Scaling behavior of random knots.

Using numerical simulations we investigate how overall dimensions of random knots scale with their length. We demonstrate that when closed non-self-avoiding random trajectories are divided into groups consisting of individual knot types, then each such group shows the scaling exponent of approximately 0.588 that is typical for self-avoiding walks. However, when all generated knots are grouped together, their scaling exponent becomes equal to 0.5 (as in non-self-avoiding random walks). We explain here this apparent paradox. We introduce the notion of the equilibrium length of individual types of knots and show its correlation with the length of ideal geometric representations of knots. We also demonstrate that overall dimensions of random knots with a given chain length follow the same order as dimensions of ideal geometric representations of knots.

ACACIA: an agent-based program for simulating behavior to reach long-term goals

We present ACACIA, an agent-based program implemented in Java StarLogo 2.0 that simulates a two-dimensional microworld populated by agents, obstacles and goals. Our program simulates how agents can reach long-term goals by following sensorial-motor couplings (SMCs) that control how the agents interact with their environment and other agents through a process of local categorization. Thus, while acting in accordance with this set of SMCs, the agents reach their goals through the emergence of global behaviors. This agent-based simulation program would allow us to understand some psychological processes such as planning behavior from the point of view that the complexity of these processes is the result of agent-environment interaction.

A simple model to describe the thixotropic behavior of paints.

We propose a simple rheological model to describe the thixotropic behavior of paints, since the classical hysteresis area, which is usually used, is not enough to evaluate thixotropy. The model is based on the assumption that viscosity is a direct measure of the structural level of the paint. The model depends on two equations: the Cross-Carreau equation to describe the equilibrium viscosity and a second order kinetic equation to express the time dependence of viscosity. Two characteristic thixotropic times are differentiated: one for the net structure breakdown, which is defined as a power law function of shear rate, and an other for the net structure buildup, which is not dependent on the shear rate. The knowledge of both kinetic processes can be used to improve the quality and applicability of paints. Five representative commercial protective marine paints are tested. They are based on chlorinated rubber, acrylic, alkyd, vinyl, and epoxy resins. The temperature dependence of the rheological behavior is also studied with the temperature ranging from 5 ºC to 35 ºC. It is found that the paints exhibit both shear thinning and thixotropic behavior. The model fits satisfactorily the thixotropy of the studied paints. It is also able to predict the thixotropy dependence on temperature. Both viscosity and the degree of thixotropy increase as the temperature decreases.

The Use of virtual reality in the study of people's responses to violent incidents

This paper reviews experimental methods for the study of the responses of people to violence in digital media, and in particular considers the issues of internal validity and ecological validity or generalisability of results to events in the real world. Experimental methods typically involve a significant level of abstraction from reality, with participants required to carry out tasks that are far removed from violence in real life, and hence their ecological validity is questionable. On the other hand studies based on fi eld data, while having ecological validity, cannot control multiple confounding variables that may have an impact on observed results, so that their internal validity is questionable. It is argued that immersive virtual reality may provide a unifi cation of these two approaches. Since people tend to respond realistically to situations and events that occur in virtual reality, and since virtual reality simulations can be completely controlled for experimental purposes, studies of responses to violence within virtual reality are likely to have both ecological and internal validity. This depends on a property that we call"plausibility"- including the fi delity of the depicted situation with prior knowledge and expectations. We illustrate this with data from a previously published experiment, a virtual reprise of Stanley Milgram"s 1960s obedience experiment, and also with pilot data from a new study being developed that looks at bystander responses to violent incidents.

Behavior of propagating and evanescent components in azimuthally polarized non-paraxial fields

The contribution of the propagating and the evanescent waves associated with freely propagating non-paraxial light fields whose transverse component is azimuthally polarized at some plane is investigated. Analytic expressions are derived for describing both the spatial shape and the relative weight of the propagating and the evanescent components integrated over the transverse plane. The analysis is carried out within the framework of the plane-wave angular spectrum approach. These results are used to illustrate the behavior of a kind of donut-like beams with transverse azimuthal polarization at some plane.

