论文信息 - Intergalactic Magnetic Fields from Quasar Outflows

2007 - 0708.1788

Reionization bias in high‐redshift quasar near‐zones

Absorption spectra of high-redshift quasars exhibit an increasingly thick Lyα forest, suggesting that the fraction of neutral hydrogen in the intergalactic medium (IGM) is increasing towards z ∼6. However, the interpretation of these spectra is complicated by the fact that the Lyα optical depth is already large for neutral hydrogen fractions in excess of 10 -4 , and also because quasars are expected to reside in dense regions of the IGM. We present a model for the evolution of the ionization state of the IGM which is applicable to the dense, biased regions around high-redshift quasars as well as more typical regions in the IGM. We employ a cold dark matter based model in which the ionizing photons for reionization are produced by star formation in dark matter haloes spanning a wide range of masses, combined with numerical radiative transfer simulations which model the resulting opacity distribution in quasar absorption spectra. With an appropriate choice for the parameter which controls the star formation efficiency, our model is able to simultaneously reproduce the observed Lyα forest opacity at 4 < z < 6, the ionizing photon mean-free-path at z ∼ 4 and the rapid evolution of highly ionized near-zone sizes around high-redshift quasars at 5.8 < z < 6.4. In our model, reionization extends over a wide redshift range, starting at z ≥ 10 and completing as HII regions overlap at z ∼ 6-7. We find that within 5 physical Mpc of a high-redshift quasar, the evolution of the ionization state of the IGM precedes that in more typical regions by around 0.3 redshift units. More importantly, when combined with the rapid increase in the ionizing photon mean-free-path expected shortly after overlap, this offset results in an ionizing background near the quasar which exceeds the value in the rest of the IGM by a factor of ∼2-3. We further find that in the post-overlap phase of reionization the size of the observed quasar near-zones is not directly sensitive to the neutral hydrogen fraction of the IGM. Instead, these sizes probe the level of the background ionization rate and the temperature of the surrounding IGM. The observed rapid evolution of the quasar near-zone sizes at 5.8 < z < 6.4 can thus be explained by the rapid evolution of the ionizing background, which in our model is caused by the completion of overlap at the end of reionization by 6 ≤ z ≤ 7.

2018 - Medicine

Comparison of 1.5- and 3.0-T magnetic resonance imaging for evaluating lesions of the knee

Background: With conflicting results in the literature, it remains unclear whether a higher field strength automatically increases the sensitivity and specificity of magnetic resonance imaging (MRI) for detecting pathological lesions in the knee. Therefore, we performed a systematic review and meta-analysis of studies comparing the diagnostic accuracy of 1.5- and 3.0-T MRI for lesions within the knee. Methods: Sixteen studies were included in the meta-analysis of the diagnostic accuracy of MRI for lesions of the knee joint, and areas under the curve (AUC) derived from the summary receiver operating characteristic curve analysis were determined for comparison of the diagnostic accuracy with differing magnetic field strength as well as for lesions in different tissues of the knee. Separate meta-analyses were performed for the diagnosis of lesions within articular cartilage, ligaments, and meniscus. Results: For lesions within the articular cartilage, the AUC for 1.5-T MRI differed significantly from that for 3.0-T MRI (Z = 3.4, P < .05). However, for lesions within the ligaments and meniscus, the AUC values for 1.5-T MRI did not differ significantly from those for 3.0-T MRI (Z = 0.32, P > .05, and Z = 0.33, P > .05, respectively). Conclusion: Our results indicate that both 1.5-T and 3.0-T MRI offer high diagnostic accuracy and clinical relevance for knee injuries involving the meniscus or a ligament. However, the present meta-analysis indicates that 3.0-T MRI does offer greater diagnostic accuracy than 1.5-T MRI for articular cartilage lesions.

