Level-of-detail for cognitive real-time characters

We present a solution for the real-time simulation of artificial environments containing cognitive and hierarchically organized agents at constant rendering framerates. We introduce a level-of-detail concept to behavioral modeling, where agents populating the world can be both reactive and proactive. The disposable time per rendered frame for behavioral simulation is variable and determines the complexity of the presented behavior. A special scheduling algorithm distributes this time to the agents depending on their level-of-detail such that visible and nearby agents get more time than invisible or distant agents. This allows for smooth transitions between reactive and proactive behavior. The time available per agent influences the proactive behavior, which becomes more sophisticated because it can spend time anticipating future situations. Additionally, we exploit the use of hierarchies within groups of agents that allow for different levels of control. We show that our approach is well-suited for simulating environments with up to several hundred agents with reasonable response times and the behavior adapts to the current viewpoin

Experimental and numerical study of microstructure formation and the origin of crystallographic misorientation in Al-Zn-Si alloy coatings

Al-Zn-Si alloy coatings are widely used for the corrosion protection of steel sheets. In addition to the favorable corrosion properties, the Al-43wt%Zn-1.6wt%Si coatings present several features which are of metallurgical interest. The first one is their surface appearance dominated by the typical spangle morphology exhibiting dull and shiny areas on the coating surface. Further on, the dendrite tips do apparently not grow along the 〈100〉 crystallographic directions that are typical for fcc-metals, but rather along directions in between 〈100〉 and 〈110〉. In addition, continuous variations of the crystallographic orientation, up to 35°, are observed within individual grains of Al-Zn-Si coatings [Sémoroz1 01]. The objective of the present study is to establish a better understanding of the microstructure development which is responsible for the formation of both the characteristic spangle pattern and the important variations of crystallographic orientation within the grains. In order to elucidate these questions, the present study includes three main axes, (i) a detailed microstructure characterization of industrially solidified samples, (ii) modeling work which encompasses microstructure modeling by the phase field method and a geometrical model, as well as the determination of the solid-liquid interfacial energy anisotropy by an inverse method, and (iii) re-solidification experiments aimed at studying the behavior of Al-Zn-Si layers under modified solidification conditions. The results show that the dendrite network spreads quickly in the coating layer at a temperature between 530 to 535°C. During growth, the dendrite tips are separated from the confining boundaries by a thin, solute-rich liquid film. It was found that the preferred dendrite growth directions are in between 〈100〉 and 〈110〉, 28.5° from 〈100〉. Further on, a mathematical expression for the interfacial energy anisotropy of the considered alloy has been determined. The combination of the geometrical model and surface topography measurements allowed concluding that the spangle pattern is due to preferential dendrite growth along one of the two boundaries confining the melt layer. In addition, the new experimental evidence forced to discard the mechanisms previously proposed for the formation of intragranular crystallographic misorientations. The experimental findings acquired during this study indicate that the solidification shrinkage occurring in the area of the grain envelope is the driving force for the formation of the observed intragranular misorientations. The solidification shrinkage leads to the development of tensile stresses in the oxide film covering the coating while it solidifies. These stresses apply on the dendrite network and lead to plastic deformation in the tip area of the growing dendrite arms

Value of fecal calprotectin in the evaluation of patients with abdominal discomfort: an observational study

<p>Abstract</p> <p>Background</p> <p>The evaluation of patients with abdominal discomfort is challenging and patient selection for endoscopy based on symptoms is not reliable. We evaluated the diagnostic value of fecal calprotectin in patients with abdominal discomfort.</p> <p>Methods</p> <p>In an observational study, 575 consecutive patients with abdominal discomfort referred for endoscopy to the Department of Gastroenterology & Hepatology at the University Hospital Basel in Switzerland, were enrolled in the study. Calprotectin was measured in stool samples collected within 24 hours before the investigation using an enzyme-linked immunosorbent assay. The presence of a clinically significant finding in the gastrointestinal tract was the primary endpoint of the study. Final diagnoses were adjudicated blinded to calprotectin values.</p> <p>Results</p> <p>Median calprotectin levels were higher in patients with significant findings (N = 212, median 97 μg/g, IQR 43-185) than in patients without (N = 326, 10 μg/g, IQR 10-23, P < 0.001). The area under the receiver operating characteristics curve (AUC) to identify a significant finding was 0.877 (95% CI, 0.85-0.90). Using 50 μg/g as cut off yielded a sensitivity of 73% and a specificity of 93% with good positive and negative likelihood ratios (10.8 and 0.29, respectively). Fecal calprotectin was useful as a diagnostic parameter both for findings in the upper intestinal tract (AUC 0.730, 0.66-0.79) and for the colon (AUC 0.912, 0.88-0.94) with higher diagnostic precision for the latter (P < 0.001). In patients > 50 years, the diagnostic precision remained unchanged (AUC 0.889 vs. 0.832, P = 0.165).</p> <p>Conclusion</p> <p>In patients with abdominal discomfort, fecal calprotectin is a useful non-invasive marker to identify clinically significant findings of the gastrointestinal tract, irrespective of age.</p

