Energy flux determines magnetic field strength of planets and stars.

Science.gov (United States)

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.

Comparative study of maximum isometric grip strength in different sports

Directory of Open Access Journals (Sweden)

Noé Gomes Borges Junior

2009-01-01

Full Text Available http://dx.doi.org/10.5007/1980-0037.2009v11n3p292   The objective of this study was to compare maximum isometric grip strength (Fmaxbetween different sports and between the dominant (FmaxD and non-dominant (FmaxND hand. Twenty-nine male aikido (AI, jiujitsu (JJ, judo (JU and rowing (RO athletes and 21non-athletes (NA participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of the subjects was that suggested by the American Society of Hand Therapy. Factorial 2X5 ANOVA with Bonferroni correction, followed by a paired t test and Tukey test, was used for statistical analysis. The highest Fmax values were observed for the JJ group when using the dominant hand,followed by the JU, RO, AI and NA groups. Variation in Fmax could be attributed to handdominance (30.9%, sports modality (39.9% and the interaction between hand dominance andsport (21.3%. The present results demonstrated significant differences in Fmax between the JJ and AI groups and between the JJ and NA groups for both the dominant and non-dominant hand. Significant differences in Fmax between the dominant and non-dominant hand were only observed in the AI and NA groups. The results indicate that Fmax can be used for comparisonbetween different sports modalities, and to identify differences between the dominant and nondominanthand. Studies involving a larger number of subjects will permit the identification of differences between other modalities.

The maximum percentage of fly ash to replace part of original Portland cement (OPC) in producing high strength concrete

Science.gov (United States)

Mallisa, Harun; Turuallo, Gidion

2017-11-01

This research investigates the maximum percent of fly ash to replace part of Orginal Portland Cement (OPC) in producing high strength concrete. Many researchers have found that the incorporation of industrial by-products such as fly ash as in producing concrete can improve properties in both fresh and hardened state of concrete. The water-binder ratio was used 0.30. The used sand was medium sand with the maximum size of coarse aggregate was 20 mm. The cement was Type I, which was Bosowa Cement produced by PT Bosowa. The percentages of fly ash to the total of a binder, which were used in this research, were 0, 10, 15, 20, 25 and 30%; while the super platicizer used was typed Naptha 511P. The results showed that the replacement cement up to 25 % of the total weight of binder resulted compressive strength higher than the minimum strength at one day of high-strength concrete.

SU(N) instantons in the field strength approach to QCD

International Nuclear Information System (INIS)

Reinhardt, H.

1994-01-01

Field strength formulated Yang-Mills theory is confronted to the traditional formulation in terms of gauge fields. It is shown that both formulations yield the same semiclassics, in particular the same instanton physics. The field strength formulation is, however, superior at the tree level where it includes already a good deal of quantum fluctuations of the standard formulation. These quantum fluctuations break the scale invariance of classical QCD and give rise to an instanton interaction. The latter causes the instanton to condense and to form a homogeneous instanton solid. These instanton solids show up in the field strength approach as homogeneous (constant up to gauge transformations) vacuum solutions. A new class of SU(N) instantons is presented which are not embeddings of SU(N-1) instantons but have non-trivial SU(N) color structure and carry winding number n = N/(N 2 -1)/6. These novel instantons generate (after condensation) the lowest action homogeneous solutions of the field strength approach. (orig.)

Cognition and sensation in very high static magnetic fields: a randomized case-crossover study with different field strengths.

Science.gov (United States)

Heinrich, Angela; Szostek, Anne; Meyer, Patric; Nees, Frauke; Rauschenberg, Jaane; Gröbner, Jens; Gilles, Maria; Paslakis, Georgios; Deuschle, Michael; Semmler, Wolfhard; Flor, Herta

2013-01-01

To establish the extent to which representative cognitive functions in subjects undergoing magnetic resonance (MR) imaging are acutely impaired by static magnetic fields of varying field strengths. This study was approved by the local ethics committee, and informed consent was obtained from all subjects. In this single-blind case-crossover study, 41 healthy subjects underwent an extensive neuropsychologic examination while in MR units of differing field strengths (1.5, 3.0, and 7.0 T), including a mock imager with no magnetic field as a control condition. Subjects were blinded to field strength. Tests were performed while subjects were lying still in the MR unit and while the examination table was moved. The tests covered a representative set of cognitive functions, such as memory, eye-hand coordination, attention, reaction time, and visual discrimination. Subjective sensory perceptions were also assessed. Effects were analyzed with a repeated-measures analysis of variance; the within-subject factors were field strength (0, 1.5, 3.0, and 7.0 T) and state (static, dynamic). Static magnetic fields were not found to have a significant effect on cognitive function at any field strength. However, sensory perceptions did vary according to field strength. Dizziness, nystagmus, phosphenes, and head ringing were related to the strength of the static magnetic field. Static magnetic fields as high as 7.0 T did not have a significant effect on cognition. RSNA, 2012

Predicting the Maximum Dynamic Strength in Bench Press: The High Precision of the Bar Velocity Approach.

Science.gov (United States)

Loturco, Irineu; Kobal, Ronaldo; Moraes, José E; Kitamura, Katia; Cal Abad, César C; Pereira, Lucas A; Nakamura, Fábio Y

2017-04-01

Loturco, I, Kobal, R, Moraes, JE, Kitamura, K, Cal Abad, CC, Pereira, LA, and Nakamura, FY. Predicting the maximum dynamic strength in bench press: the high precision of the bar velocity approach. J Strength Cond Res 31(4): 1127-1131, 2017-The aim of this study was to determine the force-velocity relationship and test the possibility of determining the 1 repetition maximum (1RM) in "free weight" and Smith machine bench presses. Thirty-six male top-level athletes from 3 different sports were submitted to a standardized 1RM bench press assessment (free weight or Smith machine, in randomized order), following standard procedures encompassing lifts performed at 40-100% of 1RM. The mean propulsive velocity (MPV) was measured in all attempts. A linear regression was performed to establish the relationships between bar velocities and 1RM percentages. The actual and predicted 1RM for each exercise were compared using a paired t-test. Although the Smith machine 1RM was higher (10% difference) than the free weight 1RM, in both cases the actual and predicted values did not differ. In addition, the linear relationship between MPV and percentage of 1RM (coefficient of determination ≥95%) allow determination of training intensity based on the bar velocity. The linear relationships between the MPVs and the relative percentages of 1RM throughout the entire range of loads enable coaches to use the MPV to accurately monitor their athletes on a daily basis and accurately determine their actual 1RM without the need to perform standard maximum dynamic strength assessments.

Microchip Electrophoresis at Elevated Temperatures and High Separation Field Strengths

Science.gov (United States)

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

2014-01-01

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 can be used to 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. PMID:24114979

Unification of field theory and maximum entropy methods for learning probability densities

Science.gov (United States)

Kinney, Justin B.

2015-09-01

The need to estimate smooth probability distributions (a.k.a. probability densities) from finite sampled data is ubiquitous in science. Many approaches to this problem have been described, but none is yet regarded as providing a definitive solution. Maximum entropy estimation and Bayesian field theory are two such approaches. Both have origins in statistical physics, but the relationship between them has remained unclear. Here I unify these two methods by showing that every maximum entropy density estimate can be recovered in the infinite smoothness limit of an appropriate Bayesian field theory. I also show that Bayesian field theory estimation can be performed without imposing any boundary conditions on candidate densities, and that the infinite smoothness limit of these theories recovers the most common types of maximum entropy estimates. Bayesian field theory thus provides a natural test of the maximum entropy null hypothesis and, furthermore, returns an alternative (lower entropy) density estimate when the maximum entropy hypothesis is falsified. The computations necessary for this approach can be performed rapidly for one-dimensional data, and software for doing this is provided.

Unification of field theory and maximum entropy methods for learning probability densities.

Science.gov (United States)

Kinney, Justin B

2015-09-01

The need to estimate smooth probability distributions (a.k.a. probability densities) from finite sampled data is ubiquitous in science. Many approaches to this problem have been described, but none is yet regarded as providing a definitive solution. Maximum entropy estimation and Bayesian field theory are two such approaches. Both have origins in statistical physics, but the relationship between them has remained unclear. Here I unify these two methods by showing that every maximum entropy density estimate can be recovered in the infinite smoothness limit of an appropriate Bayesian field theory. I also show that Bayesian field theory estimation can be performed without imposing any boundary conditions on candidate densities, and that the infinite smoothness limit of these theories recovers the most common types of maximum entropy estimates. Bayesian field theory thus provides a natural test of the maximum entropy null hypothesis and, furthermore, returns an alternative (lower entropy) density estimate when the maximum entropy hypothesis is falsified. The computations necessary for this approach can be performed rapidly for one-dimensional data, and software for doing this is provided.

A Maximum Principle for SDEs of Mean-Field Type

Energy Technology Data Exchange (ETDEWEB)

Andersson, Daniel, E-mail: danieand@math.kth.se; Djehiche, Boualem, E-mail: boualem@math.kth.se [Royal Institute of Technology, Department of Mathematics (Sweden)

2011-06-15

We study the optimal control of a stochastic differential equation (SDE) of mean-field type, where the coefficients are allowed to depend on some functional of the law as well as the state of the process. Moreover the cost functional is also of mean-field type, which makes the control problem time inconsistent in the sense that the Bellman optimality principle does not hold. Under the assumption of a convex action space a maximum principle of local form is derived, specifying the necessary conditions for optimality. These are also shown to be sufficient under additional assumptions. This maximum principle differs from the classical one, where the adjoint equation is a linear backward SDE, since here the adjoint equation turns out to be a linear mean-field backward SDE. As an illustration, we apply the result to the mean-variance portfolio selection problem.

A Maximum Principle for SDEs of Mean-Field Type

International Nuclear Information System (INIS)

Andersson, Daniel; Djehiche, Boualem

2011-01-01

We study the optimal control of a stochastic differential equation (SDE) of mean-field type, where the coefficients are allowed to depend on some functional of the law as well as the state of the process. Moreover the cost functional is also of mean-field type, which makes the control problem time inconsistent in the sense that the Bellman optimality principle does not hold. Under the assumption of a convex action space a maximum principle of local form is derived, specifying the necessary conditions for optimality. These are also shown to be sufficient under additional assumptions. This maximum principle differs from the classical one, where the adjoint equation is a linear backward SDE, since here the adjoint equation turns out to be a linear mean-field backward SDE. As an illustration, we apply the result to the mean-variance portfolio selection problem.

Does combined strength training and local vibration improve isometric maximum force? A pilot study.

Science.gov (United States)

Goebel, Ruben; Haddad, Monoem; Kleinöder, Heinz; Yue, Zengyuan; Heinen, Thomas; Mester, Joachim

2017-01-01

The aim of the study was to determine whether a combination of strength training (ST) and local vibration (LV) improved the isometric maximum force of arm flexor muscles. ST was applied to the left arm of the subjects; LV was applied to the right arm of the same subjects. The main aim was to examine the effect of LV during a dumbbell biceps curl (Scott Curl) on isometric maximum force of the opposite muscle among the same subjects. It is hypothesized, that the intervention with LV produces a greater gain in isometric force of the arm flexors than ST. Twenty-seven collegiate students participated in the study. The training load was 70% of the individual 1 RM. Four sets with 12 repetitions were performed three times per week during four weeks. The right arm of all subjects represented the vibration trained body side (VS) and the left arm served as the traditional trained body side (TTS). A significant increase of isometric maximum force in both body sides (Arms) occurred. VS, however, significantly increased isometric maximum force about 43% in contrast to 22% of the TTS. The combined intervention of ST and LC improves isometric maximum force of arm flexor muscles. III.

High-energy behavior of field-strength interactions

International Nuclear Information System (INIS)

Levin, D.N.

1976-01-01

It is known that spontaneously broken gauge theories are the only renormalizable theories of massive spin-one particles with mass dimension less than or equal to 4. This paper describes a search for renormalizable interactions with higher mass dimension. Specifically, we examine the high-energy behavior of a class of models which involve field-strength interactions. Power counting shows that the high-energy behavior of these models is no worse than the naively estimated high-energy behavior of a gauge theory in the U gauge. Therefore, there may be a ''soft'' symmetry-breaking mechanism (for instance, a soft divergence of an antisymmetric tensor current) which enforces renormalizable high-energy behavior in the same way that spontaneously broken gauge invariance guarantees the renormalizability of gauge theories. This hope is supported by the existence of ''gauge theories'' of strings, which describe analogous interactions of strings and field strengths. Unfortunately, this idea is tarnished by explicit calculations in which renormalizability is imposed in the form of unitarity bounds. These unitarity bounds imply that all possible field-strength couplings must be zero and that the remaining interactions describe a spontaneously broken gauge theory. Thus this result supports an earlier conjecture that gauge theories are the only renormalizable theories of massive vector bosons

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

Science.gov (United States)

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…

Magnetic-field-induced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength.

Science.gov (United States)

Raaijmakers, A J E; Raaymakers, B W; Lagendijk, J J W

2008-02-21

Several institutes are currently working on the development of a radiotherapy treatment system with online MR imaging (MRI) modality. The main difference between their designs is the magnetic field strength of the MRI system. While we have chosen a 1.5 Tesla (T) magnetic field strength, the Cross Cancer Institute in Edmonton will be using a 0.2 T MRI scanner and the company Viewray aims to use 0.3 T. The magnetic field strength will affect the severity of magnetic field dose effects, such as the electron return effect (ERE): considerable dose increase at tissue air boundaries due to returning electrons. This paper has investigated how the ERE dose increase depends on the magnetic field strength. Therefore, four situations where the ERE occurs have been simulated: ERE at the distal side of the beam, the lateral ERE, ERE in cylindrical air cavities and ERE in the lungs. The magnetic field comparison values were 0.2, 0.75, 1.5 and 3 T. Results show that, in general, magnetic field dose effects are reduced at lower magnetic field strengths. At the distal side, the ERE dose increase is largest for B = 0.75 T and depends on the irradiation field size for B = 0.2 T. The lateral ERE is strongest for B = 3 T but shows no effect for B = 0.2 T. Around cylindrical air cavities, dose inhomogeneities disappear if the radius of the cavity becomes small relative to the in-air radius of the secondary electron trajectories. At larger cavities (r > 1 cm), dose inhomogeneities exist for all magnetic field strengths. In water-lung-water phantoms, the ERE dose increase takes place at the water-lung transition and the dose decreases at the lung-water transition, but these effects are minimal for B = 0.2 T. These results will contribute to evaluating the trade-off between magnetic field dose effects and image quality of MR-guided radiotherapy systems.

Magnetic-field-induced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength

International Nuclear Information System (INIS)

Raaijmakers, A J E; Raaymakers, B W; Lagendijk, J J W

2008-01-01

Several institutes are currently working on the development of a radiotherapy treatment system with online MR imaging (MRI) modality. The main difference between their designs is the magnetic field strength of the MRI system. While we have chosen a 1.5 Tesla (T) magnetic field strength, the Cross Cancer Institute in Edmonton will be using a 0.2 T MRI scanner and the company Viewray aims to use 0.3 T. The magnetic field strength will affect the severity of magnetic field dose effects, such as the electron return effect (ERE): considerable dose increase at tissue air boundaries due to returning electrons. This paper has investigated how the ERE dose increase depends on the magnetic field strength. Therefore, four situations where the ERE occurs have been simulated: ERE at the distal side of the beam, the lateral ERE, ERE in cylindrical air cavities and ERE in the lungs. The magnetic field comparison values were 0.2, 0.75, 1.5 and 3 T. Results show that, in general, magnetic field dose effects are reduced at lower magnetic field strengths. At the distal side, the ERE dose increase is largest for B = 0.75 T and depends on the irradiation field size for B = 0.2 T. The lateral ERE is strongest for B = 3 T but shows no effect for B = 0.2 T. Around cylindrical air cavities, dose inhomogeneities disappear if the radius of the cavity becomes small relative to the in-air radius of the secondary electron trajectories. At larger cavities (r > 1 cm), dose inhomogeneities exist for all magnetic field strengths. In water-lung-water phantoms, the ERE dose increase takes place at the water-lung transition and the dose decreases at the lung-water transition, but these effects are minimal for B = 0.2 T. These results will contribute to evaluating the trade-off between magnetic field dose effects and image quality of MR-guided radiotherapy systems

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

International Nuclear Information System (INIS)

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. - Highlights: • Fretting friction and wear characteristics of MRF is examined. • The friction coefficients increased with increasing magnetic field strength. • The coefficient of friction decreased with increasing oscillation frequency. • Wear volume and coefficient become worse with increasing magnetic field strength.

An Investigation Into the Relationship Between Maximum Isometric Strength and Vertical Jump Performance.

Science.gov (United States)

Thomas, Christopher; Jones, Paul A; Rothwell, James; Chiang, Chieh Y; Comfort, Paul

2015-08-01

Research has demonstrated a clear relationship between dynamic strength and vertical jump (VJ) performance; however, the relationship of isometric strength and VJ performance has been studied less extensively. The aim of this study was to determine the relationship between isometric strength and performance during the squat jump (SJ) and countermovement jump (CMJ). Twenty-two male collegiate athletes (mean ± SD; age = 21.3 ± 2.9 years; height = 175.63 ± 8.23 cm; body mass = 78.06 ± 10.77 kg) performed isometric midthigh pulls (IMTPs) to assess isometric peak force (IPF), maximum rate of force development, and impulse (IMP) (I100, I200, and I300). Force-time data, collected during the VJs, were used to calculate peak velocity, peak force (PF), peak power (PP), and jump height. Absolute IMTP measures of IMP showed the strongest correlations with VJ PF (r = 0.43-0.64; p ≤ 0.05) and VJ PP (r = 0.38-0.60; p ≤ 0.05). No statistical difference was observed in CMJ height (0.33 ± 0.05 m vs. 0.36 ± 0.05 m; p = 0.19; ES = -0.29) and SJ height performance (0.29 ± 0.06 m vs. 0.33 ± 0.05 m; p = 0.14; ES = -0.34) when comparing stronger to weaker athletes. The results of this study illustrate that absolute IPF and IMP are related to VJ PF and PP but not VJ height. Because stronger athletes did not jump higher than weaker athletes, dynamic strength tests may be more practical methods of assessing the relationships between relative strength levels and dynamic performance in collegiate athletes.

A General Stochastic Maximum Principle for SDEs of Mean-field Type

International Nuclear Information System (INIS)

Buckdahn, Rainer; Djehiche, Boualem; Li Juan

2011-01-01

We study the optimal control for stochastic differential equations (SDEs) of mean-field type, in which the coefficients depend on the state of the solution process as well as of its expected value. Moreover, the cost functional is also of mean-field type. This makes the control problem time inconsistent in the sense that the Bellman optimality principle does not hold. For a general action space a Peng’s-type stochastic maximum principle (Peng, S.: SIAM J. Control Optim. 2(4), 966–979, 1990) is derived, specifying the necessary conditions for optimality. This maximum principle differs from the classical one in the sense that here the first order adjoint equation turns out to be a linear mean-field backward SDE, while the second order adjoint equation remains the same as in Peng’s stochastic maximum principle.

A Maximum Muscle Strength Prediction Formula Using Theoretical Grade 3 Muscle Strength Value in Daniels et al.’s Manual Muscle Test, in Consideration of Age: An Investigation of Hip and Knee Joint Flexion and Extension

Directory of Open Access Journals (Sweden)

Hideyuki Usa

2017-01-01

Full Text Available This study attempted to develop a formula for predicting maximum muscle strength value for young, middle-aged, and elderly adults using theoretical Grade 3 muscle strength value (moment fair: Mf—the static muscular moment to support a limb segment against gravity—from the manual muscle test by Daniels et al. A total of 130 healthy Japanese individuals divided by age group performed isometric muscle contractions at maximum effort for various movements of hip joint flexion and extension and knee joint flexion and extension, and the accompanying resisting force was measured and maximum muscle strength value (moment max, Mm was calculated. Body weight and limb segment length (thigh and lower leg length were measured, and Mf was calculated using anthropometric measures and theoretical calculation. There was a linear correlation between Mf and Mm in each of the four movement types in all groups, excepting knee flexion in elderly. However, the formula for predicting maximum muscle strength was not sufficiently compatible in middle-aged and elderly adults, suggesting that the formula obtained in this study is applicable in young adults only.

Effects of magnetic field strength in the discharge channel on the performance of a multi-cusped field thruster

Directory of Open Access Journals (Sweden)

Peng Hu

2016-09-01

Full Text Available The performance characteristics of a Multi-cusped Field Thruster depending on the magnetic field strength in the discharge channel were investigated. Four thrusters with different outer diameters of the magnet rings were designed to change the magnetic field strength in the discharge channel. It is found that increasing the magnetic field strength could restrain the radial cross-field electron current and decrease the radial width of main ionization region, which gives rise to the reduction of propellant utilization and thruster performance. The test results in different anode voltage conditions indicate that both the thrust and anode efficiency are higher for the weaker magnetic field in the discharge channel.

47 CFR 73.184 - Groundwave field strength graphs.

Science.gov (United States)

2010-10-01

... copies of these tabulations call or write the Consumer Affairs Office, Federal Communications Commission... relative values of groundwave field strength over a plane earth as a function of the numerical distance p... earth weakens the field more rapidly than these plane earth curves would indicate. Thus, no attempt...

Magnetic Field Strength Evaluation Yu. S. Yefimov

Indian Academy of Sciences (India)

physical task is to evaluate the strength and topology of magnetic field in blazars and related ... polarization, spectral index of radiation, ratio of apparent velocity of the motion of matter along .... A detailed analysis of the evaluation of physical.

Hand grip strength and maximum peak expiratory flow: determinants of bone mineral density of adolescent students.

Science.gov (United States)

Cossio-Bolaños, Marco; Lee-Andruske, Cynthia; de Arruda, Miguel; Luarte-Rocha, Cristian; Almonacid-Fierro, Alejandro; Gómez-Campos, Rossana

2018-03-02

Maintaining and building healthy bones during the lifetime requires a complicated interaction between a number of physiological and lifestyle factors. Our goal of this study was to analyze the association between hand grip strength and the maximum peak expiratory flow with bone mineral density and content in adolescent students. The research team studied 1427 adolescent students of both sexes (750 males and 677 females) between the ages of 11.0 and 18.9 years in the Maule Region of Talca (Chile). Weight, standing height, sitting height, hand grip strength (HGS), and maximum peak expiratory flow (PEF) were measured. Furthermore, bone mineral density (BMD) and total body bone mineral content (BMC) were determined by using the Dual-Energy X-Ray Absorptiometry (DXA). Hand grip strength and PEF were categorized in tertiles (lowest, middle, and highest). Linear regression was performed in steps to analyze the relationship between the variables. Differences between categories were determined through ANOVA. In males, the hand grip strength explained 18-19% of the BMD and 20-23% of the BMC. For the females, the percentage of variation occurred between 12 and 13% of the BMD and 17-18% of the BMC. The variation of PEF for the males was observed as 33% of the BMD and 36% of the BMC. For the females, both the BMD and BMC showed a variation of 19%. The HGS and PEF were divided into three categories (lowest, middle, and highest). In both cases, significant differences occurred in bone density health between the three categories. In conclusion, the HGS and the PEF related positively to the bone density health of both sexes of adolescent students. The adolescents with poor values for hand grip strength and expiratory flow showed reduced values of BMD and BMC for the total body. Furthermore, the PEF had a greater influence on bone density health with respect to the HGS of the adolescents of both sexes.

Estimating the Magnetic Field Strength in Hot Jupiters

Energy Technology Data Exchange (ETDEWEB)

Yadav, Rakesh K. [Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138 (United States); Thorngren, Daniel P., E-mail: rakesh_yadav@fas.harvard.edu [Department of Physics, University of California, Santa Cruz, CA (United States)

2017-11-01

A large fraction of known Jupiter-like exoplanets are inflated as compared to Jupiter. These “hot” Jupiters orbit close to their parent star and are bombarded with intense starlight. Many theories have been proposed to explain their radius inflation and several suggest that a small fraction of the incident starlight is injected into the planetary interior, which helps to puff up the planet. How will such energy injection affect the planetary dynamo? In this Letter, we estimate the surface magnetic field strength of hot Jupiters using scaling arguments that relate energy available in planetary interiors to the dynamo-generated magnetic fields. We find that if we take into account the energy injected in the planetary interior that is sufficient to inflate hot Jupiters to observed radii, then the resulting dynamo should be able generate magnetic fields that are more than an order of magnitude stronger than the Jovian values. Our analysis highlights the potential fundamental role of the stellar light in setting the field strength in hot Jupiters.

Methodological aspects of functional neuroimaging at high field strength: a critical review

International Nuclear Information System (INIS)

Scheef, L.; Landsberg, M.W.; Boecker, H.

2007-01-01

The last few years have proven that high field magnetic resonance imaging (MRI) is superior in nearly every way to conventional equipment up to 1.5 tesla (T). Following the global success of 3T-scanners in research institutes and medical practices, a new generation of MRI devices with field strengths of 7T and higher is now on the horizon. The introduction of ultra high fields has brought MRI technology closer to the physical limitations and increasingly greater costs are required to achieve this goal. This article provides a critical overview of the advantages and problems of functional neuroimaging using ultra high field strengths. This review is principally limited to T2*-based functional imaging techniques not dependent on contrast agents. The main issues include the significance of high field technology with respect to SNR, CNR, resolution, and sequences, as well as artifacts, noise exposure, and SAR. Of great relevance is the discussion of parallel imaging, which will presumably determine the further development of high and ultra high field strengths. Finally, the importance of high field strengths for functional neuroimaging is explained by selected publications. (orig.)

Pulsar Emission Geometry and Accelerating Field Strength

Science.gov (United States)

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

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

Science.gov (United States)

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%.

The Effects of a Maximal Power Training Cycle on the Strength, Maximum Power, Vertical Jump Height and Acceleration of High-Level 400-Meter Hurdlers

Science.gov (United States)

Balsalobre-Fernández, Carlos; Tejero-González, Carlos Mª; del Campo-Vecino, Juan; Alonso-Curiel, Dionisio

2013-01-01

The aim of this study was to determine the effects of a power training cycle on maximum strength, maximum power, vertical jump height and acceleration in seven high-level 400-meter hurdlers subjected to a specific training program twice a week for 10 weeks. Each training session consisted of five sets of eight jump-squats with the load at which each athlete produced his maximum power. The repetition maximum in the half squat position (RM), maximum power in the jump-squat (W), a squat jump (SJ), countermovement jump (CSJ), and a 30-meter sprint from a standing position were measured before and after the training program using an accelerometer, an infra-red platform and photo-cells. The results indicated the following statistically significant improvements: a 7.9% increase in RM (Z=−2.03, p=0.021, δc=0.39), a 2.3% improvement in SJ (Z=−1.69, p=0.045, δc=0.29), a 1.43% decrease in the 30-meter sprint (Z=−1.70, p=0.044, δc=0.12), and, where maximum power was produced, a change in the RM percentage from 56 to 62% (Z=−1.75, p=0.039, δc=0.54). As such, it can be concluded that strength training with a maximum power load is an effective means of increasing strength and acceleration in high-level hurdlers. PMID:23717361

Dependence of Brownian and Néel relaxation times on magnetic field strength

International Nuclear Information System (INIS)

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

2014-01-01

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

Critical electric field for maximum tunability in nonlinear dielectrics

Science.gov (United States)

Akdogan, E. K.; Safari, A.

2006-09-01

The authors develop a self-consistent thermodynamic theory to compute the critical electric field at which maximum tunability is attained in a nonlinear dielectric. They then demonstrate that the stored electrostatic free energy functional has to be expanded at least up to the sixth order in electric field so as to define the critical field, and show that it depends solely on the fourth and sixth order permittivities. They discuss the deficiency of the engineering tunability metric in describing nonlinear dielectric phenomena, introduce a critical field renormalized tunability parameter, and substantiate the proposed formalism by computing the critical electric field for prototypical 0.9Pb(Mg1/3,Nb2/3)-0.1PbTiO3 and Ba(Ti0.85,Sn0.15)O3 paraelectrics.

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

Science.gov (United States)

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''.

A field like today's? The strength of the geomagnetic field 1.1 billion years ago

Science.gov (United States)

Sprain, Courtney J.; Swanson-Hysell, Nicholas L.; Fairchild, Luke M.; Gaastra, Kevin

2018-06-01

Palaeomagnetic data from ancient rocks are one of the few types of observational data that can be brought to bear on the long-term evolution of Earth's core. A recent compilation of palaeointensity estimates from throughout Earth history has been interpreted to indicate that Earth's magnetic field strength increased in the Mesoproterozoic (between 1.5 and 1.0 billion years ago), with this increase taken to mark the onset of inner core nucleation. However, much of the data within the Precambrian palaeointensity database are from Thellier-style experiments with non-ideal behaviour that manifests in results such as double-slope Arai plots. Choices made when interpreting these data may significantly change conclusions about long-term trends in the intensity of Earth's geomagnetic field. In this study, we present new palaeointensity results from volcanics of the ˜1.1-billion-year-old North American Midcontinent Rift. While most of the results exhibit non-ideal double-slope or sagging behaviour in Arai plots, some flows have more ideal single-slope behaviour leading to palaeointensity estimates that may be some of the best constraints on the strength of Earth's field for this time. Taken together, new and previously published palaeointensity data from the Midcontinent Rift yield a median field strength estimate of 56.0 ZAm2—very similar to the median for the past 300 Myr. These field strength estimates are distinctly higher than those for the preceding billion years (Ga) after excluding ca. 1.3 Ga data that may be biased by non-ideal behaviour—consistent with an increase in field strength in the late Mesoproterozoic. However, given that ˜90 per cent of palaeointensity estimates from 1.1 to 0.5 Ga come from the Midcontinent Rift, it is difficult to evaluate whether these high values relative to those estimated for the preceding billion years are the result of a stepwise, sustained increase in dipole moment. Regardless, palaeointensity estimates from the Midcontinent

Maximum repulsed magnetization of a bulk superconductor with low pulsed field

International Nuclear Information System (INIS)

Tsuchimoto, M.; Kamijo, H.; Fujimoto, H.

2005-01-01

Pulsed field magnetization of a bulk high-T c superconductor (HTS) is important technique especially for practical applications of a bulk superconducting magnet. Full magnetization is not obtained for low pulsed field and trapped field is decreased by reversed current in the HTS. The trapped field distribution by repulsed magnetization was previously reported in experiments with temperature control. In this study, repulsed magnetization technique with the low pulsed field is numerically analyzed under assumption of variable shielding current by the temperature control. The shielding current densities are discussed to obtain maximum trapped field by two times of low pulsed field magnetizations

Mapping the absolute electromagnetic field strength of individual field components inside a photonic crystal

NARCIS (Netherlands)

Denis, T.; Reijnders, B.; Lee, J.H.H.; Vos, Willem L.; Boller, Klaus J.; van der Slot, Petrus J.M.

2013-01-01

We present a method to map the absolute electromagnetic field strength inside photonic crystals. We demonstrate our method by applying it to map the electric field component Ez of a two-dimensional photonic crystal slab at microwave frequencies. The slab is placed between two mirrors to create a

Optical field-strength polarization of two-mode single-photon states

Energy Technology Data Exchange (ETDEWEB)

Linares, J; Nistal, M C; Barral, D; Moreno, V, E-mail: suso.linares.beiras@usc.e [Optics Area, Department of Applied Physics, Faculty of Physics and School of Optics and Optometry, University of Santiago de Compostela, Campus Universitario Sur s/n, 15782-Santiago de Compostela, Galicia (Spain)

2010-09-15

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 the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

Optical field-strength polarization of two-mode single-photon states

International Nuclear Information System (INIS)

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 the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

Relationship between maximum dynamic force of inferior members and body balance in strength training apprentices

Directory of Open Access Journals (Sweden)

Ariane Martins

2010-08-01

Full Text Available The relationship between force and balance show controversy results and has directimplications in exercise prescription practice. The objective was to investigate the relationshipbetween maximum dynamic force (MDF of inferior limbs and the static and dynamic balances.Participated in the study 60 individuals, with 18 to 24 years old, strength training apprentices.The MDF was available by mean the One Maximum Repetition (1MR in “leg press” and “kneeextension” and motor testes to available of static and dynamic balances. The correlation testsand multiple linear regression were applied. The force and balance variables showed correlationin females (p=0.038. The corporal mass and static balance showed correlation for the males(p=0.045. The explication capacity at MDF and practices time were small: 13% for staticbalance in males, 18% and 17%, respectively, for static and dynamic balance in females. Inconclusion: the MDF of inferior limbs showed low predictive capacity for performance in staticand dynamic balances, especially for males.

Maximum field capability of energy saver superconducting magnets

International Nuclear Information System (INIS)

Turkot, F.; Cooper, W.E.; Hanft, R.; McInturff, A.

1983-01-01

At an energy of 1 TeV the superconducting cable in the Energy Saver dipole magnets will be operating at ca. 96% of its nominal short sample limit; the corresponding number in the quadrupole magnets will be 81%. All magnets for the Saver are individually tested for maximum current capability under two modes of operation; some 900 dipoles and 275 quadrupoles have now been measured. The dipole winding is composed of four individually wound coils which in general come from four different reels of cable. As part of the magnet fabrication quality control a short piece of cable from both ends of each reel has its critical current measured at 5T and 4.3K. In this paper the authors describe and present the statistical results of the maximum field tests (including quench and cycle) on Saver dipole and quadrupole magnets and explore the correlation of these tests with cable critical current

Investigation of Vacuum Insulator Surface Dielectric Strength with Nanosecond Pulses

International Nuclear Information System (INIS)

Nunnally, W.C.; Krogh, M.; Williams, C.; Trimble, D.; Sampayan, S.; Caporaso, G.

2003-01-01

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

Field of first magnetic flux entry and pinning strength of superconductors for rf application measured with muon spin rotation

Science.gov (United States)

Junginger, T.; Abidi, S. H.; Maffett, R. D.; Buck, T.; Dehn, M. H.; Gheidi, S.; Kiefl, R.; Kolb, P.; Storey, D.; Thoeng, E.; Wasserman, W.; Laxdal, R. E.

2018-03-01

The performance of superconducting radiofrequency (SRF) cavities used for particle accelerators depends on two characteristic material parameters: field of first flux entry Hentry and pinning strength. The former sets the limit for the maximum achievable accelerating gradient, while the latter determines how efficiently flux can be expelled related to the maximum achievable quality factor. In this paper, a method based on muon spin rotation (μ SR ) is developed to probe these parameters on samples. It combines measurements from two different spectrometers, one being specifically built for these studies and samples of different geometries. It is found that annealing at 1400 °C virtually eliminates all pinning. Such an annealed substrate is ideally suited to measure Hentry of layered superconductors, which might enable accelerating gradients beyond bulk niobium technology.

Lattice Field Theory with the Sign Problem and the Maximum Entropy Method

Directory of Open Access Journals (Sweden)

Masahiro Imachi

2007-02-01

Full Text Available Although numerical simulation in lattice field theory is one of the most effective tools to study non-perturbative properties of field theories, it faces serious obstacles coming from the sign problem in some theories such as finite density QCD and lattice field theory with the θ term. We reconsider this problem from the point of view of the maximum entropy method.

Magnetic resonance imaging: effects of magnetic field strength

International Nuclear Information System (INIS)

Crooks, L.E.; Arakawa, M.; Hoenninger, J.; McCarten, B.; Watts, J.; Kaufman, L.

1984-01-01

Magnetic resonance images of the head, abdomen, and pelvis of normal adult men were obtained using varying magnetic field strength, and measurements of T1 and T2 relaxations and of signal-to-noise (SN) ratios were determined. For any one spin echo sequence, gray/white matter contrast decreases and muscle/fat contrast increases with field. SN levels rise rapidly up to 3.0 kgauss and then change more slowly, actually dropping for muscle. The optimum field for magnetic resonance imaging depends on tissue type, body part, and imaging sequence, so that it does not have a unique value. Magnetic resonance systems that operate in the 3.0-5.0 kgauss range achieve most or all of the gains that can be achieved by higher magnetic fields

Modelling and assessment of the electric field strength caused by mobile phone to the human head.

Science.gov (United States)

Buckus, Raimondas; Strukcinskiene, Birute; Raistenskis, Juozas; Stukas, Rimantas

2016-06-01

Electromagnetic field exposure is the one of the most important physical agents that actively affects live organisms and environment. Active use of mobile phones influences the increase of electromagnetic field radiation. The aim of the study was to measure and assess the electric field strength caused by mobile phones to the human head. In this paper the software "COMSOL Multiphysics" was used to establish the electric field strength created by mobile phones around the head. The second generation (2G) Global System for Mobile (GSM) phones that operate in the frequency band of 900 MHz and reach the power of 2 W have a stronger electric field than (2G) GSM mobile phones that operate in the higher frequency band of 1,800 MHz and reach the power up to 1 W during conversation. The third generation of (3G) UMTS smart phones that effectively use high (2,100 MHz) radio frequency band emit the smallest electric field strength values during conversation. The highest electric field strength created by mobile phones is around the ear, i.e. the mobile phone location. The strength of mobile phone electric field on the phantom head decreases exponentially while moving sidewards from the center of the effect zone (the ear), and constitutes 1-12% of the artificial head's surface. The highest electric field strength values of mobile phones are associated with their higher power, bigger specific energy absorption rate (SAR) and lower frequency of mobile phone. The stronger electric field emitted by the more powerful mobile phones takes a higher percentage of the head surface. The highest electric field strength created by mobile phones is distributed over the user's ear.

Cyclotron Lines: From Magnetic Field Strength Estimators to ...

Indian Academy of Sciences (India)

Chandreyee Maitra

2017-09-12

Sep 12, 2017 ... context can provide, to build a complete picture for the physics of accretion and ... cesses which occur near the NS surface, where the ... CRSF) which is the focal point of discussion in this arti- .... first direct measurement of the magnetic field strength of .... The above model requires a gradient in the magnetic.

Power spectrum of the geomagnetic field by the maximum entropy method

International Nuclear Information System (INIS)

Kantor, I.J.; Trivedi, N.B.

1980-01-01

Monthly mean values of Vassouras (state of Rio de Janeiro) geomagnetic field are analyzed us the maximum entropy method. The method is described and compared with other methods of spectral analysis, and its advantages and disadvantages are presented. (Author) [pt

The maximum possible stress intensity factor for a crack in an unknown residual stress field

International Nuclear Information System (INIS)

Coules, H.E.; Smith, D.J.

2015-01-01

Residual and thermal stress fields in engineering components can act on cracks and structural flaws, promoting or inhibiting fracture. However, these stresses are limited in magnitude by the ability of materials to sustain them elastically. As a consequence, the stress intensity factor which can be applied to a given defect by a self-equilibrating stress field is also limited. We propose a simple weight function method for determining the maximum stress intensity factor which can occur for a given crack or defect in a one-dimensional self-equilibrating stress field, i.e. an upper bound for the residual stress contribution to K I . This can be used for analysing structures containing defects and subject to residual stress without any information about the actual stress field which exists in the structure being analysed. A number of examples are given, including long radial cracks and fully-circumferential cracks in thick-walled hollow cylinders containing self-equilibrating stresses. - Highlights: • An upper limit to the contribution of residual stress to stress intensity factor. • The maximum K I for self-equilibrating stresses in several geometries is calculated. • A weight function method can determine this maximum for 1-dimensional stress fields. • Simple MATLAB scripts for calculating maximum K I provided as supplementary material.

Modelling and assessment of the electric field strength caused by mobile phone to the human head

Directory of Open Access Journals (Sweden)

Buckus Raimondas

2016-01-01

Full Text Available Background/Aim. Electromagnetic field exposure is the one of the most important physical agents that actively affects live organisms and environment. Active use of mobile phones influences the increase of electromagnetic field radiation. The aim of the study was to measure and assess the electric field strength caused by mobile phones to the human head. Methods. In this paper the software “COMSOL Multiphysics” was used to establish the electric field strength created by mobile phones around the head. Results. The second generation (2G Global System for Mobile (GSM phones that operate in the frequency band of 900 MHz and reach the power of 2 W have a stronger electric field than (2G GSM mobile phones that operate in the higher frequency band of 1,800 MHz and reach the power up to 1 W during conversation. The third generation of (3G UMTS smart phones that effectively use high (2,100 MHz radio frequency band emit the smallest electric field strength values during conversation. The highest electric field strength created by mobile phones is around the ear, i.e. the mobile phone location. The strength of mobile phone electric field on the phantom head decreases exponentially while moving sidewards from the center of the effect zone (the ear, and constitutes 1-12% of the artificial head’s surface. Conclusion. The highest electric field strength values of mobile phones are associated with their higher power, bigger specific energy absorption rate (SAR and lower frequency of mobile phone. The stronger electric field emitted by the more powerful mobile phones takes a higher percentage of the head surface. The highest electric field strength created by mobile phones is distributed over the user ear.

The effect of electric field maximum on the Rabi flopping and generated higher frequency spectra

International Nuclear Information System (INIS)

Niu Yueping; Cui Ni; Xiang Yang; Li Ruxin; Gong Shangqing; Xu Zhizhan

2008-01-01

We investigate the effect of the electric field maximum on the Rabi flopping and the generated higher frequency spectra properties by solving Maxwell-Bloch equations without invoking any standard approximations. It is found that the maximum of the electric field will lead to carrier-wave Rabi flopping (CWRF) through reversion dynamics which will be more evident when the applied field enters the sub-one-cycle regime. Therefore, under the interaction of sub-one-cycle pulses, the Rabi flopping follows the transient electric field tightly through the oscillation and reversion dynamics, which is in contrast to the conventional envelope Rabi flopping. Complete or incomplete population inversion can be realized through the control of the carrier-envelope phase (CEP). Furthermore, the generated higher frequency spectra will be changed from distinct to continuous or irregular with the variation of the CEP. Our results demonstrate that due to the evident maximum behavior of the electric field, pulses with different CEP give rise to different CWRFs, and then different degree of interferences lead to different higher frequency spectral features.

Carboxylated magnetic nanoparticles as MRI contrast agents: Relaxation measurements at different field strengths

Energy Technology Data Exchange (ETDEWEB)

Jedlovszky-Hajdu, Angela, E-mail: angela.hajdu@net.sote.hu [Laboratory of Nanochemistry, Department of Biophysics and Radiation Biology, Semmelweis University, Nagyvarad Sq 4, H-1089 Budapest (Hungary); Tombacz, Etelka, E-mail: tombacz@chem.u-szeged.hu [Department of Physical Chemistry and Material Science, University of Szeged, Aradi Vt. Sq 1, Szeged 6720 (Hungary); Banyai, Istvan, E-mail: banyai.istvan@science.unideb.hu [Department of Colloid and Environmental Chemistry, University of Debrecen (Hungary); Babos, Magor, E-mail: babosmagor@yahoo.com [Euromedic Diagnostics Szeged Ltd., Semmelweis St 6, Szeged 6720 (Hungary); Palko, Andras, E-mail: palko@radio.szote.u-szeged.hu [Faculty of Medicine, Department of Radiology, University of Szeged (Hungary)

2012-09-15

At the moment the biomedical applications of magnetic fluids are the subject of intensive scientific interest. In the present work, magnetite nanoparticles (MNPs) were synthesized and stabilized in aqueous medium with different carboxylic compounds (citric acid (CA), polyacrylic acid (PAA), and sodium oleate (NaOA)), in order to prepare well stabilized magnetic fluids (MFs). The magnetic nanoparticles can be used in the magnetic resonance imaging (MRI) as contrast agents. Magnetic resonance relaxation measurements of the above MFs were performed at different field strengths (i.e., 0.47, 1.5 and 9.4 T) to reveal the field strength dependence of their magnetic responses, and to compare them with that of ferucarbotran, a well-known superparamagnetic contrast agent. The measurements showed characteristic differences between the tested magnetic fluids stabilized by carboxylic compounds and ferucarbotran. It is worthy of note that our magnetic fluids have the highest r2 relaxivities at the field strength of 1.5 T, where the most of the MRI works in worldwide. - Highlights: Black-Right-Pointing-Pointer Magnetic resonance relaxation measurements were done at different field strengths. Black-Right-Pointing-Pointer Results show characteristic differences between the tested carboxylated MFs. Black-Right-Pointing-Pointer r1 and r2 relaxivities depend on the thickness of the protecting layer. Black-Right-Pointing-Pointer MFs have high r2/r1 ratios at each magnetic field.

Unification of field theory and maximum entropy methods for learning probability densities

OpenAIRE

Kinney, Justin B.

2014-01-01

The need to estimate smooth probability distributions (a.k.a. probability densities) from finite sampled data is ubiquitous in science. Many approaches to this problem have been described, but none is yet regarded as providing a definitive solution. Maximum entropy estimation and Bayesian field theory are two such approaches. Both have origins in statistical physics, but the relationship between them has remained unclear. Here I unify these two methods by showing that every maximum entropy de...

Impact of maximum TF magnetic field on performance and cost of an advanced physics tokamak

International Nuclear Information System (INIS)

Reid, R.L.

1983-01-01

Parametric studies were conducted using the Fusion Engineering Design Center (FEDC) Tokamak Systems Code to investigate the impact of variation in the maximum value of the field at the toroidal field (TF) coils on the performance and cost of a low q/sub psi/, quasi-steady-state tokamak. Marginal ignition, inductive current startup plus 100 s of inductive burn, and a constant value of epsilon (inverse aspect ratio) times beta poloidal were global conditions imposed on this study. A maximum TF field of approximately 10 T was found to be appropriate for this device

3D Global Coronal Density Structure and Associated Magnetic Field near Solar Maximum

Energy Technology Data Exchange (ETDEWEB)

Kramar, Maxim [Physics Department, The Catholic University of America, Washington, DC (United States); Airapetian, Vladimir [Department of Physics and Astronomy, George Mason University, Fairfax, VA (United States); NASA/Goddard Space Flight Center, Code 671, Greenbelt, MD (United States); Lin, Haosheng, E-mail: vladimir.airapetian@nasa.gov [College of Natural Sciences, Institute for Astronomy, University of Hawaii at Manoa, Pukalani, HI (United States)

2016-08-09

Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal dynamic phenomena at all scales. We employ STEREO/COR1 data obtained near maximum of solar activity in December 2012 (Carrington rotation, CR 2131) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from 1.5 to 4 R{sub ⊙} using a tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 Å band obtained by tomography for the same CR period. We find that the magnetic field configuration during CR 2131 has a tendency to become radially open at heliocentric distances below ~2.5 R{sub ⊙}. We compared the reconstructed 3D coronal structures over the CR near the solar maximum to the one at deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the accuracy of the magnetic field approximations for coronal modeling.

3D Global Coronal Density Structure and Associated Magnetic Field near Solar Maximum

Directory of Open Access Journals (Sweden)

Maxim Kramar

2016-08-01

Full Text Available Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal dynamic phenomena at all scales. We employ STEREO/COR1 data obtained near maximum of solar activity in December 2012 (Carrington rotation, CR 2131 to retrieve and analyze the three-dimensional (3D coronal electron density in the range of heights from $1.5$ to $4 R_odot$ using a tomography method and qualitatively deduce structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in 195 AA band obtained by tomography for the same CR period. We find that the magnetic field configuration during CR 2131 has a tendency to become radially open at heliocentric distances below $sim 2.5 R_odot$. We compared the reconstructed 3D coronal structures over the CR near the solar maximum to the one at deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal field models and test the accuracy of the magnetic field approximations for coronal modeling.

F2 layer characteristics and electrojet strength over an equatorial station

Science.gov (United States)

Adebesin, B. O.; Adeniyi, J. O.; Adimula, I. A.; Reinisch, B. W.; Yumoto, K.

2013-09-01

The data presented in this work describes the diurnal and seasonal variation in hmF2, NmF2, and the electrojet current strength over an African equatorial station during a period of low solar activity. The F2 region horizontal magnetic element H revealed that the Solar quiet Sq(H) daily variation rises from early morning period to maximum around local noon and falls to lower values towards evening. The F2 ionospheric current responsible for the magnetic field variations is inferred to build up at the early morning hours, attaining maximum strength around 1200 LT. The Sq variation across the entire months was higher during the daytime than nighttime. This is ascribed to the variability of the ionospheric parameters like conductivity and winds structure in this region. Seasonal daytime electrojet (EEJ) current strength for June solstice, March and September equinoxes, respectively had peak values ranging within 27-35 nT (at 1400 LT) , 30-40 nT (at 1200 LT) and 35-45 nT (at 1500 LT). The different peak periods of the EEJ strength were attributed to the combined effects of the peak electron density and electric field. Lastly, the EEJ strength was observed to be higher during the equinoxes than the solstice period.

