A. R.; Kay, S. M.

    2009-03-01

    The eruption of andesites with steep REE patterns and high Sr concentrations (adakite-like) in the northernmost Chilean flatslab region of the Central Andes spatially and temporally corresponds with the appearance of a marked HFSE (high field strength element) depletion in these lavas (La/Ta up to 95). Known as the Dos Hermanos and Pircas Negras andesites, these lavas erupted at the beginning (˜ 8 Ma), during (7-3 Ma), and immediately following (3-2 Ma) a period of tectonic instability characterized by eastward migration of the frontal volcanic arc. ICP-MS analyses of the HFSE reveal a range of chondritic (20-18) to subchondritic (18-11) Nb/Ta ratios in these lavas. Evident temporal trace element trends support a change from a rutile-bearing to an amphibole-bearing eclogitic residual assemblage in equilibrium with the mafic precursor magmas of these andesites. This change in residual mineralogy is contemporaneous with the onset of frontal arc migration in the region. Potential eclogitic sources for the Dos Hermanos and Pircas Negras adakitic andesites include mafic Andean lower crust and an additional flux of forearc crust transported to the sub-arc mantle via subduction erosion during the height of arc migration and Pircas Negras magmatism. Batch melting models of rutile- or amphibole-bearing eclogitic arc basalt in tandem with magma mixing calculations generate the observed adakitic signatures and near-chondritic Nb/Ta ratios of these Central Andean andesites.

  20. 47 CFR 27.55 - Power strength limits.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Power strength limits. 27.55 Section 27.55 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.55 Power strength limits. (a) Field strength limits. For...

  1. 47 CFR 27.55 - Power strength limits.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Power strength limits. 27.55 Section 27.55 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.55 Power strength limits. (a) Field strength limits. For...

  2. 47 CFR 27.55 - Power strength limits.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Power strength limits. 27.55 Section 27.55 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.55 Power strength limits. (a) Field strength limits. For...

  3. Variation of the Earth's magnetic field strength in South America during the last two millennia: New results from historical buildings of Buenos Aires and re-evaluation of regional data

    NASA Astrophysics Data System (ADS)

    Goguitchaichvili, Avto; Morales, Juan; Schavelzon, Daniel; Vásquez, Carlos; Gogorza, Claudia S. G.; Loponte, Daniel; Rapalini, Augusto

    2015-08-01

    The causes of the systematic decay of the Earth's Magnetic Field strength since eighteen century have been a matter of debate during the last decade. It is also well known that such variations may have completely different expressions under an area characterized with strong magnetic anomalies, such as the South Atlantic Magnetic Anomaly. To fully understand these atypical phenomena, it is crucial to retrieve the past evolution of Earth's magnetic field beyond the observatory records. We report on detailed rock-magnetic and archeointensity investigations from some well-studied historical buildings of Buenos Aires city, located at the heart of the South Atlantic Magnetic Anomaly. Samples consist of bricks, tiles, fireplaces and pottery, which are considered as highly suitable materials for archaeointensity studies. The dating is ascertained by historical documents complemented by archeological constraints. Eighteen out of 26 analyzed samples yield reliable absolute intensity determinations. The site-mean archaeointensity values obtained in this study range from 28.5 to 43.5 μT, with corresponding virtual axial dipole moments (VADMs) ranging from 5.3 to 8.04 × 1022 Am2. Most determinations obtained in the present study are in remarkable agreement with the values predicted by the time varying field model CALS10k.1b (Korte et al., 2011). For the older periods the recently available SHA.DIF.14 model (Pavon-Carrasco et al., 2014) seems to have greater resolution. South American archaeointensity database now includes absolute intensities from 400 to 1930 AD based on 63 selected archaeointensity determinations. The data set reveals several distinct periods of quite large fluctuations of intensity. However, most data are concentrated into a relatively narrow interval from AD 1250 to AD 1450. At the beginning of the record, values between 400 AD and 830 AD match well with ARCH3k.1 model. Some general features may be detected: the time intervals from about AD 400 to 950 and

  4. The Annual Cosmic-Radiation Intensities 1391 - 2014; The Annual Heliospheric Magnetic Field Strengths 1391 - 1983, and Identification of Solar Cosmic-Ray Events in the Cosmogenic Record 1800 - 1983

    NASA Astrophysics Data System (ADS)

    McCracken, K. G.; Beer, J.

    2015-10-01

    The annual cosmogenic ^{10}Be ice-core data from Dye 3 and the North Greenland Ice-core Project (NGRIP), and neutron-monitor data, 1951 - 2014, are combined to yield a record of the annual cosmic-ray intensity, 1391 - 2014. These data were then used to estimate the intensity of the heliospheric magnetic field (HMF), 1391 - 1983. All of these annual data are provided in the Electronic Supplementary Material. Analysis of these annual data shows that there were significant impulsive increases in ^{10}Be production in the year following the very large solar cosmic-ray events of 1942, 1949, and 1956. There was an additional enhancement that we attribute to six high-altitude nuclear explosions in 1962. All of these enhancements result in underestimates of the strength of the HMF. An identification process is defined, resulting in a total of seven impulsive ^{10}Be events in the interval 1800 - 1942 prior to the first detection of a solar cosmic-ray event using ionization chambers. Excision of the ^{10}Be impulsive enhancements yields a new estimate of the HMF, designated B(PCR-2). Five of the seven ^{10}Be enhancements prior to 1941 are well correlated with the occurrence of very great geomagnetic storms. It is shown that a solar cosmic-ray event similar to that of 25 July 1946, and occurring in the middle of the second or third year of the solar cycle, may merge with the initial decreasing phase of the 11-year cycle in cosmic-ray intensity and be unlikely to be detected in the ^{10}Be data. It is concluded that the occurrence rate for solar energetic-particle (SEP) events such as that on 23 February 1956 is about seven per century, and that there is an upper limit to the size of solar cosmic-ray events.

  5. Strength and Balance Exercises

    MedlinePlus

    ... Venous Thromboembolism Aortic Aneurysm More Strength and Balance Exercises Updated:Sep 8,2016 If you have medical ... if you have been inactive and want to exercise vigorously, check with your doctor before beginning a ...

  6. Crew Strength Training

    NASA Video Gallery

    Train to develop your upper and lower body strength in your muscles and bones by performing body-weight squats and push-ups.The Train Like an Astronaut project uses the excitement of exploration to...

  7. Hand-Strength Meter

    NASA Technical Reports Server (NTRS)

    Tcheng, Ping; Elliot, Joe

    1987-01-01

    Special grip-strength meter designed for accurate, reproducible measurement of hand rehabilitation. Four strain gauges connected in Wheatstone bridge to measure deflection caused by gripping hand. Compressive force exerted by hand transmitted to measuring beams. Beams therefore deflected or strained, and mechanical strain sensed by strain gauges and converted into electrical signal. After amplification and conditioning, signal displayed on LED as measure of gripping strength of hand.

  8. Apple Strength Issues

    SciTech Connect

    Syn, C

    2009-12-22

    Strength of the apple parts has been noticed to decrease, especially those installed by the new induction heating system since the LEP campaign started. Fig. 1 shows the ultimate tensile strength (UTS), yield strength (YS), and elongation of the installed or installation-simulated apples on various systems. One can clearly see the mean values of UTS and YS of the post-LEP parts decreased by about 8 ksi and 6 ksi respectively from those of the pre-LEP parts. The slight increase in elongation seen in Fig.1 can be understood from the weak inverse relationship between the strength and elongation in metals. Fig.2 shows the weak correlation between the YS and elongation of the parts listed in Fig. 1. Strength data listed in Figure 1 were re-plotted as histograms in Figs. 3 and 4. Figs. 3a and 4a show histograms of all UTS and YS data. Figs. 3b and 4b shows histograms of pre-LEP data and Figs. 3c and 4c of post-LEP data. Data on statistical scatter of tensile strengths have been rarely published by material suppliers. Instead, only the minimum 'guaranteed' strength data are typically presented. An example of strength distribution of aluminum 7075-T6 sheet material, listed in Fig. 5, show that its scatter width of both UTS and YS for a single sheet can be about 6 ksi and for multi-lot scatter can be as large as 11 ksi even though the sheets have been produced through well-controlled manufacturing process. By approximating the histograms shown in Figs. 3 and 4 by a Gaussian or similar type of distribution curves, one can plausibly see the strength reductions in the later or more recent apples. The pre-LEP data in Figs. 3b and 4b show wider scatter than the post-LEP data in Figs. 3c and 4c and seem to follow the binomial distribution of strength indicating that the apples might have been made from two different lots of material, either from two different vendors or from two different melts of perhaps slightly different chemical composition by a single vendor. The post

  9. Performance of An Adjustable Strength Permanent Magnet Quadrupole

    SciTech Connect

    Gottschalk, S.C.; DeHart, T.E.; Kangas, K.W.; Spencer, C.M.; Volk, J.T.; /Fermilab

    2006-03-01

    An adjustable strength permanent magnet quadrupole suitable for use in Next Linear Collider has been built and tested. The pole length is 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) is 68.7 Tesla. This paper describes measurements of strength, magnetic CL and field quality made using an air bearing rotating coil system. The magnetic CL stability during -20% strength adjustment proposed for beam based alignment was < 0.2 microns. Strength hysteresis was negligible. Thermal expansion of quadrupole and measurement parts caused a repeatable and easily compensated change in the vertical magnetic CL. Calibration procedures as well as CL measurements made over a wider tuning range of 100% to 20% in strength useful for a wide range of applications will be described. The impact of eddy currents in the steel poles on the magnetic field during strength adjustments will be reported.

  10. The Density and Compressibility of BaCO3-SrCO3-CaCO3-K2CO3-Na2CO3-Li2CO3 Liquids: New Measurements and a Systematic Trend with Cation Field Strength

    NASA Astrophysics Data System (ADS)

    Hurt, S. M.; Lange, R. A.; Ai, Y.

    2015-12-01

    The volumetric properties of multi-component carbonate liquids are required to extend thermodynamic models that describe partial melting of the deep mantle (e.g. pMELTS; Ghiorso et al., 2003) to carbonate-bearing lithologies. Carbonate in the mantle is an important reservoir of carbon, which is released to the atmosphere as CO2 through volcanism, and thus contributes to the carbon cycle. Although MgCO3 is the most important carbonate component in the mantle, it is not possible to directly measure the 1-bar density and compressibility of MgCO3 liquid because, like other alkaline-earth carbonates, it decomposes at a temperature lower than its melting temperature. Despite this challenge, Liu and Lange (2003) and O'Leary et al. (2015) showed that the one bar molar volume, thermal expansion and compressibility of the CaCO3 liquid component could be obtained by measuring the density and sound speeds of stable liquids in the CaCO3-Li2CO3-Na2CO3-K2CO3 quaternary system at one bar. In this study, this same strategy is employed on SrCO3- and BaCO3-bearing alkali carbonate liquids. The density and sound speed of seven liquids in the SrCO3-Li2CO3-Na2CO3-K2CO3 quaternary and three liquids in the BaCO3-Li2CO3-Na2CO3-K2CO3 quaternary were measured from 739-1367K, with SrCO3 and BaCO3 concentrations ranging from 10-50 mol%. The density measurements were made using the double-bob Archimedean method and sound speeds were obtained with a frequency-sweep acoustic interferometer. The molar volume and sound speed measurements were used to calculate the isothermal compressibility of each liquid, and the results show the volumetric properties mix ideally with composition. The partial molar volume and compressibility of the SrCO3 and BaCO3 components are compared to those obtained for the CaCO3 component as a function of cation field strength. The results reveal a systematic trend that allows the partial molar volume and compressibility of the MgCO3 liquid component to be estimated.

  11. Strength of inorganic glass

    SciTech Connect

    Kurkjian, C.R.

    1985-01-01

    This book presents information on the following topics: a look at the history of glass strength; atomistic theory of fracture; surface chemistry in relation to the strength and fracture of silicate glasses; high-speed photographic investigations of the dynamic localized loading of some oxide glasses; a correction for measurements of contact area using Newton's rings; envionmentally enhanced crack growth; fatigue in glass; behavior of flaws in fused silica fibers; fracture toughness of chalcogenide glasses and glass-ceramics; fracture analysis of glass surfaces; and fracture mechanics parameters for glasses - a compilation and correlation.

  12. Spin Resonance Strength Calculations

    NASA Astrophysics Data System (ADS)

    Courant, E. D.

    2009-08-01

    In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.

  13. High strength alloys

    DOEpatents

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  14. High strength alloys

    DOEpatents

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  15. Notch strength of composites

    NASA Technical Reports Server (NTRS)

    Whitney, J. M.

    1983-01-01

    The notch strength of composites is discussed. The point stress and average stress criteria relate the notched strength of a laminate to the average strength of a relatively long tensile coupon. Tests of notched specimens in which microstrain gages have been placed at or near the edges of the holes have measured strains much larger that those measured in an unnotched tensile coupon. Orthotropic stress concentration analyses of failed notched laminates have also indicated that failure occurred at strains much larger than those experienced on tensile coupons with normal gage lengths. This suggests that the high strains at the edge of a hole can be related to the very short length of fiber subjected to these strains. Lockheed has attempted to correlate a series of tests of several laminates with holes ranging from 0.19 to 0.50 in. Although the average stress criterion correlated well with test results for hole sizes equal to or greater than 0.50 in., it over-estimated the laminate strength in the range of hole sizes from 0.19 to 0.38 in. It thus appears that a theory is needed that is based on the mechanics of failure and is more generally applicable to the range of hole sizes and the varieties of laminates found in aircraft construction.

  16. High strength composites evaluation

    SciTech Connect

    Marten, S.M.

    1992-02-01

    A high-strength, thick-section, graphite/epoxy composite was identified. The purpose of this development effort was to evaluate candidate materials and provide LANL with engineering properties. Eight candidate materials (Samples 1000, 1100, 1200, 1300, 1400, 1500, 1600, and 1700) were chosen for evaluation. The Sample 1700 thermoplastic material was the strongest overall.

