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Magneto-encephalography (MEG) was used to examine the cerebral response to affective non-verbal vocalizations (ANVs) at the single-subject level. Stimuli consisted of non-verbal affect bursts from the Montreal Affective Voices morphed to parametrically vary acoustical structure and perceived emotional properties. Scalp magnetic fields were recorded in three participants while they performed a 3-alternative forced choice emotion categorization task (Anger, Fear, Pleasure). Each participant performed more than 6000 trials to allow single-subject level statistical analyses using a new toolbox which implements the general linear model (GLM) on stimulus-specific responses (LIMO-EEG). For each participant we estimated "simple" models [including just one affective regressor (Arousal or Valence)] as well as "combined" models (including acoustical regressors). Results from the "simple" models revealed in every participant the significant early effects (as early as ∼100ms after onset) of Valence and Arousal already reported at the group-level in previous work. However, the "combined" models showed that few effects of Arousal remained after removing the acoustically-explained variance, whereas significant effects of Valence remained especially at late stages. This study demonstrates (i) that single-subject analyses replicate the results observed at early stages by group-level studies and (ii) the feasibility of GLM-based analysis of MEG data. It also suggests that early modulation of MEG amplitude by affective stimuli partly reflects their acoustical properties. [ABSTRACT FROM AUTHOR]

Neurons in the visual system vary widely in the spatiotemporal properties of their receptive fields (RFs), and understanding these variations is key to elucidating how visual information is processed. We present a new approach for mapping RFs based on the filtered back projection (FBP), an algorithm used for tomographic reconstructions. To estimate RFs, a series of bars were flashed across the retina at pseudo-random positions and at aminimum of five orientations. We apply this method to retinal neurons and show that it can accurately recover the spatial RF and impulse response of ganglion cells recorded on a multi-electrode array. We also demonstrate its utility for in vivo imaging by mapping the RFs of an array of bipolar cell synapses expressing a genetically encoded Ca2+ indicator. We find that FBP offers several advantages over the commonly used spike-triggered average (STA): (i) ON and OFF components of a RF can be separated; (ii) the impulse response can be reconstructed at sample rates of 125 Hz, rather than the refresh rate of a monitor; (iii) FBP reveals the response properties of neurons that are not evident using STA, including those that display orientation selectivity, or fire at low mean spike rates; and (iv) the FBP method is fast, allowing the RFs of all the bipolar cell synaptic terminals in a field of view to be reconstructed in under 4 min. Use of the FBP will benefit investigations of the visual system that employ electrophysiology or optical reporters to measure activity across populations of neurons. [ABSTRACT FROM AUTHOR]

Time-varying magnetic stimulation can induce electric fields in the neuronal tissues and has been increasingly used in medical researches and clinical applications, such as peripheral nerve stimulation and transcranial magnetic stimulation. An acupuncture point (called acupoint) is a specific point in the human body with high sensitivity to various stimuli. In this paper, different-frequency magnetic stimulation was used to stimulate the Neiguan (PC6) acupoint. The 64 channel electroencephalogram (EEG) signals were recorded before, during, and after stimulation to determine whether magnetic stimulation at PC6 point would modulate cortex excitability and whether the frequency parameter would impact stimulation effects. The results showed that when the stimulation frequency was 0.5 Hz, the amplitudes of brain evoked potentials were much bigger and more cortex areas were activated. It suggested that 0.5 Hz magnetic stimulation at the PC6 acupoint could possess more complicated effects. [ABSTRACT FROM AUTHOR]

This paper describes a novel approach to designing a high-current magnetic field generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. Challenges for robust and practical design are introduced. A few of the main possible solutions for designing versatile and powerful pulses are introduced and discussed. Finally, future improvement in functionality of the HCMFG is proposed. [ABSTRACT FROM AUTHOR]

