725 research outputs found

    Exploring the Role of Mindsets in a Sophomore Level Undergraduate Research Course

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    Several investigations have established the benefits of undergraduate student research experiences, including improved understanding of the research process, development of research skills, improved ability to interpret research, interest in future research experiences, and considering academic/research careers. Unfortunately, some students are intimidated by the research process and avoid such opportunities for growth. Such student perceptions may limit engagement in research, compromising knowledge and skills to critically evaluate research so necessary for clinical practice. The present investigation examined the student mindset perceptions pre- and post-course and student perspectives towards research following an undergraduate research course. A mixed quantitative and qualitative design was employed. While student mindsets were primarily growth based at the outset, students reported gains in perspectives on mindsets and confidence following the course. Qualitative findings further highlight the development of applications to the profession, understanding the research process, research skills, and the challenges of research. Intentional scaffolding of a research course may reduce intimidation and foster positive attitudes towards the importance of research in the discipline

    Frontiers of beam diagnostics in plasma accelerators: measuring the ultra-fast and ultra-cold

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    Advanced diagnostics are essential tools in the development of plasma-based accelerators. The accurate measurement of the quality of beams at the exit of the plasma channel is crucial to optimize the parameters of the plasma accelerator. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement, which is particularly complex due to large energy spread and divergence of the emerging beams, and on femtosecond bunch length measurements

    Impacts of Mid-Level Biofuel Content In Gasoline on SIDI Engine-Out and Tailpipe Particulate Matter Emissions

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    In this work, the influences of ethanol and iso-butanol blended with gasoline on engine-out and post three-way catalyst (TWC) particle size distribution and number concentration were studied using a General Motors (GM) 2.0L turbocharged spark ignition direct injection (SIDI) engine. The engine was operated using the production engine control unit (ECU) with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at 10 selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm. Idle and low-speed / low-load conditions emitted higher total particle numbers than other operating conditions. At idle, the engine-out particulate matter (PM) emissions were dominated by nucleation mode particles, and the production TWC reduced these nucleation mode particles by more than 50%, while leaving the accumulation mode particle distribution unchanged. At an engine load higher than 6 bar net mean effective pressure (NMEP), accumulation mode particles dominated the engine-out particle emissions, and the TWC had little effect. Compared to the baseline gasoline (E0), E10 does not significantly change PM emissions, while E20 and BU12 both reduce PM emissions under the conditions studied. Iso-butanol was observed to impact PM emissions more than ethanol, with up to 50% reductions at some conditions. In this paper, issues related to PM measurement using the FMPS are also discussed. While some uncertainties are due to engine variation, the FMPS must be carefully maintained in order to achieve repeatable measurement results

    Afterschool Programs in America: Origins, Growth, Popularity, and Politics

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    The historical and recent growth of afterschool program (ASPs) in the U.S. is discussed in this article. Particular attention is given to the recent history of social and political influences that have led to growth and current popularity of ASPs. The article begins by reviewing changes in schooling and the labor force that created a supervision gap between the school day of children and work day of parents. This gap contributed to the need for afterschool child care. Next, influences leading to a growing recognition of the significance of school-age childcare for working families and their children, including research on the potential risks of self care and benefits of well-designed ASPs, are described. These discussions are contextualized alongside decades of social and political action and debate over the development of and funding for ASPs in America. Several key factors likely to affect after-school programming in the near future are discussed

    Changes in children’s cognitive development at the Start of School in England 2001–2008.

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    Since 1997, England has seen massive changes in the Early Years including the introduction of an early childhood curriculum, free pre-school education for three-year-olds and local programmes for disadvantaged communities. Many of these initiatives took time to introduce and become established. Beginning in 2001, and each year thereafter until 2008, the authors collected consistent data from thousands of children when they started school at the age of four on a range of variables, chosen because they are good predictors of later success. These included vocabulary, early reading and early mathematics. Children from the same set of 472 state primary schools in England were assessed each year. This paper contributes to the existing studies of educational trends over time by examining the extent to which children's scores on these measures changed over that period; in general, they were found to have remained stable

    Developmental cues and persistent neurogenic potential within an in vitro neural niche

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    <p>Abstract</p> <p>Background</p> <p>Neurogenesis, the production of neural cell-types from neural stem cells (NSCs), occurs during development as well as within select regions of the adult brain. NSCs in the adult subependymal zone (SEZ) exist in a well-categorized niche microenvironment established by surrounding cells and their molecular products. The components of this niche maintain the NSCs and their definitive properties, including the ability to self-renew and multipotency (neuronal and glial differentiation).</p> <p>Results</p> <p>We describe a model <it>in vitro </it>NSC niche, derived from embryonic stem cells, that produces many of the cells and products of the developing subventricular zone (SVZ) and adult SEZ NSC niche. We demonstrate a possible role for apoptosis and for components of the extracellular matrix in the maintenance of the NSC population within our niche cultures. We characterize expression of genes relevant to NSC self-renewal and the process of neurogenesis and compare these findings to gene expression produced by an established neural-induction protocol employing retinoic acid.</p> <p>Conclusions</p> <p>The <it>in vitro </it>NSC niche shows an identity that is distinct from the neurally induced embryonic cells that were used to derive it. Molecular and cellular components found in our <it>in vitro </it>NSC niche include NSCs, neural progeny, and ECM components and their receptors. Establishment of the <it>in vitro </it>NSC niche occurs in conjunction with apoptosis. Applications of this culture system range from studies of signaling events fundamental to niche formation and maintenance as well as development of unique NSC transplant platforms to treat disease or injury.</p

    Longitudinal phase-space manipulation with beam-driven plasma wakefields

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    The development of compact accelerator facilities providing high-brightness beams is one of the most challenging tasks in field of next-generation compact and cost affordable particle accelerators, to be used in many fields for industrial, medical and research applications. The ability to shape the beam longitudinal phase-space, in particular, plays a key role to achieve high-peak brightness. Here we present a new approach that allows to tune the longitudinal phase-space of a high-brightness beam by means of a plasma wakefields. The electron beam passing through the plasma drives large wakefields that are used to manipulate the time-energy correlation of particles along the beam itself. We experimentally demonstrate that such solution is highly tunable by simply adjusting the density of the plasma and can be used to imprint or remove any correlation onto the beam. This is a fundamental requirement when dealing with largely time-energy correlated beams coming from future plasma accelerators

    Focusing of high-brightness electron beams with active-plasma lenses

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    Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices

    Overview of Plasma Lens Experiments and Recent Results at SPARC_LAB

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    Beam injection and extraction from a plasma module is still one of the crucial aspects to solve in order to produce high quality electron beams with a plasma accelerator. Proper matching conditions require to focus the incoming high brightness beam down to few microns size and to capture a high divergent beam at the exit without loss of beam quality. Plasma-based lenses have proven to provide focusing gradients of the order of kT/m with radially symmetric focusing thus promising compact and affordable alternative to permanent magnets in the design of transport lines. In this paper an overview of recent experiments and future perspectives of plasma lenses is reported
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