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Articles 137431 - 137460 of 303977

Full-Text Articles in Physical Sciences and Mathematics

Sensitivity Of Maize Yield Potential To Regional Climate In The Southwestern U.S., Seung Hee Kim, Boksoon Myoung, David Stack, Jinwon Kim, Menas Kafatos Jan 2016

Sensitivity Of Maize Yield Potential To Regional Climate In The Southwestern U.S., Seung Hee Kim, Boksoon Myoung, David Stack, Jinwon Kim, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

The sensitivity of maize yields to the regional climate in the Southwestern U.S. (SWUS) has been investigated by using the Agricultural Production Systems sIMulator (APSIM) model in conjunction with meteorological forcings [daily maximum and minimum temperature (Tmax and Tmin), precipitation, and radiation] from the North American Regional Reanalysis (NARR) dataset. Sensitivity experiments showed that potential crop production responded nonlinearly to variations in Tmax, Tmin, and downwelling solar radiation at the surface. Mean annual yield potential (Yp) was changed by -3.0 and 1.79 Mg ha-1 for the +1 and -1 standard deviations (σ) of Tmax variation for entire the SWUS. The …

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The Spectral Theorem For Quaternionic Unbounded Normal Operators Based On The S-Spectrum, Daniel Alpay, Fabrizio Colombo, David P. Kimsey Jan 2016

The Spectral Theorem For Quaternionic Unbounded Normal Operators Based On The S-Spectrum, Daniel Alpay, Fabrizio Colombo, David P. Kimsey

Mathematics, Physics, and Computer Science Faculty Articles and Research

In this paper we prove the spectral theorem for quaternionic unbounded normal operators using the notion of S-spectrum. The proof technique consists of first establishing a spectral theorem for quaternionic bounded normal operators and then using a transformation which maps a quaternionic unbounded normal operator to a quaternionic bounded normal operator. With this paper we complete the foundation of spectral analysis of quaternionic operators. The S-spectrum has been introduced to define the quaternionic functional calculus but it turns out to be the correct object also for the spectral theorem for quaternionic normal operators. The fact that the correct notion of …

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Characterizations Of Rectangular (Para)-Unitary Rational Functions, Daniel Alpay, Palle Jorgensen, Izchak Lewkowicz Jan 2016

Characterizations Of Rectangular (Para)-Unitary Rational Functions, Daniel Alpay, Palle Jorgensen, Izchak Lewkowicz

Mathematics, Physics, and Computer Science Faculty Articles and Research

We here present three characterizations of not necessarily causal, rational functions which are (co)-isometric on the unit circle:
(i) through the realization matrix of Schur stable systems,
(ii) the Blaschke-Potapov product, which is then employed to introduce an easy-to-use description of all these functions with dimensions and McMillan degree as parameters,
(iii) through the (not necessarily reducible) Matrix Fraction Description (MFD).
In cases (ii) and (iii) the poles of the rational functions involved may be anywhere in the complex plane, but the unit circle (including both zero and infinity). A special attention is devoted to exploring the gap between the …

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Wiener Algebra For The Quaternions, Daniel Alpay, Fabrizio Colombo, David P. Kimsey, Irene Sabadini Jan 2016

Wiener Algebra For The Quaternions, Daniel Alpay, Fabrizio Colombo, David P. Kimsey, Irene Sabadini

Mathematics, Physics, and Computer Science Faculty Articles and Research

We define and study the counterpart of the Wiener algebra in the quaternionic setting, both for the discrete and continuous case. We prove a Wiener-Lévy type theorem and a factorization theorem. We give applications to Toeplitz and Wiener-Hopf operators.

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A New Realization Of Rational Functions, With Applications To Linear Combination Interpolation, Daniel Alpay, Palle Jorgensen, Izchak Lewkowicz, Dan Volok Jan 2016

A New Realization Of Rational Functions, With Applications To Linear Combination Interpolation, Daniel Alpay, Palle Jorgensen, Izchak Lewkowicz, Dan Volok

Mathematics, Physics, and Computer Science Faculty Articles and Research

We introduce the following linear combination interpolation problem (LCI): Given N distinct numbers w1,…wN and N+1 complex numbers a1,…,aN and c, find all functions f(z) analytic in a simply connected set (depending on f) containing the points w1,…,wN such that ∑u=1Nauf(wu)=c. To this end we prove a representation theorem for such functions f in terms of an associated polynomial p(z). We first introduce the following two operations, (i) substitution of p, and (ii) multiplication by monomials zj,0≤j

