Iowa State University GIS Support and Research Facility — This coverage contains polygons representing the Iowa Boundary, it was derived from a coverage of county boundaries, called COUNTIES, of the state of Iowa. COUNTIES...
Recreational Trails in the State of Iowa
Iowa State University GIS Support and Research Facility — This file represents the locations of trails in Iowa. The original trail file was created by the Iowa Department of Transportation (IDOT), and included developed...
International Nuclear Information System (INIS)
Greiter, M.
1992-01-01
This dissertation contains a collection of individual articles on various topics. Their significance in the corresponding field as well as connections between them are emphasized in a general and comprehensive introduction. In the first article, the author explores the consequences for macroscopic effective Lagrangians of assuming that the momentum density is proportional to the flow of conserved current. The universal corrections obtained for the macroscopic Lagrangian of a superconductor describe the London Hall effect, and provide a fully consistent derivation of it. In the second article, a heuristic principle is proposed for quantized Hall states: the existence and incompressibility of fractionally quantized Hall states is explained by an argument based on an adiabatic localization of magnetic flux, the process of trading uniform flux for an equal amount of fictitious flux attached to the particles. This principle is exactly implemented in the third article. For a certain class of model Hamiltonians, the author obtains Laughlin's Jastrow type wave functions explicitly from a filled Landau level, by smooth extrapolation in quantum statistics. The generalization of this analysis to the torus geometry shows that theorems restricting the possibilities of quantum statistics on closed surfaces are circumvented in the presence of a magnetic field. In the last article, the existence is proposed of a novel incompressible quantum liquid, a paired Hall state, at a half filled Landau level. This state arises adiabatically from free fermions in zero magnetic field, and reduces to a state previously proposed by Halperin in the limit of tightly bound pairs. It supports unusual excitations, including neutral fermions and charge e/4 anyons with statistical parameter θ = π/8
Hall viscosity of hierarchical quantum Hall states
Fremling, M.; Hansson, T. H.; Suorsa, J.
2014-03-01
Using methods based on conformal field theory, we construct model wave functions on a torus with arbitrary flat metric for all chiral states in the abelian quantum Hall hierarchy. These functions have no variational parameters, and they transform under the modular group in the same way as the multicomponent generalizations of the Laughlin wave functions. Assuming the absence of Berry phases upon adiabatic variations of the modular parameter τ, we calculate the quantum Hall viscosity and find it to be in agreement with the formula, given by Read, which relates the viscosity to the average orbital spin of the electrons. For the filling factor ν =2/5 Jain state, which is at the second level in the hierarchy, we compare our model wave function with the numerically obtained ground state of the Coulomb interaction Hamiltonian in the lowest Landau level, and find very good agreement in a large region of the complex τ plane. For the same example, we also numerically compute the Hall viscosity and find good agreement with the analytical result for both the model wave function and the numerically obtained Coulomb wave function. We argue that this supports the notion of a generalized plasma analogy that would ensure that wave functions obtained using the conformal field theory methods do not acquire Berry phases upon adiabatic evolution.
Recreational Assets in the State of Iowa
Iowa State University GIS Support and Research Facility — This dataset is meant to be a comprehensive database of recreational assets in public areas. Recreational assets are considered amenities provided to the public for...
The cooperative University of Iowa / Iowa State University MPH program.
Bickett-Weddle, Danelle A; Aquilino, Mary L; Roth, James A
2008-01-01
Public health is an important component of veterinary medicine. In the last 10 years, there has been growing recognition of the need to increase the number of veterinarians trained in public health. The Center for Food Security and Public Health (CFSPH) at Iowa State University (ISU), College of Veterinary Medicine, received a grant from the Centers for Disease Control and Prevention (CDC) to support veterinarians working at CFSPH while pursuing the Master of Public Health degree. CFSPH and ISU administrators worked with the University of Iowa (UI) College of Public Health to establish three cooperative programs for veterinarians to earn the MPH degree. This article describes how these programs were developed and how they operate. (1) Between 2002 and 2005, CFSPH used funds provided by the CDC to support 15 veterinarians as they worked for CFSPH and toward the MPH degree. As the program grew, distance-education methods such as the Internet, Polycom videoconferencing, and the Iowa Communications Network (ICN) were incorporated. (2) A concurrent DVM/MPH degree is now offered; students can complete both degrees in four years. As of January 2008, three students have received their DVM and MPH degrees and 16 students are enrolled in the program. (3) In June 2007, the UI and ISU launched a distance MPH program for veterinarians working in private practice, industry, and government. Eight veterinarians are participating in the program, which includes two two-week, in-person summer sessions, with the remainder of the coursework taken at a distance via the Internet.
Changing scene highlights III. [Iowa State University
Energy Technology Data Exchange (ETDEWEB)
Fassel, V. A.; Harl, Neil E.; Legvold, Sam; Ruedenberg, Klaus; Swenson, Clayton A.; Burnet, George; Fisher, Ray W.; Gschneidner, Karl A.; Hansen, Robert S.; Kliewer, Kenneth L.; Wildman, Ruth
1979-01-01
The research programs in progress at Ames Laboratory, Iowa State University, are reviewed: hydrogen (storage), materials, catalysts, TRISTAN (their laboratory isotope separator), coal preparation, coal classification, land reclamation (after surface mining, nitinol, neutron radiography, grain dust explosions, biomass conversion, etc). (LTC)
Inventory of Dams in the State of Iowa
Iowa State University GIS Support and Research Facility — Permitted dams in Iowa and associated attributes, as recorded by the Floodplain Section of the DNR. The dams regulated are those with the parameters listed below: a....
2015 State Geodatabase for Iowa
US Census Bureau, Department of Commerce — The 2015 TIGER Geodatabases are extracts of selected nation based and state based geographic and cartographic information from the U.S. Census Bureau's Master...
Marketing and Branding the Agronomy Major at Iowa State University
Miller, Bradley A.
2011-01-01
The decline of enrollments in agronomy programs across the United States has been a concern for more than a decade. In an effort to reverse this trend, the Agronomy Department at Iowa State University (ISU) launched the "I'm An Agronomist" marketing campaign in 2006. This article reports on these efforts and the change in the…
Conservation and Recreation Lands with Public Access in the State of Iowa
Iowa State University GIS Support and Research Facility — This dataset represents conservation and recreation lands in the state of Iowa. Boundaries of areas represent differences in ownership and managing agency of the...
Center for Catalysis at Iowa State University
Energy Technology Data Exchange (ETDEWEB)
Kraus, George A.
2006-10-17
The overall objective of this proposal is to enable Iowa State University to establish a Center that enjoys world-class stature and eventually enhances the economy through the transfer of innovation from the laboratory to the marketplace. The funds have been used to support experimental proposals from interdisciplinary research teams in areas related to catalysis and green chemistry. Specific focus areas included: • Catalytic conversion of renewable natural resources to industrial materials • Development of new catalysts for the oxidation or reduction of commodity chemicals • Use of enzymes and microorganisms in biocatalysis • Development of new, environmentally friendly reactions of industrial importance These focus areas intersect with barriers from the MYTP draft document. Specifically, section 2.4.3.1 Processing and Conversion has a list of bulleted items under Improved Chemical Conversions that includes new hydrogenation catalysts, milder oxidation catalysts, new catalysts for dehydration and selective bond cleavage catalysts. Specifically, the four sections are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D) All funded projects are part of a soybean or corn biorefinery. Two funded projects that have made significant progress toward goals of the MYTP draft document are: Catalysts to convert feedstocks with high fatty acid content to biodiesel (Kraus, Lin, Verkade) and Conversion of Glycerol into 1,3-Propanediol (Lin, Kraus). Currently, biodiesel is prepared using homogeneous base catalysis. However, as producers look for feedstocks other than soybean oil, such as waste restaurant oils and rendered animal fats, they have observed a large amount of free fatty acids contained in the feedstocks. Free fatty acids cannot be converted into biodiesel using homogeneous base-mediated processes. The CCAT catalyst system offers an integrated and cooperative catalytic
Measuring the Total Economic Value of State-Funded Higher Education in Iowa
Swenson, David A.
2011-01-01
This is an evaluation of the statewide total economic value of state-funded higher education in Iowa. The analysis is based on Fiscal Year 2010 final budgeted values for Iowa's three Board of Regents universities and their teaching hospital, as well as the state's 15 community colleges. Final budget year data were obtained from the respective state universities' web sites, from the Board of Regents, and from the Annual Condition of Iowa's Community Colleges, 2010, report published by the Iowa...
Digital Learning Compass: Distance Education State Almanac 2017. Iowa
Seaman, Julia E.; Seaman, Jeff
2017-01-01
This brief report uses data collected under the U.S. Department of Education's National Center for Educational Statistics (NCES) Integrated Postsecondary Education Data System (IPEDS) Fall Enrollment survey to highlight distance education data in the state of Iowa. The sample for this analysis is comprised of all active, degree-granting…
The Undergraduate Biomechanics Experience at Iowa State University.
Francis, Peter R.
This paper discusses the objectives of a program in biomechanics--the analysis of sports skills and movement--and the evolution of the biomechanics program at Iowa State University. The primary objective of such a course is to provide the student with the basic tools necessary for adequate analysis of human movement, with special emphasis upon…
2011-07-14
... modeling requirement for this SIP call should allow for the use of the modeling protocol developed by Iowa... is making a finding that the Iowa State Implementation Plan (SIP) is substantially inadequate to... ) in Muscatine County, Iowa. The specific SIP deficiencies needing revision are described below. EPA is...
Low enrichment fuel conversion for Iowa State University. Final report
International Nuclear Information System (INIS)
Bullen, D.B.; Wendt, S.E.
1996-01-01
The UTR-10 research and teaching reactor at Iowa State University (ISU) has been converted from high-enriched fuel (HEU) to low- enriched fuel (LEU) under Grant No. DE-FG702-87ER75360 from the Department of Energy (DOE). The original contract period was August 1, 1987 to July 31, 1989. The contract was extended to February 28, 1991 without additional funding. Because of delays in receiving the LEU fuel and the requirement for disassembly of the HEU assemblies, the contract was renewed first through May 31, 1992, then through May 31, 1993 with additional funding, and then again through July 31, 1994 with no additional funding. In mid-August the BMI cask was delivered to Iowa State. Preparations are underway to ship the HEU fuel when NRC license amendments for the cask are approved
Bimetric Theory of Fractional Quantum Hall States
Directory of Open Access Journals (Sweden)
Andrey Gromov
2017-11-01
Full Text Available We present a bimetric low-energy effective theory of fractional quantum Hall (FQH states that describes the topological properties and a gapped collective excitation, known as the Girvin-Macdonald-Platzman (GMP mode. The theory consists of a topological Chern-Simons action, coupled to a symmetric rank-2 tensor, and an action à la bimetric gravity, describing the gapped dynamics of a spin-2 mode. The theory is formulated in curved ambient space and is spatially covariant, which allows us to restrict the form of the effective action and the values of phenomenological coefficients. Using bimetric theory, we calculate the projected static structure factor up to the k^{6} order in the momentum expansion. To provide further support for the theory, we derive the long-wave limit of the GMP algebra, the dispersion relation of the GMP mode, and the Hall viscosity of FQH states. The particle-hole (PH transformation of the theory takes a very simple form, making the duality between FQH states and their PH conjugates manifest. We also comment on the possible applications to fractional Chern insulators, where closely related structures arise. It is shown that the familiar FQH observables acquire a curious geometric interpretation within the bimetric formalism.
Bimetric Theory of Fractional Quantum Hall States
Gromov, Andrey; Son, Dam Thanh
2017-10-01
We present a bimetric low-energy effective theory of fractional quantum Hall (FQH) states that describes the topological properties and a gapped collective excitation, known as the Girvin-Macdonald-Platzman (GMP) mode. The theory consists of a topological Chern-Simons action, coupled to a symmetric rank-2 tensor, and an action à la bimetric gravity, describing the gapped dynamics of a spin-2 mode. The theory is formulated in curved ambient space and is spatially covariant, which allows us to restrict the form of the effective action and the values of phenomenological coefficients. Using bimetric theory, we calculate the projected static structure factor up to the k6 order in the momentum expansion. To provide further support for the theory, we derive the long-wave limit of the GMP algebra, the dispersion relation of the GMP mode, and the Hall viscosity of FQH states. The particle-hole (PH) transformation of the theory takes a very simple form, making the duality between FQH states and their PH conjugates manifest. We also comment on the possible applications to fractional Chern insulators, where closely related structures arise. It is shown that the familiar FQH observables acquire a curious geometric interpretation within the bimetric formalism.
Valley-chiral quantum Hall state in graphene superlattice structure
Tian, H. Y.; Tao, W. W.; Wang, J.; Cui, Y. H.; Xu, N.; Huang, B. B.; Luo, G. X.; Hao, Y. H.
2016-05-01
We theoretically investigate the quantum Hall effect in a graphene superlattice (GS) system, in which the two valleys of graphene are coupled together. In the presence of a perpendicular magnetic field, an ordinary quantum Hall effect is found with the sequence σxy=ν e^2/h(ν=0,+/-1,+/-2,\\cdots) . At the zeroth Hall platform, a valley-chiral Hall state stemming from the single K or K' valley is found and it is localized only on one sample boundary contributing to the longitudinal conductance but not to the Hall conductivity. Our findings may shed light on the graphene-based valleytronics applications.
Properties of Nonabelian Quantum Hall States
Simon, Steven H.
2004-03-01
The quantum statistics of particles refers to the behavior of a multiparticle wavefunction under adiabatic interchange of two identical particles. While a three dimensional world affords the possibilities of Bosons or Fermions, the two dimensional world has more exotic possibilities such as Fractional and Nonabelian statistics (J. Frölich, in ``Nonperturbative Quantum Field Theory", ed, G. t'Hooft. 1988). The latter is perhaps the most interesting where the wavefunction obeys a ``nonabelian'' representation of the braid group - meaning that braiding A around B then B around C is not the same as braiding B around C then A around B. This property enables one to think about using these exotic systems for robust topological quantum computation (M. Freedman, A. Kitaev, et al, Bull Am Math Soc 40, 31 (2003)). Surprisingly, it is thought that quasiparticles excitations with such nonabelian statistics may actually exist in certain quantum Hall states that have already been observed. The most likely such candidate is the quantum Hall ν=5/2 state(R. L. Willett et al, Phys. Rev. Lett. 59, 1776-1779 (1987)), thought to be a so-called Moore-Read Pfaffian state(G. Moore and N. Read, Nucl Phys. B360 362 (1991)), which can be thought of as a p-wave paired superconducting state of composite fermions(M. Greiter, X. G. Wen, and F. Wilczek, PRL 66, 3205 (1991)). Using this superconducting analogy, we use a Chern-Simons field theory approach to make a number of predictions as to what experimental signatures one should expect for this state if it really is this Moore-Read state(K. Foster, N. Bonesteel, and S. H. Simon, PRL 91 046804 (2003)). We will then discuss how the nonabelian statistics can be explored in detail using a quantum monte-carlo approach (Y. Tserkovnyak and S. H. Simon, PRL 90 106802 (2003)), (I. Finkler, Y. Tserkovnyak, and S. H. Simon, work in progress.) that allows one to explicitly drag one particle around another and observe the change in the wavefunctions
Iowa state information handbook: formerly utilized sites remedial action program
International Nuclear Information System (INIS)
1981-01-01
This volume is one of a series produced under contract with the DOE, By Politech Corporation to develop a legislative and regulatory data base to assist the FUSRAP management in addressing the institutional and socioeconomic issues involved in carrying out the Formerly Utilized Sites Remedial Action Program. This Information Handbook series contains information about all relevant government agencies at the Federal and state levels, the pertinent programs they administer, each affected state legislature, and current Federal and state legislative and regulatory initiatives. This volume is a compilation of information about the state of Iowa. It contains: a description of the state executive branch structure; a summary of relevant state statutes and regulations; a description of the structure of the state legislature, identification of the officers and committee chairmen, and a summary of recent relevant legislative action; the full test of relevant statutes and regulations
Iowa state information handbook: formerly utilized sites remedial action program
Energy Technology Data Exchange (ETDEWEB)
None
1981-02-09
This volume is one of a series produced under contract with the DOE, By Politech Corporation to develop a legislative and regulatory data base to assist the FUSRAP management in addressing the institutional and socioeconomic issues involved in carrying out the Formerly Utilized Sites Remedial Action Program. This Information Handbook series contains information about all relevant government agencies at the Federal and state levels, the pertinent programs they administer, each affected state legislature, and current Federal and state legislative and regulatory initiatives. This volume is a compilation of information about the state of Iowa. It contains: a description of the state executive branch structure; a summary of relevant state statutes and regulations; a description of the structure of the state legislature, identification of the officers and committee chairmen, and a summary of recent relevant legislative action; the full test of relevant statutes and regulations.
2015-06-01
Several strategies are available to the Iowa Department of Transportation (IaDOT) for limiting : deterioration due to chloride-induced corrosion of embedded reinforcing bars in concrete bridge decks. : While the method most commonly used throughout t...
Work Life Balance and Job Satisfaction among Faculty at Iowa State University
Mukhtar, Farah
2012-01-01
This study utilized the existing database from the Iowa State University 2009-2010 COACHE Tenure-Track Job Satisfaction Survey Report to explore faculty work life balance and job satisfaction among academic disciplines at Iowa State University. The articulation of work and life, cast as work life balance, has become a key feature of much current…
Iowa State University GIS Support and Research Facility — This shape file represents Iowa Historic Cemeteries. Originally it was based on an Iowa DNR point file marking cemetery locations as found on 7.5 min. USGS quad...
General Land Office_GLO_Vegetation from the Years 1832 to 1859 of the State of Iowa
Iowa State University GIS Support and Research Facility — The Goverment Land Office (GLO) conducted the orginal public land survey of Iowa during the period 1832 to 1859. Deputy Surveyors and their assistants produced both...
Fractional quantum Hall states of atoms in optical lattices
International Nuclear Information System (INIS)
Soerensen, Anders S.; Demler, Eugene; Lukin, Mikhail D.
2005-01-01
We describe a method to create fractional quantum Hall states of atoms confined in optical lattices. We show that the dynamics of the atoms in the lattice is analogous to the motion of a charged particle in a magnetic field if an oscillating quadrupole potential is applied together with a periodic modulation of the tunneling between lattice sites. In a suitable parameter regime the ground state in the lattice is of the fractional quantum Hall type, and we show how these states can be reached by melting a Mott-insulator state in a superlattice potential. Finally, we discuss techniques to observe these strongly correlated states
Energy Technology Data Exchange (ETDEWEB)
1990-05-01
The proposed Department of Energy (DOE) action is financial and technical support of construction and initial operation of an agricultural commodity irradiator (principally for meat), employing a dual mode electron beam generator capable of producing x-rays, at the Iowa State University Linear Accelerator located at Ames, Iowa. The planned pilot commercial-scale facility would be used for the following activities: conducting irradiation research on agricultural commodities, principally meats; in the future, after the pilot phase, as schedules permit, possibly conducting research on other, non-edible materials; evaluating effects of irradiation on nutritional and sensory quality of agricultural products; demonstrating the efficiency of the process to control or eliminate pathogens, and/or to prolong the commodities' post-harvest shelf-life via control or elimination of bacteria, fungi, and/or insects; providing information to the public on the benefits, safety and risks of irradiated agricultural commodities; determining consumer acceptability of the irradiated products; providing data for use by regulatory agencies in developing protocols for various treatments of Iowa agricultural commodities; and training operators, maintenance and quality control technicians, scientists, engineers, and staff of regulatory agencies in agricultural commodity irradiation technology. 14 refs., 5 figs.
2011-02-22
... advance and available for prompt implementation once triggered. Section 110(k)(5) of the CAA provides that... Environmental protection, Air pollution control, Iowa, Particulate matter, State Implementation Plan. Dated...
All Known Water Wells in the State of Iowa (Public Version)
Iowa State University GIS Support and Research Facility — Combined database of all wells with uniform attributes from detailed individual well databases (see General and Entity Attribute sections of metadata for individual...
Iowa State Briefing Book for low-level radioactive waste management
International Nuclear Information System (INIS)
1981-08-01
The Iowa State Briefing Book is one of a series of state briefing books on low-level radioactive waste management practices. It has been prepared to assist state and federal agency officials in planning for safe low-level radioactive waste disposal. This report contains a profile of low-level radioactive waste generators in Iowa. The profile is the result of a survey of NRC licensees in Iowa. The briefing book also contains a comprehensive assessment of low-level radioactive waste management issues and concerns as defined by all major interested parties including industry, government, the media, and interest groups. The assessment was developed through personal communications with representatives of interested parties, and through a review of media sources. Lastly, the briefing book provides demographic and socioeconomic data and a discussion of relevant government agencies and activities, all of which may impact waste management practices in Iowa
A conformal field theory description of fractional quantum Hall states
Ardonne, E.
2002-01-01
In this thesis, we give a description of fractional quantum Hall states in terms of conformal field theory (CFT). As was known for a long time, the Laughlin states could be written in terms of correlators of chiral vertex operators of a c=1 CFT. It was shown by G. Moore and N. Read that more general
Spectroscopy of snake states using a graphene Hall bar
Energy Technology Data Exchange (ETDEWEB)
Milovanović, S. P., E-mail: slavisa.milovanovic@gmail.com; Ramezani Masir, M., E-mail: mrmphys@gmail.com; Peeters, F. M., E-mail: francois.peeters@ua.ac.be [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)
2013-12-02
An approach to observe snake states in a graphene Hall bar containing a pn-junction is proposed. The magnetic field dependence of the bend resistance in a ballistic graphene Hall bar structure containing a tilted pn-junction oscillates as a function of applied magnetic field. We show that each oscillation is due to a specific snake state that moves along the pn-interface. Furthermore, depending on the value of the magnetic field and applied potential, we can control the lead in which the electrons will end up and hence control the response of the system.
Iowa state heating oil and propane program: 1996--1997 winter heating season. Final report
International Nuclear Information System (INIS)
1997-05-01
The objective of the Iowa State Heating Oil and Propane Program is to develop a state-level, company-specific data collection effort so that retail price information on fuel oil and propane is collected by the staff of the Iowa Department of Natural Resources during the winter heating season. The second objective is to provide specific volume and retail price information to the US Department of Energy's (DOE's) Energy Information Administration on No. 2 heating oil and propane on a semi-monthly basis. This report summarizes the results of the residential No. 2 distillate fuel (home heating oil) and liquefied petroleum gas (propane) price survey over the 1996--1997 winter heating season in Iowa. The Iowa Department of Natural Resources conducted the survey under a cooperative financial assistance grant with the DOE Energy Information Administration (EIA)
Making Stuff Outreach at the Ames Laboratory and Iowa State University
Energy Technology Data Exchange (ETDEWEB)
Ament, Katherine; Karsjen, Steven; Leshem-Ackerman, Adah; King, Alexander
2011-04-01
The U. S. Department of Energy's Ames Laboratory in Ames, Iowa was a coalition partner for outreach activities connected with NOVA's Making Stuff television series on PBS. Volunteers affiliated with the Ames Laboratory and Iowa State University, with backgrounds in materials science, took part in activities including a science-themed Family Night at a local mall, Science Cafes at the Science Center of Iowa, teacher workshops, demonstrations at science nights in elementary and middle schools, and various other events. We describe a selection of the activities and present a summary of their outcomes and extent of their impact on Ames, Des Moines and the surrounding communities in Iowa. In Part 2, results of a volunteer attitude survey are presented, which shed some light on the volunteer experience and show how the volunteers participation in outreach activities has affected their views of materials education.
Imaging of Coulomb-Driven Quantum Hall Edge States
Lai, Keji; Kundhikanjana, Worasom; Kelly, Michael A.; Shen, Zhi-Xun; Shabani, Javad; Shayegan, Mansour
2011-01-01
The edges of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime are divided into alternating metallic and insulating strips, with their widths determined by the energy gaps of the QHE states and the electrostatic Coulomb
Iowa Intensive Archaeological Survey
Iowa State University GIS Support and Research Facility — This shape file contains intensive level archaeological survey areas for the state of Iowa. All intensive Phase I surveys that are submitted to the State Historic...
Iowa Water Center | Iowa Water Center
Home Iowa State University Extension Iowa Water Center Submitted by mollyd on April 24, 2012 - 09 :42 Advancing the state of water knowledge and management The Iowa Water Center is a part of a nationwide network of university-based water centers created to encourage interdisciplinary water research
Iowa | Midmarket Solar Policies in the United States | Solar Research |
Center Solar PV projects are eligible for no-interest financing for up to 50% of the financed project Energy Center administers financing and grant programs for solar photovoltaic (PV) projects. Solar cost (capped at $1,000,000). The Iowa Energy Center also offers several matching grants for project
Tunneling Spectroscopy of Quantum Hall States in Bilayer Graphene
Wang, Ke; Harzheim, Achim; Watanabe, Kenji; Taniguchi, Takashi; Kim, Philip
In the quantum Hall (QH) regime, ballistic conducting paths along the physical edges of a sample appear, leading to quantized Hall conductance and vanishing longitudinal magnetoconductance. These QH edge states are often described as ballistic compressible strips separated by insulating incompressible strips, the spatial profiles of which can be crucial in understanding the stability and emergence of interaction driven QH states. In this work, we present tunneling transport between two QH edge states in bilayer graphene. Employing locally gated device structure, we guide and control the separation between the QH edge states in bilayer graphene. Using resonant Landau level tunneling as a spectroscopy tool, we measure the energy gap in bilayer graphene as a function of displacement field and probe the emergence and evolution of incompressible strips.
Edge states in quantum Hall effect in graphene
International Nuclear Information System (INIS)
Gusynin, V.P.; Miransky, V.A.; Sharapov, S.G.; Shovkovy, I.A.
2008-01-01
We review recent results concerning the spectrum of edge states in the quantum Hall effect in graphene. In particular, special attention is paid to the derivation of the conditions under which gapless edge states exist in the spectrum of graphene with 'zigzag' and 'armchair' edges. It is found that in the case of a half-plane or a ribbon with zigzag edges, there are gapless edge states only when a spin gap dominates over a Dirac mass gap. In the case of a half-plane with an armchair edge, the existence of the gapless edge states depends on the specific type of Dirac mass gaps. The implications of these results for the dynamics in the quantum Hall effect in graphene are discussed
From rotating atomic rings to quantum Hall states.
Roncaglia, M; Rizzi, M; Dalibard, J
2011-01-01
Considerable efforts are currently devoted to the preparation of ultracold neutral atoms in the strongly correlated quantum Hall regime. However, the necessary angular momentum is very large and in experiments with rotating traps this means spinning frequencies extremely near to the deconfinement limit; consequently, the required control on parameters turns out to be too stringent. Here we propose instead to follow a dynamic path starting from the gas initially confined in a rotating ring. The large moment of inertia of the ring-shaped fluid facilitates the access to large angular momenta, corresponding to giant vortex states. The trapping potential is then adiabatically transformed into a harmonic confinement, which brings the interacting atomic gas in the desired quantum-Hall regime. We provide numerical evidence that for a broad range of initial angular frequencies, the giant-vortex state is adiabatically connected to the bosonic ν = 1/2 Laughlin state.
Fractional Quantum Hall States in a Ge Quantum Well.
Mironov, O A; d'Ambrumenil, N; Dobbie, A; Leadley, D R; Suslov, A V; Green, E
2016-04-29
Measurements of the Hall and dissipative conductivity of a strained Ge quantum well on a SiGe/(001)Si substrate in the quantum Hall regime are reported. We analyze the results in terms of thermally activated quantum tunneling of carriers from one internal edge state to another across saddle points in the long-range impurity potential. This shows that the gaps for different filling fractions closely follow the dependence predicted by theory. We also find that the estimates of the separation of the edge states at the saddle are in line with the expectations of an electrostatic model in the lowest spin-polarized Landau level (LL), but not in the spin-reversed LL where the density of quasiparticle states is not high enough to accommodate the carriers required.
Midwestern Higher Education Compact, 2014
2014-01-01
This report portrays various performance indicators that are intended to facilitate an assessment of the postsecondary education system in Iowa. Descriptive statistics are presented for Iowa and five other comparison states as well as the nation. Comparison states were selected according to the degree of similarity of population characteristics,…
Iowa State University GIS Support and Research Facility — This coverage maps alluvial deposits throughout Iowa. This generally would include areas of alluvial soils associated with modern streams that are identified on...
Iowa Bedrock Surface Elevation
Iowa State University GIS Support and Research Facility — This Digital Elevation Model (DEM) of the bedrock surface elevation in Iowa was compiled using all available data, principally information from GEOSAM, supplemented...
Iowa State University GIS Support and Research Facility — The ten ecoregions covering Iowa are part of a national ecoregion map that provides a geographic framework for research, management, and assessment of natural...
Iowa State University GIS Support and Research Facility — This coverage outlines the boundary of the Loess Hills in Iowa at 1:100,000 scale. Criteria applied to the delineation of the Loess Hills included drainage density,...
Iowa State University GIS Support and Research Facility — Sites contaminated by hazardous materials or wastes. These sites are those administered by the Contaminated Sites Section of Iowa DNR. Many are sites which are...
Iowa State University GIS Support and Research Facility — This fault coverage locates and identifies all currently known/interpreted fault zones in Iowa, that demonstrate offset of geologic units in exposure or subsurface...
Iowa Stratigraphic Data Points
Iowa State University GIS Support and Research Facility — The Iowa stratigraphic column consists of rock materials of varying geologic age that have been categorized into a shapefile for summarizing the 3 dimensional aspect...
Iowa State University GIS Support and Research Facility — The Map of the Elevation of the Bedrock Surface in Iowa was compiled using all available data, principally information from GEOSAM, supplemented with well and boring...
Composite fermion theory for bosonic quantum Hall states on lattices.
Möller, G; Cooper, N R
2009-09-04
We study the ground states of the Bose-Hubbard model in a uniform magnetic field, motivated by the physics of cold atomic gases on lattices at high vortex density. Mapping the bosons to composite fermions (CF) leads to the prediction of quantum Hall fluids that have no counterpart in the continuum. We construct trial states for these phases and test numerically the predictions of the CF model. We establish the existence of strongly correlated phases beyond those in the continuum limit and provide evidence for a wider scope of the composite fermion approach beyond its application to the lowest Landau level.
Paired quantum Hall states on noncommutative two-tori
Energy Technology Data Exchange (ETDEWEB)
Marotta, Vincenzo [Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' and INFN, Sezione di Napoli, Compl. universitario M. Sant' Angelo, Via Cinthia, 80126 Napoli (Italy); Naddeo, Adele, E-mail: naddeo@sa.infn.i [CNISM, Unita di Ricerca di Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Via Salvador Allende, 84081 Baronissi (Italy)
2010-08-01
By exploiting the notion of Morita equivalence for field theories on noncommutative tori and choosing rational values of the noncommutativity parameter theta (in appropriate units), a one-to-one correspondence between an Abelian noncommutative field theory (NCFT) and a non-Abelian theory of twisted fields on ordinary space can be established. Starting from this general result, we focus on the conformal field theory (CFT) describing a quantum Hall fluid (QHF) at paired states fillings nu=m/(pm+2) Cristofano et al. (2000) , recently obtained by means of m-reduction procedure, and show that it is the Morita equivalent of a NCFT. In this way we extend the construction proposed in Marotta and Naddeo (2008) for the Jain series nu=m/(2pm+1) . The case m=2 is explicitly discussed and the role of noncommutativity in the physics of quantum Hall bilayers is emphasized. Our results represent a step forward the construction of a new effective low energy description of certain condensed matter phenomena and help to clarify the relationship between noncommutativity and quantum Hall fluids.
Design Core Commonalities: A Study of the College of Design at Iowa State University
Venes, Jane
2015-01-01
This comprehensive study asks what a group of rather diverse disciplines have in common. It involves a cross-disciplinary examination of an entire college, the College of Design at Iowa State University. This research was intended to provide a sense of direction in developing and assessing possible core content. The reasoning was that material…
Imaging of Coulomb-Driven Quantum Hall Edge States
Lai, Keji
2011-10-01
The edges of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime are divided into alternating metallic and insulating strips, with their widths determined by the energy gaps of the QHE states and the electrostatic Coulomb interaction. Local probing of these submicrometer features, however, is challenging due to the buried 2DEG structures. Using a newly developed microwave impedance microscope, we demonstrate the real-space conductivity mapping of the edge and bulk states. The sizes, positions, and field dependence of the edge strips around the sample perimeter agree quantitatively with the self-consistent electrostatic picture. The evolution of microwave images as a function of magnetic fields provides rich microscopic information around the ν=2 QHE state. © 2011 American Physical Society.
Designated Wetlands and Setback Distances in Iowa
Iowa State University GIS Support and Research Facility — This GIS layer depicts wetlands designated for protection in the state of Iowa. Designated wetland is defined in Iowa Code subsection 459.102(21) as follows: 21....
Lake Beach Monitoring Locations in Iowa
Iowa State University GIS Support and Research Facility — Monitored state lake beach locations in Iowa. The Watershed Monitoring & Assessment Section of the Iowa DNR takes regular water samples at these listed beaches...
Superconducting Analogue of the Parafermion Fractional Quantum Hall States
Directory of Open Access Journals (Sweden)
Abolhassan Vaezi
2014-07-01
Full Text Available Read-Rezayi Z_{k} parafermion wave functions describe ν=2+(k/kM+2 fractional quantum Hall (FQH states. These states support non-Abelian excitations from which protected quantum gates can be designed. However, there is no experimental evidence for these non-Abelian anyons to date. In this paper, we study the ν=2/k FQH-superconductor heterostructure and find the superconducting analogue of the Z_{k} parafermion FQH state. Our main tool is the mapping of the FQH into coupled one-dimensional chains, each with a pair of counterpropagating modes. We show that by inducing intrachain pairing and charge preserving backscattering with identical couplings, the one-dimensional chains flow into gapless Z_{k} parafermions when k<4. By studying the effect of interchain coupling, we show that every parafermion mode becomes massive except for the two outermost ones. Thus, we achieve a fractional topological superconductor whose chiral edge state is described by a Z_{k} parafermion conformal field theory. For instance, we find that a ν=2/3 FQH in proximity to a superconductor produces a Z_{3} parafermion superconducting state. This state is topologically indistinguishable from the non-Abelian part of the ν=12/5 Read-Rezayi state. Both of these systems can host Fibonacci anyons capable of performing universal quantum computation through braiding operations.
Flux and Hall states in ABJM with dynamical flavors
Energy Technology Data Exchange (ETDEWEB)
Bea, Yago [Departamento de Física de Partículas and Instituto Galego de Física de Altas Enerxías,Universidade de Santiago de Compostela,E-15782 Santiago de Compostela (Spain); Jokela, Niko [Department of Physics and Helsinki Institute of Physics, University of Helsinki,P.O. Box 64, FIN-00014 (Finland); Lippert, Matthew [Institute for Theoretical Physics, University of Amsterdam,1098XH Amsterdam (Netherlands); Ramallo, Alfonso V. [Departamento de Física de Partículas and Instituto Galego de Física de Altas Enerxías,Universidade de Santiago de Compostela,E-15782 Santiago de Compostela (Spain); Zoakos, Dimitrios [Centro de Física do Porto and Departamento de Física e Astronomia,Faculdade de Ciências da Universidade do Porto,Rua do Campo Alegre 687, 4169-007 Porto (Portugal)
2015-03-02
We study the physics of probe D6-branes with quantized internal worldvolume flux in the ABJM background with unquenched massless flavors. This flux breaks parity in the (2+1)-dimensional gauge theory and allows quantum Hall states. Parity breaking is also explicitly demonstrated via the helicity dependence of the meson spectrum. We obtain general expressions for the conductivities, both in the gapped Minkowski embeddings and in the compressible black hole ones. These conductivities depend on the flux and contain a contribution from the dynamical flavors which can be regarded as an effect of intrinsic disorder due to quantum fluctuations of the fundamentals. We present an explicit, analytic family of supersymmetric solutions with nonzero charge density, electric, and magnetic fields.
Flux and Hall states in ABJM with dynamical flavors
Bea, Yago; Jokela, Niko; Lippert, Matthew; Ramallo, Alfonso V.; Zoakos, Dimitrios
2015-03-01
We study the physics of probe D6-branes with quantized internal worldvolume flux in the ABJM background with unquenched massless flavors. This flux breaks parity in the (2+1)-dimensional gauge theory and allows quantum Hall states. Parity breaking is also explicitly demonstrated via the helicity dependence of the meson spectrum. We obtain general expressions for the conductivities, both in the gapped Minkowski embeddings and in the compressible black hole ones. These conductivities depend on the flux and contain a contribution from the dynamical flavors which can be regarded as an effect of intrinsic disorder due to quantum fluctuations of the fundamentals. We present an explicit, analytic family of supersymmetric solutions with nonzero charge density, electric, and magnetic fields.
Edge states and integer quantum Hall effect in topological insulator thin films.
Zhang, Song-Bo; Lu, Hai-Zhou; Shen, Shun-Qing
2015-08-25
The integer quantum Hall effect is a topological state of quantum matter in two dimensions, and has recently been observed in three-dimensional topological insulator thin films. Here we study the Landau levels and edge states of surface Dirac fermions in topological insulators under strong magnetic field. We examine the formation of the quantum plateaux of the Hall conductance and find two different patterns, in one pattern the filling number covers all integers while only odd integers in the other. We focus on the quantum plateau closest to zero energy and demonstrate the breakdown of the quantum spin Hall effect resulting from structure inversion asymmetry. The phase diagrams of the quantum Hall states are presented as functions of magnetic field, gate voltage and chemical potential. This work establishes an intuitive picture of the edge states to understand the integer quantum Hall effect for Dirac electrons in topological insulator thin films.
Climate Change Consequences for Iowa'S Economy, Infrastructure, and Emergency Services
Swenson, David A.
2011-01-01
This is Chapter 6 in the state-mandated Regent's institution collaborative report, "Climate Change Impacts on Iowa, 2010: Report to the Governor and the Iowa General Assembly."Iowa's climate is changing, and that means Iowa's economy is changing. A changing Iowa economy will have consequences for agriculture, food production, Iowa's vaunted insurance agency, general energy use, Iowa's households, Iowa governments, and disaster services. This chapter profiles near and longer term consequences ...
Underground Storage Tanks in Iowa
Iowa State University GIS Support and Research Facility — Underground storage tank (UST) sites which store petroleum in Iowa. Includes sites which have been reported to DNR, and have active or removed underground storage...
Iowa State University GIS Support and Research Facility — A landscape is a collection of land shapes or land forms. Landform regions are a grouping of individual landscape features that have a common geomophology. In Iowa,...
Iowa State University's undergraduate minor, online graduate certificate and resource center in NDE
Bowler, Nicola; Larson, Brian F.; Gray, Joseph N.
2014-02-01
Nondestructive evaluation is a `niche' subject that is not yet offered as an undergraduate or graduate major in the United States. The undergraduate minor in NDE offered within the College of Engineering at Iowa State University (ISU) provides a unique opportunity for undergraduate aspiring engineers to obtain a qualification in the multi-disciplinary subject of NDE. The minor requires 16 credits of course work within which a core course and laboratory in NDE are compulsory. The industrial sponsors of Iowa State's Center for Nondestructive Evaluation, and others, strongly support the NDE minor and actively recruit students from this pool. Since 2007 the program has graduated 10 students per year and enrollment is rising. In 2011, ISU's College of Engineering established an online graduate certificate in NDE, accessible not only to campus-based students but also to practicing engineers via the web. The certificate teaches the fundamentals of three major NDE techniques; eddy-current, ultrasonic and X-ray methods. This paper describes the structure of these programs and plans for development of an online, coursework-only, Master of Engineering in NDE and thesis-based Master of Science degrees in NDE.
Single electron probes of fractional quantum hall states
Venkatachalam, Vivek
When electrons are confined to a two dimensional layer with a perpendicular applied magnetic field, such that the ratio of electrons to flux quanta (nu) is a small integer or simple rational value, these electrons condense into remarkable new phases of matter that are strikingly different from the metallic electron gas that exists in the absence of a magnetic field. These phases, called integer or fractional quantum Hall (IQH or FQH) states, appear to be conventional insulators in their bulk, but behave as a dissipationless metal along their edge. Furthermore, electrical measurements of such a system are largely insensitive to the detailed geometry of how the system is contacted or even how large the system is... only the order in which contacts are made appears to matter. This insensitivity to local geometry has since appeared in a number of other two and three dimensional systems, earning them the classification of "topological insulators" and prompting an enormous experimental and theoretical effort to understand their properties and perhaps manipulate these properties to create robust quantum information processors. The focus of this thesis will be two experiments designed to elucidate remarkable properties of the metallic edge and insulating bulk of certain FQH systems. To study such systems, we can use mesoscopic devices known as single electron transistors (SETs). These devices operate by watching single electrons hop into and out of a confining box and into a nearby wire (for measurement). If it is initially unfavorable for an electron to leave the box, it can be made favorable by bringing another charge nearby, modifying the energy of the confined electron and pushing it out of the box and into the nearby wire. In this way, the SET can measure nearby charges. Alternatively, we can heat up the nearby wire to make it easier for electrons to enter and leave the box. In this way, the SET is a sensitive thermometer. First, by operating the SET as an
Prediction of a quantum anomalous Hall state in Co-decorated silicene
Kaloni, Thaneshwor P.
