College of Science (COS)

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    1/N expansion for the degenerate Anderson model in the mixed-valence regime
    Zhang, F. C.; Lee, T. K. (American Physical Society, 1983-07)
    The 1N expansion method for the degenerate Anderson model is formulated. N is the degeneracy factor of one of the f-electron configurations. Various ground-state properties are calculated. Excellent agreement with the result of Bethe ansatz for N=6 is shown. The rate of convergence of the series is analyzed. The merit and inadequacy of the method are discussed. At zero temperature the ratio of the magnetic susceptibility and the specific-heat linear coefficient is shown to lie within a range of 1 and 1+(N-1)-1.
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    10 kpc Scale Seyfert Galaxy Outflow: HST/COS Observations of IRAS F22456-5125
    Borguet, Benoit C. J.; Edmonds, Douglas; Arav, Nahum; Dunn, Jay; Kriss, Gerard A. (IOP Publishing Ltd., 2012-06)
    We present analysis of the UV spectrum of the low-z AGN IRAS F22456-5125 obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The spectrum reveals six main kinematic components, spanning a range of velocities of up to 800 km s (1), which for the first time are observed in troughs associated with C II, C IV, N V, Si II, Si III, Si IV, and S IV. We also obtain data on the O VI troughs, which we compare to those available from an earlier Far Ultraviolet Spectroscopic Explorer epoch. Column densities measured from these ions allow us to derive a well-constrained photoionization solution for each outflow component. Two of these kinematic components show troughs associated with transitions from excited states of Si II and C II. The number density inferred from these troughs, in combination with the deduced ionization parameter, allows us to determine the distance to these outflow components from the central source. We find these components to be at a distance of similar to 10 kpc. The distances and the number densities derived are consistent with the outflow being part of a galactic wind.
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    14-year program monitoring the flux densities of 33 radio sources at low frequencies
    Salgado, José Francisco; Altschuler, Daniel R.; Ghosh, Tapasi; Dennison, Brian K.; Mitchell, Kenneth J.; Payne, Harry E. (IOP PUBLISHING LTD, 1999-01)
    We present the results of a low-frequency flux density monitoring program of 33 extragalactic radio sources. The light curves at 318 and 430 MHz over a 14 yr period are presented. The measurements were made with the NAIC Arecibo 305 m radio telescope at approximately bimonthly intervals between 1980 January and 1989 February and at less regular intervals between 1989 October and 1993 October, for a total of 64 observing sessions. In addition, we provide a first discussion of the results, pointing out several source properties and interesting objects.
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    2008-09 Annual Report Department of Biological Sciences
    (Virginia Tech, 2009-08-19)
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    2009-10 Annual Report Department of Biological Sciences
    (Virginia Tech, 2010-08-11)
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    The 2010 Interim Report of the Long-Baseline Neutrino Experiment Collaboration Physics Working Groups
