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2013

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Articles 8251 - 8280 of 11462

Full-Text Articles in Physical Sciences and Mathematics

Sequence-Specific Inhibition Of A Nonspecific Protease, Leigh A. Logsdon, Adam R. Urbach Jan 2013

Sequence-Specific Inhibition Of A Nonspecific Protease, Leigh A. Logsdon, Adam R. Urbach

Chemistry Faculty Research

A nonspecific exopeptidase, aminopeptidase N (APN), is inhibited sequence-specifically by a synthetic host, cucurbit[7]uril (Q7), which binds with high affinity and specificity to N-terminal phenylalanine (Phe) and 4-(aminomethyl)phenylalanine (AMPhe) and prevents their removal from the peptide. Liquid chromatography experiments demonstrated that in the presence of excess Q7, APN quantitatively converts the pentapeptides Thr-Gly-Ala-X-Met into the dipeptides X-Met (X = Phe, AMPhe). The resulting Q7-bound products are completely stable to proteolytic digestion for at least 24 h. Structure–activity studies revealed a direct correlation between the extent of protection of an N-terminal amino acid and its affinity for Q7. Therefore, Q7 provides …

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Broadly Applicable Methodology For The Rapid And Dosable Small Molecule-Mediated Regulation Of Transcription Factors In Human Cells, M. D. Shoulders, L. M. Ryno, Christina B. Cooley, J. W. Kelly, R. L. Wiseman Jan 2013

Broadly Applicable Methodology For The Rapid And Dosable Small Molecule-Mediated Regulation Of Transcription Factors In Human Cells, M. D. Shoulders, L. M. Ryno, Christina B. Cooley, J. W. Kelly, R. L. Wiseman

Chemistry Faculty Research

Direct and selective small molecule control of transcription factor activity is an appealing avenue for elucidating the cell biology mediated by transcriptional programs. However, pharmacologic tools to modulate transcription factor activity are scarce because transcription factors are not readily amenable to small molecule-mediated regulation. Moreover, existing genetic approaches to regulate transcription factors often lead to high nonphysiologic levels of transcriptional activation that significantly impair our ability to understand the functional implications of transcription factor activity. Herein, we demonstrate that small molecule-mediated conformational control of protein degradation is a generally applicable, chemical biological methodology to obtain small molecule-regulated transcription factors that …

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Cultivating Intelligent Tutoring Cognizing Agents In Ill-Defined Domains Using Hybrid Approaches, Rania Hodhod Jan 2013

Cultivating Intelligent Tutoring Cognizing Agents In Ill-Defined Domains Using Hybrid Approaches, Rania Hodhod

Faculty Bibliography

Cognizing agents are those systems that can perceive information from the external environment and can adapt to the changing conditions of that environment. Along the adaptation process a cognizing agent perceives information about the environment and generates reactions. An intelligent tutoring cognizing agent should deal not only with the tutoring system’s world but also with the learner-it should infer and predict new information about the learner and tailor the learning process to fit this specific learner. This paper shows how intelligent tutoring cognizing agents can be cultivated in ill-defined domains using hybrid techniques instantiated in the two example agents AEINS-CA …

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Ehrhart's Polynomial For Equilateral Triangles In Z3, Eugen J. Ionascu Jan 2013

Ehrhart's Polynomial For Equilateral Triangles In Z3, Eugen J. Ionascu

Faculty Bibliography

In this paper we calculate the Ehrhart’s polynomial associated with a 2-dimensional regular polytope (i.e. equilateral triangles) in Z3. The polynomial takes a relatively simple form in terms of the coordinates of the vertices of the triangle. We give some equivalent formula in terms of a parametrization of these objects which allows one to construct equilateral triangles with given properties. In particular, we show that given a prime number p which is equal to 1 or −5 (mod 8), there exists an equilateral triangle with integer coordinates whose Ehrhart polynomial is L(t) = (pt + 2)(t + 1)/2, t ∈ …

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Application Of Social Network Metrics To A Trust-Aware Collaborative Model For Generating Personalized User Recommendations, Iraklis Varlamis, Magdalini Eirinaki, Malamati Louta Jan 2013

