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The SACLA (SPring-8 Angstrom compact laser) was designed to significantly downsize the SASE (self-amplified spontaneous emission) type XFEL (X-ray free-electron laser), in order to generate coherent light in the wavelength region of 0.1 nm by adopting an in-vacuum undulator that can shorten the magnetic field period length. In addition, a SASE XFEL facility with a total length of 700 m has become a reality by using a C-band RF accelerating tube that enables a high acceleration gradient. Although progress was initially slow, the small-scale, low-cost SACLA was smoothly constructed, and it became the second light source to lase in the 0.1 nm wavelength region, following the LCLS (linac coherent light source) in the United States. In this paper, we look back on the history leading up to SACLA. and describe the SCSS (SPring-8 compact SASE source) project as a preparatory stage and a part of the construction/commissioning of SACLA. Since March 2012, SACLA has been operating as a shared user facility. Just a few of the upgrade activities of the facility and advanced research conducted are introduced. Finally, we will discuss the future development of the SPring-8 site, which has co-located the third-generation synchrotron radiation facility SPring-8 and the X-ray free-electron laser facility SACLA. [ABSTRACT FROM AUTHOR]

Magnetic resonance (MR) imaging uses magnetic fields and radio waves to generate an image of the body. Though it is considered safe because it does not emit ionizing radiation, the strong magnetic fields produced by the MR scanner require unique safety considerations. The American College of Radiology (ACR) has provided guidance documents on MR safety since 2002 and recently updated and reorganized these documents into the ACR Manual on MR Safety. This article discusses the physics of MR imaging, the evolution of MR safety recommendations, and MR safety procedures. [ABSTRACT FROM AUTHOR]

The field dependence of magnetization of a silicon nanosandwich measured at room temperature in weak magnetic fields manifests de Haas–van Alphen oscillations, the behavior of which is explained under the condition of the dependence of the effective carrier mass on the external magnetic field. [ABSTRACT FROM AUTHOR]

In this study, two types of smart rocks are proposed, characterized, and validated for bridge scour monitoring, including the arbitrary oriented system smart rock and the automatically pointing to south system smart rock. Effect of the smart rocks on the geomagnetic field is numerically studied, and algorithms to localize the position of the smart rocks are developed. Field validation tests are conducted at an open area in Rolla, MO, USA. Results show that the magnetic intensity decreases in cubic function with a distance away from the smart rock. The algorithm can effectively localize the position of smart rocks during validation tests. The effective monitoring range of the two smart rocks is dependent on the flux (or size) of the magnet used to fabricate the smart rocks, the accuracy of the magnetometer, the direction of smart rocks, as well as the intensity and variation of the ambient magnetic field. Compared with arbitrary oriented system smart rock, less measurement points are needed to localize the automatically pointing to south system smart rock. [ABSTRACT FROM AUTHOR]

In DC systems, DC resistive type superconducting fault current limiters (R-SFCLs) can respond within a few hundred milliseconds and limit the fault current to a very low level to protect the power equipment in DC systems. The main part of R-SFCLs are superconducting tapes. When short-circuit faults occur in the system, the superconducting tapes will quench and become a large quenched resistor to limit the fault current. The surrounding magnetic fields and the magnetic fields caused by the superconducting tapes itself influence the quench characteristics of the superconducting tapes of R-SFCLs. Thus, the current limiting characteristics of R-SFCLs will also be affected. Until present, very few studies have investigated the effects of magnetic fields on quench characteristics of superconducting tapes for DC R-SFCL. The objective of this paper is to obtain the effects of magnetic fields on quench characteristics of superconducting tapes for DC R-SFCL. Two different kinds of YBa2Cu3O7-δ (YBCO) tapes are studied under a permanent magnetic field of 0, 42.4, 75.9, 122.9 mT, respectively. One is from Shanghai Superconductor Technology Co., Ltd., Shanghai, China, type ST-12-L (named SC_SH) and the other is from American Superconductor Inc. Boston, MA, USA, type 8602 (named SC_8602). The research results show that the magnetic fields influence both the amplitude and the rising rate of the quenched resistance of an SC_SH tape. Under the same magnetic field, both the speed of quenching and the quenching resistance of SC_SH tape are larger than them of SC_8602 when the prospective current exceeds 800 A. Thus SC_SH tape can limit the fault current faster and to a lower level. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objectives: There are significant numbers of military and law enforcement bullets containing ferromagnetic materials. This study aimed to assess the magnetic field interactions for a representative sample of military and law enforcement ballistic objects at 1.5 and 3 tesla (T) to create a magnetic resonance imaging (MRI) compatibility database.Methods: Twenty-nine different bullets underwent MRI evaluation. The deflection angle method and a qualitative torque scale were used. The samples were representative of those commonly used in the North Atlantic Treaty Organization (NATO) military forces (e.g., 5.56 mm NATO), law enforcement agencies (e.g., 9 mm Parabellum), and encountered in war injuries and crime-related trauma (e.g., 7.62 mm Kalashnikov).Results: At all static magnetic field strengths, all non-nickel- and nonsteel-containing bullets exhibited no movement (deflection angle = 0°; torque = 0), whereas eight bullets containing steel core, steel jacket, or nickel jacket exhibited substantial magnetic field interactions over and above what might be regarded as safe in vivo (deflection angle = 90°; torque = 4+).Conclusion: Military and law enforcement non-nickel- or nonsteel-containing bullets appear to be safe for patients in MRI system at 1.5 and 3 T. On the other hand, nickel- and steel-containing bullets exhibit movements that are considered potentially unsafe for patients in an MRI environment. [ABSTRACT FROM AUTHOR]

