285 research outputs found
Institutional ableism and the politics of inclusive education: an ethnographic study of an inclusive high school
This thesis explores some of the ways inequalities are maintained and legitimated\ud
within the context of reforms that are focused on them. In particular, it looks at the\ud
continued marginalization of disabled students in U.S. public Schools. Central to this\ud
is the development of the concept of institutional ableism, the idea that there are\ud
discriminatory structures and practices and uninterrogated beliefs embedded within\ud
society that subvert even the most well intentioned policies. This thesis is an attempt\ud
to examine this oppression on both the macro and micro-political levels.\ud
Chapter three looks at how institutional ablism works at a policy level. Using a\ud
detailed deconstruction of the Individuals with Disabilities Education Improvement\ud
act 2004 (IDEA), the first chapter examines the ways in which institutional ableism\ud
subverts the stated intentions of IDEA to maintain disabled peoples marginalised\ud
status within the education system. The chapter further deconstructs IDEA, focusing\ud
on its attempts to address the disproportionate representation of minority students in\ud
special education.\ud
The Final three chapters look at the micro-politics of school level reforms. Based on a\ud
year long ethnography in an inclusive school in the western United States. Chapter\ud
four focuses on the relationship between teachers and disabled students examining the\ud
mechanisms used to maintain inequalities when traditional ableism has been made\ud
inaccessible. Chapter five focuses on peer relationships. It was found that in filling a\ud
gatekeepers role nondisabled students utilise the governance of friendship to preserve\ud
and regulate the hierarchical relationship between disabled and nondisabled students.\ud
Chapter six using case studies of several students looks at the school's disabled\ud
students' experience of the school, their teachers and their peers. It is clear from these\ud
cases that even with the extensive efforts to dictate and control the positioning within\ud
the school, disabled students are still able to create spaces for resistance
Electrons in Dry DNA from Density Functional Calculations
The electronic structure of an infinite poly-guanine - poly-cytosine DNA
molecule in its dry A-helix structure is studied by means of density-functional
calculations. An extensive study of 30 nucleic base pairs is performed to
validate the method. The electronic energy bands of DNA close to the Fermi
level are then analyzed in order to clarify the electron transport properties
in this particularly simple DNA realization, probably the best suited candidate
for conduction. The energy scale found for the relevant band widths, as
compared with the energy fluctuations of vibrational or genetic-sequence
origin, makes highly implausible the coherent transport of electrons in this
system. The possibility of diffusive transport with sub-nanometer mean free
paths is, however, still open. Information for model Hamiltonians for
conduction is provided.Comment: 8 pages, 4 figure
Marked changes in electron transport through the blue copper protein azurin in the solid state upon deuteration
Measuring electron transport (ETp) across proteins in the solid-state offers
a way to study electron transfer (ET) mechanism(s) that minimizes solvation
effects on the process. Solid state ETp is sensitive to any static
(conformational) or dynamic (vibrational) changes in the protein. Our
macroscopic measurement technique extends the use of ETp meas-urements down to
low temperatures and the concomitant lower current densities, because the
larger area still yields measurable currents. Thus, we reported previously a
surprising lack of temperature-dependence for ETp via the blue copper protein
azurin (Az), from 80K till denaturation, while ETp via apo-(Cu-free) Az was
found to be temperature de-pendent \geq 200K. H/D substitution (deuteration)
can provide a potentially powerful means to unravel factors that affect the ETp
mechanism at a molecular level. Therefore, we measured and report here the
kinetic deuterium isotope effect (KIE) on ETp through holo-Az as a function of
temperature (30-340K). We find that deuteration has a striking effect in that
it changes ETp from temperature independent to temperature dependent above
180K. This change is expressed in KIE values between 1.8 at 340K and 9.1 at
\leq 180K. These values are particularly remarkable in light of the previously
reported inverse KIE on the ET in Az in solution. The high values that we
obtain for the KIE on the ETp process across the protein monolayer are
consistent with a transport mechanism that involves
through-(H-containing)-bonds of the {\beta}-sheet structure of Az, likely those