2014 - IEEE Transactions on Electron Devices

Theoretical and Experimental Investigation on Intense Sheet Electron Beam Transport With Its Diocotron Instability in a Uniform Magnetic Field

In this paper, the cold-fluid model theory of an intense sheet electron beam is developed to investigate the diocotron instability during its transport in a uniform magnetic field. The model shows that if the magnetic field strength and the beam filling factor are increased separately, the diocotron instability will be suppressed, which extends the sheet-beam transport distance effectively. To verify the above conclusion, a set of complicated instruments, the electron beam measuring and analyzing system (EBMAS), was developed to measure the beam cross section, beam current density, and the 3-D trajectory. The sheet electron beam transport process in a uniform magnetic field with its diocotron instability is investigated on the basis of EBMAS measurements. The measured results agree very well with theoretical calculation and numerical simulation. A sheet-electron-beam tube based on a uniform magnetic field was then manufactured to drive a future W-band sheet-beam klystron (WSBK). Tuning the sheet-beam parameters over a broad range, including a cathode voltage range of 20-82 kV, current range of 0.5-4.27 A, and with a beam cross section of about 10 mm $\times\,$ 0.5 mm, the experimental beam transmission rate is above 98% through a beam tunnel of 100 mm in length.

1989 - Physics Letters A

Lyapunov stability of motion in Ernst space-time

Abstract The Lyapunov stability of the circular motion of test bodies in the space-time of a black hole imbedded in an axially symmetric magnetic field is investigated. The greater the magnetic field strength, the smaller is the region of stability, which disappears completely at a certain finite value of the field.

1992

A new inrush detection method for transformer differential protection

ContentsThe long-used restraining principle, based on the detection of 2nd harmonics in the currents, can not always satisfactorily meet the demand of blocking the transformer differential protection for all three phases, because the line currents are not the direct image of the core saturation. The differential protection may become inadequate. A transformer can however be switched on for all cases, without the false or fail-safe tripping, when the harmonic restraint is derived from the magnetic field strength of the core.If a delta-connected winding is present, the magnetic field strengths can not be easily recognized in the line currents, because their zero-sequence component is distorted. A new method is presented, which can estimate the fundamental and the 2nd harmonic of this zero-sequence component. The components of the magnetic field strength can therefore be determined in currents only, whose ratio is known to be characteristic for the core saturation.The proposed method was implemented on an industrial protection system based on a microprocessor and was tested on data obtained from computer-simulation and a model transformer in a laboratory. It turned out that the proposed method performed well on all cases.ÜbersichtDie üblicherweise benützte Blockierung beim Einschalten eines Transformators beruht auf der Bewertung der zweiten Harmonischen in den Strömen. Dieses Prinzip kann nicht immer den Transformatorvergleichsschutz in allen drei Phasen blockieren. Dagegen kann ein Transformator in allen Fällen ohne Fehlauslösung eingeschaltet werden, wenn die Blockierung aus der Harmonischen der magnetischen Feldstärke des Kerns abgeleitet wird.Eine neue Methode wird vorgestellt, wie die Homopolarkomponente der Grundschwingung und der zweiten Harmonischen näherungsweise berechnet werden kann. Die benötigten Anteile der Feldstärken können damit aus den Differenzströmen ermittelt werden.Das vorgeschlagene Verfahren wurde auf einer industriell gefertigten Schutzkarte implementiert. Die Überprüfung des Verfahrens erfolgte mit Berechnungsverfahren und durch Messungen im Labor.

