Modeling Stochastic Dynamical Systems for Interactive Simulation

We present techniques for constructing approximate stochastic models of complicated dynamical systems for applications in interactive computer graphics. The models are designed to produce realistic interaction at low cost.
We describe two kinds of stochastic models: continuous state (ARX) models and discrete state (Markov chains) models. System identi cation techniques are used for learning the input-output dynamics automatically, from either measurements of a real system or from an accurate simulation. The synthesis of behavior in this manner is several orders of magnitude faster than physical simulation.We demonstrate the techniques with two examples: (1) the dynamics of candle ame in the wind, modeled using data from a real candle and (2) the motion of a falling leaf, modeled using data from a complex simulation. We have implemented an interactive Java program which demonstrates real-time interaction with a realistically behaving simulation of a cartoon candle ame. The user makes the ame animation icker by blowing into a microphone.     

Activated protein C resistance, factor V Leiden and peripheral vascular disease

AIM: To study cerebrospinal fluid (CSF) concentrations of plasminogen activator inhibitor type-1 (PAI-1) in patients with neurological disease. METHODS: CSF PAI-1 concentrations were measured in 51 patients with neurological disease and 20 reference subjects using an ELISA. The patient group comprised three patients with viral meningitis, 20 with encephalitis, nine with acute lymphoblastic (n = 7) and myeloid (n = 2) leukaemia (with central nervous system involvement), and 19 with multiple sclerosis. RESULTS: Raised PAI-1 concentrations were observed in patients with leukaemia, encephalitis and multiple sclerosis. There was no difference in the mean concentrations of PAI-1 in patients with meningitis when compared with the reference subjects. The highest mean (SEM) PAI-1 concentration was found in patients with leukaemia (1.28 (0.36) ng/ml), and the next highest in those with encephalitis (1.19 (0.20) ng/ml). these values were much higher than those in patients with viral meningitis. In a previous report, raised CSF tissue-type plasminogen activator (tPA) activities were detected in patients with multiple sclerosis, leukaemia and encephalitis, with mean activities in decreasing order. PAI-1 concentrations in the same patients were the reverse of their corresponding tPA activities, being higher in those with leukaemia and encephalitis, than in patients with multiple sclerosis. There was no association between CSF PAI-1 concentrations and age in either patients or controls. Similarly, there was no association between CSF PAI-1 concentrations and urokinase-type plasminogen activator (uPA). CONCLUSIONS: Raised CSF PAI-1 concentrations may be used as a non-specific marker of neurological disease. Moreover, PAI-1 may play an important role in regulating the functions tPA, and probably uPA, in CSF.     

Fracture incidence in England and Wales: a study based on the population of Cardiff

Despite the importance of fractures as an economic and health problem, and consequent interest in osteoporosis, few workers have previously attempted to define the overall incidence of fracture. This population based study was based in the Accident and Emergency Department of Cardiff Royal Infirmary and identified all patients presenting with fractures of any type. Over a single year a total of 6467 fractures were identified among the 306,600 people who live in the city of Cardiff. This gives an overall fracture incidence of 21.1/1000/year, (23.5/1000/year in males and 18.8/1000/year in females); a result very similar to those from similar work in the USA, Australia and Norway. This result is over twice the previous estimate of fracture incidence in the UK; the figure of 9/1000/year from the only equivalent study performed since the 1960s. In part, this discrepancy appears to reflect our more rigorous definition of the study population, and our improved ascertainment of minor fractures. We believe our result to offer the most accurate estimate of fracture incidence currently available for a UK population.     

Nasal pleomorphic adenoma with skeletal muscle differentiation: potential misdiagnosis as rhabdomyosarcoma

Pleomorphic adenoma can show diverse lines of differentiation in the epithelial and myoepithelial elements, such as cartilage, bone, and fat. Myoid differentiation, however, has not been documented. We report an unusual case of nasal pleomorphic adenoma which shows focal skeletal muscle differentiation. The tumor was discovered only after successful radiation therapy for an undifferentiated carcinoma of the nasopharynx. Apart from being of morphological interest, the presence of cells with skeletal muscle differentiation also raises the practical issue of possible confusion with rhabdomyosarcoma in a biopsy. The distinguishing features are lack of cytological atypia and presence of a neoplastic glandular element.     

