The Unique Determination of Neuronal Currents in the Brain via Magnetoencephalography

The problem of determining the neuronal current inside the brain from measurements of the induced magnetic field outside the head is discussed under the assumption that the space occupied by the brain is approximately spherical. By inverting the Geselowitz equation, the part of the current which can be reconstructed from the measurements is precisely determined. This actually consists of only certain moments of one of the two functions specifying the tangential part of the current. The other function specifying the tangential part of the current as well as the radial part of the current are completely arbitrary. However, it is also shown that with the assumption of energy minimization, the current can be reconstructed uniquely. A numerical implementation of this unique reconstruction is also presented

Visualizing multi-dimensional pareto-optimal fronts with a 3D virtual reality system

In multiobjective optimization, there are several targets that are in conflict, and thus they all cannot reach their optimum simultaneously. Hence, the solutions of the problem form a set of compromised trade-off solutions (a Pareto-optimal front or Pareto-optimal solutions) from which the best solution for the particular problem can be chosen. However, finding that best compromise solution is not an easy task for the human mind. Pareto-optimal fronts are often visualized for this purpose because in this way a comparison between solutions according to their location on the Pareto-optimal front becomes somewhat easier. Visualizing a Pareto-optimal front is straightforward when there are only two targets (or objective functions), but visualizing a front for more than two objective functions becomes a difficult task. In this paper, we introduce a new and innovative method of using three-dimensional virtual reality (VR) facilities to present multi-dimensional Pareto-optimal fronts. Rotation, zooming and other navigation possibilities of VR facilities make easy to compare different trade-off solutions, and fewer solutions need to be explored in order to understand the interrelationships among conflicting objective functions. In addition, it can be used to highlight and characterize interesting features of specific Pareto-optimal solutions, such as whether a particular solution is close to a constraint boundary or whether a solution lies on a relatively steep trade-off region. Based on these additional visual aids for analyzing trade-off solutions, a preferred compromise solution may be easier to choose than by other means

Gender has to be taken into account in diagnosing adult growth hormone deficiency by the GHRH plus arginine test

Objective: Data on the effect of gender on the interpretation of the GHRH plus arginine stimulation test (GHRH + ARG test) is controversial. We validated the GHRH + ARG stimulation test in control subjects and patients with organic or idiopathic pituitary disease and a suspicion of adult growth hormone deficiency (AGHD) using the Immulite 2000 XPi GH assay. Design: We studied 126 apparently healthy adults (median age 38.8 years) and 34 patients with a suspicion of AGHD (median age 42.2 years). Identification of AGHD with the GHRH + ARG test was investigated with commonly accepted BMI-related consensus cut-off limits for peak GH concentrations. Serum samples collected during the GHRH + ARG test were analysed for GH in 2014-2015. Serum IGF-1 concentrations were studied as a reference. Results: In 14 of 65 (22%) control males the GH peak value was below the BMI-related cut-off limits for GH sufficiency indicating a false diagnosis of AGHD. All control females had a normal GHRH + ARG response. Median peak GH response was significantly (p <0.001) higher in female (39.3 mu g/L) than in male controls (21 mu g/L). According to consensus cut-offs all but one young female patient had a deficient response compatible with a diagnosis of AGHD. Conclusions: The GH response to stimulation by GHRH + ARG is gender-dependent, being lower in healthy males than in females. Gender should be considered when defining cut-off limits for peak GH concentrations in the GHRH + ARG test. The presently used BMI-related cut-off levels will lead to a significant misclassification of males as GH deficient.Peer reviewe

The biological activity of serum bacterial lipopolysaccharides associates with disease activity and likelihood of achieving remission in patients with rheumatoid arthritis

Peer reviewe

The biological activity of serum bacterial lipopolysaccharides associates with disease activity and likelihood of achieving remission in patients with rheumatoid arthritis

Peer reviewe

KLEIN: A New Family of Lightweight Block Ciphers

Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while in the same time its hardware implementation can also be compact

Inelastic x-ray scattering at the National Synchrotron Light

The research program at the inelastic x-ray scattering beamline at the National Synchrotron Light Source is focused on the study of elementary excitations in condensed matter with total energy resolution on the order of 0.1 eV to 1.0 eV. Results from selected experiments are reported to demonstrate the capability of the beamline as well as the information can be obtained from inelastic x- ray scattering experiments

Investigation of optimal parameters for finite element solution of the forward problem in magnetic field tomography based on magnetoencephalography

This paper presents an investigation of optimal parameters for finite element (FE) solution of the forward problem in magnetic field tomography (MFT) brain imaging based on magnetoencephalography (MEG). It highlights detailed analyses of the main parameters involved and evaluates their optimal values for various cases of FE model solutions (e.g., steady-state, transient, etc.). In each case, a detail study of some of the main parameters and their effects on FE solution and its accuracy are carefully tested and evaluated. These parameters include: total number and size of 3D FE elements used, number and size of elements used in surface discretisation (of both white and grey matters of the brain), number and size of elements used for approximation of current sources, number of anisotropic properties used in steady-state and transient solutions, and the time steps used in transient analyses. The optimal values of these parameters in relation to solution accuracy and mesh convergence criteria have been found and presented