  17. (Finite) statistical size effects on compressive strength

    PubMed Central

    Weiss, Jérôme; Girard, Lucas; Gimbert, Florent; Amitrano, David; Vandembroucq, Damien

    2014-01-01

    The larger structures are, the lower their mechanical strength. Already discussed by Leonardo da Vinci and Edmé Mariotte several centuries ago, size effects on strength remain of crucial importance in modern engineering for the elaboration of safety regulations in structural design or the extrapolation of laboratory results to geophysical field scales. Under tensile loading, statistical size effects are traditionally modeled with a weakest-link approach. One of its prominent results is a prediction of vanishing strength at large scales that can be quantified in the framework of extreme value statistics. Despite a frequent use outside its range of validity, this approach remains the dominant tool in the field of statistical size effects. Here we focus on compressive failure, which concerns a wide range of geophysical and geotechnical situations. We show on historical and recent experimental data that weakest-link predictions are not obeyed. In particular, the mechanical strength saturates at a nonzero value toward large scales. Accounting explicitly for the elastic interactions between defects during the damage process, we build a formal analogy of compressive failure with the depinning transition of an elastic manifold. This critical transition interpretation naturally entails finite-size scaling laws for the mean strength and its associated variability. Theoretical predictions are in remarkable agreement with measurements reported for various materials such as rocks, ice, coal, or concrete. This formalism, which can also be extended to the flowing instability of granular media under multiaxial compression, has important practical consequences for future design rules. PMID:24733930

  18. The strength anisotropia of sea ice

    SciTech Connect

    Evdokimov, G.N.; Rogachko, S.I.

    1994-12-31

    The hydraulic-engineering structure calculations of sea ice formation force require the sea ice strength data. The strength characteristics values and the types of sea ice formations in view of water depth define the type and the design of future structures in each particular region of supposed construction. The most objective information on the sea ice physical and technical properties can be obtained by field investigations ad the existing methods of their calculations refer to a great number of errors. The accumulated bank of data on studying the sea ice formation strength properties show one that ice as a natural material is of great crystalline structure variety. The level ice fields have a number of particularities. The crystal sizes increase in ice thickness. The crystals consist of fresh-water thin plates 0.5--0.6 mm in thickness oriented by pickle-water interlayers. Difference in thickness of the sea ice cover structure is one of the main causes of the changes strength characteristics layer. Besides that the sea ice strength depends upon the destroying force direction in reference to crystal orientation which characterizes the sea ice anisotropia as a material.

  19. Spin resonance strength calculation through single particle tracking for RHIC

    SciTech Connect

    Luo, Y.; Dutheil, Y.; Huang, H.; Meot, F.; Ranjbar, V.

    2015-05-03

    The strengths of spin resonances for the polarized-proton operation in the Relativistic Heavy Ion Collider are currently calculated with the code DEPOL, which numerically integrates through the ring based on an analytical approximate formula. In this article, we test a new way to calculate the spin resonance strengths by performing Fourier transformation to the actual transverse magnetic fields seen by a single particle traveling through the ring. Comparison of calculated spin resonance strengths is made between this method and DEPOL.

  20. Personnel Services Delivery Redesign (PSDR) and Brigade Level Strength Management

    DTIC Science & Technology

    2013-02-14

    people now predict, the standard organization of the twentieth century will likely become a dinosaur .1 This quote from Professor John P...strength management tasks and are currently executing vs monitoring (emphasis in original ) in order to cross-level strength, perform field grade...involvement and the personality of the Senior Mission Commander, it turns very quickly to strength management. 11 Modularity’s original assumptions of

  1. Short-term Periodization Models: Effects on Strength and Speed-strength Performance.

    PubMed

    Hartmann, Hagen; Wirth, Klaus; Keiner, Michael; Mickel, Christoph; Sander, Andre; Szilvas, Elena

    2015-10-01

    avoided because it does not provide an adequate training stimulus for gains in muscle cross-sectional area and strength performance. High-volume circuit strength training performed over 2 years negatively affected the development of the power output and maximal strength of the upper extremities in professional rugby players. Indeed, meta-analyses and results with weightlifters, American Football players, and throwers confirm the necessity of the habitual use of ≥80% 1 RM: (1) to improve maximal strength during the off-season and in-season in American Football, (2) to reach peak performance in maximal strength and vertical jump power during tapering in track-and-field, and (3) to produce hypertrophy and strength improvements in advanced athletes. The integration and extent of hypertrophy strength training in in-season conditioning depend on the duration of the contest period, the frequency of the contests, and the proportion of the conditioning program. Based on the literature, 72 h between hypertrophy strength training and strength-power training should be provided to allow for adequate regeneration times and therefore maximal stimulus intensities in training. This conclusion is only valid if the muscle is not trained otherwise during this regeneration phase. Thus, rotating hypertrophy and strength-power sessions in a microcycle during the season is a viable option. Comparative studies in competitive athletes who integrated strength training during pre-season conditioning confirm a tendency for gains in explosive strength and statistically significant improvements in medicine ball throw through SPP but not through daily undulating periodization. These findings indicate that to maximize the speed-strength in the short term (peaking), elite athletes should perform strength-power training twice per week. It is possible to perform a single strength-power session with the method of maximum explosive strength actions moving high-weight loads (90% 1 repetition maximum [RM]) at

  2. In-situ rock strength determination for blasting purposes

    SciTech Connect

    Soni, D.K.; Jain, A.

    1994-12-31

    Compressive strength of rocks is often required by mining engineers and quarrying authorities for blasting operations. Uniaxial compressive strength of rocks can be predicted with reasonable accuracy with the help of point load strength tests which can be easily conducted at site by the field staff, simultaneously as the cores are recovered from drilling operations. A number of diametral point load tests and uniaxial compressive strength tests have been conducted on the specimens of different rock types under air dried, and saturated condition as well to study the effect of ground water saturation on strength. It has been observed that due to saturation uniaxial compressive strength and point load strength get reduced to a maximum of 32 and 29 percent respectively. It has also been observed that uniaxial strength is sixteen times the point load strength in air dried as well as saturated condition. However, this factor used for calculating uniaxial compressive strength may be reduced to a lower value for the safety of miners in field blasting operations.

  3. Strength Training: For Overall Fitness

    MedlinePlus

    Healthy Lifestyle Fitness Strength training is an important part of an overall fitness program. Here's what strength training can do for ... is a key component of overall health and fitness for everyone. Lean muscle mass naturally diminishes with ...

  4. Claudin-4 forms a paracellular barrier, revealing the interdependence of claudin expression in the loose epithelial cell culture model opossum kidney cells.

    PubMed

    Borovac, Jelena; Barker, Reid S; Rievaj, Juraj; Rasmussen, Andrew; Pan, Wanling; Wevrick, Rachel; Alexander, R Todd

    2012-12-15

    The effect of claudins on paracellular fluxes has been predominantly studied in either Madin-Darby canine kidney (MDCK) or LLCPK cells. Neither model system has a very low transepithelial resistance (TER) as observed in leaky epithelia. Moreover, results from one model system are not always consistent with another. Opossum kidney (OK) cells form tight junctions yet have a very low TER. We therefore set out to characterize the paracellular transport properties of this cell culture model. Ussing chamber dilution potential measurements revealed that OK cells exhibit a very low TER (11.7 ± 1.4 Ω·cm(2)), slight cation selectivity (P(Na)/P(Cl) = 1.10 ± 0.01), and the Eisenman permeability sequence IV; the permeability of monovalent cations ranking K(+) > Cs(+) > Rb(+) > Na(+) > Li(+). Quantitative real-time PCR studies found that OK cells endogenously express claudin-4 > -1 > -6 > -20 > -9 > -12 > -11 > -15. Overexpression of claudin-4 significantly increased TER, decreased Na(+) and Cl(-) permeability, and increased levels of claudin-1, -6, and -9 mRNA. Knockdown of claudin-4 in the overexpressing cells significantly decreased TER without altering claudin expression; thus claudin-4 forms a barrier in OK cells. Knockdown of endogenous claudin-4 decreased claudin-1, -9, and -12 expression without altering TER. Claudin-2 overexpression decreased TER, significantly increased Na(+) and Cl(-) permeability, and decreased claudin-12 and -6 expression. Together these results demonstrate that claudin expression is tightly coupled in OK cells.

  5. Strength Training and Children's Health.

    ERIC Educational Resources Information Center

    Faigenbaum, Avery D.

    2001-01-01

    Provides an overview of the potential health benefits of strength training for children, discussing the role of strength training in preventing sports-related injuries and highlighting design considerations for such programs. The focus is on musculoskeletal adaptations to strength training that are observable in healthy children. Guidelines for…

  6. Strength Development for Young Adolescents

    ERIC Educational Resources Information Center

    McDaniel, Larry W.; Jackson, Allen; Gaudet, Laura

    2009-01-01

    Participation in strength training is important for older children or young adolescences who wish to improve fitness or participate in sports. When designing strength training programs for our youth this age group is immature anatomically, physiologically, and psychologically. For the younger or inexperienced group the strength training activities…

  7. Strength of Rewelded Inconel 718

    NASA Technical Reports Server (NTRS)

    Bayless, E.; Lovoy, C. V.; Mcllwain, M. C.; Munafo, P.

    1982-01-01

    Inconel 718, nickel-based alloy used extensively for high-temperature structural service, welded repeatedly without detriment to its strength. According to NASA report, tests show 12 repairs on same weld joint do not adversely affect ultimate tensile strenth, yield strength, fatigue strength, metallurgical grain structures, or ability of weld joint to respond to post weld heat treatments.

  8. The fracture strength and frictional strength of Weber Sandstone

    USGS Publications Warehouse

    Byerlee, J.D.

    1975-01-01

    The fracture strength and frictional strength of Weber Sandstone have been measured as a function of confining pressure and pore pressure. Both the fracture strength and the frictional strength obey the law of effective stress, that is, the strength is determined not by the confining pressure alone but by the difference between the confining pressure and the pore pressure. The fracture strength of the rock varies by as much as 20 per cent depending on the cement between the grains, but the frictional strength is independent of lithology. Over the range 0 2 kb, ??=0??5 + 0??6??n. This relationship also holds for other rocks such as gabbro, dunite, serpentinite, granite and limestone. ?? 1975.

  9. Failure strength of icy lithospheres

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Banerdt, W. B.

    1987-01-01

    Lithospheric strengths derived from friction on pre-existing fractures and ductile flow laws show that the tensile strength of intact ice under applicable conditions is actually an order of magnitude stronger than widely assumed. It is demonstrated that this strength is everywhere greater than that required to initiate frictional sliding on pre-existing fractures and faults. Because the tensile strength of intact ice increases markedly with confining pressure, it actually exceeds the frictional strength at all depths. Thus, icy lithospheres will fail by frictional slip along pre-existing fractures at yeild stresses greater than previously assumed rather than opening tensile cracks in intact ice.

  10. Permanent magnet multipole with adjustable strength

    DOEpatents

    Halbach, Klaus

    1985-01-01

    Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling therebetween. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.

  11. Permanent-magnet multipole with adjustable strength

    DOEpatents

    Halbach, K.

    1982-09-20

    Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling there between. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.

  12. High strength ferritic alloy

    DOEpatents

    Hagel, William C.; Smidt, Frederick A.; Korenko, Michael K.

    1977-01-01

    A high-strength ferritic alloy useful for fast reactor duct and cladding applications where an iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8% by weight niobium, from about 0.1% to about 0.3% by weight vanadium, from about 0.2% to about 0.8% by weight silicon, from about 0.2% to about 0.8% by weight manganese, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight sulfur, a maximum of about 0.02% by weight phosphorous, and from about 0.04% to about 0.12% by weight carbon.

  13. Electric-field and magnetic-field sensors

    NASA Astrophysics Data System (ADS)

    Wieckowski, T. W.

    1993-05-01

    Analysis of double-loaded loop antennas and their properties has led to the design of new measuring sensors which enable has led to determination of both electric field strength and magnetic field strength. Sensors of the design proposed are applicable to a quasipoint measurement providing independent determination of the electric and magnetic component of the field.

  14. High strength and high toughness steel

    DOEpatents

    Parker, Earl R.; Zackay, Victor F.

    1979-01-01

    A structural steel which possess both high strength and high toughness and has particular application of cryogenic uses. The steel is produced by the utilization of thermally induced phase transformation following heating in a three-phase field in iron-rich alloys of the Fe-Ni-Ti system, with a preferred composition of 12% nickel, 0.5% titanium, the remainder being iron.

  15. Fault Roughness Records Strength

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Candela, T.; Kirkpatrick, J. D.

