On binary reflected Gray codes and functions

AbstractThe binary reflected Gray code function b is defined as follows: If m is a nonnegative integer, then b(m) is the integer obtained when initial zeros are omitted from the binary reflected Gray code of m.This paper examines this Gray code function and its inverse and gives simple algorithms to generate both. It also simplifies Conder's result that the jth letter of the kth word of the binary reflected Gray code of length n is 2n-2n-j-1⌊2n-2n-j-1-k/2⌋mod2by replacing the binomial coefficient by k-12n-j+1+12

Making the Significant Significant: A Discourse Analysis Examining the Teacher\u27s Role in Negotiating Meaning of Text with Culturally and Linguistically Diverse Students

This study reports data from a three-month discourse analysis of a fifth-grade teacher`s language used to negotiate meaning of text with linguistically and culturally diverse students. Specifically, I use Gee`s (2005) discourse analysis methodology to examine the teacher`s language-in-use for seven building tasks of language--significance, activities, identities, relationships, politics (the distribution of social goods), connections, and sign systems and knowledge--in a micro level analysis for eight teaching episodes covering reading and/or social studies instruction. In doing so, I conceptualize categories and subcategories of language use for each of the language building tasks. I find that the teacher used instructional language overwhelmingly to build significance (almost two-thirds of the coded data) and that in building significance the teacher used reproduction of meaning (including repetition, paraphrase, and citation), prosodic devices, questions, overt attention, life connection, and adjective labeling. In a macro level of analysis, I examine the content of the meanings the teacher negotiated, and find that situated meanings in her discourse often allude to issues of power that implicate a discourse model of a critical outlook on social studies and social issues that appear in social studies, reading and other texts. I end with a discussion of how these findings might be of practical use for educators and suggestions for future research

Dense Iron Ejecta and Core-collapse Supernova Explosion in the Young Supernova Remnant G11.2-0.3

We present the results of near-infrared spectroscopic observations of dense (\simgt 10$^3$ cm$^{-3}$) iron ejecta in the young core-collapse supernova remnant G11.2-0.3. Five ejecta knots projected to be close to its center show a large dispersion in their Doppler shifts: two knots in the east are blueshifted by more than 1,000 \kms, while three western knots have relatively small blueshifts of 20-60 \kms. This velocity discrepancy may indicate that the western knots have been significantly decelerated or that there exists a systematic velocity difference among the knots. One ejecta filament in the northwestern boundary, on the other hand, is redshifted by \simgt 200 \kms, while opposite filament in the southeastern boundary shows a negligible radial motion. Some of the knots and filaments have secondary velocity components, and one knot shows a bow shock-like feature in the velocity structure. The iron ejecta appear to be devoid of strong emission from other heavy elements, such as S, which may attest to the alpha-rich freezeout process in the explosive nucleosynthesis of the core-collapse supernova explosion close to its center. The prominent bipolar distribution of the Fe ejecta in the northwestern and southeastern direction, along with the elongation of the central pulsar wind nebula in the perpendicular direction, is consistent with the interpretation that the supernova exploded primarily along the northwestern and southeastern direction.Comment: To appear in ApJ Letter

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes I. General Theory and Weak-Gravity Applications

When one splits spacetime into space plus time, the Weyl curvature tensor (vacuum Riemann tensor) gets split into two spatial, symmetric, and trace-free (STF) tensors: (i) the Weyl tensor's so-called "electric" part or tidal field, and (ii) the Weyl tensor's so-called "magnetic" part or frame-drag field. Being STF, the tidal field and frame-drag field each have three orthogonal eigenvector fields which can be depicted by their integral curves. We call the integral curves of the tidal field's eigenvectors tendex lines, we call each tendex line's eigenvalue its tendicity, and we give the name tendex to a collection of tendex lines with large tendicity. The analogous quantities for the frame-drag field are vortex lines, their vorticities, and vortexes. We build up physical intuition into these concepts by applying them to a variety of weak-gravity phenomena: a spinning, gravitating point particle, two such particles side by side, a plane gravitational wave, a point particle with a dynamical current-quadrupole moment or dynamical mass-quadrupole moment, and a slow-motion binary system made of nonspinning point particles. [Abstract is abbreviated; full abstract also mentions additional results.]Comment: 25 pages, 20 figures, matches the published versio

Germplasm Evaluation Program Progress Report No. 19

Breed differences in performance characteristics are an important genetic resource for improving efficiency of beef production. Diverse breeds are required to exploit heterosis and complementarity through crossbreeding and composite populations to match genetic potential with diverse markets, feed resources and climates. Beef producers are under increasing pressure to reduce fat while maintaining or improving tenderness and palatability of products. No single breed excels in all traits of importance to beef production. Previous results have shown that Bos indicus X Bos taurus (e.g., Brahman, Sahiwal and Nellore sired F1 cows out of Hereford and Angus dams) crosses were exceptionally productive and efficient cows, especially in a subtropical environment (e.g., Florida versus Nebraska). However, as the proportion Bos indicus increased, the advantages of Bos indicus crosses were tempered by older age at puberty and reduced meat tenderness. This report presents preliminary results from Cycle V of Germplasm Evaluation Program at the Roman L. Hruska U.S. Meat Animal Research Center (U.S. Meat Animal Research Center) focusing primarily on characterization of some heavy muscled continental European breeds and some tropically adapted breeds compared to Hereford and Angus sired crosses for characteristics of importance in beef production