    Collaboration, TLBNE; Akiri, T.; Allspach, D.; Andrews, M.; Arisaka, K.; Arrieta-Diaz, E.; Artuso, M.; Bai, X.; Balantekin, A. B.; Baller, B.; Barletta, W. A.; Barr, G.; Bass, M.; Beck, A.; Becker, B.; Bellini, V.; Benhar, Omar; Berger, B. E.; Bergevin, M.; Berman, E.; Berns, H.; Bernstein, A.; Beroz, F.; Bhatnagar, V.; Bhuyan, B.; Bionta, R.; Bishai, M.; Blake, A.; Blaufuss, E.; Bleakley, B.; Blucher, E.; Blusk, S.; Boehnlein, D.; Bolton, T.; Brack, J.; Bradford, R.; Breedon, R.; Bromberg, C.; Brown, R.; Buchanan, N.; Camilleri, Leslie; Campbell, M.; Carr, Rachel E.; Carminati, G.; Chen, A.; Chen, H.; Cherdack, D.; Chi, C.; Childress, S.; Choudhary, B.; Church, E.; Cline, D.; Coleman, S.; Corey, R.; D'Agostino, M. V.; Davies, G. S.; Dazeley, S.; Jong, J. D.; DeMaat, B.; Demuth, D.; Dighe, A.; Djurcic, Zelimir; Dolph, J.; Drake, G.; Drozhdin, A.; Duan, H.; Duyang, H.; Dye, S.; Dykhuis, T.; Edmunds, D.; Elliott, S.; Enomoto, S.; Escobar, C. O.; Felde, J.; Feyzi, F.; Fleming, B.; Fowler, J.; Fox, W.; Friedland, A.; Fujikawa, B. K.; Gallagher, H.; Garilli, G.; Garvey, G. T.; Gehman, V. M.; Geronimo, G. D.; Gill, R.; Goodman, M.; Goon, J.; Gorbunov, D.; Gran, R.; Guarino, V.; Guarnaccia, E.; Guenette, R.; Gupta, P.; Habig, A.; Hackenburg, R. W.; Hahn, A.; Hahn, R.; Haines, T.; Hans, S.; Harton, J.; Hays, S.; Hazen, E.; He, Q.; Heavey, A.; Heeger, K.; Hellauer, R.; Himmel, A.; Horton-Smith, Glenn A.; Howell, J.; Huber, Patrick; Hurh, P.; Huston, J.; Hylen, J.; Insler, J.; Jaffe, D.; James, C.; Johnson, C.; Johnson, M.; Johnson, R.; Johnson, W.; Johnston, W.; Johnstone, J.; Jones, B.; Jostlein, H.; Junk, T.; Junnarkar, S.; Kadel, R.; Kafka, T.; Kaminski, D.; Karagiorgi, Georgia S.; Karle, A.; Kaspar, J.; Katori, T.; Kayser, B.; Kearns, E.; Kettell, S. H.; Khanam, F.; Klein, J.; Kneller, J.; Koizumi, G.; Kopp, J.; Kopp, S.; Kropp, W.; Kudryavtsev, V. A.; Kumar, A.; Kumar, J.; Kutter, T.; Lackowski, T.; Lande, K.; Lane, C.; Lang, K.; Lanni, F.; Lanza, R.; Latorre, T.; Learned, J.; Lee, D.; Lee, K.; Li, Y.; Linden, S.; Ling, J.; Link, Jonathan M.; Littenberg, L.; Loiacono, L.; Liu, T.; Losecco, J.; Louis, W.; Lucas, P.; Lunardini, C.; Lundberg, B.; Lundin, T.; Makowiecki, D.; Malys, S.; Mandal, S.; Mann, A.; Mantsch, P.; Marciano, W. J.; Mariani, Camillo; Maricic, Jelena; Marino, A.; Marshak, M.; Maruyama, R.; Matthews, J.; Matsuno, S.; Mauger, C.; McCluskey, E.; McDonald, K.; McFarland, K. S.; McKeown, R.; McTaggart, R.; Mehdiyev, R.; Melnitchouk, W.; Meng, Y.; Mercurio, B.; Messier, M.; Metcalf, W.; Milincic, R.; Miller, W.; Mills, G.; Mishra, S.; MoedSher, S.; Mohapatra, D.; Mokhov, N.; Moore, C.; Morfin, J.; Morse, W.; Moss, A.; Mufson, S.; Musser, J.; Naples, D.; Napolitano, J.; Newcomer, M.; Norris, B.; Ouedraogo, S.; Page, B.; Pakvasa, S.; Paley, J.; Paolone, V.; Papadimitriou, V.; Parsa, Z.; Partyka, K.; Pavlovic, Z.; Pearson, C.; Perasso, S.; Petti, R.; Plunkett, R.; Polly, C. C.; Pordes, S.; Potenza, R.; Prakash, A.; Prokofiev, O.; Qian, X.; Raaf, J.; Radeka, V.; Raghavan, R.; Rameika, R.; Rebel, B.; Rescia, S.; Reitzner, D.; Richardson, M.; Riesselmann, K.; Robinson, M.; Rosen, M.; Rosenfeld, C.; Rucinski, R.; Russo, T.; Sahijpal, S.; Salon, S.; Samios, N.; Sanchez, Maria Cristina; Schmitt, R.; Schmitz, D.; Schneps, J.; Scholberg, K.; Seibert, S.; Sergiampietri, F.; Shaevitz, Marjorie Hansen; Shanahan, P.; Shaposhnikov, M.; Sharma, R.; Simos, N.; Singh, V.; Sinnis, G.; Sippach, W.; Skwarnicki, T.; Smy, M.; Sobel, H.; Soderberg, M.; Sondericker, J.; Sondheim, W.; Spitz, Joshua; Spooner, N.; Stancari, M.; Stancu, Ion; Stewart, J.; Stoler, P.; Stone, J.; Stone, S.; Strait, J.; Straszheim, T.; Striganov, S.; Sullivan, G.; Svoboda, R.; Szczerbinska, B.; Szelc, A.; Talaga, R.; Tanaka, H.; Tayloe, R.; Taylor, D.; Thomas, J.; Thompson, L.; Thomson, M.; Thorn, C.; Tian, X.; Toki, W.; Tolich, N.; Tripathi, M.; Trovato, M.; Tseung, H.; Tzanov, M.; Urheim, J.; Usman, S.; Vagins, M. R.; Berg, R. V.; Water, R. V. D.; Varner, G.; Vaziri, K.; Velev, G.; Viren, B.; Wachala, T.; Walter, C.; Wang, H.; Wang, Z.; Warner, D.; Webber, D.; Weber, A.; Wendell, R.; Wendt, C.; Wetstein, M.; White, H.; White, S.; Whitehead, L.; Willis, W.; Wilson, R. J.; Winslow, L.; Ye, J.; Yeh, M.; Yu, B.; Zeller, Geralyn P.; Zhang, C.; Zimmerman, E.; Zwaska, R. (2011-10-27)