    2014-12-01

    Fault roughness is commonly ~0.1-1% at the outcrop exposure scale. More mature faults are smoother than less mature ones, but the overall range of roughness is surprisingly limited which suggests dynamic control. In addition, the power spectra of many exposed fault surfaces follow a single power law over scales from millimeters to 10's of meters. This is another surprising observation as distinct structures such as slickenlines and mullions are clearly visible on the same surfaces at well-defined scales. We can reconcile both observations by suggesting that the roughness of fault surfaces is controlled by the maximum strain that can be supported elastically in the wallrock. If the fault surface topography requires more than 0.1-1% strain, it fails. Invoking wallrock strength explains two additional observations on the Corona Heights fault for which we have extensive roughness data. Firstly, the surface is isotropic below a scale of 30 microns and has grooves at larger scales. Samples from at least three other faults (Dixie Valley, Mount St. Helens and San Andreas) also are isotropic at scales below 10's of microns. If grooves can only persist when the walls of the grooves have a sufficiently low slope to maintain the shape, this scale of isotropy can be predicted based on the measured slip perpendicular roughness data. The observed 30 micron scale at Corona Heights is consistent with an elastic strain of 0.01 estimated from the observed slip perpendicular roughness with a Hurst exponent of 0.8. The second observation at Corona Heights is that slickenlines are not deflected around meter-scale mullions. Yielding of these mullions at centimeter to meter scale is predicted from the slip parallel roughness as measured here. The success of the strain criterion for Corona Heights supports it as the appropriate control on fault roughness. Micromechanically, the criterion implies that failure of the fault surface is a continual process during slip. Macroscopically, the

  16. Wheelchair armrest strength testing.

    PubMed

    Cooper, R A; Rentschler, A J; O'Connor, T J; Ster, J F

    2000-01-01

    There are about 1.4 million manual wheelchair users, 100,000 electric-powered wheelchair users, and 60,000 electric-powered scooter users. The current study was undertaken to determine if the fasteners of a clamp-type armrest receiver were prone to failure. The first test was used to examine the potential misalignment of the armrest receiver components that attach it to the frame. The second test was to evaluate the entire armrest using the American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America armrest static strength standard. Finally, we conducted three fatigue tests. The first fatigue test was performed by repeating the static stability tests multiple times. The last two tests were a modified version of the double-drum wheelchair fatigue test used to apply repeated loading and vibration simultaneously. A paired t-test showed that there is no statistically significant difference (p = 0.08), with a confidence of 95%, between critical alignment measurements. The armrest including the receiver passed the standard requirement of a force of 760 N being applied outward at 15 degrees. During fatigue testing, we found that armrests did not exhibit any visible or functional damage. Upon completion of the tests, the armrests and receivers functioned properly. At about 100,289 cycles on a double-drum test machine, three bolts failed on each armrest receiver when the screws were loosened to have only five threads engaged prior to commencing the test. The design of the armrest tested was in compliance with existing national and international standards. Currently, both International Standards Organization and American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society committees are developing standards for seating systems that will include static, impact, and fatigue strength testing of devices like lateral torso supports, lateral hip support, etc. Methods similar to those

  17. Investigation of Vacuum Insulator Surface Dielectric Strength with Nanosecond Pulses

    SciTech Connect

    Nunnally, W C; Krogh, M; Williams, C; Trimble, D; Sampayan, S; Caporaso, G

    2003-06-03

    The maximum vacuum insulator surface dielectric strength determines the acceleration electric field gradient possible in a short pulse accelerator. Previous work has indicated that higher electric field strengths along the insulator-vacuum interface might be obtained as the pulse duration is decreased. In this work, a 250 kV, single ns wide impulse source was applied to small diameter, segmented insulators samples in a vacuum to evaluate the multi-layer surface dielectric strength of the sample construction. Resonances in the low inductance test geometry were used to obtain unipolar, pulsed electric fields in excess of 100 MV/m on the insulator surface. The sample construction, experimental arrangement and experimental results are presented for the initial data in this work. Modeling of the multi-layer structure is discussed and methods of improving insulator surface dielectric strength in a vacuum are proposed.

  18. Strength of Chemical Bonds

    NASA Technical Reports Server (NTRS)

    Christian, Jerry D.

    1973-01-01

    Students are not generally made aware of the extraordinary magnitude of the strengths of chemical bonds in terms of the forces required to pull them apart. Molecular bonds are usually considered in terms of the energies required to break them, and we are not astonished at the values encountered. For example, the Cl2 bond energy, 57.00 kcal/mole, amounts to only 9.46 x 10(sup -20) cal/molecule, a very small amount of energy, indeed, and impossible to measure directly. However, the forces involved in realizing the energy when breaking the bond operate over a very small distance, only 2.94 A, and, thus, f(sub ave) approx. equals De/(r - r(sub e)) must be very large. The forces involved in dissociating the molecule are discussed in the following. In consideration of average forces, the molecule shall be assumed arbitrarily to be dissociated when the atoms are far enough separated so that the potential, relative to that of the infinitely separated atoms, is reduced by 99.5% from the potential of the molecule at the equilibrium bond length (r(sub e)) for Cl2 of 1.988 A this occurs at 4.928 A.

  19. On the strength of glasses

    PubMed Central

    Wisitsorasak, Apiwat; Wolynes, Peter G.

    2012-01-01

    The remarkable strength of glasses is examined using the random first order transition theory of the glass transition. The theory predicts that strength depends on elastic modulus but also on the configurational energy frozen in when the glass is prepared. The stress catalysis of cooperative rearrangements of the type responsible for the supercooled liquid’s high viscosity account quantitatively for the measured strength of a range of metallic glasses, silica, and a polymer glass. PMID:22988070

  20. Physiological Effects of Strength Training and Various Strength Training Devices.

    ERIC Educational Resources Information Center

    Wilmore, Jack H.

    Current knowledge in the area of muscle physiology is a basis for a discussion on strength training programs. It is now recognized that the expression of strength is related to, but not dependent upon, the size of the muscle and is probably more related to the ability to recruit more muscle fibers in the contraction, or to better synchronize their…

  1. Aluminum alloys with improved strength

    NASA Technical Reports Server (NTRS)

    Deiasi, R.; Adler, P.

    1975-01-01

    Mechanical strength and stress corrosion of new BAR and 7050 alloys that include Zn instead of Cr have been studied and compared with those of 7075 aluminum alloy. Added mechanical strength of new alloys is attributed to finer grain size of 5 to 8 micrometers, however, susceptibility to stress corrosion attack is increased.

  2. Strength Training for Young Athletes.

    ERIC Educational Resources Information Center

    Kraemer, William J.; Fleck, Steven J.

    This guide is designed to serve as a resource for developing strength training programs for children. Chapter 1 uses research findings to explain why strength training is appropriate for children. Chapter 2 explains some of the important physiological concepts involved in children's growth and development as they apply to developing strength…

  3. Strength properties of fly ash based controlled low strength materials.

    PubMed

    Türkel, S

    2007-08-25

    Controlled low strength material (CLSM) is a flowable mixture that can be used as a backfill material in place of compacted soils. Flowable fill requires no tamping or compaction to achieve its strength and typically has a load carrying capacity much higher than compacted soils, but it can still be excavated easily. The selection of CLSM type should be based on technical and economical considerations for specific applications. In this study, a mixture of high volume fly ash (FA), crushed limestone powder (filler) and a low percentage of pozzolana cement have been tried in different compositions. The amount of pozzolana cement was kept constant for all mixes as, 5% of fly ash weight. The amount of mixing water was chosen in order to provide optimum pumpability by determining the spreading ratio of CLSM mixtures using flow table method. The shear strength of the material is a measure of the materials ability to support imposed stresses on the material. The shear strength properties of CLSM mixtures have been investigated by a series of laboratory tests. The direct shear test procedure was applied for determining the strength parameters Phi (angle of shearing resistance) and C(h) (cohesion intercept) of the material. The test results indicated that CLSM mixtures have superior shear strength properties compared to compacted soils. Shear strength, cohesion intercept and angle of shearing resistance values of CLSM mixtures exceeded conventional soil materials' similar properties at 7 days. These parameters proved that CLSM mixtures are suitable materials for backfill applications.

  4. 47 CFR 80.753 - Signal strength requirements at the service area contour.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Signal strength requirements at the service... Station VHF Coverage § 80.753 Signal strength requirements at the service area contour. (a) The requirements for reception by a marine VHF shipboard receiver are satisfied if the field strength from...

  5. What Are Electromagnetic Fields?

    MedlinePlus

    ... will generate a single big wave; more rapid motion will generate a whole series of small waves. ... are hardly detectable. Magnetic fields arise from the motion of electric charges. The strength of the magnetic ...

  6. High-strength concrete for Peacekeeper facilities

    NASA Astrophysics Data System (ADS)

    Saucier, K. L.

    1984-03-01

    An investigation is described which was conducted to determine the processes and techniques required to produce portland-cement concrete with a compressive strength of 15,000 psi or greater using conventional concreting methods and equipment, and to develop physical property data on the mixtures. It was permitted that special materials and admixtures be used, but a requirement was set that the aggregates and cements be selected from those available in the Cheyenne, Wyoming, area. Results indicated that it is feasible to achieve the 15,000-psi compressive strengths but that workability may decrease over a 2-hour period, and this latter development should be studied under job conditions. It is recommended that: (1) all materials and procedures to be used on a specific project be tested in the laboratory for basic property information, and (2) selected mixtures be tested in the field under expected environmental conditions prior to actual job use.

  7. "The strength of Nebraska": Boyd Epley, Husker Power, and the formation of the strength coaching profession.

    PubMed

    Shurley, Jason P; Todd, Jan S

    2012-12-01

    Boyd Epley was hired as the first full-time strength and conditioning coach at the University of Nebraska in 1969. Epley's hiring was the result of his extensive knowledge of strength training, an injury, and several disappointing seasons for the Cornhusker football team. An enterprising young coach, Tom Osborne, recognized that injured football players who trained with Epley, then an injured varsity pole-vaulter, returned to the team stronger than when they left. Osborne and Epley were able to convince head football coach and athletic director, Bob Devaney, that his belief that weight training was detrimental to athletic performance was unfounded. After starting the Husker Power program, Epley consistently worked to make it more scientific and specific to the demands of football. The results of Epley's work speak for themselves, over a career that spanned 35 years, football teams under his tutelage recorded 356 wins, 5 national championships, and a host of national player of the year award winners. In addition to his work as a practitioner of strength and conditioning, Epley also played an integral role in organizing a disparate group of individuals into a recognizable profession. He was the driving force in founding the National Strength and Conditioning Association in 1978. The organization would go on to fund and disseminate research in the field, resulting in the highly skilled practitioners of strength and conditioning practicing today.

  8. Oscillator strengths and collision strengths for S v

    NASA Technical Reports Server (NTRS)

    Van Wyngaarden, W. L.; Henry, R. J. W.

    1981-01-01

    Observations of the optical extreme-ultraviolet spectrum of the Jupiter planetary system during the Voyager space mission revealed bright emission lines of some sulfur ions. The spectra of the torus at the orbit of Io are likely to contain S V lines. The described investigation provides oscillator strengths and collision strengths for the first four UV lines. The collision strengths from the ground state to four other excited states are also obtained. Use is made of a two-state calculation which is checked for convergence for some transitions by employing a three-state or a four-state approximation. Target wave functions for S V are calculated so that the oscillator strengths calculated in dipole length and dipole velocity approximations agree within 5%.

  9. Strength Matters: Resisting Erosion Across Upland Landscapes

    NASA Astrophysics Data System (ADS)

    Heimsath, A. M.

    2012-12-01

    Soil-covered upland landscapes comprise a critical part of the habitable world and our understanding of their evolution as a function of different climatic, tectonic, and geologic regimes is important across a wide range of disciplines. Erosion laws, which help direct our study and drive our models of Earth surface processes are based on little field data. Soil production and transport play essential roles in controlling the spatial variation of soil depth and therefore hillslope hydrological processes, vegetation, and soil biological activity. Field-based confirmation of the hypothesized relationship between soil thickness and soil production is recent, however, and here we quantify the first direct physical explanation of variable soil production across landscapes. We report clear empirical linkages between the mechanical strength of the parent material (erodability), soil production rates determined from the same material, and the routing of water on hillslopes. Specifically, soil production rates determined from in situ produced 10Be and 26Al decrease exponentially with increasing shear strength of parent material across three very different field sites, all underlain by granitic bedrock: The Point Reyes Peninsular and The San Gabriel Mountains in California and the Nunnock River, Australia field site used for extensive previous work. At the same field sites, we use fallout radionuclide profiles to show how the flux of water across the soil-saprolite boundary changes significantly along the hillslope profile. Specifically, we quantify the transition from creep dominated bioturbation on the upper parts of the hillslopes to overland flow dominated surficial erosion towards the axis of the unchannelled swales. Our field-based data, collected across a full range of erosion and soil production rates and topographic settings, help explain more clearly the linkages between biota, weathering, hillslope hydrology, and the evolution of the Earth's surface.

  10. Mechanical strength of porous silicon and its possible applications

    NASA Astrophysics Data System (ADS)

    Klyshko, A.; Balucani, M.; Ferrari, A.

    2008-10-01

    Porous silicon has various fields of application. Its electrical and optical properties are under study since many years, and it is also known that porosity has a considerable effect on the mechanical properties (i.e. hardness, compressive strength, elasticity, breaking strength). In the present paper a novel technique for preparing samples of porous silicon in order to measure the breaking strength of PS is presented. The technique is based on wet corrosion deposition of copper and creating a meniscus shaped porous silicon. Results of the measurements of PS with different porosity and structure of pores made on p+ and n+ material are presented. Possible applications of the data are discussed.

  11. The Pavlovian "principle of strength".

    PubMed

    Windholz, G

    1995-01-01

    The Pavlovian principle of strength assumed that the magnitude of the conditional response is a linear function of the intensity of the external conditional stimulus. But experiments failed to provide evidence for the universality of the principle. The Pavlovians tried to identify conditions that distorted the linearity of this relationship. Some of the disturbing conditions were external and some were internal intervening variables. It is possible that the relation between the strength of the conditional stimulus and the magnitude of the conditional response is not linear but logarithmic. Pavlov acknowledged the lack of experimental evidence to support the principle of strength in its original form.

  12. Strength Training and Your Child

    MedlinePlus

    ... considering strength-training programs: An instructor-to-child ratio of no more than 1 to 10. The ... major muscle groups of the upper and lower body and core. Kids should start with no load ( ...

  13. Machine Gun Liner Bond Strength

    DTIC Science & Technology

    2007-08-01

    investigation does not constitute a complete analysis of liner failures in the M2 machine gun. The fact that two different liner-failure modes were...An order-of-magnitude estimate can be made of the bond strength in this case using a standard elastic analysis and some reasonable assumptions... analysis of the forces on the machine gun bullet, it was found that the measured bond strength was adequate to resist the reaction forces produced when

  14. Strong transverse fields in delta-spots

    NASA Technical Reports Server (NTRS)

    Zirin, Harold; Wang, Haimin

    1993-01-01

    Spectroscopic measurements of the strength and direction of transverse magnetic fields in six delta-spots are presented. The field direction is determined by the relative strength of the pi- and sigma-components at different polarizer orientations, and is, with one exception, parallel to the neutral line and as strong as the umbral field. Field strengths determined by line splitting are as high as 3980 G.

