Investigations in Geometry— A Hands-On Course for Grades 6-8 Pre-Service Teachers

This paper describes a geometry course at Virginia Commonwealth University for pre-scrvicc middle school teachers that features hands-on activities, group collaboration, and technology. Details of the topics and activities covered in this course are provided. Feedback from the first group of students to complete the course was gathered throughout the semester and student responses to the class format and topics are also discussed

K-5 Mathematics Specialists\u27 Teaching and Learning about Fractions

This paper describes the fraction-based mathematical activities of two teachers who are part of 3 Mathematics Specialist preparation program. Their work with fractions is traced from two perspectives: 1) their interactions with students as they struggle with fraction concepts; and, 2) their personal journeys to develop deeper understandings of fractions as participants in the Rational Numbers course that is part of their degree program. Through their stories, we gain a better understanding of the complex nature of their work with students and how their participation in the Mathematics Specialist program helps support their work in the school buildings

Nathan Augustus Cobb: The Father of Nematology in the United States; and Nathan Cobb\u27s Publications

Introduction Nathan Augustus Cobb, referred to as the Father of Nematology in the United States (56), was a Renaissance man and a man of humble beginnings. His early life experiences instilled in him the creativity, fortitude, and self reliance that were needed to raise himself alone from age 14, to complete college with little formal pre-college education, receive his Ph.D. in Germany, and go on to found a new discipline of science called Nematology . His scientific and technical accomplishments were impressive, as indicated by the over 250 first-authored manuscripts he produced during his career. He identified over 1000 species of nematodes, including animal parasitic, plant parasitic, free-living, fresh water, and marine forms. He made many innovative technical contributions to Nematology, including: (a) fixation and preservation methods; (b) the Cobb metal mounting slide; (c) adaptation of photographic equipment, light filters, and improvements in the camera lucida for microscopic use with nematodes; and (d) development of the first flotation device for removing nematodes from soil. A self-taught and gifted artist, his illustrations were of the highest quality. He made great contributions in many other areas of science, such as botany and plant pathology, and to the cotton industry as well

Group I aptazymes as genetic regulatory switches

BACKGROUND: Allosteric ribozymes (aptazymes) that have extraordinary activation parameters have been generated in vitro by design and selection. For example, hammerhead and ligase ribozymes that are activated by small organic effectors and protein effectors have been selected from random sequence pools appended to extant ribozymes. Many ribozymes, especially self-splicing introns, are known control gene regulation or viral replication in vivo. We attempted to generate Group I self-splicing introns that were activated by a small organic effector, theophylline, and to show that such Group I aptazymes could mediate theophylline-dependent splicing in vivo. RESULTS: By appending aptamers to the Group I self-splicing intron, we have generated a Group I aptazyme whose in vivo splicing is controlled by exogenously added small molecules. Substantial differences in gene regulation could be observed with compounds that differed by as little as a single methyl group. The effector-specificity of the Group I aptazyme could be rationally engineered for new effector molecules. CONCLUSION: Group I aptazymes may find applications as genetic regulatory switches for generating conditional knockouts at the level of mRNA or for developing economically viable gene therapies

Experiences of workers with post-COVID-19 symptoms can signpost suitable workplace accommodations

The prevalence and multi-system nature of post-COVID-19 symptoms warrants clearer understanding of their work ability implications within the working age population. An exploratory survey was undertaken to provide empirical evidence of the work-relevant experiences of workers recovering from COVID-19. A bespoke online survey based on a biopsychosocial framework ran between December 2020 and February 2021. It collected quantitative ratings of work ability and return-to-work status, qualitative responses about return-to-work experiences, obstacles and recommendations, along with views on employer benefits for making accommodations. A sample of 145 UK workers recovering from COVID-19 was recruited via social media, professional networks and industry contacts. Qualitative data was subject to thematic analysis. Participants were mainly from health/social care (50%) and educational settings (14%). Findings – Just over 90% indicated that they had experienced at least some post-COVID-19 symptoms, notably fatigue and cognitive effects. For 55%, symptoms lasted longer than six months. Only 15% had managed a full return-to-work. Of the 88 who provided workability ratings, just 13 and 18% respectively rated their physical and mental workability as good or very good. Difficulties in resuming work were attributed to symptom unpredictability, their interaction with job demands, managing symptoms and demands in parallel, unhelpful attitudes and expectations. Manager and peer support was reported as variable. Workplace health management characterised by flexible long-term collaborative return-to-work planning, supported bymoreCOVID-centric absence policies and organisational cultures, appear pivotal for sustaining the return-to-work of the large segments of the global workforce affected by post-COVID-19 symptoms