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Leveraging Heritrix And The Wayback Machine On A Corporate Intranet: A Case Study On Improving Corporate Archives, Justin F. Brunelle, Krista Ferrante, Eliot Wilczek, Michele C. Weigle, Michael L. Nelson Jan 2016

Leveraging Heritrix And The Wayback Machine On A Corporate Intranet: A Case Study On Improving Corporate Archives, Justin F. Brunelle, Krista Ferrante, Eliot Wilczek, Michele C. Weigle, Michael L. Nelson

Computer Science Faculty Publications

In this work, we present a case study in which we investigate using open-source, web-scale web archiving tools (i.e., Heritrix and the Wayback Machine installed on the MITRE Intranet) to automatically archive a corporate Intranet. We use this case study to outline the challenges of Intranet web archiving, identify situations in which the open source tools are not well suited for the needs of the corporate archivists, and make recommendations for future corporate archivists wishing to use such tools. We performed a crawl of 143,268 URIs (125 GB and 25 hours) to demonstrate that the crawlers are easy to set …

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Higher Order Z-Ideals In Commutative Rings, Themba Dube, Oghenetega Ighedo Jan 2016

Higher Order Z-Ideals In Commutative Rings, Themba Dube, Oghenetega Ighedo

Mathematics, Physics, and Computer Science Faculty Articles and Research

We study ideals that resemble z-ideals in commutative rings with identity. For each positive integer n, we say an ideal of a commutative ring A is a zn-ideal in case it has the property that if a and b belong to the same maximal ideals of A, and an ϵ I , then bn is also in I. The set of all zn-ideals of A is denoted by A --> ʒn (A). This gives an ascending chain ʒ(A) < ʒ2(A) < ʒ3(A) <… of collections of ideals, starting with the collection of z-ideals. …

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Quantum Violation Of The Pigeonhole Principle And The Nature Of Quantum Correlations, Yakir Aharonov, Fabrizio Colombo, S. Popescu, Irene Sabadini, Daniele C. Struppa, Jeff Tollaksen Jan 2016

Quantum Violation Of The Pigeonhole Principle And The Nature Of Quantum Correlations, Yakir Aharonov, Fabrizio Colombo, S. Popescu, Irene Sabadini, Daniele C. Struppa, Jeff Tollaksen

Mathematics, Physics, and Computer Science Faculty Articles and Research

The pigeonhole principle: "If you put three pigeons in two pigeonholes at least two of the pigeons end up in the same hole" is an obvious yet fundamental principle of Nature as it captures the very essence of counting. Here however we show that in quantum mechanics this is not true! We find instances when three quantum particles are put in two boxes, yet no two particles are in the same box. Furthermore, we show that the above "quantum pigeonhole principle" is only one of a host of related quantum effects, and points to a very interesting structure of quantum …

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Handcrafted Microwire Regenerative Peripheral Nerve Interfaces With Wireless Neural Recording And Stimulation Capabilities, Ali Ajam, Ridwan Hossain, Nishat Tasnim, Luis Castanuela, Raul Ramos, Dong-Chul Kim, Yoonsu Choi Jan 2016

Handcrafted Microwire Regenerative Peripheral Nerve Interfaces With Wireless Neural Recording And Stimulation Capabilities, Ali Ajam, Ridwan Hossain, Nishat Tasnim, Luis Castanuela, Raul Ramos, Dong-Chul Kim, Yoonsu Choi

Computer Science Faculty Publications and Presentations

A scalable microwire peripheral nerve interface was developed, which interacted with regenerated peripheral nerves in microchannel scaffolds. Neural interface technologies are envisioned to facilitate direct connections between the nervous system and external technologies such as limb prosthetics or data acquisition systems for further processing. Presented here is an animal study using a handcrafted microwire regenerative peripheral nerve interface, a novel neural interface device for communicating with peripheral nerves. The neural interface studies using animal models are crucial in the evaluation of efficacy and safety of implantable medical devices before their use in clinical studies. 16- electrode microwire microchannel scaffolds were …

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Exploring Factors That Explain Possible Needs Of Mobile Devices Integrated In Elearning Through Learning Profiling, Cheng-Chang Pan, Stephen Sivo, Francisco Garcia Jan 2016

Exploring Factors That Explain Possible Needs Of Mobile Devices Integrated In Elearning Through Learning Profiling, Cheng-Chang Pan, Stephen Sivo, Francisco Garcia

Computer Science Faculty Publications and Presentations

Profiling elearning students is a common practice in the field. It carries good intention. Which learner group requires more attention of the university administration in optimizing resources and creating incentives resulting into a social outcome that is efficient and makes all concerned parties better off? Results suggested that the learners who perceive higher in university’s CMS support, instructor instructional and communicational use of CMS, and affinity for technology may deserve better attention of the management.