2014-01-09
Based on first-principles calculations, we demonstrate that Co-decorated silicene can host a quantum anomalous Hall state. The exchange field induced by the Co atoms combined with the strong spin-orbit coupling of the silicene opens a nontrivial band gap at the K point. As compared to other transition metals, Co-decorated silicene is unique in this respect, since usually hybridization and spin-polarization induced in the silicene suppress a quantum anomalous Hall state.
Prediction of a quantum anomalous Hall state in Co-decorated silicene
Kaloni, Thaneshwor P.; Schwingenschlö gl, Udo; Singh, Nirpendra
2014-01-01
Based on first-principles calculations, we demonstrate that Co-decorated silicene can host a quantum anomalous Hall state. The exchange field induced by the Co atoms combined with the strong spin-orbit coupling of the silicene opens a nontrivial band gap at the K point. As compared to other transition metals, Co-decorated silicene is unique in this respect, since usually hybridization and spin-polarization induced in the silicene suppress a quantum anomalous Hall state.
Tunneling between edge states in a quantum spin Hall system.
Ström, Anders; Johannesson, Henrik
2009-03-06
We analyze a quantum spin Hall device with a point contact connecting two of its edges. The contact supports a net spin tunneling current that can be probed experimentally via a two-terminal resistance measurement. We find that the low-bias tunneling current and the differential conductance exhibit scaling with voltage and temperature that depend nonlinearly on the strength of the electron-electron interaction.
Strong quasi-particle tunneling study in the paired quantum Hall states
Nomura, Kentaro; Yoshioka, Daijiro
2001-01-01
The quasi-particle tunneling phenomena in the paired fractional quantum Hall states are studied. A single point-contact system is first considered. Because of relevancy of the quasi-particle tunneling term, the strong tunneling regime should be investigated. Using the instanton method it is shown that the strong quasi-particle tunneling regime is described as the weak electron tunneling regime effectively. Expanding to the network model the paired quantum Hall liquid to insulator transition i...
2010-01-26
... DEPARTMENT OF THE TREASURY Internal Revenue Service Open Meeting of the Area 5 Taxpayer Advocacy Panel (Including the States of Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, and Texas) AGENCY... the Federal Advisory Committee Act, 5 U.S.C. App. (1988) that a meeting of the Area 5 Taxpayer...
2010-07-08
... DEPARTMENT OF THE TREASURY Internal Revenue Service Open Meeting of the Area 5 Taxpayer Advocacy Panel (Including the States of Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, and Texas) AGENCY... Federal Advisory Committee Act, 5 U.S.C. App. (1988) that a meeting of the Area 5 Taxpayer Advocacy Panel...
2010-10-12
... DEPARTMENT OF THE TREASURY Internal Revenue Service Open Meeting of the Area 5 Taxpayer Advocacy Panel (Including the States of Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, and Texas) AGENCY... the Federal Advisory Committee Act, 5 U.S.C. App. (1988) that a meeting of the Area 5 Taxpayer...
2010-03-09
... DEPARTMENT OF THE TREASURY Internal Revenue Service Open Meeting of the Area 5 Taxpayer Advocacy Panel (Including the States of Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, and Texas) AGENCY... Federal Advisory Committee Act, 5 U.S.C. App. (1988) that a meeting of the Area 5 Taxpayer Advocacy Panel...
2010-08-04
... DEPARTMENT OF THE TREASURY Internal Revenue Service Open Meeting of the Area 5 Taxpayer Advocacy Panel (including the states of Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, and Texas) AGENCY... the Federal Advisory Committee Act, 5 U.S.C. App. (1988) that a meeting of the Area 5 Taxpayer...
2010-09-10
... DEPARTMENT OF THE TREASURY Internal Revenue Service Open Meeting of the Area 5 Taxpayer Advocacy Panel (Including the States of Iowa, Kansas, Minnesota, Missouri, Nebraska, Oklahoma, and Texas) AGENCY... the Federal Advisory Committee Act, 5 U.S.C. App. (1988) that a meeting of the Area 5 Taxpayer...
2011-05-13
... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL11-39-000] Gregory R. Swecker, Beverly F. Swecker v. Midland Power Cooperative, State of Iowa; Notice of Complaint Take notice... 1978 (PURPA),\\1\\ Gregory R. Swecker and Beverly F. Swecker (Complainants) filed a petition requesting...
Gate-Controlled Transmission of Quantum Hall Edge States in Bilayer Graphene.
Li, Jing; Wen, Hua; Watanabe, Kenji; Taniguchi, Takashi; Zhu, Jun
2018-02-02
The edge states of the quantum Hall and fractional quantum Hall effect of a two-dimensional electron gas carry key information of the bulk excitations. Here we demonstrate gate-controlled transmission of edge states in bilayer graphene through a potential barrier with tunable height. The backscattering rate is continuously varied from 0 to close to 1, with fractional quantized values corresponding to the sequential complete backscattering of individual modes. Our experiments demonstrate the feasibility to controllably manipulate edge states in bilayer graphene, thus opening the door to more complex experiments.
Gate-Controlled Transmission of Quantum Hall Edge States in Bilayer Graphene
Li, Jing; Wen, Hua; Watanabe, Kenji; Taniguchi, Takashi; Zhu, Jun
2018-02-01
The edge states of the quantum Hall and fractional quantum Hall effect of a two-dimensional electron gas carry key information of the bulk excitations. Here we demonstrate gate-controlled transmission of edge states in bilayer graphene through a potential barrier with tunable height. The backscattering rate is continuously varied from 0 to close to 1, with fractional quantized values corresponding to the sequential complete backscattering of individual modes. Our experiments demonstrate the feasibility to controllably manipulate edge states in bilayer graphene, thus opening the door to more complex experiments.
Levitation of current carrying states in the lattice model for the integer quantum Hall effect.
Koschny, T; Potempa, H; Schweitzer, L
2001-04-23
The disorder driven quantum Hall to insulator transition is investigated for a two-dimensional lattice model. The Hall conductivity and the localization length are calculated numerically near the transition. For uncorrelated and weakly correlated disorder potentials the current carrying states are annihilated by the negative Chern states originating from the band center. In the presence of correlated disorder potentials with correlation length larger than approximately half the lattice constant the floating up of the critical states in energy without merging is observed. This behavior is similar to the levitation scenario proposed for the continuum model.
Iowa State University GIS Support and Research Facility — This draft dataset consists of all ditches or channelized pieces of stream that could be identified using three input datasets; namely the1:24,000 National...
Iowa State University GIS Support and Research Facility — The Natural Resources Geographic Information System (NRGIS) Library is a Geographic Information System (GIS) repository developed and maintained by the GIS Section...
Iowa State University GIS Support and Research Facility — This coverage contains points that represent populated places, ie. cities, towns, villages or any other named place where people live. The coverage was developed...
Iowa State University GIS Support and Research Facility — The unsewered communities file was originally conceived as a representation of communities without a municipal sewer system or on-site septic systems. The selection...
2011-07-22
The Iowa Department of Transportation and the offices of Motor : Vehicle Enforcement, Motor Carrier Services, Vehicle Services, : and Driver Services want to make your travels into and through : our state safer, legal and less complicated. : This boo...
Iowa State University GIS Support and Research Facility — Point locations of geologic samples/files in the IGS repository. Types of samples include well cuttings, outcrop samples, cores, drillers logs, measured sections,...
Iowa State University GIS Support and Research Facility — The bedrock geologic map portrays the current interpretation of the distribution of various bedrock stratigraphic units present at the bedrock surface. The bedrock...
Charged spin textures over the Moore-Read quantum Hall state
Romers, J.C.; Huijse, L.; Schoutens, K.
2011-01-01
We study the composite Charged Spin Texture (CST) over the Moore-Read quantum Hall state that arises when a collection of elementary CSTs are moved to the same location. Following an algebraic approach based on the characteristic pair correlations of the Moore- Read state, we and that the resulting
Sixteen-state magnetic memory based on the extraordinary Hall effect
International Nuclear Information System (INIS)
Segal, A.; Karpovski, M.; Gerber, A.
2012-01-01
We report on a proof-of-concept study of split-cell magnetic storage in which multi-bit magnetic memory cells are composed of several multilevel ferromagnetic dots with perpendicular magnetic anisotropy. Extraordinary Hall effect is used for reading the data. Feasibility of the approach is supported by realization of four-, eight- and sixteen- state cells. - Highlights: ► We propose a novel structure of multi-bit magnetic random access memory. ► Each cell contains several interconnected storage dots. ► Extraordinary Hall effect is used for reading the data. ► Four-, eight- and sixteen-state cells have been realized.
International Nuclear Information System (INIS)
Tomimatsu, Toru; Shirai, Shota; Hashimoto, Katsushi; Sato, Ken; Hirayama, Yoshiro
2015-01-01
Electric-field-induced nuclear resonance (NER: nuclear electric resonance) involving quantum Hall states (QHSs) was studied at various filling factors by exploiting changes in nuclear spins polarized at quantum Hall breakdown. Distinct from the magnetic dipole interaction in nuclear magnetic resonance, the interaction of the electric-field gradient with the electric quadrupole moment plays the dominant role in the NER mechanism. The magnitude of the NER signal strongly depends on whether electronic states are localized or extended. This indicates that NER is sensitive to the screening capability of the electric field associated with QHSs
Cost Effectiveness of ASHRAE Standard 90.1-2013 for the State of Iowa
Energy Technology Data Exchange (ETDEWEB)
Hart, Philip R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Athalye, Rahul A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Xie, YuLong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhuge, Jing Wei [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Halverson, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Loper, Susan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rosenberg, Michael I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richman, Eric E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2015-12-01
Moving to the ASHRAE Standard 90.1-2013 (ASHRAE 2013) edition from Standard 90.1-2010 (ASHRAE 2010) is cost-effective for the State of Iowa. The table below shows the state-wide economic impact of upgrading to Standard 90.1-2013 in terms of the annual energy cost savings in dollars per square foot, additional construction cost per square foot required by the upgrade, and life-cycle cost (LCC) per square foot. These results are weighted averages for all building types in all climate zones in the state, based on weightings shown in Table 4. The methodology used for this analysis is consistent with the methodology used in the national cost-effectiveness analysis. Additional results and details on the methodology are presented in the following sections. The report provides analysis of two LCC scenarios: Scenario 1, representing publicly-owned buildings, considers initial costs, energy costs, maintenance costs, and replacement costs—without borrowing or taxes. Scenario 2, representing privately-owned buildings, adds borrowing costs and tax impacts.
Public Land Survey Township Boundaries of Iowa
Iowa State University GIS Support and Research Facility — This coverage contains polygons representing the PLSS township boundaries of the state of Iowa. TOWNSHIP was developed from a set of 99 individual county coverages...
Iowa Kids Count 2011: Trends in the Well-Being of Iowa Children
Child and Family Policy Center, 2012
2012-01-01
This most recent Iowa Kids Count data book, "Iowa Kids Count 2011: Trends in the Well-Being of Iowa Children," provides data on 20 different indicators of child and family well-being at the United States, Iowa, substate and county level. The annually produced data book presents health, education, welfare and economic data including…
Iowa Kids Count 2009: Trends in the Well-Being of Iowa Children
Child and Family Policy Center, 2010
2010-01-01
This latest annually produced Iowa Kids Count data book, "Iowa Kids Count 2009: Trends in the Well-Being of Iowa Children," provides data on 18 different indicators of child and family well-being at the United States, Iowa, substate and county-level. The 18 indicators presented in the data book contain an expanse of data from economic,…
Iowa Kids Count 2010: Trends in the Well-Being of Iowa Children
Child and Family Policy Center, 2011
2011-01-01
This most recent Iowa Kids Count data book, "Iowa Kids Count 2010: Trends in the Well-Being of Iowa Children," provides data on 20 different indicators of child and family well-being at the United States, Iowa, substate and county level. The annually produced data book presents health, education, welfare and economic data including…
2013 Iowa DOT engineering intern development and management program.
2013-11-01
The Institute for Transportation (InTrans) at Iowa State University (ISU) developed an internship mentoring program in collaboration : with the Iowa Department of Transportation (DOT) to provide additional mentorship to both student interns and Iowa ...
Interplay between snake and quantum edge states in a graphene Hall bar with a pn-junction
Energy Technology Data Exchange (ETDEWEB)
Milovanović, S. P., E-mail: slavisa.milovanovic@uantwerpen.be; Peeters, F. M., E-mail: francois.peeters@uantwerpen.be [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Ramezani Masir, M., E-mail: mrmphys@gmail.com [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Department of Physics, University of Texas at Austin, 2515 Speedway, C1600 Austin, Texas 78712-1192 (United States)
2014-09-22
The magneto- and Hall resistance of a locally gated cross shaped graphene Hall bar is calculated. The edge of the top gate is placed diagonally across the center of the Hall cross. Four-probe resistance is calculated using the Landauer-Büttiker formalism, while the transmission coefficients are obtained using the non-equilibrium Green's function approach. The interplay between transport due to edge channels and snake states is investigated. When two edge channels are occupied, we predict oscillations in the Hall and the bend resistance as function of the magnetic field, which are a consequence of quantum interference between the occupied snake states.
Circularly polarized near-field optical mapping of spin-resolved quantum Hall chiral edge states.
Mamyouda, Syuhei; Ito, Hironori; Shibata, Yusuke; Kashiwaya, Satoshi; Yamaguchi, Masumi; Akazaki, Tatsushi; Tamura, Hiroyuki; Ootuka, Youiti; Nomura, Shintaro
2015-04-08
We have successfully developed a circularly polarized near-field scanning optical microscope (NSOM) that enables us to irradiate circularly polarized light with spatial resolution below the diffraction limit. As a demonstration, we perform real-space mapping of the quantum Hall chiral edge states near the edge of a Hall-bar structure by injecting spin polarized electrons optically at low temperature. The obtained real-space mappings show that spin-polarized electrons are injected optically to the two-dimensional electron layer. Our general method to locally inject spins using a circularly polarized NSOM should be broadly applicable to characterize a variety of nanomaterials and nanostructures.
Mark D. Nelson; Charles J. Barnett; Matt Brewer; Brett J. Butler; Susan J. Crocker; Grant M. Domke; Dale D. Gormanson; Cassandra M. Kurtz; Tonya W. Lister; Stephen Matthews; William H. McWilliams; Dacia M. Meneguzzo; Patrick D. Miles; Randall S. Morin; Ronald J. Piva; Rachel Riemann; James E. Smith; Brian F. Walters; Jim Westfall; Christopher W. Woodall
2016-01-01
The third full annual inventory of Iowa's forests (2009-2013) indicates that just under 3 million acres of forest land exists in the State, 81 percent of which is in family forest ownership. Almost all of Iowa's forest land is timberland (96 percent), with an average volume of more than 1,000 cubic feet of growing stock per acre on timberland and more than 1,...
Spin-singlet quantum Hall states and Jack polynomials with a prescribed symmetry
International Nuclear Information System (INIS)
Estienne, Benoit; Bernevig, B. Andrei
2012-01-01
We show that a large class of bosonic spin-singlet Fractional Quantum Hall model wavefunctions and their quasihole excitations can be written in terms of Jack polynomials with a prescribed symmetry. Our approach describes new spin-singlet quantum Hall states at filling fraction ν=(2k)/(2r-1) and generalizes the (k,r) spin-polarized Jack polynomial states. The NASS and Halperin spin-singlet states emerge as specific cases of our construction. The polynomials express many-body states which contain configurations obtained from a root partition through a generalized squeezing procedure involving spin and orbital degrees of freedom. The corresponding generalized Pauli principle for root partitions is obtained, allowing for counting of the quasihole states. We also extract the central charge and quasihole scaling dimension, and propose a conjecture for the underlying CFT of the (k,r) spin-singlet Jack states.
On the conductance sum rule for the hierarchical edge states of the fractional quantum hall effect
International Nuclear Information System (INIS)
Ma Zhongshui; Chen Yixin; Su Zhaobin.
1993-09-01
The conductance sum rule for the hierarchical edge channel currents of a Fractional Quantum Hall Effect state is derived analytically within the Haldane-Halperin hierarchy scheme. We provide also an intuitive interpretation for the hierarchical drift velocities of the edge excitations. (author). 12 refs
Final Report: An Undergraduate Minor in Wind Energy at Iowa State University
Energy Technology Data Exchange (ETDEWEB)
James McCalley
2012-11-14
This report describes an undergraduate minor program in wind energy that has been developed at Iowa State University. The minor program targets engineering and meteorology students and was developed to provide interested students with focused technical expertise in wind energy science and engineering, to increase their employability and ultimate effectiveness in this growing industry. The report describes the requirements of the minor program and courses that fulfill those requirements. Five new courses directly addressing wind energy have been developed. Topical descriptions for these five courses are provided in this report. Six industry experts in various aspects of wind energy science and engineering reviewed the wind energy minor program and provided detailed comments on the program structure, the content of the courses, and the employability in the wind energy industry of students who complete the program. The general consensus is that the program is well structured, the course content is highly relevant, and students who complete it will be highly employable in the wind energy industry. The detailed comments of the reviewers are included in the report.
On the ground state for fractional quantum hall effect
International Nuclear Information System (INIS)
Jellal, A.
1998-09-01
In the present letter, we investigate the ground state wave function for an explicit model of electrons in an external magnetic field with specific inter-particle interactions. The excitation states of this model are also given. (author)
Dams and Obstructions along Iowa's Canoe Routes
Iowa State University GIS Support and Research Facility — This dataset represents obstruction to canoe and boat users of the canoe routes of Iowa. This may represent actual dams, rock dams (natural or man made), large...
Parabolic Dunes Landform Features of Iowa
Iowa State University GIS Support and Research Facility — A landscape is a collection of land shapes or land forms. Landform Regions are a grouping of individual landscape features that have a common geomophology. In Iowa,...
Lineated Inliers Landform Features of Iowa
Iowa State University GIS Support and Research Facility — A landscape is a collection of land shapes or land forms. Landform regions are a grouping of individual landscape features that have a common geomophology. In Iowa,...
Paha Ridges Landform Features of Iowa
Iowa State University GIS Support and Research Facility — A landscape is a collection of land shapes or land forms. Landform regions are a grouping of individual landscape features that have a common geomophology. In Iowa,...
Lineated Ridges Landform Features of Iowa
Iowa State University GIS Support and Research Facility — A landscape is a collection of land shapes or land forms. Landform Regions are a grouping of individual landscape features that have a common geomophology. In Iowa,...
Shot-noise evidence of fractional quasiparticle creation in a local fractional quantum Hall state.
Hashisaka, Masayuki; Ota, Tomoaki; Muraki, Koji; Fujisawa, Toshimasa
2015-02-06
We experimentally identify fractional quasiparticle creation in a tunneling process through a local fractional quantum Hall (FQH) state. The local FQH state is prepared in a low-density region near a quantum point contact in an integer quantum Hall (IQH) system. Shot-noise measurements reveal a clear transition from elementary-charge tunneling at low bias to fractional-charge tunneling at high bias. The fractional shot noise is proportional to T(1)(1-T(1)) over a wide range of T(1), where T(1) is the transmission probability of the IQH edge channel. This binomial distribution indicates that fractional quasiparticles emerge from the IQH state to be transmitted through the local FQH state. The study of this tunneling process enables us to elucidate the dynamics of Laughlin quasiparticles in FQH systems.
Iowa's forests 1999-2003 (Part A)
Earl C. Leatherberry; W. Keith Moser; Charles Perry; Christopher Woodall; Edward Jespen; Steve Pennington; Aron Flickinger
2006-01-01
The first completed annual inventory of Iowa?s forests reports more than 2.6 million acres, nearly matching what was present in 1954. Most of Iowa?s forest stands are fully or moderately stocked, suggesting that for the near term stands are capable of supplying timber for the State?s wood products industry. The increasing number of shade-tolerant species may lead to...
Gate-controlled tunneling of quantum Hall edge states in bilayer graphene
Zhu, Jun; Li, Jing; Wen, Hua
Controlled tunneling of integer and fractional quantum Hall edge states provides a powerful tool to probe the physics of 1D systems and exotic particle statistics. Experiments in GaAs 2DEGs employ either a quantum point contact or a line junction tunnel barrier. It is generally difficult to independently control the filling factors νL and νR on the two sides of the barrier. Here we show that in bilayer graphene both νL and νR as well as their Landau level structures can be independently controlled using a dual-split-gate structure. In addition, the height of the line-junction tunnel barrier implemented in our experiments is tunable via a 5th gate. By measuring the tunneling resistance across the junction RT we examine the equilibration of the edge states in a variety of νL/νR scenarios and under different barrier heights. Edge states from both sides are fully mixed in the case of a low barrier. As the barrier height increases, we observe plateaus in RT that correspond to sequential complete backscattering of edge states. Gate-controlled manipulation of edge states offers a new angle to the exploration of quantum Hall magnetism and fractional quantum Hall effect in bilayer graphene.
International Nuclear Information System (INIS)
Ogita, M.; Nakao, M.; Singh, C.D.; Mogi, I.; Awaji, S.
2004-01-01
An AC-DC method has been proposed for simultaneous measurements of Hall effect and magnetoresistance effect in solid and liquid state of Ga and Hg metals. In low magnetic field Hall signal in solid state is proportional to magnetic field B, while in liquid state Hall signal is affected by magnetoresistance effect. It has been found that magnetoresistance has a B 2 dependence on magnetic field and affects the Hall signal. In high magnetic field, the Hall effect in liquid state is affected by a very large magnetoresistance effect compared in solid state. The magnetoresistance effect in liquid state is higher than solid state
Excitation gap of fractal quantum hall states in graphene
International Nuclear Information System (INIS)
Luo, Wenchen; Chakraborty, Tapash
2016-01-01
In the presence of a magnetic field and an external periodic potential the Landau level spectrum of a two-dimensional electron gas exhibits a fractal pattern in the energy spectrum which is described as the Hofstadter’s butterfly. In this work, we develop a Hartree–Fock theory to deal with the electron-electron interaction in the Hofstadter’s butterfly state in a finite-size graphene with periodic boundary conditions, where we include both spin and valley degrees of freedom. We then treat the butterfly state as an electron crystal so that we could obtain the order parameters of the crystal in the momentum space and also in an infinite sample. A phase transition between the liquid phase and the fractal crystal phase can be observed. The excitation gaps obtained in the infinite sample is comparable to those in the finite-size study, and agree with a recent experimental observation. (paper)
Directory of Open Access Journals (Sweden)
Netanel H. Lindner
2012-10-01
Full Text Available We study the non-Abelian statistics characterizing systems where counterpropagating gapless modes on the edges of fractional quantum Hall states are gapped by proximity coupling to superconductors and ferromagnets. The most transparent example is that of a fractional quantum spin Hall state, in which electrons of one spin direction occupy a fractional quantum Hall state of ν=1/m, while electrons of the opposite spin occupy a similar state with ν=-1/m. However, we also propose other examples of such systems, which are easier to realize experimentally. We find that each interface between a region on the edge coupled to a superconductor and a region coupled to a ferromagnet corresponds to a non-Abelian anyon of quantum dimension sqrt[2m]. We calculate the unitary transformations that are associated with the braiding of these anyons, and we show that they are able to realize a richer set of non-Abelian representations of the braid group than the set realized by non-Abelian anyons based on Majorana fermions. We carry out this calculation both explicitly and by applying general considerations. Finally, we show that topological manipulations with these anyons cannot realize universal quantum computation.
SO(8) fermion dynamical symmetry and strongly correlated quantum Hall states in monolayer graphene
Wu, Lian-Ao; Murphy, Matthew; Guidry, Mike
2017-03-01
A formalism is presented for treating strongly correlated graphene quantum Hall states in terms of an SO(8) fermion dynamical symmetry that includes pairing as well as particle-hole generators. The graphene SO(8) algebra is isomorphic to an SO(8) algebra that has found broad application in nuclear physics, albeit with physically very different generators, and exhibits a strong formal similarity to SU(4) symmetries that have been proposed to describe high-temperature superconductors. The well-known SU(4) symmetry of quantum Hall ferromagnetism for single-layer graphene is recovered as one subgroup of SO(8), but the dynamical symmetry structure associated with the full set of SO(8) subgroup chains extends quantum Hall ferromagnetism and allows analytical many-body solutions for a rich set of collective states exhibiting spontaneously broken symmetry that may be important for the low-energy physics of graphene in strong magnetic fields. The SO(8) symmetry permits a natural definition of generalized coherent states that correspond to symmetry-constrained Hartree-Fock-Bogoliubov solutions, or equivalently a microscopically derived Ginzburg-Landau formalism, exhibiting the interplay between competing spontaneously broken symmetries in determining the ground state.
Parameswaran, S A; Kivelson, S A; Shankar, R; Sondhi, S L; Spivak, B Z
2012-12-07
We study the structure of Bogoliubov quasiparticles, bogolons, the fermionic excitations of paired superfluids that arise from fermion (BCS) pairing, including neutral superfluids, superconductors, and paired quantum Hall states. The naive construction of a stationary quasiparticle in which the deformation of the pair field is neglected leads to a contradiction: it carries a net electrical current even though it does not move. However, treating the pair field self-consistently resolves this problem: in a neutral superfluid, a dipolar current pattern is associated with the quasiparticle for which the total current vanishes. When Maxwell electrodynamics is included, as appropriate to a superconductor, this pattern is confined over a penetration depth. For paired quantum Hall states of composite fermions, the Maxwell term is replaced by a Chern-Simons term, which leads to a dipolar charge distribution and consequently to a dipolar current pattern.
Quantum spin Hall states in graphene interacting with WS2 or WSe2
Kaloni, T. P.
2014-12-08
In the framework of first-principles calculations, we investigate the structural and electronic properties of graphene in contact with as well as sandwiched between WS2 and WSe2 monolayers. We report the modification of the band characteristics due to the interaction at the interface and demonstrate that the presence of the dichalcogenide results in quantum spin Hall states in the absence of a magnetic field.
Quantum spin Hall states in graphene interacting with WS2 or WSe2
Kaloni, T. P.; Kou, L.; Frauenheim, T.; Schwingenschlö gl, Udo
2014-01-01
In the framework of first-principles calculations, we investigate the structural and electronic properties of graphene in contact with as well as sandwiched between WS2 and WSe2 monolayers. We report the modification of the band characteristics due to the interaction at the interface and demonstrate that the presence of the dichalcogenide results in quantum spin Hall states in the absence of a magnetic field.
Iowa's forest resources in 2003
Earl C. Leatherberry; Gary J. Brand; Steve Pennington
2005-01-01
Reports the initial results of all five annual panels (1999-2003) of the fourth inventory of Iowa`s forest resources, the first annual inventory of the State. Includes information on forest area; volume; biomass; growth, mortality, and removals; and health.
Realization of the Axion Insulator State in Quantum Anomalous Hall Sandwich Heterostructures
Xiao, Di; Jiang, Jue; Shin, Jae-Ho; Wang, Wenbo; Wang, Fei; Zhao, Yi-Fan; Liu, Chaoxing; Wu, Weida; Chan, Moses H. W.; Samarth, Nitin; Chang, Cui-Zu
2018-02-01
The "magnetoelectric effect" arises from the coupling between magnetic and electric properties in materials. The Z2 invariant of topological insulators (TIs) leads to a quantized version of this phenomenon, known as the topological magnetoelectric (TME) effect. This effect can be realized in a new topological phase called an "axion insulator" whose surface states are all gapped but the interior still obeys time reversal symmetry. We demonstrate such a phase using electrical transport measurements in a quantum anomalous Hall (QAH) sandwich heterostructure, in which two compositionally different magnetic TI layers are separated by an undoped TI layer. Magnetic force microscopy images of the same sample reveal sequential magnetization reversals of the top and bottom layers at different coercive fields, a consequence of the weak interlayer exchange coupling due to the spacer. When the magnetization is antiparallel, both the Hall resistance and Hall conductance show zero plateaus, accompanied by a large longitudinal resistance and vanishing longitudinal conductance, indicating the realization of an axion insulator state. Our findings thus show evidence for a phase of matter distinct from the established QAH state and provide a promising platform for the realization of the TME effect.
Valley-filtered edge states and quantum valley Hall effect in gated bilayer graphene.
Zhang, Xu-Long; Xu, Lei; Zhang, Jun
2017-05-10
Electron edge states in gated bilayer graphene in the quantum valley Hall (QVH) effect regime can carry both charge and valley currents. We show that an interlayer potential splits the zero-energy level and opens a bulk gap, yielding counter-propagating edge modes with different valleys. A rich variety of valley current states can be obtained by tuning the applied boundary potential and lead to the QVH effect, as well as to the unbalanced QVH effect. A method to individually manipulate the edge states by the boundary potentials is proposed.
International Nuclear Information System (INIS)
JOHNSON, B.L.; MOON, JEONG-SUN; RENO, JOHN L.; SIMMONS, JERRY A.
1999-01-01
The propagation direction of fractional quantum Hall effect (FQHE) edge states has been investigated experimentally via the symmetry properties of the multi-terminal capacitances of a two dimensional electron gas. Although strong asymmetries with respect to zero magnetic field appear, no asymmetries with respect to even denominator Landau level filling factor ν are seen. This indicates that current-carrying FQHE edge states propagate in the same direction as integer QHE edge states. In addition, anomalous capacitance features, indicative of enhanced bulk conduction, are observed at ν = 1/2 and 3/2
Biggs, Douglas
2016-01-01
The six Land Grant colleges and universities across the upper Midwest (Wisconsin, Minnesota, Nebraska, North Dakota State, South Dakota State, and Iowa State) all faced unprecedented challenges in the 1890s. The economic depression brought on by the Panic of 1893 saw budget cutbacks and lean times, but the "McKinley Prosperity," combined…
Stability and activation gaps of the parafermionic Hall states in the second Landau level
International Nuclear Information System (INIS)
Georgiev, L.S.
2002-01-01
Analyzing the effective conformal field theory for the parafermionic Hall states, corresponding to filling fractions ν k =2+k/(kM+2), k=2,3,..., M odd, we show that the even k plateaux are expected to be more stable than their odd k neighbors. The reason is that the parafermion chiral algebra can be locally extended for k even. This reconciles the theoretical implication, that the bigger the k the less stable the fluid, with the experimental fact that, for M=1, the k=2 and k=4 plateaux are already observed at electron temperature T e ≅8 mK, while the Hall resistance for k=3 is not precisely quantized at that temperature in the sample of Pan et al. Using a heuristic gap ansatz we estimate the activation energy gap for ν 3 =13/5 to be approximately 0.015 K, which implies that the quantization of the Hall conductance could be observed for temperature below 1 mK in the same sample. We also find an appealing exact relation between the fractional electric charge and fractional statistics of the quasiholes. Finally, we argue that besides the Moore-Read phase for the ν 2 =5/2 state there is another relevant phase, in which the fundamental quasiholes obey abelian statistics and carry half-integer electric charge
Optimization of edge state velocity in the integer quantum Hall regime
Sahasrabudhe, H.; Novakovic, B.; Nakamura, J.; Fallahi, S.; Povolotskyi, M.; Klimeck, G.; Rahman, R.; Manfra, M. J.
2018-02-01
Observation of interference in the quantum Hall regime may be hampered by a small edge state velocity due to finite phase coherence time. Therefore designing two quantum point contact (QPCs) interferometers having a high edge state velocity is desirable. Here we present a new simulation method for designing heterostructures with high edge state velocity by realistically modeling edge states near QPCs in the integer quantum Hall effect (IQHE) regime. Using this simulation method, we also predict the filling factor at the center of QPCs and their conductance at different gate voltages. The 3D Schrödinger equation is split into 1D and 2D parts. Quasi-1D Schrödinger and Poisson equations are solved self-consistently in the IQHE regime to obtain the potential profile, and quantum transport is used to solve for the edge state wave functions. The velocity of edge states is found to be /B , where is the expectation value of the electric field for the edge state. Anisotropically etched trench gated heterostructures with double-sided delta doping have the highest edge state velocity among the structures considered.
Levitation of the quantum Hall extended states in the $B\\to$ 0 limit
Koschny, Th.; Schweitzer, L.
2004-01-01
We investigate the fate of the quantum Hall extended states within a continuum model with spatially correlated disorder potentials. The model can be projected onto a couple of the lowest Landau bands. Levitation of the $n=0$ critical states is observed if at least the two lowest Landau bands are considered. The dependence on the magnetic length $l_B=(\\hbar/(eB))^{1/2}$ and on the correlation length of the disorder potential $\\eta$ is combined into a single dimensionless parameter $\\hat\\eta=\\e...
Hyperspherical Slater determinant approach to few-body fractional quantum Hall states
Energy Technology Data Exchange (ETDEWEB)
Yan, Bin, E-mail: yanbin@purdue.edu; Wooten, Rachel E.; Daily, Kevin M.; Greene, Chris H.
2017-05-15
In a recent study (Daily et al., 2015), a hyperspherical approach has been developed to study few-body fractional quantum Hall states. This method has been successfully applied to the exploration of few boson and fermion problems in the quantum Hall region, as well as the study of inter-Landau level collective excitations (Rittenhouse et al., 2016; Wooten et al., 2016). However, the hyperspherical method as it is normally implemented requires a subsidiary (anti-)symmetrization process, which limits its computational effectiveness. The present work overcomes these difficulties and extends the power of this method by implementing a representation of the hyperspherical many-body basis space in terms of Slater determinants of single particle eigenfunctions. A clear connection between the hyperspherical representation and the conventional single particle picture is presented, along with a compact operator representation of the theoretical framework. - Highlights: • A hyperspherical method has been implemented to study the quantum Hall effect. • The hyperspherical many-body basis space is represented with Slater determinants. • Example numerical studies of the 4- and 8-electron systems are presented.
Non-Abelian fractional quantum Hall states for hard-core bosons in one dimension
Paredes, Belén
2012-05-01
I present a family of one-dimensional bosonic liquids analogous to non-Abelian fractional quantum Hall states. A new quantum number is introduced to characterize these liquids, the chiral momentum, which differs from the usual angular or linear momentum in one dimension. As their two-dimensional counterparts, these liquids minimize a k-body hard-core interaction with the minimum total chiral momentum. They exhibit global order, with a hidden organization of the particles in k identical copies of a one-dimensional Laughlin state. For k=2 the state is a p-wave paired phase corresponding to the Pfaffian quantum Hall state. By imposing conservation of the total chiral momentum, an exact parent Hamiltonian is derived which involves long-range tunneling and interaction processes with an amplitude decaying with the chord distance. This family of non-Abelian liquids is shown to be in formal correspondence with a family of spin-(k)/(2) liquids which are total singlets made out of k indistinguishable resonating valence bond states. The corresponding spin Hamiltonians are obtained.
International Nuclear Information System (INIS)
1983-09-01
This Safety Evaluation Report for the application filed by the Iowa State University (ISU) for a renewal of the Class 104 Operating License R-59 to continue to operate its Argonaut-type research reactor has been prepared by the Office of Nuclear Reactor Regulation of the US Nuclear Regulatory Commission. The facility is owned and operated by the Iowa State University, and is located on the ISU campus in Ames, Story County, Iowa. The staff concludes that the reactor facility can continue to be operated by ISU without endangering the health and safety of the public. The principal matters reviewed are: design, testing, and performance of the reactor components and systems; the expected consequences of credible accidents; the licensee's management organization; the method used for the control of radiological effluents; the licensee's technical specifications; financial data and information; the physical protection program; procedures for training reactor operators; and emergency plans. 11 references, 15 figures, 13 tables
Hardesty, Carolyn, Ed.
1991-01-01
This theme issue is devoted to the three men named Henry Wallace and the history they made for Iowa and for the United States. All of the Henrys were deeply involved in farming and all of them wrote in a magazine called "Wallaces' Farmer." All three of these men also did special work for the U.S. government. The most famous Henry, Henry…
Signatures of a Nonthermal Metastable State in Copropagating Quantum Hall Edge Channels
Itoh, Kosuke; Nakazawa, Ryo; Ota, Tomoaki; Hashisaka, Masayuki; Muraki, Koji; Fujisawa, Toshimasa
2018-05-01
A Tomonaga-Luttinger (TL) liquid is known as an integrable system, in which a nonequilibrium many-body state survives without relaxing to a thermalized state. This intriguing characteristic is tested experimentally in copropagating quantum Hall edge channels at bulk filling factor ν =2 . The unidirectional transport allows us to investigate the time evolution by measuring the spatial evolution of the electronic states. The initial state is prepared with a biased quantum point contact, and its spatial evolution is measured with a quantum-dot energy spectrometer. We find strong evidence for a nonthermal metastable state in agreement with the TL theory before the system relaxes to thermal equilibrium with coupling to the environment.
International Nuclear Information System (INIS)
Braggio, A; Ferraro, D; Sassetti, M; Carrega, M; Magnoli, N
2012-01-01
We propose a general mechanism for the renormalization of the tunnelling exponents in edge states of the fractional quantum Hall effect. Mutual effects of the coupling with out-of-equilibrium 1/f noise and dissipation are considered for both the Laughlin sequence and the composite co- and counter-propagating edge states with Abelian or non-Abelian statistics. For states with counter-propagating modes, we demonstrate the robustness of the proposed mechanism in the so-called disorder-dominated phase. Prototypes of these states, such as ν = 2/3 and ν = 5/2, are discussed in detail, and the rich phenomenology induced by the presence of a noisy environment is presented. The proposed mechanism could help justify the strong renormalizations reported in many experimental observations carried out at low temperatures. We show how environmental effects could affect the relevance of the tunnelling excitations, leading to important implications, in particular for the ν = 5/2 case. (paper)
Mandal, Sudhansu S.; Mukherjee, Sutirtha; Ray, Koushik
2018-03-01
A method for determining the ground state of a planar interacting many-electron system in a magnetic field perpendicular to the plane is described. The ground state wave-function is expressed as a linear combination of a set of basis functions. Given only the flux and the number of electrons describing an incompressible state, we use the combinatorics of partitioning the flux among the electrons to derive the basis wave-functions as linear combinations of Schur polynomials. The procedure ensures that the basis wave-functions form representations of the angular momentum algebra. We exemplify the method by deriving the basis functions for the 5/2 quantum Hall state with a few particles. We find that one of the basis functions is precisely the Moore-Read Pfaffian wave function.
Environmentally Regulated Facilities in Iowa
Iowa State University GIS Support and Research Facility — A unique record for each facility site with an environmental interest by DNR (such as permits). This brings together core environmental information in one place for...
Groundwater Vulnerability Regions of Iowa
Iowa State University GIS Support and Research Facility — The regions onThis map represent areas with similar hydrogeologic characteristics thought to represent similar potentials for contamination of groundwater and/or...
Exotic Non-Abelian Topological Defects in Lattice Fractional Quantum Hall States
Liu, Zhao; Möller, Gunnar; Bergholtz, Emil J.
2017-09-01
We investigate extrinsic wormholelike twist defects that effectively increase the genus of space in lattice versions of multicomponent fractional quantum Hall systems. Although the original band structure is distorted by these defects, leading to localized midgap states, we find that a new lowest flat band representing a higher genus system can be engineered by tuning local single-particle potentials. Remarkably, once local many-body interactions in this new band are switched on, we identify various Abelian and non-Abelian fractional quantum Hall states, whose ground-state degeneracy increases with the number of defects, i.e, with the genus of space. This sensitivity of topological degeneracy to defects provides a "proof of concept" demonstration that genons, predicted by topological field theory as exotic non-Abelian defects tied to a varying topology of space, do exist in realistic microscopic models. Specifically, our results indicate that genons could be created in the laboratory by combining the physics of artificial gauge fields in cold atom systems with already existing holographic beam shaping methods for creating twist defects.
Evaluation of Iowa?s anti-bullying law
Ramirez, Marizen; Ten Eyck, Patrick; Peek-Asa, Corinne; Onwuachi-Willig, Angela; Cavanaugh, Joseph E.
