Physical Sciences and Mathematics Commons^™

Altruistic Task Allocation Despite Unbalanced Relationships Within Multi-Robot Communities, Ryan Morton, George A. Bekey, Christopher M. Clark

Computer Science and Software Engineering

Typical Multi-Robot Systems consist of robots cooperating to maximize global fitness functions. However, in some scenarios, the set of interacting robots may not share common goals and thus the concept of a global fitness function becomes invalid. This work examines Multi-Robot Communities(MRC), in which individual robots have independent goals. Within the MRC context, we present a task allocation architecture that optimizes individual robot fitness functions over long time horizons using reciprocal altruism.

Previous work has shown that reciprocating altruistic relationships can evolve between two willing robots, using market-based task auctions, while still protecting against selfish robots aiming to exploit …

Real-World Performance Of Current Proactive Multi-Hop Mesh Protocols, M. Abolhasan, Brett Hagelstein, Jerry Chun-Ping Wang

Faculty of Informatics - Papers (Archive)

The proliferation of mesh or ad hoc network protocols has lead to a push for protocol standardisation. While there are a number of both open-source and proprietary mesh routing protocols being developed, there is only a small amount of literature available that shows relative strengths and weaknesses of different protocols. This paper investigates the performance of a number of available routing protocols using a real-world testbed. Three routing protocols - Optimised Link State Routing (OLSR), Better Approach To Mobile Ad hoc Network (B.A.T.M.A.N.) and BABEL - were chosen for this study. Our investigations focus on the multi-hopping performance and the …

Trophic Structure Of The Northwest Hawaiian Islands And Resident Monk Seals (Monachus Schaundslandi) During The Twentieth Century, Nina M. Thompson, Amy Hirons, Charles W. Potter, Charles Littnan

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

The Hawaiian monk seal (Monachus schauinslandi) is an endangered species only found within the Hawaiian Archipelago. The majority of the breeding population for this seal is located around six islands in the Northwest Hawaiian Island chain (NWHI). Overall, both juvenile and adult seals have a wide range in δ¹³C and δ¹⁵N from 1912-2006 (δ¹³C: -12.5‰; δ¹⁵N: 12.6‰). Seals in the northern NWHI were enriched in δ¹³C by nearly 2‰ and depleted in δ¹⁵N by nearly 6‰ during the 96 years. Meanwhile, seals within the middle and …

Dust And The Type Ii-Plateau Supernova 2004et, R. Kotak, W. P. S. Meikle, D. Farrah, C. L. Gerardy, R. J. Foley, S. D. Van Dyk, C. Fransson, P. Lundqvist, J. Sollerman, R. Fesen

Dartmouth Scholarship

We present mid-infrared (MIR) observations of the Type II-plateau supernova (SN) 2004et, obtained with the Spitzer Space Telescope between 64 and 1406 days past explosion. Late-time optical spectra are also presented. For the period 300-795 days past explosion, we argue that the spectral energy distribution (SED) of SN 2004et comprises (1) a hot component due to emission from optically thick gas, as well as free-bound radiation; (2) a warm component due to newly formed, radioactively heated dust in the ejecta; and (3) a cold component due to an IR echo from the interstellar-medium dust of the host galaxy, NGC 6946. …

Stability And Error Estimates For Vector Field Interpolation And Decomposition On The Sphere With Rbfs, Edward J. Fuselier, Grady Wright

Mathematics Faculty Publications and Presentations

A new numerical technique based on radial basis functions (RBFs) is presented for fitting a vector field tangent to the sphere, S², from samples of the field at "scattered" locations on S². The method naturally provides a way to decompose the reconstructed field into its individual Helmholtz–Hodge components, i.e., into divergence-free and curl-free parts, which is useful in many applications from the atmospheric and oceanic sciences (e.g., in diagnosing the horizontal wind and ocean currents). Several approximation results for the method will be derived. In particular, Sobolevtype error estimates are obtained for both the interpolant and …

Type-1.5 Superconducting State From An Intrinsic Proximity Effect In Two-Band Superconductors, Egor Babaev, Johan Carlstrom, Martin Speight

Egor Babaev

We show that in multiband superconductors even small interband proximity effect can lead to a qualitative change in the interaction potential between superconducting vortices by producing long-range intervortex attraction. This type of vortex interaction results in unusual response to low magnetic fields leading to phase separation into domains of a two-component Meissner states and vortex droplets.