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Beyond Just Sea-Level Rise: Considering Macroclimatic Drivers Within Coastal Wetland Vulnerability Assessments To Climate Change, Michael J. Osland, Nicholas M. Enwright, Richard H. Day, Christopher A. Gabler, Camille L. Stagg, James B. Grace Jan 2016

Beyond Just Sea-Level Rise: Considering Macroclimatic Drivers Within Coastal Wetland Vulnerability Assessments To Climate Change, Michael J. Osland, Nicholas M. Enwright, Richard H. Day, Christopher A. Gabler, Camille L. Stagg, James B. Grace

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

Due to their position at the land-sea interface, coastal wetlands are vulnerable to many aspects of climate change. However, climate change vulnerability assessments for coastal wetlands generally focus solely on sea-level rise without considering the effects of other facets of climate change. Across the globe and in all ecosystems, macroclimatic drivers (e.g., temperature and rainfall regimes) greatly influence ecosystem structure and function. Macroclimatic drivers have been the focus of climate change-related threat evaluations for terrestrial ecosystems, but largely ignored for coastal wetlands. In some coastal wetlands, changing macroclimatic conditions are expected to result in foundation plant species replacement, which would …

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Determination Of Rejected Landing Roll Runway Point-Of-No-Return And Go-Around In Transport Category Airplanes, Nihad E. Daidzic, Ph.D., Sc.D. Jan 2016

Determination Of Rejected Landing Roll Runway Point-Of-No-Return And Go-Around In Transport Category Airplanes, Nihad E. Daidzic, Ph.D., Sc.D.

International Journal of Aviation, Aeronautics, and Aerospace

The decelerate-accelerate-takeoff maneuver in transport category airplanes has been discussed. Mathematical model based on total energy conservation has been used to calculate the rejected landing point-of-no-return on a runway which will still enable the airplane to safely execute go-around and achieve regulatory screen heights and takeoff safety speeds. After this point has been exceeded or below the point-of-no-return speed no go-around should ever be considered. Landing long and fast and/or decelerating on slippery runways may very well result in an overrun which could be prevented if the go-around is attempted before reaching this critical runway point. The point-of-no-return on the …

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High-Resolution Ground-Penetrating Radar Profiles Of Perennial Lake Ice In The Mcmurdo Dry Valleys, Antarctica: Horizon Attributes, Unconformities, And Subbottom, Hilary A. Dugan, Steven A. Arcone, Maciej K. Obryk, Peter T. Doran Jan 2016

High-Resolution Ground-Penetrating Radar Profiles Of Perennial Lake Ice In The Mcmurdo Dry Valleys, Antarctica: Horizon Attributes, Unconformities, And Subbottom, Hilary A. Dugan, Steven A. Arcone, Maciej K. Obryk, Peter T. Doran

Geology Faculty Publications and Presentations

Ground-penetrating radar (GPR) is not commonly used to study lake ice, and in general, the ground-based use of radar frequencies greater than 500 MHz in cryosphere geophysics is rare, due to a general interest in deeper stratigraphy and the difficulty of extensive profiling over rough snow surfaces. Our goal was to find further information on the origin of the deposition and formation of intra-ice layers, bottom topography, and subbottom deposits using GPR with pulses centered near 850 MHz on two permanently ice-covered lakes in the Mc- Murdo Dry Valleys, Antarctica. The profiles were obtained using a one-person sled operation over …

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The Complements Of Lower Cones Of Degrees And The Degree Spectra Of Structures, Uri Andrews, Mingzhong Cai, Iskander Sh Kalimullin, Steffen Lempp, Joseph S. Miller, Antonio Montalban Jan 2016

The Complements Of Lower Cones Of Degrees And The Degree Spectra Of Structures, Uri Andrews, Mingzhong Cai, Iskander Sh Kalimullin, Steffen Lempp, Joseph S. Miller, Antonio Montalban

Dartmouth Scholarship

We study Turing degrees a for which there is a countable structure whose degree spectrum is the collection {x : x ≰ a}. In particular, for degrees a from the interval [0′, 0″], such a structure exists if a′ = 0″, and there are no such structures if a″ > 0‴.

