Physical Sciences and Mathematics Commons^™

Software Architecture Improvement Through Test-Driven Development, David S. Janzen

Computer Science and Software Engineering

This research involves empirical software engineering studies applied in academic and professional settings to assess the influence of test-driven development on software quality. Particular focus is given to internal software design quality. Pedagogical implications are also examined. Initial results and the study protocol and plans will be presented.

Bounds On Authentication Systems In Query Mode, R. Safavi-Naini, P. Wild

Faculty of Informatics - Papers (Archive)

Unconditionally secure authentication codes provide information theoretic security against an adversary who observes authenticated messages and then wants to construct a fraudulent message that is acceptable by the receiver. The attack model for these codes has recently been strengthened and adaptive adversaries with oracle access have been introduced. In this paper we give an analysis of this new model and derive information theoretic bounds on the success probability and key size of the codes. Our analysis treats two games that an adversary can play: an offline attack in which the adversary is allowed to query a verification oracle and then …

Implementing A Product Lifecycle Management Solution, Christopher M. Ray

Regis University Student Publications (comprehensive collection)

Aviation Technology Group, Inc. (ATG) is currently preparing for a lengthy FAA certification process that will require detailed documentation and verification of the accuracy of all components that will belong to the aircraft being developed (the Javelin). This includes but is not limited to contracts, detailed design specifications, CAD files, test and verification results, revision tracking, and effectivity of all components used in each aircraft. The company has recently flown its first nonconforming prototype and will be building subsequent test articles, which will be used for the process of the Javelin. In order to organize all of this information and …

Potential Of Modis Evi And Surface Temperature For Directly Estimating Per-Pixel Ecosystem C Fluxes, Abdullah Rahman, Daniel A. Sims, Vicente D. Cordova, Bassil Z. El-Masri

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

We tested the potential of estimating per-pixel gross primary production (GPP) directly from the MODIS enhanced vegetation index (EVI) and respiration directly from MODIS surface temperature (MOD11). Carbon flux data were obtained from 10 eddy covariance tower sites representing a wide range of North American vegetations. The correlation between across-site tower GPP and EVI was comparable (r = 0.77) to that between tower GPP and MOD17-GPP (r = 0.73), suggesting that EVI could be used to provide reasonably accurate direct estimates of GPP on a truly per-pixel basis. There was also a strong relationship (r2 = 0.67) between respiration and …

Big Cwatsets And Hamming Code, Matthew Davis, Thomas M. Langley, Norah Mazel

Mathematical Sciences Technical Reports (MSTR)

In contrast to Lagrange's Theorem in Finite Group Theory, we show that the ratio of the largest proper cwatset of degree d to the size of binary d-space approaches 1 as d approaches infinity. We show how to explicitly construct large cwatsets as cosets of Hamming Codes, and discuss many open questions that arise.

Population Intervention Models In Causal Inference, Alan E. Hubbard, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Marginal structural models (MSM) provide a powerful tool for estimating the causal effect of a] treatment variable or risk variable on the distribution of a disease in a population. These models, as originally introduced by Robins (e.g., Robins (2000a), Robins (2000b), van der Laan and Robins (2002)), model the marginal distributions of treatment-specific counterfactual outcomes, possibly conditional on a subset of the baseline covariates, and its dependence on treatment. Marginal structural models are particularly useful in the context of longitudinal data structures, in which each subject's treatment and covariate history are measured over time, and an outcome is recorded at …

Computing For Human Experience And Wellness, Amit P. Sheth

Kno.e.sis Publications

No abstract provided.

Gauss-Seidel Estimation Of Generalized Linear Mixed Models With Application To Poisson Modeling Of Spatially Varying Disease Rates, Subharup Guha, Louise Ryan

Harvard University Biostatistics Working Paper Series

Generalized linear mixed models (GLMMs) provide an elegant framework for the analysis of correlated data. Due to the non-closed form of the likelihood, GLMMs are often fit by computational procedures like penalized quasi-likelihood (PQL). Special cases of these models are generalized linear models (GLMs), which are often fit using algorithms like iterative weighted least squares (IWLS). High computational costs and memory space constraints often make it difficult to apply these iterative procedures to data sets with very large number of cases.

