Real-Time Classification of Twitter Trends

Social media users give rise to social trends as they share about common interests, which can be triggered by different reasons. In this work, we explore the types of triggers that spark trends on Twitter, introducing a typology with following four types: 'news', 'ongoing events', 'memes', and 'commemoratives'. While previous research has analyzed trending topics in a long term, we look at the earliest tweets that produce a trend, with the aim of categorizing trends early on. This would allow to provide a filtered subset of trends to end users. We analyze and experiment with a set of straightforward language-independent features based on the social spread of trends to categorize them into the introduced typology. Our method provides an efficient way to accurately categorize trending topics without need of external data, enabling news organizations to discover breaking news in real-time, or to quickly identify viral memes that might enrich marketing decisions, among others. The analysis of social features also reveals patterns associated with each type of trend, such as tweets about ongoing events being shorter as many were likely sent from mobile devices, or memes having more retweets originating from a few trend-setters.Comment: Pre-print of article accepted for publication in Journal of the American Society for Information Science and Technology copyright @ 2013 (American Society for Information Science and Technology

Chemical etching and organometallic chemical vapor deposition on varied geometries of GaAs

Results of micron-spaced geometries produced by wet chemical etching and subsequent OMCVD growth on various GaAs surfaces are presented. The polar lattice increases the complexity of the process. The slow-etch planes defined by anisotropic etching are not always the same as the growth facets produced during MOCVD deposition, especially for deposition on higher-order planes produced by the hex groove etching

Tailoring Nanostructures Using Copolymer Nanoimprint Lithography

Finding affordable ways of generating high-density ordered nanostructures that can be transferred to a substrate is a major challenge for industrial applications like memories or optical devices with high resolution features. In this work, we report on a novel technique to direct self-assembled structures of block copolymers by NanoImprint Lithography. Surface energy of a reusable mold and nanorheology are used to organize the copolymers in defect-free structures over tens of micrometers in size. Versatile and controlled in-plane orientations of about 25 nm half-period lamellar nanostructures are achieved and, in particular, include applications to circular tracks of magnetic reading heads.Comment: 12 pages, 4 figures; Advanced Materials 201

NASA Innovative Advanced Concepts (NIAC) Phase 1 Final Report: Venus Landsailer Zephyr

Imagine sailing across the hot plains of Venus! A design for a craft to do just this was completed by the COncurrent Multidisciplinary Preliminary Assessment of Space Systems (COMPASS) Team for the NASA Innovative Advanced Concepts (NIAC) project. The robotic craft could explore over 30 km of surface of Venus, driven by the power of the wind

Zephyr: A Landsailing Rover for Venus

With an average temperature of 450C and a corrosive atmosphere at a pressure of 90 bars, the surface of Venus is the most hostile environment of any planetary surface in the solar system. Exploring the surface of Venus would be an exciting goal, since Venus is a planet with significant scientific mysteries, and interesting geology and geophysics. Technology to operate at the environmental conditions of Venus is under development. A rover on the surface of Venus with capability comparable to the rovers that have been sent to Mars would push the limits of technology in high-temperature electronics, robotics, and robust systems. Such a rover would require the ability to traverse the landscape on extremely low power levels. We have analyzed an innovative concept for a planetary rover: a sail-propelled rover to explore the surface of Venus. Such a rover can be implemented with only two moving parts; the sail, and the steering. Although the surface wind speeds are low (under 1 m/s), at Venus atmospheric density even low wind speeds develop significant force. Under funding by the NASA Innovative Advanced Concepts office, a conceptual design for such a rover has been done. Total landed mass of the system is 265 kg, somewhat less than that of the MER rovers, with a 12 square meter rigid sail. The rover folds into a 3.6 meter aeroshell for entry into the Venus atmosphere and subsequent parachute landing on the surface. Conceptual designs for a set of hightemperature scientific instruments and a UHF communication system were done. The mission design lifetime is 50 days, allowing operation during the sunlit portion of one Venus day. Although some technology development is needed to bring the high-temperature electronics to operational readiness, the study showed that such a mobility approach is feasible, and no major difficulties are seen

High-temperature Solar Cell Development

The vast majority of space probes to date have relied upon photovoltaic power generation. If future missions designed to probe environments close to the sun (Figure 1) will be able to use such power generation, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. The significant problem is that solar cells lose performance at high temperatures