Magnetoelastic Coupling Through The Antiferromagnet-To-Ferromagnet Transition Of Quasi-Two-Dimensional [Cu(Hf2)(Pyz)(2)]Bf4 Using Infrared Spectroscopy, J L. Musfeldt, L I. Vergara, T V. Brinzari, C Lee, L C. Tung, J Kang, Y J. Wang, J A. Schlueter, Jamie L. Manson, M H. Whangbo

Chemistry and Biochemistry Faculty Publications

We investigated magnetoelastic coupling through the field-driven transition to the fully polarized magnetic state in quasi-two-dimensional [Cu(HF2)(pyz)(2)]BF4 by magnetoinfrared spectroscopy. This transition modifies out-of-plane ring distortion and bending vibrational modes of the pyrazine ligand. The extent of these distortions increases with the field, systematically tracking the low-temperature magnetization. These distortions weaken the antiferromagnetic spin exchange, a finding that provides important insight into magnetic transitions in other copper halides.

Observation Of Giant Positive Magnetoresistance In A Cooper Pair Insulator., H Q. Nguyen, Shawna M. Hollen, M D. Stewart Jr, J Shainline, Aijun Yin, J M. Xu, J M. Valles

Physics & Astronomy

Ultrathin amorphous Bi films, patterned with a nanohoneycomb array of holes, can exhibit an insulating phase with transport dominated by the incoherent motion of Cooper pairs (CP) of electrons between localized states. Here, we show that the magnetoresistance (MR) of this Cooper pair insulator (CPI) phase is positive and grows exponentially with decreasing temperature T, for T well below the pair formation temperature. It peaks at a field estimated to be sufficient to break the pairs and then decreases monotonically into a regime in which the film resistance assumes the T dependence appropriate for weakly localized single electron transport. We …

Gravity Wave Ducting In The Upper Mesosphere And Lower Thermosphere Duct System, R. L. Walterscheid, Michael P. Hickey Ph.D.

Publications

We report on a numerical study of gravity wave propagation in a pair of ducts located in a region where dramatic changes in the airglow most likely associated with ducted wave trains are observed. We examine ducting in an upper mesosphere inversion (INV) and an always present lower thermosphere stable layer (LTD) for a range of phase speeds and horizontal wavelengths characteristic of ducting events. We analyze the propagation and modal structure of ducted waves for backgrounds with increasing realism, starting with a climatological temperature profile where only the LTD is present. In succession, we add the INV based on …

Leading Students To Investigate Diffusion As A Model Of Brine Shrimp Movement, Brynja R. Kohler, Rebecca J. Swank, James W. Haefner, James A. Powell

Mathematics and Statistics Faculty Publications

Integrating experimental biology laboratory exercises with mathematical modeling can be an effective tool to enhance mathematical relevance for biologists and to emphasize biological realism for mathematicians. This paper describes a lab project de-signed for and tested in an undergraduate biomathematics course. In the lab, students follow and track the paths of individual brine shrimp confined in shallow salt water in a Petri dish. Students investigate the question, “Is the movement well characterized as a 2-dimensional random walk?” Through open, but directed discussions, students derive the corresponding partial differential equation, gain an understanding of the solution behavior, and model brine shrimp …

The Lambert W Function And Quantum Statistics, Sree Ram Valluri, M. Gil, D. J. Jeffrey, Shantanu Basu

Physics and Astronomy Publications

We present some applications of the Lambert W function (W function) to the formalism of quantum statistics (QS). We consider the problem of finding extrema in terms of energy for a general QS distribution, which involves the solution of a transcendental equation in terms of the W function. We then present some applications of this formula including Bose–Einstein systems in d dimensions, Maxwell–Boltzmann systems, and black body radiation. We also show that for the appropriate parameter values, this formula reduces to an analytic expression in connection with Wien’s displacement law that was found in a previous study. In addition, we …

Quasi-Least Squares With Mixed Linear Correlation Structures, Jichun Xie, Justine Shults, Jon Peet, Dwight Stambolian, Mary F. Cotch