Study to Obliterate Persistent Ventricular Tachycardia Introduction Catheter ablation is an effective treatment of scar-related ventricular tachycardia (VT), but the overall complexity of the procedure has precluded its widespread use. Remote magnetic navigation (RMN) has been shown to facilitate cardiac mapping and ablation of VT in a retrospective series. STOP-VT is the first multicenter, prospective, single-arm and single-procedure study evaluating RMN-based mapping and ablation of post-infarction VT. Methods Patients with documented VT and prior MI, in whom an ICD was implanted either for primary or secondary prevention, were recruited from four EU and US centers. Either a transseptal (48 patients) or transaortic (5 patients) approach was employed to gain access for ventricular endocardial mapping/ablation during VT (entrainment mapping, activation mapping) and/or substrate mapping in sinus rhythm (elimination of fractionated/late potentials, variable extent of substrate modification) with RMN and irrigated RF ablation. The primary endpoints were as follows: (i) non-inducibility of the target VT or any other sustained VT; (ii) elimination of sustained VT/VF during ICD follow-up of up to 12 months. Results The cohort included 53 consecutive patients (median age 67 years, 49 men, median LVEF 31%). One hemodynamically unstable patient was excluded at the onset of mapping. Inducibility of sustained VT was achieved an average of 2.2 times per patient (1-8), with mean tachycardia cycle length (TCL) 374 milliseconds (179-510). Mean total procedure and fluoroscopy times were 223 minutes and 8.7 minutes, respectively; mean cumulative fluoroscopy time during mapping and ablation was 0.95 minutes; maximum power averaged 42.3 W with nominal saline 30 cc/min irrigation; mean cumulative RF time was 38 minutes. Non-inducibility of the target VT was achieved in 49/52 patients (94.2%) and non-inducibility of any VT was achieved in 38/52 patients (73.1%). A combination of RMN and manual ablation was performed in two patients, rendering one non-inducible. During the 12-month ICD follow-up period, freedom from any sustained VT/VF was observed in 30 patients (62%), of which 19 (63%) were off antiarrhythmic medications. Five patients expired during follow-up: one presented with a VT storm, but for the others, death was not related to VT/VF (MI-cardiogenic shock, pulmonary embolism, bronchogenic carcinoma, end stage heart failure). No procedural complications were reported. Conclusions This first prospective, single-procedure, multicenter study indicates that remote magnetic navigation is a safe and effective method for catheter ablation of post-infarction VT. [ABSTRACT FROM AUTHOR]