In order to optimize the preformation of the field free line (FFL) for human-targeted clinical magnetic particle imaging, an advanced design for the generation of FFL with two pairs of concentric circular coils is proposed in this paper. Simulation study using FEM software was performed to study the relationship between the coil geometric parameters and the FFL quality. Particle-swarm optimization algorithm was performed to optimize the coil topology to gain a highly homogenous gradient field. The results demonstrated that high quality FFL can be generated by the concentric circular coil pairs and the topology of the concentric circle coils is also promising for the human target clinical usage, with the rotation of the FFL just perpendicular to the movement direction of patients inside. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the effects of sub- or supra-threshold low-frequency repetitive transcranial magnetic stimulation (rTMS) on cognitive function. The magnetic stimulation was delivered at 1 Hz to the left supramarginal gyrus, which is considered to be the area of origin of the P300 event-related potential component. The intensity of magnetic stimulation was 80% or 120% of motor threshold, and 100 magnetic pulses were applied. The auditory oddball task, consisting of tone burst waves, was used to elicit P300 before and shortly after magnetic stimulation. We found that P300 latency depended on the intensity of the 1 Hz magnetic stimulation. With subthreshold rTMS, P300 latency was significantly shortened compared with before magnetic stimulation by around 10 ms (Cz: \(p<0.05\) ) on average. With the suprathreshold rTMS, the latency was significantly delayed compared with before magnetic stimulation by around 10 ms (Cz: \(p< 0.01\) ) on average. The facilitation of cortical excitability by rTMS may induce the shortening of P300 latency, whereas the inhibition of cortical excitability may induce its delay. Thus, P300 latency can be altered by both sub- and supra-threshold low-frequency magnetic stimulation. [ABSTRACT FROM AUTHOR]

Chronic cranial windows have been instrumental in advancing optical studies in vivo, permitting long-term, high-resolution imaging in various brain regions. However, once a window is attached it is difficult to regain access to the brain under the window for cellular manipulations. Here we describe a simple device that combines long term in vivo optical imaging with direct brain access via glass or quartz pipettes and metal, glass, or quartz electrodes for cellular manipulations like dye or drug injections and electrophysiological stimulations or recordings while keeping the craniotomy sterile. Our device comprises a regular cranial window glass coverslip with a drilled access hole later sealed with biocompatible silicone. This chronic cranial window with access port is cheap, easy to manufacture, can be mounted just as the regular chronic cranial window, and is self-sealing after retraction of the pipette or electrode. We demonstrate that multiple injections can be performed through the silicone port by repetitively bolus loading calcium sensitive dye into mouse barrel cortex and recording spontaneous cellular activity over a period of weeks. As an example to the extent of its utility for electrophysiological recording, we describe how simple removal of the silicone seal can permit patch pipette access for whole-cell patch clamp recordings in vivo. During these chronic experiments we do not observe any infections under the window or impairment of animal health. [ABSTRACT FROM AUTHOR]

We discuss in this paper the first detailed environmental magnetic record of glacial–interglacial climatic variations in the Schirmacher Oasis, East Antarctica. We determined environmental magnetic properties and inter-parametric ratios (χ lf , χ fd %, χ ARM , SIRM, χ ARM /SIRM, χ ARM /χ lf , χ ARM /χ fd , SIRM/χ lf , S-ratio and HIRM) for sediment samples of a core from the Sandy Lake. Accelerator mass spectrometer (AMS) 14 C dates were obtained on the organic matter from bulk sediment samples. The sediment core spans the past ~ 42.5 cal. ka B.P. The magnetic minerals are mainly detrital and catchment-derived, as there is no evidence for the presence of authigenic greigite, bacterial magnetite or diagenetic dissolution. The last glacial period is characterized by a high concentration of ferrimagnetic minerals such as titanomagnetite (high values of χ lf, SIRM etc.) and coarse magnetic grain size (low χ ARM /SIRM and χ ARM /χ lf values and high S-ratio values). Deglaciation in the Schirmacher Oasis began around 21 cal. ka B.P. as suggested by the low magnetic mineral concentration. The Holocene period is characterized by relatively warm climatic events as seen in the low values of magnetic susceptibility which is primarily contributed by fine-grained titanomagnetite resulting from pedogenesis (high χ fd % values). Several of the relatively warm and cold events that we deciphered from the environmental magnetic data are correlatable with lake sediments from the Schirmacher Oasis and other ice-free areas in East Antarctica and from ice-core records on the Antarctic Plateau. [ABSTRACT FROM AUTHOR]

Plenty of evidence has implied that animals like pigeons and sea turtles utilize geomagnetic information for long-distance migration and homing. In this paper, we conduct an ab initio investigation to imitate a migratory animal's geomagnetic homing across a long distance over the surface of the Earth. Based on a simple assumption that such animals have a natural ability to sense and compare the included angle between the vector geomagnetic field (GF) and a specific geographic direction such as the due north, we show that a long-distance geomagnetic navigation (GN) can be accomplished without any assistance of prestored geomagnetic and geographic information, as long as the navigation is inside a vast area where such a spatial angle can uniquely determine a geographic location. Without any requirement of measuring the strength of the GF, this GN will not be visibly affected by the recurrent fluctuation of the GF that severely hampers traditional GN. By introducing the extended-Kalman-filter algorithm, it is able to find a shortcut in the geomagnetic space, overcoming interferences of strong Gaussian and local-area geomagnetic anomaly. We believe that the proposed approach will find a wide range of potential applications in global, local, and indoor navigations based on magnetic field in the future. [ABSTRACT FROM PUBLISHER]

