Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances, is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.Comment: 22 pages, 12 figures, review pape

Low frequency 1/f noise in doped manganite grain-boundary junctions

We have performed a systematic analysis of the low frequency 1/f-noise in single grain boundary junctions in the colossal magnetoresistance material La_{2/3}Ca_{1/3}MnO_{3-delta}. The grain boundary junctions were formed in epitaxial La_{2/3}Ca_{1/3}MnO_{3-delta} films deposited on SrTiO_3 bicrystal substrates and show a large tunneling magnetoresistance of up to 300% at 4.2 K as well as ideal, rectangular shaped resistance versus applied magnetic field curves. Below the Curie temperature T_C the measured 1/f noise is dominated by the grain boundary. The dependence of the noise on bias current, temperature and applied magnetic field gives clear evidence that the large amount of low frequency noise is caused by localized sites with fluctuating magnetic moments in a heavily disordered grain boundary region. At 4.2 K additional temporally unstable Lorentzian components show up in the noise spectra that are most likely caused by fluctuating clusters of interacting magnetic moments. Noise due to fluctuating domains in the junction electrodes is found to play no significant role.Comment: 9 pages, 7 figure

YIP1 family member 4 (YIPF4) is a novel cellular binding partner of the papillomavirus E5 proteins

E5 proteins are amongst the least understood of the Human Papillomavirus (HPV) encoded gene products. They are small, membrane-integrated proteins known to modulate a number of critical host pathways associated with pathogenesis including growth factor receptor signaling and immune evasion. Their role in the virus life cycle is less clear, indicating a role in the productive stages of the life cycle. However, a mechanism for this is currently lacking. Here we describe the identification of a novel binding partner of E5, YIPF4 using yeast two-hybrid analysis. YIPF4 is also a poorly characterized membrane spanning protein. Mutagenesis studies implicated the transmembrane regions of each protein as important for their interaction. Binding to YIPF4 was found for all E5 proteins tested suggesting that this interaction may mediate a conserved E5 function. In normal human keratinocytes YIPF4 expression was down-regulated upon differentiation and this reduction was partially rescued in cells harbouring HPV. Despite the conserved nature of the interaction with E5, siRNA mediated depletion of YIPF4 failed to impede two well-characterized functions of E5, namely EGFR trafficking or HLA class I presentation. Continued studies of YIPF4 are warranted to determine its role in the PV life cycle

Diastolic function alteration mechanisms in physiologic hypertrophy versus pathologic hypertrophy are elucidated by model-based Doppler E-wave analysis.

Athletic training can result in increased left ventricular (LV) wall thickness, termed physiologic hypertrophy (PhH). By contrast, pathologic hypertrophy (PaH) can be due to hypertension, aortic stenosis, or genetic mutation causing hypertrophic cardiomyopathy (HCM). Because morphologic (LV dimension, wall thickness, mass, etc.) and functional index similarities (LV ejection fraction, cardiac output, peak filling rate, etc.) limit diagnostic specificity, ability to differentiate between PhH and PaH is important. Conventional echocardiographic diastolic function (DF) indexes have limited ability to differentiate between PhH and PaH and cannot provide information on chamber property (stiffness and relaxation). We hypothesized that kinematic model-based DF assessment can differentiate between PhH and PaH and, by providing chamber properties, has even greater value compared with conventional metrics. For validation, we assessed DF in the following three age-matched groups: pathologic (HCM) hypertrophy (PaH, n = 14), PhH (Olympic rowers, PhH, n = 21), and controls (n = 21). Magnetic resonance imaging confirmed presence of both types of hypertrophy and determined LV mass and chamber size. Model-based indexes, chamber stiffness (k), relaxation/viscoelasticity (c), and load (xo) and conventional indexes, Epeak (peak of E-wave), ratio of Epeak to Apeak (E/A), E-wave acceleration time (AT), and E-wave deceleration time (DT) were computed. We analyzed 1588 E waves distributed as follows: 328 (PaH), 672 (athletes), and 588 (controls). Among conventional indexes, Epeak and E-wave DT were similar between PaH and PhH, whereas E/A and E-wave AT were lower in PaH. Model-based analysis showed that PaH had significantly higher relaxation/viscoelasticity (c) and chamber stiffness (k) than PhH. The physiologic equation of motion for filling-based derivation of the model provides a mechanistic understanding of the differences between PhH and PaH

IVUS-histology image registration.

In this paper, for the first time, we present a systematic framework to register intravascular ultrasound (IVUS) images with histology correspondences. We deployed intermediate representations of images, generating segmentation masks corresponding to lumen and media-adventitia borders for both histology and IVUS images, incorporated into a non-rigid registration framework using discrete multi-labeling and approximate curvature penalty for smoothness regularization. The resulting deformation field was then applied to the original histology image to transfer it to IVUS coordinate system. Finally, the results were quantified on 14 cross sections of interest. The main contribution of this work is that the registered results could be used for systematic labeling of tissues, which ultimately will lead to reliable construction of training dataset for feature extraction and supervised classification of atherosclerotic tissues

Wild places: mountain

'Wild Places: Mountain' is a contemporary dance piece by dancer/choreographers Roosna and Flak. Joseph Hyde contributed the music and the sensor programming. It was built around Sense:Stage sensors allowing dancers to control sound, video and lighting. It was made during a series of residencies in late 2014 and early 2015 in Talinn and Den Haag. It was commissioned by Korzo Theatre and premiered in February 2015 in the CaDance festival