Physical Sciences and Mathematics Commons^™

Coincidence Angular Correlation In Electron Impact Single Or Double Ionisation Of Atoms And Molecules, E. M. Staicu-Casagrande, Adnan Naja, Xueguang Ren, Mohammed Nekkab, Fabrice Catoire, F. Mezdari, Azzeddine Lahmam-Bennani, Don H. Madison, Ochbadrakh Chuluunbaatar, Boghos B. Joulakian

Physics Faculty Research & Creative Works

Experimental results obtained with our multi-parameter multi-coincidence spectrometer are presented for the (e,3e) double ionisation of Ar and (e,2e) single ionisation of small molecules. The (e,3e) measurements are discussed in terms of competition between the two double ionisation processes present under the chosen kinematics, and qualitative conclusions are given. The results for the ionisation of H₂ and the outer orbital of N₂ are compared with the predictions of the most elaborate available theoretical models for description of the molecular ionisation process. Overall reasonable agreement is observed and tentative interpretations for the discrepancies are discussed.

The Case For Optically Thick High-Velocity Broad-Line Region Gas In Active Galactic Nuclei, Stephanie A. Snedden, C. Martin Gaskell

C. Martin Gaskell Publications

A combined analysis of the profiles of the main broad quasar emission lines in both Hubble Space Telescope and optical spectra shows that while the profiles of the strong UV lines are quite similar, there is frequently a strong increase in the Lyα/Hα ratio in the high-velocity gas.We show that the suggestion that the high-velocity gas is optically thin presents many problems.We show that the relative strengths of the high-velocity wings arise naturally in an optically thick BLR component. An optically thick model successfully explains the equivalent widths of the lines, the Lyα/Hα ratios and flatter Balmer decrements in the …

Agn Reddening And Ultraviolet Extinction Curves From Hubble Space Telescope Spectra, C. Martin Gaskell, C. Martin Gaskell

C. Martin Gaskell Publications

We present intrinsic extinction curves for 14 AGNs. The AGNs have reddenings, E(B-V), of up to 0.36 mag. The majority (13 out of 14) of the extinction curves are not steep in the UV. Of the seven best determined extinction curves, five have extinction curves that are as flat as the standard Galactic curve in the optical and near UV, but flatter in the far UV, and without the λ2175 feature. One AGN, B3 0754+394, has a steep SMC-like extinction curve, and another, Mrk 304, has an LMC-like extinction curve, including a probable λ2175 bump. The remaining seven, lower-quality, extinction …

Discovery Of Polarization Reverberation In Ngc 4151, C. Martin Gaskell, René W. Goosmann, Nelly I. Merkulova, Nikolay M. Shakhovskoy, Masatoshi Shoji

C. Martin Gaskell Publications

Observations of the optical polarization of NGC 4151 in 1997–2003 show variations of an order of magnitude in the polarized flux while the polarization position angle remains constant. The amplitude of variability of the polarized flux is comparable to the amplitude of variability of the total U-band flux, except that the polarized flux follows the total flux with a lag of 8±3 days. The time lag and the constancy of the position angle strongly favor a scattering origin for the variable polarization rather than a non-thermal synchrotron origin. The orientation of the position angle of the polarized flux (parallel to …

Ngc 5548: The Agn Energy Budget Problem And The Geometry Of The Broad-Line Region And Torus, C. Martin Gaskell, Elizabeth S. Klimek, Ludmila S. Nazarova

C. Martin Gaskell Publications

We consider in detail the spectral energy distribution (SED) and multi-wavelength variability of NGC 5548. Comparison with the SEDs of other AGNs implies that the internal reddening of NGC 5548 is E(B-V) = 0.17 mag. The extinction curve is consistent with the mean curve of other AGNs found by Gaskell & Benker, but inconsistent with an SMC-type reddening curve. Because most IR emission originates exterior to the broad-line region (BLR), the SED seen by the inner BLR is different from that seen by the outer BLR and from the earth. The most likely BLR covering factor is ~ 40% and …

Transformations Between 2mass, Sdss And Bvri Photometric Systems: Bridging The Near Infrared And Optical, S. Bilir, S. Ak, S. Karaali, A. Cabrera-Lavers, T. S. Chonis, C. Martin Gaskell

