Structural Basis For The Superior Activity Of The Large Isoform Of Snow Flea Antifreeze Protein,
2010
Queen's University - Kingston, Ontario
Structural Basis For The Superior Activity Of The Large Isoform Of Snow Flea Antifreeze Protein, Yee-Foong Mok, Feng-Hsu Lin, Laurie A. Graham, Yeliz Celik, Ido Braslavsky, Peter L. Davies
Physics Faculty Research
The snow flea (Hypogastrum harveyi) is protected from freezing at sub-zero temperatures by a glycine-rich antifreeze protein (AFP) that binds to seed ice crystals and prevents them from growing larger. This AFP is hyperactive and comprises two isoforms [Graham, L. A., and Davies, P. L. (2005) Science 310, 461]. The larger isoform (15.7 kDa) exhibits several-fold higher activity than the smaller isoform (6.5 kDa), although it is considerably less abundant. To establish the molecular basis for this difference in activity, we determined the sequence of the large isoform. The primary sequences of these two isoforms are surprisingly divergent. However, both …
Interaction Of Excited States In Two-Species Bose-Einstein Condensates: A Case Study,
2010
Calvin University
Interaction Of Excited States In Two-Species Bose-Einstein Condensates: A Case Study, Todd Kapitula, Kody J.H. Law, Panayotis G. Kevrekidis
University Faculty Publications and Creative Works
In this paper we consider the existence and spectral stability of excited states in two-species Bose-Einstein condensates in the case of a pancake magnetic trap. Each new excited state found in this paper is to leading order a linear combination of two one-species dipoles, each of which is a spectrally stable excited state for one-species condensates. The analysis is done via a Lyapunov-Schmidt reduction and is valid in the limit of weak nonlinear interactions. Some conclusions, however, can be made at this limit which remain true even when the interactions are large. © 2010 Society for Industrial and Applied Mathematics.
Simulating The Fticr-Ms Signal Of A Decaying Beryllium-7 Ion Plasma In A 2d Electrostatic Pic Code,
2010
Brigham Young University - Provo
Simulating The Fticr-Ms Signal Of A Decaying Beryllium-7 Ion Plasma In A 2d Electrostatic Pic Code, Michael Takeshi Nakata
Theses and Dissertations
Beryllium-7 (Be-7) only decays by electron capture into lithium-7 (Li-7) with a half life of 53 days. We study the effect of ionization on this decay rate. We do so by trapping a Be-7 ion plasma in a cylindrical Malmberg-Penning trap and measuring Be-7 and Li-7 concentrations as functions of time by using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). We have simulated these signals in a 2-dimensional electrostatic particle-in-cell (PIC) code. The two spectrum peaks merge at high ion densities whereas at low ion densities they can be resolved. The merged peak shifts linearly according to the relative …
On The Feasibility Of A Timely Transition To A More Sustainable Energy Future,
2010
CUNY Brooklyn College
On The Feasibility Of A Timely Transition To A More Sustainable Energy Future, Micha Tomkiewicz
Publications and Research
The paper uses the framework of the IPAT equation, as applied to CO2 emission, to decompose the various driving forces in the global energy use. Data from recent history are superimposed on projections of SRES IPCC scenarios to determine if enough sustainable capacity can be built to prevent irreversible ecological deterioration. The conclusion from the analysis is that, in agreement with the IPCC 4th report, until about 2030 there are no large differences between a sustainable scenario and the one that resembles “business as usual”. The sharp divergence that follows stems from different estimates in population growth and in the …
Cosmic Evolution Of Black Holes And Spheroids. Iv. The MBh - LSph Relation,
2010
University of California - Santa Barbara
Cosmic Evolution Of Black Holes And Spheroids. Iv. The MBh - LSph Relation, Vardha N. Bennert, Tommaso Treu, Jong-Hak Woo, Matthew A. Malkan, Alexandre Le Bris, Matthew W. Auger, Sarah Gallagher, Roger D. Blandford
Physics
From high-resolution images of 23 Seyfert-1 galaxies at z = 0.36 and z = 0.57 obtained with the Near-Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope (HST), we determine host-galaxy morphology, nuclear luminosity, total host-galaxy luminosity, and spheroid luminosity. Keck spectroscopy is used to estimate black hole mass (M BH). We study the cosmic evolution of the M BH-spheroid luminosity (L sph) relation. In combination with our previous work, totaling 40 Seyfert-1 galaxies, the covered range in BH mass is substantially increased, allowing us to determine for the first time …
Fission Fragment Isomers Populated Via 6Li+232Th.,
2010
University of Richmond
Fission Fragment Isomers Populated Via 6Li+232Th., J. J. Ressler, J. A. Caggiano, C. J. Francy, P. N. Peplowski, J. M. Allmond, C. W. Beausang, L. A. Bernstein, D. L. Bleuel, J. T. Burke, P. Fallon, A. A. Hecht, D. V. Jordan, S. R. Lesher, M. A. Mcmahan, T. S. Palmer, L. Phair, N. D. Scielzo, P. G. Swearingen, G. A. Warren, M. Wiedeking
Physics Faculty Publications
Short-lived isomers in fission fragments following bombardment of 45-MeV 6Li on 232Th were examined. Isomers in the A ~ 95,122, and 132 mass regions were observed. New isomeric decays were observed in 121In [T1/2=17(2) μs], 123In (T1/2≳100 μs), and 125Sb [T1/2=25(4) μs]. These isomers are suggested to arise from ν(h11/2⊗d3/2)7−and ν(h11/2⊗s1/2)5− neutron core excitations coupling with the valence proton.