High gradient magnetic separation (HGMS) has been established since the early 1970s. A more recent application of these systems is the use in bioprocesses. To integrate the HGMS in a fermentation process, it is necessary to optimize the separation matrix with regard to the magnetic separation characteristics and permeability of the non-magnetizable components of the fermentation broth. As part of the work presented here, a combined fluidic and magnetic force finite element model simulation was created using the software COMSOL Multiphysics and compared with separation experiments. Finally, as optimal lattice orientation of the separation matrix, a transversal rhombohedral arrangement was defined. The high suitability of the new filter matrix has been verified by separation experiments. [ABSTRACT FROM PUBLISHER]

Biomagnetic monitoring of tree leaf deposited particles has proven to be a good indicator of the ambient particulate concentration. The objective of this study is to apply this method to validate a local-scale air quality model (ENVI-met), using 96 tree crown sampling locations in a typical urban street canyon. To the best of our knowledge, the application of biomagnetic monitoring for the validation of pollutant dispersion modeling is hereby presented for the first time. Quantitative ENVI-met validation showed significant correlations between modeled and measured results throughout the entire in-leaf period. ENVI-met performed much better at the first half of the street canyon close to the ring road (r = 0.58-0.79, RMSE = 44-49%), compared to second part (r = 0.58-0.64, RMSE = 74-102%). The spatial model behavior was evaluated by testing effects of height, azimuthal position, tree position and distance from the main pollution source on the obtained model results and magnetic measurements. Our results demonstrate that biomagnetic monitoring seems to be a valuable method to evaluate the performance of air quality models. Due to the high spatial and temporal resolution of this technique, biomagnetic monitoring can be applied anywhere in the city (where urban green is present) to evaluate model performance at different spatial scales. [ABSTRACT FROM AUTHOR]

Previous research has shown that positive mood may broaden attention, although it remains unclear whether this effect has a perceptual or a postperceptual locus. In this study, we addressed this question using high-density event-related potential methods. We randomly assigned participants to a positive or a neutral mood condition. Then they performed a demanding oddball task at fixation (primary task ensuring fixation) and a localization task of peripheral stimuli shown at three positions in the upper visual field (secondary task) concurrently. While positive mood did not influence behavioral performance for the primary task, it did facilitate stimulus localization on the secondary task. At the electrophysiological level, we found that the amplitude of the C1 component (reflecting an early retinotopic encoding of the stimulus in V1) was enhanced in the positive, as compared with the neutral, mood group. Importantly, this effect appeared to be largely automatic, because it occurred regardless of the task relevance of the peripheral stimulus and prior to top-down gain control effects seen at the level of the subsequent P1 component. This early effect was also observed irrespective of a change of the target-related P300 component (primary task) by positive mood. These results suggest that positive mood can automatically boost the spatial encoding of peripheral stimuli early on following stimulus onset. This effect can eventually underlie the broadening of spatial attention, which has been associated with this specific mood state. [ABSTRACT FROM AUTHOR]

The magnetic sensor is used in various fields such as industrial, automobile, IT and biomagnetism. The MI sensor is a magnetic sensor based on the MI (Magneto Impedance) effect discovered by K. Mori etal. in 1993. The MI element with a pickup coil produced by a plating process is used in electromagnetic compasses. Although it can detect 1-1000 µT level, higher performance in sensitivity and noise level is required. Here, the effect of wire length, magnetic property of the amorphous magnetic wire, the number of coil turns and number of cores on the sensor characteristics was investigated. Then based on the above investigations, the designed MI element was test produced. It was found that the designed element shows dramatically higher sensitivity and 1/100 noise, as compared to the currently used MI element (AMI306). [ABSTRACT FROM AUTHOR]