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A Hybrid Algorithm Based On Optimal Quadratic Spline Collocation And Parareal Deferred Correction For Parabolic Pdes, Jun Liu, Yan Wang, Rongjian Li Jan 2016

A Hybrid Algorithm Based On Optimal Quadratic Spline Collocation And Parareal Deferred Correction For Parabolic Pdes, Jun Liu, Yan Wang, Rongjian Li

Computer Science Faculty Publications

Parareal is a kind of time parallel numerical methods for time-dependent systems. In this paper, we consider a general linear parabolic PDE, use optimal quadratic spline collocation (QSC) method for the space discretization, and proceed with the parareal technique on the time domain. Meanwhile, deferred correction technique is also used to improve the accuracy during the iterations. In fact, the optimal QSC method is a correction of general QSC method. Along the temporal direction we embed the iterations of deferred correction into parareal to construct a hybrid method, parareal deferred correction (PDC) method. The error estimation is presented and the …

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Effect Of Spatial Inhomogeneities On The Membrane Surface On Receptor Dimerization And Signal Initiation, Romica Kerketta, Adam M. Halasz, Mara P. Steinkamp, Bridget S. Wilson, Jeremy S. Edwards Jan 2016

Effect Of Spatial Inhomogeneities On The Membrane Surface On Receptor Dimerization And Signal Initiation, Romica Kerketta, Adam M. Halasz, Mara P. Steinkamp, Bridget S. Wilson, Jeremy S. Edwards

Faculty & Staff Scholarship

Important signal transduction pathways originate on the plasma membrane, where microdomains may transiently entrap diffusing receptors. This results in a non-random distribution of receptors even in the resting state, which can be visualized as “clusters” by high resolution imaging methods. Here, we explore how spatial in-homogeneities in the plasma membrane might influence the dimerization and phosphorylation status of ErbB2 and ErbB3, two receptor tyrosine kinases that preferentially heterodimerize and are often co-expressed in cancer. This theoretical study is based upon spatial stochastic simulations of the two-dimensional membrane landscape, where variables include differential distributions and overlap of transient confinement zones (“domains”) …

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Dual Role Of Sb Ions As Electron Traps And Hole Traps In Photorefractive Sn2p2s6 Crystals, B. E. Kananen, E. M. Golden, S. A. Basun, D. R. Evans, A. A. Grabar, I. M. Stoika, J. W. Mcclory, N. C. Giles, L. E. Halliburton Jan 2016

Dual Role Of Sb Ions As Electron Traps And Hole Traps In Photorefractive Sn2p2s6 Crystals, B. E. Kananen, E. M. Golden, S. A. Basun, D. R. Evans, A. A. Grabar, I. M. Stoika, J. W. Mcclory, N. C. Giles, L. E. Halliburton

Faculty & Staff Scholarship

Doping photorefractive single crystals of Sn2P2S6 with antimony introduces both electron and hole traps. In as-grown crystals, Sb3+ (5s2 ) ions replace Sn2+ ions. These Sb3+ ions are either isolated (with no nearby perturbing defects) or they have a chargecompensating Sn2+ vacancy at a nearest-neighbor Sn site. When illuminated with 633 nm laser light, isolated Sb3+ ions trap electrons and become Sb2+ (5s2 5p1 ) ions. In contrast, Sb3+ ions with an adjacent Sn vacancy trap holes during illumination. The hole is primarily localized on the (P2S6) 4− anionic unit next to the Sb3+ ion and Sn2+ vacancy. These trapped …

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The Role Of Defects In The Electrical Properties Of Nbo2 Thin Film Vertical Devices, Toyanath Joshi, Pavel Borisov, David Lederman Jan 2016

The Role Of Defects In The Electrical Properties Of Nbo2 Thin Film Vertical Devices, Toyanath Joshi, Pavel Borisov, David Lederman

Faculty & Staff Scholarship

Epitaxial NbO2 thin films were grown on Si:GaN layers deposited on Al2O3 substrates using pulsed laser deposition. Pulsed current-voltage (IV) curves and self-sustained current oscillations were measured across a 31 nm NbO2 film and compared with a similar device made from polycrystalline NbO2 film grown on TiN-coated SiO2/Si substrate. Crystal quality of the as grown films was determined from x-ray diffractometry, x-ray photoelectron spectroscopy and atomic force microscopy data. The epitaxial film device was found to be more stable than the defect-rich polycrystalline sample in terms of current switching and oscillation behaviors.

