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We describe the use of think alouds to examine substantive processes involved in performance on a formative assessment of computational thinking (CT) designed to support self-regulated learning (SR...

Since 1995, ASET has periodically published updates to recommendations for best practices in infection prevention for Neurodiagnostic technologists. The latest installment was accepted in December 2019 for publication in Volume 60, Issue 1, before we had much knowledge or understanding about the SARS-CoV-2, the virus that causes COVID-19. This Technical Tips article is presented as an addendum to the 2020 update and includes important information about infection prevention measures specific to procedure protocols when working with patients positive or under investigation for a highly infectious disease, and when working with patients in general during the current pandemic. All Neurodiagnostic technologists who have direct patient care are responsible for ensuring the use of best practices to prevent the spread of infection.

We present a conceptual framework that leverages synergies between classroom assessment (CA) practices and self-regulated learning (SRL) theory to support academic growth and instruction. We articu...

We examined novice teachers’ beliefs about grading and constructivist teaching approaches. Adapting an existing instrument designed to assess preservice teachers’ grading beliefs that deviate from recommended practices, we administered the Survey of Grading Beliefs to 203 inservice teachers. Exploratory factor analysis resulted in a 3-factor model with a structure similar to that found in prior research; differences between the 2 samples were noted. Teachers who endorsed grading beliefs characterized as “academic enabling” tended to endorse constructivist teaching approaches. To better understand the underlying reasoning of the academic enabling factor, we conducted qualitative research with 6 additional teachers. Results revealed that teachers’ reasons for grading judgments were strategic, analytical, and thoughtful, not haphazard. This study provides empirical evidence about the nature of novice teachers’ beliefs about grading, how they relate to constructivist teaching beliefs, and how they may...

The Peer Enabled Restructured Classroom (PERC) is an instructional innovation developed to address gaps in science, technology, engineering, and math (STEM) in urban high schools. The PERC model changes instruction from teacher led to peer led by bringing peer students into the classroom to lead small-group work. Our study sought to provide empirical evidence in support of the peer-led model as a means of improving STEM learning for tutored students in urban schools. We used propensity score matching to evaluate the innovation's impact on students’ achievement on standardized end-of-course tests in two 9th-grade courses – Integrated Algebra and Biology. Results suggest that by the 2nd year of implementation, enrolment in PERC Biology increased the likelihood of passing. Similar effects were not observed for PERC Integrated Algebra, but when comparing cohorts, we found that the 2nd year was twice as likely to pass as the 1st year. We discuss implications for programme improvement.

Although test scores from similar tests in multiple choice and constructed response formats are highly correlated, equivalence in rankings may mask differences in substantive strategy use. The author used an experimental design and participant think-alouds to explore cognitive processes in mathematical problem solving among undergraduate examinees (N = 64). The study examined the effect of format on mathematics performance and strategy use for male and female examinees given stem-equivalent items. A statistically significant main effect of format on performance was found, with constructed-response items more difficult. The multiple-choice format was associated with more varied strategies, backward strategies, and guessing. Format was found to moderate the effect of problem conceptualization on performance. Results suggest that while for purposes of ranking students on performance, the multiple-choice format may be adequate, for many contemporary educational purposes that seek to provide nuanced informatio...

We investigated examinees' cognitive processes while they solved selected items from the Multistate Bar Exam (MBE), a high-stakes professional certification examination. We focused on ascertaining those mental processes most frequently used by examinees, and the most common types of errors in their thinking. We compared the relationships between different problem-solving processes, errors, and performance, and assessed the degree to which performance was related to correspondence between examinees' and model problem-solving approaches. Participants most commonly solved problems with reference to legal principles and cues presented in problem stems, but also resorted to other mental processes. We found that performance on the MBE is strongly related to domain-specific skill in using legal principles, as well as to domain-general metacognitive skill in organizing thinking. Evidence that would suggest that testwiseness strategies or common-sense reasoning was a source of construct-irrelevant variance on the ...