2016-01-01
Background Bullying is the most common form of youth aggression. Although 49 of all 50 states in the U.S. have an anti-bullying law in place to prevent bullying, little is known about the effectiveness of these laws. Our objective was to measure the effectiveness of Iowa?s anti-bullying law in preventing bullying and improving teacher response to bullying. Methods Sixth, 8th, and 11th grade children who completed the 2005, 2008 and 2010 Iowa Youth Survey were included in this study (n?=?253,0...
Ahrens, Donald Louis
To determine the influence of high school vocational agriculture on college achievement and subsequent employment of agricultural engineering majors, data were collected from 419 graduates of Iowa State University representing the period from 1942 to 1964. The 112 graduates who had taken at least 3 or more semesters of high school vocational…
Clements, Margaret; Pazzaglia, Angela M.; Stafford, Erin
2015-01-01
This "Stated Briefly" report is a companion piece that summarizes the results of another report of the same name. The purpose of the study conducted by REL Midwest in partnership with the Midwest Virtual Education Research Alliance was to develop and administer a survey to describe online course use in Iowa and Wisconsin brick-and-mortar…
Quasi-particle properties from tunneling in the v = 5/2 fractional quantum Hall state.
Radu, Iuliana P; Miller, J B; Marcus, C M; Kastner, M A; Pfeiffer, L N; West, K W
2008-05-16
Quasi-particles with fractional charge and statistics, as well as modified Coulomb interactions, exist in a two-dimensional electron system in the fractional quantum Hall (FQH) regime. Theoretical models of the FQH state at filling fraction v = 5/2 make the further prediction that the wave function can encode the interchange of two quasi-particles, making this state relevant for topological quantum computing. We show that bias-dependent tunneling across a narrow constriction at v = 5/2 exhibits temperature scaling and, from fits to the theoretical scaling form, extract values for the effective charge and the interaction parameter of the quasi-particles. Ranges of values obtained are consistent with those predicted by certain models of the 5/2 state.
Interplay of Chiral and Helical States in a Quantum Spin Hall Insulator Lateral Junction
Calvo, M. R.; de Juan, F.; Ilan, R.; Fox, E. J.; Bestwick, A. J.; Mühlbauer, M.; Wang, J.; Ames, C.; Leubner, P.; Brüne, C.; Zhang, S. C.; Buhmann, H.; Molenkamp, L. W.; Goldhaber-Gordon, D.
2017-12-01
We study the electronic transport across an electrostatically gated lateral junction in a HgTe quantum well, a canonical 2D topological insulator, with and without an applied magnetic field. We control the carrier density inside and outside a junction region independently and hence tune the number and nature of 1D edge modes propagating in each of those regions. Outside the bulk gap, the magnetic field drives the system to the quantum Hall regime, and chiral states propagate at the edge. In this regime, we observe fractional plateaus that reflect the equilibration between 1D chiral modes across the junction. As the carrier density approaches zero in the central region and at moderate fields, we observe oscillations in the resistance that we attribute to Fabry-Perot interference in the helical states, enabled by the broken time reversal symmetry. At higher fields, those oscillations disappear, in agreement with the expected absence of helical states when band inversion is lifted.
Imaging the Conductance of Integer and Fractional Quantum Hall Edge States
Directory of Open Access Journals (Sweden)
Nikola Pascher
2014-01-01
Full Text Available We measure the conductance of a quantum point contact while the biased tip of a scanning probe microscope induces a depleted region in the electron gas underneath. At a finite magnetic field, we find plateaus in the real-space maps of the conductance as a function of tip position at integer (ν=1, 2, 3, 4, 6, 8 and fractional (ν=1/3, 2/3, 5/3, 4/5 values of transmission. They resemble theoretically predicted compressible and incompressible stripes of quantum Hall edge states. The scanning tip allows us to shift the constriction limiting the conductance in real space over distances of many microns. The resulting stripes of integer and fractional filling factors are rugged on scales of a few hundred nanometers, i.e., on a scale much smaller than the zero-field elastic mean free path of the electrons. Our experiments demonstrate that microscopic inhomogeneities are relevant even in high-quality samples and lead to locally strongly fluctuating widths of incompressible regions even down to their complete suppression for certain tip positions. The macroscopic quantization of the Hall resistance measured experimentally in a nonlocal contact configuration survives in the presence of these inhomogeneities, and the relevant local energy scale for the ν=2 state turns out to be independent of tip position.
Non-Coal Mineral Production Mines in Iowa, 2000
Iowa State University GIS Support and Research Facility — Registered noncoal mineral production sites within the State of Iowa, current to the year 2000. This shape file contains polygons representing the permitted...
Cost-Effectiveness Analysis of the Residential Provisions of the 2015 IECC for Iowa
Energy Technology Data Exchange (ETDEWEB)
Mendon, Vrushali V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhao, Mingjie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Taylor, Zachary T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Poehlman, Eric A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2016-02-15
The 2015 IECC provides cost-effective savings for residential buildings in Iowa. Moving to the 2015 IECC from the 2014 Iowa State Code base code is cost-effective for residential buildings in all climate zones in Iowa.
Structure of edge-state inner products in the fractional quantum Hall effect
Fern, R.; Bondesan, R.; Simon, S. H.
2018-04-01
We analyze the inner products of edge state wave functions in the fractional quantum Hall effect, specifically for the Laughlin and Moore-Read states. We use an effective description for these inner products given by a large-N expansion ansatz proposed in a recent work by J. Dubail, N. Read, and E. Rezayi [Phys. Rev. B 86, 245310 (2012), 10.1103/PhysRevB.86.245310]. As noted by these authors, the terms in this ansatz can be constrained using symmetry, a procedure we perform to high orders. We then check this conjecture by calculating the overlaps exactly for small system sizes and compare the numerics with our high-order expansion. We find the effective description to be very accurate.
Xue, C.; Ge, J.-Y.; He, A.; Zharinov, V. S.; Moshchalkov, V. V.; Zhou, Y. H.; Silhanek, A. V.; Van de Vondel, J.
2017-07-01
We investigate the degeneracy of the superconducting vortex matter ground state by directly visualizing the vortex configurations in a kagome lattice of elongated antidots via scanning Hall probe microscopy. The observed vortex patterns, at specific applied magnetic fields, are in good agreement with the configurations obtained using time-dependent Ginzburg-Landau simulations. Both results indicate that the long-range interaction in this nanostructured superconductor is unable to lift the degeneracy between different vortex states and the pattern formation is mainly ruled by the nearest-neighbor interaction. This simplification makes it possible to identify a set of simple rules characterizing the vortex configurations. We demonstrate that these rules can explain both the observed vortex distributions and the magnetic-field-dependent degree of degeneracy.
Electronic transport in the quantum spin Hall state due to the presence of adatoms in graphene
Lima, Leandro; Lewenkopf, Caio
Heavy adatoms, even at low concentrations, are predicted to turn a graphene sheet into a topological insulator with substantial gap. The adatoms mediate the spin-orbit coupling that is fundamental to the quantum spin Hall effect. The adatoms act as local spin-orbit scatterer inducing hopping processes between distant carbon atoms giving origin to transverse spin currents. Although there are effective models that describe spectral properties of such systems with great detail, quantitative theoretical work for the transport counterpart is still lacking. We developed a multiprobe recursive Green's function technique with spin resolution to analyze the transport properties for large geometries. We use an effective tight-binding Hamiltonian to describe the problem of adatoms randomly placed at the center of the honeycomb hexagons, which is the case for most transition metals. Our choice of current and voltage probes is favorable to experiments since it filters the contribution of only one spin orientation, leading to a quantized spin Hall conductance of e2 / h . We also discuss the electronic propagation in the system by imaging the local density of states and the electronic current densities. The authors acknowledge the Brazilian agencies CNPq, CAPES, FAPERJ and INCT de Nanoestruturas de Carbono for financial support.
Structure of quasiparticles and their fusion algebra in fractional quantum Hall states
Barkeshli, Maissam; Wen, Xiao-Gang
2009-05-01
It was recently discovered that fractional quantum Hall (FQH) states can be characterized quantitatively by the pattern of zeros that describe how the ground-state wave function goes to zero when electrons are brought close together. Quasiparticles in the FQH states can be described in a similar quantitative way by the pattern of zeros that result when electrons are brought close to the quasiparticles. In this paper, we combine the pattern of zeros approach and the conformal field theory (CFT) approach to calculate the topological properties of quasiparticles. We discuss how the quasiparticles in FQH states naturally form representations of a magnetic translation algebra, with members of a representation differing from each other by Abelian quasiparticles. We find that this structure dramatically simplifies topological properties of the quasiparticles, such as their fusion rules, charges, and scaling dimensions, and has consequences for the ground state degeneracy of FQH states on higher genus surfaces. We find constraints on the pattern of zeros of quasiparticles that can fuse together, which allow us to derive the fusion rules of quasiparticles from their pattern of zeros, at least in the case of the (generalized and composite) parafermion states. We also calculate from CFT the number of quasiparticle types in the generalized and composite parafermion states, which confirm the result obtained previously through a completely different approach.
Structure of quasiparticles and their fusion algebra in fractional quantum Hall states
International Nuclear Information System (INIS)
Barkeshli, Maissam; Wen Xiaogang
2009-01-01
It was recently discovered that fractional quantum Hall (FQH) states can be characterized quantitatively by the pattern of zeros that describe how the ground-state wave function goes to zero when electrons are brought close together. Quasiparticles in the FQH states can be described in a similar quantitative way by the pattern of zeros that result when electrons are brought close to the quasiparticles. In this paper, we combine the pattern of zeros approach and the conformal field theory (CFT) approach to calculate the topological properties of quasiparticles. We discuss how the quasiparticles in FQH states naturally form representations of a magnetic translation algebra, with members of a representation differing from each other by Abelian quasiparticles. We find that this structure dramatically simplifies topological properties of the quasiparticles, such as their fusion rules, charges, and scaling dimensions, and has consequences for the ground state degeneracy of FQH states on higher genus surfaces. We find constraints on the pattern of zeros of quasiparticles that can fuse together, which allow us to derive the fusion rules of quasiparticles from their pattern of zeros, at least in the case of the (generalized and composite) parafermion states. We also calculate from CFT the number of quasiparticle types in the generalized and composite parafermion states, which confirm the result obtained previously through a completely different approach.
A Case Study of a Rural Iowa School Preparing to Meet New State Guidelines for School Libraries
Krueger, Karla Steege
2009-01-01
A qualitative case study highlighting one rural Iowa elementary school provided insight into the issue of small schools without library programs as they are preparing to meet the Iowa reinstatement of the requirement for school library programs. The site was purposefully chosen because it has been operating without a school library program or…
Stanier, C. O.; Spak, S.; Neal, T. A.; Herder, S.; Malek, A.; Miller, Z.
2017-12-01
The Iowa Board of Education voted unanimously in 2015 to adopt NGSS performance standards. The CGRER - College of Education Iowa K-12 Climate Science Education Initiative was established in 2016 to work directly with Iowa inservice teachers to provide what teachers need most to teach climate literacy and climate science content through investigational learning aligned with NGSS. Here we present teachers' requests for teaching climate with NGSS, and an approach to provide resources for place-based authentic inquiry on climate, developed, tested, and refined in partnership with inservice and preservice teachers. A survey of inservice middle school and high school science teachers was conducted at the 2016 Iowa Council of Teachers of Mathematics/Iowa Academy of Sciences - Iowa Science Teaching Section Fall Conference and online in fall 2016. Participants (n=383) were asked about their prior experience and education, the resources they use and need, their level of comfort in teaching climate science, perceived barriers, and how they address potential controversy. Teachers indicated preference for professional development on climate content and complete curricula packaged with lessons and interactive models aligned to Iowa standards, as well as training on instructional strategies to enhance students' ability to interpret scientific evidence. We identify trends in responses by teaching experience, climate content knowledge and its source, grade level, and urban and rural districts. Less than 20% of respondents reported controversy or negativity in teaching climate to date, and a majority were comfortable teaching climate science and climate change, with equal confidence in teaching climate and other STEM content through investigational activities. We present an approach and materials to meet these stated needs, created and tested in collaboration with Iowa teachers. We combine professional development and modular curricula with bundled standards, concepts, models, data
Iowa's forest resources in 2001
Earl C. Leatherberry; Steve Pennington; Gary J. Brand
2003-01-01
Results of the 2001 annual inventory of Iowa show an estimated 2.6 million acres of forest land in the State. The estimate of total all live tree volume on forest land is 3.6 billion cubic feet. Nearly 2.5 million acres of forest land in Iowa are classified as timberland. The estimate of growing-stock volume on timberland is 2.7 billion cubic feet. All live aboveground...
Particle-hole symmetry and composite fermions in fractional quantum Hall states
Nguyen, Dung Xuan; Golkar, Siavash; Roberts, Matthew M.; Son, Dam Thanh
2018-05-01
We study fractional quantum Hall states at filling fractions in the Jain sequences using the framework of composite Dirac fermions. Synthesizing previous work, we write an effective field theory consistent with all symmetry requirements, including Galilean invariance and particle-hole symmetry. Employing a Fermi-liquid description, we demonstrate the appearance of the Girvin-Macdonald-Platzman algebra and compute the dispersion relation of neutral excitations and various response functions. Our results satisfy requirements of particle-hole symmetry. We show that while the dispersion relation obtained from the modified random-phase approximation (MRPA) of the Halperin-Lee-Read (HLR) theory is particle-hole symmetric, correlation functions obtained from this scheme are not. The results of the Dirac theory are shown to be consistent with the Haldane bound on the projected structure factor, while those of the MPRA of the HLR theory violate it.
Xu, Yong; Uddin, Salah; Wang, Jun; Wu, Jiansheng; Liu, Jun-Feng
2017-08-08
We have studied numerically the penetration depth of quantum spin hall edge states in chiral honeycomb nanoribbons based on the Green's function method. The changing of edge orientation from armchair to zigzag direction decreases the penetration depth drastically. The penetration depth is used to estimate the gap opened for the finite-size effect. Beside this, we also proposed a nonlocal transistor based on the zigzag-like chiral ribbons in which the current is carried at one edge and the manipulation is by the edge magnetization at the other edge. The difficulty that the edge magnetization is unstable in the presence of a ballistic current can be removed by this nonlocal manipulation.
Terahertz spectroscopy on Faraday and Kerr rotations in a quantum anomalous Hall state.
Okada, Ken N; Takahashi, Youtarou; Mogi, Masataka; Yoshimi, Ryutaro; Tsukazaki, Atsushi; Takahashi, Kei S; Ogawa, Naoki; Kawasaki, Masashi; Tokura, Yoshinori
2016-07-20
Electrodynamic responses from three-dimensional topological insulators are characterized by the universal magnetoelectric term constituent of the Lagrangian formalism. The quantized magnetoelectric coupling, which is generally referred to as topological magnetoelectric effect, has been predicted to induce exotic phenomena including the universal low-energy magneto-optical effects. Here we report the experimental indication of the topological magnetoelectric effect, which is exemplified by magneto-optical Faraday and Kerr rotations in the quantum anomalous Hall states of magnetic topological insulator surfaces by terahertz magneto-optics. The universal relation composed of the observed Faraday and Kerr rotation angles but not of any material parameters (for example, dielectric constant and magnetic susceptibility) well exhibits the trajectory towards the fine structure constant in the quantized limit.
Tunable Acoustic Valley-Hall Edge States in Reconfigurable Phononic Elastic Waveguides
Liu, Ting-Wei; Semperlotti, Fabio
2018-01-01
We investigate the occurrence of acoustic topological edge states in a 2D phononic elastic waveguide due to a phenomenon that is the acoustic analog of the quantum valley Hall effect. We show that a topological transition takes place between two lattices having broken space-inversion symmetry due to the application of a tunable strain field. This condition leads to the formation of gapless edge states at the domain walls, as further illustrated by the analysis of the bulk-edge correspondence and of the associated topological invariants. Interestingly, topological edge states can also be triggered at the boundary of a single domain, when boundary conditions are properly selected. We also show that the static modulation of the strain field allows us to tune the response of the material between the different supported edge states. Although time-reversal symmetry is still intact in this material system, the edge states are topologically protected when intervalley mixing is either weak or negligible. This characteristic enables selective valley injection, which is achieved via synchronized source strategy.
Helical edge states and fractional quantum Hall effect in a graphene electron-hole bilayer.
Sanchez-Yamagishi, Javier D; Luo, Jason Y; Young, Andrea F; Hunt, Benjamin M; Watanabe, Kenji; Taniguchi, Takashi; Ashoori, Raymond C; Jarillo-Herrero, Pablo
2017-02-01
Helical 1D electronic systems are a promising route towards realizing circuits of topological quantum states that exhibit non-Abelian statistics. Here, we demonstrate a versatile platform to realize 1D systems made by combining quantum Hall (QH) edge states of opposite chiralities in a graphene electron-hole bilayer at moderate magnetic fields. Using this approach, we engineer helical 1D edge conductors where the counterpropagating modes are localized in separate electron and hole layers by a tunable electric field. These helical conductors exhibit strong non-local transport signals and suppressed backscattering due to the opposite spin polarizations of the counterpropagating modes. Unlike other approaches used for realizing helical states, the graphene electron-hole bilayer can be used to build new 1D systems incorporating fractional edge states. Indeed, we are able to tune the bilayer devices into a regime hosting fractional and integer edge states of opposite chiralities, paving the way towards 1D helical conductors with fractional quantum statistics.
Flood of August 24–25, 2016, Upper Iowa River and Turkey River, northeastern Iowa
Linhart, S. Mike; O'Shea, Padraic S.
2018-02-05
Major flooding occurred August 24–25, 2016, in the Upper Iowa River Basin and Turkey River Basin in northeastern Iowa following severe thunderstorm activity over the region. About 8 inches of rain were recorded for the 24-hour period ending at 4 p.m., August 24, at Decorah, Iowa, and about 6 inches of rain were recorded for the 24-hour period ending at 7 a.m., August 24, at Cresco, Iowa, about 14 miles northwest of Spillville, Iowa. A maximum peak-of-record discharge of 38,000 cubic feet per second in the Upper Iowa River at streamgage 05388250 Upper Iowa River near Dorchester, Iowa, occurred on August 24, 2016, with an annual exceedance-probability range of 0.2–1 percent. High-water marks were measured at six locations along the Upper Iowa River between State Highway 26 near the mouth at the Mississippi River and State Highway 76 about 3.5 miles south of Dorchester, Iowa, a distance of 15 river miles. Along the profiled reach of the Turkey River, a maximum peak-of-record discharge of 15,300 cubic feet per second at streamgage 05411600 Turkey River at Spillville, Iowa, occurred on August 24, 2016, with an annual exceedance-probability range of 1–2 percent. A maximum peak discharge of 35,700 cubic feet per second occurred on August 25, 2016, along the profiled reach of the Turkey River at streamgage 05411850 Turkey River near Eldorado, Iowa, with an annual exceedance-probability range of 0.2–1 percent. High-water marks were measured at 11 locations along the Turkey River between County Road B64 in Elgin and 220th Street, located about 4.5 miles northwest of Spillville, Iowa, a distance of 58 river miles. The high-water marks were used to develop flood profiles for the Upper Iowa River and Turkey River.
Stacked bilayer phosphorene: strain-induced quantum spin Hall state and optical measurement
Zhang, Tian; Lin, Jia-He; Yu, Yan-Mei; Chen, Xiang-Rong; Liu, Wu-Ming
2015-01-01
Bilayer phosphorene attracted considerable interest, giving a potential application in nanoelectronics owing to its natural bandgap and high carrier mobility. However, very little is known regarding the possible usefulness in spintronics as a quantum spin Hall (QSH) state of material characterized by a bulk energy gap and gapless spin-filtered edge states. Here, we report a strain-induced topological phase transition from normal to QSH state in bilayer phosphorene, accompanied by band-inversion that changes number from 0 to 1, which is highly dependent on interlayer stacking. When the bottom layer is shifted by 1/2 unit-cell along zigzag/armchair direction with respect to the top layer, the maximum topological bandgap 92.5 meV is sufficiently large to realize QSH effect even at room-temperature. An optical measurement of QSH effect is therefore suggested in view of the wide optical absorption spectrum extending to far infra-red, making bilayer phosphorene a promising candidate for opto-spintronic devices. PMID:26370771
Harvard Family Research Project, Cambridge, MA.
The five states featured in this second edition of "Innovative States" were chosen because they reflect crucial elements in an emerging understanding of state policy making in family support and education. Creative state partnerships involving program development and funding are a key ingredient to successful endeavors. States rely on…
Strong Bulk-Edge Coupling in the Compressible Half-Filled Quantum Hall State
International Nuclear Information System (INIS)
Milovanovic, M.V.; Shimshoni, E.
1999-01-01
We studied analytically static correlators in the compressible half-filled quantum Hall state, which characterize the nature of charged excitations in the bulk and on the edge of the system. We employ a modified version of the plasma analogy - namely, a mapping to a classical two-dimensional system of interacting particles - similarly to what has been done in studies of the incompressible (Laughlin) states. However, the 'fake plasma' corresponding to the half-filled state is found to have anomalously weak screening properties. As a consequence, the correlations along the edge do not decay algebraically as in the incompressible case, thus indicating the breakdown of Wen's edge theory. On the other hand, the bulk correlator (which parallels the Girvin-MacDonald algebraic off-diagonal long range order) decays algebraically in a similar way as in the incompressible states, signifying the presence of some kind of bosonic order even in the compressible state. The above results suggest that due to the strong coupling between charged modes on the edge and the neutral Fermions (dipoles) in the bulk, the (attractive) correlation hole is not well defined on the edge. Hence, the system there can be modeled as a free Fermi gas of electrons (with an appropriate boundary condition). A possible experimental indication of a strong bulk-edge coupling at half-filling has been indeed observed in non-local resistance measurements [1]. We also suggest, that while our results contradict the validity of an effective one-dimensional description of the edge excitations on the static level, the dynamics may decouple the edge and bulk so as to recover the Laughlin-like behavior apparent in the experiment of Grayson et al
78 FR 36010 - Iowa Disaster #IA-00052
2013-06-14
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13605 and 13606] Iowa Disaster IA-00052 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-4119- DR), dated 05/31...
76 FR 54522 - Iowa Disaster #IA-00037
2011-09-01
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12760 and 12761] Iowa Disaster IA-00037 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-4016- DR), dated 08/24...
76 FR 27738 - Iowa Disaster #IA-00030
2011-05-12
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12541 and 12542] Iowa Disaster IA-00030 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Iowa dated 05/04/2011. Incident: Severe storms and tornadoes...
78 FR 28939 - Iowa Disaster #IA-00050
2013-05-16
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13567 and 13568] Iowa Disaster IA-00050 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-4114- DR), dated 05/06...
76 FR 52042 - Iowa Disaster #IA-00035
2011-08-19
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12734 and 12735] Iowa Disaster IA-00035 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Iowa Dated. Incident: Severe Storms and Flash Flooding. Incident...
76 FR 55721 - Iowa Disaster #IA-00038
2011-09-08
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12772 and 12773] Iowa Disaster IA-00038 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-4018- DR), dated 08/30...
75 FR 47035 - Iowa Disaster # IA-00026
2010-08-04
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12258 and 12259] Iowa Disaster IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance only for the State of Iowa (FEMA-1930- DR), dated 07/29...
75 FR 51507 - Iowa Disaster #IA-00024
2010-08-20
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12279 and 12280] Iowa Disaster IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Iowa (FEMA-1930-DR), dated 08/14/2010. Incident: Severe...
75 FR 10329 - Iowa Disaster #IA-00022
2010-03-05
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12053 and 12054] Iowa Disaster IA-00022 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of IOWA (FEMA--1877-- DR), dated 02...
75 FR 11582 - IOWA Disaster # IA-00023
2010-03-11
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12062 and 12063] IOWA Disaster IA-00023 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-1880- DR), dated 03/02...
78 FR 42147 - Iowa Disaster #IA-00054
2013-07-15
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13645 and 13646] Iowa Disaster IA-00054 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance only for the State of Iowa (FEMA-4126- DR), dated 07/02...
76 FR 29284 - Iowa Disaster #IA-00031
2011-05-20
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12568 and 12569] Iowa Disaster IA-00031 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-1977- DR), dated 05/05...
75 FR 45681 - Iowa Disaster #IA-00025
2010-08-03
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12252 and 12253] Iowa Disaster IA-00025 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-1928- DR), dated 07/27...
76 FR 66768 - Iowa Disaster #IA-00033
2011-10-27
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12895 and 12896] Iowa Disaster IA-00033 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Iowa (FEMA-1998-DR), dated 10/18/2011. Incident: Flooding...
78 FR 48762 - Iowa Disaster #IA-00053
2013-08-09
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13699 and 13700] Iowa Disaster IA-00053 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-4135- DR), dated 07/31...
75 FR 53006 - Iowa Disaster #IA-00026
2010-08-30
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12258 and 12259] Iowa Disaster IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 2. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 1930-DR...
Iowa Farm and Rural Life Poll. Summary.
Lasley, Paul
The 1984 Iowa Farm and Rural Life Poll is summarized in this report. Responses from 1,585 randomly selected Iowa farm families showed that respondents opposed relaxing current state laws limiting foreign investors and non-farm corporations' ownership of farmland; had mixed feelings on absentee ownership, changing banking laws to allow banks to…
International Nuclear Information System (INIS)
Ferrari, R.; I.N.F.N., Trento
1994-01-01
The formalism introduced in a previous paper is used for discussing the Coulomb interaction of many electrons moving in two space-dimensions in the presence of a strong magnetic field. The matrix element of the coulomb interaction is evaluated in the new basis, whose states are invariant under discrete translations. This paper is devoted to the case of low filling factor, thus the authors limit themselves to the lowest Landau level and to spins all oriented along the magnetic field. For the case of filling factor ν f = 1/u they give an Ansatz on the state of many electrons which provides a good approximated solution of the Hartree-Fock equation. For general filling factor ν f = u'/u a trial state is given which converges very rapidly to a solution of the self-consistent equation. They generalize the Hartree-Fock equation by considering some correlation: all quantum states are allowed for the u' electrons with the same translation quantum numbers. Numerical results are given for the mean energy and the energy bands, for some values of the filling factor (ν f = 1/2, 1/3, 2/3, 1/4, 3/4, 1/5, 2/5, 3/5, 4/5). The results agree numerically with the Charge Density Wave approach. The boundary conditions are shown to be very important: only large systems (degeneracy of Landau level over 200) are not affected by the boundaries. Therefore results obtained on small scale systems are somewhat unreliable. The relevance of the results for the Fractional Quantum Hall Effect is briefly discussed
Chowdhury, Debanjan; Skinner, Brian; Lee, Patrick A.
2018-05-01
Electron tunneling into a system with strong interactions is known to exhibit an anomaly, in which the tunneling conductance vanishes continuously at low energy due to many-body interactions. Recent measurements have probed this anomaly in a quantum Hall bilayer of the half-filled Landau level, and shown that the anomaly apparently gets stronger as the half-filled Landau level is increasingly spin polarized. Motivated by this result, we construct a semiclassical hydrodynamic theory of the tunneling anomaly in terms of the charge-spreading action associated with tunneling between two copies of the Halperin-Lee-Read state with partial spin polarization. This theory is complementary to our recent work (D. Chowdhury, B. Skinner, and P. A. Lee, arXiv:1709.06091) where the electron spectral function was computed directly using an instanton-based approach. Our results show that the experimental observation cannot be understood within conventional theories of the tunneling anomaly, in which the spreading of the injected charge is driven by the mean-field Coulomb energy. However, we identify a qualitatively new regime, in which the mean-field Coulomb energy is effectively quenched and the tunneling anomaly is dominated by the finite compressibility of the composite Fermion liquid.
Greiter, Martin
2011-01-01
This monograph introduces an exact model for a critical spin chain with arbitrary spin S, which includes the Haldane--Shastry model as the special case S=1/2. While spinons in the Haldane-Shastry model obey abelian half-fermi statistics, the spinons in the general model introduced here obey non-abelian statistics. This manifests itself through topological choices for the fractional momentum spacings. The general model is derived by mapping exact models of quantized Hall states onto spin chains. The book begins with pedagogical review of all the relevant models including the non-abelian statistics in the Pfaffian Hall state, and is understandable to every student with a graduate course in quantum mechanics.
Quantum Hall states of atomic Bose gases: Density profiles in single-layer and multilayer geometries
International Nuclear Information System (INIS)
Cooper, N. R.; Lankvelt, F. J. M. van; Reijnders, J. W.; Schoutens, K.
2005-01-01
We describe the density profiles of confined atomic Bose gases in the high-rotation limit, in single-layer and multilayer geometries. We show that, in a local-density approximation, the density in a single layer shows a landscape of quantized steps due to the formation of incompressible liquids, which are analogous to fractional quantum Hall liquids for a two-dimensional electron gas in a strong magnetic field. In a multilayered setup we find different phases, depending on the strength of the interlayer tunneling t. We discuss the situation where a vortex lattice in the three-dimensional condensate (at large tunneling) undergoes quantum melting at a critical tunneling t c 1 . For tunneling well below t c 1 one expects weakly coupled or isolated layers, each exhibiting a landscape of quantum Hall liquids. After expansion, this gives a radial density distribution with characteristic features (cusps) that provide experimental signatures of the quantum Hall liquids
The effective action for edge states in higher-dimensional quantum Hall systems
International Nuclear Information System (INIS)
Karabali, Dimitra; Nair, V.P.
2004-01-01
We show that the effective action for the edge excitations of a quantum Hall droplet of fermions in higher dimensions is generically given by a chiral bosonic action. We explicitly analyze the quantum Hall effect on complex projective spaces CP k , with a U(1) background magnetic field. The edge excitations are described by Abelian bosonic fields on S 2k-1 with only one spatial direction along the boundary of the droplet relevant for the dynamics. Our analysis also leads to an action for edge excitations for the case of the Zhang-Hu four-dimensional quantum Hall effect defined on S 4 with an SU(2) background magnetic field, using the fact that CP 3 is an S 2 -bundle over S 4
Behrstock, Ellen; Bhatt, Monica; Cushing, Ellen; Wraight, Sara
2010-01-01
Training, recruiting, developing, and supporting talented and effective educators throughout their careers is known as human capital resource management (HCRM) in education. HCRM has been identified in recent literature as one of the ways in which districts and states may increase school effectiveness and improve student learning (Heneman &…
Gauge invariance and fractional quantized Hall effect
International Nuclear Information System (INIS)
Tao, R.; Wu, Y.S.
1984-01-01
It is shown that gauge invariance arguments imply the possibility of fractional quantized Hall effect; the Hall conductance is accurately quantized to a rational value. The ground state of a system showing the fractional quantized Hall effect must be degenerate; the non-degenerate ground state can only produce the integral quantized Hall effect. 12 references
International Nuclear Information System (INIS)
Pan, W.; Tsui, D.C.; Pan, W.; Xia, J.; Shvarts, V.; Adams, D.E.; Xia, J.; Shvarts, V.; Adams, D.E.; Stormer, H.L.; Stormer, H.L.; Pfeiffer, L.N.; Baldwin, K.W.; West, K.W.
1999-01-01
We report ultralow temperature experiments on the obscure fractional quantum Hall effect at Landau level filling factor ν=5/2 in a very high-mobility specimen of μ=1.7x10 7 cm 2 /V s . We achieve an electron temperature as low as ∼4 mK , where we observe vanishing R xx and, for the first time, a quantized Hall resistance, R xy =h/(5/2)e 2 to within 2ppm. R xy at the neighboring odd-denominator states ν=7/3 and 8/3 is also quantized. The temperature dependences of the R xx minima at these fractional fillings yield activation energy gaps Δ 5/2 =0.11 , Δ 7/3 =0.10 , and Δ 8/3 =0.055 K . copyright 1999 The American Physical Society
Current Sinkhole Boundaries in Iowa
Iowa State University GIS Support and Research Facility — This dataset is a polygon coverage of the sinkhole boundaries as determined by using LiDAR data. The polygons relate to the point coverage using the KPolyID field in...
Dreams and Opportunities: Immigrant Families and Iowa's Future. Iowa Kid's Count Special Report
Wright, Michelle Stover
2010-01-01
The fact that there has been population growth in Iowa at all (about 100,000 growth per decade over the last 50 years) is due in large measure to an increased level of immigration into the state. This immigration has helped to stabilize Iowa's population and workforce. Immigrants bring diverse experiences and backgrounds with them. This report…
South-East Iowa Groundwater Vulnerability Regions
Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro- geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...
North-East Iowa Groundwater Vulnerability Regions
Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro-geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...
Iowa DOT project management peer exchange.
2016-07-01
This project supported the planning and conduct of a two-day Iowa Department of Transportationhosted peer exchange for state : agencies that have implemented some or all of the suggested strategies outlined in the Second Strategic Highway Research...
Leaking Underground Storage Tank Sites in Iowa
Iowa State University GIS Support and Research Facility — Leaking Underground Storage Tank (LUST) sites where petroleum contamination has been found. There may be more than one LUST site per UST site.
North-West Iowa Groundwater Vulnerability Regions
Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro-geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...
South-West Iowa Groundwater Vulnerability Regions
Iowa State University GIS Support and Research Facility — The regions on this map represent areas with similar hydro- geologic characteristics thought to represent similar potentials for contamination of groundwater and/or...
Scaling behavior of mixed-state hall effect in MgB2 thin films
International Nuclear Information System (INIS)
Jung, Soon-Gil; Seong, W.K.; Kang, W.N.; Choi, Eun-Mi; Kim, Heon-Jung; Lee, Sung-Ik; Kim, Hyeong-Jin; Kim, H.C.
2006-01-01
The Hall resistivity (ρ xy ) and the longitudinal resistivity (ρ xx ) in c-axis-oriented superconducting MgB 2 thin films have been investigated in extended fields up to 18T. We have observed a scaling behavior between the Hall resistivity and the longitudinal resistivity, ρ xy =Aρ xx β , where the exponent (β) is observed to be independent of the temperatures and the magnetic fields. For a wide magnetic field region from 1 to 18T and a wide temperature region from 10 to 28K, a universal power law with β=2.0+/-0.1 was observed in c-axis-oriented MgB 2 thin films. These results can be well interpreted by using recent models
High magneticfield test of Bismuth Hall sensors for ITER steady state magnetic diagnostic
Czech Academy of Sciences Publication Activity Database
Ďuran, Ivan; Entler, Slavomír; Kohout, Michal; Kocan, M.; Vayakis, G.
2016-01-01
Roč. 87, č. 11 (2016), č. článku 11D446. ISSN 0034-6748. [Topical Conference on High-Temperature Plasma Diagnostics (HTPD2016) /21./. Madison, Wisconsin, 05.06.2016-09.06.2016] R&D Projects: GA MŠk LG14002 Institutional support: RVO:61389021 ; RVO:68378271 Keywords : Hall sensors * ITER * Hall effect * magnetic diagnostic Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (FZU-D) OBOR OECD: 2.11 Other engineering and technologies; 2.11 Other engineering and technologies (FZU-D) Impact factor: 1.515, year: 2016 http://scitation.aip.org/content/aip/journal/rsi/87/11/10.1063/1.4964435
Wuertz, A.; Wildfeuer, R.; Lorke, A.; Deviatov, E. V.; Dolgopolov, V. T.
2001-01-01
Using an innovative combination of a quasi-Corbino sample geometry and the cross-gate technique, we have developed a method that enables us to separately contact single edge channels in the quantum Hall regime and investigate equilibration among them. Performing 4-point resistance measurements, we directly obtain information on the energetic and geometric structure of the edge region and the equilibration-length for current transport across the Landau- as well as the spin-gap. Based on an alm...
Iowa Central Quality Fuel Testing Laboratory
Energy Technology Data Exchange (ETDEWEB)
Heach, Don; Bidieman, Julaine
2013-09-30
The objective of this project is to finalize the creation of an independent quality fuel testing laboratory on the campus of Iowa Central Community College in Fort Dodge, Iowa that shall provide the exploding biofuels industry a timely and cost-effective centrally located laboratory to complete all state and federal fuel and related tests that are required. The recipient shall work with various state regulatory agencies, biofuel companies and state and national industry associations to ensure that training and testing needs of their members and American consumers are met. The recipient shall work with the Iowa Department of Ag and Land Stewardship on the development of an Iowa Biofuel Quality Standard along with the Development of a standard that can be used throughout industry.
Solid Waste Land Applications with Permits by the Iowa DNR
Iowa State University GIS Support and Research Facility — All types of facilities that handle solid waste, including: sanitary landfills, appliance demanufacturing facilities, transfer stations, land application sites,...
Solid Waste Management Facilities with Permits by the Iowa DNR
Iowa State University GIS Support and Research Facility — All types of facilities that handle solid waste, including: sanitary landfills, appliance demanufacturing facilities, transfer stations, land application sites,...
Role of helical edge modes in the chiral quantum anomalous Hall state.
Mani, Arjun; Benjamin, Colin
2018-01-22
Although indications are that a single chiral quantum anomalous Hall(QAH) edge mode might have been experimentally detected. There have been very many recent experiments which conjecture that a chiral QAH edge mode always materializes along with a pair of quasi-helical quantum spin Hall (QSH) edge modes. In this work we deal with a substantial 'What If?' question- in case the QSH edge modes, from which these QAH edge modes evolve, are not topologically-protected then the QAH edge modes wont be topologically-protected too and thus unfit for use in any applications. Further, as a corollary one can also ask if the topological-protection of QSH edge modes does not carry over during the evolution process to QAH edge modes then again our 'What if?' scenario becomes apparent. The 'how' of the resolution of this 'What if?' conundrum is the main objective of our work. We show in similar set-ups affected by disorder and inelastic scattering, transport via trivial QAH edge mode leads to quantization of Hall resistance and not that via topological QAH edge modes. This perhaps begs a substantial reinterpretation of those experiments which purported to find signatures of chiral(topological) QAH edge modes albeit in conjunction with quasi helical QSH edge modes.
History of the Benton Street Bridge (Iowa City, Iowa) [SD .WMV (720x480/29fps/753.0 MB)
2010-04-01
In January 2010, Robert Sam L. Carstens, F.ASCE, a retired (1986) professor of civil engineering and Professor Emeritus at Iowa State University, donated to the Iowa Department of Transportation (DOT) a scrapbook and 131 snapshots documenting t...
The Two-Dimensional MnO2/Graphene Interface: Half-metallicity and Quantum Anomalous Hall State
Gan, Liyong
2015-10-07
We explore the electronic properties of the MnO2/graphene interface by first-principles calculations, showing that MnO2 becomes half-metallic. MnO2 in the MnO2/graphene/MnO2 system provides time-reversal and inversion symmetry breaking. Spin splitting by proximity occurs at the Dirac points and a topologically nontrivial band gap is opened, enabling a quantum anomalous Hall state. The half-metallicity, spin splitting, and size of the band gap depend on the interfacial interaction, which can be tuned by strain engineering.
Theory of the disordered ν =5/2 quantum thermal Hall state: Emergent symmetry and phase diagram
Lian, Biao; Wang, Juven
2018-04-01
Fractional quantum Hall (FQH) system at Landau level filling fraction ν =5 /2 has long been suggested to be non-Abelian, either Pfaffian (Pf) or antiPfaffian (APf) states by numerical studies, both with quantized Hall conductance σx y=5 e2/2 h . Thermal Hall conductances of the Pf and APf states are quantized at κx y=7 /2 and κx y=3 /2 , respectively, in a proper unit. However, a recent experiment shows the thermal Hall conductance of ν =5 /2 FQH state is κx y=5 /2 . It has been speculated that the system contains random Pf and APf domains driven by disorders, and the neutral chiral Majorana modes on the domain walls may undergo a percolation transition to a κx y=5 /2 phase. In this paper, we do perturbative and nonperturbative analyses on the domain walls between Pf and APf. We show the domain wall theory possesses an emergent SO(4) symmetry at energy scales below a threshold Λ1, which is lowered to an emergent U (1 )×U (1) symmetry at energy scales between Λ1 and a higher value Λ2, and is finally lowered to the composite fermion parity symmetry Z2F above Λ2. Based on the emergent symmetries, we propose a phase diagram of the disordered ν =5 /2 FQH system and show that a κx y=5 /2 phase arises at disorder energy scales Λ >Λ1 . Furthermore, we show the gapped double-semion sector of ND compact domain walls contributes nonlocal topological degeneracy 2ND-1, causing a low-temperature peak in the heat capacity. We implement a nonperturbative method to bootstrap generic topological 1 +1 D domain walls (two-surface defects) applicable to any 2 +1 D non-Abelian topological order. We also identify potentially relevant spin topological quantum field theories (TQFTs) for various ν =5 /2 FQH states in terms of fermionic version of U (1) ±8 Chern-Simons theory ×Z8 -class TQFTs.
