Spectral detector comprising a cholesteric liquid crystal mixture

\u3cp\u3eThe invention relates to a method for manufacturing a spectral detector including a photo detector array and cholesteric liquid crystal material for measuring properties of light over portions of the electromagnetic spectrum. By exposing the cholesteric liquid crystalmaterialfor different exposure intensities or exposure times of ultraviolet radiation at different positions on the cholesteric liquid crystal material in a controlled way, portions of the cholesteric liquid crystal material are obtained, each having, in general, its own optical transmission. This invention also relates to a spectral detector manufactured by the inventive method.\u3c/p\u3

A device for monitoring exposure to radiation, use of such a device, an article and a method for monitoring exposure to radiation

\u3cp\u3eA device (1) for monitoring exposure to radiation (L), particularly ultraviolet radiation, at least comprising cholesteric liquid crystal material (3) having a photo- isomerisable compound, such that during use, a light reflection band of the cholesteric liquid crystal material (3) can be modified upon exposure to the radiation to be monitored. The invention also provides a method for monitoring exposure to radiation.\u3c/p\u3

Automatic detection of burst synchrony in preterm infants

\u3cp\u3eElectroencephalographic characteristics are useful in assessment of the functional status of specific neuronal connections relative to postmenstrual age. Interhemispheric burst synchrony (IBS) is a measure of the functional connectivity between the hemispheres in the maturing preterm brain. An algorithm was developed to assess IBS and was used in a prospective, longitudinal EEG study on 18 very preterm infants (< 32 weeks gestational age) with normal follow-up at 2 years of age. The preterm infants underwent weekly 4-hour multi-channel EEG recordings, resulting in n = 77 EEGs. After automated detection of bursts, the algorithm defines the start and end of interhemispheric synchronous burst activity, based on selection criteria found in literature. The algorithm was designed to emulate visual inspection, providing objective results in an automated manner. This approach may be applied in clinical use and open novel avenues to automated analysis in EEG monitoring and, moreover, it may facilitate assessment of the functional status of interhemispheric connections. As such, assessment of low interhemispheric synchrony may be associated with brain injury.\u3c/p\u3

Scaling behavior and parasitic series resistance in disordered organic field-effect transistors

\u3cp\u3eThe scaling behavior and transfer characteristics of solution-processed disordered organic thin-film transistors were discussed. Field-effect mobility and parasitic series resistance were studied. Results showed that parasitic resistance depends on applied gate voltage and decreases with increasing field-effect mobility.\u3c/p\u3

The influence of adipose tissue on spatially resolved near-infrared spectroscopy derived skeletal muscle oxygenation: the extent of the problem

\u3cp\u3eObjective. Near-infrared spectroscopy (NIRS) measurements of tissue oxygen saturation (StO\u3csub\u3e2\u3c/sub\u3e) are useful for the assessment of skeletal muscle perfusion and function during exercise, however, they are influenced by overlying skin and adipose tissue. This study explored the extent and nature of the influence of adipose tissue thickness (ATT) on StO\u3csub\u3e2\u3c/sub\u3e. Approach. NIR spatially resolved spectroscopy (SRS) derived oxygenation was measured on vastus lateralis in 56 patients with chronic heart failure (CHF) and 20 healthy control (HC) subjects during rest and moderate intensity exercise with simultaneous assessment of oxygen uptake kinetics (τ ). In vitro measurements were performed on a flow cell with a blood mixture with full oxygen saturation (100%), which was gradually decreased to 0% by adding sodium metabisulfite. Experiments were repeated with 2 mm increments of porcine fat layer between the NIRS device and flow cell up to 14 mm. Main results. Lower ATT, higher τ , and CHF were independently associated with lower in vivo StO\u3csub\u3e2\u3c/sub\u3e in multiple regression analysis, whereas age and gender showed no independent relationship. With greater ATT, in vitro StO\u3csub\u3e2\u3c/sub\u3e was reduced from 100% to 74% for fully oxygenated blood and increased from 0% to 68% for deoxygenated blood. Significance. This study shows that ATT independently confounds NIR-SRS derived StO\u3csub\u3e2\u3c/sub\u3e by overestimating actual skeletal muscle oxygenation and by decreasing its sensitivity for deoxygenation. Because physiological properties (e.g. presence of disease and slowing of τ ) also influence NIR-SRS, a correction based on optical properties is needed to interpret calculated values as absolute StO\u3csub\u3e2\u3c/sub\u3e.\u3c/p\u3

Interhemispheric connectivity estimated from EEG time-correlation analysis in preterm infants with normal follow-up at age of five

\u3cp\u3eBrain connectivity is associated with axonal connections between brain structures. Our goal was to quantify the interhemispheric neuronal connectivity in healthy preterm infants by automated quantitative EEG time-correlation analysis. As with advancing postmenstrual age (PMA, gestational age + postnatal age) the neuronal connectivity between left and right hemisphere increases, we expect to observe changes in EEG time-correlation with age. Thirty-six appropriate-for-gestational age preterm infants (PMA between 27-37 weeks) and normal neurodevelopmental follow-up at 5 years of age were included. Of these, 22 infants underwent 3-8 repeated EEG recordings at weekly intervals. The reduced 10-20 EEG electrode system for newborns was used with five sets of bipolar channels: central-temporal, frontal polar-temporal, frontal polar-central, temporal-occipital and central-occipital. We performed EEG time-correlation analysis between homologous channels of the brain hemispheres to identify interhemispheric similarity in EEG signal shape. For each 8 s epoch of the EEG the time-correlation values and the corresponding lag times were calculated for homologous channels on both hemispheres. In all channels, the median correlation value decreased significantly (between -40% and -60% decrease) from 27 to 37 weeks PMA, for gestational maturation. For the postnatal maturation only the central-temporal channel showed a significantly decreasing trend. In contrast, the median lag time showed no uniform change with PMA. The decreasing median correlation values in all homologous channels indicate a decrease in similarity in signal shape with advancing PMA. This finding may reflect greater functional differentiation of cortical areas in the developing preterm brain and may be explained by the increase of complex neural networks with excitatory and inhibitory circuitries.\u3c/p\u3

Functional connectivity in preterm infants derived from EEG coherence analysis

Objective : To quantify the neuronal connectivity in preterm infants between homologous channels of both hemispheres. Methods : EEG coherence analysis was performed on serial EEG recordings collected from preterm infants with normal neurological follow-up. The coherence spectrum was divided in frequency bands: dnewborn(0–2 Hz), ¿newborn(2–6 Hz), anewborn(6–13 Hz), ßnewborn(13–30 Hz). Coherence values were evaluated as a function of gestational age (GA) and postnatal maturation. Results : All spectra show two clear peaks in the dnewborn and ¿newborn-band, corresponding to the delta and theta EEG waves observed in preterm infants. In the dnewborn-band the peak magnitude coherence decreases with GA and postnatal maturation for all channels. In the ¿newborn-band, the peak magnitude coherence decreases with GA for all channels, but increases with postnatal maturation for the frontal polar channels. In the ßnewborn-band a modest magnitude coherence peak was observed in the occipital channels, which decreases with GA. Conclusions : Interhemispherical connectivity develops analogously with electrocortical maturation: signal intensities at low frequencies decrease with GA and postnatal maturation, but increase at high frequencies with postnatal maturation. In addition, peak magnitude coherence is a clear trend indicator for brain maturation. Significance : Coherence analysis can aid in the clinical assessment of the functional connectivity of the infant brain with maturation