2,303 research outputs found
Theoretical Approach to Electroresistance in Ferroelectric Tunnel Junctions
In this paper, a theoretical approach, comprising the non-equilibrium Green's
function method for electronic transport and Landau-Khalatnikov equation for
electric polarization dynamics, is presented to describe polarization-dependent
tunneling electroresistance (TER) in ferroelectric tunnel junctions. Using
appropriate contact, interface, and ferroelectric parameters, measured
current-voltage characteristic curves in both inorganic
(Co/BaTiO/LaSrMnO) and organic (Au/PVDF/W)
ferroelectric tunnel junctions can be well described by the proposed approach.
Furthermore, under this theoretical framework, the controversy of opposite TER
signs observed experimentally by different groups in
Co/BaTiO/LaSrMnO systems is addressed by
considering the interface termination effects using the effective contact
ratio, defined through the effective screening length and dielectric response
at the metal/ferroelectric interfaces. Finally, our approach is extended to
investigate the role of a CoO buffer layer at the Co/BaTiO
interface in a ferroelectric tunnel memristor. It is shown that, to have a
significant memristor behavior, not only the interface oxygen vacancies but
also the CoO layer thickness may vary with the applied bias.Comment: 12 page
A Synthetic Representation of Inter-Organizational Multi-Actor Collaborative Structures: A Pragmatic Look at U.S. E-Prescribing
A synthetic representation of the collaborative structure in U.S. e-prescribing offers explanations for unintended enactments (e.g., surrogate prescribers) of this healthcare information technology. The generation and transmission of a prescription requires collaboration between at least a prescriber, pharmacy, and patient. The interactions of these actors are modeled through one or more pairs of synthetic representations built using various theoretical lenses such as language-action models. The pluralist pragmatic basis for building a synthetic representation is interpretive synthesis used widely in healthcare. The paper describes how 240+ academic articles in various fields of healthcare are used to synthesize a model of existing (manual prescribing) and intended (e-prescribing) practices. Comparison of these two synthetic models identifies differences such as change in roles or new relationships. These differences can then be interpreted through a theoretical framework which ultimately leads to research propositions, informing design or future policy
Brain Differences in the Prefrontal Cortex, Amygdala, and Hippocampus in Youth with Congenital Adrenal Hyperplasia
Context: Classical Congenital Adrenal Hyperplasia (CAH) due to 21-hydroxylase deficiency results in hormone imbalances present both prenatally and postnatally that may impact the developing brain.
Objective: To characterize gray matter morphology in the prefrontal cortex and subregion volumes of the amygdala and hippocampus in youth with CAH, compared to controls.
Design: A cross-sectional study of 27 CAH youth (16 female; 12.6 Ā± 3.4 year) and 35 typically developing, healthy controls (20 female; 13.0 Ā± 2.8 year) with 3-T magnetic resonance imaging scans. Brain volumes of interest included bilateral prefrontal cortex, and nine amygdala and six hippocampal subregions. Between-subject effects of group (CAH vs control) and sex, and their interaction (group-by-sex) on brain volumes were studied, while controlling for intracranial volume (ICV) and group differences in body mass index and bone age.
Results: CAH youth had smaller ICV and increased cerebrospinal fluid volume compared to controls. In fully-adjusted models, CAH youth had smaller bilateral, superior and caudal middle frontal volumes, and smaller left lateral orbito-frontal volumes compared to controls. Medial temporal lobe analyses revealed the left hippocampus was smaller in fully-adjusted models. CAH youth also had significantly smaller lateral nucleus of the amygdala and hippocampal subiculum and CA1 subregions.
Conclusions: This study replicates previous findings of smaller medial temporal lobe volumes in CAH patients, and suggests that lateral nucleus of the amygdala, as well as subiculum and subfield CA1 of the hippocampus are particularly affected within the medial temporal lobes in CAH youth
Asymptotic Behaviour of the Proper Length and Volume of the Schwarzschild Singularity
Though popular presentations give the Schwarzschild singularity as a point it
is known that it is spacelike and not timelike. Thus it has a "length" and is
not a "point". In fact, its length must necessarily be infinite. It has been
proved that the proper length of the Qadir-Wheeler suture model goes to
infinity [1], while its proper volume shrinks to zero, and the asymptotic
behaviour of the length and volume have been calculated. That model consists of
two Friedmann sections connected by a Schwarzschild "suture". The question
arises whether a similar analysis could provide the asymptotic behaviour of the
Schwarzschild black hole near the singularity. It is proved here that, unlike
the behaviour for the suture model, for the Schwarzschild essential singularity
and , where
is the mean extrinsic curvature, or the York time.Comment: 13 pages, 1 figur
Framework for better living with HIV in England
Duration: April 2007 - May 2009
Sigma Research was funded by Terrence Higgins Trust to co-ordinate the development of a framework to address the health, social care, support and information needs of people with diagnosed HIV in England. It has now been published as the Framework for better living with HIV in England.
The over-arching goal of the framework is that all people with diagnosed HIV in England "are enabled to have the maximum level of health, well-being, quality of life and social integration". In its explanation of how this should occur the document presents a road map for social care, support and information provision to people with diagnosed HIV in England. By establishing and communicating aims and objectives, the framework should build consensus and provide a means to establish how interventions could be prioritised and coordinated. The key drivers for the framework were clearly articulated ethical principles, agreed by all those who sign up to it, and an inclusive social development / health promotion approach.
Sigma Research worked on the framework with a range of other organisations who sent representatives to a Framework Development Group (see below for membership). The framework is evidence-based and seeks to:
Promote and protect the rights and well-being of all people with HIV in England.
Maximise the capacity of individuals and groups of people with HIV to care for, advocate and represent themselves effectively.
Improve and protect access to appropriate information, social support, social care and clinical services.
Minimise social, economic, governmental and judicial change detrimental to the health and well being of people with HIV.
Alongside the development of the framework, Sigma Research undertook a national needs assessment among people with diagnosed HIV across the UK called What do you need?. These two projects informed and supported each other.
Framework Development Group included:
African HV Policy Network
Black Health Agency
George House Trust
NAM
NAT (National AIDS Trust)
Positively Women
Terrence Higgins Trus
Getting at the Source of Distinctive Encoding Effects in the DRM Paradigm: Evidence From Signal-Detection Measures and Source Judgments
Studying DeeseāRoedigerāMcDermott (DRM) lists using a distinctive encoding task can reduce the DRM false memory illusion. Reductions for both distinctively encoded lists and non-distinctively encoded lists in a within-group design have been ascribed to use of a distinctiveness heuristic by which participants monitor their memories at test for distinctive-task details. Alternatively, participants might simply set a more conservative response criterion, which would be exceeded by distinctive list items more often than all other test items, including the critical non-studied items. To evaluate these alternatives, we compared a within-group who studied 5 lists by reading, 5 by anagram generation, and 5 by imagery, relative to a control group who studied all 15 lists by reading. Generation and imagery improved recognition accuracy by impairing relational encoding, but the within group did not show greater memory monitoring at test relative to the read control group. Critically, the within groupās pattern of list-based source judgments provided new evidence that participants successfully monitored for distinctive-task details at test. Thus, source judgments revealed evidence of qualitative, recollection-based monitoring in the within group, to which our quantitative signal-detection measure of monitoring was blind
Sensorimotor coding of vermal granule neurons in the developing mammalian cerebellum
The vermal cerebellum is a hub of sensorimotor integration critical for postural control and locomotion, but the nature and developmental organization of afferent information to this region have remained poorly understoo
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