Structural control of metamaterial oscillator strength and electric field enhancement at terahertz frequencies

DEFF Research Database (Denmark)

Keiser, G. R.; Seren, H. R.; Strikwerda, Andrew C.

2014-01-01

The design of artificial nonlinear materials requires control over internal resonant charge densities and local electric field distributions. We present a MM design with a structurally controllable oscillator strength and local electric field enhancement at terahertz frequencies. The MM consists...... of a split ring resonator (SRR) array stacked above an array of closed conducting rings. An in-plane, lateral shift of a half unit cell between the SRR and closed ring arrays results in an increase of the MM oscillator strength by a factor of 4 and a 40% change in the amplitude of the resonant electric field...

Maximum Langmuir Fields in Planetary Foreshocks Determined from the Electrostatic Decay Threshold

Science.gov (United States)

Robinson, P. A.; Cairns, Iver H.

1995-01-01

Maximum electric fields of Langmuir waves at planetary foreshocks are estimated from the threshold for electrostatic decay, assuming it saturates beam driven growth, and incorporating heliospheric variation of plasma density and temperature. Comparisons with spacecraft observations yields good quantitative agreement. Observations in type 3 radio sources are also in accord with this interpretation. A single mechanism can thus account for the highest fields of beam driven waves in both contexts.

Magnetic field strength dependence of the magnetostriction of rare-earth iron garnets

International Nuclear Information System (INIS)

Zvezdin, A.K.; Levitin, R.Z.; Popov, A.I.; Silant'ev, V.I.

1981-01-01

The magnetostriction of holmium-yttrium iron garnets Hosub(x)Ysub(3-x)Fesub(5)Osub(12) (x=3 or 1.05) is measured in pulsed magnetic fields up to 200 kOe at 78 K. It is shown that the magnetostriction constants lambda 111 and lambda 100 of these ferrimagnets depends on the magnetic field strength. The magnetostriction constant of the iron garnet Ho 3 Fe 5 O 12 increases and of the iron garnet Hosub(1.05)Ysub(1.95)Fesub(5)Osub(12) decreases with increase of the field strength. The field dependences of the anisotropic magnetostriction constants lambda 111 and lambda 100 for Hosub(1.05)Ysub(1.95)Fesub(5)Osub(12) are fundamentally different. Thus lambda 111 depends quadratically on the total effective field Hsub(eff) whereas lambda 100 depends almost linearly on Hsub(eff). A theoretical analysis of the magneto-elastic interaction in rare-earth iron garnets is carried out [ru

Magnetic-Field Dependence of Raman Coupling Strength in Ultracold "4"0K Atomic Fermi Gas

International Nuclear Information System (INIS)

Huang Liang-Hui; Wang Peng-Jun; Meng Zeng-Ming; Peng Peng; Chen Liang-Chao; Li Dong-Hao; Zhang Jing

2016-01-01

We experimentally demonstrate the relation of Raman coupling strength with the external bias magnetic field in degenerate Fermi gas of "4"0K atoms. Two Raman lasers couple two Zeeman energy levels, whose energy splitting depends on the external bias magnetic field. The Raman coupling strength is determined by measuring the Rabi oscillation frequency. The characteristics of the Rabi oscillation is to be damped after several periods due to Fermi atoms in different momentum states oscillating with different Rabi frequencies. The experimental results show that the Raman coupling strength will decrease as the external bias magnetic field increases, which is in good agreement with the theoretical prediction. (paper)

Contribution of Field Strength Gradients to the Net Vertical Current of Active Regions

Science.gov (United States)

Vemareddy, P.

2017-12-01

We examined the contribution of field strength gradients for the degree of net vertical current (NVC) neutralization in active regions (ARs). We used photospheric vector magnetic field observations of AR 11158 obtained by Helioseismic and Magnetic Imager on board SDO and Hinode. The vertical component of the electric current is decomposed into twist and shear terms. The NVC exhibits systematic evolution owing to the presence of the sheared polarity inversion line between rotating and shearing magnetic regions. We found that the sign of shear current distribution is opposite in dominant pixels (60%–65%) to that of twist current distribution, and its time profile bears no systematic trend. This result indicates that the gradient of magnetic field strength contributes to an opposite signed, though smaller in magnitude, current to that contributed by the magnetic field direction in the vertical component of the current. Consequently, the net value of the shear current is negative in both polarity regions, which when added to the net twist current reduces the direct current value in the north (B z > 0) polarity, resulting in a higher degree of NVC neutralization. We conjecture that the observed opposite signs of shear and twist currents are an indication, according to Parker, that the direct volume currents of flux tubes are canceled by their return currents, which are contributed by field strength gradients. Furthermore, with the increase of spatial resolution, we found higher values of twist, shear current distributions. However, the resolution effect is more useful in resolving the field strength gradients, and therefore suggests more contribution from shear current for the degree of NVC neutralization.

Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength

Directory of Open Access Journals (Sweden)

J. S. Pickett

2004-07-01

Full Text Available Isolated electrostatic structures are observed throughout much of the 4R_E by 19.6R_E Cluster orbit. These structures are observed in the Wideband plasma wave instrument's waveform data as bipolar pulses (one positive and one negative peak in the electric field amplitude and tripolar pulses (two positive and one negative peak, or vice versa. These structures are observed at all of the boundary layers, in the solar wind and magnetosheath, and along auroral field lines at 4.5-6.5R_E. Using the Wideband waveform data from the various Cluster spacecraft we have carried out a survey of the amplitudes and time durations of these structures and how these quantities vary with the local magnetic field strength. Such a survey has not been carried out before, and it reveals certain characteristics of solitary structures in a finite magnetic field, a topic still inadequately addressed by theories. We find that there is a broad range of electric field amplitudes at any specific magnetic field strength, and there is a general trend for the electric field amplitudes to increase as the strength of the magnetic field increases over a range of 5 to 500nT. We provide a possible explanation for this trend that relates to the structures being Bernstein-Greene-Kruskal mode solitary waves. There is no corresponding dependence of the duration of the structures on the magnetic field strength, although a plot of these two quantities reveals the unexpected result that with the exception of the magnetosheath, all of the time durations for all of the other regions are comparable, whereas the magnetosheath time durations clearly are in a different category of much smaller time duration. We speculate that this implies that the structures are much smaller in size. The distinctly different pulse durations for the magnetosheath pulses indicate the possibility that the pulses are generated by a mechanism which is different

Isolated electrostatic structures observed throughout the Cluster orbit: relationship to magnetic field strength

Directory of Open Access Journals (Sweden)

J. S. Pickett

2004-07-01

Full Text Available Isolated electrostatic structures are observed throughout much of the 4RE by 19.6RE Cluster orbit. These structures are observed in the Wideband plasma wave instrument's waveform data as bipolar pulses (one positive and one negative peak in the electric field amplitude and tripolar pulses (two positive and one negative peak, or vice versa. These structures are observed at all of the boundary layers, in the solar wind and magnetosheath, and along auroral field lines at 4.5-6.5RE. Using the Wideband waveform data from the various Cluster spacecraft we have carried out a survey of the amplitudes and time durations of these structures and how these quantities vary with the local magnetic field strength. Such a survey has not been carried out before, and it reveals certain characteristics of solitary structures in a finite magnetic field, a topic still inadequately addressed by theories. We find that there is a broad range of electric field amplitudes at any specific magnetic field strength, and there is a general trend for the electric field amplitudes to increase as the strength of the magnetic field increases over a range of 5 to 500nT. We provide a possible explanation for this trend that relates to the structures being Bernstein-Greene-Kruskal mode solitary waves. There is no corresponding dependence of the duration of the structures on the magnetic field strength, although a plot of these two quantities reveals the unexpected result that with the exception of the magnetosheath, all of the time durations for all of the other regions are comparable, whereas the magnetosheath time durations clearly are in a different category of much smaller time duration. We speculate that this implies that the structures are much smaller in size. The distinctly different pulse durations for the magnetosheath pulses indicate the possibility that the pulses are generated by a mechanism which is different from the mechanism operating in other regions.

Investigation of the radiation level and electromagnetic field strength in sample of Damascus schools

International Nuclear Information System (INIS)

Shweikani, R.; Abukassem, I.; Raja, G.; Algamdi, H.

2009-12-01

The aim of this work is to determine radon concentration and natural gamma dose rate, and to measure the electromagnetic fields (EMFs) level produced by electric power lines and also mobile phone base station inside some elementary and preparatory schools in old town during two terms (studding terms and summer break). Results showed that most of the obtained values were less than 200 Bq/m 3 the action levels, but there were some classrooms concentrations which are more than 200 Bq/m 3 . These high values may be due to building materials, radon concentration in the soil and poor ventilation. It has been noticed that radon concentrations during the second term (summer) were higher than the first term. This may be due to the poor ventilation as schools are closed during summer break. The results showed also decreasing in radon concentration with increasing height of the floor, and radon concentration in old schools is higher than modern ones. EMFs levels in ground and first floors were higher than second floor; the maximum detected values exceeded 50 V/m and 270 mA/m for electric and magnetic field strength respectively, and 0.5 μT for magnetic flux density. Mobile microwave radiation level was relatively low in all positions, and signal increases with floor height. Finally, no observable correlation between the measured electromagnetic fields and the radon concentration were established.

Short-term Periodization Models: Effects on Strength and Speed-strength Performance.

Science.gov (United States)

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

Impact of high strength electromagnetic fields generated by Tesla transformer on plant cell ultrastructure

Directory of Open Access Journals (Sweden)

Anna Rusakova

2017-09-01

Full Text Available Non-thermal effects of direct electric fields and alternating electromagnetic fields (EMF have been successfully used in a number of studies and applications in agriculture and biotechnology. Among different kinds of high strength EMF generators, the Tesla transformer (TT is known as a widely applied, low cost, and troubleproof device, which generates EMF in the range of 2–8 MHz. Despite of a number of developed and perspective applications of high strength EMFs in agriculture and biotechnology, the EMFs generated by TT, as well as the 1–50 MHz range of high strength EMF still remain unexplored in the fields of plant physiology, ultrastructure studies and biochemistry. In this work, we have shown that TT-EMFs (4 MHz induced fast stem and petiole bending, disappearance of cell organelles, vacuolar membranes, and increase of a non-photochemical chlorophyll fluorescence quenching in petioles. It is intriguing that such fatal effects can be evoked in plants by EMFs which are well known as harmless for man at the applied strength and frequency.

An Ensemble Learning for Predicting Breakdown Field Strength of Polyimide Nanocomposite Films

Directory of Open Access Journals (Sweden)

Hai Guo

2015-01-01

Full Text Available Using the method of Stochastic Gradient Boosting, ten SMO-SVR are constructed into a strong prediction model (SGBS model that is efficient in predicting the breakdown field strength. Adopting the method of in situ polymerization, thirty-two samples of nanocomposite films with different percentage compositions, components, and thicknesses are prepared. Then, the breakdown field strength is tested by using voltage test equipment. From the test results, the correlation coefficient (CC, the mean absolute error (MAE, the root mean squared error (RMSE, the relative absolute error (RAE, and the root relative squared error (RRSE are 0.9664, 14.2598, 19.684, 22.26%, and 25.01% with SGBS model. The result indicates that the predicted values fit well with the measured ones. Comparisons between models such as linear regression, BP, GRNN, SVR, and SMO-SVR have also been made under the same conditions. They show that CC of the SGBS model is higher than those of other models. Nevertheless, the MAE, RMSE, RAE, and RRSE of the SGBS model are lower than those of other models. This demonstrates that the SGBS model is better than other models in predicting the breakdown field strength of polyimide nanocomposite films.

Gauge-invariant scalar and field strength correlators in 3d

CERN Document Server

Laine, Mikko

1998-01-01

Gauge-invariant non-local scalar and field strength operators have been argued to have significance, e.g., as a way to determine the behaviour of the screened static potential at large distances, as order parameters for confinement, as input parameters in models of confinement, and as gauge-invariant definitions of light constituent masses in bound state systems. We measure such "correlators" in the 3d pure SU(2) and SU(2)+Higgs models on the lattice. We extract the corresponding mass parameters and discuss their scaling and physical interpretation. We find that the finite part of the MS-bar scheme mass measured from the field strength correlator is large, more than half the glueball mass. We also determine the non-perturbative contribution to the Debye mass in the 4d finite T SU(2) gauge theory with a method due to Arnold and Yaffe, finding $\\delta m_D\\approx 1.06(4)g^2T$.

Magnetic field deformation due to electron drift in a Hall thruster

Directory of Open Access Journals (Sweden)

Han Liang

2017-01-01

Full Text Available The strength and shape of the magnetic field are the core factors in the design of the Hall thruster. However, Hall current can affect the distribution of static magnetic field. In this paper, the Particle-In-Cell (PIC method is used to obtain the distribution of Hall current in the discharge channel. The Hall current is separated into a direct and an alternating part to calculate the induced magnetic field using Finite Element Method Magnetics (FEMM. The results show that the direct Hall current decreases the magnetic field strength in the acceleration region and also changes the shape of the magnetic field. The maximum reduction in radial magnetic field strength in the exit plane is 10.8 G for an anode flow rate of 15 mg/s and the maximum angle change of the magnetic field line is close to 3° in the acceleration region. The alternating Hall current induces an oscillating magnetic field in the whole discharge channel. The actual magnetic deformation is shown to contain these two parts.

Electric field strength in a silicon surface barrier detector with the presence of a dielectric plasma column

International Nuclear Information System (INIS)

Kanno, Ikuo

1994-01-01

The dynamic change of the electric field strength in a silicon surface barrier detector (SSBD) is studied. With the presence of a dielectric plasma column in the depletion layer of the SSBD, the electric field strength inside/outside the plasma column is suppressed/enhanced. As the length and the dielectric constant of the plasma column become shorter and smaller, the suppression and enhancement of the electric field strength become less. The electric field strength recovers the initial state, when the plasma column disappears. When the electrons and holes are inside/outside the dielectric plasma column, they have less/more electric potential than the one they have when there is no plasma column. During the movement of the electron/hole outside the plasma column to the positive/negative electrode, the enhanced electric field strength becomes smaller. Electron and hole pairs, which are the parts of the dielectric plasma column, arrive at positive and negative electrodes, having insufficient electric potential to induce the unit charge. This paper shows that the presence of a dielectric plasma column explains the main part of the residual defect in a SSBD. ((orig.))

Functional BOLD MRI: comparison of different field strengths in a motor task

International Nuclear Information System (INIS)

Meindl, T.; Born, C.; Britsch, S.; Reiser, M.; Schoenberg, S.

2008-01-01

The purpose was to evaluate the benefit of an increased field strength for functional magnetic resonance imaging in a motor task. Six right-handed volunteers were scanned at 1.5 T and 3.0 T using a motor task. Each experiment consisted of two runs with four activation blocks, each with right- and left-hand tapping. Analysis was done using BrainVoyagerQX registered . Differences between both field strengths concerning signal to noise (SNR), blood oxygen level-dependent (BOLD) signal change, functional sensitivity and BOLD contrast to noise (CNR) were tested using a paired t test. Delineation of activations and artifacts were graded by two independent readers. Results were further validated by means of a phantom study. The sensorimotor and premotor cortex, the supplementary motor area, subcortical and cerebellar structures were activated at each field strength. Additional activations of the right premotor cortex and right superior temporal gyrus were found at 3.0 T. Signal-to-noise, percentage of BOLD signal change, BOLD CNR and functional sensitivity improved at 3.0 T by a factor of up to 2.4. Functional imaging at 3.0 T results in detection of additional activated areas, increased SNR, BOLD signal change, functional sensitivity and BOLD CNR. (orig.)

Study of a permanent-magnet dipole with variable field strength and polarity

International Nuclear Information System (INIS)

Honma, Toshihiro

1996-01-01

A proto-type dipole magnet employing permanent-magnet rods has been designed and constructed. The magnet is able to change the magnetic field strength continuously as well as the polarity of the field direction by rotating the rods. The magnet has a special advantage of high-field production within a small open space available. The magnet of this type will be used for beam steering at an extraction channel for a planned negative-ion acceleration in our cyclotron. The first important objective at the exit channel is to steer the beam extracted from the cyclotron by some dipole magnet onto the optical axis of a new beam line to be constructed. This is not a trivial task because available open space is too small to install a coil-type magnet. One of the selections is to use a permanent-magnet dipole because such a magnet is expected to provide a very high field in a small space when compared with a coil-type magnet. A proto-type permanent-magnet dipole (PMD) with variable field strength and polarity has been designed and constructed for such a purpose. (J.P.N.)

THE RELATIONSHIP BETWEEN MAXIMUM UNILATERAL SQUAT STRENGTH AND BALANCE IN YOUNG ADULT MEN AND WOMEN

Directory of Open Access Journals (Sweden)

Kevin McCurdy

2006-06-01

Full Text Available The purpose of this study was to determine the relationship between unilateral squat strength and measures of static balance to compare balance performance between the dominant and non-dominant leg. Seventeen apparently healthy men (mean mass 90.5 ± 20.9 kg and age 21.7 ± 1.8 yrs and 25 women (mean mass 62.2 ± 14.5 kg and age 21.9 ± 1.3 yrs completed the study. Weight bearing unilateral strength was measured with a 1RM modified unilateral squat on the dominant and non-dominant leg. The students completed the stork stand and wobble board tests to determine static balance on the dominant and non-dominant leg. Maximum time maintained in the stork stand position, on the ball of the foot with the uninvolved foot against the involved knee with hands on the hips, was recorded. Balance was measured with a 15 second wobble board test. No significant correlations were found between the measurements of unilateral balance and strength (r values ranged between -0.05 to 0.2 for the men and women. Time off balance was not significantly different between the subjects' dominant (men 1.1 ± 0.4 s; women 0.3 ± 0.1 s and non-dominant (men 0.9 ± 0.3 s; women 0.3 ± 0.1 s leg for the wobble board. Similar results were found for the time balanced during the stork stand test on the dominant (men 26.4 ± 6.3 s; women 24.1 ± 5.6 s and non-dominant (men 26.0 ± 5.7 s; women 21.3 ± 4.1 s leg. The data indicate that static balance and strength is unrelated in young adult men and women and gains made in one variable after training may not be associated with a change in performance of the other variable. These results also suggest that differences in static balance performance between legs can not be determined by leg dominance. Similar research is needed to compare contralateral leg balance in populations who participate in work or sport activities requiring repetitive asymmetrical use. A better understanding of contralateral balance performance will help

The influence of age, sex, bulb position, visual feedback, and the order of testing on maximum anterior and posterior tongue strength and endurance in healthy belgian adults.

Science.gov (United States)

Vanderwegen, Jan; Guns, Cindy; Van Nuffelen, Gwen; Elen, Rik; De Bodt, Marc

2013-06-01

This study collected data on the maximum anterior and posterior tongue strength and endurance in 420 healthy Belgians across the adult life span to explore the influence of age, sex, bulb position, visual feedback, and order of testing. Measures were obtained using the Iowa Oral Performance Instrument (IOPI). Older participants (more than 70 years old) demonstrated significantly lower strength than younger persons at the anterior and the posterior tongue. Endurance remains stable throughout the major part of life. Gender influence remains significant but minor throughout life, with males showing higher pressures and longer endurance. The anterior part of the tongue has both higher strength and longer endurance than the posterior part. Mean maximum tongue pressures in this European population seem to be lower than American values and are closer to Asian results. The normative data can be used for objective assessment of tongue weakness and subsequent therapy planning of dysphagic patients.

High resolution separations of charge variants and disulfide isomers of monoclonal antibodies and antibody drug conjugates using ultra-high voltage capillary electrophoresis with high electric field strength.

Science.gov (United States)

Henley, W Hampton; He, Yan; Mellors, J Scott; Batz, Nicholas G; Ramsey, J Michael; Jorgenson, James W

2017-11-10

Ultra-high voltage capillary electrophoresis with high electric field strength has been applied to the separation of the charge variants, drug conjugates, and disulfide isomers of monoclonal antibodies. Samples composed of many closely related species are difficult to resolve and quantify using traditional analytical instrumentation. High performance instrumentation can often save considerable time and effort otherwise spent on extensive method development. Ideally, the resolution obtained for a given CE buffer system scales with the square root of the applied voltage. Currently available commercial CE instrumentation is limited to an applied voltage of approximately 30kV and a maximum electric field strength of 1kV/cm due to design limitations. The instrumentation described here is capable of safely applying potentials of at least 120kV with electric field strengths over 2000V/cm, potentially doubling the resolution of the best conventional CE buffer/capillary systems while decreasing analysis time in some applications. Separations of these complex mixtures using this new instrumentation demonstrate the potential of ultra-high voltage CE to identify the presence of previously unresolved components and to reduce analysis time for complex mixtures of antibody variants and drug conjugates. Copyright © 2017 Elsevier B.V. All rights reserved.

A Stochastic Maximum Principle for Risk-Sensitive Mean-Field Type Control

KAUST Repository

Djehiche, Boualem; Tembine, Hamidou; Tempone, Raul

2015-01-01

In this paper we study mean-field type control problems with risk-sensitive performance functionals. We establish a stochastic maximum principle (SMP) for optimal control of stochastic differential equations (SDEs) of mean-field type, in which the drift and the diffusion coefficients as well as the performance functional depend not only on the state and the control but also on the mean of the distribution of the state. Our result extends the risk-sensitive SMP (without mean-field coupling) of Lim and Zhou (2005), derived for feedback (or Markov) type optimal controls, to optimal control problems for non-Markovian dynamics which may be time-inconsistent in the sense that the Bellman optimality principle does not hold. In our approach to the risk-sensitive SMP, the smoothness assumption on the value-function imposed in Lim and Zhou (2005) needs not be satisfied. For a general action space a Peng's type SMP is derived, specifying the necessary conditions for optimality. Two examples are carried out to illustrate the proposed risk-sensitive mean-field type SMP under linear stochastic dynamics with exponential quadratic cost function. Explicit solutions are given for both mean-field free and mean-field models.

A Stochastic Maximum Principle for Risk-Sensitive Mean-Field Type Control

KAUST Repository

Djehiche, Boualem

2015-02-24

In this paper we study mean-field type control problems with risk-sensitive performance functionals. We establish a stochastic maximum principle (SMP) for optimal control of stochastic differential equations (SDEs) of mean-field type, in which the drift and the diffusion coefficients as well as the performance functional depend not only on the state and the control but also on the mean of the distribution of the state. Our result extends the risk-sensitive SMP (without mean-field coupling) of Lim and Zhou (2005), derived for feedback (or Markov) type optimal controls, to optimal control problems for non-Markovian dynamics which may be time-inconsistent in the sense that the Bellman optimality principle does not hold. In our approach to the risk-sensitive SMP, the smoothness assumption on the value-function imposed in Lim and Zhou (2005) needs not be satisfied. For a general action space a Peng\\'s type SMP is derived, specifying the necessary conditions for optimality. Two examples are carried out to illustrate the proposed risk-sensitive mean-field type SMP under linear stochastic dynamics with exponential quadratic cost function. Explicit solutions are given for both mean-field free and mean-field models.

Hypercapnic normalization of BOLD fMRI: comparison across field strengths and pulse sequences

DEFF Research Database (Denmark)

Cohen, Eric R.; Rostrup, Egill; Sidaros, Karam

2004-01-01

to be more accurately localized and quantified based on changes in venous blood oxygenation alone. The normalized BOLD signal induced by the motor task was consistent across different magnetic fields and pulse sequences, and corresponded well with cerebral blood flow measurements. Our data suggest...... size, as well as experimental, such as pulse sequence and static magnetic field strength (B(0)). Thus, it is difficult to compare task-induced fMRI signals across subjects, field strengths, and pulse sequences. This problem can be overcome by normalizing the neural activity-induced BOLD fMRI response...... for global stimulation, subjects breathed a 5% CO(2) gas mixture. Under all conditions, voxels containing primarily large veins and those containing primarily active tissue (i.e., capillaries and small veins) showed distinguishable behavior after hypercapnic normalization. This allowed functional activity...

Field-strength formulation of gauge theories. The Hamiltonian approach in the Abelian theory

International Nuclear Information System (INIS)

Mendel, E.; Durand, L.

1984-01-01

We develop a Hamiltonian approach to the field-strength or dual formation of the Abelian gauge theory in which the potential A/sup μ/ is eliminated as a dynamical variable. Our work is based on the covariant gauge x/sup μ/A/sub μ/(x) = 0 which allows a simple elimination of A/sup μ/ in terms of the field strengths F/sup munu/. We obtain complete results for the generating functional for the Green's functions of the theory, Z = Z[f,g], where f and g are nonlocal currents coupled to E and B, and illustrate some unfamiliar aspects of the new formalism

Gluon field strength correlation functions within a constrained instanton model

International Nuclear Information System (INIS)

Dorokhov, A.E.; Esaibegyan, S.V.; Maximov, A.E.; Mikhailov, S.V.

2000-01-01

We suggest a constrained instanton (CI) solution in the physical QCD vacuum which is described by large-scale vacuum field fluctuations. This solution decays exponentially at large distances. It is stable only if the interaction of the instanton with the background vacuum field is small and additional constraints are introduced. The CI solution is explicitly constructed in the ansatz form, and the two-point vacuum correlator of the gluon field strengths is calculated in the framework of the effective instanton vacuum model. At small distances the results are qualitatively similar to the single instanton case; in particular, the D 1 invariant structure is small, which is in agreement with the lattice calculations. (orig.)

Fluorescent lamp with static magnetic field generating means

Science.gov (United States)

Moskowitz, P.E.; Maya, J.

1987-09-08

A fluorescent lamp wherein magnetic field generating means (e.g., permanent magnets) are utilized to generate a static magnetic field across the respective electrode structures of the lamp such that maximum field strength is located at the electrode's filament. An increase in efficacy during operation has been observed. 2 figs.

Strength optimized designs of thermoelastic structures

DEFF Research Database (Denmark)

Pedersen, Pauli; Pedersen, Niels Leergaard

2010-01-01

For thermoelastic structures the same optimal design does not simultaneously lead to minimum compliance and maximum strength. Compliance may be a questionable objective and focus for the present paper is on the important aspect of strength, quantified as minimization of the maximum von Mises stre...... loads are appended....

Differentiated-effect shims for medium field levels and saturation

International Nuclear Information System (INIS)

Richie, A.

1976-01-01

The arrangement of shims on the upstream and downstream ends of magnets may be based on the independent effects of variations in the geometric length and degree of saturation at the edges of the poles. This technique can be used to match the bending strength of an accelerator's magnets at two field levels (medium fields and maximum fields) and thus save special procedures (mixing the laminations, local compensation for errors by arranging the magnets in the appropriate order) and special devices (for instance, correcting dipoles) solely for correcting bending strengths at low field levels. (Auth.)

Maximum entropy reconstruction of poloidal magnetic field and radial electric field profiles in tokamaks

Science.gov (United States)

Chen, Yihang; Xiao, Chijie; Yang, Xiaoyi; Wang, Tianbo; Xu, Tianchao; Yu, Yi; Xu, Min; Wang, Long; Lin, Chen; Wang, Xiaogang

2017-10-01

The Laser-driven Ion beam trace probe (LITP) is a new diagnostic method for measuring poloidal magnetic field (Bp) and radial electric field (Er) in tokamaks. LITP injects a laser-driven ion beam into the tokamak, and Bp and Er profiles can be reconstructed using tomography methods. A reconstruction code has been developed to validate the LITP theory, and both 2D reconstruction of Bp and simultaneous reconstruction of Bp and Er have been attained. To reconstruct from experimental data with noise, Maximum Entropy and Gaussian-Bayesian tomography methods were applied and improved according to the characteristics of the LITP problem. With these improved methods, a reconstruction error level below 15% has been attained with a data noise level of 10%. These methods will be further tested and applied in the following LITP experiments. Supported by the ITER-CHINA program 2015GB120001, CHINA MOST under 2012YQ030142 and National Natural Science Foundation Abstract of China under 11575014 and 11375053.

Assessment of short/long term electric field strength measurements for a pilot district

Science.gov (United States)

Kurnaz, Cetin; Yildiz, Dogan; Karagol, Serap

2018-03-01

The level of electromagnetic radiation (EMR) exposure increases day by day as natural consequences of technological developments. In recent years, the increasing use of cellular systems has made it necessary to measure and evaluate EMR originating from base stations. In this study, broadband and band selective electric field strength (E) measurements were taken at four different times in order to evaluate the change of short term E in Atakum district of Samsun, Turkey. The measurements were collected from 46 different locations using a SRM 3006 and a PMM 8053 EMR meter in a band from 100 kHz to 3 GHz, and the maximum E (Emax) and the average E (Eavg) were recorded. The highest values have been noticed in these measurements at 9.45 V/m and 17.53 V/m for Eavg and Emax respectively. Apart from these measurements, 24 hour long term E measurements were taken at a location where the highest value was observed and analyzed, to observe the change of Es during a day. At the end of the study, a tentative mathematical model that helps in computing the total E of the medium with 95% accuracy, was obtained.

The effect of changing the magnetic field strength on HiPIMS deposition rates

International Nuclear Information System (INIS)

Bradley, J W; Mishra, A; Kelly, P J

2015-01-01

The marked difference in behaviour between HiPIMS and conventional dc or pulsed-dc magnetron sputtering discharges with changing magnetic field strengths is demonstrated through measurements of deposition rate. To provide a comparison between techniques the same circular magnetron was operated in the three excitation modes at a fixed average power of 680 W and a pressure of 0.54 Pa in the non-reactive sputtering of titanium. The total magnetic field strength B at the cathode surface in the middle of the racetrack was varied from 195 to 380 G. DC and pulsed-dc discharges show the expected behaviour that deposition rates fall with decreasing B (here by ∼25–40%), however the opposite trend is observed in HiPIMS with deposition rates rising by a factor of 2 over the same decrease in B.These observations are understood from the stand point of the different composition and transport processes of the depositing metal flux between the techniques. In HiPIMS, this flux is largely ionic and slow post-ionized sputtered particles are subject to strong back attraction to the target by a retarding plasma potential structure ahead of them. The height of this potential barrier is known to increase with increasing B.From a simple phenomenological model of the sputtered particles fluxes, and using the measured deposition rates from the different techniques as inputs, the combined probabilities of ionization, α, and back attraction, β, of the metal species in HiPIMS has been calculated. There is a clear fall in αβ (from ∼0.9 to ∼0.7) with decreasing B-field strengths, we argue primarily due to a weakening of electrostatic ion back attraction, so leading to higher deposition rates. The results indicate that careful design of magnetron field strengths should be considered to optimise HiPIMS deposition rates. (paper)

Critical Magnetic Field Strengths for Unipolar Solar Coronal Plumes In Quiet Regions and Coronal Holes?

Science.gov (United States)

Avallone, Ellis; Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.; Winebarger, Amy

2017-01-01

Coronal plumes are bright magnetic funnels that are found in quiet regions and coronal holes that extend high into the solar corona whose lifetimes can last from hours to days. The heating processes that make plumes bright involve the magnetic field at the base of the plume, but their intricacies remain mysterious. Raouafi et al. (2014) infer from observation that plume heating is a consequence of magnetic reconnection at the base, whereas Wang et al. (2016) infer that plume heating is a result of convergence of the magnetic flux at the plume's base, or base flux. Both papers suggest that the base flux in their plumes is of mixed polarity, but do not quantitatively measure the base flux or consider whether a critical magnetic field strength is required for plume production. To investigate the magnetic origins of plume heating, we track plume luminosity in the 171 Å wavelength as well as the abundance and strength of the base flux over the lifetimes of six unipolar coronal plumes. Of these, three are in coronal holes and three are in quiet regions. For this sample, we find that plume heating is triggered when convergence of the base flux surpasses a field strength of approximately 300 - 500 Gauss, and that the luminosity of both quiet region and coronal hole plumes respond similarly to the strength of the magnetic field in the base.

Coulomb field strength measurement by electro-optic spectral decoding system at the CALIFES beam line

CERN Document Server

Pan, R; Lefevre, T; Gillepsie, WA; CERN. Geneva. ATS Department

2016-01-01

Electro-optic (EO) techniques are increasingly used for longitudinal bunch profile measurements. A bunch profile monitor, based on electro-optic spectral decoding(EOSD), has been developed and demonstrated on the CALIFES beam line at CERN. The EO response is analysed using a frequency domain description, and two methods for extraction of absolute Coulomb field strengths from the electron bunch are demonstrated. Measurements at field strengths up to 1.3 MV/m agree with the expectation based on independent charge measurements.

Development of high-mechanical strength electrical insulations for tokamak toroidal field coils

International Nuclear Information System (INIS)

Burke, C.

1977-01-01

The electrical insulation for the TF (Toroidal Field) coils is subjected to a high interlaminar shear, tensile and compressive stresses. Two candidate epoxy/glass fiber systems using prepreg and vacuum impregnation techniques were evaluated. Specimens were prepared and processed under controlled conditions to simulate specification manufacturing procedures. The strengths of the insulation were measured in interlaminar shear, tension, compression, and combined shear and compression statically. Shear modulus determinations were also made. Various techniques of surface treatments to increase bond strengths with three resin primers were tested

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

Science.gov (United States)

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 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.

Measures of maximum magnetic field in 3 GHz radio frequency superconducting cavities; Mesures du gradient accelerateur maximum dans des cavites supraconductrices en regime impulsionnel a 3 GHz

Energy Technology Data Exchange (ETDEWEB)

Thomas, Catherine [Paris-11 Univ., 91 Orsay (France)

2000-01-19

Theoretical models have shown that the maximum magnetic field in radio frequency superconducting cavities is the superheating field H{sub sh}. For niobium, H{sub sh} is 25 - 30% higher than the thermodynamical H{sub c} field: H{sub sh} within (240 - 274) mT. However, the maximum magnetic field observed so far is in the range H{sub c,max} = 152 mT for the best 1.3 GHz Nb cavities. This field is lower than the critical field H{sub c1} above which the superconductor breaks up into divided normal and superconducting zones (H{sub c1}{<=}H{sub c}). Thermal instabilities are responsible for this low value. In order to reach H{sub sh} before thermal breakdown, high power short pulses are used. The cavity needs then to be strongly over-coupled. The dedicated test bed has been built from the collaboration between Istituto Nazionale di Fisica Nucleare (INFN) - Sezione di Genoa, and the Service d'Etudes et Realisation d'Accelerateurs (SERA) of Laboratoire de l'Accelerateur Lineaire (LAL). The maximum magnetic field, H{sub rf,max}, measurements on INFN cavities give lower results than the theoretical speculations and are in agreement with previous results. The superheating magnetic fields is linked to the magnetic penetration depth. This superconducting characteristic length can be used to determine the quality of niobium through the ratio between the resistivity measured at 300 K and 4.2 K in the normal conducting state (RRR). Results have been compared to previous ones and agree pretty well. They show that the RRR measured on cavities is superficial and lower than the RRR measured on samples which concerns the volume. (author)

Electrohydrodynamics in nanochannels coated by mixed polymer brushes: effects of electric field strength and solvent quality

Science.gov (United States)

Cao, Qianqian; Tian, Xiu; You, Hao

2018-04-01

We examine the electrohydrodynamics in mixed polymer brush-coated nanochannels and the conformational dynamics of grafted polymers using molecular dynamics simulations. Charged (A) and neutral polymers (B) are alternately grafted on the channel surfaces. The effects of the electric field strength and solvent quality are addressed in detail. The dependence of electroosmotic flow characteristics and polymer conformational behavior on the solvent quality is influenced due to the change of the electric field strength. The enhanced electric field induces a collapse of the neutral polymer chains which adopt a highly extended conformation along the flow direction. However, the thickness of the charged polymer layer is affected weakly by the electric field, and even a slight swelling is identified for the A-B attraction case, implying the conformational coupling between two polymer species. Furthermore, the charged polymer chains incline entirely towards the electric field direction oppositely to the flow direction. More importantly, unlike the neutral polymer chains, the shape factor of the charged polymer chains, which is used to describe the overall shape of polymer chains, is reduced significantly with increasing the electric field strength, corresponding to a more coiled structure.

A Stochastic Maximum Principle for General Mean-Field Systems

International Nuclear Information System (INIS)

Buckdahn, Rainer; Li, Juan; Ma, Jin

2016-01-01

In this paper we study the optimal control problem for a class of general mean-field stochastic differential equations, in which the coefficients depend, nonlinearly, on both the state process as well as of its law. In particular, we assume that the control set is a general open set that is not necessary convex, and the coefficients are only continuous on the control variable without any further regularity or convexity. We validate the approach of Peng (SIAM J Control Optim 2(4):966–979, 1990) by considering the second order variational equations and the corresponding second order adjoint process in this setting, and we extend the Stochastic Maximum Principle of Buckdahn et al. (Appl Math Optim 64(2):197–216, 2011) to this general case.

A Stochastic Maximum Principle for General Mean-Field Systems

Energy Technology Data Exchange (ETDEWEB)

Buckdahn, Rainer, E-mail: Rainer.Buckdahn@univ-brest.fr [Université de Bretagne-Occidentale, Département de Mathématiques (France); Li, Juan, E-mail: juanli@sdu.edu.cn [Shandong University, Weihai, School of Mathematics and Statistics (China); Ma, Jin, E-mail: jinma@usc.edu [University of Southern California, Department of Mathematics (United States)

2016-12-15

In this paper we study the optimal control problem for a class of general mean-field stochastic differential equations, in which the coefficients depend, nonlinearly, on both the state process as well as of its law. In particular, we assume that the control set is a general open set that is not necessary convex, and the coefficients are only continuous on the control variable without any further regularity or convexity. We validate the approach of Peng (SIAM J Control Optim 2(4):966–979, 1990) by considering the second order variational equations and the corresponding second order adjoint process in this setting, and we extend the Stochastic Maximum Principle of Buckdahn et al. (Appl Math Optim 64(2):197–216, 2011) to this general case.

High-field superconducting nested coil magnet

Science.gov (United States)

Laverick, C.; Lobell, G. M.

1970-01-01

Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

Strength-limited magnetic field intensity of toroidal magnet systems fabricated or the base of layer-by-layer shrouded solenoids

International Nuclear Information System (INIS)

Litvinnko, Yu.A.

1982-01-01

The possibilities, as to the ultimate magnetic field strength, of tokamak magnet systems made on the base of layer-by-laeyer shrouded coils are considered numerically. The toroidal magnet system is considered which consists of N skewe, layer-by-layer shrouded, equistrong coils in the ideal torus approximation. The dependences of the ragnetic field strength on the internal- and external torus radii, pulse duration and aspect ratio for copper coils shrouded with fiberglass are calculated as an example. The analysis of the obtained results shows that using of the layer-by-layer shrouding scheme for toroidal solenoid coils leads to a considerable growth of the ultimate magnetic field strengths in a wide duration range. For example, the limiting field strength along the toroidal solenoid axis of the considered type inside the ''FT'' installation toroidal solenoid at equivalent field pulse duration of approximately 0.3 s reaches H 0 =1.3zx10 7 A/m

Maximum Power Training and Plyometrics for Cross-Country Running.

Science.gov (United States)

Ebben, William P.

2001-01-01

Provides a rationale for maximum power training and plyometrics as conditioning strategies for cross-country runners, examining: an evaluation of training methods (strength training and maximum power training and plyometrics); biomechanic and velocity specificity (role in preventing injury); and practical application of maximum power training and…

Chemical shift-selective snapshot FLASH MR imaging in combination with inversion-recovery T1 contrast at different field strengths

International Nuclear Information System (INIS)

Matthaei, D.; Haase, A.; Henrich, D.; Duhmke, E.

1991-01-01

With fast MR imaging, chemical shift contract becomes available to the clinician in seconds. The purpose of this paper is to evaluate the combination of chemical shift selective (CHESS) MR imaging using the snapshot FLASH MR method with the inversion-recovery technique and to obtain information concerning the signal-to-noise and chemical shift with the presaturation method at different field strengths. Investigations with volunteers and experimental animals were done at 2 and 3 T (whole body) and in a 4.7-T animal image. For the inversion-recovery experiments, saturation was done before every snapshot FLASH image. With increasing field strength due to signal-to-noise and chemical shift advantages, the method performs better. Increasing T1 values are also important at high field strengths. The combined technique is useful only for T1 water images with fat saturation. It also allows fast quantification of T1 in water-containing organs and pathologic processes. At high field strengths, fast CHESS and T1 imaging promise fast quantitative information. This is a possible argument for clinical high-field-strength MR imagining along with MR spectroscopy

Traditional versus functional strength training: Effects on muscle strength and power in the elderly

OpenAIRE

Seiler, Hilde Lohne; Torstveit, Monica Klungland; Anderssen, Sigmund A.

2013-01-01

Published versiom of an article in the journal:Journal of Aging and Physical Activity. Also available from Human Kinetics: http://http://journals.humankinetics.com/japa-back-issues/japa-volume-21-issue-1-january/traditional-versus-functional-strength-training-effects-on-muscle-strength-and-power-in-the-elderly The aim was to determine whether strength training with machines vs. functional strength training at 80% of one-repetition maximum improves muscle strength and power among the elderl...

C-130: Results of center wing residual strength and crack propagation test program

Science.gov (United States)

Reeder, F. L.; Dirkin, W. J.; Snider, H. L.

1971-01-01

Fourteen C-130 airplane center wings which had experienced from approximately 4,000 to 13,000 hours of flight service and its associated fatigue damage were tested to destruction, seven in upbending and seven in downbending. Six wings were tested directly for static residual strength in the fatigue-damaged condition as received from field service. The other eight wings were tested in crack propagation cyclic testing at a prescribed stress level for a maximum of 10,000 cycles. Then the stress level was reduced and testing was continued up to a maximum of 20,000 total cycles. Cyclic testing was performed with constant-amplitude stresses at a stress ratio of +0.1. Maximum cyclic skin stresses were approximately 18,000 psi. At the conclusion of cyclic testing, a static test to destruction was conducted to determine the residual strength of each fatigue-damaged specimen.

High strength ferritic alloy

International Nuclear Information System (INIS)

1977-01-01

A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

Energy Levels and Spectral Lines of Li Atoms in White Dwarf Strength Magnetic Fields

Science.gov (United States)

Zhao, L. B.

2018-04-01

A theoretical approach based on B-splines has been developed to calculate atomic structures and discrete spectra of Li atoms in a strong magnetic field typical of magnetic white dwarf stars. Energy levels are presented for 20 electronic states with the symmetries 20+, 20‑, 2(‑1)+, 2(‑1)‑, and 2(‑2)+. The magnetic field strengths involved range from 0 to 2350 MG. The wavelengths and oscillator strengths for the electric dipole transitions relevant to these magnetized atomic states are reported. The current results are compared to the limited theoretical data in the literature. A good agreement has been found for the lower energy levels, but a significant discrepancy is clearly visible for the higher energy levels. The existing discrepancies of the wavelengths and oscillator strengths are also discussed. Our investigation shows that the spectrum data of magnetized Li atoms previously published are obviously far from meeting requirements of analyzing discrete atomic spectra of magnetic white dwarfs with lithium atmospheres.

Numerical simulation of positive streamer development in thundercloud field enhanced near raindrops

DEFF Research Database (Denmark)

Babich, L. P.; Bochkov, E. I.; Kutsyk, I. M.

2016-01-01

As the threshold field strength for the breakdown in air significantly exceeds the maximum measured thundercloud strength 3 kV/cm/atm, the problem of lightning initiation remains unclear. According to the popular idea, lightning can be initiated from streamer discharges developed in the enhanced...

Magnetic field strength of a neutron-star-powered ultraluminous X-ray source

Science.gov (United States)

Brightman, M.; Harrison, F. A.; Fürst, F.; Middleton, M. J.; Walton, D. J.; Stern, D.; Fabian, A. C.; Heida, M.; Barret, D.; Bachetti, M.

2018-04-01

Ultraluminous X-ray sources (ULXs) are bright X-ray sources in nearby galaxies not associated with the central supermassive black hole. Their luminosities imply they are powered by either an extreme accretion rate onto a compact stellar remnant, or an intermediate mass ( 100-105M⊙) black hole1. Recently detected coherent pulsations coming from three bright ULXs2-5 demonstrate that some of these sources are powered by accretion onto a neutron star, implying accretion rates significantly in excess of the Eddington limit, a high degree of geometric beaming, or both. The physical challenges associated with the high implied accretion rates can be mitigated if the neutron star surface field is very high (1014 G)6, since this suppresses the electron scattering cross-section, reducing the radiation pressure that chokes off accretion for high luminosities. Surface magnetic field strengths can be determined through cyclotron resonance scattering features7,8 produced by the transition of charged particles between quantized Landau levels. Here, we present the detection at a significance of 3.8σ of an absorption line at 4.5 keV in the Chandra spectrum of a ULX in M51. This feature is likely to be a cyclotron resonance scattering feature produced by the strong magnetic field of a neutron star. Assuming scattering off electrons, the magnetic field strength is implied to be 1011 G, while protons would imply a magnetic field of B 1015 G.

On generalization of electric field strength in longitudinally blown arcs

OpenAIRE

Yas'ko, O.I.; Esipchuk, A.M.; Qing, Z.; Schram, D.C.; Fauchais, P.

1997-01-01

Generalization of av. elec. field strength for different discharge conditions in longitudinally blown arcs is considered. Exptl. data for distinctive devices and different gases were used for phys. modeling. Anal. showed that heat transfer processes are responsible for I-E characteristic formation. Turbulent heat transfer is the most effective for atm. pressure discharges while convection plays the main role in vacuum arcs. A generalized I-E characteristic was obtained. [on SciFinder (R)

Maximum toe flexor muscle strength and quantitative analysis of human plantar intrinsic and extrinsic muscles by a magnetic resonance imaging technique.

Science.gov (United States)

Kurihara, Toshiyuki; Yamauchi, Junichiro; Otsuka, Mitsuo; Tottori, Nobuaki; Hashimoto, Takeshi; Isaka, Tadao

2014-01-01

The aims of this study were to investigate the relationships between the maximum isometric toe flexor muscle strength (TFS) and cross-sectional area (CSA) of the plantar intrinsic and extrinsic muscles and to identify the major determinant of maximum TFS among CSA of the plantar intrinsic and extrinsic muscles. Twenty six young healthy participants (14 men, 12 women; age, 20.4 ± 1.6 years) volunteered for the study. TFS was measured by a specific designed dynamometer, and CSA of plantar intrinsic and extrinsic muscles were measured using magnetic resonance imaging (MRI). To measure TFS, seated participants optimally gripped the bar with their toes and exerted maximum force on the dynamometer. For each participant, the highest force produced among three trials was used for further analysis. To measure CSA, serial T1-weighted images were acquired. TFS was significantly correlated with CSA of the plantar intrinsic and extrinsic muscles. Stepwise multiple linear regression analyses identified that the major determinant of TFS was CSA of medial parts of plantar intrinsic muscles (flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, lumbricals and abductor hallucis). There was no significant difference between men and women in TFS/CSA. CSA of the plantar intrinsic and extrinsic muscles is one of important factors for determining the maximum TFS in humans.

The optimal shape of an object for generating maximum gravity field at a given point in space

OpenAIRE

Wang, Xiao-Wei; Su, Yue

2014-01-01

How can we design the shape of an object, in the framework of Newtonian gravity, in order to generate maximum gravity at a given point in space? In this work we present a study on this interesting problem. We obtain compact solutions for all dimensional cases. The results are commonly characterized by a simple "physical" feature that any mass element unit on the object surface generates the same gravity strength at the considered point, in the direction along the rotational symmetry axis.

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

Science.gov (United States)

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 (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.

Field strength correlators in QCD: new fits to the lattice data

International Nuclear Information System (INIS)

Meggiolaro, E.

1999-01-01

We discuss the results obtained by fitting the lattice data of the gauge-invariant field strength correlators in QCD with some particular functions which are commonly used in the literature in some phenomenological approaches to high-energy hadron-hadron scattering. A comparison is done with the results obtained in the original fits to the lattice data. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

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

Science.gov (United States)

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.

The optimal shape of an object for generating maximum gravity field at a given point in space

International Nuclear Information System (INIS)

Wang, Xiao-Wei; Su, Yue

2015-01-01

How can we design the shape of an object, in the framework of Newtonian gravity, in order to generate maximum gravity at a given point in space? In this work we present a study on this interesting problem. We obtain compact solutions for all dimensional cases. The results are commonly characterized by a simple ‘physical’ feature that any mass element unit on the object surface generates the same gravity strength at the considered point, in the direction along the rotational symmetry axis. (paper)

Field measurement of dipole magnets for TARN

International Nuclear Information System (INIS)

Hori, T.; Noda, A.; Hattori, T.; Fujino, T.; Yoshizawa, M.

