430 research outputs found
Focusing Qualitative Simulation Using Temporal Logic: Theoretical Foundations
No full textthis paper took place while the author was visiting the Qualitative Reasoning Group at the Dept. of Computer Sciences of the University of Texas at Austin. G. Brajnik and D.J. Clancy / Focusing qualitative simulation 2 formation about the trajectory of a variable or relationships between the trajectories of interconnected variables. Such information allows the modeler to restrict the simulation to a region of the state space and to specify time--varying input variables. The Temporally Constrained Qsim (TeQsim, pronounced tek'sim) algorithm combines the expressive power of these two paradigms by interleaving temporal logic model checking with qualitative simulation. Temporal logic is used to specify qualitative and quantitative trajectory information that is incorporated into the simulation to constrain and refine the resulting behaviors. Qualitative simulation constructs a set of possible behaviors consistent with a model of a dynamical system represented by a qualitative differential equation (QDE). The Qsi
Behavior Abstraction for Tractable Simulation
No full textion for Tractable Simulation Daniel J. Clancy and Benjamin Kuipers Department of Computer Sciences University of Texas at Austin Austin, Texas 78712 [email protected] and [email protected] Abstract Most qualitative simulation techniques perform simulation at a single level of detail highlighting a fixed set of distinctions. This can lead to intractable branching within the behavioral description. The complexity of the simulation can be reduced by eliminating uninteresting distinctions. Behavior abstraction provides a hierarchy of behavioral descriptions allowing the modeler to select the appropriate level of description highlighting the relevant distinctions. Two abstraction techniques are presented. Behavior aggregation eliminates occurrence branching by providing a hybrid between a behavior tree representation and a history based description. Chatter box abstraction uses attainable envisionment to eliminate intractable branching due to chatter within a behavior tree simulat..
Dynamic Chatter Abstraction: A scalable technique for avoiding irrelevant distinctions during qualitative simulation
No full textion: A scalable technique for avoiding irrelevant distinctions during qualitative simulation Daniel J. Clancy and Benjamin Kuipers Department of Computer Sciences University of Texas at Austin, Texas 78712 [email protected] and [email protected] Abstract One of the major factors hindering the use of qualitative simulation techniques to reason about the behavior of complex dynamical systems is intractable branching due to a phenomenon called chatter. Chatter occurs when a variable's direction of change is constrained only by continuity within a region of the state space. This results in intractable, potentially infinite branching within the behavioral description due to irrelevant distinctions in the direction of change. Dynamic chatter abstraction provides a general purpose, scalable solution that abstracts chattering regions of the state space into a single state within the behavioral description. Chattering regions are identified via a dynamic analysis of the model and the ..
Trajectory constraints in qualitative simulation
No full textWe present a method
for specifying
temporal
con-
straints on trajectories
of dynamical
systems and en-
forcing them during qualitative
simulation.
This ca-
pability can be used to focus a simulation,
simulate
non-autonomous
and piecewise-continuous
systems,
reason about boundary
condition problems and incor-
porate observations
into the simulation.
The method
has been implemented
in TeQSIM, a qualitative simu-
lator that combines the expressive power of qualitative
differential
equations
with temporal
logic.
