395 research outputs found

    A Review of Trends in the Scope of International Scholarship in Middle Level Education, 1989–2019

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    Middle level education as a field of study has expanded during the last thirty years to include a growing, international knowledge base. The primary purpose of this review essay is to highlight trends in the extent to which refereed scholarship in the field of middle level education has reflected international content and perspectives during the last thirty years. To accomplish this task, the authors conducted a chronological review of the major refereed publications of the Association for Middle Level Education, Adolescent Success, and the American Educational Research Association (AERA) Middle Level Education Research (MLER) SIG as well as Middle Grades Research Journal and Middle Grades Review. The authors also examined AERA conference programs between 2010 and 2019 for international content and perspectives in MLER SIG sessions. While the authors’ primary aim was to understand trends in the geographic scope of scholarship in the field, they also gleaned tentative insights about research approaches, theoretical frameworks, and editorial bias that informed a set of recommendations they offered to advance future international work in middle level education. The recommendations include (a) expanding and strengthening worldwide networks of middle grades scholars; (b) building consensus around a middle grades research agenda that has an international dimension; and (c) promoting and engaging in more international scholarship that is theory-driven; uses rigorous, appropriate comparative methodologies; and draws on perspectives from cultures and countries not well represented in the literature

    An International Study of Programs That Prepare Teachers of Young Adolescents

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    This article highlights an upcoming multi-phase, international comparative research study on higher education institution-based programs that prepare teachers of young adolescents. The purpose of this investigation is multifaceted. The investigators aim to (a) document the programmatic and pedagogical features of higher education institution-based programs that prepare teachers of young adolescents in diverse national, regional, cultural, and institutional contexts; (b) identify and describe relationships between higher education institution-based programs that prepare teachers of young adolescents and the socio-cultural, historical, and institutional contexts in which they are embedded; (c) identify and describe patterns of philosophy, programming, and practice evident across higher education institution-based programs that prepare teachers of young adolescents; (d) assess the extent to which higher education institution-based programs that prepare teachers of young adolescents operating in diverse contexts are aligned with the AMLE’s Middle Level Teacher Preparation Standards, and (e) investigate relationships among higher education institution-based programs’ design elements, contexts, implementation processes, and outcomes that prepare teachers of young adolescents

    Re-Examining School Structures of People, Place, and Time to Promote Equity at the Middle Level

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    In 2018 we published a chapter entitled “Middle Grades Schools and Structures” (Ellerbrock et al., 2018a) in Literature Reviews in Support of the Middle Level Education Research Agenda (Mertens et al., 2013). Building on the earlier work of Ellerbrock et al. (2018a), this chapter reviewed literature between 2000 and 2018 that reported on the organizational structures of middle level education settings in the United States of America and Australia. Though the findings highlighted the dearth of research specifically examining the organizational structures of middle level education, the literature examined supported the original three key interconnected themes of people, place, and time (Ellerbrock et al., 2018b) as being key features necessary for the implementation of effective middle schooling practices. In our conclusion, we called for more robust research in this area to guide policy and enact practices across different jurisdictions. At the same time, Bishop and Nagle (2018) noted the many increasing disparities in access to quality education and invited readers to consider how schools can serve all students both equitably and well. Equitable access is first and foremost, but equitable outcomes for all students is paramount. At the time of publication of all of these works, no one could have predicted the significant negative impact of COVID-19 and the resultant exacerbation of the already challenging inequities in education across the globe. However, research over the last five years, and particularly since 2020, has placed a greater focus on policy, system, and grassroots pedagogical changes to bridge this widening gap. In light of this heightened focus, this essay aims to reexamine the three key themes of people, place, and time and, when implemented with integrity, the ways middle grades schools and structures can contribute to creating both developmentally responsive and equitable educational experiences for young adolescent learners

    Measurement of the spatial distribution of mucilage around roots using infrared spectroscopy