1980-05-01

Eight dipole magnets of window-frame type with zero field gradient have been fabricated for TARN. Various characteristics of the field were examined by a measuring system with a Hall and an NMR probes. The accuracy of the measurement was better than 1 x 10 -4 at the maximum field strength of --9 kG, and the uniformity of the field in the radial direction was better than +-2 x 10 -4 over the whole useful aperture. The deviations both of the field strengths and of the effective lengths among the eight magnets are smaller than +-2 x 10 -3 . The sextupole component of the field and the variation of the effective length over the beam orbits contribute to chromaticities of the ring as the amount of -1.59 and 0.93 in the horizontal and vertical directions, respectively. (author)

Theoretical evaluation of maximum electric field approximation of direct band-to-band tunneling Kane model for low bandgap semiconductors

Science.gov (United States)

Dang Chien, Nguyen; Shih, Chun-Hsing; Hoa, Phu Chi; Minh, Nguyen Hong; Thi Thanh Hien, Duong; Nhung, Le Hong

2016-06-01

The two-band Kane model has been popularly used to calculate the band-to-band tunneling (BTBT) current in tunnel field-effect transistor (TFET) which is currently considered as a promising candidate for low power applications. This study theoretically clarifies the maximum electric field approximation (MEFA) of direct BTBT Kane model and evaluates its appropriateness for low bandgap semiconductors. By analysing the physical origin of each electric field term in the Kane model, it has been elucidated in the MEFA that the local electric field term must be remained while the nonlocal electric field terms are assigned by the maximum value of electric field at the tunnel junction. Mathematical investigations have showed that the MEFA is more appropriate for low bandgap semiconductors compared to high bandgap materials because of enhanced tunneling probability in low field regions. The appropriateness of the MEFA is very useful for practical uses in quickly estimating the direct BTBT current in low bandgap TFET devices.

The significance of vector magnetic field measurements

Science.gov (United States)

Hagyard, M. J.

1990-01-01

Observations of four flaring solar active regions, obtained during 1980-1986 with the NASA Marshall vector magnetograph (Hagyard et al., 1982 and 1985), are presented graphically and characterized in detail, with reference to nearly simultaneous Big Bear Solar Observatory and USAF ASW H-alpha images. It is shown that the flares occurred where local photospheric magnetic fields differed most from the potential field, with initial brightening on either side of a magnetic-neutral line near the point of maximum angular shear (rather than that of maximum magnetic-field strength, typically 1 kG or greater). Particular emphasis is placed on the fact that these significant nonpotential features were detected only by measuring all three components of the vector magnetic field.

Changes in maximum muscle strength and rapid muscle force characteristics after long-term special support and reconnaissance missions

DEFF Research Database (Denmark)

Christensen, Peter Astrup; Jacobsen, Jacob Ole; Thorlund, Jonas B

2008-01-01

PURPOSE: The purpose of the present study was to examine the impact of 8 days of immobilization during a Special Support and Reconnaissance mission (SSR) on muscle mass, contraction dynamics, maximum jump height/power, and body composition. METHODS: Unilateral maximal voluntary contraction, rate...... of force development, and maximal jump height were tested to assess muscle strength/power along with whole-body impedance analysis before and after SSR. RESULTS: Body weight, fat-free mass, and total body water decreased (4-5%) after SSR, along with impairments in maximal jump height (-8%) and knee...... extensor maximal voluntary contraction (-10%). Furthermore, rate of force development was severely affected (-15-30%). CONCLUSIONS: Eight days of immobilization during a covert SSR mission by Special Forces soldiers led to substantial decrements in maximal muscle force and especially in rapid muscle force...

Evaluation of mechanical strength of the joints in JT-60 toroidal field coil conductors

International Nuclear Information System (INIS)

Nishio, Satoshi; Ohkubo, Monoru; Sasajima, Hiroshi

1980-04-01

Toroidal field (TF) coils of JT-60 produce a toroidal field of 45 kG at a plasma axis, they have an inner bore of 3.90 m and a weight of about 80 metric tons per coil. Eighteen TF coils are located around a torus axis at regular intervals. TF coil conductors are mostly jointed by high frequency induction brazing, the rest jointed by welding. In deciding the details of the jointing procedures, the conductor size and the requested mechanical strength are mainly taken into consideration. Described are non-destructive inspection methods for the brazed joints, strength evaluation, and the inspection criteria. Ultrasonic testing method is found to be the most effective in evaluation of mechanical properties of the brazed joints especially in terms of fatigue strength. In section 1, specifications of the TF coils are given. In section 2, the ultrasonic inspection method and the detectability of this apparatus are described in detail, the defects of known size are compared with the indication values and display figures. The apparatus developed for JT-60 is operated automatically also recording the inspectionresults. In section 3, mechanical strength of the brazed joints with initial defects is discussed on the basis of Fracture Mechanics theory and results of the fatigue crack growth test. The inspection criteria in accordance with the descriptions of section 2 and 3 are given in section 4. (author)

States of maximum polarization for a quantum light field and states of a maximum sensitivity in quantum interferometry

International Nuclear Information System (INIS)

Peřinová, Vlasta; Lukš, Antonín

2015-01-01

The SU(2) group is used in two different fields of quantum optics, the quantum polarization and quantum interferometry. Quantum degrees of polarization may be based on distances of a polarization state from the set of unpolarized states. The maximum polarization is achieved in the case where the state is pure and then the distribution of the photon-number sums is optimized. In quantum interferometry, the SU(2) intelligent states have also the property that the Fisher measure of information is equal to the inverse minimum detectable phase shift on the usual simplifying condition. Previously, the optimization of the Fisher information under a constraint was studied. Now, in the framework of constraint optimization, states similar to the SU(2) intelligent states are treated. (paper)

Monodimensional estimation of maximum Reynolds shear stress in the downstream flow field of bileaflet valves.

Science.gov (United States)

Grigioni, Mauro; Daniele, Carla; D'Avenio, Giuseppe; Barbaro, Vincenzo

2002-05-01

Turbulent flow generated by prosthetic devices at the bloodstream level may cause mechanical stress on blood particles. Measurement of the Reynolds stress tensor and/or some of its components is a mandatory step to evaluate the mechanical load on blood components exerted by fluid stresses, as well as possible consequent blood damage (hemolysis or platelet activation). Because of the three-dimensional nature of turbulence, in general, a three-component anemometer should be used to measure all components of the Reynolds stress tensor, but this is difficult, especially in vivo. The present study aimed to derive the maximum Reynolds shear stress (RSS) in three commercially available prosthetic heart valves (PHVs) of wide diffusion, starting with monodimensional data provided in vivo by echo Doppler. Accurate measurement of PHV flow field was made using laser Doppler anemometry; this provided the principal turbulence quantities (mean velocity, root-mean-square value of velocity fluctuations, average value of cross-product of velocity fluctuations in orthogonal directions) needed to quantify the maximum turbulence-related shear stress. The recorded data enabled determination of the relationship, the Reynolds stresses ratio (RSR) between maximum RSS and Reynolds normal stress in the main flow direction. The RSR was found to be dependent upon the local structure of the flow field. The reported RSR profiles, which permit a simple calculation of maximum RSS, may prove valuable during the post-implantation phase, when an assessment of valve function is made echocardiographically. Hence, the risk of damage to blood constituents associated with bileaflet valve implantation may be accurately quantified in vivo.

Progress with High-Field Superconducting Magnets for High-Energy Colliders

Science.gov (United States)

Apollinari, Giorgio; Prestemon, Soren; Zlobin, Alexander V.

2015-10-01

One of the possible next steps for high-energy physics research relies on a high-energy hadron or muon collider. The energy of a circular collider is limited by the strength of bending dipoles, and its maximum luminosity is determined by the strength of final focus quadrupoles. For this reason, the high-energy physics and accelerator communities have shown much interest in higher-field and higher-gradient superconducting accelerator magnets. The maximum field of NbTi magnets used in all present high-energy machines, including the LHC, is limited to ˜10 T at 1.9 K. Fields above 10 T became possible with the use of Nb3Sn superconductors. Nb3Sn accelerator magnets can provide operating fields up to ˜15 T and can significantly increase the coil temperature margin. Accelerator magnets with operating fields above 15 T require high-temperature superconductors. This review discusses the status and main results of Nb3Sn accelerator magnet research and development and work toward 20-T magnets.

Control over Janus micromotors by the strength of a magnetic field

Science.gov (United States)

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

2013-01-01

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

3 telsa MRI: successful results with higher field strengths

International Nuclear Information System (INIS)

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

2004-01-01

The recent development of 3Telsa MRI (3T MRI) has been fueled by the promise of increased signal-to-noise ratio (SNR). Many are excited about the opportunity to no only use the increased SNR for clearer images, but also the change 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 strength. For example the T1 relaxation times are prolongued with increasing magnet field strength. Further, the increased RF-energy deposition (ASR), the larger 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 and a number of different methods for doing so, to properly tackle each of these concerns will take time and effort on the part of researchers and clinicians. The optimization of 3T MRI scanning will have to be combined effort, though much work has already been done. The most active area of work to date has been in neuroimaging. Multiple applications have been explored in addition to clinical anatomical imaging, where resolutions is improved showing structure in the brain never before seen in human MRI

Detection of electric field around field-reversed configuration plasma

International Nuclear Information System (INIS)

Ikeyama, Taeko; Hiroi, Masanori; Nogi, Yasuyuki; Ohkuma, Yasunori

2010-01-01

Electric-field probes consisting of copper plates are developed to measure electric fields in a vacuum region around a plasma. The probes detect oscillating electric fields with a maximum strength of approximately 100 V/m through a discharge. Reproducible signals from the probes are obtained with an unstable phase dominated by a rotational instability. It is found that the azimuthal structure of the electric field can be explained by the sum of an n=2 mode charge distribution and a convex-surface electron distribution on the deformed separatrix at the unstable phase. The former distribution agrees with that anticipated from the diamagnetic drift motions of plasma when the rotational instability occurs. The latter distribution suggests that an electron-rich plasma covers the separatrix.

Effect of electric field on the oscillator strength and cross-section for intersubband transition in a semiconductor quantum ring

International Nuclear Information System (INIS)

Bhattacharyya, S; Das, N R

2012-01-01

In this paper, we study the oscillator strength and cross-section for intersubband optical transition in an n-type semiconductor quantum ring of cylindrical symmetry in the presence of an electric field perpendicular to the plane of the ring. The analysis is done considering Kane-type band non-parabolicity of the semiconductor and assuming that the polarization of the incident radiation is along the axis of the ring. The results show that the oscillator strength decreases and the transition energy increases with the electric field. The assumption of a parabolic band leads to an overestimation of the oscillator strength. The effects of the electric field, band non-parabolicity and relaxation time on absorption cross-section for intersubband transition in a semiconductor quantum ring are also shown. (paper)

Small static electric field strength promotes aggregation-prone structures in amyloid-β(29-42)

Science.gov (United States)

Lu, Yan; Shi, Xiao-Feng; Salsbury, Freddie R.; Derreumaux, Philippe

2017-04-01

The formation of senile plaques in central neural system resulting from the aggregation of the amyloid β (Aβ) of 40 and 42 residues is one of the two hallmarks of Alzheimer's disease. Numerous experiments and computational studies have shown that the aggregation of Aβ peptides in vitro is very complex and depends on many factors such as pH, agitation, temperature, and peptide concentration. The impact of a static electric field (EF) on amyloid peptide aggregation has been much less studied, although EFs may have some applications to treat Parkinson's disease symptoms. Here, we study the influence of an EF strength of 20 mV/nm, present in the human brains, on the conformation of the Aβ29-42 dimer. Our 7 μs non-equilibrium atomistic simulations in aqueous solution show that this field-strength promotes substantially the formation of β-hairpins, believed to be a very important intermediate state during aggregation. This work also suggests that structural biology experiments conducted under appropriate EF strengths may help reduce the conformational heterogeneity of Aβ1-40/Aβ1-42 dimers and provide significant insights into their structures that may be disease-causing.

CALCULATION METHOD OF ELECTRIC POWER LINES MAGNETIC FIELD STRENGTH BASED ON CYLINDRICAL SPATIAL HARMONICS

Directory of Open Access Journals (Sweden)

A.V. Erisov

2016-05-01

Full Text Available Purpose. Simplification of accounting ratio to determine the magnetic field strength of electric power lines, and assessment of their environmental safety. Methodology. Description of the transmission lines of the magnetic field by using techniques of spatial harmonic analysis in the cylindrical coordinate system is carried out. Results. For engineering calculations of electric power lines magnetic field with sufficient accuracy describes their first spatial harmonic magnetic field. Originality. Substantial simplification of the definition of the impact of the construction of transmission line poles on the value of its magnetic field and the bands of land alienation sizes. Practical value. The environmentally friendly projection electric power lines on the level of the magnetic field.

Simultaneous Solar Maximum Mission (SMM) and very large array observations of solar active regions

Science.gov (United States)

Lang, K. R.

1986-01-01

The research deals mainly with Very Large Array and Solar Maximum Mission observations of the ubiquitous coronal loops that dominate the structure of the low corona. As illustrated, the observations of thermal cyclotron lines at microwave wavelengths provide a powerful new method of accurately specifying the coronal magnetic field strength. Processes are delineated that trigger solar eruptions from coronal loops, including preburst heating and the magnetic interaction of coronal loops. Evidence for coherent burst mechanisms is provided for both the Sun and nearby stars, while other observations suggest the presence of currents that may amplify the coronal magnetic field to unexpectedly high levels. The existence is reported of a new class of compact, variable moving sources in regions of apparently weak photospheric field.

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

Science.gov (United States)

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 (p3.0 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

Determining the effect of grain size and maximum induction upon coercive field of electrical steels

Science.gov (United States)

Landgraf, Fernando José Gomes; da Silveira, João Ricardo Filipini; Rodrigues-Jr., Daniel

2011-10-01

Although theoretical models have already been proposed, experimental data is still lacking to quantify the influence of grain size upon coercivity of electrical steels. Some authors consider a linear inverse proportionality, while others suggest a square root inverse proportionality. Results also differ with regard to the slope of the reciprocal of grain size-coercive field relation for a given material. This paper discusses two aspects of the problem: the maximum induction used for determining coercive force and the possible effect of lurking variables such as the grain size distribution breadth and crystallographic texture. Electrical steel sheets containing 0.7% Si, 0.3% Al and 24 ppm C were cold-rolled and annealed in order to produce different grain sizes (ranging from 20 to 150 μm). Coercive field was measured along the rolling direction and found to depend linearly on reciprocal of grain size with a slope of approximately 0.9 (A/m)mm at 1.0 T induction. A general relation for coercive field as a function of grain size and maximum induction was established, yielding an average absolute error below 4%. Through measurement of B50 and image analysis of micrographs, the effects of crystallographic texture and grain size distribution breadth were qualitatively discussed.

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

International Nuclear Information System (INIS)

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

2012-01-01

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.

Influence of the maximum applied magnetic field on the angular dependence of Magnetic Barkhausen Noise in API5L steels

Energy Technology Data Exchange (ETDEWEB)

Martínez-Ortiz, P. [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F. (Mexico); Pérez-Benítez, J.A., E-mail: japerezb@ipn.mx [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F. (Mexico); Espina-Hernández, J.H. [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F. (Mexico); Caleyo, F. [Departamento de Ingeniería Metalúrgica, ESIQIE, UPALM Edif. 7, Instituto Politécnico Nacional, Zacatenco, C.P. 07738 México D.F. (Mexico); Mehboob, N.; Grössinger, R. [Institute of Solid State Physics, Vienna University of Technology, Vienna A-1040 (Austria); Hallen, J.M. [Departamento de Ingeniería Metalúrgica, ESIQIE, UPALM Edif. 7, Instituto Politécnico Nacional, Zacatenco, C.P. 07738 México D.F. (Mexico)

2016-03-01

This work studies the influence of the maximum applied magnetic field on the angular dependence of the energy of the Magnetic Barkhausen Noise signal in three different API5L pipeline steels. The results show that the shape of the angular dependence of the Magnetic Barkhausen Noise energy changes with the increase of the amplitude of the applied magnetic field. This phenomenon is a consequence of the presence of unlike magnetization processes at different magnitudes of the applied magnetic field. The outcomes reveal the importance of controlling the value of the maximum applied field as parameter for the improvement of the MBN angular dependence measurements. - Highlights: • Study the angular dependence of MBN with applied field in three pipeline steels. • Reveals the change of this angular dependence with the increase applied field. • Explains this dependence based on the domain wall dynamics theory.

Influence of the maximum applied magnetic field on the angular dependence of Magnetic Barkhausen Noise in API5L steels

International Nuclear Information System (INIS)

Martínez-Ortiz, P.; Pérez-Benítez, J.A.; Espina-Hernández, J.H.; Caleyo, F.; Mehboob, N.; Grössinger, R.; Hallen, J.M.

2016-01-01

This work studies the influence of the maximum applied magnetic field on the angular dependence of the energy of the Magnetic Barkhausen Noise signal in three different API5L pipeline steels. The results show that the shape of the angular dependence of the Magnetic Barkhausen Noise energy changes with the increase of the amplitude of the applied magnetic field. This phenomenon is a consequence of the presence of unlike magnetization processes at different magnitudes of the applied magnetic field. The outcomes reveal the importance of controlling the value of the maximum applied field as parameter for the improvement of the MBN angular dependence measurements. - Highlights: • Study the angular dependence of MBN with applied field in three pipeline steels. • Reveals the change of this angular dependence with the increase applied field. • Explains this dependence based on the domain wall dynamics theory.

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

Science.gov (United States)

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.

CONSTRAINING THE SOLAR CORONAL MAGNETIC FIELD STRENGTH USING SPLIT-BAND TYPE II RADIO BURST OBSERVATIONS

Energy Technology Data Exchange (ETDEWEB)

Kishore, P.; Ramesh, R.; Hariharan, K.; Kathiravan, C. [Indian Institute of Astrophysics, 2nd Block, Koramangala, Bangalore—560034 (India); Gopalswamy, N., E-mail: kishore@iiap.res.in [Code 671, Solar Physics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)

2016-11-20

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.

Effect of 8 weeks of free-weight and machine-based strength training on strength and power performance.

Science.gov (United States)

Wirth, Klaus; Keiner, Michael; Hartmann, Hagen; Sander, Andre; Mickel, Christoph

2016-12-01

The aim of this study was to evaluate the effectiveness of free-weight and machine-based exercises to increase different strength and speed-strength variables. One hundred twenty male participants (age: 23.8 ± 2.5 years; body height: 181.0 ± 6.8 cm; body mass: 80.2 ± 8.9 kg) joined the study. The 2 experimental groups completed an 8 week periodized strength training program that included 2 training sessions per week. The exercises that were used in the strength training programs were the parallel barbell squat and the leg press. Before and after the training period, the 1-repetition-maximum in the barbell squat and the leg press, the squat jump, the countermovement jump and unilateral isometric force (maximal isometric force and the rate of force development) were evaluated. To compare each group pre vs. post-intervention, analysis of variance with repeated measures and Scheffé post-hoc tests were used. The leg press group increased their 1-repetition-maximum significantly (p squat group such variables as 1-repetition-maximum, the squat jump and the countermovement jump increased significantly (p squat group even showed a statistically significant decrease. Differences between the 2 experimental groups were detected for the squat jump and the countermovement jump. In comparison with the leg press, the squat might be a better strength training exercise for the development of jump performance.

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

Science.gov (United States)

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.

INFLUENCE OF STRENGTH TRAINING PROGRAM ON ISOMETRIC MUSCLE STRENGTH IN YOUNG ATHLETES

Directory of Open Access Journals (Sweden)

Dragan Radovanovic

2007-10-01

Full Text Available Strength training, or resistance training, is a form of physical conditioning used to increase the ability to resist force. Since muscular strength is required for success in many sports, it is logical to assume that stronger and more powerful young athletes will achieve better results. The aim of the study was to examine the effects of strength training on young athletes. An eight-week strength training program for developing muscle strength was performed in this study. Training protocol was designed specifically for young adolescent’s athletes. The program consisted of exercises for lower and upper body, abdominal and lower back muscles. The programs did not involve the maximal (1-3 repetitions maximum and other very hard intensity exercises that may had negative effect on young athletes. The results showed that strength training program had positive effects on maximal isometric muscle force (Fmax and motor skill. The increase presents the combined influence of strength training and growth.

A surface acoustic wave electric field strength meter for environmental studies of HV transmission lines

International Nuclear Information System (INIS)

Grandolfo, M.; Ranghiasci, C.; Verona, E.

1988-01-01

In recent years, there has been a significant increase in concern over the health and safety aspects of high voltage transmission lines (HVTL). The majority of research has focused on effects directly or indirectly involved with the central nervous system, including physiological, ultrastructural, and biochemical alterations, changes in blood composition, behaviour, reproduction, and development. Several recent epidemiological reports have presented preliminary data suggesting an increase in the incidence of cancer among children and adults exposed to magnetic fields through living close to various types of electrical power lines or devices. With the increase in environmental concerns there has been a concomitant consideration of biological effects and health implications related to presently existing HVTL and those planned in the future. It was concluded that the electric and magnetic field strengths and the electrical discharges are the most important electrophysical factors. Thus, it has been deemed necessary to develop measuring means to determine the field strengths in areas surrounding electric installations, in particular at ground level. In the present paper an electric field meter, based on the use of a surface acoustic wave (SAW) delay line, is presented and the experimental results obtained are discussed

The upper critical field of CeCoIn5

International Nuclear Information System (INIS)

Howald, Ludovic; Knebel, Georg; Aoki, Dai; Lapertot, Gérard; Brison, Jean-Pascal

2011-01-01

We present a detailed analysis of the upper critical field for CeCoIn 5 under high pressure. We show that, consistent with other measurements, this system shows a decoupling between the maximum of the superconducting transition temperature T c and the maximum pairing strength. We propose a model in which, in order to account for the discrepancy in pressure between the maximum of the upper critical field and the maximum of T c , we introduce magnetic pair-breaking effects, already widely suggested by other measurements. We found that within the Eliashberg frame work, the unusual shape of H c2 (T) can be completely reproduced when magnetic pair breaking is taken into account. Surprisingly, we found that the maximum of pair breaking and of pair coupling coincide in pressure, suggesting that both mechanisms originate from quantum criticality. Our model implies that CeCoIn 5 is the first compound of its family that shows clear decoupling between the maximum of T c and quantum criticality. (paper)

Initiation of Positive Streamers near Uncharged Ice Hydrometeors in the Thundercloud Field

Science.gov (United States)

Babich, L. P.; Bochkov, E. I.

2018-05-01

Since the threshold electric field required for breakdown of air is much higher than the maximum field strength measured in thunderstorm clouds, the problem of lightning initiation still remains unsolved. According to the popular hypothesis, lightning can be initiated by a streamer discharge in the field enhanced near a hydrometeor. To verify the adequacy of this hypothesis, the development of a positive streamer propagating along the thunderstorm electric field in the vicinity of an ice needle at an air pressure corresponding to an altitude of 5 km (which is typical of the lightning initiation conditions) was simulated numerically. The hydrometeor dimensions are determined at which streamers can be initiated at different strengths of the thunderstorm electric field.

The effects of combined elastic- and free-weight tension vs. free-weight tension on one-repetition maximum strength in the bench press.

Science.gov (United States)

Bellar, David M; Muller, Matthew D; Barkley, Jacob E; Kim, Chul-Ho; Ida, Keisuke; Ryan, Edward J; Bliss, Mathew V; Glickman, Ellen L

2011-02-01

The present study investigated the effects of training combining elastic tension, free weights, and the bench press. Eleven college-aged men (untrained) in the bench press participated in the 13-week study. The participants were first given instructions and then practiced the bench press, followed by a one-repetition maximum (1RM) test of baseline strength. Subjects were then trained in the bench press for 3 weeks to allow for the beginning of neural adaptation. After another 1RM test, participants were assigned to 1 of 2 conditions for the next 3 weeks of training: 85% Free-Weight Tension, 15% Elastic Tension (BAND), or 100% Free-Weight Tension (STAND). After 3 weeks of training and a third 1RM max test, participants switched treatments, under which they completed the final 3 weeks of training and the fourth 1RM test. Analysis via analysis of covariance revealed a significant (p ≤ 0.05) main effect for time and interaction effect for Treatment (BAND vs. STAND). Subsequent analysis via paired-samples t-test revealed the BAND condition was significantly better (p = 0.05) at producing raw gains in 1RM strength. (BAND 9.95 ± 3.7 kg vs. STAND 7.56 ± 2.8 kg). These results suggest that the addition of elastic tension to the bench press may be an effective method of increasing strength.

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

Science.gov (United States)

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.

Low-field-strength magnetic resonance imaging in the canine brain

International Nuclear Information System (INIS)

Esteve Ratsch, B.

2000-06-01

Magnetic resonance imaging (MRI; 0,23 T) of the canine brain was performed. Each scan plane was compared with corresponding anatomic sections. The best imaging planes to visualize various anatomic structures were determined. Low-field-strength MRI allowed the good definition of all relevant anatomic structures of the brain of 55 dogs with the exception of most cranial nerves. White matter could be best differentiated using proton-weighted images. On T1-weighted images the contrast of white matter was markedly limited in the living dogs in contrast to the examined canine specimens. The relative size of the lateral ventricle was defined as the ratio of the size of the lateral ventricle and the size of the half brain. The relative size of the lateral ventricle of Yorkshire Terrier dogs (5,35 %) was significantly (p 0,05) in the relative size of the lateral ventricles of healthy Yorkshire Terrier dogs (5,35 %) and Yorkshire Terrier dogs with neurological symptoms (7,06 %). Asymmetric lateral ventricles were very common in the examined dogs independently from body size, skull shape and neurological status. Occasionally the septum telencephali was not developed completely. 11 of 12 intracranial neoplasm could be delineated using low-field-strength MRI. Anatomic site, number of intracerebral lesions, limitation, shape and growth pattern, secondary brain lesions and development of peritumoral edema were described for each intracranial neoplasm as well as its signal intensity on T1- and T2-weighted images and contrast enhancement pattern. MRI did not allow an accurate diagnosis of tumor type, nevertheless skull shape (brachycephalic/dolichocephalic), anatomic site and number of intracerebral lesions facilitated a presumable diagnosis of the tumor type. (author)

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

Science.gov (United States)

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.

Magnetic fields, velocity fields and brightness in the central region of the Solar disk

Energy Technology Data Exchange (ETDEWEB)

Tsap, T T

1978-01-01

The longitudinal magnetic fields, velocity fields and brightness at the center of the Solar disk are studied. Observations of the magnetic field, line-of-sight velocities and brightness have been made with the doublemagnetograph of the Crimean astrophysical observatory. It is found that the average magnetic field strength recorded in the iron line lambda 5233 A is 18 Gs for the elements of N-polarity and 23 Gs for the elements of S-polarity. The magnetic elements with the field strength more than 200 Gs are observed in some of the cases. There is a close correlation between the magnetic field distribution in the lambda 5250 A FeI and D/sub 1/ Na I lines and between the magnetic field in the lambda 5250 A and brightness in the K/sub 3/CaII line. The dimensions of the magnetic elements in the lambda and D/sub 1/NaI lines are equal. The comparison of the magnetic field with the radial velocity recorded in the lambda 5250 and 5233 A lines has shown that radial velocities are close to zero in the regions of maximum longitudinal magnetic field. The chromospheric network-like pattern is observed in the brightness distribution of ten different spectral lines.

The reliabilty of isokinetic strength measurement

OpenAIRE

Kadlec, Miroslav

2011-01-01

Title: Reliability of isometric and isokinetic strength testing in the knee flexion and extension Objectives: To compare the reliability of isometric and isokinetic testing of the knee strength in flexion and extension Methods: I used intraclass correlation coefficient and Pearson's correlation coefficient. Results: I have discovered that the reliability measured on isokinetic and isometric dynamometer is high. Furthermore the reliability of the maximum strength measurement was higher with-us...

Design, characterization, and application of fast, broadband, high-dynamic range, three-axis field strength probes

NARCIS (Netherlands)

Serra, Ramiro; Leferink, Frank Bernardus Johannes

2013-01-01

Conventional field strength sensors use different detection methods, each having advantages and disadvantages. Modern signals in, for instance, wireless communication systems and radars use very complex modulation. Other signals, such as the ones often measured in reverberation chambers with mode

Design, characterization and application of fast, broadband, high-dynamic range, three-axis field strength probes

NARCIS (Netherlands)

Serra, R.; Leferink, F.B.J.

2013-01-01

Conventional field strength sensors use different detection methods, each having advantages and disadvantages. Modern signals in, for instance, wireless communication systems and radars use very complex modulation. Other signals, such as the ones often measured in reverberation chambers with mode

Relativistic hadrodynamics with field-strength dependent coupling of the scalar fields in Hartree and Hartree-Fock approximation

International Nuclear Information System (INIS)

Lindner, J.

1992-09-01

In this thesis in the framework of our model of the field-strength dependent coupling the properties of infinitely extended, homogeneous, static, spin- and isospin-saturated nuclear matter are studied. Thereby we use the Hartree-Mean-Field and the Hartree-Fock approximation, whereby the influence of the antiparticle states in the Fermi sea is neglected. In chapter 2 the Lagrangian density basing to our model is fixed. Starting from the Walecka model we modify in the Lagrangian density the Linear coupling of the scalar field to the scalar density as follows g S φanti ψψ→g S f(φ) anti ψψ. In chapter 3 we fix three different functions f(φ). For these three cases and for the Walecka model with f(φ)=φ nuclear-matter calculations are performed. In chapter 4 for the Hartree-Fock calculations, but also very especially regarding the molecular-dynamics calculations, the properties of the Dirac spinors in the plane-wave representation are intensively studied. (orig.)

Back muscle strength, lifting, and stooped working postures.

Science.gov (United States)

Poulsen, E; Jørgensen, K

1971-09-01

When lifting loads and working in a forward stooped position, the muscles of the back rather than the ligaments and bony structures of the spine should overcome the gravitational forces. Formulae, based on measurements of back muscle strength, for prediction of maximal loads to be lifted, and for the ability to sustain work in a stooped position, have been worked out and tested in practical situations. From tests with 50 male and female subjects the simplest prediction formulae for maximum loads were: max. load = 1.10 x isometric back muscle strength for men; and max. load = 0.95 x isometric back muscle strength - 8 kg for women. Some standard values for maximum lifts and permissible single and repeated lifts have been calculated for men and women separately and are given in Table 1. From tests with 65 rehabilitees it was found that the maximum isometric strength of the back muscles measured at shoulder height should exceed 2/3 of the body weight, if fatigue and/or pain in the back muscles is to be avoided during work in a standing stooped position.

The retro-cut process: precision reshaping of magnetic quadrupole lens profiles to improve field strength

International Nuclear Information System (INIS)

Szymanski, Roland; Jamieson, David N.; Rout, Bibhudutta; Brenn, Ruediger

2005-01-01

In the evolution of magnetic quadrupole lens technology for nuclear microprobe systems, the pole profile has seen several improvements that have led to increases in the pole tip field for a given lens current. In a design dating from prior to 1994 the magnetic field strength was compromised by pole tip extensions that allowed significant flux leakage away from the central bore of the lens. There are many similar lenses in use world wide and they have a weaker focusing action compared to more modern designs which omit the pole tip extensions. We demonstrate that these pre-1994 lenses can have a new profile cut into the pole tip using a precision wire cutting machine that does not require the lens to be dismantled and does not compromise the purity of the lens field. We present the results of applying this process to lenses 1 and 4 in the antisymmetric quadruplet nuclear microprobe system at the University of Freiburg. The grid shadow method was used to show lens quality was not compromised by the process and we find that the lens field strength for a given current is increased by 15% when used to focus 2 MeV H + ions in the antisymmetric quadruplet

Signal-to-noise ratio, T2 , and T2* for hyperpolarized helium-3 MRI of the human lung at three magnetic field strengths.

Science.gov (United States)

Komlosi, Peter; Altes, Talissa A; Qing, Kun; Mooney, Karen E; Miller, G Wilson; Mata, Jaime F; de Lange, Eduard E; Tobias, William A; Cates, Gordon D; Mugler, John P

2017-10-01

To evaluate T 2 , T2*, and signal-to-noise ratio (SNR) for hyperpolarized helium-3 ( 3 He) MRI of the human lung at three magnetic field strengths ranging from 0.43T to 1.5T. Sixteen healthy volunteers were imaged using a commercial whole body scanner at 0.43T, 0.79T, and 1.5T. Whole-lung T 2 values were calculated from a Carr-Purcell-Meiboom-Gill spin-echo-train acquisition. T2* maps and SNR were determined from dual-echo and single-echo gradient-echo images, respectively. Mean whole-lung SNR values were normalized by ventilated lung volume and administered 3 He dose. As expected, T 2 and T2* values demonstrated a significant inverse relationship to field strength. Hyperpolarized 3 He images acquired at all three field strengths had comparable SNR values and thus appeared visually very similar. Nonetheless, the relatively small SNR differences among field strengths were statistically significant. Hyperpolarized 3 He images of the human lung with similar image quality were obtained at three field strengths ranging from 0.43T and 1.5T. The decrease in susceptibility effects at lower fields that are reflected in longer T 2 and T2* values may be advantageous for optimizing pulse sequences inherently sensitive to such effects. The three-fold increase in T2* at lower field strength would allow lower receiver bandwidths, providing a concomitant decrease in noise and relative increase in SNR. Magn Reson Med 78:1458-1463, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Dynamics of Entanglement in Jaynes–Cummings Nodes with Nonidentical Qubit-Field Coupling Strengths

Directory of Open Access Journals (Sweden)

Li-Tuo Shen

2017-07-01

Full Text Available How to analytically deal with the general entanglement dynamics of separate Jaynes–Cummings nodes with continuous-variable fields is still an open question, and few analytical approaches can be used to solve their general entanglement dynamics. Entanglement dynamics between two separate Jaynes–Cummings nodes are examined in this article. Both vacuum state and coherent state in the initial fields are considered through the numerical and analytical methods. The gap between two nonidentical qubit-field coupling strengths shifts the revival period and changes the revival amplitude of two-qubit entanglement. For vacuum-state fields, the maximal entanglement is fully revived after a gap-dependence period, within which the entanglement nonsmoothly decreases to zero and partly recovers without exhibiting sudden death phenomenon. For strong coherent-state fields, the two-qubit entanglement decays exponentially as the evolution time increases, exhibiting sudden death phenomenon, and the increasing gap accelerates the revival period and amplitude decay of the entanglement, where the numerical and analytical results have an excellent coincidence.

A practical method for estimating maximum shear modulus of cemented sands using unconfined compressive strength

Science.gov (United States)

Choo, Hyunwook; Nam, Hongyeop; Lee, Woojin

2017-12-01

The composition of naturally cemented deposits is very complicated; thus, estimating the maximum shear modulus (Gmax, or shear modulus at very small strains) of cemented sands using the previous empirical formulas is very difficult. The purpose of this experimental investigation is to evaluate the effects of particle size and cement type on the Gmax and unconfined compressive strength (qucs) of cemented sands, with the ultimate goal of estimating Gmax of cemented sands using qucs. Two sands were artificially cemented using Portland cement or gypsum under varying cement contents (2%-9%) and relative densities (30%-80%). Unconfined compression tests and bender element tests were performed, and the results from previous studies of two cemented sands were incorporated in this study. The results of this study demonstrate that the effect of particle size on the qucs and Gmax of four cemented sands is insignificant, and the variation of qucs and Gmax can be captured by the ratio between volume of void and volume of cement. qucs and Gmax of sand cemented with Portland cement are greater than those of sand cemented with gypsum. However, the relationship between qucs and Gmax of the cemented sand is not affected by the void ratio, cement type and cement content, revealing that Gmax of the complex naturally cemented soils with unknown in-situ void ratio, cement type and cement content can be estimated using qucs.

Influence of acute static stretching on the behavior of maximum muscle strength

Directory of Open Access Journals (Sweden)

Carmen Lúcia Borges Bastos

2014-06-01

Full Text Available The aim of this study was to compare the influence of acute static stretching on maximal muscle strength (1RM. The non-probabilistic sample consisted of 30 subjects split into two groups: static stretching (SS= 15 and without stretching group (WS= 15. Muscle strength evaluation (1RM was conducted with a Dynamometer model 32527pp400 Pound push / pull devices coupled in knee extension (KE and bench press (BP. The Wilcoxon test for intragroup comparisons and the Kruskal-Wallis test for comparisons between groups (p< 0.05 were selected. There were no significant differences (p> 0.05 between the SS and WS in exercise KE and BP. Therefore, it can be concluded that there was no reduction in the performance of 1RM performing the exercises KE and BP when preceded by static stretching.

Dynamic Analysis of the Abnormal Isometric Strength Movement Pattern between Shoulder and Elbow Joint in Patients with Hemiplegia.

Science.gov (United States)

Liu, Yali; Hong, Yuezhen; Ji, Linhong

2018-01-01

Patients with hemiplegia usually have weak muscle selectivity and usually perform strength at a secondary joint (secondary strength) during performing a strength at one joint (primary strength). The abnormal strength pattern between shoulder and elbow joint has been analyzed by the maximum value while the performing process with strength changing from 0 to maximum then to 0 was a dynamic process. The objective of this study was to develop a method to dynamically analyze the strength changing process. Ten patients were asked to perform four group asks (maximum and 50% maximum voluntary strength in shoulder abduction, shoulder adduction, elbow flexion, and elbow extension). Strength and activities from seven muscles were measured. The changes of secondary strength had significant correlation with those of primary strength in all tasks ( R > 0.76, p strength ( R > 0.4, p strength pattern (all p strength pattern. The muscles, deltoid muscles, biceps brachii, triceps brachii, and brachioradialis, much influenced the stereotyped movement pattern between shoulder and elbow joint.

Simultaneous Solar Maximum Mission (SMM) and Very Large Array (VLA) observations of solar active regions

Science.gov (United States)

Willson, Robert F.

1991-01-01

Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun.

Effect of 8 weeks of free-weight and machine-based strength training on strength and power performance

Directory of Open Access Journals (Sweden)

Wirth Klaus

2016-12-01

Full Text Available The aim of this study was to evaluate the effectiveness of free-weight and machine-based exercises to increase different strength and speed-strength variables. One hundred twenty male participants (age: 23.8 ± 2.5 years; body height: 181.0 ± 6.8 cm; body mass: 80.2 ± 8.9 kg joined the study. The 2 experimental groups completed an 8 week periodized strength training program that included 2 training sessions per week. The exercises that were used in the strength training programs were the parallel barbell squat and the leg press. Before and after the training period, the 1-repetition-maximum in the barbell squat and the leg press, the squat jump, the countermovement jump and unilateral isometric force (maximal isometric force and the rate of force development were evaluated. To compare each group pre vs. post-intervention, analysis of variance with repeated measures and Scheffé post-hoc tests were used. The leg press group increased their 1-repetition-maximum significantly (p < 0.001, while in the squat group such variables as 1-repetition-maximum, the squat jump and the countermovement jump increased significantly (p < 0.001. The maximal isometric force showed no statistically significant result for the repeated measures factor, while the rate of force development of the squat group even showed a statistically significant decrease. Differences between the 2 experimental groups were detected for the squat jump and the countermovement jump. In comparison with the leg press, the squat might be a better strength training exercise for the development of jump performance.

Surface magnetic field strengths: New tests of magnetoconvective models of M dwarfs

International Nuclear Information System (INIS)

MacDonald, James; Mullan, D. J.

2014-01-01

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 and 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.

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

Science.gov (United States)

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.

Strength Development: Using Functional Isometrics in an Isotonic Strength Training Program.

Science.gov (United States)

Jackson, Allen; And Others

1985-01-01

A study was made to determine if a combination of functional isometrics and standard isotonic training would be superior to a standard isotonic program in an instructional setting. The results provide support for functional isometrics as an enhancement where achievement of maximum strength is the goal. (Author/MT)

Low-field MRI can be more sensitive than high-field MRI

Science.gov (United States)

Coffey, Aaron M.; Truong, Milton L.; Chekmenev, Eduard Y.

2013-12-01

MRI signal-to-noise ratio (SNR) is the key factor for image quality. Conventionally, SNR is proportional to nuclear spin polarization, which scales linearly with magnetic field strength. Yet ever-stronger magnets present numerous technical and financial limitations. Low-field MRI can mitigate these constraints with equivalent SNR from non-equilibrium ‘hyperpolarization' schemes, which increase polarization by orders of magnitude independently of the magnetic field. Here, theory and experimental validation demonstrate that combination of field independent polarization (e.g. hyperpolarization) with frequency optimized MRI detection coils (i.e. multi-turn coils using the maximum allowed conductor length) results in low-field MRI sensitivity approaching and even rivaling that of high-field MRI. Four read-out frequencies were tested using samples with identical numbers of 1H and 13C spins. Experimental SNRs at 0.0475 T were ∼40% of those obtained at 4.7 T. Conservatively, theoretical SNRs at 0.0475 T 1.13-fold higher than those at 4.7 T were possible despite an ∼100-fold lower detection frequency, indicating feasibility of high-sensitivity MRI without technically challenging, expensive high-field magnets. The data at 4.7 T and 0.0475 T was obtained from different spectrometers with different RF probes. The SNR comparison between the two field strengths accounted for many differences in parameters such as system noise figures and variations in the probe detection coils including Q factors and coil diameters.

Maximal Strength Testing in Healthy Children.

Science.gov (United States)

Faigenbaum, Avery D.; Milliken, Laurie A.; Westcott, Wayne L.

2003-01-01

Evaluated the safety and efficacy of 1 repetition maximum (1RM) strength testing in healthy children age 6-12 years. Data were collected on 96 children who performed a 1RM test on one upper body and one lower body exercise using child-sized weight machines. Findings indicated that children could safely perform 1RM strength tests provided…

THE TECHNOLOGICAL AND EXPLOITATIVE FACTORS OF LOCAL INCREASE OF ELECTRIC FIELD STRENGTH IN THE POWER CABLE OF COAXIAL DESIGN

Directory of Open Access Journals (Sweden)

G. V. Bezprozvannych

2016-12-01

Full Text Available Introduction. Reliability of high voltage power cables in the process of long-term operation is largely due to the intensity of polymeric insulation aging. It is now established that the aging of polyethylene, which is the main material for the insulation of high voltage power cables, under the action of the electric field is determined primarily by the presence of structural heterogeneity arising both during cable production and during use. The cable is always there deviations from the ideal structure, which manifest in a deviation of diameters of conductors from nominal values; in the arrangement of the conductor and the insulation is not strictly coaxially and eccentrically; in elliptic (oval core and insulation; change in relative dielectric constant and thickness of insulation on cable length force the formation of low molecular weight products (including water in the flow at the manufacturing stage crosslinked polyethylene insulation and moisture during operation. Such defects are structural, technological and operational irregularities, which lead to a local change in the electric field. Purpose. Analysis of the influence of the eccentricity, elliptic and spherical inclusions in the electric field distribution in the power cable of a coaxial design with cross-linked polyethylene insulation, based on numerical simulation. Methodology. The bases of the numerical method of calculation of the electrical field strength are Fredholm integral equations of the first and second kind (method of secondary sources for an axially symmetric field. Analysis of the influence of irregularities, including water treeing, the shape of the sounding signal is made using the method of discrete resistive circuit inductance and capacitance of substitution with the initial conditions. Solving systems of linear algebraic equations nodal analysis performed by the sweep method. Results. The presence of the eccentricity and ellipticity in the construction of cable has

Effect of low transverse magnetic field on the confinement strength in a quasi-1D wire

International Nuclear Information System (INIS)

Kumar, Sanjeev; Thomas, K. J.; Smith, L. W.; Farrer, I.; Ritchie, D. A.; Jones, G. A. C.; Griffiths, J.; Pepper, M.

2013-01-01

Transport measurements in a quasi-one dimensional (1D) quantum wire are reported in the presence of low transverse magnetic field. Differential conductance shows weak quantised plateaus when the 2D electrons are squeezed electrostatically. Application of a small transverse magnetic field (0.2T) enhances the overall degree of quantisation due to the formation of magneto-electric subbands. The results show the role of magnetic field to fine tune the confinement strength in low density wires when interaction gives rise to double row formation

Behavior and strength of beams cast with ultra high strength concrete containing different types of fibers

Directory of Open Access Journals (Sweden)

M.M. Kamal

2014-04-01

Full Text Available Ultra-high performance concrete (UHPC is a special type of concrete with extraordinary potentials in terms of strength and durability performance. Its production and application implement the most up-to-date knowledge and technology of concrete manufacturing. Sophisticated structural designs in bridges and high-rise buildings, repair works and special structures like nuclear facilities are currently the main fields of applications of UHPC. This paper aimed to evaluate the behavior of ultra-high strength concrete beams. This paper also aimed to determine the effect of adding fibers and explore their effect upon the behavior and strength of the reinforced concrete beams. A total of twelve simple concrete beams with and without shear reinforcements were tested in flexure. The main variables taken into consideration in this research were the type of fibers and the percentage of longitudinal reinforcement as well as the existence or absence of the web reinforcement. Two types of fibers were used including steel and polypropylene fibers. The behavior of the tested beams was investigated with special attention to the deflection under different stages of loading, initial cracking, cracking pattern, and ultimate load. Increased number of cracks was observed at the end of loading due to the use of fibers, which led to the reduced width of cracks. This led to increased stiffness and higher values of maximum loads.

Quantitative diffusion tensor MR imaging of the brain: field strength related variance of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) scalars

International Nuclear Information System (INIS)

Huisman, Thierry A.G.M.; Loenneker, Thomas; Barta, Gerd; Bellemann, Matthias E.; Hennig, Juergen; Fischer, Joachim E.; Il'yasov, Kamil A.

2006-01-01

The objectives were to study the ''impact'' of the magnetic field strength on diffusion tensor imaging (DTI) metrics and also to determine whether magnetic-field-related differences in T2-relaxation times of brain tissue influence DTI measurements. DTI was performed on 12 healthy volunteers at 1.5 and 3.0 Tesla (within 2 h) using identical DTI scan parameters. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured at multiple gray and white matter locations. ADC and FA values were compared and analyzed for statistically significant differences. In addition, DTI measurements were performed at different echo times (TE) for both field strengths. ADC values for gray and white matter were statistically significantly lower at 3.0 Tesla compared with 1.5 Tesla (% change between -1.94% and -9.79%). FA values were statistically significantly higher at 3.0 Tesla compared with 1.5 Tesla (% change between +4.04 and 11.15%). ADC and FA values are not significantly different for TE=91 ms and TE=125 ms. Thus, ADC and FA values vary with the used field strength. Comparative clinical studies using ADC or FA values should consequently compare ADC or FA results with normative ADC or FA values that have been determined for the field strength used. (orig.)

Association Between Maximal Bench Press Strength and Isometric Handgrip Strength Among Breast Cancer Survivors.

Science.gov (United States)

Rogers, Benjamin H; Brown, Justin C; Gater, David R; Schmitz, Kathryn H

2017-02-01

To characterize the relationship between 1-repetition maximum (1-RM) bench press strength and isometric handgrip strength among breast cancer survivors. Cross-sectional study. Laboratory. Community-dwelling breast cancer survivors (N=295). Not applicable. 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer, with 3 maximal contractions of the left and right hands. All measures were conducted by staff with training in clinical exercise testing. Among 295 breast cancer survivors, 1-RM bench press strength was 18.2±6.1kg (range, 2.2-43.0kg), and isometric handgrip strength was 23.5±5.8kg (range, 9.0-43.0kg). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=.399; Pisometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7kg (95% limits of agreement, -8.2 to 17.6kg). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=.31; Pstrength (R 2 =.23). Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among breast cancer survivors. 1-RM bench press strength and isometric handgrip strength quantify distinct components of muscular strength. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

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

International Nuclear Information System (INIS)

Avara, Mark J.; Reynolds, Christopher S.; Bogdanović, Tamara

2013-01-01

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

The Importance of Muscular Strength: Training Considerations.

