738 research outputs found
Thermal insulation blanket material
A study was conducted to provide a tailorable advanced blanket insulation based on a woven design having an integrally woven core structure. A highly pure quartz yarn was selected for weaving and the cells formed were filled with a microquartz felt insulation
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Assessing the Graphical Perception of Time and Speed on 2D+Time Trajectories
We empirically evaluate the extent to which people perceive non-constant time and speed encoded on 2D paths. In our graphical perception study, we evaluate nine encodings from the literature for both straight and curved paths. Visualizing time and speed information is a challenge when the x and y axes already encode other data dimensions, for example when plotting a trip on a map. This is particularly true in disciplines such as time-geography and movement analytics that often require visualizing spatio-temporal trajectories. A common approach is to use 2D+time trajectories, which are 2D paths for which time is an additional dimension. However, there are currently no guidelines regarding how to represent time and speed on such paths. Our study results provide InfoVis designers with clear guidance regarding which encodings to use and which ones to avoid; in particular, we suggest using color value to encode speed and segment length to encode time whenever possible
Bestimmung von Intensität und Position des extrahierten Elektronenstrahls an ELSA mittels Hochfrequenzresonatoren
Am Physikalischen Institut der Universität Bonn werden Experimente zur Untersuchung der Nukleonenstruktur betrieben. Aus dem Speicherring der Beschleunigeranlage ELSA wird zu diesem Zweck ein Elektronenstrahl von einigen hundert Picoampère extrahiert und auf ein Radiatortarget zur Erzeugung von Bremsstrahlungsphotonen gelenkt. Zur korrekten Interpretation der untersuchten Ereignisse im Experimentaufbau ist die Aufrechterhaltung der eingestellten Strahlposition erforderlich, weswegen ein System zu deren permanenter Kontrolle eingerichtet wurde. Um die Strahlqualität im Messbetrieb nicht zu beeinträchtigen, wurde auf Hohlraumresonatoren zurückgegriffen. Die Überhöhung der Feldstärken bei resonanter Anregung durch die Teilchenpakete des Strahls ermöglicht die Extraktion messbarer Signale bei einer Frequenz von 1,5 Gigahertz und Leistungen unter einem Attowatt. Nach Verstärkung und Umsetzung der Signale auf eine Frequenz von wenigen Kilohertz erfolgt eine schmalbandige Gleichrichtung durch Lock-In-Verstärker. Über einen PC werden die Messspannungen mit einer Rate von 9 Hertz ausgelesen, mit einem C++-Programm in die gesuchten Strahlparameter umgerechnet und dann zur Anzeige im Beschleuniger-Kontrollsystem aufbereitet. Im Regelbetrieb kann so die Strahlposition am Radiatortarget auf Millimeterbruchteile genau erfasst werden. Die Lagesignale müssen auf die Stromstärke normiert werden, deren Messung ebenfalls über einen Resonator erfolgt. Die auf wenige Picoampère genauen Messwerte ermöglichen die unmittelbare Steuerung des Extraktionsmechanismus zur Einstellung des erwünschten Strahlstroms
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Active Reading of Visualizations
We investigate whether the notion of active reading for text might be usefully applied to visualizations. Through a qualitative study we explored whether people apply observable active reading techniques when reading paper-based node-link visualizations. Participants used a range of physical actions while reading, and from these we synthesized an initial set of active reading techniques for visualizations. To learn more about the potential impact such techniques may have on visualization reading, we implemented support for one type of physical action from our observations (making freeform marks) in an interactive node-link visualization. Results from our quantitative study of this implementation show that interactive support for active reading techniques can improve the accuracy of performing low-level visualization tasks. Together, our studies suggest that the active reading space is ripe for research exploration within visualization and can lead to new interactions that make for a more flexible and effective visualization reading experience
TWAM: A Certifying Abstract Machine for Logic Programs
Type-preserving (or typed) compilation uses typing derivations to certify
correctness properties of compilation. We have designed and implemented a
type-preserving compiler for a simply-typed dialect of Prolog we call T-Prolog.