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Ionic Liquid Based Fluorescent Sensors For Cations, Jaelene M. Torres Jan 2016

Ionic Liquid Based Fluorescent Sensors For Cations, Jaelene M. Torres

Theses, Dissertations and Culminating Projects

The development of novel fluorescent sensors for cations is an area of current interest. Most of these sensors are large organic molecules that have a low solubility in water and are not suitable to be used as sensors in water. The goal of this study is to develop a new sensor by attaching an ionic liquid group to make it water-soluble. We have used a well-known photoinduced electron transfer (PET) sensor for protons as our first test. This sensor is based on a chromophore-spacer-receptor design that is based on an anthracene chromophore and a morpholine proton receptor. The sensor is …

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Rapid And Accurate C-V Measurements, Ji-Hong Kim, Pragya R. Shrestha, Jason P. Campbell, Jason T. Ryan, David Nminibapiel, Joseph J. Kopanski Jan 2016

Rapid And Accurate C-V Measurements, Ji-Hong Kim, Pragya R. Shrestha, Jason P. Campbell, Jason T. Ryan, David Nminibapiel, Joseph J. Kopanski

Electrical & Computer Engineering Faculty Publications

We report a new technique for the rapid measurement of full capacitance-voltage (C-V) characteristic curves. The displacement current from a 100-MHz applied sine wave, which swings from accumulation to strong inversion, is digitized directly using an oscilloscope from the MOS capacitor under test. A C-V curve can be constructed directly from this data but is severely distorted due to nonideal behavior of real measurement systems. The key advance of this paper is to extract the system response function using the same measurement setup and a known MOS capacitor. The system response correction to the measured C-V curve of the unknown …

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Seebeck Coefficient Enhancement Of Ald Pbte/Pbse Nanolaminate Structures Deposited Inside Porous Silicon Templates, Xin Chen, Pengtao Lin, Kai Zhang, Helmut Baumgart, Brian Geist, Vladimir Kochergin Jan 2016

Seebeck Coefficient Enhancement Of Ald Pbte/Pbse Nanolaminate Structures Deposited Inside Porous Silicon Templates, Xin Chen, Pengtao Lin, Kai Zhang, Helmut Baumgart, Brian Geist, Vladimir Kochergin

Electrical & Computer Engineering Faculty Publications

In this paper, lead chalcogenide based thermoelectric nanolaminate structures were fabricated by alternately depositing PbTe and PbSe ALD layers on regular planar silicon wafers and on microporous silicon templates. Lead bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (Pb(C11H19O2) 2), plus (trimethylsilyl) telluride ((Me3Si)2Te) and (trimethylsilyl) selenide ((Me3Si)2Se) were used as the chemical ALD precursors for lead, tellurium and selenium, respectively. The Seebeck coefficient in horizontal direction (parallel direction to the surface) to the multiple layered PbTe/PbSe nanolaminate structures was measured by an MMR Seebeck system, and benchmarked against the Seebeck coefficient …

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X-Ray Structure And Properties Of The Ferrous Octaethylporphyrin Nitroxyl Complex, Nagabhushanam Kundakarla, Sergey V. Lindeman, Hafiz Md. Rahman, Michael D. Ryan Jan 2016

X-Ray Structure And Properties Of The Ferrous Octaethylporphyrin Nitroxyl Complex, Nagabhushanam Kundakarla, Sergey V. Lindeman, Hafiz Md. Rahman, Michael D. Ryan

Chemistry Faculty Research and Publications

The preparation and characterization of the iron octaethylporphyrin nitroxyl ion, [Fe(OEP)(NO)−], is reported. The complex was synthesized by the one-electron reduction of Fe(OEP)(NO) using anthracenide as the reducing agent. The compound was isolated as the potassium (2.2.2)cryptand salt. The anion was characterized using X-ray analysis with visible and infrared spectroscopy. The spectral features of the iron nitroxyl complex were consistent with previous literature reports. The important structural changes upon reduction were a significant decrease in the Fe–N–O bond angle from 142° to 127° and an increase in the N–O bond length from that in the starting nitrosyl moiety. …

