99 research outputs found
Aspects of real-time digital spectral analysis
In the field of control engineering there is
a need
to
study
the dynamic behaviour
of systems which are subjected
to
random
disturbances. A technique
which
is
of great practical use
is to
describe the dynamic
properties as a
function
of
frequency. This
involves determining the frequency content, or spectrum, of
the
disturbances,
and
the frequency
response
function
of
the
system.
There
are many analogue and digital techniques which are designed for this
type
of spectral analysis.
However, digital computer
techniques
are
often avoided because they
are slow, and data must
be
collected
'off-line'.
A
recently
discovered
computational method,
termed the fast-
Fourier-transform (FFT),
enables
digital
spectral analysis
to be
carried-
out in
a much shorter
time than
was previously possible.
In
view of
this discovery it
was
decided to develop digital computer programmes
which would overcome
the disadvantages
of conventional
digital
spectral
analysis. Using these
programmes a computer would
be
connected, via
an analogue
to digital interface, to the
signal source, and would process
the data
as
it
entered
the
computer.
In the jargon
of computing,
the
computer would
be 'on-line'
and analyzing
the
spectra
in 'real-time'.
The first
part of
the
project consisted of an
investigation
of
the FFP
when programmed
for an on-line
digital
computer.
The
results of
this investigation
showed
that
a rapid, accurate, and compact
FFT
could be
programmed
by
using
fixed-point
arithmetic, and coding
in
an assembly language. The
speed of
the transform
was sufficient
to
allow spectral analysis over a
frequency
range useful
in
control
applications.
Two
on-line computer programmes
based upon
the YPP were
then
written; one
for 'real-time'
spectral analysis of a single record, and
another
for the 'real-time'
estimation of
the frequency
response
function
relating
two
signals.
In
order
that the
results of
these
programmes could
be
sensibly
interpreted, a statistical study was made
of
the
spectral estimators used
in the
programmes.
Arising from this
study, several contributions
to the field of
digital
spectra. analysis
were made.
These
were : -
1) A
more general covariance relationship
for cross-spectral
estimators.
2) An
examination of aliasing
in digital
spectral estimators.
3) Some theoretical
results concerning spectral estimators
for
closed loop
systems with random
disturbances inside the loop,
Some
experimental work was conducted with
the
real-time'
spectral analysis programmes, and it
was concluded
that the tec:
inique
is
more powerful
than
conventional
digital.
methods
because it is on-
line,
and can provide estimates with
improved
resolution and
statistical stability. Real-time digital
spectral analysis methods also
have the
advantage
that they
may
be
simply and quickly modified
to suit
specific applications
A Rewriting-Logic-Based Technique for Modeling Thermal Systems
This paper presents a rewriting-logic-based modeling and analysis technique
for physical systems, with focus on thermal systems. The contributions of this
paper can be summarized as follows: (i) providing a framework for modeling and
executing physical systems, where both the physical components and their
physical interactions are treated as first-class citizens; (ii) showing how
heat transfer problems in thermal systems can be modeled in Real-Time Maude;
(iii) giving the implementation in Real-Time Maude of a basic numerical
technique for executing continuous behaviors in object-oriented hybrid systems;
and (iv) illustrating these techniques with a set of incremental case studies
using realistic physical parameters, with examples of simulation and model
checking analyses.Comment: In Proceedings RTRTS 2010, arXiv:1009.398
Computerised interpretation of fetal heart rate during labour (INFANT): a randomised controlled trial
Background. Continuous electronic fetal heart-rate monitoring is widely used during labour, and computerised interpretation could increase its usefulness. We aimed to establish whether the addition of decision-support software to assist in the interpretation of cardiotocographs affected the number of poor neonatal outcomes.
Methods. In this unmasked randomised controlled trial, we recruited women in labour aged 16 years or older having continuous electronic fetal monitoring, with a singleton or twin pregnancy, and at 35 weeks’ gestation or more at 24 maternity units in the UK and Ireland. They were randomly assigned (1:1) to decision support with the INFANT system or no decision support via a computer-generated stratified block randomisation schedule. The primary outcomes were poor neonatal outcome (intrapartum stillbirth or early neonatal death excluding lethal congenital anomalies, or neonatal encephalopathy, admission to the neonatal unit within 24 h for ≥48 h with evidence of feeding difficulties, respiratory illness, or encephalopathy with evidence of compromise at birth), and developmental assessment at age 2 years in a subset of surviving children. Analyses were done by intention to treat. This trial is completed and is registered with the ISRCTN Registry, number 98680152.
Findings. Between Jan 6, 2010, and Aug 31, 2013, 47062 women were randomly assigned (23515 in the decision-support group and 23547 in the no-decision-support group) and 46042 were analysed (22987 in the decision-support group and 23055 in the no-decision-support group). We noted no difference in the incidence of poor neonatal outcome between the groups—172 (0·7%) babies in the decision-support group compared with 171 (0·7%) babies in the no-decision-support group (adjusted risk ratio 1·01, 95% CI 0·82–1·25). At 2 years, no significant differences were noted in terms of developmental assessment.
Interpretation. Use of computerised interpretation of cardiotocographs in women who have continuous electronic fetal monitoring in labour does not improve clinical outcomes for mothers or babies
Re-visiting Meltsner: Policy Advice Systems and the Multi-Dimensional Nature of Professional Policy Analysis
10.2139/ssrn.15462511-2
Quality standards for the management of alcohol-related liver disease: consensus recommendations from the British Association for the Study of the Liver and British Society of Gastroenterology ARLD special interest group
Objective Alcohol-related liver disease (ALD) is the most
common cause of liver-related ill health and liver-related
deaths in the UK, and deaths from ALD have doubled
in the last decade. The management of ALD requires
treatment of both liver disease and alcohol use; this
necessitates effective and constructive multidisciplinary
working. To support this, we have developed quality
standard recommendations for the management of ALD,
based on evidence and consensus expert opinion, with the
aim of improving patient care.