2015 - Journal of Magnetism and Magnetic Materials

Magnetic particle capture for biomagnetic fluid flow in stenosed aortic bifurcation considering particle–fluid coupling

Abstract Magnetic nanoparticles drug carriers continue to attract considerable interest for drug targeting in the treatment of cancer and other pathological conditions. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the basic principle behind the Magnetic Drug Targeting (MDT). It is essential to couple the ferrohydrodynamic (FHD) and magnetohydrodynamic (MHD) principles when magnetic fields are applied to blood as a biomagnetic fluid. The present study is devoted to study on MDT technique by particle tracking in the presence of a non uniform magnetic field in a stenosed aortic bifurcation. The present numerical model of biomagnetic fluid dynamics (BFD) takes into accounts both magnetization and electrical conductivity of blood. The blood flow in the bifurcation is considered to be incompressible and Newtonian. An Eulerian–Lagrangian technique is adopted to resolve the hemodynamic flow and the motion of the magnetic particles in the flow using ANSYS FLUENT two way particle–fluid coupling. An implantable infinitely long cylindrical current carrying conductor is used to create the requisite magnetic field. Targeted transport of the magnetic particles in a partly occluded vessel differs distinctly from the same in a regular unblocked vessel. Results concerning the velocity and temperature field indicate that the presence of the magnetic field influences the flow field considerably and the disturbances increase as the magnetic field strength increases. The insert position is also varied to observe the variation in flow as well as temperature field. Parametric investigation is conducted and the influence of the particle size ( d p ), flow Reynolds number (Re) and external magnetic field strength ( B 0 ) on the “capture efficiency” (CE) is reported. The difference in CE is also studied for different particle loading condition. According to the results, the magnetic field increased the particle concentration in the target region. Analysis shows that there exists an optimum regime of operating parameters for which deposition of the drug carrying magnetic particles in a target zone on the partly occluded vessel wall can be maximized. The results provide useful design bases for in vitro set up for the investigation of MDT in stenosed blood vessels.

1995 - In Vivo

Physical chemistry and the biologic week in the perspective of chrono-oncology.

The computation of spectra and cross-spectra yielding coherences suggests that there exist certain relationships between rhythmicities and electromagnetic fields that are external to the biologic structure studied. Models are here provided which may prompt further investigation by allowing at least tentative, quantitative temporal insights into physico-chemical aspects of the biologic week. On the basis of empirical data, a computation of the oscillating frequency during the diffusion of ions in a magnetic field can be performed. The frequency of some ions found in cells (Ca2+, K+, Na+, Mg2+) and of some proteins (albumin, hemoglobin) can be calculated given the diffusion constant in cells, the magnetic field strength, the relative molecular mass and the effective charge. For a field of 10(-9) Tesla, the oscillating period of K+ is about 180 hours, that of Ca2+ about 160 hours, that of Na+ about 150 hours and that of Mg2+ about 145 hours; the period lengths of albumin and hemogiobin are of the order of 30 and 40 days. Without a consideration of any receptors, the results seem to represent, at least numerically, realistic components in the time structure investigated by chronobiology.

2018 - 1804.09313

A First Look at BISTRO Observations of the ρ Oph-A core

We present 850 μm imaging polarimetry data of the ρ Oph-A core taken with the Submillimeter Common-User Bolometer Array-2 (SCUBA-2) and its polarimeter (POL-2) as part of our ongoing survey project, -fields In STar forming RegiOns (BISTRO). The polarization vectors are used to identify the orientation of the magnetic field projected on the plane of the sky at a resolution of 0.01 pc. We identify 10 subregions with distinct polarization fractions and angles in the 0.2 pc ρ Oph-A core; some of them can be part of a coherent magnetic field structure in the ρ Oph region. The results are consistent with previous observations of the brightest regions of ρ Oph-A, where the degrees of polarization are at a level of a few percent, but our data reveal for the first time the magnetic field structures in the fainter regions surrounding the core where the degree of polarization is much higher (>5%). A comparison with previous near-infrared polarimetric data shows that there are several magnetic field components that are consistent at near-infrared and submillimeter wavelengths. Using the Davis–Chandrasekhar–Fermi method, we also derive magnetic field strengths in several subcore regions, which range from approximately 0.2 to 5 mG. We also find a correlation between the magnetic field orientations projected on the sky and the core centroid velocity components.

2015 - Physics in medicine and biology

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

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.