Application Of Social Network Metrics To A Trust-Aware Collaborative Model For Generating Personalized User Recommendations, Iraklis Varlamis, Magdalini Eirinaki, Malamati Louta

Faculty Publications

Social network analysis has emerged as a key technique in modern sociology, but has recently gained a lot of interest in Web mining research, because of the advent and the increasing popularity of social media, such as blogs, social networks, micro-blogging, customer review sites etc. Such media often serve as platforms for information dissemination and product placement or promotion. One way to improve the quality of recommendations provided to the members of social networks is to use trustworthy resources. In this environment, community-based reputation can help estimating the trustworthiness of individual users. Consequently, influence and trust are becoming essential qualities …

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Predicting Anthropogenic Streambed Shifts In Beckley, West Virginia, Modeled Over 15 Years Using Landsat Tm And Dems, Andrew D. Reinhardt Jan 2013

Predicting Anthropogenic Streambed Shifts In Beckley, West Virginia, Modeled Over 15 Years Using Landsat Tm And Dems, Andrew D. Reinhardt

Theses, Dissertations and Capstones

Anthropogenic change of streambeds in the Beckley, West Virginia watershed region was modeled using Landsat 5 TM satellite data from 1988 and 2003, and Digital Elevation Model (DEM) data for 1969 and 2005. Comparing the 15 year land cover changes and the 36 year elevation shifts, and using a modified Universal Soil Loss Equation (USLE), in ESRI ArcMap and ERDAS Imagine, a streambed shift model was created. The model predicted land cover and elevation changes for 2018, using inputs from geospatial differencing of 2003 and 1988 land cover as well as 2003 and 1969 DEM data. Further analysis using hydrodynamic …

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Toward A Comprehensive Model Of Photosystem Ii Oxygen Evolving Complex Photoassembly, James Scott Board Ii Jan 2013

Toward A Comprehensive Model Of Photosystem Ii Oxygen Evolving Complex Photoassembly, James Scott Board Ii

Theses, Dissertations and Capstones

Elucidating the mechanism of photoassembly of the oxygen-evolving complex (OEC) will lead to a better understanding of how nature catalyzes water oxidation. Although the temperature dependence of oxygen evolution has been described in the literature [1,2], we have performed a comprehensive study that covers Photosystem II (PSII) activity oxygen evolution in the presence and absence of 2,6-dichloro-1,4benzoquinone (DCBQ) from 5–45°C. In addition, we performed similar measurements for OEC photoassembly in the absence of DCBQ. PSIIenriched particles used for our measurements were prepared according to Berthold, Babcock, and Yocum[3], with modifications from Kolling, et al.[4] The oxygen-evolution of intact BBY particles …

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A Remote Sensing And Gis-Based Wetland Analysis In Canaan Valley, West Virginia, Yisha Shi Jan 2013

A Remote Sensing And Gis-Based Wetland Analysis In Canaan Valley, West Virginia, Yisha Shi

Theses, Dissertations and Capstones

With the increasing influence in climate change and human activity, more and more people have begun to recognize the benefits of wetlands. However, there was a continuous annual net loss in the wetlands area since 1980s. Many programs have been implemented to monitor the status and trend of wetlands recently. In West Virginia, the wetlands area is a small portion of the State’s land, but it plays a key role in the whole ecosystem. This research aimed to detect the land cover and vegetation changes focusing on Canaan Valley area, which represents the greatest wetlands area of West Virginia. Remote …

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Interaction Of Pyrimoidiazolium Ions With Calf Thymus Dna, Stormy Rene Gibson Jan 2013

Interaction Of Pyrimoidiazolium Ions With Calf Thymus Dna, Stormy Rene Gibson

Theses, Dissertations and Capstones

A new class of fluorescent dyes, pyridoimidiazolium cations, is being considered for their possible use in the biochemical field because of their interactions with DNA. Binding of low molecular weight fluorophores has been proven to cause a wide variety of biological responses in DNA. The dyes used here have been synthesized using α-diimine type compounds. The reaction used has the capability to produce many fluorescent cations. Binding constants of these compounds in acetonitrile with calf thymus DNA have been determined by measuring emission intensity. Emission intensity showed the degree to which binding is occurring. The experimental results show that binding …