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Hydrogen-Atom Attack On Phenol And Toluene Is Ortho-Directed, Olha Krechkivska, Callan M. Wilcox, Tyler P. Troy, Klaas Nauta, Bun Chan, Rebecca Jacob, Scott A. Reid, Leo Radom, Timothy W. Schmidt, Scott H. Kable Jan 2016

Hydrogen-Atom Attack On Phenol And Toluene Is Ortho-Directed, Olha Krechkivska, Callan M. Wilcox, Tyler P. Troy, Klaas Nauta, Bun Chan, Rebecca Jacob, Scott A. Reid, Leo Radom, Timothy W. Schmidt, Scott H. Kable

Chemistry Faculty Research and Publications

The reaction of H + phenol and H/D + toluene has been studied in a supersonic expansion after electric discharge. The (1 + 1′) resonance-enhanced multiphoton ionization (REMPI) spectra of the reaction products, at m/z = parent + 1, or parent + 2 amu, were measured by scanning the first (resonance) laser. The resulting spectra are highly structured. Ionization energies were measured by scanning the second (ionization) laser, while the first laser was tuned to a specific transition. Theoretical calculations, benchmarked to the well-studied H + benzene → cyclohexadienyl radical reaction, were performed. The spectrum arising from the …

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Accessing Spin-Crossover Behaviour In Iron(Ii) Complexes Of N-Confused Scorpionate Ligands, James R. Gardinier, Alexander Richard Treleven, Kristin J. Meise, Sergey Lindeman Jan 2016

Accessing Spin-Crossover Behaviour In Iron(Ii) Complexes Of N-Confused Scorpionate Ligands, James R. Gardinier, Alexander Richard Treleven, Kristin J. Meise, Sergey Lindeman

Chemistry Faculty Research and Publications

The first examples of a class of N-confused tris(pyrazolyl)methane ‘scorpionate’ ligands have been prepared. The magnetic properties of their iron(II) tetrafluoroborate complexes are dictated by changing one substituent per ligand rather than three as is typical for normal scorpionate ligands.

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A Full-Dimensional Model Of Ozone Forming Reaction: The Absolute Value Of The Recombination Rate Coefficient, Its Pressure And Temperature Dependencies, Alexander Teplukhin, Dmitri Babikov Jan 2016

A Full-Dimensional Model Of Ozone Forming Reaction: The Absolute Value Of The Recombination Rate Coefficient, Its Pressure And Temperature Dependencies, Alexander Teplukhin, Dmitri Babikov

Chemistry Faculty Research and Publications

Rigorous calculations of scattering resonances in ozone are carried out for a broad range of rotational excitations. The accurate potential energy surface of Dawes is adopted, and a new efficient method for calculations of ro–vibrational energies, wave functions and resonance lifetimes is employed (which uses hyper-spherical coordinates, the sequential diagonalization/truncation approach, grid optimization and complex absorbing potential). A detailed analysis is carried out to characterize distributions of resonance energies and lifetimes, their rotational/vibrational content and their positions with respect to the centrifugal barrier. Emphasis is on the contribution of these resonances to the recombination process that forms ozone. It is …

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Does Koopmans’ Paradigm For 1-Electron Oxidation Always Hold? Breakdown Of Ip/EOx Relationship For P-Hydroquinone Ethers And The Role Of Methoxy Group Rotation, Marat R. Talipov, Anitha Boddeda, Sergey V. Lindeman, Rajendra Rathore Jan 2016

Does Koopmans’ Paradigm For 1-Electron Oxidation Always Hold? Breakdown Of Ip/EOx Relationship For P-Hydroquinone Ethers And The Role Of Methoxy Group Rotation, Marat R. Talipov, Anitha Boddeda, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

Koopmans’ paradigm states that electron loss occurs from HOMO, thus forming the basis for the observed linear relationships between HOMO/IP, HOMO/Eox, and IP/Eox. In cases where a molecule undergoes dramatic structural reorganization upon 1-electron oxidation, the IP/Eoxrelationship does not hold, and the origin of which is not understood. For example, X-ray crystallography of the neutral and cation radicals of bicyclo[2.2.1]heptane-annulated p-hydroquinone ethers (THE and MHE) showed that they undergo electron-transfer-induced conformational reorganization and show breakdown of the IP/Eox relationship. DFT calculations revealed that Koopmans’ paradigm …