UPenn Biostatistics Working Papers

Quasi-least squares (QLS) is a two-stage computational approach for estimation of the correlation parameters in the framework of generalized estimating equations (GEE). We prove two general results for the class of mixed linear correlation structures: namely, that the stage one QLS estimate of the correlation parameter always exists and is feasible (yields a positive definite estimated correlation matrix) for any correlation structure, while the stage two estimator exists and is unique (and therefore consistent) with probability one, for the class of mixed linear correlation structures. Our general results justify the implementation of QLS for particular members of the class of …

Leucothoidae, Kristine N. White, James Darwin Thomas

Marine & Environmental Sciences Faculty Articles

Four genera and 17 species of leucothoids, the majority of these belonging to the genus Leucothoe, are herein reported from the Great Barrier Reef. Fifteen species are new to science and only Anamixis bazimut has been previously reported from the Great Barrier Reef.

Optimizing The Signal-To-Noise Ratio Of A Beam-Deflection Measurement With Interferometric Weak Values, David J. Starling, P. Ben Dixon, Andrew N. Jordan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

The amplification obtained using weak values is quantified through a detailed investigation of the signal-to-noise ratio for an optical beam-deflection measurement. We show that for a given deflection, input power and beam radius, the use of interferometric weak values allows one to obtain the optimum signal-to-noise ratio using a coherent beam. This method has the advantage of reduced technical noise and allows for the use of detectors with a low saturation intensity. We report on an experiment which improves the signal-to-noise ratio for a beam-deflection measurement by a factor of 54 when compared to a measurement using the same beam …

Experimental And Theoretical Study Of The Structures And Enthalpies Of Formation Of The Synthetic Reagents 1,3-Thiazolidine-2-Thione And 1,3-Oxazolidine-2-Thione., María Victoria Roux, Manuel Temprado, Pilar Jiménez, Concepción Foces-Foces, Rafael Notario, Archana R. Parameswar, Alexei V. Demchenko, James S. Chickos, Carol A. Deakyne, Alicia K. Ludden, Joel F. Liebman

James Chickos

No abstract provided.

Collaborative Research: The Response Of Lakes To Disturbance And Climate Change: Calibrating Sedimentary Records To Test The Landscape Position Concept, Jasmine E. Saros

University of Maine Office of Research Administration: Grant Reports

Landscape disturbance and climate change affect lakes in proportion to their contact with ground water, sometimes resulting in different responses in neighboring lakes. This project develops methods for reconstructing past water chemistry and food webs of lakes. The biological and chemical deposits in surface sediment samples will be compared with the water in 62 modern lakes. The resulting relationships will be tested by comparing sediment cores with 24 years of observations from the North Temperate Lakes Long Term Ecological Research (NTL-LTER) site. The methods will then be used to reconstruct 150 years of history for several lakes, adding perspective to …

Photodisintegration Of 4He Into P + T, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

The two-body photodisintegration of ⁴He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid ⁴He target. This is the first measurement of the photodisintegration of ⁴He above 0.4 GeV. The differential cross sections for the γ ⁴He → pt reaction were measured as a function of photon-beam energy and proton-scattering angle and are compared with the latest model calculations by J.M. …

Absolute Nitrogen Atom Density Measurements By Two-Photon Laser-Induced Fluorescence Spectroscopy In Atmospheric Pressure Dielectric Barrier Discharges Of Pure Nitrogen, Et-Touhami Es-Sebbar, Christian Sarra-Bournet, Nicolas Naudé, Françoise Massines, Nicolas Gherardi

Dr. Et-touhami Es-sebbar

In this paper, two-photon absorption laser induced fluorescence spectroscopy is used to follow the nitrogen atom density in flowing dielectric barrier discharges fed with pure nitrogen and operating at atmospheric pressure. Two different dielectric barrier discharge regimes are investigated: the Townsend regime, which is homogeneous although operating at atmospheric pressure, and the more common filamentary regime. In both regimes, densities as high as 3x1014 /cm3 are detected. However, the N atoms kinetic formation depends on the discharge regime. The saturation level is reached more rapidly with a filamentary discharge. For a given discharge regime, the N atom density depends strongly …

Josephson Scanning Tunneling Microscopy: A Local And Direct Probe Of The Superconducting Order Parameter, Richard P. Barber Jr., Hikari Kimura, Shuhei Ono, Yoichi Ando, Robert C. Dynes