The crux of our approach is a new certifying abstract machine which we call the
Typed Warren Abstract Machine (TWAM). The TWAM has a dependent type system
strong enough to specify the semantics of a logic program in the logical
framework LF. We present a soundness metatheorem which constitutes a partial
correctness guarantee: well-typed programs implement the logic program
specified by their type. This metatheorem justifies our design and
implementation of a certifying compiler from T-Prolog to TWAM.Comment: 41 pages, under submission to ACM Transactions on Computational Logi
Role of PKC in the Regulation of the Human Kidney Chloride Channel ClC-Ka
The physiological role of the renal ClC-Ka/ClC-K1 channels is to confer a high Cl- permeability to the thin Ascending Limb of Henle (tAL), which in turn is essential for establishing the high osmolarity of the renal medulla that drives water reabsorption from collecting ducts. Here, we investigated by whole-cell patch-clamp measurements on HEK293 cells co-expressing ClC-Ka (tagged with GFP) and the accessory subunit barttin (tagged with m-Cherry) the effect of a natural diuretic extract from roots of Dandelion (DRE), and other compounds activating PKC, such as ATP, on ClC-Ka activity and its membrane localization. Treatment with 400 µg/ml DRE significantly inhibited Cl- currents time-dependently within several minutes. Of note, the same effect on Cl- currents was obtained upon treatment with 100 µM ATP. Pretreatment of cells with either the intracellular Ca2+ chelator BAPTA-AM (30 μM) or the PKC inhibitor Calphostin C (100 nM) reduced the inhibitory effect of DRE. Conversely, 1 µM of phorbol meristate acetate (PMA), a specific PKC activator, mimicked the inhibitory effect of DRE on ClC-Ka. Finally, we found that pretreatment with 30 µM Heclin, an E3 ubiquitin ligase inhibitor, did not revert DRE-induced Cl- current inhibition. In agreement with this, live-cell confocal analysis showed that DRE treatment did not induce ClC-Ka internalization. In conclusion, we demonstrate for the first time that the activity of ClC-Ka in renal cells could be significantly inhibited by the activation of PKC elicited by classical maneuvers, such as activation of purinergic receptors, or by exposure to herbal extracts that activates a PKC-dependent pathway. Overall, we provide both new information regarding the regulation of ClC-Ka and a proof-of-concept study for the use of DRE as new diuretic
Impact of Size, Secondary Structure, and Counterions on the Binding of Small Ribonucleic Acids to Layered Double Hydroxide Nanoparticles
Use of ribonucleic acid (RNA) interference to regulate protein expression has become an important research topic and gene therapy tool, and therefore, finding suitable vehicles for delivery of small RNAs into cells is of crucial importance. Layered double metal hydroxides such as hydrotalcite (HT) have shown great promise as nonviral vectors for transport of deoxyribose nucleic acid (DNA), proteins, and drugs into cells, but the adsorption of RNAs to these materials has been little explored. In this study, the binding of small RNAs with different lengths and levels of secondary structure to HT nanoparticles has been analyzed and compared to results obtained with small DNAs in concurrent experiments. Initial experiments established the spectrophotometric properties of HT in aqueous solutions and determined that HT particles could be readily sedimented with near 100% efficiencies. Use of RNA+HT cosedimentation experiments as well as electrophoretic mobility shift assays demonstrated strong adsorption of RNA 25mers to HT, with twofold greater binding of single-stranded RNAs relative to double-stranded molecules. Strong affinities were also observed with ssRNA and dsRNA 54mers and with more complex transfer RNA molecules. Competition binding and RNA displacement experiments indicated that RNA-HT associations were strong and were only modestly affected by the presence of high concentrations of inorganic anions
High-throughput comparison, functional annotation, and metabolic modeling of plant genomes using the PlantSEED resource
The increasing number of sequenced plant genomes is placing new demands on the methods applied to analyze, annotate, and model these genomes. Today's annotation pipelines result in inconsistent gene assignments that complicate comparative analyses and prevent efficient construction of metabolic models. To overcome these problems, we have developed the PlantSEED, an integrated, metabolism-centric database to support subsystems-based annotation and metabolic model reconstruction for plant genomes. PlantSEED combines SEED subsystems technology, first developed for microbial genomes, with refined protein families and biochemical data to assign fully consistent functional annotations to orthologous genes, particularly those encoding primary metabolic pathways. Seamless integration with its parent, the prokaryotic SEED database, makes PlantSEED a unique environment for cross-kingdom comparative analysis of plant and bacterial genomes. The consistent annotations imposed by PlantSEED permit rapid reconstruction and modeling of primary metabolism for all plant genomes in the database. This feature opens the unique possibility of model-based assessment of the completeness and accuracy of gene annotation and thus allows computational identification of genes and pathways that are restricted to certain genomes or need better curation. We demonstrate the PlantSEED system by producing consistent annotations for 10 reference genomes. We also produce a functioning metabolic model for each genome, gapfilling to identify missing annotations and proposing gene candidates for missing annotations. Models are built around an extended biomass composition representing the most comprehensive published to date. To our knowledge, our models are the first to be published for seven of the genomes analyzed
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