C. Martin Gaskell Publications

We present color transformations for the conversion of the 2MASS photometric system to the Johnson-Cousins UBV RI system and further into the SDSS ugriz system. We have taken SDSS gri magnitudes of stars measured with the 2.5-m telescope from SDSS Data Release 5 (DR5), and BV RI and JHK_s magnitudes from Stetson’s catalogue and Cutri et al. (2003), respectively. We matched thousands of stars in the three photometric systems by their coordinates and obtained a homogeneous sample of 825 stars by the following constraints, which are not used in previous transformations: 1) the data are de-reddened, 2) giants are …

Half Metallic Ferromagnets, Peter A. Dowben

Peter Dowben Publications

Since its introduction by de Groot and colleagues in the early 1980s [1], the concept of half metallic ferromagnetism has attracted great interest. Idealized, half-metals have only one spin channel for conduction: the spin-polarized band structure exhibits metallic behavior for one spin channel, while the other spin band structure exhibits a gap at the Fermi level. Due to the gap for one spin direction, the density of states at the Fermi level has, theoretically, 100 % spin polarization. This gap in the density of states in one spin at the Fermi level, for example ↓ so N↓(E_{F …}

Demersal Fishes Associated With Lophelia Pertusa Coral And Hard-Substrate Biotopes On The Continental Slope, Northern Gulf Of Mexico, Kenneth J. Sulak, R. Allen Brooks, Kirsten E. Luke, April D. Norem, Michael Randall, Andrew J. Quaid, George E. Yeargin, Jana M. Miller, William M. Harden, John H. Caruso, Steve W. Ross

United States Geological Survey: Staff Publications

The demersal fish fauna of Lophelia pertusa (Linnaeus, 1758) coral reefs and associated hard-bottom biotopes was investigated at two depth horizons in the northern Gulf of Mexico using a manned submersible and remote sampling. The Viosca Knoll fauna consisted of at least 53 demersal fish species, 37 of which were documented by submersible video. On the 325 m horizon, dominant taxa determined from frame-by-frame video analysis included Stromateidae, Serranidae, Trachichthyidae, Congridae, Scorpaenidae, and Gadiformes. On the 500 m horizon, large mobile visual macrocarnivores of families Stromateidae and Serranidae dropped out, while a zeiform microcarnivore assumed importance on reef “Thicket” biotope, …

A Note On Probability Trees, W. J. Hurley

Journal of Modern Applied Statistical Methods

Not many introductory probability and statistics textbooks emphasize the use of probability trees to make complex probability calculations. This is puzzling in view of the power that trees bring to organizing such calculations for students. An effective classroom technique is discussed is this note.

Measuring Article Quality In Wikipedia: Models And Evaluation, Meiqun Hu, Ee Peng Lim, Aixin Sun, Hady W. Lauw, Ba-Quy Vuong

Research Collection School Of Computing and Information Systems

Wikipedia has grown to be the world largest and busiest free encyclopedia, in which articles are collaboratively written and maintained by volunteers online. Despite its success as a means of knowledge sharing and collaboration, the public has never stopped criticizing the quality of Wikipedia articles edited by non-experts and inexperienced contributors. In this paper, we investigate the problem of assessing the quality of articles in collaborative authoring of Wikipedia. We propose three article quality measurement models that make use of the interaction data between articles and their contributors derived from the article edit history. Our Basic model is designed based …

Sphere Packing, Lattices, And Epstein Zeta Function, Lenny Fukshansky

CMC Faculty Publications and Research

The sphere packing problem in dimension N asks for an arrangement of non-overlapping spheres of equal radius which occupies the largest possible proportion of the corresponding Euclidean space. This problem has a long and fascinating history. In 1611 Johannes Kepler conjectured that the best possible packing in dimension 3 is obtained by a face centered cubic and hexagonal arrangements of spheres. A proof of this legendary conjecture has finally been published in 2005 by Thomas Hales. The analogous problem in dimension 2 has been solved by Laszlo Fejes Toth in 1940, and this really is the extent of our current …

Can Semantic Web Techniques Empower Comprehension And Projection In Cyber Situational Awareness?, Amit P. Sheth

Kno.e.sis Publications

No abstract provided.

