1,140 research outputs found

    Improving the School Context of Early Adolescence Through Teacher Attunement to Victimization: Effects on School Belonging

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    The present study examined the effects of teacher attunement to victimization on student perceptions of the bullying culture of their schools as a means of fostering a sense of belonging among early adolescents. Participants (n = 1,264) in sixth grade reported on the frequency that they had been bullied, and teachers were asked to report students who were “picked on.” Teacher attunement represented the correspondence between self-identified and teacher-identified victims. Attunement at the beginning of the school year was related to positive changes in student reports that their peers would intervene in bullying; in turn, sense of belonging was greater when students perceived that their peers would intervene in bullying. Teacher attunement was indirectly related to greater belonging through its impact on student perceptions of the bullying context

    Supporting Online Learning for Advanced Placement Students in Small Rural Schools: Conceptual Foundations and Intervention Components of the Facilitator Preparation Program

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    This paper examines the need for interventions to support students who are taking advanced placement courses in small rural districts and describes the Facilitator Preparation Program (FPP) as a strategy to address this need. Issues in the delivery of Online Distance Education (ODE) in small rural schools are summarized and the conceptual foundations and service delivery considerations of the FPP are outlined. Future research needs are also considered

    Adequate Yearly Progress in Small Rural Schools and Rural Low-Income Schools

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    Adequate yearly progress (AYP) on No Child Left Behind criteria was examined for a randomly selected sample of districts that qualify for the Rural Education Achievement Program (REAP). The sample involved 10% of districts that were eligible for the Small Rural Schools Achievement (SRSA) program and 10% that were eligible for the Rural and Low-income Schools (RLIS) program. Based on district reports, nearly 80% of SRSA schools made AYP, 11% failed, and 11% did not have adequate data. For schools in the RLIS program, districts reported that 65% made AYP, 29% failed, and 6% did not report adequate data. The SRSA and RLIS samples had different patterns for the categories of students that did not make AYP. Also, SRSA and RLIS districts were differentially distributed across the United States. Implications for interventions are discussed

    Elucidating enzymatic polymerisations : Chain-length selectivity of Candida antarctica lipase B towards various aliphatic diols and dicarboxylic acid diesters

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    The sustainable synthesis of polymers is a field with growing interest due to the need of modern society to preserve the environment whilst making used products and food sustainable for the future generations. In this work we investigate the possibility of synthesizing aliphatic polyesters derived from various dicarboxylic acid diesters and diols in a solvent-free reaction system. Candida antarctica lipase B was selected as biocatalyst and its selectivity towards the carbon and ester chain length were elucidated. The selected enzyme was able to synthesize various polyesters combining C4-C10 diesters and C4-C8 diols. All combinations led to monomer conversions above 90% in 24 h with the best number average molecular weights (Mn) being obtained through the combination of dimethyl adipate and 1,8-octanediol leading to a Mn of 7141 Da. Differential scanning calorimetry analysis shows a clear trend with an increase in melting temperature of the polymers that correlates with both the increase of the Mn or of the polymer's constitutional repeat unit carbon chain length. Thermogravimetric analysis and rheology measurements performed on selected samples also confirm the trend showing a variation of the polymer's degradation temperatures and viscosity profiles

    Dynamical response of the Hodgkin-Huxley model in the high-input regime

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    The response of the Hodgkin-Huxley neuronal model subjected to stochastic uncorrelated spike trains originating from a large number of inhibitory and excitatory post-synaptic potentials is analyzed in detail. The model is examined in its three fundamental dynamical regimes: silence, bistability and repetitive firing. Its response is characterized in terms of statistical indicators (interspike-interval distributions and their first moments) as well as of dynamical indicators (autocorrelation functions and conditional entropies). In the silent regime, the coexistence of two different coherence resonances is revealed: one occurs at quite low noise and is related to the stimulation of subthreshold oscillations around the rest state; the second one (at intermediate noise variance) is associated with the regularization of the sequence of spikes emitted by the neuron. Bistability in the low noise limit can be interpreted in terms of jumping processes across barriers activated by stochastic fluctuations. In the repetitive firing regime a maximization of incoherence is observed at finite noise variance. Finally, the mechanisms responsible for spike triggering in the various regimes are clearly identified.Comment: 14 pages, 24 figures in eps, submitted to Physical Review

    The Millstone Grit Group (Pennsylvanian) of the Northumberland-Solway Basin and Alston Block of northern England

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    In the Northumberland–Solway Basin and Alston Block of northern England, some aspects of the stratigraphical and sedimentological relationships between the Millstone Grit Group, the Stainmore Formation (Namurian part of the Yoredale Group) and the Westphalian Pennine Coal Measures Group are uncertain. Also, confusion has resulted from discontinuation of Millstone Grit as a formal lithostratigraphical term north of the Stainmore Basin. This paper presents the evidence for, and describes the nature of, a Kinderscoutian (early Pennsylvanian) abrupt transition from typical ‘Yoredale cyclicity’, characterized by marine limestones in a dominantly siliciclastic succession but including marked fluvial channels, to a sandstone-dominated fluvial succession recognizable as the Millstone Grit Group. Sandbodies present in this region are probably the fluvial feeder systems to many of the fluvio-deltaic successions recorded farther south in the Central Pennine Basin. However, onset of the Millstone Grit Group occurs much earlier to the south, during the Pendleian (late Mississippian), despite the entry of fluvial systems into the Central Pennines Basin from the north. In addition to explaining this counter-intuitive relationship, the paper also recognizes continuation of the fluvial regime into the lowermost part of the Pennine Coal Measures Group