Currently, the temporal distribution of electric arcs across the ingot during vacuum arc remelting (VAR) is not a known or monitored process parameter. Previous studies indicate that the distribution of arcs can be neither diffuse nor axisymmetric about the center of the furnace. Correct accounting for the heat flux, electric current flux, and mass flux into the ingot is critical to achieving realistic solidification models of the VAR process. The National Energy Technology Laboratory has developed an arc position measurement system capable of locating arcs and determining the arc distribution within an industrial VAR furnace. The system is based on noninvasive magnetic field measurements and a VAR specific form of the Biot-Savart law. The system was installed on a coaxial industrial VAR furnace at ATI Albany Operations in Albany, OR. This article reports on the different arc distributions observed during production of Ti-6Al-4V. It is shown that several characteristic arc distribution modes can develop. This behavior is not apparent in the existing signals used to control the furnace, indicating the measurement system is providing new information. It is also shown that the different arc distribution modes observed may impact local solidification times, particularly at the side wall. [ABSTRACT FROM AUTHOR]

It is known that δ-type sunspot groups have a high flare productivity and produce strong flares. In particular, βγδ type sunspots are the most active type of all. A βγδ active region NOAA 9957 with frequent flux cancellations but without any marked flare activity during its decay phase was studied in this work. Using SOHO/MDI Dopplergrams and magnetograms, we detected continuous prominent downflow motions of 1500 - 1700 m s for several hours on the magnetic neutral line in this region. In the downflow region, penumbral structures were observed to decay. We will interpret and discuss the phenomenon as a case of submergence of the magnetic flux. [ABSTRACT FROM AUTHOR]

In ITER, magnetic fusion will explore the burning plasma regime. Because such burning plasma is sustained by its own fusion reactions, alpha particles need to be confined (Hazeltine 2010 Fusion Eng. Des. 7-9 85). New experiments using d(3He,p)α and d(d,p)t fusion reaction products were performed in JET. Fusion product loss was measured from MHD-quiescent plasmas with a charged particle activation probe installed at a position opposite to the magnetic field ion gradient drift (see figure 1)--1.77m above mid-plane--in the ceiling of JET tokamak. This new kind of escaping ion detector (Bonheure et al 2008 Fusion Sci. Technol. 53 806) provides for absolutely calibrated measurements. Both the mechanism and the magnitude of the loss are dealt with by this research. Careful analysis shows measured loss is in quantitative agreement with predictions from the classical orbit loss model. However, the comparison with simulated loss radial profile, although improved compared with previous studies in TFTR, Princeton, US (Zweben et al 2000 Nucl. Fusion 40 91), is not fully satisfactory and potential explanations for this discrepancy are examined. [ABSTRACT FROM AUTHOR]

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Δ E=3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter. [ABSTRACT FROM AUTHOR]

Abstract: We present first discharge rate measurements for Micromegas detectors in the presence of a high longitudinal magnetic field in the GeV kinematical region. Measurements were performed by using two Micromegas detectors and a photon beam impinging a CH2 target in the Hall B of the Jefferson Laboratory. One detector was equipped with an additional GEM foil, and a reduction of the discharge probability by two orders of magnitude compared to the stand-alone Micromegas was observed. The detectors were placed in the FROST solenoid providing a longitudinal magnetic field up to 5T. It allowed for precise measurements of the discharge probability dependence with a diffusion-reducing magnetic field. Between 0 and 5T, the discharge probability increased by a factor of 10 for polar angles between 19° and 34°. A GEANT4-based simulation developed for sparking rate calculation was calibrated against these data in order to predict the sparking rate in a high longitudinal magnetic field environment. This simulation is then used to investigate the possible use of Micromegas in the Forward Vertex Tracker (FVT) of the future CLAS12 spectrometer. In the case of the FVT a sparking rate of 1Hz per detector was obtained at the anticipated CLAS12 luminosity. [Copyright &y& Elsevier]

In this article the author discusses about the safety of magnetic resonance imaging (MRI) in patients with implanted cardiac rhythm management devices (CRMDs) in the U.S. As stated, the electromagnetic fields generated by MRI machines can interact with pacemaker and implantable cardioverterdefibrillators (ICDs) in multiple ways. Another concern is the displacement of the device generator by the MRI-generated magnetic field.