This paper proposes a computationally efficient strategy based on the Gauss-Seidel algorithm that iteratively fits sub-models of the GLMM …

Deploying The Digital Aid Framework: A Non-Traditionalist View Of The Intrinsic Nature Of E-Business Solutions For Humanitarian Relief, J. Sargent

Faculty of Informatics - Papers (Archive)

Commercial Fortune 500 companies come readily to mind in any discussion or categorization of global e- Businesses. However, organizations within the international humanitarian relief sector such as UNHCR, the UN’s refugee agency, are consistently over-looked or underestimated as global ‘e-Biz’ players. This paper acts as a primer for the principles of e-Business for humanitarian relief by presenting deployment examples of traditional e-Business processes in non-traditional contexts; refugee and Internally Displaced Person (IDP) crises. Preliminary research indicates such illustrated indicative examples detailed in the Digital Aid Framework have potential for easy adoption and integration into future humanitarian (refugee & IDP) relief …

Humancentric Applications Of Precise Location Based Services, L. Perusco, Katina Michael

Faculty of Informatics - Papers (Archive)

This paper focuses on the growing need to consider the implications of humancentric applications of precise location based services (LBS). As newer positioning technologies are introduced into the market with a greater level of location accuracy, and existing technologies are utilized in an integrated fashion to overcome limitations, issues pertaining to the use and potential misuse of location information rise to the fore. The scenario planning methodology provides a robust approach within which to consider future possibilities based on current market developments. To this end, document and content analysis play an important role in the collection of facts used to …

Specific Heat And Thermodynamic Properties Of Metallic Systems: Instrumentation And Analysis, Brian E. Lang

Theses and Dissertations

A small-scale adiabatic calorimeter has been constructed as part of a larger project to study nano-particles and to facilitate specific heat measurements on samples where it is difficult to obtain enough material to run on the current large-scale adiabatic apparatus. This calorimeter is designed to measure sample sizes of less than 0.8 cc over a temperature range from 13 K to 350 K. Specific heat results on copper, sapphire, and benzoic acid show the accuracy of the measurements to be better than ±0.4% for temperatures higher than 50 K. The reproducibility of these measurements is generally better than ±0.25%. Experimental …

Austin Creek And Beaver Creek Sampling Project, Robin A. Matthews, Michael Hilles, Joan Vandersypen

Lake Whatcom Other Reports

Beaver Creek and Austin Creek were sampled intensively on November 20, 2004 to measure temperature, dissolved oxygen, turbidity, total nitrogen, total phosphorus, total suspended solids, and fecal coliforms. The objective was to assess the amount of variability that can be expected for water quality measurements collected from these creeks at different times during the day and in different locations within the Austin Creek and Beaver Creek watersheds.

Five New Multicomponent Planetary Systems, Steve Vogt, R. Paul Butler, Geoffrey W. Marcy, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason T. Wright, John A. Johnson

Information Systems and Engineering Management Research Publications

We report Doppler measurements for six nearby G- and K-type main-sequence stars that show multiple low-mass companions, at least one of which has planetary mass. One system has three planets, the fourth triple-planet system known around a normal star, and another has an extremely low minimum mass of 18 M⊕. HD 128311 (K0 V) has two planets (one previously known) with minimum masses (M sin i) of 2.18MJ and 3.21MJ and orbital periods of 1.26 and 2.54 yr, suggesting a possible 2 : 1 resonance. For HD 108874 (G5 V), the velocities reveal two planets (one previously known) having minimum …

Gateway Battered Women's Services Website Development Project, Lena Alhusseini

Regis University Student Publications (comprehensive collection)

The development of a website for a non-profit organization concerned with domestic violence is described, including the needs assessment, methodology, implementation, finalization, and evaluation. Gateway Battered Women's Services (GBWS), in Aurora, Colorado, provides shelter, advocacy, and counseling for women and children affected by domestic violence. Its goal is the elimination of personal and societal violence against all women and children through education, support services, and promoting social change within the community. GBWS needed a web presence, a database, and an online counseling service to distribute information on domestic violence to potential clients and volunteers and to solicit donations. A questionnaire …

Noao Fundamental Plane Survey. Ii. Age And Metallicity Along The Red Sequence From Line‐Strength Data, Jenica E. Nelan, Russell J. Smith, Michael J. Hudson, Gary A. Wegner

Dartmouth Scholarship

We present spectroscopic line-strength data for 4097 red-sequence galaxies in 93 low-redshift galaxy clusters and use these to investigate variations in average stellar populations as a function of galaxy mass. Our analysis includes an improved treatment of nebular emission contamination, which affects ~10% of the sample galaxies. Using the stellar population models of D. Thomas and collaborators, we simultaneously fit 12 observed line-strength-σ relations in terms of common underlying trends of age, [Z/H] (total metallicity), and [α/Fe] (α-element enhancement). We find that the observed line-strength-σ relations can be explained only if higher mass red-sequence galaxies are, on average, …

Deep Photometry Of The Globular Cluster M5: Distance Estimates From White Dwarf And Main-Sequence Stars, Andrew C. Layden, Ted Von Hippel, Et Al.

