281 research outputs found

    Josephson Junctions defined by a Nano-Plough

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    We define superconducting constrictions by ploughing a deposited Aluminum film with a scanning probe microscope. The microscope tip is modified by electron beam deposition to form a nano-plough of diamond-like hardness, what allows the definition of highly transparent Josephson junctions. Additionally a dc-SQUID is fabricated to verify appropriate functioning of the junctions. The devices are easily integrated in mesoscopic devices as local radiation sources and can be used as tunable on-chip millimeter wave sources

    Microwave spectroscopy on a double quantum dot with an on-chip Josephson oscillator

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    We present measurements on microwave spectroscopy on a double quantum dot with an on-chip microwave source. The quantum dots are realized in the two-dimensional electron gas of an AlGaAs/GaAs heterostructure and are weakly coupled in series by a tunnelling barrier forming an 'ionic' molecular state. We employ a Josephson oscillator formed by a long Nb/Al-AlOx_x/Nb junction as a microwave source. We find photon-assisted tunnelling sidebands induced by the Josephson oscillator, and compare the results with those obtained using an externally operated microwave source.Comment: 6 pages, 4 figure

    Spectroscopic determination of hole density in the ferromagnetic semiconductor Ga1−x_{1-x}Mnx_{x}As

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    The measurement of the hole density in the ferromagnetic semiconductor Ga1−x_{1-x}Mnx_{x}As is notoriously difficult using standard transport techniques due to the dominance of the anomalous Hall effect. Here, we report the first spectroscopic measurement of the hole density in four Ga1−x_{1-x}Mnx_{x}As samples (x=0,0.038,0.061,0.083x=0, 0.038, 0.061, 0.083) at room temperature using Raman scattering intensity analysis of the coupled plasmon-LO-phonon mode and the unscreened LO phonon. The unscreened LO phonon frequency linearly decreases as the Mn concentration increases up to 8.3%. The hole density determined from the Raman scattering shows a monotonic increase with increasing xx for x≀0.083x\leq0.083, exhibiting a direct correlation to the observed TcT_c. The optical technique reported here provides an unambiguous means of determining the hole density in this important new class of ``spintronic'' semiconductor materials.Comment: two-column format 5 pages, 4 figures, to appear in Physical Review

    RNAseq analysis of Aspergillus fumigatus in blood reveals a just wait and see resting stage behavior

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    Background: Invasive aspergillosis is started after germination of Aspergillus fumigatus conidia that are inhaled by susceptible individuals. Fungal hyphae can grow in the lung through the epithelial tissue and disseminate hematogenously to invade into other organs. Low fungaemia indicates that fungal elements do not reside in the bloodstream for long. Results: We analyzed whether blood represents a hostile environment to which the physiology of A. fumigatus has to adapt. An in vitro model of A. fumigatus infection was established by incubating mycelium in blood. Our model allowed to discern the changes of the gene expression profile of A. fumigatus at various stages of the infection. The majority of described virulence factors that are connected to pulmonary infections appeared not to be activated during the blood phase. Three active processes were identified that presumably help the fungus to survive the blood environment in an advanced phase of the infection: iron homeostasis, secondary metabolism, and the formation of detoxifying enzymes. Conclusions: We propose that A. fumigatus is hardly able to propagate in blood. After an early stage of sensing the environment, virtually all uptake mechanisms and energy-consuming metabolic pathways are shut-down. The fungus appears to adapt by trans-differentiation into a resting mycelial stage. This might reflect the harsh conditions in blood where A. fumigatus cannot take up sufficient nutrients to establish self-defense mechanisms combined with significant growth

    Spin polarization of the L-gap surface states on Au(111)

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    The electron spin polarization (ESP) of the L-gap surface states on Au(111) is investigated theoretically by means of first-principles electronic-structure and photoemission calculations. The surface states show a large spin-orbit induced in-plane ESP which is perpendicular to the in-plane wavevector, in close analogy to a two-dimensional electron gas with Rashba spin-orbit interaction. The surface corrugation leads to a small ESP component normal to the surface, being not reported so far. The surface-states ESP can be probed qualitatively and quantitatively by spin- and angle-resolved photoelectron spectroscopy, provided that the initial-state ESP is retained in the photoemission process and not obscured by spin-orbit induced polarization effects. Relativistic photoemission calculations provide detailed information on what photoemission set-ups allow to conclude from the photoelectron ESP on that of the surface states.Comment: 22 pages with 8 figure