A micro-Faraday array detector (row of miniature 32 thin film strip electrodes wire bonded to an on-chip integrated capacitance transimpedance amplifier) was tested for use in a multiple collector secondary ion mass spectrometry. The detector was mounted on a standard IMS3f SIMS instrument in place of a microchannel plate. The measurements were performed by using a silicon sample bombarded by either or Cs+ primary ions with or without D2O flooding and detecting secondary ions of Si±, SiH±, O-, SiD−, OD−. A parallel detection of near masses of 29Si and 28SiH or 18O and 16OD was demonstrated at a sensitivity level ∼230 counts/s.

The maintenance of genome stability requires efficient DNA double-stranded break (DSB) repair mediated by the phosphorylation of multiple histone H2AX molecules near the break sites. The phosphorylated H2AX (gammaH2AX) molecules form foci covering many megabases of chromatin. The formation of gamma-H2AX foci is critical for efficient DNA damage response (DDR) and for the maintenance of genome stability, however, the mechanisms of protein organization in foci is largely unknown. To investigate the nature of gammaH2AX foci formation, we analyzed the distribution of gammaH2AX and other DDR proteins at DSB sites using a variety of techniques to visualize, expand and partially disrupt chromatin. We report here that gammaH2AX foci change composition during the cell cycle, with proteins 53BP1, NBS1 and MRE11 dissociating from foci in G(2) and mitosis to return at the beginning of the following G(1). In contrast, MDC1 remained colocalized with gamma-H2AX during mitosis. In addition, while gammaH2AX was found to span large domains flanking DSB sites, 53BP1 and NBS1 were more localized and MDC1 colocalized in doublets in foci. H2AX and MDC1 were found to be involved in chromatin relaxation after DSB formation. Our data demonstrates that the DSB repair focus is a heterogeneous and dynamic structure containing internal complexity.

The Survey of Assessment Beliefs (SAB) was developed to measure teacher candidates' perceptions about grading practices. After piloting, the SAB was administered to 222 teacher candidates at a large northeastern urban university, along with a measure of their beliefs about teaching. Candidates were found to support many grading practices not recommended by professional standards. Support for grading practices that deviate from professional recommendations was positively associated with support for constructivist approaches. Significant differences were found in grading and teaching attitudes between elementary and secondary education teacher candidates. Teacher candidates became more moderate in endorsing nonstandard grading practices following coursework in classroom assessment but on average maintained a tendency to approve academically enabling grading practices. This study provides empirical evidence about possible areas of tension between constructivist learning theory and principles of educational m...

Many U.S. students must pass a standards-based exit exam to earn a high school diploma. The degree to which exit exams and state standards properly signal to students their preparedness for postsecondary schooling has been questioned. The alignment of test scores with college grades for students at the University of Arizona (n = 2,667) who took the Arizona high school exams was ascertained in this study. The pass/fail signal accuracy of test scores varied depending on subject: The writing cut score was well aligned with collegiate performance, the reading cut score was below expectations, and the mathematics cut score was set quite rigorously. High school content and performance standards might not be as diluted as prior research has suggested.

Current advances in cancer biology have identified major pathways involved in tumorigenesis. The association of DNA damage with premalignant stages of tumor progression, genome instability and further oncogenic transformation opens the possibility of using common DNA damage markers for early cancer detection, prediction, prognosis, therapeutics and possibly for cancer prevention. Perhaps the most sensitive DNA damage marker is gammaH2AX formation in the chromatin flanking the free DNA double-stranded ends in double-strand breaks (DSBs) and eroded telomeres, both present during oncogenic transformation. Our group and others found elevated endogenous levels of in various human cancer cell lines, premalignant lesions and solid tumors. These data suggest that increased DNA damage is a general characteristic of cancer development. GammaH2AX-based assay can be applied to human biopsies, aspirates and, possibly, to mononuclear cells of the peripheral blood. We propose that detection of gammaH2AX could benefit for the early cancer screening and to ascertain the efficiency of clinical treatment involving chemo- and radiotherapeutic protocols.

