Site specificity in femtosecond laser desorption of neutral H atoms from graphite(0001).

Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states of chemisorbed hydrogen in the desorption process. Very slow velocities of 700 and 400  ms^{-1} for H and D atoms are associated with the desorption out of the highest vibrational state of a barrierless potential.

Exploring risk groups workplace bullying with categorical data.

In this study, we first explore whether different exposure groups of workplace bullying exist, employing a large, heterogeneous sample. The results show six different exposure groups: almost 30.5% is not bullied since they report hardly any negative act at work at all, 27.

Time-variant analysis of phase couplings and amplitude-frequency dependencies of and between frequency components of EEG burst patterns in full-term newborns.

Objective: Burst activity of the 'trace alternant' (TA) EEG pattern in the quiet sleep of full-term newborns is investigated to explore the timing and the time-variant coupling characteristics of and between a burst's oscillatory components. The working hypothesis is that signal properties provide information about the neuronal initiation processes of the burst, and about the coupling and interrelation dynamics between cortical low-frequency oscillations and high-frequency spindles in thalamic structures which substantially contribute to the burst pattern.

Methods: For time-variant phase-locking index (PLI), phase-synchronization index (PSI), quadratic phase coupling (QPC) measures, and amplitude-frequency dependency analyses the Gabor and the Hilbert transformation, both implemented as fast Fourier transformation-based approaches, were used.

On the stability of the n:m phase synchronization index.

Synchronization analysis of multitrial EEG or (magneto encephalogram) MEG signals is an excellent approach to detect functional connectivity between different neuronal oscillators. In our current research, the n:m phase synchronization index (n:m PSI ) is of special interest. We prove the existence of stable and unstable synchronies dependent upon the analysis frequencies and show that they lie closely together in the frequency domain.

A subset of naturally isolated Bacillus strains show extreme virulence to the free-living nematodes Caenorhabditis elegans and Pristionchus pacificus.

The main food source of free-living nematodes in the soil environment is bacteria, which can affect nematode development, fecundity and survival. In order to occupy a reliable source of bacterial food, some nematodes have formed specific relationships with an array of invertebrate hosts (where bacteria proliferate once the hosts dies), thus forming a tritrophic system of nematode, bacteria and insect or other invertebrates. We isolated 768 Bacillus strains from soil (from Germany and the UK), horse dung and dung beetles and fed them to the genetically tractable free-living nematodes Caenorhabditis elegans and Pristionchus pacificus to isolate nematocidal strains.

Connectivity analysis of somatosensory evoked potentials in patients with major depression. Analysis of connectivity.

Objectives: Connectivity analysis was used to investigate the processing of intracutaneous stimuli and directed interactions within the pain matrix in patients with major depression (MD) and healthy controls (HCs), by means of frequency selective generalized partial directed coherence (gPDC).

Methods: Eighteen patients with MD and 18 HCs underwent stimulations consisting of moderately painful intracutaneous electrical stimuli to the right and left middle fingers. Connectivity analysis was based on nine selected EEG electrodes.

A novel PDMS micro membrane biosensor based on the analysis of surface stress.

The biological and medical application of biosensors is more and more important with the development of technology and society. Detection of cells and biological molecules utilizing biosensors based on the analysis of surface stress would facilitate inexpensive and high-throughput test and diagnosis. This paper presents a biocompatible surface stress-based polydimethylsiloxane (PDMS) micro membrane biosensor.

Autocorrelation and phase retrieval in the UV using two-photon absorption in diamond pin photodiodes.

We report on the utilization of the two-photon induced free carrier generation in a diamond pin-type photodiode to record fringe-resolved second-order autocorrelations of femtosecond pulses in the UV. Measurements in photovoltaic mode are performed at the second and third harmonic of a Ti:sapphire laser (lambda(0)=401 nm and lambda(0)=265 nm) with pulse energies down to about 2 nJ. The band gap of diamond of 5.