Despite the decline in U.S. cancer incidence and mortality rates, cancer remains the number one cause of death for people under the age of 85 and one in four people in the U.S. will die of cancer, mainly because of metastasis. Recently, interest in mesenchymal stem cell (MSC) tumor-homing has led to inquires into: (a) why MSCs home to tumors, (b) what the inherent protumor and antitumor consequences are, and (c) how to best capitalize on MSC tumor-homing for cell-based diagnostics and therapy. Here, these questions are reviewed and method for addressing them using animal models and tracking methodologies (or, synonymously, detection methodologies) are discussed. First, MSCs in a regenerative and tumor-homing context are reviewed, followed by MSC delivery and genetic labeling methods for tissue model systems. Finally, the use of the nonoptical methods, magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography, along with optical methods, fluorescence imaging and bioluminescent imaging, are reviewed related to tracking MSCs within disease model settings. The benefits and drawbacks of each detection method in animal models is reviewed along with the utility of each for therapeutic use. STEM CELLS 2011;29:920-927 [ABSTRACT FROM AUTHOR]

new best estimate methodology is proposed and oriented towards the determination of parameters related to a magnetic field anomaly produced by a simple geometric-shaped model or body such as a thin dike and horizontal cylinder. This approach is mainly based on solving a system of algebraic linear equations for estimating the three model parameters, e.g., the depth to the top (center) of the body ( z), the index parameter or the effective magnetization angle ( θ) and the amplitude coefficient or the effective magnetization intensity ( k). The utility and validity of this method is demonstrated by analyzing two synthetic magnetic anomalies, using simulated data generated from a known model with different random errors components and a known statistical distribution. This approach was also examined and applied to two real field magnetic anomalies from the United States and Brazil. The agreement between the results obtained by the proposed method and those obtained by other interpretation methods is good and comparable. Moreover, the depth obtained by such an approach is found to be in high accordance with that obtained from drilling information. The advantages of such a proposed method over other existing interpretative techniques are clarified, where it can be generalized to be automatically applicable for interpreting other geological structures described by mathematical formulations. [ABSTRACT FROM AUTHOR]

We present and interpret observations of two morphologically homologous flares that occurred in active region (AR) NOAA 10501 on 20 November 2003. Both flares displayed four homologous Hα ribbons and were both accompanied by coronal mass ejections (CMEs). The central flare ribbons were located at the site of an emerging bipole in the centre of the active region. The negative polarity of this bipole fragmented in two main pieces, one rotating around the positive polarity by ≈ 110° within 32 hours. We model the coronal magnetic field and compute its topology, using as boundary condition the magnetogram closest in time to each flare. In particular, we calculate the location of quasi-separatrix layers (QSLs) in order to understand the connectivity between the flare ribbons. Though several polarities were present in AR 10501, the global magnetic field topology corresponds to a quadrupolar magnetic field distribution without magnetic null points. For both flares, the photospheric traces of QSLs are similar and match well the locations of the four Hα ribbons. This globally unchanged topology and the continuous shearing by the rotating bipole are two key factors responsible for the flare homology. However, our analyses also indicate that different magnetic connectivity domains of the quadrupolar configuration become unstable during each flare, so that magnetic reconnection proceeds differently in both events. [ABSTRACT FROM AUTHOR]

Abstract: A novel and highly sensitive electrochemiluminescence (ECL) assay based on magnetic beads separation/collection process and thymine–Hg2+–thymine (T–Hg2+–T) coordination chemistry has been designed to detect Hg2+ ions in aqueous solution. In this protocol, two amine-terminated complementary DNA probes with five thymine–thymine (T–T) mismatches were introduced. One was coupled with carboxyl-modified magnetic beads and the other was labeled with tris (2, 2-bipyridine) ruthenium (II) (TBR). The couple of DNA probes, in the presence of Hg2+, can form double-stranded structure via the Hg2+-mediated coordination of T–Hg2+–T base pair. Therefore, they can be collected on the surface of electrode using a magnetic field. On the electrode, TBR labels and tripropylamine (TPA) could react to emit photons, which were detected by a custom-built ECL system. The detection limit for Hg2+ in this assay is 5nM, which is below the upper limit of Hg2+ for drinkable water mandated by United States Environmental Protection Agency (EPA), 10nM. To the best of our knowledge, this is the first example of ECL assay applying to detect Hg2+ with highly sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Mercury is the target of two space missions: MESSENGER (NASA), orbit insertion of which is planned for 2011 March, and ESA/JAXA BepiColombo, which would be launched in 2014. They will observe the surface of the planet with high accuracy (about 1 arcsec for BepiColombo), and this will encourage further study its rotation. Mercury is assumed to be composed of a rigid mantle and a partially molten core. We study the influence of the core–mantle interactions on the rotation perturbed by the solar gravitational interaction by modelling the core as an ellipsoidal cavity filled with inviscid fluid of constant uniform density and vorticity. We use both analytical (Lie transforms) and numerical tools to study this rotation with different shapes of the core. We stress on, in particular, the proper frequencies of the system, because they characterize the response of Mercury to the different solicitations, due to the orbital motion of Mercury around the Sun. We show that, contrary to its size, the shape of the core cannot be determined from observations of either longitudinal or polar motions. However, we highlight the strong influence of resonance between the proper frequency of the core and the spin of Mercury that raises the velocity field inside the core. We show that the key parameter is the polar flattening of the core. This effect cannot be directly derived from observations of the surface of Mercury, but we cannot exclude the possibility of an indirect detection by measuring the magnetic field. [ABSTRACT FROM AUTHOR]

