Synchrotron X-ray study of polycrystalline wurtzite Zn1-xMgxO (0 <= x <= 0.15): Evolution of crystal structure and polarization

The effect of Mg-substitution on the crystal structure of wurtzite ZnO is presented based on synchrotron X-ray diffraction studies of polycrystalline Zn1-xMgxO (0 <= x <= 0.15). Increase in Mg concentration results in pronounced c-axis compression of the hexagonal lattice, and in diminution of the off-center cation displacement within each tetrahedral ZnO4 unit. Going from ZnO to Zn0.85Mg0.15O, significant changes in the ionic polarization are observed (-5.6 to -4.8 uC/cm2), despite only subtle increments in the cell volume (~0.03 %) and the ab-area dimension (~0.1 %). The optical properties of the samples have also been characterized and the band gap changes from 3.24 eV (ZnO) to 3.35 eV (Zn0.85Mg0.15O).Comment: 9 Pages, Word + PDF, 3 Figures, 1 Tabl

Situating Food Insecurity in a Historic Albuquerque Community: The Whorled Relationship between Food Insecurity and Place

This article examines conceptualizations of the relationship between food insecurity and place. We use an ethnographically inspired and community-engaged approach to situate our analysis of fluid dynamics at work in a community with high levels of food insecurity. We propose that the relationship between place and people’s experience of food insecurity is recursive, dialectical, and “whorled.” This relationship reflects complex, interconnected, and multidimensional processes with consequences for the health of residents. Our research demonstrates the key nature of the health-place nexus by exploring how food insecurity articulates with place in unexpected ways that go beyond discussions of food, food environments, food access, food practices or food systems that have become common in the literature

Differential modes of orphan subunit recognition for the WRB/CAML complex

A large proportion of membrane proteins must be assembled into oligomeric complexes for function. How this process occurs is poorly understood, but it is clear that complex assembly must be tightly regulated to avoid accumulation of orphan subunits with potential cytotoxic effects. We interrogated assembly in mammalian cells by using the WRB/CAML complex, an essential insertase for tail-anchored proteins in the endoplasmic reticulum (ER), as a model system. Our data suggest that the stability of each subunit is differentially regulated. In WRB’s absence, CAML folds incorrectly, causing aberrant exposure of a hydrophobic transmembrane domain to the ER lumen. When present, WRB can correct the topology of CAML both in vitro and in cells. In contrast, WRB can independently fold correctly but is still degraded in the absence of CAML. We therefore propose that there are at least two distinct regulatory pathways for the surveillance of orphan subunits in the mammalian ER

Tuning magnetic frustration on the diamond lattice of the A-site magnetic spinels CoAl2−x_{2-x}Gax_xO4_4: Lattice expansion and site disorder

The spinels CoB$_2$O$_4$ with magnetic Co$^{2+}$ ions on the diamond lattice A site can be frustrated because of competing near-neighbor ($J_1$) and next-near neighbor ($J_2$) interactions. Here we describe attempts to tune the relative strengths of these interactions by substitution on the non-magnetic B-site. The system we employ is CoAl$_{2-x}$Ga$_x$O$_4$, where Al is systematically replaced by the larger Ga, ostensibly on the B site. As expected, Ga substitution expands the lattice, resulting in Co atoms on the A-site being pushed further from one other and thereby weakening magnetic interactions. In addition, Ga distributes between the B and the A site in a concentration dependent manner displacing an increasing amount of Co from the A site with increasing $x$. This increased inversion, which is confirmed by neutron diffraction studies carried out at room temperature, affects magnetic ordering very significantly, and changes the nature of the ground state. Modeling of the magnetic coupling illustrates the complexity that arises from the cation site disorder.Comment: 9 pages, 10 figure

Standards of Best Practices Environmental Education & Interpretation Professionals

This document provides guidelines about the knowledge and skills needed to provide effective Environmental Education and Interpretation (EE&I) experiences in the state of Nevada. Effective experiences not only further the mission of the organization but also inspire understanding, appreciation, and stewardship of Southern Nevada’s environment. Standards of Best Practices for Nevada Environmental Education & Interpretation (NEE&I) Professionals is a guide for providers working at public lands, nature centers, museums, zoos, aquaria, schools, and all nature and heritage-rich places. It is designed to help NEE&I providers develop and implement the highest quality experiences for all possible audiences. It is a tool for NEE&I providers to use as they develop new experiences, deliver programs, or evaluate the effectiveness of the experience. Because EE&I experiences come in many forms, not every part of this document will apply to every EE&I experience

Verification of Anderson superexchange in MnO via magnetic pair distribution function analysis and ab initio theory

We present a temperature-dependent atomic and magnetic pair distribution function (PDF) analysis of neutron total scattering measurements of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. The known antiferromagnetic ground-state structure fits the low-temperature data closely with refined parameters that agree with conventional techniques, confirming the reliability of the newly developed magnetic PDF method. The measurements performed in the paramagnetic phase reveal significant short-range magnetic correlations on a ∼1  nm length scale that differ substantially from the low-temperature long-range spin arrangement. Ab initio calculations using a self-interaction-corrected local spin density approximation of density functional theory predict magnetic interactions dominated by Anderson superexchange and reproduce the measured short-range magnetic correlations to a high degree of accuracy. Further calculations simulating an additional contribution from a direct exchange interaction show much worse agreement with the data. The Anderson superexchange model for MnO is thus verified by experimentation and confirmed by ab initio theory

Indices of Body Composition and Repeatability of Residual Feed Intake in Growing Columbia Ewes Fed the Same Diet

Residual feed intake (RFI), an efficiency measurement based upon the difference in expected and actual feed intake, is used to improve production efficiency of livestock. The purpose of this study was to evaluate the repeatability of ewe RFI measured for two consecutive years, and to investigate the relationship between indices of body composition in yearling ewes and RFI. Two trials, using the same Columbia ewe lambs (n = 17) were conducted in consecutive years (2014, 2015) using the same diet. RFI was calculated for each ewe each year. RFI did not differ (P = 0.77) between years. Each year, ewes were separated into RFI classes (LOW (efficient); MOD (average); HIGH (inefficient)). In 2014, ewe lamb performance did not differ among classes (P &gt; 0.3). In 2015, dry matter intake was greater for HIGH ewes (P &lt; 0.0002). Ribeye area (REA; cm2) and backfat thickness (BF; cm) were measured by ultrasound on day 0 (start of trial), 17, and 45 (end of trial) in 2015 and used to calculate estimates of final body composition. RFI classification did not affect REA or BF (P &gt; 0.25). There was a trend for whole-body muscle mass to differ among RFI classes (P = 0.09), but no other body composition estimates were affected. Results suggest that RFI is repeatable; however, indices of body composition seem to be independent of RFI in Columbia ewes fed the same diet under similar conditions

Smoothness of de nite unitary eigenvarieties at critical points

We compute an upper bound for the dimension of the tangent spaces at classical points of certain eigenvarieties associated with definite unitary groups, especially including the so-called critically refined cases. Our bound is given in terms of “critical types” and when our bound is minimized it matches the dimension of the eigenvariety. In those cases, which we explicitly determine, the eigenvariety is necessarily smooth and our proof also shows that the completed local ring on the eigenvariety is naturally a certain universal Galois deformation ring