Understanding the time variant connectivity of the language network in developmental dyslexia: new insights using Granger causality.

The reading process takes place in a neuronal network comprising the inferior frontal, posterior dorsal and posterior ventral brain areas. It is suggested that developmental dyslexia is caused by a disruption of the two posterior network areas. What remains debatable is whether these areas are affected in their functionality or whether the neuronal networking (connectivity) of these areas suffer from a disturbed information transfer.

A new Kalman filter approach for the estimation of high-dimensional time-variant multivariate AR models and its application in analysis of laser-evoked brain potentials.

In this methodological study we present a new version of a Kalman filter technique to estimate high-dimensional time-variant (tv) multivariate autoregressive (tvMVAR) models. It is based on an extension of the state-space model for a multivariate time series to a matrix-state-space model for multi-trial multivariate time series. The result is a general linear Kalman filter (GLKF).

Study of the time-varying cortical connectivity changes during the attempt of foot movements by spinal cord injured and healthy subjects.

In this study we estimated time-varying cortical connectivity patterns from a group of Spinal Cord Injured (SCI) patients during the attempt to move a paralyzed limb. These data were compared with the time-varying connectivity patterns estimated in a control group during the real execution of the movement by using time-varying Partial Directed Coherence. Connectivity was estimated from high resolution EEG recordings with the use of realistic head modelling and the linear inverse estimation of the cortical activity in a series of Regions of Interest of the cortex (ROIs).

Spatial control of the energy metabolism of yeast cells through electrolytic generation of oxygen.

The metabolic dynamics of yeast cells is controlled by electric pulses delivered through a spatially extended yeast cell/Au electrode interface. Concomitant with voltage pulses, oxygen is generated electrolytically at the electrode surface and delivered to the cells. The generation of oxygen was investigated in dependence of the applied voltage, width of the voltage pulses and temperature of the electrolytic solution.

Analysis of induced components in electroencephalograms using a multiple correlation method.

Background: Evoked and induced activities are two typical components in the EEG and MEG time series after a stimulation. While evoked activity is phase-locked to the stimulus, induced activity is not. Present analysis methods are able to detect non-phase-locked parts of the signal, however, they do not improve the signal-to-noise ratio (SNR) of these signal components.

Coordination of the EEG and the heart rate of preterm neonates during quiet sleep.

Aim of this study was to confirm that EEG bursts are associated with heart rate (HR) accelerations, and to investigate the synchronicity between quadratic phase couplings (QPC) courses of the EEG and HR before and during burst activity during quiet sleep in preterm newborns. The time-courses of QPC between frequency components of the EEG ([0.25-1.

Modeling glioma growth and invasion in Drosophila melanogaster.

Glioblastoma is the most common and most malignant intrinsic human brain tumor, characterized by extensive invasion and proliferation of glial (astrocytic) tumor cells, frequent activation of tyrosine kinase receptor signaling pathways, relative resistance to chemotherapy and radiotherapy, and poor prognosis. Using the Gal4-UAS system, we have produced glioma models in Drosophila by overexpressing homologs of human tyrosine kinase receptors under control of the glia-specific promoter reversed polarity (repo). Glial overexpression of activated epidermal growth factor receptor (EGFR) resulted in enhanced proliferation and migration of larval glial cells with increased numbers in the eye imaginal disc, diffuse tumor-like enlargement of the optic stalk, and marked ectopic invasion of glial cells along the optic nerve.

Identification of neural activity based on fMRI data: a simulation study.

This study proposes a technique for determining effective connectivity among brain regions which operates at the level of neuronal dynamics. We propose an alternative time-variant dynamic causal model (TV-DCM) where neuronal dynamic activity evolves based on generalized dynamic neural networks (GDNNs). The identification of brain architecture connectivity is carried out based on a least squares criterion and on a global search technique.

Modelling of cortical and thalamic 600 Hz activity by means of oscillatory networks.