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Transmission Rate In Partial Differential Equation In Epidemic Models, Alaa Elkadry Jan 2013

Transmission Rate In Partial Differential Equation In Epidemic Models, Alaa Elkadry

Theses, Dissertations and Capstones

The rate at which susceptible individuals become infected is called the transmission rate. It is important to know this rate in order to study the spread and the effect of an infectious disease in a population. This study aims at providing an understanding of estimating the transmission rate from mathematical models representing the population dynamics of an infectious diseases using two different methods. Throughout, it is assumed that the number of infected individuals is known. In the first chapter, it includes historical background for infectious diseases and epidemic models and some terminology needed to understand the problems. Specifically, the partial …

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Solutions Of Dynamic Equations On Time Scales With Jumps, Kayode Daniel Olumoyin Jan 2013

Solutions Of Dynamic Equations On Time Scales With Jumps, Kayode Daniel Olumoyin

Theses, Dissertations and Capstones

To obtain the solution of first order dynamic equations on time scales with jumps, a good question to ask is, how many initial conditions will be needed? We shall show that you only need the initial condition that gives you either the initial position or the initial velocity. The solution at each left scattered point in the time scale can be obtained analytically. With this approach we shall write the general form of the solution of a first order dynamic equations on time scales with jumps. To do this we shall use the Hilger derivative, anti-derivatives, the Hilger Complex plane, …

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Continuous Brightness Estimation (Cobe): Implementation And Its Possible Applications, G. Presti, Davide Andrea Mauro Jan 2013

Continuous Brightness Estimation (Cobe): Implementation And Its Possible Applications, G. Presti, Davide Andrea Mauro

Computer Sciences and Electrical Engineering Faculty Research

This paper presents a time-domain technique based solely on simple operations, like filtering and scaling, to continuously track a sound descriptor correlated to brightness and pitch. In opposition to existing algorithms this approach does not rely on input framing or frequencydomain transforms, ensuring a better temporal resolution and the possibility to model analog-like implementations. In the first part of the document we present the details of our approach to brightness estimation; then we will compare CoBE to the brightness estimation implemented in MIR Toolbox; we introduce and define the concept of “Equivalent Brightness Frequency” (EBF) and finally we show how …

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Further Evidence Of The Contribution Of The Ear Canal To Directional Hearing: Design Of A Compensating Filter, Andrea Martelloni, Davide Andrea Mauro Phd, Antonio Mancuso Jan 2013

Further Evidence Of The Contribution Of The Ear Canal To Directional Hearing: Design Of A Compensating Filter, Andrea Martelloni, Davide Andrea Mauro Phd, Antonio Mancuso

Computer Sciences and Electrical Engineering Faculty Research

It has been proven, and it is well documented in literature, that the directional response in HRTFs comes largely from the effect of the pinnae. However, few studies have analysed the contribution given by the remaining part of the external ear, particularly the ear canal. This work investigates the directionally dependent response of the modelled ear canal of a dummy head, assuming that the behaviour of the external ear is sufficiently linear to be approximated by an LTI system. In order to extract the ear canal's transfer function, two critical microphone placements (at the eardrum and at the beginning of …

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Osmb Ais Funds Final Report: Task 1 Boat Ramp Monitoring For New Zealand Mud Snails, Valance Brenneis, Samuel Cimino, Angela L. Strecker Jan 2013

Osmb Ais Funds Final Report: Task 1 Boat Ramp Monitoring For New Zealand Mud Snails, Valance Brenneis, Samuel Cimino, Angela L. Strecker

