MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary Waveform Generation

Neural stimulation systems are used to modulate electrically excitable tissue to interrogate neural circuit function or provide therapeutic benefit. Conventional stimulation systems are expensive and limited in functionality to standard stimulation waveforms, and they are bad for high frequency stimulation. We present MEDUSA, a system that enables new research applications that can leverage multi-channel, arbitrary stimulation waveforms. MEDUSA is low cost and uses commercially available components for widespread adoption. MEDUSA is comprised of a PC interface, an FPGA for precise timing control, and eight bipolar current sources that can each address up to 16 electrodes. The current sources have a resolution of 15.3 nA and can provide ±5 mA with ±5 V compliance. We demonstrate charge-balancing techniques in vitro using a custom microelectrode. An in vivo strength-duration curve for earthworm nerve activation is also constructed using MEDUSA. MEDUSA is a multi-functional neuroscience research tool for electroplating microelectrodes, performing electrical impedance spectroscopy, and examining novel neural stimulation protocols

Angular momentum transport modeling: achievements of a gyrokinetic quasi-linear approach

QuaLiKiz, a model based on a local gyrokinetic eigenvalue solver is expanded to include momentum flux modeling in addition to heat and particle fluxes. Essential for accurate momentum flux predictions, the parallel asymmetrization of the eigenfunctions is successfully recovered by an analytical fluid model. This is tested against self-consistent gyrokinetic calculations and allows for a correct prediction of the ExB shear impact on the saturated potential amplitude by means of a mixing length rule. Hence, the effect of the ExB shear is recovered on all the transport channels including the induced residual stress. Including these additions, QuaLiKiz remains ~10 000 faster than non-linear gyrokinetic codes allowing for comparisons with experiments without resorting to high performance computing. The example is given of momentum pinch calculations in NBI modulation experiments

Cordyla pinnata améliore les propriétés du sol et la productivité des cultures

Dans les systèmes agroforestiers, les cultures sous le couvert des arbres (SC) bénéficient de plus de nutriments, après décomposition et minéralisation des litières, que celles hors de leur couvert (HC). La fertilité des sols et la productivité du mil et de l’arachide ont été évaluées sur des sols prélevés à différentes distances de Cordyla pinnata, une légumineuse arborée qui forme un parc agroforestier au Sénégal. Les analyses de sols ont montré des valeurs plus élevées pour N total, Ca échangeable et CEC sous le couvert de l’espèce. Pour le mil, la hauteur, les biomasses aérienne et racinaire ont également été plus élevées sur les sols SC. Par conséquent, la biomasse totale du mil a fortement augmenté (+ 90%) sur les sols SC. Pour l’arachide, la longueur totale, les biomasses (tiges, feuilles, gousses, racines) ont été supérieures sur les sols SC. Comme pour le mil, la biomasse totale de l’arachide a augmenté (+ 94%) sur les sols SC par rapport au découvert. La plupart des variables des cultures ont été plus élevées sur les sols SC, probablement à cause de leur meilleur statut nutritif. L’introduction des arbres dans les systèmes de production au Sahel pourrait ainsi constituer une bonne stratégie pour améliorer la fertilité des sols et contribuer au développement d’une agriculture durable.Mots clés: Arachide, Fertilité des sols, Mil, Parc agroforestier, Sénéga

Constraints to liberty of movement and attachment styles significantly account for well-being in three Palestinian samples

Background: Political violence and constraints on liberty of movement can have consequences for health and well-being but affect individuals differently. Objective: In three Palestinian samples, we sought to examine the relationship between key environmental and psychological factors and general and mental health, including the previously unexplored roles of constraints to liberty of movement and attachment orientation. Method: Participants (n=519) in the Occupied Palestinian Territories and Jordan completed questionnaires on constraints to liberty of movement (4-item scale devised by the authors for the purpose of the current study), attachment insecurity (Experiences in Close Relationships Scale – Short Form, Wei et al., 2007), resource loss (Conservation of Resources Evaluation scale, Hobfoll & Lilly, 1993), experience of political violence (Experience and fear of political violence, Hobfoll et al., 2011), demographics, general health (adapted from DeSalvo et al, 2006) and mental health (PHQ4 for depression, and Ballenger et al.’s, (2001) 2 item screener for anxiety). All measures were translated from English to Arabic and back-translated into English. Results: Findings from regression and mediation analyses indicated that (i) differences in general and mental health among Palestinians in the Occupied Palestinian Territories and the diaspora in Jordan, can be explained by the assessed constructs; (ii) constraints to liberty of movement, attachment avoidance, and resource loss significantly accounted for poor general health; (iii) constraints to liberty of movement, attachment anxiety, and resource loss significantly explained general anxiety symptoms; and (iv) attachment anxiety, resource loss, and experience of political violence significantly explained depression symptoms. Conclusion: Findings have theory-building implications for psychological models of human flourishing and suffering, suggesting that they are incomplete without consideration of liberty as a context, as well as implications for policymakers and champions of global health initiatives, as they highlight the psychological effects of constraints to liberty of movement on health

Characterizing cross‐linking within polymeric biomaterials in the SEM by secondary electron hyperspectral imaging

