947 research outputs found
Grading Students with Significant Disabilities in Inclusive Settings: Teacher Perspectives
The present study describes teacher (K-12) opinions and practices related to grading and
providing modified instruction, assignments, and assessments for students with low-incidence
disabilities in inclusive settings. One hundred and thirty nine teachers working in K-12 inclusive
schools in Arizona and California completed an on-line survey regarding modifications to the
general education curriculum and grading practices. Findings of this study include: (a) general
and special education teachers use different practices and have different preferences for grading
students with disabilities; (b) General and special educators also reported differences in their
level of comfort and training for grading, with special educators feeling more prepared to grade
students with disabilities; (c) Elementary teachers were more likely to accept modified work than
secondary teachers; and (d) Secondary teachers report using modifications to instruction less
frequently than elementary school teachers. Implications and recommendations based on these
findings are reported
Theoretical study of the effect of substituent and backbone conformation on the electronic properties of symmetrically substituted poly(di‐n‐alkylsilanes)
We present the results of ab initio 3‐21G∗ geometry optimizations and valence effective Hamiltonian (VEH) band structure calculations aimed at determining the evolution of the geometric and electronic (ionization potential, electron affinities, and band gaps) properties of all‐trans poly(dimethylsilane), poly(diethylsilane), poly(di‐n‐propylsilane), and poly(di‐n‐butylsilane) when increasing the size of the alkyl group. In the latter polymer, we have also studied the 7/3 conformation, in order to analyze the effect of the backbone conformation on the geometric and electronic structure. The VEH ionization potentials of all‐trans poly(di‐n‐alkylsilanes) are almost equal, and as experimental photoemission data show, only slight differences are appreciated. The band gap decreases in going from poly(di‐n‐butylsilane) to poly(di‐n‐propylsilane) and to poly(diethylsilane), and increases when passing to poly(dimethylsilane), which coincides with experimental evidences on poly(di‐n‐alkylsilanes). The change from all‐trans to 7/3 conformation of poly(di‐n‐butylsilane) implies an increase of both, ionization potential and band gap, in perfect agreement with experimental photoemission and absorption data. The applicability of VEH to deal with poly(di‐n‐alkylsilanes) is [email protected]
Electrical response of β-PVDF in a constant uniaxial strain rate deformation
The microstructure of β-PVDF has great influence on its piezo- and pyroelectric responses. The microstructure of β-PVDF drastically changes upon a mechanical deformation perpendicular to the preferred chain orientation, mainly above the yielding point. The voltage (open-circuit response) developed in β-PVDF films was monitored while the material is subjected to a constant strain rate programFundação para a Ciência e Tecnologia (FCT) -
POCTI/CTM/33501/99
On the relevance of the polar β-phase of poly(vinylidene fluoride) for high performance lithium-Ion battery separators
Separator membranes based on poly(vinylidene fluoride), PVDF, poly(vinylidene fluoride-co-trifluoroethylene), PVDF-TrFE, poly(vinylidene fluoride-co-hexafluropropylene), PVDF-HFP and poly(vinylidene fluoride-co-chlorotrifluoroethylene), PVDF-CTFE were prepared by solvent casting method using N,N-dimethylformamide (DMF) as solvent. In all cases, the same polymer/solvent ratio and solvent evaporation temperature were used. For all membranes, porous microstructure is achieved with a degree of porosity larger than 50%. The β-phase content as well as degree of crystallinity were different for each membrane, which were lower for the co-polymer membranes when compared with PVDF. On the other hand, the observed ionic conductivity values, electrolyte uptake, tortuosity and MacMullin number were similar for all membranes. The electrochemical performance of the separator membranes was evaluated in Li/C–LiFePO4 half-cell configuration showing good cyclability and rate capability for all membranes. Among the all separator membranes, PVDF-TrFE demonstrate the best electrochemical performance, with a discharge capacity value of 87 mAh.g-1 after 50 cycles with a capacity retention of 78 % at 2C.Finally, the correlation between the β-phase content in the membranes and the cycling performance was demonstrated (which was significant at high-C rates): larger β-phase contents, leading higher polarity, facilitates faster lithium ion migration within the separator for similar microstructures.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. The authors thank FEDER funds through the COMPETE 2020 Programme and National Funds through FCT under the projects PTDC/CTM-ENE/5387/2014 and UID/CTM/50025/2013 and grants SFRH/BD/90215/2012 (J.C.D.) and SFRH/BPD/112547/2015 (C.M.C.). The authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) (including the FEDER financial support) and from the Basque Government Industry Department under the ELKARTEK Program. Authors are grateful to the Government of the Basque Country for financial support (Grupos de Investigación, IT718-13). The authors thank Solvay, Timcal and Phostech for kindly supplying the high quality materials.info:eu-repo/semantics/publishedVersio
