41,122 research outputs found
Heart catheter cable and connector
Ultraminiature catheter cables that are stiff enough for intravenous insertion yet flexible at the tip, sterilizable, and economical are fabricated entirely from commercially available parts. Assembly includes air passageway for reference pressures and coaxial cable for transmission of signals from the tip of catheter
A Graphical Language for Proof Strategies
Complex automated proof strategies are often difficult to extract, visualise,
modify, and debug. Traditional tactic languages, often based on stack-based
goal propagation, make it easy to write proofs that obscure the flow of goals
between tactics and are fragile to minor changes in input, proof structure or
changes to tactics themselves. Here, we address this by introducing a graphical
language called PSGraph for writing proof strategies. Strategies are
constructed visually by "wiring together" collections of tactics and evaluated
by propagating goal nodes through the diagram via graph rewriting. Tactic nodes
can have many output wires, and use a filtering procedure based on goal-types
(predicates describing the features of a goal) to decide where best to send
newly-generated sub-goals.
In addition to making the flow of goal information explicit, the graphical
language can fulfil the role of many tacticals using visual idioms like
branching, merging, and feedback loops. We argue that this language enables
development of more robust proof strategies and provide several examples, along
with a prototype implementation in Isabelle
Temperature-dependent resistivity of suspended graphene
In this paper we investigate the electron-phonon contribution to the
resistivity of suspended single layer graphene. In-plane as well as flexural
phonons are addressed in different temperature regimes. We focus on the
intrinsic electron-phonon coupling due to the interaction of electrons with
elastic deformations in the graphene membrane. The competition between screened
deformation potential vs fictitious gauge field coupling is discussed, together
with the role of tension in the suspended flake. In the absence of tension,
flexural phonons dominate the phonon contribution to the resistivity at any
temperature with a and dependence at low and high
temperatures, respectively. Sample-specific tension suppresses the contribution
due to flexural phonons, yielding a linear temperature dependence due to
in-plane modes. We compare our results with recent experiments.Comment: 11 pages, 3 figure
A multi proxy investigation into the effects of burial environments on nuclear DNA in bone over forensic and archaeological timescales
This research conducted a two-pronged approach to study the effects of
taphonomic processes by conducting analysis of experimental burials of porcine
femora and parallel analysis of ancient human archaeological remains from
geologically distinct cemeteries. The aim of this study was to identify the major
degradative factors from depositional environments that affect the bone
composition and the retention and retrieval of nucleic DNA from archaeological
bone. Four different experimental burial environments of clay, compost, lime and
sand were designed, displaying different properties of soil type, pH, water content
and organic content. Analysis of the burial mediums and bones were conducted at
regular intervals over an 18 month period. Observations of changes in the burial
medium, comparisons of the rates and degree of soft tissue decomposition, bone
diagenesis from compositional assessment, and bone colour change were made
and analysed in correspondence with the different environments. The analytical
data collected on the diagenesis of the archaeological bone from both studies, was
compared to the DNA profiling success rates.
The research and optimisation of sample preparation and DNA analysis enabled
the most cost-effective and appropriate methods to be identified and utilised in
accordance with the preservation state of the bone samples. This allowed the
analysis of ancient archaeological bone to be analysed in-line with forensic
protocols, to enable a uniform accessible approach to produce comparable results
across different laboratories.
Drawing together the results from the various analytical techniques made it
possible to identify the variables that affect bone diagenesis and the survival of
nuclear DNA, and provide evidence that the rate of decomposition and bone
degradation is affected more significantly by the burial environment than duration
of burial, as stated in the research hypothesis. The presence of water, sand and the
level of organic content were found to be the most degradative variables within the
experimental burial conditions; causing changes in bone crystallinity, and
infiltration of contaminants into the bone. The presence of lime, chalk or limestone in an environment was found to have preserving properties in both the porcine
and human burials, by retarding the rate and degree of soft tissue decomposition,
and reducing the diagenetic changes in bone composition evident from the other
environments.