Logic Is To The Quantum As Geometry Is To Gravity,
2010
Syracuse University- Physics Department and Perimeter Institute
Logic Is To The Quantum As Geometry Is To Gravity, Rafael D. Sorkin
Physics - All Scholarship
will propose that the reality to which the quantum formalism implicitly refers is a kind of generalized history, the word history having here the same meaning as in the phrase sum-over-histories. This proposal confers a certain independence on the concept of event, and it modifies the rules of inference concerning events in order to resolve a contradiction between the idea of reality as a single history and the principle that events of zero measure cannot happen (the Kochen-Specker paradox being a classic expression of this contradiction). The so-called measurement problem is then solved if macroscopic events satisfy classical rules of …
Covariant Quantum Fields On Noncommutative Spacetimes,
2010
Syracuse University
Covariant Quantum Fields On Noncommutative Spacetimes, A. P. Balachandran, A. Ibort, G. Marmo, M. Martone
Physics - All Scholarship
A spinless covariant field $\phi$ on Minkowski spacetime $\M^{d+1}$ obeys the relation $U(a,\Lambda)\phi(x)U(a,\Lambda)^{-1}=\phi(\Lambda x+a)$ where $(a,\Lambda)$ is an element of the Poincar\'e group $\Pg$ and $U:(a,\Lambda)\to U(a,\Lambda)$ is its unitary representation on quantum vector states. It expresses the fact that Poincar\'e transformations are being unitary implemented. It has a classical analogy where field covariance shows that Poincar\'e transformations are canonically implemented. Covariance is self-reproducing: products of covariant fields are covariant. We recall these properties and use them to formulate the notion of covariant quantum fields on noncommutative spacetimes. In this way all our earlier results on dressing, statistics, etc. for …
Quantum Corrections To The Gravitational Potential And Orbital Motion,
2010
Wilfrid Laurier University
Quantum Corrections To The Gravitational Potential And Orbital Motion, Ioannis Haranas, Vasile Mioc
Physics and Computer Science Faculty Publications
GRT predicts the existence of relativistic corrections to the static Newtonian potential, which can be calculated and verified experimentally. The idea leading to quantum corrections at large distances consists of the interactions of massless particles, which only involve their coupling energies at low energies. Using the quantum correction term of the potential we obtain the perturbing quantum acceleration function. Next, with the help of the Newton-Euler planetary equations, we calculate the time rates of changes of the orbital elements per revolution for three different orbits around the primary. For one solar mass primary and an orbit with semimajor axis and …
Stochastic Electromagnetic Beams In Positive-And Negative-Phase Materials,
2010
University of Miami
Stochastic Electromagnetic Beams In Positive-And Negative-Phase Materials, Zhisong Tong, Olga Korotkova
Physics Articles and Papers
Theoretical analysis of interaction of stochastic electromagnetic beamlike fields with positive- and negative-phase materials suggests that suitable combinations of such materials can serve as media where spectral, coherence, and polarization properties of beams can self-reconstruct.
