Overview and developments in noninvasive diagnosis of nonalcoholic fatty liver disease

High prevalence of non-alcoholic fatty liver disease (NAFLD) and very diverse outcomes that are related to disease form and severity at presentation have made the search for noninvasive diagnostic tools in NAFLD one of the areas with most intense development in hepatology today.Various methods have been investigated in the recent years,including imaging methods like ultrasound and magnetic resonance imaging,different forms of liver stiffness measurement,various biomarkers of necroinflammatory processes (acute phase reactants,cytokines,markers of apoptosis),hyaluronic acid and other biomarkers of liver fibrosis.Multicomponent tests,scoring systems and diagnostic panels were also developed with the purposes of differentiating non-alcoholic steatohepatitis from simple steatosis or discriminating between various fibrosis stages.In all of the cases,performance of noninvasive methods was compared with liver biopsy,which is still considered to be a gold standard in diagnosis,but is by itself far from a perfect comparative measure.We present here the overview of the published data on various noninvasive diagnostic tools,some of which appear to be very promising,and we address as well some of still unresolved issues in this interesting field.

Resistance modulation in Ge2Sb2Te5

Chalcogenide based phase change random access memory(PCRAM) holds great promise for high speed and large data storage applications.This memory is scalable,requires a low switching energy,has a high endurance,has fast switching speed,and is nonvolatile.However,decreasing the switching time whilst increasing the cycle endurance is a key challenge for this technology to replace dynamic random access memory.Here we demonstrate high speed and high endurance ultrafast transient switching in the SET state of a prototypical phase change memory cell.Volatile switching is modeled by electron-phonon and lattice scattering on short timescales and charge carrier excitation on long timescales.This volatile switching in phase change materials enables the design of hybrid memory modulators and ultrafast logic circuits.

Thermal analysis in high power GaAs-based laser diodes

The thermal characteristics of 808 nm Al Ga As/Ga As laser diodes（LDs） are analyzed via electrical transient measurements and infrared thermography. The temperature rise and thermal resistance are measured at various input currents and powers. From the electrical transient measurements, it is found that there is a significant reduction in thermal resistance with increasing power because of the device power conversion efficiency. The component thermal resistance that was obtained from the structure function showed that the total thermal resistance is mainly composed of the thermal resistance of the sub-mount rather than that of the LD chip, and the thermal resistance of the sub-mount decreases with increasing current. The temperature rise values are also measured by infrared thermography and are calibrated based on a reference image, with results that are lower than those determined by electrical transient measurements. The difference in the results is caused by the limited spatial resolution of the measurements and by the signal being captured from the facet rather than from the junction of the laser diode.