8,488 research outputs found
High fidelity sorting of remarkably similar components via metal-mediated assembly.
Subtle differences in ligand coordination angle and rigidity lead to high fidelity sorting between individual components displaying identical coordination motifs upon metal-mediated self-assembly. Narcissistic self-sorting can be achieved between highly similar ligands that vary minimally in rigidity and internal coordination angle upon combination with Fe(ii) ions and 2-formylpyridine. Selective, sequential cage formation can be precisely controlled in a single flask from a mix of three different core ligands (and 33 total components) differing only in the hybridization of one group that is uninvolved in the metal coordination process
Long Memory and FIGARCH Models for Daily and High Frequency Commodity Prices
Daily futures returns on six important commodities are found to be well described as FIGARCH fractionally integrated volatility processes, with small departures from the martingale in mean property. The paper also analyzes several years of high frequency intra day commodity futures returns and finds very similar long memory in volatility features at this higher frequency level. Semi parametric Local Whittle estimation of the long memory parameter supports the conclusions. Estimating the long memory parameter across many different data sampling frequencies provides consistent estimates of the long memory parameter, suggesting that the series are self-similar. The results have important implications for future empirical work using commodity price and returns data.Commodity returns, Futures markets, Long memory, FIGARCH
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Arcadia, a software development environment research project
The research objectives of the Arcadia project are two-fold: discovery and development of environment architecture principles and creation of novel software development tools, particularly powerful analysis tools, which will function within an environment built upon these architectural principles.Work in the architecture area is concerned with providing the framework to support integration while also supporting the often conflicting goal of extensibility. Thus, this area of research is directed toward achieving external integration by providing a consistent, uniform user interface, while still admitting customization and addition of new tools and interface functions. In an effort to also attain internal integration, research is aimed at developing mechanisms for structuring and managing the tools and data objects that populate a software development environment, while facilitating the insertion of new kinds of tools and new classes of objects.The unifying theme of work in the tools area is support for effective analysis at every stage of a software development project. Research is directed toward tools suitable for analyzing pre-implementation descriptions of software, software itself, and towards the production of testing and debugging tools. In many cases, these tools are specifically tailored for applicability to concurrent, distributed, or real-time software systems.The initial focus of Arcadia research is on creating a prototype environment, embodying the architectural principles, which supports Ada1 software development. This prototype environment is itself being developed in Ada.Arcadia is being developed by a consortium of researchers from the University of California at Irvine, the University of Colorado at Boulder, the University of Massachusetts at Amherst, TRW, Incremental Systems Corporation, and The Aerospace Corporation. This paper delineates the research objectives and describes the approaches being taken, the organization of the research endeavor, and current status of the work
Substrate-Integrated Folded Waveguide Slot Antenna
In recent years a number of researchers have proposed novel techniques for fabricating rectangular waveguide using
microwave integrated circuit techniques. These so-called substrate integrated guides have been fabricated using
multilayer LTCC, multi- and single-layer microwave laminates and photoimageable thick films. All of
these structures result in dielectric filled rectangular waveguide and as such have a width reduction of 1/square root of the relative permittivity over conventional waveguide. Furthermore, by their very nature they are easily integrated with planar transmission lines and circuits, allowing hybrid waveguide/microstrip systems to be fabricated on a single substrate. Several researchers have investigated slot antennas and arrays in substrate-integrated guide. In this paper we show a slot antenna in a folded substrate-integrated waveguide. These waveguides have half the width of the other types of substrate-integrated waveguide. As such the present structure allows arrays of slot antennas to be more highly integrated
Web Based Interactive Software In International Business: The Case Of The Global Market Potential System Online (GMPSO)
This paper seeks to confirm whether students using the Global Market Potential System Online (GMPSO) web based software, (http://globalmarketpotential.com), for their class project enhanced their knowledge and understanding of international business. The challenge most business instructors and practitioners face is to determine how to bring the real world of business into a classroom or training environment. Experts claim that the answer lies in the Project-Based Learning (PBL) method and web based interactive software widely used at universities and businesses around the world. The findings indicate that the GMPSO enhanced the studentsâ understanding of international business and improved their team working, research and critical thinking skills
Cutter Assembly for Microscope and Related Method
A low-profile cutter assembly for use on a microscope and related cutting method are provided. The cutter assembly includes a support subassembly having a mounting ring for receiving and engaging the objective of a microscope. A cutter subassembly carried by the support subassembly is displaceable between a home and a forward position in response to actuation. Upon reaching the forward position, additional actuation causes the front end of the cutter subassembly to pivot toward the stage, thereby placing a cutter adjacent to or in contact with the specimen. By selectively actuating the cutter subassembly, multiple cuts may be performed, as necessary or desired for cutting a spore or isolating a particular specimen
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Dual and opposing roles of primary cilia in medulloblastoma development.
Recent work has shown that primary cilia are essential for Hedgehog (Hh) signaling during mammalian development. It is also known that aberrant Hh signaling can lead to cancer, but the role of primary cilia in oncogenesis is not known. Cerebellar granule neuron precursors (GNPs) can give rise to medulloblastomas, the most common malignant brain tumor in children. The primary cilium and Hh signaling are required for GNP proliferation. We asked whether primary cilia in GNPs have a role in medulloblastoma growth in mice. Genetic ablation of primary cilia blocked medulloblastoma formation when this tumor was driven by a constitutively active Smoothened protein (Smo), an upstream activator of Hh signaling. In contrast, removal of cilia was required for medulloblastoma growth by a constitutively active glioma-associated oncogene family zinc finger-2 (GLI2), a downstream transcription factor. Thus, primary cilia are either required for or inhibit medulloblastoma formation, depending on the initiating oncogenic event. Remarkably, the presence or absence of cilia was associated with specific variants of human medulloblastomas; primary cilia were found in medulloblastomas with activation in HH or WNT signaling but not in most medulloblastomas in other distinct molecular subgroups. Primary cilia could serve as a diagnostic tool and provide new insights into the mechanism of tumorigenesis
Application of a barotropic model to North Atlantic synoptic sea level variability
A barotropic, shallow-water model of the North Atlantic is used to investigate variability in adjusted sea level on time scales of a few days to a few months (by âadjusted,â we mean that the inverse barometer is removed from both the model-computed sea level and the observations). The model has 1/3° Ă 0.4° resolution in latitude and longitude, respectively, and is forced using atmospheric pressure and wind stress data derived from European Centre for Medium Range Weather Forecasts (ECMWF, 1994) analyses. The model results are compared with coastal tide gauge data. Along the western boundary, from St. John\u27s, Newfoundland, to Fernandina Beach, Florida, coherence squared between model and data is greater than 0.5 in the period range 3 to 10 days. South of Cape Hatteras, the model underestimates the amplitude seen in the data, with much better agreement north of the Cape. Model performance on the eastern boundary is generally poor. We suggest this is because on the eastern boundary, the shelf width is much narrower, compared to the internal radius of deformation, than on the western boundary. In addition, the model resolution is insufficient to adequately represent the shelf on the eastern boundary. The poorer agreement south of Cape Hatteras may be due Gulf Stream effects not accounted for by the model dynamics. Finally, we discuss the model-computed variability in the ocean interior
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