2015

Measuring magnetic fields near and far with the SKA via the zeeman effect

The measurement of Zeeman splitting in spectral lines-both in emission and absorption-can provide direct estimates of the magnetic field strength and direction in atomic and molecular clouds, both in our own MilkyWay and in external galaxies. This method will probe the magnetic field in the warm and cold neutral components of the interstellar medium, providing a complement to the extensive SKA Faraday studies planning to probe the field in the ionized components.

2005 - Analytical chemistry

Use of paired, bonded NdFeB magnets in redox magnetohydrodynamics.

Bonded neodymium-iron-boron (NdFeB) permanent magnets in a paired configuration were successfully used to control mass transport in redox-based, magnetohydrodynamics (MHD). Control of fluid flow based on magnetic fields has potential for use in portable lab-on-a-chip (LOAC) and analytical devices. Bonded magnets, composed of magnetic powder and organic binder materials, are less expensive and easier to fabricate and pattern than electromagnets and sintered permanent magnets, which have been previously used in MHD studies on electrochemical systems. The ability to pattern bonded magnets near and around the electrodes is expected to allow for better control over the magnetic field distribution and solution flow. Current was generated at an 800-microm-radius platinum disk electrode in a solution of 0.06 M nitrobenzene and 0.5 M tetra-n-butylammonium hexafluorophosphate in acetonitrile. Increases in limiting current in the presence of the magnetic field, which indicate enhancement in mass transport, for sintered (210+/-14%, N = 4, where B(r) = 1.23 T and magnetic field strength is 0.55 T) and bonded (94+/-8%, N = 4, where B(r) = 0.41 T and magnetic field strength is 0.20 T) magnets, were similar to those obtained using an electromagnet with the same magnetic flux densities. The magnetic field strength and not the magnet type is important in controlling fluid flow, which is encouraging for integration of bonded permanent magnets into LOAC devices.

2015 - Medical physics

Dynamic 31P MR spectroscopy of plantar flexion: influence of ergometer design, magnetic field strength (3 and 7 T), and RF-coil design.

PURPOSE Dynamic phosphorus magnetic resonance spectroscopy ((31)P MRS) during and after acute exercise enables the noninvasive in vivo determination of the mitochondrial capacity of skeletal muscle. Nevertheless, the lack of standardization in experimental setups leads to significant variations in published values of maximal aerobic capacity, even in the population of healthy volunteers. Thus, in this study, we aimed to assess the impact of the ergometer type (pneumatic and mechanical resistance construction), radiofrequency (RF)-coil diameter, and different magnetic field strengths (3 and 7 T) on the metabolic parameters measured by dynamic (31)P MRS during a plantar flexion isotonic exercise protocol within the same group of healthy volunteers. METHODS Dynamic (31)P MRS measurements of the calf muscle in 11 volunteers (mean age, 36 ± 13 yrs; mean BMI, 23.5 ± 2.5 kg/m(2)), on a 3 T MR system with a custom-made mechanical ergometer in the first research laboratory (RL1) and on 3 and 7 T MR systems equipped with a commercial pneumatic ergometer in the second research laboratory (RL2), were performed at three different workloads. RF-coils differed slightly between the sites and MR systems used. The repeatability of the experimental protocol was tested in every setup. The basal concentrations of phosphocreatine (PCr), exercise-induced depletion of PCr (ΔPCr), initial PCr resynthesis rate (VPCr), and mitochondrial capacity (Qmax) were calculated and compared between the research sites and field strengths. RESULTS High repeatability of the measurement protocol was found in every experimental setup. No significant differences at any workload were found in these metabolic parameters assessed at different magnetic field strengths (3 T vs 7 T), using the same ergometer (in RL2) and a similar RF-coil. In the inter-research laboratory comparison at the same field strength (3 T), but with using different ergometers and RF-coils, differences were found in the concentration of PCr measured at rest and in the drop in PCr signal intensity. These differences translated into difference in the value of mitochondrial capacity at a workload of 15% of maximal voluntary contraction (MVC) force (0.45 ± 0.16 mM/s vs 0.31 ± 0.08 mM/s, in the RL1 and RL2, respectively). CONCLUSIONS Metabolic parameters measured during exercise challenge by dynamic (31)P MRS do not depend upon the magnetic field strength used. For multicenter studies with different ergometers, it is important to set the same workload, measurement, and evaluation protocols, especially when the effects of very mild exercise (15% MVC) are to be compared. However, a higher workload (24% MVC) decreases the influence of imperfections and intersite differences for the assessed value of maximal mitochondrial capacity.