Despite previous reports of success using analytical techniques as predictive
models for DNA and bone preservation, no correlations with DNA survival could be
established. However the use of a multi-disciplinary approach enabled the
detection and identification of soil contaminants affecting the bone structure and
the ability to amplify DNA, in relation to burial environments. This research
highlighted the importance of utilising multiple analytical techniques, such as
colourimetry, ATR-FTIR, XRF and genetic analysis in order to avoid
misinterpretation and false reporting of the state of bone diagenesis or
preservation and the survival of DNA, due to environmental contaminants within
the hard tissue.
The research confirms the idea that in order to establish optimised sampling and
DNA analysis of archaeological bone, it is imperative that certain protocols are
adhered to. Precautions must be implemented from excavation through to
laboratory analysis to avoid contamination; and correct recording of burial
environment is essential to enable consideration of extrinsic factors and
contaminants when reporting results
Evaluation of the cardiovascular system during various circulatory stresses Progress report, 1 Sep. 1968 - 1 May 1969
Cardiac response to chemotherapy after myocardial infraction and diagnostic methods of heart disease in man and animal
A new quantum fluid at high magnetic fields in the marginal charge-density-wave system -(BEDT-TTF)Hg(SCN) (where ~K and Rb)
Single crystals of the organic charge-transfer salts
-(BEDT-TTF)Hg(SCN) have been studied using Hall-potential
measurements (K) and magnetization experiments ( = K, Rb). The data show
that two types of screening currents occur within the high-field,
low-temperature CDW phases of these salts in response to time-dependent
magnetic fields. The first, which gives rise to the induced Hall potential, is
a free current (), present at the surface of the sample.
The time constant for the decay of these currents is much longer than that
expected from the sample resistivity. The second component of the current
appears to be magnetic (), in that it is a microscopic,
quasi-orbital effect; it is evenly distributed within the bulk of the sample
upon saturation. To explain these data, we propose a simple model invoking a
new type of quantum fluid comprising a CDW coexisting with a two-dimensional
Fermi-surface pocket which describes the two types of current. The model and
data are able to account for the body of previous experimental data which had
generated apparently contradictory interpretations in terms of the quantum Hall
effect or superconductivity.Comment: 13 pages, 11 figure
Theoretical investigation of magnetoelectric effects in Ba2CoGe2O7
A joint theoretical approach, combining macroscopic symmetry analysis with
microscopic methods (density functional theory and model cluster Hamiltonian),
is employed to shed light on magnetoelectricity in Ba2CoGe2O7. We show that the
recently reported experimental trend of polarization guided by magnetic field
can be predicted on the basis of phenomenological Landau theory. From the
microscopic side, Ba2CoGe2O7 emerges as a prototype of a class of
magnetoelectrics, where the cross coupling between magnetic and dipolar degrees
of freedom needs, as main ingredients, the on-site spin-orbit coupling and the
spin-dependent O p - Co d hybridization, along with structural constraints
related to the noncentrosymmetric structural symmetry and the peculiar
configuration of CoO4 tetrahedrons.Comment: 5 pages, 4 figures, submitted for publicatio
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Behaviour change at work: Empowering energy efficiency in the workplace through user-centred design
Copyright @ 2011 University of California eScholarship RepositoryCO2 emissions from non-domestic buildings - primarily workplaces - make up 18 percent of the UK's carbon footprint. A combination of technology advances and behavioural changes have the potential to make significant impact, but interventions have often been planned in ways which do not take into account the needs, levels of understanding and everyday behavioural contexts of building users - and hence do not achieve the hoped-for success.This paper provides a brief introduction to the Empower project, a current industrial-academic collaboration in the UK which is applying methods from user-centred design practice to understand diverse users' needs, priorities, mental models of energy and decision-making heuristics - as well as the affordances available to them - in a number of office buildings. We are developing and trialling a set of low-cost, simple software interventions tailored to multiple user groups with different degrees of agency over their energy use, which seek to influence more energy efficient behaviour at work in areas such as HVAC, lighting and equipment use. The project comprises an ethnographic research phase, a participatory design programme involving building users in the design of interventions, and iterative trials in a large office building in central London
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