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Atomic magnetometers are emerging as an alternative to SQUID magnetometers for detection of biological magnetic fields. They have been used to measure both the magnetocardiography (MCG) and magnetoencephalography (MEG) signals. One of the virtues of the atomic magnetometers is their ability to operate as a multi-channel detector while using many common elements. Here we study two configurations of such a multi-channel atomic magnetometer optimized for MEG detection. We describe measurements of auditory evoked fields (AEF) from a human brain as well as localization of dipolar phantoms and auditory evoked fields. A clear N100m peak in AEF was observed with a signal-to-noise ratio of higher than 10 after averaging of 250 stimuli. Currently the intrinsic magnetic noise level is 4fTHz−1/2 at 10Hz. We compare the performance of the two systems in regards to current source localization and discuss future development of atomic MEG systems. •MEG signal detection and localization with a multi‐channel atomic magnetometer•Two different configurations measuring radial and tangential fields were studied.•Optimization of sensor configuration with phantom studies•Discussion of unique aspects of atomic magnetometer operation for MEG

Nuclear Quadrupole Resonance (NQR) spectroscopy has been known for 70 years. It is suitable for the study of measured (poly)crystalline chemical compounds containing quadrupole nuclei (nuclei with spin I ≥ 1) where the characteristic NQR frequencies represent the fingerprints of these compounds. In several cases, 14N NQR can distinguish between the polymorphic crystalline phases of active pharmaceutical ingredients (APIs). In order to further stimulate 14N NQR studies, we review here several results of API polymorphism studies obtained in Ljubljana laboratories: (a) In sulfanilamide, a clear distinction between three known polymorphs (α, β, γ) was demonstrated. (b) In famotidine, the full spectra of all seven different nitrogen positions were measured; two polymorphs were distinguished. (c) In piroxicam, the 14N NQR data helped in confirming the new polymorphic form V. (d) The compaction pressure in the tablet production of paracetamol, which is connected with linewidth change, can be used to distinguish between producers of paracetamol. We established that paracetamol in the tablets of six different manufacturers can be identified by 14N NQR linewidth. (e) Finally, in order to get an extremely sensitive 14N NQR spectrometer, the optical detection of the 14N NQR signal is mentioned.

Most non-invasive blood pressure measurements are based on either the auscultatory or the oscillometric technique. In this study, we performed an extensive analysis of the signals, i.e., responses of a microphone implanted in the cuff and pressure changes in the cuff, which can be recorded during such measurements. We applied several methods to separate the cuff deflation from the arterial pressure pulses, as well as to separate the microphone data into an audible part (Korotkoff sounds) and a low frequency part. The oscillometric technique is based on some empirically derived criteria applied to the oscillometric index, which is defined as a certain characteristic physical property of pressure pulses. In addition to the pressure pulses, which are a typical physical property used for the oscillometric index, we also used in this study other properties such as a time derivative and an audible part of data measured by a microphone implanted in the cuff (Korotkoff sounds). We performed a case study of 23 healthy subjects to evaluate the influence of different presentations of the oscillometric index on known height-based and slope-based empirical algorithms for the automatic determination of the systolic and diastolic blood pressures.

We present results of our study in localization of the auditory evoked magnetic field measured by a noncryogenic potassium vapour atomic magnetometer (PVAM) [5]. The magnetometer was operating in a spin-exchange relaxation-free (SERF) regime at low magnetic flux densities and high alkali-metal vapour density [1]. Audio stimulation of short 1 kHz pulse trains was applied by a pneumatic earphone. After rejecting the subject's heart-beat signals, signals originating from eye movements and. disturbances due to mechanical vibrations, the N100m could be seen in several channels of the 256-channel atomic magnetometer. This was achieved by combining the magnetometer channels into a gradiometer configuration: one magnetometer was selected as a reference channel and other channels were subtracted from this reference. Using ten gradiometric channels with the best signal-to-noise ratio the approximate source localization of the auditory evoked field was determined by applying two methods: i) non-linear least-square fitting procedure using a current dipole source model in a conducting sphere model, and ii) minimum norm estimation (MNE) method.

Combining the ferroelectric and magnetic components into the solid solution, it is expected to obtain the magneto-electric multiferroic material. Novel bulk ceramic compounds xPZT+(1 − x)PFW, where PZT Pb(Zr0.575Ti0.425)O3 and PFW Pb(Fe2/3W1/3)O3, for x 0.15, 0.20, 0.25, 0.50, 0.70, 0.80 were synthesized and their magnetic investigation was performed, including the measurement of zero-field cooled (ZFC) and field-cooled (FC) magnetization curves, magnetic hysteresis loops and AC susceptibility. In the low temperature region (below 20 K) splitting between the ZFC and FC curves together with the frequency dependent peaks in AC susceptibility point to the glassy freezing/blocking of magnetic moments and magnetic relaxor-like behaviour.

The field application of a 14 N nuclear quadrupole resonance (NQR) detector needed for the detection of different explosives, including trinitrotoluene (TNT), requires the examination of the distribution of 14 N NQR lines stemming from the monoclinic and/or orthorhombic modifications of TNT, as well as from a mixture of both. In this work, 30 different TNT samples up to 70 years old were measured. The main result of this study is that the measured 14 N NQR spectrum is strongly influenced by the environmental conditions to which the explosive was subject during its history.

Recent experiments demonstrate that the concentration of Ca 2+ in cytoplasm of Chara corallina internodal cells plays important role in electrical excitation of the plasma membrane. The concentration of free Ca 2+ in the cytoplasm −[Ca 2+] c is also sensitive to visible light. Both phenomena were simultaneously studied by noninvasive measuring action potential (AP) and magnetic field with a superconducting quantum interference device magnetometer in very close vicinity of electrically excited internodal C. corallina cells. A temporal shift in the depolarization maximum, which progressively occurred after transferring cells from the dark into the light, can be explained by the extended Othmer model. Assuming that the change in membrane voltage during the depolarization part of AP is the direct consequence of an activation of [Ca 2+] c sensitive Cl − channels, the model simulations compare well with the experimental data. We can say that we have an example of electrically elicited AP that is of biochemical nature. Electric and magnetic measurements are in good agreement.

We present results of our study in localization of the auditory evoked magnetic field measured by a noncryogenic potassium vapour atomic magnetometer (PVAM) [5]. The magnetometer was operating in a spin-exchange relaxation-free (SERF) regime at low magnetic flux densities and high alkali-metal vapour density [1]. Audio stimulation of short 1 kHz pulse trains was applied by a pneumatic earphone. After rejecting the subject's heart-beat signals, signals originating from eye movements and. disturbances due to mechanical vibrations, the N100m could be seen in several channels of the 256-channel atomic magnetometer. This was achieved by combining the magnetometer channels into a gradiometer configuration: one magnetometer was selected as a reference channel and other channels were subtracted from this reference. Using ten gradiometric channels with the best signal-to-noise ratio the approximate source localization of the auditory evoked field was determined by applying two methods: i) non-linear least-square fitting procedure using a current dipole source model in a conducting sphere model, and ii) minimum norm estimation (MNE) method. [PUBLICATION ABSTRACT]