Design A multidisciplinary group of experts from the
British Association for the Study of the Liver and British
Society of Gastroenterology ALD Special Interest Group
developed the quality standards, with input from the
British Liver Trust and patient representatives.
Results The standards cover three broad themes: the
recognition and diagnosis of people with ALD in primary
care and the liver outpatient clinic; the management of
acutely decompensated ALD including acute alcoholrelated hepatitis and the posthospital care of people
with advanced liver disease due to ALD. Draft quality
standards were initially developed by smaller working
groups and then an anonymous modified Delphi voting
process was conducted by the entire group to assess
the level of agreement with each statement. Statements
were included when agreement was 85% or greater.
Twenty-four quality standards were produced from this
process which support best practice. From the final
list of statements, a smaller number of auditable key
performance indicators were selected to allow services to
benchmark their practice and an audit tool provided.
Conclusion It is hoped that services will review their
practice against these recommendations and key
performance indicators and institute service development
where needed to improve the care of patients with ALD
Parkinson’s disease mouse models in translational research
Animal models with high predictive power are a prerequisite for translational research. The closer the similarity of a model to Parkinson’s disease (PD), the higher is the predictive value for clinical trials. An ideal PD model should present behavioral signs and pathology that resemble the human disease. The increasing understanding of PD stratification and etiology, however, complicates the choice of adequate animal models for preclinical studies. An ultimate mouse model, relevant to address all PD-related questions, is yet to be developed. However, many of the existing models are useful in answering specific questions. An appropriate model should be chosen after considering both the context of the research and the model properties. This review addresses the validity, strengths, and limitations of current PD mouse models for translational research
The many meanings of evidence: a comparative analysis of the forms and roles of evidence within three health policy processes in Cambodia
Background Discussions within the health community routinely emphasise the importance of evidence in informing policy formulation and implementation. Much of the support for the evidence-based policy movement draws from concern that policy decisions are often based on inadequate engagement with high-quality evidence. In many such discussions, evidence is treated as differing only in quality, and assumed to improve decisions if it can only be used more. In contrast, political science scholars have described this as an overly simplistic view of the policy-making process, noting that research ‘use’ can mean a variety of things and rely on nuanced aspects of political systems. An approach more in recognition of how policy-making systems operate in practice can be to consider how institutions and ideas influence which pieces of evidence appear to be relevant for, and are used within, different policy processes. Methods Drawing on in-depth interviews undertaken in 2015/16 with key health sector stakeholders in Cambodia, we investigate the evidence perceived to be relevant to policy decisions for three contrasting health policy examples – tobacco control, HIV/AIDS and performance-based salary incentives. These cases allow us to examine the ways that policy relevant evidence may differ given the framing of the issue and the broader institutional context in which evidence is considered. Results The three health issues show few similarities in how pieces of evidence were used in various aspects of policy-making, despite all being discussed within a broad policy environment in which evidence-based policymaking is rhetorically championed. Instead, we find that evidence use can be better understood by mapping how these health policy issues differ in terms of the issue characteristics, and also in terms of the stakeholders structurally established as having dominant influence for each issue. Both of these have important implications for evidence use. Contrasting concerns of key stakeholders meant that evidence related to differing issues could be understood in terms of how it was policy relevant. The stakeholders involved, however, could further be seen to possess differing logics about how to go about achieving their various outcomes – logics that could further help explain the differences seen in evidence utilisation. Conclusion A comparative approach reiterates that evidence is not a uniform concept for which more is obviously better, but rather illustrates how different constructions and pieces of evidence become relevant in relation to the features of specific health policy decisions. An institutional approach that considers the structural position of stakeholders with differing core goals or objectives, as well as their logics related to evidence utilisation, can further help to understand some of the complexities of evidence use in health policymaking
General anaesthetic and airway management practice for obstetric surgery in England: a prospective, multi-centre observational study
There are no current descriptions of general anaesthesia characteristics for obstetric surgery, despite recent changes to patient baseline characteristics and airway management guidelines. This analysis of data from the direct reporting of awareness in maternity patients' (DREAMY) study of accidental awareness during obstetric anaesthesia aimed to describe practice for obstetric general anaesthesia in England and compare with earlier surveys and best-practice recommendations. Consenting patients who received general anaesthesia for obstetric surgery in 72 hospitals from May 2017 to August 2018 were included. Baseline characteristics, airway management, anaesthetic techniques and major complications were collected. Descriptive analysis, binary logistic regression modelling and comparisons with earlier data were conducted. Data were collected from 3117 procedures, including 2554 (81.9%) caesarean deliveries. Thiopental was the induction drug in 1649 (52.9%) patients, compared with propofol in 1419 (45.5%). Suxamethonium was the neuromuscular blocking drug for tracheal intubation in 2631 (86.1%), compared with rocuronium in 367 (11.8%). Difficult tracheal intubation was reported in 1 in 19 (95%CI 1 in 16-22) and failed intubation in 1 in 312 (95%CI 1 in 169-667). Obese patients were over-represented compared with national baselines and associated with difficult, but not failed intubation. There was more evidence of change in practice for induction drugs (increased use of propofol) than neuromuscular blocking drugs (suxamethonium remains the most popular). There was evidence of improvement in practice, with increased monitoring and reversal of neuromuscular blockade (although this remains suboptimal). Despite a high risk of difficult intubation in this population, videolaryngoscopy was rarely used (1.9%)
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