Publications

We present deep VI photometry of stars in the globular cluster M5 (NGC 5904) based on images taken with the Hubble Space Telescope. The resulting color-magnitude diagram reaches below V ≈27 mag, revealing the upper 2–3 mag of the white dwarf cooling sequence and main-sequence stars 8 mag and more below the turnoff. We fit the main sequence to subdwarfs of known parallax to obtain a true distance modulus of (m ̶ M )₀ = 14:45 ± 0:11 mag. A second distance estimate based on fitting the cluster white dwarf sequence to field white dwarfs with known parallax …

Emanager - Cdo Made Simple, Solomon Vedaprakash

Regis University Student Publications (comprehensive collection)

The eManager application integrates the existing enforcement systems and MS Exchange Server 2003. The application exploits the benefits of CDO, ADO, LDAP, ADSI, XML and COM technologies. The application explicates the integration and utilization of CDO using VC++ programming language. It illustrates how CDO can be implemented effectively in various circumstances while maintaining uncomplicated application design and solutions. It demonstrates how CDO and ADO complements each other and interacts with other Windows artifacts such as ADSI, LDAP and Active Directory. The application implements the COM methodology that establishes the COM events using connection points and sinks. The integration and management …

Notes On (Twisted) Lattice Supersymmetry, Simon Catterall

Physics - All Scholarship

We describe a new approach to the problem of putting supersymmetric theories on the lattice. The basic idea is to discretize a {\it twisted} formulation of the supersymmetric theory. For certain theories with extended supersymmetry these twisted formulations contain only integer spin fields. The twisting exposes a scalar nilpotent supercharge which generates an exact lattice symmetry. We gives examples from quantum mechanics, sigma models and Yang-Mills theories.

Designed Extension Of Survival Studies: Application To Clinical Trials With Unrecognized Heterogeneity, Yi Li, Mei-Chiung Shih, Rebecca A. Betensky

Harvard University Biostatistics Working Paper Series

It is well known that unrecognized heterogeneity among patients, such as is conferred by genetic subtype, can undermine the power of randomized trial, designed under the assumption of homogeneity, to detect a truly beneficial treatment. We consider the conditional power approach to allow for recovery of power under unexplained heterogeneity. While Proschan and Hunsberger (1995) confined the application of conditional power design to normally distributed observations, we consider more general and difficult settings in which the data are in the framework of continuous time and are subject to censoring. In particular, we derive a procedure appropriate for the analysis of …

Computational Techniques For Spatial Logistic Regression With Large Datasets, Christopher J. Paciorek, Louise Ryan

Harvard University Biostatistics Working Paper Series

In epidemiological work, outcomes are frequently non-normal, sample sizes may be large, and effects are often small. To relate health outcomes to geographic risk factors, fast and powerful methods for fitting spatial models, particularly for non-normal data, are required. We focus on binary outcomes, with the risk surface a smooth function of space. We compare penalized likelihood models, including the penalized quasi-likelihood (PQL) approach, and Bayesian models based on fit, speed, and ease of implementation.

A Bayesian model using a spectral basis representation of the spatial surface provides the best tradeoff of sensitivity and specificity in simulations, detecting real spatial …