1986 - Magnetic Resonance in Medicine

Relaxation of water protons in the intra‐ and extracellular regions of blood containing Gd(DTPA)

The magnetic field dependence of the longitudinal relaxation rates 1/T1 (NMRD profiles) of blood and plasma from rabbits before and after injection of Gd(DTPA) are reported as a function of magnetic field strength from 0.01 to 50 MHz. Over 100 values along the time‐dependent magnetization were recorded for each 1/T1 and analyzed for multiple exponentials. From these data, which indicate a single exponential, from the measured Gd content of each sample, and the NMRD profiles, we show that Gd is in the extracellular space only and is present as rotationally mobile Gd(DTPA), uncomplexed with protein or blood cells; and that the water protons exchange rapidly between the intra‐ and extracellular regions. © 1986 Academic Press, Inc.

2008 - The Astrophysical Journal

Studies of Regular and Random Magnetic Fields in the ISM: Statistics of Polarization Vectors and the Chandrasekhar-Fermi Technique

Polarimetry is extensively used as a tool to trace the interstellar magnetic field projected on the plane of sky. Moreover, it is also possible to estimate the magnetic field intensity from polarimetric maps based on the Chandrasekhar-Fermi method. In this work, we present results for turbulent, isothermal, three-dimensional simulations of sub/supersonic and sub/super-Alfvénic cases. With the cubes, assuming perfect grain alignment, we created synthetic polarimetric maps for different orientations of the mean magnetic field with respect to the line of sight (LOS). We show that the dispersion of the polarization angle depends on the angle of the mean magnetic field regarding the LOS and on the Alfvénic Mach number. However, the second-order structure function of the polarization angle follows the relation SF ∝ lα, α being dependent exclusively on the Alfvénic Mach number. The results show an anticorrelation between the polarization degree and the column density, with exponent γ ∼ − 0.5, in agreement with observations, which is explained by the increase in the dispersion of the polarization angle along the LOS within denser regions. However, this effect was observed exclusively on supersonic, but sub-Alfvénic, simulations. For the super-Alfvénic, and the subsonic model, the polarization degree showed to be independent of the column density. Our major quantitative result is a generalized equation for the CF method, which allowed us to determine the magnetic field strength from the polarization maps with errors <20%. We also account for the role of observational resolution on the CF method.

2002 - Journal of Magnetism and Magnetic Materials

Magnetically modulated optical transmission of magnetic fluid films

Abstract The optical transmission of the magnetic fluid film under perpendicular magnetic fields was investigated by measuring the transmitted intensity of the normally incident light through the film. The transmittance I / I 0 of the magnetic fluid film was observed to decrease with the increase of the magnetic field strength H due to the reduction in the area occupied by the relatively optic transparent liquid phase. Moreover, under a given H , the transmittance decreased exponentially with the increasing film thickness L , i.e. I / I 0 =exp(− L / δ ), where the δ denotes the attenuation distance. It was further found that the δ varies with the magnetic field strength and the concentration of the fluid, but is independent of the sweep rate of the field.

1948 - The Review of scientific instruments

A magnetic field strength meter employing the Hall effect in germanium.