Spectral Shifts And Switches In Random Fields Upon Interaction With Negative-Phase Materials,
2010
University of Miami
Spectral Shifts And Switches In Random Fields Upon Interaction With Negative-Phase Materials, Zhisong Tong, Olga Korotkova
Physics Articles and Papers
Spectral shifts in stochastic beam-like fields on interaction with layers of positive- and negative-phase materials are examined on the basis of the ABCD-matrix approach and generalized Huygens-Fresnel principle. It is found that boundaries between such materials may cause spectral switches. Effect of absorption of negative-phase materials on the beam spectrum is discussed. Our results may find applications in connection with spectrum-selection optical interconnects, spectrally encoded information transfer, image formation in systems involving negative-phase materials, and geometrically tunable metamaterials.
Theory Of Weak Scattering Of Stochastic Electromagnetic Fields From Deterministic And Random Media,
2010
University of Miami
Theory Of Weak Scattering Of Stochastic Electromagnetic Fields From Deterministic And Random Media, Zhisong Tong, Olga Korotkova
Physics Articles and Papers
The theory of scattering of scalar stochastic fields from deterministic and random media is generalized to the electromagnetic domain under the first-order Born approximation. The analysis allows for determining the changes in spectrum, coherence, and polarization of electromagnetic fields produced on their propagation from the source to the scattering volume, interaction with the scatterer, and propagation from the scatterer to the far field. An example of scattering of a field produced by a δ-correlated partially polarized source and scattered from a δ-correlated medium is provided.
Oxidation Of Pdn (N=1–7,10) Clusters Supported On Alumina/Nial(110),
2010
Virginia Commonwealth University
Oxidation Of Pdn (N=1–7,10) Clusters Supported On Alumina/Nial(110), R. Robles, Shiv N. Khanna
Physics Publications
First-principles theoretical investigations on the oxidation of Pdn (n=1–7, 10) clusters deposited on alumina/NiAl(110) have been carried out using a gradient-corrected density-functional approach. Our studies indicate that the free Pdn clusters are compact and maintain their compact structures when deposited on the surface, undergoing only small relaxations of the Pd-Pd distance. The clusters bind to the surface via a pair of Pd atoms and with a binding energy of around 1.0 eV. Studies of oxidation through an O2molecule show that O2 occupies sites closer to the surface for Pd1, Pd4, Pd5, and Pd6 while, in other cases, the binding is …
Electronic And Magnetic Properties Of A Bn Sheet Decorated With Hydrogen And Fluorine,
2010
Peking University
Electronic And Magnetic Properties Of A Bn Sheet Decorated With Hydrogen And Fluorine, Jian Zhou, Qian Wang, Qiang Sun, Puru Jena
Physics Publications
First-principles calculations based on density-functional theory reveal some unusual properties of BN sheet functionalized with hydrogen and fluorine. These properties differ from those of similarly functionalized graphene even though both share the same honeycomb structure. (1) Unlike graphene which undergoes a metal to insulator transition when fully hydrogenated, the band gap of the BN sheet significantly narrows when fully saturated with hydrogen. Furthermore, the band gap of the BN sheet can be tuned from 4.7 to 0.6 eV and the system can be a direct or an indirect semiconductor or even a half-metal depending on surface coverage. (2) Unlike graphene, …
Crystal Field Effects On The Reactivity Of Aluminum-Copper Cluster Anions,
2010
Pennsylvania State University - Main Campus
Crystal Field Effects On The Reactivity Of Aluminum-Copper Cluster Anions, Patrick J. Roach, W. Hunter Woodward, Arthur C. Reber, Shiv N. Khanna, A. W. Castleman Jr.
Physics Publications
The limits and useful modifications of the jellium model are of great interest in understanding the properties of metallic clusters, especially involving bimetallic systems. We have measured the relative reactivity of CuAl−n clusters (n=11–34) with O2. An odd-even alternation is observed that is in accordance with spin-dependant etching, and CuAl−22is observed as a “magic peak.” The etching resistance of CuAl−22 is explained by an unusually large splitting of the 2D10 subshell that occurs because of a geometric distortion of the cluster that may also be understood as a crystal field splitting of the superatomic orbitals.