A decade of X-ray stellar observations with Chandra and XMM-Newton has led to significant advances in our understanding of the physical processes at work in hot (magnetized) plasmas in stars and their immediate environment, providing new perspectives and challenges, and in turn the need for improved models. The wealth of high-quality stellar spectra has allowed us to investigate, in detail, the characteristics of the X-ray emission across the Hertzsprung-Russell (HR) diagram. Progress has been made in addressing issues ranging from classical stellar activity in stars with solar-like dynamos (such as flares, activity cycles, spatial and thermal structuring of the X-ray emitting plasma, and evolution of X-ray activity with age), to X-ray generating processes (e.g., accretion, jets, magnetically confined winds) that were poorly understood in the preChandra/XMM-Newton era. I will discuss the progress made in the study of high energy stellar physics and its impact in a wider astrophysical context, focusing on the role of spectral diagnostics now accessible. [ABSTRACT FROM AUTHOR]

The behavioral responses of free-swimming, wild southern stingrays (Dasyatis americana) and nurse sharks (Ginglymostoma cirratum) to permanent magnets were evaluated in the Florida Keys, USA. Animals were attracted to a baited magnetic treatment board consisting of two 15 cm × 10 cm × 5 cm grade C8 Barium-Ferrite (empirically, BaFe12O19) permanent magnets producing a flux of 950 gauss at their surface and a baited procedural control board containing two smooth nonmagnetized clay bricks. In the presence of permanent magnets, D. americana and G. cirratum demonstrated a significantly greater number of avoidance behaviors away from the magnet side of the apparatus, while both species fed a significantly greater number of times from the non-magnetized procedural control side. Thus, D. americana and G. cirratum showed sensitivity to a magnetic field and were successfully repelled from baited areas containing magnets. The results from the current study suggest that the use of grade C8 Barium-Ferrite permanent magnets as an avoidance mechanism (e.g., repellent) to reduce elasmobranch mortalities associated with fishing operations and beach nets merits further investigation. [ABSTRACT FROM AUTHOR]

Objectives: To describe a new method to analyze the static sitting postural sway and to compare the results of healthy young and older adult subjects. Methods: Thirty-eight healthy subjects took part in the study, including 17 young adults (mean age 23±2.38 years old) and 21 older adults (mean age 67±2.42 years old). The device used to quantify trunk sway was the magnetic field sensor Polhemus® 3Space Isotrack II. The measurements were taken in the eyes-opened (EO) and eyes-closed (EC) condition with the subjects seated first on a wooden stable surface (SS) then on a foam unstable surface (US) without back or foot support. Each sensory condition was assessed for 90 seconds. The analyzed parameters were: maximum amplitude (Amp), total trajectory (Traj) and mean velocity (Vel) in the sagittal (X) and frontal (Y) planes. Results: In the EO and EC conditions on SS, young adults presented greater postural sway in the X and Y planes on the Traj and Vel parameters. In the US, young adults showed greater Y Traj and Y Vel in the EO and EC conditions, and there was no significant difference between the groups with regard to X Traj and X Vel in the EC condition. The young adults presented greater Amp only in the EOSS condition in the X plane. Conclusions: The young adult subjects presented greater sway in the sitting position than the older adult subjects. In addition, the Polhemus® device was a useful tool to analyze static sitting postural sway and can be used in future studies that associate static sitting postural sway with the effect of various motor tasks. [ABSTRACT FROM AUTHOR]