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Design And Synthesis Of Oxazoline-Based Scaffolds For Hybrid Lewis Acid/Lewis Base Catalysis Of Carbon–Carbon Bond Formation, Dennis Wiedenhoeft, Adam R. Benoit, Jacob D. Porter, Yibiao Wu, Rajdeep S. Virdi, Alaa Shanaa, Chris Dockendorff Jan 2016

Design And Synthesis Of Oxazoline-Based Scaffolds For Hybrid Lewis Acid/Lewis Base Catalysis Of Carbon–Carbon Bond Formation, Dennis Wiedenhoeft, Adam R. Benoit, Jacob D. Porter, Yibiao Wu, Rajdeep S. Virdi, Alaa Shanaa, Chris Dockendorff

Chemistry Faculty Research and Publications

A new class of hybrid Lewis acid/Lewis base catalysts has been designed and prepared with an initial objective of promoting stereoselective direct aldol reactions. Several scaffolds were synthesized that contain amine moieties capable of enamine catalysis, connected to heterocyclic metal-chelating sections composed of an oxazole–oxazoline or thiazole–oxazoline. Early screening results have identified oxa­zole–oxazoline-based systems capable of promoting a highly diastereo- and enantioselective direct aldol reaction of propionaldehyde with 4-nitrobenzaldehyde, when combined with Lewis acids such as zinc triflate.

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Inelastic Scattering Of Identical Molecules Within Framework Of The Mixed Quantum/Classical Theory: Application To Rotational Excitations In H2 + H2, Alexander Semenov, Dmitri Babikov Jan 2016

Inelastic Scattering Of Identical Molecules Within Framework Of The Mixed Quantum/Classical Theory: Application To Rotational Excitations In H2 + H2, Alexander Semenov, Dmitri Babikov

Chemistry Faculty Research and Publications

Theoretical foundation is laid out for description of permutation symmetry in the inelastic scattering processes that involve collisions of two identical molecules, within the framework of the mixed quantum/classical theory (MQCT). In this approach, the rotational (and vibrational) states of two molecules are treated quantum-mechanically, whereas their translational motion (responsible for scattering) is treated classically. This theory is applied to H2 + H2 system, and the state-to-state transition cross sections are compared versus those obtained from the full-quantum calculations and experimental results from the literature. Good agreement is found in all cases. It is also found that results of MQCT, …

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An Application Of The Spectral Theorem To The Laplacian On A Riemannian Manifold, Paul Bracken Jan 2016

An Application Of The Spectral Theorem To The Laplacian On A Riemannian Manifold, Paul Bracken

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

There continues to be great interest in the study of the heat equation on Riemannian manifolds. This may be due to the remarkable more recent work of Patodi [1]. It may also be due in part to the asymptotic expansion of Minakshisundaram and Pleijel. The heat equation involves a parabolic partial differential equation that describes the distribution of heat in a given region over time. This equation has also appears in probability theory to describe random walks. The heat equation is also of importance in Riemannian geometry, topology and applied mathematics.

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Response Of Antarctic Cryoconite Microbial Communities To Light, Elizabeth A. Bagshaw, Jemma L. Wadham, Martyn Tranter, Rupert Perkins, Alistair Morgan, Christopher J. Williamson, Andrew G. Fountain, Sean Fitzsimons, Ashley Dubnick Jan 2016

Response Of Antarctic Cryoconite Microbial Communities To Light, Elizabeth A. Bagshaw, Jemma L. Wadham, Martyn Tranter, Rupert Perkins, Alistair Morgan, Christopher J. Williamson, Andrew G. Fountain, Sean Fitzsimons, Ashley Dubnick

Geology Faculty Publications and Presentations

Microbial communities on polar glacier surfaces are found dispersed on the ice surface, or concentrated in cryoconite holes and cryolakes, which are accumulations of debris covered by a layer of ice for some or all of the year. The ice lid limits the penetration of photosynthetically available radiation (PAR) to the sediment layer, since the ice attenuates up to 99% of incoming radiation. This suite of field and laboratory experiments demonstrates that PAR is an important control on primary production in cryoconite and cryolake ecosystems. Increased light intensity increased efficiency of primary production in controlled laboratory incubations of debris from …

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