3,742 research outputs found

    Making a Difference in Schools: The Big Brothers Big Sisters School-Based Mentoring Impact Study Executive Summary

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    Serving almost 870,000 youth nationwide, school-based mentoring is one of the fastest growing forms of mentoring in the US today. Making a Difference in Schools presents findings from a landmark random assignment impact study of Big Brothers Big Sisters School-Based Mentoring -- the first national study of this program model. This executive summary highlights nine key findings from the full report and outlines several recommendations for policy and practice

    Making a Difference in Schools: The Big Brothers Big Sisters School-Based Mentoring Impact Study

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    School-based mentoring is one of the fastest growing forms of mentoring in the US today; yet, few studies have rigorously examined its impacts. This landmark random assignment impact study of Big Brothers Big Sisters School-Based Mentoring is the first national study of this program model. It involves 10 agencies, 71 schools and 1,139 9- to 16-year-old youth randomly assigned to either a treatment group of program participants or a control group of their non-mentored peers. Surveys were administered to all participating youth, their teachers and mentors in the fall of 2004, spring of 2005 and late fall of 2005.The report describes the programs and their participants and answers several key questions, including: Does school-based mentoring work? What kinds of mentoring experiences help to ensure benefits? How much do these programs cost? Our findings highlight both the strengths of this program model and its current limitations and suggest several recommendations for refining this promising model-recommendations that Big Brothers Big Sisters agencies across the country are already working to implement

    Multiple Choices After School: Findings from the Extended-Service Schools Initiative

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    In the summer of 2002, every state became eligible to receive federal funds for after-school programs. With this opportunity came the need to make decisions about the goals, design and content of after-school programming -- decisions that will influence which youth participate, what they experience and how they may benefit. This report aims to put policymakers and program operators on firmer ground as they grapple with these decisions; it shares lessons from existing school-based after-school programs

    Light scattering study of the “pseudo-layer” compression elastic constant in a twist-bend nematic liquid crystal

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    The nematic twist-bend (TB) phase, exhibited by certain achiral thermotropic liquid crystalline (LC) dimers, features a nanometer-scale, heliconical rotation of the average molecular long axis (director) with equally probable left- and right-handed domains. On meso to macroscopic scales, the TB phase may be considered as a stack of equivalent slabs or “pseudo-layers”, each one helical pitch in thickness. The long wavelength fluctuation modes should then be analogous to those of a smectic-A phase, and in particular the hydrodynamic mode combining “layer” compression and bending ought to be characterized by an effective layer compression elastic constant Beff and average director splay constant Keff1. The magnitude of Keff1 is expected to be similar to the splay constant of an ordinary nematic LC, but due to the absence of a true mass density wave, Beff could differ substantially from the typical value of ∌10⁶ Pa in a conventional smectic-A. Here we report the results of a dynamic light scattering study, which confirms the “pseudo-layer” structure of the TB phase with Beff in the range 10³–10⁎ Pa. We show additionally that the temperature dependence of Beff at the TB to nematic transition is accurately described by a coarse-grained free energy density, which is based on a Landau-deGennes expansion in terms of a heli-polar order parameter that characterizes the TB state and is linearly coupled to bend distortion of the director

    The potential use of BIM to aid construction waste minimalisation

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    It is widely acknowledged that the construction industry has a major impact on the environment, both in terms of resource consumption and waste production. The construction industry is responsible for producing a whole variety of different onsite wastes; the amount and type of which depends on factors such as the stage of construction, type of construction work, direct or indirect stakeholders’ design change contribution, and practices throughout the project lifecycle. A number of construction waste minimisation (CWM) techniques and tools are currently available to assist contractors to divert waste away from landfill. However, literature reveals that there are insufficient techniques and tools for reducing construction waste during the design and procurement stages. The last few years saw the emergence of Building Information Modelling (BIM) techniques, which can be adopted to improve sustainable construction performance. BIM is a maturing modelling philosophy, which has been applied to several building-related functions such as visualising designs, automating quantity takeoffs, checking compliance with regulations, and scheduling construction processes. Furthermore, BIM, as a real-time interactive and collaborative communication system, has the potential to help project stakeholders to collaboratively attain waste minimisation for sustainable construction and building throughout design, construction and throughout the lifecycle by improving building construction performance. Hence, this paper, which is part of an ongoing doctoral study, explores the potential application of BIM to design out waste. An in-depth literature review was conducted to provide a foundation for the doctoral study that aims to investigate the use of BIM as a potential platform for building design waste minimisation. The paper explores construction waste origins and causes, current waste reduction practices; examines current industry BIM practices and investigates BIM tools for sustainable project construction and management; and identifies the knowledge gaps in existing literature that pave the way for the subsequent data collection stages

    NF-ÎșB as a therapeutic target in cancer

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    The transcription factor nuclear factor (NF)-ÎșB is activated in certain cancers and in response to chemotherapy and radiation. The transcriptional activation of genes associated with cell proliferation, angiogenesis, metastasis and suppression of apoptosis appears to lie at the heart of the ability of NF-ÎșB to promote oncogenesis and cancer therapy resistance. Supporting these findings are recent experiments, performed in vitro and using xenograft models of cancer, which implicate NF-ÎșB inhibition as an important new approach for the treatment of certain hematological malignancies and as an adjuvant approach in combination with chemotherapy or radiation for a variety of cancers. Clinical trials with drugs that block NF-ÎșB are currently in progress with promising results. However, as there is currently no drug that blocks specific NF-ÎșB activation, conclusions drawn with small-molecule inhibitors must be interpreted carefully

    Multilocus sequence types of invasive Corynebacterium diphtheriae isolated in the Rio de Janeiro urban area, Brazil

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    Invasive infections caused by Corynebacterium diphtheriae in vaccinated and non-vaccinated individuals have been reported increasingly. In this study we used multilocus sequence typing (MLST) to study genetic relationships between six invasive strains of this bacterium isolated solely in the urban area of Rio de Janeiro, Brazil, during a 10-year period. Of note, all the strains rendered negative results in PCR reactions for the tox gene, and four strains presented an atypical sucrose-fermenting ability. Five strains represented new sequence types. MLST results did not support the hypothesis that invasive (sucrose-positive) strains of C. diphtheriae are part of a single clonal complex. Instead, one of the main findings of the study was that such strains can be normally found in clonal complexes with strains related to non-invasive disease. Comparative analyses with C. diphtheriae isolated in different countries provided further information on the geographical circulation of some sequence types

    Coherent control of the cooperative branching ratio for nuclear x-ray pumping

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    Coherent control of nuclear pumping in a three level system driven by x-ray light is investigated. In single nuclei, the pumping performance is determined by the branching ratio of the excited state populated by the x-ray pulse. Our results are based on the observation that in ensembles of nuclei, cooperative excitation and decay leads to a greatly modified nuclear dynamics, which we characterize by a time-dependent cooperative branching ratio. We discuss prospects of steering the x-ray pumping by coherently controlling the cooperative decay. First, we study an ideal case with purely superradiant decay and perfect control of the cooperative emission. A numerical analysis of x-ray pumping in nuclear forward scattering with coherent control of the cooperative decay via externally applied magnetic fields is presented. Next, we provide an extended survey of nuclei suitable for our scheme, and propose proof-of-principle implementations already possible with typical M\"ossbauer nuclear systems such as 57Fe^{57}\mathrm{Fe}. Finally, we discuss the application of such control techniques to the population or depletion of long-lived nuclear states.Comment: 11 pages, 8 figures; updated to the published versio
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