Phase of beta-frequency tACS over primary motor cortex modulates corticospinal excitability

The assessment of corticospinal excitability by means of transcranial magnetic stimulation-induced motor evoked potentials is an established diagnostic tool in neurophysiology and a widely used procedure in fundamental brain research. However, concern about low reliability of these measures has grown recently. One possible cause of high variability of MEPs under identical acquisition conditions could be the influence of oscillatory neuronal activity on corticospinal excitability. Based on research showing that transcranial alternating current stimulation can entrain neuronal oscillations we here test whether alpha or beta frequency tACS can influence corticospinal excitability in a phase-dependent manner. We applied tACS at individually calibrated alpha- and beta-band oscillation frequencies, or we applied sham tACS. Simultaneous single TMS pulses time locked to eight equidistant phases of the ongoing tACS signal evoked MEPs. To evaluate offline effects of stimulation frequency, MEP amplitudes were measured before and after tACS. To evaluate whether tACS influences MEP amplitude, we fitted one-cycle sinusoids to the average MEPs elicited at the different phase conditions of each tACS frequency. We found no frequency-specific offline effects of tACS. However, beta-frequency tACS modulation of MEPs was phase-dependent. Post hoc analyses suggested that this effect was specific to participants with low (<19 Hz) intrinsic beta frequency. In conclusion, by showing that beta tACS influences MEP amplitude in a phase-dependent manner, our results support a potential role attributed to neuronal oscillations in regulating corticospinal excitability. Moreover, our findings may be useful for the development of TMS protocols that improve the reliability of MEPs as a meaningful tool for research applications or for clinical monitoring and diagnosis. (C) 2018 Elsevier Ltd. All rights reserved

Direct Integration of Micromachined Pipettes in a Flow Channel for Single DNA Molecule Study by Optical Tweezers

We have developed a micromachined flow cell consisting of a flow channel integrated with micropipettes. The flow cell is used in combination with an optical trap setup (optical tweezers) to study mechanical and structural properties of λ-DNA molecules. The flow cell was realized using silicon micromachining including the so-called buried channel technology to fabricate the micropipettes, the wet etching of glass to create the flow channel,\ud and the powder blasting of glass to make the fluid connections. The volume of the flow cell is 2 µl. The pipettes have a length of 130 m, a width of 5–10 µm, a round opening of 1 um and can be processed with different shapes. Using this flow cell we stretched single molecules (λ-DNA) showing typical force-extension curves also found with conventional techniques. These pipettes can be\ud also used for drug delivery, for injection of small gas bubbles into a liquid flow to monitor the streamlines, and for the mixing of liquids to study diffusion effects. The paper describes the design, the fabrication and testing of the flow cell

A pharmacist-managed dosing algorithm for darbepoetin alfa and iron sucrose in hemodialysis patients:A randomized, controlled trial

The attainment of target hemoglobin levels in hemodialysis patients is low. Several factors play a role, such as hyporesponsiveness to erythropoiesis-stimulating agents (ESA), but also suboptimal prescribing of ESA and iron. The goal of this study was to investigate if a pharmacist-managed dosing algorithm for darbepoetin alfa (DA) and iron sucrose improves the attainment of target hemoglobin levels. In this randomized controlled trial, 200 hemodialysis patients from a Dutch teaching hospital were included. In the intervention group (n = 100), a pharmacist monthly provided dose recommendations for DA and iron sucrose based on dosing algorithms. The control group (n = 100) received usual care. In the intervention group, the percentage per patient within the target range (PTR) for hemoglobin (target range 6.8-7.4 mmol/L) and iron status was higher than in the control group (for hemoglobin median 38.5% vs 23.1%,P = .001 and for iron status median 21.1% vs 8.3%,P = .003). The percentage of high hemoglobin levels (>8.1 mmol/L) was lower in the intervention group (median 0.0% vs 7.7%,P = .034). The weekly dose of DA was lower in the intervention group (median 34.0 vs 46.9 mcg,P = .020), whereas iron dose was higher (median 75 vs 0 mg). No difference was found for the percentage of hemoglobin levels below the target range. In conclusion, a pharmacist-managed dosing algorithm for DA and iron sucrose increased the attainment of target levels for hemoglobin and iron status, reduced the percentage of high hemoglobin levels, and was associated with a lower DA and a higher iron sucrose dose

On a new iterative method for solving linear systems and comparison results

AbstractIn Ujević [A new iterative method for solving linear systems, Appl. Math. Comput. 179 (2006) 725–730], the author obtained a new iterative method for solving linear systems, which can be considered as a modification of the Gauss–Seidel method. In this paper, we show that this is a special case from a point of view of projection techniques. And a different approach is established, which is both theoretically and numerically proven to be better than (at least the same as) Ujević's. As the presented numerical examples show, in most cases, the convergence rate is more than one and a half that of Ujević