Science.gov (United States)

Suchomel, Timothy J; Nimphius, Sophia; Bellon, Christopher R; Stone, Michael H

2018-04-01

This review covers underlying physiological characteristics and training considerations that may affect muscular strength including improving maximal force expression and time-limited force expression. Strength is underpinned by a combination of morphological and neural factors including muscle cross-sectional area and architecture, musculotendinous stiffness, motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition. Although single- and multi-targeted block periodization models may produce the greatest strength-power benefits, concepts within each model must be considered within the limitations of the sport, athletes, and schedules. Bilateral training, eccentric training and accentuated eccentric loading, and variable resistance training may produce the greatest comprehensive strength adaptations. Bodyweight exercise, isolation exercises, plyometric exercise, unilateral exercise, and kettlebell training may be limited in their potential to improve maximal strength but are still relevant to strength development by challenging time-limited force expression and differentially challenging motor demands. Training to failure may not be necessary to improve maximum muscular strength and is likely not necessary for maximum gains in strength. Indeed, programming that combines heavy and light loads may improve strength and underpin other strength-power characteristics. Multiple sets appear to produce superior training benefits compared to single sets; however, an athlete's training status and the dose-response relationship must be considered. While 2- to 5-min interset rest intervals may produce the greatest strength-power benefits, rest interval length may vary based an athlete's training age, fiber type, and genetics. Weaker athletes should focus on developing strength before emphasizing power-type training. Stronger athletes may begin to emphasize power-type training while maintaining/improving their strength. Future research should

Polarized Line Formation in Arbitrary Strength Magnetic Fields Angle-averaged and Angle-dependent Partial Frequency Redistribution

Energy Technology Data Exchange (ETDEWEB)

Sampoorna, M.; Nagendra, K. N. [Indian Institute of Astrophysics, Koramangala, Bengaluru 560 034 (India); Stenflo, J. O., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in, E-mail: stenflo@astro.phys.ethz.ch [Institute of Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland)

2017-08-01

Magnetic fields in the solar atmosphere leave their fingerprints in the polarized spectrum of the Sun via the Hanle and Zeeman effects. While the Hanle and Zeeman effects dominate, respectively, in the weak and strong field regimes, both these effects jointly operate in the intermediate field strength regime. Therefore, it is necessary to solve the polarized line transfer equation, including the combined influence of Hanle and Zeeman effects. Furthermore, it is required to take into account the effects of partial frequency redistribution (PRD) in scattering when dealing with strong chromospheric lines with broad damping wings. In this paper, we present a numerical method to solve the problem of polarized PRD line formation in magnetic fields of arbitrary strength and orientation. This numerical method is based on the concept of operator perturbation. For our studies, we consider a two-level atom model without hyperfine structure and lower-level polarization. We compare the PRD idealization of angle-averaged Hanle–Zeeman redistribution matrices with the full treatment of angle-dependent PRD, to indicate when the idealized treatment is inadequate and what kind of polarization effects are specific to angle-dependent PRD. Because the angle-dependent treatment is presently computationally prohibitive when applied to realistic model atmospheres, we present the computed emergent Stokes profiles for a range of magnetic fields, with the assumption of an isothermal one-dimensional medium.

Relationship between isometric and dynamic strength in recreationally trained men.

Science.gov (United States)

McGuigan, Michael R; Newton, Michael J; Winchester, Jason B; Nelson, Arnold G

2010-09-01

The purpose of this investigation was to examine the relationships between measures of maximal isometric force (peak force [PF]), rate of force development (RFD), vertical jump performance (VJ) and 1-repetition maximum (1RM) strength in recreationally trained men. The subjects in this study were 26 men ([mean +/- SD]: age 22 +/- 1 years; height 175 +/- 7 cm; mass 90 +/- 10 kg). They were tested for PF using the isometric midthigh pull exercise. The 1RM for the squat and bench press exercise were determined as a measure of dynamic strength. Explosive strength was measured as RFD from the isometric force-time curve. Correlations between the variables were calculated using Pearson product moment correlation coefficient. There was a nearly perfect correlation between measures of PF and 1RM squat (r = 0.97, p isometric maximum strength determined during the isometric midthigh pull test correlated well with 1RM and VJ testing. However, RFD measured during the same test did not appear to correlate as well with other measures. The isometric midthigh pull provides an efficient method for assessing strength in recreationally trained individuals. Practitioners wishing to obtain performance data related to maximum strength may wish to consider isometric testing as a less time intensive method of testing.

Measuring Plasma Formation Field Strength and Current Loss in Pulsed Power Diodes

Energy Technology Data Exchange (ETDEWEB)

Johnston, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Patel, Sonal G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Falcon, Ross Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Cartwright, Keith [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Kiefer, Mark L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Cuneo, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Maron, Yitzhak [Weizmann Inst. of Science, Rehovot (Israel)

2017-11-01

This LDRD investigated plasma formation, field strength, and current loss in pulsed power diodes. In particular the Self-Magnetic Pinch (SMP) e-beam diode was studied on the RITS-6 accelerator. Magnetic fields of a few Tesla and electric fields of several MV/cm were measured using visible spectroscopy techniques. The magnetic field measurements were then used to determine the current distribution in the diode. This distribution showed that significant beam current extends radially beyond the few millimeter x-ray focal spot diameter. Additionally, shielding of the magnetic field due to dense electrode surface plasmas was observed, quantified, and found to be consistent with the calculated Spitzer resistivity. In addition to the work on RITS, measurements were also made on the Z-machine looking to quantify plasmas within the power flow regions. Measurements were taken in the post-hole convolute and final feed gap regions on Z. Dopants were applied to power flow surfaces and measured spectroscopically. These measurements gave species and density/temperature estimates. Preliminary B-field measurements in the load region were attempted as well. Finally, simulation work using the EMPHASIS, electromagnetic particle in cell code, was conducted using the Z MITL conditions. The purpose of these simulations was to investigate several surface plasma generations models under Z conditions for comparison with experimental data.

Enhancing paper strength by optimizing defect configuration

Science.gov (United States)

J.M. Considine; W. Skye; W. Chen; D. Matthys; David W. Vahey; K. Turner; R. Rowlands

2009-01-01

Poor formation in paper, as denoted by large local variation of mass, tends to reduce maximum tensile strength but has not been well characterized. The effect of grammage variation on tensile strength was studied by introducing carefully placed holes in tensile specimens made of three different paper materials. Previous researchers demonstrated that the point-stress...

Optimum coil shape for a given volume of conductor to obtain maximum central field in an air core solenoid

Energy Technology Data Exchange (ETDEWEB)

Hernandez, P. [Lawrence Berkeley Lab., CA (United States)

1995-02-01

This paper is an expansion of engineering notes prepared in 1961 to address the question of how to wind circular coils so as to obtain the maximum axial field with the minimum volume of conductor. At the time this was a germain question because of the advent of superconducting wires which were in very limited supply, and the rapid push for generation of very high fields, with little concern for uniformity.

An open, multi-vendor, multi-field-strength brain MR dataset and analysis of publicly available skull stripping methods agreement.

Science.gov (United States)

Souza, Roberto; Lucena, Oeslle; Garrafa, Julia; Gobbi, David; Saluzzi, Marina; Appenzeller, Simone; Rittner, Letícia; Frayne, Richard; Lotufo, Roberto

2018-04-15

This paper presents an open, multi-vendor, multi-field strength magnetic resonance (MR) T1-weighted volumetric brain imaging dataset, named Calgary-Campinas-359 (CC-359). The dataset is composed of images of older healthy adults (29-80 years) acquired on scanners from three vendors (Siemens, Philips and General Electric) at both 1.5 T and 3 T. CC-359 is comprised of 359 datasets, approximately 60 subjects per vendor and magnetic field strength. The dataset is approximately age and gender balanced, subject to the constraints of the available images. It provides consensus brain extraction masks for all volumes generated using supervised classification. Manual segmentation results for twelve randomly selected subjects performed by an expert are also provided. The CC-359 dataset allows investigation of 1) the influences of both vendor and magnetic field strength on quantitative analysis of brain MR; 2) parameter optimization for automatic segmentation methods; and potentially 3) machine learning classifiers with big data, specifically those based on deep learning methods, as these approaches require a large amount of data. To illustrate the utility of this dataset, we compared to the results of a supervised classifier, the results of eight publicly available skull stripping methods and one publicly available consensus algorithm. A linear mixed effects model analysis indicated that vendor (p-valuefield strength (p-value<0.001) have statistically significant impacts on skull stripping results. Copyright © 2017 Elsevier Inc. All rights reserved.

High-field-strength MR imaging evaluation of stroke in the sickle cell population

International Nuclear Information System (INIS)

Bello, J.A.; Pavlakis, S.G.; Prohovnik, I.; Hilal, S.K.; De Vivo, D.C.

1987-01-01

Stroke is a well-known but understudied complication of sickle cell disease (SCD). The authors have studied the incidence and patterns of clinical and subclinical stroke in 73 SCD patients. The patients underwent formal neurologic evaluation and high-field strength, heavily T2-weighted axial cranial MR imaging (TR = 3,500 msec, TE = 80 msec). Eighteen of the 73 patients had clinical strokes, acute, nonconvulsive neurologic events with lateralizing neurological signs lasting 1 hour. All but two of these patients demonstrated focal MR imaging abnormalities. The remaining 55 patients were controls. Ten percent of them had focal MR imaging abnormalities suggesting subclinical stroke. A feature of the SCD population is the preponderance of strokes in the distal field and watershed distribution

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

Science.gov (United States)

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. Copyright © 2016 Elsevier Inc. All rights reserved.

Improved Maximum Strength, Vertical Jump and Sprint Performance after 8 Weeks of Jump Squat Training with Individualized Loads

Science.gov (United States)

Marián, Vanderka; Katarína, Longová; Dávid, Olasz; Matúš, Krčmár; Simon, Walker

2016-01-01

The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax) and rate of force development over 100ms (RFD100), countermovement jump (CMJ) and squat jump (SJ) height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg) were divided into experimental (EXP; n = 36) and control (CON, n = 32) groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets of 4 repetitions). Subjects were given real-time feedback for every repetition during the training sessions. Significant improvements in Fmax from pre- to mid- (Δ ~14%, psquats with loads that allow repetitions to be performed ≥90% of maximum average power output can simultaneously improve several different athletic performance tasks in the short-term. Key points Jump squat exercise is one of many exercises to develop explosive strength that has been the focus of several researches, while the load used during the training seem to be an important factor that affects training outcomes. Experimental group improved performance in all assessed parameters, such as Fmax, RFD100, CMJ, SJ and 50 m sprint time. However, improvements in CMJ and SJ were recorded after the entire power training period and thereafter plateau occurred. The portable FitroDyne could serve as a valuable device to individualize the load that maximizes mean power output and visual feedback can be provided to athletes during the training. PMID:27803628

Dynamic Analysis of the Abnormal Isometric Strength Movement Pattern between Shoulder and Elbow Joint in Patients with Hemiplegia

Directory of Open Access Journals (Sweden)

Yali Liu

2018-01-01

Full Text Available Patients with hemiplegia usually have weak muscle selectivity and usually perform strength at a secondary joint (secondary strength during performing a strength at one joint (primary strength. The abnormal strength pattern between shoulder and elbow joint has been analyzed by the maximum value while the performing process with strength changing from 0 to maximum then to 0 was a dynamic process. The objective of this study was to develop a method to dynamically analyze the strength changing process. Ten patients were asked to perform four group asks (maximum and 50% maximum voluntary strength in shoulder abduction, shoulder adduction, elbow flexion, and elbow extension. Strength and activities from seven muscles were measured. The changes of secondary strength had significant correlation with those of primary strength in all tasks (R>0.76, p0.4, p<0.01. Deltoid muscles, biceps brachii, triceps brachii, and brachioradialis had significant influences on the abnormal strength pattern (all p<0.01. The dynamic method was proved to be efficient to analyze the different influences of muscles on the abnormal strength pattern. The muscles, deltoid muscles, biceps brachii, triceps brachii, and brachioradialis, much influenced the stereotyped movement pattern between shoulder and elbow joint.

Transient-field strength measurements for 52Cr traversing Fe hosts at high velocity and polarization transfer mechanisms

International Nuclear Information System (INIS)

Stuchbery, A.E.; Doran, C.E.; Byrne, A.P.; Bolotin, H.H.; Dracoulis, G.D.

1986-12-01

Transient-field strengths were measured for 52 Cr ions traversing polarized Fe hosts at velocities up to 12v>=o (v>=o = c/137 = Bohr velocity). The results are compared with predictions of various transient field parametrizations and discussed in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving Cr ions. The g-factor of the first 2 + state of 52 Cr was also measured by the transient field technique and found to be in accord with shell-model calculations

The Maximum Entropy Limit of Small-scale Magnetic Field Fluctuations in the Quiet Sun

Science.gov (United States)

Gorobets, A. Y.; Berdyugina, S. V.; Riethmüller, T. L.; Blanco Rodríguez, J.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; van Noort, M.; Del Toro Iniesta, J. C.; Orozco Suárez, D.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.

2017-11-01

The observed magnetic field on the solar surface is characterized by a very complex spatial and temporal behavior. Although feature-tracking algorithms have allowed us to deepen our understanding of this behavior, subjectivity plays an important role in the identification and tracking of such features. In this paper, we continue studies of the temporal stochasticity of the magnetic field on the solar surface without relying either on the concept of magnetic features or on subjective assumptions about their identification and interaction. We propose a data analysis method to quantify fluctuations of the line-of-sight magnetic field by means of reducing the temporal field’s evolution to the regular Markov process. We build a representative model of fluctuations converging to the unique stationary (equilibrium) distribution in the long time limit with maximum entropy. We obtained different rates of convergence to the equilibrium at fixed noise cutoff for two sets of data. This indicates a strong influence of the data spatial resolution and mixing-polarity fluctuations on the relaxation process. The analysis is applied to observations of magnetic fields of the relatively quiet areas around an active region carried out during the second flight of the Sunrise/IMaX and quiet Sun areas at the disk center from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory satellite.

Effect of Hybrid Fibers on the Mechanical Properties of High Strength Concrete

Directory of Open Access Journals (Sweden)

Hamid H. Hussein, Saeed K. Rejeb Hayder T. Abd

2014-04-01

Full Text Available In this study, high strength concrete of 75 MPa compressive strength was investigated. The experimental program was designed to study the effect of fibers and hybrid fibers (steel and polypropylene fibers on the fresh (workability and wet density and hardened properties (compressive strength, splitting strength, flexural strength and dry density of high strength concrete. Results show that decreases in slump flow of all concrete mixtures containing steel, polypropylene and hybrid fibers compared with control mix (0% fiber. Hybrid high strength concrete with steel and polypropylene fibers showed superior compressive, splitting, flexural strengths over the others concrete without or with single fibers content. The test results indicate that the maximum increase in compressive and flexural strengths are obtains with the hybridization ratio (70%steel + 30% polypropylene and were equal to 14.54% and 23.34% respectively, compared with the control mix. While, the maximum increase in splitting tensile strength with (100% steel fiber + 0 polypropylene is 21.19%. 

Weakening of flux-pinning strength for high-Tc superconductors in an alternating magnetic field

International Nuclear Information System (INIS)

Chen, Q.Y.

1992-01-01

This paper reports on the flux-pinning forces in high temperature superconductors which were found to be weakened in an ac field as the applied field strength or the frequency increases. In the weakly pinned regime, flux dynamics could be described with the concept of magnetic diffusion. Flux-motion-induced finite resistivity could lead to significant skin-effect which was reflected in the ac screening effectiveness. The frequency dependence of the relative local field within a superconducting hollow cylinder were used to deduce the flux-motion resistivity ρ. For superconducting YB 2 Cu 3 O 7 - x compounds at 77K it was found that ρ ∼(mu, Omega)-cm. The corresponding magnetic diffusion coefficient was ∼ 224 cm 2 /s. At 750 Hz the skin depth is around 1.54 mm as compared with the 2-mm sample wall thickness

Variation of the dimensions and the strength of electrical ceramics during irradiation

International Nuclear Information System (INIS)

Blaunshtein, I.M.; Kishinevskaya, M.B.; Muminov, M.I.

1988-01-01

Changes were studied in the linear dimensions and the ultimate bend strength of a wide range or ceramic materials (MK and GB7 high-alumina ceramics, the UF-46 mullite-corundum ceramic, SNTs and SK-1 steatite ceramics, and the glasses that have the same chemical composition as that of the glass phase of the GB-7 and UF-46 ceramics) following irradiation with a gamma beam from a Co 60 source and in the field of mixed gamma-neutron radiation from a VVR-SM reactor up to the maximum doses

From “Smaller is Stronger” to “Size-Independent Strength Plateau”: Towards Measuring the Ideal Strength of Iron

KAUST Repository

Han, Wei-Zhong; Huang, Ling; Ogata, Shigenobu; Kimizuka, Hajime; Yang, Zhao-Chun; Weinberger, Christopher; Li, Qing-Jie; Liu, Bo-Yu; Zhang, Xixiang; Li, Ju; Ma, Evan; Shan, Zhi-Wei

2015-01-01

The trend from “smaller is stronger” to “size-independent strength plateau” is observed in the compression of spherical iron nanoparticles. When the diameter of iron nanospheres is less than a critical value, the maximum contact pressure saturates at 10.7 GPa, corresponding to a local shear stress of ≈9.4 GPa, which is comparable to the theoretical shear strength of iron.

From “Smaller is Stronger” to “Size-Independent Strength Plateau”: Towards Measuring the Ideal Strength of Iron

KAUST Repository

Han, Wei-Zhong

2015-04-17

The trend from “smaller is stronger” to “size-independent strength plateau” is observed in the compression of spherical iron nanoparticles. When the diameter of iron nanospheres is less than a critical value, the maximum contact pressure saturates at 10.7 GPa, corresponding to a local shear stress of ≈9.4 GPa, which is comparable to the theoretical shear strength of iron.

Large-scale, near-Earth, magnetic fields from external sources and the corresponding induced internal field

Science.gov (United States)

Langel, R. A.; Estes, R. H.

1983-01-01

Data from MAGSAT analyzed as a function of the Dst index to determine the first degree/order spherical harmonic description of the near-Earth external field and its corresponding induced field. The analysis was done separately for data from dawn and dusk. The MAGSAT data was compared with POGO data. A local time variation of the external field persists even during very quiet magnetic conditions; both a diurnal and 8-hour period are present. A crude estimate of Sq current in the 45 deg geomagnetic latitude range is obtained for 1966 to 1970. The current strength, located in the ionosphere and induced in the Earth, is typical of earlier determinations from surface data, although its maximum is displaced in local time from previous results.

Strength Determinants of Jump Height in the Jump Throw Movement in Women Handball Players.

Science.gov (United States)

McGhie, David; Østerås, Sindre; Ettema, Gertjan; Paulsen, Gøran; Sandbakk, Øyvind

2018-06-08

McGhie, D, Østerås, S, Ettema, G, Paulsen, G, and Sandbakk, Ø. Strength determinants of jump height in the jump throw movement in women handball players. J Strength Cond Res XX(X): 000-000, 2018-The purpose of the study was to improve the understanding of the strength demands of a handball-specific jump through examining the associations between jump height in a jump throw jump (JTJ) and measures of lower-body maximum strength and impulse in handball players. For comparison, whether the associations between jump height and strength differed between the JTJ and the customarily used countermovement jump (CMJ) was also examined. Twenty women handball players from a Norwegian top division club participated in the study. Jump height was measured in the JTJ and in unilateral and bilateral CMJ. Lower-body strength (maximum isometric force, one-repetition maximum [1RM], impulse at ∼60% and ∼35% 1RM) was measured in seated leg press. The associations between jump height and strength were assessed with correlation analyses and t-tests of dependent r's were performed to determine if correlations differed between jump tests. Only impulse at ∼35% 1RM correlated significantly with JTJ height (p jump height and strength were significantly weaker in the JTJ than in both CMJ tests for all strength measures (p = 0.001-0.044) except one. Maximum strength and impulse at ∼60% 1RM did not seem to sufficiently capture the capabilities associated with JTJ height, highlighting the importance of employing tests targeting performance-relevant neuromuscular characteristics when assessing jump-related strength in handball players. Further, CMJ height seemed to represent a wider range of strength capabilities and care should be taken when using it as a proxy for handball-specific movements.

Last three millennia Earth's Magnetic field strength in Mesoamerica and southern United States: Implications in geomagnetism and archaeology

Science.gov (United States)

Goguitchaichvili, Avto; Ruiz, Rafael García; Pavón-Carrasco, F. Javier; Contreras, Juan Julio Morales; Arechalde, Ana María Soler; Urrutia-Fucugauchi, Jaime

2018-06-01

Earth's Magnetic Field variation strength may provide crucial information to understand the geodynamo mechanism and elucidate the conditions on the physics of the Earth's deep interiors. Aimed to reveal the fine characteristics of the geomagnetic field during the last three millennia in Mesoamerica, we analyzed the available absolute geomagnetic intensities associated to absolute radiometric dating as well some ages provided by historical documents. This analysis is achieved using thermoremanent magnetization carried by volcanic lava flows and burned archaeological artefacts. A total of 106 selected intensities from Mesoamerica and other 100 from the southern part of the United States represent the main core of the dataset to construct the variation curve using both combined bootstrap method and temporal penalized B-spline methods. The obtained intensity paleosecular variation curve for Mesoamerica generally disagrees with the values predicted by the global geomagnetic field models. There is rather firm evidence of eastward drift when compared to similar reference curves in Western Europe, Asia and Pacific Ocean. The recent hypothesis about the relationship between the geomagnetic field strength and paleoclimate is also critically analyzed in the light of this new data compilation.

A review of the safety implications of magnetic resonance imaging at field strengths of 3 Tesla and above

International Nuclear Information System (INIS)

Crook, Neil; Robinson, Leslie

2009-01-01

Rationale: Diagnostic imaging is being driven by technological developments particularly so in the field of Magnetic Resonance Imaging (MRI). Electromagnetic fields used to produce images are becoming much stronger and switched more rapidly and it is essential that safety advice remains appropriate and current. Using a systematic methodology, this review aims to identify the clinical safety implications in performing MRI at field strengths of 3 Tesla (T) and above and determine whether the current clinical safety guidelines are appropriate. Method: References were sourced from The Cochrane Library, Centre for Reviews and Dissemination Science Direct, PubMed and Google Scholar. Related websites searched included The British Institute of Radiology, Society of Radiographers, Royal College of Radiologists, The Institution of Engineering and Technology, IMRSER (Institute for Magnetic Resonance Safety, Education, and Research), MagNet (NHS PASA). References supplied in retrieved papers were also checked for potential relevance. The use of consistent search terminology and inclusion and exclusion criteria ensured quality and provided rigour to conclusions drawn. Conclusion: According to the literature retrieved, the current body of knowledge has allowed safety guidelines to be established for patient safety and these are both appropriate and valid at field strengths of 3 T.

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

Science.gov (United States)

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. © 2012 Optical Society of America

Effects of small defects and nonmetallic inclusions on the fatigue strength of metals

International Nuclear Information System (INIS)

Murakami, Y.

1991-01-01

The equation for predicting the effects of artificial small defects on the fatigue strength of metals is introduced, and it is applied to the quantitative evaluation of the effects of nonmetallic inclusions on the fatigue strength of high-strength steels. The importance of the concept that nonmetallic inclusions are virtually equivalent to defects, from the viewpoint of fatigue strength and, more practically, are equivalent to small cracks is emphasized. It is shown that nonmetallic inclusions cause relatively low-fatigue strength and large scatter of the fatigue strength of steels with high static strength or high hardness. The statistics of extreme values is used to estimate the expected maximum size of nonmetallic inclusions contained in a definite number of specimens. The lower limit of scatter in the fatigue strength of a high-strength steel is obtained by using the prediction equation for small defects together with the expected maximum size of nonmetallic inclusions

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

International Nuclear Information System (INIS)

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

2008-01-01

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.

CHARACTERISTICS OF MAXIMUM PERFORMANCE OF PEDALING EXERCISE IN RECUMBENT AND SUPINE POSITIONS

Directory of Open Access Journals (Sweden)

Morimasa Kato

2011-09-01

Full Text Available To determine the characteristics of maximum pedaling performance in the recumbent and supine positions, maximum isokinetic leg muscle strength was measured in eight healthy male subjects during pedaling at three velocities (300°/s, 480°/s, and 660°/s, and maximum incremental tests were performed for each position. The maximum isokinetic muscle strength in the recumbent position was 210.0 ± 29.2 Nm at 300°/s, 158.4 ± 19.8 Nm at 480°/s, and 110.6 ± 13.2 at 660°/s. In contrast, the muscle strength in the supine position was 229.3 ± 36.7 Nm at 300°/s, 180. 7 ± 20.3 Nm at 480°/s, and 129.6 ± 14.0 Nm at 660°/s. Thus, the maximum isokinetic muscle strength showed significantly higher values in the supine position than in the recumbent position at all angular velocities. The knee and hip joint angles were measured at peak torque using a goniometer; the knee joint angle was not significantly different between both positions, whereas the hip joint angle was greater in the supine position than in the recumbent position (Supine position: 137.3 ± 9. 33 degree at 300°/s, 140.0 ± 11.13 degrees at 480°/s, and 141.0 ± 9.61 degrees at 660°/s. Recumbent position: 99.5 ± 12.21 degrees at 300°/s, 101.6 ± 12.29 degrees at 480°/s, and 105.8 ± 14.28 degrees at 660°/s. Peak oxygen uptake was higher in the recumbent position (50.3 ± 4.43 ml·kg-1·min-1 than in the supine position (48.7 ± 5.10 ml·kg-1·min-1. At maximum exertion, the heart rate and whole-body rate of perceived exertion (RPE were unaffected by position, but leg muscle RPE was higher in the supine position (19.5 ± 0.53 than in the recumbent position (18.8 ± 0.71. These results suggest that the supine position is more suitable for muscle strength exertion than the recumbent position, and this may be due to different hip joint angles between the positions. On the contrary, the endurance capacity was higher in the recumbent position than in the supine position. Since leg muscle

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

Science.gov (United States)

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

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

International Nuclear Information System (INIS)

Joyner, K. H.; Van Wyk, M. J.; Rowley, J. 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 these 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. (authors)

The Association between Maximal Bench Press Strength and Isometric Handgrip Strength among Breast Cancer Survivors

Science.gov (United States)

Rogers, Benjamin H.; Brown, Justin C.; Gater, David R.; Schmitz, Kathryn H.

2016-01-01

Objective One-repetition maximum (1-RM) bench press strength is considered the gold standard to quantify upper-body muscular strength. Isometric handgrip strength is frequently used as a surrogate for 1-RM bench press strength among breast cancer (BrCa) survivors. The relationship between 1-RM bench press strength and isometric handgrip strength, however, has not been characterized among BrCa survivors. Design Cross-sectional study. Setting Laboratory. Participants Community-dwelling BrCa survivors. Interventions Not applicable. Main Outcome Measure 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer with three maximal contractions of left and right hands. All measures were conducted by staff with training in clinical exercise testing. Results Among 295 BrCa survivors, 1-RM bench press strength was 18.2±6.1 kg (range: 2.2-43.0) and isometric handgrip strength was 23.5±5.8 kg (range: 9.0-43.0). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=0.399; Pisometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7 kg (95% limits of agreement: −8.2 to 17.6). In a multivariable linear regression model, the average isometric handgrip strength of both hands (β=0.31; Pstrength (R2=0.23). Conclusions Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among BrCa survivors. 1-RM bench press and isometric handgrip strength quantify distinct components of muscular strength. PMID:27543047

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

Science.gov (United States)

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

Preventive strength training improves working ergonomics during welding.

Science.gov (United States)

Krüger, Karsten; Petermann, Carmen; Pilat, Christian; Schubert, Emil; Pons-Kühnemann, Jörn; Mooren, Frank C

2015-01-01

To investigate the effect of a preventive strength training program on cardiovascular, metabolic and muscular strains during welding. Welders are one of the occupation groups which typically have to work in extended forced postures which are known to be an important reason for musculoskeletal disorders. Subjects (exercise group) accomplished a 12-week strength training program, while another group served as controls (control group). Pre and post training examinations included the measurements of the one repetition maximum and an experimental welding test. Local muscle activities were analysed by surface electromyography. Furthermore, heart rate, blood pressure, lactate and rating of perceived exertion were examined. In the exercise group, strength training lead to a significant increase of one repetition maximum in all examined muscles (pwelding test muscle activities of trunk and shoulder muscles and arm muscles were significantly reduced in the exercise group after intervention (pwelding (p<.05). Effects of strength training can be translated in an improved working ergonomics and tolerance against the exposure to high physical demands at work.

Effect of Training Frequency on Maximum Expiratory Pressure

Science.gov (United States)

Anand, Supraja; El-Bashiti, Nour; Sapienza, Christine

2012-01-01

Purpose: To determine the effects of expiratory muscle strength training (EMST) frequency on maximum expiratory pressure (MEP). Method: We assigned 12 healthy participants to 2 groups of training frequency (3 days per week and 5 days per week). They completed a 4-week training program on an EMST trainer (Aspire Products, LLC). MEP was the primary…

The one repetition maximum test and the sit-to-stand test in the assessment of a specific pulmonary rehabilitation program on peripheral muscle strength in COPD patients.

Science.gov (United States)

Zanini, Andrea; Aiello, Marina; Cherubino, Francesca; Zampogna, Elisabetta; Azzola, Andrea; Chetta, Alfredo; Spanevello, Antonio

2015-01-01

Individuals with COPD may present reduced peripheral muscle strength, leading to impaired mobility. Comprehensive pulmonary rehabilitation (PR) should include strength training, in particular to lower limbs. Furthermore, simple tools for the assessment of peripheral muscle performance are required. To assess the peripheral muscle performance of COPD patients by the sit-to-stand test (STST), as compared to the one-repetition maximum (1-RM), considered as the gold standard for assessing muscle strength in non-laboratory situations, and to evaluate the responsiveness of STST to a PR program. Sixty moderate-to-severe COPD inpatients were randomly included into either the specific strength training group or into the usual PR program group. Patients were assessed on a 30-second STST and 1-minute STST, 1-RM, and 6-minute walking test (6MWT), before and after PR. Bland-Altman plots were used to evaluate the agreement between 1-RM and STST. The two groups were not different at baseline. In all patients, 1-RM was significantly related to the 30-second STST (r=0.48, Ptest. In the specific strength training group significant improvements were observed in the 30-second STST (P<0.001), 1-minute STST (P=0.005), 1-RM (P<0.001), and in the 6MWT (P=0.001). In the usual PR program group, significant improvement was observed in the 30-second STST (P=0.042) and in the 6MWT (P=0.001). Our study shows that in stable moderate-to-severe inpatients with COPD, STST is a valid and reliable tool to assess peripheral muscle performance of lower limbs, and is sensitive to a specific PR program.

Maximum likelihood as a common computational framework in tomotherapy

International Nuclear Information System (INIS)

Olivera, G.H.; Shepard, D.M.; Reckwerdt, P.J.; Ruchala, K.; Zachman, J.; Fitchard, E.E.; Mackie, T.R.

1998-01-01

Tomotherapy is a dose delivery technique using helical or axial intensity modulated beams. One of the strengths of the tomotherapy concept is that it can incorporate a number of processes into a single piece of equipment. These processes include treatment optimization planning, dose reconstruction and kilovoltage/megavoltage image reconstruction. A common computational technique that could be used for all of these processes would be very appealing. The maximum likelihood estimator, originally developed for emission tomography, can serve as a useful tool in imaging and radiotherapy. We believe that this approach can play an important role in the processes of optimization planning, dose reconstruction and kilovoltage and/or megavoltage image reconstruction. These processes involve computations that require comparable physical methods. They are also based on equivalent assumptions, and they have similar mathematical solutions. As a result, the maximum likelihood approach is able to provide a common framework for all three of these computational problems. We will demonstrate how maximum likelihood methods can be applied to optimization planning, dose reconstruction and megavoltage image reconstruction in tomotherapy. Results for planning optimization, dose reconstruction and megavoltage image reconstruction will be presented. Strengths and weaknesses of the methodology are analysed. Future directions for this work are also suggested. (author)

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

Science.gov (United States)

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.

Relationship between strength qualities and short track speed skating performance in young athletes.

Science.gov (United States)

Felser, S; Behrens, M; Fischer, S; Heise, S; Bäumler, M; Salomon, R; Bruhn, S

2016-02-01

This study analyzed the relationships between isometric as well as concentric maximum voluntary contraction (MVC) strength of the leg muscles and the times as well as speeds over different distances in 17 young short track speed skaters. Isometric as well as concentric single-joint MVC strength and multi-joint MVC strength in a stable (without skates) and unstable (with skates) condition were tested. Furthermore, time during maximum skating performances on ice was measured. Results indicate that maximum torques during eversion and dorsal flexion have a significant influence on skating speed. Concentric MVC strength of the knee extensors was higher correlated with times as well as speeds over the different distances than isometric MVC strength. Multi-joint MVC testing revealed that the force loss between measurements without and with skates amounts to 25%, while biceps femoris and soleus showed decreased muscle activity and peroneus longus, tibialis anterior, as well as rectus femoris exhibited increased muscle activity. The results of this study depict evidence that the skating times and speeds are primarily influenced by concentric MVC strength of the leg extensors. To be able to transfer the strength onto ice in an optimal way, it is necessary to stabilize the knee and ankle joints. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Avinash-Shukla mass limit for the maximum dust mass supported against gravity by electric fields

Science.gov (United States)

Avinash, K.

2010-08-01

The existence of a new class of astrophysical objects, where gravity is balanced by the shielded electric fields associated with the electric charge on the dust, is shown. Further, a mass limit MA for the maximum dust mass that can be supported against gravitational collapse by these fields is obtained. If the total mass of the dust in the interstellar cloud MD > MA, the dust collapses, while if MD < MA, stable equilibrium may be achieved. Heuristic arguments are given to show that the physics of the mass limit is similar to the Chandrasekar's mass limit for compact objects and the similarity of these dust configurations with neutron and white dwarfs is pointed out. The effect of grain size distribution on the mass limit and strong correlation effects in the core of such objects is discussed. Possible location of these dust configurations inside interstellar clouds is pointed out.

Influence of field strength, coil type and image resolution on assessment of synovitis by unenhanced MRI - a comparison with contrast-enhanced MRI

International Nuclear Information System (INIS)

Eshed, Iris; Krabbe, Simon; Axelsen, Mette; Pedersen, Susanne Juhl; Oestergaard, Mikkel; Boeyesen, Pernille; Moeller, Jakob M.; Therkildsen, Flemming; Madsen, Ole Rintek

2015-01-01

To explore if the reliability of synovitis assessment by unenhanced MRI is influenced by different MRI field-strengths, coil types and image resolutions in RA patients. Forty-one RA patients and 12 healthy controls underwent hand MRI (wrist and 2 nd -5 th metacarpophalangeal joints) at 4 different field-strengths (0.23 T/0.6 T/1.5 T/3.0 T) on the same day. Seven protocols using a STIR sequence with different field-strengths, coils (flex coils/dedicated phased-array extremity coils) and resolution were applied and scored blindly for synovitis (OMERACT-RAMRIS method). A 1.5 T post-contrast T1-weighted sequence was used as gold standard reference. Fair-good agreement (ICC=0.38-0.72) between the standard reference and the different STIR protocols (best agreement with extremity coil and small voxel size at 1.5 T). The accuracy for presence/absence of synovitis was very high per person (0.80-1.0), and moderate-high per joint (0.63-0.85), whereas exact agreements on scores were moderate (0.50-0.66). The intrareader agreement (15 patients and 3 controls) on presence/absence of synovitis was very high (0.87-1.0). Unenhanced MRI using STIR sequence is only moderately reliable for assessing hand synovitis in RA, when contrast-enhanced MRI is considered the gold standard reference. Contrast injection, field strength and coil type influence synovitis assessment, and should be considered before performing MRI in clinical trials and practice. (orig.)

Determination of strength exercise intensities based on the load-power-velocity relationship.

Science.gov (United States)

Jandačka, Daniel; Beremlijski, Petr

2011-06-01

The velocity of movement and applied load affect the production of mechanical power output and subsequently the extent of the adaptation stimulus in strength exercises. We do not know of any known function describing the relationship of power and velocity and load in the bench press exercise. The objective of the study is to find a function modeling of the relationship of relative velocity, relative load and mechanical power output for the bench press exercise and to determine the intensity zones of the exercise for specifically focused strength training of soccer players. Fifteen highly trained soccer players at the start of a competition period were studied. The subjects of study performed bench presses with the load of 0, 10, 30, 50, 70 and 90% of the predetermined one repetition maximum with maximum possible speed of movement. The mean measured power and velocity for each load (kg) were used to develop a multiple linear regression function which describes the quadratic relationship between the ratio of power (W) to maximum power (W) and the ratios of the load (kg) to one repetition maximum (kg) and the velocity (m•s(-1)) to maximal velocity (m•s(-1)). The quadratic function of two variables that modeled the searched relationship explained 74% of measured values in the acceleration phase and 75% of measured values from the entire extent of the positive power movement in the lift. The optimal load for reaching maximum power output suitable for the dynamics effort strength training was 40% of one repetition maximum, while the optimal mean velocity would be 75% of maximal velocity. Moreover, four zones: maximum power, maximum velocity, velocity-power and strength-power were determined on the basis of the regression function.

Kettlebell swing training improves maximal and explosive strength.

Science.gov (United States)

Lake, Jason P; Lauder, Mike A

2012-08-01

The aim of this study was to establish the effect that kettlebell swing (KB) training had on measures of maximum (half squat-HS-1 repetition maximum [1RM]) and explosive (vertical jump height-VJH) strength. To put these effects into context, they were compared with the effects of jump squat power training (JS-known to improve 1RM and VJH). Twenty-one healthy men (age = 18-27 years, body mass = 72.58 ± 12.87 kg) who could perform a proficient HS were tested for their HS 1RM and VJH pre- and post-training. Subjects were randomly assigned to either a KB or JS training group after HS 1RM testing and trained twice a week. The KB group performed 12-minute bouts of KB exercise (12 rounds of 30-second exercise, 30-second rest with 12 kg if 70 kg). The JS group performed at least 4 sets of 3 JS with the load that maximized peak power-Training volume was altered to accommodate different training loads and ranged from 4 sets of 3 with the heaviest load (60% 1RM) to 8 sets of 6 with the lightest load (0% 1RM). Maximum strength improved by 9.8% (HS 1RM: 165-181% body mass, p < 0.001) after the training intervention, and post hoc analysis revealed that there was no significant difference between the effect of KB and JS training (p = 0.56). Explosive strength improved by 19.8% (VJH: 20.6-24.3 cm) after the training intervention, and post hoc analysis revealed that the type of training did not significantly affect this either (p = 0.38). The results of this study clearly demonstrate that 6 weeks of biweekly KB training provides a stimulus that is sufficient to increase both maximum and explosive strength offering a useful alternative to strength and conditioning professionals seeking variety for their athletes.

Experimental and simulated strength of spot welds

DEFF Research Database (Denmark)

Nielsen, Chris Valentin; Bennedbæk, Rune A.K.; Larsen, Morten B.

2014-01-01

Weld strength testing of single spots in DP600 steel is presented for the three typical testing procedures, i.e. tensile-shear, cross-tension and peel testing. Spot welds are performed at two sets of welding parameters and strength testing under these conditions is presented by load......-elongation curves revealing the maximum load and the elongation at break. Welding and strength testing is simulated by SORPAS® 3D, which allows the two processes to be prepared in a combined simulation, such that the simulated welding properties are naturally applied to the simulation of strength testing. Besides...... the size and shape of the weld nugget, these properties include the new strength of the material in the weld and the heat affected zone based on the predicted hardness resulting from microstructural phase changes simulated during cooling of the weld before strength testing. Comparisons between overall...

MAXIMUM NUMBER OF REPETITIONS, TOTAL WEIGHT LIFTED AND NEUROMUSCULAR FATIGUE IN INDIVIDUALS WITH DIFFERENT TRAINING BACKGROUNDS

Directory of Open Access Journals (Sweden)

Valeria Panissa

2013-04-01

Full Text Available The aim of this study was to evaluate the performance, as well as neuromuscular activity, in a strength task in subjects with different training backgrounds. Participants (n = 26 were divided into three groups according to their training backgrounds (aerobic, strength or mixed and submitted to three sessions: (1 determination of the maximum oxygen uptake during the incremental treadmill test to exhaustion and familiarization of the evaluation of maximum strength (1RM for the half squat; (2 1RM determination; and (3 strength exercise, four sets at 80�0of the 1RM, in which the maximum number of repetitions (MNR, the total weight lifted (TWL, the root mean square (RMS and median frequency (MF of the electromyographic (EMG activity for the second and last repetition were computed. There was an effect of group for MNR, with the aerobic group performing a higher MNR compared to the strength group (P = 0.045, and an effect on MF with a higher value in the second repetition than in the last repetition (P = 0.016. These results demonstrated that individuals with better aerobic fitness were more fatigue resistant than strength trained individuals. The absence of differences in EMG signals indicates that individuals with different training backgrounds have a similar pattern of motor unit recruitment during a resistance exercise performed until failure, and that the greater capacity to perform the MNR probably can be explained by peripheral adaptations.

Greater Strength Gains after Training with Accentuated Eccentric than Traditional Isoinertial Loads in Already Strength-Trained Men

Science.gov (United States)

Walker, Simon; Blazevich, Anthony J.; Haff, G. Gregory; Tufano, James J.; Newton, Robert U.; Häkkinen, Keijo

2016-01-01

As training experience increases it becomes more challenging to induce further neuromuscular adaptation. Consequently, strength trainers seek alternative training methods in order to further increase strength and muscle mass. One method is to utilize accentuated eccentric loading, which applies a greater external load during the eccentric phase of the lift as compared to the concentric phase. Based upon this practice, the purpose of this study was to determine the effects of 10 weeks of accentuated eccentric loading vs. traditional isoinertial resistance training in strength-trained men. Young (22 ± 3 years, 177 ± 6 cm, 76 ± 10 kg, n = 28) strength-trained men (2.6 ± 2.2 years experience) were allocated to concentric-eccentric resistance training in the form of accentuated eccentric load (eccentric load = concentric load + 40%) or traditional resistance training, while the control group continued their normal unsupervised training program. Both intervention groups performed three sets of 6-RM (session 1) and three sets of 10-RM (session 2) bilateral leg press and unilateral knee extension exercises per week. Maximum force production was measured by unilateral isometric (110° knee angle) and isokinetic (concentric and eccentric 30°.s−1) knee extension tests, and work capacity was measured by a knee extension repetition-to-failure test. Muscle mass was assessed using panoramic ultrasonography and dual-energy x-ray absorptiometry. Surface electromyogram amplitude normalized to maximum M-wave and the twitch interpolation technique were used to examine maximal muscle activation. After training, maximum isometric torque increased significantly more in the accentuated eccentric load group than control (18 ± 10 vs. 1 ± 5%, p < 0.01), which was accompanied by an increase in voluntary activation (3.5 ± 5%, p < 0.05). Isokinetic eccentric torque increased significantly after accentuated eccentric load training only (10 ± 9%, p < 0.05), whereas concentric torque

Kinetic parameters, collision rates, energy exchanges and transport coefficients of non-thermal electrons in premixed flames at sub-breakdown electric field strengths

KAUST Repository

Bisetti, Fabrizio; El Morsli, Mbark

2014-01-01

The effects of an electric field on the collision rates, energy exchanges and transport properties of electrons in premixed flames are investigated via solutions to the Boltzmann kinetic equation. The case of high electric field strength, which

Controlling the transport of cations through permselective mesoporous alumina layers by manipulation of electric field and ionic strength

NARCIS (Netherlands)

Schmuhl, R.; Keizer, Klaas; van den Berg, Albert; ten Elshof, Johan E.; Blank, David H.A.

2004-01-01

The electric field-driven transport of ions through supported mesoporous γ-alumina membranes was investigated. The influence of ion concentration, ion valency, pH, ionic strength, and electrolyte composition on transport behavior was determined. The permselectivity of the membrane was found to be

Acute peripheral joint injury: cost and effectiveness of low-field-strength MR imaging--results of randomized controlled trial.

NARCIS (Netherlands)

Nikken, J.J.; Oei, E.H.; Ginai, A.Z.; Krestin, G.P.; Verhaar, J.A.N.; Vugt, A.B. van; Hunink, M.G.M.

2005-01-01

PURPOSE: To assess prospectively if a short imaging examination performed with low-field-strength dedicated magnetic resonance (MR) imaging in addition to radiography is effective and cost saving compared with the current diagnostic imaging strategy (radiography alone) in patients with recent acute

Enhanced electrical conductivity in graphene and boron nitride nanoribbons in large electric fields

Science.gov (United States)

Chegel, Raad

2018-02-01

Based on data of density function theory (DFT) as the input of tight binding model, the electrical conductivity (σ(T)) of graphene nanoribbos (GNRs) and Boron Nitride nanoribbos (BNNRs) under external electric fields with different wide are studied using the Green's function method. The BNNRs are wide band gap semiconductor and they are turned into metal depending on their electric field strength. The σ(T) shows increasing in low temperature region and after reaching the maximum value, it will decrease in high temperature region. In lower temperature ranges, the electrical conductivity of the GNRs is greater than that of the BNNRs. In a low temperature region, the σ(T) of GNRs increases linearly with temperature unlike the BNNRs. The electrical conductivity are strongly dependent on the electric field strength.

Influence of field strength, coil type and image resolution on assessment of synovitis by unenhanced MRI - a comparison with contrast-enhanced MRI

Energy Technology Data Exchange (ETDEWEB)

Eshed, Iris [The Sheba Medical Center, Department of Diagnostic Imaging, Tel Hashomer (Israel); Tel Aviv University, Sackler School of Medicine, Tel Aviv (Israel); Krabbe, Simon; Axelsen, Mette; Pedersen, Susanne Juhl [Copenhagen University Hospital Glostrup, Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen (Denmark); Oestergaard, Mikkel [Copenhagen University Hospital Glostrup, Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen (Denmark); Copenhagen University Hospital Gentofte, Department of Rheumatology/C, Copenhagen (Denmark); Boeyesen, Pernille [Diakonhjemmet Hospital, Department of Rheumatology, Oslo (Norway); Moeller, Jakob M. [Copenhagen University Hospital at Herlev, Department of Radiology, Copenhagen (Denmark); Therkildsen, Flemming [Metropolitan University College, Copenhagen (Denmark); Madsen, Ole Rintek [Copenhagen University Hospital Gentofte, Department of Rheumatology/C, Copenhagen (Denmark)

2015-04-01

To explore if the reliability of synovitis assessment by unenhanced MRI is influenced by different MRI field-strengths, coil types and image resolutions in RA patients. Forty-one RA patients and 12 healthy controls underwent hand MRI (wrist and 2{sup nd}-5{sup th} metacarpophalangeal joints) at 4 different field-strengths (0.23 T/0.6 T/1.5 T/3.0 T) on the same day. Seven protocols using a STIR sequence with different field-strengths, coils (flex coils/dedicated phased-array extremity coils) and resolution were applied and scored blindly for synovitis (OMERACT-RAMRIS method). A 1.5 T post-contrast T1-weighted sequence was used as gold standard reference. Fair-good agreement (ICC=0.38-0.72) between the standard reference and the different STIR protocols (best agreement with extremity coil and small voxel size at 1.5 T). The accuracy for presence/absence of synovitis was very high per person (0.80-1.0), and moderate-high per joint (0.63-0.85), whereas exact agreements on scores were moderate (0.50-0.66). The intrareader agreement (15 patients and 3 controls) on presence/absence of synovitis was very high (0.87-1.0). Unenhanced MRI using STIR sequence is only moderately reliable for assessing hand synovitis in RA, when contrast-enhanced MRI is considered the gold standard reference. Contrast injection, field strength and coil type influence synovitis assessment, and should be considered before performing MRI in clinical trials and practice. (orig.)