A fully integrated low noise superconducting quantum interference device (SQUID) in a magnetometer configuration is presented. An intrinsic high voltage responsivity as high as 500 µV/Φ0 has been obtained by introducing a resonance in the voltage - magnetic flux characteristic. This resonance is induced by an integrated superconducting coil surrounding the pick-up coil and connected to one end of the SQUID output. The SQUID magnetometer exhibits a spectral density of magnetic field noise as low as 3 fT/Hz1/2. In order to verify the suitability of the magnetometer, measurements of bandwidth and slew rate have been performed and compared with those of the same device without the resonance and with additional positive feedback. Due to their good characteristics such devices can be employed in a large number of applications including biomagnetism. [ABSTRACT FROM AUTHOR]

Objective Magnetoencephalography (MEG) signals had previously been hypothesized to have negligible sensitivity to skull defects. The objective is to experimentally investigate the influence of conducting skull defects on MEG and EEG signals. Methods A miniaturized electric dipole was implanted in vivo into rabbit brains. Simultaneous recording using 64-channel EEG and 16-channel MEG was conducted, first above the intact skull and then above a skull defect. Skull defects were filled with agar gels, which had been formulated to have tissue-like homogeneous conductivities. The dipole was moved beneath the skull defects, and measurements were taken at regularly spaced points. Results The EEG signal amplitude increased 2-10 times, whereas the MEG signal amplitude reduced by as much as 20%. The EEG signal amplitude deviated more when the source was under the edge of the defect, whereas the MEG signal amplitude deviated more when the source was central under the defect. The change in MEG field-map topography (relative difference measure, RDM∗=0.15) was geometrically related to the skull defect edge. Conclusions MEG and EEG signals can be substantially affected by skull defects. Significance MEG source modeling requires realistic volume conductor head models that incorporate skull defects. [ABSTRACT FROM AUTHOR]

The aromaticity of porphyrazine (PA) and its three triazoleporphyrazine (TAP) tautomers as well as their metal complex compounds was examined using the TRE (topological resonance energy) and the MRE (magnetic resonance energy) methods. Their local aromaticity was studied using the BRE (bond resonance energy) and the CRE (circuit resonance energy) methods. The relationship between the global and local aromaticity of TAPs and the position of the substituted nitrogen atom is discussed. The results of these calculations are compared with those provided by other aromaticity indices. Our TRE and MRE results indicate that PA and TAPs possess lower global aromaticity than porphyrin. Our BRE and CRE results show that global aromaticity is closely associated primarily with the five-membered rings which contain the –NH– pyrrolic rings, and the [18]-annulene-like conjugation pathway is not crucial for determining the aromaticity of the entire π-system. Moreover, the circuit-current susceptibility (χi) and ring current (RC) were obtained using the graph-theoretical method. The χi and RC results show that all the compounds sustain a diatropic current along the macrocycle and this current is bifurcated when it passes through every five-membered ring. Ring current maps reveal that in the five-membered rings, the ring current prefers to pass through the C–C bond when the ring contains an –NH– group, and through the C–N bond when the ring does not contain an –NH– group. [ABSTRACT FROM AUTHOR]

To better understand the physiological mechanisms responsible for the differential motor cortex functioning in aging, we used transcranial magnetic stimulation to investigate interhemispheric interactions and cortical representation of hand muscles in the early phase of physiological aging, correlating these data with participants' motor abilities. Right-handed healthy subjects were divided into a younger group (n = 15, mean age 25.4±1.9 years old) and an older group (n = 16, mean age 61.1±5.1 years old). Activity of the bilateral abductor pollicis brevis (APB) and abductor digiti minimi (ADM) was recorded. Ipsilateral silent period (ISP) was measured in both APBs. Cortical maps of APB and ADM were measured bilaterally. Mirror movements (MM) were recorded during thumb abductions. Motor abilities were tested using Nine Hole Peg Test, finger tapping, and grip strength. ISP was reduced in the older group on both sides, in terms of duration (p = 0.025), onset (p = 0.029), and area (p = 0.008). Resting motor threshold did not differ between groups. APB and ADM maps were symmetrical in the younger group, but were reduced on the right compared to the left hemisphere in the older group (p = 0.008). The APB map of the right hemisphere was reduced in the older group compared to the younger (p = 0.021). Older subjects showed higher frequency of MM and worse motor abilities (p <0.001).The reduction of right ISP area correlated significantly with the worsening of motor performances. Our results showed decreased interhemispheric interactions in the early processes of physiological aging and decreased cortical muscles representation over the non-dominant hemisphere. The decreased ISP and increased frequency of MM suggest a reduction of transcallosal inhibition. These data demonstrate that early processes of normal aging are marked by a dissociation of motor cortices, characterized, at least, by a decline of the non-dominant hemisphere, reinforcing the hypothesis of the right hemi-aging model. [ABSTRACT FROM AUTHOR]

