Genetic Diversity in Swallenia alexandrae (Poaceae, Chloridoideae), a Narrow Endemic From the Eureka Dunes (Inyo County, California)

Swallenia alexandrae, Eureka Valley dune grass (Poaceae, Chloridoideae), is a narrow endemic known only from three localities in the Eureka Valley and adjoining Saline Range in the northern portion of Death Valley National Park (Inyo County, California). This monotypic genus is listed as endangered by the U.S. Fish and Wildlife Service and as rare by the California Department of Fish and Game. Genetic diversity within and among populations of S. alexandrae was studied with randomly amplified polymorphic DNA. A single polymorphic band was detected in approximately one quarter of all individuals sampled. This result indicates very low genetic diversity in S. alexandrae. There is no evidence of private alleles and very little partitioning of genetic diversity between populations. These results are discussed in relation to conservation concerns for S. alexandrae

Quantum magnetism in the rare-earth pyrosilicates

2021 Spring.Includes bibliographical references.In recent years, both physicists and non-physicists have shown immense interest in the burgeoning field of quantum computing and the possible applications a quantum computer could be used for [1]. However, current quantum computers suffer from issues of decoherence: where the quantum state used for computation is broken by external noise. A new possible avenue for quantum computation would be to use systems that are intrinsically protected from some level of noise, such as topologically protected states. Topological states are inherently protected from small perturbations due to their topological nature. However, to exploit this feature of topologically protected systems more experimental realizations are needed to better understand the underlying mechanisms. This has motivated a surge in interest of condensed matter systems with topologically protected states, such as the quantum spin liquid or fractional quantum Hall systems. A current focus in the subfield of quantum magnetism has focused on using the anisotropic exchange properties of the rare-earth (La - Lu) ions to find quantum spin liquid states, such as the Kitaev spin liquid that is predicted for systems exhibiting a honeycomb lattice. The Kitaev model is an exactly solvable model with a quantum spin liquid ground state, allowing for precise comparison between experiment and theory. Currently, no system has been rigorously proven to be a Kitaev spin liquid but developing our understanding of the underlying physical mechanisms in these systems may allow for the "engineering" of systems that are likely to be Kitaev spin liquids. The desire to understand the underlying mechanisms for quantum spin liquids and other quantum ground states led to the study of the three-honeycomb rare-earth pyrosilicate compounds discussed in this dissertation. The first compound, Yb2Si2O7, is a quantum dimer magnet system with the first evidence for a rare-earth based triplon Bose-Einstein condensate. Inelastic neutronscattering, specific heat, and ultrasound velocity measurements showed a characteristic (for triplon Bose-Einstein condensates) dome in the field-temperature phase diagram and provided evidence for predominantly isotropic exchange, something that is not typically expected for rare-earth systems. Following this work on Yb2Si2O7, our focused turned to two of the Er3+ rare-earth pyrosilicates. The first of these Er3+-based pyrosilicates measured was D-Er2Si2O7. Previous work on D-Er2Si2O7 discovered a highly anisotropic g-tensor, an antiferromagnetic ground state, and modeled some of the magnetic field induced transitions via Monte-Carlo simulations [2]. Our work followed up on this with AC susceptibility, powder inelastic neutron scattering, and powder neutron diffraction measurements to further investigate the ground state of this quantum magnet. Through this we discovered that the system enters an antiferromagnetic state with the spins almost aligned along the previously determined local Ising-axis [2]. The inelastic neutron scattering spectrum show a gapped excitation at zero field - consistent with Ising-like exchange. Transverse field AC susceptibility shows a change in the susceptibility at 2.65 T. These signatures indicate that D-Er2Si2O7 exhibits predominantly Ising-like exchange and that a transition can be induced by a field applied transverse to the Ising axis. This allows for the possibility of D-Er2Si2O7 bein g a new experimental realization of the Transverse Field Ising Model (TFIM). The TFIM is a simple, anisotropic exchange, theoretically tractable model exhibiting quantum criticality with few experimental examples, making new experimental examples of this model highly desired. These intriguing results on D-Er2Si2O7 and Yb2Si2O7 led to an interest in the polymorph formed at lower synthesis temperatures, C-Er2Si2O7, which happens to be isostructural to Yb2Si2O7. Measurements of the neutron diffraction, specific heat, and magnetization/susceptibility in this system allowed for us to determine that C-Er2Si2O7 magnetically orders at 2.3 K into an antiferromagnetic Néel state. While this is the expected ground state for an isotropically exchange coupled honeycomb system, C-Er2Si2O7 does not form a "perfect" honeycomb lattice and it is interesting that C-Er2Si2O7 magnetically orders while Yb2Si2O7 does not. Understanding the ground state for C-Er2Si2O7 will allow for bettering our understanding of Yb2Si2O7 and rare-earth quantum magnet ground states by comparing the properties of the two systems. Overall, the work on these three compounds required numerous experimental techniques, models, and theoretical understanding. It is my hope that the preliminary understanding for these three pyrosilicates will motivate future work within the rare-earth pyrosilicate family and provide a family of rare-earth quantum magnets that can be studied to improve our understanding of novel quantum states