Effects of high frequency electromagnetic field emitted from digital cellular telephones on electronic pocket dosimeters

Energy Technology Data Exchange (ETDEWEB)

Shizuhiko, Deji; Kunihide, Nishizawa [Nagoya Univ., Nagoya (Japan)

2002-07-01

High frequency electromagnetic fields emitted from digital cellular telephones (cell phones) occasionally cause abnormally high values (wrong dosages) on electronic pocket dosimeters (EPD). Electric field strength distribution around the cell phone transmitting 1.5GHz band with a maximum power of 0.8 W was analyzed by using an isotropic probe with tri-axial dipole antennas. Five kinds of EPDs were exposed to the fields for 50s under four kinds of configurations relative to the cell phone. The electric field distribution expanded around the antenna and had a maximum strength level of 36.5 {+-} 0.30 V/m. The cell phone gave rise to a wrong dosage of four EPDs out of five. The electromagnetic susceptibility of the EPD was higher in the section where the semiconductor detector or electric circuit boards were implanted. The maximum value of wrong dosage was 1283{mu} Sv. The distance preventing electromagnetic interference differed in each EPD and ranged from 2.0cm to 21.0cm. The electromagnetic immunity levels of the EPDs were distributed from 9.2V/m to a value greater than 35V/m. The EPDs displayed wrong dosage during exposure, while they recovered their normal performance after the cell phone ceased transmitting. The electromagnetic immunity levels of the EPDs were either equal to or greater than the IEC-standard. The immunity levels should be enhanced greater than the IEC-standard from the standpoint of radiation protection.

Effects of high frequency electromagnetic field emitted from digital cellular telephones on electronic pocket dosimeters

International Nuclear Information System (INIS)

Shizuhiko, Deji; Kunihide, Nishizawa

2002-01-01

High frequency electromagnetic fields emitted from digital cellular telephones (cell phones) occasionally cause abnormally high values (wrong dosages) on electronic pocket dosimeters (EPD). Electric field strength distribution around the cell phone transmitting 1.5GHz band with a maximum power of 0.8 W was analyzed by using an isotropic probe with tri-axial dipole antennas. Five kinds of EPDs were exposed to the fields for 50s under four kinds of configurations relative to the cell phone. The electric field distribution expanded around the antenna and had a maximum strength level of 36.5 ± 0.30 V/m. The cell phone gave rise to a wrong dosage of four EPDs out of five. The electromagnetic susceptibility of the EPD was higher in the section where the semiconductor detector or electric circuit boards were implanted. The maximum value of wrong dosage was 1283μ Sv. The distance preventing electromagnetic interference differed in each EPD and ranged from 2.0cm to 21.0cm. The electromagnetic immunity levels of the EPDs were distributed from 9.2V/m to a value greater than 35V/m. The EPDs displayed wrong dosage during exposure, while they recovered their normal performance after the cell phone ceased transmitting. The electromagnetic immunity levels of the EPDs were either equal to or greater than the IEC-standard. The immunity levels should be enhanced greater than the IEC-standard from the standpoint of radiation protection

Magnetic field of Mercury

International Nuclear Information System (INIS)

Jackson, D.J.; Beard, D.B.

1977-01-01

The geomagnetic field, suitably scaled down and parameterized, is shown to give a very good fit to the magnetic field measurements taken on the first and third passes of the Mariner 10 space probe past Mercury. The excellence of the fit to a reliable planetary magnetospheric model is good evidence that the Mercury magnetosphere is formed by a simple, permanent, intrinsic planetary magnetic field distorted by the effects of the solar wind. The parameters used for a best fit to all the data are (depending slightly on the choice of data) 2.44--2.55 for the ratio of Mercury's magnetic field strength at the subsolar point to that of the earth's subsolar point field (this results in a dipole moment of 170 γR/sub M/ 3 (R/sub M/ is Mercury Radius), i.e., 2.41 x 10 22 G cm 3 in the same direction as the earth's dipole), approx.-113 γR/sub M/ 4 for the planetary quadrupole moment parallel to the dipole moment, 10degree--17degree for the tilt of the planet dipole toward the sun, 4.5degree for the tilt of the dipole toward dawn, and 2.5degree--7.6degree aberration angle for the shift in the tail axis from the planet-sun direction because of the planet's orbital velocity. The rms deviation overall for the entire data set compared with the theoretical fitted model for the magnetic field strength was 17 γ (approx.4% of the maximum field measured). If the data from the first pass that show presumed strong time variations are excluded, the overall rms deviation for the field magnitude is only 10 γ

Maximum entropy principle and hydrodynamic models in statistical mechanics

International Nuclear Information System (INIS)

Trovato, M.; Reggiani, L.

2012-01-01

This review presents the state of the art of the maximum entropy principle (MEP) in its classical and quantum (QMEP) formulation. Within the classical MEP we overview a general theory able to provide, in a dynamical context, the macroscopic relevant variables for carrier transport in the presence of electric fields of arbitrary strength. For the macroscopic variables the linearized maximum entropy approach is developed including full-band effects within a total energy scheme. Under spatially homogeneous conditions, we construct a closed set of hydrodynamic equations for the small-signal (dynamic) response of the macroscopic variables. The coupling between the driving field and the energy dissipation is analyzed quantitatively by using an arbitrary number of moments of the distribution function. Analogously, the theoretical approach is applied to many one-dimensional n + nn + submicron Si structures by using different band structure models, different doping profiles, different applied biases and is validated by comparing numerical calculations with ensemble Monte Carlo simulations and with available experimental data. Within the quantum MEP we introduce a quantum entropy functional of the reduced density matrix, the principle of quantum maximum entropy is then asserted as fundamental principle of quantum statistical mechanics. Accordingly, we have developed a comprehensive theoretical formalism to construct rigorously a closed quantum hydrodynamic transport within a Wigner function approach. The theory is formulated both in thermodynamic equilibrium and nonequilibrium conditions, and the quantum contributions are obtained by only assuming that the Lagrange multipliers can be expanded in powers of ħ 2 , being ħ the reduced Planck constant. In particular, by using an arbitrary number of moments, we prove that: i) on a macroscopic scale all nonlocal effects, compatible with the uncertainty principle, are imputable to high-order spatial derivatives both of the

Upper Extremity Muscle Volumes and Functional Strength After Resistance Training in Older Adults

Science.gov (United States)

Daly, Melissa; Vidt, Meghan E.; Eggebeen, Joel D.; Simpson, W. Greg; Miller, Michael E.; Marsh, Anthony P.; Saul, Katherine R.

2014-01-01

Aging leads to a decline in strength and an associated loss of independence. The authors examined changes in muscle volume, maximum isometric joint moment, functional strength, and 1-repetition maximum (1RM) after resistance training (RT) in the upper extremity of older adults. They evaluated isometric joint moment and muscle volume as predictors of functional strength. Sixteen healthy older adults (average age 75 ± 4.3 yr) were randomized to a 6-wk upper extremity RT program or control group. The RT group increased 1RM significantly (p strength (p = .003), isometric shoulder-adduction moment (p = .041), elbow-flexor volume (p = .017), and shoulder-adductor volume (p = .009). Shoulder-muscle volumes and isometric moments were good predictors of functional strength. The authors conclude that shoulder strength is an important factor for performing functional reaching and pulling tasks and a key target for upper extremity RT interventions. PMID:22952203

RIEGER-TYPE PERIODICITY DURING SOLAR CYCLES 14–24: ESTIMATION OF DYNAMO MAGNETIC FIELD STRENGTH IN THE SOLAR INTERIOR

Energy Technology Data Exchange (ETDEWEB)

Gurgenashvili, Eka; Zaqarashvili, Teimuraz V.; Kukhianidze, Vasil; Ramishvili, Giorgi; Shergelashvili, Bidzina [Abastumani Astrophysical Observatory at Ilia State University, Tbilisi, Georgia (United States); Oliver, Ramon; Ballester, Jose Luis [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain); Hanslmeier, Arnold [IGAM, Institute of Physics, University of Graz, Universitätsplatz 5, A-8010 Graz (Austria); Poedts, Stefaan, E-mail: teimuraz.zaqarashvili@uni-graz.at [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001, Leuven (Belgium)

2016-07-20

Solar activity undergoes a variation over timescales of several months known as Rieger-type periodicity, which usually occurs near maxima of sunspot cycles. An early analysis showed that the periodicity appears only in some cycles and is absent in other cycles. But the appearance/absence during different cycles has not been explained. We performed a wavelet analysis of sunspot data from the Greenwich Royal Observatory and the Royal Observatory of Belgium during cycles 14–24. We found that the Rieger-type periods occur in all cycles, but they are cycle dependent: shorter periods occur during stronger cycles. Our analysis revealed a periodicity of 185–195 days during the weak cycles 14–15 and 24 and a periodicity of 155–165 days during the stronger cycles 16–23. We derived the dispersion relation of the spherical harmonics of the magnetic Rossby waves in the presence of differential rotation and a toroidal magnetic field in the dynamo layer near the base of the convection zone. This showed that the harmonics of fast Rossby waves with m = 1 and n = 4, where m ( n ) indicates the toroidal (poloidal) wavenumbers, perfectly fit with the observed periodicity. The variation of the toroidal field strength from weaker to stronger cycles may lead to the different periods found in those cycles, which explains the observed enigmatic feature of the Rieger-type periodicity. Finally, we used the observed periodicity to estimate the dynamo field strength during cycles 14–24. Our estimations suggest a field strength of ∼40 kG for the stronger cycles and ∼20 kG for the weaker cycles.

Anisotropic toughness and strength in graphene and its atomistic origin

Science.gov (United States)

Hossain, M. Zubaer; Ahmed, Tousif; Silverman, Benjamin; Khawaja, M. Shehroz; Calderon, Justice; Rutten, Andrew; Tse, Stanley

2018-01-01

This paper presents the implication of crystallographic orientation on toughness and ideal strength in graphene under lattice symmetry-preserving and symmetry-breaking deformations. In symmetry-preserving deformation, both toughness and strength are isotropic, regardless of the chirality of the lattice; whereas, in symmetry-breaking deformation they are strongly anisotropic, even in the presence of vacancy defects. The maximum and minimum of toughness or strength occur for loading along the zigzag direction and the armchair direction, respectively. The anisotropic behavior is governed by a complex interplay among bond-stretching deformation, bond-bending deformation, and the chirality of the lattice. Nevertheless, the condition for crack-nucleation is dictated by the maximum bond-force required for bond rupture, and it is independent of the chiral angle of the lattice or loading direction. At the onset of crack-nucleation a localized nucleation zone is formed, wherein the bonds rupture locally satisfying the maximum bond-force criterion. The nucleation zone acts as the physical origin in triggering the fracture nucleation process, but its presence is undetectable from the macroscopic stress-strain data.

47 CFR 27.55 - Power strength limits.

Science.gov (United States)

2010-10-01

... following bands, the predicted or measured median field strength at any location on the geographical border... predicted or measured median field strength at any location on the geographical border of a licensee's... antenna mounting structure. (c) Power flux density limit for stations operating in the 746-757 MHz, 758...

Tensile strength/yield strength (TS/YS) ratios of high-strength steel (HSS) reinforcing bars

Science.gov (United States)

Tavio, Anggraini, Retno; Raka, I. Gede Putu; Agustiar

2018-05-01

The building codes such as American Concrete Institute (ACI) 318M-14 and Standard National Indonesia (SNI) 2847:2013 require that the ratio of tensile strength (TS) and yield strength (YS) should not less than 1.25. The requirement is based on the assumption that a capability of a structural member to develop inelastic rotation capacity is a function of the length of the yield region. This paper reports an investigation on various steel grades, namely Grades 420, 550, 650, and 700 MPa, to examine the impact of different TS/YS ratios if it is less or greater than the required value. Grades 550, 650, and 700 MPa were purposely selected with the intention to examine if these higher grades are still promising to be implemented in special structural systems since they are prohibited by the building codes for longitudinal reinforcement, whereas Grade 420 MPa bars are the maximum limit of yield strength of reinforcing bars that is allowable for longitudinal reinforcement of special structural systems. Tensile tests of these steel samples were conducted under displacement controlled mode to capture the complete stress-strain curves and particularly the post-yield response of the steel bars. From the study, it can be concluded that Grade 420 performed higher TS/YS ratios and they were able to reach up to more than 1.25. However, the High Strength Still (HSS) bars (Grades 550, 600, and 700 MPa) resulted in lower TS/YS ratios (less than 1.25) compared with those of Grade 420 MPa.

In situ electric fields causing electro-stimulation from conductor contact of charged human

International Nuclear Information System (INIS)

Nagai, T.; Hirata, A.

2010-01-01

Contact currents flow from/into a human body when touching an object such as a metal structure with a different electric potential. These currents can stimulate muscle and peripheral nerves. In this context, computational analyses of in situ electric fields caused by the contact current have been performed, while their effectiveness for transient contact currents has not well been investigated. In the present study, using an anatomically based human model, a dispersive finite-difference time-domain model was utilised to computed transient contact current and in situ electric fields from a charged human. Computed in situ electric fields were highly localised in the hand. In order to obtain an insight into the relationship between in situ electric field and electro-stimulation, cell-maximum and 5-mm averaged in situ electric fields were computed and compared with strength-duration curves. The comparison suggests that both measures could be larger than thresholds derived from the strength- duration curves with parameters used in previous studies. (authors)

Relationship between bone strength and dual-energy X-ray absorptiometry measurements in pigs

DEFF Research Database (Denmark)

Nielsen, Dorte Hald; McEvoy, Fintan; Madsen, M.T.

2007-01-01

BMD (1.4 g/cm2, respectively). The results showed a difference in the maximum load, in the stress at maximum load, and stiffness among each BMD group (P ... and extrinsic measures of bone strength and BMD was thus demonstrated. The projected change in each of the variables reported, for a 0.1 /cm2 alteration in BMD (within the BMD range evaluated in this study), is as follows: maximum load, 708 N; stress at maximum load, 50 N/mm2; stiffness, 391.6 N/mm; and elastic...... modulus, 108 N/mm2 (P relationship between BMD and bone strength and indicate that BMD screening can be used in fracture risk assessments in production pigs....

Minimum disturbance rewards with maximum possible classical correlations

Energy Technology Data Exchange (ETDEWEB)

Pande, Varad R., E-mail: varad_pande@yahoo.in [Department of Physics, Indian Institute of Science Education and Research Pune, 411008 (India); Shaji, Anil [School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram, 695016 (India)

2017-07-12

Weak measurements done on a subsystem of a bipartite system having both classical and nonClassical correlations between its components can potentially reveal information about the other subsystem with minimal disturbance to the overall state. We use weak quantum discord and the fidelity between the initial bipartite state and the state after measurement to construct a cost function that accounts for both the amount of information revealed about the other system as well as the disturbance to the overall state. We investigate the behaviour of the cost function for families of two qubit states and show that there is an optimal choice that can be made for the strength of the weak measurement. - Highlights: • Weak measurements done on one part of a bipartite system with controlled strength. • Weak quantum discord & fidelity used to quantify all correlations and disturbance. • Cost function to probe the tradeoff between extracted correlations and disturbance. • Optimal measurement strength for maximum extraction of classical correlations.

High-Tensile Strength Tape Versus High-Tensile Strength Suture: A Biomechanical Study.

Science.gov (United States)

Gnandt, Ryan J; Smith, Jennifer L; Nguyen-Ta, Kim; McDonald, Lucas; LeClere, Lance E

2016-02-01

To determine which suture design, high-tensile strength tape or high-tensile strength suture, performed better at securing human tissue across 4 selected suture techniques commonly used in tendinous repair, by comparing the total load at failure measured during a fixed-rate longitudinal single load to failure using a biomechanical testing machine. Matched sets of tendon specimens with bony attachments were dissected from 15 human cadaveric lower extremities in a manner allowing for direct comparison testing. With the use of selected techniques (simple Mason-Allen in the patellar tendon specimens, whip stitch in the quadriceps tendon specimens, and Krackow stitch in the Achilles tendon specimens), 1 sample of each set was sutured with a 2-mm braided, nonabsorbable, high-tensile strength tape and the other with a No. 2 braided, nonabsorbable, high-tensile strength suture. A total of 120 specimens were tested. Each model was loaded to failure at a fixed longitudinal traction rate of 100 mm/min. The maximum load and failure method were recorded. In the whip stitch and the Krackow-stitch models, the high-tensile strength tape had a significantly greater mean load at failure with a difference of 181 N (P = .001) and 94 N (P = .015) respectively. No significant difference was found in the Mason-Allen and simple stitch models. Pull-through remained the most common method of failure at an overall rate of 56.7% (suture = 55%; tape = 58.3%). In biomechanical testing during a single load to failure, high-tensile strength tape performs more favorably than high-tensile strength suture, with a greater mean load to failure, in both the whip- and Krackow-stitch models. Although suture pull-through remains the most common method of failure, high-tensile strength tape requires a significantly greater load to pull-through in a whip-stitch and Krakow-stitch model. The biomechanical data obtained in the current study indicates that high-tensile strength tape may provide better repair

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

Energy Technology Data Exchange (ETDEWEB)

Hoang-Do, Ngoc-Tram; Hoang, Van-Hung; Le, Van-Hoang [Department of Physics, Ho Chi Minh City University of Pedagogy, 280 An Duong Vuong Street, District 5, Ho Chi Minh City (Viet Nam)

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.

The spheromak as a prototype for ultra-high-field superconducting magnets

International Nuclear Information System (INIS)

Furth, H.P.; Jardin, S.C.

1987-08-01

In view of current progress in the development of superconductor materials, the ultimate high-field limit of superconducting magnets is likely to be set by mechanical stress problems. Maximum field strength should be attainable by means of approximately force-free magnet windings having favorable ''MHD'' stability properties (so that small winding errors will not grow). Since a low-beta finite-flux-hole spheromak configuration qualifies as a suitable prototype, the theoretical and experimental spheromak research effort of the past decade has served to create a substantial technical basis for the design of ultra-high-field superconducting coils. 11 refs

Condromalácia de patela: comparação entre os achados em aparelhos de RM de alto e baixo campo magnético Chondromalacia patellae: comparison of high-field strength versus low-field strength magnetic resonance imaging findings

Directory of Open Access Journals (Sweden)

Maxime Figueiredo de Oliveira Freire

2006-06-01

Full Text Available OBJETIVO: Comparar os aparelhos de ressonância magnética de baixo campo e de alto campo para estudo da cartilagem articular da patela. MATERIAIS E MÉTODOS: Foi realizado estudo usando as seqüências GRE 2D, GRE 3D, FSE T2 e STIR (baixo campo e TSE T2 SPIR. Cada seqüência foi analisada separadamente para o estudo da cartilagem, sem o conhecimento dos dados do paciente e do resultado das outras seqüências, sendo atribuído grau de lesão de 0 a 3 e descrita a sua localização. Os resultados de concordância e discordância foram analisados pelos testes de Kappa e McNemar. RESULTADOS: Na faceta medial houve baixas concordâncias e as discordâncias mostraram significativa superestimação. Na faceta lateral houve boas concordâncias e as discordâncias não foram significativas. No ápice houve boas concordâncias e as discordâncias mostraram significativa subestimação. CONCLUSÃO: A seqüência STIR teve a melhor concordância com a seqüência TSE T2 SPIR. Lesões de alto grau são mais bem caracterizadas pelas seqüências do aparelho de baixo campo. Áreas de aumento de sinal dificultam o estudo da cartilagem da faceta medial da patela no aparelho de baixo campo.OBJECTIVE: To compare the performance of low-field-strength and high-field-strength magnetic resonance imaging equipments for evaluation of the patella articular cartilage. MATERIALS AND METHODS: The study was developed using GRE 2D, GRE 3D, FSE T2, STIR sequences (low-field and TSE T2 SPIR sequence. Each sequence has been separately analyzed for evaluation of the cartilage without knowledge of other sequences results or any patients data; the lesion was assigned a grade from 0 to 3 and had its location defined. Agreement and disagreement results were analyzed by Kappa and McNemar tests. RESULTS: Medial facet has presented low agreement index and disagreements showed to be significantly overestimated. Lateral facet has presented a reasonable agreement index and disagreement

The Maximum Free Magnetic Energy Allowed in a Solar Active Region

Science.gov (United States)

Moore, Ronald L.; Falconer, David A.

2009-01-01

Two whole-active-region magnetic quantities that can be measured from a line-of-sight magnetogram are (sup L) WL(sub SG), a gauge of the total free energy in an active region's magnetic field, and sup L(sub theta), a measure of the active region's total magnetic flux. From these two quantities measured from 1865 SOHO/MDI magnetograms that tracked 44 sunspot active regions across the 0.5 R(sub Sun) central disk, together with each active region's observed production of CMEs, X flares, and M flares, Falconer et al (2009, ApJ, submitted) found that (1) active regions have a maximum attainable free magnetic energy that increases with the magnetic size (sup L) (sub theta) of the active region, (2) in (Log (sup L)WL(sub SG), Log(sup L) theta) space, CME/flare-productive active regions are concentrated in a straight-line main sequence along which the free magnetic energy is near its upper limit, and (3) X and M flares are restricted to large active regions. Here, from (a) these results, (b) the observation that even the greatest X flares produce at most only subtle changes in active region magnetograms, and (c) measurements from MSFC vector magnetograms and from MDI line-of-sight magnetograms showing that practically all sunspot active regions have nearly the same area-averaged magnetic field strength: =- theta/A approximately equal to 300 G, where theta is the active region's total photospheric flux of field stronger than 100 G and A is the area of that flux, we infer that (1) the maximum allowed ratio of an active region's free magnetic energy to its potential-field energy is 1, and (2) any one CME/flare eruption releases no more than a small fraction (less than 10%) of the active region's free magnetic energy. This work was funded by NASA's Heliophysics Division and NSF's Division of Atmospheric Sciences.

Strength properties of sandy soil-cement admixtures

OpenAIRE

Sara Rios; António Joaquim Pereira Viana Da Fonseca

2009-01-01

This paper will focus on the sensitivity of strength and stiffness properties of silty-sands, from granitic residual soil, which can be converted to a highly improved material if stabilized with cement. The study of soil stabilization with cement demands to quantify the influence of the cement percentage, porosity and water content adopted in the admixing process for different stresses and physical states. Firstly, this influence was quantified in terms of the unconfined strength and maximum ...

Fixed-head star tracker magnitude calibration on the solar maximum mission

Science.gov (United States)

Pitone, Daniel S.; Twambly, B. J.; Eudell, A. H.; Roberts, D. A.

1990-01-01

The sensitivity of the fixed-head star trackers (FHSTs) on the Solar Maximum Mission (SMM) is defined as the accuracy of the electronic response to the magnitude of a star in the sensor field-of-view, which is measured as intensity in volts. To identify stars during attitude determination and control processes, a transformation equation is required to convert from star intensity in volts to units of magnitude and vice versa. To maintain high accuracy standards, this transformation is calibrated frequently. A sensitivity index is defined as the observed intensity in volts divided by the predicted intensity in volts; thus, the sensitivity index is a measure of the accuracy of the calibration. Using the sensitivity index, analysis is presented that compares the strengths and weaknesses of two possible transformation equations. The effect on the transformation equations of variables, such as position in the sensor field-of-view, star color, and star magnitude, is investigated. In addition, results are given that evaluate the aging process of each sensor. The results in this work can be used by future missions as an aid to employing data from star cameras as effectively as possible.

Lifetime and residual strength of materials

DEFF Research Database (Denmark)

Nielsen, Lauge Fuglsang

1997-01-01

of load amplitude, load average, fractional time under maximum load, and load frequency.The analysis includes prediction of residual strength (re-cycle strength) during the process of load cycling. It is concluded that number of cycles to failure is a very poor design criterion. It is demonstrated how...... the theory developed can be generalized also to consider non-harmonic load variations.Algorithms are presented for design purposes which may be suggested as qualified alternatives to the Palmgren-Miner's methods normally used in fatigue analysis of materials under arbitrary load variations. Prediction...

Effect of a magnetic field on the fluorescence produced in irradiated anthracene solutions

International Nuclear Information System (INIS)

Dixon, R.S.; Sargent, F.P.; Lopata, V.J.; Gardy, E.M.; Brocklehurst, B.

1977-01-01

The effect of an applied magnetic field on the fluorescence from radiolytic ion recombination has been studied for anthracene in some hydrocarbon solvents. In pulse-irradiated anthracene in squalane, the fluorescence intensity following the pulse increases as a function of applied magnetic field in the range studied. At a constant magnetic field strength, the field-induced enhancement of the fluorescence intensity varies with time after the pulse. At high field strengths the enhancement reaches a maximum about 50 ns after the pulse. Similar effects are observed in cyclohexane but the enhancement is smaller than that in squalane. In benzene solutions the effect is extremely small. These findings are confirmed by observations in continuously gamma-irradiated solutions. 9,10-Dimethylanthracene gives a larger enhancement and anthracene-d 10 a smaller enhancement than the parent anthracene at high fields. The results are in general agreement with recent theoretical predictions based on the effect of a magnetic field on the loss of spin correlation of geminate ions pairs prior to recombination

Effects of electric and magnetic fields on the electronic properties of zigzag carbon and boron nitride nanotubes

Science.gov (United States)

Chegel, Raad; Behzad, Somayeh; Ahmadi, Eghbal

2012-04-01

We have investigated the electronic properties of zigzag CNTs and BNNTs under the external transverse electric field and axial magnetic field, using tight binding approximation. It was found that after switching on the electric and magnetic fields, the band modification such as distortion of the degeneracy, change in energy dispersion, subband spacing and band gap size reduction occurs. The band gap of zigzag BNNTs decreases linearly with increasing the electric field strength but the band gap variation for CNTs increases first and later decreases (Metallic) or first hold constant and then decreases (semiconductor). For type (II) CNTs, at a weak magnetic field, by increasing the electric field strength, the band gap remains constant first and then decreases and in a stronger magnetic field the band gap reduction becomes parabolic. For type (III) CNTs, in any magnetic field, the band gap increases slowly until reaches a maximum value and then decreases linearly. Unlike to CNTs, the magnetic field has less effects on the BNNTs band gap variation.

Field strength and dose dependence of contrast enhancement by gadolinium-based MR contrast agents

International Nuclear Information System (INIS)

Rinck, P.A.; Muller, R.N.

1999-01-01

The relaxivities r 1 and r 2 of magnetic resonance contrast agents and the T 1 relaxation time values of tissues are strongly field dependent. We present quantitative data and simulations of different gadolinium-based extracellular fluid contrast agents and the modulation of their contrast enhancement by the magnetic field to be able to answer the following questions: How are the dose and field dependences of their contrast enhancement? Is there an interrelationship between dose and field dependence? Should one increase or decrease doses at specific fields? Nuclear magnetic relaxation dispersion data were acquired for the following contrast agents: gadopentetate dimeglumine, gadoterate meglumine, gadodiamide injection, and gadoteridol injection, as well as for several normal and pathological human tissue samples. The magnetic field range stretched from 0.0002 to 4.7 T, including the entire clinical imaging range. The data acquired were then fitted with the appropriate theoretical models. The combination of the diamagnetic relaxation rates (R 1 = 1/T 1 and R 2 = 1/T 2 ) of tissues with the respective paramagnetic contributions of the contrast agents allowed the prediction of image contrast at any magnetic field. The results revealed a nearly identical field and dose-dependent increase of contrast enhancement induced by these contrast agents within a certain dose range. The target tissue concentration (TTC) was an important though nonlinear factor for enhancement. The currently recommended dose of 0.1 mmol/kg body weight seems to be a compromise close to the lower limits of diagnostically sufficient contrast enhancement for clinical imaging at all field strengths. At low field contrast enhancement might be insufficient. Adjustment of dose or concentration, or a new class of contrast agents with optimized relaxivity, would be a valuable contribution to a better diagnostic yield of contrast enhancement at all fields. (orig.)

Strength Analysis of Coconut Fiber Stabilized Earth for Farm Structures

Science.gov (United States)

Enokela, O. S.; P. O, Alada

2012-07-01

Investigation of the strength characteristic of soil from alluvial deposit of River Benue in makurdi stabilized with coconut fiber as a stabilizer was carried as local building material for farm structure. Processed coconut fibers were mixed with the soil at four different mix ratios of 1% fiber, 2% fiber, 3% fiber and 4% fiber by percentage weight with 0% fiber as control. Compaction test and compressive strength were carried out on the various stabilizing ratio. From the compaction test, the correlation between the maximum dry density and optimum moisture content is a second order polynomial with a coefficient of 63% obtained at1.91kg/m3and 20.0% respectively while the compressive strength test shows an optimum failure load of 8.62N/mm2 at 2%fibre:100% soil mix ratio at 2.16 maximum dry density.

Tensile rock mass strength estimated using InSAR

KAUST Repository

Jonsson, Sigurjon

2012-11-01

The large-scale strength of rock is known to be lower than the strength determined from small-scale samples in the laboratory. However, it is not well known how strength scales with sample size. I estimate kilometer-scale tensional rock mass strength by measuring offsets across new tensional fractures (joints), formed above a shallow magmatic dike intrusion in western Arabia in 2009. I use satellite radar observations to derive 3D ground displacements and by quantifying the extension accommodated by the joints and the maximum extension that did not result in a fracture, I put bounds on the joint initiation threshold of the surface rocks. The results indicate that the kilometer-scale tensile strength of the granitic rock mass is 1–3 MPa, almost an order of magnitude lower than typical laboratory values.

Tensile rock mass strength estimated using InSAR

KAUST Repository

Jonsson, Sigurjon

2012-01-01

The large-scale strength of rock is known to be lower than the strength determined from small-scale samples in the laboratory. However, it is not well known how strength scales with sample size. I estimate kilometer-scale tensional rock mass strength by measuring offsets across new tensional fractures (joints), formed above a shallow magmatic dike intrusion in western Arabia in 2009. I use satellite radar observations to derive 3D ground displacements and by quantifying the extension accommodated by the joints and the maximum extension that did not result in a fracture, I put bounds on the joint initiation threshold of the surface rocks. The results indicate that the kilometer-scale tensile strength of the granitic rock mass is 1–3 MPa, almost an order of magnitude lower than typical laboratory values.

Combining Experiments and Simulations Using the Maximum Entropy Principle

DEFF Research Database (Denmark)

Boomsma, Wouter; Ferkinghoff-Borg, Jesper; Lindorff-Larsen, Kresten

2014-01-01

are not in quantitative agreement with experimental data. The principle of maximum entropy is a general procedure for constructing probability distributions in the light of new data, making it a natural tool in cases when an initial model provides results that are at odds with experiments. The number of maximum entropy...... in the context of a simple example, after which we proceed with a real-world application in the field of molecular simulations, where the maximum entropy procedure has recently provided new insight. Given the limited accuracy of force fields, macromolecular simulations sometimes produce results....... Three very recent papers have explored this problem using the maximum entropy approach, providing both new theoretical and practical insights to the problem. We highlight each of these contributions in turn and conclude with a discussion on remaining challenges....

Design of exposure systems for ELF electric field bioeffects research

International Nuclear Information System (INIS)

Kaune, W.T.; Decker, J.R.; Phillips, R.D.; Gillis, M.F.

1978-01-01

Two systems for exposure and sham-exposure of large numbers of rats and mice to uniform, vertical, 60-Hz electric fields have been constructed. The rat system contains four racks of four rectangular 1.0m x 2.2m exposure-electrodes that are stacked vertically with a separation between adjacent electrodes of 0.41 m. Any two of the four exposure racks may be energized to a maximum field strength of 150 kV/m. Each exposure electrode is equipped with 24 Lexan cages, each of which holds a single rat. The cage floor is a stainless steel screen that serves as one electrode. The system for watering animals is contained entirely within the electrode and does not protrude above the cage's floor, thereby preventing distortion of the exposure field and electrical shock or discharge as the animal drinks. The total capacity of the system is 288 rats. A similar system of two racks of five electrodes each is used to expose as many as 450 mice to fields at a maximum strength of 150 kV/m while sham exposing an equal number. Measurements of the electric field reveal an overall uniformity within 4% over the area to be occupied by experimental animals. The field inside a Lexan cage is reduced by about 3%. No corona-discharge has been detected. Measurements of ozone concentration in the rat and mouse exposure systems show no difference from background levels. Harmonic distortion has been eliminated by damping and filtering the high-voltage supply. Animals housed in close proximity are partially shielded from the electric field; the total body current in a rat model is reduced by 35 ± 5% when rats are placed in adjacent cages. (author)

Reliability of one-repetition maximum performance in people with chronic heart failure.

Science.gov (United States)

Ellis, Rachel; Holland, Anne E; Dodd, Karen; Shields, Nora

2018-02-24

Evaluate intra-rater and inter-rater reliability of the one-repetition maximum strength test in people with chronic heart failure. Intra-rater and inter-rater reliability study. A public tertiary hospital in northern metropolitan Melbourne. Twenty-four participants (nine female, mean age 71.8 ± 13.1 years) with mild to moderate heart failure of any aetiology. Lower limb strength was assessed by determining the maximum weight that could be lifted using a leg press. Intra-rater reliability was tested by one assessor on two separate occasions . Inter-rater reliability was tested by two assessors in random order. Intra-class correlation coefficients and 95% confidence intervals were calculated. Bland and Altman analyses were also conducted, including calculation of mean differences between measures ([Formula: see text]) and limits of agreement . Ten intra-rater and 21 inter-rater assessments were completed. Excellent intra-rater (intra-class correlation coefficient 2,1 0.96) and inter-rater (intra-class correlation coefficient 2,1 0.93) reliability was found. Intra-rater assessment showed less variability (mean difference 4.5 kg, limits of agreement -8.11 to 17.11 kg) than inter-rater agreement (mean difference -3.81 kg, limits of agreement -23.39 to 15.77 kg). One-repetition maximum determined using a leg press is a reliable measure in people with heart failure. Given its smaller limits of agreement, intra-rater testing is recommended. Implications for Rehabilitation Using a leg press to determine a one-repetition maximum we were able to demonstrate excellent inter-rater and intra-rater reliability using an intra-class correlation coefficient. The Bland and Altman levels of agreement were wide for inter-rater reliability and so we recommend using one assessor if measuring change in strength within an individual over time.

Observations of the longitudinal magnetic field in the transition region and photosphere of a sunspot

Science.gov (United States)

Henze, W., Jr.; Tandberg-Hanssen, E.; Hagyard, M. J.; West, E. A.; Woodgate, B. E.; Shine, R. A.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; West, E. A.

1982-01-01

The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacraft has observed for the first time the longitudinal component of the magnetic field by means of the Zeeman effect in the transition region above a sunspot. The data presented here were obtained on three days in one sunspot, have spatial resolutions of 10 arcsec and 3 arcsec, and yield maximum field strengths greater than 1000 G above the umbrae in the spot. The method of analysis, including a line-width calibration feature used during some of the observations, is described in some detail in an appendix; the line width is required for the determination of the longitudinal magnetic field from the observed circular polarization. The transition region data for one day are compared with photospheric magnetograms from the Marshall Space Flight Center. Vertical gradients of the magnetic field are compared from the two sets of data; the maximum gradients of 0.41 to 0.62 G/km occur above the umbra and agree with or are smaller than values observed previously in the photosphere and low chromosphere.

Psychological correlates of performance in female athletes during a 12-week off-season strength and conditioning program.

Science.gov (United States)

Jones, Margaret T; Matthews, Tracey D; Murray, Mimi; Van Raalte, Judy; Jensen, Barbara E

2010-03-01

Examination of the relationship between performance testing and psychological measures before and after a 12-week strength and conditioning program was the study's purpose. Female NCAA Division-III soccer (n = 28), field hockey (n = 28), and softball (n = 19) athletes completed pre- and post-testing held 12 weeks apart. On day 1, athletes completed informed consent, 3 psychological measures (Profile of Mood States [POMS], Physical Self Perception Profile [PSPP], and Athlete's Self Perception of Physical Abilities [ASPPA]), and 2 strength tests (1 repetition maximum [1RM] bench, 1RM back squat). Day 2 consisted of the 30-yd sprint, pro agility run (PRO), vertical jump (VJ), and standing long jump (SLJ). All sports improved (p psychological measures. Specifically, Physical Strength was correlated with 1RM upper-body (r = 0.49, p Sport Competence correlated with ASPPA ratings of power (r = 0.45, p benefits of strength and conditioning. Furthermore, these results demonstrate how physical changes are related to athletes' physical self-perceptions and self-assessment of ability within their teams.

Kinetic parameters, collision rates, energy exchanges and transport coefficients of non-thermal electrons in premixed flames at sub-breakdown electric field strengths

KAUST Repository

Bisetti, Fabrizio

2014-01-02

The effects of an electric field on the collision rates, energy exchanges and transport properties of electrons in premixed flames are investigated via solutions to the Boltzmann kinetic equation. The case of high electric field strength, which results in high-energy, non-thermal electrons, is analysed in detail at sub-breakdown conditions. The rates of inelastic collisions and the energy exchange between electrons and neutrals in the reaction zone of the flame are characterised quantitatively. The analysis includes attachment, ionisation, impact dissociation, and vibrational and electronic excitation processes. Our results suggest that Townsend breakdown occurs for E/N = 140 Td. Vibrational excitation is the dominant process up to breakdown, despite important rates of electronic excitation of CO, CO2 and N2 as well as impact dissociation of O2 being apparent from 50 Td onwards. Ohmic heating in the reaction zone is found to be negligible (less than 2% of peak heat release rate) up to breakdown field strengths for realistic electron densities equal to 1010 cm-3. The observed trends are largely independent of equivalence ratio. In the non-thermal regime, electron transport coefficients are insensitive to mixture composition and approximately constant across the flame, but are highly dependent on the electric field strength. In the thermal limit, kinetic parameters and transport coefficients vary substantially across the flame due to the spatially inhomogeneous concentration of water vapour. A practical approach for identifying the plasma regime (thermal versus non-thermal) in studies of electric field effects on flames is proposed. © 2014 Taylor & Francis.

A Stochastic Maximum Principle for a Stochastic Differential Game of a Mean-Field Type

Energy Technology Data Exchange (ETDEWEB)

Hosking, John Joseph Absalom, E-mail: j.j.a.hosking@cma.uio.no [University of Oslo, Centre of Mathematics for Applications (CMA) (Norway)

2012-12-15

We construct a stochastic maximum principle (SMP) which provides necessary conditions for the existence of Nash equilibria in a certain form of N-agent stochastic differential game (SDG) of a mean-field type. The information structure considered for the SDG is of a possible asymmetric and partial type. To prove our SMP we take an approach based on spike-variations and adjoint representation techniques, analogous to that of S. Peng (SIAM J. Control Optim. 28(4):966-979, 1990) in the optimal stochastic control context. In our proof we apply adjoint representation procedures at three points. The first-order adjoint processes are defined as solutions to certain mean-field backward stochastic differential equations, and second-order adjoint processes of a first type are defined as solutions to certain backward stochastic differential equations. Second-order adjoint processes of a second type are defined as solutions of certain backward stochastic equations of a type that we introduce in this paper, and which we term conditional mean-field backward stochastic differential equations. From the resulting representations, we show that the terms relating to these second-order adjoint processes of the second type are of an order such that they do not appear in our final SMP equations. A comparable situation exists in an article by R. Buckdahn, B. Djehiche, and J. Li (Appl. Math. Optim. 64(2):197-216, 2011) that constructs a SMP for a mean-field type optimal stochastic control problem; however, the approach we take of using these second-order adjoint processes of a second type to deal with the type of terms that we refer to as the second form of quadratic-type terms represents an alternative to a development, to our setting, of the approach used in their article for their analogous type of term.

A Stochastic Maximum Principle for a Stochastic Differential Game of a Mean-Field Type

International Nuclear Information System (INIS)

Hosking, John Joseph Absalom

2012-01-01

We construct a stochastic maximum principle (SMP) which provides necessary conditions for the existence of Nash equilibria in a certain form of N-agent stochastic differential game (SDG) of a mean-field type. The information structure considered for the SDG is of a possible asymmetric and partial type. To prove our SMP we take an approach based on spike-variations and adjoint representation techniques, analogous to that of S. Peng (SIAM J. Control Optim. 28(4):966–979, 1990) in the optimal stochastic control context. In our proof we apply adjoint representation procedures at three points. The first-order adjoint processes are defined as solutions to certain mean-field backward stochastic differential equations, and second-order adjoint processes of a first type are defined as solutions to certain backward stochastic differential equations. Second-order adjoint processes of a second type are defined as solutions of certain backward stochastic equations of a type that we introduce in this paper, and which we term conditional mean-field backward stochastic differential equations. From the resulting representations, we show that the terms relating to these second-order adjoint processes of the second type are of an order such that they do not appear in our final SMP equations. A comparable situation exists in an article by R. Buckdahn, B. Djehiche, and J. Li (Appl. Math. Optim. 64(2):197–216, 2011) that constructs a SMP for a mean-field type optimal stochastic control problem; however, the approach we take of using these second-order adjoint processes of a second type to deal with the type of terms that we refer to as the second form of quadratic-type terms represents an alternative to a development, to our setting, of the approach used in their article for their analogous type of term.

The application of strength and power related field tests in older adults : criteria, current status and a future perspective

NARCIS (Netherlands)

Regterschot, G. Ruben H.; Morat, Tobias; Folkersma, Marjanne; Zijlstra, Wiebren

2015-01-01

Leg muscle strength (LMS) and leg muscle power (LMP) are determinants of aspects of functional status and important parameters for measuring intervention effects in older adults. Field tests are often used for the evaluation of LMS and LMP in older persons. However, criteria important for the

Method to increase the transition temperature and for the critical magnetic field strength of the known intermetallic compounds of vanadium or niobium

International Nuclear Information System (INIS)

Winter, H.

1977-01-01

The invention deals with a method to raise the transition temperature and critical magnetic field strength of superconducting, intermetallic compounds of vanadium and niobium. For example, a niobium alloy with 4 wt.% Al in melted in vacuum electric arc and formed into a sheet of about 1 mm thick. Strips of this sheet are electrically heated up to 1,900 0 C for one hour in a high-vacuum oven. The strips are then annealed in evacuated quartz ampoules for 120 hours at 800 0 C. These strips have a transition temperature of 24 K and a critical magnetic field strength of 600 kg; the critical current density was 5 x 10 4 A/cm 2 . (HPOE) [de

Relationship between isometric shoulder strength and arms-only swimming power among male collegiate swimmers: study of valid clinical assessment methods.

Science.gov (United States)

Awatani, Takenori; Morikita, Ikuhiro; Mori, Seigo; Shinohara, Junji; Tatsumi, Yasutaka

2018-04-01

[Purpose] The purpose of the present study was to confirm the relationships between shoulder strength (extensor strength and internal rotator strength) of the abducted position and swimming power during arm-only swimming. [Subjects and Methods] Fourteen healthy male collegiate swimmers participated in the study. Main measures were shoulder strength (strength using torque that was calculated from the upper extremity length and the isometric force of the abducted position) and swimming power. [Results] Internal rotation torque of the dominant side in the abducted external rotated position (r=0.85) was significantly correlated with maximum swimming power. The rate of bilateral difference in extension torque in the maximum abducted position (r=-0.728) was significantly correlated with the swimming velocity-to-swimming power ratio. [Conclusion] The results of this study suggest that internal rotator strength measurement in the abducted external rotated position and extensor strength measurement in the maximum abducted position are valid assessment methods for swimmers.

Peel strength of LDPE/ethylene-1-butene copolymer film crosslinked by radiation

International Nuclear Information System (INIS)

Nho, Young Chang; Kim, Jeong Il; Kang, Phil Hyun

2003-01-01

In this study, ethylene-1-butene copolymer(EBP) was blended with LDPE to improve the mechanical properties as the packaging materials. After they were irradiated by an electron beam, their physical properties such as tensile strength, elongation, modulus, peel strength, DSC, and DMA were examined. The results showed that the addition of EBP to LDPE exerted significant effects on the mechanical properties such as the tensile strength and peel strength. The addition of EBP led to a maximum increase in peel strength of ∼ 430%. The addition of 10-25w% EBP in LDPE was sufficient to enhance the peel strength significantly

Isometric and isokinetic muscle strength in patients with fibrositis syndrome. New characteristics for a difficult definable category of patients

DEFF Research Database (Denmark)

Jacobsen, Søren; Danneskiold-Samsøe, B

1987-01-01

A common complaint among patients with fibrositis syndrome is exhaustion and fatique. It was therefore felt desirable to evaluate the muscle strength of these patients compared with normal subjects. Maximum isometric and isokinetic strength of knee extension was measured in 15 patients and 15...... healthy matched subjects, using an isokinetic dynamometer (Cybex II). Maximum isometric strength at various knee extension angles (90 degrees, 60 degrees and 30 degrees degrees) was significantly (p less than 0.001) lower in the fibrositis group than in controls, a reduction of approximately 58......-66%. Maximum isokinetic strength at various knee extension velocities (30-240 degrees per second) was also significantly (p less than 0.01) lower in the fibrositis group than in controls, the reduction being approximately 41-51%. In conclusion, isometric and isokinetic muscle strength is found to be lower...

Influence of synthetic calcium silicates on the strength properties of fine-grained concrete

Science.gov (United States)

Yarusova, S. B.; Gordienko, P. S.; Kozin, A. V.; Zhevtun, I. G.; Perfilev, A. V.

2018-04-01

The effect of additives based on acicular calcium hydrosilicates (xonotlite and tobermorite) and wollastonite, obtained from boric acid production waste in autoclave synthesis at a temperature of 220 °C, on the strength of fine-grained concrete, has been studied in this paper. It was shown that when the calcium hydrosilicates and wollastonite are introduced, an increase in the strength characteristics of concrete is observed. After heat and moisture treatment, the maximum increase in strength is observed with the addition of 4% of mass content of calcium hydrosilicates and 6% of mass content of wollastonite. After 28 days of hardening under normal conditions, the maximum increase in strength of concrete is observed with the addition of 4% of mass content of both types of additives. It was shown that the water absorption of concrete decreases with a maximum when 4% of mass content is added, as in the case of the introduction of calcium hydrosilicates, and wollastonite. With a further increase in the number of additives, the amount of water absorption increases, but these values remain below the values for the control sample without additives.

Performance of an Adjustable Strength Permanent Magnet Quadrupole

CERN Document Server

Gottschalk, Stephen C; Kangas, Kenneth; Spencer, Cherrill M; Volk, James T

2005-01-01

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 centerline and field quality made using an air bearing rotating coil system. The magnetic centerline 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 centerline. Calibration procedures as well as centerline 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.

Undrained shear strength determination and correlations on Søvind Marl

DEFF Research Database (Denmark)

Grønbech, Gitte Lyng; Nielsen, Benjaminn Nordahl

2016-01-01

on both the preconsolidation and the undrained shear strength. Two apparent values of the preconsolidation stresses can be determined due to the fissured structure (Grønbech et al. 2015) which also considerably decreases the undrained shear strength. Determination of shear strength of fissured clay...... is done through field testing or triaxial testing. Christensen and Hansen (1959) tested fissured Danish Oligocene clay and found the undrained shear strength, Su, be approximately 1/3 of the measured field vane shear strength, cfv. This correlation has since been used in Danish geotechnical practice...

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

Science.gov (United States)

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

Controlled Aloin Release from Crosslinked Polyacrylamide Hydrogels: Effects of Mesh Size, Electric Field Strength and a Conductive Polymer

Directory of Open Access Journals (Sweden)

Anuvat Sirivat

2013-10-01

Full Text Available The aim of this paper is to investigate the effects of hydrogel mesh size, a conductive polymer, and electric field strength on controlled drug delivery phenomena using drug-loaded polyacrylamide hydrogels prepared at various crosslinking ratios both with and without a conductive polymer system. Poly(p-phenylene vinylene, PPV, as the model conductive polymer, was used to study its ability to control aloin released from aloin-doped poly(p-phenylene vinylene/polyacrylamide hydrogel (aloin-doped PPV/PAAM. In the passive release, the diffusion of aloin from five aloin-doped PPV/PAAM hydrogel systems each was delayed ranging from during the first three hours to during the first 14 h due to the ionic interaction between the anionic drug and PPV. After the delayed periods, aloin could diffuse continuously into the buffer solution through the PAAM matrix. The amount of aloin released from the aloin-doped PPV/PAAM rose with increasing electric field strength as a result of the three mechanisms: the expansion of PPV chains inside the hydrogel, iontophoresis, and the electroporation of the matrix pore size, combined. Furthermore, the conductive polymer and the electric field could be used in combination to regulate the amount of release drug to a desired level, to control the release rate, and to switch the drug delivery on/off.

Strength testing and training of rowers: a review.

