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https://www.readbyqxmd.com/read/28328013/validation-of-surface-to-volume-ratio-measurements-derived-from-oscillating-gradient-spin-echo-on-a-clinical-scanner-using-anisotropic-fiber-phantoms
#1
Gregory Lemberskiy, Steven H Baete, Martijn A Cloos, Dmitry S Novikov, Els Fieremans
A diffusion measurement in the short-time surface-to-volume ratio (S/V) limit (Mitra et al., Phys Rev Lett. 1992;68:3555) can disentangle the free diffusion coefficient from geometric restrictions to diffusion. Biophysical parameters, such as the S/V of tissue membranes, can be used to estimate microscopic length scales non-invasively. However, due to gradient strength limitations on clinical MRI scanners, pulsed gradient spin echo (PGSE) measurements are impractical for probing the S/V limit. To achieve this limit on clinical systems, an oscillating gradient spin echo (OGSE) sequence was developed...
March 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28327777/predicting-and-assessing-rupture-in-protein-gels-under-oscillatory-shear
#2
Brice Saint-Michel, Thomas Gibaud, Sébastien Manneville
Soft materials may break irreversibly upon applying sufficiently large shear oscillations, a process whose physical mechanism remains largely elusive. In this work, the rupture of protein gels made of sodium caseinate under an oscillatory stress is shown to occur in an abrupt, brittle-like manner. Upon increasing the stress amplitude, the build-up of harmonic modes in the strain response can be rescaled for all gel concentrations. This rescaling yields an empirical criterion to predict the rupture point way before the samples are significantly damaged...
March 22, 2017: Soft Matter
https://www.readbyqxmd.com/read/28327734/band-edge-oscillator-strength-of-colloidal-cdse-cds-dot-in-rods-comparison-of-absorption-and-time-resolved-fluorescence-spectroscopy
#3
I Angeloni, W Raja, A Polovitsyn, F De Donato, R Proietti Zaccaria, I Moreels
We studied the oscillator strength fgap of the band gap transition in heteronanocrystals (hNCs) with a spherical CdSe core embedded in an elongated CdS shell. A comparison with fgap of core-only CdSe NCs confirmed a reduction of the electron-hole overlap in hNCs with a band gap larger than 2.05 eV or smaller than 1.98 eV. However, the decrease in fgap is limited to about 50% when compared to CdSe NCs, suggesting that residual confinement still localizes the electron near the core. We correlated fgap with the radiative lifetime obtained from multiexponential photoluminescence (PL) decay traces...
March 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28327467/automated-detection-of-epileptic-ripples-in-meg-using-beamformer-based-virtual-sensors
#4
Carolina Migliorelli, Joan Alonso, Sergio Romero, Rafal Nowak, Antonio Russi, Miguel Mananas
OBJECTIVE: In epilepsy, high-frequency oscillations (HFOs) are considered events highly linked to the seizure onset zone (SOZ). The detection of HFOs in noninvasive signals such as scalp EEG and MEG is still a challenging task. The aim of this study was to automatize the detection of ripples in MEG signals reducing the high-frequency noise using beamformer-based virtual sensors (VS) and applying an automatic procedure exploring the time-frequency content of the detected events. APPROACH: 200 seconds of MEG signals and simultaneous iEEG were selected in nine patients with refractory epilepsy...
March 22, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28326440/effects-of-visual-motion-consistent-or-inconsistent-with-gravity-on-postural-sway
#5
Priscilla Balestrucci, Elena Daprati, Francesco Lacquaniti, Vincenzo Maffei
Vision plays an important role in postural control, and visual perception of the gravity-defined vertical helps maintaining upright stance. In addition, the influence of the gravity field on objects' motion is known to provide a reference for motor and non-motor behavior. However, the role of dynamic visual cues related to gravity in the control of postural balance has been little investigated. In order to understand whether visual cues about gravitational acceleration are relevant for postural control, we assessed the relation between postural sway and visual motion congruent or incongruent with gravity acceleration...