It inter-
leaves temporal
logic model checking with the simu-
lation to constrain
and refine the resulting predicted
behaviors and to inject discontinuous
changes into the
simulation
Poiesis and Obstruction in Art Practice
No full textThis PhD thesis examines the concept of poiesis, that is ‘calling into existence that which was not there before’, in the context of obstruction in studio practice. It poses the question ‘Is there a methodology that engages with obstruction which in turn calls new work’? In this thesis, the concept of poiesis emerging from the late Dr. Murray Cox’s ‘Aeolian Mode’, is analyzed alongside a concept of praxis, (a philosophical companion to poiesis), familiar to artistic practice. This thesis describes the orientation of the original idea, The Aeolian Mode, clinically developed by Dr. Murray Cox in Broadmoor Psychiatric Hospital. This PhD seeks to identify if there are similar ‘tenets of approach’ held within the methodology of ‘The Aeolian Mode’, that would be useful or are identifiable in artistic studio practice. This thesis draws on the work of the philosopher, Professor Richard Kearney, specifically Kearney’s ideas on the necessity of ‘the other’ for ‘radical possibility’ to occur. It maps a context of both Freudian and Jungian interpretations of art practice, identifying how these ideas have shaped the way art is seen today. Furthermore, it challenges the Freudian idea of ‘pathography’ and favours a Jungian approach of ‘individuation’ in the understanding of creative processes. It develops a ‘methodology of the conversation’, interviewing students, established artists, tutors about their approaches to obstruction/poiesis in art practice. Additionally, it examines my own obstruction to painting and identifies the methodology that released me from this obstruction. Conducting these interviews on art practice has enabled me to confirm my initial concerns about Freudian ‘pathography’ whilst validating the possibility of the Jungian concept of ‘individuation’ being of use to art practice. Finally, this PhD discusses the implications for further study and research, which have emerged during the ‘methodology of the conversation’ and the task of dissolving my obstruction to painting
Mitral valve repair and bioprosthetic replacement without postoperative anticoagulation does not increase the risk of stroke or mortality
No full textObjectives: The study aimed to determine if mitral valve repair (MVRR) or bioprosthetic mitral valve replacement (BMVR) without postoperative anticoagulation is associated with a similar risk of thromboembolism and death as anticoagulation. Methods: We retrospectively reviewed our 2004-09 experience in 249 MVRR and bioprosthetic replacement patients (53percent female; 63 year mean age). Concurrent procedures principally included antiarrhythmic surgery, aortic valve replacement, tricuspid valve repair and coronary bypass grafting. Warfarin therapy was instituted at the discretion of the surgeon. Thirty-day, a period known to have the highest risk of valve-related thromboembolism, outcomes were compared relying on the incidence of stroke and death as surrogates of thromboembolic complications. Intermediate-term survival was compared between the groups using Cox proportional hazard models. The mean follow-up was 2.9 years. Given the non-randomized warfarin use, a propensity score using patient comorbidities and concurrent procedures was created and added to the Cox models. Results: One hundred and ninety-two (77percent) patients were discharged on warfarin and 57 (23percent) were discharged without warfarin. Thirty-day mortality in patients discharged from the index hospitalization was 1.2percent and was similar for the two groups (P = 0.99). Four ischaemic perioperative strokes were detected; 3 in the warfarin group and 1 in the no warfarin group (P = 0.99). Overall survival was 84percent, with 84percent survival in the warfarin group and 86percent in the no warfarin group (P = 0.79). Bleeding complications were comparable between the two groups (P = 0.72). In a multivariate analysis, warfarin was not related to mortality. Conclusions: Despite current guidelines recommending postoperative anticoagulation following MVRR or bioprosthetic replacement, the avoidance of warfarin does not increase perioperative complications and has no impact on intermediate survival. Accordingly, a prospective randomized study to adjudicate the role of extended warfarin thromboprophylaxis in mitral valve surgery is warranted. © The Author 2012. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.Akins CW, 2008, EUR J CARDIO-THORAC, V33, P523, DOI 10.1016-j.ejcts.2007.12.055; Alfieri O, 2001, J THORAC CARDIOV SUR, V122, P674, DOI 10.1067-mtc.2001.117277; Aramendi JL, 1998, J HEART VALVE DIS, V7, P610; Asopa Sanjay, 2006, Interact Cardiovasc Thorac Surg, V5, P761, DOI 10.1510-icvts.2006.143099; Bonow Robert O, 2008, Circulation, V118, pe523, DOI 10.1161-CIRCULATIONAHA.108.190748; Budnitz Daniel S, 2011, N Engl J Med, V365, P2002, DOI 10.1056-NEJMsa1103053; Butchart EG, 2005, EUR HEART J, V26, P2463, DOI 10.1093-eurheartj-ehi426; CARPENTIER A, 1980, J THORAC CARDIOV SUR, V79, P338; Colli A, 2010, J HEART VALVE DIS, V19, P405; EBERLEIN U, 1990, EUR J CARDIO-THORAC, V4, P605, DOI 10.1016-1010-7940(90)90020-Z; EDMUNDS LH, 1987, ANN THORAC SURG, V44, P430; EDMUNDS LH, 1988, ANN THORAC SURG, V46, P257; Geerts WH, 2008, CHEST, V133, p381S, DOI 10.1378-chest.08-0656; Gherli T, 2004, CIRCULATION, V110, P496, DOI 10.1161-01.CIR.0000137122.95108.52; HERAS M, 1995, J AM COLL CARDIOL, V25, P1111, DOI 10.1016-0735-1097(94)00563-6; HORSTKOTTE D, 1998, J THROMB THROMBOLYS, V5, pS19; Horstkotte D, 1995, J Heart Valve Dis, V4, P114; LAWRIE GM, 2012, 48 SOC THORAC SUG AN; NUNEZ L, 1984, ANN THORAC SURG, V37, P84; NUNEZ L, 1982, ANN THORAC SURG, V33, P354; Ruel M, 2004, ANN THORAC SURG, V78, P77, DOI 10.1016-j.athorascur.2003.12.058; Russo A, 2008, J AM COLL CARDIOL, V51, P1203, DOI 10.1016-j.jacc.2007.10.058; Salem DN, 2008, CHEST, V133, p593S, DOI 10.1378-chest.08-0724; Vahanian A, 2007, EUR HEART J, V28, P230, DOI 10.1093-eurheartj-ehl428; Vaughan P, 2005, J HEART VALVE DIS, V14, P57620
J Child Psychol Psychiatry
No full textBackground:Extensive literature in human and animal models has documented an association between maternal smoking during pregnancy and externalizing behavior in offspring. It remains unclear, however, the extent to which postnatal environmental smoke exposure is associated with behavioral development, particularly for children whose mothers did not smoke during pregnancy. The present study examined whether magnitude of exposure to environmental smoke across the first four years of life demonstrated a linear association with later externalizing symptoms.Methods:Exposure was quantified through salivary cotinine measured when children were 6, 15, 24, and 48 months of age, providing a more accurate quantification of realized exposure than can be estimated from parental-report of cigarettes smoked. Data were available for n = 1,096 (50% male; 44% African American) children recruited for the Family Life Project, a study of child development in areas of rural poverty.Results:Analyses indicate a linear association between cotinine and children\u2019s symptoms of hyperactivity and conduct problems. This association remained significant after controlling for family poverty level, parental education, parental history of ADHD, hostility, depression, caregiver IQ, and obstetric complications. Furthermore, this association was unchanged when excluding mothers who smoked during pregnancy from the model.Conclusions:Findings are consistent with animal models demonstrating an effect of environmental exposure to nicotine on ongoing brain development in regions related to hyperactivity and impulsivity, and highlight the importance of mitigating children\u2019s exposure to environmental smoke, including sources that extend beyond the parents.R01 HD081252/HD/NICHD NIH HHS/United StatesP01HD039667/Eunice Kennedy Shriver National Institute of Child Health and Human Development/UG3 OD023332/CD/ODCDC CDC HHS/United StatesUG3 OD023332/OD/NIH HHS/United StatesUH3 OD023332/OD/NIH HHS/United StatesUH3OD023332-01/NIH Office of the Director
An endoscopic structured light system using multispectral detection
