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Search Results: 1 - 10 of 206147 matches for " Andrew D. Tomasch "
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Cosmic-Ray Positrons: Are There Primary Sources?
Stephane Coutu,Steven W. Barwick,James J. Beatty,Amit Bhattacharyya,Chuck R. Bower,Christopher J. Chaput,Georgia A. de Nolfo,Michael A. DuVernois,Allan Labrador,Shawn P. McKee,Dietrich Muller,James A. Musser,Scott L. Nutter,Eric Schneider,Simon P. Swordy,Gregory Tarle,Andrew D. Tomasch,Eric Torbet
Physics , 1999, DOI: 10.1016/S0927-6505(99)00011-0
Abstract: Cosmic rays at the Earth include a secondary component originating in collisions of primary particles with the diffuse interstellar gas. The secondary cosmic rays are relatively rare but carry important information on the Galactic propagation of the primary particles. The secondary component includes a small fraction of antimatter particles, positrons and antiprotons. In addition, positrons and antiprotons may also come from unusual sources and possibly provide insight into new physics. For instance, the annihilation of heavy supersymmetric dark matter particles within the Galactic halo could lead to positrons or antiprotons with distinctive energy signatures. With the High-Energy Antimatter Telescope (HEAT) balloon-borne instrument, we have measured the abundances of positrons and electrons at energies between 1 and 50 GeV. The data suggest that indeed a small additional antimatter component may be present that cannot be explained by a purely secondary production mechanism. Here we describe the signature of the effect and discuss its possible origin.
Novel Chalcone-Based Fluorescent Human Histamine H3 Receptor Ligands as Pharmacological Tools
Miriam Tomasch,Holger Stark
Frontiers in Systems Neuroscience , 2012, DOI: 10.3389/fnsys.2012.00014
Abstract: Novel fluorescent chalcone-based ligands at human histamine H3 receptors (hH3R) have been designed, synthesized, and characterized. Compounds described are non-imidazole analogs of ciproxifan with a tetralone motif. Tetralones as chemical precursors and related fluorescent chalcones exhibit affinities at hH3R in the same concentration range like the reference antagonist ciproxifan (hH3R pKi value of 7.2). Fluorescence characterization of our novel ligands shows emission maxima about 570 nm for yellow fluorescent chalcones and ≥600 nm for the red fluorescent derivatives. Interferences to cellular autofluorescence could be excluded. All synthesized chalcone compounds could be used to visualize hH3R proteins in stably transfected HEK-293 cells using confocal laser scanning fluorescence microscopy. These novel fluorescent ligands possess high potential to be used as pharmacological tools for hH3R visualization in different tissues.
Metabolic fluxes in the central carbon metabolism of Dinoroseobacter shibae and Phaeobacter gallaeciensis, two members of the marine Roseobacter clade
Tobias Fürch, Matthias Preusse, Jürgen Tomasch, Hajo Zech, Irene Wagner-D?bler, Ralf Rabus, Christoph Wittmann
BMC Microbiology , 2009, DOI: 10.1186/1471-2180-9-209
Abstract: Using 13C labelling techniques in specifically designed experiments, it could be shown that glucose-grown cells of D. shibae catabolise the carbon source exclusively via the Entner-Doudoroff pathway, whereas alternative routes of glycolysis and the pentose phosphate pathway are obviously utilised for anabolic purposes only. Enzyme assays confirmed this flux pattern and link the lack of glycolytic flux to the absence of phosphofructokinase activity. The previously suggested formation of phosphoenolpyruvate from pyruvate during mixotrophic CO2 assimilation was found to be inactive under the conditions studied. Moreover, it could be shown that pyruvate carboxylase is involved in CO2 assimilation and that the cyclic respiratory mode of the TCA cycle is utilised. Interestingly, the use of intracellular pathways was highly similar for P. gallaeciensis.The present study reveals the first insight into pathway utilisation within the Roseobacter group. Fluxes through major intracellular pathways of the central carbon metabolism, which are closely linked to the various important traits found for the Roseobacter clade, could be determined. The close similarity of fluxes between the two physiologically rather different species might provide the first indication of more general key properties among members of the Roseobacter clade which may explain their enormous success in the marine realm.The Roseobacter lineage, representing a group of Alphaproteobacteria [1], is found in various marine habitats where it is present in high abundance, comprising up to 25% of the total bacterial community [2]. Overall, the diverse metabolic properties of the Roseobacter clade and its ubiquitous occurrence in marine ecosystems suggest that members of this clade play an important role in global biogeochemical processes such as cycling of carbon or sulphur [3]. Members of the Roseobacter clade participate in DMSP demethylation [4], the oxidation of carbon monoxide [5] and degradation of aromatic co
Taking the Guesswork Out of Curriculum Design: Learning to Engineer Explicit Grammar Curricula through the Analysis of Multiple Influences on the Acquisition Process  [PDF]
Andrew D. Schenck, Wonkyung Choi
Open Journal of Modern Linguistics (OJML) , 2012, DOI: 10.4236/ojml.2012.23015
Abstract: While a study by Goldschneider and DeKeyser (2005) was able to explain how factors such as phonological salience, frequency, morphological regularity, semantic complexity, and syntactic complexity influence acquisition order, the examination of six similar morphological features provided only a limited perspective. The purpose of this study was to see if causal variables, both individually and cumulatively, could be used to predict acquisition orders with more highly disparate morphological and syntactic features. Results of Spearman rank calculations revealed that the integration of causal factors yielded the highest correlation to both the Processability Theory (rs = 0.821; p = 0.007) and Natural Order Hypothesis (rs = 0.529; p = 0.143), suggesting that these factors have a synergistic influence on morphosyntactic development. Methods to predict the acquisition of both syntactic and morphological features are suggested, along with an empirically-based method to guide explicit grammar instruction.
Building a Better Mousetrap: Replacing Subjective Writing Rubrics with More Empirically-Sound Alternatives for EFL Learners  [PDF]
Andrew D. Schenck, Eoin Daly
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.38193
Abstract: Although writing rubrics can provide valuable feedback, the criteria they use are often subjective, which compels raters to employ their own tacit biases. The purpose of this study is to see if discreet empirical characteristics of texts can be used in lieu of the rubric to objectively assess the writing quality of EFL learners. The academic paragraphs of 38 participants were evaluated according to several empirically calculable criteria related to cohesion, content, and grammar. Values were then compared to scores obtained from holistic scoring by multiple raters using a multiple regression formula. The resulting correlation between variables (R = .873) was highly significant, suggesting that more empirical, impartial means of writing evaluation can now be used in conjunction with technology to provide student feedback and teacher training.
Unlocking the Secrets of Morphosyntactic Development by Examining Acquisition Order Disparities in an EFL Context  [PDF]
Andrew D. Schenck, Wonkyung Choi
Open Journal of Modern Linguistics (OJML) , 2013, DOI: 10.4236/ojml.2013.31006