    Engineering Proteinase Inihibitor Genes For Plant Defense Against Predators

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    Small proteinaceous inhibitors (Mr\u3c20,000) of the digestive serine proteinases of animals and microorganisms are found as moderately abundant proteins in storage organs and leaves of many plant genera. The proteins are powerful inhibitors of the digestive enzymes of plant predators and therefore are considered to be part of the array of defensive chemicals of plants. Proteinase inhibitor genes show excellent promise, using DNA technology, to manipulate plant genomes to express these biologically active proteins in order to improve natural defense systems. Members of two unrelated families of serine proteinase inhibitors found in tomato and potato plants, called Inhibitor I (monomer Mr 8000) and Inhibitor II (monomer Mr 12,300), are under both environmental and developmental regulation in different tissues of the plants. Genes coding for wound-inducible Inhibitors I and II have been isolated from both tomato and potato genomes and characterized. Tobacco plants have been transformed with the chimeric genes containing wound-inducible promoters fused with the reporter gene, chloramphenicol acetyl transferase, to assess promoter function and signal transmission. Transacting factors that regulate their expression in response to wounding are also being identified and purified. Intact genes are being employed to transform agriculturally important crop plants to determine their potential usefulness to enhance defensive capabilities of plants against herbivores and pathogens

    The Mineralogical and Chemical Case for Habitability at Yellowknife Bay, Gale Crater, Mars

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    Sediments of the Yellowknife Bay formation (Gale crater) include the Sheepbed member, a mudstone cut by light-toned veins. Two drill samples, John Klein and Cumberland, were collected and analyzed by the CheMin XRD/XRF instrument and the Sample Analysis at Mars (SAM) evolved gas and isotopic analysis suite of instruments. Drill cuttings were also analyzed by the Alpha Particle X-ray Spectrometer (APXS) for bulk composition. The CheMin XRD analysis shows that the mudstone contains basaltic minerals (Fe-forsterite, augite, pigeonite, plagioclase), as well as Fe-oxide/hydroxides, Fe-sulfides, amorphous materials, and trioctahedral phyllosilicates. SAM evolved gas analysis of higher-temperature OH matches the CheMin XRD estimate of ~20% clay minerals in the mudstone. The light-toned veins contain Ca-sulfates; anhydrite and bassanite are detected by XRD but gypsum is also indicated from Mastcam spectral mapping. These sulfates appear to be almost entirely restricted to late-diagenetic veins. The sulfate content of the mudstone matrix itself is lower than other sediments analyzed on Mars. The presence of phyllosilicates indicates that the activity of water was high during their formation and/or transport and deposition (should they have been detrital). Lack of chlorite places limits on the maximum temperature of alteration (likely <100 C). The presence of Ca-sulfates rather than Mg- or Fe-sulfates suggests that the pore water pH was near-neutral and of relatively low ionic strength (although x-ray amorphous Mg-and Fe- sulfates could be present and undetectable by CheMin). The presence of Fe and S in both reduced and oxidized states represents chemical disequilibria that could have been utilized by chemolithoautotrophic biota, if present. When compared to the nearby Rocknest sand shadow mineralogy or the normative mineralogy of Martian soil, both John Klein and Cumberland exhibit a near-absence of olivine and a surplus of magnetite (7-9% of the crystalline component). The magnetite is interpreted as an authigenic product formed when olivine was altered to phyllosilicate. Saponitization of olivine (a process analogous to serpentinization) could have produced H2 in situ. Indeed, early diagenetic hollow nodules ("minibowls") present in the Cumberland mudstone are interpreted by some as forming when gas bubbles accumulated in the unconsolidated mudstone. Lastly, all of these early diagenetic features appear to have been preserved with minimal alteration since their formation, as indicated by the ease of drilling (weak lithification, lack of cementing phases), the presence of 20-30% amorphous material, and the late-stage fracturing with emplacement of calcium sulfate veins and minibowl infills, where they were intersected by veins. A rough estimate of the minimum duration of the lacustrine environment is provided by the minimum thickness of the Sheepbed member. Given 1.5 meters, and applying a mean sediment accumulation rate for lacustrine strata of 1 m/1000 yrs yields a duration of 1,500 years. If the aqueous environments represented by overlying strata are considered, such as Gillespie Lake and Shaler, then this duration increases. The Sheepbed mudstone meets all the requirements of a habitable environment: Aqueous deposition at clement conditions of P, T, pH, Eh and ionic strength, plus the availability of sources of chemical energy

    Educational Barriers of Rural Youth: Relation of Individual and Contextual Difference Variables

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    The purpose of this study was to examine the relation of several individual and contextual difference factors to the perceived educational barriers of rural youth. Data were from a broader national investigation of students’ postsecondary aspirations and preparation in rural high schools across the United States. The sample involved more than 7,000 rural youth in 73 high schools across 34 states. Results indicated that some individual (e.g., African American race/ethnicity) and contextual (e.g., parent education) difference factors were predictive while others were not. Extensions to, similarities, and variations with previous research are discussed. Implications, limitations, and suggestions for future research are also discussed
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