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

6sterreichische Wasser- und Abfallwirtschaft / Synthetisch hergestellte Nanomaterialien in Konsumprodukten und deren Verbleib am Ende ihrer Nutzungsphase

Seit geraumer Zeit finden k\ufcnstlich hergestellte und oberfl\ue4chenmodifizierte Nanomaterialien in diversen Alltagsprodukten Anwendung. F\ufcr die gegenst\ue4ndliche Materialflussanalyse wurden 6 Nanokonsumprodukte ausgew\ue4hlt, die am \uf6sterreichischen Markt erh\ue4ltlich sind und vorwiegend metallische Nanomaterialien enthalten (d. h.: Nano-SiO2, -TiO2, -Ag oder CdSe-Quantenpunkte). Ein Produktbeispiel enthielt Kohlenstoffnanor\uf6hrchen (kurz CNTs). F\ufcr die Materialflussanalysen mussten die Nanomaterial-Inputmengen auf Produktebene abgesch\ue4tzt werden. Anhand von Produktinformationen sowie wissenschaftlichen Publikationen wurden erste Hochrechnungen des \uf6sterreichweiten Verbrauchs durchgef\ufchrt. Beim Produktbeispiel \u201eTV-Ger\ue4te mit Quantenpunkt-Displays\u201c war die Datengrundlage so d\ufcrftig, dass keine Mengenabsch\ue4tzung m\uf6glich war. Dieses Szenario ist aber Beispiel daf\ufcr, dass bei vielen Produktkategorien mangelnde bis keine Produktinformationen vorliegen und f\ufcr diese daher derzeit keine quantitative Absch\ue4tzung des Verbleibs von Nanomaterialien in Abfallstr\uf6men m\uf6glich ist. Die ersten Mengenabsch\ue4tzungen zeigen, dass Nano-TiO2 bereits im Tonnenma fstab in Sonnencremen eingesetzt wird (in 6sterreich ca. 5,4 bis 40,8 t/a). Nano-SiO2 in Autoversiegelungen, Nano-Ag in Wandfarben oder Putzlappen sowie CNTs in Tennisschl\ue4gern werden hingegen eher im unteren einstelligen Kilogrammma fstab eingesetzt. Anhand der Materialflussanalysen l\ue4sst sich absch\ue4tzen, dass sich metallische/metalloxidische Nanomaterialien mit hoher Wahrscheinlichkeit im Zuge der Abfallbehandlung in Sekund\ue4rabf\ue4llen, wie Verbrennungsr\ufcckst\ue4nden, anreichern, welche wiederum gr\uf6 ftenteils deponiert werden. Kohlenstoffbasierte Nanomaterialien wie CNTs werden mit hoher Wahrscheinlichkeit w\ue4hrend der Abfallverbrennung vollst\ue4ndig oxidiert. Ihre Elimination kann aber nur dann gew\ue4hrleistet werden, wenn w\ue4hrend der Verbrennung eine entsprechend lange Verweildauer bei hohen Temperaturen sichergestellt ist. Die Unsicherheiten bzw. gro fen Schwankungsbreiten der hochgerechneten Nanomaterialfl\ufcsse verdeutlichen, dass es noch gro fe Wissens- und Informationsl\ufccken gibt und vor allem entsprechender Forschungsbedarf hinsichtlich des genauen Umweltverhaltens von Nanoprodukten \u2013 insbesondere \ufcber das Verhalten und potenzielle Freisetzungspfade in der Entsorgungsphase \u2013 besteht.For some time now, engineered and surface-modified nanomaterials have been used in various everyday products. For the material flow analyses presented in the following paper, six nano-based consumer products were selected that are available on the Austrian market and primarily contain metallic nanomaterials (nano-SiO2, -TiO2, -Ag or CdSe quantum dots); one sample product contained carbon nanotubes (CNTs). For the purpose of the material flow analyses, it was necessary to estimate the amounts of nanomaterial input at the product level. On the basis of available product information and academic publications, initial estimates of consumption in Austria were prepared. In the case of the sample product \u201ctelevisions with quantum dot displays,\u201d there was too little data available to do so. However, this scenario offers valuable proof of the fact that little to no product information is available for many product categories, making it impossible to quantitatively estimate the amount of nanomaterials in waste streams. The initial estimates show that tons of nano-TiO2 are already used in sun creams (ca. 5.4 to 40.8 t/year in Austria). In contrast, only several kilograms each of nano-SiO2 (in automotive paint sealants), nano-Ag (in indoor paints and washcloths), and CNTs (in tennis rackets) are used each year. Based on the material flow analyses it can be assumed that, in the course of waste treatment, metallic/metal oxide nanomaterials very likely enrich in secondary waste like combustion residues, which in turn predominantly end up in landfills. Carbon-based nanomaterials like CNTs are most likely completely oxidized in the course of incineration. However, their elimination can only be ensured if they are subjected to high temperatures for a sufficiently long time. The uncertainties/substantial variances in the projected nanomaterial flows clearly show that there are still considerable gaps in our knowledge and available information, and that research regarding the exact environmental fate of nano-products \u2013 especially into their behavior and potential emission pathways in the disposal phase \u2013 is urgently needed