The effects of finitely conducting ground on the signature of lightning-generated magnetic fields at ground level were evaluated by numerical solution of Sommerfeld's integrals. Results are presented for distances between 10 m to 1 km from the lightning channel and for ground conductivities in the range of 0.01 and 0.0001 S/m. The results obtained from the exact theory are compared with the predictions of two frequently used analytical approximations to Sommerfeld's equations. Based on that comparison, the limits of validity of these approximate theories are obtained. [ABSTRACT FROM AUTHOR]

Summary: Objectives: The effects of the Michigan splint on the change in disc displacement (DD) as well as the position of the condyles were determined by metrical analysis using magnetic resonance imaging (MRI). Methods: Twenty-five patients with clinical DD symptoms were treated by means of the Michigan splint, and an assessment of the effects of the splint was conducted or verified by MRI before and during the period of therapy, 5 months follow-up. The positions of the condyles and the disc were calculated from the MRI in the parasagittal plane. Results: There were no changes in the positions of the disc and condyles in the physiological joints of the patients (n=23) prior to and during the time the splint was in place (p>0.05). The splint achieved a DD decrease (p<0.05), and pain was eliminated in 69.2% of the DD joints with reduction (n=13). As far as the DD joints without reduction (n=13) are concerned, pain was eliminated in 74.9% of the joints, that is, without any change in the positions of the disc and condyles (p>0.05). Conclusions: The evaluation of the Michigan splint therapy showed that it has no influence in the repositioning of the DD joints without reduction, but the DD joints with reduction have a limited positive effect. In both forms of these displacements, conditions for the elimination of the clinical symptoms are created. [Copyright &y& Elsevier]

Purpose: This cohort study aims to examine cardiovascular disease (CVD) mortality risks among workers in occupations potentially exposed to magnetic fields (MF). Methods: Risks for major CVD mortality by potential job-related MF exposure were examined in a sample of U.S. workers from the National Longitudinal Mortality Study using multivariate proportional hazards models. Results: After adjustment for demographic factors, there were no significant excess risks between individuals with medium (0.15 to <0.20 μT), high (0.20 to <0.30 μT), or very high (≥0.30 μT) exposure levels as compared with individuals with background exposure levels of MF (<0.15 μT) for the CVD mortality outcomes. Indirect adjustment for potential confounding by current smoking prevalence did not change the pattern of these results. Conclusion: Our study does not provide evidence for an association between occupational MF exposure and CVD mortality risk. [Copyright &y& Elsevier]

Abstract: One of the great discoveries of NASA''s Galileo mission was the presence of an intrinsically produced magnetic field at Ganymede. Generation of the relatively strong (750 nT) field likely requires dynamo action in Ganymede''s metallic core, but how such a dynamo has been maintained into the present epoch remains uncertain. Using a one-dimensional, three layer thermal model of Ganymede, we find that magnetic field generation can only occur if the sulfur mass fraction in Ganymede''s core is very low (≲3%) or very high (≳21%), and the silicate mantle can cool rapidly (i.e. it has a viscosity like wet olivine). However, these requirements are not necessarily compatible with cosmochemical and physical models of the satellite. We therefore investigate an alternative scenario for producing Ganymede''s magnetic field in which passage through an eccentricity pumping Laplace-like resonance in Ganymede''s past enables present day dynamo action in the metallic core. If sufficient tidal dissipation occurs in Ganymede''s silicate mantle during resonance passage, silicate temperatures can undergo a runaway which prevents the core from cooling until the resonance passage ends. The rapid silicate and core cooling that follows resonance escape triggers dynamo action via thermal and/or compositional convection. To test the feasibility of this mechanism we couple our thermal model with an orbital evolution model to examine the effects of resonance passage on Ganymede''s silicate mantle and metallic core. We find that, contrary to expectations, there are no physically plausible scenarios in which tidal heating in the silicates is sufficient to cause the thermal runaway necessary to prevent core cooling. These findings are robust to variations in the silicate rheology, tidal dissipation factor of Jupiter (), structure of the ice shell, and the inclusion of partial melting in the silicate mantle. Resonance passage therefore appears unlikely to explain Ganymede''s magnetic field and we must appeal to the special conditions described above to explain the presence of the field. [Copyright &y& Elsevier]

