1,272 research outputs found
On-line multiobjective automatic control system generation by evolutionary algorithms
Evolutionary algorithms are applied to the on- line generation of servo-motor control systems. In this paper, the evolving population of controllers is evaluated at run-time via hardware in the loop, rather than on a simulated model. Disturbances are also introduced at run-time in order to pro- duce robust performance. Multiobjective optimisation of both PI and Fuzzy Logic controllers is considered. Finally an on-line implementation of Genetic Programming is presented based around the Simulink standard blockset. The on-line designed controllers are shown to be robust to both system noise and ex- ternal disturbances while still demonstrating excellent steady- state and dvnamic characteristics
Per-protocol investigation of a best practice exercise referral scheme.
Objectives: To investigate the effects of an exercise referral scheme (ERS) aligned to the UK best practice guidelines on a range of outcomes including those associated with key health concerns of the Scottish population. Study design A longitudinal design with data collection at three time points (baseline, midway and post) during a 12-week ERS intervention was employed. Methods: Health-related physical fitness was assessed through measurement of resting heart rate, blood pressure, FEV1:FEV6 (ratio of forced expiratory volume over one [FEV1] and six [FEV6] seconds), body mass and peak oxygen uptake (VO2 peak), whilst functional capacity was assessed through the five times sit to stand test. Psychosocial well-being and quality of life were measured using the World Health Organization Quality of Life questionnaire (WHOQOL-BREF) and the Profile of Mood State questionnaires. Growth curve analyses were used to model each outcome variable across the three time periods. Results: A range of effects were obtained with significant linear improvements in physical performance tests (P < 0.001) and psychosocial assessments (P ≤ 0.002). Additionally, significant quadratic effects of time were obtained for body composition variables and physical activity levels (P < 0.001) with the greatest improvements obtained between baseline and midway assessments. Conclusions: An ERS aligned to the UK best practice guidelines can positively influence a range of health outcomes including those associated with lung function and cardiovascular fitness which are prevalent medical conditions in Scotland. In addition, results indicate that ERS can positively affect outcomes related to functional capacity as well as mental well-being and perceptions of health. The findings of the study identify the need for further investigation including consideration of the initial health status of referred clients
A novel selective 11b-hydroxysteroid dehydrogenase type 1 inhibitor prevents human adipogenesis.
Glucocorticoid excess increases fat mass, preferentially within omental depots; yet circulating cortisol concentrations are normal in most patients with metabolic syndrome (MS). At a pre-receptor level, 11b-hydroxysteroid dehydrogenase type 1 (11b-HSD1) activates cortisol from cortisone locally within adipose tissue, and inhibition of 11b-HSD1 in liver and adipose tissue has been proposed as a novel therapy to treat MS by reducing hepatic glucose output and adiposity. Using a transformed human subcutaneous preadipocyte cell line (Chub-S7) and human primary preadipocytes, we have defined the role of glucocorticoids and 11b-HSD1 in regulating adipose tissue differentiation. Human cells were differentiated with 1.0 mM cortisol (F), or cortisone (E) with or without 100 nM of a highly selective 11b-HSD1 inhibitor PF-877423. 11b-HSD1 mRNA expression increased across adipocyte differentiation (P!0.001, nZ4), which was paralleled by an increase in 11b-HSD1 oxo-reductase activity (from nil on day 0 to 5.9G1.9 pmol/mg per h on day 16,P!0.01, nZ7). Cortisone enhanced adipocyte differentiation; fatty acid-binding protein 4 expression increased 312-fold (P!0.001) and glycerol-3-phosphate dehydrogenase 47-fold (P!0.001) versus controls. This was abolished by co-incubation with PF-877423. In addition, cellular lipid content decreased significantly. These findings were confirmed in the primary cultures of human subcutaneous preadipocytes. The increase in 11b-HSD1 mRNA expression and activity is essential for the induction of human adipogenesis. Blocking adipogenesis with a novel and specific 11b-HSD1 inhibitor may represent a novel approach to treat obesity in patients with MS
Doppler colour flow mapping of fetal intracerebral arteries in the presence of central nervous system anomalies
The adjunctive role of Doppler colour flow mapping in the evaluation of intracerebral morphology and arterial blood flow in the presence of normal and abnormal central nervous system morphology was determined. A total of 59 fetuses with suspected central nervous system pathology between 14 and 37 weeks of gestation was studied (median 31 weeks). One hundred and one fetuses with normal central nervous system anatomy between 14 and 37 weeks (median 19 weeks) served as controls. Visualisation of blood flow in one or more intracerebral arterial vessels was successful in more than 80% of normal fetuses. For the anterior, middle and posterior cerebral artery, the percentages were 63%, 89% and 45%, respectively, at 14–25 weeks and 74%, 100% and 55%, respectively, at 26–37 weeks of gestation. Intracerebral arterial flow identification was attempted in 52/59 (88%) affected fetuses. Identification of blood flow in one or more intracerebral arterial vessels was successful in (77%) fetuses. End-diastolic flow velocities were present in at least one of the intracerebral arteries in fetuses, absent in one case of hydrocephaly and raised in the presence of an intracerebral vascular tumour. Doppler colour flow mapping seems to provide only limited additional information on intracranial structural pathology
Echocardiography in the human fetus
The objectives of this study were as follows.