Science.gov (United States)

Lawton, Trent W; Cronin, John B; McGuigan, Michael R

2011-05-01

In the quest to maximize average propulsive stroke impulses over 2000-m racing, testing and training of various strength parameters have been incorporated into the physical conditioning plans of rowers. Thus, the purpose of this review was 2-fold: to identify strength tests that were reliable and valid correlates (predictors) of rowing performance; and, to establish the benefits gained when strength training was integrated into the physical preparation plans of rowers. The reliability of maximal strength and power tests involving leg extension (e.g. leg pressing) and arm pulling (e.g. prone bench pull) was high (intra-class correlations 0.82-0.99), revealing that elite rowers were significantly stronger than their less competitive peers. The greater strength of elite rowers was in part attributed to the correlation between strength and greater lean body mass (r = 0.57-0.63). Dynamic lower body strength tests that determined the maximal external load for a one-repetition maximum (1RM) leg press (kg), isokinetic leg extension peak force (N) or leg press peak power (W) proved to be moderately to strongly associated with 2000-m ergometer times (r = -0.54 to -0.68; p training experience and muscle morphology, in that those individuals with greater training experience and/or proportions of slow twitch fibres performed more repetitions. Muscle balance ratios derived from strength data (e.g. hamstring-quadriceps ratio training may be counterproductive to strength development over the shorter term (i.e. training within the sequence of training units should be considered, particularly over the non-competition phase (e.g. 2-6 sets × 4-12 repetitions, three sessions a week). Maximal strength was sustained when infrequent (e.g. one or two sessions a week) but intense (e.g. 73-79% of maximum) strength training units were scheduled; however, it was unclear whether training adaptations should emphasize maximal strength, endurance or power in order to enhance

Fracture strength testing of crowns made of CAD/CAM composite resins.

Science.gov (United States)

Okada, Ryota; Asakura, Masaki; Ando, Akihiro; Kumano, Hirokazu; Ban, Seiji; Kawai, Tatsushi; Takebe, Jun

2018-03-28

The purpose of this study was to ascertain whether computer aided design/computer aided manufacturing (CAD/CAM) composite resin crowns have sufficient strength to withstand the bite force of the molar teeth. The null hypothesis was that the fracture strength of CAD/CAM composite resin crowns is lower than the average maximum bite force of the molar tooth. The crowns, which shape is the right maxillary first molar, were fabricated using four CAD/CAM blanks made of composite resins (Block HC: HC, KZR-CAD HR: HR, KZR-CAD HR2: HR2, Avencia Block: AVE) and one CAD/CAM blank made of lithium disilicate glass-ceramic (IPS e.max CAD: IPS), which was used as a control. Fracture strength of fabricated crowns bonded to metal abutment and biaxial flexural strength of the materials were evaluated. The results of fracture strength test and biaxial flexural strength test showed different tendencies. The fracture strength of CAD/CAM composite resin crowns except HC ranged from 3.3kN to 3.9kN, and was similar to that of IPS (3.3kN). In contrast, biaxial flexural strength of CAD/CAM composite resins ranged from 175MPa to 247MPa, and was significantly lower than that of IPS (360MPa). All CAD/CAM composite resin crowns studied presented about 3-4 times higher fracture strength than the average maximum bite force of the molar tooth (700-900N), which result leads to the conclusion that CAD/CAM composite resin crowns would have sufficient strength to withstand the bite force of the molar teeth. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Quantifying the Strength of General Factors in Psychopathology: A Comparison of CFA with Maximum Likelihood Estimation, BSEM, and ESEM/EFA Bifactor Approaches.

Science.gov (United States)

Murray, Aja Louise; Booth, Tom; Eisner, Manuel; Obsuth, Ingrid; Ribeaud, Denis

2018-05-22

Whether or not importance should be placed on an all-encompassing general factor of psychopathology (or p factor) in classifying, researching, diagnosing, and treating psychiatric disorders depends (among other issues) on the extent to which comorbidity is symptom-general rather than staying largely within the confines of narrower transdiagnostic factors such as internalizing and externalizing. In this study, we compared three methods of estimating p factor strength. We compared omega hierarchical and explained common variance calculated from confirmatory factor analysis (CFA) bifactor models with maximum likelihood (ML) estimation, from exploratory structural equation modeling/exploratory factor analysis models with a bifactor rotation, and from Bayesian structural equation modeling (BSEM) bifactor models. Our simulation results suggested that BSEM with small variance priors on secondary loadings might be the preferred option. However, CFA with ML also performed well provided secondary loadings were modeled. We provide two empirical examples of applying the three methodologies using a normative sample of youth (z-proso, n = 1,286) and a university counseling sample (n = 359).

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Determination of electric field strength and kinetic temperature in the cathode fall region of a hollow cathode discharge

Energy Technology Data Exchange (ETDEWEB)

De la Rosa, M I; Perez, C; Gruetzmacher, K [Universidad de Valladolid, Facultad de Ciencias, 47071 Valladolid (Spain); Gonzalo, A B; Del Val, J A, E-mail: delarosa@opt.uva.e [Universidad de Salamanca, Escuela Politecnica Superior, 05003 Avila (Spain)

2010-05-01

In this work, we demonstrate the high potential of two-photon excitation of the 1S -2S transition of atomic hydrogen followed by optogalvanic detection, for measuring under identical experimental conditions, the kinetic temperature and the electric field strength in the cathode sheath region of a hollow cathode discharge. The first obtained results for both parameters are discussed in this paper.

MRI of the knee: how do field strength and radiologist's experience influence diagnostic accuracy and interobserver correlation in assessing chondral and meniscal lesions and the integrity of the anterior cruciate ligament?

International Nuclear Information System (INIS)

Krampla, W.; Roesel, M.; Svoboda, K.; Nachbagauer, A.; Gschwantler, M.; Hruby, W.

2009-01-01

Accuracy of MRI reports is taken for granted. In this paper the inter-observer reliability in the interpretation of meniscal lesions, degree of chondropathy, and integrity of the ACL was analyzed while taking the radiologist's experience and field strength into account. Fifty-two MRI studies of knees were interpreted by 11 radiologists independently. Twenty-two were acquired on 1.0-T, 20 on 1.5-T, and 10 on 3.0-T systems. Four of the radiologists had more than 5 years and seven had 3 to 5 years of experience in interpreting MRI studies. The findings were compared with the intra-operative findings. Inter-observer variance, specificity, and sensitivity were evaluated for each field strength. Inter-observer correlation ranged between 0.370 for cartilage lesions and 0.597 for meniscal tears. Correlation values did not increase with experience or field strength. The number of false reports was dependent on the observer, but not on field strength. The rate of false interpretations was significantly higher for most criteria in the less experienced group. In conclusion, inter-observer correlation was low, although the diagnostic criteria were defined. The use of the classification scheme should be standardized by uniform training. Radiologist experience seems to be more important than field strength. (orig.)

Residential exposure to radiofrequency fields from mobile phone base stations, and broadcast transmitters: a population-based survey with personal meter.

Science.gov (United States)

Viel, J F; Clerc, S; Barrera, C; Rymzhanova, R; Moissonnier, M; Hours, M; Cardis, E

2009-08-01

Both the public perceptions, and most published epidemiologic studies, rely on the assumption that the distance of a particular residence from a base station or a broadcast transmitter is an appropriate surrogate for exposure to radiofrequency fields, although complex propagation characteristics affect the beams from antennas. The main goal of this study was to characterise the distribution of residential exposure from antennas using personal exposure meters. A total of 200 randomly selected people were enrolled. Each participant was supplied with a personal exposure meter for 24 h measurements, and kept a time-location-activity diary. Two exposure metrics for each radiofrequency were then calculated: the proportion of measurements above the detection limit (0.05 V/m), and the maximum electric field strength. Residential address was geocoded, and distance from each antenna was calculated. Much of the time, the recorded field strength was below the detection level (0.05 V/m), the FM band standing apart with a proportion above the detection threshold of 12.3%. The maximum electric field strength was always lower than 1.5 V/m. Exposure to GSM and DCS waves peaked around 280 m and 1000 m from the antennas. A downward trend was found within a 10 km range for FM. Conversely, UMTS, TV 3, and TV 4&5 signals did not vary with distance. Despite numerous limiting factors entailing a high variability in radiofrequency exposure assessment, but owing to a sound statistical technique, we found that exposures from GSM and DCS base stations increase with distance in the near source zone, to a maximum where the main beam intersects the ground. We believe these results will contribute to the ongoing public debate over the location of base stations and their associated emissions.

Effects of high frequency electromagnetic fields emitted from digital cellular telephones on electronic pocket dosimeters

International Nuclear Information System (INIS)

Deji, Shizuhiko; Nishizawa, Kunihide

2003-01-01

Electric field strength distribution around the digital cellular telephone (cell phone) transmitting 1.5GHz band was analyzed by using an isotropic probe. Five types of electronic pocket dosimeters (EPDs) were exposed to the fields for 50sec under four kinds of configurations relative to the cell phone. The field distribution expanded around the antenna and had a maximum strength level of 36.5±0.3V/m. The cell phone caused abnormally high values (wrong dosages) to four EPDs out of five due to electromagnetic interference. Three out of the four EPDs exceeded the upper limits of dose range depending on the configurations, and the maximum value of wrong dosage among the EPDs was 1,283 μSv. The minimum distance preventing electromagnetic interference (protection distance) differed with each EPD and ranged from 2.0cm to 21.0cm. The electromagnetic immunity levels of EPD-1, 2, 3, 4 and 5 were 13.3, ≥35, ≥32, 9.2 and ≥35 V/m, respectively. Although the immunity levels were either equal to or greater than the IEC-standard level, those of the EPDs should be enhanced greater than the IEC-standard from the standpoint of radiation protection. (author)

A brief review of strength and ballistic assessment methodologies in sport.

Science.gov (United States)

McMaster, Daniel Travis; Gill, Nicholas; Cronin, John; McGuigan, Michael

2014-05-01

An athletic profile should encompass the physiological, biomechanical, anthropometric and performance measures pertinent to the athlete's sport and discipline. The measurement systems and procedures used to create these profiles are constantly evolving and becoming more precise and practical. This is a review of strength and ballistic assessment methodologies used in sport, a critique of current maximum strength [one-repetition maximum (1RM) and isometric strength] and ballistic performance (bench throw and jump capabilities) assessments for the purpose of informing practitioners and evolving current assessment methodologies. The reliability of the various maximum strength and ballistic assessment methodologies were reported in the form of intra-class correlation coefficients (ICC) and coefficient of variation (%CV). Mean percent differences (Mdiff = [/Xmethod1 - Xmethod2/ / (Xmethod1 + Xmethod2)] x 100) and effect size (ES = [Xmethod2 - Xmethod1] ÷ SDmethod1) calculations were used to assess the magnitude and spread of methodological differences for a given performance measure of the included studies. Studies were grouped and compared according to their respective performance measure and movement pattern. The various measurement systems (e.g., force plates, position transducers, accelerometers, jump mats, optical motion sensors and jump-and-reach apparatuses) and assessment procedures (i.e., warm-up strategies, loading schemes and rest periods) currently used to assess maximum isometric squat and mid-thigh pull strength (ICC > 0.95; CV 0.91; CV ballistic (vertical jump and bench throw) capabilities (ICC > 0.82; CV ballistic performance in recreational and elite athletes, alike. However, the reader needs to be cognisant of the inherent differences between measurement systems, as selection will inevitably affect the outcome measure. The strength and conditioning practitioner should also carefully consider the benefits and limitations of the different measurement

Influence of the Rashba and Dresselhaus spin-orbit interactions of equal strength on the electron states in the circular quantum dot in the presence of a magnetic field

International Nuclear Information System (INIS)

Kudryashov, V.V.; Baran, A.V.

2012-01-01

The solutions of the Schrodinger equation are obtained for an electron at a two-dimensional circular semiconductor quantum dot in the presence of both an external magnetic field and the Rashba and Dresselhaus spin-orbit interactions of equal strength. Confinement is simulated by a realistic potential well of finite depth. The dependence of energy levels on a magnetic field and a strength of spin-orbit interaction is presented. (authors)

Proton and multinuclear magnetic resonance spectroscopy in the human brain at ultra-high field strength: A review.

Science.gov (United States)

Henning, Anke

2018-03-01

Magnetic Resonance Spectroscopy (MRS) allows for a non-invasive and non-ionizing determination of in vivo tissue concentrations and metabolic turn-over rates of more than 20 metabolites and compounds in the central nervous system of humans. The aim of this review is to give a comprehensive overview about the advantages, challenges and advances of ultra-high field MRS with regard to methodological development, discoveries and applications from its beginnings around 15 years ago up to the current state. The review is limited to human brain and spinal cord application at field strength of 7T and 9.4T and includes all relevant nuclei ( 1 H, 31 P, 13 C). Copyright © 2017 Elsevier Inc. All rights reserved.

On the Fluctuating Component of the Sun's Large-Scale Magnetic Field

Science.gov (United States)

Wang, Y.-M.; Sheeley, N. R., Jr.

2003-06-01

The Sun's large-scale magnetic field and its proxies are known to undergo substantial variations on timescales much less than a solar cycle but longer than a rotation period. Examples of such variations include the double activity maximum inferred by Gnevyshev, the large peaks in the interplanetary field strength observed in 1982 and 1991, and the 1.3-1.4 yr periodicities detected over limited time intervals in solar wind speed and geomagnetic activity. We consider the question of the extent to which these variations are stochastic in nature. For this purpose, we simulate the evolution of the Sun's equatorial dipole strength and total open flux under the assumption that the active region sources (BMRs) are distributed randomly in longitude. The results are then interpreted with the help of a simple random walk model including dissipation. We find that the equatorial dipole and open flux generally exhibit multiple peaks during each 11 yr cycle, with the highest peak as likely to occur during the declining phase as at sunspot maximum. The widths of the peaks are determined by the timescale τ~1 yr for the equatorial dipole to decay through the combined action of meridional flow, differential rotation, and supergranular diffusion. The amplitudes of the fluctuations depend on the strengths and longitudinal phase relations of the BMRs, as well as on the relative rates of flux emergence and decay. We conclude that stochastic processes provide a viable explanation for the ``Gnevyshev gaps'' and for the existence of quasi periodicities in the range ~1-3 yr.

Effects of low frequency electromagnetic field on the as-cast microstructures and mechanical properties of superhigh strength aluminum alloy

International Nuclear Information System (INIS)

Zuo Yubo; Cui Jianzhong; Dong Jie; Yu Fuxiao

2005-01-01

A new superhigh strength Al-Zn-Mg-Cu alloy was made by low frequency electromagnetic casting (LFEC) and conventional direct chill (DC) casting, respectively. The effects of low frequency electromagnetic field on the as-cast microstructures and mechanical properties were investigated. The results show that under the low frequency electromagnetic field (25 Hz, 32 mT), the microstructures of LFEC ingot from the border to the center on the cross section are all fine equiaxed or nearly equiaxed grains. The grains are much finer and more uniform than that of DC ingot. It was found that magnetic flux density plays an important role on the microstructure formation of LFEC ingots. With increasing the magnetic flux density, grains become finer and more uniform. In the range of experimental parameters, the optimum magnetic flux density for LFEC process is found to be 32 mT. The mechanical tests show that for this new superhigh strength Al-Zn-Mg-Cu alloy, the as-cast mechanical properties of LFEC ingot are much higher than that of DC ingot

The efficacy of magnetic field on the thermal behavior of MnFe{sub 2}O{sub 4} nanofluid as a functional fluid through an open-cell metal foam tube

Energy Technology Data Exchange (ETDEWEB)

Amani, Mohammad [Mechanical and Energy Engineering Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Ameri, Mohammad, E-mail: ameri_m@yahoo.com [Mechanical and Energy Engineering Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Kasaeian, Alibakhsh [Department of Renewable Energies Engineering, Faculty of New Sciences & Technologies, University of Tehran, Tehran (Iran, Islamic Republic of)

2017-06-15

Highlights: • Experiments are performed with MnFe{sub 2}O{sub 4} nanofluid through an open-cell metal foam tube. • Effects of concentration, Reynolds number and magnetic field on the nanofluid thermal behavior are examined. • Heat transfer is enhanced in attendance of constant and alternating magnetic fields. - Abstract: In the present experimental study, the influence of permanent and alternating magnetic fields on the flow and thermal behavior of MnFe{sub 2}O{sub 4} magnetic nanofluid flowing through a circular open-cell metal foam tube is investigated under homogeneous heat flux conditions. The experiments are performed at various nanoparticle concentrations, Reynolds numbers and magnetic fields with different strengths and frequencies. According to the observations, the heat transfer rate enhances directly relative to nanoparticle concentration and Reynolds number in attendance of magnetic field, whereas its maximum value of 16.4% is found for 2 wt% nanoparticles at Re = 200 under alternating field with 400 G strength and 20 Hz frequency. Moreover, it is observed that the influence of strength and frequency of magnetic field is insignificant for the pressure drop. Hydrothermal efficiency as the ratio of the Nusselt number to the ratio of the pressure drop is defined in order to evaluate the privilege of using MnFe{sub 2}O{sub 4} nanofluids in practical applications. The maximum efficiency of 1.25 is observed at 2 wt% under magnetic field with 400 G and 20 Hz at Re = 1000.

Effect of the ionic strength of pulsed electric field treatment medium on the physicochemical and structural characteristics of lactoferrin.

Science.gov (United States)

Sui, Qian; Roginski, Hubert; Williams, Roderick P W; Wooster, Tim J; Versteeg, Cornelis; Wan, Jason

2010-11-24

Pulsed electric field (PEF) treatment (35 kV cm(-1) for 19.2 μs using bipolar 2 μs pulses) was conducted on bovine lactoferrin (LF; 0.4 mg mL(-1)) prepared in simulated milk ultrafiltrate (SMUF), at concentrations between 0.2× and 2× normal strength, with electrical conductivities ranging from 0.17 to 1.04 S m(-1). The physicochemical and structural characteristics (LF content by a spectrophotometric and an ELISA method, surface hydrophobicity, electrophoretic mobility, far-UV circular dichroism spectra, and tryptophan fluorescence) of LF dissolved in SMUF of all strengths tested were not changed after PEF treatment. The PEF treatment of LF in 0.2 strength SMUF did not cause the release of LF-bound ferric ion into the aqueous phase, with a concentration of LF-bound iron being the same as that of the untreated LF control (174 μg L(-1)). However, in treatment media with higher ionic strengths, ferric ion was released from the LF molecule into the aqueous phase. The concentration of LF-bound iron decreased from 174 μg L(-1) for the LF treated in 0.2 strength SMUF to 80 μg L(-1) for that treated in double-strength SMUF. The results suggest that the PEF-induced iron depletion of LF does not appear to cause an appreciable conformational change in LF molecules. PEF treatment could be developed as a novel physical way to produce iron-depleted LF, as an alternative to the existing chemical method.

Measurements of intermediate-frequency electric and magnetic fields in households

Energy Technology Data Exchange (ETDEWEB)

Aerts, Sam, E-mail: sam.aerts@intec.ugent.be [Department of Information Technology, Ghent University/iMinds, iGent, Technologiepark-Zwijnaarde 15, B-9052 Ghent (Belgium); Calderon, Carolina [Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, Oxon OX11 0RQ (United Kingdom); Valič, Blaž [Institute of Non-Ionizing Radiation (INIS), Pohorskega bataljona 215, Ljubljana 1000 (Slovenia); Maslanyj, Myron; Addison, Darren; Mee, Terry; Goiceanu, Cristian [Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, Oxon OX11 0RQ (United Kingdom); Verloock, Leen; Van den Bossche, Matthias [Department of Information Technology, Ghent University/iMinds, iGent, Technologiepark-Zwijnaarde 15, B-9052 Ghent (Belgium); Gajšek, Peter [Institute of Non-Ionizing Radiation (INIS), Pohorskega bataljona 215, Ljubljana 1000 (Slovenia); Vermeulen, Roel [Institute for Risk Assessment Sciences, Department of Environmental Epidemiology, Utrecht University, Yalelaan 2, 3508 Utrecht (Netherlands); Röösli, Martin [Swiss Tropical and Public Health Institute (Swiss TPH), Socinstrasse 57, P.O. Box, 4002 Basel (Switzerland); University of Basel, Petersplatz 1, 4003 Basel (Switzerland); Cardis, Elisabeth [Barcelona Institute for Global Health (ISGlobal) and Municipal Institute of Medical Research (IMIM-Hospital del Mar), Doctor Aiguader, 88, 08003 Barcelona (Spain); Martens, Luc; Joseph, Wout [Department of Information Technology, Ghent University/iMinds, iGent, Technologiepark-Zwijnaarde 15, B-9052 Ghent (Belgium)

2017-04-15

Historically, assessment of human exposure to electric and magnetic fields has focused on the extremely-low-frequency (ELF) and radiofrequency (RF) ranges. However, research on the typically emitted fields in the intermediate-frequency (IF) range (300 Hz to 1 MHz) as well as potential effects of IF fields on the human body remains limited, although the range of household appliances with electrical components working in the IF range has grown significantly (e.g., induction cookers and compact fluorescent lighting). In this study, an extensive measurement survey was performed on the levels of electric and magnetic fields in the IF range typically present in residences as well as emitted by a wide range of household appliances under real-life circumstances. Using spot measurements, residential IF field levels were found to be generally low, while the use of certain appliances at close distance (20 cm) may result in a relatively high exposure. Overall, appliance emissions contained either harmonic signals, with fundamental frequencies between 6 kHz and 300 kHz, which were sometimes accompanied by regions in the IF spectrum of rather noisy, elevated field strengths, or much more capricious spectra, dominated by 50 Hz harmonics emanating far in the IF domain. The maximum peak field strengths recorded at 20 cm were 41.5 V/m and 2.7 A/m, both from induction cookers. Finally, none of the appliance emissions in the IF range exceeded the exposure summation rules recommended by the International Commission on Non-Ionizing Radiation Protection guidelines and the International Electrotechnical Commission (IEC 62233) standard at 20 cm and beyond (maximum exposure quotients EQ{sub E} 1.0 and {sub E}Q{sub H} 0.13). - Highlights: • Survey of residential electric and magnetic fields at intermediate frequencies (IF). • IF-EF and -MF emitted by 280 household appliances were characterised. • Strongest emitters were induction cookers, CFLs, LCD-TVs, and microwave ovens. • No

Measurements of intermediate-frequency electric and magnetic fields in households

International Nuclear Information System (INIS)

Aerts, Sam; Calderon, Carolina; Valič, Blaž; Maslanyj, Myron; Addison, Darren; Mee, Terry; Goiceanu, Cristian; Verloock, Leen; Van den Bossche, Matthias; Gajšek, Peter; Vermeulen, Roel; Röösli, Martin; Cardis, Elisabeth; Martens, Luc; Joseph, Wout

2017-01-01

Historically, assessment of human exposure to electric and magnetic fields has focused on the extremely-low-frequency (ELF) and radiofrequency (RF) ranges. However, research on the typically emitted fields in the intermediate-frequency (IF) range (300 Hz to 1 MHz) as well as potential effects of IF fields on the human body remains limited, although the range of household appliances with electrical components working in the IF range has grown significantly (e.g., induction cookers and compact fluorescent lighting). In this study, an extensive measurement survey was performed on the levels of electric and magnetic fields in the IF range typically present in residences as well as emitted by a wide range of household appliances under real-life circumstances. Using spot measurements, residential IF field levels were found to be generally low, while the use of certain appliances at close distance (20 cm) may result in a relatively high exposure. Overall, appliance emissions contained either harmonic signals, with fundamental frequencies between 6 kHz and 300 kHz, which were sometimes accompanied by regions in the IF spectrum of rather noisy, elevated field strengths, or much more capricious spectra, dominated by 50 Hz harmonics emanating far in the IF domain. The maximum peak field strengths recorded at 20 cm were 41.5 V/m and 2.7 A/m, both from induction cookers. Finally, none of the appliance emissions in the IF range exceeded the exposure summation rules recommended by the International Commission on Non-Ionizing Radiation Protection guidelines and the International Electrotechnical Commission (IEC 62233) standard at 20 cm and beyond (maximum exposure quotients EQ E 1.0 and E Q H 0.13). - Highlights: • Survey of residential electric and magnetic fields at intermediate frequencies (IF). • IF-EF and -MF emitted by 280 household appliances were characterised. • Strongest emitters were induction cookers, CFLs, LCD-TVs, and microwave ovens. • No emissions exceeded

Strength development of high-strength ductile concrete incorporating Metakaolin and PVA fibers.

Science.gov (United States)

Nuruddin, Muhammad Fadhil; Khan, Sadaqat Ullah; Shafiq, Nasir; Ayub, Tehmina

2014-01-01

The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

The intra-observer reproducibility of cardiovascular magnetic resonance myocardial feature tracking strain assessment is independent of field strength

International Nuclear Information System (INIS)

Schuster, Andreas; Morton, Geraint; Hussain, Shazia T.

2013-01-01

Background: Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a promising novel method for quantification of myocardial wall mechanics from standard steady-state free precession (SSFP) images. We sought to determine whether magnetic field strength affects the intra-observer reproducibility of CMR-FT strain analysis. Methods: We studied 2 groups, each consisting of 10 healthy subjects, at 1.5 T or 3 T Analysis was performed at baseline and after 4 weeks using dedicated CMR-FT prototype software (Tomtec, Germany) to analyze standard SSFP cine images. Right ventricular (RV) and left ventricular (LV) longitudinal strain (Ell RV and Ell LV ) and LV long-axis radial strain (Err LAX ) were derived from the 4-chamber cine, and LV short-axis circumferential and radial strains (Ecc SAX , Err SAX ) from the short-axis orientation. Strain parameters were assessed together with LV ejection fraction (EF) and volumes. Intra-observer reproducibility was determined by comparing the first and the second analysis in both groups. Results: In all volunteers resting strain parameters were successfully derived from the SSFP images. There was no difference in strain parameters, volumes and EF between field strengths (p > 0.05). In general Ecc SAX was the most reproducible strain parameter as determined by the coefficient of variation (CV) at 1.5 T (CV 13.3% and 46% global and segmental respectively) and 3 T (CV 17.2% and 31.1% global and segmental respectively). The least reproducible parameter was Ell RV (CV 1.5 T 28.7% and 53.2%; 3 T 43.5% and 63.3% global and segmental respectively). Conclusions: CMR-FT results are similar with reasonable intra-observer reproducibility in different groups of volunteers at 1.5 T and 3 T. CMR-FT is a promising novel technique and our data indicate that results might be transferable between field strengths. However there is a considerable amount of segmental variability indicating that further refinements are needed before CMR

Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers

OpenAIRE

Richard Billich; Jakub Štvrtňa; Karel Jelen

2015-01-01

Optimal Velocity to Achieve Maximum Power Output – Bench Press for Trained Footballers In today’s world of strength training there are many myths surrounding effective exercising with the least possible negative effect on one’s health. In this experiment we focus on the finding of a relationship between maximum output, used load and the velocity with which the exercise is performed. The main objective is to find the optimal speed of the exercise motion which would allow us to reach the ma...

Effect of magnetic field strength on NMR-based metabonomic human urine data. Comparative study of 250, 400, 500, and 800 MHz

DEFF Research Database (Denmark)

Bertram, Hanne Christine; Malmendal, Anders; Petersen, Bent O.

2007-01-01

Metabonomic analysis of urine utilizing high-resolution NMR spectroscopy and chemometric techniques has proven valuable in characterizing the biochemical response to an intervention. To assess the effect of magnetic field strength on information contained in NMR-based metabonomic data sets, 1H NMR...

The photospheric vector magnetic field of a sunspot and its vertical gradient

Science.gov (United States)

Hagyard, M. J.; West, E. A.; Tandberg-Hanssen, E.; Smith, J. E.; Henze, W., Jr.; Beckers, J. M.; Bruner, E. C.; Hyder, C. L.; Gurman, J. B.; Shine, R. A.

1981-01-01

The results of direct comparisons of photospheric and transition region line-of-sight field observations of sunspots using the SMM UV spectrometer and polarimeter are reported. The analysis accompanying the data is concentrated on demonstrating that the sunspot concentrated magnetic field extends into the transition region. An observation of a sunspot on Oct. 23, 1980 at the S 18 E 03 location is used as an example. Maximum field strengths ranged from 2030-2240 gauss for large and small umbrae viewed and inclination of the field to the line-of-sight was determined for the photosphere and transition region. The distribution of the magnetic field over the sunspot and variation of the line-of-sight gradient are discussed, as are the magnitudes and gradients of the photospheric field across the penumbral-photospheric boundaries.

Maximum power point tracking

International Nuclear Information System (INIS)

Enslin, J.H.R.

1990-01-01

A well engineered renewable remote energy system, utilizing the principal of Maximum Power Point Tracking can be m ore cost effective, has a higher reliability and can improve the quality of life in remote areas. This paper reports that a high-efficient power electronic converter, for converting the output voltage of a solar panel, or wind generator, to the required DC battery bus voltage has been realized. The converter is controlled to track the maximum power point of the input source under varying input and output parameters. Maximum power point tracking for relative small systems is achieved by maximization of the output current in a battery charging regulator, using an optimized hill-climbing, inexpensive microprocessor based algorithm. Through practical field measurements it is shown that a minimum input source saving of 15% on 3-5 kWh/day systems can easily be achieved. A total cost saving of at least 10-15% on the capital cost of these systems are achievable for relative small rating Remote Area Power Supply systems. The advantages at larger temperature variations and larger power rated systems are much higher. Other advantages include optimal sizing and system monitor and control

Testing the assumption in ergonomics software that overall shoulder strength can be accurately calculated by treating orthopedic axes as independent.

Science.gov (United States)

Hodder, Joanne N; La Delfa, Nicholas J; Potvin, Jim R

2016-08-01

To predict shoulder strength, most current ergonomics software assume independence of the strengths about each of the orthopedic axes. Using this independent axis approach (IAA), the shoulder can be predicted to have strengths as high as the resultant of the maximum moment about any two or three axes. We propose that shoulder strength is not independent between axes, and propose an approach that calculates the weighted average (WAA) between the strengths of the axes involved in the demand. Fifteen female participants performed maximum isometric shoulder exertions with their right arm placed in a rigid adjustable brace affixed to a tri-axial load cell. Maximum exertions were performed in 24 directions, including four primary directions, horizontal flexion-extension, abduction-adduction, and at 15° increments in between those axes. Moments were computed and comparisons made between the experimentally collected strengths and those predicted by the IAA and WAA methods. The IAA over-predicted strength in 14 of 20 non-primary exertions directions, while the WAA underpredicted strength in only 2 of these directions. Therefore, it is not valid to assume that shoulder axes are independent when predicting shoulder strengths between two orthopedic axes, and the WAA is an improvement over current methods for the posture tested. Copyright © 2015 Elsevier Ltd. All rights reserved.

Einstein-Dirac theory in spin maximum I

International Nuclear Information System (INIS)

Crumeyrolle, A.

1975-01-01

An unitary Einstein-Dirac theory, first in spin maximum 1, is constructed. An original feature of this article is that it is written without any tetrapod technics; basic notions and existence conditions for spinor structures on pseudo-Riemannian fibre bundles are only used. A coupling gravitation-electromagnetic field is pointed out, in the geometric setting of the tangent bundle over space-time. Generalized Maxwell equations for inductive media in presence of gravitational field are obtained. Enlarged Einstein-Schroedinger theory, gives a particular case of this E.D. theory. E. S. theory is a truncated E.D. theory in spin maximum 1. A close relation between torsion-vector and Schroedinger's potential exists and nullity of torsion-vector has a spinor meaning. Finally the Petiau-Duffin-Kemmer theory is incorporated in this geometric setting [fr

Twenty-five years of maximum-entropy principle

Science.gov (United States)

Kapur, J. N.

1983-04-01

The strengths and weaknesses of the maximum entropy principle (MEP) are examined and some challenging problems that remain outstanding at the end of the first quarter century of the principle are discussed. The original formalism of the MEP is presented and its relationship to statistical mechanics is set forth. The use of MEP for characterizing statistical distributions, in statistical inference, nonlinear spectral analysis, transportation models, population density models, models for brand-switching in marketing and vote-switching in elections is discussed. Its application to finance, insurance, image reconstruction, pattern recognition, operations research and engineering, biology and medicine, and nonparametric density estimation is considered.

Particle roughness in magnetorheology: effect on the strength of the field-induced structures

International Nuclear Information System (INIS)

Vereda, F; Segovia-Gutiérrez, J P; De Vicente, J; Hidalgo-Alvarez, R

2015-01-01

We report a study on the effect of particle roughness on the strength of the field-induced structures of magnetorheological (MR) fluids in the quasi-static regime. We prepared one set of MR fluids with carbonyl iron particles and another set with magnetite particles, and in both sets we had particles with different degrees of surface roughness. Small amplitude oscillatory shear (SAOS) magnetosweeps and steady shear (SS) tests were carried out on the suspensions to measure their elastic modulus (G′) and static yield stress (τ static ). Results for both the iron and the magnetite sets of suspensions were consistent: for the MR fluids prepared with rougher particles, G′ increased at smaller fields and τ static was ca. 20% larger than for the suspensions prepared with relatively smooth particles. In addition to the experimental study, we carried out finite element method calculations to assess the effect of particle roughness on the magnetic interaction between particles. These calculations showed that roughness can facilitate the magnetization of the particles, thus increasing the magnetic energy of the system for a given field, but that this effect depends on the concrete morphology of the surface. For our real systems, no major differences were observed between the magnetization cycles of the MR fluids prepared with particles with different degree of roughness, which implied that the effect of roughness on the measured G′ and τ static was due mainly to friction between the solid surfaces of adjacent particles. (paper)

Multi-material topology design of laminates with strength criteria

DEFF Research Database (Denmark)

Lund, Erik

2012-01-01

The objective of this paper is to present a novel approach for multi-material topology optimization of laminated composite structures where strength constraints are taken into account together with other global structural performance measures. The topology design problem considered contains very...... many design variables, and when strength criteria are included in the problem, a very large number of criteria functions must be considered in the optimization problem to be solved. Thus, block aggregation methods are introduced, such that global strength measures are obtained. These formulations...... are illustrated for multi-material laminated design problems where the maximum failure index is minimized while compliance and mass constraints are taken into account....

Strength and Compaction Analysis of Sand-Bentonite-Coal Ash Mixes

Science.gov (United States)

Sobti, Jaskiran; Singh, Sanjay Kumar

2017-08-01

This paper deals with the strength and compaction characteristics of sand-bentonite-coal ash mixes prepared by varying percentages of sand, bentonite and coal ash to be used in cutoff walls and as a liner or cover material in landfills. The maximum dry density (MDD) and optimum moisture content (OMC) of sand-bentonite mixes and sand-bentonite-coal ash mixes were determined by conducting the standard proctor test. Also, the strength and stiffness characteristics of soil mixes were furnished using unconfined compressive strength test. The results of the study reveal influence of varying percentages of coal ash and bentonite on the compaction characteristics of the sand-bentonite-coal ash mixes. Also, validation of a statistical analysis of the correlations between maximum dry density (MDD), optimum moisture content (OMC) and Specific Gravity (G) was done using the experimental results. The experimental results obtained for sand-bentonite, sand-bentonite-ash and coal ash-bentonite mixes very well satisfied the statistical relations between MDD, OMC and G with a maximum error in the estimate of MDD being within ±1 kN/m3. The coefficient of determination (R2) ranged from 0.95 to 0.967 in case of sand-bentonite-ash mixes. However, for sand-bentonite mixes, the R2 values are low and varied from 0.48 to 0.56.

Statistical analysis of geomagnetic field variations during solar eclipses

Science.gov (United States)

Kim, Jung-Hee; Chang, Heon-Young

2018-04-01

We investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories, which are observed while the Moon's umbra or penumbra passed over them during a solar eclipse event. Though it is generally considered that the geomagnetic field can be modulated during solar eclipses, the effect of the solar eclipse on the observed geomagnetic field has proved subtle to be detected. Instead of exploring the geomagnetic field as a case study, we analyze 207 geomagnetic manifestations acquired by 100 geomagnetic observatories during 39 solar eclipses occurring from 1991 to 2016. As a result of examining a pattern of the geomagnetic field variation on average, we confirm that the effect can be seen over an interval of 180 min centered at the time of maximum eclipse on a site of a geomagnetic observatory. That is, demonstrate an increase in the Y component of the geomagnetic field and decreases in the X component and the total strength of the geomagnetic field. We also find that the effect can be overwhelmed, depending more sensitively on the level of daily geomagnetic events than on the level of solar activity and/or the phase of solar cycle. We have demonstrated it by dividing the whole data set into subsets based on parameters of the geomagnetic field, solar activity, and solar eclipses. It is suggested, therefore, that an evidence of the solar eclipse effect can be revealed even at the solar maximum, as long as the day of the solar eclipse is magnetically quiet.

In vitro/in silico investigation of failure criteria to predict flexural strength of composite resins.

Science.gov (United States)

Yamaguchi, Satoshi; Mehdawi, Idris Mohamed; Sakai, Takahiko; Abe, Tomohiro; Inoue, Sayuri; Imazato, Satoshi

2018-01-30

The aim of this study was to investigate a failure criterion to predict flexural strengths of composite resins (CR) by three-dimensional finite element analysis (3D-FEA). Models of flexural strength for test specimens of CR and rods comprising a three-point loading were designed. Calculation of Young's moduli and Poisson's ratios of CR were conducted using a modified McGee-McCullough model. Using the experimental CR, flexural strengths were measured by three-point bending tests with crosshead speed 1.0 mm/min and compared with the values determined by in silico analysis. The flexural strengths of experimental CR calculated using the maximum principal strain significantly correlated with those obtained in silico amongst the four types of failure criteria applied. The in silico analytical model established in this study was found to be effective to predict the flexural strengths of CR incorporating various silica filler contents by maximum principal strain.

4.5 Tesla magnetic field reduces range of high-energy positrons -- Potential implications for positron emission tomography

International Nuclear Information System (INIS)

Wirrwar, A.; Vosberg, H.; Herzog, H.; Halling, H.; Weber, S.; Mueller-Gaertner, H.W.; Forschungszentrum Juelich GmbH

1997-01-01

The authors have theoretically and experimentally investigated the extent to which homogeneous magnetic fields up to 7 Tesla reduce the spatial distance positrons travel before annihilation (positron range). Computer simulations of a noncoincident detector design using a Monte Carlo algorithm calculated the positron range as a function of positron energy and magnetic field strength. The simulation predicted improvements in resolution, defined as full-width at half-maximum (FWHM) of the line-spread function (LSF) for a magnetic field strength up to 7 Tesla: negligible for F-18, from 3.35 mm to 2.73 mm for Ga-68 and from 3.66 mm to 2.68 mm for Rb-82. Also a substantial noise suppression was observed, described by the full-width at tenth-maximum (FWTM) for higher positron energies. The experimental approach confirmed an improvement in resolution for Ga-68 from 3.54 mm at 0 Tesla to 2.99 mm FWHM at 4.5 Tesla and practically no improvement for F-18 (2.97 mm at 0 Tesla and 2.95 mm at 4.5 Tesla). It is concluded that the simulation model is appropriate and that a homogeneous static magnetic field of 4.5 Tesla reduces the range of high-energy positrons to an extent that may improve spatial resolution in positron emission tomography

Optimization Of Fluoride Glass Fiber Drawing With Respect To Mechanical Strength

Science.gov (United States)

Schneider, H. W.; Schoberth, A.; Staudt, A.; Gerndt, Ch.

1987-08-01

Heavy metal fluoride fibers have attracted considerable attention recently as lightguides for infrared optical devices. Besides the optical loss mechanical performance of the fiber is of major interest. At present fiber strength suffers from surface crystallization prior to or during fiber drawing. We developed an etching method for the preparation of preforms with clean surface. Drawing these preforms under optimized conditions in a dry atmosphere results in fibers with improved strength. So far, mean value of 400 N/mm2 tensile strength have been achieved. Maximum values of 800 N/mm2 measured on etched fibers indicate an even higher strength potential for the material itself.

Gauge field copies

International Nuclear Information System (INIS)

Bollini, C.G.; Giambiagi, J.J.; Tiomno, J.

1979-01-01

The construction of field strength copies without any gauge constraint is discussed. Several examples are given, one of which is not only a field strength copy but also (at the same time) a 'current copy'. (author) [pt

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

Science.gov (United States)

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

2016-02-27

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.

Detailing magnetic field strength dependence and segmental artifact distribution of myocardial effective transverse relaxation rate at 1.5, 3.0, and 7.0 T.

Science.gov (United States)

Meloni, Antonella; Hezel, Fabian; Positano, Vincenzo; Keilberg, Petra; Pepe, Alessia; Lombardi, Massimo; Niendorf, Thoralf

2014-06-01

Realizing the challenges and opportunities of effective transverse relaxation rate (R2 *) mapping at high and ultrahigh fields, this work examines magnetic field strength (B0 ) dependence and segmental artifact distribution of myocardial R2 * at 1.5, 3.0, and 7.0 T. Healthy subjects were considered. Three short-axis views of the left ventricle were examined. R2 * was calculated for 16 standard myocardial segments. Global and mid-septum R2 * were determined. For each segment, an artifactual factor was estimated as the deviation of segmental from global R2 * value. The global artifactual factor was significantly enlarged at 7.0 T versus 1.5 T (P = 0.010) but not versus 3.0 T. At 7.0 T, the most severe susceptibility artifacts were detected in the inferior lateral wall. The mid-septum showed minor artifactual factors at 7.0 T, similar to those at 1.5 and 3.0 T. Mean R2 * increased linearly with the field strength, with larger changes for global heart R2 * values. At 7.0 T, segmental heart R2 * analysis is challenging due to macroscopic susceptibility artifacts induced by the heart-lung interface and the posterior vein. Myocardial R2 * depends linearly on the magnetic field strength. The increased R2 * sensitivity at 7.0 T might offer means for susceptibility-weighted and oxygenation level-dependent MR imaging of the myocardium. Copyright © 2013 Wiley Periodicals, Inc.

The dependence of potential well formation on the magnetic field strength and electron injection current in a polywell device

International Nuclear Information System (INIS)

Cornish, S.; Gummersall, D.; Carr, M.; Khachan, J.

2014-01-01

A capacitive probe has been used to measure the plasma potential in a polywell device in order to observe the dependence of potential well formation on magnetic field strength, electron injection current, and polywell voltage bias. The effectiveness of the capacitive probe in a high energy electron plasma was determined by measuring the plasma potential of a planar diode with an axial magnetic field. The capacitive probe was translated along the axis of one of the field coils of the polywell, and the spatial profile of the potential well was measured. The confinement time of electrons in the polywell was estimated with a simple analytical model which used the experimentally observed potential well depths, as well as a simulation of the electron trajectories using particle orbit theory

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

International Nuclear Information System (INIS)

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

2013-01-01

The Feranchuk-Komarov operator method is developed by combining with the Levi-Civita transformation in order to construct analytical solutions of the Schrödinger 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.

Strength Development of High-Strength Ductile Concrete Incorporating Metakaolin and PVA Fibers

Directory of Open Access Journals (Sweden)

Muhammad Fadhil Nuruddin

2014-01-01

Full Text Available The mechanical properties of high-strength ductile concrete (HSDC have been investigated using Metakaolin (MK as the cement replacing material and PVA fibers. Total twenty-seven (27 mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

Variation in the WWV, 15 MHz field strength received at Hiraiso during a low solar activity and the application of the result to radio disturbance warning services

International Nuclear Information System (INIS)

Ohshio, Mitsuo; Kidokoro, Tsuneichi

1978-01-01

Recurrent geomagnetic storms occur predominantly apparently during the period of low solar activity. Radio disturbance warning services are apt to be made in terms of geomagnetic disturbances in this period. This analysis has been made from the standpoint of making the electric field strength of a short wave (WWV, 15 MHz) circuit with a long distance received at Hiraiso, Japan correspond to not only geomagnetic disturbances, but also its absorption in the ionosphere. The electric field strength has been treated as a newly introduced daily mean value of time-integrated one in this paper. The result has been obtained from the analysis that about 2/3 of the daily electric field strength of the total cases treated were influenced by geomagnetic disturbances and that about 2/3 within the remaining about 1/3 proved to be influenced by the ionospheric absorption, ionospheric parameters such as f sub(min) and the phase of a VLF radio wave circuit being used. The strength has been considered to be influenced by the absorption also in case of being influenced by geomagnetic disturbances. The remaining about 1/9 of the total cases could not correspond to its cause. Some applications of the consideration have been made to practical problems. (author)

Design study of the vertical field power supply for JT-60

International Nuclear Information System (INIS)

Yabuno, Kohei; Tani, Keiji; Shimada, Ryuichi; Kishimoto, Hiroshi; Yoshida, Hidetoshi

1977-09-01

The results of a basic design study of the vertical field power supply for JT-60 (JAERI large tokamak) are described. The objective of the study is to evaluate several types of power supply circuits for fast excitation and control of the vertical field. A design requirement is to produce a rapidly increasing vertical field within accuracy of +-5% around the proper field strength required to center the plasma in the vacuum vessel. The plasma current is assumed to increase at the rate of about 100 MA/sec. To meet the requirement, a maximum voltage of 15 kV is necessary in the current build-up time, while generally relatively low voltage is necessary after the current flattop is reached. A hybrid power supply which consists of a dc power source (a thyristor converter) and an inductive energy storage system is proposed. The maximum voltage of the dc power source is determined as 4 kV from the voltage required in the current flattop time. This is sufficient also in the current build-up time if the dc power source is used together with the inductive energy storage system. (auth.)

Reproducibility of MR-based liver fat quantification across field strength: Same-day comparison between 1.5T and 3T in obese subjects.

Science.gov (United States)

Artz, Nathan S; Haufe, William M; Hooker, Catherine A; Hamilton, Gavin; Wolfson, Tanya; Campos, Guilherme M; Gamst, Anthony C; Schwimmer, Jeffrey B; Sirlin, Claude B; Reeder, Scott B

2015-09-01

To examine the reproducibility of quantitative magnetic resonance (MR) methods to estimate hepatic proton density fat-fraction (PDFF) at different magnetic field strengths. This Health Insurance Portability and Accountability Act (HIPAA)-compliant study was approved by the Institutional Review Board. Following informed consent, 25 severely obese subjects (mean body mass index [BMI]: 45 ± 4, range: 38-53 kg/m(2) ) were scanned at 1.5T and 3T on the same day. Two confounder-corrected multiecho chemical shift-encoded gradient-echo-based imaging methods were acquired to estimate PDFF over the entire liver: 3D complex-based (MRI-C) and 2D magnitude-based (MRI-M) MRI. Single-voxel MR spectroscopy (MRS) was performed in the right liver lobe. Using linear regression, pairwise comparisons of estimated PDFF were made between methods (MRI-C, MRI-M, MRS) at each field strength and for each method across field strengths. 1.5T vs. 3T regression analyses for MRI-C, MRI-M, and MRS PDFF measurements yielded R(2) values of 0.99, 0.97, and 0.90, respectively. The best-fit line was near unity (slope(m) = 1, intercept(b) = 0), indicating excellent agreement for each case: MRI-C (m = 0.92 [0.87, 0.99], b = 1.4 [0.7, 1.8]); MRI-M (m = 1.0 [0.90, 1.08], b = -1.4 [-2.4, -0.5]); MRS (m = 0.98 [0.82, 1.15], b = 1.2 [-0.2, 3.0]). Comparing MRI-C and MRI-M yielded an R(2)  = 0.98 (m = 1.1 [1.02, 1.16], b = -1.8 [-2.8, -1.1]) at 1.5T, and R(2)  = 0.99 (m = 0.98 [0.93, 1.03], b = 1.2 [0.7, 1.7]) at 3T. This study demonstrates that PDFF estimation is reproducible across field strengths and across two confounder-corrected MR-based methods. © 2015 Wiley Periodicals, Inc.

Improved skeletal muscle mass and strength after heavy strength training in very old individuals

DEFF Research Database (Denmark)

Bechshøft, Rasmus Leidesdorff; Malmgaard-Clausen, Nikolaj Mølkjær; Gliese, Bjørn

2017-01-01

, muscle fiber type distribution and size did not differ significantly between groups. We conclude that in protein supplemented very old individuals, heavy resistance training can increase muscle mass and strength, and that the relative improvement in mass is more pronounced when initial muscle mass is low.......Age-related loss of muscle mass and function represents personal and socioeconomic challenges. The purpose of this study was to determine the adaptation of skeletal musculature in very old individuals (83 + years) performing 12 weeks of heavy resistance training (3 ×/week) (HRT) compared to a non....... The increase in CSA is correlated inversely with the baseline level of CSA (R2 = 0.43, P muscle isometric strength, isokinetic peak torque and power increased significantly only in HRT by 10–15%, whereas knee extension one-repetition maximum (1 RM) improved by 91%. Physical functional tests...

Quadriceps Strength in Patients With Isolated Cartilage Defects of the Knee: Results of Isokinetic Strength Measurements and Their Correlation With Clinical and Functional Results.