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    Mucilage is a mixture of polysaccharides and some lipids which is secreted by the root tip. It facilitates plant nutrient acquisition, stabilizes aggregates, reduces lubrication during plant growth and may increase rhizosphere water content due to its high water holding capacity. So far there is no method to measure the spatial distribution of mucilage in soil around roots. The aim of this study was to test whether infrared spectroscopy can be applied to quantify gradients of mucilage around roots in soil. The C-H to C-O ratio obtained from infrared spectroscopy measurements is an indicator of soil hydrophobicity. As Mucilage turns hydrophobic after drying we hypothesized that mucilage can be detected by the C-H to C-O ratio measured with infrared spectroscopy. We grew maize plants in rhizoboxes filled with quartz silt. Before measurement the planted containers were dried and the roots were removed from soil. Infrared spectroscopy measurements were conducted with a spatial resolution of 50x50 ”m a) radially with increasing distance from the root channel center and b) axially with increasing distance from the root channel tip. In parallel, the contact angle, which also indicates soil hydrophobicity, was quantified in the same locations. Both measurements were additionally conducted on glass slides covered with quartz silt mixed with given concentrations of mucilage. The measurements on the glass slides revealed that the C-H to C-O ratio and the contact angle measurements correlated well with the mucilage concentration in soil. Similarly, the infrared spectroscopy measurements in in the rhizoboxes revealed that radial profiles of mucilage around roots can be quantified: while the C-H to C-O ratio was highest inside the root channels, it decreased to the bulk soil values 0.7 mm in radial direction from the border of the root channel. In axial direction the C-H to C-O ratio did not change significantly, indicating that those compounds causing hydrophobicity of mucilage are not easily degraded by soil microorganisms. We showed that infrared spectroscopy can be applied to measure profiles of mucilage around roots in soil. The radial profiles of mucilage were narrower than those reported for other rhizodeposits which may be explained by the viscosity of mucilage

    The Influence of Radio-Frequency Transmit Field Inhomogeneities on the Accuracy of G-ratio Weighted Imaging

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    G-ratio weighted imaging is a non-invasive, in-vivo MRI-based technique that aims at estimating an aggregated measure of relative myelination of axons across the entire brain white matter. The MR g-ratio and its constituents (axonal and myelin volume fraction) are more specific to the tissue microstructure than conventional MRI metrics targeting either the myelin or axonal compartment. To calculate the MR g-ratio, an MRI-based myelin-mapping technique is combined with an axon-sensitive MR technique (such as diffusion MRI). Correction for radio-frequency transmit (B1+) field inhomogeneities is crucial for myelin mapping techniques such as magnetization transfer saturation. Here we assessed the effect of B1+ correction on g-ratio weighted imaging. To this end, the B1+ field was measured and the B1+ corrected MR g-ratio was used as the reference in a Bland-Altman analysis. We found a substantial bias (≈-89%) and error (≈37%) relative to the dynamic range of g-ratio values in the white matter if the B1+ correction was not applied. Moreover, we tested the efficiency of a data-driven B1+ correction approach that was applied retrospectively without additional reference measurements. We found that it reduced the bias and error in the MR g-ratio by a factor of three. The data-driven correction is readily available in the open-source hMRI toolbox (www.hmri.info) which is embedded in the statistical parameter mapping (SPM) framework

    Methodology paper: a novel phantom setup for commissioning of scanned ion beam delivery and TPS

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    Background: Commissioning of treatment planning systems (TPS) and beam delivery for scanned light ion beams is an important quality assurance task. This requires measurement of large sets of high quality dosimetric data in anthropomorphic phantoms to benchmark the TPS and dose delivery under realistic conditions. Method: A novel measurement setup is described, which allows for an efficient collection of a large set of accurate dose data in complex phantom geometries. This setup allows dose measurements based on a set of 24 small volume ionization chambers calibrated in dose to water and mounted in a holder, which can be freely positioned in a water phantom with various phantoms mounted in front of the water tank. The phantoms can be scanned in a CT and a CT-based treatment planning can be performed for a direct benchmark of the dose calculation algorithm in various situations. Results: The system has been used for acceptance testing in scanned light ion beam therapy at Heidelberg Ion Beam Therapy Center for scanned proton and carbon ion beams. It demonstrated to be useful to collect large amounts of high quality data for comparison with the TPS calculation using various phantom geometries. Conclusion: The setup is an efficient tool for commissioning and verification of treatment planning systems. It is especially suited for dynamic beam delivery, as many data points can be obtained during a single plan delivery, but can be adapted also for other dynamic therapies, like rotational IMRT

    Menge, Verteilung und Zusammensetzung organischer Bodensubstanz auf OberflÀchen von Makroporen in Bt-Horizonten