Noncompact Manifolds With Nonnegative Ricci Curvature, William Wylie

Mathematics - All Scholarship

Let (M,d) be a metric space. For 0

Distributions Of Charged Hadrons Associated With High Transverse Momentum Particles In Pp And Au+Au Collisions At √SNn = 200 Gev, J. Adams, C. Adler, M.M. Aggarwal, Z. Ahammed, J. Amonett, B.D. Anderson, D. Arkhipkin, G.S. Averichev, S.K. Badyal, J. Balewski, O. Barannikova, L.S. Barnby, J. Baudot, S. Bekele, V.V. Belaga, R. Bellwied, J. Berger, B.I. Bezverkhny, S. Bhardwaj, A.K. Bhati, H. Bichsel, A. Billmeier, L.C. Bland, C.O. Blyth, B.E. Bonner, M. Botje, A. Boucham, A.V. Brandin, A. Bravar, R.V. Cadman, X.Z. Cai, H. Caines, M. Calderón De La Barca Sánchez, J. Carroll, J. Castillo, D. Cebra, P. Chaloupka, S. Chattopadhyay, H.F. Chen, Y. Chen, S.P. Chernenko, M. Cherney, A. Chikanian, W. Christie, J.P. Coffin, T.M. Cormier, J.G. Cramer, H.J. Crawford, D. Das, S. Das, A.A. Derevschikov, L. Didenko, T. Dietel, W.J. Dong, X. Dong, J.E. Draper, F. Du, A.K. Dubey, V.B. Dunin, J.C. Dunlop, M.R. Dutta Mazumdar, V. Eckardt, L.G. Efimov, V. Emelianov, J. Engelage, G. Eppley, B. Erazmus, M. Estienne, P. Fachini, V. Faine, J. Faivre, R. Fatemi, K. Filimonov, P. Filip, E. Finch, Y. Fisyak, D. Flierl, K.J. Foley, J. Fu, C.A. Gagliardi, N. Gagunashvili, J. Gans, M.S. Ganti, L. Gaudichet, F. Geurts, V. Ghazikhanian, P. Ghosh, J.E. Gonzalez, O. Grachov, O. Grebenyuk, S. Gronstal, D. Grosnick, S.M. Guertin, A. Gupta, T.D. Gutierrez, T.J. Hallman, A. Hamed, D. Hardtke, J.W. Harris, M. Heinz, T.W. Henry, S. Hepplemann, T. Herston, B. Hippolyte, A. Hirsch, E. Hjort, G.W. Hoffmann, M. Horsley, H.Z. Huang, S.L. Huang, E. Hughes, T.J. Humanic, G. Igo, A. Ishihara, P. Jacobs, W.W. Jacobs, M. Janik, H. Jiang, I. Johnson, P.G. Jones, E.G. Judd, S. Kabana, M. Kaplan, D. Keane, V.Yu. Khodyrev, J. Kiryluk, A. Kisiel, J. Klay, S.R. Klein, A. Klyachko, D.D. Koetke, T. Kollegger, M. Kopytine, L. Kotchenda, A.D. Kovalenko, M. Kramer, P. Kravtsov, V.I. Kravtsov, K. Krueger, C. Kuhn, A.I. Kulikov, A. Kumar, G.J. Kunde, C.L. Kunz, R. Kh. Kutuev, A.A. Kuznetsov, M.A.C. Lamont, J.M. Landgraf, S. Lange, B. Lasiuk, F. Laue, J. Lauret, A. Lebedev, R. Lednicky, M.J. Levine, C. Li, Q. Li, S.J. Lindenbaum, M.A. Lisa, F. Liu, L. Liu, Z. Liu, Q.J. Liu, T. Ljubicic, W.J. Llope, H. Long, R.S. Longacre, M. Lopez-Noriega, W.A. Love, T. Ludlam, D. Lynn, J. Ma, Y.G. Ma, D. Magestro, S. Mahajan, L.K. Mangotra, D.P. Mahapatra, R. Majka, R. Manweiler, S. Margetis, C. Markert, L. Martin, J.N. Marx, H.S. Matis, Yu.A. Matulenko, C.J. Mcclain, T.S. Mcshane, F. Meissner, Yu. Melnick, A. Meschanin, M.L. Miller, Z. Milosevich, N.G. Minaev, C. Mironov, A. Mischke, D.K. Mishra, J. Mitchell, B. Mohanty, L. Molnar, C.F. Moore, M.J. Mora-Corral, D.A. Morozov, V. Morozov, M.M. De Moura, M.G. Munhoz, B.K. Nandi, S.K. Nayak, T.K. Nayak, J.M. Nelson, P.K. Netrakanti, V.A. Nikitin, L.V. Nogach, B. Norman, S.B. Nurushev, G. Odyniec, A. Ogawa, V. Okorokov, M. Oldenburg, D. Olson, G. Paic, S.K. Pal, Y. Panebratsev, S.Y. Panitkin, A.I. Pavlinov, T. Pawlak, T. Peitzmann, V. Perevoztchikov, C. Perkins, W. Peryt, V.A. Petrov, S.C. Phatak, R. Picha, M. Planinic, J. Pluta, N. Porile, J. Porter, A.M. Poskanzer, M. Potekhin, E. Potrebenikova, B.V.K.S. Potukuchi, D. Prindle, C. Pruneau, J. Putschke, G. Rai, G. Rakness, R. Raniwala, S. Raniwala, O. Ravel, R.L. Ray, S.V. Razin, D. Reichhold, J.G. Reid, G. Renault, F. Retiere, A. Ridiger, H.G. Ritter, J.B. Roberts, O.V. Rogachevskiy, J.L. Romero, A. Rose, C. Roy, L. Ruan, R. Sahoo, I. Sakrejda, S. Salur, J. Sandweiss, I. Savin, J. Schambach, R.P. Scharenberg, N. Schmitz, L.S. Schroeder, K. Schweda, J. Seger, P. Seyboth, E. Shahaliev, M. Shao, W. Shao, M. Sharma, K.E. Shestermanov, S.S. Shimanskiy, R.N. Singaraju, F. Simon, G. Skoro, N. Smirnov, R. Snellings, G. Sood, P. Sorensen, J. Sowinski, J. Speltz, H.M. Spinka, B. Srivastava, T.D.S. Stanislaus, R. Stock, A. Stolpovsky, M. Strikhanov, B. Stringfellow, C. Struck, A.A.P. Suaide, E. Sugarbaker, C. Suire, M. Šumbera, B. Surrow, T.J.M. Symons, A. Szanto De Toledo, P. Szarwas, A. Tai, J. Takahashi, A.H. Tang, D. Thein, J.H. Thomas, S. Timoshenko, M. Tokarev, M.B. Tonjes, T.A. Trainor, S. Trentalange, R.E. Tribble, O.D. Tsai, T. Ullrich, D.G. Underwood, G. Van Buren, A.M. Vander Molen, R. Varma, I.M. Vasilevski, A.N. Vasiliev, R. Vernet, S.E. Vigdor, Y.P. Viyogi, S.A. Voloshin, M. Vznuzdaev, W.T. Waggoner, F. Wang, G. Wang, X.L. Wang, Y. Wang, Z.M Wang, H. Ward, J.W. Watson, J.C. Webb, R. Wells, G.D. Westfall, C. A. Whitten Jr., H. Wieman, R. Willson, S.W. Wissink, R. Witt, J. Wood, J. Wu, N. Xu, Z. Xu, Z.Z. Xu, E. Yamamoto, P. Yepes, V.I. Yurevich, B. Yuting, Y.V. Zanevski, H. Zhang, W.M. Zhang, Z.P. Zhang, Z.P. Zhaomin, Z.P. Zizong, P.A. Żołnierczuk, R. Zoulkarneev, Y. Zoulkarneeva, A.N. Zubarev