Hachimoji DNA and RNA: A genetic system with eight building blocks

Reported here are DNA and RNA-like systems built from eight (hachi-) nucleotide letters (-moji) that form four orthogonal pairs. This synthetic genetic biopolymer meets the structural requirements needed to support Darwinism, including a polyelectrolyte backbone, predictable thermodynamic stability, and stereoregular building blocks that fit a Schrödinger aperiodic crystal. Measured thermodynamic parameters predict the stability of hachimoji duplexes, allowing hachimoji DNA to double the information density of natural terran DNA. Three crystal structures show that the synthetic building blocks do not perturb the aperiodic crystal seen in the DNA double helix. Hachimoji DNA was then transcribed to give hachimoji RNA in the form of a functioning fluorescent hachimoji aptamer. These results expand the scope of molecular structures that might support life, including life throughout the cosmos

Enhanced flight performance by genetic manipulation of wing shape in Drosophila

Insect wing shapes are remarkably diverse and the combination of shape and kinematics determines both aerial capabilities and power requirements. However, the contribution of any specific morphological feature to performance is not known. Using targeted RNA interference to modify wing shape far beyond the natural variation found within the population of a single species, we show a direct effect on flight performance that can be explained by physical modelling of the novel wing geometry. Our data show that altering the expression of a single gene can significantly enhance aerial agility and that the Drosophila wing shape is not, therefore, optimized for certain flight performance characteristics that are known to be important. Our technique points in a new direction for experiments on the evolution of performance specialities in animals

IS1-related large-scale deletion of chromosomal regions harbouring the oxygen-insensitive nitroreductase gene nfsB causes nitrofurantoin heteroresistance in Escherichia coli

Nitrofurantoin is a broad-spectrum first-line antimicrobial used for managing uncomplicated urinary tract infection (UTI). Loss-of-function mutations in chromosomal genes nfsA, nfsB and ribE of Escherichia coli are known to reduce nitrofurantoin susceptibility. Here, we report the discovery of nitrofurantoin heteroresistance in E. coli clinical isolates and a novel genetic mechanism associated with this phenomenon. Subpopulations with lower nitrofurantoin susceptibility than major populations (hereafter, nitrofurantoin-resistant subpopulations) in two E. coli blood isolates (previously whole-genome sequenced) were identified using population analysis profiling. Each isolate was known to have a loss-of-function mutation in nfsA. From each isolate, four nitrofurantoin-resistant isolates were derived at a nitrofurantoin concentration of 32 mg l-1, and a comparator isolate was obtained without any nitrofurantoin exposure. Genomes of derived isolates were sequenced on Illumina and Nanopore MinION systems. Genetic variation between isolates was determined based on genome assemblies and read mapping. Nitrofurantoin minimum inhibitory concentrations (MICs) of both blood isolates were 64 mg l-1, with MICs of major nitrofurantoin-susceptible populations varying from 4 to 8 mg l-1. Two to 99 c.f.u. per million demonstrated growth at the nitrofurantoin concentration of 32 mg l-1, which is distinct from that of a homogeneously susceptible or resistant isolate. Derived nitrofurantoin-resistant isolates had 11-66 kb deletions in chromosomal regions harbouring nfsB, and all deletions were immediately adjacent to IS1-family insertion sequences. Our findings demonstrate that the IS1-associated large-scale genetic deletion is a hitherto unrecognized mechanism of nitrofurantoin heteroresistance and could compromise UTI management. Further, frequencies of resistant subpopulations from nitrofurantoin-heteroresistant isolates may challenge conventional nitrofurantoin susceptibility testing in clinical settings