A novel capability built upon secondary electron (SE) spectroscopy provides an enhanced cross‐linking characterization toolset for polymeric biomaterials, with cross‐linking density and variation captured at a multiscale level. The potential of SE spectroscopy for material characterization has been investigated since 1947. The absence of suitable instrumentation and signal processing proved insurmountable barriers to applying SE spectroscopy to biomaterials, and consequently, capturing SE spectra containing cross‐linking information is a new concept. To date, cross‐linking extent is inferred from analytical techniques such as nuclear magnetic resonance (NMR), differential scanning calorimetry, and Raman spectroscopy (RS). NMR provides extremely localized information on the atomic scale and molecular scale, while RS information volume is on the microscale. Other methods for the indirect study of cross‐linking are bulk mechanical averaging methods, such as tensile and compression modulus testing. However, these established averaging methods for the estimation of polymer cross‐linking density are incomplete because they fail to provide information of spatial distributions within the biomaterial morphology across all relevant length scales. The efficacy of the SE spectroscopy capability is demonstrated in this paper by the analysis of poly(glycerol sebacate)‐methacrylate (PGS‐M) at different degrees of methacrylation delivering new insights into PGS‐M morphology

A Low-Cost, Wireless, Multi-Channel Deep Brain Stimulation System for Rodents

We present a small (43mm x 24mm x 15mm), off-the-shelf wireless neurostimulator for rodent deep brain stimulation research. Our device enables researchers to wirelessly configure stimulator settings, such as amplitude, pulse width, channel selection, and frequency, via a phone app. The system uses impedance-independent current-mode stimulation and steers current to a selected channel. In addition to monophasic and biphasic stimulation, the system also supports arbitrary waveform stimulation using pre-stored lookup tables. The system uses a configurable grounding phase to clear residual charge and a stimulation compliance monitor to ensure safe operation. The compliance monitor wirelessly reports the current during stimulation, the amount of passive recharge current, and the DC voltage of the electrode interface. The 400mAh battery is easy to replace and can go over 40 hours between charges. The system can be built for less than $50 using easy-to-source components to support inexpensive, highly-parallel research applications

SENSITIVITY AND SPESIFICITY VALUE OF PLATELETS, MALIGNANCY RATIO INDEX AND BOTH COMBINED IN DIAGNOSING OVARIAN CANCER AT GENERAL HOSPITAL HAJI ADAM MALIK MEDAN FROM 2016-2018

Objective: This research aimed to analyze sensitivity and specificity values of platelets, RMI and both combined as ovarian cancer diagnostic modality in Haji Adam Malik Hospital in 2016-2018. Methods: This is analytic research with a diagnostic test design on 204 patients who had been diagnosed with ovarian cancer and patients with ovary benign tumors which have been examined the value of full blood and the malignancy ratio index and ovarian mass that has been proven by the results of anatomic pathology at General Hospital Haji Adam Malik Medan in 2016-2018. The data is tabulated into 2x2 table and then calculated for each sensitivity, specificity, positive predictive value and negative predictive value. Result: By using platelet cut-off value>450000 per mm3 in diagnosing ovarian cancer with sensitivity 55.44% and specificity 83.65% were obtained. IRK has a sensitivity 83.16% and specificity 76.92%. Platelet and IRK values ​​provided the highest diagnostic value (specificity) compared to when they were each single which was 97.11% while the combination of platelet and IRK values ​​had a sensitivity of 49.50%. Conclusion: Platelet and IRK values ​​gives the highest diagnostic value (specificity) compared to when both are used, namely 97.11%

Angular momentum transport modeling: achievements of a gyrokinetic quasi-linear approach

International audienceQuaLiKiz, a model based on a local gyrokinetic eigenvalue solver is expanded to include momentum flux modeling in addition to heat and particle fluxes. Essential for accurate momentum flux predictions, the parallel asymmetrization of the eigenfunctions is successfully recovered by an analytical fluid model. This is tested against self-consistent gyrokinetic calculations and allows for a correct prediction of the E×B shear impact on the saturated potential amplitude by means of a mixing length rule. Hence, the effect of the E×B shear is recovered on all the transport channels including the induced residual stress. Including these additions, QuaLiKiz remains ∼10 000 faster than non-linear gyrokinetic codes allowing for comparisons with experiments without resorting to high performance computing. The example is given of momentum pinch calculations in NBI modulation experiments

Dynamics of zonal flow-like structures in the edge of the TJ-II stellarator

The dynamics of fluctuating electric field structures in the edge of the TJ-II stellarator, that display zonal flow-like traits, is studied. These structures have been shown to be global and affect particle transport dynamically [J.A. Alonso et al., Nucl. Fus. 52 063010 (2012)]. In this article we discuss possible drive (Reynolds stress) and damping (Neoclassical viscosity, geodesic transfer) mechanisms for the associated ExB velocity. We show that: (a) while the observed turbulence-driven forces can provide the necessary perpendicular acceleration, a causal relation could not be firmly established, possibly because of the locality of the Reynolds stress measurements, (b) the calculated neoclassical viscosity and damping times are comparable to the observed zonal flow relaxation times, and (c) although an accompanying density modulation is observed to be associated to the zonal flow, it is not consistent with the excitation of pressure side-bands, like those present in geodesic acoustic oscillations, caused by the compression of the ExB flow field