A model of feedback control for the charge-balanced suppression of epileptic seizures

Here we present several refinements to a model of feedback control for the suppression of epileptic seizures. We utilize a stochastic partial differential equation (SPDE) model of the human cortex. First, we verify the strong convergence of numerical solutions to this model, paying special attention to the sharp spatial changes that occur at electrode edges. This allows us to choose appropriate step sizes for our simulations; because the spatial step size must be small relative to the size of an electrode in order to resolve its electrical behavior, we are able to include a more detailed electrode profile in the simulation. Then, based on evidence that the mean soma potential is not the variable most closely related to the measurement of a cortical surface electrode, we develop a new model for this. The model is based on the currents flowing in the cortex and is used for a simulation of feedback control. The simulation utilizes a new control algorithm incorporating the total integral of the applied electrical potential. Not only does this succeed in suppressing the seizure-like oscillations, but it guarantees that the applied signal will be charge-balanced and therefore unlikely to cause cortical damage

Collaborative care for the detection and management of depression among adults with hypertension in South Africa: study protocol for the PRIME-SA randomised controlled trial

Background: The high co-morbidity of mental disorders, particularly depression, with non-communicable diseases (NCDs) such as cardiovascular disease (CVD), is concerning given the rising burden of NCDs globally, and the role depression plays in confounding prevention and treatment of NCDs. The objective of this randomised control trial (RCT) is to determine the real-world effectiveness of strengthened depression identification and management on depression outcomes in hypertensive patients attending primary health care (PHC) facilities in South Africa (SA). Methods/design: The study design is a pragmatic, two-arm, parallel-cluster RCT, the unit of randomisation being the clinics, with outcomes being measured for individual participants. The 20 largest eligible clinics from one district in the North West Province are enrolled in the trial. Equal numbers of hypertensive patients (n = 50) identified as having depression using the Patient Health Questionnaire (PHQ-9) are enrolled from each clinic, making up a total of 1000 participants with 500 in each arm. The nurse clinicians in the control facilities receive the standard training in Primary Care 101 (PC101), a clinical decision support tool for integrated chronic care that includes guidelines for hypertension and depression care. Referral pathways available include referrals to PHC physicians, clinical or counselling psychologists and outpatient psychiatric and psychological services. In the intervention clinics, this training is supplemented with strengthened training in the depression components of PC101 as well as training in clinical communication skills for nurse-led chronic care. Referral pathways are strengthened through the introduction of a facility-based behavioural health counsellor, trained to provide structured manualised counselling for depression and adherence counselling for all chronic conditions. The primary outcome is defined as at least 50% reduction in PHQ-9 score measured at 6 months. Discussion: This trial should provide evidence of the real world effectiveness of strengtheneddepression identification and collaborative management on health outcomes of hypertensive patients withcomorbid depression attending PHC facilities in South Africa

Comparison between analyzing powers from the inclusive reactions (p,<SUP>3</SUP>He) and (p,alpha) on <SUP>59</SUP>Co and <SUP>93</SUP>Nb at an incident energy of 100 MeV

NatuurwetenskappeFisikaPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

The production of 82Sr using larger format RbCl targets

The production of 82Sr at iThemba LABS is performed by the proton bombardment of a RbCl target using the facility's Vertical-Beam Target Station (VBTS). 82Sr is separated from the target material using a method based on target dissolution, using dilute ammonium chloride solution, and the use of chromatographic methods on Purolite S950 ion exchange resin. After performing a further purification step using AG MP-50 macroporous cation exchange resin, the result is a product with a high radionuclidic purity and negligible Rb and Fe impurity content

Investigation of the 68Zn(p,2p)67Cu nuclear reaction: new measurements up to 40 MeV and compilation up to 100 MeV

Szelecsényi, F; Steyn, G.F; Dolley, S.G; Kovács, Z; Vermeulen, C; van der Walt, T.N; (2009). Investigation of the 68Zn(p,2p)67Cu nuclear reaction: New measurements up to 40 MeV and compilation up to 100 MeV. Nuclear Instruments and Methods in Physics Research B 267 (2009) 1877–1881, DOI:10.1016/j.nimb.2009.03.097The excitation function was measured for the 68Zn(p,2p)67Cu nuclear reaction from its threshold energy up to 40 MeV. Nine pieces of highly enriched 68Zn (>98%) metal foils were irradiated to obtain reliable crosssections using the usual stacked-foil technique. All foils were subjected to high efficiency radiochemical separation before the activity measurements. A critical compilation of the available experimental crosssection results was also performed. Thick target yields of 67Cu and the longer-lived copper radio-contaminants (61Cu and 64Cu) were calculated using the reliable literature results up to 100 MeV. Additionally, EOB (End Of Bombardment) contamination levels as a function of bombarding energy and irradiation time were deduced

Analyzing power and cross section distributions of the knockout reaction 208Pb(p,2p)207Tl at an incident energy of 202 MeV

NatuurwetenskappePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected] measurements of the cross section and analyzing power for the 208Pb(p→2p)207Tl proton knockout reaction at 202 MeV are presented for three quasifree angle pairs. Energy-sharing cross section distributions are found to be in excellent agreement with distorted wave impulse approximation (DWIA) calculations, yielding spectroscopic factors that are in reasonable agreement with (e,e′p) studies and theoretical expectations. The measured analyzing powers are, however, in significant disagreement with results of standard DWIA calculations that utilize the free nucleon-nucleon interaction. Analyzing power calculations are furthermore found to be insensitive to variations in the distorting potentials, different descriptions of the bound state, different energy prescriptions of the two-body interaction, and nonlocality effects. Agreement between theory and experiment is shown to improve only when the density dependence of the nucleon-nucleon interaction is incorporated within the DWIA

Continuum cross sections for proton-induced reactions on biologically-important target nuclei.

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The use of selective volatisation in the separation of 68Ge from irradiated Ga targets

Cyclotron-produced 68Ge can be separated from its Ga target material by dissolving the target in aqua regia and collecting the volatile 68Ge in a solution containing 1.0 M NaOH and 2% Na2SO3. The solution is then acidified with HF before being loaded onto a column containing AG MP-1 anion exchange resin. The column is rinsed with dilute HF to remove any remaining impurities, before eluting the desired product with 0.1 M HCl. A radiochemically pure product is obtained