History of offending behavior in first episode psychosis patients : a marker of specific clinical needs and a call for early detection strategies among young offenders

Plusieurs études suggèrent que les patients qui présentent un premier épisode psychotique et un passé délictueux présenteraient une clinique spécifique et nécessiteraient une prise en charge adaptée. A partir d'une cohorte de patients suivis pour un premier épisode psychotique dans la région de Melbourne {The Early Psychosis Prevention and Intervention Centre), nous avons analysé la prévalence d'actes délictueux dans leur passé (1), les caractéristiques cliniques à leur admission (2), l'évolution à court terme des patients ayant commis des délits par rapport aux autres patients (3). Nous avons également cherché à déterminer si des délits plus graves (atteinte à l'intégrité d'une personne) étaient corrélés à des caractéristiques cliniques particulières. Sur les 649 patients dont les données ont pu être analysées entre 1998 et 2000, 29% avaient un passé délictueux. Ils étaient en majorité des hommes et présentaient des difficultés sociales et scolaires plus importantes que les autres patients. Ils avaient également recours de manière plus régulière à des substances illicites et commis plus souvent des tentatives de suicide. Le tableau clinique qu'ils présentaient à leur admission dans le programme de soins était plus complexe et l'évolution globalement plus défavorable après 18 mois de traitement. Nous avons relevé aussi que la durée de psychose non traitée était plus longue que celle des autres patients. Enfin, les délits avec atteinte à l'intégrité d'une autre personne étaient plus fréquents en présence d'un insight faible et nécessitaient un plus grand nombre d'hospitalisation. Ces résultats confirment le besoin d'une recherche approfondie dans ce champ de la clinique et de stratégies de prévention et de soins plus spécifiques. Une détection précoce chez les jeunes hommes qui commettent des actes délictueux serait particulièrement importante puisque notre étude suggère que certains d'entre eux seraient dans une phase débutante et non reconnue d'un épisode psychotique. Une intervention plus rapide et adaptée pourrait avoir des conséquences positives à plusieurs niveaux.

Characterization Method for Comminution Behavior of Limestone and Fuel Ash in a Circulating Fluidized Bed Boiler

Työn tavoite oli kehittää karakterisointimenetelmät kalkkikiven ja polttoaineen tuhkan jauhautumisen ennustamiselle kiertoleijukattilan tulipesässä. Kiintoainekäyttäytymisen karakterisoinnilla ja mallintamisella voidaan tarkentaa tulipesän lämmönsiirron ja tuhkajaon ennustamista. Osittain kokeelliset karakterisointimenetelmät perustuvat kalkkikiven jauhautumiseen laboratoriokokoluokan leijutetussa kvartsiputkireaktorissa ja tuhkan jauhatumiseen rotaatiomyllyssä. Karakterisointimenetelmät ottavat huomioon eri-laiset toimintaolosuhteet kaupallisen kokoluokan kiertoleijukattiloissa. Menetelmät kelpoistettiin kaupallisen kokoluokan kiertoleijukattiloista mitattujen ja fraktioittaisella kiintoainemallilla mallinnettujen taseiden avulla. Kelpoistamistaseiden vähäisyydestä huolimatta karakterisointimenetelmät arvioitiin virhetarkastelujen perusteella järkeviksi. Karakterisointimenetelmien kehittämistä ja tarkentamista tullaan jatkamaan.