The instrument to be described measures magnetic field strengths as determined from the Hall effect in germanium. The essential parts of this instrument include a small germanium probe, and a panel type microammeter calibrated directly in gauss. Its accuracy is ±2 percent at fields between 100 and 8000 gauss. At higher fields the readings are too low, the error amounting to 9 percent at 20,000 gauss. The chief advantages of this instrument are: (a) small size and portability, (b) continuous reading rather than ballistic as in ordinary field strength meters, and (c) a small non‐magnetic probe with which one can search in very narrow gaps.

2016 - Journal of Cerebral Blood Flow & Metabolism

A general model to calculate the spin-lattice (T1) relaxation time of blood, accounting for haematocrit, oxygen saturation and magnetic field strength

Many MRI techniques require prior knowledge of the T1-relaxation time of blood (T1bl). An assumed/fixed value is often used; however, T1bl is sensitive to magnetic field (B0), haematocrit (Hct), and oxygen saturation (Y). We aimed to combine data from previous in vitro measurements into a mathematical model, to estimate T1bl as a function of B0, Hct, and Y. The model was shown to predict T1bl from in vivo studies with a good accuracy (±87 ms). This model allows for improved estimation of T1bl between 1.5–7.0 T while accounting for variations in Hct and Y, leading to improved accuracy of MRI-derived perfusion measurements.

2006 - International Journal of Hyperthermia

Magnetic nanoparticles for interstitial thermotherapy – feasibility, tolerance and achieved temperatures

Background: The concept of magnetic fluid hyperthermia is clinically evaluated after development of the whole body magnetic field applicator MFH® 300F and the magnetofluid MFL 082AS. This new system for localized thermotherapy is suitable either for hyperthermia or thermoablation. The magnetic fluid, composed of iron oxide nanoparticles dispersed in water, must be distributed in the tumour and is subsequently heated by exposing to an alternating magnetic field in the applicator. We performed a feasibility study with 22 patients suffering from heavily pretreated recurrences of different tumour entities, where hyperthermia in conjunction with irradiation and/or chemotherapy was an option. The potential to estimate (by post-implantation analyses) and to achieve (by improving the technique) a satisfactory temperature distribution was evaluated in dependency on the implantation technique. Material and methods: Three implantation methods were established: Infiltration under CT fluoroscopy (group A), TRUS (transrectal ultrasound) – guided implantation with X-fluoroscopy (group B) and intra-operative infiltration under visual control (group C). In group A and B the distribution of the nanoparticles can be planned prior to implantation on the basis of three-dimensional image datasets. The specific absorption rates (SAR in W/kg) can be derived from the particle distribution imaged via CT together with the actual H-field strength (in kA/m). The temperature distribution in the tumour region is calculated using the bioheat-transfer equation assessing a mean perfusion value, which is determined by matching calculated temperatures to direct (invasive or endoluminal) temperature measurements in reference points in or near the target region. Results: Instillation of the magnetic fluid and the thermotherapy treatments were tolerated without or with only moderate side effects, respectively. Using tolerable H-field-strengths of 3.0–6.0 kA/m in the pelvis, up to 7.5 kA/m in the thoracic and neck region and >10.0 kA/m for the head, we achieved SAR of 60–380 W/kg in the target leading to a 40°C heat-coverage of 86%. However, the coverage with ≥42°C is unsatisfactory at present (30% of the target volume in group A and only 0.2% in group B). Conclusion: Further improvement of the temperature distribution is required by refining the implantation techniques or simply by increasing the amount of nanofluid or elevation of the magnetic field strength. From the actual nanoparticle distribution and derived temperatures we can extrapolate, that already a moderate increase of the H-field by only 2 kA/m would significantly improve the 42°C coverage towards 100% (98%). This illustrates the great potential of the nanofluid-based heating technology.

