Agent-based dynamics in disaggregated growth models

This paper presents an agent-based model of disaggregated economic systems with endogenous growth features named Lagon GeneriC. This model is thought to represent a proof of concept that dynamically complete and highly disaggregated agent-based models allow to model economies as complex dynamical systems. It is used here for "theory generation", investigating the extension to a framework with capital accumulation of Gintis results on the dynamics of general equilibrium.Agent-based models, economic growth.

Can gossip change nutrition behaviour? Results of a mass media and community-based intervention trial in East Java, Indonesia.

OBJECTIVE: It is unclear how best to go about improving child feeding practices. We studied the effect of a novel behaviour change intervention, Gerakan Rumpi Sehat (the Healthy Gossip Movement), on infant and young child feeding practices in peri-urban Indonesia. METHODS: The pilot intervention was designed based on the principles of a new behaviour change theory, Behaviour Centred Design (BCD). It avoided educational messaging in favour of employing emotional drivers of behaviour change, such as affiliation, nurture and disgust and used television commercials, community activations and house-to-house visits as delivery channels. The evaluation took the form of a 2-arm cluster randomised trial with a non-randomised control arm. One intervention arm received TV only, while the other received TV plus community activations. The intervention components were delivered over a 3-month period in 12 villages in each arm, each containing an average of 1300 households. There were two primary outcomes: dietary diversity of complementary food and the provision of unhealthy snacks to children aged 6-24 months. RESULTS: Dietary diversity scores increased by 0.8 points in the arm exposed to TV adverts only (95% CI: 0.4-1.2) and a further 0.2 points in the arm that received both intervention components (95% CI: 0.6-1.4). In both intervention arms, there were increases in the frequency of vegetable and fruit intake. We found inconsistent evidence of an effect on unhealthy snacking. CONCLUSION: The study suggests that novel theory-driven approaches which employ emotional motivators are capable of having an effect on improving dietary diversity and the regularity of vegetable and fruit intake among children aged 6-24 months. Mass media can have a measurable effect on nutrition-related behaviour, but these effects are likely to be enhanced through complementary community activations. Changing several behaviours at once remains a challenge

Effects of contact with a dog on prefrontal brain activity: a controlled trial

Background There is a broad range of known effects of animal contact on human mental and physical health. Neurological correlates of human interaction with animals have been sparsely inves- tigated. We investigated changes in frontal brain activity in the presence of and during con- tact with a dog. Methods Twenty-one healthy individuals each participated in six sessions. In three sessions, partici- pants had contact with a dog, and in three control sessions they interacted with a plush ani- mal. Each session had five two-minute phases with increasing intensity of contact to the dog or plush animal from the first to the fourth phase. We measured oxygenated, deoxygenated, and total hemoglobin and oxygen saturation of the blood in the frontal lobe/frontopolar area with functional near-infrared spectroscopy (SenSmart Model X-100) to assess brain activity. Findings In both conditions, the concentration of oxygenated hemoglobin increased significantly from the first to the fourth phase by 2.78 μmol/l (CI = 2.03-3.53, p < .001). Oxygenated hemoglo- bin concentration was 0.80 μmol/l higher in the dog condition compared to in the control con- dition (CI = 0.27-1.33, p = .004). Deoxygenated-hemoglobin concentration, total hemoglobin concentration, and oxygen saturation showed similar patterns. Conclusion Prefrontal brain activation in healthy subjects increased with the rise in interaction closeness with a dog or a plush animal. Moreover, interaction with a dog stimulated more brain activity compared to the control condition, suggesting that interactions with a dog can activate stron- ger attentional processes and elicit more emotional arousal than interacting with a nonliving stimulus

Agent-based dynamics in disaggregated growth models

URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/bandeau-haut/documents-de-travail/Documents de travail du Centre d'Economie de la Sorbonne 2010.77 - ISSN : 1955-611XThis paper presents an agent-based model of disaggregated economic systems with endogenous growth features named Lagon GeneriC. This model is thought to represent a proof of concept that dynamically complete and highly disaggregated agent-based models allow to model economies as complex dynamical systems. It is used here for "theory generation", investigating the extension to a framework with capital accumulation of Gintis results on the dynamics of general equilibrium.On présente le modèle Lagon generiC : modèle multi-agent pourvu de caractéristiques de croissance endogène. Il s'agit d'un prototype hautement désagrégé et dynamiquement complet qui permet la représentation d'économies comme des systèmes dynamiques complexes. Une application aux résultats de Gintis sur la dynamique des prix est également présentée

Effects of contact with a dog on prefrontal brain activity: A controlled trial

BACKGROUND There is a broad range of known effects of animal contact on human mental and physical health. Neurological correlates of human interaction with animals have been sparsely investigated. We investigated changes in frontal brain activity in the presence of and during contact with a dog. METHODS Twenty-one healthy individuals each participated in six sessions. In three sessions, participants had contact with a dog, and in three control sessions they interacted with a plush animal. Each session had five two-minute phases with increasing intensity of contact to the dog or plush animal from the first to the fourth phase. We measured oxygenated, deoxygenated, and total hemoglobin and oxygen saturation of the blood in the frontal lobe/frontopolar area with functional near-infrared spectroscopy (SenSmart Model X-100) to assess brain activity. FINDINGS In both conditions, the concentration of oxygenated hemoglobin increased significantly from the first to the fourth phase by 2.78 μmol/l (CI = 2.03-3.53, p < .001). Oxygenated hemoglobin concentration was 0.80 μmol/l higher in the dog condition compared to in the control condition (CI = 0.27-1.33, p = .004). Deoxygenated-hemoglobin concentration, total hemoglobin concentration, and oxygen saturation showed similar patterns. CONCLUSION Prefrontal brain activation in healthy subjects increased with the rise in interaction closeness with a dog or a plush animal. Moreover, interaction with a dog stimulated more brain activity compared to the control condition, suggesting that interactions with a dog can activate stronger attentional processes and elicit more emotional arousal than interacting with a nonliving stimulus