Effects of electron irradiation on the ferroelectric properties of Langmuir-Blodgett copolymer films
Erratum: Repeated Binge-Like Ethanol Drinking Alters Ethanol Drinking Patterns and Depresses Striatal GABAergic Transmission
Repeated cycles of binge alcohol drinking and abstinence are key components in the development of dependence. However, the precise behavioral mechanisms underlying binge-like drinking and its consequences on striatal synaptic physiology remain unclear. In the present study, ethanol and water drinking patterns were recorded with high temporal resolution over 6 weeks of binge-like ethanol drinking using the ‘drinking in the dark' (DID) protocol. The bottle exchange occurring at the beginning of each session prompted a transient increase in the drinking rate that might facilitate the acquisition of ethanol binge-like drinking. Ethanol drinking mice also displayed a ‘front-loading' behavior, in which the highest rate of drinking was recorded during the first 15 min. This rate increased over weeks and paralleled the mild escalation of blood ethanol concentrations. GABAergic and glutamatergic transmission in the dorsal striatum were examined following DID. Spontaneous glutamatergic transmission and the density of dendritic spines were unchanged after ethanol drinking. However, the frequency of GABAA receptor-mediated inhibitory postsynaptic currents was depressed in medium spiny neurons of ethanol drinking mice. A history of ethanol drinking also increased ethanol preference and altered the acute ethanol effects on GABAergic transmission differentially in dorsolateral and dorsomedial striatum. Together, the study shows that the bottle exchange during DID promotes fast, voluntary ethanol drinking and that this intermittent pattern of ethanol drinking causes a depression of GABAergic transmission in the dorsal striatum
Nucleation of the electroactive γ phase and enhancement of the optical transparency in low filler content poly(vinylidene)/clay nanocomposites
Poly(vinylidene fluoride), PVDF, based nanocomposites with different clays structures have been processed by solvent casting and melt crystallisation. Depending on the melting temperature of the polymer, the nanocomposite recrystalises in the electroactive or non electroactive β-phase of the polymer. This fact is related to the thermal behaviour of the clay. For montmorillonite clay, the full crystallisation of the electroactiveγ-phase occurs for clay contents lower than 0.5 wt%, allowing the nanocomposites to maintain the mechanical properties of the polymer matrix. The electroactivity of the material has been proven by measuring the piezoelectric d33 response of the material. The obtained value of d33 is -7 pC/N, lower than in β-PVDF obtained by mechanical stretching, but still among the largest coefficients obtained for polymers. Further, the optical transmittance in the visible range is strongly enhanced with respect to the transmittance of the pure polymer. Finally, it is demonstrated that the nucleation of the β-phase can be also obtained in other clays, such as in kaolinite and laponite.Fundação para a Ciência e a Tecnologia (FCT) - NANO/NMed-SD/0156/2007, PTDC/CTM/69316/2006, PTDC/CTM-NAN/112574/2009, SFRH/BD/62507/2009.FEDER funds through the "Programa Operacional Factores de Competitividade – COMPETECOST Action MP1003, the ‘European Scientific Network for Artificial Muscles’ (ESNAM)
Activation of mGlu3 Receptors Stimulates the Production of GDNF in Striatal Neurons
Metabotropic glutamate (mGlu) receptors have been considered potential targets
for the therapy of experimental parkinsonism. One hypothetical advantage
associated with the use of mGlu receptor ligands is the lack of the adverse
effects typically induced by ionotropic glutamate receptor antagonists, such as
sedation, ataxia, and severe learning impairment. Low doses of the mGlu2/3
metabotropic glutamate receptor agonist, LY379268 (0.25–3 mg/kg, i.p.)
increased glial cell line-derived neurotrophic factor (GDNF) mRNA and protein
levels in the mouse brain, as assessed by in situ
hybridization, real-time PCR, immunoblotting, and immunohistochemistry. This
increase was prominent in the striatum, but was also observed in the cerebral
cortex. GDNF mRNA levels peaked at 3 h and declined afterwards, whereas GDNF
protein levels progressively increased from 24 to 72 h following LY379268
injection. The action of LY379268 was abrogated by the mGlu2/3 receptor
antagonist, LY341495 (1 mg/kg, i.p.), and was lost in mGlu3 receptor knockout
mice, but not in mGlu2 receptor knockout mice. In pure cultures of striatal
neurons, the increase in GDNF induced by LY379268 required the activation of the
mitogen-activated protein kinase and phosphatidylinositol-3-kinase pathways, as
shown by the use of specific inhibitors of the two pathways. Both in
vivo and in vitro studies led to the conclusion
that neurons were the only source of GDNF in response to mGlu3 receptor
activation. Remarkably, acute or repeated injections of LY379268 at doses that
enhanced striatal GDNF levels (0.25 or 3 mg/kg, i.p.) were highly protective
against nigro-striatal damage induced by
1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in mice, as assessed by
stereological counting of tyrosine hydroxylase-positive neurons in the pars
compacta of the substantia nigra. We speculate that selective mGlu3 receptor
agonists or enhancers are potential candidates as neuroprotective agents in
Parkinson's disease, and their use might circumvent the limitations
associated with the administration of exogenous GDNF
- …