Center for Lakes and Reservoirs Publications and Presentations

The New Zealand mud snail (Potamopyrgus antipodarum; NZMS) is an invasive species found in a variety of ecosystems in Oregon, including brackish estuaries, heavily used recreational rivers, and highly trafficked coastal freshwater lakes. NZMS are an invasive species of concern because once established, they may out-compete native invertebrate grazers, such as native insect larvae that provide important food resources for fish, and NZMS themselves provide little nutritional value. Monitoring for the presence and population density of NZMS was performed at boat ramps located along several water bodies in 2006 – 2007. These water bodies were then re-sampled during the summer …

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Visualizing Chaos, Margaret Peterson Jan 2013

Visualizing Chaos, Margaret Peterson

Honors Theses, 1963-2015

Chaos is typically visualized on an infinite 2D plane. By using stereographic projection, my colleague Preston Hardy and I utilized a third dimension to plot basin maps of iterative root finding methods on a subset of the complex plane onto a sphere. These spheres are then shaded in accordance to the speed in which the particular initial point converges, creating images that can be used to visualize all basins of attraction on the complex plane on a finite 3D surface. The resulting images are used to explore efficiency of root finding methods as well as evaluating the choice of addition …

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Sources Of The Persistent Gender Wage Gap Along The Unconditional Earnings Distribution: Findings From Kenya, Richard U. Agesa, Jacqueline Agesa, Andrew Dabalen Jan 2013

Sources Of The Persistent Gender Wage Gap Along The Unconditional Earnings Distribution: Findings From Kenya, Richard U. Agesa, Jacqueline Agesa, Andrew Dabalen

Economics Faculty Research

Past studies on gender wage inequality in Africa typically attribute the gender pay gap either to gender differences in characteristics or in the return to characteristics. The authors suggest, however, that this understanding of the two sources may be far too general and possibly overlook the underlying covariates that drive the gender wage gap. Moreover, past studies focus on the gender wage gap exclusively at the conditional mean. The authors go further to evaluate the partial contribution of each wage-determining covariate to the magnitude of the gender pay gap along the unconditional earnings distribution. The authors' data are from Kenya, …

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Numerical Investigations Of Convective Initiation In Barbados, Kim Whitehall, Sen Chiao, Margarette Mayers-Als Jan 2013

Numerical Investigations Of Convective Initiation In Barbados, Kim Whitehall, Sen Chiao, Margarette Mayers-Als

Faculty Publications, Meteorology and Climate Science

Localized convection in Barbados accounts for hazardous conditions and a significant percentage of the island’s annual rainfall. The feature results in rainfall accumulations exceeding 50 mm in 3 hours or less, over isolated locations. Weather Research and Forecasting model (WRF) simulations are conducted for a rapid convective initiated and heavy precipitation event of 26 August 2008 over Barbados. The simulation results from the 1 km grid resolution domain depict that the shallow topography on the island plays a significant role in enhancing convective activity under weak synoptically disturbed conditions. The model results also demonstrate that the driving forces for the …

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An Inventory Of The Stellar Initial Mass Function In Early-Type Galaxies, C. Tortora, Aaron J. Romanowsky, N. R. Napolitano Jan 2013

An Inventory Of The Stellar Initial Mass Function In Early-Type Galaxies, C. Tortora, Aaron J. Romanowsky, N. R. Napolitano

Faculty Publications

Given a flurry of recent claims for systematic variations in the stellar initial mass function (IMF), we carry out the first inventory of the observational evidence using different approaches. This includes literature results, as well as our own new findings from combined stellar population synthesis (SPS) and Jeans dynamical analyses of data on ~4500 early-type galaxies (ETGs) from the SPIDER project. We focus on the mass-to-light ratio mismatch relative to the Milky Way IMF, δIMF, correlated against the central stellar velocity dispersion, σsstarf. We find a strong correlation between δIMF and σsstarf, for a wide set of dark matter (DM) …

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Students Talk About Energy In Project- Based Inquiry Science, Benedikt W. Harrer, Virginia J. Flood, Michael C. Wittmann Jan 2013

Students Talk About Energy In Project- Based Inquiry Science, Benedikt W. Harrer, Virginia J. Flood, Michael C. Wittmann

Faculty Publications

We examine the types of emergent language eighth grade students in rural Maine middle schools use when they discuss energy in their first experiences with Project-Based Inquiry Science: Energy, a research-based curriculum that uses a specific language for talking about energy. By comparative analysis of the language used by the curriculum materials to students’ language, we find that students’ talk is at times more aligned with a Stores and Transfer model of energy than the Forms model supported by the curriculum.