March 22, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28326054/dynamical-constants-and-time-universals-a-first-step-toward-a-metrical-definition-of-ordered-and-abnormal-cognition
#6
REVIEW
Mark A Elliott, Naomi du Bois
From the point of view of the cognitive dynamicist the organization of brain circuitry into assemblies defined by their synchrony at particular (and precise) oscillation frequencies is important for the correct correlation of all independent cortical responses to the different aspects of a given complex thought or object. From the point of view of anyone operating complex mechanical systems, i.e., those comprising independent components that are required to interact precisely in time, it follows that the precise timing of such a system is essential - not only essential but measurable, and scalable...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28325941/blue-organic-light-emitting-diodes-realizing-external-quantum-efficiency-over-25-using-thermally-activated-delayed-fluorescence-emitters
#7
Takuya Miwa, Shosei Kubo, Katsuyuki Shizu, Takeshi Komino, Chihaya Adachi, Hironori Kaji
Improving the performance of blue organic light-emitting diodes (OLEDs) is needed for full-colour flat-panel displays and solid-state lighting sources. The use of thermally activated delayed fluorescence (TADF) is a promising approach to efficient blue electroluminescence. However, the difficulty of developing efficient blue TADF emitters lies in finding a molecular structure that simultaneously incorporates (i) a small energy difference between the lowest excited singlet state (S1) and the lowest triplet state (T1), ΔE ST, (ii) a large oscillator strength, f, between S1 and the ground state (S0), and (iii) S1 energy sufficiently high for blue emission...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28325893/a-robust-empirical-seasonal-prediction-of-winter-nao-and-surface-climate
#8
L Wang, M Ting, P J Kushner
A key determinant of winter weather and climate in Europe and North America is the North Atlantic Oscillation (NAO), the dominant mode of atmospheric variability in the Atlantic domain. Skilful seasonal forecasting of the surface climate in both Europe and North America is reflected largely in how accurately models can predict the NAO. Most dynamical models, however, have limited skill in seasonal forecasts of the winter NAO. A new empirical model is proposed for the seasonal forecast of the winter NAO that exhibits higher skill than current dynamical models...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28324998/prediction-of-the-outcome-in-cardiac-arrest-patients-undergoing-hypothermia-using-eeg-wavelet-entropy
#9
Hana Moshirvaziri, Nima Ramezan-Arab, Shadnaz Asgari
Cardiac arrest (CA) is the leading cause of death in the United States. Induction of hypothermia has been found to improve the functional recovery of CA patients after resuscitation. However, there is no clear guideline for the clinicians yet to determine the prognosis of the CA when patients are treated with hypothermia. The present work aimed at the development of a prognostic marker for the CA patients undergoing hypothermia. A quantitative measure of the complexity of Electroencephalogram (EEG) signals, called wavelet sub-band entropy, was employed to predict the patients' outcomes...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28324930/rtms-enhanced-gamma-oscillation-through-strengthened-network-connection
#10
Mengmeng Dou, Xin Tian
Gamma oscillations emerge generally in working memory to aspect of higher cognitive functions, and typically with the interaction of brain network. How is gamma oscillatory activity influenced by the functional connection in the brain'a network? How can gamma oscillations be increased by neural modulation to result in potential benefits for working memory? The present study aims to investigate the intensity of gamma oscillations modulated by low frequency repetitive transcranial magnetic stimulation (rTMS), and the possible brain network mechanism of increased gamma oscillations during working memory task in rats...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28324134/-between-psyche-and-brain-state-of-the-art-in-psychiatry
#11
T Fuchs
Since its development around 1800 psychiatry has been oscillating between the poles of the sciences and the humanities, being directed towards subjective experience on the one hand and towards the neural substrate on the other hand. Today, this dualism seems to have been overcome by a naturalism, which identifies subjective experience with neural processes, according to Griesinger's frequently quoted statement "mental diseases are brain diseases". The progress achieved by the neurobiological paradigm on the level of a fundamental science is in contrast to the tendency to isolate mental illnesses from the patients' social relationships and to neglect subjectivity and intersubjectivity in their explanation...