  15. Dielectric strength of irradiated fiber reinforced plastics

    NASA Astrophysics Data System (ADS)

    Humer, Karl; Weber, Harald W.; Hastik, Ronald; Hauser, Hans; Gerstenberg, Heiko

    2001-05-01

    The insulation system for the toroidal field model coil of international thermonuclear experimental reactor is a fiber reinforced plastic (FRP) laminate, which consists of a combined Kapton/R-glass-fiber reinforcement tape, vacuum-impregnated with an epoxy DGEBA system. Pure disk-shaped laminates, disk-shaped FRP/stainless-steel sandwiches, and conductor insulation prototypes were irradiated at 5 K in a fission reactor up to a fast neutron fluence of 10 22 m -2 ( E>0.1 MeV) to investigate the radiation induced degradation of the dielectric strength of the insulation system. After warm-up to room temperature, swelling, weight loss, and the breakdown strength were measured at 77 K. The sandwich swells by 4% at a fluence of 5×10 21 m -2 and by 9% at 1×10 22 m -2. The weight loss of the FRP is 2% at 1×10 22 m -2. The dielectric strength remained unchanged over the whole dose range.

  16. Mechanical behavior and strength in spalled copper

    NASA Astrophysics Data System (ADS)

    Vachhani, Shraddha J.; Trujillo, Carl P.; Potocki, Mark L.; Martinez, Daniel T.; Lovato, Manuel L.; Gray, George T.; Cerreta, Ellen K.

    2017-01-01

    The bulk compressive and tensile response of samples machined from the different regions of dynamically damaged OFHC copper is examined in combination with post-mortem analysis of the recovered sample. This was done using optical microscopy and electron back-scatter diffraction to understand the strength and mechanical behavior of a material deformed under dynamic loading conditions. Stored plastic work in the shocked samples produced significant hardening in all the samples. It was also observed that the samples containing a dynamically induced damage field were slightly harder and showed enhanced yield strength over material simply subjected to shock and release that showed no dynamic damage. This was attributed to the excess work hardening around voids induced during incipient spall. By comparing the responses of two specimens with differing amounts of dynamic damage, it was concluded that there appears to be a limit to the amount of dynamic damage, after which the enhanced yield strength in the material with dynamic damage will cease to exist.

  17. Strength measurements of The Geysers reservoir rock

    SciTech Connect

    Lockner, D.A.; Byerlee, J.D.

    1980-09-01

    Rock samples taken from two outcrops and cores from well bores at the Geysers geothermal field were tested at temperatures and pressures similar to those found in the field. Both intact cylinders and cylinders containing 30/sup 0/ sawcuts were deformed at confining pressures of 200 to 1000 bars, pore pressure of 30 bars, and temperatures of 150 to 250/sup 0/C. Constant strain rate tests gave a coefficient of friction of 0.68. Friction was independent of rock type, temperature and strain rate. Most cores taken from the producing zone were highly fractured. For this reason, intact samples were rarely 50% stronger than the frictional strength. At 500 bars confining pressure, P wave velocity of 6.2 km/sec was measured for a sample taken from an outcrop. Porosities and permeabilities were also measured.

  18. Lifting strength in two-person teamwork.

    PubMed

    Lee, Tzu-Hsien

    2016-01-01

    This study examined the effects of lifting range, hand-to-toe distance, and lifting direction on single-person lifting strengths and two-person teamwork lifting strengths. Six healthy males and seven healthy females participated in this study. Two-person teamwork lifting strengths were examined in both strength-matched and strength-unmatched groups. Our results showed that lifting strength significantly decreased with increasing lifting range or hand-to-toe distance. However, lifting strengths were not affected by lifting direction. Teamwork lifting strength did not conform to the law of additivity for both strength-matched and strength-unmatched groups. In general, teamwork lifting strength was dictated by the weaker of the two members, implying that weaker members might be exposed to a higher potential danger in teamwork exertions. To avoid such overexertion in teamwork, members with significantly different strength ability should not be assigned to the same team.

  19. Crystal strength by direct computation

    NASA Astrophysics Data System (ADS)

    Bulatov, Vasily

    2007-03-01

    The art of making materials stronger goes back to medieval and even ancient times. Swords forged from Damascus steels more than 10 centuries ago possessed a unique combination of hardness and flexibility, two qualities that are difficult to attain simultaneously. The skills of metalworking were based on empirical knowledge and were passed from the master smith to his pupils. The science of physical metallurgy came about only in the XX century bringing with it new methods for finding out why some materials are strong while others are not. Soon it was realized that, when it comes to metal strength, it is all about crystal defects -- impurities, dislocations, grain boundaries, etc. - and how they are organized into crystal microstructure. This understanding has since resulted in new effective methods of material processing aiming to modify crystal microstructure in order to affect material's properties, e.g. strength and/or hardness. Remarkably and disappointingly, general understanding that microstructure defines material's response to external loads has not yet resulted in a workable physical theory of metal strength accounting for the realistic complexity of material microstructure. In this presentation I would like to discuss a few tidbits from computational and experimental research in our group at LLNL on crystal defects and their contributions to material strength. My selection of the examples aims to illustrate the major premise of our work that the mechanisms by which the microstructure affects crystal strength are multiple and complex but that there is hope to bring some order to this complexity.

  20. Triaxial determination of shear strength of tire chips

    SciTech Connect

    Wu, W.Y.; Benda, C.C.; Cauley, R.F.

    1997-05-01

    Triaxial compression tests following stress paths of constant {sigma}{sub 1} were conducted to determine the shear strength of five processed scrap tire products having different gradations and particle shapes. The interparticle frictional component was separated from the total shear strength according to the energy correction concept proposed by researchers. The experimental results show that all five tire chip products have ultimate internal friction angles of 45{degree} to over 60{degree}. The interparticle frictional component of the strength was fully mobilized and nearly reached a constant value after approximately 5% axial strain. The experimental results confirmed that the strength parameter obtained with constant {sigma}{sub 1} was more reasonable. This finding is supported by field observation in which the tire chips have an angle of repose ranging from 37{degree} to 43{degree} (loosely stock piled) and up to 85{degree} (compacted). The engineering applications of the experimental results are discussed.

  1. Strong Magnetic Field Characterisation

    DTIC Science & Technology

    2012-04-01

    coils were driven by a pulsed-power system to generate the fields. All the sources were characterised through a series of measurements and modelling... generated for the coils. Options for further investigation were provided. UNCLASSIFIED UNCLASSIFIED This...investigation. The desired field strength was based on assessments [1] from preliminary magnetohydrodynamic ( MHD ) modelling and while not achievable by

  2. Topological strength of magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Bazeia, D.; Ramos, J. G. G. S.; Rodrigues, E. I. B.

    2017-02-01

    This work deals with magnetic structures that attain integer and half-integer skyrmion numbers. We model and solve the problem analytically, and show how the solutions appear in materials that engender distinct, very specific physical properties, and use them to describe their topological features. In particular, we found a way to model skyrmion with a large transition region correlated with the presence of a two-peak skyrmion number density. Moreover, we run into the issue concerning the topological strength of a vortex-like structure and suggest an experimental realization, important to decide how to modify and measure the topological strength of the magnetic structure.

  3. Compressive strength of continuous fiber unidirectional composites

    NASA Astrophysics Data System (ADS)

    Thompson, Ronald H.

    Dow and Rosen's work in 1965 formed an intellectual framework for compressive strength of unidirectional composites. Compressive strength was explained in terms of micro-buckling, in which filaments are beams on an elastic foundation. They made simplifying assumptions, with a two dimensional idealization and linearized material properties. This study builds on their model, recognizing that the shear mode of instability drives unidirectional compressive strength. As a necessary corollary, the predictive methods developed in this study emphasize correct representation of composite shear stiffness. Non-linear effects related to matrix material properties, fiber misalignment, three dimensional representation, and thermal prestrains are taken into account. Four work streams comprise this study: first, development of a closed form analytical model; second, empirical methods development and model validation; third, creation and validation of a unit cell finite element model; and fourth, a patent application that leverages knowledge gained from the first three work streams. The analytical model characterizes the non-linearity of the matrix both with respect to shear and compressive loading. This improvement on existing analyses clearly shows why fiber modulus affects composite shear instability. Accounting for fiber misalignment in the model and experimental characterization of the fiber misalignment continuum are important contributions of this study. A simple method of compressive strength measurement of a small diameter monofilament glass-resin composite is developed. Sample definition and preparation are original, and necessary technologies are easily assessable to other researchers in this field. This study shows that glass fiber composites have the potential for high compressive strength. This potential is reached with excellent fiber alignment and suitable matrix characteristics, and results are consistent with model predictions. The unit cell three dimensional

  4. In-situ Rock Spalling Strength near Excavation Boundaries

    NASA Astrophysics Data System (ADS)

    Cai, M.; Kaiser, P. K.

    2014-03-01

    It is widely accepted that the in-situ strength of massive rocks is approximately 0.4 ± 0.1 UCS, where UCS is the uniaxial compressive strength obtained from unconfined tests using diamond drilling core samples with a diameter around 50 mm. In addition, it has been suggested that the in-situ rock spalling strength, i.e., the strength of the wall of an excavation when spalling initiates, can be set to the crack initiation stress determined from laboratory tests or field microseismic monitoring. These findings were supported by back-analysis of case histories where failure had been carefully documented, using either Kirsch's solution (with approximated circular tunnel geometry and hence σ max = 3σ 1 -σ 3) or simplified numerical stress modeling (with a smooth tunnel wall boundary) to approximate the maximum tangential stress σ max at the excavation boundary. The ratio of σ max /UCS is related to the observed depth of failure and failure initiation occurs when σ max is roughly equal to 0.4 ± 0.1 UCS. In this article, it is suggested that these approaches ignore one of the most important factors, the irregularity of the excavation boundary, when interpreting the in-situ rock strength. It is demonstrated that the "actual" in-situ spalling strength of massive rocks is not equal to 0.4 ± 0.1 UCS, but can be as high as 0.8 ± 0.05 UCS when surface irregularities are considered. It is demonstrated using the Mine-by tunnel notch breakout example that when the realistic "as-built" excavation boundary condition is honored, the "actual" in-situ rock strength, given by 0.8 UCS, can be applied to simulate progressive brittle rock failure process satisfactorily. The interpreted, reduced in-situ rock strength of 0.4 ± 0.1 UCS without considering geometry irregularity is therefore only an "apparent" rock strength.

  5. An interlaminar tension strength specimen

    NASA Technical Reports Server (NTRS)

    Jackson, Wade C.; Martin, Roderick H.

    1992-01-01

    This paper describes a technique to determine interlaminar tension strength, sigma(sub 3c) of a fiber reinforced composite material using a curved beam. The specimen was a unidirectional curved beam, bent 90 degrees, with straight arms. Attached to each arm was a hinged loading mechanism which was held by the grips of a tensile testing machine. Geometry effects of the specimen, including the effects of loading arm length, inner radius, thickness, and width, were studied. The data sets fell into two categories: low strength corresponding to a macroscopic flaw related failure and high strength corresponding to a microscopic flaw related failure. From the data available, the loading arm length had no effect on sigma(sub 3c). The inner radius was not expected to have a significant effect on sigma(sub 3c), but this conclusion could not be confirmed because of differences in laminate quality for each curve geometry. The thicker specimens had the lowest value of sigma(sub 3c) because of poor laminate quality. Width was found to affect the value of sigma(sub 3c) only slightly. The wider specimens generally had a slightly lower strength since more material was under high stress, and hence, had a larger probability of containing a significant flaw.

  6. Modeling of Sylgard Adhesive Strength

    SciTech Connect

    Stevens, Ralph Robert

    2015-02-03

    Sylgard is the name of a silicone elastomeric potting material manufactured by Dow Corning Corporation.1 Although the manufacturer cites its low adhesive strength as a feature of this product, thin layers of Sylgard do in fact have a non-negligible strength, which has been measured in recent tensile and shear debonding tests. The adhesive strength of thin layers of Sylgard potting material can be important in applications in which components having signi cantly di erent thermal expansion properties are potted together, and the potted assembly is subjected to temperature changes. The tensile and shear tractions developed on the potted surfaces of the components can cause signi cant internal stresses, particularly for components made of low-strength materials with a high area-to-volume ratio. This report is organized as follows: recent Sylgard debonding tests are rst brie y summarized, with particular attention to the adhesion between Sylgard and PBX 9501, and also between Sylgard and aluminum. Next, the type of numerical model that will be used to simulate the debonding behavior exhibited in these tests is described. Then the calibration of the debonding model will be illustrated. Finally, the method by which the model parameters are adjusted (scaled) to be applicable to other, non- tested bond thicknesses is summarized, and all parameters of the model (scaled and unscaled) are presented so that other investigators can reproduce all of the simulations described in this report as well as simulations of the application of interest.

  7. A NEW CLINICAL MUSCLE FUNCTION TEST FOR ASSESSMENT OF HIP EXTERNAL ROTATION STRENGTH: AUGUSTSSON STRENGTH TEST

    PubMed Central

    2016-01-01

    external rotation strength in patients, non–athletes and athletes. The test is practical and easy to perform in any setting and could therefore provide additional information to the common clinical hip examination, in the rehabilitation or research setting, as well as when conducting on–the–field testing in sports. Level of evidence 3 PMID:27525176

  8. Determining the Strength of an Electromagnet through Damped Oscillations

    ERIC Educational Resources Information Center

    Thompson, Michael; Leung, Chi Fan

    2011-01-01

    This article describes a project designed to extend sixth-form pupils looking to further their knowledge and skill base in physics. This project involves a quantitative analysis of the decaying amplitude of a metal plate oscillating in a strong magnetic field; the decay of the amplitude is used to make estimates of the strength of the magnetic…

  9. Static Dielectric Breakdown Strength of Condensed Heterogeneous High Explosives

    DTIC Science & Technology

    1987-06-01

    3-1 TRIPLE JUNCTION . . .. . . . . . . . . . . . . . . . * * * .3-2 SURFACE FLASHOVER ...enhancement at dielectric interfaces, surface flashover , humidity, surrounding atmosphere, temperature, pressure, and excitation time), which are...discussed in Chapter 3. To obtain meaningful critical field strengths, it is necessary to suppress surface flashover around the insulator sides and

  10. The Strength-Based Counseling Model

    ERIC Educational Resources Information Center

    Smith, Elsie J.