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Productive Resources In Students’ Ideas About Energy: An Alternative Analysis Of Watts’ Original Interview Transcripts, Benedikt W. Harrer, Virginia J. Flood, Michael C. Wittmann Jan 2013

Productive Resources In Students’ Ideas About Energy: An Alternative Analysis Of Watts’ Original Interview Transcripts, Benedikt W. Harrer, Virginia J. Flood, Michael C. Wittmann

Faculty Publications

For over 30 years, researchers have investigated students’ ideas about energy with the intent of reforming instructional practice. In this pursuit, Watts contributed an influential study with his 1983 paper “Some alternative views of energy” [Phys. Educ. 18, 213 (1983)]. Watts’ “alternative frameworks” continue to be used for categorizing students’ non-normative ideas about energy. Using a resources framework, we propose an alternate analysis of student responses from Watts’ interviews. In our analysis, we show how students’ activated resources about energy are disciplinarily productive. We suggest that fostering seeds of scientific understandings in students’ ideas about energy may play an important …

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Planetary Nebula Spectrograph Survey Of S0 Galaxy Kinematics – Ii. Clues To The Origins Of S0 Galaxies, A. Cortesi, M. R. Merrifield, L. Coccato, M. Arnaboldi, O. Gerhard, Aaron J. Romanowsky, N. G. Douglass, K. Kuiijken, M. Capaccioli, K. C. Freeman, K. Saha, A. L. Chies-Santos Jan 2013

Planetary Nebula Spectrograph Survey Of S0 Galaxy Kinematics – Ii. Clues To The Origins Of S0 Galaxies, A. Cortesi, M. R. Merrifield, L. Coccato, M. Arnaboldi, O. Gerhard, Aaron J. Romanowsky, N. G. Douglass, K. Kuiijken, M. Capaccioli, K. C. Freeman, K. Saha, A. L. Chies-Santos

Faculty Publications

The stellar kinematics of the spheroids and discs of S0 galaxies contain clues to their formation histories. Unfortunately, it is difficult to disentangle the two components and to recover their stellar kinematics in the faint outer parts of the galaxies using conventional absorption line spectroscopy. This paper therefore presents the stellar kinematics of six S0 galaxies derived from observations of planetary nebulae, obtained using the Planetary Nebula Spectrograph. To separate the kinematics of the two components, we use a maximum-likelihood method that combines the discrete kinematic data with a photometric component decomposition. The results of this analysis reveal that: the …

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The Planetary Nebula Spectrograph Survey Of S0 Galaxy Kinematics. Data And Overview, A. Cortesi, M. Arnaboldi, L. Coccato, M. R. Merrifield, O. Gerhard, S. Bamford, Aaron J. Romanowsky, N. R. Napolitano, N. G. Douglas, K. Kuiijken, M. Capaccioli, K. C. Freeman, A. L. Chies-Santos, V. Pota Jan 2013

The Planetary Nebula Spectrograph Survey Of S0 Galaxy Kinematics. Data And Overview, A. Cortesi, M. Arnaboldi, L. Coccato, M. R. Merrifield, O. Gerhard, S. Bamford, Aaron J. Romanowsky, N. R. Napolitano, N. G. Douglas, K. Kuiijken, M. Capaccioli, K. C. Freeman, A. L. Chies-Santos, V. Pota

Faculty Publications

The origins of S0 galaxies remain obscure, with various mechanisms proposed for their formation, likely depending on environment. These mechanisms would imprint different signatures in the galaxies' stellar kinematics out to large radii, offering a method for distinguishing between them. We aim to study a sample of six S0 galaxies from a range of environments, and use planetary nebulae (PNe) as tracers of their stellar populations out to very large radii, to determine their kinematics in order to understand their origins. Using a special-purpose instrument, the Planetary Nebula Spectrograph, we observe and extract PNe catalogues for these six systems*. We …

