CMOS-compatible graphene photodetector covering all optical communication bands

Optical interconnects are becoming attractive alternatives to electrical wiring in intra- and inter-chip communication links. Particularly, the integration with silicon complementary metal-oxide-semiconductor (CMOS) technology has received considerable interest due to the ability of cost-effective integration of electronics and optics on a single chip. While silicon enables the realization of optical waveguides and passive components, the integration of another, optically absorbing, material is required for photodetection. Germanium or compound semiconductors are traditionally used for this purpose; their integration with silicon technology, however, faces major challenges. Recently, graphene has emerged as a viable alternative for optoelectronic applications, including photodetection. Here, we demonstrate an ultra-wideband CMOS-compatible photodetector based on graphene. We achieve multi-gigahertz operation over all fiber-optic telecommunication bands, beyond the wavelength range of strained germanium photodetectors, whose responsivity is limited by their bandgap. Our work complements the recent demonstration of a CMOS-integrated graphene electro-optical modulator, paving the way for carbon-based optical interconnects.Comment: 18 pages, 4 figures. Nature Photonics, 201

Funnel control for systems with relative degree two

PublishedJournal ArticleTracking of reference signals yref (·) by the output y(·) of linear (as well as a considerably large class of nonlinear) single-input, single-output systems is considered. The system is assumed to have strict relative degree two with (weakly) stable zero dynamics. The control objective is tracking of the error e = y - yref and its derivative e within two prespecified performance funnels, respectively. This is achieved by the so-called funnel controller u(t) = -k0(t)2e(t)-k 1(t)e(t), where the simple proportional error feedback has gain functions k0 and k1 designed in such a way to preclude contact of e and e with the funnel boundaries, respectively. The funnel controller also ensures boundedness of all signals. We also show that the same funnel controller (i) is applicable to relative degree one systems, (ii) allows for input constraints provided a feasibility condition (formulated in terms of the system data, the saturation bounds, the funnel data, bounds on the reference signal, and the initial state) holds, (iii) is robust in terms of the gap metric: if a system is sufficiently close to a system with relative degree two, stable zero dynamics, and positive high-frequency gain, but does not necessarily have these properties, then for small initial values the funnel controller also achieves the control objective. Finally, we illustrate the theoretical results by experimental results: the funnel controller is applied to a rotatory mechanical system for position control. © 2013 Society for Industrial and Applied Mathematics

The VLTI/MIDI survey of massive young stellar objects - Sounding the inner regions around intermediate- and high-mass young stars using mid-infrared interferometry

We aim to characterize the distribution and composition of circumstellar material around young massive stars, and to investigate exactly which physical structures in these objects are probed by long-baseline mid-infrared interferometric observations. We used the two-telescope interferometric instrument MIDI of the Very Large Telescope Interferometer of the European Southern Observatory to observe a sample of 24 intermediate- and high-mass young stellar objects in the N band (8-13 micron). We had successful fringe detections for 20 objects, and present spectrally-resolved correlated fluxes and visibility levels for projected baselines of up to 128 m. We fit the visibilities with geometric models to derive the sizes of the emitting regions, as well as the orientation and elongation of the circumstellar material. Fourteen objects in the sample show the 10 micron silicate feature in absorption in the total and correlated flux spectra. For 13 of these objects, we were able to fit the correlated flux spectra with a simple absorption model, allowing us to constrain the composition and absorptive properties of the circumstellar material. Nearly all of the massive young stellar objects observed show significant deviations from spherical symmetry at mid-infrared wavelengths. In general, the mid-infrared emission can trace both disks and outflows, and in many cases it may be difficult to disentangle these components on the basis of interferometric data alone, because of the sparse spatial frequency coverage normally provided by current long-baseline interferometers. For the majority of the objects in this sample, the absorption occurs on spatial scales larger than those probed by MIDI. Finally, the physical extent of the mid-infrared emission around these sources is correlated with the total luminosity, albeit with significant scatter.Comment: 36 pages, 22 figures. Accepted to Astronomy and Astrophysic

Atmospheric Benzene Observations from an Oil and Gas Field in the Denver Julesburg Basin in July and August 2014