    In early 2010, the Long-Baseline Neutrino Experiment (LBNE) science collaboration initiated a study to investigate the physics potential of the experiment with a broad set of different beam, near- and far-detector configurations. Nine initial topics were identified as scientific areas that motivate construction of a long-baseline neutrino experiment with a very large far detector. We summarize the scientific justification for each topic and the estimated performance for a set of far detector reference configurations. We report also on a study of optimized beam parameters and the physics capability of proposed Near Detector configurations. This document was presented to the collaboration in fall 2010 and updated with minor modifications in early 2011.
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    The 2015 landslide and tsunami in Taan Fiord, Alaska
    Higman, Bretwood; Shugar, Dan H.; Stark, Colin P.; Ekstrom, Goran; Koppes, Michele N.; Lynett, Patrick; Dufresne, Anja; Haeussler, Peter J.; Geertsema, Marten; Gulick, Sean; Mattox, Andrew; Venditti, Jeremy G.; Walton, Maureen A. L.; McCall, Naoma; Mckittrick, Erin; MacInnes, Breanyn; Bilderback, Eric L.; Tang, Hui; Willis, Michael J.; Richmond, Bruce; Reece, Robert S.; Larsen, Chris; Olson, Bjorn; Capra, James; Ayca, Aykut; Bloom, Colin; Williams, Haley; Bonno, Doug; Weiss, Robert; Keen, Adam; Skanavis, Vassilios; Loso, Michael (Springer Nature, 2018-09-06)
    Glacial retreat in recent decades has exposed unstable slopes and allowed deep water to extend beneath some of those slopes. Slope failure at the terminus of Tyndall Glacier on 17 October 2015 sent 180 million tons of rock into Taan Fiord, Alaska. The resulting tsunami reached elevations as high as 193 m, one of the highest tsunami runups ever documented worldwide. Precursory deformation began decades before failure, and the event left a distinct sedimentary record, showing that geologic evidence can help understand past occurrences of similar events, and might provide forewarning. The event was detected within hours through automated seismological techniques, which also estimated the mass and direction of the slide - all of which were later confirmed by remote sensing. Our field observations provide a benchmark for modeling landslide and tsunami hazards. Inverse and forward modeling can provide the framework of a detailed understanding of the geologic and hazards implications of similar events. Our results call attention to an indirect effect of climate change that is increasing the frequency and magnitude of natural hazards near glaciated mountains.
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    2017 State of the College of Science
    Morton, Sally C. (Virginia Tech. College of Science, 2017-10-27)
    Slides from the 2017 State of the College of Science address, presented on October 27, 2017, by Dean Sally C. Morton.
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    2018 State of the Virginia Tech College of Science
    Morton, Sally C. (Virginia Tech. College of Science, 2018-10-25)
    College of Science Dean Sally C. Morton presented the 2018 State of the College on Oct. 25 for faculty, staff, alumni, and friends of the college, as well as the university community. This is a photographic slideshow from that presentation.
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    2024 Symposium on Soft Matter and Biological Physics
    (Virginia Tech, 2024-08)
    A program for the symposium held on August 31, 2024, in Hahn Hall North and Auditorium. This event featured two keynote speakers and a showcase of student poster presentations.