First-Principles Study Of Hydrogen Adsorption In Metal-Doped Cof-10,
2010
Peking University, Virginia Commonwealth University
First-Principles Study Of Hydrogen Adsorption In Metal-Doped Cof-10, Miao Miao Wu, Qian Wang, Qiang Sun, Puru Jena, Yoshiyuki Kawazoe
Physics Publications
Covalent organic frameworks (COFs), due to their low-density, high-porosity, and high-stability, have promising applications in gas storage. In this study we have explored the potential of COFs doped with Li and Ca metal atoms for storing hydrogen under ambient thermodynamic conditions. Using density functional theory we have performed detailed calculations of the sites Li and Ca atoms occupy in COF-10 and their interaction with hydrogen molecules. The binding energy of Li atom on COF-10 substrate is found to be about 1.0 eV and each Li atom can adsorb up to three H2 molecules. However, at high concentration, Li atoms cluster …
Negative Ions Of Transition Metal-Halogen Clusters,
2010
Virginia Commonwealth University
Negative Ions Of Transition Metal-Halogen Clusters, Kalpataru Pradhan, Gennady L. Gutsev, Purusottam Jena
Physics Publications
A systematic density functional theory based study of the structure and spectroscopic properties of neutral and negatively chargedMXn clusters formed by a transition metal atom M (M=Sc,Ti,V) and up to seven halogen atoms X (X=F,Cl,Br) has revealed a number of interesting features: (1) Halogen atoms are bound chemically to Sc, Ti, and V for n≤nmax, where the maximal valence nmax equals to 3, 4, and 5 for Sc, Ti, and V, respectively. For n>nmax, two halogen atoms became dimerized in the neutral species, while dimerization begins at n=5, 6, and 7 for negatively charged clusters containing Sc, Ti, and …
Electronic Structure And Properties Of Isoelectronic Magic Clusters: Al13x (X=H,Au,Li,Na,K,Rb,Cs),
2010
Johns Hopkins University
Electronic Structure And Properties Of Isoelectronic Magic Clusters: Al13x (X=H,Au,Li,Na,K,Rb,Cs), Yeon Jae Ko, Anisha Shakya, Haopeng Wang, Andrej Grubisic, Weijun Zheng, Matthias Gotz, Gerd Gantefor, Kit H. Bowen, Puru Jena, Boggavarapu Kiran
Physics Publications
The equilibrium structure, stability, and electronic properties of the Al13X (X=H,Au,Li,Na,K,Rb,Cs) clusters have been studied using a combination of photoelectron spectroscopy experiment and density functional theory. All these clusters constitute 40 electron systems with 39 electrons contributed by the 13 Al atoms and 1 electron contributed by each of the X (X=H,Au,Li,Na,K,Rb,Cs) atom. A systematic study allows us to investigate whether all electrons contributed by the X atoms are alike and whether the structure, stability, and properties of all the magic clusters are similar. Furthermore, quantitative agreement between the calculated and the measured electron affinities and vertical detachment energies enable …
Enhanced Magnetic Moments Of Alkali Metal Coated Sc Clusters: New Magnetic Superatoms,
2010
Harish-Chandra Research Institute, Virginia Commonwealth University
Enhanced Magnetic Moments Of Alkali Metal Coated Sc Clusters: New Magnetic Superatoms, Kalpataru Pradhan, J. Ulises Reveles, Prasenjit Sen, S. N. Khanna
Physics Publications
It is shown that the magnetic moments of Sc atoms can be significantly enhanced by combining them with alkali atoms. We present results of first principles electronic structure calculations of ScNan (1≤n≤12) clusters that indicate that a ScNa12 cluster consisting of a Sc atom surrounded by 12 Na atoms forming a compact icosahedral structure has a spin magnetic moment of 3μB that is three times that of an isolated Sc atom. This unusual behavior is analyzed in terms of the filling of the supershells 1S, 1P,… controlled by the nature and size of the alkali atoms and the more localized …
Magnetic Moment And Local Moment Alignment In Anionic And/Or Oxidized Fen Clusters,
2010
Virginia Commonwealth University
Magnetic Moment And Local Moment Alignment In Anionic And/Or Oxidized Fen Clusters, D. R. Roy, R. Robles, S. N. Khanna
Physics Publications
First principles studies on the ground statestructure, binding energy, spin multiplicity, and the noncollinearity of local spin moments in Fen and Fen− clusters and their oxides, viz., FenO2and FenO2− have been carried out within a density functional formalism. The ground states of Fen and Fen− clusters have collinear spins with a magnetic moment of around 3.0 μB per atom. The O2 molecule is found to be dissociatively absorbed and its most significant effect on spin occurs in Fe2, where Fe2O2 and Fe2O2− show antiferromagnetic and noncollinear spin arrangements, respectively. The calculated adiabatic electron affinity and the vertical transitions from the …