Staff attitudes that impede the implementation of behavioral treatment programs

The formation of cardiac cushion tissue, which ultimately contributes to formation of the valves and septa, is dependent on the regional activation of cardiac endothelial cells to undergo an epithelial-mesenchymal transition. This endothelial transition was correlated with activin betaA mRNA expression by Northern and in situ hybridization in both a temporal and spatial manner in developing mouse embryos. Activin betaA was the only subunit of the inhibin family detected during the initial phase of endothelial cell transition; activin betaB was detected at later stages, and inhibin alpha was not detectable in the heart. An in vitro assay that has been used to study mesenchymal cell formation in chick was modified for use with mammalian embryos. Conditioned media from embryonic mouse cardiocyte cultures was shown to substitute for the endogenous inductive signal in these assays. The presence of activin betaA was demonstrated by Western blot analysis of the cardiocyte conditioned media (CCM). Modified antisense oligonucleotides to activin betaA inhibited the endothelial-mesenchymal transition in the assay system, which was not affected by control oligonucleotides. Adapting the avian culture system for use with mice enabled the use of tissue from mice with a null allele for activin betaA. CCM produced from embryos homozygous for the mutant betaA allele did not contain activin betaA and was used in in vitro assays. CCM lacking activin betaA produced fewer mesenchymal cells from cardiac endothelial monolayers than CCM with activin betaA. Localized expression of activin betaA in the embryonic heart indicates a possible role in the endothelial-mesenchymal transition. Bioassays in which activin betaA expression is blocked or activin betaA is absent from the media indicate that activin betaA promotes the formation of mesenchymal cells in the endothelial cushions, which are required for normal septation.     

Computerised infrared imaging system for studying thermal activation on the skull following somatic stimulation in small animals

Stress radionuclide myocardial perfusion imaging and stress echocardiography are noninvasive imaging techniques with high diagnostic and prognostic utility. Previously, patient cohorts for studies using these methods have comprised predominantly men, but recent investigations have focused on women. Stress myocardial perfusion imaging is highly accurate for diagnosing coronary disease in women, particularly with newer techniques such as gated single-photon emission computed tomography, and has been shown to be a powerful prognostic predictor in both women and men. Comparable data for stress echocardiography are emerging. Older studies reported that for similar image findings fewer women than men were referred for invasive procedures, however, newer studies suggest an absence of such a gender bias. Further developments in attenuation correction for perfusion imaging and phase-contrast magnetic resonance imaging promise to enhance the utility of noninvasive imaging for both men and women.     

Left ventricular cavity obliteration during dobutamine stress echocardiography is associated with female sex and left ventricular size and function

After a left pneumonectomy, thoracoscopic closure with fibrin glue was performed for a fistula on the bronchial stump and the postoperative state progressed favorably thereafter. In this paper, we report on this successful case. Case: A 61 year-old male, who underwent a left pneumonectomy on January 17, 1996 for pulmonary carcinoma (T 3 N 1M 0 stage III A). The bronchial stump was covered with anterior serratus muscle flap. On April 1 (the 76th postoperative day), after two courses of Carboplatin and Vindesine treatment, the patient suddenly developed a fistula on the bronchial stump. Bronchofiberscopic closure with fibrin glue was attempted, but failed to close the fistula. Thoracoscopic surgery was then performed on May 15 (the 45th day after the onset of the fistula). After the intrathoracic opening of the fistula was found with a contrast medium, fibrin glue was injected to fill up to the bronchial stump, and communication with the thoracic cavity was blocked. Owing to coverage with a myocutaneous flap, the patient's general postoperative state remained relatively stable. Thoracoscopic surgery is useful as a treatment for some cases of bronchial stump fistula after pneumonectomy.