    2006-01-01

    This article proposes a strength-based model for counseling at-risk youth. The author presents the assumptions, basic concepts, and values of the strength perspective in counseling and offers strength categories as a conceptual model for viewing clients' behavior. Propositions leading toward a theory of strength-based counseling and stages of this…

  11. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... product is a number greater than 15. (iii) A rectangular grid, of such size and shape as to encompass the... the grid included within the boundaries of the community shall be at least equal to the required..., buildings and other structures. The orientation, with respect to the measuring location shall be...

  12. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... (v) A mobile run of at least 30 meters is made, that is centered on the intersection of the radial... strongest signal is found to come from a direction other than from the transmitter, after the mobile run... and recorded. Generally, all points should be within 60 meters of the center point of the mobile...

  13. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... (v) A mobile run of at least 30 meters is made, that is centered on the intersection of the radial... strongest signal is found to come from a direction other than from the transmitter, after the mobile run... and recorded. Generally, all points should be within 60 meters of the center point of the mobile...

  14. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... network in question that are located in the same Nielsen Designated Market Area (DMA) as the test site may..., such as topography, height and types of vegetation, buildings, obstacles, weather, and other local.... Census tables of population of cities and urbanized areas. (ii) The number of locations at...

  15. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) Multiple signals. If more than one signal is being measured (i.e., signals from different transmitters... the measurement. (iii) Multiple signals— (A) If more than one signal is being measured (i.e., signals... eligibility of a satellite subscriber to receive distant network signals, only stations affiliated with...

  16. The Earth's Magnetic Field: A Simple Measurement of Its Strength

    ERIC Educational Resources Information Center

    Chamberlain, William G., III

    1978-01-01

    This laboratory exercise for junior or senior high school students forms a basis for expansion of concepts, offers opportunities for analytical thinking, and presents possibilities for independent thinking. (BB)

  17. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... transmitting antenna. (B) Ground elevation at measuring location. (C) Date, time of day, and weather. (D... measurements were made, drawn on curved earth paper for equivalent 4/3 earth radius, of the largest...

  18. Fracture strength and adhesive strength of hydroxyapatite-filled polycaprolactone.

    PubMed

    Wong, Shing-Chung; Baji, Avinash

    2008-02-01

    Fracture toughness and tear strength of hydroxyapatite (HAP)-filled poly(epsilon-caprolactone) (PCL) with increasing HAP concentration were studied. The toughness was assessed in terms of essential work of fracture (EWF). Adhesive strength between HAP and PCL interfaces was evaluated using T-peel testing. The adhesion between the two components was found to be relatively strong. Double edge notched tension (DENT) and trousers test specimens were used for the EWF tests. The effect of HAP phase in PCL on the fracture and tearing toughness was investigated. The results obtained from the EWF tests for the HAP-filled PCL complied with the validity criteria of the EWF concept, namely, (1) geometric similarity for all ligament lengths; (2) fully yielded ligament and (3) plane-stress fracture condition. Values for specific essential work of fracture (w ( e )) and specific plastic work of fracture (betaw ( p )) were found to decrease with increase in HAP concentration. The testing procedure showed promise in quantifying the tearing resistance and rising R-curve behavior common in natural materials and it can be extended to other biomaterials that exhibit post-yield deformation. A quantitative assessment based on fracture mechanics of the adhesive strength between the bioactive interfaces plays an important role for continued development of tissue replacement and tissue regeneration materials.

  19. Pygmy Dipole Strength and Neutron Skins in Exotic Nuclei

    NASA Astrophysics Data System (ADS)

    Klimkiewicz, A.; Paar, N.; Adrich, P.; Fallot, M.; Boretzky, K.; Aumann, T.; Cortina-Gil, D.; Pramanik, U. Datta; Elze, Th. W.; Emling, H.; Geissel, H.; Hellström, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Nociforo, C.; Palit, R.; Simon, H.; Surówka, G.; Sümmerer, K.; Vretenar, D.; Waluś, W.

    2008-05-01

    Dipole strength distributions were determined for the neutron-rich nuclei 129-132Sn and 133,134Sb from electromagnetic excitation in an experiment using the FRS-LAND setup. For all nuclei, a sizeable fraction of ``pygmy'' dipole strength at excitation energies well below the giant dipole resonance was observed. The integrated low-lying dipole strength of the nuclei with low neutron separation energies can be compared to results for stable nuclei (e.g. N = 82 isotopes) determined for the energy regime of 5-9 MeV. A clear increase of the dipole strength with increasing asymmetry of the nuclei is observed. Comparing the ratio of the low-lying dipole over the giant dipole strength to recent relativistic mean field calculations, values for the parameters a4 and p0 of the symmetry energy and for the neutron skin thickness are derived. Averaged over 130Sn and 132Sn we extract a4 = 31.8+/-1.3 MeV and p0 = 2.2+/-0.5 MeV/fm3. The neutron skin sizes are determined to Rn-Rp = 0.23+/-0.03 fm and 0.24+/-0.03 fm for 130Sn and 132Sn, respectively. For 208Pb a neutron skin thickness of Rn-Rp = 0.18+/-0.035 fm follows, when applying the same method and using earlier published experimental findings on the dipole strength.

  20. Pore geometry as a control on rock strength

    NASA Astrophysics Data System (ADS)

    Bubeck, A.; Walker, R. J.; Healy, D.; Dobbs, M.; Holwell, D. A.

    2017-01-01

    The strength of rocks in the subsurface is critically important across the geosciences, with implications for fluid flow, mineralisation, seismicity, and the deep biosphere. Most studies of porous rock strength consider the scalar quantity of porosity, in which strength shows a broadly inverse relationship with total porosity, but pore shape is not explicitly defined. Here we use a combination of uniaxial compressive strength measurements of isotropic and anisotropic porous lava samples, and numerical modelling to consider the influence of pore shape on rock strength. Micro computed tomography (CT) shows that pores range from sub-spherical to elongate and flat ellipsoids. Samples that contain flat pores are weaker if compression is applied parallel to the short axis (i.e. across the minimum curvature), compared to compression applied parallel to the long axis (i.e. across the maximum curvature). Numerical models for elliptical pores show that compression applied across the minimum curvature results in relatively broad amplification of stress, compared to compression applied across the maximum curvature. Certain pore shapes may be relatively stable and remain open in the upper crust under a given remote stress field, while others are inherently weak. Quantifying the shape, orientations, and statistical distributions of pores is therefore a critical step in strength testing of rocks.

  1. 47 CFR 73.683 - Field strength contours and presumptive determination of field strength at individual locations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) If a location was predicted to be unserved by a local network station using a version of the ILLR... for satellite retransmission of distant network signals under the copyright law provisions of 17 U.S.C...) propagation prediction model. Such eligibility determinations shall consider only the signals of...

  2. 47 CFR 73.683 - Field strength contours and presumptive determination of field strength at individual locations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) If a location was predicted to be unserved by a local network station using a version of the ILLR... for satellite retransmission of distant network signals under the copyright law provisions of 17 U.S.C...) propagation prediction model. Such eligibility determinations shall consider only the signals of...

  3. Shear Strength of Aluminum Oxynitride

    NASA Astrophysics Data System (ADS)

    Dandekar, Dattatraya P.; Vaughan, Brian A. M.; Proud, William G.

    2007-06-01

    Aluminum oxynitride (AlON) is a transparent, polycrystalline cubic spinel. The results of investigations^1-4 on shock response of AlON permit determination of the equation of state, and shear strength retained under shock compression. Whereas the values of the HEL of AlON holds no surprises, the inelastic response of AlON reported in Ref. 1-4 differ significantly and is stress dependent. The results of Ref. 1-2 show that AlON retains a shear strength of 3 to 4 GPa when shocked up to around 20 GPa, but the results of Ref, 3-4 seem to suggest a possible loss of shear strength when shocked to 16 GPa and beyond. Our analysis examines the observed differences in the inelastic response of AlON reported in these four studies . 1. J. U. Cazamias, et. al., in Fundamental Issues and Applications of Shock-Wave and High Strain Rate Phenomena, Eds. Staudhammer, Murr, and Meyers, Elsevier, NY, 173 (2001). 2. B. A. M. Vaughn, et.al., Shock Physics, Cavendish Laboratory, Report SP/1092 (2001) 3. T. Sekine, et.al., J. Appl. Phys. 94, 4803 (2003). 4. T. F. Thornhill, et.al., Shock Compression of Matter-2005, Eds. Furnish, Elert, Russell, White, AIP, NY, 143 (2006).

  4. Bats respond to very weak magnetic fields.

    PubMed

    Tian, Lan-Xiang; Pan, Yong-Xin; Metzner, Walter; Zhang, Jin-Shuo; Zhang, Bing-Fang

    2015-01-01

    How animals, including mammals, can respond to and utilize the direction and intensity of the Earth's magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05). Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth's magnetic field strength varied and the polarity reversed tens of times over the past fifty million years.

  5. Enhanced long-term strength and durability of shotcrete with high-strength C{sub 12}A{sub 7} mineral-based accelerator

    SciTech Connect

    Won, Jong-Pil Hwang, Un-Jong; Lee, Su-Jin

    2015-10-15

    This study evaluated the performance of shotcrete using high strength C{sub 12}A{sub 7} mineral-based accelerator that has been developed to improve the durability and long-term strength. Rebound, compressive strength and flexural strength were tested in the field. Test result showed that existing C{sub 12}A{sub 7} mineral-based accelerator exhibits better early strength than the high-strength C{sub 12}A{sub 7} mineral-based accelerator until the early age, but high-strength C{sub 12}A{sub 7} mineral-based accelerator shows about 29% higher at the long-term age of 28 days. Microstructural analysis such as scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen adsorption method was evaluated to analyze long-term strength development mechanism of high strength C{sub 12}A{sub 7} mineral-based accelerator. As analysis result, it had more dense structure due to the reaction product by adding material that used to enhanced strength. It had better resistance performance in chloride ion penetration, freezing–thawing and carbonation than shotcrete that used existing C{sub 12}A{sub 7} mineral-based accelerator.

  6. Inert strength of pristine silica glass fibers

    SciTech Connect

    Smith, W.L.; Michalske, T.A.

    1993-11-01

    Silica glass fibers have been produced and tested under ultra high vacuum (UHV) conditions to investigate the inert strength of pristine fibers in absence of reactive agents. Analysis of the coefficient of variation in diameter ({upsilon}{sub d}) vs the coefficient of variation of breaking strength ({upsilon}{sub {sigma}}) does not adequately explain the variation of breaking stress. Distribution of fiber tensile strength data suggests that the inert strength of such fibers is not single valued and that the intrinsic strength is controlled by defects in the glass. Furthermore, comparison of room temperature UHV data with LN{sub 2} data indicates that these intrinsic strengths are not temperature dependent.

  7. Unbalanced field RF electron gun

    DOEpatents

    Hofler, Alicia

    2013-11-12

    A design for an RF electron gun having a gun cavity utilizing an unbalanced electric field arrangement. Essentially, the electric field in the first (partial) cell has higher field strength than the electric field in the second (full) cell of the electron gun. The accompanying method discloses the use of the unbalanced field arrangement in the operation of an RF electron gun in order to accelerate an electron beam.

  8. Strength Training and Shoulder Proprioception

    PubMed Central

    Salles, José Inácio; Velasques, Bruna; Cossich, Victor; Nicoliche, Eduardo; Ribeiro, Pedro; Amaral, Marcus Vinicius; Motta, Geraldo

    2015-01-01

    Context: Proprioception is essential to motor control and joint stability during daily and sport activities. Recent studies demonstrated that athletes have better joint position sense (JPS) when compared with controls matched for age, suggesting that physical training could have an effect on proprioception. Objective: To evaluate the result of an 8-week strength-training program on shoulder JPS and to verify whether using training intensities that are the same or divergent for the shoulder's dynamic-stabilizer muscles promote different effects on JPS. Design: Randomized controlled clinical trial. Setting: We evaluated JPS in a research laboratory and conducted training in a gymnasium. Patients or Other Participants: A total of 90 men, right handed and asymptomatic, with no history of any type of injury or shoulder instability. Intervention(s): For 8 weeks, the participants performed the strength-training program 3 sessions per week. We used 4 exercises (bench press, lat pull down, shoulder press, and seated row), with 2 sets each. Main Outcome Measure(s): We measured shoulder JPS acuity by calculating the absolute error. Results: We found an interaction between group and time. To examine the interaction, we conducted two 1-way analyses of variance comparing groups at each time. The groups did not differ at pretraining; however, a difference among groups was noted posttraining. Conclusions: Strength training using exercises at the same intensity produced an improvement in JPS compared with exercises of varying intensity, suggesting that the former resulted in improvements in the sensitivity of muscle spindles and, hence, better neuromuscular control in the shoulder. PMID:25594912

  9. Development of strength in cements

    NASA Astrophysics Data System (ADS)

    Matkovic, B.

    1981-04-01

    The production of doped belite (dicalcium silicate) clinkers as a prospective means for saving energy in Portland cement production is described. This is accomplished by small additions of either barium sulfate (BaSO4), calcium tribasic phosphate (Ca5(PO4)3OH), or vanadium oxide (V2O5) to belite (Ca2SiO4) clinker. In addition to conserving energy, doping the belite with barium sulfate imparts greater strength to the resulting modified belite. Reactants, additives, and factors contributing to the fabrication of Sorel cement are described.