Physics

Charged hadrons in 0.15⊥<4  GeV/c associated with particles of p^trig_⊥>4  GeV/c are reconstructed in pp and Au+Au collisions at √s_NN=200  GeV. The associated multiplicity and p⊥magnitude sum are found to increase from pp to central Au+Au collisions. The associated p_⊥distributions, while similar in shape on the nearside, are significantly softened on the awayside in central Au+Au relative to pp and not much harder than that of inclusive hadrons. The results, consistent with jet quenching, suggest that the awayside fragments approach equilibration with the medium traversed.

Nicholas Reactions With Carboxylic Acids For The Synthesis Of Macrocyclic Diolides, Kevin M. Shea, Kristina D. Closser, Miriam M. Quintal

Chemistry: Faculty Publications

We have developed a new strategy for the preparation of diolides using a cascade of Nicholas reactions. The carboxylic acid nucleophiles in these reactions are virtually unstudied participants in transformations of this type. Using this methodology, a 16-membered cobalt-complexed cyclic diyne is available in 28% yield over eight steps (an average of 85% per step). We can also easily access the uncomplexed diolide in one additional step.

Impact Of Bythotrephes Invasion On Zooplankton Communities In Acid-Damaged And Recovered Lakes On The Boreal Shield, Angela L. Strecker, Shelley E. Arnott

Environmental Science and Management Faculty Publications and Presentations

Invasive species introductions into freshwater ecosystems have had a multitude of effects on aquatic communities. Few studies, however, have directly compared the impact of an invader on communities with contrasting structure. Historically high levels and subsequent reductions of acid deposition have produced landscapes of lakes of varying acidity and zooplankton communitystructure. We conducted a 30-day enclosure experiment in Killarney Provincial Park, Ontario, Canada, to test the effects ofBythotrephes longimanus, an invasive invertebrate predator, on two contrasting zooplankton communities at different stages of recovery from acidification: recovered and acid damaged. Bythotrephes significantly decreased zooplankton biomass and abundance in both communities but …

Dirac-Kähler Fermions And Exact Lattice Supersymmetry, Simon Catterall

Physics - All Scholarship

We discuss a new approach to putting supersymmetric theories on the lattice. The basic idea is to start from a {\it twisted} formulation of the underlying supersymmetric theory in which the fermions are represented as grassmann valued antisymmetric tensor fields. The original supersymmetry algebra is replaced by a twisted algebra which contains a scalar nilpotent supercharge Q. Furthermore the action of the theory can then be written as the Q-variation of some function. The case of {\cal N}=2 super Yang-Mills theory in two dimensions is discussed in some detail. We then present our proposal for discretizing this theory and derive …

Lattice Formulation Of {\Cal N}=4 Super Yang-Mills Theory, Simon Catterall

Physics - All Scholarship

We construct a lattice action for {\cal N}=4 super Yang-Mills theory in four dimensions which is local, gauge invariant, free of spectrum doubling and possesses a single exact supersymmetry. Our construction starts from the observation that the fermions of the continuum theory can be mapped into the component fields of a single real anticommuting Kahler-Dirac field. The original supersymmetry algebra then implies the existence of a nilpotent scalar supercharge Q and a corresponding set of bosonic superpartners. Using this field content we write down a Q-exact action and show that, with an appropriate change of variables, it reduces to a …

Assessing “Discover Mojave” Instrument Development And Analysis: Final Report, Lori Olafson, Gregory Schraw, Michelle L. Weibel

Reports (DM)

We developed curriculum and a comprehensive assessment plan to determine whether hands-on outdoor recreation events promote knowledge, attitudes, and performance among at-risk urban children. Knowledge, attitude, and performance assessments were developed, refined and conducted through various stages based on cultural and language barriers as well a variety of age groups participating within the events. Findings revealed that knowledge, attitudes, and performance increased substantially as a result of participating in the outdoor recreation events. We conclude that the implementation and assessment of the program is strong. We also make several recommendations for future programs.

Is It The End Of Barcodes In Supply Chain Management? , Luke Mccathie, Katina Michael

Faculty of Informatics - Papers (Archive)

Barcode is a mature automatic identification (auto-ID) technology that has been used in supply chain management (SCM) for several decades. Such has been the domination of the auto-ID technique that it has pervaded all facets of SCM, from item-level identification to transportation applications. It has enjoyed free reign especially in the retail sector. However, recently radio-frequency identification (RFID) has been considered a rival technology, more superior in terms of its power to store and update information instantaneously, and non-line of sight (nLoS) ability to be read. Yet RFID is more costly and for the present barcode is still the most …

Semiconductor Nanowire Laser And Nanowire Waveguide Electro-Optic Modulators, Andrew B. Greytak, Carl J. Barrelet, Yat Li, Charles M. Lieber

Faculty Publications

Electric field modulation of visible and ultraviolet nanoscale lasers consisting of single CdS or GaN nanowires has been achieved using integrated, microfabricated electrodes. Modulation of laser emission intensity is achieved with no detectable change in the laser wavelength. The devices can also be operated below the lasing threshold to modulate the intensity of light propagating within the nanowire waveguide. Studies of the electric field dependence in devices of varied geometry indicate that modulation is due to an electroabsorption mechanism. These findings expand opportunities for multicolor, nanowire-based photonic devices and circuits.

Grain Boundary Scars On Spherical Crystals, Mark Bowick, Thomas Einert, Peter Lipowsky, Jorg Schilling, Andreas R. Bausch

Physics - All Scholarship

We present an experimental system suitable for producing spherical crystals and for observing the distribution of lattice defects (disclinations and dislocations) on a significant fraction (50%) of the sphere. The introduction of fluorescently labeled particles enables us to determine the location and orientation of grain boundary scars. We find that the total number of scars and the number of excess dislocations per scar agree with theoretical predictions and that the geometrical centers of the scars are roughly positioned at the vertices of an icosahedron.