    Investigation of contact deformation and wear characteristics of discrete track recording media

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    The even semester 2014/2015 Technical Information Engineering University of Semarang (USM) has been running the Competency Based Curriculum (CBC) in the management of learning. Conversions that occur in some subjects at an increase in scheduled meetings in the classroom or in the laboratory. Computer Networks is one of the subjects who experienced a conversion. In the curriculum in 2008, Computer Networking has a number of credits 3. From the 2 credits 3 credits are for credits 1 credits for theory and practical credits. While at the CBC in 2013, Computer Networking has 4 credits, with details of 2 credits 2 credits theory and practicum. As lecture and instructor Computer Network, researchers interested in studying the effect of applying the CBC in 2013 in the subje ct of Computer Network. Does the addition of meeting practical and theoretical material renewal in accordance with the expected competencies?. Researchers tried applying the CBC in 2013 by conducting action research. Implementation of the research was conducted during an ongoing lecture that even semester 2015/2016. The results of the study during the first half of researchers will compare with the achievements that never existed when the old curriculum still in use. The goals of this research is, subjects in the Computer Network has always been one of the subjects that the content of the material and its application in the lab was able to follow the needs of the workforc

    Ultrasonography of the reticulum in 30 healthy Saanen goats

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    Background: The reticulum plays a crucial role in the ruminant digestive tract because the primary cycle of rumen motility always starts with a reticular contraction. In contrast to cattle, there are only few results on the ultrasonographic examination of the reticulum in goats. Therefore, it was the goal of the present study, to describe the results of ultrasonography of the reticulum of 30 healthy Saanen goats. Methods: Ultrasonography was carried out on standing, non-sedated animals using a 5.0 MHz linear transducer. The shape, contour and motility of the reticulum were investigated. A nine-minute video recording of the reticulum was made for each goat and the frequency, duration and amplitude of reticular contractions were calculated as described for cattle. Results: The reticulum appeared as a crescent-shaped structure with a smooth contour located immediately adjacent to the diaphragm. 0.8 to 2.1 (1.41 ± 0.31) reticular contractions were seen per minute. In all goats, biphasic reticular contractions were observed. 90% of the goats also had monophasic reticular contractions, and two had triphasic contractions. During the nine-minute observation periods, there were 0 to 6 monophasic reticular contractions and 6 to 15 biphasic contractions per goat. The duration of the biphasic contractions was 6.56 ± 0.74 s, which was significantly longer than the monophasic contractions at 4.31 ± 0.81 s. The average interval between two reticular contractions was 45.06 ± 12.57 s. Conclusion: Ultrasonography of the reticulum in goats is a valuable tool to characterise the appearance and motility of this organ. In addition to the biphasic motility pattern seen in cattle the reticular motility of goats is characterized by monophasic reticular contractions. The results of the present study are an important contribution for better understanding of the reticular motility in goats

    Automatic identification of relevant chemical compounds from patents

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    In commercial research and development projects, public disclosure of new chemical compounds often takes place in patents. Only a small proportion of these compounds are published in journals, usually a few years after the patent. Patent authorities make available the patents but do not provide systematic continuous chemical annotations. Content databases such as Elsevier’s Reaxys provide such services mostly based on manual excerptions, which are time-consuming and costly. Automatic text-mining approaches help overcome some of the limitations of the manual process. Different text-mining approaches exist to extract chemical entities from patents. The majority of them have been developed using sub-sections of patent documents and focus on mentions of compounds. Less attention has been given to relevancy of a compound in a patent. Relevancy of a compound to a patent is based on the patent’s context. A relevant compound plays a major role within a patent. Identification of relevant compounds reduces the size of the extracted data and improves the usefulness of patent resources (e.g. supports identifying the main compounds). Annotators of databases like Reaxys only annotate relevant compounds. In this study, we design an automated system that extracts chemical entities from patents and classifies their relevance. The goldstandard set contained 18 789 chemical entity annotations. Of these, 10% were relevant compounds, 88% were irrelevant and 2% were equivocal. Our compound recognition system was based on proprietary tools. The performance (F-score) of the system on compound recognition was 84% on the development set and 86% on the test set. The relevancy classification system had an F-score of 86% on the development set and 82% on the test set. Our system can extract chemical compounds from patents and classify their relevance with high performance. This enables the extension of the Reaxys database by means of automation
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