Management of medication overuse (MO) and medication overuse headache (MOH) S1 guideline.

INTRODUCTION Chronic headache due to the overuse of medication for the treatment of migraine attacks has a prevalence of 0.5-2.0%. This guideline provides guidance for the management of medication overuse (MO) and medication overuse headache (MOH). RECOMMENDATIONS Treatment of headache due to overuse of analgesics or specific migraine medications involves several stages. Patients with medication overuse (MO) or medication overuse headache (MOH) should be educated about the relationship between frequent use of symptomatic headache medication and the transition from episodic to chronic migraine (chronification), with the aim of reducing and limiting the use of acute medication. In a second step, migraine prophylaxis should be initiated in patients with migraine and overuse of analgesics or specific migraine drugs. Topiramate, onabotulinumtoxinA and the monoclonal antibodies against CGRP or the CGRP-receptor are effective in patients with chronic migraine and medication overuse. In patients with tension-type headache, prophylaxis is performed with amitriptyline. Drug prophylaxis should be supplemented by non-drug interventions. For patients in whom education and prophylactic medication are not effective, pausing acute medication is recommended. This treatment can be performed in an outpatient, day hospital or inpatient setting. Patients with headache due to overuse of opioids should undergo inpatient withdrawal. The success rate of the stepped treatment approach is 50-70% after 6 to 12 months. A high relapse rate is observed in patients with opioid overuse. Tricyclic antidepressants, neuroleptics (antiemetics) and the administration of steroids are recommended for the treatment of withdrawal symptoms or headaches during the medication pause. Consistent patient education and further close monitoring reduce the risk of relapse

Computing the shortest elementary flux modes in genome-scale metabolic networks

This article is available open access through the publisher’s website through the link below. Copyright @ The Author 2009.Motivation: Elementary flux modes (EFMs) represent a key concept to analyze metabolic networks from a pathway-oriented perspective. In spite of considerable work in this field, the computation of the full set of elementary flux modes in large-scale metabolic networks still constitutes a challenging issue due to its underlying combinatorial complexity. Results: In this article, we illustrate that the full set of EFMs can be enumerated in increasing order of number of reactions via integer linear programming. In this light, we present a novel procedure to efficiently determine the K-shortest EFMs in large-scale metabolic networks. Our method was applied to find the K-shortest EFMs that produce lysine in the genome-scale metabolic networks of Escherichia coli and Corynebacterium glutamicum. A detailed analysis of the biological significance of the K-shortest EFMs was conducted, finding that glucose catabolism, ammonium assimilation, lysine anabolism and cofactor balancing were correctly predicted. The work presented here represents an important step forward in the analysis and computation of EFMs for large-scale metabolic networks, where traditional methods fail for networks of even moderate size. Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics online (http://bioinformatics.oxfordjournals.org/cgi/content/full/btp564/DC1).Fundação Calouste Gulbenkian, Fundação para a Ciência e a Tecnologia (FCT) and Siemens SA Portugal

Inferring differentiation pathways from gene expression

Motivation: The regulation of proliferation and differentiation of embryonic and adult stem cells into mature cells is central to developmental biology. Gene expression measured in distinguishable developmental stages helps to elucidate underlying molecular processes. In previous work we showed that functional gene modules, which act distinctly in the course of development, can be represented by a mixture of trees. In general, the similarities in the gene expression programs of cell populations reflect the similarities in the differentiation path

Level-of-detail for cognitive real-time characters

ISSN:0178-2789ISSN:1432-231

Towards a Game Agent

The objective of this report is to give the reader a survey on state-of-the-art techniques and academic research in the field of artificial life where the simulation of complex and emergent behavior is the central point of investigation. Furthermore, games, artificial intelligence, and the concept of agents are focussed to give a classification and comparison of modern techniques used to simulate and/or animate creatures and other life-like forms