The Two-Dimensional MnO2/Graphene Interface: Half-metallicity and Quantum Anomalous Hall State
Gan, Liyong; Zhang, Qingyun; Guo, Chun-Sheng; Schwingenschlö gl, Udo; Zhao, Yong
2015-01-01
We explore the electronic properties of the MnO2/graphene interface by first-principles calculations, showing that MnO2 becomes half-metallic. MnO2 in the MnO2/graphene/MnO2 system provides time-reversal and inversion symmetry breaking. Spin splitting by proximity occurs at the Dirac points and a topologically nontrivial band gap is opened, enabling a quantum anomalous Hall state. The half-metallicity, spin splitting, and size of the band gap depend on the interfacial interaction, which can be tuned by strain engineering.
Yang, Kun
2017-12-01
We consider an interface separating the Moore-Read state and Halperin 331 state in a half-filled Landau level, which can be realized in a double quantum well system with varying interwell tunneling and/or interaction strengths. In the presence of electron tunneling and strong Coulomb interactions across the interface, we find that all charge modes localize and the only propagating mode left is a chiral Majorana fermion mode. Methods to probe this neutral mode are proposed. A quantum phase transition between the Moore-Read and Halperin 331 states is described by a network of such Majorana fermion modes. In addition to a direct transition, they may also be separated by a phase in which the Majorana fermions are delocalized, realizing an incompressible state which exhibits quantum Hall charge transport and bulk heat conduction.
Quantum Hall effect on top and bottom surface states of topological insulator (Bi1-xSbx)2Te3 films.
Yoshimi, R; Tsukazaki, A; Kozuka, Y; Falson, J; Takahashi, K S; Checkelsky, J G; Nagaosa, N; Kawasaki, M; Tokura, Y
2015-04-14
The three-dimensional topological insulator is a novel state of matter characterized by two-dimensional metallic Dirac states on its surface. To verify the topological nature of the surface states, Bi-based chalcogenides such as Bi2Se3, Bi2Te3, Sb2Te3 and their combined/mixed compounds have been intensively studied. Here, we report the realization of the quantum Hall effect on the surface Dirac states in (Bi1-xSbx)2Te3 films. With electrostatic gate-tuning of the Fermi level in the bulk band gap under magnetic fields, the quantum Hall states with filling factor ±1 are resolved. Furthermore, the appearance of a quantum Hall plateau at filling factor zero reflects a pseudo-spin Hall insulator state when the Fermi level is tuned in between the energy levels of the non-degenerate top and bottom surface Dirac points. The observation of the quantum Hall effect in three-dimensional topological insulator films may pave a way toward topological insulator-based electronics.
Development of Bismuth Hall sensors for ITER steady state magnetic diagnostics.
Czech Academy of Sciences Publication Activity Database
Ďuran, Ivan; Entler, Slavomír; Kočan, M.; Kohout, Michal; Viererbl, L.; Mušálek, Radek; Chráska, Tomáš; Vayakis, G.
2017-01-01
Roč. 123, November (2017), s. 690-694 ISSN 0920-3796. [SOFT 2016: Symposium on Fusion Technology /29./. Prague, 05.09.2016-09.09.2016] R&D Projects: GA MŠk LG14002 Institutional support: RVO:61389021 ; RVO:68378271 Keywords : ITER * Magnetic diagnostic * Hall sensor * Bismuth * Neutron irradiation * Radiation hardness Subject RIV: JF - Nuclear Energetics; JF - Nuclear Energetics (FZU-D) OBOR OECD: Nuclear related engineering; Nuclear related engineering (FZU-D) Impact factor: 1.319, year: 2016 http://www.sciencedirect.com/science/article/pii/S0920379617306956
The self-consistent calculation of the edge states in bilayer quantum Hall bar
International Nuclear Information System (INIS)
Kavruk, A E; Orzturk, T; Orzturk, A; Atav, U; Yuksel, H
2011-01-01
In this study, we present the spatial distributions of the edge channels for each layer in bilayer quantum Hall bar geometry for a wide range of applied magnetic fields. For this purpose, we employ a self-consistent Thomas-Fermi-Poisson approach to obtain the electron density distributions and related screened potential distributions. In order to have a more realistic description of the system we solve three dimensional Poisson equation numerically in each iteration step to obtain self consistency in the Thomas-Fermi-Poisson approach instead of employing a 'frozen gate' approximation.
Directory of Open Access Journals (Sweden)
Roger W. Bachmann
2018-01-01
Full Text Available Field measurements of water quality in Iowa lakes contradict paleolimnological studies that used 210Pb dating techniques in 33 lakes to infer accelerating eutrophication and sediment accumulation in recent decades. We tested this hypothesis by analyzing a series of water quality measurements taken in 24 of these lakes during the period 1972–2010. There was little change in the trophic state variables. Total phosphorus and algal chlorophylls did not increase, and Secchi depths did not decrease with no evidence that the lakes had become more eutrophic. Changes in daily sediment loads in the Raccoon River also did not match the paleolimnological inferred rates of soil erosion for the period 1905–2005, and an independent estimate of soil erosion rates showed a decline of 40% in the 1977 to 2012 period rather than an increase. We hypothesized that sediment mixing by benthivorous fish could be responsible for violating the basic assumption of 210Pb sediment dating that the sediments are not disturbed once they are laid down. We developed a mathematical model that demonstrated that sediment mixing could lead to false inferences about sediment dates and sediment burial rates. This study raises the possibility that sediment mixing in Iowa lakes and similar shallow, eutrophic lakes with benthivorous fish may cause significant sediment mixing that can compromise dating using 210Pb dating of sediment cores.
Light-Induced Type-II Band Inversion and Quantum Anomalous Hall State in Monolayer FeSe
Wang, Z. F.; Liu, Zhao; Yang, Jinlong; Liu, Feng
2018-04-01
Coupling a quantum anomalous Hall (QAH) state with a superconducting state offers an attractive approach to detect the signature alluding to a topological superconducting state [Q. L. He et al., Science 357, 294 (2017), 10.1126/science.aag2792], but its explanation could be clouded by disorder effects in magnetic doped QAH materials. On the other hand, an antiferromagnetic (AFM) quantum spin Hall (QSH) state is identified in the well-known high-temperature 2D superconductor of monolayer FeSe [Z. F. Wang et al., Nat. Mater. 15, 968 (2016), 10.1038/nmat4686]. Here, we report a light-induced type-II band inversion (BI) and a QSH-to-QAH phase transition in the monolayer FeSe. Depending on the handedness of light, a spin-tunable QAH state with a high Chern number of ±2 is realized. In contrast to the conventional type-I BI resulting from intrinsic spin-orbital coupling (SOC), which inverts the band an odd number of times and respects time reversal symmetry, the type-II BI results from a light-induced handedness-dependent effective SOC, which inverts the band an even number of times and does not respect time reversal symmetry. The interplay between these two SOC terms makes the spin-up and -down bands of an AFM QSH state respond oppositely to a circularly polarized light, leading to the type-II BI and an exotic topological phase transition. Our finding affords an exciting opportunity to detect Majorana fermions in one single material without magnetic doping.
Federal Laboratory Consortium — The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electroand photo-induced reactions at very high luminosity...
Federal Laboratory Consortium — Hall C's initial complement of equipment (shown in the figure), includes two general-purpose magnetic spectrometers. The High Momentum Spectrometer (HMS) has a large...
Mark D. Nelson; Matt Brewer; Dacia M. Meneguzzo; Kathryne. Clark
2016-01-01
This resource update provides an overview of forest resources in Iowa based on inventories conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Northern Research Station in cooperation with the Iowa Department of Natural Resources. Estimates are based on field data collected using the FIA annualized sample design and are updated...
Tait, John L.; Johnson, Arthur H.
The trends in population distribution and the composition of Iowa's population are reported in this document in order to provide the leaders and citizens of Iowa with information to assist them in making decisions relating to growth and development. Birth and death rates, rural and urban residence, population by race, and age structure are…
Political Township Boundaries in Iowa for 2010, derived from Census Data
Iowa State University GIS Support and Research Facility — Currently, Iowa townships are not actually classified as civil townships, but as special district governments. Special district governments exist to provide only one...
Iowa House of Representatives District Boundaries for 2013 - 2022_85th - 89th General Assemblies
Iowa State University GIS Support and Research Facility — Iowa Legislative House district boundaries, enacted April 19, 2011, effective beginning with the elections in 2012 for the 85th General Assembly. The districts will...
Incorporated City Boundaries in Iowa in 2010 as Derived from the Census Places Dataset
Iowa State University GIS Support and Research Facility — Incorporated Cities in Iowa in 2010, as derived from the Census Places dataset. Original abstract: The TIGER/Line Files are shapefiles and related database files...
Political Township and Incorporated City Boundaries in Iowa in 2010 as Derived from Census Datasets
Iowa State University GIS Support and Research Facility — Political Township and Incorporated City Boundaries in Iowa in 2010, as Derived from Census Datasets Original Abstract: The TIGER/Line Files are shapefiles and...
76 FR 44029 - Iowa; Major Disaster and Related Determinations
2011-07-22
... determined that the damage in certain areas of the State of Iowa resulting from flooding beginning on May 25... eligible to apply for assistance under the Hazard Mitigation Grant Program. The following Catalog of... of a major disaster for the State of Iowa (FEMA-1998-DR), dated June 27, 2011, and related...
Georgiev, Lachezar S.
2006-12-01
We extend the topological quantum computation scheme using the Pfaffian quantum Hall state, which has been recently proposed by Das Sarma , in a way that might potentially allow for the topologically protected construction of a universal set of quantum gates. We construct, for the first time, a topologically protected controlled-NOT gate, which is entirely based on quasihole braidings of Pfaffian qubits. All single-qubit gates, except for the π/8 gate, are also explicitly implemented by quasihole braidings. Instead of the π/8 gate we try to construct a topologically protected Toffoli gate, in terms of the controlled-phase gate and CNOT or by a braid-group-based controlled-controlled- Z precursor. We also give a topologically protected realization of the Bravyi-Kitaev two-qubit gate g3 .
International Nuclear Information System (INIS)
Riess, J.; Duport, C.
1991-01-01
We report the first numerical results (with realistic parameter values) for the time evolution of a scattered Landau function in a model system. They give a striking illustration for the Hall velocity increase beyond the classical value of the conduction electrons in the quantum Hall regime. This phenomenon, which is crucial for the integer quantum Hall effect, is caused by a special kind of nonclassical particle dynamics induced by disorder and cannot be described by linear response theory
National Geochemical Survey Locations and Results for Iowa
Iowa State University GIS Support and Research Facility — The United States Geological Survey (USGS), in collaboration with other state and federal agencies, industry, and academia, is conducting a National Geochemical...
Iowa Breed Bird Atlas 2, 2008-2012
Iowa State University GIS Support and Research Facility — These are the locations of Iowa's Second Breeding Bird Atlas. Blocks are 3 by 3 miles in size. Some of the blocks are the same as those surveyed in the first BBA,...
75 FR 65390 - Iowa Disaster Number IA-00024
2010-10-22
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12279 and 12280] Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 5. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of Iowa (FEMA--1930--DR), dated 08/14/ 2010...
75 FR 51506 - Iowa Disaster Number IA-00026
2010-08-20
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12258 and 12259] Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 1930-DR...
75 FR 62897 - Iowa Disaster Number IA-00024
2010-10-13
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12279 and 12280] Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 4. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of IOWA (FEMA-1930-DR), dated 08/14/2010. Incident...
78 FR 53492 - Iowa Disaster Number IA-00053
2013-08-29
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13699 and 13700] Iowa Disaster Number IA-00053 AGENCY: U.S. Small Business Administration. Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 4135-DR...
75 FR 52048 - Iowa Disaster Number IA-00024
2010-08-24
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12279 and 12280] Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of Iowa (FEMA-1930-DR), dated 08/14/2010. Incident...
76 FR 80446 - Iowa Disaster Number IA-00033
2011-12-23
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12895 and 12896] Iowa Disaster Number IA-00033 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of Iowa (FEMA-1998-DR), dated 10/18/2011. Incident...
75 FR 59750 - Iowa Disaster Number IA-00026
2010-09-28
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12258 and 12259] Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 5. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 1930-DR...
75 FR 57996 - Iowa Disaster Number IA-00026
2010-09-23
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12258 and 12259] Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 4. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 1930-DR...
75 FR 17178 - Iowa Disaster Number IA-00023
2010-04-05
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12062 and 12063] Iowa Disaster Number IA-00023 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 1880-DR...
75 FR 57088 - Iowa Disaster Number IA-00026
2010-09-17
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12258 and 12259] Iowa Disaster Number IA-00026 AGENCY: U.S. Small Business Administration. ACTION: Amendment 3. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 1930-DR...
75 FR 57997 - Iowa Disaster Number IA-00024
2010-09-23
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12279 and 12280] Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 2. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of Iowa (FEMA-1930-DR), dated 08/14/2010. Incident...
75 FR 58451 - Iowa Disaster Number IA-00024
2010-09-24
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12279 and 12280] Iowa Disaster Number IA-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment 3. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for the State of Iowa (FEMA-1930-DR), dated 08/14/2010. Incident...
78 FR 38781 - Iowa Disaster Number IA-00052
2013-06-27
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13605 and 13606] Iowa Disaster Number IA-00052 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 4119-DR...
76 FR 56863 - Iowa Disaster Number IA-00036
2011-09-14
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12754 and 12755] Iowa Disaster Number IA-00036 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA- 1998-DR...
78 FR 51262 - Iowa Disaster Number IA-00054
2013-08-20
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13645 and 13646] Iowa Disaster Number IA-00054 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Presidential declaration of a major disaster for Public Assistance Only for the State of Iowa (FEMA-- 4126--DR...
International Nuclear Information System (INIS)
Ciftja, O.
1999-01-01
The microscopic approach for studying the half-filled state of the fractional quantum Hall effect is based on the idea of proposing a trial Fermi wave function of the Jastrow-Slater form, which is then fully projected onto the lowest Landau level. A simplified starting point is to drop the projection operator and to consider an unprojected wave function. A recent study claims that such a wave function approximated in a Jastrow form may still constitute a good starting point on the study of the half-filled state. In this paper we formalize the effective hypernetted-chain approximation and apply it to the unprojected Fermi wave function, which describes the even-denominator-filling states. We test the above approximation by using the Fermi hypernetted-chain theory, which constitutes the natural choice for the present case. Our results suggest that the approximation of the Slater determinant of plane waves as a Jastrow wave function may not be a very accurate approximation. We conclude that the lowest Landau-level projection operator cannot be neglected if one wants a better quantitative understanding of the phenomena. copyright 1999 The American Physical Society
Krivoruchko, D. D.; Skrylev, A. V.
2018-01-01
The article deals with investigation of the excited states populations distribution of a low-temperature xenon plasma in the thruster with closed electron drift at 300 W operating conditions were investigated by laser-induced fluorescence (LIF) over the 350-1100 nm range. Seven xenon ions (Xe II) transitions were analyzed, while for neutral atoms (Xe I) just three transitions were explored, since the majority of Xe I emission falls into the ultraviolet or infrared part of the spectrum and are difficult to measure. The necessary spontaneous emission probabilities (Einstein coefficients) were calculated. Measurements of the excited state distribution were made for points (volume of about 12 mm3) all over the plane perpendicular to thruster axis in four positions on it (5, 10, 50 and 100 mm). Measured LIF signal intensity have differences for each location of researched point (due to anisotropy of thruster plume), however the structure of states populations distribution persisted at plume and is violated at the thruster exit plane and cathode area. Measured distributions show that for describing plasma of Hall thruster one needs to use a multilevel kinetic model, classic model can be used just for far plume region or for specific electron transitions.
Sgourakis, Nikolaos G; Yau, Wai-Ming; Qiang, Wei
2015-01-06
Determining the structures of amyloid fibrils is an important first step toward understanding the molecular basis of neurodegenerative diseases. For β-amyloid (Aβ) fibrils, conventional solid-state NMR structure determination using uniform labeling is limited by extensive peak overlap. We describe the characterization of a distinct structural polymorph of Aβ using solid-state NMR, transmission electron microscopy (TEM), and Rosetta model building. First, the overall fibril arrangement is established using mass-per-length measurements from TEM. Then, the fibril backbone arrangement, stacking registry, and "steric zipper" core interactions are determined using a number of solid-state NMR techniques on sparsely (13)C-labeled samples. Finally, we perform Rosetta structure calculations with an explicitly symmetric representation of the system. We demonstrate the power of the hybrid Rosetta/NMR approach by modeling the in-register, parallel "Iowa" mutant (D23N) at high resolution (1.2Å backbone rmsd). The final models are validated using an independent set of NMR experiments that confirm key features. Copyright © 2015 Elsevier Ltd. All rights reserved.
Tunable hybridization of Majorana bound states at the quantum spin Hall edge
Keidel, Felix; Burset, Pablo; Trauzettel, Björn
2018-02-01
Confinement at the helical edge of a topological insulator is possible in the presence of proximity-induced magnetic (F) or superconducting (S) order. The interplay of both phenomena leads to the formation of localized Majorana bound states (MBS) or likewise (under certain resonance conditions) the formation of ordinary Andreev bound states (ABS). We investigate the properties of bound states in junctions composed of alternating regions of F or S barriers. Interestingly, the direction of magnetization in F regions and the relative superconducting phase between S regions can be exploited to hybridize MBS or ABS at will. We show that the local properties of MBS translate into a particular nonlocal superconducting pairing amplitude. Remarkably, the symmetry of the pairing amplitude contains information about the nature of the bound state that it stems from. Hence this symmetry can in principle be used to distinguish MBS from ABS, owing to the strong connection between local density of states and nonlocal pairing in our setup.
National Aeronautics and Space Administration — I propose to investigate the newly discovered oscillation modes specific to Magnetically Shied (MS) Hall Effect Thrusters (HET). Although HETs are classified as a...
United State Collaboration working in the ATLAS hall experiment (B180).
Maximilien Brice
2006-01-01
It's a small world; at least you might think so after a visit to Building 180. Inside, about 30 engineers and physicists weld, measure and hammer away. They hail from Pakistan, Israel, Japan, China, Russia and the United States and they work toward one common goal: the completion of the ATLAS muon chamber endcaps.
United State Collaboration working in the Atlas hall experiment (B180).
Maximilien Brice
2006-01-01
It's a small world; at least you might think so after a visit to Building 180. Inside, about 30 engineers and physicists weld, measure and hammer away. They hail from Pakistan, Israel, Japan, China, Russia and the United States and they work toward one common goal: the completion of the ATLAS muon chamber endcaps
Zamaere, Christine Berkesch; Griffeth, Stephen; Sam, Steven V.
2014-08-01
We show that for Jack parameter α = -( k + 1)/( r - 1), certain Jack polynomials studied by Feigin-Jimbo-Miwa-Mukhin vanish to order r when k + 1 of the coordinates coincide. This result was conjectured by Bernevig and Haldane, who proposed that these Jack polynomials are model wavefunctions for fractional quantum Hall states. Special cases of these Jack polynomials include the wavefunctions of Laughlin and Read-Rezayi. In fact, along these lines we prove several vanishing theorems known as clustering properties for Jack polynomials in the mathematical physics literature, special cases of which had previously been conjectured by Bernevig and Haldane. Motivated by the method of proof, which in the case r = 2 identifies the span of the relevant Jack polynomials with the S n -invariant part of a unitary representation of the rational Cherednik algebra, we conjecture that unitary representations of the type A Cherednik algebra have graded minimal free resolutions of Bernstein-Gelfand-Gelfand type; we prove this for the ideal of the ( k + 1)-equals arrangement in the case when the number of coordinates n is at most 2 k + 1. In general, our conjecture predicts the graded S n -equivariant Betti numbers of the ideal of the ( k + 1)-equals arrangement with no restriction on the number of ambient dimensions.
Quasiclassical approach to the weak levitation of extended states in the quantum Hall effect
Fogler, M. M.
1997-01-01
The two-dimensional motion of a charged particle in a random potential and a transverse magnetic field is believed to be delocalized only at discrete energies $E_N$. In strong fields there is a small positive deviation of $E_N$ from the center of the $N$th Landau level, which is referred to as the ``weak levitation'' of the extended state. I calculate the size of the weak levitation effect for the case of a smooth random potential re-deriving earlier results of Haldane and Yang [PRL 78, 298 (...
Coimbatore Balram, Ajit; Wójs, Arkadiusz; Jain, Jainendra
2014-03-01
Exact diagonalization studies have revealed that the energy spectrum of interacting electrons in the lowest Landau level splits, non-perturbatively, into bands. The theory of nearly free composite fermions (CFs) has been shown to be valid for the lowest band, and thus to capture the low temperature physics, but it over-predicts the number of states for the excited bands. We explain the state counting of higher bands in terms of composite fermions with an infinitely strong short range interaction between a CF particle and a CF hole. This interaction, the form of which we derive from the microscopic CF theory, eliminates configurations containing certain tightly bound CF excitons. With this modification, the CF theory reproduces, for all well-defined excited bands, an exact counting for ν > 1 / 3 , and an almost exact counting for ν The resulting insight clarifies that the corrections to the nearly free CF theory are not thermodynamically significant at sufficiently low temperatures, thus providing a microscopic explanation for why it has proved successful for the analysis of the various properties of the CF Fermi sea. NSF grants DMR-1005536 and DMR-0820404, Polish NCN grant 2011/01/B/ST3/04504 and EU Marie Curie Grant PCIG09-GA-2011-294186, Research Computing and Cyberinfrastructure, PSU and Wroclaw Centre for Networking and Supercomputing
Emergence of Dirac and quantum spin Hall states in fluorinated monolayer As and AsSb
Zhang, Qingyun
2016-01-21
Using first-principles calculations, we investigate the electronic and vibrational properties of monolayer As and AsSb. While the pristine monolayers are semiconductors (direct band gap at the Γ point), fluorination results in Dirac cones at the K points. Fluorinated monolayer As shows a band gap of 0.16 eV due to spin-orbit coupling, and fluorinated monolayer AsSb a larger band gap of 0.37 eV due to inversion symmetry breaking. Spin-orbit coupling induces spin splitting similar to monolayer MoS2. Phonon calculations confirm that both materials are dynamically stable. Calculations of the edge states of nanoribbons by the tight-binding method demonstrate that fluorinated monolayer As is topologically nontrivial in contrast to fluorinated monolayer AsSb.
1983-12-01
In A COMPARATIVE ANALYSIS OF PATIENT ACCESS MODES AT WILFORD HALL UNITED STATES AIR FORCE MEDICAL CENTER N AND SELECTED CIVILIAN MEDICAL CENTERS0 N...current patient access modes at WHMC and several civilian medical centers of comparable size. This project has pursued the subject of patient access in...selected civilian medical centers which are comparable to WHMC in size, specialty mix, workload, and mission, providing responsive and efficient patient
Quasiclassical approach to the weak levitation of extended states in the quantum Hall effect
International Nuclear Information System (INIS)
Fogler, M.M.
1998-01-01
The two-dimensional motion of a charged particle in a random potential and a transverse magnetic field is believed to be delocalized only at discrete energies E N . In strong fields there is a small positive deviation of E N from the center of the Nth Landau level, which is referred to as the open-quotes weak levitationclose quotes of the extended state. I calculate the size of the weak levitation effect for the case of a smooth random potential rederiving earlier results of Haldane and Yang [Phys. Rev. Lett. 78, 298 (1997)] and extending their approach to lower magnetic fields. I find that as the magnetic field decreases, this effect remains weak down to the lowest field B min where such a quasiclassical approach is still justified. Moreover, in the immediate vicinity of B min the weak levitation becomes additionally suppressed. This indicates that the open-quotes strong levitationclose quotes expected at yet even lower magnetic fields must be of a completely different origin. copyright 1998 The American Physical Society
Engineering a Robust Quantum Spin Hall State in Graphene via Adatom Deposition
Directory of Open Access Journals (Sweden)
Conan Weeks
2011-10-01
Full Text Available The 2007 discovery of quantized conductance in HgTe quantum wells delivered the field of topological insulators (TIs its first experimental confirmation. While many three-dimensional TIs have since been identified, HgTe remains the only known two-dimensional system in this class. Difficulty fabricating HgTe quantum wells has, moreover, hampered their widespread use. With the goal of breaking this logjam, we provide a blueprint for stabilizing a robust TI state in a more readily available two-dimensional material—graphene. Using symmetry arguments, density functional theory, and tight-binding simulations, we predict that graphene endowed with certain heavy adatoms realizes a TI with substantial band gap. For indium and thallium, our most promising adatom candidates, a modest 6% coverage produces an estimated gap near 80 K and 240 K, respectively, which should be detectable in transport or spectroscopic measurements. Engineering such a robust topological phase in graphene could pave the way for a new generation of devices for spintronics, ultra-low-dissipation electronics, and quantum information processing.
Iowa Department of Transportation. - Clean Water Act Public Notice
The EPA is providing notice of a proposed Administrative Penalty Assessment against Iowa Department of Transportation, a state agency with its primary office located at 800 Lincoln Way, Ames, IA 50010, for alleged violations at two roadway construction pro
Current and Historic Sinkhole and Depression locations in Iowa
Iowa State University GIS Support and Research Facility — This dataset is all of the sinkholes and depressions that originated from the SSURGO spot data, and has been updated using LiDAR and historic photography to capture...
The effect of Ni and Fe doping on Hall anomaly in vortex state of doped YBCO samples
Directory of Open Access Journals (Sweden)
M Nazarzadeh
2010-09-01
Full Text Available We have investigated hall effect on YBa2Cu3-xMxO7-δ (M=Ni, Fe bulk samples, with dopant amount 0 ≤ x ≤ 0.045 for Ni and 0 ≤ x ≤ 0.03 for Fe, with magnetic field (H=2.52, 4.61, 6.27 kOe perpendicular to sample’s surface with constant current 100 mA. Our study shows that as both dopants increases, TC decreases and it decreases faster by Ni . In these ranges of dopant and magnetic field the Hall sign reversal has been observed in all samples once and also ∆max has occurred in lower temperatures, its magnitude increases by Ni, and in Fe doped samples except in sample with dopant amount x=0.03, which almost decreases, that it can show effect of magnetic doping on hall effect.
International Nuclear Information System (INIS)
Eaves, L.
2001-01-01
The breakdown of the integer quantum Hall effect at high currents sometimes occurs a series of regular steps in the dissipative voltage drop bars used to maintain the US Resistance Standard, but have also been reported in other devices. It is proposed that the origin of the steps can be understood in terms of instability in the dissipationless flow at high electron drift velocities. The instability is induced by impurity- or defect- related inter-Landau level scattering processes in local macroscopic regions of the Hall bar. Electron-hole pairs (magneto-excitons) are generated in the quantum Hall fluid in these regions and that the electronic motion can be envisaged as a quantum analogue of the Karman vortex street which forms when a classical fluid flows past an obstacle. (author)
Anode sheath in Hall thrusters
International Nuclear Information System (INIS)
Dorf, L.; Semenov, V.; Raitses, Y.
2003-01-01
A set of hydrodynamic equations is used to describe quasineutral plasma in ionization and acceleration regions of a Hall thruster. The electron distribution function and Poisson equation are invoked for description of a near-anode region. Numerical solutions suggest that steady-state operation of a Hall thruster can be achieved at different anode sheath regimes. It is shown that the anode sheath depends on the thruster operating conditions, namely the discharge voltage and the mass flow rate
Optimization of Cylindrical Hall Thrusters
International Nuclear Information System (INIS)
Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fisch, Nathaniel J.
2007-01-01
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.
Optimization of Cylindrical Hall Thrusters
International Nuclear Information System (INIS)
Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fi, Nathaniel J.
2007-01-01
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation
Observation of the Zero Hall Plateau in a Quantum Anomalous Hall Insulator
Energy Technology Data Exchange (ETDEWEB)
Feng, Yang; Feng, Xiao; Ou, Yunbo; Wang, Jing; Liu, Chang; Zhang, Liguo; Zhao, Dongyang; Jiang, Gaoyuan; Zhang, Shou-Cheng; He, Ke; Ma, Xucun; Xue, Qi-Kun; Wang, Yayu
2015-09-16
We report experimental investigations on the quantum phase transition between the two opposite Hall plateaus of a quantum anomalous Hall insulator. We observe a well-defined plateau with zero Hall conductivity over a range of magnetic field around coercivity when the magnetization reverses. The features of the zero Hall plateau are shown to be closely related to that of the quantum anomalous Hall effect, but its temperature evolution exhibits a significant difference from the network model for a conventional quantum Hall plateau transition. We propose that the chiral edge states residing at the magnetic domain boundaries, which are unique to a quantum anomalous Hall insulator, are responsible for the novel features of the zero Hall plateau.
Joireman, Jeff; Abbott, Martin L.
This report examines the overlap between student test results on the Iowa Test of Basic Skills (ITBS) and the Washington Assessment of Student Learning (WASL). The two tests were compared and contrasted in terms of content and measurement philosophy, and analyses studied the statistical relationship between the ITBS and the WASL. The ITBS assesses…
Mark D. Nelson; Matt Brewer; Christopher W. Woodall; Charles H. Perry; Grant M. Domke; Ronald J. Piva; Cassandra M. Kurtz; W. Keith Moser; Tonya W. Lister; Brett J. Butler; Dacia M. Meneguzzo; Patrick D. Miles; Charles J. Barnett; Dale Gormanson
2011-01-01
The second full annual inventory of Iowa's forests (2004-2008) reports more than 3 million acres of forest land, almost all of which is timberland (98 percent), with an average volume of more than 1,000 cubic feet of growing stock per acre. American elm and eastern hophornbeam are the most numerous tree species, but silver maple and bur oak predominate in terms of...
Eastern Iowa, Northwestern Illinois
1973-01-01
This view of the Mississippi and Iowa River Valleys (41.5N, 90.5W) shows the rich agricultural region of the upper midwest. Most of the farms occupy one statute mile squares bounded by roads that coincide with the section lines used in the township and range system of surveying practiced in the U.S. central plains, the heart of the great corn belt. Other crops grown in the region include oats, soybeans, hay and alfalfa.
Quantum Hall Electron Nematics
MacDonald, Allan
In 2D electron systems hosted by crystals with hexagonal symmetry, electron nematic phases with spontaneously broken C3 symmetry are expected to occur in the quantum Hall regime when triplets of Landau levels associated with three different Fermi surface pockets are partially filled. The broken symmetry state is driven by intravalley Coulombic exchange interactions that favor spontaneously polarized valley occupations. I will discuss three different examples of 2D electron systems in which this type of broken symmetry state is expected to occur: i) the SnTe (111) surface, ii) the Bi (111) surface. and iii) unbalanced bilayer graphene. This type of quantum Hall electron nematic state has so far been confirmed only in the Bi (111) case, in which the anisotropic quasiparticle wavefunctions of the broken symmetry state were directly imaged. In the SnTe case the nematic state phase boundary is controlled by a competition between intravalley Coulomb interactions and intervalley scattering processes that increase in relative strength with magnetic field. An in-plane Zeeman field alters the phase diagram by lifting the three-fold Landau level degeneracy, yielding a ground state energy with 2 π/3 periodicity as a function of Zeeman-field orientation angle. I will comment on the possibility of observing similar states in the absence of a magnetic field. Supported by DOE Division of Materials Sciences and Engineering Grant DE-FG03-02ER45958.
Experimental halls workshop summary
International Nuclear Information System (INIS)
Thorndike, A.
1976-01-01
A brief discussion is given of: (1) pros and cons of open areas as compared with enclosed halls; (2) experimental hall needs of ep, anti p p, and other options; (3) hall for the lepton detector; and, (4) hall for the hadron spectrometer
Experimental halls workshop summary
International Nuclear Information System (INIS)
Thorndike, A.
1976-01-01
On May 26 and 27, 1976, approximately 50 people met for an informal workshop on plans for experimental halls for ISABELLE. Plans as they exist in the May 1976 version of the ISABELLE proposal were presented. Discussions were held on the following four general topics by separate working groups: (1) pros and cons of open areas as compared with enclosed halls; (2) experimental hall needs of ep, anti pp, and other options; (3) hall for the lepton detector; and (4) hall for the hadron spectrometer. The planning for experimental halls at PEP, the hall for the lepton detector, the hadron spectrometer, and open areas are discussed
Experimental halls workshop summary
International Nuclear Information System (INIS)
Thorndike, A.
1976-01-01
At the experimental halls workshop, discussions were held on: (1) open areas as compared with enclosed halls; (2) the needs of ep, anti pp, and other options; (3) the hall for the lepton detector; and (4) the hall for the hadron spectrometer. The value of different possibilities for the future experimental program was explored. A number of suggestions emerged which will be used as the design of the experimental halls progresses
Evaluation of Optimal Distribution of Wind Power Facilities in Iowa for 2015
Energy Technology Data Exchange (ETDEWEB)
Factor, T. (Iowa Wind Energy Institute); Milligan, M. (National Renewable Energy Laboratory)
1999-08-05
By the end of June 1999, about 250 megawatts of wind generation will have been dedicated in the state of Iowa. This represents the beginning of what is likely to be significant wind capacity development during the next 20 years in the state, as a result of possible public and governmental mandates and consumers' desire for sustainable sources of energy. As the utility industry in the United States moves towards a new structure, renewable energy sources continue to be an important part of new resource development. In this paper, we consider the predicted trends in load growth in Iowa. After accounting for the retirement of nuclear and older fossil fuel facilities over the next 15 years, we estimate Iowa's potential renewable generating capacity through the year 2015 and anticipate the contribution of wind energy to Iowa's portfolio. The Iowa Wind Energy Institute (IWEI) has been monitoring the wind resource in Iowa since June 1994 to obtain wind speed averages at 10, 33 and 50 meters above ground at fourteen geographically dispersed potential wind farm sites. Winds in the Midwest are primarily generated by fronts moving through the region. The Northwest Buffalo Ridge area of Iowa typically has wind speed averages of 7-8 m/s. Central Iowa may have typical winds slightly below this mean value. However, as a front passes through the state, there will be times when a wind farm in Central Iowa will produce more energy than one on Buffalo Ridge.
Carruthers, Cheryl; Lampe, Karen
2011-01-01
Over the last year, "School Library Monthly" ("SLM") has challenged school librarians to "nudge toward inquiry" through the "SLM" blog-driven submissions compiled by Kristin Fontichiaro. Iowa took up the challenge! This article describes how teacher librarians across Iowa teamed with classroom teachers to…
Frese, Millie K., Ed.
1998-01-01
"The Goldfinch" is a magazine oriented toward young children and intended to introduce said audience to many different aspects of Iowa history. Each issue focuses on a different topic, and features a number of articles that discuss the topic in more depth. The topic for this issue is Iowa Inventors. Featured articles highlight women…
Iowa's Forest Resources in 1999
Joseph T. II Boykin
2002-01-01
The North Central Research Station's Forest Inventory and Analysis Program began fieldwork for the fourth forest inventory of Iowa in 1999. This inventory initiates a new annual inventory system. This Research Note contains preliminary estimates of Iowa's forest resources prepared from data gathered during the first year of the inventory.
Spin-singlet hierarchy in the fractional quantum Hall effect
Ino, Kazusumi
1999-01-01
We show that the so-called permanent quantum Hall states are formed by the integer quantum Hall effects on the Haldane-Rezayi quantum Hall state. Novel conformal field theory description along with this picture is deduced. The odd denominator plateaux observed around $\
Iowa State University GIS Support and Research Facility — Air emission points for facilities in Iowa with operating permits for Title V of the Federal Clean Air Act, considered "major" permits. Also includes emission points...
Demir, I.; Krajewski, W. F.; Goska, R.; Mantilla, R.; Weber, L. J.; Young, N.
2011-12-01
The Iowa Flood Information System (IFIS) is a web-based platform developed by the Iowa Flood Center (IFC) to provide access to flood inundation maps, real-time flood conditions, flood forecasts both short-term and seasonal, flood-related data, information and interactive visualizations for communities in Iowa. The key element of the system's architecture is the notion of community. Locations of the communities, those near streams and rivers, define basin boundaries. The IFIS provides community-centric watershed and river characteristics, weather (rainfall) conditions, and streamflow data and visualization tools. Interactive interfaces allow access to inundation maps for different stage and return period values, and flooding scenarios with contributions from multiple rivers. Real-time and historical data of water levels, gauge heights, and rainfall conditions are available in the IFIS by streaming data from automated IFC bridge sensors, USGS stream gauges, NEXRAD radars, and NWS forecasts. Simple 2D and 3D interactive visualizations in the IFIS make the data more understandable to general public. Users are able to filter data sources for their communities and selected rivers. The data and information on IFIS is also accessible through web services and mobile applications. The IFIS is optimized for various browsers and screen sizes to provide access through multiple platforms including tablets and mobile devices. The IFIS includes a rainfall-runoff forecast model to provide a five-day flood risk estimate for around 500 communities in Iowa. Multiple view modes in the IFIS accommodate different user types from general public to researchers and decision makers by providing different level of tools and details. River view mode allows users to visualize data from multiple IFC bridge sensors and USGS stream gauges to follow flooding condition along a river. The IFIS will help communities make better-informed decisions on the occurrence of floods, and will alert communities
Allen, H M
1994-10-01
This project developed and tested a population-based survey, the HS Form, to examine health and health care in the Central Iowa community. Data from this new collection of proven sets of items were used to compare competing health plans, doctor offices, hospitals, and to develop preliminary norms of the community's insured, in two areas: system performance and health burden. The results showed that the survey: (1) was both feasible and efficient in delivering a comprehensive and generic assessment of consumers and patients; (2) revealed consistent, noteworthy differences between plans and between providers across both sets of criteria; and (3) indicated that there is substantial room for improvement in Central Iowa's health care delivery system from the public's perspective. Recommendations for next steps include: (1) following through on the June 1993 community forum (held to discuss the project's methods and results with local decision makers); (2) broadening the evaluation design to increase sample representativeness; and (3) implementing a pre/post approach to measure changes in plan and provider performance.
Dexter, Franklin; Jarvie, Craig; Epstein, Richard H
2018-03-01
Previously, we studied the relative importance of different institutional interventions that the largest hospital in Iowa could take to grow the anesthesia department's outpatient surgical care. Most (>50%) patients having elective surgery had not previously had surgery at the hospital. Patient perioperative experience was unimportant for influencing total anesthesia workload and numbers of patients. More important was the availability of surgical clinic appointments within several days. These results would be generalizable if the median time from surgery to a patient's next surgical procedure was large (eg, >2 years), among all hospitals in Iowa with outpatient surgery, and without regard to the hospital where the next procedure was performed. There were 37,172 surgical cases at hospital outpatient departments of any of the 117 hospitals in Iowa from July 1, 2013, to September 30, 2013. Data extracted about each case included its intraoperative work relative value units. The 37,172 cases were matched to all inpatient and outpatient records for the next 2 years statewide using patient linkage identifiers; from these were determined whether the patient had surgery again within 2 years. Furthermore, the cases' 1820 surgeons were matched to the surgeon's next outpatient or inpatient case, both including and excluding other cases performed on the date of the original case. By patient, the median time to their next surgical case, either outpatient or inpatient, exceeded 2 years, tested with weighting by intraoperative relative value units and repeated when unweighted (both P 2 years for patients versus 1 day for surgeons. Thus, although patients' experiences are an important attribute of quality of care, surgeons' experiences are orders of magnitude more important from the vantage point of marketing and growth of an anesthesia practice.
Destruction of the fractional quantum Hall effect by disorder
International Nuclear Information System (INIS)
Laughlin, R.B.
1985-07-01
It is suggested that Hall steps in the fractional quantum Hall effect are physically similar to those in the ordinary quantum Hall effect. This proposition leads to a simple scaling diagram containing a new type of fixed point, which is identified with the destruction of the fractional states by disorder. 15 refs., 3 figs
International Nuclear Information System (INIS)
Joynt, R.J.
1982-01-01
A general investigation of the electronic structure of two dimensional systems is undertaken with a view towards understanding the quantum Hall effect. The work is limited to the case of a strong perpendicular magnetic field, with a disordered potential and an externally applied electric field. The electrons are treated as noninteracting. First, the scattering theory of the system is worked out. The surprising result is found that a wavepacket will reform after scattering from an isolated potential. Also it will tend to be accelerated in the neighborhood of the scatterer if the potential has bound states. Fredholm theory can then be used to show that the extended states carry an additional current which compensates for the zero current of the bound states. Together, these give the quantized conductance. The complementary case of a smooth random potential is treated by a path-integral approach which exploits the analogies to the classical equations of motion. The Green's function can be calculated approximately, which gives the general character of both the bound and extended states. Also the ratio of these two types of states can be computed for a given potential. The charge density is uniform in first approximation, and the Hall conductance is quantized. Higher-order corrections for more rapidly fluctuating potential are calculated. The most general conditions under which the conductance is quantized are discussed. Because of the peculiar scattering properties of the system, numerical solution of the Schroedinger equation is of interest, both to confirm the analytical results, and for pedagogical reasons. The stability and convergence problems inherent in the computer solution of the problem are analyzed. Results for some model scattering potentials are presented
Forest statistics for Iowa, 1990.
