159 research outputs found
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
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
Properties of input-output Hammerstein-bilinear structure with application to an industrial air handling unit
When developing mathematical models, especially for control, the practical interest lies in relatively simple extensions of linear structures that offer improved modelling capabilities. In this paper a discrete-time input-output Hammerstein-bilinear structure is introduced and its properties are discussed in detail. It consists of a cascade connection of a static nonlinearity followed by a dynamic bilinear system. By combining advantages of constituent subsystems the Hammerstein-bilinear structure allows for both an input dependant dynamic behaviour (particular property of bilinear systems) and an increased flexibility of the steady-state characteristic (particular property of Hammerstein models) to be obtained simultaneously. Modelling capabilities of such structure are evaluated on an air-handling unit that is a part of an industrial heating, ventilation and air-conditioning system
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, 47 062 women were randomly assigned (23 515 in the decision-support group and 23 547 in the no-decision-support group) and 46 042 were analysed (22 987 in the decision-support group and 23 055 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
Antibody in breastmilk following Pertussis vaccination in three-time windows in pregnancy
Background: Pertussis-containing vaccines are routinely offered in the UK at 16-32 weeks of gestation and have been shown to be safe and effective, but there remains debate about the best timing for vaccination. Most research into this has focused on serologic immunity, but breastmilk is also important in infant immunity, and the amount of IgA in breastmilk may impact mucosal immunity. It is important to understand if the timing of vaccination in pregnancy affects the concentration of IgA in breastmilk.
Methods: Participants recruited as part of the MAMA (Maternal Antibody in Milk After Vaccination) and OpTIMUM (Optimizing the Timing of Whooping Cough Immunisations in Mums) trials received a pertussis-containing vaccine during pregnancy, either before 24 weeks, between 24 and 27+6 weeks or between 28 and 31+6 weeks. Samples of colostrum within 24 hours of delivery and breastmilk at 14 days were collected. Pertussis toxin, pertactin, tetanus toxoid and diphtheria toxoid specific-IgA levels were measured using a multiplex immunoassay.
Results: There was no difference in specific IgA levels against pertussis toxin, pertactin, tetanus toxoid and diphtheria toxoid between the groups vaccinated within different time periods. For all antigens, there was decay in antigen-specific IgA levels between colostrum and breastmilk at 14 days.
Conclusion: Our results suggest that the timing of administration of a pertussis-containing vaccine in pregnancy does not impact on antigen-specific IgA concentration in colostrum or breastmilk at 14 days
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
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
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