of am-ide groups.Comment: 15 pages, 3 figures, 2 Supplementary figure
Twisted molecular wires polarize spin currents at room temperature
A critical spintronics challenge is to develop molecular wires that render efficiently spin-polarized currents. Interplanar torsional twisting, driven by chiral binucleating ligands in highly conjugated molecular wires, gives rise to large near-infrared rotational strengths. The large scalar product of the electric and magnetic dipole transition moments ([Formula: see text]), which are evident in the low-energy absorptive manifolds of these wires, makes possible enhanced chirality-induced spin selectivity-derived spin polarization. Magnetic-conductive atomic force microscopy experiments and spin-Hall devices demonstrate that these designs point the way to achieve high spin selectivity and large-magnitude spin currents in chiral materials
User guide to the Magellan synthetic aperture radar images
The Magellan radar-mapping mission collected a large amount of science and engineering data. Now available to the general scientific community, this data set can be overwhelming to someone who is unfamiliar with the mission. This user guide outlines the mission operations and data set so that someone working with the data can understand the mapping and data-processing techniques used in the mission. Radar-mapping parameters as well as data acquisition issues are discussed. In addition, this user guide provides information on how the data set is organized and where specific elements of the set can be located
Linking Ligand-Induced Alterations in Androgen Receptor Structure to Differential Gene Expression: A First Step in the Rational Design of Selective Androgen Receptor Modulators
We have previously identified a family of novel androgen receptor (AR) ligands that, upon binding, enable AR to adopt structures distinct from that observed in the presence of canonical agonists. In this report, we describe the use of these compounds to establish a relationship between AR structure and biological activity with a view to defining a rational approach with which to identify useful selective AR modulators. To this end, we used combinatorial peptide phage display coupled with molecular dynamic structure analysis to identify the surfaces on AR that are exposed specifically in the presence of selected AR ligands. Subsequently, we used a DNA microarray analysis to demonstrate that differently conformed receptors facilitate distinct patterns of gene expression in LNCaP cells. Interestingly, we observed a complete overlap in the identity of genes expressed after treatment with mechanistically distinct AR ligands. However, it was differences in the kinetics of gene regulation that distinguished these compounds. Follow-up studies, in cell-based assays of AR action, confirmed the importance of these alterations in gene expression. Together, these studies demonstrate an important link between AR structure, gene expression, and biological outcome. This relationship provides a firm underpinning for mechanism-based screens aimed at identifying SARMs with useful clinical profiles
Electronic localization at mesoscopic length scales: different definitions of localization and contact effects in a heuristic DNA model
In this work we investigate the electronic transport along model DNA
molecules using an effective tight-binding approach that includes the backbone
on site energies. The localization length and participation number are examined
as a function of system size, energy dependence, and the contact coupling
between the leads and the DNA molecule. On one hand, the transition from an
diffusive regime to a localized regime for short systems is identified,
suggesting the necessity of a further length scale revealing the system borders
sensibility. On the other hand, we show that the lenght localization and
participation number, do not depended of system size and contact coupling in
the thermodynamic limit. Finally we discuss possible length dependent origins
for the large discrepancies among experimental results for the electronic
transport in DNA sample
A Map of Dielectric Heterogeneity in a Membrane Protein: the Hetero-Oligomeric Cytochrome b 6 f Complex