Physics

Direct measurements of the superconducting superfluid on the surface of vacuum-cleaved Bi2Sr2CaCu2O8+ BSCCO samples are reported. These measurements are accomplished via Josephson tunneling into the sample using a scanning tunneling microscope STM equipped with a superconducting tip. The spatial resolution of the STM of lateral distances less than the superconducting coherence length allows it to reveal local inhomogeneities in the pair wave function of the BSCCO. Instrument performance is demonstrated first with Josephson measurements of Pb films followed by the layered superconductor NbSe2. The relevant measurement parameter, the Josephson ICRN product, is discussed within the context of both BCS superconductors …

Development And Comparison Of Methods For Measuring Directional Sound Arrivals In Rooms, Brian Trevor Thornock

Theses and Dissertations

In room acoustics, the directional information of sound arrivals at a listening location can be used to diagnose the origins of problematic reflections so offending surfaces or other features can be properly treated. It can also be used for other purposes, including the study of psychoacoustic indicators. Many methods have been developed in the past to derive directional information, but despite their benefits, each has had significant drawbacks that have necessitated further research into their properties and development of an improved method. This thesis presents a review of past methods, their benefits and shortcomings. It discusses many theoretical and practical …

Us Itase Glaciochemistry Phase 2: East Antarctica, Paul Mayewski

University of Maine Office of Research Administration: Grant Reports

This award supports a project to undertake glaciochemical investigations of the Ross Sea Embayment Drainage System, and portions of Wilkes Land for purposes of understanding annual to multi-centennial scale climate variability. The glaciochemical data that will be collected will contribute to the U.S. component of the International Trans-Antarctic Scientific Expedition and will occur over a period of two years on an overland traverse that will begin at Taylor Dome in Northern Victoria Land and travel to the South Pole. This data, along with similar information collected on a series of earlier traverse in West Antarctica, will contribute to providing an …

A Science Management Office For The United States Component Of The International Trans Antarctic Expedition (Us Itase Smo) - A Collaborative Program Of Research From Taylor Dome To, Paul Mayewski

University of Maine Office of Research Administration: Grant Reports

This award supports the science management office (SMO) for a series of collaborative science proposals that are part of the U.S. contribution to the International Trans-Antarctic Scientific Expedition (US ITASE). It supports the science administration and the coordination of logistics needed in order to accomplish the research. The SMO will work with the Antarctic support contractor to coordinate field operations for the traverse platform so that US ITASE can undertake a series of scientific traverses in the region from Taylor Dome, in Northern Victoria Land to South Pole (NVL-SP) inclusive of interior portions of the East Antarctic plateau such as …

Depositional Ice Nucleation On Solid Ammonium Sulfate And Glutaric Acid Particles, K. J. Baustian, M. E. Wise, M. A. Tolbert

CUP Faculty Research

Heterogeneous ice nucleation on solid ammonium sulfate and solid amorphous glutaric acid particles was studied using optical microscopy and Raman spectroscopy. Optical microscopy was used to detect selective nucleation events as water vapor was slowly introduced into an environmental sample cell. Particles that nucleated ice were dried via sublimation and examined in detail using Raman spectroscopy. Depositional ice nucleation occurred preferentially on just a few ammonium sulfate and glutaric acid particles in each sample. For freezing temperatures between 214 K and 235K average ice saturation ratios of S=1.10±0.07 for solid ammonium sulfate and S=1.39±0.16 for solid amorphous glutaric …

Reexamine Structures And Relative Stability Of Medium-Sized Silicon Clusters: Low-Lying Endohedral Fullerene-Like Clusters Si30-Si38, Soohaeng Yoo, Nan Shao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We report improved results of lowest-lying silicon clusters Si₃₁–Si₃₈. A large population of low-energy clusters are collected from previous searches by several research groups and the binding energies of these clusters are computed using density-functional theory (DFT) methods. Best candidates (isomers with high binding energies) are identified from the screening calculations. Additional constrained search is then performed for the best candidates using the basin-hopping method combined with DFT geometry optimization. The obtained low-lying clusters are classified according to binding energies computed using either the Perdew–Burke–Ernzerhof (PBE) functional or the Becke exchange and Lee–Yang–Parr correlation (BLYP) functional. …