No full textPURPOSE: In clinical examinations, the tissue surface topology is an important feature for detecting the tissue pathology and implementing augmented reality. We have previously presented a miniaturised structured light (SL) system for recovery of tissue surface shape in minimally invasive surgery (MIS), based on a flexible multispectral structured illumination probe (1.9 mm diameter) (Clancy et al. in Biomed Opt Express 2(11):3119-3128, 2011. doi: 10.1364/BOE.2.003119 ). This paper reports further hardware and analytical developments to improve the light pattern decoding result and increase the reconstruction accuracy. METHODS: The feasibility of using an 8-band multispectral camera with higher pattern-colour discrimination ability than normal RGB camera in this system was studied. Additionally, the "normalised cut" algorithm was investigated to improve pattern segmentation. RESULTS: The whole SL system was evaluated by phantom and in vivo experiments. Higher pattern identification performance than that of an RGB camera was recorded by using the multispectral camera (average precision >97 %, average sensitivity >62 %). An average of [Formula: see text] reconstruction error was achieved using the proposed pattern decoding method on a heart phantom at a working distance of approximately 10 cm. CONCLUSIONS: The experiment showed the superiority of the multispectral camera over the RGB camera in the spot identification step. The proposed pattern decoding algorithm underwent evaluations using different experiments, showing that it provided promising reconstruction results. The potential of using this system in MIS environments has been demonstrated
Reductions in cardiovascular, cerebrovascular, and respiratory mortality following the national Irish smoking ban: Interrupted time-series analysis
No full textCopyright @ 2013 Stallings-Smith et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This article has been made available through the Brunel Open Access Publishing Fund.Background: Previous studies have shown decreases in cardiovascular mortality following the implementation of comprehensive smoking bans. It is not known whether cerebrovascular or respiratory mortality decreases post-ban. On March 29, 2004, the Republic of Ireland became the first country in the world to implement a national workplace smoking ban. The aim of this study was to assess the effect of this policy on all-cause and cause-specific, non-trauma mortality. Methods: A time-series epidemiologic assessment was conducted, utilizing Poisson regression to examine weekly age and gender-standardized rates for 215,878 non-trauma deaths in the Irish population, ages ≥35 years. The study period was from January 1, 2000, to December 31, 2007, with a post-ban follow-up of 3.75 years. All models were adjusted for time trend, season, influenza, and smoking prevalence. Results: Following ban implementation, an immediate 13% decrease in all-cause mortality (RR: 0.87; 95% CI: 0.76-0.99), a 26% reduction in ischemic heart disease (IHD) (RR: 0.74; 95% CI: 0.63-0.88), a 32% reduction in stroke (RR: 0.68; 95% CI: 0.54-0.85), and a 38% reduction in chronic obstructive pulmonary disease (COPD) (RR: 0.62; 95% CI: 0.46-0.83) mortality was observed. Post-ban reductions in IHD, stroke, and COPD mortalities were seen in ages ≥65 years, but not in ages 35-64 years. COPD mortality reductions were found only in females (RR: 0.47; 95% CI: 0.32-0.70). Post-ban annual trend reductions were not detected for any smoking-related causes of death. Unadjusted estimates indicate that 3,726 (95% CI: 2,305-4,629) smoking-related deaths were likely prevented post-ban. Mortality decreases were primarily due to reductions in passive smoking. Conclusions: The national Irish smoking ban was associated with immediate reductions in early mortality. Importantly, post-ban risk differences did not change with a longer follow-up period. This study corroborates previous evidence for cardiovascular causes, and is the first to demonstrate reductions in cerebrovascular and respiratory causes
Making Savers Winners: An Overview of Prize-Linked Savings Products
No full textFor over three centuries and throughout the globe, people have enthusiastically bought savings products that incorporate lottery elements. In lieu of paying traditional interest to all investors proportional to their balances, these Prize Linked Savings (PLS) accounts distribute periodic sizeable payments to some investors using a lottery-like drawing where an investor’s chances of winning are proportional to one’s account balances. This paper describes these products, provides examples of their use, argues for their potential popularity in the United States —especially to low and moderate income non-savers—and discusses the laws and regulations in the United States that largely prohibit their issuance.
- …
