23,925 research outputs found
Examining and contrasting the cognitive activities engaged in undergraduate research experiences and lab courses
While the positive outcomes of undergraduate research experiences (UREs) have
been extensively categorized, the mechanisms for those outcomes are less
understood. Through lightly structured focus group interviews, we have
extracted the cognitive tasks that students identify as engaging in during
their UREs. We also use their many comparative statements about their
coursework, especially lab courses, to evaluate their experimental
physics-related cognitive tasks in those environments. We find there are a
number of cognitive tasks consistently encountered in physics UREs that are
present in most experimental research. These are seldom encountered in lab or
lecture courses, with some notable exceptions. Having time to reflect and fix
or revise, and having a sense of autonomy, were both repeatedly cited as key
enablers of the benefits of UREs. We also identify tasks encountered in actual
experimental research that are not encountered in UREs. We use these findings
to identify opportunities for better integration of the cognitive tasks in UREs
and lab courses, as well as discussing the barriers that exist. This work
responds to extensive calls for science education to better develop students'
scientific skills and practices, as well as calls to expose more students to
scientific research.Comment: 11 pages, 3 figure
Overview of the Tevatron Collider Complex: Goals, Operations and Performance
For more than two decades the Tevatron proton-antiproton collider was the
centerpiece of the world's high energy physics program. The collider was
arguably one of the most complex research instruments ever to reach the
operation stage and is widely recognized for numerous physics discoveries and
for many technological breakthroughs. In this article we outline the historical
background that led to the construction of the Tevatron Collider, the strategy
applied to evolution of performance goals over the Tevatron's operational
history, and briefly describe operations of each accelerator in the chain and
achieved performance.Comment: Includes modifications suggested by reviewer
Advances in large-diameter liquid encapsulated Czochralski GaAs
The purity, crystalline perfection, and electrical properties of n- and p-type GaAs crystals grown by the liquid encapsulated Czochralski (LEC) technique are evaluated. The determination of the dislocation density, incidence of twinning, microstructure, background purity, mobility, and minority carrier diffusion length is included. The properties of the LEC GaAs crystals are generally comparable to, if not superior to those of small-diameter GaAs material grown by conventional bulk growth techniques. As a result, LEC GaAs is suitable for application to minority carrier devices requiring high-quality and large-area substrates
High purity low dislocation GaAs single crystals
Recent advances in GaAs bulk crystal growth using the LEC (liquid encapsulated Czochralski) technique are described. The dependence of the background impurity concentration and the dislocation density distribution on the materials synthesis and growth conditions were investigated. Background impurity concentrations as low as 4 x 10 to the 15th power were observed in undoped LEC GaAs. The dislocation density in selected regions of individual ingots was very low, below the 3000 cm .3000/sq cm threshold. The average dislocation density over a large annular ring on the wafers fell below the 10000/sq cm level for 3 inch diameter ingots. The diameter control during the program advanced to a diameter variation along a 3 inch ingot less than 2 mm
Value added or misattributed? A multi-institution study on the educational benefit of labs for reinforcing physics content
Instructional labs are widely seen as a unique, albeit expensive, way to
teach scientific content. We measured the effectiveness of introductory lab
courses at achieving this educational goal across nine different lab courses at
three very different institutions. These institutions and courses encompassed a
broad range of student populations and instructional styles. The nine courses
studied had two key things in common: the labs aimed to reinforce the content
presented in lectures, and the labs were optional. By comparing the performance
of students who did and did not take the labs (with careful normalization for
selection effects), we found universally and precisely no added value to
learning from taking the labs as measured by course exam performance. This work
should motivate institutions and departments to reexamine the goals and conduct
of their lab courses, given their resource-intensive nature. We show why these
results make sense when looking at the comparative mental processes of students
involved in research and instructional labs, and offer alternative goals and
instructional approaches that would make lab courses more educationally
valuable.Comment: Accepted to Phys Rev PE
Conjugative transfer frequencies of mef(A)-containing Tn1207.3 to macrolide-susceptible Streptococcus pyogenes belonging to different emm types
The aim of this study was to examine the gene transfer potential of mef(A)-containing Tn120.3 to macrolide-susceptible Streptococcus pyogenes belonging to different emm types. Using the filter mating technique, Tn1207.3 was transferred by conjugation to 23 macrolide-susceptible recipients representing 11 emm types. PCR analysis confirmed the presence of the mef(A) gene and the comEC junction regions of the Tn1207.3 insertion in resultant transconjugants. Significant variation was found in the transfer frequency of Tn1207.3 to different Strep. pyogenes strains, and this phenomenon may contribute to the differences in mef(A) frequency observed among clinical isolates. Significance and Impact of the Study: The spread of antimicrobial resistance among pathogenic bacteria is an important problem, but the mechanisms of horizontal transfer between strains and species are often poorly understood. For instance, little is known on how macrolide resistance spreads between strains of the human pathogen Strep. pyogenes and why certain strains more commonly display resistance than others. Here, we show that Strep. pyogenes strains vary greatly in their ability to acquire a transposon encoding macrolide resistance by horizontal gene transfer in vitro. These data provide a novel insight into the transfer of antibiotic resistance between bacterial strains and offer an explanation for the differences in the frequency of resistance determinates and resistance seen among clinical isolates. © 2014 The Authors Letters in Applied Microbiology
Recommended from our members
Risk perception of antimicrobial resistance by infection control specialists in Europe: a case-vignette study
Background
Using case-vignettes, we assessed the perception of European infection control (IC) specialists regarding the individual and collective risk associated with antimicrobial resistance (AMR) among inpatients.