UAS Literary & Arts Journal

Proof copy provided by Tidal Echoes.Featuring the work of students, faculty, and staff of the University of Alaska Southeast and members of the community.A Note from Loren, Sometimes Known as Senior Editor -- A Letter from Josh, Affectionately Known as “Sugah” (say it with a southern accent) -- A Note from Emily Wall -- On the Move -- Dangly Jangly Things -- Taco Surf -- Midwestern Trash -- On the Distaff Side -- Christmas Joy -- The Three Little McCormicks -- Trollin’ Ray’s Brain: An Interview with Ray Troll -- His Long Coat Turning -- First Autumn -- Pinta Cove Birthday Gifts -- September Wings -- When in Rome -- Early Morning Conspiracy Theory -- Flesh Wound -- Two Ravens, Five Ways -- Shades of Brown: The Question -- Hayfield-Clarke Psychiatric Center -- Hardscrabble -- Smoked Meat Sandwiches -- Slime Squishing Through Gold: An Interview with Nora Marks Dauenhauer -- Berries -- Buds -- Grandpa Jakwteen in Eclipse -- Cross Talk -- Voices -- Trouble -- Flying Home -- Snorkeling at Hanauma Bay -- Genocide -- Raven, Saving It for Later -- Mama Abel’s -- Settling In -- Blue -- Dad at 27 -- Dad photographs mother -- Backyard theatre & Oz -- Love-in, Easter Day, 1968 -- Topanga Corral -- Swallowing Senora -- Keeping Time on the Kee Nax Trail -- Ode to Ching -- Beneath the Surface (chapter title) -- A Visit from the Wild -- Teacher’s Pets -- Centennial -- See Spot Rot -- With Salsa -- Moonbaby -- The Fine Art of Raising a Tarpaulin -- Prologue -- Epiphany 2008 -- View of Auke Lake -- Shark Fins -- Translating Pasternak -- Raven Boys -- Institutional Back Door -- Uneasy Disguise -- Christmas Wind -- The Life and Times of the Orlando Bloom Fan Club -- Writer & Artist Biographie

CHD associated with syndromic diagnoses: peri-operative risk factors and early outcomes

CHD is frequently associated with a genetic syndrome. These syndromes often present specific cardiovascular and non-cardiovascular co-morbidities that confer significant peri-operative risks affecting multiple organ systems. Although surgical outcomes have improved over time, these co-morbidities continue to contribute substantially to poor peri-operative mortality and morbidity outcomes. Peri-operative morbidity may have long-standing ramifications on neurodevelopment and overall health. Recognising the cardiovascular and non-cardiovascular risks associated with specific syndromic diagnoses will facilitate expectant management, early detection of clinical problems, and improved outcomes--for example, the development of syndrome-based protocols for peri-operative evaluation and prophylactic actions may improve outcomes for the more frequently encountered syndromes such as 22q11 deletion syndrome

Arctic Tundra Vegetation Functional Types Based on Photosynthetic Physiology and Optical Properties

Climate change in tundra regions may alter vegetation species composition and ecosystem carbon balance. Remote sensing provides critical tools for monitoring these changes as optical signals provide a way to scale from plot measurements to regional patterns. Gas exchange measurements of pure patches of key vegetation functional types (lichens, mosses, and vascular plants) in sedge tundra at Barrow AK, show three significantly different values of light use efficiency (LUE) with values of 0.013+/-0.001, 0.0018+/-0.0002, and 0.0012 0.0001 mol C/mol absorbed quanta for vascular plants, mosses and lichens, respectively. Further, discriminant analysis of patch reflectance identifies five spectral bands that can separate each vegetation functional type as well as nongreen material (bare soil, standing water, and dead leaves). These results were tested along a 100 m transect where midsummer spectral reflectance and vegetation coverage were measured at one meter intervals. Area-averaged canopy LUE estimated from coverage fractions of the three functional types varied widely, even over short distances. Patch-level statistical discriminant functions applied to in situ hyperspectral reflectance successfully unmixed cover fractions of the vegetation functional types. These functions, developed from the tram data, were applied to 30 m spatial resolution Earth Observing-1 Hyperion imaging spectrometer data to examine regional variability in distribution of the vegetation functional types and from those distributions, the variability of LUE. Across the landscape, there was a fivefold variation in tundra LUE that was correlated to a spectral vegetation index developed to detect vegetation chlorophyll content

Extended Temperature Solar Cell Technology Development

Future NASA missions will require solar cells to operate both in regimes closer to the sun, and farther from the sun, where the operating temperatures will be higher and lower than standard operational conditions. NASA Glenn is engaged in testing solar cells under extended temperature ranges, developing theoretical models of cell operation as a function of temperature, and in developing technology for improving the performance of solar cells for both high and low temperature operation