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    In strukturierten Unterböden können die OberflĂ€chen von Makroporen (AggregatrĂ€nder und Bioporen) in Folge von prĂ€ferenzieller Verlagerung und Stabilisierungsprozessen mit organischer Bodensubstanz (OBS) angereichert sein. Menge, Verteilung und Zusammensetzung der OBS beeinflussen ĂŒber die physiko-chemischen OberflĂ€cheneigenschaften der Makroporen den prĂ€ferenziellen Transport und den Massentransfer zwischen Fließweg und Bodenmatrix. DarĂŒber hinaus fĂŒhrt eine rĂ€umlich diskrete Verteilung von OBS auf OberflĂ€chen von Makroporen zu - in Unterböden wenig erforschten - „hot spots“ mit erhöhten Umsatzraten. Die Analyse der OBS-Zusammensetzung gestattet außerdem RĂŒckschlĂŒsse auf die Landnutzung, so deutet z.B. das Auftreten von Benzonitril und Naphtalen (BN+NA) auf Biomasse-Verbrennung hin. Ziel der Arbeit war die Quantifizierung von organischem Kohlenstoff (Corg) und BN+NA auf intakten Makroporen-OberflĂ€chen in Bt-Horizonten von Parabraunerden aus Löss und Geschiebemergel. Die zweidimensionale (2D), mm-skalige Verteilung von Corg und BN+NA auf verschiedenen Makroporen-Typen wurde mittels Diffuse Reflectance Infrared Fourier Transform (DRIFT) Spektroskopie in Kombination mit Corg-Messungen und Pyrolyse-Feldionisation Massenspektrometrie (Py-FIMS) quantitativ beschrieben. FĂŒr eine Horizont-bezogene Quantifizierung wurden die Porenverteilungen und Porenraum-Geometrien mit Röntgen-Computertomographie (CT) dreidimensional (3D) analysiert. Erhöhte Gehalte an Corg- und BN+NA korrelierten mit dem Auftreten von Ton-haltigen Kutanen und PorenfĂŒllungen. Die Kombination von 2D- und 3D-Daten zeigte Unterschiede in der rĂ€umlichen Verteilung von Corg bzw. OBS sowie von BN+NA in AbhĂ€ngigkeit der Makroporen-Typen und Standorte bzw. bodenbildenden Substrate. Die Ergebnisse tragen zur genaueren Beschreibung von Stoffumsetzungsprozessen und Stofftransporten in strukturierten Unterböden bei und ermöglichen darĂŒber hinaus SchlĂŒsse auf die Genese von Bt-Horizonten in Parabraunerden

    Determining the HPV vaccine schedule for a HIV-infected population in sub Saharan Africa, a commentary

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    Background: Epidemiological studies have established human papillomavirus (HPV) infection as the central cause of invasive cervical cancer (ICC) and its precursor lesions. HIV is associated with a higher prevalence and persistence of a broader range of high-risk HPV genotypes, which in turn results in a higher risk of cervical disease. Recent WHO HPV vaccination schedule recommendations, along with the roll out of HAART at an earlier CD4 count within the female HIV-infected population, may have programmatic implications for sub Saharan Africa. This communication identifies research areas, which will need to be addressed for determining a HPV vaccine schedule for this population in sub Saharan Africa. A review of WHO latest recommendations and the evidence concerning one-dose HPV vaccine schedules was undertaken. Conclusion: For females >= 15 years at the time of first dose and immunocompromised and/or HIV-infected, a 3-dose schedule (0, 1-2, 6 months) is recommended for all three vaccines. There is some evidence that there is similar protection against HPV 16 and 18 infection from a single vaccination than from two or three doses, however there is no cross protection conferred to other genotypes. There is a need for periodic prevalence studies to determine the vaccination coverage of bivalent, quadrivalent and nonavalent vaccine targeted oncogenic HPV genotypes in women with CIN 3 or ICC at national level. In light of the increasing number of sub Saharan HIV-infected girls initiating HAART at a CD4 count above 350 mm(3), there are a number of clinical, virological and public health research gaps to address before a tailored vaccine schedule can be established for this population

    Carbon ion therapy for ameloblastic carcinoma

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    Ameloblastic carcinomas are rare odontogenic tumors. Treatment usually consists of surgical resection and sometimes adjuvant radiation. We report the case of a 71 year-old male patient undergoing carbon ion therapy for extensive local relapse of ameloblastic carcinoma. Treatment outcome was favourable with a complete remission at 6 weeks post completion of radiotherapy while RT-treatment itself was tolerated well with only mild side effects. High dose radiation hence is a potential alternative for patients unfit or unwilling to undergo extensive surgery or in cases when only a subtotal resection is planned or the resection is mutilating
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