Methods
In this study, sixteen case-vignettes were developed to simulate hospitalised patient scenarios in the field of AMR and IC. A total of 245 IC specialists working in different hospitals from 15 European countries were contacted, among which 149 agreed to participate in the study. Using an online database, each participant scored five randomly-assigned case-vignettes, regarding the perceived risk associated with six different multidrug resistant organisms (MDRO). The intra-class correlation coefficient (ICC), varying from 0 (poor) to 1 (perfect), was used to assess the agreement for the risk on a 7-point Likert scale. High risk and low/neutral risk scorers were compared regarding their national, organisational and individual characteristics.
Results
Between January and May 2017, 149 participants scored 655 case-vignettes. The perceptions of the individual (clinical outcome) and collective (spread) risks were consistently lower than other MDRO for extended spectrum beta-lactamase producing Enterobacteriaceae cases and higher for carbapenemase producing Enterobacteriaceae (CPE) cases. Regarding CPE cases, answers were influenced more by the resistance pattern (93%) than for other MDRO. The risk associated with vancomycin resistant Enterococci cases was considered higher for the collective impact than for the individual outcome (63% vs 40%). The intra-country agreement regarding the individual risk was globally poor varying from 0.00 (ICC: 0–0.25) to 0.51 (0.18–0.85). The overall agreement across countries was poor at 0.20 (0.07–0.33). IC specialists working in hospitals preserved from MDROs perceived a higher individual (local, p = 0.01; national, p < 0.01) and collective risk (local and national p < 0.01) than those frequently exposed to bacteraemia. Conversely, IC specialists working in hospitals with a high MDRO clinical burden had a decreased risk perception.
Conclusions
The perception of the risk associated with AMR varied greatly across IC specialists and countries, relying on contextual factors including the epidemiology. IC specialists working in high prevalence areas may underestimate both the individual and collective risks, and might further negatively promote the MDRO spread. These finding highlight the need to shape local and national control strategies according to risk perceptions and contextual factors
Recommended from our members
Capacity of English NHS hospitals to monitor quality in infection prevention and control using a new European framework: a multilevel qualitative analysis
Objective:(1) To assess the extent to which current English national regulations/policies/guidelines and local hospital practices align with indicators suggested by a European review of effective strategies for infection prevention and control (IPC); (2) to examine the capacity of local hospitals to report on the indicators and current use of data to inform IPC management and practice.
Design
A national and local-level analysis of the 27 indicators was conducted. At the national level, documentary review of regulations/policies/guidelines was conducted. At the local level data collection comprised: (a) review of documentary sources from 14 hospitals, to determine the capacity to report performance against these indicators; (b) qualitative interviews with 3 senior managers from 5 hospitals and direct observation of hospital wards to find out if these indicators are used to improve IPC management and practice.
Setting
2 acute English National Health Service (NHS) trusts and 1 NHS foundation trust (14 hospitals).
Participants
3 senior managers from 5 hospitals for qualitative interviews.
Primary and secondary outcome measures
As primary outcome measures, a ‘Red-Amber-Green’ (RAG) rating was developed reflecting how well the indicators were included in national documents or their availability at the local organisational level. The current use of the indicators to inform IPC management and practice was also assessed. The main secondary outcome measure is any inconsistency between national and local RAG rating results.
Results
National regulations/policies/guidelines largely cover the suggested European indicators. The ability of individual hospitals to report some of the indicators at ward level varies across staff groups, which may mask required improvements. A reactive use of staffing-related indicators was observed rather than the suggested prospective strategic approach for IPC management.
Conclusions
For effective patient safety and infection prevention in English hospitals, routine and proactive approaches need to be developed. Our approach to evaluation can be extended to other country settings
Monetary costs of agitation in older adults with Alzheimer's disease in the UK: prospective cohort study
While nearly half of all people with Alzheimer's disease (AD) have agitation symptoms every month, little is known about the costs of agitation in AD. We calculated the monetary costs associated with agitation in older adults with AD in the UK from a National Health Service and personal social services perspective
- …