March 21, 2017: Der Nervenarzt
https://www.readbyqxmd.com/read/28324069/glucose-homeostasis-regulation-by-peripheral-circadian-clocks-in-rodents-and-humans
#12
Frederic Gachon, Ursula Loizides-Mangold, Volodymyr Petrenko, Charna Dibner
Most organisms, including humans, have developed an intrinsic system of circadian oscillators, allowing the anticipation of events related to the rotation of the Earth around its own axis. The mammalian circadian timing system orchestrates nearly all aspects of physiology and behavior. Together with systemic signals, emanating from the central clock which resides in the hypothalamus, peripheral oscillators orchestrate tissue-specific fluctuations in gene expression, protein synthesis, and posttranslational modifications, driving overt rhythms in physiology and behavior...
March 15, 2017: Endocrinology
https://www.readbyqxmd.com/read/28323894/a-generalized-phase-resetting-method-for-phase-locked-modes-prediction
#13
Sorinel A Oprisan, Dave I Austin
We derived analytically and checked numerically a set of novel conditions for the existence and the stability of phase-locked modes in a biologically relevant master-slave neural network with a dynamic feedback loop. Since neural oscillators even in the three-neuron network investigated here receive multiple inputs per cycle, we generalized the concept of phase resetting to accommodate multiple inputs per cycle. We proved that the phase resetting produced by two or more stimuli per cycle can be recursively computed from the traditional, single stimulus, phase resetting...
2017: PloS One
https://www.readbyqxmd.com/read/28323013/electroencephalographic-sensorimotor-rhythms-are-modulated-in-the-acute-phase-following-focal-vibration-in-healthy-subjects
#14
Susanna Lopez, Fabiano Bini, Claudio Del Percio, Franco Marinozzi, Claudia Celletti, Antonio Suppa, Raffaele Ferri, Emanuela Staltari, Filippo Camerota, Claudio Babiloni
Few minutes of focal vibration (FV) on limb muscles can improve motor control in neurological (stroke, Parkinson) patients for unknown underlying neurophysiological mechanisms. Here we hypothesized that in healthy volunteers this FV would increase excitability in the primary sensorimotor cortex (S1-M1) during an isometric contraction of the stimulated muscle. The design included an initial control condition with no FV stimulation (Baseline) as well as three short experimental sessions of FV and a Sham (fake) session in a pseudo-random order...
March 17, 2017: Neuroscience
https://www.readbyqxmd.com/read/28323009/investigation-of-the-effects-of-transcranial-alternating-current-stimulation-tacs-on-self-paced-rhythmic-movements
#15
Manuel Varlet, Alanna Wade, Giacomo Novembre, Peter E Keller
Human rhythmic movements spontaneously entrain to external rhythmic stimuli. Such sensory-motor entrainment can attract movements to different tempi and enhance their efficiency, with potential clinical applications for motor rehabilitation. Here we investigate whether entrainment of self-paced rhythmic movements can be induced via transcranial alternating current stimulation (tACS), which uses alternating currents to entrain spontaneous brain oscillations at specific frequencies. Participants swung a handheld pendulum at their preferred tempo with the right hand while tACS was applied over their left or right primary motor cortex at frequencies equal to their preferred tempo (Experiment 1) or in the alpha (10Hz) and beta (20Hz) ranges (Experiment 2)...