Gary J. Brand; John T. Walkowiak
1991-01-01
Reports results of the third inventory of Iowa that was completed in 1990. Highlights the results of the inventory and contains detailed tables of forest area, timber volume, growth, removals, mortality, and ownership.
Maximilien Brice
2002-01-01
Since 1992, after its move from the 600 MeV SC, ISOLDE is a customer of the Booster (then 1 GeV, now 1.4 GeV). The intense Booster beam (some 3E13 protons per pulse) is directed onto a target, from which a mixture of isotopes emanates. After ionization and electrostatic acceleration to 60 keV, they enter one of the 2 spectrometers (General Purpose Separator: GPS, and High Resolution Separator: HRS) from which the selected ions are directed to the experiments. The photos show: the REX-ISOLDE post accelerator; the mini-ball experiment; an overview of the ISOLDE hall. In the picture (_12) of the hall, the separators are behind the wall. From either of them, beams can be directed into any of the many beamlines towards the experiments, some of which are visible in the foreground. The elevated cubicle at the left is EBIS (Electron Beam Ion Source), which acts as a charge-state multiplier for the REX facility. The ions are further mass analzyzed and passed on to the linac which accelerates them to higher energies. T...
The infrared Hall effect in YBCO: Temperature and frequency dependence of Hall scattering
International Nuclear Information System (INIS)
Grayson, M.; Cerne, J.; Drew, H.D.; Schmadel, D.C.; Hughes, R.; Preston, J.S.; Kung, P.J.; Vale, L.
1999-01-01
The authors measure the Hall angle, θ H , in YBCO films in the far- and mid-infrared to determine the temperature and frequency dependence of the Hall scattering. Using novel modulation techniques they measure both the Faraday rotation and ellipticity induced by these films in high magnetic fields to deduce the complex conductivity tensor. They observe a strong temperature dependence of the mid-infrared Hall conductivity in sharp contrast to the weak dependence of the longitudinal conductivity. By fitting the frequency dependent normal state Hall angle to a Lorentzian θ H (ω) = ω H /(γ H minus iω) they find the Hall frequency, ω H , is nearly independent of temperature. The Hall scattering rate, γ H , is consistent with γ H ∼ T 2 up to 200 K and is remarkably independent of IR frequency suggesting non-Fermi liquid behavior
Novel optical probe for quantum Hall system
Indian Academy of Sciences (India)
to explore Landau levels of a two-dimensional electron gas (2DEG) in modulation doped ... Keywords. Surface photovoltage spectroscopy; quantum Hall effect; Landau levels; edge states. ... An optical fibre carries light from tunable diode laser.
Streams in Iowa Listed as Impaired in 2010 Under the Clean Water Act
Iowa State University GIS Support and Research Facility — Under Section 303(d) of the Clean Water Act, states are required from "time to time" to submit a list of waters for which effluent limits will not be sufficient to...
Lakes in Iowa Listed as Impaired in 2010 Under the Clean Water Act
Iowa State University GIS Support and Research Facility — Under Section 303(d) of the Clean Water Act, states are required from "time to time" to submit a list of waters for which effluent limits will not be sufficient to...
Cryogenic microsize Hall sensors
International Nuclear Information System (INIS)
Kvitkovic, J.; Polak, M.
1993-01-01
Hall sensors have a variety of applications in magnetic field measurements. The active area of the Hall sensor does not play an important role in measuring of homogeneous magnetic field. Actually Hall sensors are widely used to measure profiles of magnetic fields produced by magnetization currents in samples of HTC superconductors, as well as of LTC ones. Similar techniques are used to measure magnetization of both HTC and LTC superconductors. In these cases Hall sensor operates in highly inhomogeneous magnetic fields. Because of that, Hall sensors with very small active area are required. We developed and tested Hall sensors with active area 100 μm x 100 μm - type M and 50 μm x 50 μm - type V. Here we report on the most imporant parameters of these units, as well as on their properties as differential magnetometer. (orig.)
Dexter, Franklin; Jarvie, Craig; Epstein, Richard H
2017-11-01
Percentage utilization of operating room (OR) time is not an appropriate endpoint for planning additional OR time for surgeons with high caseloads, and cannot be measured accurately for surgeons with low caseloads. Nonetheless, many OR directors claim that their hospitals make decisions based on individual surgeons' OR utilizations. This incongruity could be explained by the OR managers considering the earlier mathematical studies, performed using data from a few large teaching hospitals, as irrelevant to their hospitals. The important mathematical parameter for the prior observations is the percentage of surgeon lists of elective cases that include 1 or 2 cases; "list" meaning a combination of surgeon, hospital, and date. We measure the incidence among many hospitals. Observational cohort study. 117 hospitals in Iowa from July 2013 through September 2015. Surgeons with same identifier among hospitals. Surgeon lists of cases including at least one outpatient surgical case, so that Relative Value Units (RVU's) could be measured. Averaging among hospitals in Iowa, more than half of the surgeons' lists included 1 or 2 cases (77%; P<0.00001 vs. 50%). Approximately half had 1 case (54%; P=0.0012 vs. 50%). These percentages exceeded 50% even though nearly all the surgeons operated at just 1 hospital on days with at least 1 case (97.74%; P<0.00001 vs. 50%). The cases were not of long durations; among the 82,928 lists with 1 case, the median was 6 intraoperative RVUs (e.g., adult inguinal herniorrhaphy). Accurate confidence intervals for raw or adjusted utilizations are so wide for individual surgeons that decisions based on utilization are equivalent to decisions based on random error. The implication of the current study is generalizability of that finding from the largest teaching hospital in the state to the other hospitals in the state. Copyright © 2017 Elsevier Inc. All rights reserved.
Federal Emergency Management Agency, Department of Homeland Security — This is collection level metadata for LAS and ASCII data files from the statewide Iowa Lidar Project. The Iowa Light Detection and Ranging (LiDAR) Project collects...
Kim, Bom Soo
2018-05-01
We discuss the contribution of magnetic Skyrmions to the Hall viscosity and propose a simple way to identify it in experiments. The topological Skyrmion charge density has a distinct signature in the electric Hall conductivity that is identified in existing experimental data. In an electrically neutral system, the Skyrmion charge density is directly related to the thermal Hall conductivity. These results are direct consequences of the field theory Ward identities, which relate various physical quantities based on symmetries and have been previously applied to quantum Hall systems.
77 FR 25868 - Iowa Regulatory Program
2012-05-02
... reference of applicable portions of 30 CFR part 700 to End from the July 1, 2002, version to the July 1, 2010, version. Additionally, Iowa proposed to revise its Program related to ownership and control by... the Iowa regulatory program (Iowa program) under the Surface Mining Control and Reclamation Act of...
Quantized Hall conductance as a topological invariant
International Nuclear Information System (INIS)
Niu, Q.; Thouless, Ds.J.; Wu, Y.S.
1984-10-01
Whenever the Fermi level lies in a gap (or mobility gap) the bulk Hall conductance can be expressed in a topologically invariant form showing the quantization explicitly. The new formulation generalizes the earlier result by TKNN to the situation where many body interaction and substrate disorder are also present. When applying to the fractional quantized Hall effect we draw the conclusion that there must be a symmetry breaking in the many body ground state. The possibility of writing the fractionally quantized Hall conductance as a topological invariant is also carefully discussed. 19 references
Cheng, Qinghui; Qiang, Wei
2017-06-08
Solid-state nuclear magnetic resonance (ssNMR) spectroscopy has been widely applied to characterize the high-resolution structures of β-amyloid (Aβ) fibrils. While these structures provide crucial molecular insights on the deposition of amyloid plaques in Alzheimer's diseases (AD), ssNMR structures have been rarely used so far as the basis for designing inhibitors. It remains a challenge because the ssNMR-based Aβ fibril structures were usually obtained with sparsely isotope-labeled peptides with limited experimental constraints, where the structural models, especially the side-chain coordinates, showed restricted precision. However, these structural models often possess a higher accuracy within the hydrophobic core regions with more well-defined experimental data, which provide potential targets for the molecular design. This work presents an ssNMR-based molecular design to achieve selective inhibition of a particular type of Aβ fibrillar structure, which was formed with the Iowa mutant of Aβ with parallel-in-register β-sheet hydrophobic core. The results show that short peptides that mimic the C-terminal β-strands of the fibril may have a preference in binding to the parallel Aβ fibrils rather than the antiparallel fibrils, mainly due to the differences in the high-resolution structures in the fibril elongation interfaces. The Iowa mutant Aβ fibrils are utilized in this work mainly as a model to demonstrate the feasibility of the strategy because it is relatively straightforward to distinguish the parallel and antiparallel fibril structures using ssNMR. Our results suggest that it is potentially feasible to design structure-selective inhibitors and/or diagnostic agents to Aβ fibrils using ssNMR-based structural models.
Evaluation of Iowa's anti-bullying law.
Ramirez, Marizen; Ten Eyck, Patrick; Peek-Asa, Corinne; Onwuachi-Willig, Angela; Cavanaugh, Joseph E
2016-12-01
Bullying is the most common form of youth aggression. Although 49 of all 50 states in the U.S. have an anti-bullying law in place to prevent bullying, little is known about the effectiveness of these laws. Our objective was to measure the effectiveness of Iowa's anti-bullying law in preventing bullying and improving teacher response to bullying. Sixth, 8th, and 11th grade children who completed the 2005, 2008 and 2010 Iowa Youth Survey were included in this study (n = 253,000). Students were coded according to exposure to the law: pre-law for 2005 survey data, one year post-law for 2008 data, and three years post-law for 2010 data. The outcome variables were: 1) being bullied (relational, verbal, physical, and cyber) in the last month and 2) extent to which teachers/adults on campus intervened with bullying. Generalized linear mixed models were constructed with random effects. The odds of being bullied increased from pre-law to one year post-law periods, and then decreased from one year to three years post-law but not below 2005 pre-law levels. This pattern was consistent across all bullying types except cyberbullying. The odds of teacher intervention decreased 11 % (OR = 0.89, 95 % CL = 0.88, 0.90) from 2005 (pre-law) to 2010 (post-law). Bullying increased immediately after Iowa's anti-bullying law was passed, possibly due to improved reporting. Reductions in bullying occurred as the law matured. Teacher response did not improve after the passage of the law.
Gore, Deborah, Ed.
1987-01-01
This journal issue explores Iowa's participation in the U.S. Civil War and primarily focuses on what happened to the men, women, and children who remained at home. A number of social, political, and economic changes are examined, including: (1) the increased responsibilities of women and children; (2) the growth of abolitionism; (3) the role of…
Residential Energy Efficiency Potential: Iowa
Energy Technology Data Exchange (ETDEWEB)
Wilson, Eric J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-11-02
Energy used by Iowa single-family homes that can be saved through cost-effective improvements. Prepared by Eric Wilson and Noel Merket, NREL, and Erin Boyd, U.S. Department of Energy Office of Energy Policy and Systems Analysis.
Iowa Community Colleges Accounting Manual.
Iowa State Dept. of Education, Des Moines. Div. of Community Colleges and Workforce Preparation.
This document describes account classifications and definitions for the accounting system of the Iowa community colleges. In view of the objectives of the accounting system, it is necessary to segregate the assets of the community college according to its source and intended use. Additionally, the accounting system should provide for accounting by…
Open Feedlots Listed in the Iowa Department of Natural Resources Animal Feeding Operations Database
Iowa State University GIS Support and Research Facility — Currently, the Animal Feeding Operations (AFO) database does not allow facilities to be queried by watershed, therefore, this coverage was developed to assist with...
The Chicago to Iowa City intercity passenger rail route : business plan.
2011-03-21
Business Plan Highlights : -No Iowa General Fund or RIIF appropriations : -State/local partnership : -Funds operation for the first 10 years : -Local cash commitment to passenger rail : -Conservative and practical financial forecasts : -Three compone...
Historical performance evaluation of Iowa pavement treatments using data analytics : final report.
2016-11-01
The pavement network in Iowa has reached a mature state making maintenance and rehabilitation activities more important than new construction. As such, a need exists to evaluate the performance of the pavement treatments and estimate their performanc...
Calibrating the Iowa pore index with mercury intrusion porosimetry and petrography.
2017-10-31
The Iowa Pore Index (IPI) test is a fast, non-destructive, inexpensive, and environmentally friendly test used by several Midwestern state departments of transportation to determine the volume ratio of macropores to micropores in a coarse rock aggreg...
Elementary theory of quantum Hall effect
Directory of Open Access Journals (Sweden)
Keshav N. Shrivastava
2008-04-01
Full Text Available The Hall effect is the generation of a current perpendicular to both the direction of the applied electric as well as magnetic field in a metal or in a semiconductor. It is used to determine the concentration of electrons. The quantum Hall effect with integer quantization was discovered by von Klitzing and fractionally charged states were found by Tsui, Stormer and Gossard. Robert Laughlin explained the quantization of Hall current by using “flux quantization” and introduced incompressibility to obtain the fractional charge. We have developed the theory of the quantum Hall effect by using the theory of angular momentum. Our predicted fractions are in accord with those measured. We emphasize our explanation of the observed phenomena. We use spin to explain the fractional charge and hence we discover spin-charge locking.
National Oceanic and Atmospheric Administration, Department of Commerce — Salt marsh habitats along the shoreline of Halls Lake are threatened by wave erosion, but the reconstruction of barrier islands to reduce this erosion will modify or...
Unconventional quantum Hall effect in Floquet topological insulators
Tahir, M.
2016-07-27
We study an unconventional quantum Hall effect for the surface states of ultrathin Floquet topological insulators in a perpendicular magnetic field. The resulting band structure is modified by photon dressing and the topological property is governed by the low-energy dynamics of a single surface. An exchange of symmetric and antisymmetric surface states occurs by reversing the lights polarization. We find a novel quantum Hall state in which the zeroth Landau level undergoes a phase transition from a trivial insulator state, with Hall conductivity αyx = 0 at zero Fermi energy, to a Hall insulator state with αyx = e2/2h. These findings open new possibilities for experimentally realizing nontrivial quantum states and unusual quantum Hall plateaus at (±1/2,±3/2,±5/2, ...)e2/h. © 2016 IOP Publishing Ltd Printed in the UK.
Unconventional quantum Hall effect in Floquet topological insulators
Tahir, M.; Vasilopoulos, P.; Schwingenschlö gl, Udo
2016-01-01
We study an unconventional quantum Hall effect for the surface states of ultrathin Floquet topological insulators in a perpendicular magnetic field. The resulting band structure is modified by photon dressing and the topological property is governed by the low-energy dynamics of a single surface. An exchange of symmetric and antisymmetric surface states occurs by reversing the lights polarization. We find a novel quantum Hall state in which the zeroth Landau level undergoes a phase transition from a trivial insulator state, with Hall conductivity αyx = 0 at zero Fermi energy, to a Hall insulator state with αyx = e2/2h. These findings open new possibilities for experimentally realizing nontrivial quantum states and unusual quantum Hall plateaus at (±1/2,±3/2,±5/2, ...)e2/h. © 2016 IOP Publishing Ltd Printed in the UK.
International Nuclear Information System (INIS)
El-Arabi, N. M.
1993-01-01
Transport phenomena in two dimensional semiconductors have revealed unusual properties. In this thesis these systems are considered and discussed. The theories explain the Integral Quantum Hall Effect (IQHE) and the Fractional Quantum Hall Effect (FQHE). The thesis is composed of five chapters. The first and the second chapters lay down the theory of the IQHE, the third and fourth consider the theory of the FQHE. Chapter five deals with the statistics of particles in two dimension. (author). Refs
Composite fermions in the quantum Hall effect
International Nuclear Information System (INIS)
Johnson, B.L.; Kirczenow, G.
1997-01-01
The quantum Hall effect and associated quantum transport phenomena in low-dimensional systems have been the focus of much attention for more than a decade. Recent theoretical development of interesting quasiparticles - 'composite fermions' - has led to significant advances in understanding and predicting the behaviour of two-dimensional electron systems under high transverse magnetic fields. Composite fermions may be viewed as fermions carrying attached (fictitious) magnetic flux. Here we review models of the integer and fractional quantum Hall effects, including the development of a unified picture of the integer and fractional effects based upon composite fermions. The composite fermion picture predicts remarkable new physics: the formation of a Fermi surface at high magnetic fields, and anomalous ballistic transport, thermopower, and surface acoustic wave behaviour. The specific theoretical predictions of the model, as well as the body of experimental evidence for these phenomena are reviewed. We also review recent edge-state models for magnetotransport in low-dimensional devices based on the composite fermion picture. These models explain the fractional quantum Hall effect and transport phenomena in nanoscale devices in a unified framework that also includes edge state models of the integer quantum Hall effect. The features of the composite fermion edge-state model are compared and contrasted with those of other recent edge-state models of the fractional quantum Hall effect. (author)
Construct validity of the Iowa Gambling Task.
Buelow, Melissa T; Suhr, Julie A
2009-03-01
The Iowa Gambling Task (IGT) was created to assess real-world decision making in a laboratory setting and has been applied to various clinical populations (i.e., substance abuse, schizophrenia, pathological gamblers) outside those with orbitofrontal cortex damage, for whom it was originally developed. The current review provides a critical examination of lesion, functional neuroimaging, developmental, and clinical studies in order to examine the construct validity of the IGT. The preponderance of evidence provides support for the use of the IGT to detect decision making deficits in clinical populations, in the context of a more comprehensive evaluation. The review includes a discussion of three critical issues affecting the validity of the IGT, as it has recently become available as a clinical instrument: the lack of a concise definition as to what aspect of decision making the IGT measures, the lack of data regarding reliability of the IGT, and the influence of personality and state mood on IGT performance.
Localization in a quantum spin Hall system.
Onoda, Masaru; Avishai, Yshai; Nagaosa, Naoto
2007-02-16
The localization problem of electronic states in a two-dimensional quantum spin Hall system (that is, a symplectic ensemble with topological term) is studied by the transfer matrix method. The phase diagram in the plane of energy and disorder strength is exposed, and demonstrates "levitation" and "pair annihilation" of the domains of extended states analogous to that of the integer quantum Hall system. The critical exponent nu for the divergence of the localization length is estimated as nu congruent with 1.6, which is distinct from both exponents pertaining to the conventional symplectic and the unitary quantum Hall systems. Our analysis strongly suggests a different universality class related to the topology of the pertinent system.
International Nuclear Information System (INIS)
Klitzing von, K.
1989-01-01
The quantized Hall effect is theoretically explained in detail as are its basic properties. The explanation is completed with the pertinent mathematical relations and illustrative figures. Experimental data are critically assessed obtained by quantum transport measurement in a magnetic field on two-dimensional systems. The results are reported for a MOSFET silicon transistor and for GaAs-Al x Ga 1-x As heterostructures. The application is discussed of the quantized Hall effect in determining the fine structure constant or in implementing the resistance standard. (M.D.). 27 figs., 57 refs
Intrinsic superspin Hall current
Linder, Jacob; Amundsen, Morten; Risinggârd, Vetle
2017-09-01
We discover an intrinsic superspin Hall current: an injected charge supercurrent in a Josephson junction containing heavy normal metals and a ferromagnet generates a transverse spin supercurrent. There is no accompanying dissipation of energy, in contrast to the conventional spin Hall effect. The physical origin of the effect is an antisymmetric spin density induced among transverse modes ky near the interface of the superconductor arising due to the coexistence of p -wave and conventional s -wave superconducting correlations with a belonging phase mismatch. Our predictions can be tested in hybrid structures including thin heavy metal layers combined with strong ferromagnets and ordinary s -wave superconductors.
Remote sensing in Iowa agriculture. [land use, crop identification, and soil mapping
Mahlstede, J. P. (Principal Investigator); Carlson, R. E.; Fenton, T. E.
1974-01-01
The author has identified the following significant results. Analysis of 1972 single-date coverage indicated that a complete crop classification was not attainable at the test sites. Good multi-date coverage during 1973 indicates that many of the problems encountered in 1972 will be minimized. In addition, the compilation of springtime imagery covering the entire state of Iowa has added a new dimension to interpretation of Iowa's natural resources. ERTS-1 has provided data necessary to achieve the broad synoptic view not attainable through other means. This should provide soils and crop researchers and land use planners a base map of Iowa. Granted and due to the resolution of ERTS-1, not all details are observable for many land use planning needs, but this gives a general and current view of Iowa.
Critical current in the Integral Quantum Hall Effect
International Nuclear Information System (INIS)
Kostadinov, I.Z.
1985-11-01
A multiparticle theory of the Integral Quantum Hall Effect (IQHE) was constructed operating with pairs wave function as an order parameter. The IQHE is described with bosonic macroscopic states while the fractional QHE with fermionic ones. The calculation of the critical current and Hall conductivity temperature dependence is presented. (author)
Guterding, Daniel; Jeschke, Harald O; Valentí, Roser
2016-05-17
Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions.
A Local Net Volume Equation for Iowa
Jerold T. Hahn
1976-01-01
As a part of the 1974 Forest Survey of Iowa, the Station''s Forst Resources Evaluatioin Research Staff developed a merchantable tree volume equation and tables of coefficients for Iowa. They were developed for both board-foot (International ?-inch rule) and cubic foot volumes, for several species and species groups of growing-stock trees. The equation and...
New Fellows and Honorary Fellow
Indian Academy of Sciences (India)
Specialization: Chemical Reaction Engineering, Fluidization and Organic Synthesis Engineering ... Department of Chemical Engineering, Iowa State University, 1031, Sweeney Hall, Ames, Iowa 50011-2230, ... Upcoming Refresher Courses.
International Nuclear Information System (INIS)
Avdonin, A.; Skupiński, P.; Grasza, K.
2016-01-01
A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO. - Highlights: • Expressions for Hall coefficient and mobility for hopping conductivity are derived. • Theoretical result is compared with experimental curves measured on ZnO. • Simultaneous action of free and hopping conduction channels is considered. • Non-linearity of hopping Hall coefficient is predicted.
Energy Technology Data Exchange (ETDEWEB)
Avdonin, A., E-mail: avdonin@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Skupiński, P. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Grasza, K. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warszawa (Poland)
2016-02-15
A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO. - Highlights: • Expressions for Hall coefficient and mobility for hopping conductivity are derived. • Theoretical result is compared with experimental curves measured on ZnO. • Simultaneous action of free and hopping conduction channels is considered. • Non-linearity of hopping Hall coefficient is predicted.
Granberg, Donald; Brown, Thad A.
1995-01-01
Examines people's behavior in the Monty Hall Dilemma (MHD), in which a person must make two decisions to win a prize. In a series of five studies, found that people misapprehend probabilities in the MHD. Discusses the MHD's relation to illusion of control, belief perseverance, and the status quo bias. (RJM)
Laurent Guiraud
2000-01-01
General view of the Isotope-Separator On-Line (ISOLDE) hall. ISOLDE is dedicated to the production of a large variety of radioactive ion beams for many different experiments. Rare isotopes can be produced allowing the study of spectra for neutrino beam production.
Oguntoyinbo, Lekan
2011-01-01
Many urban and commuter universities have their sights set on students who are unlikely to connect with the college and likely to fail unless the right strategies are put in place to help them graduate. In efforts to improve retention rates, commuter colleges are looking to an unusual suspect: residence halls. The author discusses how these…
Czech Academy of Sciences Publication Activity Database
Nagaosa, N.; Sinova, Jairo; Onoda, S.; MacDonald, A. H.; Ong, N. P.
2010-01-01
Roč. 82, č. 2 (2010), s. 1539-1592 ISSN 0034-6861 Institutional research plan: CEZ:AV0Z10100521 Keywords : anomalous Hall effect * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 51.695, year: 2010
Coxon, Bruce
2011-01-01
An account is given of the life, scientific contributions, and passing of Laurance David Hall (1938-2009), including his early history and education at the University of Bristol, UK, and the synthesis and NMR spectroscopy of carbohydrates and other natural products during ∼20 years of research and teaching at the University of British Columbia in Vancouver, Canada. Lists of graduate students, post-doctoral fellows, and sabbatical visitors are provided for this period. Following a generous endowment by Dr. Herchel Smith, Professor Hall built a new Department of Medicinal Chemistry at Cambridge University, UK, and greatly expanded his researches into the technology and applications of magnetic resonance imaging (MRI) and zero quantum NMR. MRI technology was applied both to medical problems such as the characterization of cartilage degeneration in knee joints, the measurement of ventricular function, lipid localization in animal models of atherosclerosis, paramagnetic metal complexes of polysaccharides as contrast agents, and studies of many other anatomical features, but also to several aspects of materials analysis, including food analyses, process control, and the elucidation of such physical phenomena as the flow of liquids through porous media, defects in concrete, and the visualization of fungal damage to wood. Professor Hall's many publications, patents, lectures, and honors and awards are described, and also his successful effort to keep the Asilomar facility in Pacific Grove, California as the alternating venue for the annual Experimental NMR Conference. Two memorial services for Professor Hall are remembered. Copyright © 2011 Elsevier Inc. All rights reserved.
Reed, Kathlyn L
2005-01-01
Herbert James Hall, MD (1870-1923), was a pioneer in the systematic and organized study of occupation as therapy for persons with nervous and mental disorders that he called the "work cure." He began his work in 1904 during the early years of the Arts and Crafts Movement in the United States. His primary interest was the disorder neurasthenia, a condition with many symptoms including chronic fatigue, stress, and inability to work or perform everyday tasks. The prevailing treatment of the day was absolute bed rest known as the "rest cure." Hall believed that neurasthenia was not caused by overwork but by faulty living habits that could be corrected through an ordered life schedule and selected occupations. He identified several principles of therapy that are still used today including graded activity and energy conservation. Dr. Adolph Meyer credits Hall for organizing the ideas on the therapeutic use of occupation (Meyer, 1922). Hall also provided the name American Occupational Therapy Association for the professional organization and served as the fourth president. For his many contributions to the profession Hall deserves to be recognized as a major contributor to the development and organization of occupational therapy.
Field theory approach to quantum hall effect
International Nuclear Information System (INIS)
Cabo, A.; Chaichian, M.
1990-07-01
The Fradkin's formulation of statistical field theory is applied to the Coulomb interacting electron gas in a magnetic field. The electrons are confined to a plane in normal 3D-space and also interact with the physical 3D-electromagnetic field. The magnetic translation group (MTG) Ward identities are derived. Using them it is shown that the exact electron propagator is diagonalized in the basis of the wave functions of the free electron in a magnetic field whenever the MTG is unbroken. The general tensor structure of the polarization operator is obtained and used to show that the Chern-Simons action always describes the Hall effect properties of the system. A general proof of the Streda formula for the Hall conductivity is presented. It follows that the coefficient of the Chern-Simons terms in the long-wavelength approximation is exactly given by this relation. Such a formula, expressing the Hall conductivity as a simple derivative, in combination with diagonal form of the full propagator allows to obtain a simple expressions for the filling factor and the Hall conductivity. Indeed, these results, after assuming that the chemical potential lies in a gap of the density of states, lead to the conclusion that the Hall conductivity is given without corrections by σ xy = νe 2 /h where ν is the filling factor. In addition it follows that the filling factor is independent of the magnetic field if the chemical potential remains in the gap. (author). 21 ref, 1 fig
Enhanced Performance of Cylindrical Hall Thrusters
International Nuclear Information System (INIS)
Raitses, Y.; Smirnov, A.; Fisch, N.J.
2007-01-01
The cylindrical thruster differs significantly in its underlying physical mechanisms from the conventional annular Hall thruster. It features high ionization efficiency, quiet operation, ion acceleration in a large volume-to-surface ratio channel, and performance comparable with the state-of-the-art conventional Hall thrusters. Very significant plume narrowing, accompanied by the increase of the energetic ion fraction and improvement of ion focusing, led to 50-60% increase of the thruster anode efficiency. These improvements were achieved by overrunning the discharge current in the magnetized thruster plasma
International Nuclear Information System (INIS)
Jager, K. de
2003-01-01
Proton knock-out is studied in a broad program in Hall A at Jefferson Lab. The first experiment performed in Hall A studied the 16 O(e,e'p) reaction. Since then proton knock-out experiments have studied a variety of aspects of that reaction, from single-nucleon properties to its mechanism, such as final-state interactions and two-body currents, in nuclei from 2 H to 16 O. In this review the accomplishments of this program will be summarized and an outlook given of expected future results. (orig.)
Chicago to Iowa City intercity passenger rail route : business plan.
2011-03-21
This business plan describes the methods by which the Iowa Department of Transportation (DOT will partner with Iowa counties and cities to fund Iowas share of the operating and maintenance cost for the Chicago-Iowa City passenger-rail service, an ...
The fractional quantum Hall effect
International Nuclear Information System (INIS)
Stormer, H.L.
1988-01-01
The fractional quantum Hall effect (FQHE), is the manifestation of a new, highly correlated, many-particle ground state that forms in a two-dimensional electron system at low temperatures and in high magnetic fields. It is an example of the new physics that has grown out of the tremendous recent advances in semiconductor material science, which has provided us with high-quality, lower-dimensional carrier systems. The novel electronic state exposes itself in transport experiments through quantization of the Hall resistance to an exact rational fraction of h/e, and concomitantly vanishing longitudinal resistivity. Its relevant energy scale is only a few degrees kelvin. The quantization is a consequence of the spontaneous formation of an energy gap separating the condensed ground state from its rather elusive quasiparticle excitations. The theoretical understanding of the novel quantum liquids which underlie the FQHE has predominantly emerged from an ingenious many-particle wave function strongly supported by numerous few-particle simulations. Theory has now constructed a complex model for ideal two-dimensional electron systems in the presence of high magnetic fields and makes definitive, often fascinating predictions. Experiments have successively uncovered odd-denominator fractional states reaching presently to 7/13. The application of new experimental tools to the FQHE, such as optics, microwaves, and phonon techniques promises the direct observation of such parameters as the gap energy and possibly even some of the more elusive quantities in the future. While theory and experiment in the FQHE appear to be converging, there remains considerable room for challenging surprises. This paper provides a concise overview of the FQHE. It focuses on the experimental aspects and states, but does not expand on the theoretical advances. 70 refs., 11 figs
Sinova, Jairo; Valenzuela, Sergio O.; Wunderlich, J.; Back, C. H.; Jungwirth, T.
2015-10-01
Spin Hall effects are a collection of relativistic spin-orbit coupling phenomena in which electrical currents can generate transverse spin currents and vice versa. Despite being observed only a decade ago, these effects are already ubiquitous within spintronics, as standard spin-current generators and detectors. Here the theoretical and experimental results that have established this subfield of spintronics are reviewed. The focus is on the results that have converged to give us the current understanding of the phenomena, which has evolved from a qualitative to a more quantitative measurement of spin currents and their associated spin accumulation. Within the experimental framework, optical-, transport-, and magnetization-dynamics-based measurements are reviewed and linked to both phenomenological and microscopic theories of the effect. Within the theoretical framework, the basic mechanisms in both the extrinsic and intrinsic regimes are reviewed, which are linked to the mechanisms present in their closely related phenomenon in ferromagnets, the anomalous Hall effect. Also reviewed is the connection to the phenomenological treatment based on spin-diffusion equations applicable to certain regimes, as well as the spin-pumping theory of spin generation used in many measurements of the spin Hall angle. A further connection to the spin-current-generating spin Hall effect to the inverse spin galvanic effect is given, in which an electrical current induces a nonequilibrium spin polarization. This effect often accompanies the spin Hall effect since they share common microscopic origins. Both can exhibit the same symmetries when present in structures comprising ferromagnetic and nonmagnetic layers through their induced current-driven spin torques or induced voltages. Although a short chronological overview of the evolution of the spin Hall effect field and the resolution of some early controversies is given, the main body of this review is structured from a pedagogical
Estimated Depth to Bedrock of Iowa as a 110 meter pixel_32bit Imagine Format Raster Dataset
Iowa State University GIS Support and Research Facility — This raster dataset represents the depth to bedrock from the land surface. It was derived by subtracting a bedrock surface elevation layer from the NED 30 meter...
Quantum Hall Ferroelectrics and Nematics in Multivalley Systems
Sodemann, Inti; Zhu, Zheng; Fu, Liang
2017-10-01
We study broken symmetry states at integer Landau-level fillings in multivalley quantum Hall systems whose low-energy dispersions are anisotropic. When the Fermi surface of individual pockets lacks twofold rotational symmetry, like in bismuth (111) [Feldman et al. , Observation of a Nematic Quantum Hall Liquid on the Surface of Bismuth, Science 354, 316 (2016), 10.1126/science.aag1715] and in Sn1 -xPbxSe (001) [Dziawa et al., Topological Crystalline Insulator States in Pb1 -xSnxSe , Nat. Mater. 11, 1023 (2012), 10.1038/nmat3449] surfaces, interactions tend to drive the formation of quantum Hall ferroelectric states. We demonstrate that the dipole moment in these states has an intimate relation to the Fermi surface geometry of the parent metal. In quantum Hall nematic states, like those arising in AlAs quantum wells, we demonstrate the existence of unusually robust Skyrmion quasiparticles.
Poplin, A.; Yamu, C.; Rico-Gutierrez, L.
2017-09-01
This paper concentrates on power places as perceived by the students in a 60,000 people college town in the United States. Power places are favourite outdoor locations that evoke positive emotions, and are conducive to relaxation and reduction of stress. Further understanding how location affects those places and the feelings of students will help planners and designers be more intentional as they create conditions favourable to the development of cities that are healthy, sustainable, resilient and smart. Research methodologies used in this paper include empirical cartography, mapping and space syntax. We conclude the paper with a discussion of the presented results and further research directions.
Energy Technology Data Exchange (ETDEWEB)
1984-08-01
This report demonstrates the economic viability of an exterior rewrap retrofit performed on a public community facility for the performing arts. This facility originally consisted of two mess halls built by the American army. The exterior retrofit consisted of constructing a super-insulated passageway to link the two halls as well as completely wrapping the facility with six millimetre polyethylene to provide an airtight barrier. The roofs and walls were reinsulated and insulation levels were increased to RSI 10.5 in the ceilings and RSI 7.7 in the walls. The installation of a propane fuelled furnace was also included in the retrofit package. Prior to the renovations and retrofitting, the Guild Hall facility was almost unusable. The demonstration project transformed the cold, drafty buildings into an attractive, comfortable and functional centre for the performing arts. Heating requirements have been reduced to 500 MJ/m {sup 2} of floor space annually compared to a predicted 1,760 MJ/m{sup 2} of floor space based on HOTCAN analysis of the heating requirements without the energy conservation measures. 9 figs., 10 tabs.
Quantum critical Hall exponents
Lütken, C A
2014-01-01
We investigate a finite size "double scaling" hypothesis using data from an experiment on a quantum Hall system with short range disorder [1-3]. For Hall bars of width w at temperature T the scaling form is w(-mu)T(-kappa), where the critical exponent mu approximate to 0.23 we extract from the data is comparable to the multi-fractal exponent alpha(0) - 2 obtained from the Chalker-Coddington (CC) model [4]. We also use the data to find the approximate location (in the resistivity plane) of seven quantum critical points, all of which closely agree with the predictions derived long ago from the modular symmetry of a toroidal sigma-model with m matter fields [5]. The value nu(8) = 2.60513 ... of the localisation exponent obtained from the m = 8 model is in excellent agreement with the best available numerical value nu(num) = 2.607 +/- 0.004 derived from the CC-model [6]. Existing experimental data appear to favour the m = 9 model, suggesting that the quantum Hall system is not in the same universality class as th...
Restaurant volatility and the Iowa City, Iowa, smoke-free restaurant ordinance.
Sheffer, Megan A; Squier, Christopher A; Gilmore, Gary D
2013-01-01
To determine the economic impact of the Iowa City, Iowa, smoke-free restaurant ordinance (IC-SFRO) using an immediate and novel approach. In this retrospective study, food permit licensure served as the measure to assess the IC-SFRO impact. The Iowa City experience provided an excellent experimental setting, as the ordinance was enacted March 1, 2002, and repealed May 7, 2003, because of preemption. The city of Coralville served as a natural control, as it is contiguous to Iowa City, has similar population demographics, and has never enacted a smoke-free restaurant ordinance. Food permit licensure data for all Iowa City and Coralville restaurants were obtained from the Johnson County Health Department. Differences in restaurant volatility were assessed using Fisher's exact probability test. The number of restaurants increased in both Iowa City and Coralville throughout the ordinance period. The ratio of the total number of restaurants in Iowa City to the total number of restaurants in the Iowa City-Coralville metropolitan area remained stable. The proportion of restaurants for each city did not differ significantly during the preordinance, ordinance, and postordinance periods. The IC-SFRO did not adversely impact the restaurant industry in terms of restaurant closures. The Iowa legislature was urged to draft evidence-based legislation, such as amending preemption of the IC-SFRO, to protect and promote the health of its communities.
Topological Hall and Spin Hall Effects in Disordered Skyrmionic Textures
N'diaye, P. B.; Akosa, C. A.; Manchon, A.
2016-01-01
We carry out a throughout study of the topological Hall and topological spin Hall effects in disordered skyrmionic systems: the dimensionless (spin) Hall angles are evaluated across the energy band structure in the multiprobe Landauer-B\\"uttiker formalism and their link to the effective magnetic field emerging from the real space topology of the spin texture is highlighted. We discuss these results for an optimal skyrmion size and for various sizes of the sample and found that the adiabatic a...
76 FR 54521 - Iowa Disaster #IA-00036
2011-09-01
... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12754 and 12755] Iowa Disaster IA-00036 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major [[Page 54522
Iowa calibration of MEPDG performance prediction models.
2013-06-01
This study aims to improve the accuracy of AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) pavement : performance predictions for Iowa pavement systems through local calibration of MEPDG prediction models. A total of 130 : representative p...
Iowa's renewable energy and infrastructure impacts
2010-04-01
Objectives : Estimate traffic growth and pavement deterioration due to Iowas growing renewable energy industries in a multi-county area. : Develop a traffic and fiscal impact model to help assess the impact of additional biofuels plants on...
Quantum hall effect. A perspective
International Nuclear Information System (INIS)
Aoki, Hideo
2006-01-01
Novel concepts and phenomena are emerging recently in the physics of quantum Hall effect. This article gives an overview, which starts from the fractional quantum Hall system viewed as an extremely strongly correlated system, and move on to present various phenomena involving internal degrees of freedom (spin and layer), non-equilibrium and optical properties, and finally the spinoff to anomalous Hall effect and the rotating Bose-Einstein condensate. (author)
Szabo, James J.
2015-01-01
This Phase II project is developing a magnesium (Mg) Hall effect thruster system that would open the door for in situ resource utilization (ISRU)-based solar system exploration. Magnesium is light and easy to ionize. For a Mars- Earth transfer, the propellant mass savings with respect to a xenon Hall effect thruster (HET) system are enormous. Magnesium also can be combusted in a rocket with carbon dioxide (CO2) or water (H2O), enabling a multimode propulsion system with propellant sharing and ISRU. In the near term, CO2 and H2O would be collected in situ on Mars or the moon. In the far term, Mg itself would be collected from Martian and lunar regolith. In Phase I, an integrated, medium-power (1- to 3-kW) Mg HET system was developed and tested. Controlled, steady operation at constant voltage and power was demonstrated. Preliminary measurements indicate a specific impulse (Isp) greater than 4,000 s was achieved at a discharge potential of 400 V. The feasibility of delivering fluidized Mg powder to a medium- or high-power thruster also was demonstrated. Phase II of the project evaluated the performance of an integrated, highpower Mg Hall thruster system in a relevant space environment. Researchers improved the medium power thruster system and characterized it in detail. Researchers also designed and built a high-power (8- to 20-kW) Mg HET. A fluidized powder feed system supporting the high-power thruster was built and delivered to Busek Company, Inc.
Czech Academy of Sciences Publication Activity Database
Wunderlich, Joerg; Park, B.G.; Irvine, A.C.; Zarbo, Liviu; Rozkotová, E.; Němec, P.; Novák, Vít; Sinova, Jairo; Jungwirth, Tomáš
2010-01-01
Roč. 330, č. 6012 (2010), s. 1801-1804 ISSN 0036-8075 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510 EU Projects: European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 31.364, year: 2010
Hall magnetohydrodynamics: Conservation laws and Lyapunov stability
International Nuclear Information System (INIS)
Holm, D.D.