Abstract: We summarize the status of Nb3Sn development in the USA. The US conductor development program (CDP), initiated in 1999, has resulted in commercial wires that carry more than 3kAmm−2 at 12T and 4.2K. These high current Nb3Sn wires have successfully been cabled and used in accelerator magnets that achieved record magnetic fields. This article describes the CDP, its achievements, and the manufacturers involved. We discuss low magnetic field instability in magnets that re-emerged through the use of very high current density Nb3Sn wires, and solutions that address these stability problems. It is shown how cabling of high current wires is a balance between edge deformation and mechanical stability of the cable, and an empirical cable recipe is described. The article concludes with an outlook for possible future methods to optimize, and further increase, the current carrying capacity in Nb3Sn at medium magnetic fields. The article describes how record current density Nb3Sn wires have to be implemented in accelerator type magnets, to achieve magnetic fields that approach the performance limitations of Nb3Sn. [Copyright &y& Elsevier]

The U. S. National High Magnetic Field Laboratory 100 Tesla Multi-Pulse Magnet System is now successfully commissioned. This magnet system is the result of a long-term partnership project jointly funded by the U. S. Department of Energy-Office of Basic Energy Science and the National Science Foundation. Science experimentation inside the magnet started in December 2006 at the NHMFL Pulsed Field Science Facility located at Los Alamos National Laboratory. Repeated, non-destructive operation of the system with original components is continuing in the 85 T to 90 T range. The system will eventually combine, a nominal 40 T platform field produced by a controlled-waveform generator-powered long-pulse magnet with a nominal 60 T field generated by a capacitor-bank powered pulsed insert magnet to produce the rated field. Milestone non-destructive operation to 88.9 T was achieved in October 2006. This paper will present an overview of the generator driven outsert magnet system together with the high-field pulsed insert magnet's design and construction. We will review commissioning and performance data through summer of 2007. Criteria for increasing the systems maximum field performance will also be reviewed addressing the goal to increase operating field level (in support of experiments) to 95 T and then to 100 T. [ABSTRACT FROM AUTHOR]

The National High Magnetic Field Laboratory (NHMFL) has embarked on an innovative program to develop a number of Series-Connected-Hybrid magnetic systems. In this novel concept, a set of resistive coils (insert) and a set of superconducting cable-in-conduit conductor (CICC) coils (outsert) are electrically driven in series, rather than independently as in previous hybrid systems. Presently NHMFL is working on 3 different projects. The first, funded by the National Science Foundation (NSF) with an $11.7 million grant, is related to the construction of a cylindricel-bore Series-Connected Hybrid (SCH), for high field nuclear magnetic resonance (NMR), condensed matter physics, biology and chemistry, to be located at the Magnet Lab's Tallahassee location. The second, funded by the Hahn-Meitner Institute (HMI) in Berlin, relates to the engineering design for a horizontal bore Series-Connected Hybrid to be used in a neutron diffraction experimental system. Finally, the third, also funded by NSF, is a conceptual and engineering study for an SCH that would be used for neutron scattering experiments at Oak Ridge National Laboratory's Spallation Neutron Source (SNS), similar to the HMI version. Because of the main points in common between the 3 different systems, our final goal is to develop a superconducting magnetic system suitable for the 3 applications. We believe this is possible for the magnet although, due to the different field/bore orientations, some differences in the mechanical design of the cryostat and resistive inserts will exist. In this paper we will give an overview of the R&D strategy devised to develop these superconducting magnetic systems, together with a report on the present status of such program. [ABSTRACT FROM AUTHOR]

The orthogonal field components from global INTERMAGNET magnetometer stations are studied via multifractal detrended fluctuation analysis to determine whether there are clear and consistent regional patterns in the behavior of the fluctuations. There are three distinct scaling regimes in the qth-order fluctuation function for each of the 24 stations studied covering Southwest North America, Northeast North America, Central Europe, Northern Europe, Australasia and Asia. There is a consistent break point at time scale around 23 h for all stations. The scaling exponents of the second-order fluctuation functions reflect the regional character of the stations, and can be used for station classification, and for possible regional models. [ABSTRACT FROM AUTHOR]

The article discusses the use of a tool named FieldVis for visualizing astrophysical magnetohydrodynamic flow in the U.S. Astronomers have long been challenged to test theories of observable phenomena at great distances from the Earth. Simulations in this area solve the fundamental equations of ideal and compressible magnetohydrodynamics. The systems contain fluid flows and magnetic fields that dynamically interact with one another. Observers frequently can see patterns in vector fields more easily with the use of streaklines represented by FieldVis for the velocity and analogous flux lines for the magnetic field.