This study examined acquisition order disparities and their associated causes in an EFL context, so that pedagogical means of enhancing the process of morphosyntactic development could be discovered. Twenty-six South Korean EFL middle school students were given an extensive timed writing test. Following the administration of this test, an acquisition order for 16 morphosyntactic features was constructed. The EFL order was first compared to others found in ESL contexts. It was then compared to six hypothesized causes of acquisition: EFL input frequency, L1 similarity, morphosyntactic variability, semantic complexity, sonority, and morphosyntactic complexity. Results suggest that while input frequency and L1 similarity are the most significant predictors, all causal variables have a role in the manifestation of acquisition order within an EFL context. Suggestions for curricular reform that utilize the unique causal characteristics of each morphosyntactic feature have been proposed.

An Innovative Approach in Balancing Real Power Using Plug in Hybrid Electric Vehicles  [PDF]
Andrew D. Clarke, Elham B. Makram
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.210001

Many distribution systems operate under unbalanced loading conditions due to the connection of single phase loads to a three phase system. As PHEVs become more prevalent, it is expected that this unbalance will be further exacerbated due to the power draws from single phase chargers. Unbalanced loads reduce the overall system operating efficiency and power transfer capability of assets. In this paper, a new method of mitigating real power unbalance is suggested. It works by selecting which of the three phases that each single phase PHEV charger in a car park should be connected to. The algorithm is then tested on a simulation model of a real world distribution system. Using the balancing algorithm, balancing of the real power flowing through the feeder to the car park is accomplished.

A Novel Idea for Self-Balancing Car Parks for Plug in Electric Vehicle Charging  [PDF]
Andrew D. Clarke, Elham B. Makram
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.210005

Many existing studies seek to examine and mitigate possible impacts which plug in vehicle (PEV) charging will have on electric utilities. As PEVs increase in popularity, car parks will have to be built in order to allow for charging while away from home. Existing studies fail to consider the unbalance conditions in the distribution feeders to car parks during PEV charging. This paper presents an innovative idea to improve the unbalance conditions caused by a car park by reconfiguring PEV charger connections to a three-phase system. Although the developed algorithm is simple, results show its ability to balance the power among the phases. A car park is used as an example to show that balancing of the real power drawn by PEV chargers in a parking structure is a success.

A Comprehensive Analysis of Plug in Hybrid Electric Vehicles to Commercial Campus (V2C)  [PDF]
Andrew D. Clarke, Elham B. Makram
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.31003
Abstract: Vehicle to grid is an emerging technology that utilizes plug in hybrid electric vehicle batteries to benefit electric utilities during times when the vehicle is parked and connected to the electric grid. In its current form however, vehicle to grid implementation poses many challenges that may not be easily overcome and many existing studies neglect critical aspects such as battery cost or driving profiles. The goal of this research is to ease some of these challenges by examining a vehicle to grid scenario on a university campus, as an example of a commercial campus, based on time of use electricity rates. An analysis of this scenario is conducted on a vehicle battery as well as a stationary battery for comparison. It is found that vehicle to campus and a stationary battery both have the potential to prove economical based on battery cost and electricity rates.
Measurement of the Cosmic-Ray Antiproton to Proton Abundance Ratio between 4 and 50 GeV
A. S. Beach,J. J. Beatty,A. Bhattacharyya,C. Bower,S. Coutu,M. A. DuVernois,A. W. Labrador,S. McKee,S. A. Minnick,D. Muller,J. Musser,S. Nutter,M. Schubnell,S. Swordy,G. Tarle,A. Tomasch
Physics , 2001, DOI: 10.1103/PhysRevLett.87.271101
Abstract: We present a new measurement of the antiproton to proton abundance ratio, pbar/p, in the cosmic radiation. The HEAT-pbar instrument, a balloon borne magnet spectrometer with precise rigidity and multiple energy loss measurement capability, was flown successfully in Spring 2000, at an average atmospheric depth of 7.2 g/cm^2. A total of 71 antiprotons were identified above the vertical geomagnetic cut-off rigidity of 4.2 GV. The highest measured proton energy was 81 GeV. We find that the pbar/p abundance ratio agrees with that expected from a purely secondary origin of antiprotons produced by primary protons with a standard soft energy spectrum.
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