Benchmark Phaseless Auxiliary-Field Quantum Monte Carlo Method for Small Molecules

We report a scalable Fortran implementation of the phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) and demonstrate its excellent performance and beneficial scaling with respect to system size. Furthermore, we investigate modifications of the phaseless approximation that can help to reduce the overcorrelation problems common to the ph-AFQMC. We apply the method to the 26 molecules in the HEAT set, the benzene molecule, and water clusters. We observe a mean absolute deviation of the total energy of 1.15 kcal/mol for the molecules in the HEAT set; close to chemical accuracy. For the benzene molecule, the modified algorithm despite using a single-Slater-determinant trial wavefunction yields the same accuracy as the original phaseless scheme with 400 Slater determinants. Despite these improvements, we find systematic errors for the CN, CO$_2$, and O$_2$ molecules that need to be addressed with more accurate trial wavefunctions. For water clusters, we find that the ph-AFQMC yields excellent binding energies that differ from CCSD(T) by typically less than 0.5 kcal/mol.Comment: 13 pages, 7 figure

Current Productions Carnuntum, German Limes and Radiopast

[EN] The here presented three chosen projects mark out different techniques of production and their transmission of content. The differentiated impact on the public absorption of the transported content are described dependent to experiences with it in exhibitions and publications, and can be used to rectify future approaches of similar topics. In most of these productions, technical difficulties were observed and solved through extensive use of different tools and techniques to achieve a reasonable output and represent our current state of knowledge which we would like to share. The documentation of the production as well as the communication between the production and research team is indispensable to the sucsess of these media formats.[ES] Presento tres proyectos elegidos que delimitan técnicas diferentes de la producción y su transmisión de contenido. El impacto diferenciado en la absorción pública del contenido es descrito dependiente a experiencias con ello en exposiciones y publicaciones, y puede ser usado para rectificar futuros acercamientos de temas similares. En la mayor parte de estas producciones, las dificultades técnicas fueron estudiadas y solucionadas por el uso extenso de instrumentos diferentes y técnicas para conseguir una salida razonable y representar nuestro estado del conocimiento que nos gustaría compartir. La documentación de la producción así como la comunicación entre la producción y grupo de investigación es indispensable en estos formatos multimedia.The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007- 2013) under grant agreement n° 230679, under the action Marie Curie – People IAPP, with the Project entitled “Radiography of the past. Integrated non-destructive approaches to understand and valorise complex archaeological sitesHumer, F.; Gugl, C.; Pregesbauer, M.; Vermeulen, F.; Corsi, C.; Klein, M. (2011). Current Productions Carnuntum, German Limes and Radiopast. Virtual Archaeology Review. 2(4):131-137. https://doi.org/10.4995/var.2011.4569OJS13113724CORSI C., DE DAPPER M., DE PREZ S., VERMEULEN F. (2005). Geoarchaeological observations on the Roman town of Ammaia, Internet Archaeology 19.CORSI C., VERMEULEN F. (2007). Elementi per la ricostruzione del paesaggio urbano e suburbano della città romana di Ammaia in Lusitania, Lusitania, Archeologia Aerea 3: 13-30.DEPREZ S., DE DAPPER M. & DE JAEGER C. (2006), The water supply of the Roman town of Ammaia (Northeastern Alentejo, Portugal): a geoarchaeological case study, Publicações da Associação Portuguesa de Geomorfólogos 3: 109-133.MANTAS V. (2000). A sociedade luso-romano do município de Ammaia, in: Gorges J.-G. & Nogales Basarrate T. (Eds.), Sociedad y cultura en Lusitania romana, Mérida, Museo Nacional de Arte Romano: 391-420.http://www.carnuntum.co.at/ , http://www.carnuntum-db.at/, http://www.limes.co.at/, http://7reasons.at/http://www.limeswelten.net/, http://www.arctron.de/, http://7reasons.at