March 18, 2017: Neuroscience
https://www.readbyqxmd.com/read/28322886/high-gamma-oscillations-in-the-motor-cortex-during-visuo-motor-coordination-a-tacs-interferential-study
#16
E Santarnecchi, A Biasella, E Tatti, A Rossi, D Prattichizzo, S Rossi
BACKGROUND: While the role of beta (∼20Hz), theta (∼5Hz) and alpha (∼10Hz) oscillations in the motor areas have been repeatedly associated with defined properties of motor performance, the investigation of gamma (∼40-90Hz) oscillatory activity is a more recent and still not fully understood component of motor control physiology, despite its potential clinical relevance for motor disorders. OBJECTIVE/HYPOTHESIS: we have implemented an online neuromodulation paradigm based on transcranial alternating current stimulation (tACS) of the dominant motor cortex during a visuo-motor coordination task...
March 17, 2017: Brain Research Bulletin
https://www.readbyqxmd.com/read/28322327/carbon-nanotube-mode-locked-thulium-fiber-laser-with-200-nm-tuning-range
#17
Yafei Meng, Yao Li, Yongbing Xu, Fengqiu Wang
We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28322262/a-nanotechnology-ready-computing-scheme-based-on-a-weakly-coupled-oscillator-network
#18
Damir Vodenicarevic, Nicolas Locatelli, Flavio Abreu Araujo, Julie Grollier, Damien Querlioz
With conventional transistor technologies reaching their limits, alternative computing schemes based on novel technologies are currently gaining considerable interest. Notably, promising computing approaches have proposed to leverage the complex dynamics emerging in networks of coupled oscillators based on nanotechnologies. The physical implementation of such architectures remains a true challenge, however, as most proposed ideas are not robust to nanotechnology devices' non-idealities. In this work, we propose and investigate the implementation of an oscillator-based architecture, which can be used to carry out pattern recognition tasks, and which is tailored to the specificities of nanotechnologies...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28321433/transcription-factor-oscillations-in-neural-stem-cells-implications-for-accurate-control-of-gene-expression
#19
REVIEW
Pascal Bielefeld, Marijn Schouten, Paul J Lucassen, Carlos P Fitzsimons
Naturally occurring oscillations in glucocorticoids induce a cyclic activation of the glucocorticoid receptor (GR), a well-characterized ligand-activated transcription factor. These cycles of GR activation/deactivation result in rapid GR exchange at genomic response elements and GR recycling through the chaperone machinery, ultimately generating pulses of GR-mediated transcriptional activity of target genes. In a recent article we have discussed the implications of circadian and high-frequency (ultradian) glucocorticoid oscillations for the dynamic control of gene expression in hippocampal neural stem/progenitor cells (NSPCs) (Fitzsimons et al...
2017: Neurogenesis (Austin, Tex.)
https://www.readbyqxmd.com/read/28321180/multiple-kinases-involved-in-the-nicotinic-modulation-of-gamma-oscillations-in-the-rat-hippocampal-ca3-area
#20
JianGang Wang, XiaoLong He, Fangli Guo, XiangLin Cheng, Yali Wang, XiaoFang Wang, ZhiWei Feng, Martin Vreugdenhil, ChengBiao Lu
Neuronal synchronization at gamma band frequency (20-80 Hz, γ oscillations) is closely associated with higher brain function, such as learning, memory and attention. Nicotinic acetylcholine receptors (nAChRs) are highly expressed in the hippocampus, and modulate hippocampal γ oscillations, but the intracellular mechanism underlying such modulation remains elusive. We explored multiple kinases by which nicotine can modulate γ oscillations induced by kainate in rat hippocampal area CA3 in vitro. We found that inhibitors of cyclic AMP dependent kinase (protein kinase A, PKA), protein kinase C (PKC), N-methyl-D-aspartate receptor (NMDA) receptors, Phosphoinositide 3-kinase (PI3K) and extracellular signal-related kinases (ERK), each individually could prevent the γ oscillation-enhancing effect of 1 μM nicotine, whereas none of them affected baseline γ oscillation strength...
2017: Frontiers in Cellular Neuroscience
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