1996 - Journal of the American Chemical Society

Magnetic Field Dependence of Nitrogen−Proton J Splittings in 15N-Enriched Human Ubiquitin Resulting from Relaxation Interference and Residual Dipolar Coupling

One-bond 1JNH couplings have been measured in 15N-enriched human ubiquitin and range from 91.1 to 95.6 Hz. Measurements have been carried out using two different methods and at 1H frequencies of 360, 500, and 600 MHz. The best method yields a precision of ca 0.02 Hz, and permits reliable measurement of the small changes (<0.3 Hz) in 1JNH splitting that occur when the magnetic field strength is increased from 8.5 to 14 T. The dependence of the 1JNH splittings on the strength of the static magnetic field originates from two sources: a dynamic frequency shift caused by interference of the 15N chemical shift anisotropy and the 15N−1H dipolar coupling relaxation mechanisms, and a dipolar contribution caused by a small degree of alignment resulting from the anisotropic magnetic susceptibility of the diamagnetic protein. Best fitting of the measured data yields an orientation-independent decrease of 0.11 Hz in the 1JNH splittings at 600 MHz relative to 360 MHz, in perfect agreement with theoretical predictions ...

2009 - Clinical Neurophysiology

Retinotopic mapping of the human visual cortex at a magnetic field strength of 7T

OBJECTIVE fMRI-based retinotopic mapping data obtained at a magnetic field strength of 7T are evaluated and compared to 3T acquisitions. METHODS With established techniques retinotopic mapping data were obtained in four subjects for 25 slices parallel to the calcarine sulcus at 7 and 3T for three voxel sizes (2.5(3), 1.4(3), and 1.1(3)mm(3)) and in two subjects for 49 slices at 7T for 2.5(3)mm(3) voxels. The data were projected to the flattened representation of T1 weighted images acquired at 3T. RESULTS The obtained retinotopic maps allowed for the identification of visual areas in the occipito-parietal cortex. The mean coherence increased with magnetic field strength and with voxel size. At 7T, the occipital cortex could be sampled with high sensitivity in a short single session at high resolution. Alternatively, at lower resolution simultaneous mapping of a great expanse of occipito-parietal cortex was possible. CONCLUSION Retinotopic mapping at 7T aids a detailed description of the visual areas. Here, recent findings of multiple stimulus-driven retinotopic maps along the intraparietal sulcus are supported. SIGNIFICANCE Retinotopic mapping at 7T opens the possibility to detail our understanding of the cortical visual field representations in general and of their plasticity in visual system pathologies.

Intergalactic Magnetic Fields from Quasar Outflows

Cluster Magnetic Fields

PREDICTIONS OF QUASAR CLUSTERING: REDSHIFT, LUMINOSITY, AND SELECTION DEPENDENCE

Cosmological magnetic fields: their generation, evolution and observation

TURBULENCE AND DYNAMO IN GALAXY CLUSTER MEDIUM: IMPLICATIONS ON THE ORIGIN OF CLUSTER MAGNETIC FIELDS

Multiwavelength campaign on Mrk 509 - VI. HST/COS observations of the far-ultraviolet spectrum

Probing the Nature of the Weakest Intergalactic Magnetic Fields with the High-Energy Emission of Gamma-Ray Bursts

Anisotropic AGN Outflows and Enrichment of the Intergalactic Medium

The origin, evolution and signatures of primordial magnetic fields

Magnetism Science with the Square Kilometre Array

Probing Intergalactic Magnetic Fields in the GLAST Era through Pair Echo Emission from TeV Blazars

New constraints on the magnetization of the cosmic web using LOFAR Faraday rotation observations

The origin and evolution of cosmic magnetism

Cosmic Magnetism in Centimeter and Meter Wavelength Radio Astronomy

Magnetizing the Cosmic Web during Reionization

CosmoMHD: A Cosmological Magnetohydrodynamics Code

QUASARS PROBING QUASARS. III. NEW CLUES TO FEEDBACK, QUENCHING, AND THE PHYSICS OF MASSIVE GALAXY FORMATION

Astrophysics in 2001

The evolution of structure and feedback with Arcus

Primordial helical magnetic fields from inflation?

The Gamma-ray Window to Intergalactic Magnetism