Bystander responses to a violent incident in an immersive virtual environment

Under what conditions will a bystander intervene to try to stop a violent attack by one person on another? It is generally believed that the greater the size of the crowd of bystanders, the less the chance that any of them will intervene. A complementary model is that social identity is critical as an explanatory variable. For example, when the bystander shares common social identity with the victim the probability of intervention is enhanced, other things being equal. However, it is generally not possible to study such hypotheses experimentally for practical and ethical reasons. Here we show that an experiment that depicts a violent incident at life-size in immersive virtual reality lends support to the social identity explanation. 40 male supporters of Arsenal Football Club in England were recruited for a two-factor between-groups experiment: the victim was either an Arsenal supporter or not (in-group/out-group), and looked towards the participant for help or not during the confrontation. The response variables were the numbers of verbal and physical interventions by the participant during the violent argument. The number of physical interventions had a significantly greater mean in the ingroup condition compared to the out-group. The more that participants perceived that the Victim was looking to them for help the greater the number of interventions in the in-group but not in the out-group. These results are supported by standard statistical analysis of variance, with more detailed findings obtained by a symbolic regression procedure based on genetic programming. Verbal interventions made during their experience, and analysis of post-experiment interview data suggest that in-group members were more prone to confrontational intervention compared to the out-group who were more prone to make statements to try to diffuse the situation.

Genetic origin of the relationship between parental negativity and behavior problems from early childhood to adolescence: A longitudinal genetically sensitive study.

Little is known about how genetic and environmental factors contribute to the association between parental negativity and behavior problems from early childhood to adolescence. The current study fitted a cross-lagged model in a sample consisting of 4,075 twin pairs to explore (a) the role of genetic and environmental factors in the relationship between parental negativity and behavior problems from age 4 to age 12, (b) whether parent-driven and child-driven processes independently explain the association, and (c) whether there are sex differences in this relationship. Both phenotypes showed substantial genetic influence at both ages. The concurrent overlap between them was mainly accounted for by genetic factors. Causal pathways representing stability of the phenotypes and parent-driven and child-driven effects significantly and independently account for the association. Significant but slight differences were found between males and females for parent-driven effects. These results were highly similar when general cognitive ability was added as a covariate. In summary, the longitudinal association between parental negativity and behavior problems seems to be bidirectional and mainly accounted for by genetic factors. Furthermore, child-driven effects were mainly genetically mediated, and parent-driven effects were a function of both genetic and shared-environmental factors.

Customer Expectations and Organizational Buying Behavior in the Flexible Packaging Markets

Tämä työ on tehty yhteistyössä kansainvälisen metsäteollisuusyrityksen Stora Enson kanssa. Työ on osa Stora Enson strategiaa kehitettäessä uusia ja innovatiivisia pakkausmateriaaleja ja ratkaisuja joustopakkausmarkkinoille. Työn päätavoitteina oli selvittää, millaisia odotuksia tuotemerkkienomistajilla ja jatkojalostajilla on joustopakkauksista ja kuinka pakkausten ostopäätökset syntyvät monitahoisessa liikeympäristössä. Työn teoreettinen viitekehys jaettiin kahteen osaan. Asiakasodotuksia lähestyttiin tutkimalla eri palvelu- ja tuotelaadun ulottuvuuksia, ja teollisuuden ostokäyttäytymistä tutkittiin organisaatioiden ostokäyttämistä kuvaavien mallien avulla. Työn empiirisessä osuudessa käytettiin laadullista tutkimusmenetelmää käsittäen asiakashaastatteluja lähinnä Yhdysvalloissa. Haastateltavat yritykset koostuivat maailman johtavista kuluttajatuotteita valmistavista yrityksistä sekä jatkojalostajista. Tutkimustulosten mukaan odotukset pakkauksista liittyvät lähinnä tuotteen suojaamiseen sekä myynnin edistämiseen. Pääodotuksina on myös saada mahdollisimman edullisia papereita, mahdollisimman hyvillä barrier- ja paino-ominaisuuksilla. Tutkimustulokset osoittavat myös, että paperiyhtiöt ovat epäonnistuneet tekemään itseään tunnetuksi teollisuudelle ja heidän odotetaan olevan tulevaisuudessa aggressiivisempia ja innovatiivisempia. Tuotemerkkienomistajat ostavat pakkaukset ja pakkausmateriaalit normaalisti mieluiten jatkojalostajiensa kautta, mutta silti he toivovat yhteistyötä paperintoimittajien kanssa kunhan vain myös jatkojalostajat sisällytetään toimintaan mukaan.