The COHMAG report of the National Academy of Sciences provides an assessment of high field magnet science and technology in the United States, and identifies possible new initiatives for future high field magnets. Regarding NMR, the report identifies high resolution NMR spectrometers in the range of 30 T/1.3 GHz as having great scientific interest. This paper discusses technology issues associated with 30 T superconducting magnets. The enabling technology is HTS conductors and coil technology. Significant issues remain for application of HTS conductors to large coils, including long length quality, heat treatment, anisotropy and strain dependence. The outer LTS coil sections are large, with high stress and stored energy. Structural issues, including high strength conductor and reinforcement, and quench protection issues are significant. The status of technology required for a 30 T NMR magnet is examined. A preliminary conceptual design of the 30 T magnet is presented. [ABSTRACT FROM AUTHOR]

This paper presents results of design studies of high-field dipole magnets based on Nb3Sn shell-type coils performed to explore the possibilities and limitations of Nb3Sn accelerator magnets. To achieve the maximum bore field of 13–16 T, 3- and 4-layer coils were used. The coil design concepts, conductor parameters, results of magnetic and mechanical analysis are presented and discussed. Different conductor grading techniques are described and compared. An innovative design of a 3-layer coil without interlayer splices is described. [ABSTRACT FROM AUTHOR]

This paper presents experimental results obtained at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida during the summers of 2002 and 2003. Currents induced by triggered and natural lightning events were measured at the terminations of a buried power cable, in the cable shield, and in the inner cable conductor. Measurements of the horizontal component of the magnetic field above the ground surface for both natural and triggered lightning are also presented. For distant natural lightning events, locations of ground strike points were determined using the U.S. National Lightning Detection Network (NLDN). Based on the theoretical developments presented in Part I of this paper [14], the field-to-buried cable coupling equations are solved in both the time domain and in the frequency domain. The obtained experimental results are then used to validate the numerical simulations provided by the relevant developed codes. [ABSTRACT FROM AUTHOR]

In order to provide scientists with access to both high magnetic fields and very low temperatures simultaneously, to pursue studies of the properties of matter in highly polarized or magnetized states, the National High Magnetic Field Laboratory operates a High B/T Facility as a user facility at the University of Florida. This facility is designed with high refrigeration capabilities to permit studies of a wide range of applications for extended periods of time. An overview of the principal characteristics of the facility and the current scientific areas of interest are presented. [Copyright &y& Elsevier]

Some experimental and epidemiologic evidence suggests that residential exposure to power-frequency magnetic fields can increase breast cancer risk. This association was investigated in a nested case-control study of female breast cancer within a cohort of African Americans, Latinas, and Caucasians in Los Angeles County, California. Incident breast cancer was ascertained from 1993 to 1999 by linkage to county and state tumor registries. Controls were selected from a random sample of cohort members without breast cancer at baseline. Exposure was assessed in 1995-2001 by means of wiring configuration coding (an indirect measure of magnetic field exposure that has been associated with increased risk of childhood leukemia in Los Angeles and elsewhere in North America) in all homes occupied over the previous 10 years for 743 cases and 699 controls and by measurement of magnetic fields in the bedroom over a 7-day period for 347 cases and 286 controls. The estimated risk of breast cancer was not higher among women with wiring configuration codes associated with the highest magnetic fields (for a very high current configuration relative to very low, the adjusted odds ratio was 0.76 (95% confidence interval: 0.49, 1.18)). Stronger measured fields were not significantly associated with increased risk. These data suggest that residential magnetic field exposures commonly experienced by US women do not influence risk of breast cancer. [ABSTRACT FROM AUTHOR]