Cortical plasticity, including long-term potentiation (LTP)-like plasticity, can be assessed non-invasively with repetitive transcranial magnetic stimulation (rTMS) protocols. In this study, we examined age differences in responses to intermittent theta burst stimulation (iTBS) in a group of 20 young and 18 healthy older adults. Because the cholinergic system plays a role in the neural processes underlying learning and memory, including LTP, we also investigated whether short latency afferent inhibition (SAI), a neurophysiological marker of central cholinergic activity, would be associated with age-related differences in LTP-like plasticity induced by iTBS. Methods: SAI was first assessed by examining the modulation of motor evoked potentials (MEPs) in response to median nerve conditioning 20 ms prior to TMS. Participants then underwent iTBS (3 pulses at 50 Hz every 200 ms for 2 s with 8 s between trains, repeated 20 times). MEP responses (120% resting motor threshold (RMT)) were assessed immediately after iTBS and 5, 10, and 20 min post-application. Results: Responses to iTBS were quite variable in both age groups, with only approximately 60% of the participants (n = 13 young and 10 older adults) showing the expected facilitation of MEP responses. There were no significant age group differences in MEP facilitation following iTBS. Although older adults exhibited reduced SAI, individual variations were not associated with susceptibility to express LTP-like induced plasticity after iTBS. Conclusion: Overall, these results are consistent with reports of high inter-individual variability in responses to iTBS. Although SAI was reduced in older adults, consistent with a deterioration of the cholinergic system with age, SAI levels were not associated with LTP-like plasticity as assessed with iTBS. [ABSTRACT FROM AUTHOR]

Abstract: Increasing the spatial resolution of air quality assessments in urban environments is designated as a priority area within current research. Biomagnetic monitoring and air quality modelling are both methodologies able to provide information about the spatial variation of particulate pollutant levels within urban environments. This study evaluates both methods by comparing results of a biomagnetic monitoring campaign at 110 locations throughout Antwerp, Belgium, with modelled pollutant concentrations of PM10 and NO2. Due to the relation of biomagnetic monitoring with railway traffic, analyses were conducted for both all locations (n = 110) and railway traffic excluded locations (n = 67). While the general spatial variation, land use comparison and the relation with traffic intensity were comparable between the two applied methodologies, an overall bad agreement is obtained when the methodologies are correlated to each other. While no correlation was found between SIRM and PM10 results (p = 0.75 for n = 110 and p = 0.68 for n = 67), a significant but low (r ≤ 0.33) correlation was found between SIRM and NO2 (p < 0.01 for n = 110 and p = 0.04 for n = 67). While biomagnetic monitoring and air quality modelling are both able to provide high spatial resolution information about urban pollutant levels, we need to take into account some considerations. While uncertainty in the biomagnetic monitoring approach might arise from the processes that determine leaf particulate deposition and the incorporation of multiple emission sources with diverging magnetic composition, air quality modelling remains an approximation of reality which implies its dependency on accurate emission factors, implication of atmospheric processes and representation of the urban morphology. Therefore, continuous evaluation of model performance against measured data is essential to produce reliable model results. Nevertheless, this study demonstrates that in addition to telemetric monitoring networks, the combination of both air quality modelling and biomagnetic monitoring is a valuable approach to provide insights into the variation of atmospheric pollutants in heterogeneous urban environments. [Copyright &y& Elsevier]

A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m x 1 m x 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) [ABSTRACT FROM AUTHOR]

The goal of this study was to develop methods for simultaneously acquiring electrophysiological data during high-definition transcranial direct current stimulation (tDCS) using high-resolution electroencephalography (EEG). Previous studies have pointed to the after-effects of tDCS on both motor and cognitive performance, and there appears to be potential for using tDCS in a variety of clinical applications. However, little is known about the real-time effects of tDCS on rhythmic cortical activity in humans due to the technical challenges of simultaneously obtaining electrophysiological data during ongoing stimulation. Furthermore, the mechanisms of action of tDCS in humans are not well understood. We have conducted a simultaneous tDCS–EEG study in a group of healthy human subjects. Significant acute and persistent changes in spontaneous neural activity and event-related synchronization (ERS) were observed during and after the application of high-definition tDCS over the left sensorimotor cortex. Both anodal and cathodal stimulation resulted in acute global changes in broadband cortical activity which were significantly different than the changes observed in response to sham stimulation. For the group of eight subjects studied, broadband individual changes in spontaneous activity during stimulation were apparent both locally and globally. In addition, we found that high-definition tDCS of the left sensorimotor cortex can induce significant ipsilateral and contralateral changes in event-related desynchronization and ERS during motor imagination following the end of the stimulation period. Overall, our results demonstrate the feasibility of acquiring high-resolution EEG during high-definition tDCS and provide evidence that tDCS in humans directly modulates rhythmic cortical synchronization during and after its administration. [ABSTRACT FROM PUBLISHER]