A Survey: To Determine the Reorganization Characteristics and Capabilities of Six Selected School Districts in Holt County, Nebraska

School district reorganization is an ongoing process intended to enable school districts to best satisfy educational needs. The Problem of attaining the best organizational arrangement is a long-standing dilemma. The Process that may best provide a solution is a study of a district\u27s needs and resources

Break up of returning plasma after the 7 June 2011 filament eruption by Rayleigh-Taylor instabilities

A prominence eruption on 7 June 2011 produced spectacular curtains of plasma falling through the lower corona. At the solar surface they created an incredible display of extreme ultraviolet brightenings. The aim is to identify and analyze some of the local instabilities which produce structure in the falling plasma. The structures were investigated using SDO/AIA 171A and 193A images in which the falling plasma appeared dark against the bright coronal emission. Several instances of the Rayleigh-Taylor instability were investigated. In two cases the Alfven velocity associated with the dense plasma could be estimated from the separation of the Rayleigh-Taylor fingers. A second type of feature, which has the appearance of self-similar branching horns, is also discussed.Comment: 6 pages, 7 figures, submitted A&A. Movies are at http://www.mps.mpg.de/data/outgoing/innes/arcs_movie.avi and http://www.mps.mpg.de/data/outgoing/innes/horns_movie.av

Electronic controller for reciprocating rotary crystallizer

An electronic controller for a reciprocating rotary crystallizer is described. The heart of this system is the electronic timer circuit. A schematic along with a detailed description of its operation is given

Personality factors related to sobriety for participants in Alcoholics Anonymous

The effects of extraversion introversion (E-I), locus of control (LC), and attitudes towards a Power greater than ourselves (PGO) on number of relapse episodes, number of times in treatment, and length of sobriety were explored. Volunteers from local Alcoholics Anonymous (A.A.) groups (n=72) and two inpatient treatment centers (n=52) completed the Eysenck Personality Inventory, the Rotter Locus of Control measure, a questionnaire designed by the author to assess attitudes concerning the concept adopted by A.A. of a PGO, and a brief self report survey. Results of the multiple regression analyses exploring the effects of E-I, LC, and PGO indicated the 3 factors accounted for: 17.69% of the variance in number of relapses, with a significant (12\u3c.0001) PGO effect; 5.01% of the variance in number of times in treatment, with (j\u3c.08) and LC (E\u3c.11) trends when PGO was removed; and 0.67% of the variance in length of sobriety

Private Standards, Handling and Hygiene in Fruit Export Supply Chains: A Preliminary Evaluation of the Economic Impact of Parallel Standards

With the emergence of private food safety and quality standards in developed countries fruit exporting countries in the developing world face increasing constraints to access markets in the rich industrialised countries in the North. Producers in the South have no alternative as to make the necessary investments on farms and in pack houses to comply with the requirements of these food quality and safety standards. The export of fresh fruit is an important component of South African agricultural exports, with citrus fruit exported to markets such as Europe being of particular importance. This paper reports selected results from a large research project into the impact of private standard compliance on the quality of the fruit and the returns to farmers. The research process involved a multi-disciplinary analysis of Agricultural Economics and Microbiology / Plant pathology as we analysed the dynamics of the citrus export supply chain from the farms in South Africa to the end consumer in Europe. Sampled fruit containers were followed through the whole supply chain which allowed us to provide an exposé of the behaviour of the different actors in the citrus supply chain and obtain some evidence of poor handling and hygiene standards by means of a comparison of the experimental observations with various relevant components of the EurepGAP control points and compliance criteria for fruit and vegetables. Observations suggest that these standards are adequately applied to the production and handling of fruit at the farm and pack house levels while on the other hand the subsequent stages (mainly after the importing harbour in Europe) of the fruit supply chain are seemingly not subjected to the same strict requirements laid out for producers, leading to fruit quality deterioration and financial losses for producers. This constitutes clear parallel standards in terms of fruit safety and quality standards between upstream and downstream sections of the supply chain and questions thus the purpose of the standards and the financial return for producers making large investments to comply with these privately introduced standards.International Relations/Trade,