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The Sluggs Survey: Wide Field Imaging Of The Globular Cluster System Of Ngc 4278, C. Usher, D. A. Forbes, L. R. Spitler, J. P. Brodie, Aaron J. Romanowsky, J. Strader, K. A. Woodley Jan 2013

The Sluggs Survey: Wide Field Imaging Of The Globular Cluster System Of Ngc 4278, C. Usher, D. A. Forbes, L. R. Spitler, J. P. Brodie, Aaron J. Romanowsky, J. Strader, K. A. Woodley

Faculty Publications

We use multipointing Hubble Space Telescope Advanced Camera for Surveys and wide field Subaru Suprime-Cam imaging to study the globular cluster system of the L* elliptical galaxy NGC 4278. We have also obtained a handful of new globular cluster spectra with the Keck Deep Imaging Multi-Object Spectrograph. We determine the globular cluster surface density profile and use it to calculate the total number of globular clusters, finding the system to be slightly more populous than average for galaxies of its luminosity. We find clear evidence for bimodality in the globular cluster colour distribution and for a colour–magnitude relation in the …

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The Sluggs Survey: Probing The Supermassive Blackhole Connection With Bulges And Haloes Using Red And Blue Globular Cluster Systems, V. Pota, A. W. Graham, D. A. Forbes, Aaron J. Romanowsky, A. J. Brodie, J. Strader Jan 2013

The Sluggs Survey: Probing The Supermassive Blackhole Connection With Bulges And Haloes Using Red And Blue Globular Cluster Systems, V. Pota, A. W. Graham, D. A. Forbes, Aaron J. Romanowsky, A. J. Brodie, J. Strader

Faculty Publications

Understanding whether the bulge or the halo provides the primary link to the growth of supermassive black holes has strong implications for galaxy evolution and supermassive black hole formation itself. In this paper, we approach this issue by investigating extragalactic globular cluster (GC) systems, which can be used to probe the physics of both the bulge and the halo of the host galaxy. We study the relation between the supermassive black hole masses (MBH) and the GC system velocity dispersions (σGC) using an updated and improved sample of 21 galaxies. We exploit the dichotomy of GC system colours, to test …

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Mond And Imf Variations In Early-Type Galaxies From Atlas3d, C. Tortora, Aaron J. Romanowsky, V. F. Cardone, N. R. Napolitano, Ph Jetzer Jan 2013

Mond And Imf Variations In Early-Type Galaxies From Atlas3d, C. Tortora, Aaron J. Romanowsky, V. F. Cardone, N. R. Napolitano, Ph Jetzer

Faculty Publications

No abstract provided.

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The Sluggs Survey: Outer Triaxiality In The Fast Rotator Elliptical Ngc 4473, C. Foster, J. A. Arnold, D. A. Forbes, N. Pastorello, Aaron J. Romanowsky, L. R. Spitler, J. Strader, J. P. Brodie Jan 2013

The Sluggs Survey: Outer Triaxiality In The Fast Rotator Elliptical Ngc 4473, C. Foster, J. A. Arnold, D. A. Forbes, N. Pastorello, Aaron J. Romanowsky, L. R. Spitler, J. Strader, J. P. Brodie

Faculty Publications

Systematic surveys of nearby early-type galaxies using integral field unit (IFU) spectrograph data have revealed that galaxies can hide interesting structures only visible through kinematic studies. As part of their pioneering work, the ATLAS3D team have shown that most morphologically elliptical galaxies are centrally kinematically disc like. Hence, while global morphology suggests that ellipticals are ellipsoidal/triaxial in shape, their central kinematics may be consistent with (inclined) oblate systems. Here, we study the fast rotator elliptical galaxy: NGC 4473. Using slitlets, we obtain galaxy light kinematics out to unprecedentedly large galactocentric radii (2.5 effective radii). While we confirm the IFU results …