Supporting Complex Thematic, Spatial And Temporal Queries Over Semantic Web Data, Matthew Perry, Amit P. Sheth, Farshad Hakimpour, Prateek Jain

Kno.e.sis Publications

Spatial and temporal data are critical components in many applications. This is especially true in analytical domains such as national security and criminal investigation. Often, the analytical process requires uncovering and analyzing complex thematic relationships between disparate people, places and events. Fundamentally new query operators based on the graph structure of Semantic Web data models, such as semantic associations, are proving useful for this purpose. However, these analysis mechanisms are primarily intended for thematic relationships. In this paper, we describe a framework built around the RDF metadata model for analysis of thematic, spatial and temporal relationships between named entities. We …

Ammonia Elimination From Protonated Nucleobases And Related Synthetic Substrates, Ming Qian, Shuo Yang, Hong Wu, Papiya S. Majumdar, Nathan D. Leigh, Rainer Glaser

Chemistry Faculty Research & Creative Works

The results are reported of mass-spectrometric studies of the nucleobases adenine 1h (1, R = H), guanine 2h, and cytosine 3h. The protonated nucleobases are generated by electrospray ionization of adenosine 1r (1, R = ribose), guanosine 2r, and deoxycytidine 3d (3, R = deoxyribose) and their fragmentations were studied with tandem mass spectrometry. In contrast to previous EI-MS studies of the nucleobases, NH₃ elimination does present a major path for the fragmentations of the ions [1h + H]⁺, [2h + H]⁺, and …

Electrostatic Force Microscopy Studies Of Boron-Doped Diamond Films, Santosh Gupta, O. A. Williams, Eric W. Bohannan

Computer Science Faculty Research & Creative Works

Much has been learned from electrochemical properties of boron-doped diamond (BDD) thin films synthesized using microwave plasma-assisted chemical vapor deposition about the factors influencing electrochemical activity, but some characteristics are still not entirely understood, such as its electrical conductivity in relation with microscale structure. Therefore, to effectively utilize these materials, understanding both the microscopic structure and physical (electrical, in particular) properties becomes indispensable. in addition to topography using atomic force microscopy, electrostatic force microscopy (EFM) in phase mode measuring the long-range electrostatic force gradients, helps to map the electrical conductivity heterogeneity of boron-doped micro-/nanocrystalline diamond surfaces. the mapping of electrical …

Semantic Convergence Of Wikipedia Articles, Christopher J. Thomas, Amit P. Sheth

Kno.e.sis Publications

Social networking, distributed problem solving and human computation have gained high visibility. Wikipedia is a well established service that incorporates aspects of these three fields of research. For this reason it is a good object of study for determining quality of solutions in a social setting that is open, completely distributed, bottom up and not peer reviewed by certified experts. In particular, this paper aims at identifying semantic convergence of Wikipedia articles; the notion that the content of an article stays stable regardless of continuing edits. This could lead to an automatic recommendation of good article tags but also add …

Harmonic Holography: A New Holographic Principle, Ye Pu, Martin Centurion, Demetri Psaltis

Martin Centurion Publications

The process of second harmonic generation (SHG) has a unique property of forming a sharp optical contrast between noncentrosymmetric crystalline materials and other types of material, which is a highly valuable asset for contrast microscopy. The coherent signal obtained through SHG also allows for the recording of holograms at high spatial and temporal resolution, enabling whole-field four-dimensional microscopy for highly dynamic microsystems and nanosystems. Here we describe a new holographic principle, harmonic holography (H²), which records holograms between independently generated second harmonic signals and reference. We experimentally demonstrate this technique with digital holographic recording of second harmonic signals …

Conjunctive Queries For A Tractable Fragment Of Owl 1.1, Markus Krotzsch, Sebastian Rudolph, Pascal Hitzler

Computer Science and Engineering Faculty Publications

Despite the success of the Web Ontology Language OWL, the development of expressive means for querying OWL knowledge bases is still an open issue. In this paper, we investigate how a very natural and desirable form of queries-namely conjunctive ones-can be used in conjunction with OWL such that one of the major design criteria of the latter-namely decidability-can be retained. More precisely, we show that querying the tractable fragment EL++ of OWL 1.1 is decidable. We also provide a complexity analysis and show that querying unrestricted EL++ is undecidable.

Problem Solving And Proving Via Generalisation, Michael De Villiers, Mary Garner

Faculty Articles

No abstract provided.