Whether a cortical drive to one limb modulates interhemispheric inhibition (IHI) from the active targeting to the non-active motor cortex (M1) remained unclear. The present study using a conditioning-test transcranial magnetic stimulation (TMS) paradigm aimed to directly demonstrate the modulation of IHI during unilateral voluntary or imagined movement in humans. Subjects were asked to actually perform right index-finger abduction (10-70 % of the maximum voluntary contraction) or to imagine the movement. Conditioning and test TMS with an interstimulus interval of 5, 10, and 15 ms were applied over the left and right M1, respectively, and the test motor evoked potential (MEP) was recorded from the left first dorsal interosseous (FDI) muscle. The conditioning TMS intensity was adjusted ranging from 0.6 to 1.4 (in 0.2 steps) times the resting motor threshold (rMT). With test TMS alone, MEP in the left FDI muscle significantly increased during voluntary or imagined movement of the right index-finger. MEP amplitude was significantly reduced in proportion to increments of the conditioning TMS intensity at rest (1.2 and 1.4 times the rMT, P < 0.05, respectively). Importantly, the MEP inhibition was markedly enhanced during voluntary or imagined movement in comparison with that at rest. The regression analysis revealed that IHI varied depending on the intensity of the impulses conveyed from left to right M1, but not on the corticospinal excitability of the active right hand. Our results suggest that IHI from the active to non-active M1 is enhanced during unilateral volitional motor activity. [ABSTRACT FROM AUTHOR]

In the framework of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) project, the US LHC accelerator research program is developing high-gradient, large-aperture \Nb3 \Sn quadrupole magnets for the LHC interaction regions. The fabrication and tests of a first series of 120-mm-aperture “HQ01” coils revealed design issues that resulted in limited performance. A second series of coils was fabricated in which a number of improved features were implemented (HQ02 coils). The improvements were partly validated with the successful test of an HQ02 coil in a mirror structure, which reached 97% of the short sample. Here, we review the modifications in the coil design and the coil fabrication process, report the issues met during the fabrication, give details of the few differences that exist within the set of HQ02 coils, and discuss a list of further improvements that will be implemented in a third series of HQ coils. [ABSTRACT FROM PUBLISHER]

Contactless method for manipulation of polar or polarisable micro and nanoscale particles based on the dielectrophoresis force exerted by the induced electric field in high pulsed magnetic field is presented in this study. Finite element method analysis of the magnetic and resulting induced electric fields is carried out. The structure of the magnetic field generator that was based on a controlled frequency spark gap, and the structure of the coil that was used as a load are described. Experimental data showing positive dielectrophoresis on the Jurkat T‐lymphoblasts is presented. The study discusses further developments of the technique, its limitations and possible applications. [ABSTRACT FROM AUTHOR]

Biomagnetic monitoring of urban tree leaves has proven to be a good estimator of ambient particulate matter. We evaluated its relevancy by determining leaf area normalised weight (mg m−2) and SIRM (A) of leaf-deposited particles within three different size fractions (>10 μm, 3–10 μm and 0.2–3 μm) and the SIRM of the leaf-encapsulated particles. Results showed that throughout the in-leaf season, the trees accumulated on average 747 mg m−2 of dust on their leaves, of which 74 mg m−2 was within the 0.2–10 μm (∼PM10) size range and 40 mg m−2 within the 0.2–3 μm (∼PM3) size range. A significant correlation between the SIRM and weight of the surface-deposited particles confirms the potential of biomagnetic monitoring as a proxy for the amount of leaf-deposited particles. Spatial variation of both SIRM and weight throughout the street canyon suggests traffic and wind as key factors for respectively the source and distribution of urban particulates. [Copyright &y& Elsevier]