1987-01-01
Hall electric fields produce circulating mass flow in confined ideal-fluid plasmas. The conservation laws, Hamiltonian structure, equilibrium state relations, and Lyapunov stability conditions are presented here for ideal Hall magnetohydrodynamics (HMHD) in two and three dimensions. The approach here is to use the remarkable array of nonlinear conservation laws for HMHD that follow from its Hamiltonian structure in order to construct explicit Lyapunov functionals for the HMHD equilibrium states. In this way, the Lyapunov stability analysis provides classes of HMHD equilibria that are stable and whose linearized initial-value problems are well posed (in the sense of possessing continuous dependence on initial conditions). Several examples are discussed in both two and three dimensions
Coulomb blockade in hierarchical quantum Hall droplets
International Nuclear Information System (INIS)
Cappelli, Andrea; Georgiev, Lachezar S; Zemba, Guillermo R
2009-01-01
The degeneracy of energy levels in a quantum dot of Hall fluid, leading to conductance peaks, can be readily derived from the partition functions of conformal field theory. Their complete expressions can be found for Hall states with both Abelian and non-Abelian statistics, upon adapting known results for the annulus geometry. We analyze the Abelian states with hierarchical filling fractions, ν = m/(mp ± 1), and find a non-trivial pattern of conductance peaks. In particular, each one of them occurs with a characteristic multiplicity, which is due to the extended symmetry of the m-folded edge. Experimental tests of the multiplicity can shed more light on the dynamics of this composite edge. (fast track communication)
Energy consumption of sport halls
Energy Technology Data Exchange (ETDEWEB)
1983-01-01
The energy consumption of Finland's sports halls (ball games halls, ice hockey halls and swimming halls) represent approximately 1% of that of the country's whole building stock. In the light of the facts revealed by the energy study the potential energy saving rate in sports halls is 15-25%. The total savings would be something like FIM 30-40 million per annum, of which about a half would be achieved without energy-economic investments only by changing utilization habits and by automatic control measures. The energy-economic investments are for the most part connected with ventilation and their repayment period is from one to five years. On the basis of the energy study the following specific consumption are presented as target values: swimming halls: heat (kWh/m*H3/a)100, electricity (kWh/m*H3/a)35, water (l/m*H3/a)1000 icehockey halls (warm): heat (kWh/m*H3/a)25, electricity (kWh/m*H3/a)15, water (l/m*H3/a)200, ball games halls (multi-purpose halls): heat (kWh/m*H3/a)30, electricity (kWh/m*H3/a)25, water (l/m*H3/a)130. In the study the following points proved to be the central areas of energy saving in sports halls: 1. Flexible regulation of the temperature in sports spaces on the basis of the sport in question. 2. The ventilation of swimming halls should be adjusted in such a way that the humidity of the hall air would comply with the limit humidity curve determined by the quality of structures and the temperature of the outdoor air. 3. An ice skating hall is an establishment producing condensing energy from 8 to 9 months a year worth of approx. 100.000-150.000 Finnmarks. The development of the recovery of condensing energy has become more important. 4. The ventilation of ball games halls may account for over 50% of the energy consumption of the whole building. Therefore special attention should be paid to the optimatization of ventilation as a whole.
Scanning vector Hall probe microscopy
International Nuclear Information System (INIS)
Cambel, V.; Gregusova, D.; Fedor, J.; Kudela, R.; Bending, S.J.
2004-01-01
We have developed a scanning vector Hall probe microscope for mapping magnetic field vector over magnetic samples. The microscope is based on a micromachined Hall sensor and the cryostat with scanning system. The vector Hall sensor active area is ∼5x5 μm 2 . It is realized by patterning three Hall probes on the tilted faces of GaAs pyramids. Data from these 'tilted' Hall probes are used to reconstruct the full magnetic field vector. The scanning area of the microscope is 5x5 mm 2 , space resolution 2.5 μm, field resolution ∼1 μT Hz -1/2 at temperatures 10-300 K
Hall effect in the two-dimensional Luttinger liquid
International Nuclear Information System (INIS)
Anderson, P.W.
1991-01-01
The temperature dependence of the Hall effect in the normal state is a commom theme of all the cuprate superconductors and has been one of the more puzzling observations on these puzzling materials. We describe a general scheme within the Luttinger liquid theory of these two-dimensional quantum fluids which corrrelates the anomalous Hall and resistivity observations on a wide variety of both pure and doped single crystals, especially the data in the accompanying Letter of Chien, Wang, and Ong
Thermoelectric and Hall-effect studies in hydrogenerated nickel foils
International Nuclear Information System (INIS)
Rani, R.; Nigam, A.N.
1978-01-01
Thermo e.m.f. and Hall constant of hydrogenerated nickel foils have been measured. Termo e.m.f. shows a sign reversal which is not due to the change in sign of the charge carriers, as indicated by the Hall-effect measurements. To account for the sign reversal of thermo e.m.f., it is found necessary to take into account the surface states of chemisorbed hydrogen on nickel
Low-Cost, High-Performance Hall Thruster Support System
Hesterman, Bryce
2015-01-01
Colorado Power Electronics (CPE) has built an innovative modular PPU for Hall thrusters, including discharge, magnet, heater and keeper supplies, and an interface module. This high-performance PPU offers resonant circuit topologies, magnetics design, modularity, and a stable and sustained operation during severe Hall effect thruster current oscillations. Laboratory testing has demonstrated discharge module efficiency of 96 percent, which is considerably higher than current state of the art.
Routine environmental audit of Ames Laboratory, Ames, Iowa
International Nuclear Information System (INIS)
1994-09-01
This document contains the findings identified during the routine environmental audit of Ames Laboratory, Ames, Iowa, conducted September 12--23, 1994. The audit included a review of all Ames Laboratory operations and facilities supporting DOE-sponsored activities. The audit's objective is to advise the Secretary of Energy, through the Assistant Secretary for Environment, Safety and Health, as to the adequacy of the environmental protection programs established at Ames Laboratory to ensure the protection of the environment, and compliance with Federal, state, and DOE requirements
International Nuclear Information System (INIS)
Shen, M.C.; Ebel, D.
1987-01-01
In this paper some new results concerning magnetohydrodynamic (MHD) equations with the Hall current (HC) term in the Ohm's law are presented. For the cylindrical pinch of a compressible HC fluid, it is found that for large time and long wave length the solution to the governing equations exhibits the behavior of solitons as in the case of an ideal MHD model. In some special cases, the HC model appears to be better posed. An open question is whether a simple toroidal equilibrium of an HC fluid with resistivity and viscosity exists. The answer to this question is affirmative if the prescribed velocity on the boundary has a small norm. Furthermore, the equilibrium is also linearly and nonlinearly stable
Cassidy, David C.
2013-03-01
It's July 1945. Germany is in defeat and the atomic bombs are on their way to Japan. Under the direction of Samuel Goudsmit, the Allies are holding some of the top German nuclear scientists-among them Heisenberg, Hahn, and Gerlach-captive in Farm Hall, an English country manor near Cambridge, England. As secret microphones record their conversations, the scientists are unaware of why they are being held or for how long. Thinking themselves far ahead of the Allies, how will they react to the news of the atomic bombs? How will these famous scientists explain to themselves and to the world their failure to achieve even a chain reaction? How will they come to terms with the horror of the Third Reich, their work for such a regime, and their behavior during that period? This one-act play is based upon the transcripts of their conversations as well as the author's historical work on the subject.
76 FR 19187 - City of Davenport, Iowa-Construction and Operation Exemption-in Scott County, Iowa
2011-04-06
... the Eastern Iowa Industrial Center, an industrial park, with rail access. The City will hire an... design and in the rail alignment, OEA, the FHWA, the Iowa Department of Transportation, and the City...
Iowa City Reads! The Reading Event Worth Shouting About.
Donham van Deusen, Jean; Langhorne, Mary Jo
1997-01-01
Describes the Community Reading Month (CRM) initiative in Iowa City, Iowa; its goals are to promote the value of reading and to build a sense of community. Topics include the development of CRM, increased reading scores of Iowa City's elementary school students, activities for people of all ages, and planning and evaluation. (AEF)
Energy Technology Data Exchange (ETDEWEB)
Brower, M.C. [Brower & Company, Andover, MA (United States); Factor, T. [Iowa Wind Energy Institute, Fairfield, IA (United States)
1997-12-31
The Iowa Wind Energy Institute, under a grant from the Iowa Energy Center, undertook in 1994 to map wind resources in Iowa. Fifty-meter met towers were erected at 13 locations across the state deemed promising for utility-scale wind farm development. Two years of summarized wind speed, direction, and temperature data were used to create wind resource maps incorporating effects of elevation, relative exposure, terrain roughness, and ground cover. Maps were produced predicting long-term mean monthly and annual wind speeds on a one-kilometer grid. The estimated absolute standard error in the predicted annual average wind speeds at unobstructed locations is 9 percent. The relative standard error between points on the annual map is estimated to be 3 percent. These maps and tabular data for 2,000 cities and towns in Iowa are now available on the Iowa Energy Center`s web site (http.//www.energy.iastate.edu).
Hall Effect Gyrators and Circulators
Viola, Giovanni; DiVincenzo, David P.
2014-04-01
The electronic circulator and its close relative the gyrator are invaluable tools for noise management and signal routing in the current generation of low-temperature microwave systems for the implementation of new quantum technologies. The current implementation of these devices using the Faraday effect is satisfactory but requires a bulky structure whose physical dimension is close to the microwave wavelength employed. The Hall effect is an alternative nonreciprocal effect that can also be used to produce desired device functionality. We review earlier efforts to use an Ohmically contacted four-terminal Hall bar, explaining why this approach leads to unacceptably high device loss. We find that capacitive coupling to such a Hall conductor has much greater promise for achieving good circulator and gyrator functionality. We formulate a classical Ohm-Hall analysis for calculating the properties of such a device, and show how this classical theory simplifies remarkably in the limiting case of the Hall angle approaching 90°. In this limit, we find that either a four-terminal or a three-terminal capacitive device can give excellent circulator behavior, with device dimensions far smaller than the ac wavelength. An experiment is proposed to achieve GHz-band gyration in millimeter (and smaller) scale structures employing either semiconductor heterostructure or graphene Hall conductors. An inductively coupled scheme for realizing a Hall gyrator is also analyzed.
Topological Hall and spin Hall effects in disordered skyrmionic textures
Ndiaye, Papa Birame; Akosa, Collins Ashu; Manchon, Aurelien
2017-01-01
We carry out a thorough study of the topological Hall and topological spin Hall effects in disordered skyrmionic systems: the dimensionless (spin) Hall angles are evaluated across the energy-band structure in the multiprobe Landauer-Büttiker formalism and their link to the effective magnetic field emerging from the real-space topology of the spin texture is highlighted. We discuss these results for an optimal skyrmion size and for various sizes of the sample and find that the adiabatic approximation still holds for large skyrmions as well as for nanoskyrmions. Finally, we test the robustness of the topological signals against disorder strength and show that the topological Hall effect is highly sensitive to momentum scattering.
Topological Hall and spin Hall effects in disordered skyrmionic textures
Ndiaye, Papa Birame
2017-02-24
We carry out a thorough study of the topological Hall and topological spin Hall effects in disordered skyrmionic systems: the dimensionless (spin) Hall angles are evaluated across the energy-band structure in the multiprobe Landauer-Büttiker formalism and their link to the effective magnetic field emerging from the real-space topology of the spin texture is highlighted. We discuss these results for an optimal skyrmion size and for various sizes of the sample and find that the adiabatic approximation still holds for large skyrmions as well as for nanoskyrmions. Finally, we test the robustness of the topological signals against disorder strength and show that the topological Hall effect is highly sensitive to momentum scattering.
Tuning giant anomalous Hall resistance ratio in perpendicular Hall balance
Energy Technology Data Exchange (ETDEWEB)
Zhang, J. Y.; Yang, G. [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, S. G., E-mail: sgwang@iphy.ac.cn, E-mail: ghyu@mater.ustb.edu.cn [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, J. L. [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Wang, R. M. [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Amsellem, E.; Kohn, A. [Department of Materials Engineering, Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Yu, G. H., E-mail: sgwang@iphy.ac.cn, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)
2015-04-13
Anomalous Hall effect at room temperature in perpendicular Hall balance with a core structure of [Pt/Co]{sub 4}/NiO/[Co/Pt]{sub 4} has been tuned by functional CoO layers, where [Pt/Co]{sub 4} multilayers exhibit perpendicular magnetic anisotropy. A giant Hall resistance ratio up to 69 900% and saturation Hall resistance (R{sub S}{sup P}) up to 2590 mΩ were obtained in CoO/[Pt/Co]{sub 4}/NiO/[Co/Pt]{sub 4}/CoO system, which is 302% and 146% larger than that in the structure without CoO layers, respectively. Transmission electron microscopy shows highly textured [Co/Pt]{sub 4} multilayers and oxide layers with local epitaxial relations, indicating that the crystallographic structure has significant influence on spin dependent transport properties.
Josephson tunneling in bilayer quantum Hall system
International Nuclear Information System (INIS)
Ezawa, Z.F.; Tsitsishvili, G.; Sawada, A.
2012-01-01
A Bose–Einstein condensation is formed by composite bosons in the quantum Hall state. A composite boson carries the fundamental charge (−e). We investigate Josephson tunneling of such charges in the bilayer quantum Hall system at the total filling ν=1. We show the existence of the critical current for the tunneling current to be coherent and dissipationless. Our results explain recent experiments due to [L. Tiemann, Y. Yoon, W. Dietsche, K. von Klitzing, W. Wegscheider, Phys. Rev. B 80 (2009) 165120] and due to [Y. Yoon, L. Tiemann, S. Schmult, W. Dietsche, K. von Klitzing, Phys. Rev. Lett. 104 (2010) 116802]. We predict also how the critical current changes as the sample is tilted in the magnetic field. -- Highlights: ► Composite bosons undergo Bose–Einstein condensation to form the bilayer quantum Hall state. ► A composite boson is a single electron bound to a flux quantum and carries one unit charge. ► Quantum coherence develops due to the condensation. ► Quantum coherence drives the supercurrent in each layer and the tunneling current. ► There exists the critical input current so that the tunneling current is coherent and dissipationless.
Infinite symmetry in the quantum Hall effect
Directory of Open Access Journals (Sweden)
Lütken C.A.
2014-04-01
Full Text Available The new states of matter and concomitant quantum critical phenomena revealed by the quantum Hall effect appear to be accompanied by an emergent modular symmetry. The extreme rigidity of this infinite symmetry makes it easy to falsify, but two decades of experiments have failed to do so, and the location of quantum critical points predicted by the symmetry is in increasingly accurate agreement with scaling experiments. The symmetry severely constrains the structure of the effective quantum field theory that encodes the low energy limit of quantum electrodynamics of 1010 charges in two dirty dimensions. If this is a non-linear σ-model the target space is a torus, rather than the more familiar sphere. One of the simplest toroidal models gives a critical (correlation length exponent that agrees with the value obtained from numerical simulations of the quantum Hall effect.
Theory of fractional quantum hall effect
International Nuclear Information System (INIS)
Kostadinov, I.Z.
1985-08-01
A theory of the Fractional Quantum Hall Effect is constructed based on magnetic flux fractionization, which lead to instability of the system against selfcompression. A theorem is proved stating that arbitrary potentials fail to lift a specific degeneracy of the Landau level. For the case of 1/3 fractional filling a model 3-particles interaction is constructed breaking the symmetry. The rigid 3-particles wave function plays the role of order parameter. In a BCS type of theory the gap in the single particles spectrum is produced by the 3-particles interaction. The mean field critical behaviour and critical parameters are determined as well as the Ginsburg-Landau equation coefficients. The Hall conductivity is calculated from the first principles and its temperature dependence is found. The simultaneous tunnelling of 3,5,7 etc. electrons and quantum interference effects are predicted. (author)
Complex dynamics of the integer quantum Hall effect
International Nuclear Information System (INIS)
Trugman, S.A.; Nicopoulos, V.N.; Florida Univ., Gainesville, FL
1991-01-01
We investigate both classical and quantum potential scattering in two dimensions in a magnetic field, with applications to the integer quantum Hall effect. Classical scattering is complex, due in one case to the approach of scattering states to an infinite number of bound states. We show that bound states are generic, and occur for all but extremely smooth scattering potentials (|rvec ∇| → 0). Quantum scattering follows the classical behavior rather closely, exhibiting sharp resonances rather than classical bound states. Extended scatterers provide an explanation for the breakdown of the QHE at a comparatively small Hall voltage. 16 refs., 14 figs
Leeds, Daniel M.; DesJardins, Stephen L.
2015-01-01
The cost of attending college has risen steadily over the past 30 years, making financial aid an important determinant of college choice for many students and a subject of concern for colleges and state governments. In this paper, we estimate the effect of rule-based merit aid assignment on students' enrollment decisions at the University of Iowa.…
Diagnostics Systems for Permanent Hall Thrusters Development
Ferreira, Jose Leonardo; Soares Ferreira, Ivan; Santos, Jean; Miranda, Rodrigo; Possa, M. Gabriela
-Effect Thruster (PMHET), developed at the Plasma Physics Laboratory of UnB. The idea of using an array of permanent magnets, instead of an electromagnet, to produce a radial magnetic field inside the cylindrical plasma drift channel of the thruster is very attractive, especially because of the possibility of developing a HET with power consumption low enough to be used in small satellites or medium-size satellites with low on board power. Hall-Effect Thrusters are now a very good option for spacecraft primary propulsion and also for station-keeping of medium and large satellites. This is because of their high specific impulse, efficient use of propellant mass and combined low and precise thrust capabilities, which are related to an economy in terms of propellant mass utilization , longer satellite lifetime and easier spacecraft maneuvering in microgravity environment. The first HETs were developed in the mid 1950’s, and they were first called Closed Drift Thrusters. Today, the successful use of electric thrusters for attitude control and orbit modification on hundreds of satellites shows the advanced stage of development of this technology. In addition to this, after the success of space missions such as Deep Space One and Dawn (NASA), Hayabusa (JAXA) and Smart-1 (ESA), the employment of electric thrusters is also consolidated for the primary propulsion of spacecraft. This success is mainly due to three factors: reliability of this technology; efficiency of propellant utilization, and therefore reduction of the initial mass of the ship; possibility of operation over long time intervals, with practically unlimited cycling and restarts. This thrusting system is designed to be used in satellite attitude control and long term space missions. One of the greatest advantage of this kind of thruster is the production of a steady state magnetic field by permanent magnets providing electron trapping and Hall current generation within a significant decrease on the electric energy supply
Nagaosa, Naoto; Sinova, Jairo; Onoda, Shigeki; MacDonald, A. H.; Ong, N. P.
2010-04-01
The anomalous Hall effect (AHE) occurs in solids with broken time-reversal symmetry, typically in a ferromagnetic phase, as a consequence of spin-orbit coupling. Experimental and theoretical studies of the AHE are reviewed, focusing on recent developments that have provided a more complete framework for understanding this subtle phenomenon and have, in many instances, replaced controversy by clarity. Synergy between experimental and theoretical works, both playing a crucial role, has been at the heart of these advances. On the theoretical front, the adoption of the Berry-phase concepts has established a link between the AHE and the topological nature of the Hall currents. On the experimental front, new experimental studies of the AHE in transition metals, transition-metal oxides, spinels, pyrochlores, and metallic dilute magnetic semiconductors have established systematic trends. These two developments, in concert with first-principles electronic structure calculations, strongly favor the dominance of an intrinsic Berry-phase-related AHE mechanism in metallic ferromagnets with moderate conductivity. The intrinsic AHE can be expressed in terms of the Berry-phase curvatures and it is therefore an intrinsic quantum-mechanical property of a perfect crystal. An extrinsic mechanism, skew scattering from disorder, tends to dominate the AHE in highly conductive ferromagnets. The full modern semiclassical treatment of the AHE is reviewed which incorporates an anomalous contribution to wave-packet group velocity due to momentum-space Berry curvatures and correctly combines the roles of intrinsic and extrinsic (skew-scattering and side-jump) scattering-related mechanisms. In addition, more rigorous quantum-mechanical treatments based on the Kubo and Keldysh formalisms are reviewed, taking into account multiband effects, and demonstrate the equivalence of all three linear response theories in the metallic regime. Building on results from recent experiment and theory, a
Planar Hall effect bridge magnetic field sensors
DEFF Research Database (Denmark)
Henriksen, A.D.; Dalslet, Bjarke Thomas; Skieller, D.H.
2010-01-01
Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can...... Hall effect bridge sensors....
Maximilien Brice; SM18
2009-01-01
William Brinkman (centre), Director of the Department of Energy, U.S.A. at the superconducting magnet test hall SM18 with (from left to right) Coordinator for External Relations F. Pauss, Advisor for Non-Member States J. Ellis, J. Strait from Fermilab and Deputy Head of Technology Department L. Rossi on 13 November 2009.
Maximilien Brice
2011-01-01
8 April 2011 - Brazilian Minister of State for Science and Technology A. Mercadante Oliva signing the guest book with CERN Director-General R. Heuer and Head of International Relations F. Pauss; in the ATLAS visitor centre with Collaboration Former Spokesperson P. Jenni; visiting LHC superconducting magnet test hall with J.M. Jimenez.
Benoît Jeannet
2011-01-01
Austrian state secretary for foreign affairs, Wolfgang Waldner, left, was welcomed to CERN by Felicitas Pauss, head of international relations at CERN, on 19 September. While at CERN, he toured the CMS control room and underground experimental service cavern, the LHC superconducting magnet test hall, and the Universe of Particles exhibition in the Globe of Science and Innovation.
"Hall mees" Linnateatris / Triin Sinissaar
Sinissaar, Triin
1999-01-01
Tallinn Linnateatri ja Raadioteatri ühislavastus "Hall mees" Gill Adamsi näidendi järgi, lavastaja Eero Spriit, osades Helene Vannari ja Väino Laes, kunstnik Kustav - Agu Püüman. Esietendus 22. okt
Directory of Open Access Journals (Sweden)
Bamshad Michael J
2009-03-01
Full Text Available Abstract Sheldon-Hall syndrome (SHS is a rare multiple congenital contracture syndrome characterized by contractures of the distal joints of the limbs, triangular face, downslanting palpebral fissures, small mouth, and high arched palate. Epidemiological data for the prevalence of SHS are not available, but less than 100 cases have been reported in the literature. Other common clinical features of SHS include prominent nasolabial folds, high arched palate, attached earlobes, mild cervical webbing, short stature, severe camptodactyly, ulnar deviation, and vertical talus and/or talipes equinovarus. Typically, the contractures are most severe at birth and non-progressive. SHS is inherited in an autosomal dominant pattern but about half the cases are sporadic. Mutations in either MYH3, TNNI2, or TNNT3 have been found in about 50% of cases. These genes encode proteins of the contractile apparatus of fast twitch skeletal muscle fibers. The diagnosis of SHS is based on clinical criteria. Mutation analysis is useful to distinguish SHS from arthrogryposis syndromes with similar features (e.g. distal arthrogryposis 1 and Freeman-Sheldon syndrome. Prenatal diagnosis by ultrasonography is feasible at 18–24 weeks of gestation. If the family history is positive and the mutation is known in the family, prenatal molecular genetic diagnosis is possible. There is no specific therapy for SHS. However, patients benefit from early intervention with occupational and physical therapy, serial casting, and/or surgery. Life expectancy and cognitive abilities are normal.
Chudnovsky, Eugene M.
2007-01-01
An extension of Drude model is proposed that accounts for spin and spin-orbit interaction of charge carriers. Spin currents appear due to combined action of the external electric field, crystal field and scattering of charge carriers. The expression for spin Hall conductivity is derived for metals and semiconductors that is independent of the scattering mechanism. In cubic metals, spin Hall conductivity $\\sigma_s$ and charge conductivity $\\sigma_c$ are related through $\\sigma_s = [2 \\pi \\hbar...
Reasons for Moving in Nonmetro Iowa
Burke, Sandra Charvat; Edelman, Mark
2007-01-01
This study highlights the experiences of people who have recently moved to or from 19 selected nonmetropolitan counties of Iowa. This report highlights work, family, community, and housing reasons for moving. The purpose is to increase understanding about why people move so community leaders and citizens can develop actionable strategies for attracting and retaining population.
TILE at Iowa: Adoption and Adaptation
Florman, Jean C.
2014-01-01
This chapter introduces a University of Iowa effort to enhance and support active learning pedagogies in technology-enhanced (TILE) classrooms and three elements that proved essential to the campus-wide adoption of those pedagogies. It then describes the impact of those professional development efforts on the curricula and cultures of three…
Iowa Family Day Care Handbook. Second Edition.
Pinsky, Dorothy; And Others
The Iowa Family Day Care Handbook is designed as an aid for persons entering the business of providing home day care as well as for those persons already in the field. Topics include advantages and disadvantages of family day care for children, parents and providers; getting started in family day care; and a list and description of records that…
76 FR 64043 - Iowa Regulatory Program
2011-10-17
...) Requirements for permits for special categories of mining. 27--40.41(207) Permanent regulatory program--small... DEPARTMENT OF THE INTERIOR Office of Surface Mining Reclamation and Enforcement 30 CFR Part 915 [Docket No. IA-016-FOR; Docket ID: OSM-2011-0014] Iowa Regulatory Program AGENCY: Office of Surface Mining...
Iowa Case Management for Rural Drug Abuse
Hall, James A.; Vaughan Sarrazin, Mary S.; Huber, Diane L.; Vaughn, Thomas; Block, Robert I.; Reedy, Amanda R.; Jang, MiJin
2009-01-01
Objective: The purpose of this research was to evaluate the effectiveness of a comprehensive, strengths-based model of case management for clients in drug abuse treatment. Method: 503 volunteers from residential or intensive outpatient treatment were randomly assigned to one of three conditions of Iowa Case Management (ICM) plus treatment as usual…
Not your grandfather's concert hall
Cooper, Russell; Malenka, Richard; Griffith, Charles; Friedlander, Steven
2004-05-01
The opening of Judy and Arthur Zankel Hall on 12 September 2003, restores Andrew Carnegie's original 1891 concept of having three outstanding auditoriums of different sizes under one roof, and creates a 21st-century venue for music performance and education. With concerts ranging from early music to avant-garde multimedia productions, from jazz to world music, and from solo recitals to chamber music, Zankel Hall expands the breadth and depth of Carnegie Hall's offerings. It allows for the integration of programming across three halls with minifestivals tailored both to the size and strengths of each hall and to the artists and music to be performed. The new flexible space also provides Carnegie Hall with an education center equipped with advanced communications technology. This paper discusses the unique program planned for this facility and how the architects, theatre consultants, and acousticians developed a design that fulfilled the client's expectations and coordinated the construction of the facility under the floor of the main Isaac Stern Auditorium without having to cancel a single performance.
The National Academies of Sciences, Engineering and Medicine is seeking community input for a study on the future of materials research (MR). Frontiers of Materials Research: A Decadal Survey will look at defining the frontiers of materials research ranging from traditional materials science and engineering to condensed matter physics. Please join members of the study committee for a town hall to discuss future directions for materials research in the United States in the context of worldwide efforts. In particular, input on the following topics will be of great value: progress, achievements, and principal changes in the R&D landscape over the past decade; identification of key MR areas that have major scientific gaps or offer promising investment opportunities from 2020-2030; and the challenges that MR may face over the next decade and how those challenges might be addressed. This study was requested by the Department of Energy and the National Science Foundation. The National Academies will issue a report in 2018 that will offer guidance to federal agencies that support materials research, science policymakers, and researchers in materials research and other adjoining fields. Learn more about the study at http://nas.edu/materials.
Complex scattering dynamics and the quantum Hall effects
International Nuclear Information System (INIS)
Trugman, S.A.
1994-01-01
We review both classical and quantum potential scattering in two dimensions in a magnetic field, with applications to the quantum Hall effect. Classical scattering is complex, due to the approach of scattering states to an infinite number of dynamically bound states. Quantum scattering follows the classical behavior rather closely, exhibiting sharp resonances in place of the classical bound states. Extended scatterers provide a quantitative explanation for the breakdown of the QHE at a comparatively small Hall voltage as seen by Kawaji et al., and possibly for noise effects
The 3D Elevation Program: summary for Iowa
Carswell, William J.
2015-01-01
Elevation data are essential to a broad range of applications, including forest resources management, wildlife and habitat management, national security, recreation, and many others. For the State of Iowa, elevation data are critical for agriculture and precision farming, infrastructure and construction management, natural resources conservation, flood risk management, water supply and quality, and other business uses. Today, high-density light detection and ranging (lidar) data are the primary sources for deriving elevation models and other datasets. Federal, State, Tribal, and local agencies work in partnership to (1) replace data that are older and of lower quality and (2) provide coverage where publicly accessible data do not exist. A joint goal of State and Federal partners is to acquire consistent, statewide coverage to support existing and emerging applications enabled by lidar data.
The quantum Hall's effect: A quantum electrodynamic phenomenon
International Nuclear Information System (INIS)
Arbab, A. I.
2012-01-01
We have applied Maxwell's equations to study the physics of quantum Hall's effect. The electromagnetic properties of this system are obtained. The Hall's voltage, V H = 2πħ 2 n s /em, where n s is the electron number density, for a 2-dimensional system, and h = 2πħ is the Planck's constant, is found to coincide with the voltage drop across the quantum capacitor. Consideration of the cyclotronic motion of electrons is found to give rise to Hall's resistance. Ohmic resistances in the horizontal and vertical directions have been found to exist before equilibrium state is reached. At a fundamental level, the Hall's effect is found to be equivalent to a resonant LCR circuit with L H = 2π m/e 2 n s and C H = me 2 /2πħ 2 n s satisfying the resonance condition with resonant frequency equal to the inverse of the scattering (relaxation) time, τ s . The Hall's resistance is found to be R H = √L H /C H . The Hall's resistance may be connected with the impedance that the electron wave experiences when it propagates in the 2-dimensional gas. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Signatures of lattice geometry in quantum and topological Hall effect
International Nuclear Information System (INIS)
Göbel, Börge; Mook, Alexander; Mertig, Ingrid; Henk, Jürgen
2017-01-01
The topological Hall effect (THE) of electrons in skyrmion crystals (SkXs) is strongly related to the quantum Hall effect (QHE) on lattices. This relation suggests to revisit the QHE because its Hall conductivity can be unconventionally quantized. It exhibits a jump and changes sign abruptly if the Fermi level crosses a van Hove singularity. In this Paper, we investigate the unconventional QHE features by discussing band structures, Hall conductivities, and topological edge states for square and triangular lattices; their origin are Chern numbers of bands in the SkX (THE) or of the corresponding Landau levels (QHE). Striking features in the energy dependence of the Hall conductivities are traced back to the band structure without magnetic field whose properties are dictated by the lattice geometry. Based on these findings, we derive an approximation that allows us to determine the energy dependence of the topological Hall conductivity on any two-dimensional lattice. The validity of this approximation is proven for the honeycomb lattice. We conclude that SkXs lend themselves for experiments to validate our findings for the THE and—indirectly—the QHE. (paper)
Tunnelling anomalous and planar Hall effects (Conference Presentation)
Matos-Abiague, Alex; Scharf, Benedikt; Han, Jong E.; Hankiewicz, Ewelina M.; Zutic, Igor
2016-10-01
We theoretically show how the interplay between spin-orbit coupling (SOC) and magnetism can result in a finite tunneling Hall conductance, transverse to the applied bias. For two-dimensional tunnel junctions with a ferromagnetic lead and magnetization perpendicular to the current flow, the detected anomalous Hall voltage can be used to extract information not only about the spin polarization but also about the strength of the interfacial SOC. In contrast, a tunneling current across a ferromagnetic barrier on the surface of a three-dimensional topological insulator (TI) can induce a planar Hall response even when the magnetization is oriented along the current flow[1]. The tunneling nature of the states contributing to the planar Hall conductance can be switched from the ordinary to the Klein regimes by the electrostatic control of the barrier strength. This allows for an enhancement of the transverse response and a giant Hall angle, with the tunneling planar Hall conductance exceeding the longitudinal component. Despite the simplicity of a single ferromagnetic region, the TI/ferromagnet system exhibits a variety of functionalities. In addition to a spin-valve operation for magnetic sensing and storing information, positive, negative, and negative differential conductances can be tuned by properly adjusting the barrier potential and/or varying the magnetization direction. Such different resistive behaviors in the same system are attractive for potential applications in reconfigurable spintronic devices. [1] B. Scharf, A. Matos-Abiague, J. E. Han, E. M. Hankiewicz, and I. Zutic, arXiv:1601.01009 (2016).
A holographic model for the fractional quantum Hall effect
Energy Technology Data Exchange (ETDEWEB)
Lippert, Matthew [Institute for Theoretical Physics, University of Amsterdam,Science Park 904, 1090GL Amsterdam (Netherlands); Meyer, René [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo,Kashiwa, Chiba 277-8568 (Japan); Taliotis, Anastasios [Theoretische Natuurkunde, Vrije Universiteit Brussel andThe International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)
2015-01-08
Experimental data for fractional quantum Hall systems can to a large extent be explained by assuming the existence of a Γ{sub 0}(2) modular symmetry group commuting with the renormalization group flow and hence mapping different phases of two-dimensional electron gases into each other. Based on this insight, we construct a phenomenological holographic model which captures many features of the fractional quantum Hall effect. Using an SL(2,ℤ)-invariant Einstein-Maxwell-axio-dilaton theory capturing the important modular transformation properties of quantum Hall physics, we find dyonic diatonic black hole solutions which are gapped and have a Hall conductivity equal to the filling fraction, as expected for quantum Hall states. We also provide several technical results on the general behavior of the gauge field fluctuations around these dyonic dilatonic black hole solutions: we specify a sufficient criterion for IR normalizability of the fluctuations, demonstrate the preservation of the gap under the SL(2,ℤ) action, and prove that the singularity of the fluctuation problem in the presence of a magnetic field is an accessory singularity. We finish with a preliminary investigation of the possible IR scaling solutions of our model and some speculations on how they could be important for the observed universality of quantum Hall transitions.
A holographic model for the fractional quantum Hall effect
Lippert, Matthew; Meyer, René; Taliotis, Anastasios
2015-01-01
Experimental data for fractional quantum Hall systems can to a large extent be explained by assuming the existence of a Γ0(2) modular symmetry group commuting with the renormalization group flow and hence mapping different phases of two-dimensional electron gases into each other. Based on this insight, we construct a phenomenological holographic model which captures many features of the fractional quantum Hall effect. Using an -invariant Einstein-Maxwell-axio-dilaton theory capturing the important modular transformation properties of quantum Hall physics, we find dyonic diatonic black hole solutions which are gapped and have a Hall conductivity equal to the filling fraction, as expected for quantum Hall states. We also provide several technical results on the general behavior of the gauge field fluctuations around these dyonic dilatonic black hole solutions: we specify a sufficient criterion for IR normalizability of the fluctuations, demonstrate the preservation of the gap under the action, and prove that the singularity of the fluctuation problem in the presence of a magnetic field is an accessory singularity. We finish with a preliminary investigation of the possible IR scaling solutions of our model and some speculations on how they could be important for the observed universality of quantum Hall transitions.
Szabo, James
2015-01-01
Iodine enables dramatic mass and cost savings for lunar and Mars cargo missions, including Earth escape and near-Earth space maneuvers. The demonstrated throttling ability of iodine is important for a singular thruster that might be called upon to propel a spacecraft from Earth to Mars or Venus. The ability to throttle efficiently is even more important for missions beyond Mars. In the Phase I project, Busek Company, Inc., tested an existing Hall thruster, the BHT-8000, on iodine propellant. The thruster was fed by a high-flow iodine feed system and supported by an existing Busek hollow cathode flowing xenon gas. The Phase I propellant feed system was evolved from a previously demonstrated laboratory feed system. Throttling of the thruster between 2 and 11 kW at 200 to 600 V was demonstrated. Testing showed that the efficiency of iodine fueled BHT-8000 is the same as with xenon, with iodine delivering a slightly higher thrust-to-power (T/P) ratio. In Phase II, a complete iodine-fueled system was developed, including the thruster, hollow cathode, and iodine propellant feed system. The nominal power of the Phase II system is 8 kW; however, it can be deeply throttled as well as clustered to much higher power levels. The technology also can be scaled to greater than 100 kW per thruster to support megawatt-class missions. The target thruster efficiency for the full-scale system is 65 percent at high specific impulse (Isp) (approximately 3,000 s) and 60 percent at high thrust (Isp approximately 2,000 s).
Dexter, Franklin; Jarvie, Craig; Epstein, Richard H
2018-02-01
Three observational studies at large teaching hospitals found that reducing turnover times resulted in the surgeons performing more cases. We sought to determine if these findings are generalizable to other hospitals, because, if so, reducing turnover times may be an important mechanism for hospitals to use for growing caseloads. Observational cohort study. 116 hospitals in Iowa with inpatient or outpatient surgery from July 1, 2013 through June 30, 2015. Surgeons in Iowa, each with a unique identifier among hospitals. The independent variable was the number of inpatient and outpatient cases that each surgeon performed each week during the first fiscal year beginning July 1, 2013. The dependent variables were surgeons' number of inpatient and outpatient surgical cases, and intraoperative work relative value units (RVU's) for outpatient cases, during the second fiscal year. The average hospital in Iowa had less than half of its growth from year 1 to year 2 in numbers of cases among surgeons who performed >2 cases per week in the baseline year (23.0%±2.5% [SE], P2 cases per week at other hospitals in the state during that year (24.4%±2.6%, P<0.0001). Less than half the growth in RVU's was among those surgeons (21.3%±2.5%, P<0.0001). Most (≥50%) annual growth in surgery, both based on the number of total inpatient and outpatient surgical cases, and on the total outpatient RVU's, was attributable to surgeons who performed 2 or fewer cases per week at each hospital statewide during the preceding year. Therefore, the strategic priority should be to assure that the many low-caseload surgeons have access to convenient OR time (e.g., by allocating sufficient OR time, and assigning surgeon blocks, in a mathematically sound, evidence-based way). Although reducing turnover times and anesthesia-controlled times to promote growth will be beneficial for a few surgeons, the effect on total caseload will be small. Copyright © 2017 Elsevier Inc. All rights reserved.
Excitons in the Fractional Quantum Hall Effect
Laughlin, R. B.
1984-09-01
Quasiparticles of charge 1/m in the Fractional Quantum Hall Effect form excitons, which are collective excitations physically similar to the transverse magnetoplasma oscillations of a Wigner crystal. A variational exciton wavefunction which shows explicitly that the magnetic length is effectively longer for quasiparticles than for electrons is proposed. This wavefunction is used to estimate the dispersion relation of these excitons and the matrix elements to generate them optically out of the ground state. These quantities are then used to describe a type of nonlinear conductivity which may occur in these systems when they are relatively clean.
International Nuclear Information System (INIS)
Entin-Wohlman, O.
2005-01-01
Full Text:The spin-Hall effect is described. The Rashba and Dresselhaus spin-orbit interactions are both shown to yield the low temperature spin-Hall effect for strongly localized electrons coupled to phonons. A frequency-dependent electric field E(ω) generates a spin-polarization current, normal to E, due to interference of hopping paths. At zero temperature the corresponding spin-Hall conductivity is real and is proportional to ω 2 . At non-zero temperatures the coupling to the phonons yields an imaginary term proportional to ω. The interference also yields persistent spin currents at thermal equilibrium, at E = 0. The contributions from the Dresselhaus and Rashba interactions to the interference oppose each other
Modular invariance, universality and crossover in the quantum Hall effect
International Nuclear Information System (INIS)
Dolan, Brian P.
1999-01-01
An analytic form for the conductivity tensor in crossover between two quantum Hall plateaux is derived, which appears to be in good agreement with existing experimental data. The derivation relies on an assumed symmetry between quantum Hall states, a generalisation of the law of corresponding states from rational filling factors to complex conductivity, which has a mathematical expression in terms of an action of the modular group on the upper-half complex conductivity plane. This symmetry implies universality in quantum Hall crossovers. The assumption that the β-function for the complex conductivity is a complex analytic function, together with some experimental constraints, results in an analytic expression for the crossover, as a function of the external magnetic field
Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa.