The first objective was to assess and review current non-invasive methods
of studying normal and abnormal human fetal cardiac morphology and function.
A discussion of the four currently used ultrasonic techniques to define fetal cardiac
anatomy and physiology can be found in chapter 2.
The second objective consisted of the analysis of results obtained following
examination of a group of patients deemed at increased risk of producing a
child with congenital heart disease. The data from a group of 1577 pregnant
women are presented in chapter 3.
Patients with certain complications of pregnancy are also considered to be
at risk of carrying a child with congenital heart disease, either alone or in combination with other structural or chromosomal aberrations. The third objective,
therefore, was to analyse 440 patients collected in this category. The
data can be found in chapter 4.
The fourth objective was to establish and, therefore, understand possible pitfalls
and errors when assessing fetal cardiac anatomy ultrasonically. To this end an
ultrasonic-pathologic correlation was made wherever possible. The appropriate
correlations in 12 cases are presented in chapter 5.
Fetal cardiac arrhythmia may be entirely benign or life threatening. It is
imperative to correctly define the type of arrhythmia and its possible association
with congenital heart disease before a realistic prognosis can be given or before
considering therapeutic options. The objective of chapter 6 was to describe
methods of recording and definition of fetal cardiac arrhythmia and to assess
the outcome in this group
Prenatal diagnosis by ultrasound in pregnancies at risk for autosomal recessive polycystic kidney disease
Abstract
In 15 pregnancies at risk of the autosomal recessive type of polycystic kidney disease (ARPKD), there were six recurrences (40%), five of which were diagnosed prenatally between 17 and 26 weeks (mean, 22 weeks). In the remaining affected case, normal kidney size and echogenicity were still present at 30 weeks of gestation. Fetal kidney enlargement and increased echogenicity are the key ultrasonographic signs for the detection of ARPKD. Absent fetal bladder filling and oligohydramnios were only documented in two of the six affected pregnancies. The variability in onset, the intrafamilial variability and the limitations of excluding ARPKD by second trimester ultrasound have to be considered when counselling a couple at risk for this particular disorder
Finding cactus roots in polynomial time
A cactus is a connected graph in which each edge belongs to at most one cycle. A graph H is a cactus root of a graph G if H is a cactus and G can be obtained from H by adding an edge between any two vertices in H that are of distance 2 in H. We show that it is possible to test in O(n4)O(n4) time whether an n-vertex graph G has a cactus root
Elastic behavior in Contact Dynamics of rigid particles
The systematic errors due to the practical implementation of the Contact
Dynamics method for simulation of dense granular media are examined. It is
shown that, using the usual iterative solver to simulate a chain of rigid
particles, effective elasticity and sound propagation with a finite velocity
occur. The characteristics of these phenomena are investigated analytically and
numerically in order to assess the limits of applicability of this simulation
method and to compare it with soft particle molecular dynamics.Comment: submitted to PRE, 7 pages, 6 figure
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