Transcranial magnetic stimulation (TMS) holds great potential in the treatment of a host of neurological conditions due to its ability to focally modulate--suppress or enhance--activity in targeted cortical brain regions and modify activity across specific brain networks. Results from early trials in a number of neurological indications are presented, including stroke rehabilitation, Parkinson's disease, tinnitus, chronic pain, migraine, and epilepsy. We emphasize both the challenges, such as the limited efficacy to date in tinnitus, as well as the opportunities, such as the use of TMS in epilepsy caused by focal/cortical lesions. However, to establish TMS as a clinically valuable neurological therapeutic intervention, a number of hurdles must be overcome, including accurate targeting of the treatment, characterization of its therapeutic benefit for specific patients/symptoms, proof of efficacy in multicenter trials that are adequately blinded and powered, proof of the durability of the effects, and assessment of potential adverse effects of cumulative dose and repeated application. [Psychiatr Ann. 2014; 44(6):299-304.] [ABSTRACT FROM AUTHOR]

Repetitive transcranial magnetic stimulation (rTMS) offers a noninvasive, safe, and well-tolerated method of neuromodulation. We reviewed existing literature covering rTMS treatment of posttraumatic stress disorder (PTSD), schizophrenia, dementia, bipolar disorder, obsessive-compulsive disorder (OCD), autism spectrum disorder (ASD), and attention-deficit/ hyperactivity disorder (ADHD). Data for PTSD suggest the right dorsolateral prefrontal cortex may be a potential treatment site. rTMS in schizophrenia suggests high-frequency stimulation of the left DLPFC may have some benefit for negative symptoms, and low-frequency stimulation of the primary auditory cortex may assist with auditory hallucinations. The role of rTMS in the diagnosis and treatment of dementia is promising, but further studies are needed. Data for bipolar disorder are inconsistent across the spectrum of mood states. Treatment of OCD by stimulation of the supplementary motor area may have promise. Data are lacking regarding use of rTMS for ASD or ADHD to draw definitive conclusions. [Psychiatr Ann. 2014; 44(6):293-298.] [ABSTRACT FROM AUTHOR]

Transcranial magnetic stimulation (TMS) provides psychiatrists with a new treatment offering in clinical practice. Providing an office-based procedure is new for psychiatrists, and incorporating this procedure into practice has brought new challenges. The clinical delivery of TMS has various possibilities for office operations, management, and overall structure. Different clinical models and providers include traditional private practices, device partnerships, networked practices, institutions, and dedicated TMS centers. Practical considerations of using TMS, such as office set-up, training, staffing, and safety considerations are reviewed. More insurance plans are now covering TMS, but usually only after failure of multiple antidepressant medications. Criteria vary, but they play a large role in shaping the practice. TMS treatments can be clinically categorized as acute, tapering, booster, or maintenance treatments, depending on when they are being delivered. [Psychiatr Ann. 2014; 44(6):305-309.] [ABSTRACT FROM AUTHOR]

A new method for the imaging of cardiac electrical activity in patients with complete right bundle branch block (CRBBB) or complete left bundle branch block (CLBBB) is investigated using magnetocardiographic recordings of the surface of the body. This is based on the assumption that an equivalent single-current dipole moves along the unblocked bundle branch, whose position in the measurement plane is expressed in terms of the maximum and minimum, as well as the maximum gradient value of the measured magnetic field. The trajectory of the moving dipole on the measurement plane is indicative of the excitation conduction of the CRBBB or CLBBB subject during ventricular depolarization and repolarization, which is deduced by comparing each change between the dipole moment and the maximum current density in a corresponding pseudo-current density map. In summary, this method can distinguish CRBBB from CLBBB subjects by means of the dipole depth and two dipole moment components. The possibility of visualizing the excitation conduction in a CRBBB or CLBBB subject during ventricular depolarization and repolarization is then discussed. [ABSTRACT FROM AUTHOR]