The cytochrome b6f complex, a member of the cytochrome bc family that mediates energy transduction in photosynthetic and respiratory membranes, is a hetero-oligomeric complex that utilizes two pairs of b-hemes in a symmetric dimer to accomplish trans-membrane electron transfer, quinone oxidation–reduction, and generation of a proton electrochemical potential. Analysis of electron storage in this pathway, utilizing simultaneous measurement of heme reduction, and of circular dichroism (CD) spectra, to assay heme–heme interactions, implies a heterogeneous distribution of the dielectric constants that mediate electrostatic interactions between the four hemes in the complex. Crystallographic information was used to determine the identity of the interacting hemes. The Soret band CD signal is dominated by excitonic interaction between the intramonomer b-hemes, bn and bp, on the electrochemically negative and positive sides of the complex. Kinetic data imply that the most probable pathway for transfer of the two electrons needed for quinone oxidation–reduction utilizes this intramonomer heme pair, contradicting the expectation based on heme redox potentials and thermodynamics, that the two higher potential hemes bn on different monomers would be preferentially reduced. Energetically preferred intramonomer electron storage of electrons on the intramonomer b-hemes is found to require heterogeneity of interheme dielectric constants. Relative to the medium separating the two higher potential hemes bn, a relatively large dielectric constant must exist between the intramonomer b-hemes, allowing a smaller electrostatic repulsion between the reduced hemes. Heterogeneity of dielectric constants is an additional structure–function parameter of membrane protein complexes
Temperature and force dependence of nanoscale electron transport via the Cu protein Azurin
The mechanisms of solid-state electron transport (ETp) via a monolayer of
immobilized Azurin (Az) was examined by conducting probe atomic force
microscopy (CP-AFM), both as function of temperature (248 - 373K) and of
applied tip force (6-12 nN). By varying both temperature and force in CP-AFM,
we find that the ETp mechanism can alter with a change in the force applied via
the tip to the proteins. As the applied force increases, ETp via Az changes
from temperature-independent to thermally activated at high temperatures. This
is in contrast to the Cu-depleted form of Az (apo-Az), where increasing the
applied force causes only small quantitative effects, that fit with a decrease
in electrode spacing. At low force ETp via holo-Az is temperature-independent
and thermally activated via apo-Az. This observation agrees with
macroscopic-scale measurements, thus confirming that the difference in ETp
dependence on temperature between holo- and apo-Az is an inherent one that may
reflect a difference in rigidity between the two forms. An important
implication of these results, which depend on CP-AFM measurements over a
significant temperature range, is that for ETp measurements on floppy systems,
such as proteins, the stress applied to the sample should be kept constant or,
at least controlled during measurement.Comment: 24 pages, 6 figures, plus Supporting Information with 4 pages and 2
figure
A Chirality-Based Quantum Leap
There is increasing interest in the study of chiral degrees of freedom occurring in matter and in electromagnetic fields. Opportunities in quantum sciences will likely exploit two main areas that are the focus of this Review: (1) recent observations of the chiral-induced spin selectivity (CISS) effect in chiral molecules and engineered nanomaterials and (2) rapidly evolving nanophotonic strategies designed to amplify chiral light-matter interactions. On the one hand, the CISS effect underpins the observation that charge transport through nanoscopic chiral structures favors a particular electronic spin orientation, resulting in large room-temperature spin polarizations. Observations of the CISS effect suggest opportunities for spin control and for the design and fabrication of room-temperature quantum devices from the bottom up, with atomic-scale precision and molecular modularity. On the other hand, chiral-optical effects that depend on both spin- and orbital-angular momentum of photons could offer key advantages in all-optical and quantum information technologies. In particular, amplification of these chiral light-matter interactions using rationally designed plasmonic and dielectric nanomaterials provide approaches to manipulate light intensity, polarization, and phase in confined nanoscale geometries. Any technology that relies on optimal charge transport, or optical control and readout, including quantum devices for logic, sensing, and storage, may benefit from chiral quantum properties. These properties can be theoretically and experimentally investigated from a quantum information perspective, which has not yet been fully developed. There are uncharted implications for the quantum sciences once chiral couplings can be engineered to control the storage, transduction, and manipulation of quantum information. This forward-looking Review provides a survey of the experimental and theoretical fundamentals of chiral-influenced quantum effects and presents a vision for their possible future roles in enabling room-temperature quantum technologies.ISSN:1936-0851ISSN:1936-086
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