Charm Meson Mixing: An Experimental Review

We review current experimental results on charm mixing and CP violation. We survey experimental techniques, including time-dependent, time-independent, and quantum-correlated measurements. We review techniques that use a slow pion tag from D*+ --> pi+ D0 + c.c. decays and those that do not, and cover two-body and multi-body D0 decay modes. We provide a summary of D-mixing results to date and comment on future experimental prospects at the LHC and other new or planned facilities.Comment: 53 pages, 29 figures, 8 table

Improved Current Densities in MgB2 By Liquid-Assisted Sintering

Polycrystalline MgB2 samples with GaN additions were prepared by reaction of Mg, B, and GaN powders. The presence of Ga leads to a low melting eutectic phase which allowed liquid phase sintering and produces plate-like grains. For low-level GaN additions (5% at. % or less), the critical transition temperature, Tc, remained unchanged and in 1T magnetic field, the critical current density, Jc was enhanced by a factor of 2 and 10, for temperatures of \~5K and 20K, respectively. The values obtained are approaching those of hot isostatically pressed samples.Comment: 12 pages, 1 table, 4 figures, accepted in Applied Physics Letter

Online Instruction in Higher Education: Promising, Research-based, and Evidence-based Practices

The purpose of this study was to review the research literature on online learning to identify effective instructional practices. We narrowed our scope to empirical studies published 2013-2019 given that studies earlier than 2013 had become quickly outdated because of changes in online pedagogies and technologies. We also limited our search to studies with undergraduate and graduate students, application of an empirical methodological design, and descriptions of methodology, data analysis, and results with sufficient detail to assure verifiability of data collection and analysis. Our analysis of the patterns and trends in the corpus of 104 research studies led to identification of five themes: course design factors, student support, faculty pedagogy, student engagement, and student success factors. Most of the strategies with promising effectiveness in the online environment are the same ones that are considered to be effective in face-to-face classrooms including the use of multiple pedagogies and learning resources to address different student learning needs, high instructor presence, quality of faculty-student interaction, academic support outside of class, and promotion of classroom cohesion and trust. Unique to the online environment are user-friendly technology tools, orientation to online instruction, opportunities for synchronous class sessions, and incorporation of social media. Given the few studies utilizing methodological designs from which claims of causality can be made or meta-analyses could be conducted, we identified only faculty feedback as an evidence-based practice and no specific intervention that we could identify as research-based in online instruction

High- and low energy nonthermal X-ray emission from the cluster of galaxies A 2199

We report the detection of both soft and hard excess X-ray emission in the cluster of galaxies A 2199, based upon spatially resolved spectroscopy with data from the BeppoSAX, EUVE and ROSAT missions. The excess emission is visible at radii larger than 300 kpc and increases in strength relative to the isothermal component. The total 0.1-100 keV luminosity of this component is 15 % of the cluster luminosity, but it dominates the cluster luminosity at high and low energies. We argue that the most plausible interpretation of the excess emission is an inverse Compton interaction between the cosmic microwave background and relativistic electrons in the cluster. The observed spatial distribution of the non-thermal component implies that there is a large halo of cosmic ray electrons between 0.5-1.5 Mpc surrounding the cluster core. The prominent existence of this component has cosmological implications, as it is significantly changing our picture of a clusters's particle acceleration history, dynamics between the thermal and relativistic media, and total mass budgets.Comment: Accepted for publication in Astrophysical Journal, Letter

Relevance of the IES/NSF Protocol to Identification of Evidence-Based Practices

The Institute of Education Sciences (IES) and the National Science Foundation (NSF) issued common guidelines that provide a protocol by which the use of particular methodological designs in a line of research inquiry provides evidence for each successive step in the process of bringing any given instructional intervention into practice. Our purpose was to determine if research on two widely used literacy instruction approaches has been conducted at each methodological stage in the IES/NSF protocol and is relevant to identifying the approach as an evidence-based practice. We applied the IES/NSF pipeline-of-evidence guidelines to assess whether practices touted as having a research base for effectiveness have emerged from an accumulation of empirical evidence and identification of conceptual or theoretical frameworks. In mapping the six steps of the IES/NSF protocol onto the shared book reading and reciprocal teaching studies that had met What Works Clearinghouse evidence standards, we found that only reciprocal teaching involved research at each stage in the protocol and only reciprocal teaching was identified as an evidence-based instructional approach by the What Works Clearinghouse. Our results indicate that the IES/NSF pipeline-of-evidence protocol offers a productive approach to identifying evidence-based practices. The different trajectories of research on reciprocal teaching and shared book reading indicates that research at each stage in the protocol is important to the development of an instructional approach that ultimately demonstrates effectiveness in improving student learning outcomes

Identifying Evidence-Based Educational Practices: Which Research Designs Provide Findings that Can Influence Social Change?

We conducted this conceptual study to determine if the Institute of Education Sciences/National Science Foundation pipeline of evidence guidelines could be applied as a protocol that researchers could follow in establishing evidence of effective instructional practices. To do this, we compared these guidelines, new drug development process, and our own research on major methodological designs and found that they show remarkable consistency in the process by which types of studies intended to answer different research questions build a body of evidence for practice, whether that practice is in the instructional environment or health care environment. However, none of the protocols offers a constellation of studies at each stage that would be essential for movement to the next stage or the indicators of quality for each type of study. The goal of this effort is to develop consensus in the educational research community about a pipeline of evidence protocol that provides educators with confidence that the instructional practices they employ have a high likelihood of success and will enable a positive impact on the student’s learning and, in the broader context, the student’s ability to contribute to society