  10. High strength, tough alloy steel

    DOEpatents

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  11. Pilates: Build Strength in Your Core Muscles

    MedlinePlus

    ... intimidating, but it's an accessible way to build strength in your core muscles for better posture, balance ... fanatics. It's actually an accessible way to build strength in your core muscles for better posture, balance ...

  12. Community-wide distribution of predator-prey interaction strength in kelp forests.

    PubMed

    Sala, Enric; Graham, Michael H

    2002-03-19

    The strength of interactions between predators and their prey (interaction strength) varies enormously among species within ecological communities. Understanding the community-wide distribution of interaction strengths is vital, given that communities dominated by weak interactions may be more stable and resistant to invasion. In the oceans, previous studies have reported log-normal distributions of per capita interaction strength. We estimated the distribution of predator-prey interaction strengths within a subtidal speciose herbivore community (45 species). Laboratory experiments were used to determine maximum per capita interaction strengths for eight species of herbivores (including amphipods, isopods, gastropods, and sea urchins) that graze on giant kelp (Macrocystis pyrifera) microscopic stages. We found that maximum per capita interaction strength saturated as a function of individual herbivore biomass, likely caused by predator/prey size thresholds. Incorporating this nonlinearity, we predicted maximum per capita interaction strength for the remaining herbivore species. The resulting distribution of per capita interaction strengths was bimodal, in striking contrast to previous reports from other communities. Although small herbivores often had per capita interaction strengths similar to larger herbivores, their tendency to have greater densities in the field increased their potential impact as grazers. These results indicate that previous conclusions about the distributions of interaction strength in natural communities are not general, and that intermediate-sized predators can under realistic circumstances represent the most effective consumers in natural communities.

  13. CADDIS Volume 2. Sources, Stressors and Responses: Ionic Strength

    EPA Pesticide Factsheets

    Introduction to the ionic strength module, when to list ionic strength as a candidate cause, ways to measure ionic strength, simple and detailed conceptual diagrams for ionic strength, ionic strength module references and literature reviews.

  14. Strength distribution in commercial silicon carbide materials

    NASA Technical Reports Server (NTRS)

    Dutta, Sunil

    1988-01-01

    Four-point flexural strength testing has been conducted in order to establish the baseline strength and reliability of four different commercial SiC types, in conjunction with reliable Weibull modulus values. Average strength of the samples ranged from 380 to 482 MPa at room temperature and 307 to 470 MPa at 1370 C. The strength scatter reflects the effect of flaw variability, which must be minimized to improve reliability in sintered SiC.

  15. Asteroid airburst altitude vs. strength

    NASA Astrophysics Data System (ADS)

    Robertson, Darrel; Wheeler, Lorien; Mathias, Donovan

    2016-10-01

    Small NEO asteroids (<Ø140m) may not be a threat on a national or global level but can still cause a significant amount of local damage as demonstrated by the Chelyabinsk event where there was over $33 million worth of damage (1 billion roubles) and 1500 were injured, mostly due to broken glass. The ground damage from a small asteroid depends strongly on the altitude at which they "burst" where most of the energy is deposited in the atmosphere. The ability to accurately predict ground damage is useful in determining appropriate evacuation or shelter plans and emergency management.Strong asteroids, such as a monolithic boulder, fail and create peak energy deposition close to the altitude at which ram dynamic pressure exceeds the material cohesive strength. Weaker asteroids, such as a rubble pile, structurally fail at higher altitude, but it requires the increased aerodynamic pressure at lower altitude to disrupt and disperse the rubble. Consequently the resulting airbursts have a peak energy deposition at similar altitudes.In this study hydrocode simulations of the entry and break-up of small asteroids were performed to examine the effect of strength, size, composition, entry angle, and speed on the resulting airburst. This presentation will show movies of the simulations, the results of peak burst height, and the comparison to semi-analytical models.

  16. The strength of Miranda's lithosphere

    NASA Technical Reports Server (NTRS)

    Pappalardo, Robert; Greeley, Ronald

    1991-01-01

    In attempting to understand the endogenic processes which have shaped the surface of an icy satellite, it is desirable to quantify the failure strength of the satellite's lithosphere. In a crust that is fractured on a large scale, frictional sliding along pre-existing fractures occurs in response to lower differential stresses than required to initiate fracture of pristine rock, thus governing failure of a brittle lithosphere. Failure is predicted along favorably oriented fracture planes; if fractures of all orientations are assumed to be present in the crust (as is expected of a heavily cratered lithosphere), frictional failure relations are directly applicable. The Coulomb criterion predicts that the shear stress (sigma sub t) and normal stress (sigma sub n) components on a fracture plane at failure are related as sigma sub t = mu-sigma sub n + S sub o, where S sub o is the cohesion and mu is the coefficient of friction. At moderate to high pressures, the frictional sliding strength of most materials is found to be sigma sub t = 0.85 sigma sub n.

  17. 14 CFR 31.27 - Strength.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Strength. 31.27 Section 31.27 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.27 Strength. (a) The structure must be able...

  18. 14 CFR 31.27 - Strength.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Strength. 31.27 Section 31.27 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.27 Strength. (a) The structure must be able...

  19. 14 CFR 31.27 - Strength.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Strength. 31.27 Section 31.27 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.27 Strength. (a) The structure must be able...

  20. Strengths and Satisfaction across the Adult Lifespan

    ERIC Educational Resources Information Center

    Isaacowitz, Derek M.; Vaillant, George E.; Seligman, Martin E. P.

    2003-01-01

    Positive psychology has recently developed a classification of human strengths (Peterson & Seligman, in press). We aimed to evaluate these strengths by investigating the strengths and life satisfaction in three adult samples recruited from the community (young adult, middle-aged, and older adult), as well as in the surviving men of the Grant study…

  1. 14 CFR 31.27 - Strength.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Strength. 31.27 Section 31.27 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.27 Strength. (a) The structure must be able...

  2. 7 CFR 29.3061 - Strength (tensile).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strength (tensile). 29.3061 Section 29.3061... Type 93) § 29.3061 Strength (tensile). The stress a tobacco leaf can bear without tearing. Tensile strength is not an important element of quality in Burley tobacco....

  3. Improving the toughness of ultrahigh strength steel

    SciTech Connect

    Soto, Koji

    2002-01-01

    The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the toughening mechanism of the Fe/Co/Ni/Cr/Mo/C steel, AerMet 100, which has the highest toughness/strength combination among all commercial ultrahigh strength steels. The possibility of improving the toughness of this steel was examined by considering several relevant factors.

  4. Cosmological magnetic fields

    NASA Astrophysics Data System (ADS)

    Kunze, Kerstin E.

    2013-12-01

    Magnetic fields are observed on nearly all scales in the Universe, from stars and galaxies up to galaxy clusters and even beyond. The origin of cosmic magnetic fields is still an open question, however a large class of models puts its origin in the very early Universe. A magnetic dynamo amplifying an initial seed magnetic field could explain the present day strength of the galactic magnetic field. However, it is still an open problem how and when this initial magnetic field was created. Observations of the cosmic microwave background (CMB) provide a window to the early Universe and might therefore be able to tell us whether cosmic magnetic fields are of a primordial cosmological origin and at the same time constrain its parameters. We will give an overview of the observational evidence of large-scale magnetic fields, describe generation mechanisms of primordial magnetic fields and possible imprints in the CMB.

  5. Photospheric magnetic fields

    NASA Technical Reports Server (NTRS)

    Howard, R.

    1972-01-01

    Knowledge on the nature of magnetic fields on the solar surface is reviewed. At least a large part of the magnetic flux in the solar surface is confined to small bundles of lines of force within which the field strength is of the order of 500 gauss. Magnetic fields are closely associated with all types of solar activity. Magnetic flux appears at the surface at the clearly defined birth or regeneration of activity of an active region. As the region ages, the magnetic flux migrates to form large-scale patterns and the polar fields. Some manifestations of the large-scale distribution are discussed.

  6. Nondestructive Determination of Bond Strength

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Although many nondestructive techniques have been applied to detect disbonds in adhesive joints, no absolutely reliable nondestructive method has been developed to detect poor adhesion and evaluate the strength of bonded joints prior to the present work which used nonlinear ultrasonic methods to investigate adhesive bond cure conditions. Previously, a variety of linear and nonlinear ultrasonic methods with water coupling had been used to study aluminum-adhesive-aluminum laminates, prepared under different adhesive curing conditions, for possible bond strength determination. Therefore, in the course of this research effort, a variety of finite-amplitude experimental methods which could possibly differentiate various cure conditions were investigated, including normal and oblique incidence approaches based on nonlinear harmonic generation as well as several non-collinear two-wave interaction approaches. Test samples were mechanically scanned in various ways with respect to the focus of a transmitting transducer operated at several variable excitation frequencies and excitation levels. Even when powerful sample-related resonances were exploited by means of a frequency scanning approach, it was very difficult to isolate the nonlinear characteristics of adhesive bonds. However, a multi-frequency multi-power approach was quite successful and reliable. Ultrasonic tone burst signals at increasing power levels, over a wide frequency range, were transmitted through each bond specimen to determine its excitation dependent nonlinear harmonic resonance behavior. Relative amplitude changes were observed particularly in the higher harmonic spectral data and analyzed using a local displacement and strain analysis in the linear approximation. Two analysis approaches of the excitation-dependent data at specific resonances were found to be quite promising. One of these approaches may represent a very robust algorithm for classifying an adhesive bond as being properly cured or not

  7. Strength of Welded Aircraft Joints

    NASA Technical Reports Server (NTRS)

    Brueggeman, W C

    1937-01-01

    This investigation is a continuation of work started in 1928 and described in NACA-TR-348 which shows that the insertion of gusset plates was the most satisfactory way of strengthening a joint. Additional tests of the present series show that joints of this type could be improved by cutting out the portion of the plate between the intersecting tubes. T and lattice joints in thin-walled tubing 1 1/2 by 0.020 inch have somewhat lower strengths than joints in tubing of greater wall thickness because of failure by local buckling. In welding the thin-walled tubing, the recently developed "carburizing flux" process was found to be the only method capable of producing joints free from cracks. The "magnetic powder" inspection was used to detect cracks in the joints and flaws in the tubing.

  8. Oscillator strengths for OII ions

    NASA Technical Reports Server (NTRS)

    Ho, Y. K.; Henry, J. W.

    1983-01-01

    Oscillator strengths between various doublet states of OII ions are calculated in which extensive multi-configuration wave functions are used. The lower levels for the transitions are of the 2p(3) D(2)o and 2p(3) 2po states, and the upper levels are 2p(4), 3s, and 3d states. The results, which are estimated to have errors of less than 10% for individual transitions, agree quite well with the beam foil experiments, as well as with the calculations by use of the non-closed shell many electron theory (NCMET). The agreement with the rocket measurements is also good except for the 538/581 A pair, in which the 538 A line is believed to be blend with the other stronger quartet line. However, a comparison with the recent branching ratio measurement indicates that discrepances between the present calculation and th experiment do exist for certain transistions.

  9. Conditioned reinforcement and response strength.

    PubMed

    Shahan, Timothy A

    2010-03-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned reinforcers do not strengthen behavior in a reinforcement-like fashion are considered. A signposts or means-to-an-end account is explored and appears to provide a plausible alternative interpretation of the effects of stimuli associated with primary reinforcers. Related suggestions that primary reinforcers also might not have their effects via a strengthening process are explored and found to be worthy of serious consideration.

  10. An indentation fatigue strength law

    NASA Astrophysics Data System (ADS)

    Xu, Baoxing; Yonezu, Akio; Chen, Xi

    2010-05-01

    Indentation fatigue, where a cyclic load is applied on the sample via an indenter, emerges as an alternative approach for measuring the fatigue properties of materials. We have carried out indentation fatigue tests on a poly(vinyl chloride) (PVC) bulk material, as well as on TiN and NiP films/coatings deposited on SUS304 steel substrates, and demonstrate that a simple power-law relationship can be established between the indentation load amplitude and number of cycles to failure. Such a law is very similar to the conventional fatigue strength law obtained from uniaxial tests. The agreement between the fatigue stress exponents obtained by uniaxial and indentation fatigue tests suggests the potential applicability of the indentation fatigue technique for extracting the fatigue properties of materials.

  11. Cobalt: for strength and color

    USGS Publications Warehouse

    Boland, Maeve A.; Kropschot, S.J.

    2011-01-01

    Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

  12. Adhesive strength of autologous fibrin glue.

    PubMed

    Yoshida, H; Hirozane, K; Kamiya, A

    2000-03-01

    To establish an easy and rapid method for measuring the adhesive strength of fibrin glue and to clarify the factor(s) most affecting the strength, a study was made on the effect of the concentration of plasma components on the strength of cryoprecipitate (Cryo) prepared from a subject's own autologous plasma to be used as fibrin glue. The adhesive strength of the Cryo was measured with various supporting materials instead of animal skin using a tester of tension and compression. The results were as follows: (1) the strength of Cryo applied to ground flat glass (4 cm2) was significantly greater than that applied to clear glass, clear plastic, or smooth and flat wood chips; (2) the adhesive strength of Cryo depended on the concentration of thrombin with the optimal concentration being 50 units/ml; (3) the concentration of CaCl2 did not affect the adhesive strength of Cryo; (4) the adhesive reaction was dependent on the temperature and the adhesive strength more quickly reached a steady state at 37 degrees C than at lower temperature; (5) the adhesive strength was correlated well with the total concentration of fibrinogen and fibronectin. These results indicate that the adhesive strength of Cryo can be easily and quickly evaluated using a tester and ground glass with thrombin at 50 units/ml, and that the adhesive strength of Cryo can be predicted from the total concentration of fibrinogen and fibronectin.

  13. Elastic-plastic fracture mechanics of strength-mismatching

    SciTech Connect

    Parks, D.M.; Ganti, S.; McClintock, F.A.