The recent years have witnessed a rapid accumulation of experimental data showing that ionizing radiation elicits a plethora of biological effects in unirradiated cells receiving bystander signals from hit cells. This so-called radiation-induced bystander effect (RIBE) manifests in various ways including changes in gene expression, genetic and epigenetic alterations, as well as increases in cell transformation and cell death. Our group and others found that DNA double-stranded breaks (DSBs), directly measured by the gamma-H2AX focus formation assay, accumulate in bystander cells in a number of experimental systems such as human cultured cells, human three-dimensional tissue models and in mice. In addition, we recently found that various other sources of cell stress, including media from cancerous cells resulted in a DNA damage response (DDR) in normal human cells that is reminiscent of RIBE. These results suggest that the RIBE may be part of a more general stress response, however, the molecular mechanism underpinning the formation of DNA DSBs in bystander cells is still unclear. This extra view points to some possibilities that might explain why DDR in human cells can be observed under bystander conditions.

Laboratory of Molecular Pharmacology; Center for Cancer Research; NationalCancer Institute; National Institutes of Health; Bethesda, Maryland USA*Correspondence to: William M Bonner; NIH/NCI/CCR/LMP; Bldg. 37 Rm. 5050AMSC 4255; 9000 Rockville Pike; Bethesda, Maryland 20892 USA; Tel.:301.496.5942; Fax: 301.402.0752; Email: wmbonner@helix.nih.gov Received 06/18/03; Accepted 06/18/03Previously published online as a CB&T Paper in Press at:http://www.landesbioscience.com/journals/cbt/toc.php?volume=2&issue=3

Histone H2A.X is a replication-independent histone H2A isoprotein species that is encoded by a transcript alternatively processed at the 3' end to yield two mRNAs: a 0.6-kb mRNA ending with the stem-loop structure characteristic of the mRNAs for replication-linked histone species, and a second, polyadenylated 1.6-kb mRNA ending about 1 kb further downstream (C. Mannironi, W. M. Bonner, and C. L. Hatch, Nucleic Acids Res. 17:9113-9126, 1989). Of the two, the 0.6-kb H2A.X stem-loop mRNA predominates in many cell lines, indicating that the presence of two types of mRNA may not completely account for the replication independence of H2A.X protein synthesis. The ambiguity is resolved by the finding that the level of the 0.6-kb H2A.X mRNA is only weakly downregulated during the inhibition of DNA replication and only weakly upregulated during the inhibition of protein synthesis, while the levels of other replication-linked mRNAs are strongly down- or upregulated under these two conditions. Analysis of the nuclear transcription rates of specific H2A genes showed that while the rates of transcription of replication-linked H2A genes decreased substantially during the inhibition of DNA synthesis and increased substantially during the inhibition of protein synthesis, the rate of H2A.X gene transcription decreased slightly under both conditions. These differences in transcriptional regulation between the H2A.X gene and other replication-linked histone genes are sufficient to account for the differences in regulation of their respective stem-loop mRNAs.

In general, as the quantity of frother and/or coal collector is increased, so too, does the flotation of the undesired pyrite. The problem is particularly serious with oily reagents. For some coals, however, a collector, such as fuel oil, is required to achieve a high coal recovery. This requires a compromise between the competing desires of a high coal recovery and a high pyrite rejection. This study gives the quantitative effect of reagent dosage on coal and pyrite floatability and details several means of minimizing pyrite floatability during coal flotation. The effect of fuel oil on coal flotation is especially interesting in that the flotation process changes from froth flotation to emulsion or agglomerative flotation as the amount of oil is increased. This phenomenon provides an additional method of rejecting pyritic sulfur.