Kalkhoff, Stephen J; Vecchia, Aldo V; Capel, Paul D; Meyer, Michael T
2012-01-01
Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates were studied from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, a small tributary near the headwaters of the Iowa River. Concentration trends were determined using the parametric regression model SEAWAVE-Q, which accounts for seasonal and flow-related variability. Daily estimated concentrations generated from the model were used with daily streamflow to calculate daily and yearly loads. Acetochlor, alachlor, metolachlor, and their ESA and OXA degradates were generally present in >50% of the samples collected from both sites throughout the study. Their concentrations generally decreased from 1996 through 2006, although the rate of decrease was slower after 2001. Concentrations of the ESA and OXA degradates decreased from 3 to about 23% yr. The concentration trend was related to the decreasing use of these compounds during the study period. Decreasing concentrations and constant runoff resulted in an average reduction of 10 to >3000 kg per year of alachlor and metolachlor ESA and OXA degradates being transported out of the Iowa River watershed. Transport of acetochlor and metolachlor parent compounds and their degradates from the Iowa River watershed ranged from <1% to about 6% of the annual application. These trends were related to the decreasing use of these compounds during the study period, but the year-to-year variability cannot explain changes in loads based on herbicide use alone. The trends were also affected by the timing and amount of precipitation. As expected, increased amounts of water moving through the watershed moved a greater percentage of the applied herbicides, especially the relatively soluble degradates, from the soils into the rivers through surface runoff, shallow groundwater inflow, and subsurface drainage. Copyright © by the American Society of Agronomy
U.S. Environmental Protection Agency — Ecoregions by state were extracted from the seamless national shapefile. Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and...
U.S. Environmental Protection Agency — Ecoregions by state were extracted from the seamless national shapefile. Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and...
Patrice Loiez
2004-01-01
To mark the 50th Anniversary of the founding of CERN, a day of tours, displays and presentations was held in October 2004. The assembly halls for the experiments that were waiting to be installed on the LHC, such as ATLAS shown here, were transformed into display areas and cafés.
Universal intrinsic spin Hall effect
Czech Academy of Sciences Publication Activity Database
Sinova, J.; Culcer, D.; Sinitsyn, N. A.; Niu, Q.; Jungwirth, Tomáš; MacDonald, A. H.
2004-01-01
Roč. 92, č. 12 (2004), 126603/1-126603/4 ISSN 0031-9007 R&D Projects: GA ČR GA202/02/0912 Institutional research plan: CEZ:AV0Z1010914 Keywords : semiconductor quantum wells * spin-orbit interaction * spin Hall effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.218, year: 2004
International Nuclear Information System (INIS)
Dhar, S.; Basu, B.; Ghosh, Subir
2007-01-01
We explain the intrinsic spin Hall effect from generic anyon dynamics in the presence of external electromagnetic field. The free anyon is represented as a spinning particle with an underlying non-commutative configuration space. The Berry curvature plays a major role in the analysis
The Other Hall Effect: College Board Physics
Sheppard, Keith; Gunning, Amanda M.
2013-01-01
Edwin Herbert Hall (1855-1938), discoverer of the Hall effect, was one of the first winners of the AAPT Oersted Medal for his contributions to the teaching of physics. While Hall's role in establishing laboratory work in high schools is widely acknowledged, his position as chair of the physics section of the Committee on College Entrance…
Hardesty, Carolyn, Ed.
1989-01-01
This issue of the children's quarterly magazine, "The Goldfinch," focuses on World War I. A brief discussion of how the United States came to enter the War is followed by a discussion of propaganda. An article on the use of posters to encourage citizens to participate in the war effort is illustrated with reproductions of several of…
Measurement of the Hall effect in semiconductors at supersonic frequencies
International Nuclear Information System (INIS)
Putyato, I.V.; Sukhanov, S.; Lezhnev, N.B.
1978-01-01
A new method of measuring the Hall effect in variable magnetic fields at super-high frequencies using slotted line is proposed. The method is applied to the measurement of the Hall effect in n-InSb samples. It is shown that the level of output signal of samples reduces with the increasing the charge carrier concentration and with decreasing the mobility. But the range of quadratic part of the dependence of the output signal power on the control current increases. It is stated that the output signal of samples does not depend on the magnetic field frequency in the range of 4-7.3 GHz
Measurement of the Hall effect in semiconductors at supersonic frequencies
Energy Technology Data Exchange (ETDEWEB)
Putyato, I V; Sukhanov, S; Lezhnev, N B [AN Tadzhikskoj SSR, Khorog. Pamirskij Biologicheskij Inst.
1978-01-01
A new method of measuring the Hall effect in variable magnetic fields at super-high frequencies using slotted line is proposed. The method is applied to the measurement of the Hall effect in n-InSb samples. It is shown that the level of output signal of samples reduces with the increasing the charge carrier concentration and with decreasing the mobility. But the range of quadratic part of the dependence of the output signal power on the control current increases. It is stated that the output signal of samples does not depend on the magnetic field frequency in the range of 4-7.3 GHz.
Quantum Hall Effect: proposed multi-electron tunneling experiment
International Nuclear Information System (INIS)
Kostadinov, I.Z.
1985-11-01
Here we propose a tunneling experiment for the fractional and Integral Quantum Hall Effect. It may demonstrate multi-electron tunneling and may provide information about the nature of the macroscopic quantum states of 2D electronic liquid or solid. (author)
Sharp, Peggy, Ed.; Turney, Michael, Ed.
The conference proceedings in this document include edited transcripts of the plenary sessions and individual reports on each of the 10 workshops from Iowa's Children in Jeopardy Conference. The conference was held, not for professional children's services workers, but for people with civic commitment and the ability to involve themselves and…
Fractional Quantum Hall Effect in n = 0 Landau Band of Graphene with Chern Number Matrix
Kudo, Koji; Hatsugai, Yasuhiro
2018-06-01
Fully taking into account the honeycomb lattice structure, fractional quantum Hall states of graphene are considered by a pseudopotential projected into the n = 0 Landau band. By using chirality as an internal degree of freedom, the Chern number matrices are defined and evaluated numerically. Quantum phase transition induced by changing a range of the interaction is demonstrated that is associated with chirality ferromagnetism. The chirality-unpolarized ground state is consistent with the Halperin 331 state of the bilayer quantum Hall system.
Hurst, Angela L. M.
1997-01-01
The enormous success of franchising as an expansion instrument has resulted in a franchising boom over the past few decades. In response to the success of franchising as a business expansion method and the subsequent complaints by unsuccessful or defrauded franchisees, legislation was enacted at the federal and state level to attempt to prevent franchisor abuses. The 1992 Iowa Franchise Law has been called the most controversial and restrictive pieces of franchise legislation in recent memory...
The Impact of the Iowa Franchise Law on Restaurant Franchisor Expansion Strategy,
1997-06-18
the federal and state level to attempt to prevent franchisor abuses. The 1992 Iowa Franchise Law has been called the most controversial and restrictive...its 1995 Amendments on restaurant franchisor expansion strategy, litigation with franchisees, and operational changes. The study sought information...from US restaurant franchisors who may have been impacted by the law. The research instrument consisted of a self-administered questionnaire, which was
Large quantum rings in the ν > 1 quantum Hall regime
International Nuclear Information System (INIS)
Raesaenen, E; Aichinger, M
2009-01-01
We study computationally the ground-state properties of large quantum rings in the filling-factor ν>1 quantum Hall regime. We show that the arrangement of electrons into different Landau levels leads to clear signatures in the total energies as a function of the magnetic field. In this context, we discuss possible approximations for the filling factor ν in the system. We are able to characterize integer-ν states in quantum rings in an analogy with conventional quantum Hall droplets. We also find a partially spin-polarized state between ν = 2 and 3. Despite the specific topology of a quantum ring, this state is strikingly reminiscent of the recently found ν = 5/2 state in a quantum dot.
Large quantum rings in the ν > 1 quantum Hall regime.
Räsänen, E; Aichinger, M
2009-01-14
We study computationally the ground-state properties of large quantum rings in the filling-factor ν>1 quantum Hall regime. We show that the arrangement of electrons into different Landau levels leads to clear signatures in the total energies as a function of the magnetic field. In this context, we discuss possible approximations for the filling factor ν in the system. We are able to characterize integer-ν states in quantum rings in an analogy with conventional quantum Hall droplets. We also find a partially spin-polarized state between ν = 2 and 3. Despite the specific topology of a quantum ring, this state is strikingly reminiscent of the recently found ν = 5/2 state in a quantum dot.
Geometrical Description of fractional quantum Hall quasiparticles
Park, Yeje; Yang, Bo; Haldane, F. D. M.
2012-02-01
We examine a description of fractional quantum Hall quasiparticles and quasiholes suggested by a recent geometrical approach (F. D. M. Haldane, Phys. Rev. Lett. 108, 116801 (2011)) to FQH systems, where the local excess electric charge density in the incompressible state is given by a topologically-quantized ``guiding-center spin'' times the Gaussian curvature of a ``guiding-center metric tensor'' that characterizes the local shape of the correlation hole around electrons in the fluid. We use a phenomenological energy function with two ingredients: the shear distortion energy of area-preserving distortions of the fluid, and a local (short-range) approximation to the Coulomb energy of the fluctuation of charge density associated with the Gaussian curvature. Quasiparticles and quasiholes of the 1/3 Laughlin state are modeled as ``punctures'' in the incompressible fluid which then relax by geometric distortion which generates Gaussian curvature, giving rise to the charge-density profile around the topological excitation.
Hall effect in noncommutative coordinates
International Nuclear Information System (INIS)
Dayi, Oemer F.; Jellal, Ahmed
2002-01-01
We consider electrons in uniform external magnetic and electric fields which move on a plane whose coordinates are noncommuting. Spectrum and eigenfunctions of the related Hamiltonian are obtained. We derive the electric current whose expectation value gives the Hall effect in terms of an effective magnetic field. We present a receipt to find the action which can be utilized in path integrals for noncommuting coordinates. In terms of this action we calculate the related Aharonov-Bohm phase and show that it also yields the same effective magnetic field. When magnetic field is strong enough this phase becomes independent of magnetic field. Measurement of it may give some hints on spatial noncommutativity. The noncommutativity parameter θ can be tuned such that electrons moving in noncommutative coordinates are interpreted as either leading to the fractional quantum Hall effect or composite fermions in the usual coordinates
General vibration monitoring: Experimental hall
International Nuclear Information System (INIS)
Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.
1993-01-01
The reported vibration data were generated from measurements made on the experimental hall floor on December 2, 1992. At the time of the measurements, the ESRF hydrolevel was set-up in the Early Assembly Area (EAA) of the experimental hall and was being used to measure static displacement (settlement) of the floor. The vibration measurement area was on and adjacent to the EAA, in the vicinity of the ESRF hydrolevel test which was in progress. This report summarizes the objectives, instrumentation, measurement locations, observations, and conclusions, and provides selected results in the form of RMS vs. time plots, and power spectral densities from which frequency information can be derived. Measured response amplitudes were within the vibration criteria established for the APS
Nonadiabatic effects in the Quantum Hall regime
International Nuclear Information System (INIS)
Page, D.A.; Brown, E.
1993-01-01
The authors consider the effect of a finite electric field on the states of a Bloch electron in two dimensions, with a uniform magnetic field present. They make use of the concept of electric time translation symmetry and treat the electric and magnetic fields symmetrically in a time dependent formalism. In addition to a wave vector k, the states are characterized by a frequency specifying the behavior under electric time translations. An effective Hamiltonian is employed to obtain the splitting of an isolated Bloch band into open-quotes frequencyclose quotes subbands. The time-averaged velocity and energy of the states are expressed in terms of the frequency dispersion. The relationship to the Stark ladder eigenstates in a scalar potential representation of the electric field is examined. This is seen to justify the use of the averaged energy in determining occupation of the states. In the weak electric field (adiabatic) limit, an expression is recovered for the quantized Hall conductivity of a magnetic subband as a topological invariant. A numerical procedure is outlined and results obtained over a range of electric field strengths. A transition between strong and weak field regimes is seen, with level repulsions between the frequencies playing an important role. The numerical results show how the magnetic subband structure and quantized Hall conductivity emerge as the electric field becomes weaker. In this regime, the behavior can be understood by comparison to the predictions of the adiabatic approximation. The latter predicts crossings in the frequencies at certain locations in wave vector space. Nonadiabatic effects are seen to produce gaps in the frequency spectrum at these locations. 35 refs., 14 figs
Scanning vector Hall probe microscope
Czech Academy of Sciences Publication Activity Database
Fedor, J.; Cambel, V.; Gregušová, D.; Hanzelka, Pavel; Dérer, J.; Volko, J.
2003-01-01
Roč. 74, č. 12 (2003), s. 5105 - 5110 ISSN 0034-6748 Institutional research plan: CEZ:AV0Z2065902 Keywords : VHPM * Hall sensor * Helium cryostat Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.343, year: 2003 http://web. ebscohost .com/ehost/pdf?vid=8&hid=115&sid=a7c0555a-21f4-4932-b1c6-a308ac4dd50b%40sessionmgr2
Rodriguez, Lulu; Farnall, Olan; Geske, Joel; Peterson, Jane W.
1998-01-01
A study of 483 Iowa citizens and state legislators found that self-interest had the strongest effect on formation of opinions toward environmental protection; sociotropic and symbolic politics models were also effective. Results indicate that campaign messages must stress the benefits of environmental protection to the individual. (JOW)
David J. Nowak; Eric J. Greenfield
2010-01-01
This report details how land cover and urbanization vary within the states of Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota by community (incorporated and census designated places), county subdivision, and county. Specifically this report provides critical urban and community...
US Senate, 2015
2015-01-01
The Federal Government currently funds a number of programs to support early childhood education and care. However, they are well short of meeting existing needs. The Strong Start for America's Children Act significantly expands investments at the Federal level to accelerate the work being done in States to support high-quality pre-K. It also…
Supporting Energy Transitions and Miscanthus Program Development at the University of Iowa
Lain, Kayley Christina
Miscanthus is a highly productive, low-input biofuel crop that supports agricultural diversification with improved performance for climate commitment, energy security, and water quality over first generation biofuels. Despite its high performance, no local or regional markets for the feedstock have formed in North America, and current climate-based productivity assessment methods lack the information farmers and decision-makers need to establish commercial scale bioenergy markets, programs, and thermal co-firing plans. This study develops a Miscanthus Suitability Rating and a transferable field-scale siting method, applied at 10 m resolution across the State of Iowa to assess miscanthus production potential and identify individual farms that are highly suitable for large-scale miscanthus cultivation while maintaining a majority of existing row cropping acreage. Results show that highly suitable fields within 50 miles (84 km) of each of Iowa's coal-fired electrical generating units (EGUs) can displace up to 43% of current coal consumption. Every EGU in Iowa has land resource to produce local miscanthus to co-fire with other solid fuels at industry-leading levels without significantly impacting local row crop production. Seven of the state's smaller facilities could even operate exclusively on local miscanthus with advancements in densification technology. The energy evaluation tool developed in this work estimates the energy return on investment (EROI) of Iowa miscanthus for existing thermal generation facilities between 37 and 59, depending on transportation requirements and chemical field applications. This transition would diversify local agribusiness and energy feedstocks, reduce greenhouse gas emissions and provide a sustainable, dispatchable, in-state fuel source to complement wind and solar energy.
Zhou, Jian; Sun, Qiang; Wang, Qian; Kawazoe, Yoshiyuki; Jena, Puru
2016-06-07
Exploring a two-dimensional intrinsic quantum spin Hall state with a large band gap as well as an anomalous Hall state in realizable materials is one of the most fundamental and important goals for future applications in spintronics, valleytronics, and quantum computing. Here, by combining first-principles calculations with a tight-binding model, we predict that Sb or Bi can epitaxially grow on a stable and ferromagnetic MnO2 thin film substrate, forming a flat honeycomb sheet. The flatness of Sb or Bi provides an opportunity for the existence of Dirac points in the Brillouin zone, with its position effectively tuned by surface hydrogenation. The Dirac points in spin up and spin down channels split due to the proximity effects induced by MnO2. In the presence of both intrinsic and Rashba spin-orbit coupling, we find two band gaps exhibiting a large band gap quantum spin Hall state and a nearly quantized anomalous Hall state which can be tuned by adjusting the Fermi level. Our findings provide an efficient way to realize both quantized intrinsic spin Hall conductivity and anomalous Hall conductivity in a single material.
Quantum spin/valley Hall effect and topological insulator phase transitions in silicene
Tahir, M.
2013-04-26
We present a theoretical realization of quantum spin and quantum valley Hall effects in silicene. We show that combination of an electric field and intrinsic spin-orbit interaction leads to quantum phase transitions at the charge neutrality point. This phase transition from a two dimensional topological insulator to a trivial insulating state is accompanied by a quenching of the quantum spin Hall effect and the onset of a quantum valley Hall effect, providing a tool to experimentally tune the topological state of silicene. In contrast to graphene and other conventional topological insulators, the proposed effects in silicene are accessible to experiments.
Quantum spin/valley Hall effect and topological insulator phase transitions in silicene
Tahir, M.; Manchon, Aurelien; Sabeeh, K.; Schwingenschlö gl, Udo
2013-01-01
We present a theoretical realization of quantum spin and quantum valley Hall effects in silicene. We show that combination of an electric field and intrinsic spin-orbit interaction leads to quantum phase transitions at the charge neutrality point. This phase transition from a two dimensional topological insulator to a trivial insulating state is accompanied by a quenching of the quantum spin Hall effect and the onset of a quantum valley Hall effect, providing a tool to experimentally tune the topological state of silicene. In contrast to graphene and other conventional topological insulators, the proposed effects in silicene are accessible to experiments.
Field theory of anyons and the fractional quantum Hall effect
International Nuclear Information System (INIS)
Viefers, S.F.
1997-11-01
The thesis is devoted to a theoretical study of anyons, i.e. particles with fractional statistics moving in two space dimensions, and the quantum Hall effect. The latter constitutes the only known experimental realization of anyons in that the quasiparticle excitations in the fractional quantum Hall system are believed to obey fractional statistics. First, the properties of ideal quantum gases in two dimensions and in particular the equation of state of the free anyons gas are discussed. Then, a field theory formulation of anyons in a strong magnetic field is presented and later extended to a system with several species of anyons. The relation of this model to fractional exclusion statistics, i.e. intermediate statistics introduced by a generalization of the Pauli principle, and to the low-energy excitations at the edge of the quantum Hall system is discussed. Finally, the Chern-Simons-Landau-Ginzburg theory of the fractional quantum Hall effect is studied, mainly focusing on edge effects; both the ground state and the low-energy edge excitations are examined in the simple one-component model and in an extended model which includes spin effects
Observation of the fractional quantum Hall effect in graphene.
Bolotin, Kirill I; Ghahari, Fereshte; Shulman, Michael D; Stormer, Horst L; Kim, Philip
2009-11-12
When electrons are confined in two dimensions and subject to strong magnetic fields, the Coulomb interactions between them can become very strong, leading to the formation of correlated states of matter, such as the fractional quantum Hall liquid. In this strong quantum regime, electrons and magnetic flux quanta bind to form complex composite quasiparticles with fractional electronic charge; these are manifest in transport measurements of the Hall conductivity as rational fractions of the elementary conductance quantum. The experimental discovery of an anomalous integer quantum Hall effect in graphene has enabled the study of a correlated two-dimensional electronic system, in which the interacting electrons behave like massless chiral fermions. However, owing to the prevailing disorder, graphene has so far exhibited only weak signatures of correlated electron phenomena, despite intense experimental and theoretical efforts. Here we report the observation of the fractional quantum Hall effect in ultraclean, suspended graphene. In addition, we show that at low carrier density graphene becomes an insulator with a magnetic-field-tunable energy gap. These newly discovered quantum states offer the opportunity to study correlated Dirac fermions in graphene in the presence of large magnetic fields.
Samson, Thomas
Nous proposons une methode permettant d'obtenir une expression pour la conductivite de Hall de structures electroniques bidimensionnelles et nous examinons celle -ci a la limite d'une temperature nulle dans le but de verifier l'effet Hall quantique. Nous allons nous interesser essentiellement a l'effet Hall quantique entier et aux effets fractionnaires inferieurs a un. Le systeme considere est forme d'un gaz d'electrons en interaction faible avec les impuretes de l'echantillon. Le modele du gaz d'electrons consiste en un gaz bidimensionnel d'electrons sans spin expose perpendiculairement a un champ magnetique uniforme. Ce dernier est decrit par le potentiel vecteur vec{rm A} defini dans la jauge de Dingle ou jauge symetrique. Conformement au formalisme de la seconde quantification, l'hamiltonien de ce gaz est represente dans la base des etats a un-corps de Dingle |n,m> et exprime ainsi en terme des operateurs de creation et d'annihilation correspondants a_sp{ rm n m}{dag} et a _{rm n m}. Nous supposons de plus que les electrons du niveau fondamental de Dingle interagissent entre eux via le potentiel coulombien. La methode utilisee fait appel a une equation mai tresse a N-corps, de nature quantique et statistique, et verifiant le second principe de la thermodynamique. A partir de celle-ci, nous obtenons un systeme d'equations differentielles appele hierarchie d'equations quantique dont la resolution nous permet de determiner une equation a un-corps, dite de Boltzmann quantique, et dictant l'evolution de la moyenne statistique de l'operateur non-diagonal a _sp{rm n m}{dag } a_{rm n}, _{rm m}, sous l'action du champ electrique applique vec{rm E}(t). C'est sa solution Tr(p(t) a _sp{rm n m}{dag} a_{rm n},_ {rm m}), qui definit la relation de convolution entre la densite courant de Hall vec{rm J}_{rm H }(t) et le champ electrique vec {rm E}(t) dont la transformee de Laplace-Fourier du noyau nous fournit l'expression de la conductivite de Hall desiree. Pour une valeur de
Czech Academy of Sciences Publication Activity Database
Ortiz, G.; Strenger, C.; Uhnevionak, V.; Burenkov, A.; Bauer, A.J.; Pichler, P.; Cristiano, F.; Bedel-Pereira, E.; Mortet, Vincent
2015-01-01
Roč. 106, č. 6 (2015), "062104-1"-"062104-5" ISSN 0003-6951 Institutional support: RVO:68378271 Keywords : MOSFETs * doping * Hall mobility * conduction bands * epitaxy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.142, year: 2015
Mani, Arjun; Benjamin, Colin
2016-04-13
On the surface of 2D topological insulators, 1D quantum spin Hall (QSH) edge modes occur with Dirac-like dispersion. Unlike quantum Hall (QH) edge modes, which occur at high magnetic fields in 2D electron gases, the occurrence of QSH edge modes is due to spin-orbit scattering in the bulk of the material. These QSH edge modes are spin-dependent, and chiral-opposite spins move in opposing directions. Electronic spin has a larger decoherence and relaxation time than charge. In view of this, it is expected that QSH edge modes will be more robust to disorder and inelastic scattering than QH edge modes, which are charge-dependent and spin-unpolarized. However, we notice no such advantage accrues in QSH edge modes when subjected to the same degree of contact disorder and/or inelastic scattering in similar setups as QH edge modes. In fact we observe that QSH edge modes are more susceptible to inelastic scattering and contact disorder than QH edge modes. Furthermore, while a single disordered contact has no effect on QH edge modes, it leads to a finite charge Hall current in the case of QSH edge modes, and thus a vanishing of the pure QSH effect. For more than a single disordered contact while QH states continue to remain immune to disorder, QSH edge modes become more susceptible--the Hall resistance for the QSH effect changes sign with increasing disorder. In the case of many disordered contacts with inelastic scattering included, while quantization of Hall edge modes holds, for QSH edge modes a finite charge Hall current still flows. For QSH edge modes in the inelastic scattering regime we distinguish between two cases: with spin-flip and without spin-flip scattering. Finally, while asymmetry in sample geometry can have a deleterious effect in the QSH case, it has no impact in the QH case.
International Nuclear Information System (INIS)
Mani, Arjun; Benjamin, Colin
2016-01-01
On the surface of 2D topological insulators, 1D quantum spin Hall (QSH) edge modes occur with Dirac-like dispersion. Unlike quantum Hall (QH) edge modes, which occur at high magnetic fields in 2D electron gases, the occurrence of QSH edge modes is due to spin–orbit scattering in the bulk of the material. These QSH edge modes are spin-dependent, and chiral-opposite spins move in opposing directions. Electronic spin has a larger decoherence and relaxation time than charge. In view of this, it is expected that QSH edge modes will be more robust to disorder and inelastic scattering than QH edge modes, which are charge-dependent and spin-unpolarized. However, we notice no such advantage accrues in QSH edge modes when subjected to the same degree of contact disorder and/or inelastic scattering in similar setups as QH edge modes. In fact we observe that QSH edge modes are more susceptible to inelastic scattering and contact disorder than QH edge modes. Furthermore, while a single disordered contact has no effect on QH edge modes, it leads to a finite charge Hall current in the case of QSH edge modes, and thus a vanishing of the pure QSH effect. For more than a single disordered contact while QH states continue to remain immune to disorder, QSH edge modes become more susceptible—the Hall resistance for the QSH effect changes sign with increasing disorder. In the case of many disordered contacts with inelastic scattering included, while quantization of Hall edge modes holds, for QSH edge modes a finite charge Hall current still flows. For QSH edge modes in the inelastic scattering regime we distinguish between two cases: with spin-flip and without spin-flip scattering. Finally, while asymmetry in sample geometry can have a deleterious effect in the QSH case, it has no impact in the QH case. (paper)
Levitation and percolation in quantum Hall systems with correlated disorder
Song, Hui; Maruyama, Isao; Hatsugai, Yasuhiro
2007-01-01
We investigate the integer quantum Hall system in a two dimensional lattice model with spatially correlated disorder by using the efficient method to calculate the Chern number proposed by Fukui et al. [J. Phys. Soc. Jpn. 74, 1674 (2005)]. Distribution of charge density indicates that the extended states at the center of each Landau band have percolating current paths, which are topologically equivalent to the edge states that exist in a system with boundaries. As increasing the strength of d...
Spin Hall effect by surface roughness
Zhou, Lingjun
2015-01-08
The spin Hall and its inverse effects, driven by the spin orbit interaction, provide an interconversion mechanism between spin and charge currents. Since the spin Hall effect generates and manipulates spin current electrically, to achieve a large effect is becoming an important topic in both academia and industries. So far, materials with heavy elements carrying a strong spin orbit interaction, provide the only option. We propose here a new mechanism, using the surface roughness in ultrathin films, to enhance the spin Hall effect without heavy elements. Our analysis based on Cu and Al thin films suggests that surface roughness is capable of driving a spin Hall angle that is comparable to that in bulk Au. We also demonstrate that the spin Hall effect induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.
Tunneling Anomalous and Spin Hall Effects.
Matos-Abiague, A; Fabian, J
2015-07-31
We predict, theoretically, the existence of the anomalous Hall effect when a tunneling current flows through a tunnel junction in which only one of the electrodes is magnetic. The interfacial spin-orbit coupling present in the barrier region induces a spin-dependent momentum filtering in the directions perpendicular to the tunneling current, resulting in a skew tunneling even in the absence of impurities. This produces an anomalous Hall conductance and spin Hall currents in the nonmagnetic electrode when a bias voltage is applied across the tunneling heterojunction. If the barrier is composed of a noncentrosymmetric material, the anomalous Hall conductance and spin Hall currents become anisotropic with respect to both the magnetization and crystallographic directions, allowing us to separate this interfacial phenomenon from the bulk anomalous and spin Hall contributions. The proposed effect should be useful for proving and quantifying the interfacial spin-orbit fields in metallic and metal-semiconductor systems.
Numerical investigation of a Hall thruster plasma
International Nuclear Information System (INIS)
Roy, Subrata; Pandey, B.P.
2002-01-01
The dynamics of the Hall thruster is investigated numerically in the framework of a one-dimensional, multifluid macroscopic description of a partially ionized xenon plasma using finite element formulation. The model includes neutral dynamics, inelastic processes, and plasma-wall interaction. Owing to disparate temporal scales, ions and neutrals have been described by set of time-dependent equations, while electrons are considered in steady state. Based on the experimental observations, a third order polynomial in electron temperature is used to calculate ionization rate. The results show that in the acceleration channel the increase in the ion number density is related to the decrease in the neutral number density. The electron and ion velocity profiles are consistent with the imposed electric field. The electron temperature remains uniform for nearly two-thirds of the channel; then sharply increases to a peak before dropping slightly at the exit. This is consistent with the predicted electron gyration velocity distribution
Determination of the Hall Thruster Operating Regimes
International Nuclear Information System (INIS)
L. Dorf; V. Semenov; Y. Raitses; N.J. Fisch
2002-04-01
A quasi one-dimensional (1-D) steady-state model of the Hall thruster is presented. For the same discharge voltage two operating regimes are possible -- with and without the anode sheath. For given mass flow rate, magnetic field profile and discharge voltage a unique solution can be constructed, assuming that the thruster operates in one of the regimes. However, we show that for a given temperature profile the applied discharge voltage uniquely determines the operating regime: for discharge voltages greater than a certain value, the sheath disappears. That result is obtained over a wide range of incoming neutral velocities, channel lengths and widths, and cathode plane locations. It is also shown that a good correlation between the quasi 1-D model and experimental results can be achieved by selecting an appropriate electron mobility and temperature profile
Magnon Hall effect on the Lieb lattice.
Cao, Xiaodong; Chen, Kai; He, Dahai
2015-04-29
Ferromagnetic insulators without inversion symmetry may show magnon Hall effect (MHE) in the presence of a temperature gradient due to the existence of Dzyaloshinskii-Moriya interaction (DMI). In this theoretical study, we investigate MHE on a lattice with inversion symmetry, namely the Lieb lattice, where the DMI is introduced by adding an external electric field. We show the nontrivial topology of this model by examining the existence of edge states and computing the topological phase diagram characterized by the Chern numbers of different bands. Together with the topological phase diagram, we can further determine the sign and magnitude of the transverse thermal conductivity. The impact of the flat band possessed by this model on the thermal conductivity is discussed by computing the Berry curvature analytically.
Analysis of Potential Benefits and Costs of Updating the Commercial Building Energy Code in Iowa
Energy Technology Data Exchange (ETDEWEB)
Cort, Katherine A.; Belzer, David B.; Richman, Eric E.; Winiarski, David W.
2002-09-07
The state of Iowa is considering adpoting ASHRAE 90.1-1999 as its commercial building energy code. In an effort to evaluate whether or not this is an appropraite code for the state, the potential benefits and costs of adopting this standard are considered. Both qualitative and quantitative benefits are assessed. The energy simulation and economic results suggest that adopting ASHRAE 90.1-1999 would provide postitive net benefits to the state relative to the building and design requirements currently in place.
Multi-region relaxed Hall magnetohydrodynamics with flow
Energy Technology Data Exchange (ETDEWEB)
Lingam, Manasvi, E-mail: mlingam@princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Abdelhamid, Hamdi M., E-mail: hamdi@ppl.k.u-tokyo.ac.jp [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Physics Department, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt); Hudson, Stuart R., E-mail: shudson@pppl.gov [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States)
2016-08-15
The recent formulations of multi-region relaxed magnetohydrodynamics (MRxMHD) have generalized the famous Woltjer-Taylor states by incorporating a collection of “ideal barriers” that prevent global relaxation and flow. In this paper, we generalize MRxMHD with flow to include Hall effects, and thereby obtain the partially relaxed counterparts of the famous double Beltrami states as a special subset. The physical and mathematical consequences arising from the introduction of the Hall term are also presented. We demonstrate that our results (in the ideal MHD limit) constitute an important subset of ideal MHD equilibria, and we compare our approach against other variational principles proposed for deriving the partially relaxed states.
Matrix effective theories of the fractional quantum Hall effect
International Nuclear Information System (INIS)
Cappelli, Andrea; Rodriguez, Ivan D
2009-01-01
The present understanding of nonperturbative ground states in the fractional quantum Hall effect is based on effective theories of the Jain 'composite fermion' excitations. We review the approach based on matrix variables, i.e. D0 branes, originally introduced by Susskind and Polychronakos. We show that the Maxwell-Chern-Simons matrix gauge theory provides a matrix generalization of the quantum Hall effect, where the composite-fermion construction naturally follows from gauge invariance. The matrix ground states obtained by suitable projections of higher Landau levels are found to be in one-to-one correspondence with the Laughlin and Jain hierarchical states. The matrix theory possesses a physical limit for commuting matrices that could be reachable while staying in the same phase.
Quasiparticle Aggregation in the Fractional Quantum Hall Effect
Laughlin, R. B.
1984-10-10
Quasiparticles in the Fractional Quantum Hall Effect behave qualitatively like electrons confined to the lowest landau level, and can do everything electrons can do, including condense into second generation Fractional Quantum Hall ground states. I review in this paper the reasoning leading to variational wavefunctions for ground state and quasiparticles in the 1/3 effect. I then show how two-quasiparticle eigenstates are uniquely determined from symmetry, and how this leads in a natural way to variational wavefunctions for composite states which have the correct densities (2/5, 2/7, ...). I show in the process that the boson, anyon and fermion representations for the quasiparticles used by Haldane, Halperin, and me are all equivalent. I demonstrate a simple way to derive Halperin`s multiple-valued quasiparticle wavefunction from the correct single-valued electron wavefunction. (auth)
Anomalous Hall effect in polycrystalline Ni films
Guo, Zaibing
2012-02-01
We systematically studied the anomalous Hall effect in a series of polycrystalline Ni films with thickness ranging from 4 to 200 nm. It is found that both the longitudinal and anomalous Hall resistivity increased greatly as film thickness decreased. This enhancement should be related to the surface scattering. In the ultrathin films (46 nm thick), weak localization corrections to anomalous Hall conductivity were studied. The granular model, taking into account the dominated intergranular tunneling, has been employed to explain this phenomenon, which can explain the weak dependence of anomalous Hall resistivity on longitudinal resistivity as well. © 2011 Elsevier Ltd. All rights reserved.
Temperature Gradient in Hall Thrusters
International Nuclear Information System (INIS)
Staack, D.; Raitses, Y.; Fisch, N.J.
2003-01-01
Plasma potentials and electron temperatures were deduced from emissive and cold floating probe measurements in a 2 kW Hall thruster, operated in the discharge voltage range of 200-400 V. An almost linear dependence of the electron temperature on the plasma potential was observed in the acceleration region of the thruster both inside and outside the thruster. This result calls into question whether secondary electron emission from the ceramic channel walls plays a significant role in electron energy balance. The proportionality factor between the axial electron temperature gradient and the electric field is significantly smaller than might be expected by models employing Ohmic heating of electrons
Hall Thruster Thermal Modeling and Test Data Correlation
Myers, James; Kamhawi, Hani; Yim, John; Clayman, Lauren
2016-01-01
The life of Hall Effect thrusters are primarily limited by plasma erosion and thermal related failures. NASA Glenn Research Center (GRC) in cooperation with the Jet Propulsion Laboratory (JPL) have recently completed development of a Hall thruster with specific emphasis to mitigate these limitations. Extending the operational life of Hall thursters makes them more suitable for some of NASA's longer duration interplanetary missions. This paper documents the thermal model development, refinement and correlation of results with thruster test data. Correlation was achieved by minimizing uncertainties in model input and recognizing the relevant parameters for effective model tuning. Throughout the thruster design phase the model was used to evaluate design options and systematically reduce component temperatures. Hall thrusters are inherently complex assemblies of high temperature components relying on internal conduction and external radiation for heat dispersion and rejection. System solutions are necessary in most cases to fully assess the benefits and/or consequences of any potential design change. Thermal model correlation is critical since thruster operational parameters can push some components/materials beyond their temperature limits. This thruster incorporates a state-of-the-art magnetic shielding system to reduce plasma erosion and to a lesser extend power/heat deposition. Additionally a comprehensive thermal design strategy was employed to reduce temperatures of critical thruster components (primarily the magnet coils and the discharge channel). Long term wear testing is currently underway to assess the effectiveness of these systems and consequently thruster longevity.
An aerial radiological survey of the Ames Laboratory and surrounding area, Ames, Iowa
International Nuclear Information System (INIS)
Maurer, R.J.
1993-04-01
An aerial radiological survey of the Ames Laboratory and surrounding area in Ames, Iowa, was conducted during the period July 15--25, 1991. The purpose of the survey was to measure and document the terrestrial radiological environment at the Ames Laboratory and the surrounding area for use in effective environmental management and emergency response planning. The aerial survey was flown at an altitude of 200 feet (61 meters) along a series of parallel lines 350 feet (107 meters) apart. The survey encompassed an area of 36 square miles (93 square kilometers) and included the city of Ames, Iowa, and the Iowa State University. The results are reported as exposure rates at 1 meter above ground level (inferred from the aerial data) in the form of a gamma radiation contour map. Typical background exposure rates were found to vary from 7 to 9 microroentgens per hour (μR/h). No anomalous radiation levels were detected at the Ames Laboratory. However, one anomalous radiation source was detected at an industrial storage yard in the city of Ames. In support of the aerial survey, ground-based exposure rate and soil sample measurements were obtained at several sites within the survey perimeter. The results of the aerial and ground-based measurements were found to agree within the expected uncertainty of ±15%
Green, Christopher T.; Bekins, Barbara A.; Kalkhoff, Stephen J.; Hirsch, Robert M.; Liao, Lixia; Barnes, Kimberlee K.
2014-01-01
Understanding how nitrogen fluxes respond to changes in agriculture and climate is important for improving water quality. In the midwestern United States, expansion of corn cropping for ethanol production led to increasing N application rates in the 2000s during a period of extreme variability of annual precipitation. To examine the effects of these changes, surface water quality was analyzed in 10 major Iowa Rivers. Several decades of concentration and flow data were analyzed with a statistical method that provides internally consistent estimates of the concentration history and reveals flow-normalized trends that are independent of year-to-year streamflow variations. Flow-normalized concentrations of nitrate+nitrite-N decreased from 2000 to 2012 in all basins. To evaluate effects of annual discharge and N loading on these trends, multiple conceptual models were developed and calibrated to flow-weighted annual concentrations. The recent declining concentration trends can be attributed to both very high and very low discharge in the 2000s and to the long (e.g., 8 year) subsurface residence times in some basins. Dilution of N and depletion of stored N occurs in years with high discharge. Reduced N transport and increased N storage occurs in low-discharge years. Central Iowa basins showed the greatest reduction in flow-normalized concentrations, likely because of smaller storage volumes and shorter residence times. Effects of land-use changes on the water quality of major Iowa Rivers may not be noticeable for years or decades in peripheral basins of Iowa, and may be obscured in the central basins where extreme flows strongly affect annual concentration trends.
2010-02-19
... Rita C. Hall; Notice of Application Accepted for Filing With the Commision, Soliciting Motions To.... Project No.: 13652-000. c. Date filed: January 11, 2010. d. Applicant: Gary E. Hall and Rita C. Hall. e... Policies Act of 1978, 16 U.S.C. 2705, 2708. h. Applicant Contact: Mr. Gary E. Hall and Ms. Rita C. Hall, P...
Nondestructive hall coefficient measurements using ACPD techniques
Velicheti, Dheeraj; Nagy, Peter B.; Hassan, Waled
2018-04-01
Hall coefficient measurements offer great opportunities as well as major challenges for nondestructive materials characterization. The Hall effect is produced by the magnetic Lorentz force acting on moving charge carriers in the presence of an applied magnetic field. The magnetic perturbation gives rise to a Hall current that is normal to the conduction current but does not directly perturb the electric potential distribution. Therefore, Hall coefficient measurements usually exploit the so-called transverse galvanomagnetic potential drop effect that arises when the Hall current is intercepted by the boundaries of the specimen and thereby produce a measurable potential drop. In contrast, no Hall potential is produced in a large plate in the presence of a uniform normal field at quasi-static low frequencies. In other words, conventional Hall coefficient measurements are inherently destructive since they require cutting the material under tests. This study investigated the feasibility of using alternating current potential drop (ACPD) techniques for nondestructive Hall coefficient measurements in plates. Specifically, the directional four-point square-electrode configuration is investigated with superimposed external magnetic field. Two methods are suggested to make Hall coefficient measurements in large plates without destructive machining. At low frequencies, constraining the bias magnetic field can replace constraining the dimensions of the specimen, which is inherently destructive. For example, when a cylindrical permanent magnet is used to provide the bias magnetic field, the peak Hall voltage is produced when the diameter of the magnet is equal to the diagonal of the square ACPD probe. Although this method is less effective than cutting the specimen to a finite size, the loss of sensitivity is less than one order of magnitude even at very low frequencies. In contrast, at sufficiently high inspection frequencies the magnetic field of the Hall current induces a
Iowa pavement asset management decision-making framework.
2015-10-01
Most local agencies in Iowa currently make their pavement treatment decisions based on their limited experience due primarily to : lack of a systematic decision-making framework and a decision-aid tool. The lack of objective condition assessment data...
Iowa task report : US 18 concrete overlay construction under traffic.