SUMMARY A mathematical model for the description of biomagnetic fluid flow exposed to a magnetic field that accounts for both electric and magnetic properties of the biofluid is presented. This is achieved by adding the Lorentz and magnetization forces in the Navier-Stokes equations. To demonstrate the effects of magnetic fields, we consider the case of laminar, incompressible, viscous, the steady flow of a Newtonian biomagnetic fluid (i) between two parallel plates; and (ii) through a straight rigid tube with a 60% in diameter, 84% on area, axisymmetric stenosis. Two external magnetic fields were investigated: one produced by an infinite wire carrying constant current, and a dipole-like field. We show, numerically and analytically, that the wire produces an irrotational force that, independent of its intensity, only alters the pressure leaving the velocity field unaffected. In contrast, when the fluid is exposed to the dipole-like field, which generates a rotational force, then both pressure and velocity can be strongly influenced even at moderate field strengths. Similar trends were obtained when a time varying flow is simulated through the axisymmetric stenosis in the presence of the dipole-like rotational magnetic field. It is expected that our findings could have important applications in blood flow control. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The magnetic impedance (MI) of film elements in the form of meanders with a [Fe19Ni81]/Cu]/Fe19Ni81/Cu/[Fe19Ni81/Cu]/Fe19Ni81 layered structure and variable geometry is studied. For the best meanders (having a maximal MI of up to 125% and an MI maximal sensitivity of about 30%/Oe), the influence of stray magnetic fields is determined. The stray fields are produced by spherical iron particles 500 μm in diameter and ferrofluids containing iron oxide nanoparticles. The feasibility of detecting intricately configured stray fields from a set of ferromagnetic spheres arranged on the surface of an MI element is demonstrated. The sensitivity of film meander MI elements to nonuniform external magnetic fields is simulated. The results of this work may be helpful in developing special-purpose magnetic sensors intended for micropositioning, nondestructive testing, and biomagnetic detection. [ABSTRACT FROM AUTHOR]

Residual Dipolar Couplings (RDCs) are a source of NMR data that can provide a powerful set of constraints on the orientation of inter-nuclear vectors, and are quickly becoming a larger part of the experimental toolset for molecular biologists. However, few reliable protocols exist for the determination of protein backbone structures from small sets of RDCs. DynaFold is a new dynamic programming algorithm designed specifically for this task, using minimal sets of RDCs collected in multiple alignment media. DynaFold was first tested utilizing synthetic data generated for the -, α-α, and - vectors of 1BRF, 1F53, 110M, and 3LAY proteins, with up to ±1 Hz error in three alignment media, and was able to produce structures with less than 1.9 Å of the original structures. DynaFold was then tested using experimental data, obtained from the Biological Magnetic Resonance Bank, for proteins PDBID:1P7E and 1D3Z using RDC data from two alignment media. This exercise yielded structures within 1.0 Å of their respective published structures in segments with high data density, and less than 1.9 Å over the entire protein. The same sets of RDC data were also used in comparisons with traditional methods for analysis of RDCs, which failed to match the accuracy of DynaFold's approach to structure determination. [ABSTRACT FROM AUTHOR]

Magnetoencephalography (MEG), which acquires neuromagnetic fields in the brain, is a useful diagnostic tool in presurgical evaluation of epilepsy. Previous studies have shown that MEG affects the planning intracranial electroencephalography placement and correlates with surgical outcomes by using a single dipole model. Spatiotemporal source analysis using distributed source models is an advanced method for analyzing MEG, and has been recently introduced for analyzing epileptic spikes. It has advantages over the conventional single dipole analysis for obtaining accurate sources and understanding the propagation of epileptic spikes. In this article, we review the source analysis methods, describe the techniques of the distributed source analysis, interpretation of source distribution maps, and discuss the benefits and feasibility of this method in evaluation of epilepsy. [ABSTRACT FROM AUTHOR]

Highlights: [•] In this paper we have considered real, clinical scenarios in magnetoencephalography. [•] We improve the performance of methods such as LCMV by using clustering techniques. [•] The basis for these clustering techniques is the covariance matrix diagonalization. [•] The eigenspace/eigenvector corresponding to the highest eigenvalue must be used. [•] The projection of this eigenspace across trials provides the dissimilarity matrix. [ABSTRACT FROM AUTHOR]

The assessment of the dynamic status of a network is currently unavailable. It is important to know how far a network is away from its equilibrium (as an indicator of instability) at a moment, and over periods of time. Here, we introduce the Departure from Network Equilibrium (DNE), a new measure of instantaneous network dynamics. DNE is simple, fast to compute, and scalable with network size. We present the results of its application on white noise networks (as a basis) and on networks derived from magnetoencephalographic recordings from the human brain. [ABSTRACT FROM AUTHOR]

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 applied magnetic field. Conclusions: A simple treatment of Néel relaxation using the common zero-field relaxation time overestimates the relaxation time of the magnetization in situations relevant for MPI and MPS. For sinusoidally driven (or ramped) systems, whether or not a particular relaxation mechanism dominates or is even relevant depends on the magnetic field strength, the frequency (or ramp time), and the phase of the magnetization relative to the applied magnetic field. [ABSTRACT FROM AUTHOR]