Take Pride In America In Southern Nevada: Quarterly Progress Report, Period Covering July 6, 2009 – October 4, 2009, Margaret N. Rees

Anti-littering Programs

• The team showcased their clean up efforts to the Assistant Secretary of the Interior.
• Work continued on the development of an adopt-a-block/parcel program to address the litter and desert dumping problems that exist in the urban-public land interfaces throughout Clark County.
• The team has sent a representative to serve on the City of Las Vegas Keep America Beautiful task force.
• The team began collaboration with the Howard Hughes Corporation on a desert clean up.
• The recycling feasibility report was presented and approved by the SNAP board.
• The team made substantial progress on the completion of a strategic plan.
• A working …

Contributions To The Development Of The S.E.T.U.P. (Experimental And Theoretical Simulations Useful For Planetology) Project, E. Arzoumanian, C. Romanzin, M-C. Gazeau, Et. Es-Sebbar, A. Jolly, S. Perrier, Y. Benilan

Dr. Et-touhami Es-sebbar

No abstract provided.

Multiwavelength Studies For Titan's Atmospheric Composition Analysis, Y. Benilan, Et. Es-Sebbar, N. Fray, M-C. Gazeau, A. Jolly, M. Schwell, J. Guillemin

Dr. Et-touhami Es-sebbar

Titan's atmosphere mainly made of nitrogen and methane is rich in organic molecules. Hydrocarbons are formed from the photolytic dissociation of CH4 and nitriles are created by dissociation of N2 followed by reactions with hydrocarbons. In order to understand the physicochemical mechanisms responsible for the evolution of Titan's atmosphere, photochemical models are built. The latter need constrains for vertical profiles of organic compounds from the high thermosphere down to the low stratosphere as well as photodissociation rates. Those profiles over the entire atmosphere can be retrieved from Cassini observations, in particular by limb sounding, coupling infrared and ultraviolet spectroscopy. However, …

Modulation Of Enzyme-Substrate Selectivity Using Tetraethylene Glycol Functionalized Gold Nanoparticles, Bj Jordan, R Hong, G Han, S Rana, Vm Rotello

Vincent Rotello

Tetraethylene glycol (TEG) functionalized gold nanoparticles with 2 nm core diameters (AuTEG) enhance α-chymotrypsin (ChT) enzyme activity in a substrate-selective fashion. We explored the hydrolysis of four different substrates and observed a marked increase in activity with the most hydrophobic substrate N-succinyl-alanine-alanine-proline-phenylalanine- p-nitroanilide (TP), while the other substrates remain virtually unaffected by the AuTEG 'crowding effect' in solution. The enhancement in catalysis is indicated by an increase in Kcat/Km as obtained from Lineweaver–Burk analysis and we hypothesize it to arise from a macromolecular crowding effect analogous to that observed with high molecular weight poly(ethylene glycol) (PEG) polymers.

Mass Transfer Variations In Ux Monocerotis: Eight Years Of Automated Photometric Monitoring, Edward C. Olson, Gregory W. Henry, Paul B. Etzel

Information Systems and Engineering Management Research Publications

We analyze eight years (1999–2007) of automated photometric observations of the active Algol binary UX Monocerotis to search for mass transfer bursts similar to those seen in U Cephei. The largest photometric anomaly is the mean gainer luminosity difference between the stream-impact hemisphere and the opposite hemisphere. We find an updated Wilson–Devinney solution for earlier six-color observations. The UX Mon donor star fills its Roche lobe and the gainer nearly fills its rotational lobe. Instead of isolated bursts of the U Cep type, we found nearly continuous brightness fluctuations likely produced by variable mass transfer. We discuss implications for mass …

Electronic Transport Properties Of A Tilted Graphene P-N Junction, Tony Low, Joerg Appenzeller

Birck and NCN Publications

Spatial manipulation of current flow in graphene could be achieved through the use of a tilted p-n junction. We show through numerical simulation that a pseudo-Hall effect (i.e., nonequilibrium charge and current density accumulating along one of the sides of a graphene ribbon) can be observed under these conditions. The tilt angle and the p-n transition length are two key parameters in tuning the strength of this effect. This phenomenon can be explained using classical trajectory via ray analysis, and is therefore relatively robust against disorder. Lastly, we propose and simulate a three terminal device that allows direct experimental access …