Risk Behavior and Reciprocity of Organ Donation Attitudes in Young Men.

BACKGROUND: Lack of donor organs remains a major obstacle in organ transplantation. Our aim was to evaluate (1) the association between engaging in high-risk recreational activities and attitudes toward organ donation and (2) the degree of reciprocity between organ acceptance and donation willingness in young men. METHODS: A 17-item, close-ended survey was offered to male conscripts ages 18 to 26 years in all Swiss military conscription centers. Predictors of organ donation attitudes were assessed in bivariate analyses and multiple logistic regression. Reciprocity of the intentions to accept and to donate organs was assessed by means of donor card status. RESULTS: In 1559 responses analyzed, neither motorcycling nor practicing extreme sports reached significant association with donor card holder status. Family communication about organ donation, student, or academic profession and living in a Latin linguistic region were predictors of positive organ donation attitudes, whereas residence in a German-speaking region and practicing any religion predicted reluctance. Significantly more respondents were willing to accept than to donate organs, especially among those without family communication concerning organ donation. CONCLUSIONS: For the first time, it was shown that high-risk recreational activities do not influence organ donation attitudes. Second, a considerable discrepancy in organ donation reciprocity was identified. We propose that increasing this reciprocity could eventually increase organ donation rates.

The Reality of Neandertal Symbolic Behavior at the Grotte du Renne, Arcy-sur-Cure, France

The question of whether symbolically mediated behavior is exclusive to modern humans or shared with anatomically archaic populations such as the Neandertals is hotly debated. At the Grotte du Renne, Arcy-sur-Cure, France, the Châtelperronian levels contain Neandertal remains and large numbers of personal ornaments, decorated bone tools and colorants, but it has been suggested that this association reflects intrusion of the symbolic artifacts from the overlying Protoaurignacian and/or of the Neandertal remains from the underlying Mousterian.

Social sensing for psychology: Automated interpersonal behavior assessment

In this article, we show how the use of state-of-the-art methods in computer science based on machine perception and learning allows the unobtrusive capture and automated analysis of interpersonal behavior in real time (social sensing). Given the high ecological validity of the behavioral sensing, the ease of behavioral-cue extraction for large groups over long observation periods in the field, the possibility of investigating completely new research questions, and the ability to provide people with immediate feedback on behavior, social sensing will fundamentally impact psychology.

Quantifying insufficient coping behavior under chronic stress. A cross-cultural study of 1,303 students from Italy, Spain, and Argentina.

The question of how to quantify insufficient coping behavior under chronic stress is of major clinical relevance. In fact, chronic stress increasingly dominates modern work conditions and can affect nearly every system of the human body, as suggested by physical, cognitive, affective and behavioral symptoms. Since freshmen students experience constantly high levels of stress due to tight schedules and frequent examinations, we carried out a 3-center study of 1,303 students from Italy, Spain and Argentina in order to develop socioculturally independent means for quantifying coping behavior. The data analysis relied on 2 self-report questionnaires: the Coping Strategies Inventory (COPE) for the assessment of coping behavior and the Zurich Health Questionnaire which assesses consumption behavior and general health dimensions. A neural network approach was used to determine the structural properties inherent in the COPE instrument. Our analyses revealed 2 highly stable, socioculturally independent scales that reflected basic coping behavior in terms of the personality traits activity-passivity and defeatism-resilience. This replicated previous results based on Swiss and US-American data. The percentage of students exhibiting insufficient coping behavior was very similar across the study sites (11.5-18.0%). Given their stability and validity, the newly developed scales enable the quantification of basic coping behavior in a cost-efficient and reliable way, thus clearing the way for the early detection of subjects with insufficient coping skills under chronic stress who may be at risk of physical or mental health problems.