Science.gov (United States)

Hirschmüller, Anja; Andres, Tasja; Schoch, Wolfgang; Baur, Heiner; Konstantinidis, Lukas; Südkamp, Norbert P; Niemeyer, Philipp

2017-05-01

Recent studies have found a significant deficit of maximum quadriceps strength after autologous chondrocyte implantation (ACI) of the knee. However, it is unclear whether muscular strength deficits in patients with cartilage damage exist prior to operative treatment. To isokinetically test maximum quadriceps muscle strength and quantify the impact of possible strength deficits on functional and clinical test results. Cross-sectional study; Level of evidence, 3. To identify clinically relevant muscular strength deficits, 24 patients (5 females, 19 males; mean age, 34.5 years; body mass index, 25.9 kg/m 2 ) with isolated cartilage defects (mean onset, 5.05 years; SD, 7.8 years) in the knee joint underwent isokinetic strength measurements. Maximal quadriceps strength was recorded in 3 different testing modes: pure concentric contraction (flexors and extensors alternating work; con1), concentric-eccentric (only the extensors work concentrically and eccentrically; con2), and eccentric contraction in the alternating mode (ecc). Results were compared for functional performance (single-leg hop test), pain scales (visual analog scale [VAS], numeric rating scale [NRS]), self-reported questionnaires (International Knee Documentation Committee [IKDC], Knee Injury and Osteoarthritis Outcome Scale [KOOS]), and defect size (cm 2 ). Compared with the uninjured leg, significantly lower quadriceps strength was detected in the injured leg in all isokinetic working modes (con1 difference, 27.76 N·m [SD 17.47; P = .003]; con2 difference, 21.45 N·m [SD, 18.45; P =.025]; ecc difference, 29.48 N·m [SD, 21.51; P = .001]), with the largest deficits found for eccentric muscle performance. Moderate negative correlations were observed for the subjective pain scales NRS and VAS. The results of the IKDC and KOOS questionnaires showed low, nonsignificant correlations with findings in the isokinetic measurement. Moreover, defect sizes (mean, 3.13 cm 2 ) were of no importance regarding the

Accurate Maximum Power Tracking in Photovoltaic Systems Affected by Partial Shading

Directory of Open Access Journals (Sweden)

Pierluigi Guerriero

2015-01-01

Full Text Available A maximum power tracking algorithm exploiting operating point information gained on individual solar panels is presented. The proposed algorithm recognizes the presence of multiple local maxima in the power voltage curve of a shaded solar field and evaluates the coordinated of the absolute maximum. The effectiveness of the proposed approach is evidenced by means of circuit level simulation and experimental results. Experiments evidenced that, in comparison with a standard perturb and observe algorithm, we achieve faster convergence in normal operating conditions (when the solar field is uniformly illuminated and we accurately locate the absolute maximum power point in partial shading conditions, thus avoiding the convergence on local maxima.

Mechanical properties of high-strength concrete

Science.gov (United States)

Mokhtarzadeh, Alireza

This report summarizes an experimental program conducted to investigate production techniques and mechanical properties of high strength concrete in general and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. Test variables included total amount and composition of cementitious material (portland cement, fly ash, and silica fume), type and brand of cement, type of silica fume (dry densified and slurry), type and brand of high-range water-reducing admixture, type of aggregate, aggregate gradation, maximum aggregate size, and curing. Tests were conducted to determine the effects of these variables on changes in compressive strength and modulus of elasticity over time, splitting tensile strength, modulus of rupture, creep, shrinkage, and absorption potential (as an indirect indicator of permeability). Also investigated were the effects of test parameters such as mold size, mold material, and end condition. Over 6,300 specimens were cast from approximately 140 mixes over a period of 3 years.

Combining Experiments and Simulations Using the Maximum Entropy Principle

DEFF Research Database (Denmark)

Boomsma, Wouter; Ferkinghoff-Borg, Jesper; Lindorff-Larsen, Kresten

2014-01-01

in the context of a simple example, after which we proceed with a real-world application in the field of molecular simulations, where the maximum entropy procedure has recently provided new insight. Given the limited accuracy of force fields, macromolecular simulations sometimes produce results...

Maximum physical capacity testing in cancer patients undergoing chemotherapy

DEFF Research Database (Denmark)

Knutsen, L.; Quist, M; Midtgaard, J

2006-01-01

BACKGROUND: Over the past few years there has been a growing interest in the field of physical exercise in rehabilitation of cancer patients, leading to requirements for objective maximum physical capacity measurement (maximum oxygen uptake (VO(2max)) and one-repetition maximum (1RM)) to determin...... early in the treatment process. However, the patients were self-referred and thus highly motivated and as such are not necessarily representative of the whole population of cancer patients treated with chemotherapy....... in performing maximum physical capacity tests as these motivated them through self-perceived competitiveness and set a standard that served to encourage peak performance. CONCLUSION: The positive attitudes in this sample towards maximum physical capacity open the possibility of introducing physical testing...

Roles of pinning strength and density in vortex melting

International Nuclear Information System (INIS)

Obaidat, I M; Khawaja, U Al; Benkraouda, M

2008-01-01

We have investigated the role of pinning strength and density on the equilibrium vortex-lattice to vortex-liquid phase transition under several applied magnetic fields. This study was conducted using a series of molecular dynamic simulations on several samples with different strengths and densities of pinning sites which are arranged in periodic square arrays. We have found a single solid-liquid vortex transition when the vortex filling factor n>1. We have found that, for fixed pinning densities and strengths, the melting temperature, T m , decreases almost linearly with increasing magnetic field. Our results provide direct numerical evidence for the significant role of both the strength and density of pinning centers on the position of the melting line. We have found that the vortex-lattice to vortex-liquid melting line shifts up as the pinning strength or the pinning density was increased. The effect on the melting line was found to be more pronounced at small values of strength and density of pinning sites

The pattern of the electromagnetic field emitted by mobile phones in motor vehicle driving simulators

Directory of Open Access Journals (Sweden)

Piotr Politański

2013-06-01

Full Text Available Introduction: The paper reports the results of the determinations of UMTS EMF distributions in the driver's cab of motor vehicle simulators. The results will serve as the basis for future research on the influence of EMF emitted by mobile phones on driver physiology. Materials and Methods: Two motor vehicle driving simulators were monitored, while an EMF source was placed at the driver's head or on the dashboard of the motor vehicle driving simulator. For every applied configuration, the maximal electric field strength was measured, as were the values at 16 points corresponding to chosen locations on a driver's or passenger's body. Results: When the power was set for the maximum (49 mW, a value of 27 V/m was measured in the vicinity of the driver's head when the phone was close to the head. With the same power, when the phone was placed on the dashboard, the measured maximum was 15.2 V/m in the vicinity of the driver's foot. Similar results were obtained for the passenger. Significant perturbations in EMF distribution and an increase in electric field strength values in the motor vehicle driving simulator were also observed in comparison to free space measurements, and the electric field strength was up to 3 times higher inside the simulator. Conclusions: This study can act as the basis of future studies concerning the influence of the EMF emitted by mobile phones on the physiology of the driver. Additionally, the authors postulate that it is advisable to keep mobile phones at a distance from the head, i.e. use, whenever possible, hands-free kits to reduce EMF exposure, both for drivers and passengers.

A label field fusion bayesian model and its penalized maximum rand estimator for image segmentation.

Science.gov (United States)

Mignotte, Max

2010-06-01

This paper presents a novel segmentation approach based on a Markov random field (MRF) fusion model which aims at combining several segmentation results associated with simpler clustering models in order to achieve a more reliable and accurate segmentation result. The proposed fusion model is derived from the recently introduced probabilistic Rand measure for comparing one segmentation result to one or more manual segmentations of the same image. This non-parametric measure allows us to easily derive an appealing fusion model of label fields, easily expressed as a Gibbs distribution, or as a nonstationary MRF model defined on a complete graph. Concretely, this Gibbs energy model encodes the set of binary constraints, in terms of pairs of pixel labels, provided by each segmentation results to be fused. Combined with a prior distribution, this energy-based Gibbs model also allows for definition of an interesting penalized maximum probabilistic rand estimator with which the fusion of simple, quickly estimated, segmentation results appears as an interesting alternative to complex segmentation models existing in the literature. This fusion framework has been successfully applied on the Berkeley image database. The experiments reported in this paper demonstrate that the proposed method is efficient in terms of visual evaluation and quantitative performance measures and performs well compared to the best existing state-of-the-art segmentation methods recently proposed in the literature.

Microtensile strength of spruce pine after exposure to acids and bases

Science.gov (United States)

F.G. Manwiller; P.R. Godfrey

1973-01-01

Earlywood and latewood microtensile specimens from 12 trees of Pinus glabra Walt. were subjected to 10-percent solution of 5 acids and 3 bases at good for up to 3 hours. Hydrochloric and sulfuric acids were the most damaging, lowering maximum tensile strength 27 and 17 percent in earlywood and 36 and 39 percent in latewood; they reduced work to maximum load 40 percent...

Muscle Fiber Type Composition and Knee Extension Isometric Strength Fatigue Patterns in Power- and Endurance-Trained Males.

Science.gov (United States)

Kroll, Walter; And Others

1980-01-01

There is a degree of uniqueness in fatigue patterns, particularly between different levels of absolute maximum strength. Caution should be used when analyzing fatigue curves among subjects with unspecified strength levels. (CJ)

Properties of partially ionized hydrogen plasmas in high electric fields

International Nuclear Information System (INIS)

Morawetz, K.

1993-03-01

In this thesis the fundamental equations of many-particle quantum-statistics of nonequilibrium are treated in respect to arbitrary high electric fields. Generalizations are found for the T-matrix approximation as well as for the shielded potential approximation valid for any field strength. These result in a non-Markovian behavior of the obtained collision integrals, also known as intra-collisional-field-effect (ICFE), and in a broadening of the energy conservation, the so-called collisional broadening (CB), caused by applied electric fields. In linear response it is shown in a new way, how the Debye-Onsager relaxation effect can be rederived from these collision integrals. Furthermore the complete quantum result is presented. Both effects, ICFE and CB, contribute to the right classical limit. The quantum result yields an surprising maximum of this field effects in dependence of the interacting mass ratio, which may be important in exciton-plasmas and semiconductors. (orig.)

Occupational exposure of NRM spectrometrists to static and radiofrequency fields

International Nuclear Information System (INIS)

Berlana, Tania; Ubeda, Alejandro

2017-01-01

Occupational exposure to static and radiofrequency fields emitted by nuclear magnetic resonance spectrometers was assessed through systematic field metering during operation of 19 devices in nine research centers. Whereas no measurable levels of radiofrequency radiation were registered outside the spectrometers, significant exposure to static field was detected, with maximum values recorded at the user s hand (B = 683.00 mT) and head thorax (B = 135.70 mT) during spectrometer manipulation. All values were well below the exposure limits set by the European standard for workers protection against the effects of acute field exposure only. As for potential effects of chronic exposure, waiting for more complete knowledge, adoption of technical and operational strategies for exposure minimizing is advisable. In this respect, the data revealed that compared with standard magnetic shielding, ultra-shield technology allows a 20-65-fold reduction of the field strength received by the operator. (authors)

Fatigue Strength of Reinforced Concrete Flexural Members | Kuryllo ...

African Journals Online (AJOL)

It is well known that reinforced concrete flexural members subjected to cyclic loads behave differently compared with static bending and can collapse due to the fatigue of concrete, reinforcement or both when maximum fatigue stresses of concrete and steel are well below the corresponding static strengths. But up till now ...

Electric field strength and plasma delay in silicon surface barrier detector

International Nuclear Information System (INIS)

Kanno, I.; Inbe, T.; Kanazawa, S.; Kimura, I.

1994-01-01

The resistivity change of a silicon irradiated by high energy neutrons became an interest of study associated with the large scale accelerator projects . The increase of the resistivity of the silicon of a silicon surface barrier detector (SSBD) was studied as a function of neutron fluence. The plasma delay, which was an interesting but not favorite timing property of the SSBD, was reported being dependent on the resistivity of silicon . The neutron irradiation brings the change of timing property as well as the resistivity change on the SSBD. The resistivity dependence of the plasma delay should be studied for the purpose of high energy accelerator experiments. Some empirical formulae of the plasma delay were reported, however, there were no discussions on the physical meanings of the resistivity dependence of the plasma delay. The plasma delay in a SSBD is discussed in the light of electric field strength in the depletion layer of the SSBD. The explanation of the plasma delay is presented taking into account of the competing two electric forces. The resistivity of the silicon affects the plasma delay through the electric forces. 3 figs, 3 refs. (author)

Dependence of streamer density on electric field strength on positive electrode

Science.gov (United States)

Koki, Nakamura; Takahumi, Okuyama; Wang, Douyan; Takao, N.; Hidenori, Akiyama; Kumamoto University Collaboration

2015-09-01

Pulsed streamer discharge plasma, a type of non-thermal plasma, is known as generation method of reactive radicals and ozone and treatment of exhausted gas. From our previous research, the distance between electrodes has been considered a very important parameter for applications using pulsed streamer discharge. However, how the distance between electrodes affects the pulsed discharge hasn't been clarified. In this research, the propagation process of pulsed streamer discharge in a wire-plate electrode was observed using an ICCD camera for 4 electrodes having different distance between electrodes. The distance between electrodes was changeable at 45 mm, 40 mm, 35 mm, and 30 mm. The results show that, when the distance between electrodes was shortened, applied voltage with a pulse duration of 100 ns decreased from 80 to 60.3 kV. Conversely, discharge current increased from 149 to 190 A. Streamer head velocity became faster. On the other hand, Streamer head density at onset time of streamer head propagation didn't change. This is considered due to the electric field strength of streamer head at that time, in result, it was about 14 kV/mm under each distance between electrodes.

In-situ electric field in human body model in different postures for wireless power transfer system in an electrical vehicle

International Nuclear Information System (INIS)

Shimamoto, Takuya; Laakso, Ilkka; Hirata, Akimasa

2015-01-01

The in-situ electric field of an adult male model in different postures is evaluated for exposure to the magnetic field leaked from a wireless power transfer system in an electrical vehicle. The transfer system is located below the centre of the vehicle body and the transferred power and frequency are 7 kW and 85 kHz, respectively. The in-situ electric field is evaluated for a human model (i) crouching near the vehicle, (ii) lying on the ground with or without his arm stretched, (iii) sitting in the driver’s seat, and (iv) standing on a transmitting coil without a receiving coil. In each scenario, the maximum in-situ electric fields are lower than the allowable limit prescribed by international guidelines, although the local magnetic field strength in regions of the human body is higher than the allowable external magnetic field strength. The highest in-situ electric field is observed when the human body model is placed on the ground with his arm extended toward the coils, because of a higher magnetic field around the arm. (paper)

In-situ electric field in human body model in different postures for wireless power transfer system in an electrical vehicle.

Science.gov (United States)

Shimamoto, Takuya; Laakso, Ilkka; Hirata, Akimasa

2015-01-07

The in-situ electric field of an adult male model in different postures is evaluated for exposure to the magnetic field leaked from a wireless power transfer system in an electrical vehicle. The transfer system is located below the centre of the vehicle body and the transferred power and frequency are 7 kW and 85 kHz, respectively. The in-situ electric field is evaluated for a human model (i) crouching near the vehicle, (ii) lying on the ground with or without his arm stretched, (iii) sitting in the driver's seat, and (iv) standing on a transmitting coil without a receiving coil. In each scenario, the maximum in-situ electric fields are lower than the allowable limit prescribed by international guidelines, although the local magnetic field strength in regions of the human body is higher than the allowable external magnetic field strength. The highest in-situ electric field is observed when the human body model is placed on the ground with his arm extended toward the coils, because of a higher magnetic field around the arm.

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

Science.gov (United States)

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 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.

Effect of strain rate and notch geometry on tensile properties and fracture mechanism of creep strength enhanced ferritic P91 steel

Science.gov (United States)

Pandey, Chandan; Mahapatra, M. M.; Kumar, Pradeep; Saini, N.

2018-01-01

Creep strength enhanced ferritic (CSEF) P91 steel were subjected to room temperature tensile test for quasi-static (less than 10-1/s) strain rate by using the Instron Vertical Tensile Testing Machine. Effect of different type of notch geometry, notch depth and angle on mechanical properties were also considered for different strain rate. In quasi-static rates, the P91 steel showed a positive strain rate sensitivity. On the basis of tensile data, fracture toughness of P91 steel was also calculated numerically. For 1 mm notch depth (constant strain rate), notch strength and fracture toughness were found to be increased with increase in notch angle from 45° to 60° while the maximum value attained in U-type notch. Notch angle and notch depth has found a minute effect on P91 steel strength and fracture toughness. The fracture surface morphology was studied by field emission scanning electron microscopy (FESEM).

A Systematic Review of Isometric Lingual Strength-Training Programs in Adults With and Without Dysphagia.

Science.gov (United States)

McKenna, Victoria S; Zhang, Bin; Haines, Morgan B; Kelchner, Lisa N

2017-05-17

This systematic review summarizes the effects of isometric lingual strength training on lingual strength and swallow function in adult populations. Furthermore, it evaluates the designs of the reviewed studies and identifies areas of future research in isometric lingual strength training for dysphagia remediation. A comprehensive literature search of 3 databases and additional backward citation search identified 10 studies for inclusion in the review. The review reports and discusses the isometric-exercise intervention protocols, pre- and postintervention lingual-pressure data (maximum peak pressures and lingual-palatal pressures during swallowing), and oropharyngeal swallowing measures such as penetration-aspiration scales, oropharyngeal residue and duration, lingual volumes, and quality-of-life assessments. Studies reported gains in maximum peak lingual pressures following isometric lingual strength training for both healthy adults and select groups of individuals with dysphagia. However, due to the variability in study designs, it remains unclear whether strength gains generalize to swallow function. Although isometric lingual strength training is a promising intervention for oropharyngeal dysphagia, the current literature is too variable to confidently report specific therapeutic benefits. Future investigations should target homogenous patient populations and use randomized controlled trials to determine the efficacy of this treatment for individuals with dysphagia.

Study of the variation of maximum beam size with quadrupole gradient in the FMIT drift tube linac

International Nuclear Information System (INIS)

Boicourt, G.P.; Jameson, R.A.

1981-01-01

The sensitivity of maximum beam size to input mismatch is studied as a function of quadrupole gradient in a short, high-current, drift-tube linac (DTL), for two presriptions: constant phase advance with constant filling factor; and constant strength with constant-length quads. Numerical study using PARMILA shows that the choice of quadrupole strength that minimizes the maximum transverse size of the matched beam through subsequent cells of the linac tends to be most sensitive to input mismatch. However, gradients exist nearby that result in almost-as-small beams over a suitably broad range of mismatch. The study was used to choose the initial gradient for the DTL portion of the Fusion Material Irradiation Test (FMIT) linac. The matching required across quad groups is also discussed

Effect of shallow angles on compressive strength of biaxial and triaxial laminates.

Science.gov (United States)

Jia, Hongli; Yang, Hyun-Ik

2016-01-01

Biaxial (BX) and triaxial (TX) composite laminates with ±45° angled plies have been widely used in wind turbine blades. As the scale of blades increases, BX and TX laminates with shallow-angled plies (i.e. off-axis ply angle shallow-angled BX and TX laminates are critical considering their locations in a wind turbine blade, and therefore in this study, the uniaxial static compression tests were conducted using BX and TX laminates with angled-plies of ±45°, ±35°, and ±25°, for the purpose of evaluation. On the other hand, Mori-Tanaka mean field homogenization method was employed to predict elastic constants of plies in BX and TX laminates involved in tests; linear regression analyses of experimentally measured ply strengths collected from various sources were then performed to estimate strengths of plies in BX and TX laminates; finally, Tsai-Wu, Hashin, and Puck failure criteria were chosen to predict compressive strengths of BX and TX laminates. Comparison between theoretical predictions and test results were carried out to illustrate the effectiveness of each criterion. The compressive strength of BX laminate decreases as ply angle increases, and the trend was successfully predicted by all three failure criteria. For TX laminates, ±35° angled plies rather than ±45° angled plies led to the lowest laminate compressive strength. Hashin and Puck criteria gave good predictions at certain ply angles for TX laminates, but Tsai-Wu criterion was able to capture the unexpected strength variation of TX laminates with ply angle. It was concluded that the transverse tensile stress in 0° plies of TX laminates, which attains its maximum when the off-axis ply angle is 35°, is the dominant factor in failure determination if using Tsai-Wu criterion. This explains the unexpected strength variation of TX laminates with ply angle, and also indicates that proper selection of ply angle is the key to fully utilizing the advantages of shallow-angled laminates.

Assessment of Industrial Exposure to Magnetic Fields (invited paper)

International Nuclear Information System (INIS)

Chadwick, P.

1999-01-01

Magnetic field strengths produced by industrial processes can be very large, but they often exhibit a marked spatial variation. Whilst there may be the potential for exposures of workers to be high, actual exposure will be determined to a great extent by working practices. Possible metrics for epidemiological studies might be based on the temporal variability of exposure as well as maximum operator exposure or time-weighted average exposure and, whilst it might be possible to estimate these quantities from spot magnetic field strength measurements and observed working practices, this might be very difficult to achieve in practice. An alternative would be the use of a logging dosemeter: this paper describes some of the results of exposure assessments carried out in industrial environments with a modified EMDEX II magnetic field dosemeter. Magnetic fields in industrial environments often have waveforms which are not purely sinusoidal. Distortion can be introduced by the magnetic saturation of transformer and motor cores, by rectification, by poor matching between oscillator circuits and loads and when thyristors are used to control power. The resulting repetitive but non-sinusoidal magnetic field waveforms can be recorded and analysed; the spectral data may be incorporated into possible exposure metrics. It is also important to ensure that measurement instrumentation is responding appropriately in a non-sinusoidal field and this can only be done if the spectral content of the field is characterised fully. Some non-sinusoidal magnetic field waveforms cannot be expressed as a harmonic series. Specialist instrumentation and techniques are needed to assess exposure to such fields. Examples of approaches to the assessment of exposure to repetitive and non-repetitive magnetic fields are also discussed. (author)

Excess electron mobility in ethane. Density, temperature, and electric field effects

International Nuclear Information System (INIS)

Doeldissen, W.; Schmidt, W.F.; Bakale, G.

1980-01-01

The excess electron mobility in liquid ethane was measured under orthobaric conditions as a function of temperature and electric field strength up to the critical temperature at 305.33 K. The low field mobility was found to rise strongly with temperature and exhibits a maximum value of 44 cm 2 V -1 s -1 at 2 0 below the critical temperature. At temperatures above 260 K the electron drift velocity shows a sublinear field dependence at high values of the electric field strength. These observations lead to the supposition that in liquid ethane a transition from transport via localized states to transport in extended states occurs. Measurements were also performed in fluid ethane at densities from 2.4 to 12.45 mol L -1 and temperatures from 290 to 340 K. On isochores in the vicinity of the critical density, an increase of the low field mobility with temperature was observed. This effect was found to disappear both at low (rho = 2.4 mol L -1 ) and high densities (rho greater than or equal to 9.2 mol L -1 ). In this density range, a sublinear field dependence of the drift velocities at high field strengths was noted. The critical velocity associated with the appearance of hot electrons was observed to decrease with higher densities indicating a smaller fractional energy transfer in electron molecule collisions. A compilation of electron mobilities in gaseous and liquid ethane shows that, up to densitiesof rho = 9.5 mol L -1 , μ proportional to n -1 is fulfilled if temperature effects are ignored. At intermediate densities, 9 mol L -1 -1 , a density dependence of μ proportional to rho -5 is found followed by a stronger mobility decrease toward the triple point. Positive ion mobilities measured under orthobaric conditions followed Walden's rule

Vertical bending strength and torsional rigidity analysis of formula student car chassis

Science.gov (United States)

Hazimi, Hashfi; Ubaidillah, Setiyawan, Adi Eka Putra; Ramdhani, Hanief Cahya; Saputra, Murnanda Zaesy; Imaduddin, Fitrian

2018-02-01

Formula Society of Automotive Engineers (FSAE) is a competition for students to construct formula student car. One of an essential part of a formula student car is its chassis. Chassis is an internal vehicle frame which holds all another part of the vehicle and secures the driver. The team have to design their chassis and tests their design to achieve the best chassis that fulfill the regulation. This paper contains chassis design from Bengawan FSAE Team and some FEA tests to find out the Tensile Strength, Torsional Rigidity, and Von Misses Stress of Formula SAE car. Torsional rigidity was found by applying the static torsional test. The results from torsional rigidity test are a maximum deformation of 9.9512 mm with 1.7064 safety factor, and 35.935 MPa maximum Von Misses Stress. Moreover, then the result of the vertical bending strength test is 8.1214 mm max deformation with safety factor 4.2717, and 29.226 MPa maximum Von Misses Stress.

World's largest DC flywheel generator for the toroidal field power supply of JAERI's JFT-2M Tokamak nuclear fusion reactor

International Nuclear Information System (INIS)

Tani, Takashi; Nakanishi, Yuji; Horita, Tsuyoshi; Kawase, Chiharu; Oyabu, Isao; Kishimoto, Takeshi.

1996-01-01

Mitsubishi Electric has delivered the world's largest DC generator for the toroidal field coil power supply of the JFT-2M Tokamak at the Japan Atomic Energy Research Institute. The unit rotates at 225 or 460 rpm, providing a maximum rated output of 2,700 V, 19,000 A and 51.3 MW. The toroidal field is a DC field, so use of a DC generator permits a simpler design consuming less floor space than an AC drive system. The generator was manufactured following extensive studies on commutation, mechanical strength and insulation. (author)

Residual Strength of In-plane Loaded Debonded Sandwich Panels

DEFF Research Database (Denmark)

Berggreen, Carl Christian; Simonsen, Bo Cerup

2005-01-01

This paper presents a FEM based numerical model for prediction of residual strength of damaged sandwich panels. As demonstrated, the model can predict the maximum load carrying capacity of real-life panels with debond damages, where the failure is governed by face-sheet buckling followed by debond...

Effect of Seed Orientation and Medium Strength on In vitro Germination of Pterocarpus marsupium Roxb.

Directory of Open Access Journals (Sweden)

Yogeshwar MISHRA

2013-12-01

Full Text Available A method was developed for optimization of In vitro germination of an economically important timber-yielding multipurpose tree, Pterocarpus marsupium Roxb. The seeds inoculated in different orientation on different strengths of MS medium without any hormones showed varied response to the seed positions. The seeds inoculated on half strength medium in horizontal position recorded to produce a maximum germination (78.23%, shoot number (0.86 and root number (7.99. However, a maximum of shoot length of 3.67 cm was recorded in the quarter strength medium in the seeds inoculated in vertical down position, which was significantly higher than other media strength and positions. Our results indicate that the seed orientation including medium strength have tremendous effect on germination and seeds inoculated horizontally on half strength MS medium can be utilized to enhance In vitro seed germination of Pterocarpus marsupium.

Enhanced accuracy of the microwave field strength measurement in a CW-EPR by pulsed modulation technique

Science.gov (United States)

Rakvin, B.; Carić, D.; Kveder, M.

2018-02-01

The microwave magnetic field strength, B1, in the cavity of a conventional continuous wave electron paramagnetic resonance, CW-EPR, spectrometer was measured by employing modulation sidebands, MS, in the EPR spectrum. MS spectrum in CW-EPR is produced by applying the modulation frequency, ωrf, which exceeds the linewidth, δB, given in frequency units. An amplitude-modulated CW-EPR, AM-CW-EPR, was selected as detection method. Theoretical description of AM-CW-EPR spectrum was modified by adding Bloch-Siegert-like shift obtained by taking into account the cumulative effect of the non-resonant interactions between the driving fields and the spin system. This approach enables to enhance the precision of B1 measurement. In order to increase the sensitivity of the method when saturation effects, due to higher intensity of B1, decrease the resolution of AM-CW-EPR spectrum, detection at the second harmonic of CW-EPR has been employed.

Enhanced accuracy of the microwave field strength measurement in a CW-EPR by pulsed modulation technique.

Science.gov (United States)

Rakvin, B; Carić, D; Kveder, M

2018-02-01

The microwave magnetic field strength, B 1 , in the cavity of a conventional continuous wave electron paramagnetic resonance, CW-EPR, spectrometer was measured by employing modulation sidebands, MS, in the EPR spectrum. MS spectrum in CW-EPR is produced by applying the modulation frequency, ω rf , which exceeds the linewidth, δB, given in frequency units. An amplitude-modulated CW-EPR, AM-CW-EPR, was selected as detection method. Theoretical description of AM-CW-EPR spectrum was modified by adding Bloch-Siegert-like shift obtained by taking into account the cumulative effect of the non-resonant interactions between the driving fields and the spin system. This approach enables to enhance the precision of B 1 measurement. In order to increase the sensitivity of the method when saturation effects, due to higher intensity of B 1 , decrease the resolution of AM-CW-EPR spectrum, detection at the second harmonic of CW-EPR has been employed. Copyright © 2018 Elsevier Inc. All rights reserved.

Selection of the Maximum Spatial Cluster Size of the Spatial Scan Statistic by Using the Maximum Clustering Set-Proportion Statistic.

Science.gov (United States)

Ma, Yue; Yin, Fei; Zhang, Tao; Zhou, Xiaohua Andrew; Li, Xiaosong

2016-01-01

Spatial scan statistics are widely used in various fields. The performance of these statistics is influenced by parameters, such as maximum spatial cluster size, and can be improved by parameter selection using performance measures. Current performance measures are based on the presence of clusters and are thus inapplicable to data sets without known clusters. In this work, we propose a novel overall performance measure called maximum clustering set-proportion (MCS-P), which is based on the likelihood of the union of detected clusters and the applied dataset. MCS-P was compared with existing performance measures in a simulation study to select the maximum spatial cluster size. Results of other performance measures, such as sensitivity and misclassification, suggest that the spatial scan statistic achieves accurate results in most scenarios with the maximum spatial cluster sizes selected using MCS-P. Given that previously known clusters are not required in the proposed strategy, selection of the optimal maximum cluster size with MCS-P can improve the performance of the scan statistic in applications without identified clusters.

Measurement of magnetic fields in the Area Metropolitana

International Nuclear Information System (INIS)

Masis Mesen, Juan Pablo

2007-01-01

The operation and proper handling of equipment for measuring EMR-300 electromagnetic waves are studied and apply that knowledge to determine which areas of the metropolitan area are mostly affected by exposure to the emission of radiation. This team is able to measure magnetic field strength, electric field strength and power density, also can measure the most important parameters in a simple manner. International standards provide maximum values for these parameters that limit human exposure to such radiation. These standards are based on epidemiological several and laboratory that have been carried out in order to determine in which circumstances a biological entity is exposed to a level of radiation that can cause harm to their health. It focuses on measuring the level of radiation in certain areas of interest, which were chosen because are areas with high population density and also in proximity to antennas that emit electromagnetic waves. Before carrying out the data collection was performed a detailed study of which are the recommendations to measure and avoid as far as possible sources of error, once that those recommendations are implemented the making data was started. Data obtained show that these areas do not present any health risk and that levels of magnetic field strength and power density are well below the limits set by both the International Commission on Non-Ionizing Radiation Protection and the Institute of Electrical and Electronics Engineers. On the other hand, based on the obtained results and the study already done before by the Instituto Costarricense de Electricidad, it was concluded that the power density conditions for plane wave is the parameter most effective to quantize the associated risk with different levels of radiation of radio frequency electromagnetic fields. (author) [es

A Fracture-Based Criterion for Debonding Strength of Adhesive-Bonded Double-Strap Steel Joints

Directory of Open Access Journals (Sweden)

Prawit Santisukpotha

2012-01-01

Full Text Available This paper addresses the debonding strength of adhesive-bonded double-strap steel joints. A fracture-based criterion was formulated in terms of a stress singularity parameter, i.e., the stress intensity factor, which governs the magnitude of a singular stress field near the joint ends. No existing crack was assumed. A total of 24 steel joint specimens were tested under constant amplitude fatigue loadings at stress ratio of 0.2 and frequency of 2 Hz. The joint stiffness ratio was slightly less than one to control the maximum adhesive stresses at the joint ends. To detect the debonding, a simple and practical technique was developed. The test results showed that the interfacial failure near the steel/adhesive corner was a dominant failure mode. The failure was brittle and the debonding life was governed by the crack initiation stage. The finite element analysis was employed to calculate the stress intensity factors and investigate the effects of the adhesive layer thickness, lap length and joint stiffness ratio on the debonding strength.

A Field Test for Upper Body Strength and Endurance.

Science.gov (United States)

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…

Relative scale and the strength and deformability of rock masses

Science.gov (United States)

Schultz, Richard A.

1996-09-01

The strength and deformation of rocks depend strongly on the degree of fracturing, which can be assessed in the field and related systematically to these properties. Appropriate Mohr envelopes obtained from the Rock Mass Rating (RMR) classification system and the Hoek-Brown criterion for outcrops and other large-scale exposures of fractured rocks show that rock-mass cohesive strength, tensile strength, and unconfined compressive strength can be reduced by as much as a factor often relative to values for the unfractured material. The rock-mass deformation modulus is also reduced relative to Young's modulus. A "cook-book" example illustrates the use of RMR in field applications. The smaller values of rock-mass strength and deformability imply that there is a particular scale of observation whose identification is critical to applying laboratory measurements and associated failure criteria to geologic structures.

The 'strength' of a system of differential equations

International Nuclear Information System (INIS)

Hoenselaers, C.

1977-01-01

A review of Einstein's concept of ''strength'' of a system of differential equations is given. As an example the strength of the Einstein-Maxwell equations for non-null Maxwell field is calculated and shown to be the same as for the pure vacuum Einstein equations. (auth.)

Imaging Shear Strength Along Subduction Faults

Science.gov (United States)

Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Hardebeck, Jeanne L.

2017-11-01

Subduction faults accumulate stress during long periods of time and release this stress suddenly, during earthquakes, when it reaches a threshold. This threshold, the shear strength, controls the occurrence and magnitude of earthquakes. We consider a 3-D model to derive an analytical expression for how the shear strength depends on the fault geometry, the convergence obliquity, frictional properties, and the stress field orientation. We then use estimates of these different parameters in Japan to infer the distribution of shear strength along a subduction fault. We show that the 2011 Mw9.0 Tohoku earthquake ruptured a fault portion characterized by unusually small variations in static shear strength. This observation is consistent with the hypothesis that large earthquakes preferentially rupture regions with relatively homogeneous shear strength. With increasing constraints on the different parameters at play, our approach could, in the future, help identify favorable locations for large earthquakes.

Imaging shear strength along subduction faults

Science.gov (United States)

Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Hardebeck, Jeanne L.

2017-01-01

Subduction faults accumulate stress during long periods of time and release this stress suddenly, during earthquakes, when it reaches a threshold. This threshold, the shear strength, controls the occurrence and magnitude of earthquakes. We consider a 3-D model to derive an analytical expression for how the shear strength depends on the fault geometry, the convergence obliquity, frictional properties, and the stress field orientation. We then use estimates of these different parameters in Japan to infer the distribution of shear strength along a subduction fault. We show that the 2011 Mw9.0 Tohoku earthquake ruptured a fault portion characterized by unusually small variations in static shear strength. This observation is consistent with the hypothesis that large earthquakes preferentially rupture regions with relatively homogeneous shear strength. With increasing constraints on the different parameters at play, our approach could, in the future, help identify favorable locations for large earthquakes.

Moderate-Load Muscular Endurance Strength Training Did Not Improve Peak Power or Functional Capacity in Older Men and Women

Directory of Open Access Journals (Sweden)

Simon Walker

2017-09-01

Full Text Available The present study determined the effects of muscular endurance strength training on maximum strength and power, functional capacity, muscle activation and hypertrophy in older men and women. Eighty-one men and women acted as an intervention group while 22 acted as non-training controls (age range 64–75 y. Intervention training included super-sets (i.e., paired exercises, immediately performing the second exercises following completion of the first with short rest intervals (30–60 s between sets at an intensity of 50–60% one-repetition maximum (1-RM for 15–20 repetitions. Concentric leg press actions measured maximum strength (1-RM and concentric peak power. Functional capacity was assessed by maximum speed walking tests (i.e., forward walk, backward walk, timed-up-and-go, and stair climb tests. Quadriceps muscle activation was assessed by surface electromyogram and twitch interpolation technique. Vastus lateralis cross-sectional area was measured by panoramic ultrasound. Compared to control, the intervention groups increased maximum strength (1-RM; men: 10 ± 7% vs. 2 ± 3%, women: 14 ± 9% vs. 1 ± 6% both P < 0.01 and vastus lateralis cross-sectional area (men: 6 ± 7% vs. −3 ± 6%, women: 10 ± 10% vs. 0 ± 4% both P < 0.05. But there were no between-group differences in peak power, muscle activation or functional capacity (e.g., stair climb; men: −5 ± 7% vs. −4 ± 3%, women: −5 ± 6% vs. −2 ± 5% both P > 0.05. While benefits occurred during muscular endurance strength training, specific stimuli are probably needed to target all aspects of age-related health.

THE RISE AND FALL OF OPEN SOLAR FLUX DURING THE CURRENT GRAND SOLAR MAXIMUM

International Nuclear Information System (INIS)

Lockwood, M.; Rouillard, A. P.; Finch, I. D.

2009-01-01

We use geomagnetic activity data to study the rise and fall over the past century of the solar wind flow speed V SW , the interplanetary magnetic field strength B, and the open solar flux F S . Our estimates include allowance for the kinematic effect of longitudinal structure in the solar wind flow speed. As well as solar cycle variations, all three parameters show a long-term rise during the first half of the 20th century followed by peaks around 1955 and 1986 and then a recent decline. Cosmogenic isotope data reveal that this constitutes a grand maximum of solar activity which began in 1920, using the definition that such grand maxima are when 25-year averages of the heliospheric modulation potential exceeds 600 MV. Extrapolating the linear declines seen in all three parameters since 1985, yields predictions that the grand maximum will end in the years 2013, 2014, or 2027 using V SW , F S , or B, respectively. These estimates are consistent with predictions based on the probability distribution of the durations of past grand solar maxima seen in cosmogenic isotope data. The data contradict any suggestions of a floor to the open solar flux: we show that the solar minimum open solar flux, kinematically corrected to allow for the excess flux effect, has halved over the past two solar cycles.

Prediction Of Tensile And Shear Strength Of Friction Surfaced Tool Steel Deposit By Using Artificial Neural Networks

Science.gov (United States)

Manzoor Hussain, M.; Pitchi Raju, V.; Kandasamy, J.; Govardhan, D.

2018-04-01

Friction surface treatment is well-established solid technology and is used for deposition, abrasion and corrosion protection coatings on rigid materials. This novel process has wide range of industrial applications, particularly in the field of reclamation and repair of damaged and worn engineering components. In this paper, we present the prediction of tensile and shear strength of friction surface treated tool steel using ANN for simulated results of friction surface treatment. This experiment was carried out to obtain tool steel coatings of low carbon steel parts by changing contribution process parameters essentially friction pressure, rotational speed and welding speed. The simulation is performed by a 33-factor design that takes into account the maximum and least limits of the experimental work performed with the 23-factor design. Neural network structures, such as the Feed Forward Neural Network (FFNN), were used to predict tensile and shear strength of tool steel sediments caused by friction.

Magnetic Field Effects on the Plume of a Diverging Cusped-Field Thruster

KAUST Repository

Matlock, Taylor

2010-07-25

The Diverging Cusped-Field Thruster (DCFT) uses three permanent ring magnets of alternating polarity to create a unique magnetic topology intended to reduce plasma losses to the discharge chamber surfaces. The magnetic field strength within the DCFT discharge chamber (up to 4 kG on axis) is much higher than in thrusters of similar geometry, which is believed to be a driving factor in the high measured anode efficiencies. The field strength in the near plume region is large as well, which may bear on the high beam divergences measured, with peaks in ion current found at angles of around 30-35 from the thruster axis. Characterization of the DCFT has heretofore involved only one magnetic topology. It is then the purpose of this study to investigate changes to the near-field plume caused by altering the shape and strength of the magnetic field. A thick magnetic collar, encircling the thruster body, is used to lower the field strength outside of the discharge chamber and thus lessen any effects caused by the external field. Changes in the thruster plume with field topology are monitored by the use of normal Langmuir and emissive probes interrogating the near-field plasma. Results are related to other observations that suggest a unified conceptual framework for the important near-exit region of the thruster.

Bats respond to very weak magnetic fields.

Directory of Open Access Journals (Sweden)

Lan-Xiang Tian

Full Text Available 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.

Growth of pulsed electric field exposed Escherichia coli in relation to inactivation and environmental factors.

Science.gov (United States)

Aronsson, Kristina; Borch, Elisabeth; Stenlöf, Bo; Rönner, Ulf

2004-05-15

Pulsed electric fields (PEF) have been proven to inactivate microorganisms during nonthermal conditions and have the potential to replace thermal processing as a method for food preservation. However, there is a need to understand the recovery and growth of survivors and potentially injured microorganisms following PEF processing. The purpose of this investigation was to study the growth of Escherichia coli at 10 degrees C following exposure to electrical field strengths (15, 22.5 and 30 kV/cm) in relation to inactivation and the amount of potentially sublethally injured cells. One medium was used as both a treatment medium and an incubation medium, to study the influence of environmental factors on the inactivation and the growth of the surviving population. The pH (5.0, 6.0 and 7.0) and water activity (1.00, 0.985 and 0.97) of the medium was varied by adding HCl and glycerol, respectively. Growth was followed continuously by measuring the optical density. The time-to-detection (td) and the maximum specific growth rate (micromax) were calculated from these data. Results showed that the PEF process did not cause any obvious sublethal injury to the E. coli cells. The number of survivors was a consequence of the combination of electrical field strength and environmental factors, with pH being the most prominent. Interestingly, the micromax of subsequent growth was influenced by the applied electrical field strength during the process, with an increased micromax at more intense electrical field strengths. In addition, the micromax was also influenced by the pH and water activity. The td, which could theoretically be considered as an increase in shelf life, was found to depend on a complex correlation between electrical field strength, pH and water activity. That could be explained by the fact that the td is a combination of the number of survivors, the recovery of sublethal injured cells and the growth rate of the survivors. Copyright 2003 Elsevier B.V.

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

Science.gov (United States)

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

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

Science.gov (United States)

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

2016-02-27

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.

Transition-strength fluctuations and the onset of chaotic motion

International Nuclear Information System (INIS)

Alhassid, Y.; Levine, R.D.

1986-01-01

The maximum-entropy formalism is used to characterize the fluctuations in transition strengths for a bound quantum-mechanical system. In the chaotic limit only one, ever present, sum rule is required as a constraint. The resulting distribution is that of Porter and Thomas, which can also be derived from random-matrix theory. For nonchaotic systems the distribution of transition strengths has a lower entropy. A possible additional constraint, operative during the onset of chaos, is proposed. The distribution of maximal entropy subject to both constraints accords with computed intensities in a system of two degrees of freedom

Strong Magnetic Field Characterisation

Science.gov (United States)

2012-04-01

an advertised surface field of approximately 0.5 T were used to supply the static magnetic field source. The disc magnet had a diameter of 50 mm and... colour bar indicates the magnetic field strength set to an arbitrary 0.25 T. The white area has a field >0.25 T. The size of the arrow is proportional...9 shows the magnetic field strength along a slice in the XZ plane. The colours represent the total UNCLASSIFIED 10 UNCLASSIFIED DSTO-TR-2699

Direct comparison of phase-sensitive vibrational sum frequency generation with maximum entropy method: case study of water.

Science.gov (United States)

de Beer, Alex G F; Samson, Jean-Sebastièn; Hua, Wei; Huang, Zishuai; Chen, Xiangke; Allen, Heather C; Roke, Sylvie

2011-12-14

We present a direct comparison of phase sensitive sum-frequency generation experiments with phase reconstruction obtained by the maximum entropy method. We show that both methods lead to the same complex spectrum. Furthermore, we discuss the strengths and weaknesses of each of these methods, analyzing possible sources of experimental and analytical errors. A simulation program for maximum entropy phase reconstruction is available at: http://lbp.epfl.ch/. © 2011 American Institute of Physics

Impact of magnetic field strength and receiver coil in ocular MRI: a phantom and patient study.

Science.gov (United States)

Erb-Eigner, K; Warmuth, C; Taupitz, M; Willerding, G; Bertelmann, E; Asbach, P

2013-09-01

Generally, high-resolution MRI of the eye is performed with small loop surface coils. The purpose of this phantom and patient study was to investigate the influence of magnetic field strength and receiver coils on image quality in ocular MRI. The eyeball and the complex geometry of the facial bone were simulated by a skull phantom with swine eyes. MR images were acquired with two small loop surface coils with diameters of 4 cm and 7 cm and with a multi-channel head coil at 1.5 and 3 Tesla, respectively. Furthermore, MRI of the eye was performed prospectively in 20 patients at 1.5 Tesla (7 cm loop surface coil) and 3 Tesla (head coil). These images were analysed qualitatively and quantitatively and statistical significance was tested using the Wilcoxon-signed-rank test (a p-value of less than 0.05 was considered to indicate statistical significance). The analysis of the phantom images yielded the highest mean signal-to-noise ratio (SNR) at 3 Tesla with the use of the 4 cm loop surface coil. In the phantom experiment as well as in the patient studies the SNR was higher at 1.5 Tesla by applying the 7 cm surface coil than at 3 Tesla by applying the head coil. Concerning the delineation of anatomic structures no statistically significant differences were found. Our results show that the influence of small loop surface coils on image quality (expressed in SNR) in ocular MRI is higher than the influence of the magnetic field strength. The similar visibility of detailed anatomy leads to the conclusion that the image quality of ocular MRI at 3 Tesla remains acceptable by applying the head coil as a receiver coil. © Georg Thieme Verlag KG Stuttgart · New York.

Cooperative effect of random and time-periodic coupling strength on synchronization transitions in one-way coupled neural system: mean field approach.

Science.gov (United States)

Jiancheng, Shi; Min, Luo; Chusheng, Huang

2017-08-01

The cooperative effect of random coupling strength and time-periodic coupling strengh on synchronization transitions in one-way coupled neural system has been investigated by mean field approach. Results show that cooperative coupling strength (CCS) plays an active role for the enhancement of synchronization transitions. There exist an optimal frequency of CCS which makes the system display the best CCS-induced synchronization transitions, a critical frequency of CCS which can not further affect the CCS-induced synchronization transitions, and a critical amplitude of CCS which can not occur the CCS-induced synchronization transitions. Meanwhile, noise intensity plays a negative role for the CCS-induced synchronization transitions. Furthermore, it is found that the novel CCS amplitude-induced synchronization transitions and CCS frequency-induced synchronization transitions are found.

A health examination of railway high-voltage substation workers exposed to ELF electromagnetic fields.

Science.gov (United States)

Baroncelli, P; Battisti, S; Checcucci, A; Comba, P; Grandolfo, M; Serio, A; Vecchia, P

1986-01-01

This is a cross-sectional survey on the health conditions of railways workers active in 258 interconnection and conversion substations all over Italy. Measurements performed in both kinds of substations operating at 220 kV have shown that maximum levels of the electric field strength and of the magnetic flux density at 50 Hz are of the order of 5 kV/m and 15 microT, respectively. Three subject groups, differently exposed (1, 10, 20 h/week), and an unexposed control group, for a total number of 627 workers, constitute the population at study. All subjects underwent a general medical examination, laboratory investigations, and a series of selected examinations relative to three systems (nervous, cardiovascular, and haematopoietic) considered at higher risk. No differences have been found between the exposed and the control groups. It is concluded that workers exposed to ELF electromagnetic fields of moderate strength do not show the presence of clear effects on their state of health.

Radial distributions of magnetic field strength in the solar corona as derived from data on fast halo CMEs

Science.gov (United States)

Fainshtein, Victor; Egorov, Yaroslav

2018-03-01

In recent years, information about the distance between the body of rapid coronal mass ejection (CME) and the associated shock wave has been used to measure the magnetic field in the solar corona. In all cases, this technique allows us to find coronal magnetic field radial profiles B(R) applied to the directions almost perpendicular to the line of sight. We have determined radial distributions of magnetic field strength along the directions close to the Sun-Earth axis. For this purpose, using the "ice-cream cone" model and SOHO/LASCO data, we found 3D characteristics for fast halo coronal mass ejections (HCMEs) and for HCME-related shocks. With these data, we managed to obtain the B(R) distributions as far as ≈43 solar radii from the Sun's center, which is approximately twice as far as those in other studies based on LASCO data. We have concluded that to improve the accuracy of this method for finding the coronal magnetic field we should develop a technique for detecting CME sites moving in the slow and fast solar wind. We propose a technique for selecting CMEs whose central (paraxial) part actually moves in the slow wind.