The purpose of this study is to investigate information processing in the primary somatosensory system with the help of oscillatory network modelling. Specifically, we consider interactions in the oscillatory 600Hz activity between the thalamus and the cortical Brodmann areas 3b and 1. This type of cortical activity occurs after electrical stimulation of peripheral nerves such as the median nerve.

Nonlinear analysis and modeling of cortical activation and deactivation patterns in the immature fetal electrocorticogram.

An approach combining time-continuous nonlinear stability analysis and a parametric bispectral method was introduced to better describe cortical activation and deactivation patterns in the immature fetal electroencephalogram (EEG). Signal models and data-driven investigations were performed to find optimal parameters of the nonlinear methods and to confirm the occurrence of nonlinear sections in the fetal EEG. The resulting measures were applied to the in utero electrocorticogram (ECoG) of fetal sheep at 0.

Job insecurity and employability in fixed-term contractors, agency workers, and permanent workers: associations with job satisfaction and affective organizational commitment.

This study investigates how job insecurity and employability relate to job satisfaction and affective organizational commitment in permanent workers, fixed-term contract workers, and temporary agency workers. The authors hypothesized that (a) job insecurity relates negatively to job satisfaction and affective organizational commitment, and this relationship is strongest in permanent workers and weakest in temporary agency workers; and that (b) employability relates positively to job satisfaction and negatively to affective organizational commitment, and this relationship is strongest in temporary agency workers and weakest in permanent workers. Hypotheses were tested in workers (permanent: n = 329; fixed term; n = 160; temporary agency: n = 89) from 23 Belgian organizations.

Modelling and analysis of time-variant directed interrelations between brain regions based on BOLD-signals.

Time-variant Granger Causality Index (tvGCI) was applied to simulated and measured BOLD signals to investigate the reliability of time-variant analysis approaches for the identification of directed interrelations between brain areas on the basis of fMRI data. Single-shot fMRI data of a single image slice with short repetition times (200 ms, 16000 frames/subject, 64x64 voxels) were acquired from 5 healthy subjects during an externally-driven, self-paced finger-tapping paradigm (57-59 single taps for each subject). BOLD signals were derived from the pre-supplementary motor area (preSMA), the supplementary motor area (SMA), and the primary motor cortex (M1).

Study of the time-varying cortical connectivity during the attempt of a foot movement by Spinal Cord Injured patients.

In this study we estimated time-varying cortical connectivity patterns from a group of Spinal Cord Injured (SCI) patients during the attempt to move a paralyzed limb. This data were compared with the time-varying connectivity patterns estimated in a control group during the effective execution of the movement. Connectivity was estimated from high resolution EEG recordings with the use of realistic head modelling and the linear inverse estimation of the cortical activity.

Signal informatics as an advanced integrative concept in the framework of medical informatics. New trends demonstrated by examples derived from neuroscience.

Objectives: The main objective is to show current topics and future trends in the field of medical signal processing which are derived from current research concepts. Signal processing as an integrative concept within the scope of medical informatics is demonstrated.

Methods: For all examples time-variant multivariate autoregressive models were used.

Effects of perceived job insecurity on perceived anxiety and depression in nurses.

Dramatic changes in workplace structure and environment have increased the importance of psychosocial factors and job insecurity in working life. Job insecurity is shown to have a negative impact on mental and physical health. Health care transformation in Turkey increases the threat of job insecurity for many workers in the health care sector.

Brain network analysis from high-resolution EEG recordings by the application of theoretical graph indexes.

The extraction of the salient characteristics from brain connectivity patterns is an open challenging topic since often the estimated cerebral networks have a relative large size and complex structure. Since a graph is a mathematical representation of a network, which is essentially reduced to nodes and connections between them, the use of a theoretical graph approach would extract significant information from the functional brain networks estimated through different neuroimaging techniques. The present work intends to support the development of the "brain network analysis:" a mathematical tool consisting in a body of indexes based on the graph theory able to improve the comprehension of the complex interactions within the brain.