2012-05-01
The National Concrete Pavement Technology Center, Iowa Department of Transportation, and Federal Highway Administration set out to demonstrate and document the design and construction of portland cement concrete (PCC) overlays on two-lane roadways wh...
Iowa's renewable energy and infrastructure impacts : final report
2010-04-01
The federal government is aggressively promoting biofuels as an answer to global climate change and dependence on imported sources : of energy. Iowa has quickly become a leader in the bioeconomy and wind energy production, but meeting the United Stat...
Episodic chasing in pathological gamblers using the Iowa gambling task
DEFF Research Database (Denmark)
Linnet, J.; Rojskjaer, S.; Nygaard, Jørgen
2006-01-01
NPGs on the Iowa Gambling Task (IGT) and the Zuckerman Sensation Seeking Scale (SSS). The PGs showed significantly more chasing and had significantly poorer decision-making strategies than NPGs, particularly among males (F = 4.52, p
78 FR 44090 - Television Broadcasting Services; Cedar Rapids, Iowa
2013-07-23
...] Television Broadcasting Services; Cedar Rapids, Iowa AGENCY: Federal Communications Commission. ACTION... acceptance of full power television rulemaking petitions requesting channel substitutions in May 2011, it... 73 Television, Television broadcasting. Federal Communications Commission. Hossein Hashemzadeh...
Hall magnetohydrodynamics of neutral layers
International Nuclear Information System (INIS)
Huba, J.D.; Rudakov, L.I.
2003-01-01
New analytical and numerical results of the dynamics of inhomogeneous, reversed field current layers in the Hall limit (i.e., characteristic length scales < or approx. the ion inertial length) are presented. Specifically, the two- and three-dimensional evolution of a current layer that supports a reversed field plasma configuration and has a density gradient along the current direction is studied. The two-dimensional study demonstrates that a density inhomogeneity along the current direction can dramatically redistribute the magnetic field and plasma via magnetic shock-like or rarefaction waves. The relative direction between the density gradient and current flow plays a critical role in the evolution of the current sheet. One important result is that the current sheet can become very thin rapidly when the density gradient is directed opposite to the current. The three-dimensional study uses the same plasma and field configuration as the two-dimensional study but is also initialized with a magnetic field perturbation localized along the current channel upstream of the plasma inhomogeneity. The perturbation induces a magnetic wave structure that propagates in the direction of the electron drift (i.e., opposite to the current). The propagating wave structure is a Hall phenomenon associated with magnetic field curvature. The interaction between the propagating wave structure and the evolving current layer can lead to rapid magnetic field line reconnection. The results are applied to laboratory and space plasma processes
Magnetic properties and Hall effect of single-crystalline YMn6Sn6
International Nuclear Information System (INIS)
Uhlirova, K.; Sechovsky, V.; Boer, F.R. de; Yoshii, S.; Yamamoto, T.; Hagiwara, M.; Lefevre, C.; Venturini, G.
2007-01-01
Magnetization behavior and Hall resistivity of YMn 6 Sn 6 , which crystallizes in the hexagonal HfFe 6 Ge 6 -type of structure, have been investigated on single crystals at various temperatures in the ordered magnetic state. The field dependence of the Hall resistivity shows anomalies, which are related to the field-induced spin reorientations occurring in YMn 6 Sn 6 . It is also found that the Hall resistivity cannot simply be described by the anomalous contribution proportional to the magnetization, but that an additional field-dependent contribution is present
Littin, Gregory R.; McVay, Jason C.
2009-01-01
metals, wastewater, or fuel contaminants were found to exceed drinking-water regulations for the USEPA or State of Iowa targeted constituents. Bacteria densities for Escherichia coli (E. coli) ranged from less than 10 to more than 600,000 colony-forming units per 100 milliliters of water and were largest following intense rainfall runoff. The largest densities were recorded in samples collected from the tributaries, most notably from Cattail Creek downstream from the tribal headquarters area and Onion Creek downstream from the sewage lagoons. Arsenic and nickel concentrations in bottom sediment from Onion Creek exceeded the USEPA threshold effects level in a composite sample collected during the habitat assessment in July 2007. Suspended-sediment concentration was estimated in terms of total suspended solids. Overall, Onion and Bennett Creeks were the least turbid, whereas the ephemeral Cattail Creek had the most turbid samples. Aquatic-community data were collected at four sites on the Meskwaki Settlement during the summer of 2007 to provide a baseline biological assessment of stream conditions. This assessment was based on sampling of the fish, benthic macroinvertebrate, and periphyton communities along with physical habitat characteristics. Individual biological metrics were derived from the data collected during the community surveys. These metrics were used to calculate Indexes of Biological Integrity (IBIs). The calculated values from the IBIs provided a numerical value that was used to provide an assessment of the biological condition at each biological sampling site. The fish community samples indicated that all of the sampling sites would be considered in fair condition, with one exception being a collection site on the Iowa River at Highway 49 near Tama, Iowa, which was classified in poor condition. The benthic macroinvertebrate IBI indicated a classification of good for three of the four biological sampling sites, with the Iowa River near Montour, Iowa,
ADHM and the 4d quantum Hall effect
Barns-Graham, Alec; Dorey, Nick; Lohitsiri, Nakarin; Tong, David; Turner, Carl
2018-04-01
Yang-Mills instantons are solitonic particles in d = 4 + 1 dimensional gauge theories. We construct and analyse the quantum Hall states that arise when these particles are restricted to the lowest Landau level. We describe the ground state wavefunctions for both Abelian and non-Abelian quantum Hall states. Although our model is purely bosonic, we show that the excitations of this 4d quantum Hall state are governed by the Nekrasov partition function of a certain five dimensional supersymmetric gauge theory with Chern-Simons term. The partition function can also be interpreted as a variant of the Hilbert series of the instanton moduli space, counting holomorphic sections rather than holomorphic functions. It is known that the Hilbert series of the instanton moduli space can be rewritten using mirror symmetry of 3d gauge theories in terms of Coulomb branch variables. We generalise this approach to include the effect of a five dimensional Chern-Simons term. We demonstrate that the resulting Coulomb branch formula coincides with the corresponding Higgs branch Molien integral which, in turn, reproduces the standard formula for the Nekrasov partition function.
Anomalous Hall effect and Nernst effect in itinerant ferromagnets
International Nuclear Information System (INIS)
Asamitsu, A.; Miyasato, T.; Abe, N.; Fujii, T.; Onose, Y.; Onoda, S.; Nagaosa, N.; Tokura, Y.
2007-01-01
Anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) in many ferromagnetic metals including pure metals, oxides, and calcogenides, are studied to obtain unified understandings of their origins. We show the universal behavior of anomalous Hall conductivity σ xy as a function of longitudinal conductivity σ xx over six orders of magnitude, which is well reproduced by rigorous unified theory assuming both intrinsic and extrinsic contributions to the AHE. ANE is closely related with AHE and gives us further information about the electronic state in the ground state of ferromagnets. The temperature dependence of transverse Peltier coefficient α xy shows almost similar behavior among various ferromagnets and this behavior is expected from a conventional Boltzmann transport theory
Quantum Hall Valley Nematics: From Field Theories to Microscopic Models
Parameswaran, Siddharth
The interplay between quantum Hall ordering and spontaneously broken ``internal'' symmetries in two-dimensional electron systems with spin or pseudospin degrees of freedom gives rise to a variety of interesting phenomena, including novel phases, phase transitions, and topological excitations. I will discuss a theory of broken-symmetry quantum Hall states, applicable to a class of multivalley systems, where the symmetry at issue is a point-group element that combines a spatial rotation with a permutation of valley indices. I will explore its ramifications for the phase diagram of a variety of experimental systems, such as AlAs and Si quantum wells and the surface states of bismuth. I will also discuss unconventional transport phenomena in these phases in the presence of quenched randomness, and the possible mechanisms of selection between degenerate broken-symmetry phases in clean systems. I acknowledge support from NSF DMR-1455366.
Anomalous Hall effect and Nernst effect in itinerant ferromagnets
International Nuclear Information System (INIS)
Miyasato, T.; Abe, N.; Fujii, T.; Asamitsu, A.; Onose, Y.; Onoda, S.; Nagaosa, N.; Tokura, Y.
2007-01-01
Anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) in many ferromagnetic metals including pure metals, oxides, and chalcogenides, are studied to obtain unified understandings of their origins. We show the universal behavior of anomalous Hall conductivity σ xy as a function of longitudinal conductivity σ xx over six orders of magnitude, which is well reproduced by a recent theory assuming both the intrinsic and extrinsic contributions to the AHE. ANE is closely related with AHE and gives us further information about the electronic state in the ground state of ferromagnets. The temperature dependence of transverse Peltier coefficient α xy shows almost similar behavior among various ferromagnets, and this behavior is expected from a conventional Boltzmann transport theory
Quantum Hall effect in quantum electrodynamics
International Nuclear Information System (INIS)
Penin, Alexander A.
2009-01-01
We consider the quantum Hall effect in quantum electrodynamics and find a deviation from the quantum-mechanical prediction for the Hall conductivity due to radiative antiscreening of electric charge in an external magnetic field. A weak dependence of the universal von Klitzing constant on the magnetic field strength, which can possibly be observed in a dedicated experiment, is predicted
Hall devices improve electric motor efficiency
Haeussermann, W.
1979-01-01
Efficiency of electric motors and generators is reduced by radial magnetic forces created by symmetric fields within device. Forces are sensed and counteracted by Hall devices on excitation or control windings. Hall generators directly measure and provide compensating control of anu asymmetry, eliminating additional measurements needed for calibration feedback control loop.
Higher fractions theory of fractional hall effect
International Nuclear Information System (INIS)
Kostadinov, I.Z.; Popov, V.N.
1985-07-01
A theory of fractional quantum Hall effect is generalized to higher fractions. N-particle model interaction is used and the gap is expressed through n-particles wave function. The excitation spectrum in general and the mean field critical behaviour are determined. The Hall conductivity is calculated from first principles. (author)
Experimental and theoretical studies of cylindrical Hall thrusters
International Nuclear Information System (INIS)
Smirnov, Artem; Raitses, Yegeny; Fisch, Nathaniel J.
2007-01-01
The Hall thruster is a mature electric propulsion device that holds considerable promise in terms of the propellant saving potential. The annular design of the conventional Hall thruster, however, does not naturally scale to low power. The efficiency tends to be lower and the lifetime issues are more aggravated. Cylindrical geometry Hall thrusters have lower surface-to-volume ratio than conventional thrusters and, thus, seem to be more promising for scaling down. The cylindrical Hall thruster (CHT) is fundamentally different from the conventional design in the way the electrons are confined and the ion space charge is neutralized. The performances of both the large (9-cm channel diameter, 600-1000 W) and miniaturized (2.6-cm channel diameter, 50-300 W) CHTs are comparable with those of the state-of-the-art conventional (annular) design Hall thrusters of similar sizes. A comprehensive experimental and theoretical study of the CHT physics has been conducted, addressing the questions of electron cross-field transport, propellant ionization, plasma-wall interaction, and formation of the electron distribution function. Probe measurements in the harsh plasma environment of the microthruster were performed. Several interesting effects, such as the unusually high ionization efficiency and enhanced electron transport, were observed. Kinetic simulations suggest the existence of the strong fluctuation-enhanced electron diffusion and predict the non-Maxwellian shape of the electron distribution function. Through the acquired understanding of the new physics, ways for further optimization of this means for low-power space propulsion are suggested. Substantial flexibility in the magnetic field configuration of the CHT is the key tool in achieving the high-efficiency operation
Bulk electron spin polarization generated by the spin Hall current
Korenev, V. L.
2005-01-01
It is shown that the spin Hall current generates a non-equilibrium spin polarization in the interior of crystals with reduced symmetry in a way that is drastically different from the previously well-known equilibrium polarization during the spin relaxation process. The steady state spin polarization value does not depend on the strength of spin-orbit interaction offering possibility to generate relatively high spin polarization even in the case of weak spin-orbit coupling.
Bulk electron spin polarization generated by the spin Hall current
Korenev, V. L.
2006-07-01
It is shown that the spin Hall current generates a nonequilibrium spin polarization in the interior of crystals with reduced symmetry in a way that is drastically different from the previously well-known “equilibrium” polarization during the spin relaxation process. The steady state spin polarization value does not depend on the strength of spin-orbit interaction offering possibility to generate relatively high spin polarization even in the case of weak spin-orbit coupling.
Effet Hall quantique, liquides de Luttinger et charges fractionnaires
Roche, Patrice; Rodriguez, V.; Glattli, D. Christian
We review some basic properties of the Fractional Quantum Hall Effect and particularly address the physics of the edge states. The chiral Luttinger liquid properties of the edges are discussed and probed experimentally using transport measurements. Shot noise measurements, which allow determination of the quasiparticle charge are also discussed. To cite this article: P. Roche et al., C. R. Physique 3 (2002) 717-732.
Mesoscopic spin Hall effect in semiconductor nanostructures
Zarbo, Liviu
The spin Hall effect (SHE) is a name given to a collection of diverse phenomena which share two principal features: (i) longitudinal electric current flowing through a paramagnetic semiconductor or metallic sample leads to transverse spin current and spin accumulation of opposite sign at opposing lateral edges; (ii) SHE does not require externally applied magnetic field or magnetic ordering in the equilibrium state of the sample, instead it relies on the presence of spin-orbit (SO) couplings within the sample. This thesis elaborates on a new type of phenomenon within the SHE family, predicted in our recent studies [Phys. Rev. B 72, 075361 (2005); Phys. Rev. Lett. 95, 046601 (2005); Phys. Rev. B 72, 075335 (2005); Phys. Rev. B 73 , 075303 (2006); and Europhys. Lett. 77, 47004 (2007)], where pure spin current flows through the transverse electrodes attached to a clean finitesize two-dimensional electron gas (2DEG) due to unpolarized charge current injected through its longitudinal leads. If transverse leads are removed, the effect manifests as nonequilibrium spin Hall accumulation at the lateral edges of 2DEG wires. The SO coupling driving this SHE effect is of the Rashba type, which arises due to structural inversion asymmetry of semiconductor heterostructure hosting the 2DEG. We term the effect "mesoscopic" because the spin Hall currents and accumulations reach optimal value in samples of the size of the spin precession length---the distance over which the spin of an electron precesses by an angle pi. In strongly SO-coupled structures this scale is of the order of ˜100 nm, and, therefore, mesoscopic in the sense of being much larger than the characteristic microscopic scales (such as the Fermi wavelength, screening length, or the mean free path in disordered systems), but still much smaller than the macroscopic ones. Although the first theoretical proposal for SHE, driven by asymmetry in SO-dependent scattering of spin-up and spin-down electrons off impurities
Report of experimental hall subworking group
International Nuclear Information System (INIS)
Miyake, K.; Ohama, T.; Takahashi, K.
1982-01-01
The general plan of constructing the TRISTAN e + e - colliding beam experimental halls may be divided into two parts. The first step is to construct two test-experimental halls associated with the 6.5 GeV x 6.5 GeV e + e - accumulator ring, and the second step is to build four experimental halls at the 30 GeV x 30 GeV e + e - TRISTAN main ring. At this workshop, extensive discussions on the detailed design of the four main ring experimental halls have been made. Four experimental areas will be built at the main ring, and two test-experimental halls at the accumulating ring. Among the four areas at the main ring, two will be used for electron-proton possible as well as electron-positron colliding beam experiment. The other two will be used exclusively for e + e - colliding experiments. Only a preliminary design has been made for these four experimental areas. A tentative plan of a larger experimental hall includes a counting and data processing room, a utility room, and a radiation safety control room. Two smaller halls have simpler structure. The figures of the experimental halls are presented. The two test-experimental halls at the accumulator ring will be used to test the detectors for e + e - colliding experiments before the final installation. The utility rooms designed for the halls are used to supply coolant and electric power of superconducting magnets. At the workshop, various ideas concerning the preliminary plan are presented. (Kato, T.)
Nematic and Valley Ordering in Anisotropic Quantum Hall Systems
Parameswaran, S. A.; Abanin, D. A.; Kivelson, S. A.; Sondhi, S. L.
2010-03-01
We consider a multi-valley two dimensional electron system in the quantum Hall effect (QHE) regime. We focus on QHE states that arise due to spontaneous breaking of the valley symmetry by the Coulomb interactions. We show that the anisotropy of the Fermi surface in each valley, which is generally present in such systems, favors states where all the electrons reside in one of the valleys. In a clean system, the valley ordering occurs via a finite temperature Ising-like phase transition, which, owing to the Fermi surface anisotropy, is accompanied by the onset of nematic order. In a disordered system, domains of opposite polarization are formed, and therefore long-range valley order is destroyed, however, the resulting state is still compressible. We discuss the transport properties in ordered and disordered regimes, and point out the possible relation of our results to recent experiments in AlAs [1]. [1] Y. P. Shkolnikov, S. Misra, N. C. Bishop, E. P. De Poortere, and M. Shayegan, Observation of Quantum Hall ``Valley Skyrmions", Phys. Rev. Lett. 95, 068809 (2005)[2] D.A. Abanin, S.A. Parameswaran, S.A. Kivelson and S.L. Sondhi, Nematic and Valley Ordering in Anisotropic Quantum Hall Systems, to be published.
Giant anisotropic magnetoresistance in a quantum anomalous Hall insulator
Kandala, Abhinav; Richardella, Anthony; Kempinger, Susan; Liu, Chao-Xing; Samarth, Nitin
2015-01-01
When a three-dimensional ferromagnetic topological insulator thin film is magnetized out-of-plane, conduction ideally occurs through dissipationless, one-dimensional (1D) chiral states that are characterized by a quantized, zero-field Hall conductance. The recent realization of this phenomenon, the quantum anomalous Hall effect, provides a conceptually new platform for studies of 1D transport, distinct from the traditionally studied quantum Hall effects that arise from Landau level formation. An important question arises in this context: how do these 1D edge states evolve as the magnetization is changed from out-of-plane to in-plane? We examine this question by studying the field-tilt-driven crossover from predominantly edge-state transport to diffusive transport in Crx(Bi,Sb)2−xTe3 thin films. This crossover manifests itself in a giant, electrically tunable anisotropic magnetoresistance that we explain by employing a Landauer–Büttiker formalism. Our methodology provides a powerful means of quantifying dissipative effects in temperature and chemical potential regimes far from perfect quantization. PMID:26151318
The quantum Hall effect helicity
Energy Technology Data Exchange (ETDEWEB)
Shrivastava, Keshav N., E-mail: keshav1001@yahoo.com [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); School of Physics, University of Hyderabad, Hyderabad 500046 (India)
2015-04-16
The quantum Hall effect in semiconductor heterostructures is explained by two signs in the angular momentum j=l±s and g=(2j+1)/(2l+1) along with the Landau factor (n+1/2). These modifications in the existing theories explain all of the fractional charges. The helicity which is the sign of the product of the linear momentum with the spin p.s plays an important role for the understanding of the data at high magnetic fields. In particular it is found that particles with positive sign in the spin move in one direction and those with negative sign move in another direction which explains the up and down stream motion of the particles.
Stuart Hall: An Organic Intellectual
Directory of Open Access Journals (Sweden)
Johanna Fernández Castro
2017-01-01
Full Text Available Stuart Hall (3 February 1932 – 10 February 2014 is acknowledged as one of the founding figures of British Cultural Studies. His extensive academic work on topics such as race, ethnicity and identity reflects his own position as a diasporic intellectual. His contribution to the study of popular culture is determined by the importance of his political character in every social act, his non-deterministic view of Marxism, and is especially determined by his insistence on playing an active role beyond academia in order to contribute to the transformation of hegemonic structures. The following biography aims to give a focused view of his personal history and its direct influence on his key theoretical reflections.
3D Quantum Hall Effect of Fermi Arc in Topological Semimetals
Wang, C. M.; Sun, Hai-Peng; Lu, Hai-Zhou; Xie, X. C.
2017-09-01
The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface has an open Fermi surface, which cannot host the quantum Hall effect. Via a "wormhole" tunneling assisted by the Weyl nodes, the Fermi arcs at opposite surfaces can form a complete Fermi loop and support the quantum Hall effect. The edge states of the Fermi arcs show a unique 3D distribution, giving an example of (d -2 )-dimensional boundary states. This is distinctly different from the surface-state quantum Hall effect from a single surface of topological insulator. As the Fermi energy sweeps through the Weyl nodes, the sheet Hall conductivity evolves from the 1 /B dependence to quantized plateaus at the Weyl nodes. This behavior can be realized by tuning gate voltages in a slab of topological semimetal, such as the TaAs family, Cd3 As2 , or Na3Bi . This work will be instructive not only for searching transport signatures of the Fermi arcs but also for exploring novel electron gases in other topological phases of matter.
Effect of land cover change on runoff curve number estimation in Iowa, 1832-2001
Wehmeyer, Loren L.; Weirich, Frank H.; Cuffney, Thomas F.
2011-01-01
Within the first few decades of European-descended settlers arriving in Iowa, much of the land cover across the state was transformed from prairie and forest to farmland, patches of forest, and urbanized areas. Land cover change over the subsequent 126 years was minor in comparison. Between 1832 and 1859, the General Land Office conducted a survey of the State of Iowa to aid in the disbursement of land. In 1875, an illustrated atlas of the State of Iowa was published, and in 2001, the US Geological Survey National Land Cover Dataset was compiled. Using these three data resources for classifying land cover, the hydrologic impact of the land cover change at three points in time over a period of 132+ years is presented in terms of the effect on the area-weighted average curve number, a term commonly used to predict peak runoff from rainstorms. In the four watersheds studied, the area-weighted average curve number associated with the first 30 years of settlement increased from 61·4 to 77·8. State-wide mapped forest area over this same period decreased 19%. Over the next 126 years, the area-weighted average curve number decreased to 76·7, despite an additional forest area reduction of 60%. This suggests that degradation of aquatic resources (plants, fish, invertebrates, and habitat) arising from hydrologic alteration was likely to have been much higher during the 30 years of initial settlement than in the subsequent period of 126 years in which land cover changes resulted primarily from deforestation and urbanization.
Experiments on Quantum Hall Topological Phases in Ultra Low Temperatures
International Nuclear Information System (INIS)
Du, Rui-Rui
2015-01-01
This project is to cool electrons in semiconductors to extremely low temperatures and to study new states of matter formed by low-dimensional electrons (or holes). At such low temperatures (and with an intense magnetic field), electronic behavior differs completely from ordinary ones observed at room temperatures or regular low temperature. Studies of electrons at such low temperatures would open the door for fundamental discoveries in condensed matter physics. Present studies have been focused on topological phases in the fractional quantum Hall effect in GaAs/AlGaAs semiconductor heterostructures, and the newly discovered (by this group) quantum spin Hall effect in InAs/GaSb materials. This project consists of the following components: 1) Development of efficient sample cooling techniques and electron thermometry: Our goal is to reach 1 mK electron temperature and reasonable determination of electron temperature; 2) Experiments at ultra-low temperatures: Our goal is to understand the energy scale of competing quantum phases, by measuring the temperature-dependence of transport features. Focus will be placed on such issues as the energy gap of the 5/2 state, and those of 12/5 (and possible 13/5); resistive signature of instability near 1/2 at ultra-low temperatures; 3) Measurement of the 5/2 gaps in the limit of small or large Zeeman energies: Our goal is to gain physics insight of 5/2 state at limiting experimental parameters, especially those properties concerning the spin polarization; 4) Experiments on tuning the electron-electron interaction in a screened quantum Hall system: Our goal is to gain understanding of the formation of paired fractional quantum Hall state as the interaction pseudo-potential is being modified by a nearby screening electron layer; 5) Experiments on the quantized helical edge states under a strong magnetic field and ultralow temperatures: our goal is to investigate both the bulk and edge states in a quantum spin Hall insulator under
The integer quantum hall effect revisited
Energy Technology Data Exchange (ETDEWEB)
Michalakis, Spyridon [Los Alamos National Laboratory; Hastings, Matthew [Q STATION, CALIFORNIA
2009-01-01
For T - L x L a finite subset of Z{sup 2}, let H{sub o} denote a Hamiltonian on T with periodic boundary conditions and finite range, finite strength intetactions and a unique ground state with a nonvanishing spectral gap. For S {element_of} T, let q{sub s} denote the charge at site s and assume that the total charge Q = {Sigma}{sub s {element_of} T} q{sub s} is conserved. Using the local charge operators q{sub s}, we introduce a boundary magnetic flux in the horizontal and vertical direction and allow the ground state to evolve quasiadiabatically around a square of size one magnetic flux, in flux space. At the end of the evolution we obtain a trivial Berry phase, which we compare, via a method reminiscent of Stokes Theorem. to the Berry phase obtained from an evolution around an exponentially small loop near the origin. As a result, we show, without any averaging assumption, that the Hall conductance is quantized in integer multiples of e{sup 2}/h up to exponentially small corrections of order e{sup -L/{zeta}}, where {zeta}, is a correlation length that depends only on the gap and the range and strength of the interactions.
The University of Iowa Tractatus Map
Directory of Open Access Journals (Sweden)
David G Stern
2016-12-01
Full Text Available Drawing on recent work on the nature of the numbering system of the Tractatus and Wittgenstein’s use of that system in his composition of the Prototractatus, the paper sets out the rationale for the online tool called The University of Iowa Tractatus Map. The map consists of a website with a front page that links to two separate subway-style maps of the hypertextual numbering system Wittgenstein used in his Tractatus. One map displays the structure of the published Tractatus; the other lays out the structure of the Prototractatus. The site makes available the full text of the German and the two canonical English translations. While we envisage the map as a tool that we would like a wide variety of readers to find helpful, we argue that our website amounts to a radically new edition of Wittgenstein’s early masterpiece, with far-reaching implications for the interpretation of that text. In particular, we claim that our visually compelling presentation of the book’s overall structure delivers on Wittgenstein’s cryptic claim in a letter to his publisher that it is the numbers that “make the book surveyable and clear”.
Direct comparison of fractional and integer quantized Hall resistance
Ahlers, Franz J.; Götz, Martin; Pierz, Klaus
2017-08-01
We present precision measurements of the fractional quantized Hall effect, where the quantized resistance {{R}≤ft[ 1/3 \\right]} in the fractional quantum Hall state at filling factor 1/3 was compared with a quantized resistance {{R}[2]} , represented by an integer quantum Hall state at filling factor 2. A cryogenic current comparator bridge capable of currents down to the nanoampere range was used to directly compare two resistance values of two GaAs-based devices located in two cryostats. A value of 1-(5.3 ± 6.3) 10-8 (95% confidence level) was obtained for the ratio ({{R}≤ft[ 1/3 \\right]}/6{{R}[2]} ). This constitutes the most precise comparison of integer resistance quantization (in terms of h/e 2) in single-particle systems and of fractional quantization in fractionally charged quasi-particle systems. While not relevant for practical metrology, such a test of the validity of the underlying physics is of significance in the context of the upcoming revision of the SI.
Contactless measurement of alternating current conductance in quantum Hall structures
Energy Technology Data Exchange (ETDEWEB)
Drichko, I. L.; Diakonov, A. M.; Malysh, V. A.; Smirnov, I. Yu.; Ilyinskaya, N. D.; Usikova, A. A. [A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Galperin, Y. M. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo (Norway); A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Kummer, M.; Känel, H. von [Laboratorium für Festkörperphysik ETH Zürich, CH-8093 Zürich (Switzerland)
2014-10-21
We report a procedure to determine the frequency-dependent conductance of quantum Hall structures in a broad frequency domain. The procedure is based on the combination of two known probeless methods—acoustic spectroscopy and microwave spectroscopy. By using the acoustic spectroscopy, we study the low-frequency attenuation and phase shift of a surface acoustic wave in a piezoelectric crystal in the vicinity of the electron (hole) layer. The electronic contribution is resolved using its dependence on a transverse magnetic field. At high frequencies, we study the attenuation of an electromagnetic wave in a coplanar waveguide. To quantitatively calibrate these data, we use the fact that in the quantum-Hall-effect regime the conductance at the maxima of its magnetic field dependence is determined by extended states. Therefore, it should be frequency independent in a broad frequency domain. The procedure is verified by studies of a well-characterized p-SiGe/Ge/SiGe heterostructure.
Quantum Hall effect in epitaxial graphene with permanent magnets.
Parmentier, F D; Cazimajou, T; Sekine, Y; Hibino, H; Irie, H; Glattli, D C; Kumada, N; Roulleau, P
2016-12-06
We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications.
On the quantization of Hall currents in presence of disorder
Combes, J; Hislop, P
2005-01-01
We review recent results of two of the authors concerning the quantization of Hall currents, in particular a general quantization formula for the difference of edge Hall conductances in semi-infinite samples with and without a confining wall. We then study the case where the Fermi energy is located in a region of localized states and discuss new regularizations. We also sketch the proof of localization for 2D-models with constant magnetic field with random potential located in a half-plane in two different situations: 1) with a zero potential in the other half plane and for energies away from the Landau levels and 2) with a confining potential in the other half plane and on an interval of energies that covers an arbitrary number of Landau levels.
Quantum Hall effect in epitaxial graphene with permanent magnets
Parmentier, F. D.; Cazimajou, T.; Sekine, Y.; Hibino, H.; Irie, H.; Glattli, D. C.; Kumada, N.; Roulleau, P.
2016-12-01
We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications.
Elastic gauge fields and Hall viscosity of Dirac magnons
Ferreiros, Yago; Vozmediano, María A. H.
2018-02-01
We analyze the coupling of elastic lattice deformations to the magnon degrees of freedom of magnon Dirac materials. For a honeycomb ferromagnet we find that, as happens in the case of graphene, elastic gauge fields appear coupled to the magnon pseudospinors. For deformations that induce constant pseudomagnetic fields, the spectrum around the Dirac nodes splits into pseudo-Landau levels. We show that when a Dzyaloshinskii-Moriya interaction is considered, a topological gap opens in the system and a Chern-Simons effective action for the elastic degrees of freedom is generated. Such a term encodes a phonon Hall viscosity response, entirely generated by quantum fluctuations of magnons living in the vicinity of the Dirac points. The magnon Hall viscosity vanishes at zero temperature, and grows as temperature is raised and the states around the Dirac points are increasingly populated.
Anomalous Hall effect in ZrTe5
Liang, Tian; Lin, Jingjing; Gibson, Quinn; Kushwaha, Satya; Liu, Minhao; Wang, Wudi; Xiong, Hongyu; Sobota, Jonathan A.; Hashimoto, Makoto; Kirchmann, Patrick S.; Shen, Zhi-Xun; Cava, R. J.; Ong, N. P.
2018-05-01
Research in topological matter has expanded to include the Dirac and Weyl semimetals1-10, which feature three-dimensional Dirac states protected by symmetry. Zirconium pentatelluride has been of recent interest as a potential Dirac or Weyl semimetal material. Here, we report the results of experiments performed by in situ three-dimensional double-axis rotation to extract the full 4π solid angular dependence of the transport properties. A clear anomalous Hall effect is detected in every sample studied, with no magnetic ordering observed in the system to the experimental sensitivity of torque magnetometry. Large anomalous Hall signals develop when the magnetic field is rotated in the plane of the stacked quasi-two-dimensional layers, with the values vanishing above about 60 K, where the negative longitudinal magnetoresistance also disappears. This suggests a close relation in their origins, which we attribute to the Berry curvature generated by the Weyl nodes.
The quantum Hall effects: Philosophical approach
Lederer, P.
2015-05-01
The Quantum Hall Effects offer a rich variety of theoretical and experimental advances. They provide interesting insights on such topics as gauge invariance, strong interactions in Condensed Matter physics, emergence of new paradigms. This paper focuses on some related philosophical questions. Various brands of positivism or agnosticism are confronted with the physics of the Quantum Hall Effects. Hacking's views on Scientific Realism, Chalmers' on Non-Figurative Realism are discussed. It is argued that the difficulties with those versions of realism may be resolved within a dialectical materialist approach. The latter is argued to provide a rational approach to the phenomena, theory and ontology of the Quantum Hall Effects.
Piezo Voltage Controlled Planar Hall Effect Devices.
Zhang, Bao; Meng, Kang-Kang; Yang, Mei-Yin; Edmonds, K W; Zhang, Hao; Cai, Kai-Ming; Sheng, Yu; Zhang, Nan; Ji, Yang; Zhao, Jian-Hua; Zheng, Hou-Zhi; Wang, Kai-You
2016-06-22
The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages. Room temperature magnetic NOT and NOR gates are demonstrated based on the piezo voltage controlled Co2FeAl planar Hall effect devices without the external magnetic field. Our demonstration may lead to the realization of both information storage and processing using ferromagnetic materials.
Disorder effect on chiral edge modes and anomalous Hall conductance in Weyl semimetals
International Nuclear Information System (INIS)
Takane, Yositake
2016-01-01
Typical Weyl semimetals host chiral surface states and hence show an anomalous Hall response. Although a Weyl semimetal phase is known to be robust against weak disorder, the effect of disorder on chiral states has not been fully clarified so far. We study the behavior of such chiral states in the presence of disorder and its consequences on an anomalous Hall response, focusing on a thin slab of Weyl semimetal with chiral surface states along its edge. It is shown that weak disorder does not disrupt chiral edge states but crucially affects them owing to the renormalization of a mass parameter: the number of chiral edge states changes depending on the strength of disorder. It is also shown that the Hall conductance is quantized when the Fermi level is located near Weyl nodes within a finite-size gap. This quantization of the Hall conductance collapses once the strength of disorder exceeds a critical value, suggesting that it serves as a probe to distinguish a Weyl semimetal phase from a diffusive anomalous Hall metal phase. (author)
Road safety audit for the intersection of US 59 and IA 9 in Osceola County, Iowa.
2012-03-01
The Iowa Department of Transportation (DOT) requested a road safety audit (RSA) of the US 59/IA 9 intersection in northwestern Iowa, just south of the Minnesota border, to assess intersection environmental issues and crash history and recommend appro...
Contribution of the study of the Hall Effect. Hall Effect of powder products
International Nuclear Information System (INIS)
Cherville, Jean
1961-01-01
This research thesis reports the development of an apparatus aimed at measuring the Hall Effect and the magneto-resistance of powders at room temperature and at the liquid nitrogen temperature. The author also proposes a theoretical contribution to the Hall Effect and reports the calculation of conditions to be met to obtain a correct value for the Hall constant. Results are experimentally verified. The method is then applied to the study of a set of powdered pre-graphitic graphites. The author shows that their Hall coefficient confirms the model already proposed by Mrozowski. The study of the Hall Effect of any kind of powders can thus be performed, and the Hall Effect can therefore be a mean to study mineral and organic compounds, and notably powdered biological molecules [fr
Topologically induced fractional Hall steps in the integer quantum Hall regime of MoS 2
Firoz Islam, SK; Benjamin, Colin
2016-09-01
The quantum magnetotransport properties of a monolayer of molybdenum disulfide are derived using linear response theory. In particular, the effect of topological terms on longitudinal and Hall conductivity is analyzed. The Hall conductivity exhibits fractional steps in the integer quantum Hall regime. Further complete spin and valley polarization of the longitudinal conductivitity is seen in presence of these topological terms. Finally, the Shubnikov-de Hass oscillations are suppressed or enhanced contingent on the sign of these topological terms.
Spin Hall effect by surface roughness
Zhou, Lingjun; Grigoryan, Vahram L.; Maekawa, Sadamichi; Wang, Xuhui; Xiao, Jiang
2015-01-01
induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.
Mesoscopic effects in the quantum Hall regime
Indian Academy of Sciences (India)
. When band mixing between multiple Landau levels is present, mesoscopic effects cause a crossover from a sequence of quantum Hall transitions for weak disorder to classical behavior for strong disorder. This behavior may be of relevance ...
Plasmon Geometric Phase and Plasmon Hall Shift
Shi, Li-kun; Song, Justin C. W.
2018-04-01
The collective plasmonic modes of a metal comprise a simple pattern of oscillating charge density that yields enhanced light-matter interaction. Here we unveil that beneath this familiar facade plasmons possess a hidden internal structure that fundamentally alters its dynamics. In particular, we find that metals with nonzero Hall conductivity host plasmons with an intricate current density configuration that sharply departs from that of ordinary zero Hall conductivity metals. This nontrivial internal structure dramatically enriches the dynamics of plasmon propagation, enabling plasmon wave packets to acquire geometric phases as they scatter. At boundaries, these phases accumulate allowing plasmon waves that reflect off to experience a nonreciprocal parallel shift. This plasmon Hall shift, tunable by Hall conductivity as well as plasmon wavelength, displaces the incident and reflected plasmon trajectories and can be readily probed by near-field photonics techniques. Anomalous plasmon geometric phases dramatically enrich the nanophotonics toolbox, and yield radical new means for directing plasmonic beams.
A system for pulse Hall effect measurements
International Nuclear Information System (INIS)
Orzechowski, T.; Kupczak, R.
1975-01-01
Measuring system for fast Hall-voltage changes in an n-type germanium sample irradiated at liquid nitrogen temperature with a high-energy electron-beam from the Van de Graaff accelerator is described. (author)
AA under construction in its hall
CERN PhotoLab
1980-01-01
The Antiproton Accumulator was installed in a specially built hall. Here we see it at an "early" stage of installation, just a few magnets on the floor, no vacuum chamber at all, but: 3 months later there was circulating beam !
Studies of quantum dots in the quantum Hall regime
Goldmann, Eyal
We present two studies of quantum dots in the quantum Hall regime. In the first study, presented in Chapter 3, we investigate the edge reconstruction phenomenon believed to occur when the quantum dot filling fraction is n≲1 . Our approach involves the examination of large dots (≤40 electrons) using a partial diagonalization technique in which the occupancies of the deep interior orbitals are frozen. To interpret the results of this calculation, we evaluate the overlap between the diagonalized ground state and a set of trial wavefunctions which we call projected necklace (PN) states. A PN state is simply the angular momentum projection of a maximum density droplet surrounded by a ring of localized electrons. Our calculations reveal that PN states have up to 99% overlap with the diagonalized ground states, and are lower in energy than the states identified in Chamon and Wen's study of the edge reconstruction. In the second study, presented in Chapter 4, we investigate quantum dots in the fractional quantum Hall regime using a Hartree formulation of composite fermion theory. We find that under appropriate conditions, the chemical potential of the dots oscillates periodically with B due to the transfer of composite fermions between quasi-Landau bands. This effect is analogous the addition spectrum oscillations which occur in quantum dots in the integer quantum Hall regime. Period f0 oscillations are found in sharply confined dots with filling factors nu = 2/5 and nu = 2/3. Period 3 f0 oscillations are found in a parabolically confined nu = 2/5 dot. More generally, we argue that the oscillation period of dots with band pinning should vary continuously with B, whereas the period of dots without band pinning is f0 .
The fluctuation Hall conductivity and the Hall angle in type-II superconductor under magnetic field
Energy Technology Data Exchange (ETDEWEB)
Tinh, Bui Duc, E-mail: tinhbd@hnue.edu.vn [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam); Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Hoc, Nguyen Quang; Thu, Le Minh [Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam)
2016-02-15
Highlights: • The time-dependent Ginzburg–Landau was used to calculate fluctuation Hall conductivity and Hall angle in type-II superconductor in 2D and 3D. • We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. • The results were compared to the experimental data on YBCO. - Abstract: The fluctuation Hall conductivity and the Hall angle, describing the Hall effect, are calculated for arbitrary value of the imaginary part of the relaxation time in the frame of the time-dependent Ginzburg–Landau theory in type II-superconductor with thermal noise describing strong thermal fluctuations. The self-consistent Gaussian approximation is used to treat the nonlinear interaction term in dynamics. We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. The results are compared with experimental data on high-T{sub c} superconductor.
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Resistive Instabilities in Hall Current Plasma Discharge
International Nuclear Information System (INIS)
Litvak, Andrei A.; Fisch, Nathaniel J.
2000-01-01
Plasma perturbations in the acceleration channel of a Hall thruster are found to be unstable in the presence of collisions. Both electrostatic lower-hybrid waves and electromagnetic Alfven waves transverse to the applied electric and magnetic field are found to be unstable due to collisions in the E X B electron flow. These results are obtained assuming a two-fluid hydrodynamic model in slab geometry. The characteristic frequencies of these modes are consistent with experimental observations in Hall current plasma thrusters
Are tent halls subject to property tax?
Directory of Open Access Journals (Sweden)
Mariusz Macudziński
2016-12-01
Full Text Available The presented publication is a response to currently asked questions and interpretative doubts of taxpayers and tax authorities, namely whether tent halls are subject to property tax. General issues connected with an entity and a subject of taxation of this tax are presented herein. The answer to the question asked is then provided through the qualification of constructions works and the allocation of tent halls in the proper category of the works, with the use of the current law.