Progress in understanding the origins of prostate cancer is hindered by a lack of relevant in vivo human models, but in a recent article, Zhang et al.1 demonstrate the utility of ex vivo culturing of slices of normal prostate tissue obtained from surgeries. The prostate is composed primarily of two cell types, basal and luminal cells, but prostate cancer is commonly believed to originate from the luminal cells because tumor biopsies exhibit luminal cell expansion coupled with an absence of basal cells.2 However, both cell lineages may harbor potential cancer cells.3,4 Zhang et al.1 report that the basal and luminal epithelial cells exhibit substantially different responses to DNA damage. In basal cells, phosphorylation of H2AX and KAP1 was found to be dependent on ATM and to follow kinetics considered typical of a robust DNA damage response, while these phosphorylations were attenuated in the luminal cells. On the other hand, DNA-PK was phosphorylated in both cell types, suggesting that DNA-PK-dependent repair was activated in the luminal cells despite the diminished H2AX and KAP1 responses. Since these studies cannot reveal what specifically is occurring at the DNA level in response to DNA damaging agents, it is not known what qualitative or quantitative differences might exist in the repaired DNA in these two cell types. In previous work, the same laboratories presented evidence that the subdued H2AX response may be due to lower H2AX levels in the luminal cells.5 since H2AX is considered essential for the rapid phase of DNA DSB rejoining, but expendable for DSB rejoining itself,6 one might expect differences in the rates of DSB repair in these two cell types. Also, there is evidence that the presence of H2AX and γ-H2AX foci in a cell may make for more accurate DNA rejoining at DSBs,7 supporting the notion that DNA repair in luminal cells may be less accurate than in basal cells. On the other hand, in spite of exhibiting radiation hypersensitivity, defective class-switch recombination, and male sterility, the H2AX-null mouse has a normal physical phenotype, indicating that rapid DSB repair may not be essential for organisms living in unstressed circumstances. Cells taken from the H2AX-null mouse and induced to proliferate in culture exhibit multiple genome defects,5 but how the lack of H2AX affects genome stability in non- or slowly proliferating cells is still not clear. In summary, the studies by Zhang et al.1 suggest that DNA damage in the prostate is processed by different pathways in different cell types under as close to in vivo conditions as can be currently obtained experimentally, and offer a plausible hypothesis for differential mutability of different cell types. Being able to elucidate and compare DNA repair in different cell and tissue types in normal human tissues will help enlighten the processes of oncogenesis in humans.

It has been documented widely that when the generation times of eucaryotic cells are lengthened by slowing the rate of protein synthesis, the duration of the chromosome cycle (S, G2, and M phases) remains relatively invariant. Paradoxically, when the growth of exponentially growing cultures of CHO cells is partially inhibited with inhibitors of protein synthesis, the immediate effect is a proportionate reduction in the rate of total protein, histone protein, and DNA synthesis. However, on further investigation it was found that over the next 2 h the rates of histone protein and DNA synthesis recover, in some cases completely to the uninhibited rate, while the synthesis rates of other proteins do not recover. We called this process chromosome cycle compensation. The amount of compensation seen in CHO cell cultures can account quantitatively for the relative invariance in the length of the chromosome cycle (S, G2, and M phases) reported for these cells. The mechanism for this compensation involves a specific increase in the levels of histone mRNAs. An invariant chromosome cycle coupled with a lengthening growth cycle must result in a disproportionate lengthening of the G1 phase. Thus, these results suggest that chromosome cycle invariance may be due more to specific cellular compensation mechanisms rather than to the more usual interpretation involving a rate-limiting step for cell cycle progression in the G1 phase.

During the replication of chromatin, the syntheses of the histone protein and DNA components are closely coordinated but not totally linked. The interrelationships of total protein synthesis, histone protein synthesis, DNA synthesis, and mRNA levels have been investigated in Chinese hamster ovary cells subjected to several different types of inhibitors in several different temporal combinations. The results from these studies and results reported elsewhere can be brought together into a consistent framework which combines the idea of autoregulation of histone biosynthesis as originally proposed by W. B. Butler and G. C. Mueller (Biochim. Biophys. Acta 294:481-496, 1973] with the presence of basal histone synthesis and the effects of protein synthesis on DNA synthesis. The proposed framework obviates the difficulties of Butler and Mueller's model and may have wider application in understanding the control of cell growth.

Histones constitute the protein core around which DNA is coiled to form the basic structural unit of the chromosome known as the nucleosome. Because of the large amount of new histone needed during chromosome replication, the synthesis of histone and DNA is regulated in a complex manner. During RNA transcription and DNA replication, the basic nucleosomal structure as well as interactions between nucleosomes must be greatly altered to allow access to the appropriate enzymes and factors. The presence of extensive and varied post-translational modifications to the otherwise highly conserved histone primary sequences provides obvious opportunities for such structural alterations, but despite concentrated and sustained effort, causal connections between histone modifications and nucleosomal functions are not yet elucidated.

Factors in the extracellular environment, specifically hypertonic or acidic growth media, are shown to alter the modification of histones in several cell lines. For histone 2A, changes in modification were visible in the mass pattern and were found to be primarily changes in phosphorylation. The increased modification of the core histones was quickly reversed when cells were returned to normal medium.