    1996-12-31

    Approximate solutions to stress-fields are provided for a strength-mismatched interface crack in small-scale yielding (SSY) for non-hardening and low hardening materials. Variations of local deformation intensities, characterized by a J-type contour integral, are proposed. The softer material experiences a higher deformation intensity level, J{sub S}, while the harder material sees a much lower deformation intensity level, J{sub H}, compared to that obtained from the applied J near the respective homogeneous crack-tips. For a low hardening material, the stress fields are obtained by scaling from an elastic/perfectly-plastic problem, based on an effective mismatch, M{sub eff}, which is a function of mismatch, M, and the hardening exponent, n. Triaxial stress build-up is discussed quantitatively in terms of M. The influence of strength-mismatch on cleavage fracture is discussed using Weibull statistics.

  14. The Distribution of Subjective Memory Strength: List Strength and Response Bias

    ERIC Educational Resources Information Center

    Criss, Amy H.

    2009-01-01

    Models of recognition memory assume that memory decisions are based partially on the subjective strength of the test item. Models agree that the subjective strength of targets increases with additional time for encoding however the origin of the subjective strength of foils remains disputed. Under the fixed strength assumption the distribution of…

  15. Correlation between the strength of glass ionomer cements and their bond strength to bovine teeth.

    PubMed

    Hibino, Yasushi; Kuramochi, Ken-ichi; Harashima, Atsushi; Honda, Muneaki; Yamazaki, Atsushi; Nagasawa, Yuko; Yamaga, Taniichiro; Nakajima, Hiroshi

    2004-12-01

    This study examined the possible correlation between the strength of glass ionomers and their adhesive strength to bovine teeth. The shear bond strengths of three different brands of glass ionomer mixed at four different P/L ratios to bovine teeth were measured 24 hours after the cement specimens were prepared. The correlation between shear bond strength and mechanical strength reported in our previous study was also examined. No significant (p > 0.05) increases in the bond strength to bovine teeth were found in any of the cements when the mixing ratio increased. The present study showed no significant (p > 0.05) correlation between mechanical strength of cement and its bond strength to bovine teeth. Rather than trying to increase the strength of the cement, it would be more effective to enhance the adhesive bond strength through procedures such as surface conditioning or cleaning of the tooth structure when glass ionomers are used as luting agents.

  16. 47 CFR 73.186 - Establishment of effective field at one kilometer.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... coordinate paper, plot field strengths as ordinate and distance as abscissa. (ii) Using semi-log coordinate paper, plot field strength times distance as ordinate on the log scale and distance as abscissa on...

  17. Bond strength of glass fiber reinforced plastics (GFRP) grouted anchors

    SciTech Connect

    Bellavance, E.; Xu, H.; Benmokrane, B.

    1995-11-01

    This paper describes the results of laboratory and field pull-out tests on cement grouted glass fiber reinforced plastic (GFRP) anchors. As an alternative for grouted steel anchors, GFRP bars have many advantages over steel tendons, and can avoid corrosion and some difficulties in transportation, handling, and installation. Three types of 36 GFRP anchors and 20 steel anchors installed in three types of host media: steel pipe, concrete block, and rock mass were tested in the laboratory as well as in the field. The bond strength, load carrying capacity, load-displacement behavior, and critical bond length of cement grouted GFRP anchors were examined in comparison with conventional steel anchors.

  18. INTEGRATION OF STRENGTH AND CONDITIONING PRINCIPLES INTO A REHABILITATION PROGRAM

    PubMed Central

    Lorenz, Daniel S.

    2011-01-01

    . Conclusion: Despite abundance of information on the implementation of training principles in the strength and conditioning field, investigation regarding the use of these principles in a properly designed rehabilitation program is lacking. PMID:21904701

  19. Counterpart of the Weyl tensor for Rarita-Schwinger type fields

    NASA Astrophysics Data System (ADS)

    Brandt, Friedemann

    2017-04-01

    In dimensions larger than 3 a modified field strength for Rarita-Schwinger type fields is constructed whose components are not constrained by the field equations. In supergravity theories the result provides a modified (supercovariant) gravitino field strength related by supersymmetry to the (supercovariantized) Weyl tensor. In various cases, such as for free Rarita-Schwinger type gauge fields and for gravitino fields in several supergravity theories, the modified field strength coincides on-shell with the usual field strength. A corresponding result for first order derivatives of Dirac type spinor fields is also presented.

  20. Dynamic Strength Ceramic Nanocomposites Under Pulse Loading

    NASA Astrophysics Data System (ADS)

    Skripnyak, Evgeniya G.; Skripnyak, Vladimir V.; Vaganova, Irina K.; Skripnyak, Vladimir A.

    2015-06-01

    Multi-scale computer simulation approach has been applied to research of strength of nanocomposites under dynamic loading. The influence of mesoscopic substructures on the dynamic strength of ceramic and hybrid nanocomposites, which can be formed using additive manufacturing were numerically investigated. At weak shock wave loadings the shear strength and the spall strength of ceramic and hybrid nanocomposites depends not only phase concentration and porosity, but size parameters of skeleton substructures. The influence of skeleton parameter on the shear strength and the spall strength of ceramic nanocomposites with the same concentration of phases decreases with increasing amplitude of the shock pulse of microsecond duration above the double amplitude of the Hugoniot elastic limit of nanocomposites. This research carried out in 2014 -2015 was supported by grant from The Tomsk State University Academic D.I. Mendeleev Fund Program and also Ministry of Sciences and Education of Russian Federation (State task 2014/223, project 1943, Agreement 14.132.

  1. Strength, flexibility, and maturity in adolescent athletes.

    PubMed

    Pratt, M

    1989-05-01

    The relationship between lower-extremity strength and flexibility and maturational status as measured by Tanner staging (TS) was assessed in 84 male high school athletes. The sum of one-repetition maximum lifts for knee extension and flexion was determined and flexibility was measured with the American Alliance of Health, Physical Education, Recreation, and Dance sit-and-reach test. Chronologic age, body weight, and percent fat were also recorded. Strength and flexibility were compared for each maturational and chronologic age category. Maturational age was better correlated with strength and flexibility than was chronologic age. All correlations were significant. Multiple regression analysis demonstrated significant correlations of TS and age with strength and flexibility. Tanner staging had greater predictive value than age for strength and flexibility. After adjusting for age, the relationship between TS and strength remained significant.

  2. Strengths and satisfaction across the adult lifespan.

    PubMed

    Isaacowitz, Derek M; Vaillant, George E; Seligman, Martin E P

    2003-01-01

    Positive psychology has recently developed a classification of human strengths (Peterson & Seligman, in press). We aimed to evaluate these strengths by investigating the strengths and life satisfaction in three adult samples recruited from the community (young adult, middle-aged, and older adult), as well as in the surviving men of the Grant study of Harvard graduates. In general, older adults had higher levels of interpersonal and self-regulatory strengths, whereas younger adults reported higher levels of strengths related to exploring the world. Grant study men tended to report lower strength levels than older adults from the community. Among the young adults, only hope significantly predicted life satisfaction, whereas among the middle-aged individuals, the capacity for loving relationships was the only predictor. Among community-dwelling older adults, hope, citizenship, and loving relationships all positively and uniquely predicted life satisfaction, compared with loving relationships and appreciation of beauty in the Grant sample.

  3. Effect of adherend steel strength on static and fatigue strength of adhesive/rivet combined joint

    NASA Astrophysics Data System (ADS)

    Imanaka, Makoto; Haraga, Kosuke; Nishikawa, Tetsuya

    1992-02-01

    Adhesive/rivet combined bonding has attracted special interest recently as a joining technique of high-strength steel because of its high joint efficiency. In this study, the effects of steel strength on the tensile and fatigue strength of adhesive/rivet combined and adhesive joints were investigated. In addition, the stress distributions of these joints were analyzed by finite-element methods, taking into consideration the plastic deformation of adherend steels. With the increase of steel strength, the tensile strength of combined and adhesive joints increased and tensile strength was improved by the combination with the rivet. However, irrespective of the steel strength, the fatigue strength of combined and adhesive joints was constant and the fatigue strength of the combined joint was similar to that of the adhesive joint. These findings could be explained from the difference of stress distribution between static and fatigue load conditions.

  4. Development of a Female Atlas of Strengths

    DTIC Science & Technology

    1982-02-01

    Physiotherapy ; 1977, 63(2), 51-55. 31. Falkel, .3. Planter flexor strength testing using the cybex isokinetic dynanometer. Phys. Ther.; 1978, 58(7), 847...instances "heart attacks," or "cardiac arrest," strokes ,or pulmonary embolism. If this research project causes any physical injury to you, treatment...STUDY: Edwards, R.H.T. and Hyde, S. Methods of measuring muscle strength and fatigue. Physiotherapy ; 1977, 63(2), 51-55. KEYWORDS: Muscle strength tests

  5. Fracture strength of silicon solar cells

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1979-01-01

    A test program was developed to determine the nature and source of the flaw controlling the fracture of silicon solar cells and to provide information regarding the mechanical strength of cells. Significant changes in fracture strengths were found in seven selected in-process wafer-to-cell products from a manufacturer's production line. The fracture strength data were statistically analyzed and interpreted in light of the exterior flaw distribution of the samples.

  6. Mechanical strength and stability of lithium aluminate

    NASA Astrophysics Data System (ADS)

    Brimhall, J. L.

    1992-06-01

    Pacific Northwest Laboratory (PNL) investigated the strength and resistance to thermal shock of lithium aluminate annular pellets. The room temperature, axial compressive fracture strength of pellets made at Westinghouse Advanced Energy Systems (WAES) varied from 80 to 133 ksi. The strength at 430 C (806 F) was to 30 to 40 percent lower. The strength at 900 C (1652 F) showed a wide variation with one measurement near 90 ksi. These strength values are consistent with other data and predictions made in the literature when the grain size and porosity of the microstructure are taken into account. In diametral compression tests, the fracture strengths were much lower due to the existence of tensile stresses in some pellet regions from this type of loading. However, the fracture stresses were still generally higher than those reported in the literature; this fracture resistance probably reflects the better quality of the pellets tested in this study. Measurements on pellets made at PNL indicated lower strengths compared to the WAES material. This strength difference could be accounted for by different processing technologies: material made at PNL was cold-pressed and sintered with high porosity whereas the WAES material was isostatically hot-pressed with high density. Thermal shocking of the material by ramping to 900 C in two minutes did not have an observable effect on the microstructure or the strength of any of the pellets.

  7. Strength Training in Individuals with Stroke

    PubMed Central

    Eng, Janice J

    2012-01-01

    Purpose This paper reviews the mechanisms underlying the inability to generate force in individuals with stroke and summarizes the effects of strength training in these individuals. In addition, a systematic review of studies that have incorporated progressive strengthening interventions in individuals with stroke is presented. Summary of Key Points Central (e.g., motor recruitment) and peripheral (e.g., muscle atrophy) sources may alter muscle strength in individuals with stroke and further investigations are needed to partition and quantify their effects. As to the effect of strength training interventions in individuals with stroke, the majority of studies (albeit with small samples) that evaluated muscle strength as an outcome demonstrated improvements. With regard to the effect of strength training on functional outcomes in individuals with stroke, positive outcomes were found in less rigorous pre-test/post-test studies, but more conflicting results with controlled trials. Conclusions Although there is some suggestion that strength training alone can improve muscle strength, further research is required to optimize strength training and the transfer of these strength gains to functional tasks in individuals with stroke. PMID:23255839

  8. Accelerated Strength Testing of Thermoplastic Composites

    NASA Technical Reports Server (NTRS)

    Reeder, J. R.; Allen, D. H.; Bradley, W. L.

    1998-01-01

    Constant ramp strength tests on unidirectional thermoplastic composite specimens oriented in the 90 deg. direction were conducted at constant temperatures ranging from 149 C to 232 C. Ramp rates spanning 5 orders of magnitude were tested so that failures occurred in the range from 0.5 sec. to 24 hrs. (0.5 to 100,000 MPa/sec). Below 204 C, time-temperature superposition held allowing strength at longer times to be estimated from strength tests at shorter times but higher temperatures. The data indicated that a 50% drop in strength might be expected for this material when the test time is increased by 9 orders of magnitude. The shift factors derived from compliance data applied well to the strength results. To explain the link between compliance and strength, a viscoelastic fracture model was investigated. The model, which used compliance as input, was found to fit the strength data only if the critical fracture energy was allowed to vary with temperature reduced stress rate. This variation in the critical parameter severely limits its use in developing a robust time-dependent strength model. The significance of this research is therefore seen as providing both the indication that a more versatile acceleration method for strength can be developed and the evidence that such a method is needed.

  9. Muscle Strength and Speed Performance in Youth Soccer Players.

    PubMed

    Peñailillo, Luis; Espíldora, Francisco; Jannas-Vela, Sebastián; Mujika, Iñigo; Zbinden-Foncea, Hermann

    2016-04-01

    This study aimed to examine the relationship between maximum leg extension strength and sprinting performance in youth elite male soccer players. Sixty-three youth players (12.5 ± 1.3 years) performed 5 m, flying 15 m and 20 m sprint tests and a zigzag agility test on a grass field using timing gates. Two days later, subjects performed a one-repetition maximum leg extension test (79.3 ± 26.9 kg). Weak to strong correlations were found between leg extension strength and the time to perform 5 m (r = -0.39, p = 0.001), flying 15 m (r = -0.72, p < 0.001) and 20 m (r = -0.67, p < 0.001) sprints; between body mass and 5 m (r = -0.43, p < 0.001), flying 15 m (r = -0.75, p < 0.001), 20 m (r = -0.65, p < 0.001) sprints and agility (r =-0.29, p < 0.001); and between height and 5 m (r = -0.33, p < 0.01) and flying 15 m (r = -0.74, p < 0.001) sprints. Our results show that leg muscle strength and anthropometric variables strongly correlate with sprinting ability. This suggests that anthropometric characteristics should be considered to compare among youth players, and that youth players should undergo strength training to improve running speed.