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    2D Hierarchical Microbarcodes with Expanded Storage Capacity for Optical Multiplex and Information Encryption
    Worch, Josh; Xie, Yujie; Tong, Zaizai; Rho, Julia; Dove, Andrew; O'Reilly, Rachel (2023-11-28)
    The design of nanosegregated fluorescent tags/barcodes by geometrical patterning with precise dimensions and hierarchies could integrate multilevel optical information within one carrier and enhance microsized barcoding techniques for ultrahigh-density optical data storage and encryption. However, precise control of the spatial distribution in micro/nanosized matrices intrinsically limits the accessible barcoding applications in terms of material design and construction. Here, crystallization forces are leveraged to enable a rapid, programmable molecular packing and rapid epitaxial growth of fluorescent units in 2D via crystallization-driven self-assembly. The fluorescence encoding density, scalability, information storage capacity, and decoding techniques of the robust 2D polymeric barcoding platform are explored systematically. These results provide both a theoretical and an experimental foundation for expanding the fluorescence storage capacity, which is a longstanding challenge in state-of-the-art microbarcoding techniques and establish a generalized and adaptable coding platform for high-throughput analysis and optical multiplexing.
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    (2S,4R)-4-Fluoro-pyrrolidinium-2-carboxyl-ate
    Hobart, David B. Jr.; Merola, Joseph S. (International Union of Crystallography, 2012-08-01)
    The crystal structure of the title compound, C(5)H(8)FNO(2), at 100 K, displays inter-molecular N-H⋯O hydrogen bonding between the ammonium and carboxyl-ate groups as a result of its zwitterionic nature in the solid state. The five-membered ring adopts an envelope conformation with the C atom at the 3-position as the flap. The compound is of inter-est with respect to the synthesis and structural properties of synthetic collagens. The absolute structure was determined by comparison with the commercially available material.
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    3D electron microscopy and volume-based bouton sorting reveal the selectivity of inputs onto geniculate relay cell and interneuron dendrite segments
    Maher, Erin E.; Briegel, Alex C.; Imtiaz, Shahrozia; Fox, Michael A.; Golino, Hudson; Erisir, Alev (Frontiers, 2023-03)
    IntroductionThe visual signals evoked at the retinal ganglion cells are modified and modulated by various synaptic inputs that impinge on lateral geniculate nucleus cells before they are sent to the cortex. The selectivity of geniculate inputs for clustering or forming microcircuits on discrete dendritic segments of geniculate cell types may provide the structural basis for network properties of the geniculate circuitry and differential signal processing through the parallel pathways of vision. In our study, we aimed to reveal the patterns of input selectivity on morphologically discernable relay cell types and interneurons in the mouse lateral geniculate nucleus. MethodsWe used two sets of Scanning Blockface Electron Microscopy (SBEM) image stacks and Reconstruct software to manually reconstruct of terminal boutons and dendrite segments. First, using an unbiased terminal sampling (UTS) approach and statistical modeling, we identified the criteria for volume-based sorting of geniculate boutons into their putative origins. Geniculate terminal boutons that were sorted in retinal and non-retinal categories based on previously described mitochondrial morphology, could further be sorted into multiple subpopulations based on their bouton volume distributions. Terminals deemed non-retinal based on the morphological criteria consisted of five distinct subpopulations, including small-sized putative corticothalamic and cholinergic boutons, two medium-sized putative GABAergic inputs, and a large-sized bouton type that contains dark mitochondria. Retinal terminals also consisted of four distinct subpopulations. The cutoff criteria for these subpopulations were then applied to datasets of terminals that synapse on reconstructed dendrite segments of relay cells or interneurons. ResultsUsing a network analysis approach, we found an almost complete segregation of retinal and cortical terminals on putative X-type cell dendrite segments characterized by grape-like appendages and triads. On these cells, interneuron appendages intermingle with retinal and other medium size terminals to form triads within glomeruli. In contrast, a second, presumed Y-type cell displayed dendrodendritic puncta adherentia and received all terminal types without a selectivity for synapse location; these were not engaged in triads. Furthermore, the contribution of retinal and cortical synapses received by X-, Y- and interneuron dendrites differed such that over 60% of inputs to interneuron dendrites were from the retina, as opposed to 20% and 7% to X- and Y-type cells, respectively. ConclusionThe results underlie differences in network properties of synaptic inputs from distinct origins on geniculate cell types.