Using Practice Facilitation to Increase Rates of Colorectal Cancer Screening in Community Health Centers, North Carolina, 2012–2013: Feasibility, Facilitators, and Barriers

INTRODUCTION: Practice facilitation involves trained individuals working with practice staff to conduct quality improvement activities and support delivery of evidence-based clinical services. We examined the feasibility of using practice facilitation to assist federally qualified health centers (FQHCs) to increase colorectal cancer screening rates in North Carolina. METHODS: The intervention consisted of 12 months of facilitation in 3 FQHCs. We conducted chart audits to obtain data on changes in documented recommendation for colorectal cancer screening and completed screening. Key informant interviews provided qualitative data on barriers to and facilitators of implementing office systems. RESULTS: Overall, the percentage of eligible patients with a documented colorectal cancer screening recommendation increased from 15% to 29% (P < .001). The percentage of patients up to date with colorectal cancer screening rose from 23% to 34% (P = .03). Key informants in all 3 clinics said the implementation support from the practice facilitator was critical for initiating or improving office systems and that modifying the electronic medical record was the biggest challenge and most time-consuming aspect of implementing office systems changes. Other barriers were staff turnover and reluctance on the part of local gastroenterology practices to perform free or low-cost diagnostic colonoscopies for uninsured or underinsured patients. CONCLUSION: Practice facilitation is a feasible, acceptable, and promising approach for supporting universal colorectal cancer screening in FQHCs. A larger-scale study is warranted

Testing the ureilite projectile hypothesis for the El'gygytgyn impact: determination of siderophile element abundances and Os isotope ratios in ICDP drill core samples and melt rocks

The geochemical nature of the impactites from International Continental Scientific Drilling Project-El'gygytgyn lake drill core 1C is compared with that of impact melt rock fragments collected near the western rim of the structure and literature data. Concentrations of major and trace elements, with special focus on siderophile metals Cr, Co, Ni, and the platinum group elements, and isotope ratios of osmium (Os), were determined to test the hypothesis of an ureilite impactor at El'gygytgyn. Least squares mixing calculations suggest that the upper volcanic succession of rhyolites, dacites, and andesites were the main contributors to the polymict impact breccias. Additions of 2-13.5 vol% of basaltic inclusions recovered from drill core intervals between 391.6 and 423.0 mblf can almost entirely account for the compositional differences observed for the bottom of a reworked fallout deposit at 318.9 mblf, a polymict impact breccia at 471.4 mblf, and three impact melt rock fragments. However, the measured Os isotope ratios and slightly elevated PGE content (up to 0.262 ng g(-1) Ir) of certain impactite samples, for which the CI-normalized logarithmic PGE signature displays a relatively flat (i.e., chondritic) pattern, can only be explained by the incorporation of a small meteoritic contribution. This component is also required to explain the exceptionally high siderophile element contents and corresponding Ni/Cr, Ni/Co, and Cr/Co ratios of impact glass spherules and spherule fragments that were recovered from the reworked fallout deposits and from terrace outcrops of the Enmyvaam River approximately 10 km southeast of the crater center. Mixing calculations support the presence of approximately 0.05 wt% and 0.50-18 wt% of ordinary chondrite (possibly type-LL) in several impactites and in the glassy spherules, respectively. The heterogeneous distribution of the meteoritic component provides clues for emplacement mechanisms of the various impactite units

Antiferromagnetic spintronics

Antiferromagnetic materials are magnetic inside, however, the direction of their ordered microscopic moments alternates between individual atomic sites. The resulting zero net magnetic moment makes magnetism in antiferromagnets invisible on the outside. It also implies that if information was stored in antiferromagnetic moments it would be insensitive to disturbing external magnetic fields, and the antiferromagnetic element would not affect magnetically its neighbors no matter how densely the elements were arranged in a device. The intrinsic high frequencies of antiferromagnetic dynamics represent another property that makes antiferromagnets distinct from ferromagnets. The outstanding question is how to efficiently manipulate and detect the magnetic state of an antiferromagnet. In this article we give an overview of recent works addressing this question. We also review studies looking at merits of antiferromagnetic spintronics from a more general perspective of spin-ransport, magnetization dynamics, and materials research, and give a brief outlook of future research and applications of antiferromagnetic spintronics.Comment: 13 pages, 7 figure

Coherent-mode decomposition of partially polarized, partially coherent sources

It is shown that any partially polarized, partially coherent source can be expressed in terms of a suitable superposition of transverse coherent modes with orthogonal polarization states. Such modes are determined through the solution of a system of two coupled integral equations. An example, for which the modal decomposition is obtained in closed form in terms of fully linearly polarized Hermite Gaussian modes, is given