Household determinants of biocontaminant exposures in Canadian homes

Exposure to biocontaminants, such as dust mites, animal dander, bacteria, and mold, is associated with a range of health effects. This study identified household characteristics associated with indoor biocontaminant loadings in four Canadian cities. Floor dust was collected in 290 Canadian homes in Edmonton, Halifax, Montreal, and Windsor. The dust samples were analyzed for house dust mite allergens (Der f 1 and Der p 1), cat allergen (Fel d 1), cockroach allergen (Bla g 1), beta-(1,3)-D-glucan, and endotoxin. Household information was obtained through questionnaires and home inspections. We performed univariate and multivariate analyses to identify household determinants of biocontaminant loadings and mold odor presence. We observed large regional variations for all biocontaminants, except for cockroach allergen. The ranges of the contaminants measured in loadings and concentrations were similar to that of previous Canadian studies. Household characteristics including presence of carpeting, low floor cleaning frequency, older home age, presence of pets, and indoor relative humidity above 45% were positively associated with the presence of multiple indoor biocontaminants. High floor cleaning frequency and use of dehumidifiers were negatively associated with the presence of multiple indoor biocontaminants. Mold odor was positively associated with older home age, past water damage, and visible mold growth

Life-Space Mobility and Aging in Place

Research on older adults explores the notion of “aging in place”—providing older adults the opportunity to continue to occupy familiar surroundings, to live in their own homes and communities. But oftentimes one’s ability to stay or leave, particularly in old age, depends on the built environment. Mobility is the ability to meet the basic needs to access goods, activities, services, and social interactions as they relate to quality of life. Thus, mobility is essential to older adults due to their limited, or gradually reducing, physical and cognitive abilities. In transportation research, mobility is often regarded in terms of travel behavior and it is measured by the number of outside-home travel. However, in other fields, including public health, it refers to the relative ease and freedom of movement in all of its forms. This study intends to broaden the understanding of the environmental factors on older adults’ mobility in different life spaces, from one’s bedroom to sidewalk, from home to a final destination via walking, public transit and/or driving. We document and examine 1) the ways in which older adults talk about, understand, and make meaning of their experiences and conditions related to life-space mobility and, 2) how these frames of reference guide their ability to be able to age in place. To achieve these aims, we developed a life-space mobility assessment tool and conduct semi-structured interviews with 25 older adults who have participated in home accessibility modification programs in the U.S. Western region. Given that interviewees already have engaged in some level of self-determination to improve their lives at home, we are interested in their life-space mobility and which opportunities they might see to improve their auto sufficiency. Our work provides both a basis and springboard for studying further geographies and discussion about policy initiatives to effectively and equitably address growing mobility disparities

Non-equivalence in old- and new-flagellum daughter cells of a proliferative division in Trypanosoma brucei

Differentiation of Trypanosoma brucei, a flagellated protozoan parasite, between life cycle stages typically occurs through an asymmetric cell division process, producing two morphologically distinct daughter cells. Conversely, proliferative cell divisions produce two daughter cells, which look similar but are not identical. To examine in detail differences between the daughter cells of a proliferative division of procyclic T. brucei we used the recently identified constituents of the flagella connector. These segregate asymmetrically during cytokinesis allowing the new-flagellum and the old-flagellum daughters to be distinguished. We discovered that there are distinct morphological differences between the two daughters, with the new-flagellum daughter in particular re-modelling rapidly and extensively in early G1. This re-modelling process involves an increase in cell body, flagellum, and flagellum attachment zone length and is accompanied by architectural changes to the anterior cell end. The old-flagellum daughter undergoes a different G1 re-modelling, however, despite this there was no difference in G1 duration of their respective cell cycles. This work demonstrates that two daughters of a proliferative division of T. brucei are non-equivalent and enables more refined morphological analysis of mutant phenotypes. We suggest all proliferative divisions in T. brucei and related organisms will involve non-equivalence

Soil nutrient maps of Sub-Saharan Africa: assessment of soil nutrient content at 250 m spatial resolution using machine learning

Spatial predictions of soil macro and micro-nutrient content across Sub-Saharan Africa at 250 m spatial resolution and for 0–30 cm depth interval are presented. Predictions were produced for 15 target nutrients: organic carbon (C) and total (organic) nitrogen (N), total phosphorus (P), and extractable—phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), sodium (Na), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), aluminum (Al) and boron (B). Model training was performed using soil samples from ca. 59,000 locations (a compilation of soil samples from the AfSIS, EthioSIS, One Acre Fund, VitalSigns and legacy soil data) and an extensive stack of remote sensing covariates in addition to landform, lithologic and land cover maps. An ensemble model was then created for each nutrient from two machine learning algorithms

Catastrophic musculoskeletal injuries in thoroughbred racehorses on racetracks in Gauteng- South Africa

The incidence and types of catastrophic musculoskeletal injuries in Thoroughbreds that resulted in euthanasia on selected racetracks in South Africa between 1998 and 2012 were investigated by an observational retrospective investigation. Data from the National Horseracing Authority of Southern Africa for these racetracks were used to calculate incidence rates in Thoroughbreds (n = 114) that sustained catastrophic musculoskeletal injuries during racing that required immediate euthanasia, based on the diagnosis made by the on-site veterinarian as well as on fetlock radiographs and dissections of 53 cadaver limbs of horses that sustained a catastrophic musculoskeletal injury. The proximal sesamoid bones and the distal suspensory ligament were involved in 55.26% of horses; 73.58% of the cadaver limb radiographs were of the left forelimb, 64.15% were closed fractures, and 74.47% had biaxial proximal sesamoid bone fractures. Catastrophic musculoskeletal injuries occurred almost exclusively unilaterally and involved mostly the left front leg. The average incidence rate for a catastrophic musculoskeletal injury occurring in a year at any of the tracks was 0.6 of 1000 starts.The South African Veterinary Foundation and the University of Pretoria’s Research Committee.http://www.jsava.co.zaam2019Companion Animal Clinical StudiesStatistic