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    3D models of the leader valley using satellite & UAV imagery following the 2016 Kaikoura earthquake
    Zekkos, D.; Clark, M.; Willis, Michael J.; Athanasopoulos-Zekkos, A.; Manousakis, J.; Knoper, L.; Stahl, T.; Massey, C.; Archibald, G.; Greenwood, W.; Medwedeff, W. (2018-01-01)
    The ability to quickly, efficiently and reliably characterize changes in the landscape following an earthquake has remained a challenge for the earthquake engineering profession. The 2016 Mw7.8 Kaikoura earthquake provided a unique opportunity to document changes in topography following an earthquake on a regional scale using satellite derived high-resolution digital models. Along-track stereo satellite imagery had been collected for the pre-event topography. Satellites were tasked and collected stereo-mode post-event imagery. Both sets of images were used to create digital surface models (DSMs) of the affected area before and after the event. The procedure followed and indicative results for the Leader valley are presented with emphasis on the challenges associated with the implementation of the technique for the first time in this environment. The valley is of interest because of the variety of features it includes, i.e., the large Leader landslide, smaller landslides, stable sloping and flat ground as well as fault rupture lineaments. The open-source SETSM software is used to provide multiple DSMs. Our workflow is described and results are compared against the DSM created using Structure-from-Motion with imagery collected by Unmanned Aerial Vehicles (UAV) and aerial LIDAR. Overall, the sub-meter agreement between the DSM created using satellites and the DSM created using UAV and LIDAR datasets demonstrates viability for use in seismic studies, but features smaller than about 0.5 m are more difficult to discern.
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    A 4-year longitudinal neuroimaging study of cognitive control using latent growth modeling: developmental changes and brain-behavior associations
    Kim-Spoon, Jungmeen; Herd, Toria; Brieant, Alexis; Elder, Jacob; Lee, Jacob; Deater-Deckard, Kirby; Casas, Brooks (2021-08-15)
    Despite theoretical models suggesting developmental changes in neural substrates of cognitive control in adolescence, empirical research has rarely examined intraindividual changes in cognitive control-related brain activation using multi-wave multivariate longitudinal data. We used longitudinal repeated measures of brain activation and behavioral performance during the multi-source interference task (MSIT) from 167 adolescents (53% male) who were assessed annually over four years from ages 13 to 17 years. We applied latent growth modeling to delineate the pattern of brain activation changes over time and to examine longitudinal associations between brain activation and behavioral performance. We identified brain regions that showed differential change patterns: (1) the fronto-parietal regions that involved bilateral insula, bilateral middle frontal gyrus, left pre-supplementary motor area, left inferior parietal lobule, and right precuneus; and (2) the rostral anterior cingulate cortex (rACC) region. Longitudinal confirmatory factor analyses of the fronto-parietal regions revealed strong measurement invariance across time implying that multivariate functional magnetic resonance imaging data during cognitive control can be measured reliably over time. Latent basis growth models indicated that fronto-parietal activation decreased over time, whereas rACC activation increased over time. In addition, behavioral performance data, age-related improvement was indicated by a decreasing trajectory of intraindividual variability in response time across four years. Testing longitudinal brain-behavior associations using multivariate growth models revealed that better behavioral cognitive control was associated with lower fronto-parietal activation, but the change in behavioral performance was not related to the change in brain activation. The current findings suggest that reduced effects of cognitive interference indicated by fronto-parietal recruitment may be a marker of a maturing brain that underlies better cognitive control performance during adolescence.
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    5-year follow-up of adolescents with social anxiety disorder: Current functioning during COVID-19
    Carlton, Corinne N.; Garcia, Katelyn M.; Honaker, Makayla; Richey, John A.; Ollendick, Thomas H. (Elsevier, 2023-04)
    The present study followed-up adolescents with social anxiety disorder (SAD) during the COVID-19 pandemic, approximately 5-years following their participation in an Attention Bias Modification Training (ABMT) program (Ollendick et al., 2019). The current study aimed to evaluate current functioning and quality of life (QoL) during the emerging adulthood period. Participants included 27 young adults who completed a randomized controlled trial of ABMT and were available for follow-up. Participants filled out self-report measures of QoL and functioning and underwent a clinical interview to assess current severity of social anxiety. Clinician-rated symptoms of SAD significantly decreased from post-treatment to 5-year follow-up. Additionally, results demonstrated that social anxiety severity was significantly related to poorer self-reported physical and psychological health as well as poorer functioning with regard to social distancing fears during COVID-19. Lastly, when evaluating change in symptoms over time, increases in social anxiety severity over a 5-year period significantly predicted worsened social distancing fears during COVID-19.
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    The 750 GeV diphoton excess in unified SU(2)(L) x SU(2)(R) x SU(4) models from noncommutative geometry
    Aydemir, U.; Minic, Djordje; Sun, C.; Takeuchi, Tatsu (World Scientific, 2016-06-14)