Journal Of Combinatorial Optimization, Special Issue On Communication Networks And Internet Applications, Maggie Xiaoyan Cheng

Computer Science Faculty Research & Creative Works

No abstract provided.

Household Food Insecurity Is Inversely Associated With Social Capital And Health In Females From Special Supplemental Nutrition Program For Women, Infants, And Children Households In Appalachian Ohio, Jennifer L. Walker, David H. Holben, Mary L. Kropf, John P. Holcomb Jr., Heidi Anderson

Mathematics and Statistics Faculty Publications

Food insecurity has been negatively associated with social capital (a measure of perceived social trust and community reciprocity) and health status. Yet, these factors have not been studied extensively among women from households participating in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) or the WIC Farmers’ Market Nutrition Program. A cross-sectional, self-administered, mailed survey was conducted in Athens County, Ohio, to examine the household food security status, social capital, and self-rated health status of women from households receiving WIC benefits alone (n=170) and those from households receiving both WIC and Farmers’ Market Nutrition Program benefits (n=65), …

Tidal Flushing Characteristics In Virginia’S Tidal Embayments, Center For Coastal Resources Management, Virginia Institute Of Marine Science, Julie Herman, Jian Shen, Jie Huang

Reports

This project evaluated water bodies in the Virginia coastal zone using several water quality models to calculate residence times. Results were grouped into tidal flushing categories (quickly, intermediately, and slowly flushed) that reflect a relative time frame in which a water body is flushed.

⁵⁷Fe Mössbauer Spectral And Muon Spin Relaxation Study Of The Magnetodynamics Of Monodispersed Γ-Fe₂O₃ Nanoparticles, Leïla Rebbouh, Raphäel P. Hermann, Fernande Grandjean, Taeghwan Hyeon, Kwangjin An, Alex Amato, Gary J. Long

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of monodispersed iron oxide nanoparticles with diameters of 4, 7, 9, and 11 nm have been measured between 4.2 and 315 K and fitted within the formalism for stochastic fluctuations of the hyperfine Hamiltonian. In this model, the hyperfine field is assumed to relax between the six ±x, ±y, and ±z directions in space with a distribution of relaxation rates that is temperature dependent. Muon spin relaxation measurements have been carried out on the 9 nm particles between 4.2 and 295 K. Both techniques reveal three regimes in the magnetic dynamics of these nanoparticles. In the low-temperature …

A Strategy To Protect And Sensitize Near-Infrared Luminescent Nd3+ And Yb3+: Organic Tropolonate Ligands For The Sensitization Of Ln3+-Doped Nayf4 Nanocrystals, Jian Zhang, Chad M. Shade, Demetra A. Chengelis, Stéphane Petoud

Chemistry Department: Faculty Publications

A strategy to sensitize and protect near-infrared (NIR) emitting Nd³⁺ and Yb³⁺ is presented. Combining protection provided by the inorganic matrix of NaYF₄ nanocrystals and sensitization from tropolonate ligands capped on their surface, the lanthanide cation centered luminescence was observed through the ligand excitation. The extended lanthanide luminescence lifetimes indicate the success of this strategy.

Matched Filtering And Parameter Estimation Of Ringdown Waveforms, Emanuele Berti, Jaime Cardoso, Vitor Cardoso, Marco Cavaglia

Physics Faculty Research & Creative Works

Using recent results from numerical relativity simulations of nonspinning binary black hole mergers, we revisit the problem of detecting ringdown waveforms and of estimating the source parameters, considering both LISA and Earth-based interferometers. We find that Advanced LIGO and EGO could detect intermediate-mass black holes of mass up to ∼10³M_⊙ out to a luminosity distance of a few Gpc. For typical multipolar energy distributions, we show that the single-mode ringdown templates presently used for ringdown searches in the LIGO data stream can produce a significant event loss ( > 10% for all detectors in a large interval of …

Zeeman Splitting And G Factor Of The 1s²2s²2p ²P3/2 And ²P1/2 Levels In Ar¹³⁺, R. Soria Orts, Jose R. Crespo Lopez-Urrutia, Hjalmar Bruhns, Antonio J. Gonzalez, Zoltan Harman, Ulrich D. Jentschura, Christoph H. Keitel, Alain Lapierre, Hiroyuki Tawara, I. I. Tupitsyn, Joachim Hermann Ullrich, Andrey V. Volotka