High time resolution measurements of volatile organic compounds (VOCs) were collectedusing a proton-transfer-reaction quadrupole mass spectrometry (PTR-QMS) instrument at the PlattevilleAtmospheric Observatory (PAO) in Colorado to investigate how oil and natural gas (ONG) developmentimpacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurementswere carried out in July and August 2014 as part of NASAs Deriving Information on Surface Conditions fromColumn and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaign. ThePTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontalsurveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (meanbenzene 0.53 ppbv, maximum benzene 29.3 ppbv), primarily at night (mean nighttime benzene 0.73ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurementsindicate that benzene originated from within the WGF, and typical source signatures detected in the canistersamples implicate emissions from ONG activities rather than urban vehicular emissions as primary benzenesource. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerlyflow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that trafficemissions were not responsible for the observed high benzene levels. Previous measurements at the BoulderAtmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzeneenhancements between the two atmospheric observatories. Fugitive emissions of benzene from ONGoperations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO

International forum. an investigation of iron status in blood donors

No abstract availabl

Multi-National Topics Maps for Parliamentary Debate Analysis

In recent years, automated political text processing became an indispensable requirement for providing automatic access to political debate. During the Covid-19 worldwide pandemic, this need became visible not only in social sciences but also in public opinion. We provide a path to operationalize this need in a multi-lingual topic-oriented manner. Using a publicly available data set consisting of parliamentary speeches, we create a novel process pipeline to identify a good reference model and to link national topics to the cross-national topics. We use design science research to create this process pipeline as an artifact

TGA2 signaling in response to reactive electrophile species is not dependent on cysteine modification of TGA2

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Reactive electrophile species (RES), including prostaglandins, phytoprostanes and 12-oxo phytodienoic acid (OPDA), activate detoxification responses in plants and animals. However, the pathways leading to the activation of defense reactions related to abiotic or biotic stress as a function of RES formation, accumulation or treatment are poorly understood in plants. Here, the thiol-modification of proteins, including the RES-activated basic region/leucine zipper transcription factor TGA2, was studied. TGA2 contains a single cysteine residue (Cys186) that was covalently modified by reactive cyclopentenones but not required for induction of detoxification genes in response to OPDA or prostaglandin A1. Activation of the glutathione-S-transferase 6 (GST6) promoter was responsive to cyclopentenones but not to unreactive cyclopentanones, including jasmonic acid suggesting that thiol reactivity of RES is important to activate the TGA2-dependent signaling pathway resulting in GST6 activation We show that RES modify thiols in numerous proteins in vivo, however, thiol reactivity alone appears not to be sufficient for biological activity as demonstrated by the failure of several membrane permeable thiol reactive reagents to activate the GST6 promoter.Peer reviewedFinal Published versio

Genome-wide mapping of genetic determinants influencing DNA methylation and gene expression in human hippocampus

Emerging evidence emphasizes the strong impact of regulatory genomic elements in neurodevelopmental processes and the complex pathways of brain disorders. The present genome-wide quantitative trait loci analyses explore the cis-regulatory effects of single-nucleotide polymorphisms (SNPs) on DNA methylation (meQTL) and gene expression (eQTL) in 110 human hippocampal biopsies. We identify cis-meQTLs at 14,118 CpG methylation sites and cis-eQTLs for 302 3'-mRNA transcripts of 288 genes. Hippocampal cis-meQTL-CpGs are enriched in flanking regions of active promoters, CpG island shores, binding sites of the transcription factor CTCF and brain eQTLs. Cis-acting SNPs of hippocampal meQTLs and eQTLs significantly overlap schizophrenia-associated SNPs. Correlations of CpG methylation and RNA expression are found for 34 genes. Our comprehensive maps of cis-acting hippocampal meQTLs and eQTLs provide a link between disease-associated SNPs and the regulatory genome that will improve the functional interpretation of non-coding genetic variants in the molecular genetic dissection of brain disorders

Illuminating hydrological processes at the soil-vegetation-atmosphere interface with water stable isotopes

Funded by DFG research project “From Catchments as Organised Systems to Models based on Functional Units” (FOR 1Peer reviewedPublisher PDFPublisher PD

Review of magnetic gear technologies and their applications in marine energy

The marine energy industry is in its early stages but has a large potential for growth. One of the most significant challenges is the reduction of operation and maintenance costs. Magnetic gears (MGs) offer the potential for long periods between maintenance intervals due to their frictionless torque transmission which could reduce these costs. This study presents a summary of the state of the art in MG technology and then investigates its potential for marine energy applications. A brief overview is given of the state of the marine energy industry and the environment in which marine energy converters (MECs) operate. A short history of MG development over the past century is then presented followed by a discussion of the leading MG technologies and their relative advantages. In order to demonstrate the potential of MGs in marine applications, the current technologies, i.e. mechanically geared and direct drive machines, are examined in terms of sizing, reliability and economic value using previous studies on a similar technology, namely wind. MGs are applied to four types of MECs to demonstrate how the technology can be incorporated. The potential to deploy at scale and potential obstacles to this are then discussed