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

Use of Treated Municipal Wastewater as Power Plant Cooling System Makeup Water: Tertiary Treatment versus Expanded Chemical Regimen for Recirculating Water Quality Management

Treated municipal wastewater is a common, widely available alternative source of cooling water for thermoelectric power plants across the U.S. However, the biodegradable organic matter, ammonia-nitrogen, carbonate and phosphates in the treated wastewater pose challenges with respect to enhanced biofouling, corrosion, and scaling, respectively. The overall objective of this study was to evaluate the benefits and life cycle costs of implementing tertiary treatment of secondary treated municipal wastewater prior to use in recirculating cooling systems. The study comprised bench- and pilot-scale experimental studies with three different tertiary treated municipal wastewaters, and life cycle costing and environmental analyses of various tertiary treatment schemes. Sustainability factors and metrics for reuse of treated wastewater in power plant cooling systems were also evaluated. The three tertiary treated wastewaters studied were: secondary treated municipal wastewater subjected to acid addition for pH control (MWW_pH); secondary treated municipal wastewater subjected to nitrification and sand filtration (MWW_NF); and secondary treated municipal wastewater subjected nitrification, sand filtration, and GAC adsorption (MWW_NFG). Tertiary treatment was determined to be essential to achieve appropriate corrosion, scaling, and biofouling control for use of secondary treated municipal wastewater in power plant cooling systems. The ability to control scaling, in particular, was found to be significantly enhanced with tertiary treated wastewater compared to secondary treated wastewater. MWW_pH treated water (adjustment to pH 7.8) was effective in reducing scale formation, but increased corrosion and the amount of biocide required to achieve appropriate biofouling control. Corrosion could be adequately controlled with tolytriazole addition (4-5 ppm TTA), however, which was the case for all of the tertiary treated waters. For MWW_NF treated water, the removal of ammonia by nitrification helped to reduce the corrosivity and biocide demand. Also, the lower pH and alkalinity resulting from nitrification reduced the scaling to an acceptable level, without the addition of anti-scalant chemicals. Additional GAC adsorption treatment, MWW_NFG, yielded no net benefit. Removal of organic matter resulted in pitting corrosion in copper and cupronickel alloys. Negligible improvement was observed in scaling control and biofouling control. For all of the tertiary treatments, biofouling control was achievable, and most effectively with pre-formed monochloramine (2-3 ppm) in comparison with NaOCl and ClO2. Life cycle cost (LCC) analyses were performed for the tertiary treatment systems studied experimentally and for several other treatment options. A public domain conceptual costing tool (LC3 model) was developed for this purpose. MWW_SF (lime softening and sand filtration) and MWW_NF were the most cost-effective treatment options among the tertiary treatment alternatives considered because of the higher effluent quality with moderate infrastructure costs and the relatively low doses of conditioning chemicals required. Life cycle inventory (LCI) analysis along with integration of external costs of emissions with direct costs was performed to evaluate relative emissions to the environment and external costs associated with construction and operation of tertiary treatment alternatives. Integrated LCI and LCC analysis indicated that three-tiered treatment alternatives such as MWW_NSF and MWW_NFG, with regular chemical addition for treatment and conditioning and/or regeneration, tend to increase the impact costs and in turn the overall costs of tertiary treatment. River water supply and MWW_F alternatives with a single step of tertiary treatment were associated with lower impact costs, but the contribution of impact costs to overall annual costs was higher than all other treatment alternatives. MWW_NF and MWW_SF alternatives exhibited moderate external impact costs with moderate infrastructure and chemical conditioner dosing, which makes them (especially MWW_NF) better treatment alternatives from the environmental sustainability perspective since they exhibited minimal contribution to environmental damage from emissions

Adrenoleukodystrophy (ALD)

First reported case in 1910, ALD results in serious cognitive and developmental issues. Adult form reported in 1976. Gene of cause identified in 1993 by Mosser et al. X-linked, mutation on ABCD1 gene codes for VLCFA transporter. More likely to occur in males. To be diagnosed with ALD, persons must show signs and symptoms of motor neuron degeneration in both the upper and lower motor neurons that cannot be explained by other factors. There is no single test that can definitively diagnose ALD; instead, the diagnosis is dependent on the symptoms and signs that the physician observes in the patient. A hematopoietic stem cell transplantation at the early stages of the cerebral symptoms. (Class Project