Physics Faculty Research & Creative Works

The Zeeman line components of the magnetic-dipole (M1) 1s² 2s^{2 2} P_1/2 -²P_3/2 transition in boronlike Ar¹³⁺ were experimentally resolved by high-precision emission spectroscopy using the Heidelberg electron beam ion trap. We determined the gyromagnetic (g) factors of the ground and first-excited levels to be g_1/2 =0.663(7) and g_3/2 =1.333(2), respectively. This corresponds to a measurement of the g factor of a relativistic electron in a bound non- S state of a multielectron ion with a 1.5 parts-per-thousand accuracy. The results are compared to theoretical calculations by means of the configuration …

In-House Polymerase Chain Reaction For Affordable And Sustainable Chlamydia Trachomatis Detection In Trinidad And Tobago, Joanne Rampersad, Xiaohui Wang, Helen Gayadeen, Samuel Ramsewak, David Ammons

Chemistry Faculty Publications and Presentations

Objectives: To provide a preliminary assessment of in-house polymerase chain reaction (PCR) as an alternative to the more costly commercial test for detection of asymptomatic infection by Chlamydia trachomatis and to provide much needed demographic data on infection indicators within the Trinidad and Tobago public health care system.

Methods: An inexpensive in-house nested-PCR with an Internal Amplification Control was used to detect C. trachomatis and Neisseria gonorrhoeae in urine samples collected from 273 apparently healthy, pregnant women from March-September 2004 in Trinidad, West Indies. Demographic information on participants was collected and subjected to statistical analyses.

Results: C. trachomatis was detected …

Race: A Robust Adaptive Caching Strategy For Buffer Cache, Yifeng Zhu, Hong Jiang

School of Computing: Faculty Publications

While many block replacement algorithms for buffer caches have been proposed to address the well-known drawbacks of the LRU algorithm, they are not robust and cannot maintain an consistent performance improvement over all workloads. This paper proposes a novel and simple replacement scheme, called RACE (Robust Adaptive buffer Cache management schemE), which differentiates the locality of I/O streams by actively detecting access patterns inherently exhibited in two correlated spaces: the discrete block space of program contexts from which I/O requests are issued and the continuous block space within files to which I/O requests are addressed. This scheme combines global I/O …

Fish And Coral Reef Communities Of The Parque Nacional Sistema Arrecifal Veracruzano (Veracruz Coral Reef System National Park) Veracruz, Mexico: Preliminary Results, Marcos Alberto Rangel Avalos, Lance K. B. Jordan, Brian K. Walker, David S. Gilliam, Elvira Carvajal Hinojosa, Richard E. Spieler

Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

Effective resource management requires robust baseline datasets and efficient monitoring programs to identify and quantify temporal change. The Parque Nacional Sistema Arrecifal Veracruzano (Veracruz Coral Reef System National Park) encompasses a total of 52000ha including 23 coral reefs in two island groups separated by the mouth of the Jamapa River; one near the port of Veracruz, Mexico and one approximately 20km south near Punta Antón Lizardo. Both groups receive substantial fisheries pressure and other anthropogenic impacts. Using non-destructive, visual methods we surveyed fish and benthic assemblages at 18 sites, which included 10 individual coral reefs within the Park. For fishes, …

Hydrogen-Bonding Networks In Heterocyclic Thioureas, Aakarsh Saxena, Robert D. Pike

Arts & Sciences Articles

The synthesis of heterocyclic thioureas from heterocyclic amines with phenyl- or methylisothiocyanate or CS2 is described. Seven new X-ray crystal structures are reported: In N-(3-pyridyl)-N′-phenylthiourea (Pna21, a = 10.1453(3), b = 17.6183(5), c = 6.4787(2), V = 1158.02(6), Z = 4) hydrogen-bonding results in formation of a 3D network consisting of helices, which form channels parallel to the c-axis. In N-(4-pyridyl)-N′-phenylthiourea (P21/c, a = 16.9314(3), b = 10.3554(2), c = 13.5152(3), β = 106.5080(10), V = 2271.96(8), Z = 4, two independent molecules) hydrogen-bonding results in N–H···S bridged dimers …