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The Densest Galaxy, J. Strader, A. C. Seth, J. P. Brodie, D. A. Forbes, G. Fabbiano, Aaron J. Romanowsky, C. Conroy, N. Caldwell, V. Pota, C. Usher, J. A. Arnold Jan 2013

The Densest Galaxy, J. Strader, A. C. Seth, J. P. Brodie, D. A. Forbes, G. Fabbiano, Aaron J. Romanowsky, C. Conroy, N. Caldwell, V. Pota, C. Usher, J. A. Arnold

Faculty Publications

We report the discovery of a remarkable ultra-compact dwarf galaxy around the massive Virgo elliptical galaxy NGC 4649 (M60), which we call M60-UCD1. With a dynamical mass of 2.0 × 108 M ☉ but a half-light radius of only ~24 pc, M60-UCD1 is more massive than any ultra-compact dwarfs of comparable size, and is arguably the densest galaxy known in the local universe. It has a two-component structure well fit by a sum of Sérsic functions, with an elliptical, compact (rh = 14 pc; n ~ 3.3) inner component and a round, exponential, extended (rh = 49 pc) outer component. …

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Filling The Gap: A New Class Of Old Star Cluster?, D. A. Forbes, V. Pota, C. Usher, Aaron J. Romanowsky, J. Strader, J. P. Brodie, J. A. Arnold, L. R. Spitler Jan 2013

Filling The Gap: A New Class Of Old Star Cluster?, D. A. Forbes, V. Pota, C. Usher, Aaron J. Romanowsky, J. Strader, J. P. Brodie, J. A. Arnold, L. R. Spitler

Faculty Publications

It is not understood whether long-lived star clusters possess a continuous range of sizes and masses (and hence densities) or if rather, they should be considered as distinct types with different origins. Utilizing the Hubble Space Telescope to measure sizes and long exposures on the Keck 10 m telescope to obtain distances, we have discovered the first confirmed star clusters that lie within a previously claimed size–luminosity gap dubbed the ‘avoidance zone’ by Hwang et al. The existence of these star clusters extends the range of sizes, masses and densities for star clusters, and argues against current formation models that …

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The Sluggs Survey: The Globular Cluster Systems Of Three Early-Type Galaxies Using Wide-Field Imaging, S. S. Kartha, D. A. Forbes, L. R. Spitler, Aaron J. Romanowsky, J. A. Arnold, J. P. Brodie Jan 2013

The Sluggs Survey: The Globular Cluster Systems Of Three Early-Type Galaxies Using Wide-Field Imaging, S. S. Kartha, D. A. Forbes, L. R. Spitler, Aaron J. Romanowsky, J. A. Arnold, J. P. Brodie

Faculty Publications

We present the results from a wide-field imaging study of globular cluster (GC) systems in three early-type galaxies. Combinations of Subaru/Suprime-Cam, CFHT/MegaCam and HST/WFPC2/ACS data were used to determine the GC system properties of three highly flattened galaxies NGC 720, NGC 1023 and NGC 2768. This work is the first investigation of the GC system in NGC 720 and NGC 2768 to very large galactocentric radius (∼ 100 kpc). The three galaxies have clear blue and red GC subpopulations. The radial surface densities of the GC systems are fitted with Sersic profiles, and detected out to 15, 8 and 10 …

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Angular Momentum And Galaxy Formation Revisited: Effects Of Variable Mass-To-Light Ratios, S. M. Fall, Aaron J. Romanowsky Jan 2013

Angular Momentum And Galaxy Formation Revisited: Effects Of Variable Mass-To-Light Ratios, S. M. Fall, Aaron J. Romanowsky

Faculty Publications

We rederive the relation between the specific angular momentum j sstarf and the mass M sstarf of the stellar matter in galaxies of different morphological types. This is a revision of the j sstarf-M sstarf diagram presented in our recent comprehensive study of galactic angular momentum. In that work, we estimated j sstarf from kinematic and photometric data that extended to large radii and M sstarf from near-infrared luminosities LK with an assumed universal mass-to-light ratio M sstarf/LK . However, recent stellar population models show large variations in M sstarf/LK correlated with B – V color. In the present work, …

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