Assessment of the Potential Use of Compost Filled Plastic Void Forming Units to Serve as Vents on Historic Landfills and Related Sites

Much of the solid municipal waste generated by society is sent to landfill, where biodegrading processes result in the release of methane, a major contributor to climate change. This work examined the possibility of installing a type of biofilter within paved areas of the landfill site, making use of modified pervious paving, both to allow the escape of ground gas and to avoid contamination of groundwater, using specially designed test models with provision for gas sampling in various chambers. It proposes the incorporation of an active layer within a void forming box with a view to making dual use of the pervious pavement to provide both a drainage feature and a ground gas vent, whilst providing an active layer for the oxidation of methane by microbial action. The methane removal was observed to have been effected by microbial oxidation and as such offers great promise as a method of methane removal to allow for development of landfills.<br/

Bivariate jointness measures in Bayesian Model Averaging: Solving the conundrum

We introduce a new measure of bivariate jointness to assess the degree of inclusion dependency between pairs of explanatory variables in Bayesian Model Averaging analysis. Building on the discussion concerning appropriate statistics to assess covariate inclusion dependency in this context, a set of desirable properties for bivariate jointness measures is proposed. We show that none of the proposed measures so far meets all these criteria and an alternative measure is presented which fulfils all of them. Our measure corresponds to a regularised version of the Yule’s Q association coefficient, obtained by combining the original measure with a Jeffreys prior to avoid problems in the case of zero counts. We provide an empirical illustration using cross-country data on economic growth and its determinants

Safer_RAIN: A DEM-based hierarchical filling-&-spilling algorithm for pluvial flood hazard assessment and mapping across large urban areas

The increase in frequency and intensity of extreme precipitation events caused by the changing climate (e.g., cloudbursts, rainstorms, heavy rainfall, hail, heavy snow), combined with the high population density and concentration of assets, makes urban areas particularly vulnerable to pluvial flooding. Hence, assessing their vulnerability under current and future climate scenarios is of paramount importance. Detailed hydrologic-hydraulic numerical modeling is resource intensive and therefore scarcely suitable for performing consistent hazard assessments across large urban settlements. Given the steadily increasing availability of LiDAR (Light Detection And Ranging) high-resolution DEMs (Digital Elevation Models), several studies highlighted the potential of fast-processing DEM-based methods, such as the Hierarchical Filling-&amp;-Spilling or Puddle-to-Puddle Dynamic Filling-&amp;-Spilling Algorithms (abbreviated herein as HFSAs). We develop a fast-processing HFSA, named Safer_RAIN, that enables mapping of pluvial flooding in large urban areas by accounting for spatially distributed rainfall input and infiltration processes through a pixel-based Green-Ampt model. We present the first applications of the algorithm to two case studies in Northern Italy. Safer_RAIN output is compared against ground evidence and detailed output from a two-dimensional (2D) hydrologic and hydraulic numerical model (overall index of agreement between Safer_RAIN and 2D benchmark model: sensitivity and specificity up to 71% and 99%, respectively), highlighting potential and limitations of the proposed algorithm for identifying pluvial flood-hazard hotspots across large urban environments