Predicting Folding Sequences Based on the Maximum Rock Strength and Mechanical Equilibrium

Science.gov (United States)

Cubas, N.; Souloumiac, P.; Maillot, B.; Leroy, Y. M.

2007-12-01

The objective is to propose and validate simple procedures, compared to the finite-element method, to select and optimize the dominant mode of folding in fold-and-thrust belts and accretionary wedges, and to determine its stress distribution. Mechanical equilibrium as well as the constraints due to the limited rock strength of the bulk material and of major discontinuities, such as décollements, are accounted for. The first part of the proposed procedure, which is at the core of the external approach of classical limit analysis, consists in estimating the least upper bound on the tectonic force by minimisation of the internal dissipation and part of the external work. The new twist to the method is that the optimization is also done with respect to the geometry of the evolving fold. If several folding events are possible, the dominant mode is the one leading to the least upper bound. The second part of the procedure is based on the Equilibrium Element Method, which is an application of the internal approach of limit analysis. The optimum stress field, obtained by spatial discretisation of the fold, provides the best lower bound on the tectonic force. The difference between the two bounds defines an error estimate of the exact unknown tectonic force. To show the merits of the proposed procedure, its first part is applied to predict the life span of a thrust within an accretionary prism, from its onset, its development with a relief build up and its arrest because of the onset of a more favorable new thrust (Cubas et al., 2007). This life span is sensitive to the friction angles over the ramp and the décollement. It is shown how the normal sequence of thrusting in a supercritical wedge is ended with the first out-of sequence event. The second part of the procedure provides the stress state over each thrust showing that the active back thrust is a narrow fan which dip is sensitive to the friction angle over the ramp and the amount of relief build up (Souloumiac et

Effect of Pressure and Heat Treatments on the Compressive Strength of Reactive Powder Concrete

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Helmi Masdar

2018-01-01

Full Text Available This paper presents the corresponding compressive strength of RPC with variable pressure combined with heating rate, heating duration, and starting time of heating. The treatments applied were 8 MPa static pressure on fresh RPC prims and heat curing at 240 °C in an oven. The compressive strength test was conducted at 7-d and 28-d. The images of RPC morphology were captured on the surface of a fractured specimen using Scanning Electron Microscopy in Secondary Electron detector mode to describe pore filing mechanism after treatments. The results show that a heating rate at 50 °C/hr resulted in the highest compressive strength about 40 % more than those at 10 or 100 °C/hr. A heating duration of 48 hours led to the maximum compressive strength. Heat curing applied 2 days after casting resulted in the maximum compressive. Heat curing had a signicant effect on the compresssive strength due to the acceleration of both reactions (hydration and pozzolanic and the degree of transformation from tobermorite to xonotlite. It is concluded that the optimum condition of treatments is both pressure and heat curing at 2-day after casting with a rate of 50 °C/hr for 48 hours.

Exposure to electromagnetic fields from smart utility meters in GB; part I) laboratory measurements.

Science.gov (United States)

Peyman, Azadeh; Addison, Darren; Mee, Terry; Goiceanu, Cristian; Maslanyj, Myron; Mann, Simon

2017-05-01

Laboratory measurements of electric fields have been carried out around examples of smart meter devices used in Great Britain. The aim was to quantify exposure of people to radiofrequency signals emitted from smart meter devices operating at 2.4 GHz, and then to compare this with international (ICNIRP) health-related guidelines and with exposures from other telecommunication sources such as mobile phones and Wi-Fi devices. The angular distribution of the electric fields from a sample of 39 smart meter devices was measured in a controlled laboratory environment. The angular direction where the power density was greatest was identified and the equivalent isotropically radiated power was determined in the same direction. Finally, measurements were carried out as a function of distance at the angles where maximum field strengths were recorded around each device. The maximum equivalent power density measured during transmission around smart meter devices at 0.5 m and beyond was 15 mWm -2 , with an estimation of maximum duty factor of only 1%. One outlier device had a maximum power density of 91 mWm -2 . All power density measurements reported in this study were well below the 10 W m -2 ICNIRP reference level for the general public. Bioelectromagnetics. 2017;38:280-294. © 2017 Crown copyright. BIOELECTROMAGNETICS © 2017 Wiley Periodicals, Inc. © 2017 Crown copyright. BIOELECTROMAGNETICS © 2017 Wiley Periodicals, Inc.

Effect of Protein Intake on Strength, Body Composition and Endocrine Changes in Strength/Power Athletes

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Kang Jie

2006-12-01

Full Text Available Abstract Comparison of protein intakes on strength, body composition and hormonal changes were examined in 23 experienced collegiate strength/power athletes participating in a 12-week resistance training program. Subjects were stratified into three groups depending upon their daily consumption of protein; below recommended levels (BL; 1.0 – 1.4 g·kg-1·day-1; n = 8, recommended levels (RL; 1.6 – 1.8 g·kg-1·day-1; n = 7 and above recommended levels (AL; > 2.0 g·kg-1·day-1; n = 8. Subjects were assessed for strength [one-repetition maximum (1-RM bench press and squat] and body composition. Resting blood samples were analyzed for total testosterone, cortisol, growth hormone, and insulin-like growth factor. No differences were seen in energy intake (3,171 ± 577 kcal between the groups, and the energy intake for all groups were also below the recommended levels for strength/power athletes. No significant changes were seen in body mass, lean body mass or fat mass in any group. Significant improvements in 1-RM bench press and 1-RM squat were seen in all three groups, however no differences between the groups were observed. Subjects in AL experienced a 22% and 42% greater change in Δ 1-RM squat and Δ 1-RM bench press than subjects in RL, however these differences were not significant. No significant changes were seen in any of the resting hormonal concentrations. The results of this study do not provide support for protein intakes greater than recommended levels in collegiate strength/power athletes for body composition improvements, or alterations in resting hormonal concentrations.

Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions

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Othuman Mydin M.A.

2014-01-01

Full Text Available Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder.

Effects of endurance training only versus same-session combined endurance and strength training on physical performance and serum hormone concentrations in recreational endurance runners.

Science.gov (United States)

Schumann, Moritz; Mykkänen, Olli-Pekka; Doma, Kenji; Mazzolari, Raffaele; Nyman, Kai; Häkkinen, Keijo

2015-01-01

This study investigated the effects of endurance training only (E, n = 14) and same-session combined training, when strength training is repeatedly preceded by endurance loading (endurance and strength training (E+S), n = 13) on endurance (1000-m running time during incremental field test) and strength performance (1-repetition maximum (1RM) in dynamic leg press), basal serum hormone concentrations, and endurance loading-induced force and hormone responses in recreationally endurance-trained men. E was identical in the 2 groups and consisted of steady-state and interval running, 4-6 times per week for 24 weeks. E+S performed additional mixed-maximal and explosive-strength training (2 times per week) immediately following an incremental running session (35-45 min, 65%-85% maximal heart rate). E and E+S decreased running time at week 12 (-8% ± 5%, p = 0.001 and -7% ± 3%, p force (-5% to -9%, p = 0.032 to 0.001) and testosterone and cortisol responses (18%-47%, p = 0.013 to p benefits when strength training was performed repeatedly after endurance training compared with endurance training only. This was supported by similar acute responses in force and hormonal measures immediately post-endurance loading after the training with sustained 1RM strength in E+S.

Corrosion Behavior and Strength of Dissimilar Bonding Material between Ti and Mg Alloys Fabricated by Spark Plasma Sintering

Science.gov (United States)

Pripanapong, Patchara; Kariya, Shota; Luangvaranunt, Tachai; Umeda, Junko; Tsutsumi, Seiichiro; Takahashi, Makoto; Kondoh, Katsuyoshi

2016-01-01

Ti and solution treated Mg alloys such as AZ31B (ST), AZ61 (ST), AZ80 (ST) and AZ91 (ST) were successfully bonded at 475 °C by spark plasma sintering, which is a promising new method in welding field. The formation of Ti3Al intermetallic compound was found to be an important factor in controlling the bonding strength and galvanic corrosion resistance of dissimilar materials. The maximum bonding strength and bonding efficiency at 193 MPa and 96% were obtained from Ti/AZ91 (ST), in which a thick and uniform nano-level Ti3Al layer was observed. This sample also shows the highest galvanic corrosion resistance with a measured galvanic width and depth of 281 and 19 µm, respectively. The corrosion resistance of the matrix on Mg alloy side was controlled by its Al content. AZ91 (ST) exhibited the highest corrosion resistance considered from its corrode surface after corrosion test in Kroll’s etchant. The effect of Al content in Mg alloy on bonding strength and corrosion behavior of Ti/Mg alloy (ST) dissimilar materials is discussed in this work. PMID:28773788

Corrosion Behavior and Strength of Dissimilar Bonding Material between Ti and Mg Alloys Fabricated by Spark Plasma Sintering

Directory of Open Access Journals (Sweden)

Patchara Pripanapong

2016-08-01

Full Text Available Ti and solution treated Mg alloys such as AZ31B (ST, AZ61 (ST, AZ80 (ST and AZ91 (ST were successfully bonded at 475 °C by spark plasma sintering, which is a promising new method in welding field. The formation of Ti3Al intermetallic compound was found to be an important factor in controlling the bonding strength and galvanic corrosion resistance of dissimilar materials. The maximum bonding strength and bonding efficiency at 193 MPa and 96% were obtained from Ti/AZ91 (ST, in which a thick and uniform nano-level Ti3Al layer was observed. This sample also shows the highest galvanic corrosion resistance with a measured galvanic width and depth of 281 and 19 µm, respectively. The corrosion resistance of the matrix on Mg alloy side was controlled by its Al content. AZ91 (ST exhibited the highest corrosion resistance considered from its corrode surface after corrosion test in Kroll’s etchant. The effect of Al content in Mg alloy on bonding strength and corrosion behavior of Ti/Mg alloy (ST dissimilar materials is discussed in this work.

Occupational exposure to electromagnetic fields in physiotherapy departments

International Nuclear Information System (INIS)

Macca, I.; Scapellato, M. L.; Carrieri, M.; Di Bisceglie, A. P.; Saia, B.; Bartolucci, G. B.

2008-01-01

To assess occupational exposure to electromagnetic fields, 11 microwave (MW), 4 short-wave diathermy and 15 magneto therapy devices were analysed in eight physiotherapy departments. Measurements taken at consoles and environmental mapping showed values above European Directive 2004/40/EC and ACGIH exposure limits at ∼50 cm from MW applicators (2.45 GHz) and above the Directive magnetic field limit near the diathermy unit (27.12 MHz). Levels in front of MW therapy applicators decreased rapidly with distance and reduction in power; this may not always occur in work environments where nearby metal structures (chairs, couches, etc.) may reflect or perturb electromagnetic fields. Large differences in stray field intensities were found for various MW applicators. Measurements of power density strength around MW electrodes confirmed radiation fields between 30 deg. and 150 deg., with a peak at 90 deg., in front of the cylindrical applicator and maximum values between 30 deg. and 150 deg. over the whole range of 180 deg. for the rectangular parabolic applicator. Our results reveal that although most areas show substantially low levels of occupational exposure to electromagnetic fields in physiotherapy units, certain cases of over-occupational exposure limits do exist. (authors)

Study on Droplet Size and Velocity Distributions of a Pressure Swirl Atomizer Based on the Maximum Entropy Formalism

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Kai Yan

2015-01-01

Full Text Available A predictive model for droplet size and velocity distributions of a pressure swirl atomizer has been proposed based on the maximum entropy formalism (MEF. The constraint conditions of the MEF model include the conservation laws of mass, momentum, and energy. The effects of liquid swirling strength, Weber number, gas-to-liquid axial velocity ratio and gas-to-liquid density ratio on the droplet size and velocity distributions of a pressure swirl atomizer are investigated. Results show that model based on maximum entropy formalism works well to predict droplet size and velocity distributions under different spray conditions. Liquid swirling strength, Weber number, gas-to-liquid axial velocity ratio and gas-to-liquid density ratio have different effects on droplet size and velocity distributions of a pressure swirl atomizer.

Strength and power of knee extensor muscles

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Knežević Olivera

2011-01-01

Full Text Available In the studies of human neuromuscular function, the function of leg muscles has been most often measured, particularly the function of the knee extensors. Therefore, this review will be focused on knee extensors, methods for assessment of its function, the interdependence of strength and power, relations that describe these two abilities and the influence of various factors on their production (resistance training, stretching, movement tasks, age, etc.. Given that it consists of four separate muscles, the variability of their anatomical characteristics affects their participation in strength and power production, depending on the type of movement and motion that is performed. Since KE is active in a variety of activities it must be able to generate great strength in a large and diverse range of muscle lengths and high shortening velocities, in respect to different patterns of strength production, and thus different generation capacities within the muscle (Blazevich et al., 2006. It has been speculated that KE exerts its Pmax at workloads close to subject's own body weight or lower (Rahmani et al., 2001, which is very close to the maximum dynamic output hypothesis (MDI of Jaric and Markovic (2009. Changes under the influence of resistance training or biological age are variously manifested in muscle's morphological, physiological and neural characteristics, and thus in strength and power. Understanding the issues related to strength and power as abilities of great importance for daily activities, is also important for sports and rehabilitation. Performances improvement in sports in which leg muscles strength and power are crucial, as well as recovery after the injuries, are largely dependent on the research results regarding KE function. Also, the appropriate strength balance between knee flexors and extensors is important for the knee joint stability, so that the presence of imbalance between these two muscle groups might be a risk factor for

EFFECTS OF CREATINE, GINSENG, AND ASTRAGALUS SUPPLEMENTATION ON STRENGTH, BODY COMPOSITION, MOOD, AND BLOOD LIPIDS DURING STRENGTH-TRAINING IN OLDER ADULTS

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Michael E. Rogers

2006-03-01

Full Text Available The effects of supplemental dietary creatine and a botanical extract consisting of ginseng and astragalus were evaluated in 44 adults aged 55-84 years participating in a 12-week strength-training program. Participants consumed creatine only (Cr, creatine plus botanical extract (CrBE, or placebo (PL, and performed bench press, lat pull down, biceps curl, leg press, knee extension, and knee flexion for 3 sets of 8-12 reps on 3 days per week for 12 weeks. The 1-repetition maximum for each exercise, body composition (full-body DEXA, blood lipids, and mood states were evaluated before and after the intervention. Training improved (p < 0.05 strength and lean mass for all groups, however greater gains were observed with Cr and CrBE compared with placebo (but no difference was found between Cr and CrBE. Only CrBE improved blood lipids and self-reported vigor, and the CrBE group lost significantly more body fat and gained more bench press strength than Cr. These results indicate that strength and lean mass gains achieved by older adults participating in a strength training program can be enhanced with creatine supplementation, and that ginseng and astragalus may provide additional health and psychological benefits. However, these herbs do not appear to have an additive effect on strength and lean mass gains during training

Effect of aluminum anodizing in phosphoric acid electrolyte on adhesion strength and thermal performance

Science.gov (United States)

Lee, Sulki; Kim, Donghyun; Kim, Yonghwan; Jung, Uoochang; Chung, Wonsub

2016-01-01

This study examined the adhesive bond strength and thermal performance of the anodized aluminum 6061 in phosphoric acid electrolyte to improve the adhesive bond strength and thermal performance for use in metal core printed circuit boards (MCPCB). The electrolyte temperature and applied voltage were altered to generate varied pore structures. The thickness, porosity and pore diameter of the anodized layer were measured. The pore morphologies were affected most by temperature, which was the driving force for ion transportation. The mechanism of adhesive bond was penetration of the epoxy into the pores. The optimal anodization conditions for maximum adhesive bond strength, 27 MPa, were 293 K and 100V. The maximum thermal conductivity of the epoxy-treated anodized layer was 1.6 W/m·K at 273 K. Compared with the epoxy-treated Al layer used for conventional MCPCBs, the epoxy-treated anodized layer showed advanced thermal performance due to a low difference of thermal resistance and high heat dissipation.

Maximum-Entropy Inference with a Programmable Annealer

Science.gov (United States)

Chancellor, Nicholas; Szoke, Szilard; Vinci, Walter; Aeppli, Gabriel; Warburton, Paul A.

2016-03-01

Optimisation problems typically involve finding the ground state (i.e. the minimum energy configuration) of a cost function with respect to many variables. If the variables are corrupted by noise then this maximises the likelihood that the solution is correct. The maximum entropy solution on the other hand takes the form of a Boltzmann distribution over the ground and excited states of the cost function to correct for noise. Here we use a programmable annealer for the information decoding problem which we simulate as a random Ising model in a field. We show experimentally that finite temperature maximum entropy decoding can give slightly better bit-error-rates than the maximum likelihood approach, confirming that useful information can be extracted from the excited states of the annealer. Furthermore we introduce a bit-by-bit analytical method which is agnostic to the specific application and use it to show that the annealer samples from a highly Boltzmann-like distribution. Machines of this kind are therefore candidates for use in a variety of machine learning applications which exploit maximum entropy inference, including language processing and image recognition.

Muscular strength is associated with self-esteem in college men but not women.

Science.gov (United States)

Ciccolo, Joseph T; SantaBarbara, Nicholas J; Dunsiger, Shira I; Busch, Andrew M; Bartholomew, John B

2016-12-01

Muscular strength is a well-known predictor of morbidity and mortality. Similarly, self-esteem is a predictor of health and well-being. The relationship between these two variables, however, is currently unknown. This study examined the cross-sectional relationship between maximal muscular strength (i.e. handgrip and one-repetition-maximum (1-RM) squat) and global self-esteem in 126 college students. Significant correlations were found between both measures of muscular strength and self-esteem. Further analyses revealed that these relationships were only significant for men. Based on these results, additional research is needed to further explore the relationship between muscular strength and self-esteem, especially in other demographic groups and longitudinally. © The Author(s) 2015.

The impact of obesity on skeletal muscle strength and structure through adolescence to old age.

Science.gov (United States)

Tomlinson, D J; Erskine, R M; Morse, C I; Winwood, K; Onambélé-Pearson, Gladys

2016-06-01

Obesity is associated with functional limitations in muscle performance and increased likelihood of developing a functional disability such as mobility, strength, postural and dynamic balance limitations. The consensus is that obese individuals, regardless of age, have a greater absolute maximum muscle strength compared to non-obese persons, suggesting that increased adiposity acts as a chronic overload stimulus on the antigravity muscles (e.g., quadriceps and calf), thus increasing muscle size and strength. However, when maximum muscular strength is normalised to body mass, obese individuals appear weaker. This relative weakness may be caused by reduced mobility, neural adaptations and changes in muscle morphology. Discrepancies in the literature remain for maximal strength normalised to muscle mass (muscle quality) and can potentially be explained through accounting for the measurement protocol contributing to muscle strength capacity that need to be explored in more depth such as antagonist muscle co-activation, muscle architecture, a criterion valid measurement of muscle size and an accurate measurement of physical activity levels. Current evidence demonstrating the effect of obesity on muscle quality is limited. These factors not being recorded in some of the existing literature suggest a potential underestimation of muscle force either in terms of absolute force production or relative to muscle mass; thus the true effect of obesity upon skeletal muscle size, structure and function, including any interactions with ageing effects, remains to be elucidated.

Automatic maximum entropy spectral reconstruction in NMR

International Nuclear Information System (INIS)

Mobli, Mehdi; Maciejewski, Mark W.; Gryk, Michael R.; Hoch, Jeffrey C.

2007-01-01

Developments in superconducting magnets, cryogenic probes, isotope labeling strategies, and sophisticated pulse sequences together have enabled the application, in principle, of high-resolution NMR spectroscopy to biomolecular systems approaching 1 megadalton. In practice, however, conventional approaches to NMR that utilize the fast Fourier transform, which require data collected at uniform time intervals, result in prohibitively lengthy data collection times in order to achieve the full resolution afforded by high field magnets. A variety of approaches that involve nonuniform sampling have been proposed, each utilizing a non-Fourier method of spectrum analysis. A very general non-Fourier method that is capable of utilizing data collected using any of the proposed nonuniform sampling strategies is maximum entropy reconstruction. A limiting factor in the adoption of maximum entropy reconstruction in NMR has been the need to specify non-intuitive parameters. Here we describe a fully automated system for maximum entropy reconstruction that requires no user-specified parameters. A web-accessible script generator provides the user interface to the system

Electric and magnetic field testing in vicinity of 110/x kV substations

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Grbić Maja

2016-01-01

Full Text Available The levels of non-ionizing radiation (electric and magnetic fields at power frequency, which occur near 110/x kV substations are analyzed in this paper. The results of electric field strength and magnetic flux density measurements in the vicinity of three typical substations of the aforementioned voltage level are shown. With the purpose of estimating the exposure of the population to these fields, the obtained results were compared to the reference maximum levels set for increased sensitivity areas, which amount to 2 kV/m for electric field and 40 μT for magnetic flux density. The objective of the conducted analysis is to reach general conclusions on the levels of electric and magnetic fields, which may occur in the vicinity of the substations mentioned above, and evaluate their compliance with the national regulations on the population protection from non-ionizing radiation.

Relationship Between Selected Strength and Power Assessments to Peak and Average Velocity of the Drive Block in Offensive Line Play.

Science.gov (United States)

Jacobson, Bert H; Conchola, Eric C; Smith, Doug B; Akehi, Kazuma; Glass, Rob G

2016-08-01

Jacobson, BH, Conchola, EC, Smith, DB, Akehi, K, and Glass, RG. Relationship between selected strength and power assessments to peak and average velocity of the drive block in offensive line play. J Strength Cond Res 30(8): 2202-2205, 2016-Typical strength training for football includes the squat and power clean (PC) and routinely measured variables include 1 repetition maximum (1RM) squat and 1RM PC along with the vertical jump (VJ) for power. However, little research exists regarding the association between the strength exercises and velocity of an actual on-the-field performance. The purpose of this study was to investigate the relationship of peak velocity (PV) and average velocity (AV) of the offensive line drive block to 1RM squat, 1RM PC, the VJ, body mass (BM), and body composition. One repetition maximum assessments for the squat and PC were recorded along with VJ height, BM, and percent body fat. These data were correlated with PV and AV while performing the drive block. Peal velocity and AV were assessed using a Tendo Power and Speed Analyzer as the linemen fired, from a 3-point stance into a stationary blocking dummy. Pearson product analysis yielded significant (p ≤ 0.05) correlations between PV and AV and the VJ, the squat, and the PC. A significant inverse association was found for both PV and AV and body fat. These data help to confirm that the typical exercises recommended for American football linemen is positively associated with both PV and AV needed for the drive block effectiveness. It is recommended that these exercises remain the focus of a weight room protocol and that ancillary exercises be built around these exercises. Additionally, efforts to reduce body fat are recommended.

Effect of pulsed electric fields (PEF) on accumulation of selenium and zinc ions in Saccharomyces cerevisiae cells.

Science.gov (United States)

Pankiewicz, Urszula; Sujka, Monika; Kowalski, Radosław; Mazurek, Artur; Włodarczyk-Stasiak, Marzena; Jamroz, Jerzy

2017-04-15

The cultures of Saccharomyces cerevisiae were treated with pulsed electric fields (PEF) in order to obtain a maximum accumulation of selenium and zinc ions (simultaneously) in the biomass. The following concentrations: 100μgSe/ml and 150μgZn/ml medium were assumed to be optimal for the maximum accumulation of these ions, that is 43.07mg/gd.m. for selenium and 14.48mg/gd.m. for zinc, in the cultures treated with PEF. At optimal PEF parameters: electric field strength of 3kV/cm and pulse width of 10μs after the treatment of 20-h culture for 10min, the maximum accumulation of both ions in the yeast cells was observed. Application of PEF caused the increase of ions accumulation by 65% for selenium and 100% for zinc. Optimization of PEF parameters led to the further rise in the both ions accumulation resulting in over 2-fold and 2.5-fold higher concentration of selenium and zinc. Copyright © 2016 Elsevier Ltd. All rights reserved.

An overview of strength training injuries: acute and chronic.

Science.gov (United States)

Lavallee, Mark E; Balam, Tucker

2010-01-01

This article introduces the history of strength training, explains the many different styles of strength training, and discusses common injuries specific to each style. Strength training is broken down into five disciplines: basic strength or resistance training, bodybuilding, power lifting, style-dependant strength sports (e.g., strongman competitions, Highland games, field events such as shot put, discus, hammer throw, and javelin), and Olympic-style weightlifting. Each style has its own principal injuries, both acute and chronic, related to the individual technique. Acute injuries should be further categorized as emergent or nonemergent. Specific age-related populations (i.e., the very young and the aging athlete) carry additional considerations.

Isokinetic and isometric muscle strength combined with transcutaneous electrical muscle stimulation in primary fibromyalgia syndrome

DEFF Research Database (Denmark)

Jacobsen, Søren; Wildschiødtz, Gordon; Danneskiold-Samsøe, B

1991-01-01

Twenty women with primary fibromyalgia syndrome and 20 age matched healthy women were investigated. The subjects performed maximum voluntary isokinetic contractions of the right quadriceps in an isokinetic dynamometer. Maximum voluntary isometric contractions of the right quadriceps were performed...... of superimposed twitches was 65% in the patient group and 15% in the control group (p = 0.003). Patients with primary fibromyalgia have a lower maximum voluntary muscle strength than expected. The increased presence of superimposed electrically elicited twitches during maximum voluntary contraction indicates...... submaximal force application in primary fibromyalgia syndrome....

Efficiency of autonomous soft nanomachines at maximum power.

Science.gov (United States)

Seifert, Udo

2011-01-14

We consider nanosized artificial or biological machines working in steady state enforced by imposing nonequilibrium concentrations of solutes or by applying external forces, torques, or electric fields. For unicyclic and strongly coupled multicyclic machines, efficiency at maximum power is not bounded by the linear response value 1/2. For strong driving, it can even approach the thermodynamic limit 1. Quite generally, such machines fall into three different classes characterized, respectively, as "strong and efficient," "strong and inefficient," and "balanced." For weakly coupled multicyclic machines, efficiency at maximum power has lost any universality even in the linear response regime.

The Location-Scale Mixture Exponential Power Distribution: A Bayesian and Maximum Likelihood Approach

OpenAIRE

Rahnamaei, Z.; Nematollahi, N.; Farnoosh, R.

2012-01-01

We introduce an alternative skew-slash distribution by using the scale mixture of the exponential power distribution. We derive the properties of this distribution and estimate its parameter by Maximum Likelihood and Bayesian methods. By a simulation study we compute the mentioned estimators and their mean square errors, and we provide an example on real data to demonstrate the modeling strength of the new distribution.

Numerical simulation of thermomagnetic convection of cold water near its density maximum in a square enclosure under a magnetic quadrupole field

Energy Technology Data Exchange (ETDEWEB)

Shi, Er; Sun, Xiaoqin; He, Yecong; Jiang, Changwei, E-mail: cw_jiang@163.com [School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410114 (China)

2017-06-15

Natural convection of cold water near its density maximum in a square enclosure is studied numerically under the influence of a magnetic quadrupole field without gravity. A generalized model which includes a non-Boussinesq parabolic density–temperature relationship is established. The governing equations in primitive variables are discretized using the finite-volume method and solved using the SIMPLE algorithm. The effects of magnetic force number, Rayleigh number and density inversion parameter on flow and heat transfer characteristics are analyzed. The results show that the primary flow pattern depends mainly on the density inversion parameter. Multi-cellular flow structures are observed for certain ranges of density inversion parameter independent of the value of Rayleigh number and magnetic force number. The heat transfer changes non-monotonically under combined actions of the quadrupole magnetic field and density inversion. (paper)

Magnetic and Engineering Analysis of an Adjustable Strength Permanent Magnet Quadrupole

CERN Document Server

Gottschalk, Stephen C

2005-01-01

Magnetic and engineering analyses used in the design of an adjustable strength permanent magnet quadrupole will be reported. The quadrupole designed has a pole length of 42cm, aperture diameter 13mm, peak pole tip strength 1.03Tesla and peak integrated gradient * length (GL) of 68.7Tesla. Analyses of magnetic strength, field quality, magnetic centerline, temperature compensation and dynamic eddy currents induced during field adjustments will be presented. Magnet sorting strategies, pole positioning sensitivity, component forces, and other sensitivity analyses will be presented. Engineering analyses of stress, deflection and thermal effects as well as compensation strategies will also be shown.

INVESTIGATION OF THE EFFECTS OF DIFFERENT EDGE JOINT ELEMENTS ON DIAGONAL TENSILE STRENGTH IN FURNITURE EDGE JOINTS

Directory of Open Access Journals (Sweden)

Arif GÜRAY

2002-01-01

Full Text Available In this work, the diagonal tensile strength of furniture edge joints such as wooden dowel, minifix, and alyan screw was investigated in panel-constructed boards for Suntalam and MDF Lam. For this purpose, a diagonal tensile strength test was applied to the 72 samples. According to the results, the maximum diagonal tensile strength was found to be in MDF Lam boards that jointed with alyan screw.

Modelling information flow along the human connectome using maximum flow.

Science.gov (United States)

Lyoo, Youngwook; Kim, Jieun E; Yoon, Sujung

2018-01-01

The human connectome is a complex network that transmits information between interlinked brain regions. Using graph theory, previously well-known network measures of integration between brain regions have been constructed under the key assumption that information flows strictly along the shortest paths possible between two nodes. However, it is now apparent that information does flow through non-shortest paths in many real-world networks such as cellular networks, social networks, and the internet. In the current hypothesis, we present a novel framework using the maximum flow to quantify information flow along all possible paths within the brain, so as to implement an analogy to network traffic. We hypothesize that the connection strengths of brain networks represent a limit on the amount of information that can flow through the connections per unit of time. This allows us to compute the maximum amount of information flow between two brain regions along all possible paths. Using this novel framework of maximum flow, previous network topological measures are expanded to account for information flow through non-shortest paths. The most important advantage of the current approach using maximum flow is that it can integrate the weighted connectivity data in a way that better reflects the real information flow of the brain network. The current framework and its concept regarding maximum flow provides insight on how network structure shapes information flow in contrast to graph theory, and suggests future applications such as investigating structural and functional connectomes at a neuronal level. Copyright © 2017 Elsevier Ltd. All rights reserved.

Parametric characteristics of a solar thermophotovoltaic system at the maximum efficiency

International Nuclear Information System (INIS)

Liao, Tianjun; Chen, Xiaohang; Yang, Zhimin; Lin, Bihong; Chen, Jincan

2016-01-01

Graphical abstract: A model of the far-field TPVC driven by solar energy, which consists of an optical concentrator, an absorber, an emitter, and a PV cell and is simply referred as to the far-field STPVS. - Highlights: • A model of the far-field solar thermophotovoltaic system (STPVS) is established. • External and internal irreversible losses are considered. • The maximum efficiency of the STPVS is calculated. • Optimal values of key parameters at the maximum efficiency are determined. • Effects of the concentrator factor on the performance of the system are discussed. - Abstract: A model of the solar thermophotovoltaic system (STPVS) consisting of an optical concentrator, a thermal absorber, an emitter, and a photovoltaic (PV) cell is proposed, where the far-field thermal emission between the emitter and the PV cell, the radiation losses from the absorber and emitter to the environment, the reflected loss from the absorber, and the finite-rate heat exchange between the PV cell and the environment are taken into account. Analytical expressions for the power output of and overall efficiency of the STPVS are derived. By solving thermal equilibrium equations, the operating temperatures of the emitter and PV cell are determined and the maximum efficiency of the system is calculated numerically for given values of the output voltage of the PV cell and the ratio of the front surface area of the absorber to that of the emitter. For different bandgaps, the maximum efficiencies of the system are calculated and the corresponding optimum values of several operating parameters are obtained. The effects of the concentrator factor on the optimum performance of the system are also discussed.

Radial distributions of magnetic field strength in the solar corona as derived from data on fast halo CMEs

Directory of Open Access Journals (Sweden)

Fainshtein V.G.

2018-03-01

Full Text Available In recent years, information about the distance between the body of rapid coronal mass ejection (CME and the associated shock wave has been used to measure the magnetic field in the solar corona. In all cases, this technique allows us to find coronal magnetic field radial profiles B(R applied to the directions almost perpendicular to the line of sight. We have determined radial distributions of magnetic field strength along the directions close to the Sun–Earth axis. For this purpose, using the “ice-cream cone” model and SOHO/LASCO data, we found 3D characteristics for fast halo coronal mass ejections (HCMEs and for HCME-related shocks. With these data we managed to obtain the B(R distributions as far as ≈43 solar radii from the Sun's center, which is approximately twice as far as those in other studies based on LASCO data. We have concluded that to improve the accuracy of this method for finding the coronal magnetic field we should develop a technique for detecting CME parts moving in the slow and fast solar wind. We propose a technique for selecting CMEs whose central (paraxial part actually moves in the slow wind.

Flow Strength of Shocked Aluminum in the Solid-Liquid Mixed Phase Region

Science.gov (United States)

Reinhart, William

2011-06-01

Shock waves have been used to determine material properties under high shock stresses and very-high loading rates. The determination of mechanical properties such as compressive strength under shock compression has proven to be difficult and estimates of strength have been limited to approximately 100 GPa or less in aluminum. The term ``strength'' has been used in different ways. For a Von-Mises solid, the yield strength is equal to twice the shear strength of the material and represents the maximum shear stress that can be supported before yield. Many of these concepts have been applied to materials that undergo high strain-rate dynamic deformation, as in uni-axial strain shock experiments. In shock experiments, it has been observed that the shear stress in the shocked state is not equal to the shear strength, as evidenced by elastic recompressions in reshock experiments. This has led to an assumption that there is a yield surface with maximum (loading)and minimum (unloading), shear strength yet the actual shear stress lies somewhere between these values. This work provides the first simultaneous measurements of unloading velocity and flow strength for transition of solid aluminum to the liquid phase. The investigation describes the flow strength observed in 1100 (pure), 6061-T6, and 2024 aluminum in the solid-liquid mixed phase region. Reloading and unloading techniques were utilized to provide independent data on the two unknowns (τc and τo) , so that the actual critical shear strength and the shear stress at the shock state could be estimated. Three different observations indicate a change in material response for stresses of 100 to 160 GPa; 1) release wave speed (reloading where applicable) measurements, 2) yield strength measurements, and 3) estimates of Poisson's ratio, all of which provide information on the melt process including internal consistency and/or non-equilibrium and rate-dependent melt behavior. The study investigates the strength properties

The effects of long term strength training on hemodynamic parameters and resistin level in postmenopausal women

Directory of Open Access Journals (Sweden)

Cecília Tardivo Marin

2014-05-01

Full Text Available Objective: Investigate the influence of strength training (ST on serum resistin levels and blood pressure of postmenopausal women. Methods: Longitudinal study conducted at the Federal University of São Carlos with twenty-three sedentary postmenopausal women. The ST lasted 13 months (Dec./2008 to Jan./2010 and consisted of two weekly sessions with three sets of 8-12 maximum repetitions and one exercise for each main muscle group. Maximum muscular strength was tested in the following exercises: bench press, 45° leg press, and standing arm curl. Serum resistin level was determined using the ELISA method. ANOVA (with repeated measures was used for the comparisons between periods Pre-, 6 months and 13 months (p < 0.05; Pearson’s correlation test was used to evaluate the correlations between resistin × blood pressure, resistin × muscle strength and strength × blood pressure. Results: Women presented the following anthropometric profile: 61.33±3.8 years; height 148.5±32.7 cm; body mass 67.56±10.85 kg. The ST decreased resistin levels (30272.4 ± 8100.1 to 16350.6 ± 2404.6 pg/mL and systolic blood pressure (120.5 ± 11.8 to 115.8 ± 1.6 mmHg, and increased muscular strength in the leg press 45o (172.3 ± 27.3 to 348.6 ± 40.8kg, bench press (31.9 ± 4.1 to 41.8 ± 5.6 kg and arm curl (21.0 ± 2.4 to 26.5 ± 2.9 kg after 13 months (p < 0.05. Conclusion: The results of this study revealed that long-term ST increases maximum muscular strength, decreases systolic blood pressure and serum resistin levels, which are beneficial physiological alterations that reduce the risk for cardiovascular diseases in postmenopausal women. doi:10.5020/18061230.2013.p325

Sensitivity study of buckling strength for cylindrical shells

Energy Technology Data Exchange (ETDEWEB)

Kato, Hideo; Sasaki, Toru [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)

2001-09-01

Aiming at making clear buckling behavior of cylindrical shells under earthquake loadings, we investigated procedure of recent elastic-plastic buckling analysis by finite element method (FEM). Thereby it is confirmed that the buckling strength becomes as well as that of a shell with a cross section of a perfect cylinder, if we apply the first buckling eigenvector to imperfection mode and assume the maximum imperfection amplitude to be 1% of the wall thickness. And then, by carrying out sensitivity study of buckling with geometrical parameters, such as length (L), radius (R), wall thickness (t), and load parameter, such as pressure, we obtained several characteristics about buckling strength and buckling mode for cylindrical shells. From the geometrical parameter analysis, it is seen that bending buckling occurs for small R/t (thick wall) and elastic buckling occurs for 2{<=}L/R{<=}4 and R/t{>=}400. And from the load parameter analysis, it is shown that hoop stress caused by the inner pressure increases shear buckling strength but decreases bending buckling strength, and hoop stress by hydrostatic pressure changes buckling mode and generates local deformation. (author)

Functional Capacity in Adults With Cerebral Palsy: Lower Limb Muscle Strength Matters.

Science.gov (United States)

Gillett, Jarred G; Lichtwark, Glen A; Boyd, Roslyn N; Barber, Lee A

2018-05-01

To investigate the relation between lower limb muscle strength, passive muscle properties, and functional capacity outcomes in adults with cerebral palsy (CP). Cross-sectional study. Tertiary institution biomechanics laboratory. Adults with spastic-type CP (N=33; mean age, 25y; range, 15-51y; mean body mass, 70.15±21.35kg) who were either Gross Motor Function Classification System (GMFCS) level I (n=20) or level II (n=13). Not applicable. Six-minute walk test (6MWT) distance (m), lateral step-up (LSU) test performance (total repetitions), timed up-stairs (TUS) performance (s), maximum voluntary isometric strength of plantar flexors (PF) and dorsiflexors (DF) (Nm.kg -1 ), and passive ankle joint and muscle stiffness. Maximum isometric PF strength independently explained 61% of variance in 6MWT performance, 57% of variance in LSU test performance, and 50% of variance in TUS test performance. GMFCS level was significantly and independently related to all 3 functional capacity outcomes, and age was retained as a significant independent predictor of LSU and TUS test performance. Passive medial gastrocnemius muscle fascicle stiffness and ankle joint stiffness were not significantly related to functional capacity measures in any of the multiple regression models. Low isometric PF strength was the most important independent variable related to distance walked on the 6MWT, fewer repetitions on the LSU test, and slower TUS test performance. These findings suggest lower isometric muscle strength contributes to the decline in functional capacity in adults with CP. Copyright © 2018 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Maintained ship hull girder ultimate strength reliability considering corrosion and fatigue

DEFF Research Database (Denmark)

Hu, Yong; Cui, W.; Pedersen, Preben Terndrup

2004-01-01

The prupose of this paper is to propose a methodology to assess the time-variant ultimate strength of ship hull girder under the degradations of corrosion and fatigue. The effects of fatigue cracks on the tensile and compressive residual ultimate strength of stiffened panels and unstiffened plates......, webs and flanges, respectively. The effects of inspections and repair are taken into account. A minimum net thickness rule is used to determine repair policies. A procedure is proposed to determine the maximum allowable corrosion thickness of different parts of the hull cross section. The procedure...

Effects of augmented trunk stabilization with external compression support on shoulder and scapular muscle activity and maximum strength during isometric shoulder abduction.

Science.gov (United States)

Jang, Hyun-jeong; Kim, Suhn-yeop; Oh, Duck-won

2015-04-01

The aim of the present study was to investigate the effects of augmented trunk stabilization with external compression support (ECS) on the electromyography (EMG) activity of shoulder and scapular muscles and shoulder abductor strength during isometric shoulder abduction. Twenty-six women volunteered for the study. Surface EMG was used to monitor the activity of the upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), and middle deltoid (MD), and shoulder abductor strength was measured using a dynamometer during three experimental conditions: (1) no external support (condition-1), (2) pelvic support (condition-2), and (3) pelvic and thoracic supports (condition-3) in an active therapeutic movement device. EMG activities were significantly lower for UT and higher for MD during condition 3 than during condition 1 (p strength was significantly higher during condition 3 than during condition 1 (p isometric shoulder abduction and increasing shoulder abductor strength. Copyright © 2014 Elsevier Ltd. All rights reserved.

Objective Bayesianism and the Maximum Entropy Principle

Directory of Open Access Journals (Sweden)

Jon Williamson

2013-09-01

Full Text Available Objective Bayesian epistemology invokes three norms: the strengths of our beliefs should be probabilities; they should be calibrated to our evidence of physical probabilities; and they should otherwise equivocate sufficiently between the basic propositions that we can express. The three norms are sometimes explicated by appealing to the maximum entropy principle, which says that a belief function should be a probability function, from all those that are calibrated to evidence, that has maximum entropy. However, the three norms of objective Bayesianism are usually justified in different ways. In this paper, we show that the three norms can all be subsumed under a single justification in terms of minimising worst-case expected loss. This, in turn, is equivalent to maximising a generalised notion of entropy. We suggest that requiring language invariance, in addition to minimising worst-case expected loss, motivates maximisation of standard entropy as opposed to maximisation of other instances of generalised entropy. Our argument also provides a qualified justification for updating degrees of belief by Bayesian conditionalisation. However, conditional probabilities play a less central part in the objective Bayesian account than they do under the subjective view of Bayesianism, leading to a reduced role for Bayes’ Theorem.

Information Entropy Production of Maximum Entropy Markov Chains from Spike Trains

Science.gov (United States)

Cofré, Rodrigo; Maldonado, Cesar

2018-01-01

We consider the maximum entropy Markov chain inference approach to characterize the collective statistics of neuronal spike trains, focusing on the statistical properties of the inferred model. We review large deviations techniques useful in this context to describe properties of accuracy and convergence in terms of sampling size. We use these results to study the statistical fluctuation of correlations, distinguishability and irreversibility of maximum entropy Markov chains. We illustrate these applications using simple examples where the large deviation rate function is explicitly obtained for maximum entropy models of relevance in this field.

Validity of maximal isometric knee extension strength measurements obtained via belt-stabilized hand-held dynamometry in healthy adults.

Science.gov (United States)

Ushiyama, Naoko; Kurobe, Yasushi; Momose, Kimito

2017-11-01

[Purpose] To determine the validity of knee extension muscle strength measurements using belt-stabilized hand-held dynamometry with and without body stabilization compared with the gold standard isokinetic dynamometry in healthy adults. [Subjects and Methods] Twenty-nine healthy adults (mean age, 21.3 years) were included. Study parameters involved right side measurements of maximal isometric knee extension strength obtained using belt-stabilized hand-held dynamometry with and without body stabilization and the gold standard. Measurements were performed in all subjects. [Results] A moderate correlation and fixed bias were found between measurements obtained using belt-stabilized hand-held dynamometry with body stabilization and the gold standard. No significant correlation and proportional bias were found between measurements obtained using belt-stabilized hand-held dynamometry without body stabilization and the gold standard. The strength identified using belt-stabilized hand-held dynamometry with body stabilization may not be commensurate with the maximum strength individuals can generate; however, it reflects such strength. In contrast, the strength identified using belt-stabilized hand-held dynamometry without body stabilization does not reflect the maximum strength. Therefore, a chair should be used to stabilize the body when performing measurements of maximal isometric knee extension strength using belt-stabilized hand-held dynamometry in healthy adults. [Conclusion] Belt-stabilized hand-held dynamometry with body stabilization is more convenient than the gold standard in clinical settings.

Fracture Strength of Fused Silica From Photonic Signatures Around Collision Sites

Science.gov (United States)

Yost, William T.; Cramer, K Elliott

2015-01-01

Impact sites in glass affect its fracture strength. An analytical model that predicts fracture strength from grey-field polariscope (GFP) readings (photoelastic retardations) has been developed and reported in the literature. The model is suggestive that stress fields, resulting from impact damage, destablizes sites within the glass, which lead to pathways that cause strength degradation. Using data collected from fused silica specimens fabricated from outer window panes that were designed for the space shuttle, the model was tested against four categories of inflicted damage. The damage sites were cored from the window carcasses, examined with the GFP and broken using the ASTM Standard C1499-09 to measure the fracture strength. A correlation is made between the fracture strength and the photoelastic retardation measured at the damage site in each specimen. A least-squares fit is calculated. The results are compared with the predictions from the model. A plausible single-sided NDE damage site inspection method (a version of which is planned for glass inspection in the Orion Project) that relates photoelastic retardation in glass components to its fracture strength is presented.

Walking performance and muscle strength in the later stage poststroke: a nonlinear relationship.

Science.gov (United States)

Carvalho, Cristiane; Sunnerhagen, Katharina S; Willén, Carin

2013-05-01

To evaluate the relation between muscle strength in the lower extremities and walking performance (speed and distance) in subjects in the later stage poststroke and to compare this with normative data. A cross-sectional observational study. University hospital department. Subjects poststroke (n=41; 31 men, 10 women) with a mean age of 59±5.8 years and a time from stroke onset of 52±36 months were evaluated. An urban sample (n=144) of 40- to 79-year-olds (69 men, 75 women) formed the healthy reference group. Not applicable. Muscle strength in the lower extremities was measured with an isokinetic dynamometer and combined into a strength index. Values for the 30-meter walk test for self-selected and maximum speed and the 6-minute walk test were measured. A nonlinear regression model was used. The average strength index was 730±309 in the subjects after stroke compared with 1112±362 in the healthy group. A nonlinear relation between walking performance and muscle strength was evident. The model explained 37% of the variance in self-selected speed in the stroke group and 20% in the healthy group, and 63% and 38%, respectively, in the maximum walking speed. For the 6-minute walk test, the model explained 44% of the variance in the stroke group. Subjects in the later stage poststroke were weaker than the healthy reference group, and their weakness was associated with walking performance. At the same strength index, subjects walked at lower speeds and shorter distances after stroke, indicating that there are multiple impairments that affect walking ability. Treatments focused on increasing muscle strength thus continue to hold promise. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Quantitative susceptibility mapping across two clinical field strengths: Contrast-to-noise ratio enhancement at 1.5T.

Science.gov (United States)

Ippoliti, Matteo; Adams, Lisa C; Winfried, Brenner; Hamm, Bernd; Spincemaille, Pascal; Wang, Yi; Makowski, Marcus R

2018-04-16

Quantitative susceptibility mapping (QSM) is an MRI postprocessing technique that allows quantification of the spatial distribution of tissue magnetic susceptibility in vivo. Contributing sources include iron, blood products, calcium, myelin, and lipid content. To evaluate the reproducibility and consistency of QSM across clinical field strengths of 1.5T and 3T and to optimize the contrast-to-noise ratio (CNR) at 1.5T through bandwidth tuning. Prospective. Sixteen healthy volunteers (10 men, 6 women; age range 24-37; mean age 27.8 ± 3.2 years). 1.5T and 3T systems from the same vendor. Four spoiled gradient echo (SPGR) sequences were designed with different acquisition bandwidths. QSM reconstruction was achieved through a nonlinear morphology-enabled dipole inversion (MEDI) algorithm employing L1 regularization. CNR was calculated in seven regions of interest (ROIs), while reproducibility and consistency of QSM measurements were evaluated through voxel-based and region-specific linear correlation analyses and Bland-Altman plots. Interclass correlation, Wilcoxon rank sum test, linear regression analysis, Bland-Altman analysis, Welch's t-test. CNR analysis showed a statistically significant (P limits of agreement from -18.7 to 25.8 ppb) in the ROI-based analysis, while the correlation was found to be good for the voxel-based analysis of averaged maps (R ≥ 0.90, widest limits of agreement from -9.3 to 9.1 ppb). CNR of QSM images reconstructed from 1.5T acquisitions can be enhanced through bandwidth tuning. MEDI-based QSM reconstruction demonstrated to be reproducible and consistent both across field strengths (1.5T and 3T) and bandwidth variation. 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.