  10. Hand Grip Strength Vs. Sprint Effectiveness in Amputee Soccer Players.

    PubMed

    Wieczorek, Marta; Wiliński, Wojciech; Struzik, Artur; Rokita, Andrzej

    2015-11-22

    Amputee soccer is one of the types of soccer designed for the disabled, especially those who have undergone amputations, as well as those with extremity dysfunction. The objective of the study was to find the relationship between hand grip strength and sprint time in amputee soccer players. Thirteen field amputee soccer players participated in the study. A SAEHAN hydraulic hand dynamometer manufactured by Jamar was used for hand grip strength measurements. The sprint running test was conducted over a distance of 30 m. The Fusion Smart Speed System was employed for running time measurements. No statistically significant relationships were found between hand grip strength of the left or right hand, and sprint times over 1, 5, 10, 15, 20, 25 and 30 m. Analysis of the running velocity curve of the subjects showed an interesting profile characterized by a 15 meter-long acceleration phase and a significant velocity increase over a distance of 20 - 25 m. The study suggests that there is no relationship between hand grip strength and sprint effectiveness in amputee soccer players. The specificity of locomotion with the use of elbow crutches among elite Polish amputee soccer players probably accounts for the profile of the sprint velocity curve. Extension of the acceleration phase in the sprint run and a velocity increase in the subsequent part of the run were observed.

  11. Dramatically enhanced electrical breakdown strength in cellulose nanopaper

    NASA Astrophysics Data System (ADS)

    Huang, Jianwen; Zhou, Yuanxiang; Zhou, Zhongliu; Liu, Rui

    2016-09-01

    Electrical breakdown behaviors of nanopaper prepared from nanofibrillated cellulose (NFC) were investigated. Compared to conventional insulating paper made from micro softwood fibers, nanopaper has a dramatically enhanced breakdown strength. Breakdown field of nanopaper is 67.7 kV/mm, whereas that of conventional paper is only 20 kV/mm. Air voids in the surface of conventional paper are observed by scanning electron microscope (SEM). Further analyses using mercury intrusion show that pore diameter of conventional paper is around 1.7 μ m , while that of nanopaper is below 3 nm. Specific pore size of nanopaper is determined to be approximately 2.8 nm by the gas adsorption technique. In addition, theoretical breakdown strengths of nanopaper and conventional paper are also calculated to evaluate the effect of pore size. It turns out that theoretical values agree well with experimental data, indicating that the improved strength in nanopaper is mainly attributed to the decreased pore size. Due to its outstanding breakdown strength, this study indicates the suitability of nanopaper for electrical insulation in ultra-high voltage convert transformers and other electrical devices.

  12. Functionalization enhancement on interfacial shear strength between graphene and polyethylene

    NASA Astrophysics Data System (ADS)

    Jin, Yikuang; Duan, Fangli; Mu, Xiaojing

    2016-11-01

    Pull-out processes were simulated to investigate the interfacial mechanical properties between the functionalized graphene sheet (FGS) and polyethylene (PE) matrix by using molecular dynamics simulation with ReaxFF reactive force field. The interfacial structure of polymer and the interfacial interaction in the equilibrium FGS/PE systems were also analyzed to reveal the enhancement mechanism of interfacial shear strength. We observed the insertion of functional groups into polymer layer in the equilibrium FGS/PE systems. During the pull-out process, some interfacial chains were attached on the FGS and pulled out from the polymer matrix. The behavior of these pulled out chains was further analyzed to clarify the different traction action of functional groups applied on them. The results show that the traction effect of functional groups on the pulled-out chains is agreement with their enhancement influence on the interfacial shear strength of the FGS/PE systems. They both are basically dominated by the size of functional groups, suggesting the enhancement mechanism of mechanical interlocking. However, interfacial binding strength also exhibits an obvious influence on the interfacial shear properties of the hybrid system. Our simulation show that geometric constrains at the interface is the principal contributor to the enhancement of interfacial shear strength in the FGS/PE systems, which could be further strengthened by the wrinkled morphology of graphene in experiments.

  13. Muscle Strength and Speed Performance in Youth Soccer Players

    PubMed Central

    Peñailillo, Luis; Espíldora, Francisco; Jannas-Vela, Sebastián; Mujika, Iñigo

    2016-01-01

    Abstract This study aimed to examine the relationship between maximum leg extension strength and sprinting performance in youth elite male soccer players. Sixty-three youth players (12.5 ± 1.3 years) performed 5 m, flying 15 m and 20 m sprint tests and a zigzag agility test on a grass field using timing gates. Two days later, subjects performed a one-repetition maximum leg extension test (79.3 ± 26.9 kg). Weak to strong correlations were found between leg extension strength and the time to perform 5 m (r = -0.39, p = 0.001), flying 15 m (r = -0.72, p < 0.001) and 20 m (r = -0.67, p < 0.001) sprints; between body mass and 5 m (r = -0.43, p < 0.001), flying 15 m (r = -0.75, p < 0.001), 20 m (r = -0.65, p < 0.001) sprints and agility (r =-0.29, p < 0.001); and between height and 5 m (r = -0.33, p < 0.01) and flying 15 m (r = -0.74, p < 0.001) sprints. Our results show that leg muscle strength and anthropometric variables strongly correlate with sprinting ability. This suggests that anthropometric characteristics should be considered to compare among youth players, and that youth players should undergo strength training to improve running speed. PMID:28149358

  14. Quadriceps muscle strength in scoliosis.

    PubMed

    Swallow, E B; Barreiro, E; Gosker, H; Sathyapala, S A; Sanchez, F; Hopkinson, N S; Moxham, J; Schols, A; Gea, J; Polkey, M I

    2009-12-01

    Quadriceps muscle weakness is an important component of chronic obstructive pulmonary disease (COPD). We hypothesised that quadriceps weakness would also be a feature of restrictive lung disease due to scoliosis. We studied 10 patients with severe scoliosis (median (interquartile range (IQR)) forced expiratory volume in 1 s (FEV(1))() 35.3 (11)% predicted), 10 patients with severe COPD (FEV(1) 26.5 (9.0)% pred) and 10 healthy age-matched adults. We measured quadriceps strength, exercise capacity and analysed quadriceps muscle biopsies for myosin heavy-chain (MyHC) isoform expression and the presence of oxidative stress. Both groups exhibited quadriceps weakness with median (IQR) maximal voluntary contraction force being 46.0 (17.0) kg, 21.5 (21.0) kg and 31.5 (11.0) kg, respectively (p = 0.02 and 0.04, respectively, for each patient group against controls). Oxidative stress was significantly greater in the quadriceps of both restrictive and COPD patients. The scoliosis patients exhibited a decrease in the proportion of MyHC type I compared with controls; median (IQR) 35.3 (18.5)% compared with 47.7 (9.3)%, p = 0.028. The scoliosis patients also showed an increase in MyHC IIx (26.3 (15.5)% compared with 11.3 (13.0)%, p = 0.01. Quadriceps weakness is a feature of severe scoliosis; the similarities between patients with scoliosis and patients with COPD suggest a common aetiology to quadriceps weakness in both conditions.

  15. Probabilistic Modeling of Ceramic Matrix Composite Strength

    NASA Technical Reports Server (NTRS)

    Shan, Ashwin R.; Murthy, Pappu L. N.; Mital, Subodh K.; Bhatt, Ramakrishna T.

    1998-01-01

    Uncertainties associated with the primitive random variables such as manufacturing process (processing temperature, fiber volume ratio, void volume ratio), constituent properties (fiber, matrix and interface), and geometric parameters (ply thickness, interphase thickness) have been simulated to quantify the scatter in the first matrix cracking strength (FMCS) and the ultimate tensile strength of SCS-6/RBSN (SiC fiber (SCS-6) reinforced reaction-bonded silicon nitride composite) ceramic matrix composite laminate at room temperature. Cumulative probability distribution function for the FMCS and ultimate tensile strength at room temperature (RT) of (0)(sub 8), (0(sub 2)/90(sub 2), and (+/-45(sub 2))(sub S) laminates have been simulated and the sensitivity of primitive variables to the respective strengths have been quantified. Computationally predicted scatter of the strengths for a uniaxial laminate have been compared with those from limited experimental data. Also the experimental procedure used in the tests has been described briefly. Results show a very good agreement between the computational simulation and the experimental data. Dominating failure modes in (0)(sub 8), (0/90)(sub s) and (+/-45)(sub S) laminates have been identified. Results indicate that the first matrix cracking strength for the (0)(sub S), and (0/90)(sub S) laminates is sensitive to the thermal properties, modulus and strengths of both the fiber and matrix whereas the ultimate tensile strength is sensitive to the fiber strength and the fiber volume ratio. In the case of a (+/-45)(sub S), laminate, both the FMCS and the ultimate tensile strengths have a small scatter range and are sensitive to the fiber tensile strength as well as the fiber volume ratio.

  16. A review of floc strength and breakage.

    PubMed

    Jarvis, P; Jefferson, B; Gregory, J; Parsons, S A

    2005-09-01

    The main focus of the paper is to review current understanding of floc structure and strength. This has been done by reviewing current theoretical understanding of floc growth and breakage and an analysis of different techniques used for measuring floc strength. An overview has also been made of the general trends seen in floc strength analysis. The rate of floc formation is a balance between breakage and aggregation with flocs eventually reaching a steady-state size for a given shear rate. The steady-state floc size for a particular shear rate can, therefore, be a good indicator of floc strength. This has resulted in the development of a range of techniques to measure floc size at different applied shear levels using a combination of one or more of the following tools: light scattering and transmission; microscopy; photography; video and image analysis software. Floc strength may be simply quantified using the initial floc size for a given shear rate and the floc strength factor. More complex techniques have used theoretical modelling to determine whether flocs break by large-scale fragmentation or smaller-scale surface erosion effects, although this interpretation is open to debate. Impeller-based mixing, ultrasound and vibrating columns have all been used to provide a uniform, accurate and controllable dissipation of energy onto a floc suspension to determine floc strength. Other more recent techniques have used sensitive micromanipulators to measure the force required to break or compress individual flocs, although these techniques have been limited to the measurement of only a few hundred flocs. General trends emerge showing that smaller flocs tend to have greater strength than larger flocs, whilst the use of polymer seems to give increased strength to only some types of floc. Finally, a comparison of the strength of different types of floc (activated sludge flocs, organic matter flocs, sweep flocs and charge neutralised flocs) has been made highlighting

  17. Understanding Bone Strength Is Not Enough.

    PubMed

    Hernandez, Christopher J; van der Meulen, Marjolein Ch

    2017-01-09

    Increases in fracture risk beyond what are expected from bone mineral density (BMD) are often attributed to poor "bone quality," such as impaired bone tissue strength. Recent studies, however, have highlighted the importance of tissue material properties other than strength, such as fracture toughness. Here we review the concepts behind failure properties other than strength and the physical mechanisms through which they cause mechanical failure: strength describes failure from a single overload; fracture toughness describes failure from a modest load combined with a preexisting flaw or damage; and fatigue strength describes failure from thousands to millions of cycles of small loads. In bone, these distinct failure mechanisms appear to be more common in some clinical fractures than others. For example, wrist fractures are usually the result of a single overload, the failure mechanism dominated by bone strength, whereas spinal fractures are rarely the result of a single overload, implicating multiple loading cycles and increased importance of fatigue strength. The combination of tissue material properties and failure mechanisms that lead to fracture represent distinct mechanistic pathways, analogous to molecular pathways used to describe cell signaling. Understanding these distinct mechanistic pathways is necessary because some characteristics of bone tissue can increase fracture risk by impairing fracture toughness or fatigue strength without impairing bone tissue strength. Additionally, mechanistic pathways to failure associated with fracture toughness and fatigue involve multiple loading events over time, raising the possibility that a developing fracture could be detected and interrupted before overt failure of a bone. Over the past two decades there have been substantial advancements in fracture prevention by understanding bone strength and fractures caused by a single load, but if we are to improve fracture risk prevention beyond what is possible now, we must

  18. Inferring the spatial variation of the wedge strength based on a modified critical taper model

    NASA Astrophysics Data System (ADS)

    Yang, C.; Liu, H.; Hsieh, Y.; Dong, J.

    2013-12-01

    Critical taper wedge theory has been widely applied to evaluate the strength of the detachment fault and the wedge by measuring taper angle. Traditional taper model, which incorporated constant cohesion and friction angle, fails to explain the lateral variation of the taper angle. A modified critical taper model adopting nonlinear Hoek-Brown failure criterion is proposed accordingly. The fold-and-thrust belt of central Taiwan was studied. Based on the field works and laboratory tests, the geological strength index (GSI) and the uniaxial compressive strength were obtained and the wedge strength can be estimated accordingly. The GSI values from investigation are decreased from the west to the east along the cross section due to the wedge strength heterogeneity. The uniaxial compressive strength of intact rock varies from the age of formation and lithology. The estimated wedge strength exhibits a strong spatial variation. The strength of the detachment fault was derived from rotary shear tests using fault gouge materials under different velocities and normal stresses. General speaking, the steady-state friction coefficient are about 0.29-0.46 when the shear velocity less than 0.1 m/s. The friction coefficient is not sensitive to the normal stress. Consequently, the lateral variation of the taper angle, which calculated by modified critical taper model, is mainly dominated by the wedge strength heterogeneity and the thickening of the wedge from the west to the east.

  19. Restorative Justice as Strength-Based Accountability

    ERIC Educational Resources Information Center

    Ball, Robert

    2003-01-01

    This article compares strength-based and restorative justice philosophies for young people and their families. Restorative justice provides ways to respond to crime and harm that establish accountability while seeking to reconcile members of a community. Restorative approaches are an important subset of strength-based interventions.

  20. The genetic architecture of maize stalk strength

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stalk strength is an important trait in maize (Zea mays L.). Strong stalks reduce lodging and maximize harvestable yield. Studies show rind penetrometer resistance (RPR), or the force required to pierce a stalk rind with a spike, is a valid approximation of strength. We measured RPR across 4,892 rec...